PubMed Health⌕ Search

Biomedical subjects

S Baba

Publications and source records attributed to S Baba.

At least 595 records · Page 33Linked to original sources
PubMed1989

Fructose-related glycation.

We investigated in vitro the effect of the polyol pathway on the formation of advanced Maillard reaction products which have fluorescence and cross-links. Bovine serum albumin supplemented with various concentrations of glucose, fructose or sorbitol was incubated for 14 days. The fluorescence intensity was higher after incubation with fructose than after incubation with glucose. However, no significant increase in fluorescence intensity was found after incubation with sorbitol. These results suggest that in the polyol pathway fructose plays an important role in the formation of advanced Maillard products.

Fructose↗
PubMed1989

Estimation of cholesterol loading of the low-density lipoprotein fraction in diabetic subjects without ultracentrifugation.

We report here a new formula for estimating apolipoprotein (apo) B concentration in the low-density lipoprotein (LDL) fraction from measurements of plasma triglyceride and apoB. ApoB in plasma and in the triglyceride-rich lipoprotein fraction (VLDL, d less than 1.019) and plasma triglyceride were measured in 112 subjects, including 56 diabetics. There was a significant correlation between VLDL-apoB and plasma triglyceride (Y = 0.07X + 1, r = 0.73, P less than 0.001). We calculated LDL-apoB according to this formula: LDL-apoB = total apoB - (0.07 x total triglyceride + 1). We found an excellent relationship between LDL-apoB (total apoB - VLDL-apoB) and calculated LDL-apoB (Y = 1.0X + 1, r = 0.96, P less than 0.001). This new formula will enable us to estimate the apoB concentration in the LDL fraction without ultracentrifugation.

Apolipoproteins B↗
PubMed1989

[Cellular immune dysfunction in the NOD mouse: suppression of concanavalin A-induced responses in spleen cells by activated macrophages].

It is generally accepted that T lymphocyte-mediated autoimmunity contributes to the pathogenesis of Type 1 diabetes in humans and animals. Using spleen cells from nonobese diabetic (NOD) mice, a model of human Type 1 diabetes, we have analyzed the subset of T lymphocytes by flow cytometry and investigated concanavalin A (Con A)-induced interleukin 2 (IL-2) production and cell proliferation. NOD mice showed a higher percentage of Thy1.2+, L3T4+, and Lyt2+ T lymphocytes than did control ICR mice through the whole age examined. Spleen cells from a large majority of NOD mice were found to generate very low IL-2 production and cell proliferation in response to Con A. However, a few mice preserved their responsiveness to Con A. The following reasons may indicate that macrophage-mediated suppression participates in the deficient function of NOD spleen cells. (a) Macrophage depletion from NOD spleen cells retrieved Con A-induced IL-2 production. (b) Thioglycollate-induced peritoneal exudate cells containing many activated macrophages could completely suppress cell proliferation. (c) Prostaglandin synthetase inhibitor indomethacin reversed the suppression of IL-2 production by macrophages. (d) Conversely, exogenous prostaglandins could show the partial suppression of IL-2 production. These results suggest that activated macrophages suppress the response of NOD spleen cells to Con A mostly through prostaglandins. This impairment may contribute to the pathogenesis of Type 1 diabetes in NOD mice.

Animals↗
PubMed1989

Effect of cooling rate on insulin release from frozen-thawed dispersed rat islet cells.

Rat islet cells, dissociated with EDTA-Dispase, were immersed in 10% dimethyl sulfoxide at 20 degrees C for 15 min and frozen to -40 degrees C at a cooling rate of 0.5 or 1.0 degree C/min and subsequently further to -80 degrees C at 3 degrees C/min by a programmable freezer. After being maintained at -80 degrees C for 10 min, they were rapidly thawed in a water bath at 37 degrees C. They were cultured for 12 h and preincubated in 3.3 mM glucose-containing Krebs-Henseleit bicarbonate buffer (KHBB) for 1 h. Groups of 10(4) cells were then incubated in 3.3 or 16.7 mM glucose-containing KHBB for another hour. As a control, non-frozen-thawed cultured islet cells were incubated similarly. The non-frozen rat islet cells released 1.29 pg insulin/cell.60 min in the presence of 3.3 mM glucose and this release level was significantly elevated to 1.64 pg insulin/cell.60 min in the presence of 16.7 mM glucose. The cells frozen at 0.5 degree C/min releasing 1.55 pg insulin/cell.60 min in the presence of 3.3 mM glucose also responded to 16.7 mM glucose and released the significantly high level of 1.87 pg insulin/cell.60 min. However, the islet cells frozen at a cooling rate of 1 degree C/min secreted 1.74 and 1.92 pg insulin/cell.60 min in the presence of 3.3 mM and 16.7 mM glucose respectively. There was no significant difference between these levels. These results indicate that cryopreservation at a cooling rate of 0.5 degree C/min may be adequate for the preservation of dispersed pancreatic endocrine cells.

Animals↗
PubMed1989

Cellular differentiation in the embryonic rat pancreas, with special reference to the co-existence of substances immunoreactive to both insulin and glucagon antibodies in the same cells.

We used light and electron microscopy and immunohistochemistry to examine the pancreas primordium in 11- to-20-day-old rat embryos. Cells that were immunoreactive to glucagon-like antibodies (G-like cells) first appeared under light microscopy on day 11, and those immunoreactive to insulin-like antibodies (I-like cells) appeared on day 13. All the I-like cells also reacted to G-like substance antibody. From the 13th to the 17th day of gestation, the G-like cells proliferated rapidly while the I-like cells increased in number very slowly. All the I-like cells continued to react with G-like substance antibody as well. The I-like cells began increasing rapidly on the 18th day and soon occupied about half of the islet-constituting cells. They no longer reacted with G-like substance antibody. Using double-label immunostaining with protein A-colloidal gold, the pancreatic endocrine cells became visible in 15-day-old embryos as large polygonal cells containing numerous secretion granules 180-200 nm in diameter. Some of these cells reacted to both I-like and G-like substance antibodies. These findings show the co-existence of G-like and I-like substances in rat embryo pancreatic endocrine cells between the 13th and 17th days of gestation, after which the I-like cells proliferate rapidly, and undergo definitive differentiation from the G-like cells.

Animals↗
PubMed1989

Radio-gas chromatography on wide-bore capillary columns equipped with a synchronized accumulating radioisotope detector.

A gas chromatographic system with wide-bore capillary columns and synchronized accumulating radioisotope detector (SARD) was developed. A direct injection method and constant-flow regulation were applied. The performance of wide-bore capillary columns was good and the correspondence of the resolution obtained with SARD and that with mass detection was excellent. It was proved that the apparatus could detect of the order of 1 pg of 3H-labelled substances (3.7 TBq/mmol) and compete in terms of sensitivity with gas chromatography-mass spectrometry.

Chromatography, Gas↗
PubMed1989

Improved synchronized accumulating radioisotope detector for gas chromatography.

A synchronized accumulating radioisotope detector for radio gas chromatography was developed. It comprised seven gas-flow proportional counters each with an inner volume of 10 ml. Every counter tube was connected by a mutual anti-coincidence circuit to reduce the background. The transit time of gas particles in one counter tube could be set to an optimal value between 1 and 4 s by regulating the flow-rate of the counting gas, according to analytical requirements. The improved detector maintained high chromatographic resolution, which suggested the applicability of the apparatus to capillary gas chromatography.

Chromatography, Gas↗
PubMed1989

Target antigen of islet cell antibody in Japanese insulin-dependent diabetes mellitus.

The target antigens of islet cell antibody (ICA) have not been clarified. We tried to modify the antigen in human pancreatic tissues and characterize the ICA with immunohistochemical methods. Human pancreatic tissues were treated with periodate (A), borohydride (B), neuraminidase (C), methanol (D), chloroform-methanol (E), or protease (F) to modify the antigens, and stained by an immunofluorescent method using ICA-positive sera from five Japanese insulin-dependent diabetes mellitus (IDDM) patients. In all sera the fluorescence of islets disappeared or waned after A, C, D, and E, and did not change after F. The disappearance or loss of fluorescence induced by A was recovered after B. It is, therefore, suggested that one of the antigens of ICA in Japanese IDDM patients is the sialic acid residue of glycolipid.

Adolescent↗
PubMed1989

Effects of dietary sucrose on age-related changes in VLDL-triglyceride kinetics in the rat.

The effects of sucrose feeding on in vivo kinetics of triglyceride metabolism were compared in rats aged 2 and 12 months. Sucrose was supplied as a 10% solution in their drinking water for 2 weeks. Although plasma triglyceride concentrations doubled with age, total triglyceride secretion rates for the whole rat (mg/min/rat) increased by 40%, suggesting a decrease in the efficiency of triglyceride removal from plasma with aging. The rate of triglyceride secretion per unit body mass (mg/min/kg body weight), however, decreased by 40% as the rats grew to 12 months of age. These age-related differences were statistically significant only in rats receiving supplementary sucrose. Feeding sucrose to rats of both ages doubled the secretion rates of triglyceride not only for the whole rat but also per unit body mass. However, it tripled triglyceride concentrations, implying that the sugar decreases the removal efficiency of plasma triglyceride equally in rats at either age. Fasting hypertriglyceridemia induced by sucrose supplement was much greater in old rats than in young rats (162 +/- 30 vs. 80 +/- 8 mg/dl). The present studies demonstrate that dietary sucrose enhances age-related changes in triglyceride kinetics in the rat.

Aging↗
PubMed1989

Combined effect of exogenous insulin and sucrose on alterations in plasma lipoproteins induced by cholesterol feeding in the rat.

We have recently reported increased cholesterol concentrations in high-density and very-low-density lipoproteins (HDL and VLDL) in sucrose-fed rats with exogenous hyperinsulinemia. In order to see if exogenous hyperinsulinemia has any effect on the alterations in plasma lipoproteins induced by cholesterol feeding, we fed a cholesterol-rich diet supplemented with lard, cholic acid and propylthiouracil to hyperinsulinemic, sucrose-supplemented rats and examined plasma lipoprotein profiles. Three control groups were investigated: one receiving chow only, the other receiving a cholesterol-rich diet, the third receiving exogenous insulin, sucrose, and no cholesterol-rich diet but chow. Hyperinsulinemia was induced by a constant s.c. infusion of porcine insulin (6 U/day) from an osmotic minipump. Insulin infusion plus sucrose produced an increase in HDL cholesterol concentrations similar to that seen in the previously reported injection model in the face of no change in total and low-density lipoprotein (LDL) cholesterol. Rats receiving a cholesterol-rich diet but no insulin developed marked hypercholesterolemia characterized by an elevation of cholesterol not only in LDL but also in intermediate-density lipoprotein (IDL) and VLDL. Infusing insulin into cholesterol-fed rats produced a further increase in IDL and VLDL cholesterol but was not accompanied by any further increase in LDL cholesterol. HDL cholesterol was decreased below normal.

Animals↗
PubMed1989

Internalization and degradation of insulin by a human insulin receptor-v-ros hybrid in Chinese hamster ovary cells.

Chinese hamster ovary cell lines expressing either the wild-type human insulin receptor or a hybrid molecule in which the tyrosine kinase domain of the insulin receptor is replaced with that of the oncogene, v-ros were examined for their ability to internalize and degrade insulin. Cells expressing the hybrid receptor were found to internalize and degrade insulin at approximately half the rate of cells expressing the native insulin receptor. Moreover, insulin was incapable of inducing the internalization of the cell-surface hybrid molecule. In contrast, the constitutive rate of receptor internalization was found to be the same for the hybrid and wild-type receptors. These results obtained were similar to those with cells expressing either wild-type or mutant receptors lacking kinase activity. In conclusion, the substitution of the specificity of tyrosine kinase of the insulin receptor with that of the v-ros oncogene product results in defective internalization and degradation of insulin, and loss of ligand-induced receptor internalization.

Animals↗
PubMed1989

Pupillary light reflex in borderline diabetes mellitus.

It is well known that in diabetes mellitus the early phase insulin release response to glucose becomes blunted. Besides, autonomic neuropathy develops frequently. The autonomic nerve function is related to insulin release in normal subjects. Therefore, in the present study the autonomic function was investigated in different degrees of the early phase insulin release response to glucose loading in borderline diabetes mellitus (B-DM) as well as the early stage of diabetes mellitus (E-DM). In our study the pupillary light reflex seemed to be more sensitive for the detection of autonomic neuropathy than the cardiac beat-to-beat variation in B-DM and E-DM. The light reflex, therefore, was used and the following results were obtained. (1) Autonomic neuropathy was detected even in B-DM, though it was slighter than in E-DM. (2) The parasympathetic nerve appeared to be impaired more than the sympathetic in B-DM and this was especially the case in subjects with relatively good insulin release response. Therefore, the suppression of the early phase insulin release in B-DM may be caused by this autonomic neuropathy already present. (3) In B-DM with reduced insulin release autonomic neuropathy seemed to be more advanced and it became more remarkable in E-DM. Particularly the sympathetic abnormality was loaded in this regard. These observations suggest that it is necessary to consider an involvement of autonomic nerve dysfunction for the understanding of the pathogenesis of B-DM.

Adult↗
PubMed1989

Sophisticated mesh filtration technique of a large-scale isolation of islets and their function.

A large-scale isolation of islets is required for islet transplantation. We improved our conventional method, and could obtain about three times more islets than by the conventional methods. Pancreata of adult Wistar rats were inflated by injection of buffer with (A) or without 1.3 mg/ml collagenase (B). The rats were bled from the inferior vena cava and the aorta in (A) simultaneously with the inflation. They were further digested with collagenase and filtered through two different meshes (pore size: 1190 and 590 microns) (A1) or three different meshes (pore size: 1190, 590 120 microns) (A2) in order. Insulin released from islets isolated in this manner was determined by 1-h incubation with 3.3 and 16.7 mM glucose. Besides, 600 islets each were transplanted into the liver of streptozotocin-induced diabetic Wistar rats and their fasting plasma glucose was measured at weekly intervals. (1) With these methods more numerous islets were harvested by A1 (mean: 554) and A2 (mean: 746) than B (mean: 224). (2) Insulin released at both glucose concentrations was similar among islets obtained by A1, A2 and B. (3) The plasma glucose-lowering effect was similar among the islets obtained by these methods. (4) A more selected range of islet sizes was obtained by A2 than A1. These observations indicate that the present techniques (A1 and A2) are less time-consuming and simpler for a large-scale isolation of islets.

Animals↗
PubMed1989

Islet function after storage at -2 degrees C and -196 degrees C.

The radical treatment of type 1 diabetes by transplantation requires the extracorporeal storage of islets, and this has frequently been studied. Damage from ice formation, however, has prevented the development of any satisfactory method for preservation. We compared islet function after frozen storage with that after non-frozen storage. Isolated rat islets immersed in 10% dimethyl sulfoxide were kept at -2 degrees C (group A) and -196 degrees C (group B) for 7 days. After one day of culture, some of the islets were incubated in 3.3 and 16.7 mM glucose-containing Krebs--Henseleit bicarbonate buffer for 60 min. The other islets were incubated with 3H-leucine for 2 h. The radioactivity of whole-islet homogenate and the insulin extracted from it were measured. We also counted the number of islets before and after the 7-day storage. The islets thus preserved were transplanted into streptozotocin-induced diabetic rats and the fasting plasma glucose was determined weekly. Non-cooled islets were used as controls (group C). Insulin release in the presence of 16.7 mM glucose did not significantly differ between groups C and A, whereas it was lower in group B than in groups A or C. The islet uptake of 3H-leucine was lower in A and B compared with C, but the insulin synthesis was similar in all three groups. More islets were recovered from A than B. Fasting plasma glucose was lowered similarly in the diabetic rats after transplantation of islets from A and B. The relative ease of preservation at -2 degrees C, and the positive results of this experiment, favor this method of preservation.

Animals↗
PubMed1989

Production of anti-insulin monoclonal antibody and its application to immunoassay of insulin and immunohistochemistry.

An unlimited supply of suitable antisera is wanted for immunoassays, analysis of antigenic determinants and precise localization of antigens in biological systems. Therefore, we produced a monoclonal antiporcine insulin antibody by the hybridoma technology and assessed it in comparison with polyclonal antibody. The spleen cells of BALB/c mice immunized against porcine insulin were hybridized with mouse myeloma cells (P3-X63-Ag8-U1). The monoclonal antibody thus generated was shown to have high binding capacity and specificity to porcine insulin in radioimmunoassay. It reacted with human insulin as well, but did not crossreact with other polypeptide hormones produced in the pancreatic islets such as glucagon, somatostatin and pancreatic polypeptide. In immunohistochemistry human and dog islets were stained by this monoclonal antibody. Rat islets were not stained, although they reacted with polyclonal anti-insulin antibody. The insulin of human serum samples measured using the monoclonal antibody was tightly correlated with that using the polyclonal antibody. These observations indicate that our hybridoma-derived monoclonal antibody is useful for immunoassay as well as localization of insulin.

Animals↗
PubMed1989

Participation of nicotinic receptor in hormone release from isolated rat islets of Langerhans.

Pancreatic hormone release is generally thought to be regulated through adrenergic as well as muscarinic receptors. We have previously observed possible nicotinic involvement in insulin release. In the present study, we incubated isolated rat islets for 60 min with various concentrations of atropine (a muscarinic receptor blocker), alpha-bungarotoxin (alpha-Btx, a nicotinic receptor blocker), and anti-acetylcholine receptor antibody (IgG) (anti-Ach.R.Ab) obtained from a patient with myasthenia gravis. Atropine suppressed insulin release, and alpha-Btx and anti-Ach.R.Ab potentiated it; atropine did not suppress glucagon release, while alpha-Btx and anti-Ach.R.Ab raised it. None of these agents influenced somatostatin release. These observations suggest that muscarinic as well as nicotinic receptors influence insulin release, as nicotinic receptors do glucagon release. Neither nicotinic nor muscarinic receptors seem to regulate somatostatin release.

Acetylcholine↗