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Biomedical subjects

K Nosaka

Publications and source records attributed to K Nosaka.

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

An antisense EGFR oligodeoxynucleotide enveloped in Lipofectin induces growth inhibition in human malignant gliomas in vitro.

Epidermal growth factor receptor (EGFR) plays an important role in the progression of malignancy in gliomas. We studied the growth inhibition of the malignant glioma cell lines using an antisense EGFR oligodeoxynucleotide enveloped with Lipofectin. At a concentration of 5 microM of the antisense EGFR oligodeoxynucleotide enveloped with Lipofectin, the proliferation of three malignant glioma cell lines was significantly inhibited (p < 0.05) compared with that of the cells exposed to 5 microM sense EGFR oligodeoxynucleotide. The activity of the tyrosine kinase and the DNA synthesis was also significantly suppressed (p < 0.05). These findings show that the antisense EGFR oligodeoxynucleotide enveloped with Lipofectin has a possibility to become a useful gene therapy against malignant gliomas.

Brain Neoplasms↗
PubMed1998

A Brassica cDNA clone encoding a bifunctional hydroxymethylpyrimidine kinase/thiamin-phosphate pyrophosphorylase involved in thiamin biosynthesis.

We report the characterization of a Brassica napus cDNA clone (pBTHI) encoding a protein (BTHI) with two enzymatic activities in the thiamin biosynthetic pathway, thiamin-phosphate pyrophosphorylase (TMP-PPase) and 2-methyl-4-amino-5-hydroxymethylpyrimidine-monophosphate kinase (HMP-P kinase). The cDNA clone was isolated by a novel functional complementation strategy employing an Escherichia coli mutant deficient in the TMP-PPase activity. A biochemical assay showed the clone to confer recovery of TMP-PPase activity in the E. coli mutant strain. The cDNA clone is 1746 bp long and contains an open reading frame encoding a peptide of 524 amino acids. The C-terminal part of BTH1 showed 53% and 59% sequence similarity to the N-terminal TMP-PPase region of the bifunctional yeast proteins Saccharomyces THI6 and Schizosaccharomyces pombe THI4, respectively. The N-terminal part of BTH1 showed 58% sequence similarity to HMP-P kinase of Salmonella typhimurium. The cDNA clone functionally complemented the S. typhimurium and E. coli thiD mutants deficient in the HMP-P kinase activity. These results show that the clone encodes a bifunctional protein with TMP-PPase at the C-terminus and HMP-P kinase at the N-terminus. This is in contrast to the yeast bifunctional proteins that encode TMP-PPase at the N-terminus and 4-methyl-5-(2-hydroxyethyl)thiazole kinase at the C-terminus. Expression of the BTH1 gene is negatively regulated by thiamin, as in the cases for the thiamin biosynthetic genes of microorganisms. This is the first report of a plant thiamin biosynthetic gene on which a specific biochemical activity is assigned. The Brassica BTH1 gene may correspond to the Arabidopsis TH-1 gene.

Alkyl and Aryl Transferases↗
PubMed1997

Mutation thi81 causing a deficiency in the signal transduction of thiamine pyrophosphate in Saccharomyces cerevisiae.

We isolated a strain carrying a recessive constitutive mutation (thi81) for the expression of thiamine metabolism in Saccharomyces cerevisiae. The thi81 mutant exhibits significant thiamine transport, thiamine-repressible acid phosphatase (T-rAPase) activities and significant activities of enzymes involved in thiamine biosynthesis which are repressed in the wild-type strain in medium supplemented with thiamine (2 x 10(-7) M). The thi81 mutant exhibited the same level of thiamine pyrophosphokinase activity and intracellular thiamine pyrophosphate concentration as the wild-type strain in medium supplemented with exogenous thiamine. The mutant strain constitutively produced PHO3 mRNA encoding T-rAPase in medium supplemented with thiamine. These results suggest that the thi81 mutant lacks a negative factor involved in the regulation of the genes encoding proteins involved in yeast thiamine metabolism.

Acid Phosphatase↗
PubMed1997

Isolation and characterization of a thiamin transport gene, THI10, from Saccharomyces cerevisiae.

We isolated a thiamin transporter gene, THI10, from a genomic library of Saccharomyces cerevisiae by the complementation of a yeast mutant defective in thiamin transport activity. The THI10 gene contained an open reading frame of 1,794 base pairs encoding a 598-amino acid polypeptide with a calculated molecular weight of 66, 903. The nucleotide sequence of THI10 is completely identical to that of an anonymous DNA (open reading frame L8083.2) mapped to chromosome XII; two other genes (open reading frames YOR071c and YOR192c) in chromosome XV are extremely similar to THI10. Moreover, the THI10 gene product showed significant sequence homology with yeast allantoin and uracil transporters. Hydropathy profile suggested that THI10 product is highly hydrophobic and contains many transmembrane regions. Gene disruption of the THI10 locus completely abolished the thiamin transport activity and thiamin binding activity in yeast plasma membrane fraction. Both the transport and thiamin binding activities were restored in the disrupted cells when the THI10 open reading frame was expressed by yeast GAL1 promoter, suggesting that the THI10 gene encodes for the thiamin transport carrier protein. Northern blot analysis demonstrated that THI10 gene expression is regulated at the mRNA level by intracellular thiamin pyrophosphate and that it requires a positive regulatory factor encoded by THI3 gene.

Amino Acid Sequence↗
PubMed1997

An adenosine deaminase inhibitor prevents puromycin aminonucleoside nephrotoxicity.

Puromycin aminonucleoside (PAN) toxicity was totally inhibited in the rat in vivo and in cultured glomerular epithelial cells (GECs) in vitro using the adenosine deaminase (ADA) inhibitor, 2'-deoxycoformycin (DCF). DCF completely inhibited ADA activity in glomeruli and protected against the development of PAN nephrosis; the 24-h urinary protein excretion of treated rats compared with controls (PAN rats) 9 days after PAN injection was 16 +/- 2 mg and 524 +/- 55 mg, respectively (p < .01). Morphological examination also demonstrated that the glomerular epithelial cells were protected against PAN-induced damage. Furthermore, when DCF was added to the first passage of GECs simultaneously with PAN, the adenosine triphosphate contents of remnant GECs on culture substrata increased in a dose-dependent manner, and PA toxicity was completely inhibited by 10(-4) M DCF. The order of ADA activity in glomeruli from various species was as follows: rat > monkey > guinea pig > dog > rabbit > mouse. High activity of ADA in the glomerulus was limited to species in which PAN induced nephrosis. Additionally, DCF increased glomerular cyclic AMP contents, resulting from enhanced adenosine accumulation in the pericellular space. These results indicate that the pathogenesis of PAN toxicity is closely related to adenosine metabolism and that ADA plays a key role in this model. Furthermore, we speculate that DCF contributes to the inhibition of reactive oxygen metabolites by decreasing the substrate of xanthine oxidase and/or increasing pericellular adenosine accumulation.

Adenosine↗
PubMed1997

A rare case of laryngeal myxoma.

We report a rare case of laryngeal myxoma in a 57-year-old Japanese man. Except for a five-year history of gradually progressive hoarseness, he had been in good health. Video-stroboscopic examination revealed a solid mass in the anterior third of the right vocal fold. Phonosurgery performed with a microscope showed that the mass was encapsulated and located between the epithelium and vocal fold ligaments of the right vocal fold. This hard, elastic mass which measured 7 mm in diameter, was diagnosed as a myxoma. Only three cases of myxoma of the larynx have been reported in the English literature, with only one other case involving the vocal fold.

Hoarseness↗
PubMed1997

Influence of previous concentric exercise on eccentric exercise-induced muscle damage.

This study investigated whether a fatiguing concentric exercise performed immediately before eccentric exercise would exacerbate eccentric exercise-induced muscle damage. One arm of nine female subjects (mean +/- s: 23.3 +/- 6.7 years) performed 12 maximal eccentric actions of the elbow flexors (ECC), and the other arm performed 100 repetitions of isokinetic concentric actions of the elbow flexors followed by the same eccentric exercise (CON-ECC). The two exercise regimens (ECC and CON-ECC) were separated by 2 weeks and presented in a counterbalanced order. Changes in muscle soreness level, maximal isometric force generation, relaxed and flexed elbow joint angle, upper arm circumference and plasma creatine kinase activity were compared between the ECC and CON-ECC conditions. All measures changed significantly after both ECC and CON-ECC; however, there were significant differences in the changes between the conditions. A lower level of soreness, a faster recovery of maximal isometric force generation, a smaller decrease in relaxed elbow joint angle and a smaller increase in upper arm circumference and creatine kinase activity were evident after the CON-ECC condition compared to the ECC condition. Thus, it would seem that muscle damage was attenuated by performance of previous concentric exercise. An additional experiment using a different group of subjects (n = 5) showed that warm-up exercise before the eccentric exercise also attenuated eccentric exercise-induced muscle damage.

Adult↗
PubMed1997

cAMP mediates homologous downregulation of PAF receptor mRNA expression in mesangial cells.

To clarify the molecular mechanism and significance of homologous desensitization of platelet-activating factor (PAF) signaling, we examined the effect of PAF on PAF receptor mRNA expression in rat mesangial cells by Northern blot analysis. Treatment of the cells with PAF (10(-7)-10(-8) M) reduced the expression of PAF receptor mRNA in 1 h, and this reduction was recovered by pretreatment of mesangial cells with a specific PAF receptor antagonist, WEB-2086 (10(-6) M), or a cyclooxygenase inhibitor, indomethacin (10(-6) M), for 10 min. PAF-stimulated prostaglandin E2 (PGE2) and adenosine 3',5'-cyclic monophosphate (cAMP) formation was measured by radioimmunoassays specific for each substance. Reduction of PAF receptor mRNA expression was mimicked by treatment of the cells with PGE2 (10(-6) M) or dibutyryl-cAMP (10(-3) M), a cell-permeable analog of cAMP. These results, taken together, suggest that PAF receptor mRNA expression is downregulated by exposure to PAF in cultured mesangial cells. This homologous downregulation is mediated by cAMP production through PGE2 synthesis.

Animals↗
PubMed1997

Long-term effects of LTB4 antagonist on lipid induced renal injury.

Glomerular infiltration of macrophages is a characteristic alteration of renal histopathology in hyperlipidemic renal injury. Each macrophage has two key enzymes to synthesize LTB4:5-lipoxygenase and LTA4 hydrolase. In this study we examined the long-term effects of LTB4 antagonist on real function and histopathology of spontaneously hypercholesterolemic (SHC) rat, which is model of hyperlipidemic renal injury, to see if the LTB4 antagonist could reduce the progression of renal damage. Spontaneously hypercholesterolemic rats fed a normal diet (C) developed end-stage renal failure in 26 weeks, while those fed a diet supplemented with LTB4 antagonist (E) showed normal renal function, and mild histopathological alterations (SCr: C, 1.4 +/- 0.3; E, 0.6 +/- 0.1 mg/dl, P < 0.03) without statistical differences in serum total cholesterol, body weight and blood pressure between two groups. These results suggest that LTB4 plays an important role in progression of hyperlipidemic renal injury.

Animals↗
PubMed1996

Creatine kinase release from regenerated muscles after eccentric contractions in rats.

The purpose of this study was to test the hypothesis that an increase in plasma creatine kinase (CK) activity after eccentric contractions (ECC) would be attenuated in regenerated muscle fibres. Adult male Wistar rats (aged 12-14 weeks) were randomly assigned to a treatment group (n = 14) or a control group (n = 10). In the treatment group, 1.2% barium chloride solution (BaCl2) was injected into the tibialis anterior (TA) and extensor digitorum longus (EDL) muscles to induce degeneration and subsequent regeneration. The same amount of isotonic saline solution was injected into TA and EDL for the control group. Histological observation showed that approximately 50% of the fibres in the transverse sections of both muscles underwent necrosis 2 days after BaCl2 injection. The CK activity increased about tenfold at 2-4 h after BaCl2 injection. At 4 weeks after BaCl2 injection, when the regeneration process was almost complete, the TA and EDL of anaesthetized rats from both groups were subjected to ECC in which maximal dorsiflexion was caused by nerve electrical stimulation and the flexed foot was forcibly extended by a lever arm connected to a motor. This action was performed in 2 sets of 30 repetitions. Maximal isometric torque of the dorsiflexors decreased to about 15% (P < 0.01) of the pre-ECC value immediately after the exercise. Blood samples were collected before and 2, 4, 12, 24, 48 h after ECC. The CK activity increased significantly (P < 0.01) and peaked at 2-4 h after ECC, and there was no significant difference in the amount of CK increase between the treatment [1007 (SEM 120) IU.l-1] and the control [1064 (SEM 120) IU.l-1] group. Contrary to the hypothesis, CK release after ECC was not attenuated in muscle regenerated from BaCl2-induced myonecrosis.

Animals↗
PubMed1996

Effect of adenosine on phorbol myristate acetate induced-reactive oxygen metabolite production in cultured mesangial cells.

Cultured rat mesangial cells produced chemiluminescence in response to phorbol myristate acetate. Because 90% of this chemiluminescence was suppressed by 10 mU/ml superoxide dismutase, reactive oxygen metabolites are most likely involved in the chemiluminescence reaction. To clarify the role of cyclic AMP in the regulation of reactive oxygen metabolites production in cultured mesangial cells, we studied the effects of adenosine, an adenosine analog (2-chloroadenosine), and forskolin on phorbol myristate acetate-induced chemiluminescence. Exogenous adenosine suppressed the production of reactive oxygen metabolites in a dose-dependent manner (maximum at 1 mM adenosine: 70.6 +/- 3.2% of control). Lower concentration of 2-chloroadenosine (maximum at 100 mu M 2-chloroadenosine: 63.2 +/- 2.1% of control) and forskolin (maximum at 200 mu M forskolin: 53.4 +/- 2.6% of control) also significantly suppressed the production of reactive oxygen metabolites. In addition, adenosine analogs increased intracellular cyclic AMP in a dose-dependent manner in the order: 5'-N-ethylcarboxamidoadenosine>2-chloroadenosine>N6-cyclohexyladenosine. These results are in accordance with the probability that exogenous adenosine, by increasing intracellular cyclic AMP via the A2 receptor, inhibits the production of reactive oxygen metabolites through direct protein kinase C activation induced by phorbol myristate acetate in cultured rat mesangial cells.

2-Chloroadenosine↗
PubMed1996

Urinary excretion of pyridinium cross-links of collagen in infancy.

This cross-sectional study evaluated urinary excretion of pyridinium cross-links of collagen, specific markers of ongoing bone resorption, in infants aged 1 week to 7 months and examined the relationship between urinary cross-links and individual renal function. Spot urines from a total of 100 infants were analyzed. The collagen cross-links, pyridinoline (Pyd) and deoxypyridinoline (D-Pyd), were assayed by fluorescence detection after high-performance liquid chromatography (HPLC). Beta2-Microglobulin (beta2M), an index of renal tubular function, was determined by radioimmunoassay. In healthy term infants, urinary collagen cross-links were several times higher than the reported data for older children, with peak values seen at 1 month of age. Excretion of Pyd and D-Pyd was also markedly elevated in 1-month-old preterm infants, despite poor somatic growth. Such high excretion of collagen cross-links probably reflects the state of accelerated bone turnover in infancy. The postnatal change in the cross-links was different from that in urinary beta2M, and the values obtained did not correlate with beta2M in either term or preterm infants. These results indicate that cross-link excretion is not influenced directly by individual renal function.

Amino Acids↗
PubMed1996

Variability in serum creatine kinase response after eccentric exercise of the elbow flexors.

There is a large inter-subject variability in serum creatine kinase (CK) response after eccentric exercise. This study examined and compared the variability of CK activity, other serum protein increases (aspartate aminotransferase, alanine aminotransferase, lactate dehydrogenase, aldolase, myoglobin),changes in muscle damage indicators (maximal isometric force: MIF, relaxed and flexed elbow joint angle: RANG and FANG, circumference: CIR, and muscle soreness level: SOR), and changes in magnetic resonance (MR) images. Ten male subjects (21.7 +/- 1.6 yrs) performed 24 maximal eccentric actions of the elbow flexors, and measurements except MR images were taken immediately before and after, and for 10 days after exercise. MR images were taken 7 days after exercise. A large variability in peak CK response (236 - 25,244 IU.I(-1) was found among subjects. Spearman rank-order correlation coefficients (r) revealed significant correlations of peak CK with peak serum protein levels (r = 0.79-0.95), peak changes in MIF (r = 0.73-0.79), RANG (r = 0.69), and CIR (r = 0.91). The higher the peak CK levels, the more profound the abnormality in the MR images and the larger the changes in MR signal intensity (r = 0.90-0.94). It is concluded that the large variability in CK response after exercise seems to be related to the variability in exercise-induced muscle damage.

Adult↗
PubMed1996

Changes in indicators of inflammation after eccentric exercise of the elbow flexors.

This study examined muscle swelling and changes in inflammatory markers in the blood following eccentric exercise-induced muscle damage. Subjects (N = 14) who had not been involved in a resistance training program performed 24 maximal eccentric actions of the elbow flexors. Muscle swelling was assessed by measures of the upper arm circumference (CIR), ultrasonography (USG), and magnetic resonance imaging (MRI). Plasma concentrations of interleukin-1 alpha, interleukin-1 beta, interleukin-2, interleukin-6, tumor necrosis factor-alpha, and plasma levels of C-reactive protein, cortisol, and zinc were analyzed. Established indicators of muscle damage (maximal isometric force, range of motion, muscle soreness, and plasma creatine kinase, aspartate aminotransferase, and lactate dehydrogenase activities) were also measured. All measures, including CIR and USG, except for MRI, were assessed immediately before and after and for 5 d post-exercise. MRI was taken at pre- and 1, 3, 6, 10, 23, 31, and 58 d post-exercise. All muscle damage indicators changed significantly after exercise. A large increase in CIR (> 20 mm) was found 4-5 d after exercise, and this coincided with USG, showing an increase in muscle thickness. The echointensity of USG increased with the enlargement of the elbow flexors. MRI displayed enlargement of the biceps brachii and brachialis cross-sectional area that started at 1 d, and lasted until 23 d, post-exercise. The most profound increase in the enlargement and signal intensity of the MRI was found 3 or 6 d after exercise. However, none of the plasma levels of inflammatory makers showed significant muscle swelling, which is indicative of muscle edema, but the inflammatory responses after exercise appear to be different from those accompanying infection or tissue injury.

Aspartate Aminotransferases↗