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Biomedical subjects

K Tsuji

Publications and source records attributed to K Tsuji.

At least 343 records · Page 19Linked to original sources
PubMed1994

Increased calcium-channel currents of pancreatic beta cells in neonatally streptozocin-induced diabetic rats.

Using a whole-cell patch-clamp technique, voltage-dependent Ca(2+)-channel activities were found to be increased in cultured single beta cells isolated from neonatally streptozocin-induced diabetic rats (NSZ rats). The current-voltage relationship and inactivation time course of Ba2+ currents via L-type Ca2+ channels were indistinguishable between NSZ and control rats. However, the current density observed in NSZ rats was significantly greater than that in control rats. Ba2+ currents via T-type Ca2+ channels were also found to be enhanced in NSZ beta cells. The insulin-secretory capacity of cultured pancreatic islets in response to a depolarizing stimulus (20 mmol/L arginine or 30 mmol/L KCl) in the presence of 11.1 mmol/L glucose was augmented in NSZ rats, whereas that in response to 11.1 and 16.7 mmol/L glucose alone was significantly reduced. It is concluded that the impaired insulinotropic action of glucose in beta cells in NSZ rats is not due to reduced activity of voltage-dependent Ca2+ channels. The fact that insulin secretion induced by a depolarizing stimulus was enhanced in NSZ rats may be related to the augmented activity of the voltage-dependent calcium current found in NSZ beta cells.

Animals↗
PubMed1994

A marked increase in intracellular Ca2+ concentration induced by acromelic acid in cultured rat spinal neurons.

Acromelic acid, a kainate derivative of natural origin, markedly increased intracellular Ca2+ concentration ([Ca2+]i) in cultured rat spinal neurons in a concentration dependent manner; the half effective concentration (EC50) was 1.3 microM. Acromelic acid was more potent in increasing [Ca2+]i than any other glutamate receptor agonists tested, and the rank order of the activity was as follows: acromelic acid > alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) > kainate > N-methyl-D-aspartate (NMDA) > L-glutamate. Acromelic acid did not increase the [Ca2+]i in a Ca(2+-)free medium. 2,3-Dihydroxy-9-nitro-7-sulfamoylbenzo(F)quinoxaline (NBQX) completely inhibited the [Ca2+]i increase induced by acromelic acid. These results suggest that the [Ca2+]i increase was not through Ca2+ mobilization from intracellular stores but due to Ca2+ influx mediated by the activation of non-NMDA receptors. Acromelic acid increased the [Ca2+]i in rat hippocampal neurons as well; however, the EC50 (6 microM) was considerably higher than that in spinal neurons. The marked increase of [Ca2+]i in cultured spinal neurons would explain, at least in part, the earlier findings that systemic administration of acromelic acid causes selective degeneration confined to lower spinal interneurons.

Animals↗
PubMed1994

A clean-up method for analysis of trace amounts of microcystins in lake water.

A clean-up method using high performance liquid chromatography (HPLC) and liquid chromatography/mass spectrometry (LC/MS) was developed to pursue trace amounts of microcystins in lake water. The method consisted of the combined usage of octadecyl silanized (ODS) silica gel and silica gel cartridges. In the first clean-up process, the retention behavior of microcystin RR on ODS silica gel cartridge was carefully observed together with microcystin LR, and 10% water-methanol was chosen as the best solvent system to elute microcystins from the ODS silica gel cartridge. Because many impurities still remained in the desired fraction from the raw water even after the clean-up with ODS silica gel, an additional clean-up process was developed using various cartridges. As a result of extensive experiments, the second clean-up process using silica gel cartridge was established, and the impurities were effectively eliminated. The present method including a tandem cartridge system allowed a precise analysis of microcystins in water samples from three different lakes at a 0.02 ppb level.

Chromatography, High Pressure Liquid↗
PubMed1994

Quantification of serum-soluble HLA class I antigens in patients with gastric cancer.

The amount of sHLA-I in serum was examined in 74 patients with gastric cancer and 15 normal healthy controls. For mAbs, W6/32 specific for HLA-A, -B, -C, and biotin IOT2 specific for HLA class I associated with beta 2 microglobulin, were used to determine the values of sHLA-I using an ELISA. The patients in stage-IV gastric cancer showed lower values of sHLA-I (445.4 +/- 247.1 ng/ml) than those in stage I (725.9 +/- 575.8 ng/ml), stage II (752.8 +/- 255.0 ng/ml), and normal controls (868.9 +/- 715.0 ng/ml) (P < 0.05). In analysis of the patients with HLA-A24, the allele that has been reported to secrete more sHLA-I than other alleles, the results were nearly the same. These results suggest that the secretion of sHLA-I is low in patients with very advanced cancer. However, there was no correlation between the sHLA-I level and the metastasis or prognosis in longitudinal studies in 11 patients.

Adult↗
PubMed1994

Developmental change in activity of red cell porphobilinogen deaminase and its electrophoretic variant in the Japanese population.

The activity of porphobilinogen deaminase (PBGD), an enzyme whose partial deficiency is associated with acute intermittent porphyria (AIP), changes during development. Little is known about the postnatal change of PBGD activity and the prevalence of its electrophoretic variant in the Japanese population. The activity of PBGD was measured fluorometrically in 194 infants aged 0-12 months, while isoelectric focusing of PBGD was performed in 400 healthy Japanese adults aged 20-45 years and 30 children with various hematological disorders aged 1-15 years. The PBGD level was 1.9 times higher in the neonates than in the adults, decreased abruptly during the first month of life, and reached the adult level at the age of 9 months. None of the 400 healthy Japanese adults and the 30 children with hematological disorders showed any electrophoretic variant. These results suggest that there is no need to consider any polymorphism in the gene dose study of PBGD and that the biochemical screening of AIP is applicable to since the late infancy.

Adult↗
PubMed1994

Interchange trisomy 9 due to maternal t(6;9) translocation.

The occurrence of interchange trisomy due to a 3:1 malsegregation has been documented in only a few cases with trisomy 21. We describe the first case of interchange trisomy 9 due to a maternal t(6:9) translocation. The patient, a boy neonate who died immediately after birth, had intra-uterine growth retardation, specific craniofacial features including microcephaly with a high forehead, low-set ears, upslanting short palpebral fissures, microphthalmia, bulbous nose and micrognathia, cryptorchidism, cystic kidney and various skeletal anomalies. His phenotype was consistent with that of the trisomy 9 syndrome. Cytogenetic analysis showed his karyotype of 47,XY,-6, + der(6), + der(9)t(6;9)(q27;q21.1)mat. The present report indicates that a very rare interchange mode of a 3:1 segregation can give rise to a live birth with full trisomy 9 in female carriers with reciprocal translocations involving the proximal long arm of chromosome 9.

Adult↗
PubMed1994

Resin glycosides. XXI. Tuguajalapins I-X, the resin glycosides having long-chain fatty acid groups from the root of Merremia hungaiensis.

Ten resin glycosides (jalapins) named tuguajalapins I-X were isolated from the root of Merremia hungaiensis. Their structures have been determined on the bases of chemical and spectral data. Unlike the jalapins so far reported, all of their acyl groups consist of two or three long-chain fatty acids, that is, palmitic, stearic and/or arachidic acids.

Carbohydrate Sequence↗
PubMed1994

Synthesis and antibacterial activities of 2-oxaisocephems.

A series of 2-oxaisocephems with a thio-substituted methyl group at the 3-position and a 2-aminothiazol-4-yl moiety at the 7-position was synthesized via benzyl 3-acetyloxymethyl-7-azido-8- oxo-1-aza-4-oxabicyclo[4.2.0]oct-2-ene-2-carboxylate (2), derived from benzyl acetoacetate (1). The new 2-oxaisocephems were tested for antibacterial activities. Among them, the derivatives having a [2-(2-aminothiazol-4-yl)-2- (Z)-cyclopentyloxyimino]acetamido group at the 7-position characteristically showed potent activities against gram-positive bacteria including methicillin-resistant Staphylococcus aureus (MRSA) and Enterococcus faecalis as compared with cefuzonam and cefmenoxime, which are third-generation cephalosporins.

Anti-Bacterial Agents↗
PubMed1994

Study on the bile salt, sodium scymnol sulfate, from Rhizoprionodon acutus. IV. Structures of chimaerol and sodium chimaerol sulfate in the bile of Lamna ditropis and Rhizoprionodon acutus.

Sodium chimaerol sulfate (1) was isolated from the bile of Lamna ditropis and Rhizoprionodon acutus by chromatography on silica gel and Sephadex LH-20, together with sodium scymnol sulfates, (24R,25S)- and (24R,25R)-(+)-3 alpha,7 alpha,12 alpha,24,26-pentahydroxy-5 beta-cholestan-27-yl sodium sulfates (3 and 4) and 3, respectively. On acid hydrolysis, compound 1 afforded chimaerol (2), which was identified as (24R,25R)-(+)-5 beta-cholestane-3 alpha,7 alpha,12 alpha,24,26-pentol by direct comparison with an authentic sample, prepared by reduction of (24R,25S)-(+)-24,26-epoxy-5 beta-cholestane-3 alpha,7 alpha,12 alpha,27-tetrol (5) with LiAlH4. The structure of 1 was concluded to be (24R,25R)-(+)-3 alpha,7 alpha,12 alpha,24-tetrahydroxy-5 beta-cholestan-26-yl sodium sulfate, based on the chemical transformation and spectral data.

Aluminum Compounds↗
PubMed1994

Study on pharmacological effect of bile salts, sodium scymnol sulfate, from Rhizoprionodon acutus. I. Effect of scymnol, chimaerol and sodium scymnol sulfate on cerebral anoxia.

The effects of scymnol, chimaerol and sodium scymnol sulfate, prepared from the bile of Rhizoprionodon acutus, on cerebral anoxia were investigated in experimental models of hypoxia, ischemia and histotoxic anoxia in mice. Scymnol, at a dose of 100 mg/kg, showed a significant protective action against cerebral anoxia in all of the models studied and significantly increased the partial oxygen pressure of the arterial blood. The anti-anoxic activity of scymnol was found to be slightly greater than that of idevenone. A similar protective effect of sodium scymnol sulfate was seen at doses higher than 100 mg/kg. The survival time on hypoxia was significantly prolonged in the animals pretreated with chimaerol.

Animals↗
PubMed1994

Studies on active substances in herbs used for hair treatment. I. Effects of herb extracts on hair growth and isolation of an active substance from Polyporus umbellatus F.

The effects of methanol extracts of 80 herbs on hair growth were investigated, using normal C3H/He mice from which telogen hair on the back had been removed. Eighteen of the extracts apparently promoted hair regrowth on the mice. As one of active principles in Polyporus umbellatus F., 3,4-dihydroxybenzaldehyde was isolated by column chromatography on Amberlite XAD-2, Sephadex LH-20 and silica gel.

Animals↗
PubMed1994

Quadruple cancers in a human T-cell leukemia virus type 1 carrier.

Human T-cell leukemia virus type 1 (HTLV-1) infection is considered to contribute to the risk of malignancies other than adult T-cell leukemia. We report a 64-year-old male HTLV-1 carrier who developed quadruple malignancies such as cancer of the urinary bladder, skin, larynx and liver.

Basal Cell Carcinoma↗