Search PubMed⌕ Search

Biomedical subjects

T Endo

Publications and source records attributed to T Endo.

At least 1,117 records · Page 62Linked to original sources
PubMed1981

Troponin and its components from ascidian smooth muscle.

Troponin was isolated from the thin filaments of ascidian smooth muscle and separated into three components by ion-exchange chromatography, the molecular weights of which were 33,000, 24,000, and 18,000, respectively. The three components were designated as troponin t (TN-T), troponin I (TN-I), and troponin C (TN-C) in order of molecular weight, since each component had properties similar to those of the respective components of vertebrate skeletal-muscle troponin. The ascidian troponin or the mixture of the three components conferred Ca2+-sensitivity on reconstituted rabbit actomyosin in the presence of tropomyosin. One of the characteristics of the ascidian troponin was Ca2+-dependent activation of actin-myosin interaction in collaboration with tropomyosin, whereas its inhibitory action on the actomyosin ATPase in the absence of Ca2+ was less remarkable. From this, it is concluded that in the ascidian smooth muscle actin-myosin interaction is regulated by an actin-linked troponin-tropomyosin system, but the ascidian troponin acts as a Ca2+-dependent activator of an actomyosin system.

Actomyosin↗
PubMed1981

Proton-nuclear-magnetic-resonance study on molecular conformations of long neurotoxins. alpha-Bungarotoxin from Bungarus multicinctus and Toxin B from Naja naja.

The 270-MHz proton NMR spectra were analyzed of the long neurotoxins alpha-bungarotoxin from Bungarus multicinctus and Toxin B from Naja naja. The aromatic proton resonances were completely assigned to individual nuclei for alpha-bungarotoxin and in part for toxin B. The pH dependences of proton chemical shifts were analyzed by the nonlinear least-square method, for obtaining pKa values and protonation shifts. The pKa values of Tyr-25, an invariant residue of neurotoxins, are 12.1 for alpha-bungarotoxin and 11.3 for toxin B, suggesting the presence of a strong hydrogen bond involving Tyr-25 in alpha-bungarotoxin. The Trp-29 residues of both toxins show a common titration shift due to the carboxylate group of Asp-31 and a similar structural arrangement of functionally invariant pair of Trp-29 and Asp-31 is implied. From the temperature dependences of the chemical shifts of His-68 and a methyl group of alpha-bungarotoxin, the local structure around His-68 near the tail part is shown to be more flexible than the other part. The six main-chain amide protons of alpha-bungarotoxin exchange most slowly with solvent deuterons and are found by interproton nuclear Overhauser effects to be in the beta-sheet near the aromatic ring of Tyr-25 residue. Hydrogen leads to deuterium exchange rates in 2H2O solution at 37 degrees C were measured of slowly exchanging amide protons of alpha-bungarotoxin, toxin B, and two short neurotoxins, namely cobrotoxin and erabutoxin b. The two long neurotoxins have amide protons with relatively long half-times spanning as long as 10-100 h, but the two short neurotoxins do not have amide protons with half-times longer than 3 h. The distributions of the half-times of amide proton exchange indicate the structural rigidity of neurotoxins in the order, alpha-bungarotoxin greater than toxin B greater than cobrotoxin approximately erabutoxin b, in agreement with the order of neurotoxicity as reported previously by Chicheportiche et al. and by Lee and Chen.

Amino Acid Sequence↗
PubMed1981

Pharmacological studies on iridoid compounds. III. The choleretic mechanism of iridoid compounds.

We made a study on choleretic property and mechanism of action of iridoid compounds as well as dehydrocholate (DHC), cholate (CA), and salicylate (SA), examining their effects on factors such as bile flow, bile acids, electrolytes (Na+, K+, Cl-, and HCO3-), and their metabolites. Each sample showed a characteristic property, respectively. Genipin and patrinoside decreased biliary concentrations of bile acids, Na+, Cl-, and HCO3-, corresponding to their rapid choleretic actions which were due to bile acids independent fraction. The choleretic action of DHC is approximately twice as potent as that of CA. Their actions were due to bile acids-dependent fraction. CA gave a marked increase in Na+ concentration but DHC did not. And both compounds gave a marked diminution in Cl- concentration and weakly decreased HCO3- concentration. SA showed a weak and durable choleretic action and also gave a marked increase in HCO3- concentration. The main metabolite detected from the bile given genipin was genipin-1-O-glucuronic acid (GGA). The periodical pattern of GGA level in bile was in agreement with that of genipin- induced choleretic action, and quantitatively cation, anion gap produced was nearly compensated by biliary concentration of GGA. From out various results, the choleretic mechanism of iridoid compounds is considered to be as follows: The hemiacetal moiety of them undergoes conjugation in the liver to give glucuronide. Glucuronide thus formed is secreted into the biliary tree being coupled mainly with Na+ and water is passively excreted.

Animals↗
PubMed1981

[Studies on the prostaglandin E2 receptor in human corpora lutea (author's transl)].

It is known that Prostaglandins (PGs) have a specific effect on the corpus luteum function. In this paper we have studied the physical and chemical characteristics of PGE2 receptor in human corpora lutea to explain the mechanism on corpus luteum function. The presence of PGs binding sites in corpora lutea has been reported, but hardly any papers are available on the presence of PGE2 binding sites in human corpora lutea. The present study was undertaken to determine, using the proportion graph method, whether PGE2 receptors are present in human corpora lutea or not. The number of binding sites and association constant of PGE2 receptor to human corpora lutea of the luteal phase of the cycle and gestation were examined. There is evidence (1) that PGE2 receptors were present in human corpora lutea, and the binding sites have one specific and one non-specific binding system. (2) That the number of binding sites in early, mid and late luteal phase corpora lutea were respectively 105-157, 190-196, 162-190 f moles/mg protein. Association constants were 2.0-12.0 x 10(11) M-1. (3) That the number of binding sites of 6th week gestation corpora lutea were 98-100 f moles/mg protein, and those of 12th week gestation were 40-85 f moles/mg protein. Association constants of the gestation corpora lutea were 17.0-20.0 x 10(11) M-1.

Adult↗
PubMed1980

Intestinal parasites in Southeast-Asian refugees. Prevalence in a community of Laotians.

In response to public concerns, 165 Meo Laotians had stools screened for intestinal parasites by the Illinois Department of Public Health. One hundred twenty-nine had at least one pathogenic parasite detected. Hookworm was detected most frequently, followed by Giardia lamblia, Trichuris trichiura, and Ascaris lumbricoides. Hookworm and overall infection were more frequent in persons 4 years of age and older, while giardiasis, ascariasis, and trichuriasis were most common in the 4- to 14-year age group. Most infections were helminthic and of no public health consequence in the United States. However, giardiasis was seven times as prevalent in refugee children as in the general US population, posing a potential public health risk in child-care settings.

Adolescent↗
PubMed1980

Pharmacological studies on iridoid compounds. II. Relationship between structures and choleretic actions of iridoid compound.

The relationship between the structures and the choleretic actions of iridoid compounds was examined. Only patrinoside and villoside accelerated bile secretion among the iridoid glucosides but all of the iridoid aglycones increased it after intravenous administration rats. The choleretic effects of villoside, patrinoside aglycone, and 11-deoxy patrinoside aglycone were far weaker in comparison with those of other active iridoid compounds. When an equimolar amount of patrinoside, its aglycone, or 11-deoxy patrinoside aglycone was administered intravenously, their periodical patterns of choleretic activities nearly paralleled with those of isovaleric acid excreted in the bile. Patrinoside was partly hydrolyzed into its aglycone by the artificial gastric juice or the intestinal content. After intraduodenal administration of patrinoside (1 g/kg), the amount of patrinoside enough to exert a choleretic action was detected in the portal blood. These findings indicate that the hemiacetal moiety of iridoid compounds plays an important role in exerting a strong choleretic action and that patrinoside shows the same action following saponification of isovalerate of C-1 position in the liver.

Animals↗
PubMed1980

Hybridomas secreting monoclonal antibody with specificity for Toxoplasma gondii.

This study reports the successful establishment of eight functional hybridomas between mouse myeloma cells and spleen cells from mice hyperimmune to T. gondii as monitored by indirect immunofluorescence and radioimmunoassay techniques. Two of these eight cloned hybridomas showed positive reactivity in the Sabin Feldman dye test. Three hybridoma clones selected, following fusion of myeloma cells with freshly harvested spleen cells from hyperimmune mice, secreted into the culture medium antitoxoplasma antibody fo the IgC class. When spleen cells from hyperimmune mice were precultured in vitro for 5 days in presence of Con A and LPS and then fused with myeloma cells, five of the stable hybridomas secreted antitoxoplasma antibody of the IgM class, while one secreted antibody of the IgG class. These monoclonal antitoxoplasma antibodies should permit a rational approach to the purification of corresponding antigenic molecules from toxoplasma.

Animals↗
PubMed1980

Age and blood pressure related changes in cholesterol esterase activity and cholesterol content in aortas of stroke prone spontaneously hypertensive rats, spontaneously hypertensive rats and normotensive Wistar Kyoto rats.

Changes in aortic lipolytic enzyme activities (cholesterol esterase and lipoprotein lipase) and acid phosphatase activity during aging were investigated in three strains of rats with different blood pressures; stroke prone spontaneously hypertensive rats (SHRSP), spontaneously hypertensive rats (SHR) and normotensive Wistar Kyoto (WKR). The blood pressures of male, 7 month old animals, was 234 (SHRSP), 173 (SHR) and 128 (WKR) mmHg. The cholesterol esterase activity markedly decreased with age in the aortas of SHRSP, SHR and normotensive WKR rats, while acid phosphatase activity decreased only slightly, if at all, and lipoprotein lipase activity remained unchanged. This effect was enhanced by increasing blood pressure in SHRSP, SHR and WKR. The total aortic cholesterol content increased significantly with hypertension in a inverse relation with cholesterol esterase activity. These results suggest that cholesterol deposition in aged arteries is, at least partialy, ascribable to an age-related decrease in cholesterol esterase, and that hypertension aggravates the deposition of arterial cholesterol by accelerating the age-related decrease in aortic cholesterol esterase activity.

Acid Phosphatase↗