Biomedical subjects
K Nanjo
Publications and source records attributed to K Nanjo.
[Proinsulin converting enzyme (PC2, PC3) gene].
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[First case of Japanese spotted fever in Wakayama prefecture in Japan].
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Beta-thalassemia (beta 90 GAG-->TAG): genetic diagnosis by allele-specific polymerase chain reaction and estimation of mutant mRNA expression by reverse transcription polymerase chain reaction.
Genetic diagnosis of a family of beta-thalassemia (beta 90 GAG-->TAG) was carried out by allele-specific polymerase chain reaction (AS-PCR). The proband, her daughter and granddaughter were proved to be heterozygotes of normal and mutant alleles. As some nonsense mutations express a decreased amount of MrNAs, we determined the expression level of the mutant mRNA of beta-thalassemia (beta 90 GAG-->TAG), by application of a combination method of reverse transcription PCR (RT-PCR) and dot-blot hybridization with allele-specific oligonucleotides. The mutant mRNA was not markedly reduced. In conclusion, 1) individuals with the mutant beta-globin gene were diagnosed successfully by AS-PCR, and 2) a significant amount of the mutant beta-globin mRNA was synthesized.
Human prohormone convertase 3 gene: exon-intron organization and molecular scanning for mutations in Japanese subjects with NIDDM.
Proinsulin is converted to insulin by the concerted action of two sequence-specific subtilisin-like proteases termed prohormone convertase 2 (PC2) and prohormone convertase 3 (PC3). PC3 is a type I proinsulin-processing enzyme that initiates the sequential processing of proinsulin to insulin by cleaving the proinsulin molecule on the COOH-terminal side of the dibasic peptide, Arg31-Arg32, joining the B-chain and C-peptide. Thus, PC3 plays a key role in regulating insulin biosynthesis. Expressions of insulin and PC3, but not PC2, are coordinately regulated by glucose, consistent with the important role of PC3 in regulating proinsulin processing. NIDDM is associated with increased secretion of proinsulin and proinsulin-like molecules, suggesting that mutations in the PC3 gene may be involved in the development of this disorder. To examine this hypothesis, we have isolated and characterized the human PC3 gene and screened it for mutations in a group of Japanese subjects with NIDDM. The PC3 gene consists of 14 exons spanning more than 35 kb. The exon-intron organization of PC2 and PC3 genes are conserved, consistent with a common evolutionary origin for the prohormone convertase gene family. Single-strand conformational analysis and nucleotide sequencing of the entire coding region of the PC3 gene in 102 Japanese subjects with NIDDM revealed missense mutations in exons 2 (Arg/Gln53) and 14 (Gln/Glu638), neither of which was associated with NIDDM in this population. These data suggest that genetic variation in the PC3 gene is unlikely to be a major contributor to NIDDM susceptibility in Japanese.
Missense mutation of amylin gene (S20G) in Japanese NIDDM patients.
Many studies suggest that amylin, which is cosecreted with insulin from islet beta-cells, is a biologically active peptide and modulates plasma glucose levels. We therefore scanned the amylin gene for mutations in 294 Japanese NIDDM patients by single-strand conformational polymorphism, and we found a single heterozygous missense mutation (Ser-->Gly at position 20: S20G mutation) in 12 NIDDM patients (frequency 4.1%). None of the 187 nondiabetic subjects or 59 IDDM patients had the mutation. Of 12 patients carrying the mutation, 8 were diagnosed as having NIDDM at a relatively early age (< or = 35 years), and they had severe diabetes and strong family histories of late-onset NIDDM. On the other hand, the remaining four patients were diagnosed as having NIDDM after age 51, and they had mild diabetes without family histories of diabetes. In high-performance liquid chromatography analysis, a small amount (16%) of amylin immunoreactivity appeared in the position corresponding to normal amylin and a much larger amount (84%) appeared in the position corresponding to mutant amylin. These findings suggest that the S20G mutation of the amylin gene may play a partial role in the pathogenesis of early-onset NIDDM in the Japanese population and may also provide an important model to investigate the true physiological action of amylin.
Effects of cilostazol on development of experimental diabetic neuropathy: functional and structural studies, and Na+ -K+ -ATPase acidity in peripheral nerve in rats with streptozotocin-induced diabetes.
We studied the ability of cilostazol (CL), an antithrombotic and vasodilating agent, to prevent functional, structural and biochemical abnormalities including delayed motor nerve conduction velocity (MNCV), morphological changes in myelinated fibers, and decreased Na(+)-K(+) -ATPase activity in the peripheral nerves of rats with streptozotocin (STZ)-induced diabetes. Cilostazol treatment (30 mg/kg/day p.o.) for 10 weeks significantly prevented the delay in MNCV in the tail nerve, and morphometric analysis of the sural nerves revealed that this dose of cilostazol had a significant effect on reduction of average size of myelinated fibers. In untreated diabetic rats, cyclic AMP content and Na(+)-K(+)-ATPase activity of peripheral nerve were each significantly less than in normal control rats. Cilostazol (30 mg/kg/day) prevented reduction of Na(+)-K(+)-ATPase activity. Decrease in cyclic AMP content was completely prevented with both doses of cilostazol (30 and 10 mg/kg/day). These findings suggest that cilostazol may have beneficial effects in the treatment of diabetic neuropathy, possibly via improvement of nerve Na(+)-K(+) -ATPase activity and cyclic AMP content. Cilostazol may thus be a potent drug for the clinical treatment of diabetic neuropathy.
Association of the prohormone convertase 2 gene (PCSK2) on chromosome 20 with NIDDM in Japanese subjects.
Proinsulin is converted to insulin by the concerted action of two sequence-specific subtilisin-like proteases termed prohormone convertase 2 (PC2) and prohormone convertase 3. PC2 is a type II proinsulin-processing enzyme, and it cleaves the proinsulin molecule on the COOH-terminal side of dibasic peptide, Lys64-Arg65, which joins the C-peptide and the A-chain domains. We have previously cloned and characterized the exon-intron organization of the human PC2 gene (gene symbol PCSK2), localized this gene to human chromosome 20 band p11.2 by fluorescence in situ hybridization, and identified a simple tandem-repeat DNA polymorphism (STRP) in intron 2 of the form (CA)n, suitable for genetic studies. Since non-insulin-dependent diabetes mellitus (NIDDM) is associated with increased secretion of proinsulin and proinsulin-like molecules, we conducted a case-control study to determine whether a genetic variation in PCSK2 might contribute to the development of NIDDM. The study population consisted of 152 Japanese NIDDM subjects and 102 normal healthy nondiabetic control subjects matched for age and body mass index. The subjects were genotyped at the STRP in intron 2, and the results indicated a significant difference (P = 0.004) in the overall allele frequency distribution between the two groups. The A1 allele was found more frequently in NIDDM than in nondiabetic subjects (11 vs. 4%, P = 0.0068). The NIDDM patients were divided into two subgroups according to the presence or absence of the A1 allele.(ABSTRACT TRUNCATED AT 250 WORDS)
[A case of mesenteric leiomyosarcoma with giant abscess].
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Simple tandem repeat DNA polymorphism in the human glycogen synthase gene is associated with NIDDM in Japanese subjects.
We investigated the possible association between alleles of a simple tandem repeat DNA polymorphism in the human glycogen synthase gene and non-obese non-insulin-dependent diabetes (NIDDM) in Japanese subjects. Nine alleles (-4G, -3G, -2G, -1G, 0G, 1G, 2G, 3G, and 4G) were identified in the study group of 164 patients with NIDDM and 115 non-diabetic subjects. The overall frequency distribution of the glycogen synthase gene alleles was significantly different between the two groups (p = 0.0316). The 2G allele was found more frequently in patients with NIDDM than in non-diabetic subjects (17.7% vs 8.7%, p = 0.0016). These results suggest that the 2G allele could be a genetic marker of NIDDM in Japanese subjects.
Nicardipine may impair glucose metabolism in hypertensive diabetic patients.
The respective effects of 6 month's administration of beta-blockers (atenolol, metoprolol, carteolol and arotinolol), calcium-channel blockers (nicardipine, diltiazem) and angiotensin converting enzyme inhibitor (enalapril) on hemoglobin A1c (HbA1c) levels were evaluated in hypertensive patients with non-insulin-dependent diabetes mellitus (NIDDM), using a retrospective method. NIDDM patients with stable HbA1c and body weight were selected for this study. The following results were obtained. (1) The administration of nicardipine or beta-blockers significantly elevated HbA1c levels. (2) The administration of diltiazem or enalapril did not have any influence on HbA1c levels. These findings suggest that not only beta-blocker but nicardipine (dihydropyridine type calcium-channel blocker) may cause deterioration in glucose metabolism in NIDDM patients.
Abnormal insulinemia.
The recent development of molecular biology enables us to identify three abnormal insulins (insulin Chicago, insulin Los Angeles and insulin Wakayama). In Japan, three pedigrees in which affected individuals secrete [LeuA3] insulin (insulin Wakayama) have been identified. In each family, hyperinsulinemia associated with an abnormally elevated insulin to C-peptide molar ratio was demonstrated to occur in an autosomal dominant pattern of inheritance. In accordance with in vivo observations, semisynthetic [LeuA3] insulin demonstrated reduced in vitro receptor binding and biological activity relative to the human standard. The development of diabetes mellitus in affected family members was not uniform, was influenced by aging, and was different among families. Patients with impaired glucose tolerance demonstrated reduced insulin secretory reserve. Some of these features are thought to resemble the nature of non-insulin dependent diabetes mellitus (NIDDM). Therefore, insulin Wakayama may be a useful model for the study of the development of NIDDM.
[The molecular mechanism of insulin biosynthesis and mutant insulin gene syndrome].
The biosynthetic process of insulin in pancreatic beta cells consists of many steps including transcription of insulin gene to mRNA, translation of mRNA to preproinsulin, production of proinsulin by cleavage of signal peptide, and conversion of proinsulin to insulin and C-peptide. This process also includes intra-cellular trafficking (nucleus, cytoplasm, endoplasmic reticulum, Golgi apparatus, secretary granule, and extra-cellular secretion). The factors concerning and regulating these steps are discussed, although some of these have not been fully understood. The possible influences of insulin gene mutations (mutant insulin gene syndrome) to these steps are also discussed. Understanding of the molecular mechanism of insulin biosynthesis might be usefull to explain the defective insulin production of NIDDM.
[Analysis of the gene encoding human PC2, a prohormone processing enzyme].
Prohormone Convertase 2 (PC2) is a specific endoprotease responsible for the processing of proinsulin to insulin. PC2 is expressed in pancreatic islets, pituitary and brain but is very low or absent in most other tissues, such as liver, spleen and kidney. To evaluate the regulated expression of the human PC2 gene we have analyzed its structure and characterized its promoter. The gene spans > 130 kilobase pairs and consists of 12 exons. Comparison with the structure of the gene encoding human furin, revealed a high degree of conservation of exon-intron junctions. The hPC2 gene was localized to chromosome 20, band p11.2. The promoter region of the PC2 gene is very G + C rich and contains six potential Sp1 binding sites but no TATA or CAAT box. Analysis of the level of chrolamphenicol acetyltransferase activity with several deletion mutants identified the region from -1100 to -539 from the translation start site as essential for the PC2 promoter activity.
[Review for clinical molecular genetics of mutant insulin].
Three types of structurally abnormal insulin "Insulin Chicago, Los Angeles and Wakayama" has been identified in 6 families by the recent development of molecular biology. It has been clarified that a point mutation in the coding region of each patient's insulin gene allele give rise to a substitution of one amino acid of each insulin, resulting in reduced biological activities of these insulins. These abnormal insulin have slow metabolic clearance rate which cause typical hyperinsulinemia accompanying normal level of plasma C-peptide. In this paper, we review insulin gene mutations and discuss its participation to the pathogenesis of NIDDM.
[Glycogen synthase gene-glycogen synthase gene in Japanese patients with NIDDM].
As glycogen synthase is a key enzyme of the non-oxidative pathway of glucose metabolism in the skeletal muscle, and reduced activity of this enzyme is related to insulin resistance, it seems likely that this enzyme is a candidate gene for contributing to the pathogenesis of NIDDM. In this paper, we review recent findings of polymorphism of the human glycogen synthase gene, XbaI restriction enzyme length polymorphism and simple tandem repeat DNA polymorphism, and discuss the possible association between the glycogen synthase gene and NIDDM.
[Role of IAPP in the pathogenesis and development of NIDDM].
Islet amyloid deposits are the characteristic lesions of the pancreas of the patients with non-insulin-dependent diabetes mellitus (NIDDM). Islet amyloid polypeptide (IAPP or amylin) is a 37 amino acid peptide, which was extracted and characterized from islet amyloid deposits in patients with NIDDM. Recent studies and characterization of IAPP cDNA suggest that IAPP is a normal islet hormone and is co-secreted with insulin from islet beta cells of the pancreas. In this paper, we review recent advance of the research for IAPP including our results, and discuss the role of IAPP in the development of NIDDM, and we propose a new type of diabetes, "amyloid diabetes".
Familial hyperproinsulinemia associated with NIDDM. A case study.
OBJECTIVE: To report studies on an elderly patient with moderate NIDDM associated with marked fasting hyperinsulinemia. RESEARCH DESIGN AND METHODS: The propositus and several family members were studied by a combination of clinical, biochemical, and molecular genetic approaches to define the underlying genetic defect. RESULTS: Fasting levels of contrainsulin hormones were normal, and resistance to exogenous insulin was absent. Gel filtration and reverse-phase high-performance liquid chromatography revealed elevated amounts of a structurally abnormal proinsulin intermediate (AC proinsulin). A study of the family of the propositus showed the same abnormality in 4 of 5 members in 3 successive generations. Genetic analysis revealed a point mutation affecting residue 65 of human proinsulin (Arg-->His) in one allele of the insulin gene in the propositus, a defect similar to that described previously in 3 other apparently unrelated lineages. CONCLUSIONS: This family exhibits a clear-cut relationship between increasing age and metabolic decompensation in all the hyperproinsulinemic members, suggesting that (inherited) metabolic stress and age both contribute to development of diabetes mellitus.