Immunoglobulin from insulin-dependent diabetic children inhibits glucose-induced insulin release.

Immunoglobulin was separated from islet cell antibody positive plasma of six children with newly diagnosed insulin-dependent (type I) diabetes mellitus. The dynamics of insulin release in response to glucose and partially purified antibodies were determined in dispersed rat islet cells perifused on small columns of Biogel P-2 beads. After perifusion at 5.5 mmol/L D-glucose in the presence of healthy control immunoglobulin, the rate of insulin release increased in a biphasic manner after stimulation with 30 mmol/L D-glucose. In cells exposed to diabetic immunoglobulin, 30 mmol/L D-glucose had little, if any, effect on insulin release. These results suggest that islet cell antibodies in insulin-dependent diabetes may interfere with the insulin release mechanisms in the pancreatic B-cells.

Block in insulin release from column-perifused pancreatic beta-cells induced by islet cell surface antibodies and complement.

Dispersed rat pancreatic islet cells were mixed into a short column of Bio-Gel P-2 polyacrylamide beads and perifused with an antiserum containing islet cell surface antibodies. The release of radioactive chromium from prelabeled cells, as a measure of cell membrane permeability, was not affected by cell surface antibodies alone, but increased dramatically in the presence of complement. While there was an eightfold increase in glucose-stimulated insulin release from beta-cells exposed to control serum and complement, insulin release was completely blocked from beta-cells exposed to islet-cell-specific antibodies and complement. These findings suggest that islet cell surface antibodies can mediate complement-dependent cytotoxicity.

Defect of the first-phase insulin secretion to glucose stimulation in the perfused pancreas of the nonobese diabetic (NOD) mouse.

To investigate the development of impaired insulin secretion in type I diabetes mellitus, the pancreata of ICR and NOD mice (10-50 wk of age) were perfused. According to insulin responses to 30 mM glucose and to 19 mM arginine, we classified the NOD mice into four groups: those having normal insulin secretion to glucose and to arginine similar to that of control ICR mice (group 1); those with a defect in the first-phase insulin secretion to glucose stimulation but with almost normal insulin secretion to arginine, total insulin release to glucose being significantly smaller than that of group 1 (group 2); those having only a small insulin response to either stimulus, but a fasting plasma glucose level still within the normal range (group 3); and those being overtly diabetic, showing no insulin response to either stimulus (group 4). The severity of insulitis and insulin concentration of the pancreas in each group of NOD mice was well correlated with the insulin release from the perfused pancreas. These results indicate that the initial sign of B-cell damage in NOD mice is a defect of the first phase of glucose-induced insulin secretion, which is followed by a total loss of ability to respond to glucose or arginine stimulation.

Simplification for measuring input function of FDG PET: investigation of 1-point blood sampling method.

UNLABELLED: The current method for quantitative FDG PET study requires application of multiple arterial blood sampling for measuring the input function, but the procedure is invasive and complicated. The purpose of this study was to establish a 1-point blood sampling technique that gives data comparable with the data of more elaborate serial arterial sampling. METHODS: We established a time point for 1-point arterial sampling that exhibited the highest correlation between plasma radioactivity at the time point and the real integrated value (IV) of the measured input function obtained by multiple arterial sampling in 120 patients and the smallest coefficient of variation of the real IV divided by plasma radioactivity at the time point in 120 patients. Scaling factors for estimation at each sampling point were determined, and a reference table was established to make the supposed input function. RESULTS: The optimal time for 1-point arterial sampling was 12 min after FDG injection. A good correlation was observed between the real IVs and those estimated from 1-point arterial blood sampling at 12 min using the supposed input function (n = 120; P < 0.001). The time point at which the difference between values of arterial and venous blood disappeared was 40 min after FDG injection. The percentage errors of IV estimation by 1-point sampling were 1.70% (n = 120) for arterial blood at 12 min and 3.64% (n = 10) for venous blood at 40 min. CONCLUSION: We conclude that the simplified 1-point sample method works in a manner that is comparable with serial arterial sampling and should be useful for clinical PET.

Islet cell surface antibodies preferentially inhibit glucose-stimulated insulin release in vitro.

The effect of islet surface antibodies (ICSA) on in vitro insulin release was studied. Isolated rat islets were incubated in the presence of immunoglobulin preparations from patients with insulin-dependent and non-insulin-dependent diabetes mellitus (IDDM, NIDDM) and healthy subjects, and stimulated with D-glucose, L-arginine or tolbutamide. After incubation, the amount of insulin release from the rat islets was determined. The immunoglobulin preparations from 5 newly diagnosed IDDM patients who were positive for ICSA, and from 5 age-matched healthy subjects were examined. Even in the absence of complement or lymphocytes, immunoglobulin fractions positive for ICSA significantly inhibited low and high concentrations of glucose-stimulated insulin release compared with normal control (P less than 0.02), but had little influence on insulin release after stimulation with tolbutamide. Arginine-stimulated insulin release was almost the same in ICSA-positive immunoglobulin fractions and the control. Immunoglobulin fractions negative for ICSA either from four patients with recently diagnosed IDDM or from four newly diagnosed NIDDM patients had only negligible effect on insulin release after stimulation with glucose. These results suggest that ICSA in IDDM patients, even in the absence of complement or lymphocytes, may preferentially interfere with the mechanisms of glucose-stimulated insulin release in the pancreatic B cells.

Relationship between erythrocyte sorbitol content and diabetic microangiopathy in patients with non-insulin-dependent diabetes mellitus: the study of a diet loading test.

To determine whether erythrocyte sorbitol content could become an indicator of diabetic microangiopathy, we studied the relationship between the changes in erythrocyte sorbitol content in response to diet loading and diabetic microangiopathy in patients with non-insulin-dependent diabetes mellitus. The increase of change in erythrocyte sorbitol content (delta Sor) after diet loading (420 kcal) significantly correlated with that of plasma glucose levels (delta BS). The patients with less than or equal to 40 m/s of motor or sensory nerve conduction velocity (MCV and SCV) had significantly higher delta Sor and delta Sor/delta BS values than those with greater than 40 m/s of MCV and SCV; nevertheless, there were no significant differences in delta BS between the two groups. Furthermore there was a significant negative correlation between nerve conduction velocity and delta Sor and Delta Sor/delta BS values. On the other hand, the patients with nephropathy or retinopathy showed no significant increase in delta Sor or delta Sor/delta BS compared with patients without these complications. The results demonstrated that delta Sor and delta Sor/delta BS could become indicators of the presence or severity of diabetic neuropathy. Furthermore the more significant participation of alteration in the polyol pathway in the pathogenesis of neuropathy than of the other microangiopathies was suggested.

Reduced norepinephrine turnover in brown adipose tissue of pre-obese mice treated with monosodium-L-glutamate.

Norepinephrine (NE) turnover, an index of sympathetic nervous system (SNS) activity, was measured in interscapular brown adipose tissue (IBAT), heart and pancreas of 3-weeks-old pre-obese monosodium-L-glutamate (MSG) mice and at 6-weeks-old mildly obese MSG mice. In IBAT, rates of NE turnover were slower not only in 3-weeks-old MSG mice but also in older obese MSG mice than in their saline controls. In heart, rates of NE turnover were slower in 6-weeks-old mildly obese MSG mice, but not in pre-obese MSG mice. No significant difference in NE turnover in pancreas was observed at either age. The low NE turnover in IBAT of MSG-treated mice prior to the onset of gross obesity suggests that low SNS activity may be an initial contributor to their high energy efficiency and resultant obesity.

The association between end-stage diabetic nephropathy and methylenetetrahydrofolate reductase genotype with macroangiopathy in type 2 diabetes mellitus.

The T/T genotype of the methylenetetrahydrofolate reductase C677 T gene polymorphism is associated with elevated homocysteine levels and presumably with increased atherosclerotic risk. We evaluated the interaction between this gene polymorphism and end-stage diabetic nephropathy on the observed prevalence of macroangiopathy in type 2 diabetes mellitus. The methylenetetrahydrofolate reductase 677 C/T genotypes were determined in 174 type 2 diabetic patients: 80 with and 94 without renal failure due to diabetic nephropathy. In the patients with renal failure, the T/T genotype and T allele were significantly associated with macroangiopathy (T/T; 31 % vs. 2 %, P = 0.0001 T allele; 59 % vs. 29 %, P = 0.00014), whereas the associations were not significant in the patients without renal failure. In the multiple logistic regression analysis, age (10 years OR 4.05 [1.79 - 9.31], P < 0.0005) and 677 T allele (6.84 [2.12 - 22.05], P = 0.0013) were significantly associated with macroangiopathy in the patients with renal failure. In conclusion, this study demonstrated that the 677 T/T genotype and T allele of MTHFR were significantly associated with macroangiopathy in type 2 diabetic patients with renal failure. The MTHFR 677 T allele, together with renal dysfunction due to diabetic nephropathy, could be a strong risk factor for atherosclerotic disease.

Detection and possible functional influence of antibodies directed againt the pancreatic islet cell surface.

Antibodies directed towards determinants on the surface of rat islet cells can be detected qualitatively by the indirect immunofluorescence or quantitatively by a specific radioassay for IgG. Antibodies are found in insulin-dependent diabetics or in rabbits immunized with islet cells. Such antibodies may affect the B-cell function as indicated by the inhibition of incorporation of radioactive leucine into proinsulin/insulin in vitro.

Effects of aspartame on diabetic rats and diabetic patients.

The effects of aspartame (L-aspartyl-L-phenylalanine methyl ester) on plasma glucose and insulin levels were investigated in diabetic rats and patients with non-insulin-dependent diabetes mellitus. The oral administration of 0.45 mg aspartame per 100g body weight, which is equivalent to 150 mg of glucose in sweetness, to streptozotocin-induced diabetic rats had no effect on the plasma glucose or insulin levels. Also, 225 mg oral aspartame loading, which is equivalent to 75 g of glucose in sweetness, to patients with non-insulin-dependent diabetes mellitus did not increase plasma glucose or insulin levels, although 75 g of oral glucose loading increased plasma glucose and insulin levels in diabetic patients as expected. Aspartame ingestion for three days at a dose of 24-48 mg per day and the intake of snacks flavored with 240 mg of aspartame also did not increase fasting plasma glucose levels. These results suggest that acute administration of aspartame has no influence on plasma glucose or insulin levels in diabetic rats and patients with non-insulin-dependent diabetes mellitus.

[Fluorine-18 labeled 6-fluoro-L-dopa: systematization and evaluation of its usefulness].

6-[18F]Fluoro-L-dopa (L-3,4-dihydroxy-6-[18F]fluorophenylalanine; 6-[18F]FDPA) is useful to assess presynaptic dopamine metabolism in central nervous system. In this paper, we report on the usefulness of the 6-[18F]FDOPA synthesis system developed for the routine synthesis. This system consists of the 6-[18F]FOPA synthesis and the separation units in conjunction with controller using a personal computer. The synthesis time of 6-[18F]FDOPA was 73 minutes. The typical yield and specific activity were 1.4-2.4 GBq and 244-270 MBq/mumol at the end of synthesis, respectively, under the irradiation condition of 50 microA for 130 minutes. The radiochemical yields of 6-[18F]FDOPA were 31.3-38.7% based on the [18F]acetylhypofluorite, and the results were affected with the condition of potassium acetate (AcOK) to produce gaseous [18F]acetylhypofluorite. This system is useful for the routine production of 6-[18F]FDOPA because of its high yield and high specific activity while maintaining AcOK in good condition, and decreasing the radiation exposure for chemist.

[Clinical study of combination chemotherapy with mitomycin C, vindesine and cisplatin (MVP therapy) in advanced non-small cell lung cancer].

Thirty-seven patients with inoperable non-small cell lung cancer were treated with the combination chemotherapy (MVP therapy) with mitomycin C (8 mg/m2), vindesine (3 mg/m2 X 2) and cisplatin (60 mg/m2). The partial responders were 13 cases (35%), and the median survival time was 271 days. In this study the cisplatin dose was less than in any other report of "MVP" therapy. But both the response rate and the median survival time did not differ from those reported elsewhere. The side effects (bone marrow suppression, renal toxicity, etc.) were mild, and did not prevent the continuance of this therapy. Thus, we could repeat more than 6 courses of "MVP" therapy for 8 patients. Nowadays, it is difficult to obtain complete responders with any chemotherapy for inoperable non-small cell lung cancer. To prolong lives of patients and maintain good quality of life, we recommend chemotherapy with low toxicity in often-repeatable courses.