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Biomedical subjects

M Nakano

Publications and source records attributed to M Nakano.

At least 415 records · Page 23Linked to original sources
PubMed1996

A chemiluminescent detection of superoxide radical produced by adherent leucocytes to the subendothelium following thrombolysis: studies with a photochemically induced thrombosis model in the guinea pig femoral artery.

Reocclusion following thrombolysis is a major limitation of thrombolytic therapy with recombinant tissue-type plasminogen activator (rt-PA) because denuded vessel wall exposed to blood following thrombolysis is a favourable surface for platelet and leucocyte deposition. We have applied a chemiluminescence technique to detect superoxide radical (0(-2)) produced by leucocytes adherent to the femoral artery 24 h after photochemically induced thrombogenesis in the guinea pig in vivo and subsequent thrombolysis by rt-PA. Intravenous administration of MCLA, a specific chemiluminescence reagent for detecting O(-2), markedly increased photon emission. the photon emission was markedly potentiated by phorbol myristate acetate and was suppressed by superoxide dismutase. Reocclusion 24 h after rt-PA induced thrombolysis was observed in 10 of 16 animals. Histological observations revealed extensive polymorphonuclear leucocytes adherent to the vessel wall at the site of thrombogenesis and thrombolysis. A higher level of 0(-2) could be detected from the arteries in which thrombolysis was induced compared with those without thrombolysis. Further, the level 0(-2) detected was greater in reoccluded arteries compared with those in which reflow was established. These observations suggest that 0(-2) is produced by adherent leucocytes at the site of thrombolysis and that leucocytes are involved in reocclusion after thrombolysis.

Animals↗
PubMed1996

Determination of R(+)- and S(-)-lansoprazole using chiral stationary-phase liquid chromatography and their enantioselective pharmacokinetics in humans.

PURPOSE: Stereoselective and sensitive methods employing chiral stationary phase columns for HPLC determination of enantiomers of lansoprazole in the human serum were developed and pharmacokinetic behaviors of the enantiomers were evaluated in seven subjects. METHODS: Five chiral stationary phase columns: Chiralcel OD (cellulose tris(3,5-dimethyl-phenylcarbamate)), OF (cellulose tris(4-chlorophenylcarbamate)), OG (cellulose tris(4-methylphenylcarbamate)) and OJ (cellulose tris(4-methylbenzoate)), and Chiralpak AS (amylose tris ((S)-1-phenylethylcarbamate)) were investigated. RESULTS: Chiralcel OD and Chiralpak AS columns gave a good resolution of R(+)- and S(-)-enantiomers from racemic lansoprazole, but Chiralcel OF, OG, and OJ did not. The mean Cmax and the AUC values of R(+)-enantiomer were 3-5 times greater than those of S(-)-enantiomer following oral administration of 30 mg of racemic lansoprazole. The CLtot values of R(+)-enantiomer were significantly smaller than those of S(-)-enantiomer. Binding of R(+)-enantiomer to human serum proteins was significantly greater than that of S(-)-enantiomer. The mean metabolic ratio (metabolites/parent compound) in human liver microsomes of S(-)-enantiomer was significantly greater than that of R(+)-enantiomer. CONCLUSIONS: The stereoselective pharmacokinetics of lansoprazole enantiomers is likely due to its stereoselective protein binding and/or metabolism.

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed1996

Effects of a mixture of organisms, Lactobacillus acidophilus or Streptococcus faecalis on cholesterol metabolism in rats fed on a fat- and cholesterol-enriched diet.

The effect of a mixture of organisms (a probiotic mixture) comprising Bacillus, Lactobacillus, Streptococcus, Clostridium, Saccharomyces and Candida (10(7-8) colony-forming units/g rice bran of each component) on lipid metabolism was compared with that of L. acidophilus and that of S. faecalis. There were four treatment groups: rice bran (control), the mixture of organisms, L. acidophilus or S. faecalis (30 g/kg) were given to rats in a fat- and cholesterol-enriched diet for 4 weeks. The serum total cholesterol concentration of the group fed on the mixture of organisms was reduced by 15-33% compared with the other groups at the end of the 4-week feeding period (P < 0.05). This group also had a lower hepatic cholesterol concentration (36-44%) than the two single-bacteria groups (P < 0.05). 3-Hydroxy-3-methylglutaryl-Co A reductase (NADPH; EC 1.1.1.34) activities of the mixed-organism and L. acidophilus groups were significantly lower (61-63%) than those of the other groups (P < 0.05); the activity of the S. faecalis group was also significantly lower (42%) than that of the control group (P < 0.05). The faecal cholesterol and bile acid concentrations of the mixed-organism group increased compared with those of the L. acidophilus and S. faecalis groups (P < 0.05). The capacity of the mixed-organism cells to bind bile salt in vitro was significantly higher (approximately 50%) than that of the single-bacteria cells (P < 0.05). On the other hand, cholesterol micelle formation for the mixed-organism cells was significantly (approximately 9%) lower than that of the single-bacteria cells (P < 0.05). These results indicate that the mixture of organisms decreased the synthesis of cholesterol in the liver and increased the loss of steroids from the intestine, in rats. Thus, the mixture of organisms had a hypocholesterolaemic role.

Animals↗
PubMed1996

Interaction of nucleosome core DNA with transition proteins 1 and 3 from boar late spermatid nuclei.

The DNA binding properties of boar transition protein 1 and 3 (TP1 and TP3) were studied by means of physicochemical techniques. The ultraviolet difference absorption spectra upon TP1 and TP3 binding to rat liver nucleosome core DNA (double-stranded DNA) showed TP1- and TP3-induced hyperchromicity at 260 nm, which is suggestive of local melting of DNA. CD measurements of TP1-DNA and TP3-DNA complexes indicated that the binding of TP1 and TP3 induced different conformational changes in DNA, probably including local melting of DNA. Thermal melting studies on the binding of TP1 and TP3 to DNA showed that although at 1 mM NaCl TP1 and TP3 caused slight stabilization of the DNA against thermal melting, destabilization of the DNA was observed at 50 mM NaCl. From the results of quenching of the tyrosine fluorescence of TP1 and the tryptophan fluorescence of TP3 upon their binding to double-stranded and single-stranded boar liver nucleosome core DNA at 50 mM NaCl, the apparent association constants for the binding of TP1 to double- and single-stranded DNA were calculated to be 8.0 x 10(4) and 1.3 x 10(5) M-1, respectively, and those for the binding of TP3 to double- and single-stranded DNA to be 7.1 x 10(4) and 1.8 x 10(5) M-1, respectively. These results suggest that TP1 and TP3, having higher affinity for single-stranded DNA, induce local destabilization of DNA, probably through the stacking of Tyr32 and Trp18 with nucleic acid bases, respectively.

Amino Acid Sequence↗
PubMed1996

The involvement and sources of active oxygen in experimentally induced acute pancreatitis.

The involvement of active oxygen has been suggested in the development of cerulein-induced acute pancreatitis in rats. Previously, we directly detected pancreatic active oxygen (O2-) production in rats with cerulein-induced pancreatitis by using a supersensitive photon counter and a cypridina luciferin analogue (MCLA) that reacts specifically with O2- by emitting luminescence. In the present study, with the specific aim of determining the source of O2-, we prepared two groups of animals with cerulein-induced pancreatitis: those treated with allopurinol, a xanthine oxidase inhibitor; and those treated with nitrogen mustard, a leukopenia-inducing substance. In each of these two groups, pancreatic O2- production and the severity of pancreatic injuries were comparatively studied. In the leukopenic animal group, decreases in O2- dependent chemiluminescence and improvement in the pancreatic condition coincided. This suggests that neutrophils might be involved in experimentally induced pancreatitis as a source of active oxygen.

Acute Disease↗
PubMed1996

A novel neutralization epitope on the 'thumb' subdomain of human immunodeficiency virus type 1 reverse transcriptase revealed by a monoclonal antibody.

We have prepared a MAb, 7C4, which inhibits the RNA-dependent DNA polymerase activity of human immunodeficiency virus type 1 (HIV- 1) reverse transcriptase (RT); this MAb has allowed identification of a previously unknown neutralizing epitope of RT. Analysis of the epitope and of the mechanism of polymerase inhibition revealed that 7C4 acts by interfering with the interaction between RT and the template-primer. 7C4 recognizes a discontinuous epitope on the two alpha-helices, alphaH and alpha(I), that make up the 'thumb' subdomain of RT. The existing crystallographic model of HIV-1 RT suggests that the 'thumb' subdomain, together with the 'fingers' and 'palm', form a nucleic-acid-binding cleft in the 66 kDa subunit of RT and that alphaH is in contact with the primer strand of the template-primer. The extent of inhibition of enzyme activity produced by 7C4 correlates with the reported primer-length-dependency of template-primer binding to RT. Inhibition by 7C4 was competitive with respect to the template-primer and mixed with respect to the substrate. Binding of 7C4 to RT was prevented by preincubation of the enzyme with high concentrations of template-primer but not with substrate. Thus, the 7C4 epitope apparently exists on part of the template-primer binding site of the alphaH and alpha(I) regions of the 'thumb' subdomain. This neutralization epitope is a logical target for the development of new types of HIV-1 RT inhibitors.

Animals↗
PubMed1996

Intra- and interbreed genetic variations of mitochondrial DNA major non-coding regions in Japanese native dog breeds (Canis familiaris).

Mitochondrial DNA (mtDNA) major non-coding regions were amplified from 73 dogs of eight Japanese native dog breeds and from 21 dogs of 16 non-Japanese dog breeds by the polymerase chain reaction and their DNA sequences were determined. A total of 51 nucleotide positions within the non-coding region (969-972 base pairs) showed nucleotide variations of which 48 were caused by transition. These nucleotide substitutions were abundant in the region proximate to tRNA(Pro). In addition to the nucleotide substitutions, the dog mtDNA D-loop sequences had a heteroplasmic repetitive sequence (TACACGTAGCG) involving size variation. The DNA sequences of the non-coding region were classified into four different groups by phylogenetic analysis and the deepest branchpoints of this dog phylogeny was calculated to about 100,000 years before the present. Phylogenetic analysis showed that Japanese native dog breeds could not be clearly delimited as distinct breeds. Many haplotypes found in members of some clustering groups were seen in each dog breed, and interbreed nucleotide differences between Japanese dog breeds were almost the same as the intrabreed nucleotide diversities.

Animals↗
PubMed1996

Cloning and expression analysis of Aedes aegypti opsin: adaptation of an in situ hybridization protocol for mosquitoes.

Opsin is a G protein coupled photoreceptor that activates a signal transduction cascade in the ommatidia. Its primary and secondary structure is conserved both in insects and vertebrates as exemplified by the Drosophila opsins. Through serendiplious cloning of a PCR fragment, we have identified an opsin cDNA. The latter was used to clone full length cDNAs from a mosquito head library. The main purpose of cloning was to have a positive control probe to establish an in situ hybridization protocol for less abundant probes. Opsin-mRNA is localized specifically to the visual receptor cells in the ommatida. No other cells in the brain or the remainder of the body are positive. This is confirmed by Northern blot analysis. The sequence of the receptor, of which we have found two different transcripts, confirms its typical topology, including the seven transmembrane spanning regions and the intracellular carboxy terminus that has potential phosphorylation sites. Our in situ hybridization protocol combines several procedures: the most important points are: (a) the immediate processing of sections after cutting, and (b) the sections are never allowed to dry out once the procedure was started. Our protocol has a much higher sensitivity, using approximately 50 x lower concentrations of probe compared to published protocols. In addition to the detection of opsin-mRNA, it has been successfully applied to the detection of the low abundant insulin receptor homologue. Furthermore, Aedes aegypti probes were visualizing a similar tissue specificity when applied to the malaria mosquito Anopheles albimanus.

Aedes↗
PubMed1996

Serum prostate-specific antigen values for the prediction of clinical stage and prognosis in patients with prostate cancer: an analysis of 749 cases.

BACKGROUND: The clinical significance of pretreatment serum prostate-specific antigen (PSA) values was studied to determine the ability to predict clinical stage and prognosis using a relatively large number of patients with prostate cancer. METHODS: Serum PSA values at diagnosis were analyzed from 749 patients with newly-diagnosed prostate cancer and registered in the Tokai Urological Cancer Registry. Correlations between the PSA value, the clinical stage and prognosis of the patients were evaluated. RESULTS: Serum PSA values at each stage of diagnosis showed positivity (> or = 3.6 ng/mL) in 23% (stage A1) to 91.2% (stage D2) of patients, and it was possible to obtain statistical differences between the stages, even between A1 and A2. Based on a cumulative study of PSA distribution, stages greater than A2 could be diagnosed using a cut-off of 7.2 ng/mL, with a 99.2% positive predictive value (PPV), and a 16.2% negative predictive value (NPV). At a PSA level of 10.8 ng/mL, stages greater than B2 could be predicted with a PPV of 95.3% but an NPV of 40.3%. Pretreatment PSA values were a significant prognostic indicator in stage D2 patients using 100 to 150 ng/mL as the cut-off values. These differences were primarily found in the poorly differentiated group, which showed a statistical difference using cut-off PSA values from 75 to 150 ng/mL. CONCLUSIONS: Serum PSA levels from a large number of patients can be used to predict the stage and prognosis of prostate cancer patients.

Aged↗
PubMed1996

Effect of activated charcoal and atropine on absorption and/or exsorption of organophosphorus compounds in rats.

Effects of activated charcoal and atropine for the removal of organophosphorus compounds, which remain in the gastrointestinal tract or have already been absorbed into the systemic circulation, were investigated in rats. Activated charcoal extensively adsorbed the organophosphates fenitrothion, tolelofos methyl, piperophos and salithion, and its immediate administration after oral ingestion of fenitrothion remarkably reduced serum fenitrothion levels, but had no effect on the serum levels of the compound which had been absorbed from the gastrointestinal tract. Thus, all of the organophosphorus compounds were poorly exsorbed (0.002-0.39% of the dose in 120 min) from the blood into the intestinal lumen probably due to their extensive protein binding and large distribution volumes. Atropine inhibited absorption of fenitrothion in the perfusion in-situ and also delayed the absorption of the compound in-vivo, but had no significant effect on exsorption of fenitrothion. The serum fenitrothion levels on treatment with both atropine and charcoal significantly decreased compared with those of the control. We conclude that, oral activated charcoal will not be able to enhance the elimination of organophosphorus compounds which have already been absorbed into the systemic circulation, but constituted useful method for the removal of the compounds remaining in the gastrointestinal tract because of its excellent adsorptive capacity.

Animals↗
PubMed1996

Pharmacokinetic and pharmacodynamic properties of FK070 (KDI-792), a novel thromboxane receptor antagonist/thromboxane synthetase inhibitor, after single and multiple oral administrations to healthy volunteers.

FK070, a thromboxane A2 (TXA2) receptor antagonist/TXA2 synthetase inhibitor, was given orally to healthy male volunteers in a single- and multiple-dose study. In the single-dose study (200, 300, 400 mg), the area under the plasma concentration-time curve (AUC) and the maximum plasma concentration (Cmax) increased non-linearly with dose, while the mean elimination half-life (V0) was essentially unchanged (3.9-7.3h). Recovery of the unchanged drug in the urine was 12-25%. Cmax and AUC as determined with 200 mg of drug after a meal decreased by about 60 and 30%, respectively. Ex-vivo platelet aggregation in the plasma by a TXA2 analogue, U46619, was almost completely inhibited within 1 h, after all doses of drug, with a significant dose-dependent inhibition maintained for 8 h or more, which was much longer than was expected from drug plasma concentration. The aggregation by adenosine diphosphate (ADP) was inhibited to a lesser extent. FK070 also inhibited TXA2 synthetase as evidenced by decreased production of TXB2 and reciprocally increased production of 6-keto-prostaglandin F1 alpha in the serum during ex-vivo whole blood coagulation. These effects peaked 1 h after drug and lasted until 4 h with the higher doses. In the multiple-dose study (300 mg, twice a day, after meals for 6.5 days), drug concentrations in the plasma were well fitted to a three-compartment open model with first-order absorption. FK070 afforded extensive inhibition of platelet aggregation by U46619 throughout the administration period, with a significant inhibition lasting as long as 48 h after conclusion of administration. No clearly drug-related changes were found in routine laboratory tests, subjective and objective findings, or vital signs. FK070 was concluded to be well tolerated and to provide long-lasting blockade of TXA2 receptors, and plasma concentration-dependent inhibition of TXA2 synthetase in the platelets.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMed1996

Quinolone-resistant Neisseria gonorrhoeae: correlation of alterations in the GyrA subunit of DNA gyrase and the ParC subunit of topoisomerase IV with antimicrobial susceptibility profiles.

Fifty-five clinical strains of Neisseria gonorrhoeae were examined for mutations in the gyrA and parC genes and for antimicrobial susceptibility profiles. The MICs of quinolones for 31 strains with alterations in GyrA were significantly higher than the MICs for 24 strains without such alterations. Eleven strains with alterations in both GyrA and ParC were significantly more resistant to fluoroquinolones than those with alterations in GyrA alone. The MICs of cephalosporins for these strains were also significantly higher than those for other strains.

Amino Acid Sequence↗
PubMed1996

Microtubule-disrupting agents inhibit nitric oxide production in murine peritoneal macrophages stimulated with lipopolysaccharide or paclitaxel (Taxol).

Paclitaxel (Taxol), a yew-derived antimitotic agent which binds to microtubules, can mimic certain effects of lipopolysaccharide (LPS) on macrophages from LPS responder mouse strains. The production of nitric oxide (NO) by the peritoneal macrophages of LPS responder C3H/HeN mice stimulated with taxol or LPS was partially, but not completely, suppressed by microtubule-disrupting agents, such as colchicine, podophyllotoxin, vinblastine, and nocodazole, but not by lumicolchicine, an inactive derivative of colchicine. Inducible NO synthase protein expression induced by taxol and LPS in the macrophages was also suppressed by colchicine, but colchicine did not suppress the transcription of iNOS mRNA in the macrophages after stimulation with taxol or LPS. These findings suggest that microtubules function in the posttranscriptional processes of iNOS protein expression rather than in the transcriptional process of iNOS mRNA and the synthetic process of NO molecules.

Animals↗
PubMed1996

Rapid detection of point mutations of the Neisseria gonorrhoeae gyrA gene associated with decreased susceptibilities to quinolones.

Mutations in the gyrA gene resulting in amino acid changes at Ser-91 and Asp-95 are significantly associated with decreased susceptibilities to quinolones in Neisseria gonorrhoeae. To detect these mutations, we developed a rapid and simple assay based on amplification of the region of the gyrA gene containing the mutation sites by PCR and digestion of the PCR product with a restriction enzyme. A naturally occurring HinfI restriction site was present in the region containing the Ser-91 codon, and an artificial HinfI restriction site was created in the region containing the Asp-95 codon by the method of primer-specified restriction site modification. The mutations generating alterations at Ser-91 and Asp-95 were detected as restriction fragment length polymorphisms of the PCR products digested with HinfI. Fifty-five clinical strains of N. gonorrhoeae were examined for mutations in the gyrA gene by this method. Mutations at Ser-91 and/or Asp-95 were detected in all the 31 strains in which the mutations had been confirmed by DNA sequencing. Our method allows simultaneous testing of a large number of strains and provides results within 8 h. This rapid and simple assay could be a useful screening device for genetic alterations associated with decreased susceptibilities to quinolones in N. gonorrhoeae and could facilitate epidemiological studies on clinical isolates of N. gonorrhoeae with decreased susceptibilities to quinolones.

Base Sequence↗
PubMed1996

Centromere protein B of African green monkey cells: gene structure, cellular expression, and centromeric localization.

Centromere protein B (CENP-B) is a centromeric DNA-binding protein which recognizes a 17-bp sequence (CENP-B box) in human and mouse centromeric satellite DNA. The African green monkey (AGM) is phylogenetically closer to humans than mice and is known to contain large amounts of alpha-satellite DNA, but there has been no report of CENP-B boxes or CENP-B in the centromere domains of its chromosomes. To elucidate the AGM CENP-B-CENP-B box interaction, we have analyzed the gene structure, expression, biochemical properties, and centromeric localization of its CENP-B. The amino acid sequence deduced from the cloned AGM CENP-B gene was established to be highly homologous to that of human and mouse CENP-B. In particular, the DNA binding and homodimer formation domains demonstrated 100% identity to their human and mouse counterparts. Immunoblotting and DNA mobility shift analyses revealed CENP-B to be expressed in AGM cell lines. As predicted from the gene structure, the AGM CENP-B in the cell extracts exhibited the same DNA binding specificity and homodimer forming activity as human CENP-B. By indirect immunofluorescent staining of AGM mitotic cells with anti-CENP-B antibodies, a centromere-specific localization of AGM CENP-B could be demonstrated. We also isolated AGM alpha-satellite DNA with a CENP-B box-like sequence with CENP-B affinity. These results not only prove that CENP-B functionally persists in AGM cells but also suggest that the AGM genome contains the recognition sequences for CENP-B (CENP-B boxes with the core recognition sequence or CENP-B box variants) in centromeric satellite DNA.

Amino Acid Sequence↗