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Biomedical subjects

S Taniguchi

Publications and source records attributed to S Taniguchi.

At least 253 records · Page 14Linked to original sources
PubMed1996

Amitriptyline inhibits the G protein and K+ channel in the cloned thyroid cell line.

We have reported that thyroid K+ channel is activated by extracellular application of the thyroid-stimulating hormone (TSH) using single channel recording method performed on cloned normal rat thyroid cell (FRTL-5) membrane. Treatment of dibutyryladenosine cyclic monophosphate (Bt2 cAMP) also activated the TSH-dependent K+ channel. These findings indicate that the thyroid K+ channel is activated through the TSH-adenosine cyclic monophosphate (cAMP)-protein kinase A system. We examined the effects of amitriptyline on TSH-guanosine triphosphate binding protein (G protein)-adenylate cyclase-cAMP-K+ channel system in the cloned normal rat thyroid cell line FRTL-5. Amitriptyline inhibited the cAMP production induced by TSH. Amitriptyline also inhibited the cAMP production induced by cholera toxin, indicating that amitriptyline inhibited the thyroid G protein. Amitriptyline had no effect on TSH-receptor binding and cAMP production by forskolin (adenylate cyclase stimulator). Amitriptyline inhibited the K+ channel activation by cAMP, indicating that the suppressing mechanism is not the inhibition of TSH receptor or G protein but the direct suppression of K+ channel. It was concluded that amitriptyline inhibited the thyroid G protein and K+ channel.

Amitriptyline↗
PubMed1996

Cobra venom factor stimulates anti-alpha-galactose antibody production in baboons. Implications for pig-to-human xenotransplantation.

Cobra venom factor (CVF) depletes complement and may therefore be of use in preventing the hyperacute rejection that follows discordant organ xenotransplantation. In two baboons studied, the intramuscular injection of CVF (0.25 mg/kg) was followed by a marked reduction in serum C3 and CH50, and serum cytotoxicity to pig kidney (PK15) cells. There was, however, a very rapid rise in the level of anti-alpha-galactose (alpha Gal) antibody, and a slower rise in anti-CVF antibody. A second intramuscular injection of CVF on day 14 was ineffective in reducing C3, CH50, and serum cytotoxicity. The major oligosaccharide of CVF is known to contain alpha Gal residues, which we suggest stimulate the major increase in anti-alpha Gal antibody level seen in the present study. In the clinical situation, this might lead to an increased immune response to a concomitantly transplanted pig organ.

Animals↗
PubMed1996

Distribution of platelet activating factor receptor mRNA along the rat nephron segments.

Platelet activating factor (PAF) receptor mRNA was semi-quantitated in microdissected rat nephron segments by the reverse transcription-polymerase chain reaction (RT-PCR). PCR primers were designed from two alternative splicing isoforms of rat PAF receptor cDNA; a homologue of human leukocyte PAF receptor cDNA (p172) and the other with a unique sequence in the 5'-noncoding region upstream of the splice acceptor site (p18). Only the expression of mRNA corresponding to p172 was detectable, which was most abundant in the glomerulus, followed in order by: proximal convoluted tubule > proximal straight tubule > outer medullary and cortical collecting duct, distal convoluted tubule > thick ascending limb of Henle's loop. These results suggest the potential physiological roles of PAF in the entire renal tubule as well as in the glomerulus.

Alternative Splicing↗
PubMed1996

Decreased expression of a single tropomyosin isoform, TM5/TM30nm, results in reduction in motility of highly metastatic B16-F10 mouse melanoma cells.

Tropomyosin is an actin-associated cytoskeletal protein expressed in muscle and non-muscle cells. There are several tropomyosin isoforms, and their cellular expression is known to be associated with transformation events caused by retroviral infection and chemical mutagens. We found that expression of a low-molecular weight tropomyosin isoform, TM5/TM30nm, was higher in a high-metastatic B16 mouse melanoma cell line, B16-F10, than in B16-F1, a low-metastatic mouse melanoma cell line. In order to determine whether this elevated level of TM5/TM30nm plays a role in malignant phenotype, B16-F10 cells were transfected with recombinant DNA containing antisense rat TM5/TM30nm cDNA linked to the human metallothioneinIIa promoter, which is inducible by heavy metals such as zinc and cadmium. When the stably transfected clones were treated with ZnSO4, decreased expression of TM5/TM30nm and reduction in cell motility, which is thought to be an indicator of cellular malignancy were observed. These findings suggest that TM5/TM30nm plays a fundamental role in regulating cell motility, which is essential for metastasis and invasion of tumor cells.

Amino Acid Sequence↗
PubMed1996

Effect of ionomycin on cell pH in isolated renal proximal tubules.

In isolated rabbit proximal tubules the addition of 2.0 microM but not 0.2 microM ionomycin induced a sustained increase in cell pH ([pH]i). This [pH]i response to 2.0 microM ionomycin was shown to be independent of several transporters such as Na+/H+ exchanger, Na(+)-HCO3- cotransporter, Cl-/HCO3- exchanger, or H(+)-ATPase. On the other hand, the removal of extracellular Ca2+ abolished the [pH]i increase or even induced a transient [pH]i decrease in the presence of ionomycin. These results are consistent with the induction of Ca2+/H+ exchange by ionomycin. Therefore Ca2+ ionophores should be used with caution as probes to estimate renal tubule functions.

Animals↗
PubMed1996

Novel FNR homologues identified in four representative oral facultative anaerobes: Capnocytophaga ochracea, Capnocytophaga sputigena, Haemophilus aphrophilus, and Actinobacillus actinomycetemcomitans.

Based upon DNA sequence data and positive immunochemical reactivity of expressed protein, novel homologues of the FNR family were identified in four representative oral facultative anaerobes: Capnocytophaga ochracea, Capnocytophaga sputigena, Haemophilus aphrophilus, and Actinobacillus actinomycetemcomitans. The similarity to E. coli FNR and to HlyX (itself 71% similar to E. coli FNR, while regulating expression of hemolysin operon in Actinobacillus pleuropneumoniae) was estimated from the deduced partial amino acid sequence to be, in the above order of tested species, 98, 98, 86, and 85%, and 75, 75, 88, and 88%, respectively. The phylogenetic relatedness indicates a rather closer link of HlyX to the FNR homologues from both pathogens, H. aphrophilus and A. actinomycetemcomitans. The possibility that the A. actinomycetemcomitans FNR homologue functions as a redox-sensing transcriptional factor to regulate, in addition to anaerobic respiration, microaerobic expression of the leukotoxin operon (ltx gene) is suggested.

Aggregatibacter actinomycetemcomitans↗
PubMed1996

Positive and negative regulation of cell proliferation through prostaglandin receptors in NIH-3T3 cells.

Among major eicosanoids and their analogs, prostaglandin (PG) F2 alpha > PGD2 > PGE1 > or = PGE2 > iloprost, a stable agonist of PGI2, dose-dependently stimulated DNA synthesis in quiescent NIH-3T3 cells. PGF2 alpha, PGD2, and PGE2, in that order, formed inositol phosphates and elevated intracellular Ca2+ ([Ca2+]i) but did not form cAMP nor inhibit forskolin-induced cAMP formation. Iloprost, PGI2, and PGE1 induced cAMP formation dose dependently with an ED50 of around 10(-7) M, and PGE2 at more than 10(-6) M did it. [3H]PGF2 alpha and [3H]PGD2 bindings membranes from NIH-3T3 cells were displaced in the order of PGF2 alpha > PGD2 > or = PGE2, while [3H]PGE2 binding was displaced by PGE2 > PGD2 > or = PGF2 alpha. Expression of mRNA encoding EP1 and EP4 (EP2) subtypes could be detected by reverse transcription- polymerase chain reaction using primers specific for EP1 and EP4 (EP2) cDNAs, but not that of EP3 subtype mRNA. The dose dependence of cAMP formation on iloprost and PGI2 and that of [Ca2+]i elevation on PGF2 alpha, D2, and E2 were similar to that of [3H]thymidine incorporation on the corresponding agonists. Fluprostenol (1 microM), a PGF2 alpha receptor agonist > 17-phenyl-trinor-PGE2 (1 microM), an EP1 receptor agonist stimulated [3H]thymidine incorporation, but an EP3 receptor agonist, ONO-AP-324 nor an EP4 (EP2) receptor agonist, 11-deoxy-PGE1 (1 microM) did not. Iloprost, dibutyryl cAMP, forskolin, or cholera toxin, when applied alone, enhanced [3H]thymidine incorporation, while they inhibited [3H]thymidine incorporation induced by submaximal concentrations of PGF2 alpha or epidermal growth factor (EGF), when applied within 12 hr after agonist stimulation. These results suggest that the proliferation of NIH-3T3 cells is stimulated by PGs via the PGF2 alpha receptor, EP1 subtype of PGE receptor, and the PGI2/PGE1 receptor through [Ca2+]i- and cAMP-dependent pathways, and that cAMP pathway negatively cross-talks with [Ca2+]i-or receptor tyrosine kinase-mediated DNA synthesis in a cell cycle-dependent manner.

3T3 Cells↗
PubMed1996

Adenocarcinoma in the anal canal associated with a fistula: report of a case.

Adenocarcinoma in the anal canal associated with an anal fistula is extremely rare, and in most cases its origin is difficult to ascertain because the primary sites have already been destroyed before any diagnosis of malignancy is able to be made. We report herein the case of a 62-year-old man found to have papillary adenocarcinoma with partial mucinous carcinoma associated with an anal fistula. The tumor was not exposed to the mucosal surface of the anal canal or rectum and an abdominoperineal resection was carried out. Macroscopic findings suggested that the tumor had developed from the anal fistula; however, the tumor showed a positive results when tested for O-acetylated sialic acids. This test also proved positive in the mucus of normal rectal mucosa, but not in the mucus of the anal glands. We speculated that the results of these tests may indicate that this tumor could have originated from the rectal mucosa, from where it migrated into the anal fistula.

Adenocarcinoma, Mucinous↗
PubMed1996

Liver cell adenoma in a young man with elevated serum PIVKA-II level.

A 21-year-old man was referred to our hospital because of a liver mass lesion detected by abdominal ultrasonography. He had received no hormonal treatment. Physical examinations revealed no abnormalities, and laboratory data, including hepatic function test results, were within normal ranges, with the exception of elevated levels of serum protein induced by vitamin K absence or antagonist (PIVKA)-II (2.2 AU/ml). Abdominal ultrasonography revealed a hyperechoic mass lesion measuring 10 x 10 cm, with hypoechoic areas located in the right posterior segment of the liver. A low-density area and a hypervascular area were detected in the right posterior segment of the liver by computed tomography and celiac angiography, respectively. As hepatocellular carcinoma could not be completely excluded, the tumor was resected. The tissue consisted of sheets of tumor cells with eosinophilic cytoplasm and round nuclei showing a thin trabecular pattern, and these histological findings indicated liver cell adenoma. After resection of the tumor, serum PIVKA-II returned to the normal level.

Adenoma, Liver Cell↗
PubMed1996

Butylated hydroxyanisole blocks the inhibitory effects of tumor necrosis factor-alpha on collagen production in human dermal fibroblasts.

Tumor necrosis factor-alpha (TNF-alpha) has been demonstrated to selectively decrease the production of type I and type III collagens in human dermal fibroblasts. The effects of the commonly used food antioxidants, butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), alpha-tocopherol, propyl gallate, superoxide dismutase (SOD), and catalase on TNF-alpha-induced growth enhancement and collagen metabolism were evaluated in the present study. BHA at concentrations of both 5 x 10(-5) and 10(-4) M inhibited cell proliferation and DNA synthesis induced by 10 ng/ml TNF-alpha in human dermal fibroblasts, while other antioxidants had minimal effects. Further, BHA (5 x 10(-5) M and 10(-4) M) significantly blocked TNF-alpha-induced decreases in collagen synthesis. These results suggest that antioxidants such as BHA may be involved in the modulation of collagen synthesis by TNF-alpha in human dermal fibroblasts.

Antioxidants↗
PubMed1996

Ganglioneuroblastoma of the thymus: an adult case with the syndrome of inappropriate secretion of antidiuretic hormone.

A 61-year-old woman was admitted to the hospital because of general fatigue. Laboratory examinations showed hyponatremia, plasma hypo-osmolarity, and inappropriate increased concentration of the plasma antidiuretic hormone (ADH) in the presence of concentrated urine. Magnetic resonance imaging revealed a mass lesion in the anterior mediastinum. An extended thymectomy was performed under the diagnosis of thymoma with the syndrome of inappropriate secretion of antidiuretic hormone (SIADH). Histologically the tumor was located in the thymic tissue and was diagnosed as ganglioneuroblastoma. Immunohistochemical studies showed the existence of ADH in the tumor cells. To the knowledge of the authors, this is the first case of ganglioneuroblastoma of the thymus with SIADH.

Female↗
PubMed1996

Lymphocytic aleukemic leukemia cutis.

A 21-year-old male patient had localized papules on the chest and arms. Biopsy of a lesion showed it to be a malignant lymphoid neoplasm, and immunohistochemical studies confirmed a lymphoblastoma origin. Aberrant lymphoid cells were noted in the cutaneous blood vessels, but simultaneous examination of the peripheral blood showed no evidence of leukemia. One month elapsed before observable leukemic cells were found in the blood and sternal marrow, confirming the diagnosis of acute lymphocytic leukemia. Examination of a cutaneous biopsy specimen led to early diagnosis of the disease.

Adult↗
PubMed1996

Effect of unsaturated fatty acids and antioxidants on immunoglobulin production by mesenteric lymph node lymphocytes of Sprague-Dawley rats.

The effect of UFA on Ig production by rat MLN lymphocytes was examined to clarify their influence on allergic reactions. A 4-h treatment at 1 mM inhibited the production of IgA, IgG, and IgM by the lymphocytes, but stimulated IgE production. The IgE production-stimulating activity became stronger with increasing number of carbon atoms and/or double bonds. However, no saturated fatty acid with carbon numbers from 12 to 18 affected IgE production by the lymphocytes. Hydrogen peroxide exerted Ig production-regulating activity similar to that of UFA, suggesting that the effect of UFA is at least partly due to oxidation products. Thus, the effect of antioxidants on the Ig production-regulating activity of arachidonic acid was examined. alpha-Tocopherol and BHT annulled the stimulation of IgE production by arachidonic acid, but ascorbic acid was not effective. The IgE production-enhancing activity of UFA was closely related to their oxidation rate in culture medium. These results suggest that UFA enhance the allergic reaction through the stimulation of IgE production and the inhibition of IgA production, and that hydrophobic antioxidants are partially effective to annul the adverse effect of UFA.

Animals↗