Shoji Tsutaya

Positive association of endothelial nitric oxide synthase gene polymorphism with hypertension in Northern Japan

Vascular endothelial cells produce nitric oxide (NO), which contributes to the regulation of blood pressure and regional blood flow. Although Endothelial NO synthase (eNOS) gene polymorphisms have been shown to have a positive association with coronary artery disease, the linkage between eNOS gene polymorphisms and hypertension has been controversial. In the present study, therefore, we identified genotypes for Glu298Asp and variable number tandem repeats in intron 4 (4b/a) in 183 hypertensive and 193 normotensive populations. The Glu298Asp variant had a significant association with hypertension (odds ratio, 1.8; 95% confidence interval, 1.1-3.0). The allele frequencies of 298Asp for Glu298 in hypertensive patients were significantly higher than those in normotensive subjects (0.128 vs 0.080, p<0.05). Diastolic and mean arterial blood pressures were significantly higher in hypertensive subjects with the 298Asp allele than those without the variant allele (p<0.05). However, disequilibrium of 4b/a polymorphism was absent between these two groups. These results suggest that the Glu298Asp variant may be a genetic susceptibility factor for hypertension.

A case of multiple endocrine neoplasia type II accompanied by thyroid medullary carcinoma and pheochromocytomas expressing corticotropin-releasing factor and urocortins.

A 38-year-old woman with RET gene mutation presented with tumors in her thyroid and bilateral adrenal glands. I-metaiodobenzylguanidine scintigraphy revealed accumulation of the radioisotope in both adrenal glands. Both plasma adrenaline and noradrenaline levels were elevated. The circadian rhythms for plasma adrenocorticotropic hormone (ACTH) and cortisol levels were disturbed. Plasma ACTH and cortisol levels failed to be suppressed by an overnight dexamethasone test, suggesting autonomic secretion of ACTH and cortisol, although the patient had no typical Cushingoid features, hypertension, or impaired glucose tolerance. Pathological examination showed that these tumors were pheochromocytoma and thyroid medullary carcinoma, respectively, both of which highly expressed corticotropin-releasing factor, urocortin1, and urocortin3. Together with the endocrinological and pathological observations, the patient was diagnosed as multiple endocrine neoplasia type II with corticotropin-releasing factor- and urocortin-producing tumors that stimulated ACTH and glucocorticoid secretion.

Association of novel promoter single nucleotide polymorphisms in vasopressin V1a receptor gene with essential hypertension in nonobese Japanese.

We studied the association between four novel single nucleotide polymorphisms (SNPs) in the promoter region of V1aR gene and essential hypertension in 620 Japanese subjects (365 hypertensives and 255 healthy). A significant association was found between one of the genotypes and alleles at SNP -6951 and hypertension in a subsample of nonobese individuals. This association demonstrated an independent risk for nonobese hypertension.

A novel mutation of the thiazide-sensitive sodium chloride cotransporter gene in a Japanese family with Gitelman syndrome

Gitelman syndrome is an inherited renal disorder characterized by impaired NaCl reabsorption in the distal convoluted tubule leading to hypokalemia, hypomagnesemia and normocalcemic hypocalciuria. It has been shown that this syndrome results from mutations in the gene encoding the thiazide-sensitive sodium chloride cotransporter (TSC). We performed the mutational analysis in the TSC gene of a 30-year-old Japanese woman with Gitelman syndrome and found two mutations at adjacent spots in both alleles. One was a frame shift mutation which generated stop codon at position 671, the other was a single nucleotide mutation, which resulted in an aminoacid substitution at position 672, Met to Ile. Her 52-year-old mother and two daughters had neither hypokalemia nor hypomagnesemia. However, her mother and her 8-year-old daughter had the Met672Ile mutation as heterozygotes. Her 4-year-old daughter had the same frame shift mutation as her mother, a heterozygotic mutation. These results suggest that Gitelman syndrome requires 2 compound heterozygotic mutations and the coexistence of the large deletion in the C-terminal domain with Met672Ile substitution of the TSC could impair the transporter activity underling the hypokalemia and hypomagnesemia in this patient.

A case of thyrotropin-producing pituitary adenoma, accompanied by an increase in anti-thyrotropin receptor antibody after tumor resection

We describe a rare, but interesting, case of TSH-producing adenoma (TSHoma), accompanied by increases in both anti-TSH receptor antibody (TRAb) and thyroid-stimulating antibody (TSAb) after tumor resection. A 21-yr-old woman was referred to our department for further evaluation of pituitary tumor. In a nearby hospital, she had been diagnosed as having pituitary tumor. Her serum free T4, free T3, and TSH levels were all elevated concomitantly. On the basis of a diagnosis of pituitary adenoma with TSH production, transsphenoidal resection of the pituitary adenoma was performed. Two weeks after the operation, the blood concentrations of TSH were undetectable, whereas both TRAb and TSAb levels were elevated. TSAb levels gradually increased further from 2 weeks to 3 months after the operation, accompanied by an increase in TSH and free T4 levels. TSH is an important hormone in maintaining physiology and regulating immunomodulators in thyrocytes, as it can influence a variety of immune-regulating cytokine-like activities and inhibit expressions of Fas antigen, intracellular adhesion molecule-1, and class II trans-activator. Changes in TSH would modulate the immune circumstances in the thyroid, and then induce TRAb and TSAb. Autoimmune parameters with thyroid function should be observed carefully when managing patients with TSHoma.

Possible involvement of reusable towels in the high rate of Bacillus species-positive blood cultures in Japanese hospitals.

BACKGROUND A number of outbreaks caused by Bacillus species have been reported to date. Outbreaks reported in the last decade have predominantly arisen in Japanese hospitals. AIM To elucidate factors contributing to these real or pseudo outbreaks by Bacillus species, and to evaluate the rate of Bacillus species-positive blood culture samples in Japan. METHODS A systematic review of the literature was performed. Reports including data on outbreaks caused by Bacillus species were searched for in PubMed, Google Scholar and Evidence-based Medicine BMJ from inception through 10 Aug 2014. Japanese nationwide data on bacteriological tests were collected from Japan Nosocomial Infections Surveillance. Regional bacteriological data for Akita prefecture were collected using the Akita Regional Network for Infection Monitoring/Control System. FINDINGS Contamination of reusable towels was suspected as a cause for the high rate of Bacillus-positive blood cultures in Japan. The rate of Bacillus species in blood cultures was much higher in Japan than in reports from other countries. CONCLUSIONS The high contamination rate of blood culture samples by Bacillus species in Japan is a matter of concern for infection control and medical treatment. Bacteriological investigation of reusable towels should be considered in hospitals with a high frequency of Bacillus-positive blood cultures.

Gene analysis of the calcium channel 1 subunit and clinical studies for two patients with hypokalemic periodic paralysis

Hypokalemic periodic paralysis (HypoPP) is a skeletal muscle disorder in which episodic attacks of muscle weakness occur; they are associated with decreased serum potassium (K+) levels. Recent molecular approaches have clarified that the condition is caused by mutations in the skeletal muscle voltage-gated calcium channel 1 subunit (CACNA1S). We describe two unrelated patients with HypoPP, followed by their relevant clinical studies and gene analysis. Clinical studies included an oral glucose tolerance test (OGTT), food-loading and insulin tolerance tests (ITT). For Case 1, serum K+ levels were extremely decreased following insulin tolerance testing compared with levels for controls. These results support the hypothesis that no efflux of K+ ion occurs in patients because of low activity of adenosine triphosphate (ATP)-sensitive K+ channel (KATP) channels. Mutational analysis of the CACNA1S gene showed a duplicate insertion of 14 base pairs (bp) from 52 to 65 in intron 26, present in the heterozygous state in both patients. No other mutations were detected in the CACNA1S gene, the muscle sodium channel gene (SCN4A) or the voltage-gated K+ channel gene (KCN3) of either patient. Further analysis showed that this duplicate insertion of 14 bp in intron 26 of the CACNA1S gene was found in 23.7% of healthy subjects. K+ dynamics studies are useful for confirming this syndrome, while further gene analysis for various ion channels using amplification and direct sequencing are required to evaluate the molecular basis of the disorder in the individual patient.

Diagnosis of a case of Gitelman’s syndrome based on renal clearance studies and gene analysis of a novel mutation of the thiazide-sensitive Na-Cl cotransporter

Gitelman’s syndrome is a recessively inherited renal tubular disorder characterized by low plasma potassium and magnesium levels, reduced calcium excretion, metabolic alkalosis, and increased plasma renin activity and plasma aldosterone concentration with normal blood pressure levels. A 23-yr-old man was referred to our department for further evaluation of hypokalemia. The patient also had hypomagnesemia and markedly reduced urinary calcium excretion. Renal clearance studies and gene analysis of the thiazide-sensitive Na-Cl cotransporter (TSC) were performed in the patient. In response to an iv injection of furosemide, chloride clearance (CCl) increased markedly, while distal fractional chloride reabsorption CH2O/ (CH2O+CCl) was considerably reduced. In contrast, thiazide ingestion had no significant effects on these parameters. The patient had compound heterozygous mutations in the alleles encoding the TSC gene, one of which has not been formerly reported. Renal clearance studies and TSC gene analysis by amplification and direct sequencing are useful diagnostic tools for confirming a diagnosis of Gitelman’s syndrome.

Lack of association of 4G/5G polymorphism in plasminogen activator inhibitor-1 gene with stroke

Abstract Disturbances in fibrinolytic activity have been linked with an increased risk for stroke. The insertion/deletion (4G/5G) variation in the plasminogen activator inhibitor-1 (PAI-1) gene promotor has been raised as a risk for cerebrovascular diseases because of its association with the transcription and the increased plasma PAI-1 levels. However, the association between the 4G/5G polymorphism and stroke has been controversial. Therefore, we evaluated the prevalence of PAI-1 genotype in 72 cerebral infarction, 60 cerebral hemorrhage and 94 healthy subjects in northern Japan. The specific genotypes for the 4G/5G polymorphism were isolated using restriction fragment length polymorphism. The distribution of 4G/5G genotypes in the healthy control group was 40.4% for 4G/4G, 45.8% for 4G/5G and 13.8% for 5G/5G, respectively. We found no association in the 4G/5G polymorphism of the PAI-1 gene with cerebral infarction or cerebral hemorrhage. Our results suggest that the PAI-1 4G/5G gene polymorphism may not be a genetic risk factor for stroke in northern Japan.

The role of protein kinases in glycoprotein GMP-140 expression on activated human platelets

Abstract The expression of glycoprotein GMP-140 (P-selectin, CD-62P) is stimulated in human platelets by vasopressin via G protein-coupled receptors. In order to clarify the subsequent intracellular signal pathway, we examined the role of protein kinases in vasopressin action on thrombocytic CD62P expression in normal subjects. Staurosporine, a protein kinase (PK) C inhibitor, inhibited platelet aggregation and CD62P expression, whereas phorbol ester (PMA), a PKC stimulator, provoked them. On the other hand, 8-bromo-adenosine-3′,5′-monophosphate-cyclic AMP (8-Br-cAMP), a membrane permeant cAMP analogue, had no effect on platelet activation. PMI, a PKA inhibitor, had a little effect on them. From these results, it is suggested that PKC plays a dominant role in AVP action on platelet aggregation and CD62P expression.