32 results on '"S. Claassen"'
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2. Creation and implementation of an electronic health record note for quality improvement in pediatric epilepsy: Practical considerations and lessons learned
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David Czank, Aleksandra Mineyko, Luis Bello Espinosa, Alice W. Ho, Stafford Dean, Curtis S Claassen, Julia Jacobs, Morris H. Scantlebury, Brett A. Simms, Joka McMahon, Jeffrey Buchhalter, Maarit Mackay, Gary Ruta, Juan Pablo Appendino, Sabrina D'Alfonso, Brian L. Brooks, Kim Smyth, Tammy Still, Trina Roberts, Sonia Rothenmund, Jong M. Rho, Nancy Thornton, Jane Corbeil, and Tyson Sawchuk
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medicine.medical_specialty ,Quality management ,EHR ,media_common.quotation_subject ,Documentation ,Clinical decision support system ,quality improvement ,medicine ,Electronic Health Records ,Humans ,informatics ,Quality (business) ,Prospective Studies ,Facilitated communication ,Child ,Baseline (configuration management) ,RC346-429 ,media_common ,QI ,Emergency department ,electronic health record ,Neurology ,Informatics ,Family medicine ,Full‐length Original Research ,epilepsy ,Original Article ,Neurology (clinical) ,Neurology. Diseases of the nervous system ,Psychology - Abstract
Author(s): Buchhalter, Jeffrey R; Scantlebury, Morris H; D'Alfonso, Sabrina; Pablo Appendino, Juan; Bello Espinosa, Luis; Brooks, Brian L; Claassen, Curtis; Corbeil, Jane; Czank, David; Dean, Stafford; Ho, Alice W; Jacobs, Julia; Mackay, Maarit; McMahon, Joka; Mineyko, Aleksandra; Rho, Jong M; Roberts, Trina; Rothenmund, Sonia; Ruta, Gary; Sawchuk, Tyson; Simms, Brett A; Smyth, Kim; Still, Tammy; Thornton, Nancy | Abstract: ObjectiveTo describe the development of the Pediatric Epilepsy Outcome-Informatics Project (PEOIP) at Alberta Children's Hospital (ACH), which was created to provide standardized, point-of-care data entry; near-time data analysis; and availability of outcome dashboards as a baseline on which to pursue quality improvement.MethodsStakeholders involved in the PEOIP met weekly to determine the most important outcomes for patients diagnosed with epilepsy, create a standardized electronic note with defined fields (patient demographics, seizure and syndrome type and frequency and specific outcomes- seizure type and frequency, adverse effects, emergency department visits, hospitalization, and care pathways for clinical decision support. These were embedded in the electronic health record from which the fields were extracted into a data display platform that provided patient- and population-level dashboards updated every 36nhours. Provider satisfaction and family experience surveys were performed to assess the impact of the standardized electronic note.ResultsIn the last 5nyears, 3,245 unique patients involving 13, 831 encounters had prospective, longitudinal, standardized epilepsy data accrued via point-of-care data entry into an electronic note as part of routine clinical care. A provider satisfaction survey of the small number of users involved indicated that the vast majority believed that the note makes documentation more efficient. A family experience survey indicated that being provided with the note was considered "valuable" or "really valuable" by 86% of respondents and facilitated communication with family members, school, and advocacy organizations.SignificanceThe PEOIP serves as a proof of principle that information obtained as part of routine clinical care can be collected in a prospective, standardized, efficient manner and be used to construct filterable process/outcome dashboards, updated in near time (36nhours). This information will provide the necessary baseline data on which multiple of QI projects to improve meaningful outcomes for children with epilepsy will be based.
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- 2021
3. New insights into the genetic etiology of Alzheimer's disease and related dementias
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Bellenguez, C. Küçükali, F. Jansen, I.E. Kleineidam, L. Moreno-Grau, S. Amin, N. Naj, A.C. Campos-Martin, R. Grenier-Boley, B. Andrade, V. Holmans, P.A. Boland, A. Damotte, V. van der Lee, S.J. Costa, M.R. Kuulasmaa, T. Yang, Q. de Rojas, I. Bis, J.C. Yaqub, A. Prokic, I. Chapuis, J. Ahmad, S. Giedraitis, V. Aarsland, D. Garcia-Gonzalez, P. Abdelnour, C. Alarcón-Martín, E. Alcolea, D. Alegret, M. Alvarez, I. Álvarez, V. Armstrong, N.J. Tsolaki, A. Antúnez, C. Appollonio, I. Arcaro, M. Archetti, S. Pastor, A.A. Arosio, B. Athanasiu, L. Bailly, H. Banaj, N. Baquero, M. Barral, S. Beiser, A. Pastor, A.B. Below, J.E. Benchek, P. Benussi, L. Berr, C. Besse, C. Bessi, V. Binetti, G. Bizarro, A. Blesa, R. Boada, M. Boerwinkle, E. Borroni, B. Boschi, S. Bossù, P. Bråthen, G. Bressler, J. Bresner, C. Brodaty, H. Brookes, K.J. Brusco, L.I. Buiza-Rueda, D. Bûrger, K. Burholt, V. Bush, W.S. Calero, M. Cantwell, L.B. Chene, G. Chung, J. Cuccaro, M.L. Carracedo, Á. Cecchetti, R. Cervera-Carles, L. Charbonnier, C. Chen, H.-H. Chillotti, C. Ciccone, S. Claassen, J.A.H.R. Clark, C. Conti, E. Corma-Gómez, A. Costantini, E. Custodero, C. Daian, D. Dalmasso, M.C. Daniele, A. Dardiotis, E. Dartigues, J.-F. de Deyn, P.P. de Paiva Lopes, K. de Witte, L.D. Debette, S. Deckert, J. Del Ser, T. Denning, N. DeStefano, A. Dichgans, M. Diehl-Schmid, J. Diez-Fairen, M. Rossi, P.D. Djurovic, S. Duron, E. Düzel, E. Dufouil, C. Eiriksdottir, G. Engelborghs, S. Escott-Price, V. Espinosa, A. Ewers, M. Faber, K.M. Fabrizio, T. Nielsen, S.F. Fardo, D.W. Farotti, L. Fenoglio, C. Fernández-Fuertes, M. Ferrari, R. Ferreira, C.B. Ferri, E. Fin, B. Fischer, P. Fladby, T. Fließbach, K. Fongang, B. Fornage, M. Fortea, J. Foroud, T.M. Fostinelli, S. Fox, N.C. Franco-Macías, E. Bullido, M.J. Frank-García, A. Froelich, L. Fulton-Howard, B. Galimberti, D. García-Alberca, J.M. García-González, P. Garcia-Madrona, S. Garcia-Ribas, G. Ghidoni, R. Giegling, I. Giorgio, G. Goate, A.M. Goldhardt, O. Gomez-Fonseca, D. González-Pérez, A. Graff, C. Grande, G. Green, E. Grimmer, T. Grünblatt, E. Grunin, M. Gudnason, V. Guetta-Baranes, T. Haapasalo, A. Hadjigeorgiou, G. Haines, J.L. Hamilton-Nelson, K.L. Hampel, H. Hanon, O. Hardy, J. Hartmann, A.M. Hausner, L. Harwood, J. Heilmann-Heimbach, S. Helisalmi, S. Heneka, M.T. Hernández, I. Herrmann, M.J. Hoffmann, P. Holmes, C. Holstege, H. Vilas, R.H. Hulsman, M. Humphrey, J. Biessels, G.J. Jian, X. Johansson, C. Jun, G.R. Kastumata, Y. Kauwe, J. Kehoe, P.G. Kilander, L. Ståhlbom, A.K. Kivipelto, M. Koivisto, A. Kornhuber, J. Kosmidis, M.H. Kukull, W.A. Kuksa, P.P. Kunkle, B.W. Kuzma, A.B. Lage, C. Laukka, E.J. Launer, L. Lauria, A. Lee, C.-Y. Lehtisalo, J. Lerch, O. Lleó, A. Longstreth, W., Jr Lopez, O. de Munain, A.L. Love, S. Löwemark, M. Luckcuck, L. Lunetta, K.L. Ma, Y. Macías, J. MacLeod, C.A. Maier, W. Mangialasche, F. Spallazzi, M. Marquié, M. Marshall, R. Martin, E.R. Montes, A.M. Rodríguez, C.M. Masullo, C. Mayeux, R. Mead, S. Mecocci, P. Medina, M. Meggy, A. Mehrabian, S. Mendoza, S. Menéndez-González, M. Mir, P. Moebus, S. Mol, M. Molina-Porcel, L. Montrreal, L. Morelli, L. Moreno, F. Morgan, K. Mosley, T. Nöthen, M.M. Muchnik, C. Mukherjee, S. Nacmias, B. Ngandu, T. Nicolas, G. Nordestgaard, B.G. Olaso, R. Orellana, A. Orsini, M. Ortega, G. Padovani, A. Paolo, C. Papenberg, G. Parnetti, L. Pasquier, F. Pastor, P. Peloso, G. Pérez-Cordón, A. Pérez-Tur, J. Pericard, P. Peters, O. Pijnenburg, Y.A.L. Pineda, J.A. Piñol-Ripoll, G. Pisanu, C. Polak, T. Popp, J. Posthuma, D. Priller, J. Puerta, R. Quenez, O. Quintela, I. Thomassen, J.Q. Rábano, A. Rainero, I. Rajabli, F. Ramakers, I. Real, L.M. Reinders, M.J.T. Reitz, C. Reyes-Dumeyer, D. Ridge, P. Riedel-Heller, S. Riederer, P. Roberto, N. Rodriguez-Rodriguez, E. Rongve, A. Allende, I.R. Rosende-Roca, M. Royo, J.L. Rubino, E. Rujescu, D. Sáez, M.E. Sakka, P. Saltvedt, I. Sanabria, Á. Sánchez-Arjona, M.B. Sanchez-Garcia, F. Juan, P.S. Sánchez-Valle, R. Sando, S.B. Sarnowski, C. Satizabal, C.L. Scamosci, M. Scarmeas, N. Scarpini, E. Scheltens, P. Scherbaum, N. Scherer, M. Schmid, M. Schneider, A. Schott, J.M. Selbæk, G. Seripa, D. Serrano, M. Sha, J. Shadrin, A.A. Skrobot, O. Slifer, S. Snijders, G.J.L. Soininen, H. Solfrizzi, V. Solomon, A. Song, Y. Sorbi, S. Sotolongo-Grau, O. Spalletta, G. Spottke, A. Squassina, A. Stordal, E. Tartan, J.P. Tárraga, L. Tesí, N. Thalamuthu, A. Thomas, T. Tosto, G. Traykov, L. Tremolizzo, L. Tybjærg-Hansen, A. Uitterlinden, A. Ullgren, A. Ulstein, I. Valero, S. Valladares, O. Broeckhoven, C.V. Vance, J. Vardarajan, B.N. van der Lugt, A. Dongen, J.V. van Rooij, J. van Swieten, J. Vandenberghe, R. Verhey, F. Vidal, J.-S. Vogelgsang, J. Vyhnalek, M. Wagner, M. Wallon, D. Wang, L.-S. Wang, R. Weinhold, L. Wiltfang, J. Windle, G. Woods, B. Yannakoulia, M. Zare, H. Zhao, Y. Zhang, X. Zhu, C. Zulaica, M. Farrer, L.A. Psaty, B.M. Ghanbari, M. Raj, T. Sachdev, P. Mather, K. Jessen, F. Ikram, M.A. de Mendonça, A. Hort, J. Tsolaki, M. Pericak-Vance, M.A. Amouyel, P. Williams, J. Frikke-Schmidt, R. Clarimon, J. Deleuze, J.-F. Rossi, G. Seshadri, S. Andreassen, O.A. Ingelsson, M. Hiltunen, M. Sleegers, K. Schellenberg, G.D. van Duijn, C.M. Sims, R. van der Flier, W.M. Ruiz, A. Ramirez, A. Lambert, J.-C. EADB GR@ACE DEGESCO EADI GERAD Demgene FinnGen ADGC CHARGE
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Characterization of the genetic landscape of Alzheimer's disease (AD) and related dementias (ADD) provides a unique opportunity for a better understanding of the associated pathophysiological processes. We performed a two-stage genome-wide association study totaling 111,326 clinically diagnosed/'proxy' AD cases and 677,663 controls. We found 75 risk loci, of which 42 were new at the time of analysis. Pathway enrichment analyses confirmed the involvement of amyloid/tau pathways and highlighted microglia implication. Gene prioritization in the new loci identified 31 genes that were suggestive of new genetically associated processes, including the tumor necrosis factor alpha pathway through the linear ubiquitin chain assembly complex. We also built a new genetic risk score associated with the risk of future AD/dementia or progression from mild cognitive impairment to AD/dementia. The improvement in prediction led to a 1.6- to 1.9-fold increase in AD risk from the lowest to the highest decile, in addition to effects of age and the APOE ε4 allele. © 2022. The Author(s).
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- 2022
4. Assessment of fetal development during mid and late term pregnancies by standard B-Mode ultrasonography in Shetland ponies.
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Wagner LH, Aurich J, Claaßen S, Melchert M, Kaps M, and Aurich C
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- Animals, Female, Pregnancy, Horses embryology, Horses anatomy & histology, Pregnancy, Animal, Gestational Age, Fetal Development physiology, Ultrasonography, Prenatal veterinary, Ultrasonography, Prenatal methods
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Transrectal and transabdominal ultrasonography is an established method to monitor pregnancy, fetal growth and wellbeing in different species. Growth charts with multiple bio-morphometric parameters to estimate days of gestation and days before parturition exist in small companion animals, sheep and goats, riding type horses and large ponies but not in small horse breeds like Shetland ponies. The aim of this study was to apply fetal biometric assessment and detailed description of physiologic fetal development to mid and late term pregnancies in Shetland mares and to generate reference data for clinical practice and for future research. Fetal parameters were collected starting on day 101 of pregnancy in five Shetland mares. The fetal biometric parameters determined consisted of aortic diameter, eye diameter, combined rib and intercostal distance (CRID), stomach length and width and different heart morphology parameters in sagittal and frontal plane. Additionally, fetal activity and organ development in terms of differentiation and changes in echogenicity were recorded. Considering reliably assessable parameters, fetal CRID was the best predictor for gestational age with ± 13.6 days and fetal aortic diameter the most accurate for prediction of days until parturition with ± 16.2 days., Competing Interests: Declaration of competing interest The authors do not report any conflict of interest., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)
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- 2024
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5. The nasopharyngeal microbiome in South African children with lower respiratory tract infection: a nested case-control study of the Drakenstein Child Health Study.
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Claassen-Weitz S, Xia Y, Workman L, Hannan L, Gardner-Lubbe S, Mwaikono KS, Mounaud SH, Nierman WC, Africa S, Patel F, Dube FS, Allen V, Edries LAT, Zar HJ, and Nicol MP
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Background: Lower respiratory tract infection (LRTI) is a leading cause of infant morbidity and mortality globally. LRTI may be caused by viral or bacterial infections, individually or in combination. We investigated associations between LRTI and infant nasopharyngeal (NP) viruses and bacteria in a South African birth cohort., Methods: In a case-control study of infants enrolled in the Drakenstein Child Health Study (DCHS), LRTI cases were identified prospectively and age-matched with controls from the cohort. NP swabs were tested using quantitative real-time polymerase chain reaction (qPCR) and 16S rRNA gene amplicon sequencing. We calculated adjusted Conditional Odds Ratios (aORs) for qPCR targets and used mixed effects models to identify differentially abundant taxa between LRTI cases and controls and explore viral-bacterial interactions., Results: Respiratory Syncytial Virus (RSV) [aOR: 5.69, 95% CI: 3.03-10.69], human rhinovirus (HRV) [1.47, 1.03-2.09], parainfluenza virus [3.46, 1.64-7.26], adenovirus [1.99, 1.08-3.68], enterovirus [2.32, 1.20-4.46], Haemophilus influenzae [1.72, 1.25-2.37], Klebsiella pneumoniae [2.66, 1.59-4.46], or high-density (> 6.9 log
10 copies/mL) Streptococcus pneumoniae [1.53, 1.01-2.32] were associated with LRTI. Using 16S sequencing, LRTI was associated with increased relative abundance of Haemophilus (q = 0.0003) and decreased relative abundance of Dolosigranulum (q = 0.001), Corynebacterium (q = 0.091) and Neisseria (q = 0.004). In samples positive for RSV, Staphylococcus and Alloprevotella were present at lower relative abundance in cases than controls. In samples positive for parainfluenza virus or HRV, Haemophilus was present at higher relative abundance in cases., Conclusions: The associations between bacterial taxa and LRTI are strikingly similar to those identified in high-income countries, suggesting a conserved phenotype. RSV was the major virus associated with LRTI. H. influenzae appears to be the major bacterial driver of LRTI, acting synergistically with viruses. The Gram-positive bacteria Dolosigranulum and Corynebacteria may protect against LRTI, while Staphylococcus was associated with reduced risk of RSV-related LRTI., Funding: National Institutes of Health of the USA, Bill and Melinda Gates Foundation, National Research Foundation South Africa, South African Medical Research Council, L'Oréal-UNESCO For Women in Science South Africa, Australian National Health and Medical Research Council., Competing Interests: Competing interests The authors declare that they have no competing interests.- Published
- 2024
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6. Carbapenem-resistant Klebsiella pneumoniae among hospitalized patients in Cape Town, South Africa: molecular epidemiology and characterization.
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Marais G, Moodley C, Claassen-Weitz S, Patel F, Prentice E, Tootla H, Nyakutira N, Lennard K, Reddy K, Bamford C, Niehaus A, Whitelaw A, and Brink A
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Background: The molecular epidemiology of carbapenem-resistant Enterobacterales in Cape Town remains largely unknown., Objectives: This study aimed to describe the molecular epidemiology, resistome, virulome and mobilome of carbapenem-resistant Klebsiella pneumoniae (CRKP) within Cape Town to guide therapy, antimicrobial stewardship and infection prevention and control practices., Methods: Eighty-five CRKP isolates from hospitalized patients underwent WGS as part of a prospective, multicentre, cross-sectional study, conducted between 1 November 2020 and 30 November 2022, across public-sector and private-sector hospitals in Cape Town, South Africa., Results: MLST revealed three novel types, ST6785, ST6786 and ST6787, while the most common were ST219, ST307, ST17, ST13 and ST2497. Different predominant clones were noted in each hospital. The most common carbapenemase gene was bla
OXA-48-like , detected in 71% of isolates, with blaNDM detected in 5%. Notably, co-detection of two carbapenemase genes ( blaOXA-48-like and blaNDM ) occurred in 13% of isolates. The yersiniabactin siderophore was detected in 73% of isolates, and was most commonly associated with the ICE Kp 5 mobile element. All carbapenemases were located on plasmids. The genes blaOXA-181 and blaOXA-232 colocalized with a ColKP3 replicon type on assembled contigs in 83% and 100% of cases, respectively., Conclusions: CRKP epidemiology in Cape Town reflects institutionally dominant, rather than regional, clones. The most prevalent carbapenemase gene was blaOXA-48-like , in keeping with CRKP epidemiology in South Africa in general. Emerging clones harbouring both blaOXA-48-like and blaNDM , such as ST17, ST2497 and the novel ST6787, are a concern due to the limited availability of appropriate antimicrobial agents in South Africa., (© The Author(s) 2024. Published by Oxford University Press on behalf of British Society for Antimicrobial Chemotherapy.)- Published
- 2024
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7. Genital tract infections, the vaginal microbiome and gestational age at birth among pregnant women in South Africa: a cohort study protocol.
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Gigi RMS, Mdingi MM, Jung H, Claassen-Weitz S, Bütikofer L, Klausner JD, Muzny CA, Taylor CM, van de Wijgert JHHM, Peters RPH, and Low N
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- Child, Female, Pregnancy, Infant, Newborn, Humans, Child, Preschool, Pregnant Women, Cohort Studies, Gestational Age, South Africa epidemiology, Pregnancy Outcome, Chlamydia trachomatis, Premature Birth epidemiology, HIV Infections complications, Pregnancy Complications, Infectious, Reproductive Tract Infections epidemiology, Mycoplasma Infections
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Introduction: Preterm birth complications are the most common cause of death in children under 5 years. The presence of multiple microorganisms and genital tract inflammation could be the common mechanism driving early onset of labour. South Africa has high levels of preterm birth, genital tract infections and HIV infection among pregnant women. We plan to investigate associations between the presence of multiple lower genital tract microorganisms in pregnancy and gestational age at birth., Methods and Analysis: This cohort study enrols around 600 pregnant women at one public healthcare facility in East London, South Africa. Eligible women are ≥18 years and at <27 weeks of gestation, confirmed by ultrasound. At enrolment and 30-34 weeks of pregnancy, participants receive on-site tests for Chlamydia trachomatis and Neisseria gonorrhoeae , with treatment if test results are positive. At these visits, additional vaginal specimens are taken for: PCR detection and quantification of Trichomonas vaginalis , Candida spp., Mycoplasma genitalium, M. hominis , Ureaplasma urealyticum and U. parvum ; microscopy and Nugent scoring; and for 16S ribosomal RNA gene sequencing and quantification. Pregnancy outcomes are collected from a postnatal visit and birth registers. The primary outcome is gestational age at birth. Statistical analyses will explore associations between specific microorganisms and gestational age at birth. To explore the association with the quantity of microorganisms, we will construct an index of microorganism load and use mixed-effects regression models and classification and regression tree analysis to examine which combinations of microorganisms contribute to earlier gestational age at birth., Ethics and Dissemination: This protocol has approvals from the University of Cape Town Research Ethics Committee and the Canton of Bern Ethics Committee. Results from this study will be uploaded to preprint servers, submitted to open access peer-reviewed journals and presented at regional and international conferences., Trial Registration Number: NCT06131749; Pre-results., Competing Interests: Competing interests: CAM has received research grant funding to her institution by Gilead, Abbott Molecular, Visby and Lupin Pharmaceuticals. She is a consultant to BioNTech, Cepheid and BioFire Diagnostics. She has received honoraria for educational presentations and review activities from Scynexis, Visby, Abbott, Elsevier, UpToDate and DynaMed Plus., (© Author(s) (or their employer(s)) 2023. Re-use permitted under CC BY. Published by BMJ.)
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- 2023
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8. Abundance of Anti-Muellerian hormone in cat ovaries and correlation of its plasma concentration with animal age, weight and stage of the estrous cycle.
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Claaßen S, Aurich J, Walter I, Gautier C, and Aurich C
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- Female, Animals, Anti-Mullerian Hormone, Ovarian Follicle, Estrous Cycle, Ovary metabolism, Follicular Cyst metabolism, Follicular Cyst veterinary
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In female animals of different species, Anti-Müllerian hormone (AMH) is produced by follicular granulosa cells and has been associated with the ovarian follicle pool. Because concentration of AMH in plasma of ovary-intact female cats is apparently more variable than previously assumed, we have analysed AMH concentration in blood of cats (n = 93) presented for routine ovariectomy and assessed ovarian histology and AMH protein expression in the surgically removed ovaries. We hypothesised that AMH is synthesized only in preantral and small antral follicles and that plasma AMH concentration reflects the antral follicle count (AFC). Corpora lutea were detected in 35% of the female cats, whereas plasma progesterone concentration was ≥1 ng/mL in 57% of the cats. Follicular cysts were present in 15 cats (16%). Positive immunostaining for AMH protein was detected in close to all primordial and antral follicles, ovarian cysts, 70% of corpora lutea and 28% of atretic follicles. Concentration of AMH in plasma averaged 6.8 ± 0.5 ng/mL (range 1.3-21.7 ng/mL). The AFC increased with increasing AMH concentration with a moderate positive correlation between AFC and AMH (r = 0.286, p < 0.01). Plasma AMH concentration was not affected by season or cats' age, weight, stage of the estrous cycle and presence of follicular cysts. In conclusion, AMH protein is expressed in all endocrine structures of the cat ovary. While AMH is a marker for the presence of ovarian tissue, its usefulness to assess ovarian function in individual female cats is of limited value., Competing Interests: Declaration of competing interest None of the authors has any conflict of interest to declare., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)
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- 2023
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9. Low progesterone concentration in early pregnancy is detrimental to conceptus development and pregnancy outcome in horses.
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Wagner LH, Aurich J, Melchert M, Okada CTC, Gautier C, Kaps M, Claaßen S, and Aurich C
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- Pregnancy, Horses, Animals, Female, Ovulation, Prostaglandins F, Cloprostenol pharmacology, Progesterone, Pregnancy Outcome veterinary
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High progesterone concentrations in the early luteal phase support pregnancy, whereas subphysiological progesterone concentrations delay embryonic development at least until placentation. In this study, fetal growth and development of pregnancy was investigated in pregnancies with prostaglandin F
2α -induced low progesterone concentrations (PGF) in the early luteal phase and control pregnancies (CON) in the same mares (n = 12). Mares were inseminated and in PGF pregnancies received the prostaglandin F2α analogue cloprostenol (62.5 µg) on days 0-3 after ovulation to induce subphysiological progesterone concentrations; CON pregnancies remained untreated. Mares were assigned to PGF or CON treatments in alternating order and received the opposite treatment in the following year. Blood was collected and conceptus size determined repeatedly by transrectal (≤day 101) and transabdominal (>day 101) ultrasonography. After birth, foals were weighed, measured and submitted to a clinical examination. Treatment PGF resulted in fewer pregnancies than CON treatment. All foals born from CON pregnancies were healthy and mature, whereas 4/7 PGF pregnancies were either lost (one embryonic death, one abortion) or resulted in the birth of compromised foals (P = 0.018). Size of the conceptus (e.g., diameter day 49: PGF 6.6 ± 0.7, CON 7.7 ± 0.7 cm, P = 0.006) and embryo proper (e.g., crown rump length day 54; PGF 4.4 ± 0.8, CON 5.8 ± 0.6 cm, P = 0.015) differed between treatments. These size differences decreased over time and at birth PGF foals did not differ significantly from CON foals. In conclusion, reduced progesterone concentration in the early luteal phase leads to delayed conceptus growth beyond placentation and increased pregnancy loss., Competing Interests: Declaration of Competing Interest The authors declare that they have no financial or personal relationship with other people or organizations that could inappropriately influence or bias this article. As an Editor with Animal Reproduction Science, Dr. Christine Aurich was not privy to any of the review process other than the anonymous reviews that were returned to her as corresponding author., (Copyright © 2023 The Authors. Published by Elsevier B.V. All rights reserved.)- Published
- 2023
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10. Succession and determinants of the early life nasopharyngeal microbiota in a South African birth cohort.
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Claassen-Weitz S, Gardner-Lubbe S, Xia Y, Mwaikono KS, Mounaud SH, Nierman WC, Workman L, Zar HJ, and Nicol MP
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- Infant, Child, Humans, Infant, Newborn, South Africa, Birth Cohort, RNA, Ribosomal, 16S genetics, Nasopharynx microbiology, Bacteria genetics, Moraxella genetics, Corynebacterium genetics, Anti-Bacterial Agents therapeutic use, Microbiota genetics, HIV Infections drug therapy
- Abstract
Background: Bacteria colonizing the nasopharynx play a key role as gatekeepers of respiratory health. Yet, dynamics of early life nasopharyngeal (NP) bacterial profiles remain understudied in low- and middle-income countries (LMICs), where children have a high prevalence of risk factors for lower respiratory tract infection. We investigated longitudinal changes in NP bacterial profiles, and associated exposures, among healthy infants from low-income households in South Africa., Methods: We used short fragment (V4 region) 16S rRNA gene amplicon sequencing to characterize NP bacterial profiles from 103 infants in a South African birth cohort, at monthly intervals from birth through the first 12 months of life and six monthly thereafter until 30 months., Results: Corynebacterium and Staphylococcus were dominant colonizers at 1 month of life; however, these were rapidly replaced by Moraxella- or Haemophilus-dominated profiles by 4 months. This succession was almost universal and largely independent of a broad range of exposures. Warm weather (summer), lower gestational age, maternal smoking, no day-care attendance, antibiotic exposure, or low height-for-age z score at 12 months were associated with higher alpha and beta diversity. Summer was also associated with higher relative abundances of Staphylococcus, Streptococcus, Neisseria, or anaerobic gram-negative bacteria, whilst spring and winter were associated with higher relative abundances of Haemophilus or Corynebacterium, respectively. Maternal smoking was associated with higher relative abundances of Porphyromonas. Antibiotic therapy (or isoniazid prophylaxis for tuberculosis) was associated with higher relative abundance of anerobic taxa (Porphyromonas, Fusobacterium, and Prevotella) and with lower relative abundances of health associated-taxa Corynebacterium and Dolosigranulum. HIV-exposure was associated with higher relative abundances of Klebsiella or Veillonella and lower relative abundances of an unclassified genus within the family Lachnospiraceae., Conclusions: In this intensively sampled cohort, there was rapid and predictable replacement of early profiles dominated by health-associated Corynebacterium and Dolosigranulum with those dominated by Moraxella and Haemophilus, independent of exposures. Season and antibiotic exposure were key determinants of NP bacterial profiles. Understudied but highly prevalent exposures prevalent in LMICs, including maternal smoking and HIV-exposure, were associated with NP bacterial profiles. Video Abstract., (© 2023. The Author(s).)
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- 2023
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11. Sputum bacterial load and bacterial composition correlate with lung function and are altered by long-term azithromycin treatment in children with HIV-associated chronic lung disease.
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Abotsi RE, Dube FS, Rehman AM, Claassen-Weitz S, Xia Y, Simms V, Mwaikono KS, Gardner-Lubbe S, McHugh G, Ngwira LG, Kwambana-Adams B, Heyderman RS, Odland JØ, Ferrand RA, and Nicol MP
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- Adolescent, Humans, Child, Azithromycin therapeutic use, Anti-Bacterial Agents therapeutic use, Sputum microbiology, Bacterial Load, RNA, Ribosomal, 16S genetics, Bacteria genetics, Haemophilus, Moraxella, Lung microbiology, Lung Diseases drug therapy, HIV Infections complications, HIV Infections drug therapy
- Abstract
Background: Long-term azithromycin (AZM) treatment reduces the frequency of acute respiratory exacerbation in children and adolescents with HIV-associated chronic lung disease (HCLD). However, the impact of this treatment on the respiratory bacteriome is unknown., Method: African children with HCLD (defined as forced expiratory volume in 1 s z-score (FEV1z) less than - 1.0 with no reversibility) were enrolled in a placebo-controlled trial of once-weekly AZM given for 48-weeks (BREATHE trial). Sputum samples were collected at baseline, 48 weeks (end of treatment) and 72 weeks (6 months post-intervention in participants who reached this timepoint before trial conclusion). Sputum bacterial load and bacteriome profiles were determined using 16S rRNA gene qPCR and V4 region amplicon sequencing, respectively. The primary outcomes were within-participant and within-arm (AZM vs placebo) changes in the sputum bacteriome measured across baseline, 48 weeks and 72 weeks. Associations between clinical or socio-demographic factors and bacteriome profiles were also assessed using linear regression., Results: In total, 347 participants (median age: 15.3 years, interquartile range [12.7-17.7]) were enrolled and randomised to AZM (173) or placebo (174). After 48 weeks, participants in the AZM arm had reduced sputum bacterial load vs placebo arm (16S rRNA copies/µl in log
10 , mean difference and 95% confidence interval [CI] of AZM vs placebo - 0.54 [- 0.71; - 0.36]). Shannon alpha diversity remained stable in the AZM arm but declined in the placebo arm between baseline and 48 weeks (3.03 vs. 2.80, p = 0.04, Wilcoxon paired test). Bacterial community structure changed in the AZM arm at 48 weeks compared with baseline (PERMANOVA test p = 0.003) but resolved at 72 weeks. The relative abundances of genera previously associated with HCLD decreased in the AZM arm at 48 weeks compared with baseline, including Haemophilus (17.9% vs. 25.8%, p < 0.05, ANCOM ω = 32) and Moraxella (1% vs. 1.9%, p < 0.05, ANCOM ω = 47). This reduction was sustained at 72 weeks relative to baseline. Lung function (FEV1z) was negatively associated with bacterial load (coefficient, [CI]: - 0.09 [- 0.16; - 0.02]) and positively associated with Shannon diversity (0.19 [0.12; 0.27]). The relative abundance of Neisseria (coefficient, [standard error]: (2.85, [0.7], q = 0.01), and Haemophilus (- 6.1, [1.2], q < 0.001) were positively and negatively associated with FEV1z, respectively. An increase in the relative abundance of Streptococcus from baseline to 48 weeks was associated with improvement in FEV1z (3.2 [1.11], q = 0.01) whilst an increase in Moraxella was associated with decline in FEV1z (-2.74 [0.74], q = 0.002)., Conclusions: AZM treatment preserved sputum bacterial diversity and reduced the relative abundances of the HCLD-associated genera Haemophilus and Moraxella. These bacteriological effects were associated with improvement in lung function and may account for reduced respiratory exacerbations associated with AZM treatment of children with HCLD. Video Abstract., (© 2023. The Author(s).)- Published
- 2023
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12. Inhibition of the cholesterol transporter ABCA1 by probucol decreases capacitation and tyrosine phosphorylation of dog spermatozoa, and is dose dependent.
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Schäfer-Somi S, Claaßen S, and Lechner D
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- Dogs, Male, Animals, Phosphorylation, Sperm Motility physiology, Spermatozoa physiology, Cholesterol metabolism, Sperm Capacitation, Acrosome Reaction, Tyrosine pharmacology, Tyrosine metabolism, Probucol pharmacology, Probucol metabolism, Semen metabolism
- Abstract
The ATP binding cassette (ABC) transporter molecule ABCA1 participates in the cholesterol transport within and through cell membranes. We recently demonstrated that in dog spermatozoa, capacitation could be decreased with probucol (PRO), an ABCA1 specific antagonist. In this study, a dose-effect relationship of PRO on dog sperm capacitation, tyrosine phosphorylation and cholesterol efflux from the sperm plasma membrane was investigated. A total of 16 ejaculates from dogs of different breeds, aged 2-4 years were used. Sperm motility and membrane integrity in the main fraction was determined by CASA. Samples were stained with a boron dipyrromethene difluoride (BODIPY) fluorophore (P9672, Sigma- Aldrich, A) diluted in DMSO at a final concentration of 0.4 μM. All samples were divided into 5 aliquots, with 0, 100, 250, 500 and 1000 μM of PRO. After incubation at 37 °C for 2 h, PI was added and flow cytometry performed. All aliquots were examined for capacitation and acrosome reaction by using the CTC assay and tyrosine phosphorylation (TP). Membrane integrity was measured in all aliquots to investigate the effect of PRO on cell membranes. Membrane integrity did not differ between controls (0 μM), and 100, 250 and 500 μM PRO, but decreased with 1000 μM PRO (p < 0.05). Increasing PRO concentration decreased the percentage alive cells with cholesterol efflux per PRO group (0 μM: 77.8 ± 10.6%, 100 μM: 63.7 ± 11.7%, 250 μM: 52.1 ± 12.9%, 500 μM: 37.7 ± 11.6%, 1000 μM: 33.1 ± 14.4%; p < 0.05), decreased head and entire tail phosphorylated cells (0 μM: 34.6%, 1000 μM: 5.1% p < 0.05); and decreased the percentage capacitated cells (maximum with PRO 500 μM: capacitated vs. control: 54.2 ± 17% vs 25 ± 7.7%, p < 0.05). Conclusion: PRO decreased the cholesterol efflux, and decreased tyrosine phosphorylation and capacitation in a dose-dependent manner. This suggests a strong involvement of the ABCA1 transporter in different functional aspects of sperm capacitation in dogs., Competing Interests: Declaration of competing interest The authors declare no conflict of interest., (Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.)
- Published
- 2023
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13. Increased relaxation, less boredom, and a faster passage of time during a period of silence in the forest.
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Pfeifer E, Pothmann K, Claaßen S, and Wittmann M
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- Humans, Emotions, Affect, Forests, Boredom, Anxiety psychology
- Abstract
Introduction: There is growing evidence of the beneficial effects of exposure to nature on health and well-being. Time spent in nature can decrease stress, anxiety, depression, and improve mood. In the present study, we compared the experience of a short period of silence in the natural environment of a forest with the same amount of silence in a seminar room., Methods: We applied an intra-subject design with two 6:30-min sessions of silence in two different environments (forest, seminar room). The participants (n=41) were assigned to four groups. Two groups started with the indoor condition and two groups with the outdoor condition. After 1 week, the two groups were exposed to the other condition. Participants filled out personality-trait scales on meaning in life and belief in oneness with the world, as well as state scales assessing emotional reactions, relaxation, boredom, and the subjective sense of self, time, and space., Results: Participants felt significantly more relaxed and less bored in the forest compared to indoors. They experienced time less intensely, judging it to pass faster and to last shorter in the forest. Regarding trait variables, the higher the search for meaning, the higher oneness beliefs in participants. The higher oneness beliefs, the more positive participants felt during silence in the forest., Discussion: Interest in nature-assisted therapy is increasing in the healthcare sector. Exposure to silence in the natural setting of a forest could prove to be an effective complement to interventions applied in nature-assisted therapy, such as forest therapy., Competing Interests: Conflict of interest 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 Elsevier B.V. All rights reserved.)
- Published
- 2023
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14. Medical Students' Participation in Extracurricular Activities: Motivations, Contributions, and Barriers. A Qualitative Study.
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Achar Fujii RN, Kobayasi R, Claassen Enns S, and Zen Tempski P
- Abstract
Introduction: Extracurricular activities in medical education are defined as any social, philanthropic, non-mandatory, and unpaid activities. These activities promote interactions between students and the community in ways that both provide care and create learning opportunities and experiences for both students and the community at large. This study elaborates on the motivational aspects, learnings, and barriers that occur when students participate in these activities., Methods: This is a cross-sectional study of medical students in their first to fifth years. Qualitative analyses have been used to understand the motivation, barriers, and contributions associated with extracurricular activities participation., Results: Of the 586 students enrolled in the medical course, 462 students agreed to participate in the research. The students reported that they were motivated to participate in contributing to society, support their professional choices, integrate their knowledge, gain life experience, develop communication and leadership skills, learn to work in a team, and become more responsible, empathetic, and resilient. Barriers to participation were the limited number of available positions, selection criteria, lack of support from those involved, personal issues, poor time management, risk of lowered academic performance, and lack of physical and financial resources., Discussion: Medical students are motivated to participate in Community-based extracurricular activities (CBEA) and this experience leads to improvement in the curriculum and can develop fundamental skills and attitudes such as leadership, commitment, and responsibility. To maximize the benefits of these activities, schools must support students and ensure that they have the time and chance to participate without physical strain, that were barriers mentioned by the academics., Competing Interests: The authors report no conflicts of interest in this work., (© 2022 Achar Fujii et al.)
- Published
- 2022
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15. The association between bacteria colonizing the upper respiratory tract and lower respiratory tract infection in young children: a systematic review and meta-analysis.
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Claassen-Weitz S, Lim KYL, Mullally C, Zar HJ, and Nicol MP
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- Child, Child, Preschool, Cross-Sectional Studies, Humans, RNA, Ribosomal, 16S, Bacteria classification, Bacteria pathogenicity, Respiratory Tract Infections epidemiology, Respiratory Tract Infections microbiology
- Abstract
Background: Bacteria colonizing the upper respiratory tract (URT) of young children play a key role in the pathogenesis of lower respiratory tract infection (LRTI)., Objectives: To systematically review the literature on the association between bacteria colonizing the URT and LRTI among young children., Data Sources: MEDLINE, Academic Search Premier, Africa-Wide Information and CINAHL, Scopus and Web of Science., Study Eligibility Criteria: Studies published between 1923 and 2020, investigating URT bacteria from LRTI cases and controls., Participants: Children under 5 years with and without acute LRTI., Methods: Three reviewers independently screened titles, abstracts and full texts. Meta-analysis was done using Mantel-Haenszel fixed- or random-effects models., Results: Most eligible studies (41/50) tested nasopharyngeal specimens when investigating URT bacteria. Most studies were of cross-sectional design (44/50). Twenty-four studies were performed in children in lower- or lower-middle-income countries (LMICs). There was higher prevalence of Haemophilus influenzae (pooled OR 1.60; 95% CI 1.23-2.07) and Klebsiella spp. (pooled OR 2.04; 95% CI 1.17-3.55) from URT specimens of cases versus controls. We observed a positive association between the detection of Streptococcus pneumoniae from URT specimens and LRTI after excluding studies where there was more antibiotic treatment prior to sampling in cases vs. controls (pooled OR 1.41; 95% CI 1.04-1.90). High density colonization with S. pneumoniae (>6.9 log
10 copies/mL) was associated with an increased risk for LRTI. The associations between both Streptococcus and Haemophilus URT detection and LRTI were supported, at genus level, by 16S rRNA sequencing. Evidence for the role of Moraxella catarrhalis and Staphylococcus aureus was inconclusive., Conclusions: Detection of H. influenzae or Klebsiella spp. in the URT was associated with LRTI, while evidence for association with S. pneumoniae was less conclusive. Longitudinal studies assessing URT microbial communities, together with environmental and host factors are needed to better understand pathogenesis of childhood LRTI., (Copyright © 2021 The Authors. Published by Elsevier Ltd.. All rights reserved.)- Published
- 2021
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16. Using a multiple-delivery-mode training approach to develop local capacity and infrastructure for advanced bioinformatics in Africa.
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Ras V, Botha G, Aron S, Lennard K, Allali I, Claassen-Weitz S, Mwaikono KS, Kennedy D, Holmes JR, Rendon G, Panji S, Fields CJ, and Mulder N
- Subjects
- Africa, Algorithms, Curriculum, Genome, Human, Geography, Humans, Microbiota, Computational Biology education, Computational Biology methods, RNA, Ribosomal, 16S, Software
- Abstract
With more microbiome studies being conducted by African-based research groups, there is an increasing demand for knowledge and skills in the design and analysis of microbiome studies and data. However, high-quality bioinformatics courses are often impeded by differences in computational environments, complicated software stacks, numerous dependencies, and versions of bioinformatics tools along with a lack of local computational infrastructure and expertise. To address this, H3ABioNet developed a 16S rRNA Microbiome Intermediate Bioinformatics Training course, extending its remote classroom model. The course was developed alongside experienced microbiome researchers, bioinformaticians, and systems administrators, who identified key topics to address. Development of containerised workflows has previously been undertaken by H3ABioNet, and Singularity containers were used here to enable the deployment of a standard replicable software stack across different hosting sites. The pilot ran successfully in 2019 across 23 sites registered in 11 African countries, with more than 200 participants formally enrolled and 106 volunteer staff for onsite support. The pulling, running, and testing of the containers, software, and analyses on various clusters were performed prior to the start of the course by hosting classrooms. The containers allowed the replication of analyses and results across all participating classrooms running a cluster and remained available posttraining ensuring analyses could be repeated on real data. Participants thus received the opportunity to analyse their own data, while local staff were trained and supported by experienced experts, increasing local capacity for ongoing research support. This provides a model for delivering topic-specific bioinformatics courses across Africa and other remote/low-resourced regions which overcomes barriers such as inadequate infrastructures, geographical distance, and access to expertise and educational materials., Competing Interests: The authors have declared that no competing interests exist.
- Published
- 2021
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17. The Influence of DNA Extraction and Lipid Removal on Human Milk Bacterial Profiles.
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Ojo-Okunola A, Claassen-Weitz S, Mwaikono KS, Gardner-Lubbe S, Zar HJ, Nicol MP, and du Toit E
- Abstract
Culture-independent molecular techniques have advanced the characterization of environmental and human samples including the human milk (HM) bacteriome. However, extraction of high-quality genomic DNA that is representative of the bacterial population in samples is crucial. Lipids removal from HM prior to DNA extraction is common practice, but this may influence the bacterial population detected. The objective of this study was to compare four commercial DNA extraction kits and lipid removal in relation to HM bacterial profiles. Four commercial DNA extraction kits, QIAamp
® DNA Microbiome Kit, ZR Fungal/Bacterial DNA MiniPrep™, QIAsymphony DSP DNA Kit and ZymoBIOMICS™ DNA Miniprep Kit, were assessed using milk collected from ten healthy lactating women. The kits were evaluated based on their ability to extract high quantities of pure DNA from HM and how well they extracted DNA from bacterial communities present in a commercial mock microbial community standard spiked into HM. Finally, the kits were evaluated by assessing their extraction repeatability. Bacterial profiles were assessed using Illumina MiSeq sequencing targeting the V4 region of the 16S rRNA gene. The ZR Fungal/Bacterial DNA MiniPrep™ and ZymoBIOMICS™ DNA Miniprep (Zymo Research Corp., Irvine, CA, USA) kits extracted the highest DNA yields with the best purity. DNA extracted using ZR Fungal/Bacterial DNA MiniPrep™ best represented the bacteria in the mock community spiked into HM. In un-spiked HM samples, DNA extracted using the QIAsymphony DSP DNA kit showed statistically significant differences in taxa prevalence from DNA extracted using ZR Fungal/Bacterial DNA MiniPrep™ and ZymoBIOMICS™ DNA Miniprep kits. The only difference between skim and whole milk is observed in bacterial profiles with differing relative abundances of Enhydrobacter and Acinetobacter . DNA extraction, but not lipids removal, substantially influences bacterial profiles detected in HM samples, emphasizing the need for careful selection of a DNA extraction kit to improve DNA recovery from a range of bacterial taxa.- Published
- 2020
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18. Optimizing 16S rRNA gene profile analysis from low biomass nasopharyngeal and induced sputum specimens.
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Claassen-Weitz S, Gardner-Lubbe S, Mwaikono KS, du Toit E, Zar HJ, and Nicol MP
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- Bacteria genetics, Bacteria isolation & purification, Biomass, Computer Simulation, DNA, Bacterial genetics, DNA, Ribosomal genetics, Gene Dosage, High-Throughput Nucleotide Sequencing, Humans, Infant, Newborn, Specimen Handling, Bacteria classification, Nasopharynx microbiology, RNA, Ribosomal, 16S genetics, Sequence Analysis, DNA methods, Sputum microbiology
- Abstract
Background: Careful consideration of experimental artefacts is required in order to successfully apply high-throughput 16S ribosomal ribonucleic acid (rRNA) gene sequencing technology. Here we introduce experimental design, quality control and "denoising" approaches for sequencing low biomass specimens., Results: We found that bacterial biomass is a key driver of 16S rRNA gene sequencing profiles generated from bacterial mock communities and that the use of different deoxyribonucleic acid (DNA) extraction methods [DSP Virus/Pathogen Mini Kit® (Kit-QS) and ZymoBIOMICS DNA Miniprep Kit (Kit-ZB)] and storage buffers [PrimeStore® Molecular Transport medium (Primestore) and Skim-milk, Tryptone, Glucose and Glycerol (STGG)] further influence these profiles. Kit-QS better represented hard-to-lyse bacteria from bacterial mock communities compared to Kit-ZB. Primestore storage buffer yielded lower levels of background operational taxonomic units (OTUs) from low biomass bacterial mock community controls compared to STGG. In addition to bacterial mock community controls, we used technical repeats (nasopharyngeal and induced sputum processed in duplicate, triplicate or quadruplicate) to further evaluate the effect of specimen biomass and participant age at specimen collection on resultant sequencing profiles. We observed a positive correlation (r = 0.16) between specimen biomass and participant age at specimen collection: low biomass technical repeats (represented by < 500 16S rRNA gene copies/μl) were primarily collected at < 14 days of age. We found that low biomass technical repeats also produced higher alpha diversities (r = - 0.28); 16S rRNA gene profiles similar to no template controls (Primestore); and reduced sequencing reproducibility. Finally, we show that the use of statistical tools for in silico contaminant identification, as implemented through the decontam package in R, provides better representations of indigenous bacteria following decontamination., Conclusions: We provide insight into experimental design, quality control steps and "denoising" approaches for 16S rRNA gene high-throughput sequencing of low biomass specimens. We highlight the need for careful assessment of DNA extraction methods and storage buffers; sequence quality and reproducibility; and in silico identification of contaminant profiles in order to avoid spurious results.
- Published
- 2020
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19. Association of maternal prenatal psychological stressors and distress with maternal and early infant faecal bacterial profile.
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Naudé PJW, Claassen-Weitz S, Gardner-Lubbe S, Botha G, Kaba M, Zar HJ, Nicol MP, and Stein DJ
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- Adult, Female, Humans, Infant, Infant, Newborn, Male, Pregnancy, Feces microbiology, Mothers psychology, Prenatal Exposure Delayed Effects microbiology, Stress, Psychological microbiology
- Abstract
Objective: Findings from animal studies indicate that the early gut bacteriome is a potential mechanism linking maternal prenatal stress with health trajectories in offspring. However, clinical studies are scarce and the associations of maternal psychological profiles with the early infant faecal bacteriome are unknown. This study aimed to investigate the associations of prenatal stressors and distress with early infant faecal bacterial profiles in a South African birth cohort study., Methods: Associations between prenatal symptoms of depression, distress, intimate partner violence (IPV) and posttraumatic stress disorder (PTSD) and faecal bacterial profiles were evaluated in meconium and subsequent stool specimens from 84 mothers and 101 infants at birth, and longitudinally from a subset of 69 and 36 infants at 4-12 and 20-28 weeks of age, respectively, in a South African birth cohort study., Results: Infants born to mothers that were exposed to high levels of IPV had significantly higher proportions of Citrobacter and three unclassified genera, all of which belonging to the family Enterobacteriaceae detected at birth. Proportions of these Enterobacteriaceae remained significantly increased over time (birth to 20-28 weeks of life) in infants born to mothers with high levels of IPV exposure compared to infants from mothers with no/low IPV exposure. Infants born to mothers exposed to IPV also had higher proportions of the genus Weissella at 4-12 weeks compared to infants from mothers with no/low IPV exposure. Faecal specimens from mothers exposed to IPV had higher proportions of the family Lactobacillaceae and lower proportions of Peptostreptococcaceae at birth. Maternal psychological distress was associated with decreased proportions of the family Veillonellaceae in infants at 20-28 weeks and a slower decline in Gammaproteobacteria over time. No changes in beta diversity were apparent for maternal or infant faecal bacterial profiles in relation to any of the prenatal measures for psychological adversities., Conclusion: Maternal lifetime IPV and antenatal psychological distress are associated with altered bacterial profiles in infant and maternal faecal bacteria. These findings may provide insights in the involvement of the gut bacteria linking maternal psychological adversity and the maturing infant brain.
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- 2020
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20. Composition of Gut Microbiota of Children and Adolescents With Perinatal Human Immunodeficiency Virus Infection Taking Antiretroviral Therapy in Zimbabwe.
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Flygel TT, Sovershaeva E, Claassen-Weitz S, Hjerde E, Mwaikono KS, Odland JØ, Ferrand RA, Mchugh G, Gutteberg TJ, Nicol MP, Cavanagh JP, and Flægstad T
- Subjects
- Adolescent, Anti-Retroviral Agents adverse effects, CD4 Lymphocyte Count, CD4-Positive T-Lymphocytes, Child, Cross-Sectional Studies, Dysbiosis virology, Female, HIV Infections virology, Humans, Male, RNA, Ribosomal, 16S genetics, Sequence Analysis, RNA, Viral Load, Zimbabwe epidemiology, Anti-Retroviral Agents therapeutic use, Dysbiosis epidemiology, Gastrointestinal Microbiome drug effects, Gastrointestinal Microbiome genetics, HIV, HIV Infections drug therapy, HIV Infections epidemiology
- Abstract
Background: Human immunodeficiency virus (HIV) infection causes impairment of the gastrointestinal barrier, with substantial depletion of CD4+ T cells in the gut. Antiretroviral therapy (ART) restores CD4+ counts and may have beneficial effects on gut microbiota in adults. Little is known about effect of long-term ART on gut microbiome in HIV-infected children. We investigated composition of gut microbiota in HIV-infected and -uninfected children and assessed associations between gut microbiota and patient characteristics., Methods: In a cross-sectional study, rectal swabs were collected from 177 HIV-infected and 103 HIV-uninfected controls. Gut microbial composition was explored using 16S ribosomal ribonucleic acid sequencing., Results: Human immunodeficiency virus-infected children had significantly lower alpha-diversity and higher beta-diversity compared to HIV-uninfected. No association was observed between microbiome diversity and CD4+ T-cell count, HIV viral load, or HIV-associated chronic lung disease. We found enriched levels of Corynebacterium (P < .01), Finegoldia (P < .01), and Anaerococcus (P < .01) in HIV-infected participants and enrichment of Enterobacteriaceae (P = .02) in participants with low CD4+ counts (<400 cells/mm3). Prolonged ART-treatment (≥10 years) was significantly associated with a richer gut microbiota by alpha diversity., Conclusions: Human immunodeficiency virus-infected children have altered gut microbiota. Prolonged ART may restore the richness of the microbiota closer to that of HIV-uninfected children., (© The Author(s) 2019. Published by Oxford University Press for the Infectious Diseases Society of America.)
- Published
- 2020
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21. Cardiac troponin I is present in plasma of type 1 myocardial infarction patients and patients with troponin I elevations due to other etiologies as complex with little free I.
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van Wijk XMR, Claassen S, Enea NS, Li P, Yang S, Brouwer MA, Cramer GE, Zuk R, Lynch KL, and Wu AHB
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- Animals, Cell Line, Female, Humans, Male, Myocardial Infarction classification, Rats, Rats, Nude, Myocardial Infarction blood, Myocardium metabolism, Troponin I blood, Troponin T blood
- Abstract
Background: Cardiac troponin (cTn) is a complex of three subunits (T, I, and C), with some studies reporting that ~5-10% is cytosolic and unbound ('free'). It has been hypothesized that free cTn is released before complex and before or without cell death dependent on the severity of ischemia. In this context, new generation assays that can discriminate free, binary (IC) and ternary (TIC) complex forms may aid to differentiate between type 1 myocardial infarction (MI) and cTn elevations due to different etiologies, e.g. demand ischemia and type 2 MI., Methods: Serial plasma samples from six type 1 MI patients and twenty-seven patients with other cTnI elevations, e.g. due to demand ischemia and type 2 MI, were analyzed using high-sensitivity ET Healthcare Pylon assays for total cTnI, complex cTnI (IC and TIC), and cTnTIC. The specificity of the anti-cTnT antibody in the cTnTIC assay was such that only full-size cTnTIC is detected. In vitro stability of different cTnI forms was assessed by spiking free cTnI and cTnTIC in cTnI-free serum, incubating at 4 or 37 °C, and measuring different cTnI forms over 0-182 h. Presence of cytosolic free cTnI was evaluated on fixed rat cardiac tissue using an antibody against free cTnI., Results: Pylon assays for total and complex cTnI tracked well over time with each other and gave similar results, both for type 1 MI and non-type 1 MI patients, indicating that the vast majority was complex cTnI. As a minority of complex cTnI was full-size cTnTIC, this indicated that complex cTnI mainly consisted of a degraded form of cTnTIC (low-molecular weight cTnTIC) and/or cTnIC. Full-size cTnTIC was more abundant in early compared to late samples. In vitro studies indicated that free cTnI and cTnTIC are not stable at 37 °C (28% and 11% recovery after 24 h, respectively) and this is also true to some extent for cTnTIC at 4 °C (60% recovery after 24 h). Free cTnI was not readily detected in rat cardiac tissue., Conclusions: In agreement with type 1 MI, cTnI in samples of patients with cTnI elevations due to other etiologies is found predominantly as complex cTnI, of which some is full-size cTnTIC. In most cases, assays for total and complex cTnI indicated there was little free cTnI; however, its presence cannot be completely excluded, due to the inability of its direct measurement and limited stability., (Copyright © 2019 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.)
- Published
- 2019
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22. Influence of Socio-Economic and Psychosocial Profiles on the Human Breast Milk Bacteriome of South African Women.
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Ojo-Okunola A, Claassen-Weitz S, Mwaikono KS, Gardner-Lubbe S, Stein DJ, Zar HJ, Nicol MP, and du Toit E
- Subjects
- Adult, Age Factors, Bacteriological Techniques, Female, Humans, Lactation, RNA, Ribosomal, 16S, South Africa, Bacteria growth & development, Microbiota, Milk, Human microbiology, Mothers statistics & numerical data, Socioeconomic Factors
- Abstract
The human breast milk (HBM) bacteriome is an important, continuous source of microbes to the neonate in early life, playing an important role in shaping the infant's intestinal bacteriome. Study of the composition of the HBM bacteriome is an emerging area of research, with little information available, particularly from low- and middle-income countries. The aim of this study was to characterize the diversity of bacterial communities in HBM samples collected between 6-10 weeks postpartum from lactating South African women and to study potential influencing factors of the bacteriome. Using 16S rRNA gene sequencing of samples from 554 women, we demonstrated that the HBM bacteriome was largely dominated by the phyla Firmicutes (mean relative abundance: 71.1%) and Actinobacteria (mean relative abundance: 16.4%). The most abundant genera identified from the HBM bacteriome were Streptococcus (mean relative abundance: 48.6%), Staphylococcus (mean relative abundance: 17.8%), Rothia (mean relative abundance: 5.8%), and Corynebacterium (mean relative abundance: 4.3%). "Core" bacterial genera including Corynebacterium , Streptococcus, Staphylococcus, Rothia, Veillonella, Gemella, Acinetobacter, Micrococcus and a genus belonging to the Enterobacteriaceae family were present in 80% of samples. HBM samples were classified, according to their bacteriome, into three major clusters, dominated by the genera Staphylococcus (cluster 1), a combination of Staphylococcus and Streptococcus (cluster 2), and Streptococcus (cluster 3). The cluster groups differed significantly for Shannon and chao1 richness indices. Bacterial interactions were studied using co-occurrence networks with positive associations observed between the abundances of Staphylococcus and Corynebacteria (members of the skin microflora) and between Streptococcus, Rothia, Veillonella, and Gemella (members of the oral microflora). HBM from older mothers had a higher Shannon diversity index. The study site was associated with differences in HBM bacteriome composition (permutational multivariate analysis of variance using distance matrices (PERMANOVA), p < 0.05). No other tested socio-demographic or psychosocial factors were associated with HBM bacterial composition., Competing Interests: The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.
- Published
- 2019
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23. HIV-exposure, early life feeding practices and delivery mode impacts on faecal bacterial profiles in a South African birth cohort.
- Author
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Claassen-Weitz S, Gardner-Lubbe S, Nicol P, Botha G, Mounaud S, Shankar J, Nierman WC, Mulder N, Budree S, Zar HJ, Nicol MP, and Kaba M
- Subjects
- Adult, Bifidobacterium genetics, Bifidobacterium isolation & purification, Breast Feeding, Feces virology, Feeding Behavior, Female, Firmicutes genetics, Firmicutes isolation & purification, HIV genetics, HIV pathogenicity, HIV Infections genetics, HIV Infections virology, Humans, Infant, Infant Formula microbiology, Infant, Newborn, Meconium virology, Mothers, Proteobacteria genetics, Proteobacteria isolation & purification, RNA, Ribosomal, 16S genetics, South Africa epidemiology, Feces microbiology, Gastrointestinal Microbiome genetics, HIV Infections microbiology, Meconium microbiology
- Abstract
There are limited data on meconium and faecal bacterial profiles from African infants and their mothers. We characterized faecal bacterial communities of infants and mothers participating in a South African birth cohort. Stool and meconium specimens were collected from 90 mothers and 107 infants at birth, and from a subset of 72 and 36 infants at 4-12 and 20-28 weeks of age, respectively. HIV-unexposed infants were primarily exclusively breastfed at 4-12 (49%, 26/53) and 20-28 weeks (62%, 16/26). In contrast, HIV-exposed infants were primarily exclusively formula fed at 4-12 (53%; 10/19) and 20-28 weeks (70%, 7/10). Analysis (of the bacterial 16S rRNA gene sequences of the V4 hypervariable region) of the 90 mother-infant pairs showed that meconium bacterial profiles [dominated by Proteobacteria (89%)] were distinct from those of maternal faeces [dominated by Firmicutes (66%) and Actinobacteria (15%)]. Actinobacteria predominated at 4-12 (65%) and 20-28 (50%) weeks. HIV-exposed infants had significantly higher faecal bacterial diversities at both 4-12 (p = 0.026) and 20-28 weeks (p = 0.002). HIV-exposed infants had lower proportions of Bifidobacterium (p = 0.010) at 4-12 weeks. Maternal faecal bacterial profiles were influenced by HIV status, feeding practices and mode of delivery. Further longitudinal studies are required to better understand how these variables influence infant and maternal faecal bacterial composition.
- Published
- 2018
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24. Modeling the development of panic disorder with interoceptive conditioning.
- Author
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De Cort K, Schroijen M, Hurlemann R, Claassen S, Hoogenhout J, Van den Bergh O, Goossens L, Van Diest I, and Schruers K
- Subjects
- Adult, Aged, Carbon Dioxide administration & dosage, Electrocardiography, Female, Galvanic Skin Response, Humans, Male, Middle Aged, Pentagastrin administration & dosage, Psychiatric Status Rating Scales, Self Report, Somatoform Disorders etiology, Young Adult, Anxiety etiology, Conditioning, Classical, Models, Theoretical, Somatoform Disorders complications, Somatoform Disorders psychology
- Abstract
Panic disorder is characterized by the paroxysmal occurrence and fear of bodily symptoms. In recent years it has been proposed that patients "learn" to fear cardiorespiratory sensations through interoceptive conditioning. This study sought to model the initial stage of this process in healthy volunteers (N=44) using mild cardiac sensations. An additional aim was to explore whether anxiety sensitivity - a known risk factor for panic disorder - modulates such interoceptive learning. Infusions of pentagastrin and saline were used to manipulate the presence versus absence of cardiac sensations, respectively, and served as conditioned stimuli in a differential interoceptive conditioning paradigm. Inhalation of 35% CO
2 -enriched air served as the panicogenic, unconditioned stimulus (UCS). In half of the participants ("prepared" condition), cardiac sensations caused by pentagastrin were followed by inhalation of CO2 -enriched air (penta CS+), whereas the absence of such sensations (saline) was followed by room air (saline CS-). The reversed combination ("unprepared" condition) was used in the other half of the participants. Conditioning effects showed up for self-reported UCS-expectancy, but not for skin conductance and anxiety ratings. Only participants from the prepared group learned to expect the UCS, and differential learning was impaired with higher scores on anxiety sensitivity. Expectancy learning was more easily established towards the presence compared to the absence of cardiac sensations, whereas the reverse effect was observed for safety learning. Modeling impaired discriminatory learning and the moderating effect of anxiety sensitivity provides new insight in the development of panic disorder., (Copyright © 2016 Elsevier B.V. and ECNP. All rights reserved.)- Published
- 2017
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25. Current Knowledge and Future Research Directions on Fecal Bacterial Patterns and Their Association with Asthma.
- Author
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Claassen-Weitz S, Wiysonge CS, Machingaidze S, Thabane L, Horsnell WG, Zar HJ, Nicol MP, and Kaba M
- Published
- 2016
- Full Text
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26. Fecal Carriage of Staphylococcus aureus in the Hospital and Community Setting: A Systematic Review.
- Author
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Claassen-Weitz S, Shittu AO, Ngwarai MR, Thabane L, Nicol MP, and Kaba M
- Abstract
Background and Rationale: Staphylococcus aureus fecal carriage has been identified as a potential source for nosocomial transmission and a risk factor for disease development. This systematic review determined the overall S. aureus [including methicillin susceptible and resistant S. aureus (MSSA and MRSA)] fecal carriage rates within the community and healthcare settings., Methodology: Peer-reviewed articles indexed in Medline, Scopus, Academic Search Premier, Africa-Wide Information, CINAHL, and Web of Science were identified using applicable and controlled vocabulary through to 11 November 2015. Eligible studies were ascertained by three independent reviewers. Random-effects meta-analyses of proportions were performed to determine S. aureus, MSSA and MRSA fecal carriage rates reported by eligible studies., Results: Twenty six studies were included in this review. The pooled estimates for S. aureus, MSSA and MRSA fecal carriage were 26% (95% confidence interval (CI): 16.8-36.3%), 86% (95% confidence interval (CI): 65.9-97.9%) and 10% (95% CI: 0.7-27.0%), respectively. Fecal S. aureus carriage rates increased on average from 10 to 65% during the first 8 weeks of life, followed by an average carriage rate of 64% at 6 months and 46% at 1 year of life. Genotyping techniques were employed mainly in studies conducted in developed countries and comprised largely of gel-based techniques. Six studies reported on the role of S. aureus fecal strains in diarrhea (n = 2) and the risk for acquiring infections (n = 4). Eight of the 26 studies included in this review performed antibiotic susceptibility testing of S. aureus fecal isolates., Conclusion: This study provides evidence that screening for S. aureus fecal carriage, at least in populations at high risk, could be an effective measure for the prevention of S. aureus transmission and infection in the healthcare and community setting. More well-structured studies need to be conducted and sequence-based genotyping techniques should be employed for the comparison of isolates on a global scale in both developing and developed countries.
- Published
- 2016
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27. The requirements of a specialist Breast Centre.
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Wilson AR, Marotti L, Bianchi S, Biganzoli L, Claassen S, Decker T, Frigerio A, Goldhirsch A, Gustafsson EG, Mansel RE, Orecchia R, Ponti A, Poortmans P, Regitnig P, Rosselli Del Turco M, Rutgers EJ, van Asperen C, Wells CA, Wengström Y, and Cataliotti L
- Subjects
- Accreditation, Communication, Early Detection of Cancer, Education, Medical, Continuing legislation & jurisprudence, Education, Medical, Continuing organization & administration, Female, Humans, Interdisciplinary Communication, Patient Care Team legislation & jurisprudence, Patient Care Team organization & administration, Physician-Patient Relations, Breast Neoplasms diagnosis, Breast Neoplasms therapy, Cancer Care Facilities organization & administration, Patient-Centered Care organization & administration
- Abstract
Introduction: In recognition of the advances and evidence based changes in clinical practice that have occurred in recent years and taking into account the knowledge and experience accumulated through the voluntary breast unit certification programme, Eusoma has produced this up-dated and revised guidelines on the requirements of a Specialist Breast Centre (BC)., Methods: The content of these guidelines is based on evidence from the recent relevant peer reviewed literature and the consensus of a multidisciplinary team of European experts. The guidelines define the requirements for each breast service and for the specialists who work in specialist Breast Centres., Results: The guidelines identify the minimum requirements needed to set up a BC, these being an integrated Breast Centre, dealing with a sufficient number of cases to allow effective working and continuing expertise, dedicated specialists working with a multidisciplinary approach, providing all services throughout the patients pathway and data collection and audit. It is essential that the BC also guarantees the continuity of care for patients with advanced (metastatic) disease offering treatments according to multidisciplinary competencies and a high quality palliative care service. The BC must ensure that comprehensive support and expertise may be needed, not only through the core BC team, but also ensure that all other medical and paramedical expertise that may be necessary depending on the individual case are freely available, referring the patient to the specific care provider depending on the problem., Conclusions: Applying minimum requirements and quality indicators is essential to improve organisation, performance and outcome in breast care. Efficacy and compliance have to be constantly monitored to evaluate the quality of patient care and to allow appropriate corrective actions leading to improvements in patient care., (Copyright © 2013 Elsevier Ltd. All rights reserved.)
- Published
- 2013
- Full Text
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28. A comparison of the efficiency of five different commercial DNA extraction kits for extraction of DNA from faecal samples.
- Author
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Claassen S, du Toit E, Kaba M, Moodley C, Zar HJ, and Nicol MP
- Subjects
- Bacteria genetics, DNA, Bacterial genetics, Denaturing Gradient Gel Electrophoresis, Humans, Polymerase Chain Reaction, Reagent Kits, Diagnostic economics, Bacteria isolation & purification, DNA, Bacterial isolation & purification, Feces chemistry, Feces microbiology, Genetic Techniques instrumentation
- Abstract
Differences in the composition of the gut microbiota have been associated with a range of diseases using culture-independent methods. Reliable extraction of nucleic acid is a key step in identifying the composition of the faecal microbiota. Five widely used commercial deoxyribonucleic acid (DNA) extraction kits (QIAsymphony® Virus/Bacteria Midi Kit (kit QS), ZR Fecal DNA MiniPrep™ (kit Z), QIAamp® DNA Stool Mini Kit (kit QA), Ultraclean® Fecal DNA Isolation Kit (kit U) and PowerSoil® DNA Isolation Kit (kit P)) were evaluated, using human faecal samples. Yield, purity and integrity of total genomic DNA were compared spectrophotometrically and using gel electrophoresis. Three bacteria, commonly found in human faeces were quantified using real time polymerase chain reaction (qPCR) and total bacterial diversity was studied using denaturing gradient gel electrophoresis (DGGE) as well as terminal restriction fragment length polymorphism (T-RFLP). The measurements of DNA yield and purity exhibited variations between the five kits tested in this study. Automated kit QS exhibited the best quality and highest quantity of DNA. All kits were shown to be reproducible with CV values≤0.46 for DNA extraction. qPCR results showed that all kits were uniformly efficient for extracting DNA from the selected target bacteria. DGGE and T-RFLP produced the highest diversity scores for DNA extracted using kit Z (H'=2.30 and 1.27) and kit QS (H'=2.16 and 0.94), which also extracted the highest DNA yields compared to the other kits assessed., (Copyright © 2013 Elsevier B.V. All rights reserved.)
- Published
- 2013
- Full Text
- View/download PDF
29. Training breast care nurses throughout Europe: the EONS postbasic curriculum for breast cancer nursing.
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Eicher M, Kadmon I, Claassen S, Marquard S, Pennery E, Wengstrom Y, and Fenlon D
- Subjects
- Europe, Female, Humans, Societies, Nursing, Breast Neoplasms nursing, Curriculum, Education, Nursing, Continuing methods, Oncology Nursing education
- Abstract
Background: The European Parliamentary Group on Breast Cancer and the European Society of Breast Cancer Specialists state that there is a need for EU agreed guidelines on breast care nursing and training. Therefore the European Oncology Nursing Society (EONS) commissioned the development of a post-basic curriculum for breast cancer nursing., Purpose: The goal was to define a European curriculum for the training of breast care nurses., Methods: The curriculum was developed using a variety of sources, including guidelines from a number of European and other countries world wide, relevant literature and input from an expert panel of senior European nurses with expertise in breast care nursing., Results: An English language, European curriculum of breast care nursing was developed at a postbasic level to provide guidance for the training of breast care nurses throughout Europe. Definitions for breast care nurse roles and activities and levels of practice, as well as indicative content are provided., Conclusions: The training of nurses in breast cancer care should be mandatory and common practice for European countries. To enhance comparability and standard development, the indicative content should be applied in all future post-basic education., (Copyright © 2011 Elsevier Ltd. All rights reserved.)
- Published
- 2012
- Full Text
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30. Electrophysiological and fluorescence microscopy studies with HERG channel/EGFP fusion proteins.
- Author
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Claassen S, Schwarzer S, Ludwig J, and Zünkler BJ
- Subjects
- Cell Line, Cell Membrane genetics, Cytoplasm genetics, ERG1 Potassium Channel, Ether-A-Go-Go Potassium Channels genetics, Green Fluorescent Proteins genetics, Green Fluorescent Proteins metabolism, Humans, Microscopy, Confocal, Protein Structure, Tertiary genetics, Protein Transport genetics, Recombinant Fusion Proteins genetics, Recombinant Fusion Proteins metabolism, Torsades de Pointes genetics, Torsades de Pointes metabolism, Cell Membrane metabolism, Cytoplasm metabolism, Ether-A-Go-Go Potassium Channels metabolism, Potassium metabolism
- Abstract
HERG (human ether-a-go-go-related gene) encodes the Kv11.1 protein alpha-subunit that underlies the rapidly activating delayed rectifier K+ current (IKr) in the heart. Alterations in the functional properties or membrane incorporation of HERG channels, either by genetic mutations or by administration of drugs, play major roles in the development of life-threatening torsades de pointes cardiac arrhythmias. Visualization of ion channel localization is facilitated by enhanced green fluorescent protein (EGFP) tagging, but this process can alter their properties. The aim of the present study was to characterize the electrophysiological properties and the cellular localization of HERG channels in which EGFP was tagged either to the C terminus (HERG/EGFP) or to the N terminus (EGFP/HERG). These fusion constructs were transiently expressed in human embryonic kidney (HEK) 293 cells, and the whole-cell patch-clamp configuration and a confocal laser scanning microscope with primary anti-HERG antibodies and fluorescently labeled secondary antibodies were used. For EGFP/HERG channels the deactivation kinetics were faster and the peak tail current density was reduced when compared to both wild-type HERG channels and HERG/EGFP channels. Laser scanning microscopic studies showed that both fusion proteins were localized in the cytoplasm and on discrete microdomains in the plasma membrane. The extent of labeling with anti-HERG antibodies of HEK 293 cells expressing EGFP/HERG channels was less when compared to HERG/EGFP channels. In conclusion, both electrophysiological and immunocytochemical studies showed that EGFP/HERG channels themselves have a protein trafficking defect. HERG/EGFP channels have similar properties as untagged HERG channels and, thus, might be especially useful for fluorescence microscopy studies.
- Published
- 2008
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- View/download PDF
31. Effects of fluoroquinolones on HERG channels and on pancreatic beta-cell ATP-sensitive K+ channels.
- Author
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Zünkler BJ, Claassen S, Wos-Maganga M, Rustenbeck I, and Holzgrabe U
- Subjects
- Algorithms, Animals, Data Interpretation, Statistical, ERG1 Potassium Channel, Electrophysiology, Ether-A-Go-Go Potassium Channels drug effects, Ether-A-Go-Go Potassium Channels genetics, Humans, Insulin-Secreting Cells drug effects, KATP Channels, Patch-Clamp Techniques, Piperazines chemistry, Piperazines pharmacology, Potassium Channels, Inwardly Rectifying drug effects, Potassium Channels, Inwardly Rectifying genetics, Structure-Activity Relationship, Transfection, Ether-A-Go-Go Potassium Channels metabolism, Fluoroquinolones pharmacology, Insulin-Secreting Cells metabolism, Potassium Channels, Inwardly Rectifying metabolism
- Abstract
An inhibition of the cardiac rapid delayed rectifier K(+) current (I(Kr)) and of the ATP-sensitive K(+) (K(ATP)) current seems to be involved in the mechanisms of the cardiotoxic effects and the alterations in glucose homeostasis, respectively, induced by some fluoroquinolones. The aim of the present study was to compare the effects of fluoroquinolone derivatives on the pore-forming subunit of the cardiac I(Kr), which is encoded by human ether-a-go-go-related gene (HERG), and on the ATP-sensitive K(+) (K(ATP)) channel from the clonal insulinoma cell line RINm5F. Sparfloxacin blocked HERG currents half-maximally (IC(50) value) at a concentration of 33.2 microM, whereas norfloxacin and lomefloxacin each tested at a concentration of 300 microM inhibited HERG currents only by 2.8+/-3.6% and 12.3+/-4.7%, respectively. Four newly synthesized fluoroquinolone derivatives with either a p-fluoro-phenyl (compound C3) or an o-fluoro-phenyl (compound C4) substituent at position N(1) and an additional dimethylated piperazine ring (compounds C1 and C2) inhibited HERG currents by 7.3-14.7% at test concentrations of 100 microM. The rank order of potency for the inhibition of K(ATP) currents was C2>C1, C4, sparfloxacin>C3. In conclusion, the structural requirements for fluoroquinolones to inhibit I(Kr) currents and K(ATP) currents appear to differ. The amino group at position C(5) seems to be primarily responsible for the strong HERG current blocking property of sparfloxacin. In contrast, for the block of pancreatic beta-cell K(ATP) currents by fluoroquinolones the substituents at positions N(1), C(7) and C(8) all might play a role.
- Published
- 2006
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- View/download PDF
32. Comparison of the effects of metoclopramide and domperidone on HERG channels.
- Author
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Claassen S and Zünkler BJ
- Subjects
- Cell Line, Dose-Response Relationship, Drug, ERG1 Potassium Channel, Ether-A-Go-Go Potassium Channels, Humans, Patch-Clamp Techniques, Antiemetics toxicity, Domperidone toxicity, Metoclopramide toxicity, Potassium Channels, Voltage-Gated antagonists & inhibitors
- Abstract
Torsades de pointes (TdP) is a potentially fatal form of ventricular arrhythmia that occurs under conditions where cardiac repolarization is delayed (as indicated by prolonged QT intervals from electrocardiographic recordings). A likely mechanism for QT prolongation and TdP is blockade of the rapid component of the cardiac delayed rectifier K(+) current (I(Kr)), which is encoded by HERG (human ether-a-go-go-related gene). The gastroprokinetic agent cisapride is a potent blocker of HERG currents and serious cardiac arrhythmias and deaths from TdP and ventricular fibrillation have been reported in patients taking cisapride. The aim of the present study was to compare the effects of the gastroprokinetic agents domperidone and metoclopramide on HERG channels transiently expressed in human embryonic kidney (HEK 293) cells using the whole-cell configuration of the patch-clamp technique. Both domperidone and metoclopramide concentration-dependently blocked HERG currents, and the following values were calculated for IC(50) (the concentrations causing half-maximal inhibition) and n (the Hill coefficient): 57.0 nmol/l and 0.99 for domperidone, 5.4 micromol/l and 0.95 for metoclopramide. The observation that the extent of block of HERG currents by domperidone increased at more positive membrane potentials whereas block of HERG currents by metoclopramide displayed a smaller degree of voltage dependency seems to indicate that domperidone and metoclopramide have distinct binding sites on HERG channels. In conclusion, the potency for block of HERG currents is about 100-fold lower for metoclopramide when compared to domperidone., (Copyright (c) 2005 S. Karger AG, Basel)
- Published
- 2005
- Full Text
- View/download PDF
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