Glucose, insulin, and somatostatin infusion for the determination of insulin sensitivity in vivo.
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Biomedical subjects
Publications and source records attributed to M Haneda.
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The association between microalbuminuria and systemic blood pressure was investigated in 80 nonproteinuric subjects with non-insulin-dependent diabetes. Seventeen of 80 diabetics had urinary albumin excretion rates (AER) over 20 micrograms/min and were defined as microalbuminuric. The microalbuminuric diabetics showed a higher incidence of proliferative retinopathy and neuropathy than the normoalbuminurics. Moreover, the former group had significantly higher values of systolic blood pressure compared to the latter, although the creatinine clearance was not significantly different between the two groups. These results suggest that microalbuminuria is strongly associated with a rise of systemic blood pressure in non-insulin-dependent diabetics.
In order to elucidate the clinical significance of microalbuminuria in non-insulin-dependent diabetes mellitus (NIDDM), 62 Japanese subjects with NIDDM and without proteinuria were followed for three years. After the three-year follow up, four (19%) of 21 microalbuminuric patients--albumin excretion rates (AER) greater than 15 micrograms/min--developed overt proteinuria, while none of the 42 normoalbuminuric patients did. Among these normoalbuminuric patients, eight patients (19.5%) developed microalbuminuria. The microalbuminuric patients who developed overt proteinuria had higher AER at the beginning of the study than the patients who stayed microalbuminuric. The patients who developed microalbuminuria showed a significantly higher systolic blood pressure in the final year than the patients who stayed normoalbuminuric. These results indicate that microalbuminuria precedes overt proteinuria in Japanese NIDDM, and progression of diabetic nephropathy is rapid and associated with a rise in blood pressure.
Cultured mesangial cells possess a large number of receptors specific to IGF-I with a small number of insulin receptors. Physiological concentrations of IGF-I increased the uptakes of aminoisobutyric acid and 2-deoxyglucose in mesangial cells, while insulin exhibited similar effects only with unphysiologically high concentration. These findings suggest that, in cultured mesangial cells, IGF-I may regulate cellular metabolic functions such as glucose and amino acid uptakes through its own receptors rather than insulin receptors.
Type IV collagen production by cultured rat glomerular mesangial cells was evaluated quantitatively by measuring type IV collagen secreted into culture media and associated with the cells using enzyme-linked immunosorbent assay (ELISA). The majority of type IV collagen was secreted into culture media; type IV collagen increased with cell growth in the early log phase and decreased in the late log phase and after cofluency. By exposing the cells to high concentrations of glucose (27.8 mM), both secreted and cell-associated type IV collagens increased significantly compared with the cells cultured under normal glucose concentrations (5.6 mM) or under equivalent concentrations of mannitol, resulting in a significant increase in total type IV collagen accumulation.
To clarify the possible role of intrarenal renin-angiotensin system (RAS) in the evolution of renal hemodynamic alteration in diabetes, we investigated the change of tissue angiotensin-converting enzyme (ACE) activity, a key enzyme of RAS, in the kidneys obtained from streptozotocin-induced diabetic rats. Tissue ACE activity was significantly reduced in both outer cortex (0.29 +/- 0.04, mean +/- SEM, n = 6) and inner cortex with outer medulla (2.43 +/- 0.28, n = 6) of the kidneys from diabetic rats 2 weeks after induction of diabetes compared with those from control rats (0.47 +/- 0.05, n = 7, in outer cortex; 3.68 +/- 0.32, n = 7, in inner cortex with outer medulla). ACE activities in the lung and aorta of diabetic rats were not different from those of control rats. ACE activities in the serum and urine were significantly elevated in diabetic rats. Treatment of diabetic rats with insulin to achieve near euglycemia completely prevented these alterations in ACE activity, except that, in the urine, the elevation of ACE was partially corrected with insulin. In contrast to ACE activity, activity of N-acetyl-beta-D-glucosaminidase (a lysosomal enzyme of the tubule) and r-glutamyl transpeptidase (a brush border enzyme) in the kidney were not reduced in diabetic rats, whereas in the urine both enzyme activities were significantly elevated in diabetic rats. It is likely, therefore, that the reduction of ACE activity in the kidneys of diabetic rats may reflect the impairment of vascular endothelial cells in the kidney, rather than tubular damage.(ABSTRACT TRUNCATED AT 250 WORDS)
In this study, 52 nonproteinuric Japanese patients with non-insulin-dependent diabetes (NIDDM) were followed from 1985 to 1990 to investigate the rate of development and progression of microalbuminuria and the factors which influence it. In 1985, 34 patients were normoalbuminuric, and 18 patients were microalbuminuric. Five years later, 11 of 34 initially normoalbuminuric patients (32.4%) developed microalbuminuria, and 6 of 18 initially microalbuminuric patients (33.3%) developed overt proteinuria. At the beginning of the study, hypertension existed more frequently in the patients who later developed microalbuminuria (8 of 11, 72.7%) than in the patients who stayed normoalbuminuric (4 of 23, 17.4%). Age-adjusted values of mean blood pressure (+/- SEM) at the beginning of the study in the patients who developed microalbuminuria (98.2 +/- 3.4 mm Hg, n = 11) were significantly higher than those in the patients who stayed normoalbuminuric (87.3 +/- 2.4 mm Hg, n = 23). In six patients who developed overt proteinuria, initial urinary albumin excretion rates (AER) were higher than those in the patients who stayed microalbuminuric, and four patients who presented with initial AER greater than 100 micrograms/min all developed overt proteinuria. These results indicate that, in Japanese patients with NIDDM, the rate of development of microalbuminuria is faster than that reported in Caucasian IDDM, and preexisting hypertension with relatively poor control of blood pressure may be a risk factor for the development of microalbuminuria.