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Biomedical subjects

Y Kasai

Publications and source records attributed to Y Kasai.

At least 37 records · Page 2Linked to original sources
PubMed2001

Heterogeneity of neuronal nicotinic acetylcholine receptors in 5-HT-containing chemoreceptor cells of the chicken aorta.

The effects of nicotinic agonists and antagonists on whole-cell currents and 5-hydroxytryptamine (5-HT) release were studied in order to characterize nicotinic ACh receptors on the 5-HT-containing chemoreceptor cells of the chicken aorta. ACh, nicotine and dimethylphenylpiperazinium (DMPP) evoked concentration-dependent inward currents accompanied by increases in current noise at a holding potential of -70 mV. The peak amplitude of the current response to DMPP was 50% larger than that to either nicotine or ACH: Hexamethonium, alpha - bungarotoxin (alpha - BTX) and methyllycaconitine decreased nicotine-induced inward currents in a concentration-dependent manner. Although hexamethonium (0.1 mM) abolished the current response to nicotine (30 microM), a high concentration (1 microM) of alpha - BTX decreased it only by about 30% of the control response. Methyllycaconitine (0.1 microM) decreased the current response to nicotine to the same extent as did alpha - BTX whilst a high concentration (10 microM) abolished the response. ACh, nicotine and DMPP caused concentration-dependent increases in 5-HT output from the thoracic aorta which effect was blocked by hexamethonium (0.1 mM). Pre-treatment with alpha - BTX (1 microM) for 30 min reduced the output of 5-HT induced by ACh to 70% of the control response. It is suggested that neuronal nicotinic ACh receptors, sensitive and insensitive to alpha - BTX, are present on the chemoreceptor cells of the chicken aorta, the activation of which causes the release of 5-HT.

Acetylcholine↗
PubMed2001

Molecular detection of marine bacterial populations on beaches contaminated by the Nakhodka tanker oil-spill accident.

In January 1997, the tanker Nakhodka sank in the Japan Sea, and more than 5000 tons of heavy oil leaked. The released oil contaminated more than 500 km of the coastline, and some still remained even by June 1999. To investigate the long-term influence of the Nakhodka oil spill on marine bacterial populations, sea water and residual oil were sampled from the oil-contaminated zones 10, 18, 22 and 29 months after the accident, and the bacterial populations in these samples were analysed by denaturing gradient gel electrophoresis (DGGE) of PCR-amplified 16S rDNA fragments. The dominant DGGE bands were sequenced, and the sequences were compared with those in DNA sequence libraries. Most of the bacteria in the sea water samples were classified as the Cytophaga-Flavobacterium-Bacteroides phylum, alpha-Proteobacteria or cyanobacteria. The bacteria detected in the oil paste samples were different from those detected in the sea water samples; they were types related to hydrocarbon degraders, exemplified by strains closely related to Sphingomonas subarctica and Alcanivorax borkumensis. The sizes of the major bacterial populations in the oil paste samples ranged from 3.4 x 10(5) to 1.6 x 10(6) bacteria per gram of oil paste, these low numbers explaining the slow rate of natural attenuation.

Accidents↗
PubMed2001

Physicochemical analysis of the interaction between a metal ion and the metal-ion-binding motif in hammerhead ribozymes.

Hammerhead ribozymes have a metal-ion-binding motif in the conserved core region, and this motif can capture several kinds of metal ions. In order to determine what kind of metal ions can be recognized by the motif, we measured 2D 1H-1H NOESY spectra in the presence of various metal ions, such as Cd2+, Na+ and Co(NH3)6(3+) ions, as well as in the absence of these ions. We have completed the assignment of the resonances of the base protons and anomeric protons in all cases, and determined their chemical shift perturbations.

Binding Sites↗
PubMed2001

The TOL plasmid pWW0 xylN gene product from Pseudomonas putida is involved in m-xylene uptake.

The upper operon of the TOL plasmid pWW0 of Pseudomonas putida encodes a set of enzymes involved in the conversion of toluene and xylenes to their carboxylic acid derivatives. The last gene of the upper operon, xylN, encodes a 465-amino-acid polypeptide which exhibits significant sequence similarity to FadL, an outer membrane protein involved in fatty acid transport in Escherichia coli. To analyze the role of the xylN gene product, xylN on TOL plasmid pWW0 was disrupted by inserting a kanamycin resistance gene, and the phenotypes of P. putida harboring the wild-type and xylN mutant TOL plasmids were characterized. The growth of P. putida harboring the wild-type TOL plasmid was inhibited by a high concentration of m-xylene, while that of P. putida harboring the xylN mutant TOL plasmid was not. The apparent K(s) value for the oxidation of m-xylene in intact cells of the xylN mutant was fourfold higher than that of the wild-type strain, although the TOL catabolic enzyme activities in cell extracts from the two strains were almost identical. We therefore presume that the xylN gene product is a porin involved in the transport of m-xylene and its analogues across the outer membrane. Western blot analysis confirmed the localization of XylN in the outer membrane.

Bacterial Outer Membrane Proteins↗
PubMed2001

A comparative study of the fluoroquinolone antibacterial agents on the action potential duration in guinea pig ventricular myocardia.

We examined the effects of ten fluoroquinolone antibacterial agents, levofloxacin, sitafloxacin, trovafloxacin, ciprofloxacin, gemifloxacin, tosufloxacin, gatifloxacin, grepafloxacin, moxifloxacin and sparfloxacin, on action potentials recorded from guinea pig ventricular myocardia. Sparfloxacin prolonged action potential duration (APD) by about 8% at 10 microM and 41% at 100 microM. Gatifloxacin, grepafloxacin and moxifloxacin also prolonged APD at 100 microM by about 13%, 24% and 25%, respectively. In contrast, levofloxacin, sitafloxacin, trovafloxacin, ciprofloxacin, gemifloxacin and tosufloxacin had little or no APD-prolonging effect at concentrations as high as 100 microM. These findings suggest that there are differences in potency to prolong QT interval among the fluoroquinolones.

Action Potentials↗
PubMed2001

Release of dopamine and ATP from PC12 cells treated with dexamethasone, reserpine and bafilomycin A1.

The amounts and time courses of dopamine and ATP released from perfused PC12 cells were examined using a simultaneous on-line recording system. High KCl (60 mM) caused dopamine and ATP release with similar time courses. The relative amount of dopamine to ATP in the effluent was 9.5. In PC12 cells cultured with dexamethasone, reserpine or bafilomycin A1 for 2 days, these drugs did not affect increases of intracellular Ca2+ in response to high KCl. Dexamethasone doubled the amount of dopamine release induced by high KCl without changing the amount of ATP release. High KCl failed to cause dopamine release in reserpine-treated cells but evoked ATP release. Bafilomycin A1 decreased both high KCl-induced dopamine and ATP release. The ratio of released ATP to total adenine nucleotides and adenosine in response to high KCl was not changed by treatment with the drugs. These results suggest that dopamine and ATP are simultaneously released from secretory vesicles of PC12 cells, in which they are stored via different pathways. Similar to dopamine uptake into secretory vesicles, the H+-gradient across the vesicular membrane developed by vacuolar ATPase may play an important role in the vesicular uptake of ATP.

Adenosine Triphosphate↗
PubMed2001

AIS overexpression in advanced esophageal cancer.

We examined AIS status in digestive tract cancers and found that all eight esophageal cancer cell lines (100%) showed AIS/TA-AIS gene overexpression, whereas 1 of 12 (8%) gastric cancer and 0 of 14 (0%) colon cancer cell lines showed AIS/TA-AIS gene expression. We then confirmed that the AIS gene, not the TA-AIS gene, was dominantly expressed in esophageal cancers by reverse transcription-PCR. AIS protein was also expressed in AIS gene-positive cell lines. Subsequently, we tested AIS gene expression in paired esophageal normal tissues and cancers. Twenty-five of 39 (64%) primary esophageal cancers demonstrated an obviously higher expression of AIS gene compared to paired normal tissues. Moreover, high AIS gene expression was significantly associated with lymph node metastases in esophageal cancer (P = 0.0271). These results suggested that AIS may be useful as a marker for advanced esophageal cancer.

Aged↗
PubMed2001

[Clinical significance of anti-liver-type arginase autoantibody in blood of recipients after partial liver transplantation].

Autoantibody against human liver-type arginase was detected in blood of patients treated with partial liver transplantation and consisted of all subclasses of IgG, i.e., IgG1, IgG2, IgG3 and IgG4, and IgM. We newly constructed an ELISA system for the antibodies by the aid of arginase protein immunopurified from extracts of human liver tissues. Addition of 2.0 mol/l urea in 0.1 mol/l citrate buffer(pH 4.5) was effective for elimination of immunoglobulins, such as IgG and IgM, and rheumatoid factors adsorped non-specifically to liver-type arginase-autoantibody complexes on the plate. We found that, during a short period of about two months after operation, in successful cases, liver-type arginase increased, remarkably and repeatedly, in blood of recipients followed by elevation of IgM level within a week and also IgG2 level two or three weeks later. Thus the change in IgG2 level seemed to depend on those of the arginase and/or IgM. However, in unsuccessful cases, such fluctuation was not so clear as the successful cases. To be noteworthy was production of autoantibodies directed to liver-type arginase in blood of patients with liver injury although the arginase, as well as AST and ALT, is an enzyme which leaks out of liver tissue. Appearance of the autoantibodies in blood supports occurrence of liver injury, in part, in graft liver because the enzyme exists exclusively in the liver. Among immunoglobulins to liver-type arginase, IgG2 seemed to be the most helpful index to know rightly postoperative conditions of recipients of liver transplantation, and its measurement could be useful for long-term follow-up of the patients.

Arginase↗
PubMed2001

Molecular detection of p16 promoter methylation in the serum of patients with esophageal squamous cell carcinoma.

PURPOSE AND EXPERIMENTAL DESIGN: Recent evidence shows that the presence of promoter hypermethylation of tumor suppressor genes has been demonstrated in the serum DNA of patients with various cancers such as lung, liver, and head and neck cancer. We have examined promoter hypermethylation of the p16 gene in esophageal squamous cell carcinoma (SCC) using methylation-specific PCR to detect tumor DNA in the serum. RESULTS: Aberrant promoter methylation of the p16 gene was detected in 31 of 38 (82%) esophageal SCCs. Subsequently, we tested for promoter methylation in the paired serum DNA of 31 patients with a p16 alteration in the primary tumor. We found that 7 of these 31 (23%) patients had the same methylation changes in the serum DNA. CONCLUSIONS: This result indicates that promoter methylation present in the tumors of esophageal SCC patients can be detected in the serum of the same patient and that this approach can potentially be used for the screening and monitoring of the disease.

Carcinoma, Squamous Cell↗
PubMed2000

Specific association of estrogen receptor beta with the cell cycle spindle assembly checkpoint protein, MAD2.

Estrogen receptors (ERs) are ligand-activated transcription factors that regulate gene expression and cell growth. Two ERs now have been identified: ERalpha and the more recently discovered ERbeta. The physiological function of ERbeta remains unclear, but evidence from vascular injury studies and from ERbeta knockout mice suggests that ERbeta may be involved in the regulation of cellular proliferation. Here we show a direct and specific interaction between ERbeta and the cell cycle mitotic spindle assembly checkpoint protein, MAD2 (mitosis arrest-deficient 2). The ERbeta-MAD2 interaction was identified by screening of a yeast two-hybrid system vascular endothelial cell library with ERbeta and confirmed with glutathione S-transferase-fusion protein interaction studies. In contrast, ERalpha did not interact with MAD2 in either the two-hybrid system or in the protein-protein interaction experiments. Amino acids 173-208 in the hinge region of ERbeta were sufficient to mediate the interaction with MAD2 in the two-hybrid system and in glutathione S-transferase-fusion protein studies. These data identify a link between ERbeta and MAD2 of potential importance to regulation of the cell cycle and support a function of ERbeta distinct from the established role of ERs as transcription factors.

Amino Acid Sequence↗
PubMed2000

Effect of hormone replacement therapy on post-menopausal changes of lymphocytes and T cell subsets.

Immunosenescence is associated with the occurrence of lethal diseases, such as infection and malignancy. Since endocrinosenescence occurs simultaneously with immunosenescence, we determined whether or not lymphocytes and T cell subsets were altered in post-menopausal women. The ability of hormone replacement therapy (HRT) to reverse or modify the aberrations of the cell populations observed in elderly women was also examined. Thirty-nine untreated post-menopausal women and 39 women on HRT were studied. The proportions of lymphocytes and T cell subsets (helper, cytotoxic and immature T cells, and naive and memory/activated T cells) were determined by two color flow cytometry. Thirteen women were examined before and during HRT. At late post-menopause (> or = 30 years post-menopausal period), the proportion of peripheral blood lymphocytes showed a tendency to decline (p=0.06) compared with that at early (< or = 10 years) post-menopause. Significant (p<0.05) decrease in naive T cells and an increase in memory/activated T cells occurred at late post-menopause compared to those at early post-menopause. The percentage of lymphocytes in women on HRT was significantly (p<0.05) higher than that in untreated women at late post-menopausal stage. Furthermore, in a prospective study, HRT induced a significant (p<0.02) increase in the percentage of lymphocytes but showed no effect on the aberrations of naive and memory/activated T cells. HRT prevents the decline in the lymphocytes observed in post-menopausal women. However, HRT appears not to influence the observed alteration in T cell subsets.

Aged↗
PubMed2000

The ratio of splicing variants of MGC-24/CD164, a sialomucin, correlates with the metastatic potential of colorectal carcinomas.

MGC-24/CD164 is a sialomucin expressed in many normal and cancerous tissues. In humans, soluble and transmembrane forms of MGC-24 are produced by alternative splicing. The total MGC-24 RNA level was found to be lower in human colorectal carcinomas as compared with the adjacent normal mucosal tissues. Lower MGC-24 mRNA levels in colon carcinomas and in the adjacent normal mucosa epithelium correlate with lymphatic vessel invasion by the carcinoma. The ratio of the soluble form to the transmembrane form of the mRNA in colorectal carcinomas was determined by ribonuclease protection assay. Higher ratios were correlated with less venous invasion and less remote metastasis, which became evident during postoperative observation.

Alternative Splicing↗
PubMed2000

Comparison of the effects of add-back therapy with various natural oestrogens on bone metabolism in rats administered a long-acting gonadotrophin-releasing hormone agonist.

The hypoestrogenic state induced by gonadotrophin-releasing hormone agonist (GnRHa) has been shown to be effective in the treatment of oestrogen-dependent disorders but to induce bone loss. Adding back low doses of oestrogen in GnRHa therapy has been proposed to prevent bone loss. The purpose of this study is to assess the efficacy of add-back therapy with different natural oestrogens such as oestrone (OE(1)), oestradiol (OE(2)) and oestriol (OE(3)). Three-month-old female rats (250 g) were subcutaneously administered microcapsules of leuprorelin acetate in doses of 1 mg/kg of body weight every 4 weeks. GnRHa therapy lasted 16 weeks, and pellets of OE(1), OE(2) or OE(3) (0.5 mg/pellet, 60 day release), as an add-back agent, were implanted at 8 weeks of treatment. At the end of treatment, GnRHa alone decreased bone mineral density of the femur and lumbar vertebrae, and increased serum levels of bone metabolic markers such as alkaline phosphatase and osteocalcin levels. As for cancellous bone histomorphometry, GnRHa decreased bone volume while it increased osteoid volume, osteoid surface, eroded surface, mineral apposition rate and bone formation rate. All the oestrogens tested prevented these changes caused by GnRHa therapy. GnRHa induced a significant increase in body weight and a marked reduction in uterine weight, which was not observed in OE(1) or OE(2) add-back group. Body weight and uterine weight of the OE(3) add-back group were the same as those of the GnRHa group. These findings indicate that GnRHa induces high turnover bone loss which can be prevented by concomitant administration of natural oestrogens such as OE(1), OE(2) and OE(3) to the same extent. In addition, OE(3) is unique in that it is much less effective than OE(1) and OE(2) in blocking body weight gain and in promoting growth of uterine tissues. Because of its tissue-selective actions, OE(3) could be considered as one of the most appropriate oestrogens used for GnRHa add-back therapy.

Alkaline Phosphatase↗
PubMed2000

Collaborative work to evaluate toxicity on male reproductive organs by repeated dose studies in rats 14). Comparison of the effects of 2- and 4-weeks intravenous administration of etoposide.

In order to examine whether effects on male reproductive organs following 2-weeks administration of Etoposide (ET) are detectable, ET was administered intravenously once a week to rats for 2 and 4 weeks at 5 and 10 mg/kg/week. No deaths and no drug-related changes in body weight or in gross pathology were observed. However, decreased testis and/or thymus weights were noted. And histopathological examination revealed decrease and/or loss of spermatogonia and spermatocytes in the testes. It was evident that the target cells of the test article in the male reproductive organs are spermatogonia. Atrophy of the medulla and increase of immature lymphocytes in the cortex of the thymus and increase of fatty cells and increase of immature hematopoietic cells in the bone marrow were also apparent. The histological changes in the testis, thymus and bone marrow suggest that ET inhibits cellular mitosis which reflects its mechanism of action as an anticancer agent. It is concluded that effects of ET on male reproductive organs can be detected by histopathological examination of the testes after 2-weeks repeated administration.

Animals↗
PubMed2000

[Interim report on JFMTC Study no. 21 on the effectiveness of UFT as an adjuvant therapy for semi-advanced cancer of the stomach].

This interim report, for findings as of May, 1998, covers data on 435 gastrectomized patients with semi-advanced stomach cancer collected from 144 institutions between November, 1993 and March, 1996. The active arm of the study involved CDDP i.p. administration of 70 mg/m2 at the time of resective surgery, followed by UFT oral administration for one year at 3-4 capsules daily. A randomized control involved no adjuvant therapy after CDDP i.p. administered as in the active arm. The results obtained indicated no significant difference between the groups in terms of 3 year survival or disease free survival rates. Reports appearing elsewhere have suggested that 3-4 capsules/day of UFT may be insufficient to reach the threshold of the effective tissue level, and that 6 capsules may be necessary to obtain the expected results. (JFMTC: Japanese Foundation of Multidisciplinary Treatment for Cancer).

Antineoplastic Combined Chemotherapy Protocols↗
PubMed2000

[Interim report of JFMTC study no. 20 on the effectiveness of high dose CDDP plus 5-FU regimen as an adjuvant therapy for far-advanced cancer of the stomach].

This interim analysis of the JFMTC study as of May, 1998 covers 321 gastrectomized patients with far-advanced stomach cancer from 135 institutions between November, 1993 and March, 1996. The intensive therapy group (I-group) received CDDP i.p. administration on resective surgery with 70 mg/m2 followed by CDDP i.v. of 80 mg/m2 (day 1, i.v.), accompanying 5-FU of 350 mg/m2/day (day 1-5, c.v.i.) in the 4th, 8th and 12th weeks. The I-group was randomly compared with the standard therapy group (S-group) of MMC of 6 mg/m2 i.v. in the 4th, 8th and 12th weeks and UFT of 3-4 capsules daily for postoperative one year. The results obtained were that 1. adverse reactions were found more in the I-group than in the S-group, particularly notable in the decrease in blood cells, loss of appetite and nausea/vomiting, and incidence of grade 3 or more being 13% (neutrophile leukocytes), 26% and 21%, respectively; 2. there was no significant difference between I- and S-groups in terms of 3-year survival or disease-free survival rates. (JFMTC: Japanese Foundation of Multidisciplinary Treatment for Cancer).

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1999

Regulation of myosin phosphatase by a specific interaction with cGMP- dependent protein kinase Ialpha.

Contraction and relaxation of smooth muscle are regulated by myosin light-chain kinase and myosin phosphatase through phosphorylation and dephosphorylation of myosin light chains. Cyclic guanosine monophosphate (cGMP)-dependent protein kinase Ialpha (cGKIalpha) mediates physiologic relaxation of vascular smooth muscle in response to nitric oxide and cGMP. It is shown here that cGKIalpha is targeted to the smooth muscle cell contractile apparatus by a leucine zipper interaction with the myosin-binding subunit (MBS) of myosin phosphatase. Uncoupling of the cGKIalpha-MBS interaction prevents cGMP-dependent dephosphorylation of myosin light chain, demonstrating that this interaction is essential to the regulation of vascular smooth muscle cell tone.

Amino Acid Motifs↗