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Biomedical subjects

N Watanabe

Publications and source records attributed to N Watanabe.

At least 937 records · Page 52Linked to original sources
PubMed1989

Mitochondrial aspartate aminotransferase by immunoprecipitation method in patients with acute myocardial infarction.

The semiautomated kinetic procedure for determining cytoplasmic aspartate aminotransferase (c-AST) and mitochondrial aspartate aminotransferase (m-AST) activities was studied by the use of the immunoprecipitation method with anti-c-AST antibody in serum samples. The measured activity for m-AST remained constant after the addition of c-AST up to 1,000 IU/l throughout the 60-min incubation period. The measurements of m-AST activity were reproducible, selective and complete as determined by a purified m-AST. The precision of this method was as good as that of the manual method (CV 2.04%). The present method and the manual method gave approximately equal results for m-AST (r = 0.987). The effects of activations on m- and c-AST activity were compared by the addition of pyridoxal 5'-phosphate to sera of various diseases. A higher activation ratio by pyridoxal 5'-phosphate was observed on both aspartate aminotransferase activities in the serum of patients with ischemic heart diseases than in the serum of patients with liver diseases.

Adult↗
PubMed1988

[Characterization of type II insulin-like growth factor binding on rat hepatocytes of primary monolayer culture: regulation of the binding by IGF-I and related peptides].

Nature of insulin-like growth factor (IGF) binding on rat hepatocytes of primary monolayer culture and its regulation by IGF-related peptides were studied. The specific binding of 125I-IGF-I to the rat hepatocytes was saturable and dependent on incubation time and temperature. The optimal pH of incubation medium was 7.8-8.2. The steady-state binding was attained at 20 degrees C for 6 h, and averaged 12% per 4 X 10(5) cells. Fifty percent displacement of the 125I-IGF-I binding was observed at concentrations of 10 ng/ml of IGF-I and 5 ng/ml of IGF-II, but insulin (10 ng/ml-10 micrograms/ml) did not inhibit the binding. IGF-II inhibited the binding of 125I-IGF-II to the hepatocytes half maximally at concentrations of 2 ng/ml. A Scatchard plot of the data of binding was linear, and indicated association constant of 1.0 X 10(9)M-1 and a binding site of 44,000 per cell. Preincubation of the hepatocytes with either IGFs or insulin at 37 degrees C for 24 h resulted in the reduction of 125I-IGF-I binding to the hepatocytes in a dose-related manner, being dependent on incubation time and insulin concentrations. The binding was reduced to 20% of the control value in the presence of 10(-7)M IGF-I, and to 85% of the control in the presence of 5 X 10(-8)M IGF-II. Although insulin showed no affinity to the type II IGF receptors, 125I-IGF-I binding to the hepatocytes was decreased to 60% of the control after preincubation with 10(-10)M insulin. These results indicate that 1) the hepatocytes of primary monolayer cultures have only type II IGF binding, 2) preincubation of the cells with IGF-I, IGF-II or insulin induces the reduction of 125I-IGF-I binding to the cells, indicating down-regulation of the binding, and 3) this binding site of rat hepatocytes is regulated by not only IGF-I and IGF-II but also insulin of physiological concentrations.

Animals↗
PubMed1988

Studies on cholesterol esterase in rat adipose tissue: comparison of substrates and regulation of the activity.

Efficiency of substrates for cholesterol esterase (EC 3.1.1.13) assay, and regulation of the activity were investigated in rat epididymal adipose tissue. The activity in the supernatant was activated by cyclic AMP-dependent protein kinase, cyclic AMP, ATP and Mg2+, both with micellar and liposomal substrates. However, the micellar substrate was more suitable for the assay than the liposomal with respect to Vmax and Km. Thus, the micellar substrate was employed. Pretreatment of the supernatant with exogenous cyclic AMP-dependent protein kinase enhanced the activity dose dependently, whereas that with cyclic AMP decreased the activity slightly. The cyclic AMP-dependent protein kinase activity in the assay mixture was within the range which can cause changes in cholesterol esterase activity. These results suggest that the amount of cyclic AMP-dependent protein kinase, rather than the cyclic AMP level, plays an important role in the regulation of cholesterol esterase in tissues with a high cholesterol esterase activity relative to the kinase activity, such as in adipose tissue.

Adenylyl Cyclases↗
PubMed1988

Glucagon-like peptide-1 (7-36 amide): a potent glucagonostatic and insulinotropic hormone.

Glucagon-like peptide-1 (GLP-1) (1-37) and the fraction derived from it, GLP-1 (7-36 amide), are peptides encoded by the preproglucagon gene and possibly co-secreted with enteroglucagon. When added at a 25-nM concentration, GLP-1 (7-36 amide) decreased the release of glucagon from the perfused rat pancreas from 68.5 +/- 9.0 pg/ml to 41.5 +/- 11.5 pg/ml at 2 min in the presence of 11.2 mM glucose (P less than 0.01), and from 196.0 +/- 32.5 pg/ml to 87.0 +/- 23.5 pg/ml at 5 min in the presence of 2.8 mM glucose (P less than 0.05). Insulin levels increased from 12.6 +/- 3.0 microU/ml to 48.9 +/- 14.0 microU/ml at 10 min in the presence of 11.2 mM glucose (P less than 0.05) and from 2.0 +/- 0.4 microU/ml to 8.2 +/- 2.3 microU/ml at 2 min in the presence of 2.8 mM glucose (P less than 0.05). Glucagon and insulin release were not affected significantly by GLP-1 (1-37), irrespective of glucose concentration. We suggest that GLP-1 (7-36 amide) rather than enteroglucagon may be the true physiologic gut hormone and that it may act as 'incretin' in the enteroinsular axis. We suggest further that the glucagonostatic and insulinotropic activities of this peptide are unique and might be important in islet-cell function.

Animals↗
PubMed1988

Induction of synthesis of tumor necrosis factor in human and murine cell lines by exogenous recombinant human tumor necrosis factor.

Treatment of sensitive human myosarcoma cells (KYM-S) with exogenous tumor necrosis factor (r-TNF) resulted in the production of TNF by the cells. The newly synthesized cellular TNF was identified immunologically on Western blots and as a single 1.8-kilobase band on Northern blots. TNF synthesis began within 2 h of administration of the exogenous TNF in a dose-dependent manner. r-TNF also induced TNF synthesis in mouse tumorigenic fibroblasts (L-M). Resistant sublines of these cells as well as TNF nonsensitive human diploid fibroblasts possessed TNF mRNA without pretreatment, indicating an inverse correlation between levels of TNF expressed and sensitivity to the cytotoxic effects of exogenous TNF. It is conceivable that the newly synthesized cellular TNF functions in some protective manner to block cytolytic effects of exogenous TNF.

Animals↗
PubMed1988

Continuous internalization of tumor necrosis factor receptors in a human myosarcoma cell line.

The cell dynamics of the receptor for tumor necrosis factor (TNF) were examined in TNF-sensitive KYM cells derived from human myosarcoma. With receptor synthesis inhibited by cycloheximide, the half-life of the surface TNF receptor was 2 h in the absence of TNF and 30 min in its presence, suggesting that the TNF receptor is non-recycling and that its internalization is accelerated by TNF. During cell incubation with TNF receptor degradation suppressed by chloroquine, the number of surface TNF receptors remained approximately constant, but the total number of surface and internal TNF receptors increased gradually, at 3 h reaching 1.5 times the initial number, thus suggesting continuous synthesis, externalization, internalization, and degradation of the TNF receptor in the absence of cycloheximide. On cell incubation with 125I-TNF, the intracellular quantity of the pulse-labeled TNF-receptor complex promptly increased, reaching a maximum at 20 min, and then gradually declined, thus confirming that the TNF receptor is internalized as a TNF-receptor complex in the presence of TNF. During incubations with protein synthesis suppressed by cycloheximide following surface TNF receptor digestion by trypsin, TNF receptors reappeared on the cell surface, increasing in number to a peak at 60 min and gradually decreasing, and cells previously exposed to cycloheximide with or without TNF showed no recurrence of surface TNF receptors, suggesting that the TNF receptor is non-recycling. The results of the study thus suggest that the TNF receptor is continuously internalized and degraded intracellularly by lysosomes without being recycled regardless of the presence or absence of TNF and, further, that its internalization is accelerated when it is part of the TNF-receptor complex.

Cell Line↗
PubMed1988

Distribution of silicones in water, sediment and fish in Japanese rivers.

A new analytical method for assaying polyorganosiloxanes (silicones) in environmental samples is presented. The method utilizes petroleum for solvent extraction of the sample (water, sediment, biological tissue) together with inductively coupled plasma detection of the extracted organic silicones. The detection limit for silicones in the final methyl isobutyl ketone sample/extract is approximately 0.01 ppm, and the method is applied to samples from various Japanese rivers to quantify silicones in several environmental materials. Silicones are reported from river waters (up to approximately 50 ppb), riverine sediments (up to 6 ppm), and as an extractable component of fish tissue (up to approximately 0.9 ppm).

Animals↗
PubMed1988

Trophic effect of glucagon-(1-21)-peptide on the isolated rat ileal mucosal cells.

The trophic effect of glucagon-(1-21)-peptide on rat ileal epithelial cells was studied in vitro. Glucagon-(1-21)-peptide stimulated [3H]thymidine incorporation of mucosal cells significantly in a dose-dependent manner. Then glucagon-related peptides which have common sequences with glucagon-(1-21)-peptide were also tested. The biological potencies to augment [3H]-thymidine uptake were closely related with their amino-acid residues of N-terminal region. The result suggests that the N-terminal amino-acid sequence of glucagon molecule plays an important role in intestinal cell growth.

Amino Acid Sequence↗
PubMed1988

Three types of rat U1 small nuclear RNA genes with different flanking sequences are induced to express in vivo.

There are about 50 copies of U1 RNA genes/pseudogenes in the rat genome. To date, we have isolated so far 25 phage clones carrying a U1 RNA gene/pseudogene from two rat genomic libraries. The 12 clones were selected by hybridization with the U1 RNA coding region under a stringent condition, and were mapped and sequenced. Here, we report three types of U1 RNA genes with different flanking sequences, all of which were shown to be induced to express in vivo by transfection with their polylinker-inserted maxi U1 RNA genes into cultured rat cells. Although these three classes of U1 RNA genes have few homologous flanking sequences, they provide both upstream and downstream of the genes two conserved blocks, which may possibly play an important role in U1 RNA expression.

Animals↗
PubMed1988

Toxic effect of tumor necrosis factor on tumor vasculature in mice.

Stereoscopic observation via an implanted sight glass in mice bearing transplanted methylcholanthrene-induced A-cells showed tumorivascular hemorrhage at 1-2 h after tumor necrosis factor (TNF) administration, congestion at 4-6 h, and hemorrhage, congestion, and blood circulation blockage at 24 h. Histological examination after TNF administration to mice bearing similar methylcholanthrene-induced A-cell transplants showed thrombus formation in the tumor vasculature at 4 h and thereafter. Suppression of this thrombus formation with heparin had no apparent influence on the necrotic response, tumor growth inhibition or complete cure rate following TNF administration to mice bearing the methylcholanthrene-induced A-cell tumors. The results suggest that direct toxicity of TNF on tumor vasculature is a factor in the overall antitumor mechanism of TNF.

Animals↗
PubMed1988

Insulin binding to circulating monocytes in children with insulin-dependent and non-insulin-dependent diabetes mellitus.

This study describes insulin binding to circulating monocytes in 24 children with insulin-dependent diabetes mellitus (IDDM), five children with non-insulin-dependent diabetes mellitus (NIDDM), and 10 healthy and 12 obese control children. Insulin binding to monocytes was greatly increased in untreated IDDM children with obvious ketoacidosis (5.51 +/- 3.49 vs. 1.91 +/- 0.47 pg/10(6) cells, P less than 0.01), whereas it was decreased in those without obvious ketoacidosis (1.39 +/- 0.30 vs. 1.91 +/- 0.47 pg/10(6) cells, P less than 0.01). Insulin treatment restored insulin binding almost to the level of control children in both ketoacidotic and non-ketoacidotic patients. Insulin binding to monocytes was markedly decreased in untreated NIDDM children with hyperinsulinemia compared with healthy control children (0.73 +/- 0.27 vs. 1.91 +/- 0.47 pg/10(6) cells, P less than 0.01) or obese control children (0.73 +/- 0.27 vs. 1.33 +/- 0.35 pg/10(6) cells, P less than 0.01). These data indicate that changes in insulin secretion and metabolic conditions might be involved in the fluctuation of the number of insulin receptors in IDDM children as well as in NIDDM children.

Adolescent↗
PubMed1988

Synergistic effects of recombinant human tumor necrosis factor and hyperthermia on in vitro cytotoxicity and artificial metastasis.

Synergy in cytotoxic effect between recombinant human tumor necrosis factor and hyperthermia (incubation at 38.5 degrees C or 40 degrees C) was observed to occur against L-M (mouse tumorigenic fibroblast) cells and shown to be related to an accelerated turnover rate of recombinant human tumor necrosis factor-receptor complex under elevated temperatures rather than to changes in number of cell receptors or binding strength. However, no synergy in cytotoxic effect was observed to occur against human embryonic lung (HEL) cells. A clearly synergistic inhibition of metastatic tumor growth by combined administration of recombinant human tumor necrosis factor (300 units) and whole-body hyperthermia (40 degrees C, 30 min) was also observed in BALB/c mice previously given injections of 1 x 10(6) Meth-A (MH) cells/mouse via tail vein, neither of which alone resulted in significant inhibition.

Animals↗
PubMed1988

Synergistic cytotoxic and antitumor effects of recombinant human tumor necrosis factor and hyperthermia.

A synergistic increase in the cytotoxic effects of recombinant human tumor necrosis factor (rH-TNF) and hyperthermia was demonstrated both in vitro and in vivo. The cytotoxicity of rH-TNF against L-M cells in incubation for 12 h at 38.5 and 40 degrees C based on the concentration necessary for 50% cytotoxicity was, respectively, 125 and more than 500 times as high as in similar incubation at 37 degrees C. As observed 18 days after implantation of Meth-A fibrosarcoma cells in mice, single i.v. administration of rH-TNF at 1000 units/mouse resulted in complete cures in five mice when performed in combination with hyperthermia (40 degrees C), whereas rH-TNF alone in the same dose resulted in 27.1% inhibition of tumor growth and hyperthermia alone had no appreciable effect on tumor growth. The i.v. administration of rH-TNF three times at 100 or 300 units/mouse together with hyperthermia (40 degrees C) resulted in 41.2 and 89.0% tumor growth inhibition, respectively; similar administration without hyperthermia appeared to have little or no appreciable effect on tumor growth. The results suggest that combination therapy including rH-TNF and hyperthermia may be of value in the treatment of malignancy in human patients.

Animals↗
PubMed1988

Induction of antigen-specific IgA-forming cells in the middle ear mucosa.

Antigen-specific IgA-forming cells were induced in the middle ear mucosa by the use of soluble and particulate forms of dinitrophenylated ovalbumin. Hartley guinea pigs were locally immunized in the duodenum (group A) and trachea (group B) with the particulate form of dinitrophenylated ovalbumin one week after systemic priming with the soluble form. Otitis media was then induced with the intratympanic inoculation of the antigen. The control animals (group C) received only intratympanic inoculation after systemic priming. The mean titers of salivary IgA antibody of groups A and B were significantly greater than that of group C, and the mean value of serum IgG antibody titers of group C was significantly greater than those of groups A and B. The occurrences of otitis media in groups A and B were significantly suppressed, and histologic changes of the middle ear mucosa of groups A and B were slighter than those of group C. Antigen-specific IgA-forming cells were detected in the inflamed middle ear mucosa from group A and B animals, while these cells could not be found in group C animals. These results demonstrate the immunization strategy whereby the mucosal IgA immunity of the middle ear cavity can be effectively induced and enhanced to prevent otitis media.

Animals↗
PubMed1988

Alterations in gastric mucosal microvascular endothelium in a stressed condition--relevance to gastric ulcerogenesis.

The present paper describes the morphological and functional alterations of the gastric mucosal microvascular endothelium under restraint-stressed condition. On the basis of the direct cholinergic innervation of capillaries and non-muscular venules in the gastric mucosa, these endothelial changes would be caused by the stress-induced overstimulation of the cholinergic nerves and modified by the degranulation of mast cells, contributing to the stress-induced ulcer formation as schematically illustrated in Fig. 10.

Aged↗
PubMed1988

Observation of portal circulation through superior mesenteric vein by enteric coated capsule of thallium-201.

A new method of oral administration of an enteric coated capsule of 201Tl (201Tl-capsule) was developed to evaluate the portal circulation through the superior mesenteric vein (SMV). The 201Tl-capsule was not collapsed in the artificial gastric juice, whereas it melted soon after soaking in the artificial intestinal juice. In a clinical trial of 42 cases, 201Tl was satisfactory released in the duodenum in 36 cases where clear liver images were observed except in 1 patient. Heart to liver ratio (H/L) at 60 or 90 min after duodenal release of 201Tl was 0.32 +/- 0.07 (mean +/- 1 s.d.) in normal controls, 0.34 +/- 0.12 in chronic hepatitis, 0.31 +/- 0.12 in acute hepatitis, 0.45 +/- 0.13 in liver cirrhosis and 0.48 +/- 0.32 in cirrhosis with hepatocellular carcinoma. In 11 patients who had both oral and rectal studies with 201Tl, 7 showed a high H/L ratio of more than 0.8 in the rectal study but only 1 showed a similarly high ratio of 1.07 in the oral study. In the group of varied liver disorders we have studied so far, it was found that most of the SMV blood flowed into the liver and the degree of portal systemic shunting (PSS) from the SMV was much smaller compared to that from the inferior mesenteric vein. The present study with oral administration of the 201Tl-capsule was of value in understanding portal circulation through the SMV, however, this technique seemed of limited usefulness for evaluating overall pathologic PSS.

Capsules↗