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Glucose Stimulation (glucose + stimulation)

Distribution by Scientific Domains

Medical Sciences	33%
Life Sciences	33%

Selected Abstracts

Improved Outcomes in Islet Isolation and Transplantation by the Use of a Novel Hemoglobin-based O2 Carrier

AMERICAN JOURNAL OF TRANSPLANTATION, Issue 12 2006
J. G. Avila
During isolation, islets are exposed to warm ischemia. In this study, intraductal administration of oxygenated polymerized, stroma-free hemoglobin-pyridoxalated (Poly SFH-P) was performed to improve O2 delivery. Rat pancreata subjected to 30-min warm ischemia were perfused intraductally with collagenase in oxygenated Poly SFH-P/RPMI or RPMI (control). PO2 was increased by Poly SFH-P (381.7 ± 35.3 mmHg vs. 202.3 ± 28.2, p = 0.01) and pH maintained within physiological range (7.4,7.2 vs. 7.1,6.6, p = 0.009). Islet viability (77%± 4.6 vs. 63%± 4.7, p = 0.04) was improved and apoptosis lower with Poly SFH-P (caspase-3: 34,714 ± 2167 vs. 45,985 ± 1382, respectively, p = 0.01). Poly SFH-P improved islet responsiveness to glucose as determined by increased intracellular Ca2+ levels and improved insulin secretion (SI 5.4 ± 0.1 vs. 3.1 ± 0.2, p = 0.03). Mitochondrial integrity was improved in Poly SFH-P-treated islets, which showed higher percentage change in membrane potential after glucose stimulation (14.7%± 1.8 vs. 9.8 ± 1.4, respectively, p < 0.05). O2 delivery by Poly SFH-P did not increase oxidative stress (GSH 7.1 ± 2.9 nm/mg protein for Poly SFH-P vs. 6.8 ± 2.4 control, p = 0.9) or oxidative injury (MDA 1.8 ± 0.9 nmol/mg protein vs. 6.2 ± 2.4, p = 0.19). Time to reach normoglycemia in transplanted diabetic nude mice was shorter (1.8 ± 0.4 vs. 7 ± 2.5 days, p = 0.02), and glucose tolerance improved in the Poly SFH-P group (AUC 8106 ± 590 vs. 10,863 ± 946, p = 0.03). Oxygenated Poly SFH-P improves islet isolation and transplantation outcomes by preserving mitochondrial integrity. [source]

Effects of strong static magnetic fields used in magnetic resonance imaging on insulin-secreting cells

BIOELECTROMAGNETICS, Issue 1 2009
Tomonori Sakurai
Abstract The magnetic flux density of MRI for clinical diagnosis has been steadily increasing. However, there remains very little biological data regarding the effect of strong static magnetic fields (SMFs) on human health. To evaluate the effects of strong SMFs on biological systems, we cultured insulin-secreting cells under exposure to sham and SMF conditions (3,10 T of magnetic flux density, and 0,41.7 T/m of magnetic field gradient) for 0.5 or 1 h, and analyzed insulin secretion, mRNA expression, glucose-stimulated insulin secretion, insulin content, cell proliferation and cell number. Exposure to SMF with a high magnetic field gradient for 1 h significantly increased insulin secretion and insulin 1 mRNA expression. Exposure to SMF with a high magnetic flux density for 0.5 h significantly enhanced responsiveness to glucose stimulation. Exposure to SMF did not affect the insulin content, cell proliferation or cell number. Our results suggested that MRI systems with a higher magnetic flux density might not cause cell proliferative or functional damages on insulin-secreting cells, and that SMF with a high magnetic field gradient might be used clinically after thorough in vivo investigations are conducted. Bioelectromagnetics 30:1,8, 2009. © 2008 Wiley-Liss, Inc. [source]

Noncompartmental pharmacokinetics analysis of glucose-stimulated insulin response in African,American and Caucasian youths

BIOPHARMACEUTICS AND DRUG DISPOSITION, Issue 3 2009
Lanyi Xie
Abstract The objective of this study was to examine the differences in glucose and insulin responses between African,American and Caucasian youths and to determine the associations of between-group differences with sex, body mass index (BMI) and pubertal status using a noncompartmental pharmacokinetic approach. Sixteen African,American and 22 Caucasian healthy adolescents were tested using the frequently sampled intravenous glucose tolerance test. Longitudinal t -tests across each observation revealed that (1) African,American youths have higher insulin concentrations between 4 to 19,min; (2) insulin levels remained similar as subjects were grouped according to sex and pubertal status; (3) for glucose, the only difference was found as it approached steady-state basal level (>100,min) between groups with different BMIs. Linear regression showed that insulin concentrations between 4 to 19,min are associated with BMI in Caucasians. African,American youths were found to have higher insulin responses after glucose stimulation and the insulin concentrations were more related to BMI in Caucasians compared with African,Americans. BMI also has a significant effect on the glucose steady state basal level. The acute insulin response to glucose (AIRg) extended to 20,min resulted in a more significant racial difference (p<0.0006) compared with the calculation done over 10,min suggested in the past (p<0.001). Copyright © 2009 John Wiley & Sons, Ltd. [source]

Real-time detection of single-living pancreatic ,-cell by laser tweezers Raman spectroscopy: High glucose stimulation

BIOPOLYMERS, Issue 7 2010
Xi Rong
Abstract Glucose acts as a ,-cell stimulus factor and leads to cellular responses that involve a large amount of biomolecule formation, relocation, and transformation. We hypothesize that information about these changes can be obtained in real-time by laser tweezers Raman spectroscopy. To test this hypothesis, repeated measurements designs in accordance with the application of Raman spectroscopy detection were used in the current experiment. Single rat ,-cells were measured by Raman spectroscopy in 2.8 mmol/l glucose culture medium as a basal condition. After stimulation with high glucose (20 mmol/l), the same cells were measured continuously. Each cell was monitored over a total time span of 25 min, in 5 min intervals. During this period of time, cells were maintained at an appropriate temperature controlled by an automatic heater, to provide near-physiological conditions. It was found that some significant spectral changes induced by glucose were taking place during the stimulation time course. The most noticeable changes were the increase of spectral intensity at the 1002, 1085, 1445, and 1655 cm,1 peaks, mainly corresponding to protein and lipid. We speculate that these changes might have to do with ,-cell protein and lipid synthesis. Using laser tweezers Raman spectroscopy in combination with glucose stimulation, optical spectral information from rat ,-cells was received and analyzed. © 2010 Wiley Periodicals, Inc. Biopolymers 93: 587,594, 2010. This article was originally published online as an accepted preprint. The "Published Online" date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com [source]

Alginate/Aminopropyl,Silicate/Alginate Membrane Immunoisolatability and Insulin Secretion of Encapsulated Islets

BIOTECHNOLOGY PROGRESS, Issue 2 2002
Shinji Sakai
We utilized the sol,gel reaction to prepare an immunoisolatable membrane for a microcapsule-shaped bioartificial pancreas. The membrane, derived from two precursors, 3-(aminopropyl)trimethoxysilane (APTrMOS) and tetramethoxysilane (TMOS), was formed onto calcium,alginate gel beads via electrostatic interaction. The molecular weight cutoff point of less than 150 000 required for immunoisolation was achieved at molar ratios ([APTrMOS]/[TMOS]) ranging from 0.60 to 2.40 with the amount of APTrMOS fixed at 3.40 mmol/(10 mL of calcium,alginate). When encapsulated in a membrane prepared at the molar ratio of 0.60, the islets contracted in volume and showed no response to stimulation by a high glucose concentration. However, islets in a membrane prepared at the molar ratio of 2.40 showed no contraction and responded to the glucose stimulation at almost the same level as free islets. These results demonstrated that the molar ratio of the precursors was a dominant factor affecting membrane permeability and the insulin secretion activity of the encapsulated islets. [source]