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Aims The goal of the study was to evaluate the efficacy of epalrestat, an aldose reductase inhibitor, on diabetic retinopathy and diabetic nephropathy, based on analysis of the results of the Aldose Reductase Inhibitor–Diabetes Complications Trial, a 3-year multicentre comparative clinical trial of conventional therapy (control group) and epalrestat therapy (epalrestat group) in Japanese patients with mild diabetic neuropathy. Methods The subjects of the study were patients enrolled in the Aldose Reductase Inhibitor–Diabetes Complications Trial for whom data for major patient characteristics, severity of diabetic neuropathy at the end of the study and time-courses of diabetic retinopathy and diabetic nephropathy were available (57 and 52 patients from the control and epalrestat groups, respectively). Progression of diabetic retinopathy/nephropathy (a primary endpoint) in relation to major patient characteristics, severity of diabetic neuropathy at the end of the study (assessed from the mean of z-scores in four neurological function tests) and epalrestat treatment were analysed using univariate analysis and multiple logistic regression analysis. Results Progression of diabetic retinopathy/nephropathy was significantly inhibited in the epalrestat group compared with the control group (odds ratio = 0.323, P = 0.014) and was dependent on the severity of diabetic neuropathy at the end of the study (odds ratio = 2.131, P = 0.025). Conclusions Epalrestat prevented progression of diabetic neuropathy and retinopathy/nephropathy. The effect on diabetic retinopathy/nephropathy may have occurred indirectly because of the prevention of progression of diabetic neuropathy, in addition to the inhibitory action of epalrestat on aldose reductase.

Aims The long-term efficacy of epalrestat, an aldose reductase inhibitor, in improving subjective symptoms and nerve function was comprehensively assessed to identify patients with diabetic peripheral neuropathy who responded to epalrestat treatment. Methods Stratified analyses were conducted on data from patients in the Aldose Reductase Inhibitor—Diabetes Complications Trial (ADCT). The ADCT included patients with diabetic peripheral neuropathy, median motor nerve conduction velocity ≥ 40 m/s and with glycated haemoglobin (HbA1c) ≤ 9.0%. Longitudinal data on HbA1c and subjective symptoms of the patients for 3 years were analysed (epalrestat n = 231, control subjects n = 273). Stratified analyses based on background variables (glycaemic control, grades of retinopathy or proteinuria) were performed to examine the relationship between subjective symptoms and nerve function. Multiple logistic regression analyses were conducted. Results Stratified subgroup analyses revealed significantly better efficacy of epalrestat in patients with good glycaemic control and less severe diabetic complications. In the control group, no improvement in nerve function was seen regardless of whether symptomatic benefit was obtained. In the epalrestat group, nerve function deteriorated less or improved in patients whose symptoms improved. The odds ratio of the efficacy of epalrestat vs. control subjects was approximately 2 : 1 (4 : 1 in patients with HbA1c ≤ 7.0%). Conclusion Our results suggest that epalrestat, an aldose reductase inhibitor, will provide a clinically significant means of preventing and treating diabetic neuropathy if used in appropriate patients. Diabet. Med. 25, 818–825 (2008)

In order to study a long-term effect along with adverse action of epalrestat, an aldose reductase inhibitor, a randomized, prospective study was conducted over the period of 3 years at 112 facilities. Six hundred and three diabetic patients with median motor conduction velocity (MCV)>40 m/s, HbA1c

OBJECTIVE—We sought to evaluate the long-term efficacy and safety of epalrestat, an aldose reductase inhibitor, on diabetic peripheral neuropathy. RESEARCH DESIGN AND METHODS—Subjects with diabetic neuropathy, median motor nerve conduction velocity (MNCV) ≥40 m/s, and HbA1c ≤9% were enrolled in this open-label, multicenter study and randomized to 150 mg/day epalrestat or a control group. After excluding the withdrawals, 289 (epalrestat group) and 305 (control group) patients were included in the analyses. The primary end point was change from baseline in median MNCV at 3 years. Secondary end points included assessment of other somatic nerve function parameters (minimum F-wave latency [MFWL] of the median motor nerve and vibration perception threshold [VPT]), cardiovascular autonomic nerve function, and subjective symptoms. RESULTS—Over the 3-year period, epalrestat prevented the deterioration of median MNCV, MFWL, and VPT seen in the control group. The between-group difference in change from baseline in median MNCV was 1.6 m/s (P < 0.001). Although a benefit with epalrestat was observed in cardiovascular autonomic nerve function variables, this did not reach statistical significance compared with the control group. Numbness of limbs, sensory abnormality, and cramping improved significantly with epalrestat versus the control group. The effects of epalrestat on median MNCV were most evident in subjects with better glycemic control and with no or mild microangiopathies. CONCLUSIONS—Long-term treatment with epalrestat is well tolerated and can effectively delay the progression of diabetic neuropathy and ameliorate the associated symptoms of the disease, particularly in subjects with good glycemic control and limited microangiopathy.

OBJECTIVE—The purpose of this study was to evaluate the efficacy of fidarestat, a novel aldose reductase (AR) inhibitor, in a double-blind placebo controlled study in patients with type 1 and type 2 diabetes and associated peripheral neuropathy. RESEARCH DESIGN AND METHODS—A total of 279 patients with diabetic neuropathy were treated with placebo or fidarestat at a daily dose of 1 mg for 52 weeks. The efficacy evaluation was based on change in electrophysiological measurements of median and tibial motor nerve conduction velocity, F-wave minimum latency, F-wave conduction velocity (FCV), and median sensory nerve conduction velocity (forearm and distal), as well as an assessment of subjective symptoms. RESULTS—Over the course of the study, five of the eight electrophysiological measures assessed showed significant improvement from baseline in the fidarestat-treated group, whereas no measure showed significant deterioration. In contrast, in the placebo group, no electrophysiological measure was improved, and one measure significantly deteriorated (i.e., median nerve FCV). At the study conclusion, the fidarestat-treated group was significantly improved compared with the placebo group in two electrophysiological measures (i.e., median nerve FCV and minimal latency). Subjective symptoms (including numbness, spontaneous pain, sensation of rigidity, paresthesia in the sole upon walking, heaviness in the foot, and hypesthesia) benefited from fidarestat treatment, and all were significantly improved in the treated versus placebo group at the study conclusion. At the dose used, fidarestat was well tolerated, with an adverse event profile that did not significantly differ from that seen in the placebo group. CONCLUSIONS—The effects of fidarestat-treatment on nerve conduction and the subjective symptoms of diabetic neuropathy provide evidence that this treatment alters the progression of diabetic neuropathy.

A number of diabetic patients with diabetic neuropathy were treated with epalrestat, an aldose reductase inhibitor, since this drug was launched into the market in Japan. More than 5000 patients with diabetic neuropathy who were treated with epalrestat for 3-12 months were treated to analyze the efficacy and the adverse reactions of the drug in this study. The improvement rates of subjective symptoms (i.e., spontaneous pain, numbness, coldness, and hypoesthesia) was 75% (slightly improved or better) and those of nerve function tests (i.e., motor nerve conduction velocity, sensory nerve-conduction velocity, and vibration threshold) 36%. Adverse drug reactions were encountered in 129 cases (2.5%) out of 5249 patients, none of which were severe ones. Although data are limited, they strongly suggest that epalrestat is a highly effective and safe agent for the treatment of diabetic neuropathy.

The clinical efficacy of troglitazone, a new oral hypoglycaemic agent was investigated in Type 2 diabetes in combination with sulphonylureas. Two hundred and ninety-one patients with Type 2 diabetes (age 21-81 years) whose previous glycaemic control by sulphonylureas was judged stable but unsatisfactory (fasting plasma glucose (FPG) > 8.3 mmol I-1) were randomly allocated into the troglitazone treatment group (troglitazone group, n = 145) or the placebo treatment group (placebo group, n = 146). They were treated by test drugs for 12 weeks in combination with the same dose of sulphonylureas before the trial. One hundred and twenty-two patients who received troglitazone and 126 patients who received placebo were evaluated for efficacy. The baseline characteristics did not differ significantly between the two groups. In the troglitazone group, FPG and HbA(1c) decreased significantly after the treatment (before vs after, FPG: 10.8 +/- 2.0 mmol I(-1) vs 9.2 +/- 2.5 mmol I(-1), p< 0.001; HbA(1c): 9.2 +/- 1.4% vs 8.5 +/- 1.5%, p< 0.001). FPG and HbA(1c) did not change after the treatment in the placebo group (before vs after, FPG: 10.5 +/- 1.7 mmol I(-1) vs 10.7 +/- 2.2 mmol I(-1); HbA(1c): 9.0 +/- 1.5% vs 9.2 +/- 1.6 %). Serum total cholesterol and HDL-cholesterol did not change in either group, however, serum triglyceride significantly decreased in the troglitazone group. No serious adverse events occurred in either group. In conclusion, troglitazone 400 mg day(-1) had a significant hypoglycaemic effect in combination with sulphonylureas without any serious adverse events. Troglitazone, developed as an insulin action enhancer, can be a useful hypoglycaemic agent in the treatment of patients with Type 2 diabetes who are not well controlled by sulphonylureas alone.

OBJECTIVE To investigate the clinical efficacy of troglitazone, a newly developed oral hypoglycemic agent, in patients with NIDDM. RESEARCH DESIGN AND METHODS There were 284 NIDDM patients (20–82 years of age) whose glycemic control while on a diet was judged stable but was judged unsatisfactory (fasting plasma glucose [FPG] ≥ 8.3 mmol/l) when entered into a multicenter and double-blind study with parallel groups study. They were randomly allocated into two groups, the troglitazone group (the T group: 400 mg/day p.o.) and the placebo group (the P group), and were treated with test drugs for 12 weeks. RESULTS We evaluated efficacy in 136 patients of the T group and 126 patients of the P group. There was no significant difference in any of baseline characteristics between the T and P groups. In the T group, FPG and HbA1c decreased significantly after treatment (before versus after, FPG 10.1 ± 1.6 vs. 8.8 ± 1.9 mmol/l, P < 0.001; HbA1c: 8.6 ± 1.5 vs 8.1 ± 1.7%, P < 0.001). FPG and HbA1c did not change after treatment in the P group (before versus after, FPG 10.1 ± 1.8 vs. 9.9 ± 2.1 mmol/l; HbA1c 8.5 ± 1.5 vs. 8.6 ± 1.6%). Of 136 patients in the T group, 62 (45.6%) were classified as responders. Serum triglyceride level also decreased in the T group but not in the P group. Body weight increased slightly only in the T group. There were no differences in changes in blood pressure between the two groups. No serious adverse events occurred in either group. CONCLUSIONS Troglitazone at 400 mg/day decreased FPG and HbA1c significantly in NIDDM patients who had failed to respond to diet therapy. Troglitazone, developed as a drug to enhance insulin action, can be a useful hypoglycemic agent for the treatment of NIDDM.

To investigate the significance of fructose-induced protein modification, we examined both fructose- and glucose-induced protein oxidation and the formation of advanced glycation end products (AGE) in vitro. Albumin incubated in the presence of 100 mM fructose at 37 degrees C for 1 week showed 5.1-fold and 3.1-fold increases in the content of carbonyl, which is a marker for oxidized protein, when compared with either control incubated without sugar or with 100 mM glucose. Similarly, the same incubation with fructose increased the fluorescence intensity over 100-fold and 15-fold formation compared with that of no sugar and glucose controls, respectively. Both fructose-induced fluorescence and protein oxidation were almost completely suppressed in the presence of the iron chelator; deferoxamine (100 microM), the hydroxyl radical scavenger; MK-447 (1 mM), or aminoguanidine (200 mM), which is an inhibitor of AGE formation. In contrast, the fructose-induced formation of fluorescent albumin was potentiated in the presence of 100 microM FeCl2. This was completely inhibited in the presence of 60 microM or more deferoxamine. These results suggest that fructose promotes both AGE formation and protein oxidation possibly through the formation of hydroxyl radicals.

The clinical efficacy of epalrestat (150 mg/day, 50 mg tid, po; A group), an aldose reductase inhibitor, was evaluated in 196 patients with diabetic neuropathy by a double-blind study using placebo (9 mg/day, 3 mg tid, po; P group) as a control for 12 weeks. The disappearance rates of upper limb spontaneous pain were 42.9% and 12.0% in the A and P groups, respectively, and those of lower limb spontaneous pain 48.6% and 22.6%, thus being significantly higher in the A group (p0.05, logrank-test). The motor nerve conduction velocity of the peroneal nerve significantly increased only in the A group (delta 1.6 +/- 0.6 m/sec, p0.01, paired t-test), and the extent of increase in that of the median nerve was significantly greater in the A group than in the P group (p0.05). Thresholds of vibratory sensation and autonomic nerve function were also significantly improved in the A group (p0.05). The data were reanalyzed by dividing patients into two groups according to their HbA1c values. The improvement ratings of subjective symptoms and of nerve function tests for cases with HbA1cor = 7.5% were both significantly different between the A and P groups, with the improvement rate being higher in the A group, and also higher as compared to the analysis for cases with HbA1c7.5%.(ABSTRACT TRUNCATED AT 250 WORDS)

According to a national survey of dialysis patients in Japan conducted by the Japanese Society for Dialysis Therapy, there were 1,033 patients on dialysis in the Shiga area which has a population of about 1.2 million. Of these 1,033 dialysis patients 140 were the result of diabetic nephropathy. From four hospitals affiliated to Shiga University of Medical Science the medical records of 90 diabetic subjects on dialysis therapy were reviewed and various clinical parameters were analysed and compared with those of patients with chronic glomerulonephritis. Since only one patient had Type 1 (insulin-dependent) diabetes, the remaining 89 with Type 2 (non-insulin-dependent) diabetes were used for this study. The significantly different variables between patients with Type 2 diabetes and chronic glomerulonephritis were age (60.4 vs 54.6 years,p

Dorsal column function and peripheral motor and sensory conduction velocities (MCV, SCV) were evaluated in experimental diabetic rats and compared with those in 2,5-hexanedione (2,5-HD) intoxicated rats. Hyperglycemia was induced by a single injection of streptozocin, and electrophysiological studies were performed 4 and 12 weeks after the injection. For 8 weeks 2,5-HD was administered daily by drinking water to make the 2,5-HD neuropathy rats. Age-matched rats were used as control. In diabetic rats, gracile surface potentials evoked by electrical stimulation of the lumbosacral trunk remained normal during the experimental period, whereas the N and P waves of the evoked potentials were suppressed and the duration of the N wave was prolonged in the 2,5-HD rats. In 4-week diabetic rats, the antidromic compound action potentials of the gracile tract recorded at the most proximal site of lumbosacral trunk were normal. In 12-week diabetic rats, the gracile tract conduction velocity (GTCV) was decreased, although the duration of these potentials was normal. By contrast, the GTCV was decreased and the duration was markedly prolonged in 2,5-HD rats. These findings might indicate that temporal dispersion of incoming volleys in the gracile tract is increased in 2,5-HD rats, but not in diabetic rats. These results suggest that diabetic myelopathy exists that but the magnitude and progression of this condition are quite different from those of 2,5-HD intoxication, typical dying-back-type neuropathy and that the dorsal column is less vulnerable than the peripheral nerve in diabetes mellitus.

We evaluated the effects of chronic verapamil treatment on the cardiac alpha 1-adrenoceptor signalling system in streptozocin-induced diabetic rats. The decrease in maximum cell surface [3H]bunazosin binding (Bmax) in isolated cardiac myocytes from the diabetic group (-46%, P0.01) was completely reversed by a 4-week course of verapamil, while Bmax in the verapamil-treated control group was unchanged. Similarly, the reduction in ventricular inositol 1,4,5-trisphosphate (IP3) production after stimulation with 10 microM noradrenaline (NA) seen in diabetes (-30%, P0.01) was completely normalized by verapamil, while the response in the verapamil-treated control group was unaffected. These results indicate that verapamil can induce complete recovery of the impaired cardiac alpha 1-adrenoceptor signalling system in the diabetic heart without affecting glucose metabolism.

In order to clarify if vasopressin (VP) plays a role in the pathophysiology of hyperosmolar nonketotic diabetic coma (HNDC), VP has been infused to diabetic rats and plasma levels of glucose (PG), ketone bodies, FFA and glucagon were determined. High-dose VP infusion (1.2 U/kg/h) caused gradual elevation of PG (60%) and glucagon levels (600%), while ketone bodies showed transient decrease (20%) at 30 min. Under the suppression of endogenous glucagon secretion by constant infusion of somatostatin (100 micrograms/kg/h), high dose VP showed 25% increase in PG levels and 30% reduction of ketone body levels for the subsequent VP infusion for 1.5 hour. Low-dose VP infusion (0.06 U/kg/h) had no hyperglycemic effect, but suppressed ketosis (20%) in the same condition. There were no changes in plasma FFA concentrations, indicating no significant effect of VP on lipolysis. The results indicate that VP often elevated in HNDC may play an important role for the pathophysiology of HNDC through suppression of hepatic ketogenesis.

A forty-one-year-old male who was found to have lung carcinoid tumor showed clinical features of Cushing syndrome. At the age of 38 years during a regular check-up, a chest roentgenogram showed multiple nodular shadows in the bilateral lung, and he was admitted to hospital. By open lung biopsy, he was diagnosed as having malignant carcinoid or small cell carcinoma of the lung. The abnormal lung shadows did not respond to chemotherapy (CDDP + VDS). The clinical course after discharge was uneventful until the age of 41 years, when he was readmitted to our hospital because of brain metastasis. Physical examination revealed moon face and central obesity. Plasma ACTH level was high and dexamethasone suppression test showed no cortisol suppression on 8 mg dexamethasone administration. Therefore, it was thought that the patient had ACTH producing ectopic tumor which led to Cushing syndrome. We measured the molecular weight of ACTH by column chromatography and found he had a big ACTH (molecular weight about 22,000). Reexamining him clinically and histologically, we concluded that the patient had atypical carcinoid tumor in the lung which might produce ACTH causing Cushing syndrome with metastasis to the brain.

CS-045, (+/-)-5-[4-(6-hydroxy-2,5,7,8-tetramkethylchroman-2- ylmethoxy)benzyl]-2,4-thiazolidinedione, lowers plasma glucose in several animal models of non-insulin dependent diabetes mellitus (NIDDM) presumably by increasing insulin sensitivity. Little adverse effect was found in a phase 1 study on healthy male subjects. In order to test its efficacy in lowering plasma glucose in NIDDM in man, a pilot multi-center clinical trial of CS-045 was carried out in 146 patients with NIDDM whose glycemic control was inadequate (FPG greater than 140 mg/dl) on diet and/or other oral hypoglycemic agents. CS-045 was given orally in a daily dose of 200 mg or 400 mg for 12 weeks in addition to the previous treatment. The mean fasting plasma glucose (FPG) and fructosamine began to decrease within 2 weeks and the mean HbA1c within 8 weeks. After 12 weeks, the FPG fell from 192 +/- 41 to 155 +/- 45 mg/dl (P less than 0.01), fructosamine from 3.7 +/- 0.6 to 3.3 +/- 0.6 (P less than 0.01), and HbA1c from 8.9 +/- 1.5 to 8.1 +/- 1.5% (P less than 0.01). The drug was effective in 39% of patients in that FPG fell by more than 20% of the initial value. This rate of efficacy was the same when CS-045 was given alone or together with other oral hypoglycemic agents. The drug was more effective in a dosage of 400 mg than with 200 mg (the rate of efficacy 46% vs 25%) and more effective in obese patients than in lean patients (46% vs 25%).(ABSTRACT TRUNCATED AT 250 WORDS)

To determine the effectiveness of dietary protein restriction on proteinuria in patients with non-insulin dependent diabetes (NIDDM), 14 diabetic patients with overt nephropathy were placed on either a low protein diet (N = 7) or conventional protein diet (N = 7) for one month. After the study period, daily urinary protein excretion rates decreased significantly, from 3.2 +/- 0.4 to 1.9 +/- 0.4 g/day, and serum albumin levels increased from 3.3 +/- 0.2 to 3.7 +/- 0.5 g/dl only in the low protein diet group, without any significant changes in either serum creatinine levels or creatinine clearance. These findings suggest that dietary protein restriction has a beneficial role in the treatment of NIDDM patients with overt nephropathy.

A film test for the rapid detection of plasma/serum 3-hydroxybutyrate (3-OHB) has been developed. The film contains NAD, nitro blue tetrazolium, 3-OHB dehydrogenase, and diaphorase, and the surface is coated with modified biomembrane and can detect 50-1500 microM 3-OHB within 2-3 min. One drop or 50 microliters of plasma/serum or blood is applied to the film, and the violet color is read via reflectance meter after 2 min. Plasma/serum samples greater than 1500 microM 3-OHB can be measured by dilution with saline. In blood with 40% hematocrit, the color developed is 50% less than with plasma/serum, and this was adjusted in the reflectance meter. A good correlation (r = 0.99) was observed between results with automated and film methods and between visual methods and reflectance meter. In insulin-dependent diabetes mellitus, all 3 subjects with positive ketonuria (+ +), 8 of 12 subjects with mild ketonuria (+), and 7 of 25 subjects without ketonuria exhibited elevation of 3-OHB in blood greater than 200 microM. The results indicate that 3-OHB film is valuable not only in the emergency room for the differential diagnosis between ketoacidotic and nonketotic hypersomolar coma but also as a marker for insulin dependency, energy dependency on fatty acid compared with glucose, and metabolic control of diabetes.

In order to assess the relationship between clinical efficacy of troglitazone on glycemic control and baseline characteristics of patients with NIDDM, we analyzed the data of ten clinical studies on troglitazone carried out in Japan. The study consisted of 604 subjects with NIDDM whose glycemic control had been unsatisfactory (fasting plasma glucose (FPG)or = 8.3 mM) with diet or sulfonylureas (SU) and who had been assigned to one of ten clinical studies at a dose of 400 mg/day troglitazone for 12-16 weeks. In patients who had been treated with SU, troglitazone was given in combination with the SU drugs. The percentage decrease in FPG was adopted as the index of clinical efficacy. The relationship between this index and various baseline parameters of patients was analyzed. It was found that FPG and triglycerides decreased significantly with troglitazone (pre- and post-treatment: FPG 10.3 +/- 2.0 and 8.7 +/- 2.2 mM; triglyceride 1.82 +/- 1.27 and 1.51 +/- 0.99 mM, respectively). The percentage decrease in FPG after treatment did not differ between groups treated with troglitazone alone and those treated with troglitazone in combination with SU drugs (14.7 vs. 15.5%). Patients were classified into two groups according to the percentage decrease in FPG, greater and less than 15%. The group with greater decrease in FPG included more females and had the older mean age, greater body mass index (BMI), higher pre-treatment FPG, and higher pre-treatment C-peptide values. In the multiple regression analysis, female gender, age, BMI and pre-treatment FPG level were selected as the variables for the best regression model. The results indicate that troglitazone at 400 mg/day decreased FPG significantly in patients with NIDDM and the percentage decrease in FPG was positively correlated with female gender, higher pre-treatment FPG, older age, greater BMI and higher C-peptide level. The results suggest that this drug is more effective in patients with greater insulin resistance, in keeping with its proposed mode of effect.

To delineate the ability of diabetic nerves to regenerate and to determine the effect of aldose reductase (AR) inhibitors (ARIs) on nerve regeneration in diabetic neuropathy, we evaluated nerve regeneration electrophysiologically and morphologically after sciatic nerve crush injury in three groups of male Sprague-Dawley rats: untreated diabetic (streptozocin [STZ]-induced, n = 16), tolrestat-treated diabetic (n = 16), and age-matched controls (n = 16). Compound muscle action potentials (CMAPs) appeared 4 weeks after crush injury in the control group and 5 weeks after injury in both diabetic groups. Motor nerve conduction velocity (MNCV) in the crushed nerves was decreased in both diabetic groups compared with the control group throughout the experiment. However, this decrease was significantly prevented at 24 weeks with tolrestat treatment. Morphologically, the density of myelinated nerve fibers (MNFs) and the number of MNFs per fascicle were significantly decreased in untreated diabetic rats, but tolrestat significantly prevented the former decrease at 5 weeks and the latter at 24 weeks. The mean diameter of large MNFs (>4 μm) was smaller in the untreated diabetic group than in the control group, but this decrease also was significantly prevented with tolrestat treatment. These results suggest that nerve regeneration is impaired in diabetic neuropathy and that tolrestat can prevent this impairment.

In order to clarify the mechanisms of interaction between endothelin-1 (ET-1) and cyclic AMP (cAMP) or cyclic GMP (cGMP), we examined the effects of cAMP or cGMP on ET-1-induced activation of mitogen-activated protein kinase (MAPK), one of the key enzymes in the signal transduction of ET-1, in cultured rat mesangial cells. ET-1 was able to activate both p42 and p44 MAP kinases in a dose-dependent manner. Cell permeable analogues of cAMP and cGMP, dibutylyl cAMP (BT2-cAMP) and 8 bromo cGMP (8br-GMP), significantly inhibited ET-1-induced activation of MAPK. Atrial natriuretic peptide (ANP), which increased cellular cGMP, was able to inhibit ET-1-induced activation of MAPK in a dose-dependent manner, while c-ANP, an analogue specific to the clearance receptors of ANP, exerted no effect. These results indicate that cAMP and cGMP could modulate the action of ET-1 in mesangial cells at a step of the activation of MAPK.

In order to examine whether the existence of microalbuminuria can predict the development of overt proteinuria and cardiovascular death in Japanese subjects with non-insulin-dependent diabetes mellitus (NIDDM), we investigated 47 patients for a 10-year follow-up period. Patients were divided into two groups by the initial values of urinary albumin excretion rates. The percentage of patients who developed overt proteinuria during the follow-up period was significantly higher in patients who were initially classified as microalbuminuric group (63.6%) than in normoalbuminuric group (17.4%). During the follow-up period, one of the patients with normoalbuminuria had died of congestive heart failure, while four of those with microalbuminuria had died; one of stroke and three from noncardiovascular diseases. These results indicate that the existence of microalbuminuria had the predictive power for the development of overt proteinuria, but not for cardiovascular death in Japanese subjects with NIDDM.

We identified three families having a mutation in the mitochondrial tRNA(LEU(UUR)) gene at bp 3243 in 300 patients with non-insulin dependent diabetes mellitus (NIDDM), who had first degree relatives of patients with NIDDM. We found six individuals with diabetes, one with impaired glucose tolerance (IGT), and five with normal glucose tolerance (NGT) among three families. Insulin secretory response to oral glucose load was impaired in six diabetics, but was normal in IGT and NGT, and the proportion of mutant DNA in the blood did not always associate with the severity of glucose intolerance. Furthermore, both gender and obesity may influence the clinical expression of diabetes in three pairs with an age-matched brother-sister relationship with similar high mutation rate in blood samples. Thus, although patients with mitochondrial gene mutation had a high frequency of diabetes, the proportion of mutant DNA evaluated by blood samples may not necessarily indicate glucose intolerance in the members with the mutation. Unidentified factors including gender, aging, and obesity may alter the clinical manifestation of diabetes.

Obesity is considered to be one of the major risk factors for developing non-insulin dependent diabetes mellitus (NIDDM). Our cohort study for NIDDM in Aito, Shiga 1980-1990 confirmed that aging, higher body mass index (obesity) and high blood pressure were independent risk factors for developing NIDDM in Japan. In Pima Indians, decreased glucose disposal rate (GDR) is significantly related to percentage of body fat (%fat). Insulin signaling for glycogen synthesis in the skeletal muscles is impaired in the early stages of obesity. Although the molecular mechanism for insulin resistance in obesity is still unknown, hyperinsulinemia induces insulin receptor loss by means of the down regulation mechanism, and prolonged hyperglycemia may induce the impairment of insulin receptor kinase in the skeletal muscles in obese subjects. These dysfunctions in insulin signaling may cause the deterioration of insulin sensitivity, resulting in worsening glycemic control. Thus dysfunction of insulin receptor signaling in skeletal muscles may be a target for preventing diabetes in obese subjects.

According to a nation-wide survey of dialysis patients in Japan the number of diabetic patients with end-stage renal failure introduced to dialysis therapy has been increasing year by year, exceeding 6000 cases (28% of total cases) in 1991. A six-fold increase in numbers and a three-fold increase in percentages (DM/total) were observed in the past ten years. Although the medical technology and regimen in dialysis therapy have been greatly improved, the prognosis of those diabetic patients on maintenance dialysis has remained unsatisfactory. Their quality of life has been severely damaged mostly because of the impairment of visual acuity. The early detection and early introduction of effective therapy for diabetic nephropathy, therefore, may be the most imminent tasks necessary to prevent the various problems afflicting diabetic patients on end-stage renal failure.

In order to clarify the possible contribution of the abnormal polyol pathway to the development of diabetic nephropathy, the effect of aldose reductase inhibitor on renal function and morphology was examined in streptozotocin (STZ)-induced diabetic rats. Six months after STZ injection, glomerular filtration rate and renal plasma flow showed marked decline with significant increase in nuclear-free mesangial area (MA) and relative mesangial area (RMA; MA per glomerular area) in diabetic rats. Oral administration of an aldose reductase inhibitor, Epalrestat, prevented renal hypofunction and mesangial expansion in diabetic rats without influencing the levels of blood glucose. These results suggest that the abnormal polyol pathway in diabetic rats is closely related to the development of mesangial expansion, a morphologic representative of diabetic glomerulopathy, and renal hypofunction.

A 71-year-old man with a history of sarcoidosis was admitted to our hospital because of polyuria and polydipsia. On admission, the serum calcium concentration was elevated to 12.7mg/dl, and the creatinine clearance was 28.3ml/min. The initial serum 1,25-dihydroxyvitamin D concentration was 55.0pg/ml, while angiotensin-converting enzyme activity and serum PTH-rP concentration were within the normal range. Radiological studies revealed enlargement of bilateral hilar lymph nodes and a nodular lesion in the right lower lung field. Transbronchial lung biopsy showed noncaseous granuloma consistent with pulmonary sarcoidosis. After oral administration of 20mg prednisolone daily, the serum calcium and 1,25-dihydroxyvitamin D concentration returned to normal, and creatinine clearance was raised to 55ml/min. In conclusion, low dose glucocorticoid administration successfully reduced serum 1,25-dihydroxyvitamin D level with a prompt decrease in serum calcium level in a patient with sarcoidosis.

A 54-year-old woman presented proteinuria and severe hyperlipoproteinemia, She had type III hyperlipoproteinemia with the phenotype E2/2. Renal biopsy specimen revealed lipoprotein thrombi within the glomerular capillary lumina without tubulointerstitial lesion and deposition of IgA in the mesangium and peripheral capillary loops, indicating lipoprotein glomerulopathy with IgA nephropathy. Treatment with probucol resulted in the improvement of both hyperlipoproteinemia and proteinuria with the disappearance of the lipoprotein thrombi in the glomerular capillary without any change in the mesangial IgA deposition. The data suggest that probucol may be effective against the early stage of lipoprotein glomerulopathy with less lipoprotein thrombi and without tubulointerstitial damage.

In order to produce a model of ischemic neuropathy with neural microvascular alterations, sodium laurate was injected into a femoral artery and saline into the contralateral artery at the mid-thigh level in Sprague-Dawley rats aged 11 weeks. In view of the dose-related findings, 0.3 mg sodium laurate dissolved in 0.1 ml saline was used for the main experiment. The laurate-injected leg showed paresis during the experimental period. On day 1-7, various stages of Wallerian degeneration and acute microvascular changes were found. At 1 month, regenerating myelinated nerve fibers (MNFs) were found at the central or total fascicular area mainly in the distal tibial nerve. Morphometric analyses suggested that MNFs other than regenerating fibers are atrophic ones. The proliferative changes of nutrient microvascular walls were striking. The percent of closed epineurial microvessels was significantly larger on the laurate-injected sides and inversely associated with the diameter of MNFs. At 7 months, the attenuation of MNFs was more prominent and microvascular alterations were persistently observed. These pathological findings resemble those of chronic ischemic neuropathy including diabetic neuropathy, suggesting that this neuropathy model might provide some valuable and useful clues for clarifying the pathogenesis of chronic ischemic neuropathy.

To evaluate the possible contribution of atrial natriuretic peptide (ANP) to the development of glomerular hyperfiltration, we examined the effect of non-peptide competitive antagonist for biological receptors of ANP, HS-142-1, on glomerular filtration rate (GFR) and renal plasma flow (RPF) in diabetic rats. Increased GFR and RPF in diabetic rats were significantly ameliorated by the injection of HS-142-1, while blood pressure remained unchanged. Urinary cyclic GMP excretion was significantly higher in diabetic rats than in control rats and HS-142-1 decreased urinary cGMP excretion significantly. These results indicate that atrial natriuretic peptide contributes to the development of glomerular hyperfiltration and hyperperfusion in diabetes and HS-142-1 might be useful in the treatment of them.

To evaluate the activation of the sorbitol pathway in cardiac muscle in diabetic rats, we measured sorbitol, fructose, and myo-inositol content in cardiac tissue obtained from control and streptozotocin-diabetic rats, with or without an 8-week insulin treatment, using gas chromatography-mass spectrometry (GC-MS). Cardiac fructose and sorbitol content in 10-week diabetic rats increased by 60-fold and 3.9-fold of those of control rats, respectively (P less than .001). In contrast, cardiac myo-inositol content in 10-week diabetic rats decreased to 56% (P less than .025) of the control value. The abnormalities in cardiac fructose, sorbitol, and myo-inositol content were completely normalized by the 8-week insulin treatment, which was initiated 2 weeks after the induction of diabetes. There was no difference in cardiac aldose reductase activity between control and diabetic rats. However, cardiac sorbitol dehydrogenase activity in diabetic rats was 151% (P less than .005) higher than that of control rats, although hepatic sorbitol dehydrogenase activity was not different between the two groups. These results indicate that the sorbitol pathway is significantly activated in cardiac tissue obtained from streptozotocin-induced diabetic rats, which results in the marked cardiac accumulation of fructose.

Hypertension is a very frequent condition in individuals with non-insulin dependent diabetes mellitus (NIDDM) in Japan and has affected the occurrence of late diabetic complications, especially stroke and nephropathy. Despite similar characteristics of hypertension among Japanese and white patients, the effect of hypertension on the development of coronary artery disease (CAD) in these two populations is strikingly different. In white NIDDM patients, hypertension is one of the major risk factors for the development of CAD. However, CAD is an infrequent complication in NIDDM patients in Japan, even though they have hypertension, lipid abnormalities, and renal complications.

A family with multiple spinal xanthomas and sitosterolemia is described. A 48-year-old woman presented with paraplegia due to multiple intradural extramedullary tumors. The patient also showed marked tendon xanthomas and analysis of sterol composition in both plasma and the xanthoma established the diagnosis of the rare inherited metabolic disease, sitosterolemia and xanthomatosis. Two other siblings in the family presented with marked tendon xanthomas and coronary atherosclerosis, but did not show any neurological signs or symptoms. Magnetic resonance imaging (MRI) study revealed multiple intradural extramedullary tumors in spinal canals of the proband and her sister, but not in the other affected sibling (brother). This is the first report of familial occurrence of multiple extramedullary spinal tumors due to the inherited metabolic abnormality.

In view of the possible implication of multifactorial mechanisms in the pathogenesis of diabetic neuropathy, the aldose reductase inhibitor (ARI), Statil, which ameliorates abnormal sorbitol or myo-inositol metabolism in diabetic nerves, and the prostaglandin E1 (PGE1) analogue, OP1206.alpha CD (OP), which improves diabetic vascular derangements, were administered simultaneously for 2 months to streptozocin (STZ)-induced diabetic rats with 5 months' duration of diabetes, and the effects on sciatic motor nerve conduction velocity (MNCV), Na(+)-K(+)-adenosine triphosphatase (ATPase) activity, and morphology of myelinated nerve fibers (MNF) were compared with the effects of a monotherapy with OP. The combination regimen ameliorated abnormal nerve sorbitol and myo-inositol levels and normalized decreased MNCV and enzyme activity. In contrast, neither sorbitol nor myo-inositol metabolism was ameliorated, and only insufficient improvement of MNCV and morphology of MNF was obtained with a monotherapy with OP. In addition, the combination therapy reversed both a decrease in the percent of large MNF and an increase in the percent of small MNF in diabetic rats, whereas a monotherapy with OP reversed only a decrease in the percent of large MNF. The results might suggest that a multiple-drug therapy with different mechanisms of action has greater effects on diabetic neuropathy than a single-drug therapy and is worthy of clinical consideration.

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.

Chronic insulinopenic diabetes was induced by i.v. streptozotocin in the non-human primate Macaca fuscata. Five diabetic monkeys were kept for 8-19 months and nine for 24-48 months without any insulin treatment. Hyperglycemia (241 +/- 22 mg/dl, M +/- SE less than or equal to 1 year) progressed to 376 +/- 34 mg/dl (greater than 2 years) and ketosis to 3.5 mM (greater than 2 years) during the course of diabetes; this was roughly inversely proportional to hypoinsulinemia (3.4 microU/ml, 2 years). Serum cholesterol increased from 184 +/- 11 (less than or equal to 1 year) to 328 +/- 66 mg/dl (greater than 2 years) with the major increase in LDL-cholesterol (2.7-fold over control, greater than 2 years). HDL-cholesterol did not change at all throughout the experimental period. TG increased from 144 +/- 25 (less than or equal to 1 year) to 676 +/- 116 (greater than 2 years) with a major increase in the VLDL fraction (15-fold over control, greater than 2 years). Serum levels of apo B increased to 141 +/- 16 (less than or equal to 2 years) and 223 +/- 8 mg/dl (greater than 2 years) in contrast to control, 73 +/- 2. Morphologically, lipid deposition in the intima and fatty streaks have been observed in the abdominal aorta of all the diabetic monkeys with duration of more than 2 years. In six of the diabetic monkeys atheromatous changes such as intimal and medial thickening with smooth muscle cell proliferation were observed with foam cell formation. Similar atherosclerotic lesions were observed in renal and coronary arteries in at least six of these monkeys. In diabetic monkeys with duration of less than 2 years, mild atherosclerotic lesions were observed in two out of five. The results indicate that long standing insulinopenia leads to metabolic derangements characterized by hyperglycemia, ketonemia and hyperlipidemia. Elevation of LDL-cholesterol and VLDL TG with an increase of apo B is a characteristic of lipoprotein disorder. Morphologically, early to moderately advanced lesions of atherosclerosis were observed in aorta, renal and coronary arteries as a result of metabolic derangement due to insulin deficiency.

A new oral agent, 5-[4-(2-(5-ethyl 12-pyridyl)ethoxy]- benzoyl]-2,4-thiazolidinedione (pioglitazone), has been developed for treatment of non-insulin-dependent diabetes mellitus (NIDDM). This agent increases insulin sensitivity in vivo in genetically obese Wistar fatty rats. Administration of the agent (3 mg/kg/day) for 10 days to the rats ameliorated hyperglycemia and hyperinsulinemia, indicating that it decreased insulin resistance. To clarify the mechanism of the drug to increase insulin sensitivity, we examined insulin binding and kinase activity of insulin receptors from muscles of both untreated and treated rats. Pioglitazone treatment did not change insulin binding in Wistar fatty rats but increased insulin-stimulated autophosphorylation of insulin receptors to 78% over the level in the control but not the basal state. Kinase activity toward exogenous substrate, poly Glu4Tyr1, was also increased to 87% over the level of untreated control obese rats. In contrast, in lean rats, pioglitazone treatment did not increase autophosphorylation and kinase activity toward exogenous substrates. To further elucidate the mechanism, we incubated insulin receptors with the agent and measured kinase activity. Incubation of solubilized receptors with the agent did not increase kinase activity. However, the receptors from IM-9 cells, which were incubated with 10−8 M pioglitazone for 7 days, showed a 46% increase over the control in insulin-stimulated autophosphorylation and kinase activity. These results suggested that pioglitazone increased insulin sensitivity in part by activating kinase of the receptors through indirect effect on insulin receptors and that the drug may have useful benefits in insulin resistance of NIDDM.

Many lines of evidence including epidemiological (1), clinical (2,3) and experimental (4,5) studies have shown the existence of specific abnormalities in cardiac muscle in diabetes. Recently, it has been suggested that Ca2+ overload into cardiac muscle may be one of the contributing factors for cardiomyopathy (6). Furthermore, an increase in tissue Ca2+ level has been reported in chronic diabetic rats (7), which may be associated with cardiomyopathy in diabetes (8). Interestingly, Afzal N. et al. (9) have shown that treatment of streptozotocin-diabetic rats with verapamil, a voltage- sensitive Ca2+ channel blocker, improves cardiac dysfunction. These reports suggest that an excess Ca2+ influx through voltage-sensitive Ca2+ channel may induce cardiomyopathy in diabetes. However, there has been no report on voltage sensitive Ca2+ channel in diabetic rat heart. Therefore, in the present study, we have examined the status of Ca2+ channels in cardiac muscle as well as skeletal muscle membrane from control and streptozotocin- induced diabetic rats using [3H]PN200-110, a dihydropyridine derivative as a ligand.

The pathogenic mechanism of diabetic nephropathy has been extensively investigated, and the significance of alteration in glomerular hemodynamics or mesangial cell metabolism has been recently clarified. It is expected that in the near future these pathologically important alterations can be corrected, and the development diabetic nephropathy can be halted.

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-β-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. These results suggested that the reduction of tissue ACE activity in the kidneys of diabetic rats might play an important role for the alteration of renal microcirculation and contribute to the development of diabetic nephropathy.

An oral prostaglandin E1 (PGE1) analogue, OP-1206.alpha-CD, was given to rats with streptozocin (STZ)-induced diabetes to examine the therapeutic effects of OP-1206 on short-term and long-term diabetic neuropathy and its action mechanism with special reference to nerve Na(+)-K(+)-ATPase activity. In the short-term experiment, OP-1206 was administered daily to diabetic rats in 3- and 30-mg/kg doses for 4 wk from the day of STZ injection. In the long-term study, 10 micrograms/kg OP-1206 was also given daily for 8 wk from 7 mo after induction of diabetes. The compound improved decreased sciatic motor nerve conduction velocity in both short-term and long-term diabetic rats. The nerve Na(+)-K(+)-ATPase activity of diabetic rats, reduced by 40% compared with controls, was reversed to the level of controls in both experiments, whereas weight loss and hyperglycemia were unchanged, and neither nerve sorbitol accumulation nor myo-inositol depletion was corrected. In a morphometric analysis of myelinated nerve fibers (MNFs) in long-term diabetes, the mean diameter of the largest 10% of MNFs was significantly reduced in untreated diabetic compared with control rats, but OP-1206 completely reversed this reduction. The results suggest that OP-1206 ameliorates a decrease in nerve Na(+)-K(+)-ATPase activity without any effect on nerve myo-inositol level and that the compound may be not only a potent therapeutic agent for the treatment of diabetic neuropathy but also a useful research tool to investigate the mechanism of nerve Na(+)-K(+)-ATPase activity regulation.

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 μg/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 measangial 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.

A 48-year-old woman with a 30-year history of tendinous xanthomatosis developed paraplegia. The magnetic resonance image revealed extramedullary tumors. The analysis of her sera and tumors revealed increased amount of plant sterols, especially sitosterol, and the diagnosis of sitosterolemia was made. This is the first reported case of a patient with sitosterolemia who had the neurological complication of spinal cord compression due to extramedullary sitosterolemic xanthomas.