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Biomedical subjects

T Yoshimura

Publications and source records attributed to T Yoshimura.

At least 289 records · Page 16Linked to original sources
PubMed1997

Effects of highly purified eicosapentaenoic acid on vascular reactivity to angiotensin II and norepinephrine in pregnant rabbits.

OBJECTIVE: We sought to determine whether the pressor response to an infusion of angiotensin II during pregnancy would be reduced by the oral administration of highly purified eicosapentaenoic acid ethyl ester (EPA-E). METHODS: We administered EPA-E orally to nine pregnant rabbits (200 mg/kg/day) from day 5 of gestation to day 5 postpartum. Pressor responses to graded doses of intravenously infused angiotensin II and norepinephrine were examined serially during pregnancy and the postpartum period. RESULTS: The EPA-E-treated, as well as the control pregnant rabbits (n = 6), were significantly less responsive to the vasoconstrictor effects of angiotensin II throughout pregnancy than the nonpregnant rabbits (n = 8). The vascular reactivity to infused angiotensin II in EPA-E-treated pregnant rabbits, as compared with that of control pregnant rabbits was unchanged, but reactivity to angiotensin II was lower only on the fifth postpartum day. The pressor responses to infused norepinephrine were unchanged during pregnancy and in the postpartum period, and EPA-E did not alter the response. The litters of four of the nine rabbits were partially or completely macerated. CONCLUSION: EPA-E did not reduce the already blunted pressor responsiveness to angiotensin II during pregnancy in rabbits. The effect of EPA-E in a state of increased pressor responsiveness during pregnancy due to a deficiency of vasodilatory prostaglandins needs to be determined.

Angiotensin II↗
PubMed1997

Retrograde cerebral perfusion with pharmacological cerebral protection in the repair of aortic arch aneurysm.

Twenty-six patients underwent resection and graft replacement of an aortic arch aneurysm (proximal arch,5; transverse arch:2, distal arch,8; and type A dissecting aneurysm. Retrograde cerebral perfusion with pharmacological cerebral protection was carried out during aortic arch aneurysm surgery. Prostaglandin E1, thiopental methylpredonisolone were administered for cerebral protection during core cooling. D-Mannitol and deferoxamine mesylate (radical scavengers) were administered for prevention of reperfusion injury. retrograde cerebral perfusion time was 48 +/- 16 minutes (range 20-80 minutes). Perfusion flow was 288 +/- 93 mL/min (range 150-500 mL/min). Since retrograde cerebral perfusion requires no arterial cannulation or aortic cross clamp, the operative field is simplified, and the risks of air and debris emboli to the brain were minimized. Reconstruction was designed to minimize the circulatory arrest time. Eleven cases underwent emergency surgery due to rupture and acute dissection. Five patients (19.2%) died (three from bleeding from the distal anastomosis, one from postoperative DIC and, one from intraoperative dissection). The remaining 21 patients survived neurologically intact. Retrograde cerebral perfusion with pharmacological cerebral protection is a very simple method to prevent air embolism or thromboembolism in aortic arch aneurysm surgery and allows aortic arch replacement in a bloodless field. In spite of the extended circulatory arrest time, recovery of consciousness was complete.

Adult↗
PubMed1997

[A case report of alternating abducens hemiplegia with special reference to the supranuclear pathway to the facial nucleus].

A case of alternating abducens hemiplegia was reported. A 16-year-old girl developed alternating hemiplegia characterized by the left abducens nerve palsy and right hemiparesis. In addition, she had right supranuclear facial nerve palsy. A brain MRI showed left mid to lower pontine lesion and vertebral angiography revealed medullary venous malformation in the left pons. SEP with right posterior tibial nerve stimulation showed a delayed central conduction time, suggesting that the lesion involved left medial lemniscus. We previously reported a 39-year-old man who developed pure alternating abducens hemiplegia. He did not show supranuclear facial nerve palsy or SEP abnormality. These findings support the idea that the supranuclear facial nerve fiber leaves the pyramidal tract at the upper to middle pons and descends in the area of the pontine tegmentum around the medial lemniscus.

Abducens Nerve↗
PubMed1997

[A case of successfully treated fungal tricuspid infective endocarditis with repeated pulmonary embolism].

A case of successfully treated fungal tricuspid infective endocarditis with repeated pulmonary embolism is reported. A 60-year-old man had received along term intravenous hyperalimentation for the treatment of the complication after hepatopancreatoduodenectomy, associated with Candida sepsis. He was once discharged, successfully treated with antifungal agents. But he was readmitted to our hospital due to fever, cough and chest pain. Blood culture revealed Candida tropicalis. Pulmonary scintigraphy and angiography revealed multiple infarcts of the right lung, and echocardiography showed vegetation on the tricuspid valve. Because of exacerbation of shortness of breath, tricuspid valvuloplasty and thromboembolectomy in the pulmonary arteries was performed. Postoperative course was uneventful and he had a marked improvement of dyspnea after operation.

Candidiasis↗
PubMed1997

Perinatal bile acid metabolism: analysis of urinary bile acids in pregnant women and newborns.

The metabolism of bile acids in 30 pregnant women was evaluated by analyzing the urinary composition of bile acids during late gestation (weeks 30-41) and again in these women and their newborn infants during the first week after delivery. The levels of individual bile acids were determined by gas chromatography-mass spectrometry after solvolysis and hydrolysis of bile acid conjugates. The mean total bile acid/creatinine ratio in pregnant women decreased from 1.22 micromol/mmol creatinine at 30-32 weeks of gestation to 0.15 micromol/mmol creatinine at 6-7 days after delivery. The mean percentage of 1beta-hydroxylated bile acids peaked at 27% at 3-4 days after delivery. In newborn infants, the mean total bile acid/creatinine ratio rapidly increased from 3.39 micromol/mmol creatinine at birth to 54.33 micromol/mmol creatinine at 7 days. During this period, large amounts (40-50%) of unsaturated ketonic bile acids, especially 7alpha,12alpha-dihydroxy-3-oxo-5beta-chol-1-en-24-oic acid and 7alpha,12alpha-dihydroxy-3-oxo-4-cholen-24-oic acid, were observed in the infants' urine. These data suggest that, during the perinatal period, the formation of polyhydroxylated and unsaturated ketonic bile acids probably represents a mechanism for the excretion of bile salts, and that the metabolism of bile acids in both the mother and the infant changes significantly after birth.

Adult↗
PubMed1996

Site-directed mutagenesis of the amino acid residues in beta-strand III [Val30-Val36] of D-amino acid aminotransferase of Bacillus sp. YM-1.

The beta-strand III formed by amino acid residues Val30-Val36 is located across the active site of the thermostable D-amino acid aminotransferase (D-AAT) from thermophilic Bacillus sp. YM-1, and the odd-numbered amino acids (Tyr31, Val33, Lys35) in the strand are revealed to be directed toward the active site. Interestingly, Glu32 is also directed toward the active site. We first investigated the involvement of these amino acid residues in catalysis by alanine scanning mutagenesis. The Y31A and E32A mutant enzymes showed a marked decrease in k(cat) value, retaining less than 1% of the wild-type enzyme activity. The k(cat) values of V33A and K35A were changed slightly, but the Km of K35A for alpha-ketoglutarate was increased to 35.6 mM, compared to the Km value of 2.5 mM for the wild-type enzyme. These results suggested that the positive charge at Lys35 interacted electrostatically with the negative charge at the side chain of alpha-ketoglutarate. Site-directed mutagenesis of the Glu32 residue was conducted to demonstrate the role of this residue in detail. From the kinetic and spectral characteristics of the Glu32-substituted enzymes, the Glu32 residue seemed to interact with the positive charge at the Schiff base formed between the aldehyde group of pyridoxal 5'-phosphate (PLP) and the epsilon-amino group of the Lys145 residue.

Alanine Transaminase↗
PubMed1996

[Occupational dangers to health of nursing staffs in hemodialysis units].

Since hemodialysis patients are at high risk for blood-borne viral infection such as hepatitis B and C virus infection, nursing staffs of the hemodialysis units have a significant occupational exposure to blood-borne virus infection. Furthermore, they are in danger of contacting occupational low back-pain because they have to take care of patients in a half-rising position. In addition, they may also suffer from burned-out syndrome because they have to look after all the chronic renal failure patients as well as run machines during the hemodialysis procedure. In this paper, we describe occupational danger to health of nursing staffs working in hemodialysis units.

Back Pain↗
PubMed1996

Characterization of cis-acting elements of the gene for macrophage-stimulating protein from the human. The involvement of positive and negative regulatory elements.

To analyze the promotor region of the human macrophage-stimulating protein (MSP) gene, the 5'-flanking region of this gene was cloned. The major initiation site was determined at T located 49 base pairs upstream of the translation initiation site by primer extention with mRNA from HepG2 and Hep3B cells. There was no TATA sequence in this region. Transient transfection assay with 5'-deletion constructs showed that the transcription of this gene was regulated by positive and negative regulatory elements (PRE and NRE). The PRE (-34 to +2) was essential for the maximal transcription of this gene, and the NRE (-141 to -34) appeared to be responsible for the tissue-specific expression of the gene. The PRE contained the CCAAT sequence and a mutation from CCAAT to CTGAT resulted in a significant loss of the transcriptional activity. Electrophoretic mobility shift assay suggested that two different proteins bound to the PRE (MSP-PRE-binding protein-1 (MSP-PREB1) and 2). MSP-PREB1 and 2 were detected in various cell types, and the CCAAT sequence was involved in these bindings. These findings indicate that MSP-PREB1 and 2 are positive regulators. Further characterization also revealed that MSP-PREB2 was identical to CCAAT binding transcription factor, also known as NF-Y.

Base Sequence↗
PubMed1996

Stereospecificity of thermostable ornithine 5-aminotransferase for the hydrogen transfer in the L- and D-ornithine transamination.

The thermostable ornithine 5-aminotransferase of a thermophile, Bacillus sp. YM-2, is unique in acting on both enantiomers of ornithine, although less effectively on the D-enantiomer. We studied the stereospecificity of the enzyme for the hydrogen abstraction from C-5 of the substrate moiety and the addition and removal of the hydrogen at C-4' of the cofactor (pyridoxal phosphate and pyridoxamine phosphate) moiety of the external Schiff base intermediate in the transamination of L- and D-ornithine. L- and D-[5-3H]ornithines were prepared by incubation of L- and D-ornithines with the enzyme in 3H2O, respectively. When the L-[5-3H]ornithine was incubated with L-ornithine 5-aminotransferase of a mesophile, Bacillus sphaericus, which catalyzes the stereospecific abstraction of pro-S hydrogen from C-5 of L-ornithine, most of the tritium was released into the solvent. The D-[5-3H]ornithine also reacted with the enzyme of B. sphaericus in the presence or absence of the amino acid racemase of Pseudomonas putida. Tritium was released only in the presence of the racemase, which catalyzes the racemization of ornithine but does not act on C-5 of ornithine. These results show that the Bacillus sp. YM-2 ornithine 5-aminotransferase stereospecifically abstracts the pro-S hydrogen from C-5 of L- and D-ornithine. When the apo form of the enzyme was incubated with pyridoxamine 5'-phosphate that was stereospecifically tritiated at C-4' and 2-oxoglutarate in the presence of L-ornithine or D-ornithine, tritium was released exclusively from (4'S)-[4'-3H]pyridoxamine. Therefore, addition and abstraction of hydrogen at C-4' of the cofactor moiety stereospecifically occur on the si face of the external Schiff base intermediate in the overall transamination catalyzed by Bacillus sp. YM-2 ornithine 5-aminotransferase irrespective of the C-2 configuration of the amino donor.

Amino Acid Isomerases↗
PubMed1996

Vitamin B12 affects non-photic entrainment of circadian locomotor activity rhythms in mice.

Administration of vitamin B12 (VB12) has been reported to normalize human sleep-wake rhythm disorders such as non-24-h sleep-wake syndrome (HNS), delayed sleep phase syndrome (DSPS) or insomnia. However, the mechanisms of the action of VB12 on the rhythm disorders are unknown. In the present study, therefore, effects of VB12 on circadian rhythms of locomotor activity were examined in mice. In the first experiment, CBA/J mice were maintained under continuous light condition (LL) or blinded, and after free-running rhythms became stable, the mice were intraperitoneally injected with either VB12 or saline at a fixed time every day. In all the mice with tau > 24 h, saline injections resulted in entrainment of circadian rhythms, whereas not all the mice with tau < 24 h entrained to the injection. In contrast to saline injections, VB12 injections did not always induce entrainment and about half of the mice with tau > 24 h free-ran during the injection. In the second experiment, the amount of phase advances of circadian rhythms induced by a single injection of saline at circadian time (CT) 11 under LL was compared between the mice with and without VB12 silastic tubes. The results showed that the amplitude of phase advances was smaller in the mice with VB12 than those without VB12. In the third experiment, daily injections of saline were given to the mice with VB12 silastic tubes maintained under LL. In this chronic treatment of VB12 as well, attenuating effects of VB12 on saline-induced entrainment were observed. These results suggest that VB12 affects the mechanisms implicated in non-photic entrainment of circadian rhythms in mice.

Animals↗
PubMed1996

[The association of self-rated health and mortality--a 7-year follow-up study of a Japanese community].

This study aims to examine whether self-rated health is an independent predictor of cause-specific mortality even after the influence by a variety of factors in relation to mortality reported by previous studies have been excluded. This study included randomly selected 4,259 inhabitants (1,827 men and 2,432 women) in Y city, Fukuoka prefecture, Japan, aged from 30 to 79 in 1987. These subjects were surveyed in 1987 by self-administered questionnaires regarding self-rated health as well as life habits, and followed up for their vital status and underlying causes of death. After excluding the individuals who were lost to follow up or who didn't respond to the question on self-rated health, 4,046 individuals were analysed to see the relationship between self-rated health and cause-specific mortality by Cox proportional hazard models, controlling for sex, age, smoking, BMI, medical care use and ADL. It was shown that relative risks for all causes, cancer, circulatory disease and other causes among the unhealthy group were 2.95 (95% CI: 1.93-4.50), 2.96 (1.53-5.73), 2.32 (0.86-6.26) and 4.09 (2.12-7.89), relatively. In the analyses of the subgroup (subjects without diseases in 1987 or subjects excluding deceased cases within first 3 years after follow-up), to avoid selection bias, the association between self-rated health and mortality was substantially similar to the results obtained in the former analysis, even the association was weakened. Even after excluding both of the subjects with diseases in 1987 and the subjects who died in the first 3 years after follow-up, self-rated health could be associated with mortality from all causes (RR = 1.89, 95%CI; 0.91-3.94). From the results it is suggested that self-rated health itself can be the independent predictor of mortality.

Adult↗
PubMed1996

[A sero-epidemiological study on atrophic gastritis and Helicobacter pylori infection].

The aim of this study is to clarify the relationship between the incidence of atrophic gastritis and Helicobacter pylori infection. A case control study was conducted in 1995. Cases and controls were selected among those who took an annual health examination in a rural area of Fukuoka Prefecture. Cases are those who were not diagnosed as having atrophic gastritis in 1991 or 1992 but were diagnosed as having atrophic gastritis in 1995 by the examination of serum pepsinogens. Controls are those who were not diagnosed as having atrophic gastritis between 1991, or 1992 and 1995. Helicobacter pylori infection was evaluated by anti Helicobacter pylori IgG in 1995. The odds ratio for atrophic gastritis was calculated using Logistic regression analysis. The odds ratio of age and sex was not significant, but the odds ratio of Helicobacter pylori infection was significantly elevated (5.2, 95% confidence interval: 2.08-13.17). As for the influence of sex difference on the incidence of atrophic gastritis by Helicobacter pylori infection, the odds ratio among males was not significant (1.4, 95% confidence interval: 0.30-6.10), but the odds ratio among females was significantly high (9.8, 95% confidence interval: 2.82-34.11). These results suggest that Helicobacter pylori infection is associated with the incidence of atrophic gastritis. There may be a risk difference between males and females in the incidence of atrophic gastritis caused by Helicobacter pylori infection.

Adult↗
PubMed1996

Oxygen and one reducing equivalent are both required for the conversion of alpha-hydroxyhemin to verdoheme in heme oxygenase.

Heme oxygenase is a central enzyme of heme degradation and associated carbon monoxide biosynthesis. We have prepared the alpha-hydroxyheme-heme oxygenase complex, which is the first intermediate in the catalytic reaction. The active site structure of the complex was examined by optical absorption, EPR, and resonance Raman spectroscopies. In the ferric form of the enzyme complex, the heme iron is five coordinate high spin and the alpha-hydroxyheme group in the complex assumes a structure of an oxophlorin where the alpha-meso hydroxy group is deprotonated. In the ferrous form, the alpha-hydroxy group is protonated and consequently the prosthetic group assumes a porphyrin structure. The alpha-hydroxyheme group undergoes a redox-linked conversion between a keto and an enol form. The ferric alpha-hydroxyheme reacts with molecular oxygen to form a radical species. Reaction of the radical species with a reducing equivalent yields the verdoheme-heme oxygenase complex. Reaction of the ferrous alpha-hydroxyheme-heme oxygenase complex with oxygen also yields the verdoheme-enzyme complex. We conclude that the catalytic conversion of ferric alpha-hydroxyheme to verdoheme by heme oxygenase requires molecular oxygen and one reducing equivalent.

Animals↗
PubMed1996

High-efficiency in vivo gene transfer using intraarterial plasmid DNA injection following in vivo electroporation.

A novel method for high-efficiency and region- controlled in vivo gene transfer was developed by combining in vivo electroporation and intraarterial plasmid DNA injection. A mammalian expression plasmid for the Escherichia coli lacZ gene (driven with a SV40 early promoter) was injected into the internal carotid artery of rats whose brain tumors (from prior inoculation) had been electroporated between two electrodes. The lacZ gene was efficiently transferred and expressed in the tumor cell 3 days after plasmid injection. However, neither any gene transfers nor any elevated lacZ activity was detected in tissues outside the electrodes. The plasmid was not transferred without electroporation. Human monocyte chemoattractant protein-1 cDNA was also transferred by this method, and its long-lasting (3 weeks) expression was confirmed by using the Epstein-Barr virus episomal replicon system. The expressed monocyte chemoattractant protein-1 protein was functional, as evident by the presence of a large number of monocytes in tumor tissue. This method, electrogene therapy, which does not require viral genes or particles, allows genes to be transferred and expressed in desired organs or tissues, and it may lead to the development of a new type of highly effective gene therapy.

Animals↗
PubMed1996

Role of heme axial ligands in the conformational stability of the native and molten globule states of horse cytochrome c.

One unique aspect of cytochrome c folding concerns the involvement of the covalently attached heme group and its axial ligands. To elucidate the role of the ligands in stabilizing the native and molten globule states, we studied the conformational and thermodynamic features of the iron-free derivative of horse cyctochrome c (porphyrin-cytochrome c). At neutral pH, far-UV circular dichroism suggested that porphyrin-cytochrome c has native-like alpha-helices, whereas near-UV CD suggested that the side-chains are flexible. Its stability against heat or denaturants was much less than that of the intact protein, and similar to that of the acidic molten globule state of the holoprotein. These results indicate that, at neutral pH, the ligation of His18 of the iron is important for the maintenance of the native structure whereas the Met80 ligation is not essential, and that porphyrin-cytochrome c assumes a molten globule-like state. Porphyrin-cytochrome c was largely unfolded at pH 2.0 in the absence of salt, but assumed another molten globule-like structure in the presence of anions. The salt-induced stabilization of the molten globule-like state was the same as that of apocytochrome c, requiring a much higher salt concentration than holocytochrome c. These results indicate that, at acidic pH, the His18 ligation is important, although not essential, for stabilizing the molten globule state. Taken together, both specific (i.e. the His18 axial ligand, as observed at acidic pH) and nonspecific interactions (the hydrophobic effects of the heme, as observed at neutral pH) contribute to stabilizing the molten globule state.

Animals↗
PubMed1996

Evident difference in the excitability of the motoneuron pool between normal subjects and patients with spasticity assessed by a new method using H-reflex and M-response.

The excitability of the motoneuron (MN) pool in the resting state was compared between normal control subjects and patients with spasticity resulting from HTLV-I-associated myelopathy, using a new parameter, Hslp/Mslp, and the conventional parameters Hmax/Mmax and Hth/Mth. Differences in the excitability of the MN pool between these two groups reached a high degree of statistical significance only when assessed with the new parameter. This suggests the methodological advantage of the Hslp/Mslp over both Hmax/Mmax and Hth/Mth for evaluation of the excitability of the MN pool in the resting state.

Action Potentials↗
PubMed1996

Spectroscopic characterization of nitrosylheme in nitric oxide complexes of ferric and ferrous cytochrome c' from photosynthetic bacteria.

Reactions of ferric and ferrous cytochromes c' from four photosynthetic bacteria (Rhodobacter capsulatus ATCC 11166, Rhodopseudomonas palustris ATCC 17001, Rhodospirillum rubrum ATCC 11170, and Chromatium vinosum ATCC 17899) with nitric oxide have been investigated by electronic absorption and electron paramagnetic resonance spectroscopies. The heme iron(III) of these ferric cytochromes c' has been recently reported to be in a quantum mechanically admixed (S = 5/2, 3/2) state [Fujii, S., Yoshimura, T., Kamada, H., Yamaguchi, K., Suzuki, S., Shidara, S. and Takakuwa, S. (1995) Biochim. Biophys. Acta 1251, 161-169]. The affinity of ferric cytochromes c' for NO among these bacterial species (C. vinosum > Rps. palustris approximately Rb. capsulatus >> R. rubrum) was apparently related to the S = 3/2 content in the or der. In the reaction of ferrous cytochrome c' with NO, six- and five-coordinated nitrosylhemes, which represent species with and without a ligand at the axial position trans to nitrosyl group, have been formed. The content of six-coordinated nitrosylheme in NO-ferrous cytochrome c' has been determined to be Rb. capsulatus approximately Rps. palustris > C. vinosum < R rubrum, suggesting that a stability of iron-to-histidine bond decreases with this order. The NO reactions of ferric and ferrous cytochromes c' from photosynthetic bacteria have been compared with those of cytochromes c' from denitrifying bacteria.

Cytochrome c Group↗