Misao Yamamoto

Association between a polymorphism in the angiotensin-converting enzyme gene and microvascular complications in Japanese patients with NIDDM

SummaryThe relationship between diabetic nephropathy and an insertion (I)/deletion (D) polymorphism in intron 16 of the angiotensin-converting enzyme (ACE) gene is still under debate. The association of ACE gene polymorphism with nephropathy and retinopathy was therefore examined in 362 Japanese patients with non-insulin-dependent diabetes mellitus (NIDDM) and 105 healthy control subjects. Distribution of the ACE genotype did not differ between healthy control subjects and diabetic patients without complications. However, the frequency of the D allele was significantly higher in the diabetic subjects with nephropathy than in those without (0.32 in normoalbuminuric patients vs 0.44 in albuminuria patients with albuminuria) (χ2=7.7; p=0.006). There was no significant association between ACE genotype and retinopathy. These observations thus demonstrate a significant association of the ACE gene polymorphism with nephropathy, but not with retinopathy, in Japanese patients with NIDDM.

IDENTIFICATION AND INITIAL CHARACTERIZATION OF A FOURTH LEADER EXON AND PROMOTER OF THE HUMAN IGF-II GENE

Transcription of the human insulin-like growth factor II (IGF-II) gene is regulated by activation of multiple promoters which act in a tissue-specific and development-dependent manner. Previously, we have identified three different promoters, one of which is active in adult liver tissue only, whereas the other two are active in many fetal tissues and adult non-hepatic tissues. Here we report the identification of a fourth leader exon of the human IGF-II gene indicating the presence of a fourth promoter. Transcription from this promoter yields a 5.0 kb IGF-II mRNA species, which is detected in fetal liver and leiomyosarcoma tissue.

Advanced glycosylation end products induced tissue factor expression in human monocyte-like U937 cells and increased tissue factor expression in monocytes from diabetic patients

Tissue factor (TF) plays a central role in the initial activation of the extrinsic coagulation pathway and is thought to be involved in the development of atherosclerosis and thrombosis. The effect of advanced glycosylation end products (AGEs) on TF expression and its mechanism were assessed by flow cytometric analysis. Human macrophage-like U937 cells, which were shown to contain mRNA encoding the receptors of advanced glycosylation end products (RAGE), expressed TF in a dose-dependent manner on incubation with AGE-albumin. AGE-albumin-induced TF expression was completely inhibited by the anti-oxidant agents, catalase and probucol. TF expression in peripheral monocytes from normal volunteers was also increased by AGE-albumin. Finally, TF expression in monocytes from individuals with diabetes mellitus, in whom the concentration of circulating AGEs is reported to be increased, was higher than that in monocytes from normal controls. These results suggest that AGE-induced TF expression in macrophages/monocytes is mediated by oxidant stress. AGEs may promote thrombosis and the development of atherosclerosis by inducing TF expression in monocytes in patients with diabetes mellitus.

Stroke topography in diabetic and nondiabetic patients by magnetic resonance imaging

Stroke is more frequent in diabetic than in nondiabetic patients. We studied lesion topography in 61 stroke patients with diabetes mellitus and 77 without diabetes using magnetic resonance imaging. Location, number and size of infarcts were investigated. Prevalence of hypertension did not differ between diabetic and nondiabetic patients. In elderly subgroups (> or = 65 years), infratentorial infarcts > or = 5 mm in diameter were more frequent in diabetic than in nondiabetic patients (32 vs. 12%, P < 0.05), while supratentorial infarcts were not different (56 vs. 68%, ns). Asymptomatic hemorrhage combined with silent infarction was significantly less frequent in diabetic than in nondiabetic patients (5 vs. 22%, P < 0.05). In nondiabetic patients with significant stenosis in the carotid system, supratentorial infarction measuring > or = 15 mm was more frequent than in those without stenotic lesions, but the number of infarcts per patient irrespective of size was smaller when stenosis was present. On the other hand, the number of infarcts in diabetic patients was similar between those with and without carotid system stenosis. The present study demonstrated that infratentorial infarcts were more common in elderly diabetic patients, suggesting the vulnerability of vertebrobasilar circulation in diabetes.

Effect of glycated collagen on proliferation of human smooth muscle cells in vitro

SummaryWhile non-enzymatic glycation of long-lived tissue proteins such as collagen has been implicated in chronic complications of diabetes mellitus, its role in the aetiology of diabetic macroangiopathy has not been elucidated. To test the hypothesis that glycation of collagen abolishes the inhibitory effect of native collagen on the proliferation of human smooth muscle cells, we obtained smooth muscle cells from human gastric arteries and cultured them on dishes coated with glycated or non-glycated collagen. The proliferation of human smooth muscle cells in the presence of 10 % fetal calf serum or platelet derived growth factor-BB (10 ng/ml) was inhibited by type 1 collagen coated on the dishes. Glycation of collagen with glucose 6-phosphate for 7 days abolished the growth-inhibitory effect of native collagen. Succinylation of collagen, which like glycation blocked the lysyl residues in collagen, also abolished the growth-inhibitory effect. Adhesion of human smooth muscle cells to collagen-coated dishes was not affected by glycation of collagen. Addition of glycated albumin to the medium did not affect the growth of human smooth muscle cells on plastic dishes. The inhibition of human smooth muscle cell proliferation by collagen was not reversed by the glycation of collagen in the presence of aminoguanidine. Results suggest that early glycation abolishes the inhibitory effect of collagen on human smooth muscle cell proliferation and may thus participate in the progression of macro-angiopathy in diabetes.

Circadian blood pressure variation in non-insulin-dependent diabetes mellitus with nephropathy

We studied a circadian blood pressure variation in relation to the progression of diabetic nephropathy in patients with non-insulin-dependent diabetes mellitus (NIDDM). Age, duration of diabetes, body mass index and glycemic control did not differ among the groups of patients with normo-, micro- and macroalbuminuria. None of the patients received antihypertensive drugs. There were no differences in renal and autonomic functions between normo- and microalbuminuric groups, but these functions were impaired in the macroalbuminuric group. The rise in blood pressure was more apparent in 24-h ambulatory blood pressure (AMBP), especially during night-time, as compared with casual blood pressure. Such blood pressure rise was in accordance with the progression of nephropathy. However, pulse rate did not differ among the three groups. The nocturnal fall in blood pressure was blunted in the micro- and macroalbuminuria groups, but evident in the normoalbuminuric group. In the latter, daytime systolic blood pressure (SBP) was significantly higher than night-time SBP (123 +/- 5 mmHg vs. 113 +/- 3 mmHg, P = 0.002). In contrast, in the former two groups of patients, there were no significant differences in SBP between daytime and night-time (134 +/- 9 mmHg vs. 134 +/- 9 mmHg, ns, for microalbuminuria and 159 +/- 8 mmHg vs. 165 +/- 7 mmHg, ns, for macroalbuminuria). Urinary albumin excretion was significantly correlated with night-time SBP (r = 0.48, P = 0.015), but not with daytime SBP (r = 0.30, ns).(ABSTRACT TRUNCATED AT 250 WORDS)

Na+-dependent glucose uptake and collagen synthesis by cultured bovine retinal pericytes.

This study was performed to clarify the presence of sodium-dependent glucose uptake and its role in the synthesis of type IV and type VI collagen by cultured bovine retinal pericytes. The glucose uptake by retinal pericytes and retinal endothelial cells was measured using 3H-D-glucose in the presence or absence of sodium. Glucose uptake in the presence of sodium was twice as high as that observed in the presence of phlorizin and sodium or in the absence of sodium. Sodium-dependent glucose uptake was observed at different sodium concentrations, and its half-maximal stimulation occurred at 48 mM. These findings were not observed in retinal endothelial cells. Levels of type IV and type VI collagen produced by retinal pericytes were significantly increased at glucose concentrations higher than 20 mM. Phlorizin decreased both collagen synthesis and glucose consumption by retinal pericytes incubated with 30 mM of glucose to the levels observed with 5 mM of glucose. These data suggest that sodium-dependent glucose uptake is present in retinal pericytes and that excessive glucose entry into the cell is an important factor for overproduction of collagen. Phlorizin normalized the synthesis of type IV and type VI collagen with decreasing glucose consumption under high glucose conditions.

Correction of serious iron overload in a chronic hemodialysis patient by recombinant human erythropoietin and removal of red blood cells: confirmation by follow-up liver biopsy.

A chronic hemodialysis case, a 46-year-old woman with secondary hemosiderosis induced by parenteral iron and blood transfusion due to a refractory anemia, was effectively treated with recombinant human erythropoietin and the removal of red blood cells. The cumulative dose of the iron removed was 5,712 mg. Plasma ferritin decreased from 8,290 to 2,203 micrograms/l during 18 months. Concomitantly, liver histology performed before and after the therapy revealed a prominent regression of the deposited iron.

Prospective Study of Asymmetric Retinopathy as a Predictor of Brain Infarction in Diabetes Mellitus

hypothalamus (4). The IGF-I levels were not statistically different between regimens and, if anything, tended to be lower on intraperitoneal insulin making it highly unlikely that IGF-1 would be mediating any decrease in our patients GH profile. IGFBP-l appears to have an inhibitory effect on IGF-I action in various tissues (6), and it has been suggested that increased amounts of this binding protein inhibit the detection of IGF-1 by the hypothalamus and/or pituitary gland (5). Suppressing IGFBP-l levels with direct intraperitoneal (intraportal) insulin administration may allow improved detection of IGF-I by the pituitary or hypothalamus and subsequently lead to a decreased GH secretion. This case report highlights a possible benefit of insulin delivery via the intraperitoneal route. These preliminary findings need, however, to be examined in larger studies and over longer time intervals. If the marked increase of IGFBP-l known to occur in type I diabetes can be more effectively suppressed by using intraperitoneal insulin this may provide particular benefit to adolescent diabetic patients as elevated levels of IGFBP-l have been postulated to play a role in the growth impairment seen in these patients (7).

Development of ischemic stroke in normotensive and hypertensive diabetic patients with or without antihypertensive treatment: An 8-year followup study

Although the impact of hypertension as a risk factor for brain infarction in diabetes mellitus is evident, the beneficial effect of antihypertensive therapy has not been demonstrated. Therefore, we designed a prospective cohort study to elucidate the effects of antihypertensive therapy on the development of ischemic stroke in diabetic outpatients. Two hundred forty patients, 219 non-insulin-dependent diabetes mellitus (NIDDM) and 21 insulin-dependent diabetes mellitus (IDDM), without history of cerebrovascular accident were followed for 8 years, from January 1981 until December 1988, in our diabetic clinic. Forty-eight of 88 hypertensive patients had received antihypertensive drugs. Among 40 untreated hypertensive and 152 initially normotensive diabetics, 14 hypertensives and 11 normotensives required antihypertensive therapy during followup period. Twenty-three patients were dropped out because of the unidentified reasons. Cerebrovascular accident occurred in 24 patients (10%): 18 brain infarctions, 4 transient ischemic attack (TIA), 1 subarachnoidal hemorrhage, and 1 brain hemorrhage. The percent incidence of ischemic strokes in the hypertension-treated patients was 8.9% which was similar to the 8.1% of the normotensives. In contrast, ischemic strokes developed in 29% of the untreated hypertensives, being significantly more frequent than in the former two groups. Multivariate analysis showed that serum total cholesterol and male gender were independent significant precursors of brain infarction in diabetic patients. In conclusion, antihypertensive treatment decreased the incidence of ischemic stroke in diabetics. Serum total cholesterol turned to independent risk factors for ischemic stroke in diabetic patients.