Measurement of spin-spin relaxation of 0.05-wt. % ruby.
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Journal Article↗
Biomedical subjects
T Endo
Publications and source records attributed to T Endo.
Quantum Hall effect in silicon metal-oxide-semiconductor inversion layers: Experimental conditions for determination of h/e2.
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Journal Article↗
Fecal bile acids and neutral sterols in rats with spontaneous colon cancer.
Fecal bile acids and neutral sterols of spontaneous colon cancer-bearing Wistar-Furth strain rats were examined and compared with those of control rats of the same strain by gas chromatography and gas chromatography-mass spectrometry. The amount of total fecal bile acids and the percentage of fecal lithocholic acid were almost similar in both groups, but the percentage of fecal deoxycholic acid was significantly higher in the colon cancer group than in the controls. The amount of total fecal neutral sterols and the percentage of fecal coprostanol were also markedly higher in the colon cancer group than in the controls. The percentage of cholesterol and the amount of beta-sitosterol were, however, almost similar in the two groups. These results indicate that fecal deoxycholic acid and fecal coprostanol are notably higher in rats with colon cancer than in controls.
Animals↗
Partial N-terminal sequence analysis of DRw53 antigens: the beta-chains of DRw53 antigens are structurally distinct from beta-chains of DR and DQ antigens.
DRw53 antigens were isolated from DR7-homozygous and DRw9-homozygous cell lines with an alloantiserum, Hon, containing an anti-DRw53 alloantibody. Partial N-terminal sequence analysis of the isolated DRw53 antigens revealed that DRw53 alpha-chains have sequences indistinguishable from those of DR alpha-chains. In contrast, DRw53 beta-chains have sequences distinct from those of the DR beta-chains and DQ beta-chains isolated from the same cell lines. The DRw53 beta-chains are also distinct from DP beta-chains. These results suggest that the DRw53 beta-chains chains are products of a gene that has not yet been well characterized in the HLA-D region.
Amino Acid Sequence↗
Stopped-flow fluorescence studies on binding kinetics of neurotoxins with acetylcholine receptor.
Acetylcholine receptor from Narke japonica electroplax exhibits a fluorescence change upon binding of snake neurotoxins. This fluorescence change primarily arises from the conformational change of the acetylcholine receptor and reflects the binding process of the toxin with the receptor. The time dependence of the fluorescence change has been monitored for 28 short neurotoxins and 8 long neurotoxins by using a stopped-flow technique. The steady-state fluorescence change is of the same order of magnitude for the short neurotoxins but varies among the long neurotoxins. Nha 10, a short neurotoxin with weak neurotoxicity, causes no fluorescence change in the receptor but can still bind to the receptor with sufficiently high affinity. The substitution of the conserved residue Asp-31 to Gly-31 in Nha is probably responsible for the reduced neurotoxicity. The rate constants for the binding of the neurotoxins to the receptor have been obtained by analyzing the transient fluorescence change. The rate constants show surprisingly a wide range of distribution: (1.0-20.5) X 10(6) M-1 s-1 for short neurotoxins and (0.26-1.9) X 10(6) M-1 s-1 for long neurotoxins. Examination of the relationship between the rate constants of fluorescence change of the short neurotoxins and their amino acid sequences, thermal stability, hydrogen-deuterium exchange behavior, overall net charge, etc. reveals the following. Positive charges on the side chains of residues 27 and 30 and overall net charge of the neurotoxin govern the magnitude of the binding rate of the neurotoxin with the receptor.
Amino Acid Sequence↗
Immunocytochemical and biochemical localization of parvalbumin in the retina.
The cellular distribution of parvalbumin-like immunoreactivity (PA-LI) in normal retina of rat, monkey, and human was investigated by immunohistochemical peroxidase-antiperoxidase methods, and the levels of PA-LI in normal rat retina and brain were measured by radioimmunoassay. The antibody, raised in rabbits using rat skeletal muscle parvalbumin, did not cross-react with other Ca2+-binding proteins such as calmodulin or S-100 proteins. In rat retina, PA-LI-containing cells are located in the proximal inner nuclear layer and send processes to the external half of the internal plexiform layer, suggesting that they are amacrine cells. In monkey and human retina, PA-LI-positive cells exist in the outermost sublayer of inner nuclear layer, and PA-LI-containing fibers that extend horizontally are found in the internal zone of outer plexiform layer. The radioimmunoassay revealed that the rat retina contained 1710 +/- 91 ng PA-LI/mg protein, the levels of which were higher than that of brain (881 +/- 165 ng PA-LI/mg protein). These results show an additional location for PA-LI outside skeletal muscle and brain, and also provide information on the function of interneurons of retina, which are still poorly understood.
Animals↗
Gastrointestinal absorption of inorganic mercuric compounds in vitro.
Effects of intraluminal pH on the intestinal absorption and tissue binding of HgCl2 and HgO were studied in the everted sac of rat small intestine. The sac was incubated in media containing HgCl2 or HgO (10(-5 M] at different pH values. With an increase in pH, the uptake of HgCl2 in the intestinal tissue decreased and the transport of HgCl2 through the tissue increased. Similar pH dependence was observed in the uptake of HgO. The transport of HgCl2 seemed to be correlated with mercury bound to a protein (molecular weight between 440,000 and 669,000) and to be inversely correlated with that bound to intestinal metallothionein. These results suggest that the increase of intraluminal pH promotes the absorption of HgCl2 accompanied by a change in the binding of HgCl2 to the everted tissue sac.
Absorption↗
Type beta transforming growth factor is an inhibitor of myogenic differentiation.
We have investigated the effect of type beta transforming growth factor (TGF-beta) on the differentiation of skeletal muscle myoblasts. TGF-beta potently (ID50 approximately 10 pM) prevents established cell lines and primary cultures of rat and chicken embryo myoblasts from fusing into multinucleated myotubes. Inhibition of morphological differentiation by TGF-beta correlates with inhibition of the expression of muscle-specific mRNAs and proteins, strong induction of extracellular matrix type I collagen and fibronectin, and a marked tendency of the treated myoblasts to aggregate into densely multilayered arrays or clusters. Myogenic differentiation can resume after removal of TGF-beta from the medium. Examination of the time of action of TGF-beta shows that myoblasts stochastically reach a point beyond which they become insensitive to the inhibitory action of TGF-beta. This resistance of committed myoblasts to the inhibitory action of TGF-beta is not associated with any measurable change in the number or affinity of TGF-beta receptors in those cells. The results indicate that TGF-beta is a potent inhibitor of myogenesis and may regulate muscle development in vivo.
Cell Differentiation↗
Proton nuclear magnetic resonance analyses of the molecular conformations of unique long neurotoxins bearing Phe-25: Astrotia stokesii b, Astrotia stokesii c, and Acanthophis antarcticus b.
The 270-MHz proton NMR spectra of the unique long neurotoxins bearing Phe-25, Astrotia stokesii b (As b) and Astrotia stokesii c (As c) from Astrotia stokesii, and Acanthophis antarcticus b (Aa b) from Acanthophis antarcticus, have been analyzed. The aromatic proton resonances of Phe-25 in As b and Aa b were assigned on the basis of the nuclear Overhauser effects observed on irradiation of slowly exchanging amide protons. Phe-25 was found to be involved in hydrophobic interactions with Ile/Val-42, Ala-46 and Ile-58 in As b and As c, and with Ala-46 and Val-58 in Aa b. These hydrophobic interactions, instead of the hydrogen bond between Tyr-25 and Glu-42 found in other neurotoxins, appear to be important for maintenance of the biologically active tertiary structure. The pH dependency of the chemical shift and intensity of the Trp-72 N-1 proton resonance of As b indicates that the indole ring is not fully exposed to the solvent and that the extra tail segment of this long neurotoxin interacts with the main part of the molecule.
Circular Dichroism↗
Immunochemical and immunohistochemical localization of parvalbumin in rat nervous tissues.
The contents of parvalbumin in various nervous tissues of the rat were measured by radioimmunoassay (RIA) and its cellular distribution was immunohistochemically examined by peroxidase-antiperoxidase methods. The antibody, raised in rabbits using rat skeletal muscle parvalbumin, did not cross-react with other Ca2+-binding proteins such as calmodulin or S-100 proteins. The RIA demonstrated the wide distribution of the antigen, with very high levels in the cerebellum (3,217 +/- 519 ng/mg protein). The immunohistochemical description by Celio and Heizmann [Nature 293, 300-302 (1981)] was confirmed concerning the existence of the antigen in Purkinje cells of the cerebellum; nonpyramidal neurons of the cerebral cortex; and medium-sized cells of the olfactory bulb, hippocampus, and reticular nucleus of the thalamus. In addition to these neurons, we found the parvalbumin-like immunoreactivity in the large neurons of the superior vestibular nucleus and the neurons of the medial superior olive nucleus. In the gamma-aminobutyric acid (GABA)-containing nuclei such as substantia nigra, caudatoputamen, and globus pallidus, parvalbumin-positive cells and fibers were rare. In the medial lemniscus of the midbrain which contains no GABA, parvalbumin-immunoreactive fibers were prominent. The possibility was discussed that parvalbumin exists in a specific population of neurons that differ from those containing GABA.
Animals↗
Transcriptional and posttranscriptional control of c-myc during myogenesis: its mRNA remains inducible in differentiated cells and does not suppress the differentiated phenotype.
It is widely accepted that the cellular oncogene c-myc plays an important role in the control of cell proliferation and that its expression diminishes in differentiated cells. We examined whether there is a correlation between c-myc expression and cell proliferation or differentiation by using a subclone of a rat skeletal muscle cell line L6E9. Myoblasts irreversibly withdraw from the cell cycle, fuse to form multinucleated myotubes, and express muscle-specific genes (terminal differentiation). Muscle-specific genes can also be expressed in the absence of fusion (biochemical differentiation). Such mononucleated but biochemically differentiated cells can be stimulated to reenter the cell cycle. c-myc was induced by insulin, insulin-like growth factor, or serum factors in G0-arrested cells, whereas induction by protein synthesis inhibitors or superinduction by protein synthesis inhibitors in combination with serum factors occurred in all physiological states tested. We found that c-myc expression was reduced in biochemically and terminally differentiated cells as well as in quiescent undifferentiated cells but that it remained inducible by growth factors in all three physiological states. Results of nuclear runoff transcription assays suggested that the induction of c-myc mRNA by growth factors and its deinduction in these physiological states were regulated mainly at the transcriptional level. In contrast, induction and superinduction of c-myc mRNA by protein synthesis inhibitors alone and in combination with growth factors, respectively, were regulated posttranscriptionally mainly by stabilization of c-myc mRNA. Moreover, c-myc and muscle-specific genes could be simultaneously transcribed in both biochemically and terminally differentiated cells. These results indicate that irreversible repression of c-myc is not required for terminal myogenic differentiation and that its expression is insufficient by itself to suppress the differentiated phenotype.
Animals↗
Comparative effects of nicardipine, a new calcium antagonist, on size of myocardial infarction after coronary artery occlusion in dogs.
To examine whether nicardipine, a dihydropyridine derivative, limits size of myocardial infarction, and to compare the protective effects of nicardipine administered before and early and late after coronary artery occlusion, 99mTc-labeled albumin microspheres were injected into the left atrium during 5 min temporary coronary artery occlusion to determine the extent of the hypoperfused zone (the area at risk). The coronary arteries were then reperfused for 45 min before 6 hr permanent coronary artery occlusion. Fifteen minutes before permanent occlusion, dogs were randomly assigned to a control group (n = 11), a pretreatment group (n = 9), which received at this point 10 micrograms/kg of nicardipine as a loading dose followed by a continuous infusion of 8 micrograms/kg/hr for 6 hr, an early treatment group (n = 9), in which nicardipine treatment was initiated 15 min after occlusion, or a late treatment group (n = 8), in which nicardipine administration was delayed for 3 hr. Six hours after coronary artery occlusion, the hearts were excised and the left ventricle of each was cut into 3 mm thick slices and stained with triphenyltetrazolium chloride. The extent of myocardial necrosis was measured by planimetry of the unstained areas. Thereafter, the same slices were autoradiographed and the extent of the hypoperfused zone was measured by planimetry of the "cold spot." The extent of the hypoperfused zone was identical among the four groups. In the control group, the ratio of the extent of myocardial necrosis to the extent of the hypoperfused zone was 95.8 +/- 3.8% (mean +/- SEM). However, it was significantly smaller in the pretreatment group (59.9 +/- 13.3%, p less than .05) and the early treatment group (49.0 +/- 10.6%, p less than .01) than in the control group. In the late treatment group, this value was not different from that in the control group (86.5 +/- 7.1%). There was a close inverse correlation between reduction of infarct size and the extent of the hypoperfused zone in the pretreatment and early treatment groups. Thus, nicardipine administered before or early after coronary artery occlusion limited infarct size by 37% to 49%, whereas when administration was delayed for 3 hr infarct size was not reduced. Furthermore, nicardipine had more striking effects on the ischemic myocardium of dogs with small hypoperfused zones than on that of dogs with large hypoperfused zones.
Animals↗
Parvalbumin is reduced in the peripheral nerves of diabetic rats.
Parvalbumin (PA), one of the Ca2+-binding neuronal marker proteins, has been revealed to exist in the myelinated axons of the posterior root of the spinal cord and the peripheral nerve of rats. To investigate the role of PA for the genesis of diabetic neuropathy, the levels of PA in the sciatic nerve of normal and streptozotocin-induced diabetic rats were measured by radioimmunoassay (RIA) for PA. The immunohistochemical distribution of PA in the sciatic nerve from both groups was also studied. The RIA for PA revealed that the levels of PA in the sciatic nerve of diabetic rats were significantly decreased when compared with those of normal rats. However, the contents of S-100 protein, another type of Ca2+-binding glial marker protein, did not show any significant difference in the sciatic nerve from both groups. Immunohistochemically, the amount of PA containing myelinated axons of the diabetic nerve was markedly decreased when compared with nondiabetic subjects. These results suggest that the decreased level of PA in the peripheral nerve might contribute to the genesis of diabetic neuropathy.
Animals↗
Electrophysiological and pharmacological studies on the mechanisms of ventricular tachycardia.
Employing electrophysiological and pharmacological methods, the mechanisms of recurrent ventricular tachycardia were studied in 31 patients, 18 with old myocardial infarction and 13 with idiopathic ventricular tachycardia. In the cases of ventricular tachycardia with old myocardial infraction, the initiation and termination of the tachycardia could be achieved by programmed electrical stimulation in 13 out of 18 patients. Endocardial mapping showed that the earliest excitation site during tachycardia was at the border zone of infarction, where the diastolic fragmented activity was detected. Programmed electrical stimulation sometimes provoked more than two kinds of QRS morphology of tachycardia in the same patient. Class IA antiarrhythmic agents were effective in terminating tachycardia. These data suggest that there are multiple reentrant pathways consisting of partially depressed fast fibers at the border zone of infarction. In the cases with idiopathic ventricular tachycardia, the induction and termination of tachycardia was effected by electrical stimulation in 8 out of 13 patients. For the termination of tachycardia, long overdrive pacing was sometimes necessary. The diastolic fragmented activity could not be detected by endocardial mapping. A class IV drug such as verapamil was more effective for the termination of tachycardia than class I drugs, and there were repetitive short runs of ventricular extrasystole observed until the final termination. These data support the reentrant pathways containing slow with enhanced automaticity as the circuit of idiopathic ventricular tachycardia.
Adolescent↗
Effects of positive end-expiratory pressure ventilation and extracorporeal ultrafiltration method in patients with refractory heart failure.
We studied the effects of positive end-expiratory pressure (PEEP) ventilation in ten patients with acute myocardial infarction (nine in Killip class III, one in Killip class IV; pulmonary capillary wedge pressure greater than 24 mmHg) and of extracorporeal ultrafiltration method (ECUM) in seven patients with refractory heart failure due to acute myocardial infarction and others. Application of PEEP resulted in significant increases in PaO2 and SaO2 and decrease in PaCO2. Significant reduction in mean pulmonary arterial and pulmonary capillary wedge pressures and heart rate was observed, while stroke work index increased significantly. There was a significant correlation between changes in stroke work index and PaO2 after the application of PEEP. The use of ECUM removed fluid of 1416 +/- 662 ml (680-2800 ml) with the ultrafiltration flux rate being 478 +/- 223 ml/hour. Significant decreases in mean pulmonary arterial, pulmonary capillary wedge and central venous pressures were observed, while PaO2 increased significantly. BUN and serum creatinine levels increased significantly, and total protein and serum albumin tended to increase. There was a significant correlation between fluid removed and change in PaO2 after the use of ECUM. Thus, PEEP and ECUM are beneficial for patients with refractory heart failure. The mechanism(s) are: reduction in preload due to an increased intrathoracic pressure and a decreased systemic venous return with PEEP, or due to removal of excess fluid with ECUM, and improvement of the oxygenation of the blood.
Aged↗
Effects of phorbol esters on protein phosphorylation and free T3 release by mouse thyroid lobes.
Phorbols stimulated 32P incorporation into several proteins in mouse thyroid lobes. Phosphoproteins (34 K and 23 K) were detected by SDS-polyacrylamide gel electrophoresis and autoradiography. Among phorbols tested, 12-O-tetradecanoyl-phorbol-13-acetate (TPA) was the strongest stimulator of protein phosphorylation. On the other hand, TPA at 50-200 ng/ml significantly stimulated free T3 release by mouse thyroid lobes. The stimulatory effect of TPA was not additive to that of TPA or dibutyryl cAMP. TSH stimulation of free T3 release by mouse thyroid lobes, however, was significantly inhibited by H-7 (an inhibitor of protein kinase C) at a concentration of 50 microM. These results suggest that protein kinase C may play some role in thyroid hormone secretion by phosphorylating the endogenous substrates.
1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
Immunohistochemical analysis of human adenocarcinoma-associated antigen YH206 detected by a monoclonal antibody.
A monoclonal antibody YH206 (IgM, kappa) was prepared using human lung adenocarcinoma A549 cell line as an immunogen. The histological distribution of antigenic determinant of the YH206 antigen was highly restricted to adenocarcinomas of various organs including the lung, the pancreas and the stomach, but it did not react with 10 cases of colonic adenocarcinomas by the immunoperoxidase technique. It did not stain non-cancerous tissues of 16 different organs, except for the renal tubules and for the secreting glands of the pancreas with which the antibody faintly reacts. It did not react with either granulocytes, lymphocytes or red blood cells. Positive staining was observed in various fetal tissues. Periodic acid and neuraminidase treatments on tissue sections suggested that the chemical nature of the antigenic determinant of YH206 antigen was carbohydrate in nature which might be masked by sialic acids.
Adenocarcinoma↗
[A study of the effect of reactant volume of solution to fluorapatite formation upon tooth enamel].
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Apatites↗