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Biomedical subjects

M Kai

Publications and source records attributed to M Kai.

At least 145 records · Page 8Linked to original sources
PubMed1994

Monte Carlo simulation of DNA strand breaks induced by monoenergetic electrons using higher-order structure models of DNA.

A new theoretical model for estimating yield of initial DNA strand break induced by several monoenergetic electrons is presented. It is based on the Monte Carlo track structure simulation and on new DNA structure models (one turn of double-strand DNA, nucleosome, solenoid), and links physical and chemical stages of radiation action. Direct and indirect effects are strictly distinguished. Some results of calculations indicated: (1) the number of single strand breaks per nucleus (6 microns in diameter) per Gy in pure water was about 10 times that in a cell environment (OH radical life time is assumed to be 8.7 ns). This is due to the difference in the time-dependent variation in the total number of the OH radical; and (2) the contribution of indirect effects to total damage decreased as the order of the DNA target model structure used in the stimulation increased (e.g. a one-turn model of double-strand DNA, approximately 98.4%; but the 30-nm solenoid model, approximately 86.1%). This was due to the protective effect of histone protein against OH radical attack. Double-strand breaks were scored if two single-strand breaks were located on the same base pair. The present study indicated that the information from morphological and biochemical examinations of the cell environment must be considered more carefully with computer simulation.

Computer Graphics↗
PubMed1993

Determination of a cysteine protease inhibitor and its ethyl ester in mouse serum and muscle by liquid chromatography-mass spectrometry.

A liquid chromatographic-mass spectrometric method is described for the determination of a cysteine protease inhibitor (E64C) and its ethyl ester in mouse serum and muscle samples. The compounds in the sample, after deproteinization and solid-phase extraction, were separated by isocratic reversed-phase high-performance liquid chromatography and detected by on-line mass spectrometry. The use of an aqueous mobile phase containing methanol and 30 mM ammonium trichloroacetate provided abundant protonated molecular ions of the compounds in the atmospheric pressure chemical ionization interface of the detection system. The method permitted the quantitative determination of the inhibitors without internal standards in the biological matrices. The detection limits for the compounds, in the selected-ion monitoring mode, were 10-15 pmol on-column, at a signal-to-noise ratio of 5.

Animals↗
PubMed1993

High-performance liquid chromatography of N-terminal tryptophan-containing peptides with precolumn fluorescence derivatization with glyoxal.

A precolumn fluorescence derivatization method combined with high-performance liquid chromatography is described for the sensitive and selective determination of N-terminal tryptophan-containing peptides. The peptides and tryptophan were converted into fluorescent derivatives with glyoxal in a moderately acidic medium (pH 4.5). The derivatives were separated on a reversed-phase column with isocratic elution with an aqueous mobile phase composed of acetonitrile, methanol and phosphate buffer (pH 6.0), and subsequently detected by fluorimetry. The derivatization technique provided the respective N-terminal tryptophan-containing oligopeptides with single fluorescent peaks in chromatography. The detection limits for the peptides were 55-382 fmol per 100-microliters injection volume at a signal-to-noise ratio of 3. The method also allowed the facile detection of an N-terminal tryptophyl fragment in the enzyme reaction mixture of dynorphin A with trypsin.

Amino Acid Sequence↗
PubMed1993

Determination of tryptophan in human serum by high-performance liquid chromatography with pre-column fluorescence derivatization using phenylglyoxal.

A high-performance liquid chromatographic method based on pre-column fluorescence derivatization with phenylglyoxal is described for the sensitive and selective quantification of total (free plus albumin-bound) and free tryptophan in serum. Serum was deproteinized with perchloric acid for total tryptophan and by ultrafiltration for free tryptophan, and then subjected to fluorescence derivatization. The reaction mixture was separated on a reversed-phase column by isocratic elution and the tryptophan derivative was then detected by fluorimetry. The method was at least ten-fold more sensitive than other conventional chromatographic methods with no derivatization. The lower limit of determination (signal-to-noise ratio = 3) for endogenous tryptophan in human serum was 72 nmol/l, which corresponds to 200 fmol on-column.

Adult↗
PubMed1993

Rapid detection of Mycoplasma pneumoniae in clinical samples by the polymerase chain reaction.

A DNA amplification method was used to detect Mycoplasma pneumoniae in clinical samples. M. pneumoniae 16S ribosomal RNA gene sequences were selected as the amplification target region. The polymerase chain reaction (PCR) with purified DNA fragments as templates yielded an expected 88-bp fragment from M. pneumoniae but not from other Mycoplasma spp. nor from any of the other bacteria assayed. With this method, the 88-bp product specific for M. pneumoniae could be obtained from a minimum of 0.05 pg of M. pneumoniae DNA. Subsequently this PCR technique was used for the detection of M. pneumoniae in throat-swab samples. Twenty-two of 30 culture-positive clinical samples gave positive results in the PCR test. Thirty-two culture-negative clinical samples and 33 samples from healthy volunteers, of which only one was culture-positive, gave negative results in the same PCR test. This PCR method is useful for the direct detection of M. pneumoniae in clinical samples.

Base Sequence↗
PubMed1993

Analysis of intestinal flora of a patient with congenital absence of the portal vein.

A 14-year-old female patient, admitted for a closer examination of liver tumour (hepatocellular adenoma), was diagnosed as having a congenital absence of the portal vein. The blood ammonia level (approximately 120 micrograms dl-1) in the superior mesenteric vein was markedly low compared to the normal value of 300-350 micrograms dl-1 in the portal vein. The decreased ammonia concentration and urease activity of the patient's faeces were demonstrated. The dominant intestinal flora in the faeces of the patient, before operation, was Bifidobacterium sp., Bifidobacterium breve, Bifidobacterium lonqum, Lactobacillus plantarum, and after the operation Bacteroides vulgatus, Veillonella parvula, Peptococcus magnus Bifidobacterium longum. In contrast, Bifidobacterium bifidum, Bacteroides ureolyticus, Bacteroides ovatus and Bacteroides distasonis, B. ovatus, Bifidobacterium adolescentis were dominant flora in the faeces of two healthy volunteers, respectively. Among microorganisms isolated from the patient, Morganella morganii, Candida sp., Eubacterium aerofacience and Eubacterium rectale were strongly positive in urease activity in vitro; Streptococcus mitior, Staphylococcus intermedius, Micrococcus kristinae, Selenomonas ruminantum, Bacteroides ureolyticus and Lactobacillus casei ss. pseudoplantarum from the healthy volunteers. These results imply the homeostatic regulation system of faecal ammonia concentration by urease-producing microorganisms in the patient.

Adolescent↗
PubMed1993

[Estimations of organ dose and health risk of the mass chest X-ray examinations in children].

In Japan, mass chest X-ray examinations are mandated by law for schoolchildren and students. Recently, questions of the justification of such X-ray examination have arisen. In this study the absorbed doses of each organ, and the health detriments from the mass chest X-ray examinations to schoolchildren and students were estimated. The doses of organs were measured by the TLDs (Mg2SiO4), slab phantom, and anthropomorphic phantom. The probability of fatal cancer, and the resultant reduction in life expectancy induced by mass chest X-ray examinations were calculated by the multiplicative risk projection model of the ICRP-1990. The absorbed doses of lung, thyroid glands, esophagus, stomach, breast, and red bone marrow in first-year elementary schoolchildren were 90, 30, 90, 60, 90, and 30 muGy, respectively, and the doses in ovaries and testes were almost nil. Each organ dose of first-year students of junior high school was about 1.5 times that for elementary schoolchildren. The total radiation-induced lifetime cancer risk of schoolchildren and students was from 0.3 x 10(-5) to 0.9 x 10(-5) per person by the multiplicative risk projection model of the ICRP-1990 and a factor of 2 for the DDREF (dose and dose rate effectiveness factor). The reduction in life expectancy by radiation induced fatal cancer was from 15 x 10(-5) years to 50 x 10(-5) years per person. The results of this study suggest that subjects of mass chest X-ray examinations should be carefully selected from the viewpoint of radiation protection.

Adolescent↗
PubMed1992

Thiobacillus ferrooxidans cytochrome c oxidase: purification, and molecular and enzymatic features.

Cytochrome c oxidase from Thiobacillus ferrooxidans was purified to homogeneity and some of its properties were studied. The oxidase was solubilized with n-octyl-beta-D-thioglucoside (OTG) under acidic conditions (pH 4.0) and purified by one step of ion-exchange chromatography with a CM-Toyopearl column. The absorption spectrum of the oxidase showed peaks at 420 and 595 nm in the oxidized form and at 440 and 595 nm in the reduced form. Its CO compound showed a novel absorption spectrum; a double-peaked gamma band appeared at 429 and 438 nm. The oxidase seemed to have CuA-like copper atom from its ESR and near-infrared spectra. The oxidase molecule consisted of three polypeptides with molecular weights of 53,000, 22,000, and 17,000, respectively, as estimated by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. The molecular weight of the enzyme in a solution containing detergents was estimated to be 169,000 on the basis of the results obtained by gel filtration, while the molecular weight per heme alpha was estimated to be 83,700. The copper content of the oxidase was 1.01 g atom per mol of heme alpha. Therefore, the cytochrome seemed to contain one molecule of heme alpha and one atom of copper in the minimal structural unit consisting of one molecule each of the three subunits, and to occur as a dimer of the unit in the solution. The oxidase oxidized ferrocytochrome c-552 of the bacterium, and the optimal pH of the reaction was 3.5.(ABSTRACT TRUNCATED AT 250 WORDS)

Cell Fractionation↗
PubMed1991

Detection of 3,6-dinitrobenzo[a]pyrene in airborne particulates.

3,6-Dinitrobenzo[a]pyrene, a new mutagen, was detected in airborne particulates collected in Santiago (Chile). The quantity of the compound in the airborne particulates was very small, accounting for 0.01 micrograms/g of total particulates (0.002 ng/m3 of air) at the lowest concentration. It was found that 3,6-dinitrobenzo[a]pyrene is readily decomposed by UV irradiation at 312 nm. The decomposed product was identified as 3-nitrobenzo[a]pyrene-6-quinone by means of mass spectrometry and proton nuclear magnetic resonance analysis. The mutagenicity of 3,6-dinitrobenzo[a]pyrene was 137,000 revertants/nmole for Salmonella typhimurium strain TA98, less than that for strain TA98/1,8-DNP6, an acetyltransferase-deficient mutant, and more than that for strain YG1024, an acetyltransferase-rich mutant.

Air Pollutants↗
PubMed1991

Pre-column fluorescence derivatization high-performance liquid chromatography of opioid peptides in rat brain and its use for enzymatic peptide characterization.

A high-performance liquid chromatographic method involving fluorescence derivatization followed by separation on a reversed-phase polymer (octadecylated polyvinylalcohol copolymer gel) column is described for the determination of opioid peptides in rat brain tissues. The peptides extracted from brain tissues were converted into fluorescent derivatives by reaction with hydroxylamine, cobalt(II) ion and borate. The derivatives were separated on an Asahipak ODP-50 column by gradient elution of acetonitrile in the mobile phase containing borate buffer (pH 9.5). The detection limits (S/N = 3) for the peptides were 0.33-1.21 pmol per 100 microliters injected. The method actually permit the determination of leucine enkephalin, methionine enkephalin, methionine enkephalin-Arg-Phe and methionine enkephalin-Arg-Gly-Leu in the tissues. The method is also applied to the characterization of the peptides in the tissues by means of enzymatic degradations with carboxypeptidase A and trypsin.

Amino Acid Sequence↗
PubMed1991

High-performance liquid chromatographic determination of peptides released by tryptic degradation from opioid peptide precursors in rat brain.

A high-performance liquid chromatographic method involving postcolumn fluorescence derivatization is described for the quantification of five fragment peptides (methionine-enkephalin-Thr-Ser-Glu-Lys, methionine-enkephalin-Lys, methionine-enkephalin-Arg, leucine-enkephalin-Lys and leucine-enkephalin-Arg) released by tryptic digestion from the opioid peptide precursors (proopiomeranocortin and proenkephalins A and B) in rat brain tissues. The tissue proteins containing the precursors are hydrolyzed with trypsin to the fragment peptides. The peptides are separated on an Asahipak ODP-50 column and on-line detected fluorometrically by using hydroxylamine, cobalt(II) and borate buffer reagents. The detection limits (S/N = 3) for the peptides are 0.7-2.8 pmol per 100 microliters injected. The distribution of the precursors in the brain tissues was also discussed on the basis of the determined values of the fragment peptides.

Amino Acid Sequence↗
PubMed1991

[Monoamine oxidase inhibitory effects of pentanthrene type heterocyclic compounds].

Pentanthrene type heterocyclic compounds, which contain oxazole, isoxazole, oxadiazole, thiazole, isothiazole, thiadiazole or pyrrole ring as C-ring, and naphthalene, quinoline, isoquinoline or quinoxaline ring as A.B-ring, were prepared, and their monoamine oxidase (MAO) inhibitory activities were examined. As expected from our previous investigation on the structure-activity relationship of this series, most of them showed strong inhibitory potency to both MAO-A and MAO-B. However, a few indicated highly selective inhibition for either of MAO subtypes.

Animals↗
PubMed1991

Effects of longitudinal maternal glucose control on infants of diabetic mothers.

Between 1980 and 1987, 45 pregnant women with diabetes mellitus who required insulin therapy were delivered at Kagoshima Municipal Hospital. The perinatal mortality rate in the present study was zero. Twelve infants were large for gestational age, ten were small for gestational age, and 23 were appropriate for gestational age. Tight maternal glucose control (fasting values of less than 100mg/dl and 2 hours post-prandial values of less than 120mg/dl) obtained before 32 weeks of gestation significantly decreased the incidence of large for gestational age infants. However, longitudinal control patterns of maternal glucose during pregnancy have little effect on the incidence of small for gestational age infants and neonatal complications. The former was more closely related to maternal vascular complications. Congenital malformations were found in two cases.

Birth Weight↗
PubMed1990

High-performance liquid chromatographic determination of a cysteine protease inhibitor and its ethyl ester in mouse serum and muscle by pre-column fluorescence derivatization.

A simple and sensitive high-performance liquid chromatographic method has been developed for the determination of a cysteine protease inhibitor (E-64-c) and its ethyl ester in mouse serum and muscle samples. After deproteinization with acetone, E-64-c is converted into a fluorescent derivative by reaction with 3-bromomethyl-6,7-dimethoxy-1-methyl-2(1H)-quinoxalinone. The derivative is separated on a reversed-phase column by isocratic elution of aqueous acetonitrile and monitored fluorimetrically. The ethyl ester is hydrolysed to E-64-c by carboxyl esterase and then derivatized in the same way as E-64-c. The limits of detection, at a signal-to-noise ratio of 3, of E-64-c and the ester are 500 pmol/ml in serum (10 microliters) and 300 pmol/g in muscle (20 mg), corresponding to ca. 0.5 pmol each in a 50-microliters injection volume. The method allows the determination of E-64-c and the ethyl ester in mouse serum and muscle after oral administration of these compounds.

Administration, Oral↗
PubMed1989

Thiobacillus ferrooxidans cytochrome c-552: purification and some of its molecular features.

Soluble cytochrome c-552 was purified from Thiobacillus ferrooxidans to an electrophoretically homogeneous state. The cytochrome showed absorption peaks at 276, 411 and 523 nm in the oxidized form and peaks at 315, 417, 523 and 552 nm in the reduced form. The molecular weight of the cytochrome was estimated to be 13,800 on the basis of the amino acid composition and heme content, and 14,000 from SDS-polyacrylamide gel electrophoresis analysis. Its midpoint redox potential at pH 7.0 was determined to be +0.36 V. The N-terminal amino acid sequence of the cytochrome was determined as follows: A-G-G-A-G-G-P-A-P-Y-R-I-S-?-D-?-M-V-?-S-G-M-P-G-. Ferrocytochrome c-552 was oxidized by the membrane fraction of T. ferrooxidans, and the oxidation rate was more rapid at pH 3.0 than at pH 6.5. Ferricytochrome c-552 was reduced by Fe(II)-cytochrome c oxidoreductase with Fe2+ at pH 3.5, while horse ferricytochrome c was not reduced by the enzyme under the same reaction conditions.

Amino Acid Sequence↗
PubMed1989

High-performance liquid chromatographic determination of substance P-like arginine-containing peptide in rat brain by on-line post-column fluorescence derivatization with benzoin.

A high-performance liquid chromatographic method with fluorescence detection is described for the determination of substance P, one of the neuropeptides, in the hypothalamus tissue of rat brain. The detection is based on on-line post-column fluorescence derivatization selective for arginine-containing peptides. The endogenous substance P-like arginine-containing peptide extracted from the tissue and [D-Phe11]-neurotensin as an internal standard were separated from various interfering substances on a reversed-phase column (TSKgel ODS-120T) by gradient elution with acetonitrile-phosphate buffer (pH 2.3). The peptides in the eluate were then automatically converted into fluorescent derivatives for detection by reaction with benzoin. Arginine-containing fragments produced by the enzyme reaction of substance P in the chromatographic fraction with trypsin were also detected, for the identification of the endogenous substance P-like arginine-containing peptide. The method was sensitive enough to permit the quantitative determination of the peptide at a concentration as low as 580 fmol/mg of protein in the brain homogenate. The concentration values of the substance P-like arginine-containing peptide in the tissue were 9.45 +/- 1.50 pmol/mg of protein (six determinations).

Animals↗