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Biomedical subjects

H Kishikawa

Publications and source records attributed to H Kishikawa.

At least 55 records · Page 3Linked to original sources
PubMed1998

Suppressive effect of simvastatin on intramural small coronary arterial lesions in cholesterol-fed rabbits.

The aim of this study was to examine the suppressive effect of simvastatin on intramural coronary arterial lesions in cholesterol-fed rabbits. In one experiment, six groups of rabbits were fed laboratory chow alone or with added 0.1%, 0.2%, 0.3%, 0.5% or 1.0% cholesterol for 16 weeks. In another experiment, four groups of rabbits were fed a 0.5% cholesterol diet and treated with simvastatin at 1, 3, or 5 mg/kg/day or placebo. In each rabbit, the levels of serum total cholesterol (TC) were determined at 1-week intervals to calculate the integrated values. The lesion induction ratio was defined as the ratio of intramural coronary arteries 50-150 microm in diameter with arterial lipoidosis to the total number of arteries of the same diameter. In the two experiments, there were positive correlations between the lesion induction ratio and integrated TC (r=0.785, P<0.0001 and r=0.763, P<0.0001, respectively). The slopes of the regression lines for integrated TC obtained in the two experiments were similar, but the lesion induction ratio in the simvastatin-treated group was always lower, by about 14%, in comparison with that in the non-simvastatin-treated group. These findings suggest that simvastatin induces lesion reduction not only by reducing the levels of circulating cholesterol but also by directly suppressing the development of lipoidosis.

Animals↗
PubMed1998

Bradykinin potentiates insulin-stimulated glucose uptake and enhances insulin signal through the bradykinin B2 receptor in dog skeletal muscle and rat L6 myoblasts.

Previously we demonstrated that bradykinin infusion could increase glucose uptake into dog peripheral tissues, and that bradykinin could potentiate insulin-induced glucose uptake through glucose transporter 4 (GLUT4) translocation in dog adipocytes. However, skeletal muscle is the predominant tissue for insulin-mediated glucose disposal. The aim of this study was to determine how bradykinin affected insulin-stimulated glucose uptake in dog skeletal muscle and myotubes transformed from rat L6 myoblasts. The bradykinin receptor binding studies revealed that dog skeletal muscle and rat L6 myoblasts possessed significant numbers of bradykinin receptors (Kd = 88 and 76 pmol/l, Bmax = 82.5 and 20 fmol/mg protein respectively). An RT-PCR (reverse transcriptase-polymerase chain reaction) amplification showed mRNA specific for bradykinin B2 receptor in both cells. Bradykinin significantly increased 2-deoxyglucose uptake in isolated muscle and L6 myoblasts in the presence of insulin (10(-7) mol/l) in a dose-dependent manner, but not in the absence of insulin. Bradykinin also enhanced insulin-stimulated GLUT4 translocation, and insulin-induced phosphorylation of insulin receptor beta subunit and insulin receptor substrate-1 (IRS-1) without affecting the binding affinities or numbers of cell surface insulin receptors in both cells. It is concluded that bradykinin could potentiate the insulin-induced glucose uptake through GLUT4 translocation in dog skeletal muscle and rat L6 myoblasts. This effect could be explained by the potency of bradykinin to upregulate the insulin receptor tyrosine kinase activity which stimulates phosphorylation of IRS-1, followed by an increase in GLUT4 translocation.

Animals↗
PubMed1998

Creation and characterization of a mitochondrial DNA-depleted pancreatic beta-cell line: impaired insulin secretion induced by glucose, leucine, and sulfonylureas.

It has been proposed that mitochondrial oxidative phosphorylation in pancreatic beta-cells plays an important role in insulin secretion. To examine the impact of mitochondrial dysfunction on insulin secretion, we created a MIN6 cell line that depleted mitochondrial DNA (mtDNA) by treatment with ethidium bromide (EtBr), and studied the response of the cell line to various secretagogues. MIN6 cells cultured with 0.5 microg/ml EtBr for over 2 months (termed MIN6 deltamt cells) revealed a marked (>90%) decrease in mtDNA content and a lack of mRNAs encoded by mtDNA. MIN6 deltamt cells showed the defects of cytochrome c oxidase activity, glucose- and leucine-induced increase in cellular ATP content, and respiratory chain-driven ATP synthesis, suggesting that MIN6 deltamt cells lost oxidative phosphorylation activity due to the selective disruption of the subunits of respiratory chain enzymes encoded by mtDNA. MIN6 deltamt cells also showed a decrease in glucose utilization, suggesting the impairment of the glycolytic pathway as well. After stimulation with glucose and leucine, MIN6 deltamt cells showed no response in insulin secretion or intracellular free Ca2+ concentration ([Ca2+]i). On the other hand, arginine stimulated insulin secretion and an increase in [Ca2+]i in MIN6 deltamt cells as in MIN6 cells. Glibenclamide also stimulated insulin secretion and an increase in [Ca2+]i in both types of cells, but the responses of MIN6 deltamt cells were significantly lower than those of MIN6 cells. These results suggest the importance of ATP production in insulin secretion and an increase in [Ca2+]i, both induced by glucose and leucine. Moreover, mitochondrial function turns out to be not essential but important for the activation of sulfonylurea-induced insulin secretion.

Adenosine Triphosphate↗
PubMed1998

[Direct effects of Chinese herbal medicine "hochuekkito" on sperm movement].

BACKGROUND AND PURPOSE: Chinese herbal medicine, "Hochuekkito" is widely used for male infertility in Japan. There have been many reports concerning its clinical usefulness but very few reports of in vitro experiments studying the mechanism of its effects. In addition to stimulating germ cells, we analyzed its direct effects on sperm using computer assisted semen analyzer (CASA). MATERIALS AND METHODS: Motile sperm were prepared using swim up technique from semen collected from ten healthy volunteers. Sperm movements (motility, velocity, linearity) were analyzed by CASA after adding either serum containing anti-sperm antibody (ASA) or normal serum with or without Hochuekkito. RESULTS: Two hours after adding serum with ASA, the decrease of sperm motility was significantly reduced from 25.1% (92.8%-->67.7%) to 12.5% (92.9%-->80.6%) by adding Hochuekkito. No significant difference in velocity and linearity was observed between two groups. By adding normal serum, any of three parameters differed significantly with or without Hochuekkito. CONCLUSION: Protective effects of Hochuekkito on sperm was suggested. Although normal sperm with ASA was used in this report, since the sperm of infertile patients are said to be more fragile, this results imply that direct protective effect is one of the mechanism of Hochuekkito for male infertility.

Adult↗
PubMed1998

[A welder with chemical pneumonitis caused by inhalation of zinc fume].

A 61-year-old man with a 32-year occupational history of welding developed malaise, cough, and dyspnea after inhalation of smoke while welding galvanized steel. On admission, peripheral leukocytosis, hypoxemia, and diffuse granular and linear opacities on a chest X-ray were present. The bronchioli were exaggerated in a chest high-resolution CT. Bronchoalveolar lavage revealed mild lymphocytosis and transbronchial lung biopsy showed siderosis and exudation of fibrin and neutrophils into alveolar spaces. The clinical and radiographic findings later improved except for an obstructive disorder on pulmonary function test. The respiratory health hazards associated with welding vary according to the materials and the concentration of inhaled substances. Acute chemical pneumonitis caused by inhalation of zinc fumes (zinc oxide) was accompanied by chronic siderosis in this case. It is well known that metal fume fever commonly occurs when inhaling zinc oxide fumes. However acute chemical pneumonitis after exposure to zinc oxide during welding has been only rarely reported.

Aerosols↗
PubMed1998

[A case of familial myoclonus showing extremely benign clinical course].

We report a patient with familial myoclonus showing an extremely benign clinical course. The patient was a 70-year-old woman, who first noticed shaking of hands at age of 25. The symptom did not worsen for more than 40 years. She visited our hospital at the age of 70 because of disturbance in chores because of worsening of her hand shaking in the past one year. A family history showed that 4 members had similar symptoms and that the two were afflicted with fits of loss of consciousness. On neurologic examination, rhythmic myoclonic jerks were noted in all the extremities, more in the upper limbs, both at rest and during action. Tandem gait was mildly disturbed. The remainings of neurologic examination were normal. SEP and jerk-locked back averaging provided evidence of cortical myoclonus. EEG showed multifocal polyspike discharges. Gene analysis for DRPLA, pyruvate and lactate levels in serum and the cerebrospinal fluid, serum amino acid levels, and CSF HVA and 5-HIAA levels were all normal. No brain atrophy was noted in cranial MRI. Myoclonus was markedly reduced after administration of clonazepam. The clinical features and electrophysiological data of our patient are consistent with the clinical diagnosis of familial essential myoclonus and epilepsy/benign adult familial myoclonic epilepsy.

Aged↗
PubMed1997

Interleukin-12 promotes enhanced resistance to Listeria monocytogenes infection of lead-exposed mice.

The heavy metal lead (Pb) has been shown to downregulate various parameters of cell-mediated immune (CMI) responses. This inhibition of CMI responses by Pb is exemplified by a higher mortality rate upon infections with sublethal doses of a variety of pathogens. Unlike Pb, which lowers host resistance, interleukin-12 (IL-12) exerts a substantial stimulatory influence on the host response to intracellular bacteria such as Listeria monocytogenes. To explore the influence of IL-12 in mice rendered susceptible to Listerial infection by oral exposure to Pb, we determined bacterial burdens and production of interferon gamma (IFN-gamma). As expected, Pb-exposed mice had increased morbidity due to higher Listerial titers as compared to control mice. However, administration of exogenous IL-12 reversed the Pb-induced inhibition of host defense and boosted the resistance of the non-Pb-treated mice. The enhanced CMI responses observed in both IL-12-treated groups were accompanied with elevations of IFN-gamma in the sera and spleens. Significant reduction in the number of viable Listeria in Pb-exposed mice upon IL-12 administration suggests that the processes downstream of IL-12 production were intact in the Pb-exposed mice and that the inhibition by Pb was due to the lack of functional IL-12. Alternatively, the exogenous IL-12 may have overcome a downstream effect by enhancing an secondary pathway. Support for the former hypothesis is based on the observation that Pb induced elevated levels of p40 splenic messenger RNA since increased p40 expression would result from lack of IL-12 formation. Contrary to the IFN-gamma levels, significantly higher levels of IL-6 and corticosterone were observed in the sera and spleens of Pb-exposed mice upon infection, suggesting heightened stress in the absence of IL-12. Overall, the results suggest that an environmental pollutant such as Pb can enhance the stress response, which naturally occurs during an infection, and can further compromise health by lowering host resistance by altering cytokine levels.

Animals↗
PubMed1997

Successful treatment of intermittent claudication due to spinal canal stenosis using beraprost sodium, a stable prostaglandin I2 analogue. A case report.

The syndrome of intermittent claudication can be induced not only by vascular insufficiency of the lower limbs but also by diseases of the spinal cord and cauda equina. The authors describe a sixty-year-old man with intermittent claudication due to spinal canal stenosis who was successfully treated with beraprost sodium, a stable prostaglandin I2 analogue. This drug has a long biological half-life and is orally effective in vasodilation, which is suggested to be beneficial in treating this syndrome. Beraprost sodium may become one of the major drugs for conservative therapy of intermittent claudication induced by spinal canal stenosis.

Epoprostenol↗
PubMed1997

Cell-specific regulation of IRS-1 gene expression: role of E box and C/EBP binding site in HepG2 cells and CHO cells.

Insulin receptor substrate 1 (IRS-1) is one of the major substrates of insulin receptor tyrosine kinase and mediates multiple insulin signals downstream. We have previously shown that the levels of IRS-1 mRNA varied in different tissues. To elucidate the molecular mechanisms of the tissue specific regulation of IRS-1, we have studied the cis-acting elements and transacting factors in CHO and HepG2 cells. Using the chloramphenicol acetyltransferase (CAT) assay with the various deletion mutants of the IRS-1 promoter-CAT fusion plasmids, several regions responsible for positive or negative regulation in each cell line were identified. A region from -1645 to -1585 bp, which regulated expression negatively in CHO cells and positively in HepG2 cells, was further analyzed. Within this region a fragment from -1645 to -1605 bp upregulated the IRS-1 promoter only in HepG2 cells, whereas a fragment from -1605 to -1585 bp downregulated only in CHO cells. In the gel mobility shift assay, several nuclear proteins that bind to these fragments were detected, and among them, two nuclear proteins that bind to a potential E box (nucleotide [nt] -1635 to -1630) and two nuclear proteins that bind to a potential C/EBP binding site (nt -1599 to -1591) were identified in HepG2 and CHO cells, respectively. CAT assays using promoters mutated at the E box or at the C/EBP binding site revealed that these sequences were responsible for cell-specific regulation of the IRS-1 gene. We therefore concluded that the two nuclear proteins that bind to the E box regulate IRS-1 gene expression positively in HepG2 cells and the two nuclear proteins that bind to the C/EBP binding site regulate it negatively in CHO cells.

Animals↗
PubMed1997

Impact of natural IRS-1 mutations on insulin signals: mutations of IRS-1 in the PTB domain and near SH2 protein binding sites result in impaired function at different steps of IRS-1 signaling.

Insulin receptor substrate-1 (IRS-1) is one of the major substrates of insulin receptor tyrosine kinase and mediates various insulin signals downstream. In this study, we have examined the impact of three natural IRS-1 mutations identified in NIDDM patients (G971R, P170R, and M209T) on insulin signaling. G971R is located near src homology 2 protein binding sites, and P170R and M209T are located in the phosphotyrosine binding domain of IRS-1. 32D-IR cells, stably overexpressing human insulin receptor, were transfected with wild-type human IRS-1 cDNA (WT) or three mutant IRS-1 cDNAs and analyzed. All the cell lines expressing mutant IRS-1 showed a significant reduction in [3H]thymidine incorporation compared with WT. Upon insulin stimulation, cells expressing G971R showed a 39% decrease (P < 0.005) in phosphatidylinositol 3-kinase (PI 3-kinase) activity, a 43% decrease (P < 0.01) in binding of the 85-kDa regulatory subunit of PI 3-kinase, and a 22% decrease (P < 0.05) in mitogen-activated protein kinase activity compared with those expressing WT. Cells expressing P170R and M209T showed slight but significant decreases in PI 3-kinase activity (17 and 14%, respectively; both P < 0.05) and in binding of p85 (22 and 16%, respectively; both P < 0.05) and a greater decrease in mitogen-activated protein kinase activity (41 and 43%, respectively; both P < 0.005) compared with WT. After insulin stimulation, cells expressing P170R and M209T showed significant decreases in IRS-1 phosphorylation (37 and 42%, respectively; both P < 0.05) and in IRS-1 binding to the insulin receptor (48 and 53%, respectively; P < 0.01) compared with WT. G971R showed no changes in IRS-1 phosphorylation and in IRS-1 binding to the insulin receptor compared with WT. These data suggest that the impaired mitogenic response of P170R and M209T was mainly due to reduced binding to the insulin receptor, whereas the impaired response of G971R was mainly due to reduced association with PI 3-kinase p85.

Animals↗
PubMed1997

[Preoperative localization of enlarged parathyroid glands by 99mTc-MIBI scintigraphy].

BACKGROUND: Recent studies have shown that 99mTc-methoxy-isobutyl-isonitrile (99mTc-MIBI), a new agent for myocardial perfusion imaging, can be successfully applied to parathyroid imaging. We evaluated the efficacy of 99mTc-MIBI scintigraphy for preoperative localization of enlarged parathyroid glands in patients with hyperparathyroidism. PATIENTS AND METHODS: From June 1994 to September 1996, 24 patients with biochemical confirmation of hyperparathyroidism were studied with 99mTc-MIBI scintigraphy prior to operation. Eleven patients had primary hyperparathyroidism (PHPT) and 13 had secondary hyperparathyroidism (SHPT) associated with chronic renal failure, including one patient with recurrent disease after subtotal parathyroidectomy. A positive 99mTc-MIBI scan for an enlarged gland was defined as an area of persistent focal uptake on the delayed image acquired at 150 min after intravenous injection of 600 MBq of 99mTc-MIBI. RESULTS: Of 11 patients with PHPT, 10, were found to have solitary parathyroid adenomas at surgery and one patient had primary hyperplasia. 99mTc-MIBI scintigraphy accurately detected 9 of 10 adenomas and 2 of 3 hyperplastic glands with no false positive results. Both of the two glands that were not detected by 99mTc-MIBI weighed 200 mg. The mean weight of the 11 glands that were visualized was 1264 mg (range 300 approximately 4300 mg). The sensitivity and predictive value positive for PHPT were 84.6% and 100%, respectively. In 13 patients with SHPT, all of 49 parathyroid glands were identified during surgery, with 43 hyperplastic glands and 6 normal-size glands. Of 43 hyperplastic glands, 28 were detected by 99mTc-MIBI and there was significant difference between the mean weight of these 28 glands (999 mg, range 290 approximately 2630 mg) and that of the 15 nonimaged hyperplastic glands (283 mg, range 90 approximately 540 mg). None of the six normal glands were imaged with 99mTc-MIBI. One patient had a false positive scan caused by a thyroid nodule. The sensitivity and predictive value positive for SHPT were 65.1% and 96.6%, respectively. CONCLUSION: 99mTc-MIBI scintigraphy is an excellent imaging method for localization of enlarged parathyroid glands in patients with hyperparathyroidism, especially with PHPT. However, it has the difficulty to demonstrate enlarged glands smaller than 300 mg in weight.

Adult↗
PubMed1997

[Microscopic polyangiitis and pulmonary fibrosis in a patient who died of Candida pneumonia and intra-alveolar hemorrhage].

A 74-year-old man was admitted to our hospital because of edema of the lower legs, fever, and increasing fatigue. Laboratory evaluation revealed proteinuria, microhematuria, leukocytosis, thrombocytosis, anemia, a high level of C-reactive protein. A test for myeloperoxidase-antineutrophil cytoplasmic antibodies was highly positive. Microscopic polyarteritis nodosa was diagnosed and therapy with prednisolone was begun. Examination of a renal biopsy sample showed necrotizing crescentic glomerulonephritis. A chest roentgenogram and CT scan disclosed bilateral basilar interstitial changes. Six months later, the patient was admitted again because of disturbance of consciousness, malnutrition, and hyponatremia. After admission, alveolar infiltrates developed in the right lung and the patient died on the 5th hospital day as a result of respiratory failure. An autopsy revealed Candida pneumonia of the right lung and massive intra-alveolar hemorrhage, which was believed to have caused the respiratory failure. Other findings were usual interstitial pneumonia, cellular small-vessel angiitis in the lungs, and healed angiitis in the kidneys and liver. In this case of microscopic polyangiitis and chronic interstitial pneumonia, steroid therapy was effective against the angiitis, but the patient died of an opportunistic infection and alveolar hemorrhage.

Aged↗
PubMed1996

A carboxy-terminal truncation of human alpha-galactosidase A in a heterozygous female with Fabry disease and modification of the enzymatic activity by the carboxy-terminal domain. Increased, reduced, or absent enzyme activity depending on number of amino acid residues deleted.

Fabry disease is an X-linked disorder of glycosphingolipid metabolism caused by a deficiency of alpha-galactosidase A (alpha-Gal A). We identified a novel mutation of alpha-Gal A gene in a family with Fabry disease, which converted a tyrosine at codon 365 to a stop and resulted in a truncation of the carboxy (C) terminus by 65 amino acid (AA) residues. In a heterozygote of this family, although the mutant and normal alleles were equally transcribed in cultured fibroblasts, lymphocyte alpha-Gal A activity was approximately 30% of the normal control and severe clinical symptoms were apparent. COS-1 cells transfected with this mutant cDNA showed a complete loss of its enzymatic activity. Furthermore, those cotransfected with mutant and wildtype cDNAs showed a lower alpha-Gal A activity than those with wild type alone (approximately 30% of wild type alone), which suggested the dominant negative effect of this mutation and implied the importance of the C terminus for its activity. Thus, we generated mutant cDNAs with various deletion of the C terminus, and analyzed. Unexpectedly, alpha-Gal A activity was enhanced by up to sixfold compared with wild-type when from 2 to 10 AA residues were deleted. In contrast, deletion of 12 or more AA acid residues resulted in a complete loss of enzyme activity. Our data suggest that the C-terminal region of alpha-Gal A plays an important role in the regulation of its enzyme activity.

Amino Acid Sequence↗
PubMed1996

Bradykinin enhances GLUT4 translocation through the increase of insulin receptor tyrosine kinase in primary adipocytes: evidence that bradykinin stimulates the insulin signalling pathway.

It has been suggested that bradykinin stimulates glucose uptake in experiments in vivo and in cultured cells. However, its mechanism has not yet been fully elucidated. In this study, the effects of bradykinin on the insulin signalling pathway were evaluated in isolated dog adipocytes. The bradykinin receptor binding study revealed that dog adipocytes possessed significant numbers of bradykinin receptors (Kd = 83 pmol/l, binding sites = 1.7 x 10(4) site/ cell). Reverse transcription-polymerase chain reaction amplification showed the mRNA specific for bradykinin B2 receptor in the adipocytes. Bradykinin alone did not increase 2-deoxyglucose uptake in adipocytes; however, in the presence of insulin (10(-7) mol/l) it significantly increased 2-deoxyglucose uptake in a dose-dependent manner. Bradykinin also enhanced insulin stimulated GLUT4 translocation from the intracellular fraction to the cell membrane, and insulin induced phosphorylation of the insulin receptor beta subunit and insulin receptor substrate-1 (IRS-1) without affecting the binding affinities or numbers of cell surface insulin receptors in dog adipocytes. The time-course of insulin stimulated phosphorylation of the insulin receptor beta subunit revealed that phosphorylation reached significantly higher levels at 10 min, and stayed at the higher levels until 120 min in the presence of bradykinin, suggesting that bradykinin delayed the dephosphorylation of the insulin receptor. It is concluded that bradykinin could potentiate insulin induced glucose uptake through GLUT4 translocation. This effect could be explained by the potency of bradykinin to upregulate the insulin receptor tyrosine kinase activity which stimulates phosphorylation of IRS-1, followed by GLUT4 translocation.

Adipocytes↗
PubMed1996

Molecular scanning of the insulin receptor substrate-1 (IRS-1) gene in Japanese patients with NIDDM: identification of five novel polymorphisms.

Since the insulin receptor substrate-1 (IRS-1) is the major substrate of the insulin receptor tyrosine kinase and has been shown to activate phosphatidylinositol (PI) 3-kinase and promote GLUT4 translocation, the IRS-1 gene is a potential candidate for development of non-insulin-dependent diabetes mellitus (NIDDM). In this study, we have identified IRS-1 gene polymorphisms, evaluated their frequencies in Japanese subjects, and analysed the contribution of these polymorphisms to the development of NIDDM. The entire coding region of the IRS-1 gene of 94 subjects (47 NIDDM and 47 control subjects) was screened by polymerase chain reaction-single stranded conformation polymorphism (PCR-SSCP) analysis. Seven SSCP polymorphisms were identified. These corresponded to two previously identified polymorphisms [Gly971 --> Arg (GGG --> AGG) and Ala804 (GCA --> GCG)] as well as five novel polymorphisms [Pro190 --> Arg (CCC --> CGC), Met209 --> Thr (ATG --> ACG), Ser809 --> Phe (TCT --> TTT), Leu142 (CTT --> CTC), and Gly625 (GGC --> GGT)]. Although the prevalence of each of these polymorphisms was not statistically different between NIDDM and control subjects, the prevalence of the four IRS-1 polymorphisms with an amino acid substitution together was significantly higher in NIDDM than in control subjects (23.4 vs 8.5%, p < 0.05), and two substitutions (Met 209 --> Thr and Ser809 --> Phe) were found only in NIDDM patients. Equilibrium glucose infusion rates during a euglycaemic clamp in NIDDM and control subjects with the IRS-1 polymorphisms decreased by 29.5 and 22.0%, respectively on the average when compared to those in comparable groups without polymorphisms, although they were not statistically significant. Thus, IRS-1 polymorphisms may contribute in part to the insulin resistance and development of NIDDM in Japanese subjects; however, they do not account for the major part of the decrease in insulin-stimulated glucose uptake which is observed in subjects with clinically apparent NIDDM.

Amino Acid Sequence↗