Akizuki Morikawa

Apolipoprotein E polymorphism and hyperlipemia in type II diabetics.

The relationship between apolipoprotein E (apoE) polymorphism and plasma lipids and hyperlipemia was investigated in 105 male type II diabetics and 111 male nondiabetics. ApoE phenotypes were determined by a one-dimensional rapid flat gel isoelectric focusing method as described previously. The apoE phenotype frequency in diabetics was similar to that in nondiabetics. The frequency of hyperlipemia was higher in diabetics (56.2%) than in nondiabetics (32.4%). It was highest in the apoE3/2 group of diabetics and nondiabetics, followed by the apoE4/3 and apoE3/3 groups in the order described, indicating that the susceptibility to hyperlipemia differs among the apoE phenotype groups. ApoE3/2 diabetics had significantly higher levels of apoE and very-low-density lipoprotein (VLDL) cholesterol (chol)/VLDL triglyceride (TG) ratios than apoE3/3 diabetics. The effects of diabetes mellitus on plasma lipid levels differed among the various apoE phenotype groups: i.e., plasma total chol and low-density lipoprotein (LDL) chol increased only in apoE3/2 and apoE4/3 diabetics and plasma high-density lipoprotein chol decreased only in apoE3/3 diabetics, as compared with the corresponding apoE phenotype groups of nondiabetics, whereas plasma TG, VLDL TG, and VLDL chol increased in the three apoE phenotype diabetics. Furthermore, an increase of apoEII; apoEIII ratio was observed in apoE3/3 diabetics, particularly in those with hypertriglyceridemia. This study has also shown that the increased apoEII: apoEIII ratio is due to increased sialation of apoE based on the study of sialidase digestion of apo VLDL. We conclude that apoE polymorphism should be taken into consideration when plasma lipoprotein patterns are studied in type II diabetics and that increased sialation of apoE may at least partly contribute to an increased frequency of hypertriglyceridemia in type II diabetics.

Detection of the association between a deletion polymorphism in the gene encoding angiotensin I-converting enzyme and advanced diabetic retinopathy

We investigated the relationship between advanced diabetic retinopathy (ADR) and an angiotensin-converting enzyme (ACE) gene polymorphism in subjects with type 2 diabetes and ADR, pre-proliferative (PrePDR) or proliferative diabetic retinopathy (PDR) without overt nephropathy. Polymerase chain reactions were used to detect insertion/deletion (I/D) polymorphisms of the ACE gene. There was no difference in the frequency of II, ID, or DD genotypes, or of I and D alleles among subjects with type 2 diabetes without diabetic retinopathy (NDR) or with simple diabetic retinopathy (SDR) and non-diabetic controls. There was also no difference in the frequency of ACE genotypes among subjects with type 2 diabetes with NDR, or SDR and ADR. However, the frequency of the ACE DD genotype in ADR was significantly higher than that in controls (chi(2)=6.64, P=0.036). On the other hand, the frequency of the D allele in ADR was significantly higher than that in controls (chi(2)=6.33, P=0.012), NDR (chi(2)=4.18, P=0.041) and SDR (chi(2)=4. 89, P=0.027), respectively. These results indicate a significant relationship between the presence of the D allele polymorphism in the ACE gene and ADR in Japanese subjects with type 2 diabetes and no overt nephropathy.

Which hypoglycaemic agents to use in type 2 diabetic subjects with CKD and how

would obviously be of paramount importance. In the study by Liu et al. [9], hypovolaemia was identified in only 20% of patients, but identifying hypovolaemia retrospectively is difficult so this number may not be accurate. In the clinical situation, assessing ongoing fluid needs and responsiveness is complex as physicians balance the risks of fluid overload with those of hypovolaemia. Second, should vasopressors be used to restore baseline blood pressure or limit the risks of hypotension? This is a controversial area but there is no good evidence that liberal use of vasopressors decreases the incidence of acute renal failure. Finally, what level of arterial pressure should be chosen as the target? Finding one value that could be applicable to all patients would be difficult, perhaps such a value should be related to the patient’s own baseline blood pressure value which may be unknown. Clearly, even if relative hypotension does participate in the development of acute renal failure, focusing primarily on arterial blood pressure as a target may be rather limited. Rather than providing a new goal, these observations by Liu et al. [9] are more a message supporting the importance of early, rapid and complete resuscitation in all patients.

Increased frequency of apolipoprotein epsilon 4 allele in type II diabetes with hypercholesterolemia.

The apolipoprotein E (apoE) phenotype and allele frequencies were examined in type II (non-insulindependent) diabetic patients with normolipidemia (n = 134) and hypercholesterolemia (type IIa hyperlipoproteinemia, n = 35; type lib hyperlipoproteinemia, n = 42). The frequencies of apoE4-present phenotypes (apoE4/3, apoE4/4, and apoE4/2) were highest in the type IIa group (51.4%), followed by the type Mb group (38.1%) and the normolipidemic group (16.4%), respectively, whereas the frequency of the most common phenotype, apoE3/3, was lowest in the type IIa group (48.6%), followed by the type lib group (61.9%) and the normolipidemic group (79.9%), respectively. There were significant differences in the apoE phenotype frequencies between the normolipidemic group and the type IIa and Mb groups. The frequency of the ∈4 allele was significantly higher in the type IIa (28.6%) and Mb (20.2%) groups than in the normolipidemic group (8.9%), whereas the frequency of the ∈3 allele was significantly lower in the type IIa (71.4%) and Mb (78.6%) groups than in the normolipidemic group (89.2%). The frequency of the ∈2 allele tended to be lower in diabetic patients with hypercholesterolemia. In addition, these frequencies were also examined in nondiabetic subjects (n = 59). The frequency of the ∈4 allele tended to be higher in hypercholesterolemic diabetic subjects (24.1%) than in hypercholesterolemicnondiabetic subjects (15.3%). These data suggest that diabetic patients with the ∈4 allele may be more susceptible to hypercholesterolemia than diabetic patients without the ∈4 allele and possibly nondiabetic subjects with the ∈4 allele, although the underlying mechanism is unknown.

Metabolic and morphological changes of the heart in Chinese hamsters (CHAD strain) with spontaneous long-term diabetes

We studied the effect of spontaneous long-term (9-10 months) diabetes on the heart of Chinese hamsters (CHAD strain) to elucidate the relationship between diabetes mellitus and cardiomyopathy. The diabetic hamsters, aged approximately 11 months, showed body weight loss, hyperglycemia (mean fasting plasma glucose 402 mg/dl), hypoinsulinemia, hyperlipidemia and ketonemia. The diabetic hamsters showed reduced activities of cytoplasmic glycolytic key enzymes; hexokinase, pyruvate kinase and phosphofructokinase, increases in cardiac glycogen and glucose-6-phosphate contents and a 40% decrease in cardiac ATP content, indicating decreased energy production. An accumulation of myocardial triglyceride and cholesterol was found in the diabetic hamsters. In addition, the cardiac norepinephrine content was increased in the diabetic hamsters, suggesting the presence of autonomic nervous disorder. Increased heart weight and thickening of the septum and both ventricular walls were found in the diabetic hamsters. Light-microscopic analysis revealed that 42.9% of the diabetic hamsters had myocardial degeneration without any vascular lesion of extramural large and intramural small vessels, whereas the non-diabetic controls had no myocardial or vascular lesions. These data suggest that the diabetic Chinese hamsters had cardiomyopathy, which is possibly caused by extravascular factors such as metabolic or autonomic nervous disorder although conclusive evidence is lacking.

Urinary bladder dysfunction in spontaneously diabetic Chinese hamsters

Urinary bladder dysfunction was investigated in spontaneously diabetic Chinese hamsters of the Asahikawa colony (CHAD). The wet weight of the urinary bladder was significantly increased in CHAD when compared with non-diabetic controls. In response to continuous infusion of physiological saline into the bladder under anesthesia, regular micturition was observed in controls. However, the threshold volume (i.e. the minimum volume at which rhythmic contraction appeared) was significantly increased and the amplitude of bladder contractions during micturition was decreased in CHAD aged 3-5 months (duration of diabetes, 0.6-2.2 months), leading to incomplete micturition. The frequency of micturition was also increased. Overflow incontinence was observed in all CHAD aged 13-15 months (duration of diabetes, 10-14 months). Acetylcholinesterase staining and activity in the urinary bladder walls were both significantly decreased in CHAD compared with controls. The in vitro increment of urinary bladder pressure caused by stimulation with bethanechol was not different between CHAD and controls. These findings suggest that CHAD have urinary bladder dysfunction which is caused by autonomic neuropathy and not by detrusor myopathy.

Insulin and glucagon response of the diabetic Chinese hamster in the Asahikawa colony

The relationship between pancreatic hormone content and pattern of hormone release has not been completely elucidated because of heterogeneity in diabetes. Accordingly, this study was performed to establish the relationship, using spontaneously diabetic Chinese hamsters in the Asahikawa colony, a newly discovered experimental model resembling insulin-deficient diabetes in humans. As a result of investigations of insulin and glucagon responses to glucose or arginine in vivo and in vitro using isolated islets obtained by the collagenase procedure, a decreased insulin response and paradoxical glucagon response to glucose, and an excessive glucagon response to arginine were found in the diabetic animals. While the yield of isolated islets tended to decrease, a decreased pancreatic insulin content and increased pancreatic glucagon content were found as the diabetic state advanced. It may be suggested, therefore, that the relationship between pancreatic hormone content and pattern of hormone release in diabetic animals in the Asahikawa colony is based on the disruption of islets, disruption or dysfunction of B-cells and hyperplasia or hypertrophy of A-cells by some cause genetically determined.

Rapid gastric emptying and pathological changes of vagus nerve in the spontaneously diabetic Chinese hamster

To estimate autonomic neuropathy in the spontaneously diabetic Chinese hamster, which is an established strain for the non-obese non-insulin-dependent diabetes mellitus model, gastric emptying and morphometric analysis of the vagus nerve were studied in 12-month-old spontaneously diabetic Chinese hamsters (duration of diabetes was 9 months). Gastric emptying was determined by the phenol red method. Vagus was obtained from just above the diaphragm. Morphometric analysis of myelinated fibers was performed light-microscopically using semi-thin sections and unmyelinated fibers were studied electron-microscopically using ultra-thin sections. Gastric emptying of spontaneously diabetic Chinese hamster was significantly increased compared with control (86.6 +/- 1.9 vs. 51.2 +/- 3.4, P < 0.01). Myelinated fibers of the spontaneously diabetic Chinese hamster were not different from control animals, while the size of unmyelinated fibers in the spontaneously diabetic Chinese hamster was significantly decreased. These data suggest that pathological changes in unmyelinated fibers, which consist mainly of afferent fibers, might play a role in gastric motor dysfunction in the spontaneously diabetic Chinese hamster.

Gastric Neuropeptides and Gastric Motor Abnormality in Streptozotocin-Induced Diabetic Rats

Alterations of gastric calcitonin gene-related peptide and substance P content and gastric emptying in early stages of streptozotocin-induced diabetic rats were investigated. Diabetes was induced by intravenous injection of streptozotocin (50 mg/kg) in male Wistar rats. Gastric emptying of phenol red solution and calcitonin gene-related peptide and substance P content of gastric walls, measured by radioimmunoassay, was assessed two and four weeks after streptozotocin injection. Gastric emptying two weeks after streptozotocin was delayed (32 ± 9%) and that four weeks after was enhanced (73 ± 2%) compared with nondiabetic control rats (50 ± 3%). Calcitonin gene-related peptide content of the gastric antrum and corpus was increased two weeks after and decreased four weeks after streptozotocin, while gastric substance P content was not changed at any time in diabetic rats. Insulin treatment reversed alterations of gastric emptying and calcitonin gene-related peptide content. The delayed gastric emptying in two-week diabetic rats was reversed by CGRP antagonist and the enhanced gastric emptying in four-week diabetic rats was reversed by CGRP pretreatment. These results suggest a possible relationship between gastric calcitonin gene-related peptide and abnormal gastric motility in diabetic state.

Natural history of B-cell dysfunction in spontaneously diabetic Chinese hamsters

To elucidate the pathogenesis of diabetes in spontaneously diabetic Chinese hamsters (CHAD strain), a longitudinal study from just after weaning to overt diabetic state was performed. Fasting and non-fasting plasma glucose, non-fasting plasma insulin and pancreatic hormone contents (insulin, glucagon and amylin) were measured, and light microscopic examination of pancreatic islets by immunohistochemical technique and pancreas perfusion study were performed. No insulitis was found in the islets of the CHAD strain. In animals aged 1 month, there was no significant difference in the percentage of B-cell area to islet area between the CHAD strain and the control. At this stage, hyperinsulinemia was observed despite normal plasma glucose levels both in fasting and non-fasting states. In the animals of the CHAD strain aged 2-4 months, insulin secretion from the pancreas, pancreatic insulin content and non-fasting plasma insulin level decreased in proportion to the decrease of B-cell mass. In animals aged about ten months, severe hyperglycemia and hypoinsulinemia were observed. We demonstrated the existence of amylin-like immunoreactivity in the B-cells of Chinese hamsters. However, no amyloid deposit was observed in the islets of the CHAD strain. After the onset of diabetes, amylin secretion from the pancreas and pancreatic amylin content in the CHAD strain were significantly lower than those in the control. We demonstrated the natural history of B-cell dysfunction in the CHAD strain. It could mean the process of B-cell exhaustion. The profile of the CHAD strain is similar to some types of human NIDDM. Therefore, the CHAD strain is a useful diabetic model in the study of NIDDM.