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Biomedical subjects

M Nishida

Publications and source records attributed to M Nishida.

At least 19 recordsLinked to original sources
PubMed1992

Possible multifunction of glucose transporter. Transport of nicotinamide by reconstituted liposomes.

A kinetic study of the uptake of nicotinamide by reconstituted liposomes containing the human erythrocyte glucose transporter, compared with that of D-glucose, demonstrated that the Km and Vmax. values were almost the same for each compound, and that the uptake of D-glucose was competitively inhibited by nicotinamide. At 20 mM concentration, 2-deoxy-D-glucose, 3-O-methyl-D-glucose and 4,6-O-ethylidene-D-glucose all caused 50% inhibition of nicotinamide uptake, but L-glucose and nicotinic acid were not inhibitory. Similar results were obtained for the uptake of D-glucose. Cytochalasin B binding to the liposomes was inhibited in a dose-dependent manner by either nicotinamide or D-glucose. Antibody for glucose transporter detected in band 4.5 by SDS/PAGE inhibited the uptake of D-glucose and nicotinamide. A possible uptake of nicotinamide by nucleoside transporter was excluded. In human erythrocytes, cytochalasin B binding was inhibited dose-dependently by either nicotinamide or D-glucose, and cytochalasin B depressed the uptake of both nicotinamide and 2-deoxy-D-glucose. These findings were well reproduced in the reconstituted liposomes. The very close similarities between uptake of nicotinamide and D-glucose suggest that the glucose transporter plays a direct role in transport of nicotinamide, which is structurally quite different from monosaccharides, and thus that the transporter is probably multifunctional.

Biological Transport↗
PubMed1992

Hormonal control of manganese transport in the mouse thyroid.

The present study deals with a possible mechanism controlling the transport of manganese (Mn), an essential trace element, from the circulation to the thyroid. Mice were pretreated with propylthiouracil (PTU) or triiodothyronine (T3), and a measurement of the thyroid:serum concentration ratio (T/S) of radioactive manganese (54Mn) was carried out. The T/S of 54Mn was greatly enhanced by PTU, but reduced by T3. Several methods were used to demonstrate that the T/S of 54Mn depends upon the level of thyroid-stimulating hormone (TSH) in the serum. First, bovine TSH was injected into mice; an increase in the T/S resulted. Secondly, serum thyroxine and T3 levels measured by radioimmunoassay (RIA) suggested that PTU produced an increase in serum TSH and T3 a decrease. However, direct measurement of mouse TSH by RIA for rat TSH failed to produce proof of any changes in TSH level, owing to poor cross-reactivity. Taking all the information into account, it is concluded that Mn-transport into the thyroid is controlled by the thyroid state.

Animals↗
PubMed1992

Tyrosine-7 is an essential residue for the catalytic activity of human class PI glutathione S-transferase: chemical modification and site-directed mutagenesis studies.

The glutathione (GSH)-conjugating activity of human class Pi glutathione S-transferase (GST pi) toward 1-chloro-2,4-dinitrobenzene (CDNB) was significantly lowered by reaction with N-acetylimidazole, an O-acetylating reagent for tyrosine residues. Further, the replacement of Tyr7 in GST pi, which is conserved in all cytosolic GSTs, with phenylalanine by site-directed mutagenesis also lowered the activities toward CDNB and ethacrynic acid. The Km values of the mutant for both GSH and CDNB were almost equivalent to those of the wild type, while the Vmax of the former was about 55-fold smaller than that of the latter. Therefore, Tyr7 is considered to be an essential residue for the catalytic activity of GST pi.

Base Sequence↗
PubMed1992

Interaction of bovine serum albumin with the surface of a microcrystalline aluminum oxide hydroxide compound: a possible new type of phosphate adsorbent.

Aluminum hydroxide gel (ALG) has been effective for ameliorating acidosis associated with phosphatemia caused by hemodialysis. However, aluminum accumulation in the body causes severe side effects. As substitute for ALG, a new type of aluminum oxide hydroxide (tentatively named PT-A) was prepared with the hope of future clinical use. PT-A has a microcrystalline structure with a high resistance to pH change and has more phosphate-binding efficacy than ALG. It was tested for possible interaction with protein by adsorption test, zeta-potential analysis, X-ray diffraction, and scanning electron microscopy. Bovine serum albumin (BSA) was chosen as a model protein. The interaction of BSA with PT-A depended on the amount of adsorbent. Protein adsorption occurred rapidly and reached the maximal level at near neutral pHs. Phosphate adsorption was not affected by the presence of BSA, but the interaction of BSA with PT-A was significantly reduced by the presence of phosphate. Zeta-potential changes on the surface of PT-A indicated that the positively charged surface of PT-A was covered with negatively charged phosphate ions that repelled negatively charged BSA molecules. X-ray diffraction patterns indicated no observable structural alteration caused by adsorption of BSA or phosphate, and scanning electron microscopy revealed that BSA covered the outer surface of PT-A but did not cover small pores, where phosphate can freely penetrate.

Adsorption↗
PubMed1992

Phosphorus-31 magnetic resonance spectroscopy of forearm flexor muscles in student rowers using an exercise protocol adjusted for differences in cross-sectional muscle area.

To assess exercise energy metabolism of forearm flexor muscles in rowers, six male student rowers and six control subjects matched for age and sex were studied using phosphorus-31 magnetic resonance spectroscopy (31P-MRS). Firstly, to adjust for the effect of differences in cross-sectional muscle area, the maximal cross-sectional area (CSAmax) of the forearm flexor muscles was estimated in each individual using magnetic resonance imaging. Multistage exercise was then carried out with an initial energy production of 1 J.cm-2 CSAmax for 1 min and an increment of 1 J.cm-2 CSAmax every minute to the point of muscle exhaustion. A series of measurements of 31P-MRS were performed every minute. The CSAmax was significantly greater in the student rowers than in the control subjects [19.8 (SD 2.2) vs 17.1 (SD 1.2) cm2, P less than 0.05]. The absolute maximal exercise intensity (J.min-1) was greater in the rowers than in the control subjects. However, the maximal exercise intensity per unit of muscle cross sectional area (J.min-1.cm-2) was not significantly different between the two groups. During mild to moderate exercise intensities, a decrease in phosphocreatine and an increase in inorganic phosphate before the onset of acidosis were significantly less in the rowers, indicating a requirement of less adenosine 5'-diphosphate to drive adenosine 5'-triphosphate production. The onset of acidosis was also significantly delayed in the rowers. No difference was observed in forearm blood flow between the two groups at the same exercise intensity (J.min-1.cm-2).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

A modified model of reversible middle cerebral artery embolization in rats without craniectomy.

A detailed description is given of a new model of reversible focal cerebral ischaemia in rats. A spherical embolus, attached to the end of an 8-0 surgical thread was injected into the middle cerebral artery (MCA) via the external and internal carotid arteries (ECA and ICA) and could be withdrawn by pulling the extravascular portion of the thread when reperfusion was to follow ischaemia. In contrast to similar techniques, the 8-0 thread did not block blood flow in either the common carotid artery (CCA) or the ICA during ischaemia and, as the CCA did not have to be ligated, flow could be restored via the ipsilateral CCA and ICA after the ischaemic period. Neurological deficit, mortality rate, tissue water content, regional pH, ATP and, in some experiments, electroencephalogram (EEG) and cerebral blood flow (CBF) were evaluated in ischaemia and after various length of reperfusion. The overall mortality rate was 21%; all these animals were lost in the first hours of recirculation. The water content of their brains differed significantly from those who survived 24 hours (81 and 77% respectively). A significant difference in CBF of the ipsi- and contralateral putamen was found immediately after embolization (a CBF decrease of 26 +/- 5 and 5 +/- 5 ml/100 g/min, respectively), and relative hyperperfusion (+23 +/- 27 ml/100 g/min) was observed in the ipsilateral putamen during reperfusion. EEG amplitude declined on both the affected and non-affected sides after embolization (to 54 +/- 8% and 71 +/- 6% of pre-ischaemic values) and remained decreased (66 +/- 8% of control) on the ipsilateral side after 1 hour of reperfusion.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

The incidence of cardiac events in Japanese men with atypical or nonanginal chest pain: a prospective study on the significance of exercise testing.

The incidence of cardiac events in Japanese men (mean age 54 +/- 10 years) with atypical or nonanginal chest pain was assessed prospectively. Three groups of patients, those with typical angina (TA; n = 134), those with atypical angina (AA; n = 192), and those with nonanginal chest pain (NA; n = 311) were studied with regard to cardiac events (cardiac death or nonfatal myocardial infarction), risk factors, and results of exercise testing. The total cholesterol and high-density lipoprotein-cholesterol levels were significantly different among the three groups, but no differences were observed for other risk factors. The incidences of cardiac events were 8.5%, 2.2%, and 1.3% in the TA, AA, and NA groups, respectively (p less than 0.05) during 3.2 +/- 1.5 years. Significant ST segment changes were observed in 70.1%, 25.5%, and 18.0% of the patients in the TA, AA, and NA groups, respectively, at the time of enrollment. The risk ratio for cardiac events in a positive exercise test was 1.7 (difference not significant) for the TA group and 6.1 (p less than 0.05) for the others combined (AA and NA groups). The risk ratio adjusted for risk factors (Cox model) was 2.2 (difference not significant) for the TA group and 4.9 (p less than 0.05) for the AA and NA groups combined. In conclusion, the incidence of cardiac events in those with AA or NA chest pain was relatively low in Japan, but the independent prognostic significance of positive exercise testing was demonstrated in this group of patients.

Adult↗
PubMed1992

The effect of temporary hepatic artery or portal vein occlusion in obstructive jaundice.

Hepatic hemodynamics before vascular occlusion and the effect of transient hepatic artery or portal vein occlusion on the liver were investigated in normal dogs and dogs with experimentally induced obstructive jaundice by measurement of hepatic tissue blood flow (HTBF), index of hemoglobin concentration (IHb), oxygen saturation (ISO2), serum glutamic pyruvic transaminase (SGPT) concentration, and malonaldehyde (MDA) concentration in liver tissue. Livers with obstructive jaundice had increased blood flow and a lower hemoglobin concentration compared with normal livers at baseline before vascular occlusion. Percentage change of ISO2 from baseline was higher than percentage change of HTBF after reperfusion in both normal and obstructive jaundiced liver, although they were decreased to almost similar proportions during vascular occlusion. MDA concentration in obstructive jaundice after reperfusion following vascular occlusion was higher than in normal liver. Furthermore, MDA concentration after reperfusion following hepatic artery occlusion was increased compared with after reperfusion following portal venous occlusion in obstructive jaundice. There was no evidence of massive liver necrosis which was newly developed by transient vascular occlusion. These results represent the pathological condition in the liver before transient vascular occlusion and after reperfusion in obstructive jaundice.

Alanine Transaminase↗
PubMed1992

Transcription of a recombinant influenza virus RNA in cells that can express the influenza virus RNA polymerase and nucleoprotein genes.

A new transfection system for influenza virus was developed using the clone 76 cell line, in which the viral RNA polymerase and nucleoprotein (NP) genes can be expressed in response to dexamethasone. Ribonucleoprotein (RNP) complexes were reconstituted by expressing proteins from a chimeric NS-chloramphenicol acetyltransferase (CAT) RNA consisting of the full-length negative-strand RNA of the CAT gene positioned between the 5'- and 3'-terminal sequences of influenza virus RNA segment 8, and purifying NP from an NP gene-expressing Escherichia coli strain. When the reconstituted RNP was transfected into clone 76 cells, CAT was produced only when the synthesis of the three RNA polymerase subunits and NP was induced by treatment with dexamethasone.

Animals↗
PubMed1992

Co-existence of colonies with different serotypes and other biological characteristics in clinical isolates of Pseudomonas aeruginosa.

The biological characteristics of individual colonies of Pseudomonas aeruginosa from 138 specimens were investigated. Of these isolates, 90 (65.2%) formed colonies of similar appearance and morphology, and 48 (34.8%) formed colonies which differed either in appearance or morphology. The individual colonies of 138 isolates were tested for serotype. The former 90 isolates formed only the colonies with one kind of serotype, whereas 17 of the latter 48 isolates formed the colonies with more than one kind of serotype. All the 9 isolates tested also differed in other biochemical characteristics: acid productions from xylose, mannitol and maltose, urease production and gelatin liquefaction. beta-Lactamase activity was investigated in 7 isolates forming colonies with more than one serotype. There were no marked differences in beta-lactamase activity among the different colonies in 5 isolates but marked differences among those in the other 2 isolates.

Gelatin↗
PubMed1992

[Changes in serotypes of clinical isolates of Pseudomonas aeruginosa by anti-pseudomonal drugs].

Forty-two isolates of P. aeruginosa from various infections were each incubated in Mueller-Hinton broth including piperacillin, cefsulodin, ceftazidime, imipenem, gentamicin or norfloxacin (1MIC-4MIC) at 35 degrees C for 18 hours, and serotyped using monoclonal antibodies. Serotypes of 4 (9.5%)-8 (19.0%) of the 42 isolates each changed to different groups after incubation. No relationship was found between serotypes of the formed variants and anti-pseudomonal drugs used. When P. aeruginosa TA-2 was exposed to cefsulodin at different concentrations (1MIC and 2MIC) under the above conditions, the distinct variants different in serotypes were formed according to the drug concentrations. Furthermore, P. aeruginosa TA-2 and TA-13 were incubated in Mueller-Hinton broth including cefsulodin (1/2 or 2MIC) and gentamicin (1/2MIC), respectively, and the growth curves of parent and variant cells were determined. In the experiments, the variants appeared 6 hours after onset of the incubation and grew with the parents. The present results may explain our findings previously reported; coexistence of colonies different in serotype of P. aeruginosa isolated from some individual patients. The results indicate the possibility that alteration in bacterial surfaces in association with changes in serotypes might occur in vivo in these patients infected with P. aeruginosa and treated with anti-pseudomonal drugs.

Anti-Bacterial Agents↗
PubMed1992

In vitro and in vivo antibacterial activities of a new quinolone, OPC-17116.

The in vitro and in vivo antibacterial activities of OPC-17116 were compared with those of ofloxacin, enoxacin, ciprofloxacin, and tosufloxacin. The MICs of OPC-17116 for 90% of the strains tested were 0.125 to 8 micrograms/ml against gram-positive bacteria such as members of the genera Staphylococcus, Streptococcus, and Enterococcus: less than or equal to 0.063 to 16 micrograms/ml against members of the family Enterobacteriaceae; and less than or equal to 0.063 to 16 micrograms/ml against glucose-nonfermentative bacilli such as Pseudomonas aeruginosa. The activity of OPC-17116 against gram-positive organisms was comparable to that of tosufloxacin and higher than those of other reference drugs. The in vitro activity of OPC-17116 against gram-negative bacteria was similar to those of the reference drugs. In experimental systemic infections in mice with various organisms, the efficacy of OPC-17116 was similar to that of tosufloxacin and greater than those of ofloxacin, enoxacin, and ciprofloxacin. In a pyelonephritic model in mice with P. aeruginosa KU-1, OPC-17116 was as active as ciprofloxacin and more active than ofloxacin, enoxacin, and tosufloxacin. In respiratory tract infections in mice with Staphylococcus aureus Smith, Streptococcus pneumoniae TMS 3, and Klebsiella pneumoniae 3K25, the efficacy of OPC-17116 was generally greater than that of tosufloxacin. The peak level of OPC-17116 in the lungs of mice was 10 times higher than that in serum and was significantly greater than levels in lung achieved with an equivalent dose of the other quinolones. The therapeutic efficacy of OPC-17116 may depend not only on its in vitro activity but also on its high concentration in tissue.

Administration, Oral↗
PubMed1992

Endothelins. Myocardial actions of a new class of cytokines.

There is growing evidence to support the existence of a dynamic interaction in vivo between cardiac myocytes and adjacent microvascular endothelial cells in the regulation of both cardiac myocyte and possibly endothelial cell phenotype and function. Endothelins may be only one of several endogenous cytokines or autocoids that are released by the cardiac microvascular and/or endocardial endothelium and transported vectorially to adjacent myocytes that could modify cardiac contractile state, perhaps in response to changes in microvascular blood flow. Similarly, cardiac myocytes themselves could release cytokines that could directly affect endothelial cell proliferation or angiogenesis and indirectly elicit or modify the release of endothelium-derived cytokines and autocoids. Thus, in addition to modifying function, endothelial cell-cardiac myocyte interactions may also be of importance in the dynamic events that lead to myocardial wall remodeling and angiogenesis during hypertrophic growth and in the response to cardiac injury.

Amino Acid Sequence↗
PubMed1992

Characterization of thyroidal membrane-bound Mg-adenosinetriphosphatase activated by trypsin or poly-L-lysine.

The Mg-adenosinetriphosphatase (ATPase) in the thyroidal NaI-treated microsome fraction was activated by treatment with basic polyamino acids or trypsin, but not with acidic polyamino acids and basic proteins such as lysozyme and ribonuclease. The enzyme kinetics showed that the activation of trypsin or poly-L-lysine was due to an increase in the maximal velocity of the hydrolyzing reaction without a change in the affinity of the enzyme for its substrate. A break at about 25 degrees C was observed in the Arrhenius plots of Mg-ATPase in the trypsin- or poly-L-lysine treated preparations, but there was no break in the control preparation. These results suggest that the activating effect of trypsin or poly-L-lysine on Mg-ATPase activity in the thyroidal NaI-treated microsome fraction is related to the lipid environment surrounding the enzyme molecule in the thyroid cell membrane.

Animals↗
PubMed1992

Beneficial effect of stopping smoking on future cardiac events in male smokers with previous myocardial infarction.

UNLABELLED: We assessed the effect of stopping smoking on future cardiac events (cardiac death and non-fatal myocardial infarction (MI)) in 90 male smokers with previous MI by a prospective follow-up study. At the time of enrollment, the patients were divided into 2 groups according to their current smoking status (Group A: those who had stopped smoking (n = 60), and Group B: those who were still smoking (n = 30)). Follow-up was performed prospectively by annual postal questionnaires. During the mean follow-up period of 3.1 +/- 1.4 years, 13 cardiac events (11 cardiac deaths and 2 cases of non-fatal MI) occurred in the 87 evaluable patients. The cardiac event rates in Groups A and B were 8.5% and 28.6%, respectively, and the relative risk was 3.4 (Group A vs B, p less than 0.05) by univariate analysis. The relative risk using multivariate analysis (Cox) was also statistically significant (3.1, p less than 0.05). HDL-cholesterol was significantly lower in Group B than in Group A, but other coronary risk factors apart from smoking were not significantly different between the two groups. At the end of the follow-up period, 89.8% of the patients in Group A remained nonsmokers and 21% of the patients in Group B had stopped smoking. CONCLUSION: Stopping smoking significantly reduced the risk of future cardiac events in male smokers with previous MI. This prospective follow-up study demonstrated that a significant reduction in the risk of future cardiac events could be achieved by stopping smoking in this group of patients.

Adult↗
PubMed1992

A simple ergometer for 31P NMR spectroscopy during dynamic forearm exercise in a whole body magnetic resonance imaging system.

The purpose of this study was to construct a simple ergometer for the 31P NMR spectroscopic study of dynamic forearm exercise in a whole body magnetic resonance imaging system and to evaluate the total system and the physiological response to this type of exercise using a multistage protocol. The system consisted of a completely nonmagnetic assembly including a rope, pulley and weights. The work of lifting weights was quantitated. The exercise protocol of 1-min increments in work load enabled subjects to reach maximal effort. Phosphocreatine decreased linearly with an increase in work load and was accompanied by a fall in pH and an increase in lactate level in the antecubital vein of the exercising forearm; concomitantly, there was a slight increase in whole body oxygen uptake and heart rate. Spectroscopy gave reproducible results using this exercise protocol. These results demonstrate that this system provides a reliable means for performing 31P magnetic resonance spectroscopy studies during forearm exercise.

Adenosine Triphosphate↗
PubMed1992

Bilateral symmetrical cerebral arteriovenous malformations in the basal ganglia--case report.

A 21-year-old male presented with visual disturbance followed by severe headache. Computed tomography showed right thalamic hemorrhage entering the right lateral ventricle. Cerebral angiography revealed bilateral symmetrical arteriovenous malformations (AVMs) fed by the lenticulostriate, anterior choroidal, and lateral posterior choroidal arteries and draining into the vein of Galen. Partial removal of the right AVM induced bleeding on the left side, probably due to postoperative hemodynamic changes. Bilateral symmetrical cerebral AVMs are extremely rare, but provide serious problems for surgical intervention in the deep cerebrum.

Adult↗