21 results on '"Granfeldt D"'
Search Results
2. Cost-of-Illness of Acromegaly in Sweden – A Register-Linkage Population-Based Study
- Author
-
Lesén, E, primary, Granfeldt, D, additional, Houchard, A, additional, Dinet, J, additional, Berthon, A, additional, Olsson, DS, additional, Björholt, I, additional, and Johannsson, G, additional
- Published
- 2016
- Full Text
- View/download PDF
3. The Cost Effectiveness of Delayed-Release Dimethyl Fumarate Versus Interferon Beta-1b In A Swedish Setting
- Author
-
Granfeldt, D, primary, Björstad, Å, additional, Öhrman, S, additional, and Björholt, I, additional
- Published
- 2015
- Full Text
- View/download PDF
4. PCN91 - Cost-of-Illness of Metastatic Gastroenteropancreatic Neuroendocrine Tumours In Sweden – A Register-Linkage Population-Based Study
- Author
-
Lesén, E, Granfeldt, D, Houchard, A, Berthon, A, Dinet, J, Björstad, Å, Björholt, I, Elf, A, and Johanson, V
- Published
- 2016
- Full Text
- View/download PDF
5. PDB25 - Cost-of-Illness of Acromegaly in Sweden – A Register-Linkage Population-Based Study
- Author
-
Lesén, E, Granfeldt, D, Houchard, A, Dinet, J, Berthon, A, Olsson, DS, Björholt, I, and Johannsson, G
- Published
- 2016
- Full Text
- View/download PDF
6. A chemical waveform synthesizer
- Author
-
Olofsson, J., primary, Bridle, H., additional, Sinclair, J., additional, Granfeldt, D., additional, Sahlin, E., additional, and Orwar, O., additional
- Published
- 2005
- Full Text
- View/download PDF
7. Neutrophil secretion induced by an intracellular Ca2+ rise and followed by whole-cell patch-clamp recordings occurs without any selective mobilization of different granule populations.
- Author
-
Granfeldt D, Harbecke O, Björstad A, Karlsson A, and Dahlgren C
- Published
- 2006
- Full Text
- View/download PDF
8. PND52 - The Cost Effectiveness of Delayed-Release Dimethyl Fumarate Versus Interferon Beta-1b In A Swedish Setting
- Author
-
Granfeldt, D, Björstad, Å, Öhrman, S, and Björholt, I
- Published
- 2015
- Full Text
- View/download PDF
9. Erratum to "Individualized metal implants for focal cartilage lesions in the knee can be cost-effective: a simulation on 47-year-old in a Swedish setting" [J ISAKOS 8 (2023) 197-203].
- Author
-
Bernfort L, Granfeldt D, and Ryd L
- Published
- 2023
- Full Text
- View/download PDF
10. Individualized metal implants for focal cartilage lesions in the knee can be cost-effective: A simulation on 47-year-old in a Swedish setting.
- Author
-
Bernfort L, Granfeldt D, and Ryd L
- Subjects
- Humans, Aged, Middle Aged, Sweden epidemiology, Cost-Benefit Analysis, Knee Joint surgery, Quality of Life, Cartilage
- Abstract
Objectives: In the aging population, the knee is the joint most commonly causing impaired function and incapacity. While definite treatment by prosthetic replacement is often performed late, symptomatic knee cartilage lesions cause much suffering also in younger ages. Early intervention could, therefore, be instituted at an early stage to the benefit of both patients and society. Small, metal surface, resurfacing implants have been tested with promising results. A system that features patient-specific implants and surgical instruments shows good clinical results and favorable survival rates. This study aims to assess the cost utility of this metal device compared with microfracture (MFX), being the standard procedure in Sweden., Methods: We constructed a simulation model in Excel. In the model, a cohort of 47-year-old patients (which is the mean age of patients treated with the metal implant) with symptomatic knee cartilage lesions received either MFX or metal implantation. Outcomes for the cohort were simulated over 40 years, such as in a previously published model based on MFX, and sensitivity analyses (deterministic and probabilistic) of the results were undertaken. Data on transition probabilities, costs, and quality of life were taken from clinical data, published literature, and official price lists. Only direct medical costs were included., Results: Results from the analysis showed that the metal device is a cost-effective treatment strategy compared with MFX. The incremental cost-effectiveness ratio (ICER) reached acceptable levels at ∼5 years postoperatively. Over the full-time horizon of 40 years, the metal device was cost saving with concomitant gains in quality-adjusted life years (QALYs), translating to a dominant treatment strategy. Results were robust according to sensitivity analysis with the initial success rate of up to three years for both metal and MFX having the largest impact., Conclusions: A metal implant may be a cost-effective treatment alternative for patients in their 40's when compared to MFX in a Swedish setting., Level of Evidence: 5 [1]., (Copyright © 2023 The Author(s). Published by Elsevier Inc. All rights reserved.)
- Published
- 2023
- Full Text
- View/download PDF
11. Carpal tunnel syndrome in acromegaly: a nationwide study.
- Author
-
Vouzouneraki K, Esposito D, Mukka S, Granfeldt D, Ragnarsson O, Dahlqvist P, and Olsson DS
- Subjects
- Acromegaly complications, Adult, Aged, Carpal Tunnel Syndrome complications, Cohort Studies, Comorbidity, Female, Humans, Incidence, Male, Middle Aged, Registries, Retrospective Studies, Sweden epidemiology, Acromegaly epidemiology, Carpal Tunnel Syndrome epidemiology
- Abstract
Objective: Carpal tunnel syndrome (CTS) is common in patients with acromegaly, with a reported prevalence of 19-64%. We studied CTS in a large national cohort of patients with acromegaly and the temporal relationship between the two diagnoses., Design: Retrospective, nationwide, cohort study including patients diagnosed with acromegaly in Sweden, 2005-2017, identified in the Swedish Healthcare Registries., Methods: CTS (diagnosis and surgery in specialised healthcare) was analysed from 8.5 years before the diagnosis of acromegaly until death or end of the study. Standardised incidence ratios (SIRs) with 95% CIs were calculated for CTS with the Swedish population as reference., Results: The analysis included 556 patients with acromegaly (50% women) diagnosed at mean (s.d.) age 50.1 (15.0) years. During the study period, 48 patients were diagnosed with CTS and 41 patients underwent at least one CTS surgery. In the latter group, 35 (85%) were operated for CTS before the acromegaly diagnosis; mean interval (range) 2.2 (0.3-8.5) years and the SIR for having CTS surgery before the diagnosis of acromegaly was 6.6 (4.8-8.9). Women with acromegaly had a higher risk for CTS than men (hazard ratio: 2.5, 95% CI: 1.3-4.7)., Conclusions: Patients with acromegaly had a 6-fold higher incidence for CTS surgery before the diagnosis of acromegaly compared with the general population. The majority of patients with both diagnoses were diagnosed with CTS prior to acromegaly. Increased awareness of signs of acromegaly in patients with CTS might help to shorten the diagnostic delay in acromegaly, especially in women.
- Published
- 2021
- Full Text
- View/download PDF
12. Treatment Patterns and Survival among Patients with Metastatic Gastroenteropancreatic Neuroendocrine Tumours in Sweden - a Population-based Register-linkage and Medical Chart Review Study.
- Author
-
Lesén E, Granfeldt D, Berthon A, Dinet J, Houchard A, Myrenfors P, Björstad Å, Björholt I, Elf AK, and Johanson V
- Abstract
Background: Gastroenteropancreatic neuroendocrine tumours (GEP-NETs) are neoplasms derived from the endocrine system in the gastrointestinal tract and pancreas. Treatment options include surgery; pharmacological treatments like somatostatin analogues (SSA), interferon alpha, molecular targeted therapy and chemotherapy; and peptide receptor radionuclide therapy. The objective of this study was to describe treatment patterns and survival among patients with metastatic GEP-NET grade 1 or 2 in Sweden. Methods: Data was obtained via linkage of nationwide registers. Patients diagnosed with metastatic GEP-NET grade 1 or 2 in Sweden between 2005 and 2013 were included (n=811; National population). In addition, medical chart review was performed for the subpopulation diagnosed at Sahlgrenska University Hospital, Gothenburg (n=127; Regional population). Treatment patterns, including treatment sequences, and overall survival were assessed. Results: Most patients had small intestinal NET (76%). In the regional population, 72% had grade 1 tumours; 50% had functioning tumours. The two most common first-line treatments were surgery (57%) and SSA (25%). After first-line surgery, 46% received SSA, while 40% had no further treatment. After first-line SSA, 52% received surgery, while 27% had no further treatment. Overall median survival time from date of diagnosis was 7.0 years (95% CI 6.2-not reached). Among patients with distant metastases, pancreatic NET (vs. small intestinal NET) was associated with poorer survival (HR 1.9; 95% CI 1.1-3.3), as were liver metastases (HR 3.2; 95% CI 1.5-7.0). Conclusions: First-line surgery was typically followed by SSA or no further treatment. Among patients with distant metastases, pancreatic NET or liver metastases were associated with a poorer survival., Competing Interests: Competing Interests: EL and IB were employed by PharmaLex Sweden at the time of the execution of this study and when the manuscript was prepared. DG and ÅB are employed by PharmaLex Sweden. PharmaLex Sweden is a consultancy and research company working with the pharmaceutical and medical device industry as well as with health care organisations and with universities. AB, JD and PM were employed by Ipsen at the time of the execution of this study and when the manuscript was prepared. AH is employed by Ipsen. VJ and A-KE were not financially compensated by Ipsen for work done in this study. The authors have no other competing interests to report. Substantial contributions to study conception/design, or acquisition/analysis/interpretation of data: [EL, DG, AB, JD, AH, IB, A-KE, and VJ]; Drafting of the publication, or revising it critically for important intellectual content: [EL, DG, AB, AH, PM, ÅB, A-KE, and VJ]; Final approval of the publication: [EL, DG, AB, JD, AH, PM, ÅB, IB, A-KE, and VJ]., (© The author(s).)
- Published
- 2019
- Full Text
- View/download PDF
13. Cost-of-illness of metastatic gastroenteropancreatic neuroendocrine tumours in Sweden-A population-based register-linkage study.
- Author
-
Lesén E, Granfeldt D, Houchard A, Berthon A, Dinet J, Gabriel S, Björstad Å, Björholt I, Elf AK, and Johanson V
- Subjects
- Female, Health Care Costs, Health Expenditures statistics & numerical data, Humans, Intestinal Neoplasms epidemiology, Intestinal Neoplasms therapy, Male, Malignant Carcinoid Syndrome economics, Malignant Carcinoid Syndrome epidemiology, Malignant Carcinoid Syndrome therapy, Middle Aged, Neoplasm Metastasis, Neuroendocrine Tumors epidemiology, Neuroendocrine Tumors therapy, Pancreatic Neoplasms epidemiology, Pancreatic Neoplasms therapy, Patient Acceptance of Health Care statistics & numerical data, Registries, Stomach Neoplasms epidemiology, Stomach Neoplasms therapy, Sweden epidemiology, Cost of Illness, Intestinal Neoplasms economics, Neuroendocrine Tumors economics, Pancreatic Neoplasms economics, Stomach Neoplasms economics
- Abstract
The objective was to estimate the cost-of-illness of grades 1 and 2 metastatic gastroenteropancreatic neuroendocrine tumours (GEP-NETs) in Sweden in 2013 in a population-based study including all patients diagnosed between 2005 and 2013. Data were obtained from national registers, and patients who utilised healthcare resources due to metastatic GEP-NETs in 2013 were included. The study included 478 patients (mean age 64 [SD=11] years, 51% men). The majority (80%) had small intestinal NET, 10% had pancreatic NET, and 41% had carcinoid syndrome. The total cost-of-illness was €12,189,000 in 2013, of which direct costs constituted 77% and costs from production loss constituted 22%. The largest contributor to the direct medical costs was prescription drugs (54%; primarily somatostatin analogues [91% of the total drug cost]). Production loss due to sickness absence constituted 52% of the total costs of production loss. The total annual cost per patient was €25,500. By patient group, the cost was €24,800 (95% CI €21,600-€28,100) for patients with small intestinal NET, €37,300 (95% CI €23,300-€51,300) for those with pancreatic NET and €18,600 (95% CI €12,600-€24,500) for patients with other GEP-NETs. To conclude, the total annual cost of grades 1 and 2 metastatic GEP-NETs in Sweden was €25,500 per patient and year., (© 2019 John Wiley & Sons Ltd.)
- Published
- 2019
- Full Text
- View/download PDF
14. Decreasing mortality and changes in treatment patterns in patients with acromegaly from a nationwide study.
- Author
-
Esposito D, Ragnarsson O, Granfeldt D, Marlow T, Johannsson G, and Olsson DS
- Subjects
- Acromegaly epidemiology, Acromegaly etiology, Acromegaly mortality, Adenoma metabolism, Adenoma mortality, Adenoma physiopathology, Adult, Aged, Cohort Studies, Combined Modality Therapy, Female, Follow-Up Studies, Growth Hormone-Secreting Pituitary Adenoma metabolism, Growth Hormone-Secreting Pituitary Adenoma mortality, Growth Hormone-Secreting Pituitary Adenoma physiopathology, Health Care Surveys, Humans, Hypopituitarism epidemiology, Hypopituitarism etiology, Hypopituitarism mortality, Hypopituitarism prevention & control, Male, Middle Aged, Mortality, Prevalence, Registries, Sex Factors, Sweden epidemiology, Acromegaly prevention & control, Adenoma therapy, Growth Hormone-Secreting Pituitary Adenoma therapy, Health Transition, Human Growth Hormone metabolism, Practice Patterns, Physicians' trends
- Abstract
Context: New therapeutic strategies have developed for the management of acromegaly over recent decades. Whether this has improved mortality has not been fully elucidated., Objective: The primary aim was to investigate mortality in a nationwide unselected cohort of patients with acromegaly. Secondary analyses included time trends in mortality and treatment patterns., Design: A total of 1089 patients with acromegaly were identified in Swedish National Health Registries between 1987 and 2013. To analyse time trends, the cohort was divided into three periods (1987-1995, 1996-2004 and 2005-2013) based on the year of diagnosis., Main Outcome Measures: Using the Swedish population as reference, standardized mortality ratios (SMRs) were calculated with 95% confidence intervals (CIs)., Results: Overall SMR was 2.79 (95% CI: 2.43-3.15) with 232 observed and 83 expected deaths. Mortality was mainly related to circulatory diseases (SMR: 2.95, 95% CI: 2.35-3.55), including ischemic heart disease (2.00, 1.35-2.66) and cerebrovascular disease (3.99, 2.42-5.55) and malignancy (1.76, 1.27-2.26). Mortality decreased over time, with an SMR of 3.45 (2.87-4.02) and 1.86 (1.04-2.67) during the first and last time period, respectively ( P = .015). During the same time periods, the frequency of pituitary surgery increased from 58% to 72% ( P < 0.001) and the prevalence of hypopituitarism decreased from 41% to 23% ( P < 0.001)., Conclusions: Excess mortality was found in this nationwide cohort of patients with acromegaly, mainly related to circulatory and malignant diseases. Although still high, mortality significantly declined over time. This could be explained by the more frequent use of pituitary surgery, decreased prevalence of hypopituitarism and the availability of new medical treatment options., (© 2018 European Society of Endocrinology.)
- Published
- 2018
- Full Text
- View/download PDF
15. Comorbidities, treatment patterns and cost-of-illness of acromegaly in Sweden: a register-linkage population-based study.
- Author
-
Lesén E, Granfeldt D, Houchard A, Dinet J, Berthon A, Olsson DS, Björholt I, and Johannsson G
- Subjects
- Acromegaly drug therapy, Acromegaly economics, Acromegaly pathology, Adult, Aged, Comorbidity, Cost of Illness, Diabetes Mellitus drug therapy, Diabetes Mellitus economics, Diabetes Mellitus epidemiology, Diabetes Mellitus pathology, Female, Humans, Hypertension drug therapy, Hypertension economics, Hypertension epidemiology, Hypertension pathology, Male, Middle Aged, Sweden, Acromegaly epidemiology
- Abstract
Objective: Acromegaly is a complex endocrine disease with multiple comorbidities. Treatment to obtain biochemical remission includes surgery, medical therapy and radiation. We aimed to describe comorbidities, treatment patterns and cost-of-illness in patients with acromegaly in Sweden., Design: A nationwide population-based study., Methods: Patients with acromegaly were identified and followed in national registers in Sweden. Longitudinal treatment patterns were assessed in patients diagnosed between July 2005 and December 2013. The cost-of-illness during 2013 was estimated from a societal perspective among patients diagnosed between 1987 and 2013., Results: Among 358 patients with acromegaly (48% men, mean age at diagnosis 50.0 (s.d. 15.3) years) at least one comorbidity was reported in 81% (n = 290). The most common comorbidities were hypertension (40%, n = 142), neoplasms outside the pituitary (30%, n = 109), hypopituitarism (22%, n = 80) and diabetes mellitus (17%, n = 61). Acromegaly treatment was initiated on average 3.7 (s.d. 6.9) months after diagnosis. Among the 301 treated patients, the most common first-line treatments were surgery (60%, n = 180), somatostatin analogues (21%, n = 64) and dopamine agonists (14%, n = 41). After primary surgery, 24% (n = 44) received somatostatin analogues. The annual per-patient cost was €12 000; this was €8700 and €16 000 if diagnosed before or after July 2005, respectively. The cost-of-illness for acromegaly and its comorbidities was 77% from direct costs and 23% from production loss., Conclusions: The prevalence of comorbidity is high in patients with acromegaly. The most common first-line treatment in acromegalic patients was surgery followed by somatostatin analogues. The annual per-patient cost of acromegaly and its comorbidities was €12 000., (© 2017 European Society of Endocrinology.)
- Published
- 2017
- Full Text
- View/download PDF
16. Inhibition of phospholipase A(2) abrogates intracellular processing of NADPH-oxidase derived reactive oxygen species in human neutrophils.
- Author
-
Björnsdottir H, Granfeldt D, Welin A, Bylund J, and Karlsson A
- Subjects
- Carcinogens pharmacology, Cells, Cultured, Electric Capacitance, Enzyme Inhibitors pharmacology, Flow Cytometry, Humans, Hydrogen Peroxide metabolism, NADP metabolism, Neutrophils cytology, Neutrophils drug effects, Oxidation-Reduction, Peroxidase metabolism, Phospholipases A2 metabolism, Superoxides metabolism, Tetradecanoylphorbol Acetate pharmacology, Cell Membrane metabolism, NADPH Oxidases metabolism, Neutrophils metabolism, Phospholipase A2 Inhibitors, Reactive Oxygen Species metabolism
- Abstract
Upon activation of human neutrophils, superoxide can be produced at two cellular sites; either in the plasma membrane, giving extracellular release of oxidants, or in intracellular organelles, resulting in oxidants being retained in the cell. The involvement of phospholipase A(2) (PLA(2)) in phorbol myristate acetate (PMA)-induced activation of the two pools of NADPH-oxidase was investigated using a variety of PLA(2) inhibitors and the oxidase activity was measured by luminol/isoluminol-amplified chemiluminescence (CL). Two of the seven inhibitors were without effect, two inhibitors inhibited both intra- and extracellular ROS production equally, and three inhibitors inhibited intracellular but not extracellular CL. Using another technique to measure ROS, PHPA oxidation, we found that intracellular ROS production was unaltered with the three last inhibitors, indicating that PLA(2) is not involved in the NADPH-oxidase activity per se, but in the intracellular processing of the radicals necessary for the CL reaction to take place. The PLA(2) inhibitors did not abolish the activity of myeloperoxidase (MPO), an enzyme necessary for intracellular CL to occur. Instead, we suggest that these PLA(2) inhibitors block heterotypic granule fusion and prohibit the colocalization of ROS and MPO needed for intracellular CL activity., (Copyright © 2013 Elsevier Inc. All rights reserved.)
- Published
- 2013
- Full Text
- View/download PDF
17. Controlling desensitized states in ligand-receptor interaction studies with cyclic scanning patch-clamp protocols.
- Author
-
Granfeldt D, Sinclair J, Millingen M, Farre C, Lincoln P, and Orwar O
- Subjects
- Animals, Cell Line, Electrophysiology, Kinetics, Ligands, Protein Binding, Rats, Patch-Clamp Techniques methods, Receptors, GABA-A metabolism, beta-Alanine metabolism, gamma-Aminobutyric Acid metabolism
- Abstract
Ligand-gated ion channels are important control elements in regulation of cellular activities, and increasing evidence demonstrates their role as therapeutic targets. The receptors display complex desensitization kinetics, occurring on vastly different time scales. This is not only important in biology and pharmacology but might also be of technological significance since populations of receptors under microfluidic control can function analogously to DRAM memory circuits. Using a novel microfluidic method, and computer modeling of the receptor state distributions, we here demonstrate that GABAA receptor populations can be controlled to display high or low EC50 values, depending on input function (i.e., the exact pattern of agonist application). The sensitivity of the receptors can be tuned up to 40-fold (beta-alanine) by the particular agonist exposure pattern. By combining patch-clamp experiments with computer modeling of receptor state distributions, we can control the assembly of receptors in desensitized states. The technique described can be used as an analytical tool to study the effect of desensitization on the activity of ion channel effectors. We describe the differential blocking effect of the competitive antagonist bicuculline on the high- and low-EC50 GABAA receptor preparations and conclude that the inhibition is dramatically dependent on how the different desensitized states are populated. Furthermore, we show that both GABA and beta-alanine, two agonists with different affinity but similar efficacy, induce the same type of desensitization behavior and memory effects in GABAA receptors.
- Published
- 2006
- Full Text
- View/download PDF
18. A biohybrid dynamic random access memory.
- Author
-
Sinclair J, Granfeldt D, Pihl J, Millingen M, Lincoln P, Farre C, Peterson L, and Orwar O
- Subjects
- Animals, Cell Line, Humans, Kinetics, Patch-Clamp Techniques methods, Rats, gamma-Aminobutyric Acid chemistry, Ion Channels chemistry, Microfluidic Analytical Techniques methods, Receptors, GABA-A chemistry
- Abstract
We report that GABA(A) receptors in a patch-clamped biological cell form a short-term memory circuit when integrated with a scanning-probe microfluidic device. Laminar patterns of receptor activators (agonists) provided by the microfluidic device define and periodically update the data input which is read and stored by the receptors as state distributions (based on intrinsic multistate kinetics). The memory is discharged over time and lasts for seconds to minutes depending on the input function. The function of the memory can be represented by an equivalent electronic circuit with striking similarity in function to a dynamic random access memory (DRAM) used in electronic computers. Multiplexed biohybrid memories may form the basis of large-scale integrated biocomputational/sensor devices with the curious ability to use chemical signals including odorants, neurotransmitters, chemical and biological warfare agents, and many more as input signals.
- Published
- 2006
- Full Text
- View/download PDF
19. Reactivation of formyl peptide receptors triggers the neutrophil NADPH-oxidase but not a transient rise in intracellular calcium.
- Author
-
Bylund J, Björstad A, Granfeldt D, Karlsson A, Woschnagg C, and Dahlgren C
- Subjects
- Androstadienes pharmacology, Antigens, CD chemistry, Antigens, CD metabolism, Cytochalasin B pharmacology, Cytoskeleton drug effects, Cytoskeleton enzymology, Enzyme Activation drug effects, Enzyme Activation physiology, Enzyme Inhibitors pharmacology, GTP-Binding Proteins metabolism, HL-60 Cells, Humans, Platelet Membrane Glycoproteins chemistry, Platelet Membrane Glycoproteins metabolism, Protein Structure, Tertiary, Receptor, Anaphylatoxin C5a, Receptors, Cell Surface chemistry, Receptors, Cell Surface metabolism, Receptors, Complement chemistry, Receptors, Complement metabolism, Receptors, Formyl Peptide, Receptors, Immunologic chemistry, Receptors, Interleukin-8A chemistry, Receptors, Interleukin-8A metabolism, Receptors, Interleukin-8B chemistry, Receptors, Interleukin-8B metabolism, Receptors, Peptide chemistry, Signal Transduction drug effects, Signal Transduction physiology, Wortmannin, Calcium metabolism, NADPH Oxidases metabolism, Neutrophils enzymology, Receptors, G-Protein-Coupled, Receptors, Immunologic metabolism, Receptors, Peptide metabolism
- Abstract
In neutrophils, coupling of chemoattractants to their cell surface receptor at low temperature (
- Published
- 2003
- Full Text
- View/download PDF
20. Capacitative Ca2+ influx and activation of the neutrophil respiratory burst. Different regulation of plasma membrane- and granule-localized NADPH-oxidase.
- Author
-
Granfeldt D, Samuelsson M, and Karlsson A
- Subjects
- Calcium Channels physiology, Egtazic Acid pharmacology, Enzyme Activation, Lanthanum pharmacology, Thapsigargin pharmacology, Calcium metabolism, Cell Membrane enzymology, Cytoplasmic Granules enzymology, NADPH Oxidases metabolism, Neutrophils metabolism, Respiratory Burst, Signal Transduction
- Abstract
The neutrophil NADPH-oxidase may be activated in the plasma membrane, resulting in release of oxygen metabolites extracellularly, or in the granule or phagosomal membranes, giving intracellular production of oxidants. An increase in [Ca2+]i mediated through binding of fMLF to its receptor is part of a signaling cascade that activates the plasma membrane-localized oxidase. In contrast, a rise in [Ca2+]i induced by a Ca2+ ionophore results in activation of the intracellular pool of oxidase. We mimicked fMLF-induced emptying of intracellular Ca2+ stores with thapsigargin. This induced a pronounced intracellular oxidase activity but no extracellular release of oxidants. The thapsigargin-induced effect was dependent on capacitative Ca2+ influx, because the effect was inhibited dose-dependently by EGTA and the Ca2+ channel blocker La3+. At La3+ concentrations between 200 and 400 microM, thapsigargin also induced a massive extracellular production of superoxide anion. No other channel blockers tested induced a similar effect. We conclude that elevation in [Ca2+]i by capacitative Ca2+ influx induces NADPH-oxidase activation at an intracellular site. Further, activation of the plasma membrane-localized NADPH-oxidase is regulated by a more complex Ca2+ signaling, involving capacitative Ca2+ influx and possibly the specific action of La3+-sensitive Ca2+ channels.
- Published
- 2002
21. An intact cytoskeleton is required for prolonged respiratory burst activity during neutrophil phagocytosis.
- Author
-
Granfeldt D and Dahlgren C
- Subjects
- Adult, Humans, In Vitro Techniques, Kinetics, Luminescent Measurements, NADPH Oxidases metabolism, Reactive Oxygen Species metabolism, Saccharomyces cerevisiae immunology, Cytoskeleton metabolism, Neutrophils immunology, Neutrophils metabolism, Phagocytosis physiology, Respiratory Burst
- Abstract
The temporal relationship between phagocytosis and respiratory burst activity was investigated. Neutrophil uptake of yeast particles was synchronized and the kinetics of the oxidative burst was determined using an isoluminol/luminol amplified chemiluminescence system. The reactive oxygen species were mainly generated intracellularly (defined as the activity that remained in an luminol-enhanced system in the presence of superoxide dismutase and catalase). Following phagocytosis, the intracellular response rapidly reached a level close to the maximum and the activity was almost constant for the first 10 to 15 min. The response then slowly declined. The presence of cytochalasin B, an inhibitor of actin polymerization, greatly reduced the respiratory burst activity, and this was true also when the inhibitor was added after completion of uptake of yeast particles. Our results thus show that there is a continuous production of oxygen metabolites long after phagocytosis is completed. There is also a requirement for an intact cytoskeleton for prolonged superoxide production inside the phagosome.
- Published
- 2001
- Full Text
- View/download PDF
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.