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Biomedical subjects

M Kai

Publications and source records attributed to M Kai.

At least 127 records · Page 7Linked to original sources
PubMed1995

Infrequent somatic mutation of the MTS1 gene in primary bladder carcinomas.

We examined a candidate tumor suppressor gene on chromosome 9p21, MTS1/CDK4I (multiple tumor suppressor 1/cyclin-dependent kinase 4 inhibitor), which has been found to be mutated frequently in cell lines derived from bladder carcinomas, for somatic mutations in 39 primary bladder cancers by means of SSCP (single-stranded conformational polymorphism) and DNA sequencing. Mutations were detected in two of these carcinomas; one was a 61-base deletion and the other a 1-base deletion. In both cases the homologous allele was missing, indicating that "two-hit" mutation of the MTS1 gene had taken place in these tumors. The results indicated that inactivation of the MTS1 gene is likely to be a contributing factor in some, but not the majority of, bladder cancers.

Base Sequence↗
PubMed1995

Protein C deficiency and stroke in early life.

Plasma concentrations of protein C, protein S and antithrombin III were measured in 33 unselected children with a history of cryptogenic stroke (group 1), four children with previously ascertained low plasma concentrations of protein C following stroke (group 2) and 42 healthy children undergoing minor surgery (group 3). Protein S and antithrombin III were normal in all patients. Low concentrations of protein C were found in two patients in group 1 and in six healthy children in group 3. Low protein C concentrations returned to normal over many months in three of the four patients in group 2. Prophylactic antithrombotic therapy and/or termination of pregnancy had been carried out unneccessarily in two families in whom inherited protein C deficiency was not confirmed. The suggestion that heterozygous protein C deficiency contributes to the risk of arterial stroke was not supported by this study.

Adolescent↗
PubMed1995

Exercise induced ventilation/perfusion inequality in the horse.

Exercise in normal human subjects causes deterioration of matching of ventilation to blood flow in the lungs, but only in about 50% of those examined. A previous study (Wagner et al. 1989) of 5 horses showed no significant worsening of ventilation/blood flow (VA/Q) relationships during heavy exercise as determined by multiple inert gas elimination technique (MIGET). Because of the small number of horses in that study and the 50% human incidence of exercise induced VA/Q mismatch, we studied an additional 6 Thoroughbreds, comparing VA/Q relationships at the walk (1.4 m/s, 0 degrees incline) and during galloping (9.6 +/- 0.3 m/s, 7% incline). Such data were collected under 4 different conditions wherein inspired gas was 1) air, 2) 21% O2 in helium, 3) 15% O2 in N2 and 4) 15% O2 in helium. Each horse exercised 4 times (morning and afternoon of 2 days, with inspired gas conditions randomised). There was a small but significant increase in VA/Q mismatch (similar under all 4 conditions). The second moment of the VA/Q distribution (determined by the MIGET) increased significantly (P < 0.01) from 0.31 +/- 0.01 at the walk to 0.38 +/- 0.02 during gallop. This increase however is small: 0.38 is well within the range of this parameter for normal human subjects (where the 95% upper confidence limit is 0.60). This study shows that a small amount of exercise induced VA/Q mismatch can occur in the horse as in man, but the mechanism remains to be elucidated and its clinical significance remains to be established.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗
PubMed1995

Strand break formation in plasmid DNA irradiated in aqueous solution: effect of medium temperature and hydroxyl radical scavenger concentration.

Plasmid pBR322 DNA (4363 base pairs) in aerobic aqueous solution was irradiated with 60Co gamma-radiation. The change of diffusion coefficients (D) of chemical species, rate constants (k) of radical-DNA interaction and solubilities of O2 in water cannot be ignored when a temperature varies more than a few tens of centigrade. It is important to examine the variation of the yields of DNA strand breaks as a function of temperature in order to analyze the mechanisms of DNA strand breaks from the chemical point of view. Hence, we observed the change of the yield of strand breaks with temperatures between -20 and 42 degrees C by agarose gel electrophoresis. We also observed the change of the yield of strand breaks with the concentration of OH scavenger (Tris) from 1 mmol dm-3 to 100 mmol dm-3 and summarized it with previous experiments. This summarization indicated that the order of the lifetime of OH radical in cellular environment is several nanosecond. This value is consistent with the measurement of the lifetime of 8.7 nanosecond for OH radical in mammalian cell (Roots, R. and Okada, S. (1975) Radiat. Res. 64, 306-320).

Culture Media↗
PubMed1995

Deodorization of laboratory animal facilities by ozone.

Deodorizing effect of ozone was investigated comparing two types of compact ozonizing apparatus made on an experimental basis. The concentrations of ammonia and trimethylamine were examined as an indicator for deodorizing effect of ozone in animal rooms of rats and guinea pigs at laboratory animal facilities of three different universities. Both of the ozonizing apparatus were able to remove ammonia and trimethylamine in animal rooms, with no significant difference in the performance of the two apparatus.

Ammonia↗
PubMed1995

Localisation of the gene encoding diacylglycerol kinase 3 (DAGK3) to human chromosome 3q27-28 and mouse chromosome 16.

The gene encoding a 90 kDa diacylglycerol kinase protein, DAGK3, that is predominately expressed in the retina, was localised by fluorescence in situ hybridisation to human chromosome 3q27-28. This was subsequently confirmed by mapping of its mouse homologue to chromosome 16, a region syntenic to this part of human chromosome 3. No retinopathies have so far been assigned to this region.

Animals↗
PubMed1995

Synchronous circadian rhythms of mRNA levels and activities of cholesterol 7 alpha-hydroxylase in the rabbit and rat.

Cholesterol 7 alpha-hydroxylase, the key enzyme in a series of metabolic changes for the production of bile acids from cholesterol, shows circadian rhythms. The mechanism of the circadian rhythms is the subject of controversy; moreover, few pieces of information are presently available. Because the rabbit is a good animal model for the study of human cholesterol-bile acid metabolism, in the present study we isolated a complete cDNA encoding rabbit cholesterol 7 alpha-hydroxylase (3022 base pairs (bp) long and 1503 bp open-reading frame encoding 501 amino acid residues). Using this isolate rabbit cDNA and the rat cDNA as probes, the circadian rhythms of this enzyme were studied in normal male rabbits and rats. The animals were maintained on a 12-h light-dark cycle. Three subjects each were then killed every 3 h for 1 day. The livers were harvested, and the mRNA levels and the activities of the enzyme were measured. Both mRNA levels and activities of the enzyme showed remarkable circadian rhythms, with higher values during the dark phase and lower values reaching minimum during the light phase. The enzyme activities correlated well with the mRNA levels. There was no shift in the cycles of the enzyme activities and the mRNA levels. These findings suggest that pretranslational regulation is the most likely mechanism for the circadian rhythms of cholesterol 7 alpha-hydroxylase. Because the rhythms of mRNA levels and activities of this enzyme are synchronous, the turnover of the enzyme should be as fast as that of the mRNA, and we can hereafter measure the mRNA levels instead of the enzyme.

Amino Acid Sequence↗
PubMed1995

[Retinopathy and perinatal outcome in diabetic pregnancy].

Sixty patients with diabetes mellitus (DM) antedated pregnancy were enrolled; seven had proliferative retinopathy, 13 had simple retinopathy, and 40 were intact. Diet and/or insulin was prescribed to adjust their glucose control at fasting to < 100 mg/dl, as well as at 2 hours postprandial to < 120 mg/dl. Glycohemoglobin (Hemoglobin A1c) levels ranged between 5.4% and 6.4% in the third trimester in three groups. Incidences of pregnancy complications (toxemia, hydramnios, urinary tract infection and cesarean section) and neonatal complications (low Apgar score, hypoglycemia, jaundice, polycythemia, respiratory distress syndrome and anomaly) did not differ significantly with the grade of retinopathy. Compared with the intact group, the duration of DM was significantly longer in the retinopathy groups and the incidence of fetal distress was significantly higher in the proliferative retinopathy group. In ten of 60 patients (16.7%) the grade of retinopathy progressed during pregnancy. In four patients photocoagulation was performed for neovascularization, and proved to be effective. There was a tendency for those whose retinopathy progressed to the proliferative stage during pregnancy to have larger decreases in glycohemoglobin and for their retinopathy to worsen after delivery. With tight maternal glucose control and intensive fetal surveillance, we obtained good perinatal outcome in pregnancies with diabetic retinopathy, as compared to diabetic pregnancy without diabetic microangiopathy. Careful and frequent monitoring of retinal changes should be required during pregnancy and the postpartum period.

Adult↗
PubMed1994

Fluorogenic reactions for biomedical chromatography.

A number of fluorogenic reactions, which have been used for HPLC detection systems by means of pre- and/or postcolumn derivatization, are surveyed with respect to both sensitivity and selectivity for the determination of biomedically important substances. For the derivatization of the substances, two types of fluorogenic reactions, fluorescence-generating and fluorescence-tagging, have been studied. The former are usable in most instances for both pre- and postcolumn derivatization methods, and the latter only for precolumn derivatization methods. HPLC methods utilizing the fluorogenic reactions allow analytes to be detected at picomole-subfemtomole levels. In the fluorescence-generating reactions, several fluorogenic reagents possessing two or more reactive sites in the molecule, which show molecular recognition for a variety of analytes, permit facile and reproducible detection in HPLC because there are fewer interferences from biological matrices.

Amines↗
PubMed1994

Molecular cloning of a diacylglycerol kinase isozyme predominantly expressed in human retina with a truncated and inactive enzyme expression in most other human cells.

In order to clone novel diacylglycerol kinase (DGK) isozymes, we first obtained a DGK-related cDNA fragment by polymerase chain reaction using the human hepatoma cell line HepG2 mRNA and degenerated primers. The amplified fragment was subsequently used as a probe for screening the cDNA library from HepG2 cells. We obtained a cDNA clone coding for a novel DGK isozyme (designated DGK gamma) comprised of 791 amino acid residues. The amino acid sequence of DGK gamma was 52 and 62% identical to those of previously sequenced porcine 80-kDa and rat 90-kDa enzymes, respectively. DGK gamma, although initially cloned from the HepG2 cDNA libraries, was unexpectedly expressed in the human retina abundantly and to a much lesser extent in the brain. Other human tissues, including the liver and HepG2 cells, contained extremely low levels of DGK gamma mRNA. Furthermore, HepG2 cells and most of the human tissues except for the retina and brain expressed a truncated DGK gamma with an internal deletion of 25 amino acid residues (Ile451-Gly475). When transfected into COS-7 cells, the nontruncated cDNA gave phosphatidylserine-dependent DGK activity with no apparent specificity with regard to the acyl compositions of diacylglycerol. In contrast the truncated cDNA failed to give DGK activity in spite of the expression of its mRNA and enzyme protein in COS cells, thus demonstrating that the truncated DGK gamma is catalytically inactive. The sequence comparison of the three cloned DGKs revealed the presence of four highly conserved regions including the two sets each of EF-hand and zinc finger structures. Although the implication of the catalytically inactive form of DGK gamma remains unknown, this work further demonstrates the occurrence of multiple animal DGK isozymes with a conserved basic structure but with markedly different expression patterns depending on the cell types.

Amino Acid Sequence↗
PubMed1994

Two membrane-bound c-type cytochromes of Thiobacillus ferrooxidans: purification and properties.

Membrane-bound cytochrome c, cytochrome c-552 (m) was purified from Thiobacillus ferrooxidans. It showed an absorption peak at 410 nm in the oxidized form, and peaks at 552, 523 and 416 nm in the reduced form. Its molecular mass, Em,7 and isoelectric point were 22,300, +0.336 volt and 9.1, respectively. Another membrane-bound cytochrome c, cytochrome c-550 (m) was also purified. It showed an absorption peak at 408 nm in the oxidized form, and peaks at 550, 523 and 418 nm in the reduced form. Its molecular mass was estimated to be 51,000. Ferrocytochromes c-552 (m) and c-550 (m) were oxidized by cytochrome c oxidase of the bacterium. The reactivity with the oxidase of cytochrome c-550 (m) was higher than that of cytochrome c-552 (s) (soluble cytochrome) of the bacterium, while the reactivity of cytochrome c-552 (m) was greatly lower than that of cytochrome c-552 (s).

Amino Acid Sequence↗
PubMed1994

Determination of guanine and its nucleosides and nucleotides in human erythrocytes by high-performance liquid chromatography with postcolumn fluorescence derivatization using phenylglyoxal reagent.

A high-performance liquid chromatographic method with on-line postcolumn fluorescence derivatization is described for the simple and sensitive determination of guanine and its nucleosides and nucleotides in human erythrocytes. After deproteinization of the biospecimen, guanine and its nucleosides and nucleotides were separated on a reversed-phase column (TSKgel ODS-120T) by gradient elution with methanol in the aqueous mobile phase consisting of tetra-n-propylammonium phosphate (pH 6.0) and phosphate buffer (pH 6.0). The compounds were then automatically converted into fluorescent derivatives by reaction with phenylglyoxal. This derivatization was selective for guanine-containing compounds. The present method permitted the reliable quantification of GDP and GTP in human erythrocytes. The detection limits (at a signal-to-noise ratio of 3) for guanine and its nucleosides and nucleotides were 3.2-10.0 pmol in a 20-microliters injection volume. The concentrations of GDP and GTP in human erythrocytes were 17.2 +/- 6.2 and 40.2 +/- 5.8 nmol/ml, respectively.

Adult↗
PubMed1994

Antigenic variation and serotyping of HIV type 1 from four World Health Organization-sponsored HIV vaccine sites. WHO Network for HIV Isolation and Characterization.

Serologic reactivities of serum or plasma from 55 HIV-1 subjects in four countries--Brazil, Rwanda, Thailand, and Uganda--were examined by V3 peptide immunoassay. Forty-seven (85.5%) of the 55 specimens tested positive to the homologous peptide. A strong correlation between serotype (i.e., pattern of serologic reactivity with a panel of peptides) and genotype was not found. However, the V3 peptide immunoassays may be useful for epidemiologic studies to trace the distinctive HIV-1 strains from different geographic regions of the world. The serology data obtained may be useful for the development of effective V3-based vaccines.

AIDS Vaccines↗
PubMed1994

Growth inhibition of Clostridium difficile by intestinal flora of infant faeces in continuous flow culture.

Growth of Clostridium difficile was inhibited more strongly in continuous flow (CF) culture with C. difficile-negative faeces of infants than with C. difficile-positive faeces. Culture of faecal flora of infants yielded a greater variety of bacterial species in C. difficile-negative than in C. difficile-positive faeces. In the mixed CF culture of C. difficile with Enterococcus avium, Bacteroides distasonis, Eubacterium lentum, C. ramosum, C. perfringens and either Escherichia coli or Klebsiella pneumoniae isolated from C. difficile-negative faeces, inhibition of growth of C. difficile was demonstrated when the pH of the culture medium was decreased. Amino-acid analysis of CF cultures showed considerable utilisation of aspartic acid, serine, threonine, arginine and asparagine. A marked increase in concentrations of citrulline and ornithine was found in the culture that inhibited growth of C. difficile. The addition of citrulline and ornithine into a Gifu anaerobic medium (GAM) broth produced no inhibition of growth of C. difficile. The addition of the mixture of the depleted amino acids (aspartic acid, serine, threonine, arginine and asparagine) to the culture filtrate or adjustment of the pH of the culture filtrate induced considerable growth of C. difficile. These results suggest that the inhibition of growth of C. difficile may be due to consumption of amino acids by intestinal flora, and not to the presence of inhibitors produced by the intestinal flora.

Amino Acids↗
PubMed1994

Mechanism of reduction in alveolar-arterial PO2 difference by helium breathing in the exercising horse.

Previous work has shown that replacing N2 in air with He at the same inspired O2 fraction reduces the exercise-induced alveolar-arterial PO2 difference (AaPO2) in horses but has provided no mechanism explaining this effect. We sought to distinguish among possible causes by using the multiple inert gas elimination technique. Six horses were studied on a high-speed treadmill while they breathed either ambient air or normoxic He-O2. O2 uptake reached 138.0 ml.min-1.kg-1 and was not affected by He-O2. Temperature-corrected arterial PO2 was 76.7 Torr (air) and 86.9 Torr (He-O2) (P < 0.01). Corresponding AaPO2 was 22.3 and 15.9 Torr, respectively (P < 0.01). Mean AaPO2 predicted from ventilation-perfusion inequality did not change with He-O2 (12.7 Torr with air and 11.9 Torr with He-O2). Mean arterial PCO2 was 50.1 Torr with air and 44.1 Torr with He-O2 (P < 0.01); minute ventilation and tidal volume were correspondingly higher by 140 l/min and 1.0 liter, respectively, with He-O2. Pulmonary O2 diffusing capacity, cardiac output, and all ventilation-perfusion dispersion indexes did not change with He-O2. Intrapulmonary shunt was insignificant. Higher ventilation with He-O2 explained only approximately 4 Torr of the 10-Torr rise observed in arterial PO2. The remainder (and the corresponding fall in AaPO2) was due to more complete diffusion equilibration as a consequence of the higher minute ventilation and thus alveolar PO2, which reduced the average slope of the O2 dissociation curve, thereby increasing the ratio of diffusive to perfusive conductance.

Animals↗
PubMed1994

Toxic epidermal necrolysis with tracheobronchial and pulmonary complications.

A 55-year-old man developed multiple erythematous skin lesions after surgery for acoustic neurinoma. Necrosis and detachment of the epidermis developed and a diagnosis of toxic epidermal necrolysis (TEN) was made. Progressive dyspnea was evident two days after the onset of the skin lesions. Chest X-ray revealed diffuse interstitial shadows in both lung fields. On bronchoscopic examination, erosion, vesicle formation, necrosis and desquamation of the epidermis were seen in the tracheobronchial mucosa. Therapy, including prednisolone, improved the skin lesions as well as the chest X-ray and bronchoscopic findings. Tracheobronchial and pulmonary lesions were followed before, during and after treatment of TEN.

Bronchi↗
PubMed1994

Characteristics of vacuolating toxin produced by Helicobacter pylori.

OBJECTIVE: We sought a good indicator cell line to use in detecting the vacuolating toxin produced by Helicobacter pylori and in examining the characteristics of the toxin. DESIGN AND METHODS: Using five cell lines [baby hamster kidney (BHK-21), human amnion (FL), human uterine cancer (HeLa), rabbit kidney (RK-13) and African green monkey kidney (Vero)], cytotoxicity assays were performed with 33 H. pylori strains. To analyse the proteins produced by toxigenic and non-toxigenic strains, immunoblotting was done with the sera of patients with gastroduodenal diseases. RESULTS: When RK-13, FL, Vero, BHK-21 and HeLa cells were used for the assay, 73, 61, 27, 27 and 21% of strains, respectively, were toxigenic. The vacuolating toxin is sensitive to heat at 70 degrees C. By immunoblot analysis, under non-denaturing conditions, immune sera recognized proteins with molecular weights of 600,000 and 500,000 in the toxigenic but not in the non-toxigenic strains. CONCLUSION: H. pylori produces vacuolating toxin, which is a heat-sensitive protein at 70 degrees C and is easily detectable by cytotoxicity assay using the RK-13 cell line. Toxigenic H. pylori strains produce various proteins, including this toxin, which are recognized by sera from patients with gastroduodenal diseases.

Animals↗