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Biomedical subjects

K Kano

Publications and source records attributed to K Kano.

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

[Postoperative MRI findings after cholesteatoma surgery].

This study was designed to show MRI findings of postoperative middle ear pathologies and to discuss the usefulness of Gadolinium-enhanced MRI in evaluating the postoperative state of cholesteatoma. Thirty-eight ears which underwent intact canal wall tympanoplasty for cholesteatoma were examined. Recurrent cholesteatoma was detected as an iso-intensity area on T1-weighted images with negative enhancement. Notably, residual cholesteatoma were generally depicted as a round iso-intensity area with negative enhancement. Residual cholesteatoma less than 5mm in diameter were, however, not generally detectable with our MRI scanner. Granulation tissue can be separated from cholesteatoma as an area with positive enhancement. Cholesterol granuloma shows a characteristic high signal pattern on both T1 and T2-weighted images. Hypovascular fibrous tissue and fluid collection may be depicted as a pattern similar to that of cholesteatoma. However, the signal is usually more homogeneous than that of cholesteatoma. We conclude that Gadolinium-enhanced MRI is useful for detecting postoperative cholesteatoma and avoiding unnecessary second-look operations after cholesteatoma surgery, by the canal-up procedure.

Adolescent↗
PubMed1994

Effect of oviductal epithelial cells on fertilization of pig oocytes in vitro.

The incidence of polyspermy is reduced by co-culture of pig oocytes with oviductal cells. It is not known whether the effect is due to soluble factors secreted into the medium. Oviductal epithelial cell monolayers and cell-conditioned media were prepared and their effects on fertilization of pig oocytes were examined. In vitro matured pig oocytes were inseminated with ejaculated boar spermatozoa at a concentration of 1x10(5) or 1x10(6) cells/ml and co-cultured in one of 5 culture systems: an oviductal epithelial cell monolayer, a fibroblast monolayer, an oviductal epithelial cell-conditioned medium, or a fibroblast-conditioned medium, and medium alone (modified-TCM199). In all 5 systems, the majority (range 85 to 100%) of the oocytes were penetrated by sperm. When oocytes were inseminated with spermatozoa at a concentration of 1x10(5) cells/ml, the percentages of monospermic oocytes were significantly higher in the oocytes co-cultured with oviductal epithelial cells and fibroblasts than that of the oocytes cultured without these cells. In contrast, when oocytes were inseminated with spermatozoa at a concentration of 1x10(6) cells/ml, the percentages of monospermic oocytes were significantly higher in the oocytes co-cultured with epithelial cells than those cultured with the fibroblasts and in the control medium. The suppressive effect on polyspermy was observed in the oviductal epithelial cells-conditioned medium when oocytes were inseminated with spermatozoa at both concentrations of 1x10(5) and 1x10(6) cells/ml. The effect was absent in the fibroblasts-conditioned medium. Moreover, the effect of the epithelial cells was maintained during the culture period, whereas the proportion of monospermic oocytes co-cultured with fibroblasts showed a gradual decrease, reaching 0% after 16 h. These results suggest that a soluble factor(s) derived from the oviductal epithelial cells decreased the number of spermatozoa penetrating the oocytes without suppressing the high rate of fertilization.

Journal Article↗
PubMed1994

Differential inhibition of eukaryotic DNA polymerases by halenaquinol sulfate, a p-hydroquinone sulfate obtained from a marine sponge.

Halenaquinol sulfate, a p-hydroquinone sulfate obtained from a marine sponge, inhibited the activity of eukaryotic DNA polymerases in varying degrees; the Ki values for DNA polymerases, alpha, beta, delta and epsilon were 1.3, 80, 17.5 and 2.0 microM, respectively, whereas it was less effective against E. coli DNA polymerase I. The inhibition occurred competitively with each of dATP and dTTP, but non-competitively with dCTP, dGTP and the template DNA. Thus, halenaquinol sulfate is demonstrated to be a potential inhibitor of DNA polymerases alpha and epsilon, and be a useful tool for analyzing the dNTP binding sites of DNA polymerases.

Animals↗
PubMed1994

Thyroid function in children with nephrotic syndrome.

The thyroid function of seven children with untreated nephrotic syndrome who had a normal serum creatinine concentration was compared with that of the same patients in remission and age-matched controls. There was a significant decrease in serum thyroxine (T4), tri-iodothyronine (T3) and thyroid-binding globulin (TBG) concentrations in untreated nephrotic children compared with the same patients in remission and age-matched controls. Most values for serum free T4, free T3 and thyroid-stimulating hormone (TSH) in the patients with nephrosis were within the normal range. However, the mean serum free T4 and free T3 concentrations were significantly (P < 0.05) lower in the untreated patients than in the same patients in remission, and the mean serum TSH concentrations were significantly (P < 0.05) higher in the untreated patients than in the same patients in remission. There were massive urinary losses of T4, T3, TBG, free T4 and free T3 in the untreated nephrotic children compared with the same patients in remission and age-matched controls. The daily urinary protein excretion showed a positive correlation with the urinary T4, T3, free T4, free T3 and TBG excretion. Furthermore, the urinary protein excretion showed a negative correlation with the serum T4, T3, free T4, free T3 and TBG levels. There was a negative correlation between serum albumin and serum TSH. These findings provide evidence of mild hypothyroidism in children with untreated nephrotic syndrome, partly because of losses of T4, T3, free T4, free T3 and TBG into the urine.

Child↗
PubMed1994

Effects of hyaluronic acid on the development of 1- and 2-cell porcine embryos to the blastocyst stage in vitro.

The purpose of this study was to evaluate the ability of hyaluronic acid to improve the development of 1- and 2-cell porcine embryos to the blastocyst stage in a simple medium. In Experiment 1, we confirmed the ability of Whitten's medium supplemented with 15 mg/ml BSA to support the development of porcine embryos to the blastocyst stage under our experimental conditions. Embryos collected from oviducts were cultured at 38.5 degrees C in an atmosphere of 5% CO(2) in humidified air up to 6 d. After 2 d of culture, 82 and 78% of embryos reached the 4-cell stage or beyond in TCM199 supplemented with 10% fetal calf serum (FCS) and in Whitten's medium with BSA, respectively. However, no embryo developed to the morula stage in TCM199 after 6 d of culture. On the other hand, 26 and 15% of embryos developed to the morula and the blastocyst stage in Whitten's medium, respectively. In Experiment 2, we determined whether supplementation of hyaluronic acid in Whitten's medium would improve the development of porcine embryos to the blastocyst stage. After 6 d of culture, development of the embryos to the blastocyst stage was best supported in Whitten's medium with 4 mg/ml BSA and 0.5 mg/ml hyaluronic acid (70%). The proportion of degenerated embryos was lower in the presence than in the absence of hyaluronic acid. These results indicate that the supplementation of Whitten's medium with hyaluronic acid improves the development of 1- and 2-cell porcine embryos to the blastocyst stage.

Journal Article↗
PubMed1994

HLA-B*3501-peptide interactions: role of anchor residues of peptides in their binding to HLA-B*3501 molecules.

Two HLA-B*3501 binding self-peptides, LPFDFTPGY (37F) and LPGPKFLQY (28H), were isolated from HLA-B*3501 molecules expressed by cultured human B lymphoid cells. Both sequences were consistent with previously reported motifs of HLA-B*3501 binding peptides which carry proline at position 2 and tyrosine at position 9 as anchor residues. Direct binding of these peptides to HLA-B*3501 molecules was quantitated by flow cytometry analysis of RMA-S cells. transfected with the HLA-B*3501 gene (RMA-S-B*3501). Both 37F and 28H peptides bound effectively to HLA-B*3501 molecules. Substitution of amino acids at position 2 and/or 9 of HLA-B*3501 binding peptides markedly reduced their binding to HLA-B*3501 molecules. These results indicate that two anchor residues, proline at position 2 and tyrosine at position 9 are critical in binding of peptides to HLA-B*3501 molecules. Insertion of up to four glycine residues at position 8 of the peptide 37F did not affect its binding affinity to HLA*3501 molecules. These results indicate that long peptides can effectively bind to HLA class I molecules provided that anchor residues are conserved.

Amino Acid Sequence↗
PubMed1994

Magnetic resonance imaging in patients with sudden deafness.

Although many theories on the etiology of sudden deafness have been proposed, the main pathological focus remains uncertain. In this study, MR examinations were performed on patients with unilateral sudden deafness to study the relationship between MRI findings and response to treatments, i.e. amidotrizoate, steroid, or both. In 7 out of 30 cases, the cochlea and/or the vestibule showed higher signal intensity on proton density and T2-weighted images on the diseased side (MRI positive cases). These findings suggest changes in the chemical composition of the perilymph and/or the endolymph, since proton density and T2-weighted images reflect water content. It appears that MRI positive sudden deafness is more difficult to cure even with the use of amidotrizoate or steroid than MRI negative sudden deafness. Amidotrizoate seems to be more effective in MRI negative sudden deafness. MRI would help us to further classify the etiology of sudden deafness.

Adolescent↗
PubMed1993

Separation of amino acid-oxazole derivatives of the redox coenzyme pyrroloquinoline quinone by capillary zone electrophoresis.

Condensation products (oxazole derivatives) from the reaction of the coenzyme pyrroloquinoline quinone (PQQ) with several alpha-amino acids were successfully separated by capillary zone electrophoresis. Addition of a certain organic solvent such as dimethyl sulphoxide to the electrolyte solution is essential for reproducible and complete separation. The organic modifier appears to prevent the oxazole derivatives from absorbing on the capillary wall. Product analysis of the condensation reactions of PQQ with amino acids was performed by this method and the mechanism is discussed briefly. PQQ-spiked bovine serum was also analysed. Unsubstituted type 1 oxazole derivative was predominantly detected. This result suggests that most of the PQQ in mammalian fluids, if any, exists as PQQ derivatives, probably as a type 1 oxazole derivative.

Amino Acids↗
PubMed1993

Characterization of topa quinone cofactor.

Electrochemical characterization of topa quinone (6-hydroxydopa quinone), the organic cofactor of copper-containing amine oxidases, has been performed with the aid of spectroscopy and ab initio energy minimization technique. Topa quinone exhibits a totally reversible cyclic voltammogram at a mercury electrode, which is ascribed to a two-step one-electron conversion between topa quinone and topa via topa semiquinone intermediate. Digital simulation of the reversible wave has afforded the separated estimation of each one-electron redox potential. The acid-dissociation constants of the phenolic hydroxyl groups of topa quinone, topa semiquinone and topa have been evaluated electrochemically and supported by electronic and electron spin resonance spectra. At pH 7.0, topa quinone is acid-dissociated and has a two-electron redox potential of 0.079 V vs. NHE coupled with a three-proton transfer. Redox catalytic activity of topa quinone for the oxidation of amines and NADH was not observed over conventional voltammetric time periods. Energy minimization calculation of acid-dissociated topa quinone anion indicates an intermediate electronic structure between the p- and o-quinone types with three almost equivalent carbonyl groups. The lack of the redox catalytic activity of free topa quinone appears to be attributable to the partial contribution of the p-quinone-type structure.

Benzoquinones↗
PubMed1993

Molecular analysis of HLA-B39 subtypes.

Serological studies have suggested the presence of a new HLA-B39 subtype (B39.2) in the Japanese population. To identify the new HLA-B39 subtype and compare it with an other HLA-B39 subtype (B39.1), the genes encoding HLA-B39.1 (B*39013) and B39.2 (B*3902) have been cloned from Japanese. We have sequenced these genes and completed the sequence of HLA-B39.1 (B*39011) gene from a Caucasian that was partially sequenced. Comparison of the sequence data revealed that B*3902 and B*39013 differ by three nucleotide substitutions which result in a two amino acids change at residues 63 and 67, while one silent substitution at codon 312 is found between B*39011 and B*39013. These results suggest that B*3902 has evolved from B*39013 rather than B*39011.

Amino Acid Sequence↗
PubMed1993

Structural analysis of HLA-B40 epitopes.

Two genes encoding HLA-B60 or HLA-B61 were cloned from Japanese and the exons of their genes were sequenced. One silent mutation was observed at the exon 1 between HLA-B60 (B*40012) and B*40011. Seven nucleotide substitutions were seen at the exon 3 between HLA-B61 (B*4006) and B*4002. Three substitutions at codon 95, CTC in B*4002 to TGG in B*4006, changed Leu in B*4002 to Trp in B*4006, while two substitutions at codon 97, AGC in B*4002 and ACG in B*4006, changed Ser in B*4002 to Thr in B*4006. Since B*4002 shares the epitope of alloantibodies specific for HLA-B61, two HLA-B61 subtypes are discriminated by two amino acid substitutions at residues 95 and 97. B*40012 and B*4006 differ by four amino acid substitutions on the beta sheet and five amino acid substitutions on the alpha 2 helix. Since the residues at the beta sheet seem hardly to affect the binding of alloantibody, it is suspected that the residues on the alpha 2 helix provide epitopes for alloantibodies that discriminate allospecificity between HLA-B60 and HLA-B61.

Amino Acid Sequence↗
PubMed1993

Lung cancer mortality among a cohort of male chromate pigment workers in Japan.

In 1975, five manufacturers of chromate pigment in Japan were examined in a study of the carcinogenicity of chromates. These companies were producing lead chromate, zinc chromate, molybdate orange and/or strontium chromate. The current study covers a cohort of 666 workers involved in the manufacture of chromate pigment for at least 1 year between 1950 and 1975. The workers were followed up for 15-40 years, until 1989. Many previous reports have found an excess lung cancer risk among workers involved in the manufacture of chromate pigments and chromate chemicals. In the current study, subjects were classified on the basis of years worked, years of observation, characteristics of company, type of work engaged in for the longest period of time, and involvement in the manufacture of zinc chromate. Mortality was compared with that of all Japanese males by means of the person-year method. The route of exposure was primarily inhalation through the respiratory system. None of the results showed statistically significant differences that would suggest an excess risk for malignant neoplasms, particularly lung cancer, among workers engaged in the manufacture of chromate pigment in Japan.

Cause of Death↗
PubMed1993

Gallstone formation in cholestanol-fed mice.

We examined the effect of cholestanol (5 alpha-dihydrocholesterol) on cholesterol and bile acid metabolism in BALB/c mice. After feeding 1% cholestanol in the diet for 14 months, gallstones composed of 55% cholesterol and 45% cholestanol developed in 20% of the mice and were associated with mucosal inflammation and serosal vessel thickening of the gallbladder. Cholestanol concentrations increased 42-fold in the serum (0.17 versus 0.004 mg/ml) and 18-fold in the liver (0.55 versus 0.03 mg/g) as compared with control mice, whereas cholesterol declined 20 and 26% in serum and liver, respectively. Hepatic microsomal HMG-CoA reductase activity, reflecting cholesterol synthesis, rose 51% (from 7.2 to 10.9 pmol/mg/min). In contrast, hepatic microsomal cholesterol 7 alpha-hydroxylase activity, the rate-determining enzyme for bile acid synthesis, was severely depressed as compared with control mice (0.9 versus 2.2 pmol/mg/min). Discontinuing cholestanol from the diet for 1 month reduced the elevated serum and liver cholestanol concentrations and restored hepatic HMG-CoA reductase and cholesterol 7 alpha-hydroxylase activities to normal. These results demonstrate that cholestanol is absorbed, replaces cholesterol in serum and liver, causes increased cholesterol synthesis, but inhibits bile acid synthesis. The combination of increased cholesterol synthesis with decreased bile acid formation promotes gallstone formation in cholestanol-fed mice.

Animals↗
PubMed1993

1-Alkyl-2,3-diacylglycerol synthesis in primary culture cells of guinea pig harderian gland.

Using a primary culture system of guinea pig Harderian gland cells, we investigated the metabolism of a unique lipid: 1-alkyl-2,3-diacylglycerol containing methyl-branched fatty acids. The cells were obtained by collagenase digestion, and cells with lipid-droplets were collected by two-step centrifugation. We cultured these cells, and examined their lipid and fatty acid compositions. The de novo synthesis of lipids in these cells was studied as to the incorporation of [1(2)-14C]acetate and [U-14C]glucose. The major lipid proved to be 1-alkyl-2,3-diacylglycerol, as in tissue, and it contained a large amount of methylbranched fatty acids specific to this gland. The incorporation of [14C]acetate and [14C]glucose into 1-alkyl-2,3-diacylglycerol in the cultured cells amounted to 79.7 and 88.2% of the total incorporation into the lipid fraction, respectively. The incorporation of [14C]acetate into fatty acids in the cultured cells was detected for the chain lengths of C14 to C25. The activities of glycerol-3-phosphate dehydrogenase in the cultured cells and Harderian gland were lower than that in adipose tissue. These results confirm that cultured cells reflect the lipid metabolism originating in the Harderian gland and show that this culture system can serve as one part of the armamentarium for further study of this unique lipid metabolism.

Acetates↗
PubMed1993

Inhibition of cell proliferation by a unique lysophosphatidic acid, PHYLPA, isolated from Physarum polycephalum: signaling events of antiproliferative action by PHYLPA.

The unique Physarum lysophosphatidic acid, PHYLPA, having a cyclopropane in the fatty acid moiety and a cyclic phosphate at C-2 and C-3 positions of the glycerol, inhibited proliferation of human fibroblast cells, TIG-3 and TIG-7, which were cultured in a chemically defined (serum-free) medium. The cells at S- and M-phases proceeded to G2- and G1-phases, respectively, and most of cells were arrested at G1- or G2-phase during PHYLPA treatment. The growth was recovered when PHYLPA was removed from the medium. In the presence of serum, PHYLPA did not show obvious inhibitory effects, indicating the existence of a factor(s) which neutralizes the antiproliferative activity of PHYLPA. PHYLPA elicited an increase in 3',5'-cyclic adenosine monophosphate (cAMP) in a biphasic fashion in fibroblast cells. It also elicited inositol phosphate accumulation, as well as a transient rise in cytoplasmic free Ca2+ ion.

Animals↗