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Biomedical subjects

T Endo

Publications and source records attributed to T Endo.

At least 955 records · Page 53Linked to original sources
PubMed1987

Role of C-terminal tail of long neurotoxins from snake venoms in molecular conformation and acetylcholine receptor binding: proton nuclear magnetic resonance and competition binding studies.

The role of the "C-terminal tail" segment of long neurotoxins has been investigated. The C-terminal four to five residues of alpha-bungarotoxin and Laticauda colubrina b have been cleaved off by carboxypeptidase P. The effect of such deletion on the toxin conformation has been monitored in proton nuclear magnetic resonance spectra and circular dichroism spectra. The removal of the C-terminal residues primarily affects the chemical shifts of proton resonances of the residues close to the cleavage site and does not induce a major conformational change. Therefore, the C-terminal tail of long neurotoxins does not appear to be important in maintaining the specific polypeptide chain folding. On the other hand, competition binding with tritium-labeled toxin alpha to Narke japonica acetylcholine receptor has revealed that cleavage of the C-terminal residues reduces the binding activity of alpha-bungarotoxin or Laticauda colubrina b to acetylcholine receptor. Thus it is likely that (the basic amino acid residues in) the C-terminal tail is directly involved in the binding of long neurotoxins to electric organ (and muscle) acetylcholine receptor.

Amino Acid Sequence↗
PubMed1987

Three types of muscle-specific gene expression in fusion-blocked rat skeletal muscle cells: translational control in EGTA-treated cells.

When rat skeletal muscle cells were treated with EGTA, an inhibitor of cell fusion, a battery of muscle-specific mRNAs was synthesized but not translated despite the synthesis of many other proteins. Most of the muscle-specific mRNAs were associated with polysomes in fused myotubes, whereas they were found in postpolysomal fractions in EGTA-treated cells. Therefore, in addition to the well-documented transcriptional and posttranscriptional control of muscle-specific genes, translational control of this specific group of genes, presumably involving a Ca2+-dependent process, is also observed in these fusion-blocked cells. These findings and results obtained with other fusion inhibitors demonstrate that three types of muscle-specific gene expression take place in the fusion-blocked cells depending on the inhibitors used: one, neither muscle-specific mRNAs nor proteins are synthesized; two, the mRNAs are synthesized but not translated; and three, both the mRNAs and the proteins are synthesized.

Animals↗
PubMed1987

Regulation of fibronectin and type I collagen mRNA levels by transforming growth factor-beta.

Human platelet-derived transforming growth factor-beta (TGF-beta 1) increases the accumulation of the extracellular matrix proteins, fibronectin and type I collagen, in mesenchymal and epithelial cells. To determine the basis for this effect, we have examined the levels of mRNAs corresponding to fibronectin and alpha 2(I) procollagen in NRK-49 rat fibroblasts and L6E9 rat myoblasts treated with TGF-beta 1. TGF-beta 1 increased severalfold the levels of mRNAs for both proteins. The kinetics of this effect were similar for both mRNA species. The increase in fibronectin and alpha 2(I) procollagen mRNAs was detectable 2 h after addition of TGF-beta 1 to the cells and their maximal levels remained constant for several days. Actinomycin D, but not cycloheximide, inhibited the increase in fibronectin and alpha 2(I) procollagen mRNA levels induced by TGF-beta 1. The results indicate that TGF-beta 1 controls the composition and abundance of extracellular matrices at least in part by inducing a coordinate increase in the levels of fibronectin and type I collagen mRNAs.

Animals↗
PubMed1987

pH dependence of individual tryptophan N-1 hydrogen exchange rates in lysozyme and its chemically modified derivatives.

Nuclear magnetic resonance analyses have been made of the individual hydrogen-deuterium exchange rates of tryptophan indole N-1 hydrogens in native lysozyme and its chemically modified derivatives including lysozyme with an ester cross-linkage between Glu-35 and Trp-108, lysozyme with an internal amide cross-linking between the epsilon-amino group of Lys-13 and the alpha-carboxyl group of Leu-129, and lysozyme with the beta-aspartyl sequence at Asp-101. The pH dependence curves of the exchange rates for Trp-63 and Trp-108 are different from those expected for tryptophan. The pH dependence curve for Trp-108 exchange exhibits the effects from molecular aggregation at pH above 5 and from a transition between the two conformational fluctuations at around pH 4. The exchange rates for tryptophan residues in native lysozyme and modified derivatives are not correlated with the thermodynamic or kinetic parameters in protein denaturation, suggesting that the fluctuations responsible for the exchange are not global ones. The exchange rates for tryptophan residues remote from the modification site are perturbed. Such tryptophan residues are found to be involved in a small but distinct conformational change due to the modification. Therefore, the perturbations of the N-1 hydrogen exchange rates are related to the minor change in local conformation or in conformational strain induced by the chemical modification.

Deuterium↗
PubMed1987

Structures of the sugar chains of a major glycoprotein present in the egg jelly coat of a starfish, Asterias amurensis.

Sugar chains of a major glycoprotein, obtained from the egg jelly coat of a starfish (Asterias amurensis), were released quantitatively as oligosaccharides by hydrazinolysis. After N-acetylation, they were converted to radioactive oligosaccharides by reduction with NaB3H4. Analysis by paper electrophoresis revealed that all of them were neutral oligosaccharides. Upon Bio-Gel P-4 column chromatography, the radioactive oligosaccharide mixture was separated into four components. Structural study of each component by sequential glycosidase digestion in combination with 1H-NMR spectroscopy revealed that the glycoprotein contains the following oligosaccharides, in which R represents either proton, Glc alpha 1----, Glc alpha 1----3Glc alpha 1----, or Glc alpha 1----2Glc alpha 1----3Glc alpha 1----. (Formula: see text)

Acetylation↗
PubMed1987

A novel human class II specificity, DQ "Wa," resides on DQ molecules of DR4,Dw15 and DRw8,Dw8 B-cell lines identified as DQ "blank".

The molecular localization of a novel human class II specificity, DQ "Wa," was investigated. A monoclonal antibody, HU46, which has previously been shown to react with DR4, Dw15 and DRw8, Dw8 B cells that type as DQ "blank," was used for the isolation and structural characterization of class II molecules bearing the DQ "Wa" determinant. The partial N-terminal sequence analysis of class II molecules bearing the DQ "Wa" determinant, purified from two B-cell lines, EBV-Wa (DR4, Dw15, DQ "blank") and GI (DRw8, Dw8, DQ "blank"), shows that the alpha and beta chain sequences are homologous to HLA-DQ. Within the limits of our analysis, the alpha and beta chains from both cell lines are identical. Both beta chains possess a phenylalanine residue at position 9 that differs from the tyrosine residue present at this position in beta chains of DQ alleles. These studies indicate that a novel human class II specificity, DQ "Wa," resides on a new allelic form of DQ molecules found in DR4, Dw15 and DRw8, Dw8 cells that are DQ "blank."

Alleles↗
PubMed1987

Life cycle of Tritrichomonas muris.

Morphological and physiological studies were carried out on a flagellate, Tritrichomonas muris, in golden hamsters. The experiments confirmed that a pseudocyst and an intermediate form exist in addition to the trophozoite in the life cycle; furthermore it was shown that the pseudocyst was the infective stage, and that a true cyst did not occur.

Animals↗
PubMed1987

Proton nuclear magnetic resonance characterization of phospholipase A2 from Laticauda semifasciata.

The molecular properties of phospholipases (PLases) A2 I and A2 III from a sea snake, Laticauda semifasciata, have been characterized by gel-filtration, as well as proton NMR, CD, UV absorption, and fluorescence spectroscopic methods. PLase A2 I exists as a monomer in aqueous solution in the presence or in the absence of Ca2+. The dissociation constants of the Ca2+-enzyme complexes have been determined for the two enzymes. The 270-mHz proton NMR spectra of PLases A2 I and A2 III have been measured, and the aromatic proton resonances of His-21 and His-48 in the active site have been assigned. By analyzing the pH dependence of the chemical shifts of the histidine proton resonances, pKa values have been determined for His-21 and His-48 with and without Ca2+. The conformational transitions have been found to take place at low pH or at high temperature (at approximately 65 degrees C). Fluorescence change of PLase A2 I upon addition of substrate analogs suggests that Trp-70 in PLase A2 I is involved in the binding to micellar substrates. The lack of Trp-70 in PLase A2 III is probably related to the low enzymatic activity as compared with that of PLase A2 I.

Animals↗
PubMed1987

Effects of extracellular potassium on acid release and motility initiation in Toxoplasma gondii.

The internal pH (pHi) of Toxoplasma gondii was estimated by measuring the accumulation of the weak base 9-aminoacridine in buffers with various ionic compositions. The pHi of the metabolizing parasite increased when the extracellular K+ was elevated in alkaline medium or when the external pH (pHe) was substantially increased in medium employing high external K+ (90 mM). The parasite in mouse peritoneal fluid, or in potassium sulfate buffer (pH 8.2), where the pHi was demonstrated to be increased to 7.9, became motile when acidic buffer was substituted for the original suspension medium. This acid-induced independent movement subsided within 5 min but was repeatedly induced if the pHe was serially lowered to 6.0. Basic buffers, on the other hand, abolished motility when applied to the moving parasites. Nigericin, which is known to collapse pH gradients across the membrane, also abolished motility.

Animals↗
PubMed1987

Current status of prehospital care of patients with acute myocardial infarction in Tokyo: analysis of 3-year experience with coronary care unit network.

To clarify the current status of prehospital care of patients with acute myocardial infarction (AMI) in the Tokyo metropolitan area, the availability of the coronary care unit (CCU) network during the past 3 years (January 1982 through December 1984) was analyzed, examining: final diagnosis, circumstances at the onset of AMI, course of transportation to CCU, time elapsed before admission, severity of AMI, and prognosis of patients. Of 6,939 patients admitted to CCU by means of the CCU network, 2,408 patients (34.7%) had AMI. The patient's decision time was, on the average, 12 hr 3 min, longer when the course of transportation to CCU was more complicated. The fatality for AMI was 17.2%. Causes of death were pump failure in 52.8%, arrhythmias in 62.8% and mechanical failure such as cardiac rupture in 8.5%. Patients with complicated AMI were admitted earlier and had a higher fatality than those without complications. Thus, community oriented programs are required to more fully inform the population at risk of AMI to shorten the patient's decision time, and more effective means to treat patients with pump failure and to prevent the development of pump failure need to be established.

Aged↗
PubMed1987

Demonstration of calcium-dependent proteases (calpains) and thyroglobulin proteolysis in hog thyroid cytosol.

Ca2+-dependent neutral proteases in hog thyroid cytosol were found to digest thyroglobulin. The protease activity was divided into two peaks by DEAE-cellulose column chromatography. Peak I was eluted at 0.2 M NaCl and required only a micromolar range of Ca2+ for its 50% activation, while peak II, which was eluted at about 0.4 M NaCl, displayed little activity until the Ca2+ concentration was increased at more than 10(-4) M. Among various inhibitors used, thiol protease inhibitors (leupeptin, E-64 and monoiodoacetic acid) were the most effective, whereas a calmodulin antagonist (trifluoperazine) and serine protease inhibitors (phenylmethyl-sulfony-fluoride and pepstatin A) were not effective, indicating that these Ca2+-dependent proteases corresponded to calpains 1 and 2. Among the substrates tested, casein was the best and thyroglobulin was also a good for calpain 2. By using immunoblotting procedure with anti-thyroglobulin antibody, it has been found that calpain 2 degrades thyroglobulin to yield 67 K and 46 K thyroglobulin and further that it also degrades 40 K thyroglobulin.

Animals↗
PubMed1987

Differential induction of adult and fetal globin gene expression in the human erythremia cell line KMOE.

Induction of globin gene expression in KMOE cells derived from a patient with acute erythremia was studied by Northern blot and S1 analysis. KMOE cells exposed to cytosine arabinofuranoside (Ara-C) synthesized beta-globin gene transcripts, however, in the presence of hemin gamma-globin gene transcripts. An increase in alpha-globin gene transcripts was also detectable in KMOE cells treated with both Ara-C and hemin. Upon exposure to hemin after exposure to Ara-C, or exposure to Ara-C after hemin, there was a 5-10-fold increase in gamma-globin gene transcripts compared to that of cells induced by hemin alone. Neither epsilon nor zeta globin transcripts were detected. The KMOE cell line, therefore, exhibits phenotypic properties of adult and fetal erythroid cells.

Cell Line↗