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Biomedical subjects

Y Uchida

Publications and source records attributed to Y Uchida.

At least 451 records · Page 25Linked to original sources
PubMed1991

Increased phosphorylation of DNA topoisomerase II in etoposide-resistant mutants of human cancer KB cells.

We have isolated two etoposide (VP16)-resistant cell lines, KB/VP-1 and KB/VP-2, from human cancer KB cells after stepwise exposure to increasing doses of VP16. KB/VP-1 and KB/VP-2 showed 30- and 50-fold higher resistance to VP16 and also 20- and 30-fold higher resistance to teniposide than the parent cell line. Furthermore, both resistant cell lines showed more than 2-fold cross-resistance to Adriamycin and daunomycin than KB cells. The levels of accumulation and outward transport of radioactive VP16 were similar in KB/VP-1, KB/VP-2, and KB. The activity of nuclear extracts of DNA topoisomerase II for both KB/VP-1 and KB/VP-2 assayed by decatenation of kinetoplast DNA was consistently similar to that of KB. However, in both immunoblot assay with specific anti-topoisomerase II antibody and Northern blot analysis with specific human DNA topoisomerase II complementary DNA, cellular levels of topoisomerase II in both resistant cell lines were less than one-tenth the level in KB. The cellular levels of DNA topoisomerase I, however, were similar between the mutants and their parent. A quantitative precipitation assay of covalent DNA-topoisomerase II complexes showed greatly reduced VP16-induced cleavages of 3'-32P-DNA by nuclear extracts of KB/VP-1 or KB/VP-2 cells in comparison with KB cells. The relative specific phosphorylation of DNA topoisomerase II was about 14- to 18-fold higher in the mutants than in the parental cells. Phosphoamino acid analysis of DNA topoisomerase II showed that serine was the phosphorylated amino acid in all three cell lines, KB, KB/VP-1, and KB/VP-2. These data suggest that reduced expression of DNA-topoisomerase II might account for the acquired VP16 resistance and reduced VP16-induced cleavages of DNA-topoisomerase II complexes in both VP16-resistant variants.

Carcinoma, Squamous Cell↗
PubMed1991

Application of the tryptophanase promoter to high expression of the tryptophan synthase gene in Escherichia coli.

The application of an inducible regulation system using the tryptophanase operon promoter (TPase promoter; Ptna) was examined for its high expression of the tryptophan synthase (TS) gene in Escherichia coli. The main problem in the application of Ptna for industrial purposes is catabolite repression by glucose, since glucose is the most abundant carbon source. However, this problem could be avoided by changing glucose to an organic acid, such as succinate, fumarate, malate and acetate, in the course of cultivation after glucose initially added was completely consumed. Under these conditions, L-tryptophan was also used to induce tryptophan synthase. Thus, the specific activity of TS in E. coli strain no. 168 harbouring pBR322F-Ptna TS was increased 500-fold compared to that of the cultured host strain. About 1 mol L-tryptophan/l reaction mixture was formed from indole and L-serine at 37 degrees C for 3.5 h.

Carbon↗
PubMed1991

Brain stem auditory-evoked potentials in meningomyelocele. Natural history of Chiari II malformations.

Brain stem auditory-evoked potentials (BAEPs) were recorded in 30 patients with meningomyelocele and shunted hydrocephalus ranging in age from birth to 33 years. Twenty-two of them had Chiari II malformation, one of which was symptomatic. In 22 cases, including 15 with Chiari II malformation, BAEPs were recorded repeatedly after periods ranging from 18 months to 7 years. The results were as follows: (1) III-V interpeak latency (IPL) decreased progressively from prolonged to the normal range with growth until 25 years of age; (2) I-III IPL tended to prolong gradually from the normal range; (3) these findings may indicate that the natural history of Chiari II malformation is delayed maturation of the brain stem and intensification in the elongation and stretching of the hindbrain and lower cranial nerves.

Adolescent↗
PubMed1991

2-Acetylfuran, a confounder in urinalysis for 2,5-hexanedione as an n-hexane exposure indicator.

The apparent amount of 2,5-hexanedione, a biomarker of n-hexane expsoure in occupational health, in the urine of both exposed and non-exposed subjects varied not only as a function of the pH at which the urine sample was hydrolyzed but also depending on the capillary column used for gas chromatographic (GC) analysis of the urinary hydrolyzates after extraction with dichloromethane. The formation of a compound, identified by gas chromatography-mass spectrometry (GC-MS) as 2-acetylfuran, following acid hydrolysis was a major cause of confounding effects. This compound was hardly separated from 2.5-hexanedione on a capillary column such as DB-WAX, whereas separation could be achieved on a DB-1 capillary column. 2-Acetylfuran was formed when a urine sample was heated at a pH of less than 2 for hydrolysis, and the amount detected in urine did not differ between exposed and non-exposed subjects, indicating that the formation of 2-acetylfuran is independent of n-hexane exposure. When urinary hydrolysis is used, hydrolysis at a pH of less than 0.5, extraction with dichloromethane, and GC analysis on a non-polar capillary column are proposed to be the best analytical conditions for 2,5-hexanedione analysis in biological monitoring of exposure to n-hexane.

Confounding Factors, Epidemiologic↗
PubMed1991

Methanol in urine as a biological indicator of occupational exposure to methanol vapor.

The exposure-excretion relationship and possible health effects of exposure to methanol vapor were studied in 33 exposed workers during the second half of 2 working weeks. Urinary methanol concentrations were also determined in 91 nonexposed subjects. The geometric mean value for methanol in urine samples from the latter was less than 2 mg/l (95% upper limit of normal, less than 5 mg/l) when log-normal distribution was assumed. Among the exposed workers, the methanol level in urine samples collected prior to the work shift exceeded the 95% upper limit of normal. The time-weighted average intensity of exposure to methanol vapor was measured using personal sampling devices (in which water severed as an absorbent) in 48 cases of methanol exposure (i.e., 2 of the 33 exposed workers failed to provide urine samples, whereas 17 subjects were examined twice). Methanol concentrations in urine were determined in samples collected at the end of the shift from the 48 exposed cases as well as from 30 nonexposed controls. There was a significant correlation between the exposure to methanol vapor at concentrations of up to 5,500 ppm and the levels of methanol measured in the shift-end urine samples. The calculation indicated that a mean level of 42 mg methanol/l urine (95% confidence range, 26-60 mg/kg) was excreted in the shift-end urine sample following 8 h exposure to methanol at 200 ppm (the current occupational exposure limit). Dimmed vision and nasal irritation were among the most frequent symptoms complained during work. Three cases showing clinical signs of borderline significance were identified.

Adult↗
PubMed1991

Dose-dependent increase in 2,5-hexanedione in the urine of workers exposed to n-hexane.

The concentrations of 2,5-hexanedione (2,5-HD), an n-hexane metabolite, and 2-acetylfuran (2-AF) were measured in urine samples from 123 workers who had predominantly been exposed to n-hexane vapor and 53 workers who had experienced no exposure to solvents. The time-weighted average intensity of exposure to n-hexane vapor was determined by a diffusive sampling method. For biological monitoring of exposure, urine samples were collected late in the afternoon during the second half of a working week and were analyzed in the presence and absence of acid hydrolysis (at pH less than 0.5) for 2,5-HD and 2-AF by gas chromatography on a nonpolar capillary DB-1 column. The urinary 2,5-HD concentration increased as a linear function of the intensity of exposure to n-hexane, showing a correlation coefficient of 0.64-0.77 after acid hydrolysis and that of 0.73-0.83 in the absence of hydrolysis, depending on the correction for urinary density (P less than 0.01 in all cases, with no improvement in the coefficient occurring after the corrections). In contrast, 2-AF levels were independent of n-hexane exposure. The geometric mean 2,5-HD concentration in urine samples from 53 nonexposed men was 0.26 mg/l as observed (i.e., with no correction), 0.19 mg/l after correction for a urinary specific gravity of 1.016, and 0.23 mg/g creatinine after correction for creatinine concentration, and the geometric standard deviation was approximately 2.

Chromatography, Gas↗
PubMed1991

Urinary methylhippuric acid isomer levels after occupational exposure to a xylene mixture.

The quantitative relationship between exposure to xylene vapor and urinary excretion of methylhippuric acid (MHA) isomers were studied in the second half of a working week. The participants in the study were 121 male workers engaged in dip-coating of metal parts who were predominantly exposed to three xylene isomers. The intensity of exposure measured by diffusive sampling during an 8-h shift was such that the geometric mean vapor concentration was 3.8 ppm for xylenes (0.8 ppm for o-xylene, 2.1 ppm for m-xylene, and 0.9 ppm for p-xylene), 0.8 ppm for toluene, and 0.9 ppm for ethylbenzene. Urine samples were collected at the end of the shift and analyzed for metabolities by HPLC. The statistical analysis showed that there is a linear relationship between the intensity of exposure to xylenes and the concentration of MHA in urine, that the regression line passes very close to the origin, and that the increment in observed (i.e., noncorrected) MHA concentrations as a function of increasing xylene concentration was 17.8 mg x l-1 ppm-1. Further examination on the basis on individual xylene isomers showed that the slopes of the regression lines for o- and m-isomers were similar (i.e., 17.1 and 16.6 mg l-1 ppm-1, respectively), whereas that for p-xylene was larger (21.3 mg l-1 ppm-1).

Air Pollutants, Occupational↗
PubMed1991

Aortic valve replacement and splenectomy in a patient with chronic idiopathic thrombocytopenic purpura--preoperative management with high-dose gamma-globulin.

We report the management of a patient with chronic idiopathic thrombocytopenic purpura and severe aortic valvular disease. Preoperative intravenous high-dose gamma-globulin administration was employed, and aortic valve replacement combined with splenectomy were performed during the same operation. The platelet count at admission was 34,000/mm3 and increased to 146,000/mm3 after the gamma-globulin therapy. Platelet transfusion at the end of the cardiopulmonary bypass was considered no longer necessary in the postoperative period, because the platelet count increased quickly after the procedure. The postoperative course was uneventful. We believe that open heart surgery and splenectomy can successfully be performed simultaneously in a patient with chronic idiopathic thrombocytopenic purpura treated with high-dose gamma-globulin therapy.

Aortic Valve Insufficiency↗
PubMed1991

Percutaneous fiberoptic angioscopy of the cardiac valves.

The feasibility of percutaneous translumial angioscopy of the cardiac valves was examined in eight patients with and in 11 patients without valvular disease. In eight of these patients, a guiding balloon catheter (9F) was introduced into the aortic root, a guide wire (0.014 or 0.025 inch) was introduced through the catheter into the left ventricle to prevent dislocation of the catheter, and a fiberscope (1.6 or 4.6F) was advanced to the distal tip of the catheter. The balloon was then inflated with carbon dioxide and was manipulated against the aortic valve; a body temperature heparinized saline was infused through the catheter for observation. Similarly, the balloon catheter was advanced transseptally into the left atrium for observation of the mitral valve in four patients. Also, the balloon catheter was advanced through the right femoral vein into the right atrium for observation of the tricupid valve in three patients. In patients with a normal aortic valve, the aortic cusp surface was smooth and white and the edges were sharp. They opened briskly during systole and coapted each other completely during diastole. In rheumatic aortic regurgitation, the cuspus were thick and blunt and their coaptation insufficiency was observed during diastole. In a patient with rheumatic AS, globular and yellow cusps were observed. Mitral valve leaflets were smooth and white in a patients without mitral valvular disease, while the leaflets were yellow, thick and irregular, and blood regurgitation from the left ventricle into the left atrium could be observed in two patients with rheumatic MSR. The process of opening and closure of a tricuspid valve was also observed in three patients without tricuspid valvular disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1991

Peripheral nerve palsy associated with congenital constriction band syndrome.

Of 21 patients with congenital constriction band syndrome treated in our clinic from 1967 to 1988, four had constriction bands proximal to the wrist. Three of these also had a peripheral nerve palsy. Late surgical decompression does not help but early diagnosis, using electrodiagnosis methods, and neurolysis or nerve grafting as soon as possible may improve nerve function.

Amniotic Band Syndrome↗
PubMed1991

A personal diffusive sampler for occupational acetone vapor exposure monitoring.

A commercially produced badge-type personal sampler, with water as absorbent and originally designed for monitoring of formaldehyde, was investigated for possible application to monitoring of occupational exposure to acetone, one of the hydrophilic solvents which cannot be monitored so far with activated carbon cloth-equipped diffusive samplers. Under the experimental condition of exposure at constant acetone concentration, the amount of acetone absorbed was proportional to the acetone exposure concentration up to 1500 ppm and duration of exposure for up to 8 h. Inter-sampler variation became wider, however, at 8 h of exposure to 1500 ppm acetone. Loss of acetone in the absorbent water due to spontaneous desorption became significant at 6 h after acetone impregnation of absorbent water. In practice, therefore, limitation of the duration of exposure up to 4 h is recommended.

Absorption↗
PubMed1991

Exposure of 1,1,1-trichloroethane and dose-related excretion of metabolites in urine of printing workers.

The quantitative relationship between the time-weighted average exposure by inhalation to 1,1,1-trichloroethane and excretion of metabolites in urine at the end of a work shift was investigated in 48 male printing workers exposed to the solvent at levels below 65 ppm. Male control subjects, 10 in all, were also investigated. Statistical analysis showed that there is a linear relationship between the two exposure indicators, suggesting that occupational exposure to 1,1,1-trichloroethane can be bio-monitored by means of urinalysis for either total trichloro-compounds or trichloroacetic acid. The correlation coefficient was higher for total trichloro-compounds (r = 0.86-0.89 depending on correction for urine density) than trichloroacetic acid (r = 0.50-0.71), which suggests that the former is a better indicator of exposure to 1,1,1-trichloroethane than the latter. The calculations based on the present study suggest that, at the end of the shift, only less than 2% of 1,1,1-trichloroethane absorbed will be excreted as metabolites in urine.

Air Pollutants, Occupational↗
PubMed1991

The growth inhibitory factor that is deficient in the Alzheimer's disease brain is a 68 amino acid metallothionein-like protein.

We have purified and characterized the growth inhibitory factor (GIF) that is abundant in the normal human brain, but greatly reduced in the Alzheimer's disease (AD) brain. GIF inhibited survival and neurite formation of cortical neurons in vitro. Purified GIF is a 68 amino acid small protein, and its amino acid sequence is 70% identical to that of human metallothionein II with a 1 amino acid insert and a unique 6 amino acid insert in the NH2-terminal and the COOH-terminal portions, respectively. The antibodies to the unique sequence of GIF revealed a distinct subset of astrocytes in the gray matter that appears to be closely associated with neuronal perikarya and dendrites. In the AD cortex, the number of GIF-positive astrocytes was drastically reduced, suggesting that GIF is down-regulated in the subset of astrocytes during AD.

Aged↗
PubMed1991

Enhancement of keratin synthesis induced by lipokeratinogenoside, N-(O-linoleoyl)-omega-hydroxy fatty acyl sphingosyl glucose, in association with alteration of the intracellular Ca(2+)-content and protein kinase in cultured keratinocytes (FRSK).

Lipokeratinogenoside [N-(O-linoleoyl)-omega-hydroxy fatty acyl sphingosyl beta-glucose] is one of the epidermosides which were found to be glycosphingolipids characteristic of the epidermis of mammalian skin. On the addition of lipokeratinogenoside to cultured rat keratinocytes (FRSK), the amount of keratin in the cells increased, 48 and 144 h after cultivation, to 1.4 to 1.8 times higher than that without the addition of lipokeratinogenoside, and the number of cornified envelopes also significantly increased on cultivation of the cells with lipokeratinogenoside. Immunohistochemical staining with anti-keratin antibody revealed that the cells cultivated with lipokeratinogenoside were densely covered with keratin in distinct contrast to the control cells. The same enhanced syntheses of keratin and cornified envelopes were observed on cultivation in the presence of TPA, which has been shown to elevate the intracellular Ca(2+)-content and to translocate cytoplasmic protein kinase C to the plasma membrane in the initial stage of transmembrane signalling. Similarly, lipokeratinogenoside showed the ability to increase the intracellular Ca(2+)-content to the same extent as TPA did and to translocate protein kinase C to the membrane fraction. However, the above activities of lipokeratinogenoside decreased with removal of the linoleic acid moiety from lipokeratinogenoside with mild alkali, but linoleic acid alone did not show any activities, indicating that the lipokeratinogenoside molecule itself is required for expression of the activities.

Animals↗
PubMed1991

Endothelin-1-induced relaxation of guinea pig trachealis muscles.

Our accompanying paper demonstrated that endothelin-1 (ET-1 constricts guinea pig airways directly and indirectly through mediators such as histamine and arachidonate metabolites. In order to exclude the role of mast cells in bronchoconstriction, we sensitized guinea pigs and challenged them in vitro with an antigen (ovalbumin). In the postanaphylactic trachea, ET-1 caused a transient relaxation followed by constriction. Such relaxation by ET was also observed in the tracheas constricted with carbamylcholine. The relaxation was completely blocked by nordihydroguaretic acid and AA861, lipooxygenase inhibitors, but not by indomethacin, a cyclooxygenase inhibitor, and FPL 55712, a leukotriene antagonist. Because the relaxation was not affected even in the presence of methylarginine, an inhibitor of NO synthesis, and superoxide dismutase, an enzyme for destroying NO radical, we concluded that ET-1 induces the relaxation of the tracheal muscles by producing lipooxygenase products, probably hydroperoxides of arachidonic acid.

Anaphylaxis↗