Search PubMed⌕ Search

Biomedical subjects

H Ishida

Publications and source records attributed to H Ishida.

At least 487 records · Page 27Linked to original sources
PubMed1995

Determination of 25-hydroxyvitamin D3 in human plasma using a non-radioactive tetranorvitamin D analogue as an internal standard.

A convenient non-radioactive method for assaying plasma 25-hydroxyvitamin D3 is described. The method uses 22-hydroxytetranorvitamin D3 as an internal standard and includes two-step liquid- and solid-phase extractions and quantification by normal-phase HPLC. The intra- and inter-assay coefficients of variation were 2.2% and 2.4%, respectively, and the analytical recovery of 25-hydroxyvitamin D3 added to plasma was quantitative. Assay linearity was obtained in the range 0.5-4.0 ml of plasma. When compared with the method employing a radioactive 25-hydroxyvitamin D3 tracer, the correlation coefficient was 0.990 (slope 0.999 and intercept 1.19 ng/ml).

Adult↗
PubMed1995

Lethal shock is inducible by lipopolysaccharide but not by superantigen in mice with retrovirus-induced immunodeficiency syndrome.

The retrovirus-induced murine AIDS (MAIDS) shares many features with human AIDS. Here, we examined the susceptibility of mice with MAIDS to staphylococcal enterotoxin-triggered shock. Following sensitization with D-galactosamine (D-Gal), mice with MAIDS were resistant to the otherwise lethal effect of superantigen staphylococcal enterotoxin A (SEA). Peak IL-2 levels in these mice after D-Gal/SEA challenge were 10-fold higher than those in uninfected controls, and concurrently, IL-10 levels rose markedly with reduction of circulating IL-1 and IFN-gamma. Treatment with neutralizing anti-IL-10 mAb before D-Gal/SEA challenge led to increased IFN-gamma levels in mice with MAIDS, and resulted in a dose-dependent mortality. In contrast, mice with MAIDS were more susceptible to the toxicity of bacterial endotoxin LPS than were uninfected controls. Administration of 100 micrograms LPS alone induced 50% lethality in mice infected with MAIDS virus 8 wk previously but not in uninfected controls. Administration of 10 micrograms LPS caused acute shock in D-Gal-sensitized mice with MAIDS. Peak TNF-alpha levels in these mice after LPS challenge were increased more than 10-fold, whereas IL-10 levels were one-third of those after SEA challenge. Moreover, serum IFN-gamma was undetectable in uninfected controls and rose to 1063 +/- 483 pg/ml in mice with MAIDS 4 h after LPS challenge. These results suggest that aberrant profiles of cytokine production are crucial in determining fatal outcome in these two types of septic shock in MAIDS.

Animals↗
PubMed1995

Synthesis of sialyl Lewis X ganglioside analogues containing modified L-fucose residues.

Sialyl Le(x) ganglioside analogues containing 2-epi-, 2,3-di-epi-, 4-epi-, and 2-O-methyl-L-fucose in place of the L-fucose residue have been synthesized. Glycosylation of 2-(trimethylsilyl)ethyl O-(2-acetamido-4,6-O-benzylidene-2-deoxy-beta-D-glucopyranosyl)-(1-->3)- 2,4,6- tri-O-benzyl-beta-D-galactopyranoside with the methyl 1-thioglycoside derivatives of the respective fucose analogues, using dimethyl(methylthio)sulfonium triflate (DMTST) as a promoter, gave the corresponding protected 2-(trimethylsilyl)ethyl deoxy-alpha-L-hexopyranosyl-(1-->3)-O-(2- acetamido-2-deoxy-beta-D-glucopyranosyl)-(1-->3)-beta-D-galactopyrano sid es. These were transformed by reductive ring-opening of their benzylidene acetal groups into the glycosyl acceptors. Dimethyl (methylthio)sulfonium triflate-promoted glycosylation of these compounds with methyl O-(methyl 5-acetamido-4,7,8,9-tetra-O-acetyl-3,5-dideoxy-D-glycero-alpha-D-galacto -2- nonulopyranosylonate)-(2-->3)-2,4,6-tri-O-benzoyl-1-thio-beta-D- galactopyranoside afforded the desired pentasaccharides, which were converted via reductive removal of their benzyl groups, O-acetylation, selective removal of the 2-(trimethylsilyl)ethyl group, and reaction with trichloroacetonitrile, into the corresponding alpha-tri-chloroacetimidates. Glycosylation of (2S,3R,4E)-2-azido-3-O-benzoyl-4-octadecene-1,3-diol these in the presence of boron trifluoride etherate afforded the expected beta-glycosides, which were transformed in good yields, via selective reduction of the azido group, coupling with octadecanoic acid, O-deacylation, and deesterification, into the target gangliosides. The 2-(trimethylsilyl)ethyl glycosides of sialyl Le(x) oligosaccharides containing modified fucose were also prepared from the intermediates of the ganglioside synthesis.

Carbohydrate Sequence↗
PubMed1995

Endogenous interleukin 10 prevents apoptosis in macrophages during Salmonella infection.

To elucidate the biological roles of endogenous interleukin 10 (IL-10) in macrophage responses during bacterial infection, we examined in vitro effects of neutralizing IL-10 by anti-IL-10 monoclonal antibodies (mAb) on apoptosis of the peritoneal macrophages following Salmonella choleraesuis infection. Marked increments of TNF-alpha production were observed in the culture supernatant later than 6 h after in vitro culture with anti-IL-10 mAb. These macrophages succumbed to apoptosis at this stage accompanied by marked increment of IL-1 release, despite the expression of higher amount of endogenous heat shock protein 70, an inhibitor of TNF-alpha-mediated apoptosis. These results suggest that endogenous IL-10 plays an essential role in protection of Salmonella-infected macrophages from autocrine suicide caused by excessive production of TNF-alpha after killing of Salmonella.

Animals↗
PubMed1995

Synthetic and structural studies of alpha-sialyl-(2-->6) and alpha-sialyl-(2-->3) 1-deoxynojirimycin derivatives potentially useful for biomedical applications.

Suitably protected derivatives of 1-deoxynojirimycin (1,5-dideoxy-1,5-imino-D-glucitol, DNJ) and its D-galacto analog were coupled with 2-thioglycosides of N-acetylneuraminic acid. The resulting disaccharides were converted into a variety of alpha-sialyl-(2-->6)-and alpha-sialyl-(2-->3)-DNJ derivatives, including the cyclic lactams 6-O-(5-acetamido-3,5-dideoxy-D-glycero-alpha-D-galacto-2-nonulopyrano sylono- 1',5-lactam)-1,5-dideoxy-1,5-imino-D-glucitol and -D-galactitol. The structural features of the synthetic compounds were investigated by ion-spray mass and 1H NMR spectrometry. The 1C4 conformation of N-tert-butoxycarbonyl-DNJ, a synthetic intermediate having the gluco configuration, was confirmed by X-ray crystallography.

1-Deoxynojirimycin↗
PubMed1995

Age-dependent changes in response of rat prostatic tissues to isoproterenol and forskolin: changes with sexual maturation in function of G proteins.

Developmental changes in the responses of rat ventral prostate to isoproterenol (IPR) and forskolin (F) were studied in relation to the function of beta-adrenoceptor-adenylate cyclase system. The response of adenylate cyclase in the tissues to IPR at 10(-7)M and above was steadily enhanced after birth and reached a maximum at 12 weeks, followed by a decrease with age. In contrast, the response of the enzyme to F at 10(-7)M and above was highest at 2 weeks, but thereafter decreased. The changes in the response of the enzyme to IPR coincided with changes in the beta-adrenoceptor density and the binding ability of GTP binding proteins (G proteins) to GTP. The ADP-ribosylation of inhibitory G proteins (Gi proteins) catalyzed by pertussis toxin (IAP) decreased 70% in the tissues from 4 to 8 weeks, and then maintained this level. On the other hand, the ADP-ribosylation of stimulatory G proteins (Gs proteins) catalyzed by cholera toxin (CT) increased only 20% in the tissues from 2 to 4 weeks. Thus, the ratio of ADP-ribosylation of Gs to that of Gi significantly increased from 4 weeks, reaching a maximum at 12 weeks, but thereafter decreased gradually with age. These changes paralleled those in the function of G proteins and the response of the enzyme to IPR. It is suggested that the rapid and marked decrease in apparent level of Gi proteins in the rat ventral prostate after 4 weeks may have a key role in controlling the function of the beta-adrenoceptor-adenylate cyclase system in the tissues.

Adenosine Diphosphate Ribose↗
PubMed1995

Mechanism of isoproterenol-induced heterologous desensitization of mucin secretion from rat submandibular glands. Regulation of phosphorylation of Gi proteins controls the cell response to the subsequent stimulation.

Short-term treatment of rat submandibular tissues with 10 microM isoproterenol (IPR) resulted in reduction of mucin secretion in response to the agonist during further incubation, and in increases in EC50 values. This IPR-induced reduction of secretion was coupled with selective decreases in the number of beta-adrenoceptors in the tissues and in their affinity for agonists, as assessed by measurement of the specific binding of [3H]dihydroalprenolol. Treatment of the tissues with IPR caused a 30% decrease in IPR-stimulated adenylate cyclase activity and a 25% increase in the GTP binding capacity of inhibitory G proteins (Gi proteins). This IPR treatment triggered a 60% increase in the ability of pertussis toxin (IAP) to catalyze ADP-ribosylation of Gi proteins in the tissue membranes. Enhanced function of stimulatory G proteins (Gs proteins) was observed only during the first incubation of the tissues with IPR. The IAP-catalyzed ADP-ribosylation of Gi proteins in tissues treated with IPR was decreased by prior treatment with cyclic AMP dependent protein kinase, but was increased markedly by prior treatment with alkaline phosphatase. Neither IPR-induced desensitization of protein secretion nor increase in the IAP-catalyzed ADP-ribosylation of Gi proteins was observed in the tissues pretreated with 0.25 microM okadaic acid. These findings suggest that the regulation of Gi protein phosphorylation plays an important role in the IPR-induced heterologous desensitization of mucin secretion from rat submandibular glands.

Adrenergic beta-Agonists↗
PubMed1995

Microsatellite instability in prostate cancer.

Assessment of the genetic instability of a microsatellite has indicated a new mechanism in human carcinogenesis. Examination was made to determine whether microsatellite instability is associated with the onset of prostate cancer. Twenty-nine DNA samples from 24 primary prostate cancer, two metastatic lymph-node and three benign prostatic hypertrophy patients were used. Differences in unrelated microsatellites for tumor and normal DNA were detected in nine of 24 (37.5%) cases. Seven of 11 (63.6%) with poorly differentiated adenocarcinomas and seven of 15 (46.7%) stage D metastatic patients showed somatic instability in a number of microsatellites. Statistically significant differences in well to moderately differentiated tumors and poorly differentiated cancer (P = 0.015, Chi-square test), were detected but not for stages A-C and D (P = 0.2311). Genetic alterations would thus appear to be rare in low grade and/or early prostate cancers but more common in high grade and/or advanced prostate cancers.

DNA Replication↗
PubMed1995

Altered functions of ion channels in diabetic beta cells.

Selective impairment of glucose-induced insulin secretion and hyper-responsiveness to arginine are known features of GK rats, a genetic model of NIDDM. We focus on the ionic mechanism underlying these phenomena using patch-clamp techniques. Pancreatic islets were isolated from male GK rats and age-matched control Wistar rats and were subjected to dispersion and culture. Single channel recordings of KATP channels were performed using either on-cell mode or inside-out patch mode. Ca2+ channel currents were recorded under conventional whole-cell mode. In GK beta cells, ATP sensitivity of KATP channels itself was not altered, although glucose-induced closure of KATP channels was severely impaired. Among substrates for fuel metabolism, only dehydroxyacetone (DHA) reproduced this anomaly. On the other hand, current densities of L-type Ca2+ channels were increased in GK beta cells. Since DHA is a known substrate for glycerol phosphate shuttle, current data suggest that major metabolic deficit of GK beta cells resides in this shuttle. On the other hand, increased L-type Ca2+ channel activities might be an ionic basis for augmented insulin response to nonglucose depolarizing stimuli in GK beta cells.

Adenosine Triphosphate↗
PubMed1995

Effects of Troglitazone (CS-045) on insulin secretion in isolated rat pancreatic islets and HIT cells: an insulinotropic mechanism distinct from glibenclamide.

In order to elucidate the direct effects of (+/-)-5-[4-(6-hydroxy-2,5,7,8-tetramethylchroman-2-yl-methoxy) benzyl]-2,4-thiazolidinedione (Troglitazone), a newly-developed oral hypoglycaemic agent, on pancreatic beta-cell function, in vitro investigation of isolated rat pancreatic islets and a hamster beta-cell line (HIT cell) were performed. Troglitazone stimulates both glucose, and glibenclamide-induced insulin release at a concentration of 10(-6) mol/l in these cells but, conversely, inhibits insulin secretion at 10(-4) mol/l. Glucose uptake in HIT cells is similarly enhanced by 10(-6) mol/l Troglitazone, but is reduced in the presence of 10(-4) mol/l Troglitazone. However, a quantitative immunoblot analysis with a specific antibody for GLUT 2 glucose transporter revealed no significant change in GLUT 2 protein in HIT cells with 10(-6) mol/l Troglitazone. Specific binding of [3H]-glibenclamide to beta-cell membranes is replaced by Troglitazone in a non-competitive manner, but 10(-6) mol/l Troglitazone failed to eliminate ATP-sensitive K++ channel activity. These results suggest that Troglitazone has a putative non-competitive binding site at, or in the vicinity of, the sulphonylurea receptor in rat pancreatic islets and HIT cells and that the dual effect of Troglitazone on insulin secretory capacity is mediated through the modulation of glucose transport activity, possibly due to the modification of intrinsic activity in glucose transporter in pancreatic beta cells by this novel agent.

ATP-Binding Cassette Transporters↗
PubMed1995

Hyperresponse in calcium-induced insulin release from electrically permeabilized pancreatic islets of diabetics GK rats and its defective augmentation by glucose.

In spontaneously diabetic GK rats, insulin secretion from pancreatic beta cells in response to glucose is selectively impaired, probably due to deficient intracellular metabolism of glucose and impaired closure of KATP channels during glucose stimulation. By using electrically permeabilized islets of GK rats, we explored the functional modulations in exocytotic steps distal to the rise in [Ca2+]i in the diabetic condition. At 30 nmol/l Ca2+ (basal conditions) insulin release was similar between GK and non-diabetic control Wistar rats. In response to 3.0 mumol/l Ca2+ (maximum stimulatory conditions), insulin release was significantly augmented in permeabilized GK islets (p < 0.01). Raising glucose concentrations from 2.8 to 16.7 mmol/l further augmented insulin release induced by 3.0 mumol/l Ca2+ from permeabilized control islets (p < 0.001), but had no effect on that from permeabilized GK islets. The stimulatory effect of glucose on insulin release from permeabilized control islets was partly inhibited by 2,4-dinitrophenol, an inhibitor of mitochondrial oxidative phosphorylation (p < 0.01). The hyperresponse to Ca2+ in GK islets may play a physiologically compensatory role on the putative functional impairment both in [Ca2+]i rise and energy state in response to glucose in diabetic beta cells, and may explain the relative preservation of insulin release induced by non-glucose depolarizing stimuli, such as arginine, from pancreatic islets in non-insulin-dependent diabetes mellitus.

2,4-Dinitrophenol↗
PubMed1995

Identification of osteopontin in human dental calculus matrix.

Osteopontin is a prominent non-collagenous component of bone matrix, although it is expressed in several other tissues. Recently, osteopontin was reported to be involved in urinary stone formation and atherosclerotic lesions of the aorta, suggesting that it may be a key protein associated with these types of pathological mineralization. In this study, whether or not human dental calculus contains osteopontin was investigated by immunoblotting and immunohistochemical analyses. After extraction of calculus proteins with EDTA and separation of the proteins by electrophoresis, immunoblotting analysis revealed the presence of osteopontin. Two forms of osteopontin appeared at 61 and 68 kDa on 10% polyacrylamide gel and the proteins were digested with thrombin, a highly specific protease. Moreover, immunohistochemical analysis revealed that osteopontin was localized in dental calculus adherent to tooth roots. These findings indicate that osteopontin is, in fact, present in human dental calculus and may be involved in calculus formation as the stone matrix.

Dental Calculus↗
PubMed1995

Three-dimensional display of the pelvic structure of anorectal malformations based on CT and MR images.

Three-dimensional images of the pelvic structure of patients with anorectal malformation (ARM) were constructed by computer graphics based on radiographic computerized tomography (CT) and magnetic resonance (MR) images. Organ contour data from CT images and raw MR image data were transferred to a personal computer and to a graphic workstation respectively. On MR image processing, organs were extracted semiautomatically by thresholding enclosed areas. After several steps of image processing, three-dimensional anatomy of each anomaly was visualized with emphasis on position and shape of the muscle complex. In control patients without an anomaly, images showed that the rectum is supported by the levator muscle from behind and descends along with the urethra. In the male patient, the anal canal separates from the urethra and penetrates through the middle of the sphincter complex to reach the orifice. In those with low-type anomaly with a fistula opening to the perineum or the vestibule, images showed the fistula descending through the anterior portion of the sphincter complex. Images of those with a rectourethral fistula could show the muscle complex behind the rectum and at the region where the external sphincter should be. In those with cloacal anomalies, anatomical position and the shape of three different viscera were easily recognized, and the muscle complex was shown like that of rectourethral-type anomalies. This study is a new approach to the anomaly to facilitate understanding it and can assist a surgeon in planning a procedure. This kind of application would make it possible for a surgeon to consider the strategy on a display screen before the real surgery.

Anal Canal↗
PubMed1995

Therapeutic applications of ribozymes.

The demonstration that RNA can be cleaved by cis or trans ribozymes (catalytic RNAs, RNA enzymes) has potentially important therapeutic implications. Since their discovery in the 1980s, the biochemistry and conserved sequences of ribozymes have been well characterized. Ribozymes are effective modulators of gene expression because of their simple structure, sitespecific cleavage activity, and catalytic potential. The targets of ribozyme-mediated gene modulation have ranged from cancer cells to foreign genes that cause infectious diseases. Additional target sites for ribozymes are in initial phases of development and design. Ribozymes have been targeted against a myriad of genes, including oncogenes (ras, BCR-ABL, c-fos) and drug resistance genes, as well as the human immunodeficiency virus-type I genome. These ribozymes have cleaved the target RNAs in vitro and altered the cellular pathology. Currently, the therapeutic application of ribozymes to human diseases is limited by gene transfer systems. It is anticipated that ribozymes ultimately will play an important role in human gene therapy.

Acquired Immunodeficiency Syndrome↗