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Biomedical subjects

M Chiba

Publications and source records attributed to M Chiba.

At least 253 records · Page 14Linked to original sources
PubMed1991

Rapid on-line precolumn high-performance liquid chromatographic method for the determination of benomyl, carbendazim and aldicarb species in drinking water.

A reversed-phase high-performance liquid chromatographic (HPLC) method has been developed for the determination of trace concentrations of benomyl, carbendazim, aldicarb, aldicarb sulphoxide and aldicarb sulphone in drinking water. A 10-ml sample of water is passed through a 3-cm precolumn, packed with 5-microns C8 sorbent, at a flow-rate of 5 ml/min. The HPLC system is then switched to an acetonitrile-water gradient elution program. The preconcentrated analytes are eluted from, and separated by, the 3-cm C8 precolumn and determined by UV absorption. The total analytical time is 25 min. The lowest detectable concentrations are in the range of 2.5 x 10(-9)-11.0 x 10(-9) g/ml for the five analytes investigated with 10 ml of sample.

Aldicarb↗
PubMed1991

A shuttle vector for analysis of illegitimate recombination in mammalian cells: effects of DNA topoisomerase inhibitors on deletion frequency.

To study the mechanism of illegitimate recombination in mammalian cells, we have developed a shuttle vector, pNK1, that contains three bacterial markers, amp (ApR), galK, and neo (KmR). The frequency of deletions occurring in autonomously replicating pNK1 DNA during the growth of monkey COS1 cells was measured by transfecting the plasmid into Escherichia coli cells and counting the number of galK- ApS double mutants among total KmR cells. This method allowed us to test the effects of topoisomerase inhibitors on deletion formation in mammalian cells. The DNA topoisomerase II (TopII) inhibitor, 4'-dimethylepipodophyllotoxin thenylidene-beta-D-glucoside (VM26), stimulated deletions in pNK1 DNA in monkey cells. Since VM26 does not inhibit the strand-break activity of TopII, but rather stabilizes an enzyme-DNA complex in which DNA is cleaved upon treatment with sodium dodecyl sulfate, it is implicated that TopII participates in the deletion process in mammalian cells.

Amsacrine↗
PubMed1991

Distribution of terbium and increase in calcium concentrations in organs of mice administered with terbium chloride.

To investigate the biological effects of terbium (Tb), male mice were intraperitoneally administered with TbCl3 at doses of 10, 50, or 250 mg Tb/kg. The Tb distribution in organs was determined after 18-20 h of injection by using a spectrofluorometer. The concentrations of Ca, Mg, Fe, and Zn in various organs were determined by atomic absorption spectrometer. Tb administered was mainly found in pancreas, seminal vesicles, spleen, liver, and testes. In each organ. Tb concentration increased according to the dosage of Tb. Contrary to our expectation, the increase of Ca concentration was obvious in organs in which high Tb concentrations were found. The correlation coefficients between Tb and Ca concentrations were from 0.863 in spleen to 0.986 in liver. In heart, lung, and blood. Tb was scarcely detected and insignificant change of Ca concentrations was observed. This result suggests that Tb induces increased Ca concentrations in organs.

Animals↗
PubMed1991

Liver abscess as the initial manifestation of colonic Crohn's disease: report of a case.

Liver abscess is a rare complication of Crohn's disease and in most of the reported cases, the diagnosis of Crohn's disease preceded that of liver abscess. We report herein a case in which a liver abscess was the initial clinical manifestation of Crohn's disease in a 36 year old man who presented with high fever and weakness. The diagnosis of liver abscess was established by abdominal ultrasonography, computed tomography and an arterial blood culture. The abscess was resolved with antibiotic therapy alone and during the drug therapy, a barium enema examination was performed which revealed a stricture at the transverse colon. Resection of the transverse colon was performed and macroscopic and microscopic examination of the resected specimen established the diagnosis of Crohn's disease. The liver abscess was thus speculated to be secondary to the inflamed bowel. Although rare, Crohn's disease should be included in the differential diagnosis of diseases causing liver abscess.

Adult↗
PubMed1991

Prolonged effects of hypofunction on the mechanical strength of the periodontal ligament in rat mandibular molars.

The ultimate loads required to extract three mandibular molars in the dissected jaw were examined after elimination of the antagonistic teeth for up to 64 days. The ultimate loads in the experimental first and second molars decreased rapidly in the first few days, while those in the third molar remained low during the same period in both experimental and control groups. The ultimate loads in all three molars of the experimental animals then increased gradually towards the end of the experiment at rates similar to those in controls. Maximum relative reductions of the ultimate load were observed within the first 8 days in all three molars. An increase in the length of roots was also found in all hypofunctional molars. Daily rates of root elongation ranged from 13 to 19 microns/day in the control and from 18 to 26 microns/day in the experimental molars during the whole experiment. The greatest value (80 microns/day) was obtained during the first 8 days in the third molars of both control and experimental animals. Thus the mechanical strength of the periodontal ligament estimated in vitro may be increased by the development of teeth and by non-functional occlusal contacts with the opposing gingiva-covered alveolar ridge deprived of its tooth crowns. The ligament of the third molar was apparently immature at the beginning of the experiment.

Animals↗
PubMed1991

Class II (HLA-DR, HLA-DP, and HLA-DQ) antigens on colonic epithelia in ulcerative colitis: a comparison between uneventful and intractable cases.

Class II antigens on colonic epithelia involved in ulcerative colitis (UC) with uneventful or intractable courses were investigated using an immunoperoxidase method. Twenty normal colonic mucosa served as normal controls. Nineteen specimens from 14 uneventful cases and 23 specimens from 12 intractable cases were studied. Normal colonic epithelia did not express class II antigens. In UC, there were no differences between uneventful cases and intractable cases in the frequencies of class II antigen expression, the distribution of class II antigen expression ratio, or the mutual relationship of the extent of expression of the three class II antigens on colonic epithelia. However, while the extent of expression of HLA-DR and HLA-DP antigens on the epithelia was positively correlated with the degree of inflammation in uneventful cases, there was no such correlation in intractable cases. These observations may suggest that the induction mechanisms of class II antigens on colonic epithelia in UC differ in uneventful and intractable cases.

Adolescent↗
PubMed1991

Metastatic potential of mouse skin carcinomas produced by different protocols of chemical carcinogenesis.

Squamous cell carcinomas (SCC) of the mouse skin were produced by three different protocols of chemical carcinogenesis, i.e., complete carcinogenesis with 7,12-dimethylbenz(a)anthracene (DMBA) two-stage carcinogenesis with DMBA as initiator, 12-O-tetradecanoyl-phorbol-13-acetate (TPA) as promoter and three stage carcinogenesis with DMBA, TPA and N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) as third-stage agent or progressor. Tumors were sequentially studied at weeks 38-52 of treatment. Although no significant differences in the rate of appearance of gamma-glutamyl transpeptidase (GGT) could be seen, a larger number of SCC produced by complete carcinogenesis protocols were GGT-negative. This coincided with the higher grade of malignancy of these tumors as evaluated by histopathology. In general terms high-grade tumors were seen more frequently in the complete carcinogenesis experiment than in the other two protocols. SCC produced by complete carcinogenesis also exhibited a markedly higher DNA index than the SCC from the other experimental groups. All three protocols were very effective in producing late metastasizing tumors, and no significant differences could be established in the incidence of spontaneous lung metastasis. This shows that, contrary to general knowledge, if adequately observed for more than 40 weeks, SCC of the murine skin is able to metastasize in the lung in approximately 30% of cases. Nevertheless, complete carcinogenesis-induced SCC were usually of higher histological grade, a proportion of these were GGT-negative and produced more multiple or diffuse metastases than the tumors induced by the multistage protocols.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1991

[A case of mediastinal cavernous hemangioma].

A case of mediastinal cavernous hemangioma was reported. An asymptomatic 6-year-old girl was discovered to have a mass in the left anterior superior mediastinum on a routine chest x-ray film. Computed tomograms demonstrated a mediastinal mass with calcification. Under a median sternotomy, a 10 x 9 x 5 cm mass was resected after dissecting the connections to the pericardium. As the mass surrounded the left phrenic nerve, the nerve was resected with the tumor. The histopathology was cavernous hemangioma. The calcification was not found in the vessels as the phleboliths but was showed in the interstitial tissues.

Calcinosis↗
PubMed1990

Development of an automated high-performance liquid chromatographic method for the on-line pre-concentration and determination of trace concentrations of pesticides in drinking water.

An automated reversed-phase high-performance liquid chromatographic (HPLC) method has been developed for the determination of trace concentrations of propoxur, carbofuran, carbaryl, propham, captan, chloropropham, barban and butylate in drinking water. A 100-ml of sample water is passed through a 3-cm precolumn, packed with 5-microns ODS sorbent, at a flow-rate of 5 ml/min. The HPLC system is then switched to an acetonitrile-water gradient elution program. The analytes, which are concentrated on the precolumn, are eluted and separated on a 25-cm C8 analytical column and determined by measuring the UV absorption at 220 nm. The resolution of analytes is excellent regardless of whether the elution from the precolumn is done unidirectionally or with backflushing. The precolumn can be used repeatedly for at least 30 samples without a significant decrease in efficiency. The total analytical time is 60 min. Tap, distilled, deionized, commercial spring and HPLC-grade waters were analyzed. The lowest detectable concentrations are in the range of 10.10(-12)-460.10(-12) g/ml for the eight pesticides with 100 ml of sample.

Captan↗
PubMed1990

Kinetic properties of the metabolism of imipramine and desipramine in isolated rat hepatocytes.

The metabolism of imipramine and desipramine was examined by using isolated rat hepatocytes. The enzyme systems having high-affinity-and-low-capacity and low-affinity-and-high-capacity kinetic properties were found to catalyze aromatic 2-hydroxylations of imipramine and desipramine, and aliphatic N-demethylation of imipramine, respectively. The Km and Vmax values for N-demethylation of imipramine (which formed desipramine) were about 5-10 and 5 times larger than those of both 2-hydroxylations respectively. A competitive inhibition between the 2-hydroxylations of imipramine and desipramine ("parallel pathway interaction") (Chiba M, Fujita S and Suzuki T, J Pharm Sci 77: 944-947, 1988), observed using liver microsomes, was found also in isolated hepatocytes. It was concluded that the characteristics of imipramine metabolism observed in liver microsomes were well reproduced in isolated rat hepatocytes.

Animals↗
PubMed1990

Pharmacokinetic correlation between in vitro hepatic microsomal enzyme kinetics and in vivo metabolism of imipramine and desipramine in rats.

A kinetic model capable of predicting the effect of the rate of intraportal imipramine infusion in rats on the steady-state concentrations of imipramine and its active metabolite, desipramine, was developed by using kinetic parameters obtained from in vitro studies. A nonlinear relationship was observed between steady-state concentrations of imipramine and desipramine (formed from imipramine) and the intraportal infusion rate of imipramine. Biliary and urinary excretion rates of both compounds were negligible compared with the corresponding infusion rate, and the free fractions of imipramine and desipramine in blood were constant over the concentration range used in this investigation. In vitro studies revealed that imipramine and desipramine 2-hydroxylations were mediated by a high-affinity and low-capacity (saturable) enzyme(s), while N-demethylation of imipramine (which formed desipramine) was mediated by a low-affinity and high-capacity (not saturable) enzyme(s). The adequate prediction of the steady-state concentrations of imipramine and desipramine by the proposed model was possible only after incorporating the mutual competitive inhibition between 2-hydroxylations of imipramine and desipramine, in addition to the incorporation of saturable kinetics of imipramine and desipramine 2-hydroxylations. Furthermore, the steady-state concentrations of desipramine were predicted to also be affected by the formation rate of desipramine, which increased nonlinearly with the increase in the rate of intraportal infusion of imipramine.

Animals↗
PubMed1990

Lymphoid cell subsets in colonic mucosa and HLA-DR antigens on colonic epithelia in colitis excluding ulcerative colitis and Crohn's disease.

Lymphoid cell subsets, including T cells as well as Ig-containing cells in the colonic mucosa and HLA-DR antigens on colonic epithelia, were examined in non-IBD colitis (colitis excluding ulcerative colitis (UC) and Crohn's disease) by the indirect immunoperoxidase staining method. Mouse anti-CD5, CD8, CD4, IgG, IgA1, IgA2, IgM, IgD, IgE, HLA-DR, and NuIa monoclonal antibodies were used as the first antibody. The results were compared to those of the normal controls and UC. T cell subsets in non-IBD colitis were almost similar to those of the controls and UC. The number of Ig-containing cells of all classes, except for IgA, tended to be increased in non-IBD colitis. In particular, both IgG- and IgE-containing cells were significantly increased compared to those in the controls. Compared to UC, IgG-containing cells were decreased in non-IBD colitis. Namely, in non-IBD colitis, as well as in UC, the change of Ig-containing cells (B cell lineage) was more pronounced than that of T cells. The frequency of the expression of HLA-DR antigens on colonic epithelia in non-IBD colitis was 70%, which was significantly higher than that in controls (0%), but significantly lower than that in UC (100%). Whether the differences in the number of IgG-containing cells, and the frequency of epithelial HLA-DR expression between non-IBD colitis and UC was due to the differences of the degree of local inflammation or due to the differences of the nature of the two diseases was not elucidated in this study.

Colitis↗
PubMed1990

Class II (HLA-DR, -DP, and -DO) antigens on intestinal epithelia in ulcerative colitis, Crohn's disease, colorectal cancer and normal small intestine.

Class II antigens in involved colonic epithelia of ulcerative colitis (UC), Crohn's disease (CD), colorectal cancer, and epithelia of normal small intestine were investigated using an immunoperoxidase method. Ten normal colonic mucosa served as normal controls. Ten specimens were studied for each group. Normal colonic epithelia did not express class II antigens. In colonic diseases; (1) with regard to the frequency and extent of class II antigens on epithelia. HLA-DR antigens were the most highly and greatly expressed, followed by HLA-DP and then HLA-DQ antigens. (2) The extent of HLA-DR and -DP, but not HLA-DQ, expression on epithelia of UC and colorectal cancer seemed to be positively correlated with the degree of mononuclear cell infiltration in the lesion. (3) The extent of class II antigen expression on colonic epithelia in CD was not related to the degree of mononuclear cell infiltration in the lesion. (4) The extent of HLA-DR and -DP expression on epithelia of colorectal cancer seemed to be positively correlated with increasing undifferentiation. In the normal small intestine, where HLA-DR antigens were physiologically expressed on epithelia. HLA-DQ antigens were not expressed. The heterogeneity among colonic diseases, and between the physiological and pathological status, may reflect differences in immunoregulation.

Adult↗