42 results on '"Neumann, Silke"'
Search Results
2. Healthy grocery delivery in the usual care for adults recovering from an acute coronary event: protocol for a three-arm randomised controlled trial.
- Author
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Reynolds AN, Hood F, Wilson R, Ross A, Neumann S, Turner R, Iosua E, Katare R, Shahin A, Kok ZY, Chan H, Coffey S, and Mann J
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- Adult, Humans, Cholesterol, Dietary Fiber, Fats, Unsaturated, Randomized Controlled Trials as Topic, Coronary Disease, Diet, Healthy
- Abstract
Introduction: Coronary heart disease is a major contributor to the global burden of disease. Appropriate nutrition is a cornerstone of the prevention and treatment of coronary heart disease; however, barriers including cost and access to recommended foods limits long-term adherence for many. We are conducting, in adults with coronary heart disease, a randomised controlled trial comparing usual care with two dietary interventions in which usual care is augmented by 12 weeks free delivered groceries., Methods and Analysis: Three hundred adults recovering from an acute coronary event will be recruited from outpatient cardiovascular services in three regions of Aotearoa New Zealand. Participants will be randomly allocated to three arms: usual care (control group), usual care and the free delivery of foods high in dietary fibre or usual care and the free delivery of foods high in unsaturated fats. Interventions duration is 12 weeks, with a further 12 months follow-up. The primary outcome measures are change in low-density lipoprotein (LDL) cholesterol concentration following the intervention, and a cost-effectiveness analysis of healthcare access and social costs in the year after the intervention. A broad range of secondary outcome measures include other blood lipids, anthropometry, glycaemia, inflammatory markers, gut microbiome, dietary biomarkers, food acceptability, dietary change and the facilitators and barriers to dietary change. The trial will determine whether the free provision of groceries known to reduce cardiovascular risk within usual care will be clinically beneficial and justify the cost of doing so. Results may also provide an indication of the relative benefit of foods rich in dietary fibre or unsaturated fats in coronary heart disease management., Ethics and Dissemination: This trial, The Healthy Heart Study, has Health and Disability Ethics Committee approval (20/NTB/121), underwent Māori consultation, and has locality authority to be conducted in Canterbury, Otago and Southland., Trial Registration Number: ACTRN12620000689976, U1111-1250-1499., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2023. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)
- Published
- 2023
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3. The effects of wholegrain processing on appetite: randomised crossover trial in adults with type 2 diabetes.
- Author
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Reynolds AN, Diep Pham HT, Åberg S, Neumann S, and Mann J
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- Adult, Humans, Middle Aged, Aged, Whole Grains, Cross-Over Studies, Energy Intake, Hunger, Appetite, Diabetes Mellitus, Type 2
- Abstract
Aims : Recent observational data indicate higher ultra-processed food intakes are associated with a broad range of adverse health outcomes. Experimental studies on why this might be are lacking. We have considered the effects of wholegrain processing on measures of appetite in free-living adults with type 2 diabetes. Materials and methods : Participants were randomised to two interventions of two-weeks duration, separated by washout. Interventions were nutrient-matched wholegrain foods that differed by the amount of processing. Self-reported hunger and satiety were indicated on visual analogue scales before or after meals for four days at baseline and the end of each intervention. Metabolite markers of appetite were measured pre and post intervention in fasting plasma. Results : 31 adults (63 ± 13 years old, BMI 32.4 ± 7, HbA1c 7.5 ± 3.4% (59 ± 14 mmol mol
-1 )) commenced the trial, 28 (90%) completed both interventions. Wholegrain consumption, as measured by alkylresorcinols, was balanced between interventions. Self-reported pre-meal hunger was consistently lower at breakfast (MD, mean difference 0.49/10 95% CI 0.03 to 0.94), lunch (MD 0.67/10 95% CI 0.09 to 1.25), and dinner (MD -0.71/10 95% CI 0.19 to 1.23) during the intervention of less processed whole grains when compared with pre-intervention measures, however this did not result in a difference between interventions. Change in metabolite markers of appetite did not differ between interventions. Conclusions : A significant difference in hunger or satiety between less and more processed whole grains over intervention periods of two weeks was not detected within the current trial. Further experimental studies are needed to consider the potential effects of food processing on physiological processes such as appetite to provide mechanistic understanding behind observations of highly processed food intakes and adverse health outcomes.- Published
- 2023
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4. Cutting-edge advances in modeling the blood-brain barrier and tools for its reversible permeabilization for enhanced drug delivery into the brain.
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Sharma A, Fernandes DC, Reis RL, Gołubczyk D, Neumann S, Lukomska B, Janowski M, Kortylewski M, Walczak P, Oliveira JM, and Maciaczyk J
- Abstract
The blood-brain barrier (BBB) is a sophisticated structure whose full functionality is required for maintaining the executive functions of the central nervous system (CNS). Tight control of transport across the barrier means that most drugs, particularly large size, which includes powerful biologicals, cannot reach their targets in the brain. Notwithstanding the remarkable advances in characterizing the cellular nature of the BBB and consequences of BBB dysfunction in pathology (brain metastasis, neurological diseases), it remains challenging to deliver drugs to the CNS. Herein, we outline the basic architecture and key molecular constituents of the BBB. In addition, we review the current status of approaches that are being explored to temporarily open the BBB in order to allow accumulation of therapeutics in the CNS. Undoubtedly, the major concern in field is whether it is possible to open the BBB in a meaningful way without causing negative consequences. In this context, we have also listed few other important key considerations that can improve our understanding about the dynamics of the BBB., (© 2023. The Author(s).)
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- 2023
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5. Late-stage MC38 tumours recapitulate features of human colorectal cancer - implications for appropriate timepoint selection in preclinical studies.
- Author
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Shields NJ, Peyroux EM, Ferguson AL, Steain M, Neumann S, and Young SL
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- Humans, Immunotherapy, Flow Cytometry, Colonic Neoplasms, Adenocarcinoma
- Abstract
Anti-tumour T cell responses play a crucial role in controlling the progression of colorectal cancer (CRC), making this disease a promising candidate for immunotherapy. However, responses to immune-targeted therapies are currently limited to subpopulations of patients and specific types of cancer. Clinical studies have therefore focussed on identifying biomarkers that predict immunotherapy responses and elucidating the immunological landscapes of different cancers. Meanwhile, our understanding of how preclinical tumour models resemble human disease has fallen behind, despite their crucial role in immune-targeted drug development. A deeper understanding of these models is therefore needed to improve the development of immunotherapies and the translation of findings made in these systems. MC38 colon adenocarcinoma is a widely used preclinical model, yet how it recapitulates human colorectal cancer remains poorly defined. This study investigated the tumour-T cell immune landscape of MC38 tumours using histology, immunohistochemistry, and flow cytometry. We demonstrate that early-stage tumours exhibit a nascent TME, lacking important immune-resistance mechanisms of clinical interest, while late-stage tumours exhibit a mature TME resembling human tumours, with desmoplasia, T cell exhaustion, and T cell exclusion. Consequently, these findings clarify appropriate timepoint selection in the MC38 model when investigating both immunotherapies and mechanisms that contribute to immunotherapy resistance. Overall, this study provides a valuable resource that will enable appropriate application of the MC38 model and expedite the development and clinical translation of new immunotherapies., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Shields, Peyroux, Ferguson, Steain, Neumann and Young.)
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- 2023
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6. Calpains Released from Necrotic Tumor Cells Enhance Antigen Cross-Presentation to Activate CD8 + T Cells In Vitro.
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Shields NJ, Peyroux EM, Campbell K, Mehta S, Woolley AG, Counoupas C, Neumann S, and Young SL
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- Antigen Presentation, CD8-Positive T-Lymphocytes, Calpain metabolism, Dendritic Cells, Humans, Necrosis metabolism, Cross-Priming, Neoplasms metabolism
- Abstract
The initiation of CD8
+ T cell responses against dead cell-associated Ags is tightly regulated, facilitating adaptive immunity against pathogens and tumors while preventing autoimmunity. It is now well established that dying cells actively regulate the generation of CD8+ T cell responses via the release or exposure of damage-associated molecular patterns. However, it is unclear whether nonproteasomal proteases (activated in stressed and dying cells) can influence the availability of Ags for cross-presentation. Using a mouse model of immunogenic necrosis, we investigated the role of tumor-derived proteases in the priming of CD8+ T cells. We demonstrate that proteases released from necrotic tumor cells can degrade whole-protein Ag, generating proteolytic intermediates that are efficiently cross-presented by dendritic cells and enhance CD8+ T cell cross-priming. We identify a dominant role for calpain proteases, which are activated during necrotic cell death induced by severe heat shock. Mechanistically, proteolytic intermediates generated by tumor-derived proteases associate with necrotic tumor cell debris, which acts as a vehicle for Ag transfer that facilitates highly efficient cross-presentation in dendritic cells. Our results suggest that proteolytic systems activated in Ag donor cells during cell death may influence the availability of antigenic substrates for cross-presentation, thereby regulating the antigenicity of cell death., (Copyright © 2022 by The American Association of Immunologists, Inc.)- Published
- 2022
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7. WNT/β-Catenin-Mediated Resistance to Glucose Deprivation in Glioblastoma Stem-like Cells.
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Yusuf S, Aretz P, Nickel AC, Westhoff P, Sharma A, Qin N, Remke M, Steiger HJ, Hänggi D, Liu H, Liu H, Neumann S, Reifenberger G, and Maciaczyk J
- Abstract
Isocitrate dehydrogenase (IDH)-wildtype glioblastoma is the most common primary malignant brain tumor. It is associated with a particularly poor prognosis, as reflected by an overall median survival of only 15 months in patients who undergo a supramarginal surgical reduction of the tumor mass followed by combined chemoradiotherapy. The highly malignant nature of IDH-wildtype glioblastoma is thought to be driven by glioblastoma stem-like cells (GSCs) that harbor the ability of self-renewal, survival, and adaptability to challenging environmental conditions. The wingless (WNT) signaling pathway is a phylogenetically highly conserved stemness pathway, which promotes metabolic plasticity and adaptation to a nutrient-limited tumor microenvironment. To unravel the reciprocal regulation of the WNT pathway and the nutrient-limited microenvironment, glioblastoma cancer stem-like cells were cultured in a medium with either standard or reduced glucose concentrations for various time points (24, 48, and 72 h). Glucose depletion reduced cell viability and facilitated the survival of a small population of starvation-resistant tumor cells. The surviving cells demonstrated increased clonogenic and invasive properties as well as enhanced chemosensitivity to pharmacological inhibitors of the WNT pathway (LGK974, berberine). Glucose depletion partially led to the upregulation of WNT target genes such as CTNNB1 , ZEB1 , and AXIN2 at the mRNA and corresponding protein levels. LGK974 treatment alone or in combination with glucose depletion also altered the metabolite concentration in intracellular compartments, suggesting WNT-mediated metabolic regulation. Taken together, our findings suggest that WNT-mediated metabolic plasticity modulates the survival of GSCs under nutrient-restricted environmental conditions.
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- 2022
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8. Crosstalk between β-Catenin and CCL2 Drives Migration of Monocytes towards Glioblastoma Cells.
- Author
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Aretz P, Maciaczyk D, Yusuf S, Sorg RV, Hänggi D, Liu H, Liu H, Dakal TC, Sharma A, Bethanabatla R, Neumann S, and Maciaczyk J
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- Cell Line, Tumor, Cell Proliferation, Humans, Leukocytes, Mononuclear metabolism, Monocytes metabolism, Tumor Microenvironment, Wnt Signaling Pathway, Brain Neoplasms metabolism, Chemokine CCL2 genetics, Chemokine CCL2 pharmacology, Glioblastoma genetics, Glioblastoma metabolism, beta Catenin genetics, beta Catenin metabolism
- Abstract
Isocitrate dehydrogenase (IDH)-wildtype glioblastoma (GBM) is a fast growing and highly heterogeneous tumor, often characterized by the presence of glioblastoma stem cells (GSCs). The plasticity of GSCs results in therapy resistance and impairs anti-tumor immune response by influencing immune cells in the tumor microenvironment (TME). Previously, β-catenin was associated with stemness in GBM as well as with immune escape mechanisms. Here, we investigated the effect of β-catenin on attracting monocytes towards GBM cells. In addition, we evaluated whether CCL2 is involved in β-catenin crosstalk between monocytes and tumor cells. Our analysis revealed that shRNA targeting β-catenin in GBMs reduces monocytes attraction and impacts CCL2 secretion. The addition of recombinant CCL2 restores peripheral blood mononuclear cells (PBMC) migration towards medium (TCM) conditioned by shβ-catenin GBM cells. CCL2 knockdown in GBM cells shows similar effects and reduces monocyte migration to a similar extent as β-catenin knockdown. When investigating the effect of CCL2 on β-catenin activity, we found that CCL2 modulates components of the Wnt/β-catenin pathway and alters the clonogenicity of GBM cells. In addition, the pharmacological β-catenin inhibitor MSAB reduces active β-catenin, downregulates the expression of associated genes and alters CCL2 secretion. Taken together, we showed that β-catenin plays an important role in attracting monocytes towards GBM cells in vitro. We hypothesize that the interactions between β-catenin and CCL2 contribute to maintenance of GSCs via modulating immune cell interaction and promoting GBM growth and recurrence.
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- 2022
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9. Obesity Has a Systemic Effect on Immune Cells in Naïve and Cancer-Bearing Mice.
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Neumann S, Campbell K, Woodall MJ, Evans M, Clarkson AN, and Young SL
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- Adaptive Immunity, Animals, Breast Neoplasms immunology, Cell Line, Tumor, Colorectal Neoplasms immunology, Female, Humans, Male, Mice, Myeloid Cells metabolism, Neoplasm Transplantation, Tumor Microenvironment, Breast Neoplasms pathology, Colorectal Neoplasms pathology, Lymphocytes, Tumor-Infiltrating metabolism, Obesity immunology
- Abstract
Obesity is a major risk factor for developing cancer, with obesity-induced immune changes and inflammation in breast (BC) and colorectal cancer (CRC) providing a potential link between the two. This study investigates systemic effects of obesity on adaptive and innate immune cells in healthy and tumour-bearing mice. Immune cells from lean and obese mice were phenotyped prior to implantation of either BC (C57mg and EO771.LMB) or CRC (MC38) cells as tumour models. Tumour growth rate, tumour-infiltrating lymphocytes (TIL) and peripheral blood immune cell populations were compared between obese and lean mice. In vitro studies showed that naïve obese mice had higher levels of myeloid cells in the bone marrow and bone marrow-derived dendritic cells expressed lower levels of activation markers compared to cells from their lean counterparts. In the tumour setting, BC tumours grew faster in obese mice than in lean mice and lower numbers of TILs as well as higher frequency of exhausted T cells were observed. Data from peripheral blood showed lower levels of myeloid cells in tumour-bearing obese mice. This study highlights that systemic changes to the immune system are relevant for tumour burden and provides a potential mechanism behind the effects of obesity on cancer development and progression in patients.
- Published
- 2021
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10. Primary prophylaxis of bacterial infections and Pneumocystis jirovecii pneumonia in patients with hematologic malignancies and solid tumors: 2020 updated guidelines of the Infectious Diseases Working Party of the German Society of Hematology and Medical Oncology (AGIHO/DGHO).
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Classen AY, Henze L, von Lilienfeld-Toal M, Maschmeyer G, Sandherr M, Graeff LD, Alakel N, Christopeit M, Krause SW, Mayer K, Neumann S, Cornely OA, Penack O, Weißinger F, Wolf HH, and Vehreschild JJ
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- Antineoplastic Agents therapeutic use, Drug Resistance, Bacterial, Fluoroquinolones therapeutic use, Germany, Hematologic Neoplasms drug therapy, Hematology, Humans, Medical Oncology, Microbiota drug effects, Pneumonia, Pneumocystis complications, Societies, Medical, Anti-Bacterial Agents therapeutic use, Hematologic Neoplasms complications, Pneumocystis carinii drug effects, Pneumonia, Pneumocystis prevention & control
- Abstract
Hematologic and oncologic patients with chemo- or immunotherapy-related immunosuppression are at substantial risk for bacterial infections and Pneumocystis jirovecii pneumonia (PcP). As bacterial resistances are increasing worldwide and new research reshapes our understanding of the interactions between the human host and bacterial commensals, administration of antibacterial prophylaxis has become a matter of discussion. This guideline constitutes an update of the 2013 published guideline of the Infectious Diseases Working Party (AGIHO) of the German Society for Hematology and Medical Oncology (DGHO). It gives an overview about current strategies for antibacterial prophylaxis in cancer patients while taking into account the impact of antibacterial prophylaxis on the human microbiome and resistance development. Current literature published from January 2012 to August 2020 was searched and evidence-based recommendations were developed by an expert panel. All recommendations were discussed and approved in a consensus conference of the AGIHO prior to publication. As a result, we present a comprehensive update and extension of our guideline for antibacterial and PcP prophylaxis in cancer patients.
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- 2021
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11. Molecular monitoring of glioblastoma's immunogenicity using a combination of Raman spectroscopy and chemometrics.
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Robert C, Tsiampali J, Fraser-Miller SJ, Neumann S, Maciaczyk D, Young SL, Maciaczyk J, and Gordon KC
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- Discriminant Analysis, Humans, Principal Component Analysis, Support Vector Machine, Glioblastoma, Spectrum Analysis, Raman
- Abstract
Raman spectroscopy (RS) has been used as a powerful diagnostic and non-invasive tool in cancer diagnosis as well as in discrimination of cancer and immune cells. In this study RS in combination with chemometrics was applied to cellular Raman spectral data to distinguish the phenotype of T-cells and monocytes after incubation with media conditioned by glioblastoma stem-cells (GSCs) showing different molecular background. For this purpose, genetic modulations of epithelial-to-mesenchymal transition (EMT) process and expression of immunomodulator CD73 were introduced. Principal component analysis of the Raman spectral data showed that T-cells and monocytes incubated with tumour-conditioned media (TCMs) of GSCs with inhibited EMT activator ZEB1 or CD73 formed distinct clusters compared to controls highlighting their differences. Further discriminatory analysis performed using linear discriminant analysis (LDA) and support vector machine classification (SVM), yielded sensitivities and specificities of over 70 and 67% respectively upon validation against an independent test set. Supporting those results, flow cytometric analysis was performed to test the influence of TCMs on cytokine profile of T-cells and monocytes. We found that ZEB1 and CD73 influence T-cell and monocyte phenotype and promote monocyte differentiation into a population of mixed pro- and anti-tumorigenic macrophages (MΦs) and dendritic cells (DCs) respectively. In conclusion, Raman spectroscopy in combination with chemometrics enabled tracking T-cells and monocytes., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier B.V. All rights reserved.)
- Published
- 2021
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12. Enzymatic Activity of CD73 Modulates Invasion of Gliomas via Epithelial-Mesenchymal Transition-Like Reprogramming.
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Tsiampali J, Neumann S, Giesen B, Koch K, Maciaczyk D, Janiak C, Hänggi D, and Maciaczyk J
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Glioblastoma (GBM) is the most aggressive malignant primary brain tumour in adulthood. Despite strong research efforts current treatment options have a limited impact on glioma stem-like cells (GSCs) which contribute to GBM formation, progression and chemoresistance. Invasive growth of GSCs is in part associated with epithelial-mesenchymal-like transition (EMT), a mechanism associated with CD73 in several cancers. Here, we show that CD73 regulates the EMT activator SNAIL1 and further investigate the role of enzymatic and non-enzymatic CD73 activity in GBM progression. Reduction of CD73 protein resulted in significant suppression of GSC viability, proliferation and clonogenicity, whereas CD73 enzymatic activity exhibited negative effects only on GSC invasion involving impaired downstream adenosine (ADO) signalling. Furthermore, application of phosphodiesterase inhibitor pentoxifylline, a potent immunomodulator, effectively inhibited ZEB1 and CD73 expression and significantly decreased viability, clonogenicity, and invasion of GSC in vitro cultures. Given the involvement of adenosine and A
3 adenosine receptor in GSC invasion, we investigated the effect of the pharmacological inhibition of A3 AR on GSC maintenance. Direct A3 AR inhibition promoted apoptotic cell death and impaired the clonogenicity of GSC cultures. Taken together, our data indicate that CD73 is an exciting novel target in GBM therapy. Moreover, pharmacological interference, resulting in disturbed ADO signalling, provides new opportunities to innovate GBM therapy.- Published
- 2020
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13. Whole-Grain Processing and Glycemic Control in Type 2 Diabetes: A Randomized Crossover Trial.
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Åberg S, Mann J, Neumann S, Ross AB, and Reynolds AN
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- Aged, Blood Glucose analysis, Blood Glucose Self-Monitoring, Breakfast, Cross-Over Studies, Diabetes Mellitus, Type 2 blood, Energy Intake physiology, Female, Food Handling, Humans, Male, Meals, Middle Aged, New Zealand, Postprandial Period, Triticum metabolism, Blood Glucose metabolism, Diabetes Mellitus, Type 2 diet therapy, Diabetes Mellitus, Type 2 metabolism, Glycemic Control, Whole Grains metabolism
- Abstract
Objective: To consider the effects of whole-grain processing, specifically milling, on glycemic control in free-living adults with type 2 diabetes., Research Design and Methods: Participants of this crossover trial were randomized to two interventions of 2 weeks, separated by washout. They were advised to replace the grain foods they normally consumed with intervention foods. Intervention foods were nutrient-matched whole-grain products of wheat, oats, and brown rice that differed in their degree of processing. No other lifestyle advice was given. Continuous glucose monitoring systems were worn. Other cardiometabolic risk factors and alkylresorcinols (a biomarker of whole-grain intake) were measured pre- and postintervention., Results: Thirty-one adults with type 2 diabetes (63 ± 13 years old, BMI 32.4 ± 7 kg/m
2 , HbA1c 7.5 ± 3.4% [59 ± 14 mmol/mol]) commenced the trial; 28 (90%) completed both interventions. The increase in alkylresorcinols did not differ between interventions, and there was no difference in reported energy intake. Postprandial responses were 9% (95% CI 3-15) lower following breakfast and 6% (1-10) lower following all meals of less-processed whole grains when compared with finely milled grains. Day-long glycemic variability also was reduced when measured by 24-h SD (-0.16 mmol/L [95% CI -0.25 to -0.06]) and mean amplitude of glycemic excursion (-0.36 [95% CI -0.65 to -0.08]). Mean change in body weight differed by 0.81 kg (95% CI 0.62-1.05) between interventions, increasing during the finely milled intervention and decreasing during the less-processed whole-grain intervention. This was not a mediating factor for the glycemic variables considered., Conclusions: Consuming less-processed whole-grain foods over 2 weeks improved measures of glycemia in free-living adults with type 2 diabetes compared with an equivalent amount of whole-grain foods that were finely milled. Dietary advice should promote the consumption of minimally processed whole grains., (© 2020 by the American Diabetes Association.)- Published
- 2020
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14. The Effects of Obesity on Anti-Cancer Immunity and Cancer Immunotherapy.
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Woodall MJ, Neumann S, Campbell K, Pattison ST, and Young SL
- Abstract
Cancer is one of the leading causes of morbidity and mortality worldwide. Traditional treatments include surgery, chemotherapy and radiation therapy, and more recently targeted therapies including immunotherapy are becoming routine care for some cancers. Immunotherapy aims to upregulate the patient's own immune system, enabling it to destroy cancerous cells. Obesity is a metabolic disorder characterized by significant weight that is an important contributor to many different diseases, including cancers. Obesity impacts the immune system and causes, among other things, a state of chronic low-grade inflammation. This is hypothesized to impact the efficacy of the immunotherapies. This review discusses the effects of obesity on the immune system and cancer immunotherapy, including the current evidence on the effect of obesity on immune checkpoint blockade, something which currently published reviews on this topic have not delved into. Data from several studies show that even though obesity causes a state of chronic low-grade inflammation with reductions in effector immune populations, it has a beneficial effect on patient survival following anti-PD-1/PD-L1 and anti-CTLA-4 treatment. However, research in this field is just emerging and further work is needed to expand our understanding of which cancer patients are likely to benefit from immunotherapy.
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- 2020
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15. The Delta-Subunit Selective GABA A Receptor Modulator, DS2, Improves Stroke Recovery via an Anti-inflammatory Mechanism.
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Neumann S, Boothman-Burrell L, Gowing EK, Jacobsen TA, Ahring PK, Young SL, Sandager-Nielsen K, and Clarkson AN
- Abstract
Inflammatory processes are known to contribute to tissue damage in the central nervous system (CNS) across a broad range of neurological conditions, including stroke. Gamma amino butyric acid (GABA), the main inhibitory neurotransmitter in the CNS, has been implicated in modulating peripheral immune responses by acting on GABA
A receptors on antigen-presenting cells and lymphocytes. Here, we investigated the effects and mechanism of action of the delta-selective compound, DS2, to improve stroke recovery and modulate inflammation. We report a decrease in nuclear factor (NF)-κB activation in innate immune cells over a concentration range in vitro . Following a photochemically induced motor cortex stroke, treatment with DS2 at 0.1 mg/kg from 1 h post-stroke significantly decreased circulating tumor necrosis factor (TNF)-α, interleukin (IL)-17, and IL-6 levels, reduced infarct size and improved motor function in mice. Free brain concentrations of DS2 were found to be lower than needed for robust modulation of central GABAA receptors and were not affected by the presence and absence of elacridar, an inhibitor of both P-glycoprotein and breast cancer resistance protein (BCRP). Finally, as DS2 appears to dampen peripheral immune activation and only shows limited brain exposure, we assessed the role of DS2 to promote functional recovery after stroke when administered from 3-days after the stroke. Treatment with DS2 from 3-days post-stroke improved motor function on the grid-walking, but not on the cylinder task. These data highlight the need to further develop subunit-selective compounds to better understand change in GABA receptor signaling pathways both centrally and peripherally. Importantly, we show that GABA compounds such as DS2 that only shows limited brain exposure can still afford significant protection and promote functional recovery most likely via modulation of peripheral immune cells and could be given as an adjunct treatment., (Copyright © 2019 Neumann, Boothman-Burrell, Gowing, Jacobsen, Ahring, Young, Sandager-Nielsen and Clarkson.)- Published
- 2019
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16. The flavonoid, 2'-methoxy-6-methylflavone, affords neuroprotection following focal cerebral ischaemia.
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Clarkson AN, Boothman-Burrell L, Dósa Z, Nagaraja RY, Jin L, Parker K, van Nieuwenhuijzen PS, Neumann S, Gowing EK, Gavande N, Ahring PK, Holm MM, Hanrahan JR, Nicolazzo JA, Jensen K, and Chebib M
- Subjects
- Animals, Brain metabolism, Disease Models, Animal, Flavones pharmacokinetics, Male, Mice, Mice, Inbred BALB C, Mice, Knockout, Receptors, GABA-A drug effects, Receptors, GABA-A genetics, Receptors, GABA-A physiology, Stroke drug therapy, Synaptic Potentials drug effects, Synaptic Potentials physiology, Brain Ischemia drug therapy, Flavones administration & dosage, GABA Modulators administration & dosage, Neuroprotective Agents administration & dosage
- Abstract
Tonic inhibitory currents, mediated by extrasynaptic GABA
A receptors, are elevated at a delay following stroke. Flavonoids minimise the extent of cellular damage following stroke, but little is known about their mode of action. We demonstrate that the flavonoid, 2'-methoxy-6-methylflavone (0.1-10 µM; 2'MeO6MF), increases GABAA receptor tonic currents presumably via δ-containing GABAA receptors. Treatment with 2'MeO6MF 1-6 h post focal ischaemia dose dependently decreases infarct volume and improves functional recovery. The effect of 2'MeO6MF was attenuated in δ-/- mice, indicating that the effects of the flavonoid were mediated via δ-containing GABAA receptors. Further, as flavonoids have been shown to have multiple modes of action, we investigated the anti-inflammatory effects of 2'MeO6MF. Using a macrophage cell line, we show that 2'MeO6MF can dampen an LPS-induced elevation in NFkB activity. Assessment of vehicle-treated stroke animals revealed a significant increase in circulating IL1β, TNFα and IFγ levels. Treatment with 2'MeO6MF dampened the stroke-induced increase in circulating cytokines, which was blocked in the presence of the pan-AKT inhibitor, GSK690693. These studies support the hypothesis that compounds that potentiate tonic inhibition via δ-containing GABAA receptors soon after stroke can afford neuroprotection.- Published
- 2019
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17. Effects of an Exergame Software for Older Adults on Fitness, Activities of Daily Living Performance, and Quality of Life.
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Neumann S, Meidert U, Barberà-Guillem R, Poveda-Puente R, and Becker H
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- Aged, Aged, 80 and over, Exercise Therapy methods, Exercise Therapy statistics & numerical data, Female, Humans, Male, Middle Aged, Physical Fitness physiology, Spain, Statistics, Nonparametric, Switzerland, Video Games psychology, Activities of Daily Living psychology, Exercise Therapy standards, Physical Fitness psychology, Quality of Life psychology, Video Games statistics & numerical data
- Abstract
Background: As people become older, the biological process of aging leads to a decline in functional capabilities, which entails difficulties in the performance of daily tasks. Within the "Active and Assisted Living Joint Programme" a consortium from Spain, Germany, and Switzerland developed an interactive Exergame software for older adults to maintain their physical abilities and independence within the daily tasks., Subjects and Methods: An interventional study was conducted to validate the software. For 3 months, Swiss and Spanish seniors used the system at least three times a week for minimum half an hour in their homes. The physical condition in terms of maintaining or increasing strength, balance, safety, and mobility of the seniors was assessed by using the Berg Balance Scale and the Senior Fitness Test. In addition, the effect on independence within the activities of daily living was assessed by using the Canadian Occupational Performance Measure, the Performance Quality Rating Scale, and the Iconographical Falls Efficacy Scale. We used the EQ 5D to evaluate the "quality of life.", Results: Twenty-nine participants (male; n = 14; female; n = 15) completed the study. Scores of endurance (2 minutes step test; P = 0.01, η
2 = 0.3) increased significantly. Moderate effect sizes in quality of life (r = 0.3), lower body strength (η2 = 0.08), and large effect sizes in endurance (η2 = 0.3) were detected. A small effect was evaluated within the gait speed (r = 0.2), mobility in the lower body (r = 0.2), and the balance capabilities (r = 0.2)., Conclusion: The results of this study lead us to the conclusion that physical training with activity-focused exergames that are related to the everyday tasks of older adults could help to maintain and improve the individual fitness status.- Published
- 2018
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18. Acute or Delayed Systemic Administration of Human Amnion Epithelial Cells Improves Outcomes in Experimental Stroke.
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Evans MA, Lim R, Kim HA, Chu HX, Gardiner-Mann CV, Taylor KWE, Chan CT, Brait VH, Lee S, Dinh QN, Vinh A, Phan TG, Srikanth VK, Ma H, Arumugam TV, Fann DY, Poh L, Hunt CPJ, Pouton CW, Haynes JM, Selemidis S, Kwan W, Teo L, Bourne JA, Neumann S, Young S, Gowing EK, Drummond GR, Clarkson AN, Wallace EM, Sobey CG, and Broughton BRS
- Subjects
- Animals, Callithrix, Disease Models, Animal, Female, Heterografts, Humans, Male, Mice, Stroke metabolism, Stroke pathology, Amnion transplantation, Epithelial Cells transplantation, Neuroprotection, Stroke therapy
- Abstract
Background and Purpose: Human amnion epithelial cells (hAECs) are nonimmunogenic, nontumorigenic, anti-inflammatory cells normally discarded with placental tissue. We reasoned that their profile of biological features, wide availability, and the lack of ethical barriers to their use could make these cells useful as a therapy in ischemic stroke., Methods: We tested the efficacy of acute (1.5 hours) or delayed (1-3 days) poststroke intravenous injection of hAECs in 4 established animal models of cerebral ischemia. Animals included young (7-14 weeks) and aged mice (20-22 months) of both sexes, as well as adult marmosets of either sex., Results: We found that hAECs administered 1.5 hours after stroke in mice migrated to the ischemic brain via a CXC chemokine receptor type 4-dependent mechanism and reduced brain inflammation, infarct development, and functional deficits. Furthermore, if hAECs administration was delayed until 1 or 3 days poststroke, long-term functional recovery was still augmented in young and aged mice of both sexes. We also showed proof-of-principle evidence in marmosets that acute intravenous injection of hAECs prevented infarct development from day 1 to day 10 after stroke., Conclusions: Systemic poststroke administration of hAECs elicits marked neuroprotection and facilitates mechanisms of repair and recovery., (© 2018 American Heart Association, Inc.)
- Published
- 2018
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19. Combining dendritic cells and B cells for presentation of oxidised tumour antigens to CD8 + T cells.
- Author
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Grant ML, Shields N, Neumann S, Kramer K, Bonato A, Jackson C, Baird MA, and Young SL
- Abstract
The dendritic cell (DC) is the foremost antigen-presenting cell (APC) for ex vivo expansion of tumour-specific patient T cells. Despite marked responses in some patients following reinfusion of DC-activated autologous or HLA-matched donor T cells, overall response rates remain modest in solid tumours. Furthermore, most studies aim to generate immune responses against defined tumour-associated antigens (TAA), however, meta-analysis reveals that those approaches have less clinical success than those using whole tumour cells or their components. Tumour lysate (TL) is used as a source of tumour antigen in clinical trials and potentially represents the full range of TAAs in an undefined state. Little is known about how different APCs cooperate to present TL antigens. We examined the effect of oxidised whole-cell lysate (ox-L) versus soluble fraction freeze-thaw lysate (s-L) on bone marrow-derived DCs and macrophages, and magnetic bead-isolated splenic B cells. The APCs were used individually, or in combination, to prime T cells. CD8
+ T cells produced interferon (IFN)-γ in response to both s-L and ox-L, but only proliferated in response to ox-L. IFN-γ production and proliferation was enhanced by priming with the DC+B cell combination. Compared to DC alone, a trend toward greater interleukin (IL)-12 production was observed when DC+B cell were loaded with s-L and ox-L antigens. CD8+ T-cell specific lysis in vivo was greatest in ox-L-primed groups and DC+B cell priming significantly increased in vivo cytotoxicity compared to DC alone. These improved T-cell responses with two APCs and stressed cell lysate has implications for APC-based adoptive cell therapies., Competing Interests: The authors declare no conflict of interest.- Published
- 2017
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20. Epidemiology of invasive aspergillosis and azole resistance in patients with acute leukaemia: the SEPIA Study.
- Author
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Koehler P, Hamprecht A, Bader O, Bekeredjian-Ding I, Buchheidt D, Doelken G, Elias J, Haase G, Hahn-Ast C, Karthaus M, Kekulé A, Keller P, Kiehl M, Krause SW, Krämer C, Neumann S, Rohde H, La Rosée P, Ruhnke M, Schafhausen P, Schalk E, Schulz K, Schwartz S, Silling G, Staib P, Ullmann A, Vergoulidou M, Weber T, Cornely OA, and Vehreschild MJ
- Subjects
- Adolescent, Adult, Aged, Aged, 80 and over, Animals, Aspergillus isolation & purification, Female, Germany epidemiology, Humans, Incidence, Invasive Pulmonary Aspergillosis microbiology, Male, Middle Aged, Prospective Studies, Young Adult, Antifungal Agents pharmacology, Aspergillus drug effects, Azoles pharmacology, Drug Resistance, Fungal, Invasive Pulmonary Aspergillosis epidemiology, Leukemia, Myeloid, Acute complications, Precursor Cell Lymphoblastic Leukemia-Lymphoma complications
- Abstract
Invasive aspergillosis (IA) is a serious hazard to high-risk haematological patients. There are increasing reports of azole-resistant Aspergillus spp. This study assessed the epidemiology of IA and azole-resistant Aspergillus spp. in patients with acute leukaemia in Germany. A prospective multicentre cohort study was performed in German haematology/oncology centres. The incidence of probable and proven aspergillosis according to the revised EORTC/MSG criteria was assessed for all patients with acute leukaemia [acute myeloid leukaemia (AML) and acute lymphoblastic leukaemia (ALL)]. Cases were documented into a web-based case report form, and centres provided data on standards regarding prophylactic and diagnostic measures. Clinical isolates were screened centrally for azole resistance and, if applicable, underlying resistance mechanisms were analysed. Between September 2011 and December 2013, 179 cases of IA [6 proven (3.4%) and 173 probable (96.6%)] were diagnosed in 3067 patients with acute leukaemia. The incidence of IA was 6.4% among 2440 AML patients and 3.8% among 627 ALL patients. Mortality at Day 84 was 33.8% (49/145) and attributable mortality was 26.9% (39/145). At Day 84, 53 patients (29.6%) showed a complete response, 25 (14.0%) a partial response and 17 (9.5%) a deterioration or failure. A total of 77 clinical Aspergillus fumigatus isolates were collected during the study period. Two episodes of azole-resistant IA (1.1%) were caused by a TR/L98H mutation in the cyp51A gene. With only two cases of IA due to azole-resistant A. fumigatus, a change of antifungal treatment practices in Germany does not appear warranted currently., (Copyright © 2016 Elsevier B.V. and International Society of Chemotherapy. All rights reserved.)
- Published
- 2017
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21. Improved Antitumor Activity of a Therapeutic Melanoma Vaccine through the Use of the Dual COX-2/5-LO Inhibitor Licofelone.
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Neumann S, Shirley SA, Kemp RA, and Hook SM
- Abstract
Immune-suppressive cell populations impair antitumor immunity and can contribute to the failure of immune therapeutic approaches. We hypothesized that the non-steroidal anti-inflammatory drug licofelone, a dual cyclooxygenase-2/5-LO inhibitor, would improve therapeutic melanoma vaccination by reducing immune-suppressive cell populations. Therefore, licofelone was administered after tumor implantation, either alone or in combination with a peptide vaccine containing a long tyrosinase-related protein 2-peptide and the adjuvant α-galactosylceramide, all formulated into cationic liposomes. Mice immunized with the long-peptide vaccine and licofelone showed delayed tumor growth compared to mice given the vaccine alone. This protection was associated with a lower frequency of immature myeloid cells (IMCs) in the bone marrow (BM) and spleen of tumor-inoculated mice. When investigating the effect of licofelone on IMCs in vitro , we found that the prostaglandin E
2 -induced generation of IMCs was decreased in the presence of licofelone. Furthermore, pre-incubation of BM cells differentiated under IMC-inducing conditions with licofelone reduced the secretion of cytokines interleukin (IL)-10 and -6 upon lipopolysaccharides (LPS) stimulation as compared to untreated cells. Interestingly, licofelone increased IL-6 and IL-10 secretion when administered after the LPS stimulus, demonstrating an environment-dependent effect of licofelone. Our findings support the use of licofelone to reduce tumor-promoting cell populations.- Published
- 2016
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22. Infectious diseases in allogeneic haematopoietic stem cell transplantation: prevention and prophylaxis strategy guidelines 2016.
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Ullmann AJ, Schmidt-Hieber M, Bertz H, Heinz WJ, Kiehl M, Krüger W, Mousset S, Neuburger S, Neumann S, Penack O, Silling G, Vehreschild JJ, Einsele H, and Maschmeyer G
- Subjects
- Anti-Infective Agents therapeutic use, Bacterial Infections etiology, Germany, Hematology organization & administration, Hematopoietic Stem Cell Transplantation adverse effects, Humans, Medical Oncology organization & administration, Mycoses etiology, Parasitic Diseases etiology, Practice Guidelines as Topic, Societies, Medical, Transplantation, Homologous, Vaccination methods, Virus Diseases etiology, Bacterial Infections prevention & control, Hematopoietic Stem Cell Transplantation methods, Mycoses prevention & control, Parasitic Diseases prevention & control, Virus Diseases prevention & control
- Abstract
Infectious complications after allogeneic haematopoietic stem cell transplantation (allo-HCT) remain a clinical challenge. This is a guideline provided by the AGIHO (Infectious Diseases Working Group) of the DGHO (German Society for Hematology and Medical Oncology). A core group of experts prepared a preliminary guideline, which was discussed, reviewed, and approved by the entire working group. The guideline provides clinical recommendations for the preventive management including prophylactic treatment of viral, bacterial, parasitic, and fungal diseases. The guideline focuses on antimicrobial agents but includes recommendations on the use of vaccinations. This is the updated version of the AGHIO guideline in the field of allogeneic haematopoietic stem cell transplantation utilizing methods according to evidence-based medicine criteria.
- Published
- 2016
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23. Three-Year Follow-Up of a Randomized Phase II Trial on Refinement of Early-Stage NSCLC Adjuvant Chemotherapy with Cisplatin and Pemetrexed versus Cisplatin and Vinorelbine (the TREAT Study).
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Kreuter M, Vansteenkiste J, Fischer JR, Eberhardt WE, Zabeck H, Kollmeier J, Serke M, Frickhofen N, Reck M, Engel-Riedel W, Neumann S, Thomeer M, Schumann C, De Leyn P, Graeter T, Stamatis G, Griesinger F, and Thomas M
- Subjects
- Adenocarcinoma secondary, Adult, Aged, Carcinoma, Large Cell secondary, Carcinoma, Non-Small-Cell Lung secondary, Carcinoma, Squamous Cell secondary, Chemotherapy, Adjuvant, Cisplatin administration & dosage, Female, Follow-Up Studies, Humans, Lung Neoplasms pathology, Lymphatic Metastasis, Male, Middle Aged, Neoplasm Invasiveness, Neoplasm Recurrence, Local drug therapy, Neoplasm Staging, Pemetrexed administration & dosage, Prognosis, Prospective Studies, Survival Rate, Time Factors, Vinblastine administration & dosage, Vinblastine analogs & derivatives, Vinorelbine, Adenocarcinoma drug therapy, Antineoplastic Combined Chemotherapy Protocols therapeutic use, Carcinoma, Large Cell drug therapy, Carcinoma, Non-Small-Cell Lung drug therapy, Carcinoma, Squamous Cell drug therapy, Lung Neoplasms drug therapy, Neoplasm Recurrence, Local pathology
- Abstract
Introduction: Adjuvant chemotherapy in non-small cell lung cancer (NSCLC) improves survival but is associated with significant toxicity. The Randomized Phase II Trial on Refinement of Early-Stage NSCLC Adjuvant Chemotherapy with Cisplatin and Pemetrexed versus Cisplatin and Vinorelbine (TREAT study) was designed to test the hypothesis that a protocol with reduced toxicity might improve feasibility of postoperative delivery of adjuvant chemotherapy drugs to patients with NSCLC, thereby improving compliance and, potentially, survival., Methods: Two adjuvant regimens were evaluated for feasibility in 132 patients with NSCLC: the standard regimen of cisplatin and vinorelbine (CVb) (cisplatin 50 mg/m(2) on day 1 and day 8 and vinorelbine 25 mg/m(2) on days 1, 8, 15, and 22 every 4 weeks) and a regimen consisting of cisplatin and pemetrexed (CPx) (cisplatin 75 mg/m(2) and pemetrexed 500 mg/m(2) on day 1 every 3 weeks). The primary end-point analysis showing that CPx is safe and feasible with dose delivery superior to that of CVb has already been published. Here we report the 3-year follow-up results of the secondary efficacy end points-overall, relapse-free, distant metastasis-free, and local relapse-free survival-also with regard to histologic diagnosis., Results: After a median of 39 months, no significant differences in any of the outcome parameters between CVb and CPx were observed. Also, histologic diagnosis and tumor size in stage IB did not influence survival in the CPx-treated patients. Yet, Cox regression analyses showed that overall survival at 3 years was significantly correlated with feasibility and the occurrence of dose-limiting toxicity., Conclusions: Although adjuvant chemotherapy with CPx is safe and characterized by less toxicity and better dose delivery than CVb, overall survival was not influenced by treatment arm in the context of this phase II trial., (Copyright © 2015 International Association for the Study of Lung Cancer. Published by Elsevier Inc. All rights reserved.)
- Published
- 2016
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24. Innate Immunity and Inflammation Post-Stroke: An α7-Nicotinic Agonist Perspective.
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Neumann S, Shields NJ, Balle T, Chebib M, and Clarkson AN
- Subjects
- Animals, Humans, Inflammation drug therapy, Inflammation pathology, Myeloid Cells drug effects, Myeloid Cells immunology, Myeloid Cells pathology, Stroke drug therapy, Stroke pathology, alpha7 Nicotinic Acetylcholine Receptor agonists, Immunity, Innate drug effects, Inflammation etiology, Inflammation immunology, Stroke complications, Stroke immunology, alpha7 Nicotinic Acetylcholine Receptor immunology
- Abstract
Stroke is one of the leading causes of death and long-term disability, with limited treatment options available. Inflammation contributes to damage tissue in the central nervous system across a broad range of neuropathologies, including Alzheimer's disease, pain, Schizophrenia, and stroke. While the immune system plays an important role in contributing to brain damage produced by ischemia, the damaged brain, in turn, can exert a powerful immune-suppressive effect that promotes infections and threatens the survival of stroke patients. Recently the cholinergic anti-inflammatory pathway, in particular its modulation using α7-nicotinic acetylcholine receptor (α7-nAChR) ligands, has shown potential as a strategy to dampen the inflammatory response and facilitate functional recovery in stroke patients. Here we discuss the current literature on stroke-induced inflammation and the effects of α7-nAChR modulators on innate immune cells.
- Published
- 2015
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25. Synthetic TRP2 long-peptide and α-galactosylceramide formulated into cationic liposomes elicit CD8+ T-cell responses and prevent tumour progression.
- Author
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Neumann S, Young K, Compton B, Anderson R, Painter G, and Hook S
- Subjects
- Administration, Intravenous, Animals, Cancer Vaccines administration & dosage, Galactosylceramides administration & dosage, Immunologic Factors administration & dosage, Injections, Subcutaneous, Interferon-gamma metabolism, Intramolecular Oxidoreductases administration & dosage, Liposomes administration & dosage, Melanoma immunology, Mice, Inbred C57BL, Survival Analysis, T-Lymphocytes, Cytotoxic immunology, Treatment Outcome, CD8-Positive T-Lymphocytes immunology, Cancer Vaccines immunology, Galactosylceramides metabolism, Immunologic Factors metabolism, Intramolecular Oxidoreductases immunology, Liposomes metabolism, Melanoma therapy
- Abstract
The lipid antigen α-galactosylceramide (α-GalCer) is a potent activator of invariant natural killer T-cells (iNKT cells) and can stimulate cytotoxic and anti-tumour immune responses. However optimal responses appear to be induced by α-GalCer when cell-based vaccines are delivered intravenously. Here we investigated if co-delivery of protein and peptide antigens along with α-GalCer in a liposomal formulation could stimulate therapeutic anti-tumour immune responses. Cationic liposomes were inherently immune-stimulatory and induced cytotoxic immune responses when delivered both by intravenous and subcutaneous injection. However, only vaccine delivered intravenously stimulated therapeutic anti-tumour immune responses to a peptide antigen. Surface modification with polyethylene glycol (PEG) did not improve immune responses to either intravenously or subcutaneously delivered vaccines. Immune responses to short and long peptide sequences (CD8 and CD4 epitopes) of the self-antigen tyrosinase-related protein 2 (TRP2) as a vaccine antigen, co-delivered with α-GalCer in either cationic liposomes or PBS were further examined. Enhanced production of IFN-γ, increased cytotoxic T-cell responses and tumour survival were observed when a long TRP2-peptide was delivered with α-GalCer in cationic liposomes., (Copyright © 2015 Elsevier Ltd. All rights reserved.)
- Published
- 2015
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26. Antiviral prophylaxis in patients with solid tumours and haematological malignancies--update of the Guidelines of the Infectious Diseases Working Party (AGIHO) of the German Society for Hematology and Medical Oncology (DGHO).
- Author
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Sandherr M, Hentrich M, von Lilienfeld-Toal M, Massenkeil G, Neumann S, Penack O, Biehl L, and Cornely OA
- Subjects
- Acute Disease, Antineoplastic Agents therapeutic use, Autografts, Female, Germany, Hematology, Humans, Male, Medical Oncology, Practice Guidelines as Topic, Societies, Medical, Stem Cell Transplantation, Antiviral Agents therapeutic use, Breast Neoplasms therapy, Leukemia therapy, Virus Diseases prevention & control
- Abstract
Reactivation of viral infections is common in patients with solid tumour or haematological malignancy. Incidence and severity depend on the extent of cellular immunosuppression. Antiviral prophylaxis may be effective to prevent viral reactivation. In 2006, the Infectious Diseases Working Party of German Society for Hematology and Medical Oncology (DGHO) published guidelines for antiviral prophylaxis in these patient populations. Here, we present an update of these guidelines for patients with solid and haematological malignancies undergoing antineoplastic treatment but not allogeneic stem cell transplantation. Relevant literature for reactivation of different viruses (herpes simplex virus (HSV), varicella zoster virus (VZV), hepatitis B virus (HBV) and respiratory viruses) is discussed to provide evidence-based recommendations for clinicians taking care of this patient population. We recommend a risk-adapted approach with (val)acyclovir against HSV and VZV in patients treated with alemtuzumab, bortezomib or purine analogues. Seasonal vaccination against influenza is recommended for all patients with solid or haematological malignancies regardless of antineoplastic therapy. Hepatitis B screening is recommended in lymphoproliferative disorders, acute leukaemia, and breast cancer, and during treatment with monoclonal anti-B-cell antibodies, anthracyclines, steroids and in autologous stem cell transplantation. In those with a history of hepatitis B prophylactic lamivudine, entecavir or nucleotide analogues as adefovir are recommended to prevent reactivation.
- Published
- 2015
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27. Example of the application of the PERSONA methodology in the definition of needs and requirements for the WeTakeCare system.
- Author
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Barbera-Guillem R, Poveda-Puente R, Neumann S, Becker H, Ramírez M, Wienholtz A, and Schaedler I
- Subjects
- Activities of Daily Living psychology, Aged psychology, Aged, 80 and over, Female, Geriatric Assessment methods, Humans, Male, Middle Aged, Needs Assessment, Self-Help Devices psychology
- Abstract
In user-centred design and marketing, personas are fictional characters created to represent the different user types that might use a site, brand, or product in a similar way [1]. As in other projects, the main application and use value of the persona approach in WeTakeCare project has been to depict and thus make "vivid" the characters and the milieus created and selected. It has helped to better understand and communicate the differences among the potential users. It has also helped to understand the heterogeneity and diversity of the users' lives and to focus on how to meet their actual needs [2].
- Published
- 2015
28. Universal response-adaptation relation in bacterial chemotaxis.
- Author
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Krembel AK, Neumann S, and Sourjik V
- Subjects
- Bacterial Proteins metabolism, Adaptation, Physiological physiology, Chemotaxis physiology, Escherichia coli metabolism, Escherichia coli physiology
- Abstract
The bacterial strategy of chemotaxis relies on temporal comparisons of chemical concentrations, where the probability of maintaining the current direction of swimming is modulated by changes in stimulation experienced during the recent past. A short-term memory required for such comparisons is provided by the adaptation system, which operates through the activity-dependent methylation of chemotaxis receptors. Previous theoretical studies have suggested that efficient navigation in gradients requires a well-defined adaptation rate, because the memory time scale needs to match the duration of straight runs made by bacteria. Here we demonstrate that the chemotaxis pathway of Escherichia coli does indeed exhibit a universal relation between the response magnitude and adaptation time which does not depend on the type of chemical ligand. Our results suggest that this alignment of adaptation rates for different ligands is achieved through cooperative interactions among chemoreceptors rather than through fine-tuning of methylation rates for individual receptors. This observation illustrates a yet-unrecognized function of receptor clustering in bacterial chemotaxis., (Copyright © 2015, American Society for Microbiology. All Rights Reserved.)
- Published
- 2015
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29. Predicting chemical environments of bacteria from receptor signaling.
- Author
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Clausznitzer D, Micali G, Neumann S, Sourjik V, and Endres RG
- Subjects
- Computer Simulation, Information Theory, Models, Chemical, Cellular Microenvironment physiology, Chemotaxis physiology, Computational Biology methods, Escherichia coli physiology, Models, Biological
- Abstract
Sensory systems have evolved to respond to input stimuli of certain statistical properties, and to reliably transmit this information through biochemical pathways. Hence, for an experimentally well-characterized sensory system, one ought to be able to extract valuable information about the statistics of the stimuli. Based on dose-response curves from in vivo fluorescence resonance energy transfer (FRET) experiments of the bacterial chemotaxis sensory system, we predict the chemical gradients chemotactic Escherichia coli cells typically encounter in their natural environment. To predict average gradients cells experience, we revaluate the phenomenological Weber's law and its generalizations to the Weber-Fechner law and fold-change detection. To obtain full distributions of gradients we use information theory and simulations, considering limitations of information transmission from both cell-external and internal noise. We identify broad distributions of exponential gradients, which lead to log-normal stimuli and maximal drift velocity. Our results thus provide a first step towards deciphering the chemical nature of complex, experimentally inaccessible cellular microenvironments, such as the human intestine.
- Published
- 2014
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30. Primary prophylaxis of invasive fungal infections in patients with haematologic malignancies. 2014 update of the recommendations of the Infectious Diseases Working Party of the German Society for Haematology and Oncology.
- Author
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Tacke D, Buchheidt D, Karthaus M, Krause SW, Maschmeyer G, Neumann S, Ostermann H, Penack O, Rieger C, Ruhnke M, Sandherr M, Schweer KE, Ullmann AJ, and Cornely OA
- Subjects
- Adult, Azoles therapeutic use, Germany, Humans, Immunocompromised Host, Opportunistic Infections prevention & control, Primary Prevention methods, Societies, Medical standards, Antifungal Agents therapeutic use, Chemoprevention methods, Chemoprevention standards, Hematologic Neoplasms drug therapy, Mycoses prevention & control, Practice Guidelines as Topic, Primary Prevention standards
- Abstract
Invasive fungal infections cause substantial morbidity and mortality in immunocompromised patients, particularly in those with haematological malignancies and recipients of allogeneic haematopoietic stem cell transplantation. Difficulties in diagnosing invasive fungal infections and subsequent delays in treatment initiation lead to unfavourable outcomes and emphasise the importance of prophylaxis. Since the recommendations of the Infectious Diseases Working Party of the German Society for Haematology and Oncology in 2009, results of 14 additional clinical studies have been published comprising 2,899 patients and initiating this update. Key recommendations for adult patients are as follows: Posaconazole remains the drug of choice during remission-induction chemotherapy in acute myeloid leukaemia, myelodysplastic syndrome and allogeneic haematopoietic stem cell transplantation with graft versus host disease (AI). In the pre-engraftment period of allogeneic transplantation, several antifungals are appropriate and can be recommended with equal strength: voriconazole (BI), micafungin (BI), fluconazole (BI) and posaconazole (BII). There is poor evidence regarding antifungal prophylaxis in the post-engraftment period of allogeneic haematopoietic stem cell transplantation if no steroids for treatment of graft versus host disease are required. Aerosolised liposomal amphotericin B inhalation in conjunction with fluconazole can be used in patients with prolonged neutropenia (BII).
- Published
- 2014
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31. Activation of the NLRP3 inflammasome is not a feature of all particulate vaccine adjuvants.
- Author
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Neumann S, Burkert K, Kemp R, Rades T, Rod Dunbar P, and Hook S
- Subjects
- Alum Compounds pharmacology, Animals, Cathepsin B immunology, Chitosan pharmacology, Female, Freund's Adjuvant pharmacology, Humans, Interleukin-1beta immunology, Male, Mice, NLR Family, Pyrin Domain-Containing 3 Protein, Nanoparticles, Adjuvants, Immunologic pharmacology, Carrier Proteins immunology, Inflammasomes immunology
- Abstract
Particulate vaccine formulations, designed to improve the delivery of antigens to antigen-presenting cells (APCs) and to stimulate an immune response, have been shown to activate the NLRP3 inflammasome. This leads to the processing and secretion of interleukin (IL)-1β, which supports the recruitment of pro-inflammatory immune cells into the tissue and can therefore be beneficial for vaccine potency. Recent work suggested that this may be a common mechanism of action for all particulate formulations. The aim of this study was to investigate whether the activation of the NLRP3 inflammasome was common to many delivery systems. We prepared polymer-based chitosan nanoparticles (CNPs), lipid-based cubosomes, a water in oil emulsion of incomplete Freund's adjuvant (IFA) and alum formulations and examined inflammasome activation in vitro using murine bone-marrow-derived dendritic cells and human peripheral blood mononuclear cells and in vivo in mice. The formulations differed in their morphology, size and zeta-potential. Only the positively charged particles (CNPs and alum) were able to activate the inflammasome and increase the secretion of IL-1β. A decrease in the activation of the inflammasome with these particulates was observed when cathepsin B-mediated effects were blocked, implying a role of lysosomal rupture in the activation process. These findings demonstrate a role for the surface charge of particulates in the activation of the NLRP3 inflammasome, which should be considered when designing a novel vaccine formulation.
- Published
- 2014
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32. Exponential signaling gain at the receptor level enhances signal-to-noise ratio in bacterial chemotaxis.
- Author
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Neumann S, Løvdok L, Bentele K, Meisig J, Ullner E, Paldy FS, Sourjik V, and Kollmann M
- Subjects
- Algorithms, Escherichia coli physiology, Bacterial Physiological Phenomena, Chemotaxis, Models, Theoretical, Signal Transduction
- Abstract
Cellular signaling systems show astonishing precision in their response to external stimuli despite strong fluctuations in the molecular components that determine pathway activity. To control the effects of noise on signaling most efficiently, living cells employ compensatory mechanisms that reach from simple negative feedback loops to robustly designed signaling architectures. Here, we report on a novel control mechanism that allows living cells to keep precision in their signaling characteristics - stationary pathway output, response amplitude, and relaxation time - in the presence of strong intracellular perturbations. The concept relies on the surprising fact that for systems showing perfect adaptation an exponential signal amplification at the receptor level suffices to eliminate slowly varying multiplicative noise. To show this mechanism at work in living systems, we quantified the response dynamics of the E. coli chemotaxis network after genetically perturbing the information flux between upstream and downstream signaling components. We give strong evidence that this signaling system results in dynamic invariance of the activated response regulator against multiplicative intracellular noise. We further demonstrate that for environmental conditions, for which precision in chemosensing is crucial, the invariant response behavior results in highest chemotactic efficiency. Our results resolve several puzzling features of the chemotaxis pathway that are widely conserved across prokaryotes but so far could not be attributed any functional role.
- Published
- 2014
- Full Text
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33. Imprecision of adaptation in Escherichia coli chemotaxis.
- Author
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Neumann S, Vladimirov N, Krembel AK, Wingreen NS, and Sourjik V
- Subjects
- Cell Proliferation, Escherichia coli metabolism, Ligands, Adaptation, Physiological, Chemotaxis, Escherichia coli cytology, Escherichia coli physiology
- Abstract
Adaptability is an essential property of many sensory systems, enabling maintenance of a sensitive response over a range of background stimulus levels. In bacterial chemotaxis, adaptation to the preset level of pathway activity is achieved through an integral feedback mechanism based on activity-dependent methylation of chemoreceptors. It has been argued that this architecture ensures precise and robust adaptation regardless of the ambient ligand concentration, making perfect adaptation a celebrated property of the chemotaxis system. However, possible deviations from such ideal adaptive behavior and its consequences for chemotaxis have not been explored in detail. Here we show that the chemotaxis pathway in Escherichia coli shows increasingly imprecise adaptation to higher concentrations of attractants, with a clear correlation between the time of adaptation to a step-like stimulus and the extent of imprecision. Our analysis suggests that this imprecision results from a gradual saturation of receptor methylation sites at high levels of stimulation, which prevents full recovery of the pathway activity by violating the conditions required for precise adaptation. We further use computer simulations to show that limited imprecision of adaptation has little effect on the rate of chemotactic drift of a bacterial population in gradients, but hinders precise accumulation at the peak of the gradient. Finally, we show that for two major chemoeffectors, serine and cysteine, failure of adaptation at concentrations above 1 mM might prevent bacteria from accumulating at toxic concentrations of these amino acids.
- Published
- 2014
- Full Text
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34. Treatment of invasive fungal infections in cancer patients-updated recommendations of the Infectious Diseases Working Party (AGIHO) of the German Society of Hematology and Oncology (DGHO).
- Author
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Mousset S, Buchheidt D, Heinz W, Ruhnke M, Cornely OA, Egerer G, Krüger W, Link H, Neumann S, Ostermann H, Panse J, Penack O, Rieger C, Schmidt-Hieber M, Silling G, Südhoff T, Ullmann AJ, Wolf HH, Maschmeyer G, and Böhme A
- Subjects
- Amphotericin B administration & dosage, Amphotericin B adverse effects, Amphotericin B therapeutic use, Antifungal Agents administration & dosage, Antifungal Agents adverse effects, Candidiasis, Invasive drug therapy, Candidiasis, Invasive etiology, Catheter-Related Infections drug therapy, Catheter-Related Infections prevention & control, Chemotherapy-Induced Febrile Neutropenia complications, Clinical Trials as Topic, Combined Modality Therapy, Drug Monitoring, Drug Therapy, Combination, Echinocandins administration & dosage, Echinocandins adverse effects, Echinocandins therapeutic use, Fungemia drug therapy, Fungemia prevention & control, Humans, Immunocompromised Host, Immunotherapy, Invasive Pulmonary Aspergillosis drug therapy, Invasive Pulmonary Aspergillosis etiology, Invasive Pulmonary Aspergillosis surgery, Mycoses etiology, Mycoses surgery, Mycoses therapy, Salvage Therapy, Triazoles administration & dosage, Triazoles adverse effects, Triazoles therapeutic use, Antifungal Agents therapeutic use, Mycoses drug therapy, Neoplasms complications
- Abstract
The Infectious Diseases Working Party (AGIHO) of the German Society of Hematology and Oncology (DGHO) here presents its updated recommendations for the treatment of documented fungal infections. Invasive fungal infections are a main cause of morbidity and mortality in cancer patients undergoing intensive chemotherapy regimens. In recent years, new antifungal agents have been licensed, and agents already approved have been studied in new indications. The choice of the most appropriate antifungal treatment depends on the fungal species suspected or identified, the patient's risk factors (e.g., length and depth of neutropenia), and the expected side effects. This guideline reviews the clinical studies that served as a basis for the following recommendations. All recommendations including the levels of evidence are summarized in tables to give the reader rapid access to the information.
- Published
- 2014
- Full Text
- View/download PDF
35. Pharmacokinetics of meropenem in critically ill patients with severe infections.
- Author
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Binder L, Schwörer H, Hoppe S, Streit F, Neumann S, Beckmann A, Wachter R, Oellerich M, and Walson PD
- Subjects
- Adult, Aged, Aged, 80 and over, Anti-Bacterial Agents therapeutic use, Critical Illness, Female, Humans, Infections blood, Intensive Care Units, Male, Meropenem, Microbial Sensitivity Tests, Middle Aged, Prospective Studies, Retrospective Studies, Thienamycins therapeutic use, Anti-Bacterial Agents blood, Anti-Bacterial Agents pharmacokinetics, Infections drug therapy, Infections metabolism, Thienamycins blood, Thienamycins pharmacokinetics
- Abstract
Background: Meropenem is an effective β-lactam antibiotic that is frequently used to treat serious infections in both intensive care unit (ICU) and febrile neutropenic hematology/oncology (Hem/Onc) patients. Studies suggest that to be effective, meropenem concentrations must be maintained above the inhibitory concentrations for the majority of a dosing interval. However, the pharmacokinetics (PK) of meropenem seem to differ in critically ill patients compared with healthy or less ill subjects used to select labeled dosing regimens., Objectives: This study was designed to investigate meropenem PK in critically ill patients and to see how often standard dosing regimens produced adequate plasma concentrations. A secondary objective was to investigate how achieved concentrations were related to outcomes (morbidity and mortality) in these patients., Methods: Meropenem plasma concentrations over time were measured using a high pressure liquid chromatography assay in febrile Hem/Onc and ICU patients who were treated with standard meropenem dosing schedules. Outcomes such as fever control and survival were assessed in these patients and compared with individual meropenem PK data and with recommended target concentrations., Results: A total of 25 subjects including 10 febrile Hem/Onc and 15 ICU patients with a variety of serious illnesses and baseline renal function were studied. Mean peak concentrations were less variable than were pre-dose concentrations. Post peak and trough concentrations were often below recommended minimum inhibitory concentrations. Both clearance and volumes of distribution were greater than reported in less ill subjects, only in part explained by increased renal clearance. Therefore, serum concentrations often did not exceed recommended concentration targets even for moderately sensitive organisms. Inadequate concentrations were especially common in the mostly ill, febrile neutropenic Hem/Onc subjects and seemed to explain at least some therapeutic failures. Conversely, drug accumulation occurred in ICU subjects with decreased renal function., Conclusions: Standard meropenem dosing regimens were inadequate in many critically ill febrile, neutropenic Hem/Onc, and septic ICU patients. These data suggest a role for meropenem concentration monitoring in such patients.
- Published
- 2013
- Full Text
- View/download PDF
36. Chemotactic signaling via carbohydrate phosphotransferase systems in Escherichia coli.
- Author
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Neumann S, Grosse K, and Sourjik V
- Subjects
- Escherichia coli Proteins metabolism, Fluorescence Resonance Energy Transfer, Histidine Kinase, Immunoblotting, Methyl-Accepting Chemotaxis Proteins, Models, Biological, Bacterial Proteins metabolism, Carbohydrate Metabolism physiology, Chemotaxis physiology, Escherichia coli enzymology, Membrane Proteins metabolism, Phosphotransferases metabolism, Signal Transduction physiology
- Abstract
Chemotaxis allows bacteria to follow gradients of nutrients, environmental stimuli, and signaling molecules, optimizing bacterial growth and survival. Escherichia coli has long served as a model of bacterial chemotaxis, and the signal processing by the core of its chemotaxis pathway is well understood. However, most of the research so far has focused on one branch of chemotactic signaling, in which ligands bind to periplasmic sensory domains of transmembrane chemoreceptors and induce a conformational change that is transduced across the membrane to regulate activity of the receptor-associated kinase CheA. Here we quantitatively characterize another, receptor-independent branch of chemotactic signaling that is linked to the sugar uptake through a large family of phosphotransferase systems (PTSs). Using in vivo characterization of intracellular signaling and protein interactions, we demonstrate that signals from cytoplasmic PTS components are transmitted directly to the sensory complexes formed by chemoreceptors, CheA and an adapter protein CheW. We further conclude that despite different modes of sensing, the PTS- and receptor-mediated signals have similar regulatory effects on the conformation of the sensory complexes. As a consequence, both types of signals become integrated and undergo common downstream processing including methylation-dependent adaptation. We propose that such mode of signaling is essential for efficient chemotaxis to PTS substrates and may be common to most bacteria.
- Published
- 2012
- Full Text
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37. The energy-speed-accuracy tradeoff in sensory adaptation.
- Author
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Lan G, Sartori P, Neumann S, Sourjik V, and Tu Y
- Abstract
Adaptation is the essential process by which an organism becomes better suited to its environment. The benefits of adaptation are well documented, but the cost it incurs remains poorly understood. Here, by analysing a stochastic model of a minimum feedback network underlying many sensory adaptation systems, we show that adaptive processes are necessarily dissipative, and continuous energy consumption is required to stabilize the adapted state. Our study reveals a general relation among energy dissipation rate, adaptation speed and the maximum adaptation accuracy. This energy-speed-accuracy relation is tested in the Escherichia coli chemosensory system, which exhibits near-perfect chemoreceptor adaptation. We identify key requirements for the underlying biochemical network to achieve accurate adaptation with a given energy budget. Moreover, direct measurements confirm the prediction that adaptation slows down as cells gradually de-energize in a nutrient-poor medium without compromising adaptation accuracy. Our work provides a general framework to study cost-performance tradeoffs for cellular regulatory functions and information processing.
- Published
- 2012
- Full Text
- View/download PDF
38. Pleural malakoplakia caused by Rhodococcus equi infection in a patient after stem cell transplantation.
- Author
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Behnes CL, Neumann S, Schweyer S, and Radzun HJ
- Subjects
- Actinomycetales Infections complications, Actinomycetales Infections surgery, Biopsy, Humans, Immunohistochemistry, Immunosuppressive Agents adverse effects, Malacoplakia surgery, Male, Middle Aged, Pleural Diseases surgery, Tomography, X-Ray Computed, Transplantation, Homologous, Treatment Outcome, Actinomycetales Infections microbiology, Leukemia, Prolymphocytic, T-Cell surgery, Malacoplakia microbiology, Pleural Diseases microbiology, Rhodococcus equi isolation & purification, Stem Cell Transplantation adverse effects
- Abstract
Malakoplakia is a disease especially of the urinary tract with typical plaques most frequently observed in the urinary bladder's mucosa. In the context of immunosuppression malakoplakia can also occur in other organs. Some of these extravesical malakoplakias are associated with an infection by Rhodococcus equi, a rare human pathogen well known from veterinary medicine. Here we present the first case of a pleural malakoplakia without lung involvement caused by a proved Rhodococcus equi infection.
- Published
- 2012
- Full Text
- View/download PDF
39. Clinically defined chemotherapy-associated bowel syndrome predicts severe complications and death in cancer patients.
- Author
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Vehreschild MJ, Meissner AM, Cornely OA, Maschmeyer G, Neumann S, von Lilienfeld-Toal M, Karthaus M, Wattad M, Staib P, Hellmich M, Christ H, and Vehreschild JJ
- Subjects
- Adolescent, Adult, Aged, Aged, 80 and over, Antineoplastic Agents administration & dosage, Female, Humans, Incidence, Male, Middle Aged, Mitoxantrone administration & dosage, Neoplasms drug therapy, Neutropenia chemically induced, Neutropenia mortality, Risk Factors, Syndrome, Time Factors, Antineoplastic Agents adverse effects, Inflammatory Bowel Diseases chemically induced, Inflammatory Bowel Diseases mortality, Mitoxantrone adverse effects, Neoplasms mortality
- Abstract
Background: Neutropenic patients are at risk of abdominal complications and yet the incidence and impact of these complications on patients' morbidity and mortality have not been sufficiently evaluated. We aimed to assess a clinical rule for early detection of abdominal complications leading to death or transfer to intensive care in patients with chemotherapy-associated neutropenia., Design and Methods: This observational multicenter study was carried out in seven German hematology-oncology departments. For inclusion, neutropenia of at least 5 consecutive days was required. Risk factors for "transfer to intensive care" and "death" were assessed by backward-stepwise binary logistic regression analyses. Chemotherapy-associated bowel syndrome was defined as a combination of fever (T ≥37.8 °C) and abdominal pain and/or lack of bowel movement for 72 hours or more. Five hundred and twenty-one neutropenic episodes were documented in 359 patients., Results: The incidence of chemotherapy-associated bowel syndrome was 126/359 (35%) in first episodes of neutropenia. Transfer to intensive care occurred in 41/359 (11%) and death occurred in 17/359 (5%) first episodes. Chemotherapy-associated bowel syndrome and duration of neutropenia were identified as risk factors for transfer to intensive care (P<0.001; OR 4.753; 95% CI 2.297-9.833, and P=0.003; OR 1.061/d; 95% CI 1.021-1.103). Chemotherapy-associated bowel syndrome and mitoxantrone administration were identified as risk factors for death (P=0.005; OR 4.611; 95% CI 1.573-13.515 and P=0.026; OR 3.628; 95% CI 1.169-11.256)., Conclusions: The occurrence of chemotherapy-associated bowel syndrome has a significant impact on patients' outcome. In future interventional clinical trials, this definition might be used as a selection criterion for early treatment of patients at risk of severe complications.
- Published
- 2011
- Full Text
- View/download PDF
40. Lateral density of receptor arrays in the membrane plane influences sensitivity of the E. coli chemotaxis response.
- Author
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Khursigara CM, Lan G, Neumann S, Wu X, Ravindran S, Borgnia MJ, Sourjik V, Milne J, Tu Y, and Subramaniam S
- Subjects
- Blotting, Western, Cryoelectron Microscopy, Escherichia coli metabolism, Escherichia coli Proteins, Fluorescence Resonance Energy Transfer, Histidine Kinase, Ligands, Methyl-Accepting Chemotaxis Proteins, Multiprotein Complexes physiology, Bacterial Proteins metabolism, Chemotaxis physiology, Escherichia coli physiology, Membrane Proteins metabolism, Models, Molecular, Multiprotein Complexes metabolism, Signal Transduction physiology
- Abstract
In chemotactic bacteria, transmembrane chemoreceptors, CheA and CheW form the core signalling complex of the chemotaxis sensory apparatus. These complexes are organized in extended arrays in the cytoplasmic membrane that allow bacteria to respond to changes in concentration of extracellular ligands via a cooperative, allosteric response that leads to substantial amplification of the signal induced by ligand binding. Here, we have combined cryo-electron tomographic studies of the 3D spatial architecture of chemoreceptor arrays in intact E. coli cells with computational modelling to develop a predictive model for the cooperativity and sensitivity of the chemotaxis response. The predictions were tested experimentally using fluorescence resonance energy transfer (FRET) microscopy. Our results demonstrate that changes in lateral packing densities of the partially ordered, spatially extended chemoreceptor arrays can modulate the bacterial chemotaxis response, and that information about the molecular organization of the arrays derived by cryo-electron tomography of intact cells can be translated into testable, predictive computational models of the chemotaxis response.
- Published
- 2011
- Full Text
- View/download PDF
41. Differences in signalling by directly and indirectly binding ligands in bacterial chemotaxis.
- Author
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Neumann S, Hansen CH, Wingreen NS, and Sourjik V
- Subjects
- Bacterial Proteins genetics, Chemotactic Factors pharmacology, Chemotaxis drug effects, Dose-Response Relationship, Drug, Escherichia coli drug effects, Escherichia coli Proteins genetics, Humans, Membrane Proteins genetics, Methyl-Accepting Chemotaxis Proteins, Models, Theoretical, Signal Transduction drug effects, Bacterial Proteins metabolism, Chemotaxis physiology, Escherichia coli physiology, Escherichia coli Proteins metabolism, Ligands, Membrane Proteins metabolism, Signal Transduction physiology
- Abstract
In chemotaxis of Escherichia coli and other bacteria, extracellular stimuli are perceived by transmembrane receptors that bind their ligands either directly, or indirectly through periplasmic-binding proteins (BPs). As BPs are also involved in ligand uptake, they provide a link between chemotaxis and nutrient utilization by cells. However, signalling by indirectly binding ligands remains much less understood than signalling by directly binding ligands. Here, we compared intracellular responses mediated by both types of ligands and developed a new mathematical model for signalling by indirectly binding ligands. We show that indirect binding allows cells to better control sensitivity to specific ligands in response to their nutrient environment and to coordinate chemotaxis with ligand transport, but at the cost of the dynamic range being much narrower than for directly binding ligands. We further demonstrate that signal integration by the chemosensory complexes does not depend on the type of ligand. Overall, our data suggest that the distinction between signalling by directly and indirectly binding ligands is more physiologically important than the traditional distinction between high- and low-abundance receptors.
- Published
- 2010
- Full Text
- View/download PDF
42. Responses of Escherichia coli bacteria to two opposing chemoattractant gradients depend on the chemoreceptor ratio.
- Author
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Kalinin Y, Neumann S, Sourjik V, and Wu M
- Subjects
- Aspartic Acid pharmacology, Escherichia coli drug effects, Methyl-Accepting Chemotaxis Proteins, Receptors, Cell Surface, Serine pharmacology, Bacterial Proteins metabolism, Chemoreceptor Cells metabolism, Chemotactic Factors pharmacology, Chemotaxis, Escherichia coli physiology, Escherichia coli Proteins metabolism, Membrane Proteins metabolism
- Abstract
Escherichia coli chemotaxis has long served as a simple model of environmental signal processing, and bacterial responses to single chemical gradients are relatively well understood. Less is known about the chemotactic behavior of E. coli in multiple chemical gradients. In their native environment, cells are often exposed to multiple chemical stimuli. Using a recently developed microfluidic chemotaxis device, we exposed E. coli cells to two opposing but equally potent gradients of major attractants, methyl-aspartate and serine. The responses of E. coli cells demonstrated that chemotactic decisions depended on the ratio of the respective receptor number of Tar/Tsr. In addition, the ratio of Tar to Tsr was found to vary with cells' growth conditions, whereby it depended on the culture density but not on the growth duration. These results provide biological insights into the decision-making processes of chemotactic bacteria that are subjected to multiple chemical stimuli and demonstrate the importance of the cellular microenvironment in determining phenotypic behavior.
- Published
- 2010
- Full Text
- View/download PDF
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