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Biomedical subjects

K Nosaka

Publications and source records attributed to K Nosaka.

At least 73 records · Page 4Linked to original sources
PubMed1996

Roles of Ca2+ and PKC in regulation of acid/base transport in isolated proximal tubules.

Roles of Ca2+ and protein kinase C (PKC) in the regulation of acid/base transport in isolated rabbit proximal tubules were investigated by measuring cytosolic Ca2+ concentrations ([Ca2+]i) and cell pH (pHi) with fluorescent probes. Ionomycin (0.2 microM) increased [Ca2+]i by approximately 200 nM but did not affect the basolateral Na(+)-HCO3- cotransporter. However, the apical Na+/H+ exchanger was inhibited by 50% by ionomycin, and this inhibition was abolished either by 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid, an intracellular Ca2+ chelator, or by KN-62, an inhibitor of calcium-calmodulin-dependent protein kinase II (CaM kinase II). On the other hand, phorbol 12-myristate 13-acetate (PMA, 0.5 microM) did not affect the apical Na+/H+ exchanger but did stimulate the basolateral Na(+)-HCO3- cotransporter by 60-80%, and this stimulation was prevented by calphostin C, an inhibitor of PKC. Consistent with the cotransporter stimulation, PMA decreased steady-state pHi in the presence of CO2/ HCO3-. These results indicate that 1) the acute increase in [Ca2+]i within physiological ranges inhibits the apical Na+/H+ exchanger, probably through mediation of CaM kinase II; and 2) the short-term PKC activation stimulates the basolateral Na(+)-HCO3- cotransporter.

Acids↗
PubMed1996

Changes in serum enzyme activities after injection of bupivacaine into rat tibialis anterior.

This study investigated the time course of changes in serum creatine kinase (CK), aspartate aminotransferase (AST), and alanine amino-transferase (ALT) activities after intramuscular injection of bupivacaine into the tibialis anterior (TA) of rats. Morphological changes in muscle cells, relationships between the amount of increase in the enzyme activities and the muscle mass damaged, and responses of serum enzymes to additional injections of bupivacaine hydrochloride (BPVC) were also examined. Adult male Wistar rats (24 wk) were placed into one of four groups. Group A (n = 7) was a control, and no injection was applied. Saline solution (0.5 ml of 0.9%) was injected into the right TA for group B (n = 5). BPVC (0.5 ml of 0.5%) was injected into the right TA for group C (n = 9) and into both the right and left TA for group D (n = 9). No increases in CK, AST, and ALT were observed for groups A and B. After BPVC injection, groups C and D showed significant (P < 0.01) increases in serum enzyme activities. CK peaked 4 h after BPVC injection, and AST and ALT peaked 12 h postinjection, then returned to the baseline by the time infiltration of mononuclear cells into the damaged muscle cells progressed. The amount of enzyme increase was significantly larger (P < 0.01) for group D compared with group C. Injection of BPVC into the right then into the left TA 4 h later displayed a bipolar response, and the second injection into the TA 12 wk after the first injection resulted in smaller increase in serum enzyme activities. It appeared that increases in serum enzyme activities reflected muscle damage; however, changes in enzymes occurred in the early stage of myonecrosis.

Alanine Transaminase↗
PubMed1996

Immunohistological study in cases of HELLP syndrome (hemolysis, elevated liver enzymes and low platelets) and acute fatty liver of pregnancy.

We immunohistologically studied the hepatic tissue sections in cases with the syndrome of hemolysis, elevated liver enzymes, and low platelets (HELLP syndrome; n = 2) and acute fatty liver of pregnancy (AFLP; n = 2) compared to necropsy controls. Unlike in the AFLP cases, a marked infiltration of neutrophils in liver tissues was found in both cases of the HELLP syndrome. Immunostaining with the antihuman (polyclonal) TNF-alpha, IL-1 beta, IL-8 and antihuman neutrophil elastase (monoclonal antibody) was performed in paraffin-embedded hepatic tissue sections. Liver tissues in HELLP syndrome patients were stained strongly with TNF-alpha and neutrophil elastase antibody. The strongest staining pattern was observed in the eclamptic case, whereas in the AFLP cases, as in the necropsy controls, a very weak staining for anti-TNF-alpha and elastase antibody was found. The liver sections of the HELLP syndrome cases were moderately stained with polyclonal IL-1 beta and IL-8 antibodies whereas AFLP and controls had a very faint staining. Significant correlations were found between the numbers of necrotic hepatocytes and elastase dots in the same microscopic fields (randomly selected) of liver sections from two cases of HELLP syndrome (r2 = 0.63; p < 0.0001), which might suggest a neutrophil-mediated tissue damage in such a disease. This study suggests that a cytokine- and neutrophil-mediated liver injury occurs in the HELLP syndrome but not in AFLP.

Adult↗
PubMed1995

The role of ATP hydrolysis in the function of the chaperonin GroEL: dynamic complex formation with GroES.

In order to understand the role of ATP hydrolysis of the chaperonin GroEL during protein folding, we have studied GroEL-GroES complex formation in the presence of ATP or ADP by using capillary electrophoresis and surface plasmon resonance. Capillary electrophoresis analysis showed that the GroEL 14-mer and GroES 7-mer formed a 1:1 complex in the presence of ATP. In the presence of ADP, both the association and dissociation rates of the complex were slower by about one order of magnitude than the rates in the presence of ATP at 25 degrees C. The implications of such a stable complex on the overall mechanism of chaperonin function are discussed.

Adenosine Diphosphate↗
PubMed1995

Adenosine kinase-deficient mutant of Saccharomyces cerevisiae.

A cordycepin-resistant mutant strain of Saccharomyces cerevisiae (CD-R2) was found to be deficient in adenosine kinase. This mutant accumulated S-adenosylhomocysteine during growth in the presence of exogenous adenosine and it grew in a pseudohyphal manner in the presence of this nucleotide.

Adenosine↗
PubMed1995

Unilateral pulmonary agenesis with tracheoesophageal fistula: a case report.

The authors describe a neonate with unilateral pulmonary agenesis and esophageal atresia (Gross type C). Definitive repair for the atresia was completed during the early neonatal period, and the patient is alive and well more than 1 year after surgery. Most patients with pulmonary agenesis associated with esophageal atresia have not survived, mainly because of postoperative cardiorespiratory failure. Early protection and preservation of respiratory units is essential for the management of these patients.

Esophageal Atresia↗
PubMed1995

The urinary concentration of sialic acid is increased in non-insulin-dependent diabetic patients with microangiopathy: a possible useful marker for diabetic microangiopathy.

In order to investigate the relationship between urinary excretion of sialic acid and the severity of diabetic microangiopathy, urinary levels of sialic acid were determined in patients with non-insulin-dependent diabetes mellitus. The urinary molar ratio of sialic acid to creatinine in the diabetic patients was significantly higher than in the healthy controls (p < 0.01). Moreover, the urinary ratio was found to be gradually increased with the degree of diabetic microangiopathy. Urine molar ratio of sialic acid to creatinine in patients with proliferative diabetic retinopathy was significantly higher than in patients without retinopathy (p < 0.01). Urinary excretion in patients with macroproteinuria was also significantly higher than in patients without nephropathy (p < 0.01). Since urinary levels of sialic acid are proportionally increased with the severity of diabetic microangiopathy, the measurement of urinary sialic acid could become a useful biochemical means to monitor the degree of diabetic microangiopathy.

Adult↗
PubMed1995

Muscle damage following repeated bouts of high force eccentric exercise.

This study was designed to test the hypothesis that performing repeated bouts of eccentric exercise when muscles were not recovered from previous exercise would exacerbate muscle damage. Twelve nonweight-trained males (21.7 +/- 2.4 yr) performed three sets of 10 eccentric actions of the elbow flexors (ECC) using a dumbbell that was set at 80% of the preexercise maximal isometric force level. This same exercise was repeated 3 and 6 d after the first exercise. Maximal isometric force, relaxed and flexed elbow joint angle, muscle soreness, plasma creatine kinase, and glutamic-oxaloacetic transaminase activities were assessed. Ultrasound images were taken from the upper arm. These measures (except soreness) were assessed immediately before and after each eccentric exercise bout (ECC1, ECC2, and ECC3) and 3 d after ECC3. Soreness was assessed prior to ECC1 and once a day for 9 d thereafter. All criterion measures changed significantly (P < 0.01) after ECC1. ECC2 and ECC3 performed 3 and 6 d after ECC1 did not exacerbate damage and did not appear to slow the recovery rate. Increased echointensity in ultrasound images was demonstrated following ECC1, but no indication of increased damage was found after ECC2 and ECC3. Strenuous exercise performed with "damaged" muscles did not exacerbate damage or affect the repair process.

Adaptation, Physiological↗
PubMed1994

Isolation and characterization of the THI6 gene encoding a bifunctional thiamin-phosphate pyrophosphorylase/hydroxyethylthiazole kinase from Saccharomyces cerevisiae.

Thiamin-phosphate pyrophosphorylase (TMP-PPase; EC 2.5.1.3) involved in de novo synthesis of thiamin in Saccharomyces cerevisiae is a bifunctional enzyme with 4-methyl-5-beta-hydroxyethylthiazole kinase (Th-kinase; EC 2.7.1.50) activity, which is an octamer of identical 60-kDa subunits (Kawasaki, Y. (1993) J. Bacteriol. 175, 5153-5158). Previous study demonstrated that the activities of both TMP-PPase and Th-kinase are reduced by the mutation of a single nuclear gene, designated THI6. We have cloned the THI6 gene from a yeast genomic library by functional complementation of the thi6 mutant and determined by DNA blot analysis that THI6 is located on chromosome XVI. The nucleotide sequence of the THI6 gene contained an open reading frame of 1,620 base pairs encoding a 540-amino acid polypeptide with a calculated molecular weight of 58,058, which is similar to the determined molecular mass of the purified bifunctional enzyme. Gene disruption demonstrated that the thi6 null strain is auxotrophic for thiamin, indicating that the THI6 protein is essential for thiamin synthesis in yeast. A recently isolated thi6 mutant, thi6-3, bearing a replacement of Glu370 by Lys370, showed a decrease in only Th-kinase activity, proving that the THI6 gene of S. cerevisiae encodes a structural gene of the thiamin biosynthetic bifunctional enzyme. Furthermore, complementation analysis of the thi6 null strain with the modified THI6 DNAs by a 12-nucleotide linker insertion suggested that a region from amino acids 138 to 187 and that from amino acids 370 to 453 are involved in functional domains of TMP-PPase and Th-kinase, respectively, whereas the COOH-terminal region is necessary for both enzyme activities. Strains conferring no Th-kinase but slight TMP-PPase activity could grow in medium without thiamin, suggesting that 4-methyl-5-beta-hydroxyethylthiazole is not involved in the pathway of de novo synthesis of thiamin via 4-methyl-5-beta-hydroxyethylthiazole monophosphate. Northern blot analysis demonstrated that THI6 gene expression is regulated at the mRNA level by intracellular thiamin pyrophosphate, a coenzyme form of thiamin, and that it requires the positive regulatory factors encoded by the THI2 and THI3 genes.

Alkyl and Aryl Transferases↗
PubMed1994

Chaperonin GroE and ADP facilitate the folding of various proteins and protect against heat inactivation.

In the presence of ADP, the molecular chaperones GroEL and GroES from Escherichia coli not only facilitated the refolding of various proteins, but also prevented their irreversible heat inactivation in vitro. Without nucleotides the refolding reactions were arrested by GroEL. Addition of GroES and ADP to the reaction mixture initiated the refolding reactions and the enzyme activities were regained efficiently. The presence of GroE (GroEL and GroES) and ADP also protected against heat inactivation of native enzymes at various temperatures. These findings suggest that in the presence of GroES, nucleotide binding is an important event in the mechanism of GroEL-facilitated protein folding.

Adenosine Diphosphate↗
PubMed1994

Effect of eccentric exercise on plasma enzyme activities previously elevated by eccentric exercise.

The purpose of this study was to investigate whether plasma activities of creatine kinase (CK) and glutamic-oxaloacetic transaminase (GOT), elevated by eccentric exercise, would be affected by a second bout of eccentric exercise. A group of 26 male students [20.3 (SD 1.9) years] were placed in one of three groups. Group A (n = 8) performed one bout of 24 maximal eccentric actions (ECC) of the forearm flexors (ECC1), and groups B (n = 10) and C (n = 8) performed two bouts of ECC (ECC1, ECC2). The ECC2 was performed by the opposite arm 3 days (group B) or 5 days (group C) after ECC1. None of the subjects had performed this eccentric exercise prior to this study. Maximal isometric force (MIF), range of motion (ROM), upperarm circumference (CIR), muscle soreness level (SOR), and plasma CK and GOT activities were measured before and for 8 days (group B) or 10 days (groups A, C) postexercise. The MIF, ROM, CIR, and SOR changed significantly after exercise (P < 0.01), and no significant differences in changes were found between ECC1 and ECC2, or among the groups. This suggested that ECC1 and ECC2 produced a similar stress to the forearm flexor muscles. Therefore, it was expected that CK and GOT activities would show similar increases after ECC1 and ECC2. However, increases in CK and GOT activities after ECC2 were significantly smaller (P < 0.01) than after ECC1 in both groups B and C. The results of this study confirmed that CK and GOT responses were diminished when initial blood enzyme activities were elevated.

Adult↗
PubMed1994

Basic fibroblast growth factor messenger RNA is expressed strongly at the acute stage of cerebral contusion.

Basic fibroblast growth factor (bFGF) has a neurotrophic effect both in vitro and in vivo, and is considered to play an important role in the maintenance of neuronal functions in the normal brain. Neural damage in brain contusion progresses after the primary injury of trauma because of cerebral hemodynamic and metabolic impairment including intracranial hemorrhage and/or brain swelling. Northern blot analysis of bFGF mRNA was performed in rats after cerebral contusion produced by our modified fluid percussion device. Expression of bFGF mRNA increased significantly on the second day after trauma. A possible role of bFGF is functioning to protect the critical neurons from secondary neural damage in cerebral contusion.

Actins↗
PubMed1994

Effects of chromium picolinate supplementation on body composition, strength, and urinary chromium loss in football players.

The effects of 9 weeks of daily chromium supplementation (200 microgram Cr as picolinate) were investigated in a double-blind design in football players during spring training. Testing was done pre-, mid-, and postsupplementation on the following criterion measures: urinary chromium excretion, girth and skinfold measures, percent body fat and lean body mass, and isometric and dynamic strength. With the exception of 2 variables (of 65 variables analyzed), no significant group by trials interactions were found (based on a repeated measures ANOVA). The two exceptions were unrelated and inconsequential. For 27 of the 38 subjects, average urinary chromium loss at pre was 0.36 microgram/24 hr, whereas it was undetectable (<0.1 microgram/24 hr) for 10 subjects and excessive in 1 subject (2.4 micrograms/24 hr). Subjects receiving chromium supplements demonstrated urinary chromium losses five times greater than those in the placebo group at mid and post. Chromium picolinate supplementation was ineffective in bringing about changes in body composition or strength during a program of intensive weight-lifting training.

Adult↗
PubMed1994

Tumor necrosis factor-alpha mRNA expression in lipopolysaccharide-stimulated rat kidney. Chronological analysis of localization.

To study the time course of lipopolysaccharide-induced production of tumor necrosis factor-alpha (TNF-alpha) in the kidney, we utilized a highly sensitive non-radioisotopic in situ hybridization with 1-nm gold-conjugated anti-digoxigenin for localization of TNF-alpha mRNA expression after lipopolysaccharide administration. TNF-alpha mRNA expression localized by in situ hybridization showed a peak increment in proximal tubular epithelial cells and glomeruli at 2 hours and returned to almost normal levels at 6 hours. The intensity of the signal was much stronger in proximal tubules than in glomeruli. These findings were confirmed by the demonstration of similar kinetics in the increase of TNF-alpha message, measured by using amplification of the third and fourth exons of TNF-alpha gene by reverse transcription-polymerase chain reaction of microdissected proximal tubular segments and isolated glomeruli. Reverse transcription-polymerase chain reaction of cultured rat mesangial and glomerular epithelial cells demonstrated that mesangial cells, not glomerular epithelial cells, were responsible for the observed glomerular signals.

Animals↗
PubMed1993

Isolation and characterization of a thiamin pyrophosphokinase gene, THI80, from Saccharomyces cerevisiae.

The thi80 mutant of Saccharomyces cerevisiae (Nishimura, H., Kawasaki, Y., Nosaka, K., Kaneko, Y., and Iwashima, A. (1991) J. Bacteriol. 173, 2716-2719) shows markedly reduced activity of thiamin pyrophosphokinase (TPK; EC 2.7.6.2). We have isolated a DNA fragment carrying the THI80 gene from a yeast genomic library by its ability to complement constitutive synthesis of the thiamin-repressible acid phosphatase, encoded by the PHO3 gene, of thi80 mutant cells. On the other hand, the thi80 locus was found to be located 3.3 centimorgans proximal to the smp3 locus on the right arm of chromosome XV by genetic mapping analysis, and one more fragment bearing the THI80 gene trailing SMP3 gene was obtained by the plasmid eviction method. The nucleotide sequence of the overlapped region between the two isolated DNAs contained an open reading frame of 957 base pairs, encoding a 319-amino acid polypeptide with a calculated molecular weight of 36,616. When the intact THI80 open reading frame was expressed as a fusion protein carrying three vector-encoded amino acids at its N terminus in Escherichia coli lacking TPK, marked TPK activity was detected in the procaryotic cells, proving that the THI80 gene of S. cerevisiae encodes a structural gene of TPK. A gene disruption experiment demonstrated that the THI80 gene was essential for growth, and therefore, revealed that TPK is the only enzyme capable of synthesizing thiamin pyrophosphate in yeast. Studies of Northern blot analysis and the enzyme assay demonstrated that the THI80 gene expression is regulated mainly at the mRNA level by the intracellular thiamin pyrophosphate and requires the positive regulatory factors encoded by THI2 and THI3 genes. However, unlike thiamin-repressible acid phosphatase and the enzymes involved in thiamin synthesis of S. cerevisiae, TPK was found to be expressed constitutively at a low level and incompletely repressed by exogenous thiamin.

Amino Acid Sequence↗
PubMed1993

Inhibitory effect of diltiazem on diazepam metabolism in the mouse hepatic microsomes.

In order to elucidate the drug interaction between diltiazem and diazepam, the effect of diltiazem on the N-demethylation of diazepam in the mouse hepatic microsomes was investigated. Kinetic study showed that diltiazem noncompetitively inhibited the N-demethylation of diazepam with inhibition constant (Ki) value of 247.8 microM, indicating that diltiazem exhibits an inhibitory effect on the hepatic oxidative metabolism of diazepam. It was therefore suggested that diltiazem may impair the metabolism of diazepam in vivo.

Animals↗
PubMed1993

Shunt nephritis: efficacy of an antibiotic trial for clinical diagnosis.

Coagulase negative staphylococcus, a normal skin flora, is especially nosopoietic under shunt management, because coagulase negative staphylococcus sometimes forms a biofilm around itself at catheter tips in vivo, which shields the organism from the effects of antibiotics. But it is difficult to distinguish this pathogen from a possible confounding contamination of a blood culture. In this article, we report a case, and discuss how a patient with suspected shunt nephritis should be examined and treated. In addition, to further histological and prognostic interpretation, we review the previously reported cases of shunt nephritis in Japanese adults.

Adult↗