bromochloroacetic-acid and Hyperglycemia

Type I diabetes is characterized by destruction of insulin-producing beta-islet cells in the pancreas resulting in hyperglycemia and associated morbidity. The successful treatment of diabetes by transplanted islets has resulted in renewed efforts to identify methods to augment islet availability. One approach is to identify and expand islet precursor cells able to later differentiate into functional endocrine cells. A population of cytokeratin 19-negative, vimentin-positive, insulin-negative, glucagon-negative, and nestin-positive cells was cultured from human fetal pancreas and passaged for over 20 population doublings. These cells were stimulated to form cell aggregates when grown on poly-D-lysine (PDL)-coated surfaces and then evaluated for differentiation potential using in vivo function as a surrogate marker for the presence of differentiated precursor cells. Streptozotocin-induced diabetic SCID mice implanted with PDL-induced cell aggregates were able to maintain glucose concentrations below 200 mg/dL for over 70 days (n = 5). In addition, human C-peptide was detectable in implanted animals but not in control animals. These findings show that a population of human fetal pancreas-derived cells (1) can be cultured and expanded in vitro, (2) can maintain the ability to differentiate into beta-islet-like cells, and (3) can correct hyperglycemia in a mouse model of diabetes. Further improvements in isolation, culture, and differentiation of human pancreas-derived beta-cell precursors may one day help to provide a novel source of islets for use in transplantation therapy to treat type I diabetes.

Topics: Animals; Biomarkers; Cell Differentiation; Cell Separation; Clone Cells; Diabetes Mellitus, Experimental; Fetal Tissue Transplantation; Glucagon; Humans; Hyperglycemia; Insulin; Intermediate Filament Proteins; Islets of Langerhans; Keratins; Mice; Mice, SCID; Nerve Tissue Proteins; Nestin; Pancreas; Polylysine; Stem Cell Transplantation; Streptozocin; Transplantation, Heterologous; Vimentin

The aim of this work was to study the effect of induced hyperglycemia on islet cell mass and insulin secretion in normal toads. Immunolabeled beta cell area, replication (bromodeoxyuridine) and apoptosis (propidium iodide) rate, islet neogenesis (cytokeratin), and insulin secretion in vitro were measured in adult male specimens of Bufo arenarum during and after interruption of the injection of either a 50% glucose solution (2 g/100 g) or its vehicle for 4 days. Glucose administration caused hyperglycemia (122.6 +/- 16.7 and 508.3 +/- 115.9 mg/dl vs 23.5 +/- 1.26 and 22.8 +/- 1.8 mg/dl, at days 3 and 5, respectively, P < 0.05) and a significant decrease in the number of islets/mm(2) (day 3: 9.7 +/- 0.9 vs 3.3 +/- 0.4, P < 0.05; day 5: 9.4 +/- 0.8 vs 7.4 +/- 0.6; day 9: 9.6 +/- 0.9 vs 6.2 +/- 0.4, P < 0.05) and in the percentage of immunolabeled beta cell area (day 3: 2.07 +/- 0.2 vs 0.5 +/- 0.1%, P < 0.05; day 5: 1.8 +/- 0.1 vs 0.6 +/- 0.1%; day 9: 1.7 +/- 0.1 vs 0.7 +/- 0.1%, P < 0.05). Glucose-injected animals had a simultaneous significantly higher percentage of BrdU-labeled beta cells (day 3: 0.46 +/- 0.02 vs 0.23 +/- 0.03%; day 5: 0.54 +/- 0.13 vs 0.22 +/- 0.02%; day 9: 0.61 +/- 0.0 vs 0.27 +/- 0.05%, P < 0.05) and cytokeratin-labeled endocrine cells (day 3: 0.21 +/- 0.06 vs 0.01 +/- 0.00%; day 5: 0.17 +/- 0.06 vs 0.01 +/- 0.01%; day 9: 1.25 +/- 0.2 vs 0.01 +/- 0.008%, P < 0.05) and a higher rate of apoptotic beta cells (day 3: 0.14 +/- 0.04 vs 0.05 +/- 0.02%; day 5: 0.4 +/- 0.06 vs 0.05 +/- 0.2, P < 0.05; day 9: 0.47 +/- 0.04 vs 0.06 +/- 0.03, P < 0.05). Comparable amounts of insulin were secreted in vitro by both groups in response to 2 mM glucose, whereas there was a significantly reduced response to 8 mM glucose in treated animals (day 3: 73 +/- 12 vs 165 +/- 20%; day 5: 74 +/- 11 vs 204 +/- 18%, P < 0.05). This decreased response to high glucose reverted to normal after removal of the glucose injection. These results show for the first time that short-term hyperglycemia triggers marked morphological and transient secretory changes in the toad pancreas similar in part to those elicited in the pancreas of several mammals. As with other results previously reported, these results support the usefulness of the toad as an alternative easily handled model to study the growth and secretory function of the endocrine pancreas.

Topics: Animals; Apoptosis; Blood Glucose; Bufo arenarum; Cell Division; Fluorescent Antibody Technique; Glucose; Hyperglycemia; Immunohistochemistry; Insulin; Insulin Secretion; Islets of Langerhans; Keratins

We propose a new indicator for diabetic control that shows the extent of glycation of hair protein (keratin), the glycation index (A(390)/A(412)) which is based on the ratio of glycated protein- to cystine-induced coloration, where A(390) and A(412) represent each absorbance in the color reactions of glycated protein and cystine in the hair protein. Samples can be quickly and non-invasively collected and easily stored. This index for the back and scalp hairs from hypercholesterolemic mice with hyperglycemia, diabetic rats and diabetic patients gave significantly higher values (2.0-6.0-fold) than those of normal subjects (p<0.01). The glycation indices (mean + or - S.D.) of hairs from diabetic and non-diabetic subjects were 3.00 + or - 0.96 (n = 21) and 1.51 + or - 0.45 (n = 30), respectively. These indices (y) correlated well with the levels of glycohemoglobin (HbA(1c), chi) in diabetic and non-diabetic subjects: y = 0.69 chi- 2.03 (r = 0.82, n = 31, p<0.01). Within-run precision (reproducibility, CV) for the assay of the glycation indices of hairs from the three groups was 6.7-9.4% (n = 10 each). The proposed glycation index of hair gave reasonable results for animals and humans with normo- and hyperglycemia, suggesting that it is reliable and can be diagnostically useful.

Topics: Animals; Blood Glucose; Cystine; Diabetes Mellitus; Glycated Hemoglobin; Glycation End Products, Advanced; Hair; Humans; Hyperglycemia; Keratins; Mice; Rats