Biomedical subjects
Publications and source records attributed to D C Yang.
A seventy-seven-year old woman, with mitral stenosis, presented with cardiomegaly evident on her chest roentgenogram. The cardiac enlargement was due to a giant left atrium that distorted the cardiac structures. An echocardiogram and a first-pass nuclear angiogram were able to delineate the huge left atrium.
We have previously reported that several naphthoquinones stimulated tyrosine-specific protein phosphorylation in isolated rat liver membranes. Our more recent study demonstrated a similar effect by orthovanadate, which concomitantly stimulated phosphorylation of protein-tyrosine and phosphatidylinositol (Ptd-Ins). Results presented here show a simultaneous increase in PtdIns phosphorylation along with stimulation of tyrosine-protein phosphorylation by naphthoquinones. This PtdIns kinase resembles the type I PtdIns kinase in that it was insensitive to adenosine inhibition. The product, nevertheless, comigrated with a PtdIns-4-phosphate standard in TLC using three different solvent systems. Stimulation of PtdIns phosphorylation by vanadate or naphthoquinones could be achieved in the following preparations: intact rat liver membranes, Triton X-100-solubilized membranes, solubilized membranes partially purified by Sephacryl chromatography, solubilized membranes purified by wheat germ agglutinin chromatography. The naphthoquinone or vanadate-activated PtdIns kinase activity could be isolated by antiphosphotyrosine antibody-agarose affinity chromatography. The relative potencies of a series of ring-substituted naphthoquinones in the stimulation of tyrosine-protein phosphorylation, PtdIns kinase activity, dithiothreitol-dependent oxygen consumption, and cytochrome c reduction were highly correlated. We conclude that oxidant(s) produced by redox cycling of naphthoquinones stimulated an adenosine-insensitive PtdIns kinase through tyrosine phosphorylation of the enzyme.
An unusual case of obstruction of the iliac veins by a markedly distended urinary bladder (UB) is presented. Initial radionuclide venography (RNV) was positive, revealing obstruction of the iliac veins associated with marked dilatation of the UB. After the UB was emptied, RNV was negative.
The Clostridium bryantii-Methanospirillum hungatei syntrophic coculture, grown on caproate, was adapted to grow on crotonate. Then, C. bryantii was isolated in pure culture from crotonate bottle plates. A 16S rRNA sequence analysis of the pure subculture revealed that, as a member of the gram-positive phylum, it was not closely related to any of the Clostridium species with which it was compared or to any of the other clusters in the gram-positive phylum with which it was compared. However, it was closely related to another syntrophic fatty acid-degrading bacterium, Syntrophomonas wolfei. On the basis of its phylogeny, physiology, and cell wall ultrastructure, we propose assignment of C. bryantii to Syntrophospora bryantii gen. nov., nov. comb.
Currently, Doppler ultrasound and contrast angiography are the main imaging procedures being used to evaluate arterial bypass shunts. IV radionuclide total body arteriography (TBA) is another useful imaging procedure for evaluation of bypass shunts. The authors reviewed 33 patients, 19 women and 14 men, ranging in age from forty-three to eighty-five, who had TBA done after arterial bypass surgery. Ten patients had multiple shunts and 5 had multiple follow-up studies. In total there were 80 shunts, including 43 femoropopliteal, 16 axillofemoral, 1 axillopopliteal, 13 crossover femorofemoral, and 7 aortofemoral shunts. Sixty-two of the 80 shunts were patent, 14 were occluded, and 4 had partial occlusion. The results were confirmed by Doppler studies, contrast angiograms, and/or surgical exploration without false positives or false negatives. Since the radiotracer used was 99mTc-labeled red blood cells, a MUGA study can also be performed immediately following TBA in the same injection. Twenty-eight patients had gated cardiac blood pool studies (MUGA) done; 16 had abnormal wall motion and diminished ventricular function. TBA requires only a single IV injection of radiotracer (less than 1 cc) in the upper limb. The imaging times for total body arterial and perfusion images are seventy seconds and five minutes respectively. Both total body arterial and perfusion images clearly demonstrated the entire course of shunts (single or multiple); underlying and coexisting arterial abnormalities, e g, occlusive disease (27 patients), or aneurysm (3 patients); and related perfusion changes in the extremities. TBA has unique features. It permits a complete, excellent visualization of the bypass graft without the hazard of contrast media injection. It is a simple and a virtually noninvasive procedure, particularly useful for preoperative workups and postoperative follow-ups.
Orthovanadate stimulated the incorporation of 32P from [gamma-32P]ATP by Triton X-100-solubilized rat liver plasma membrane into endogenous, trichloroacetic acid-precipitable materials as well as added (Glu4:Tyr1) copolymers. Extraction of incubation mixture with chloroform-methanol-HCl revealed that the increase in 32P incorporation by vanadate was predominantly into endogenous phospholipids. [32P]Phosphatidylinositol 4-phosphate (PtdIns-4-P) was identified by thin-layer chromatography as the major phosphorylated product of vanadate stimulation, which also resulted in elevated 32P, predominantly in P-Tyr in endogenous membrane proteins. Vanadate effects on protein tyrosine and phosphatidylinositol phosphorylation were concomitant and exhibited similar sensitivity. These effects of vanadate were enhanced by the presence of either dithiothreitol or NAD(P)H. Phosphatidylinositol phosphorylation could also be stimulated by a substrate of and inhibited by a synthetic inhibitory copolymer of tyrosine kinase. These results suggest that vanadate, an oxygen radical producer, stimulates a tyrosine kinase-PtdIns kinase coupled system much like those described for a number of growth factors and oncogene encoded products.
Eight of the mammalian aminoacyl-tRNA synthetases associate as a multienzyme complex, whereas prokaryotic and low eukaryotic synthetases occur only as free soluble enzymes. Association of the synthetases may result in effective compartmentalization of synthetases and suggests the association of the entire protein biosynthetic machinery. To elucidate the structural elements and the nature of the molecular interactions involved in the association of the synthetases, we have cloned and sequenced the complementary DNA coding human aspartyl-tRNA synthetase. The full length cDNA encodes an open reading frame of 500 amino acids with 56% identity with yeast aspartyl-tRNA synthetase. The similarity with yeast aspartyl-tRNA synthetase is unevenly distributed with a high percent of identity at the C-terminus and relatively low identity at the N-terminus. The N-terminal sequence strongly prefers an alpha-helical secondary structure and shows amphiphilic characteristics. Further comparison with the yeast synthetases showed that the basic positively charged helixes in yeast synthetases are evolved to a neutral amphiphilic helix in this mammalian synthetase. The mammalian neutral amphiphilic helix is so far unique among all known sequences of bacterial, yeast, and mammalian synthetases and may account for the association of synthetases in the synthetase complex.
Noise distribution of a medium size coal mine was studied. There were 17 kinds of machine noise sources with an additional noise due firing of the gun. 449 sets of machine were distributed at the different canes and working places. Over 3000 workers were exposed to this noise. Noise intensity level of machines was 78.5-117 dB(A), of firing-a-gun 128 dB(A), the main working group Leq exceeded criterion (90 dB(A)) by 3-20 dB(A). Coal excavating machine had a high noise intensity level. These results may have reference value for investigation of noise pollution in the coal mines of China.
The multienzyme complexes of mammalian aminoacyl-tRNA synthetases were purified from rat liver, rabbit liver, and rabbit reticulocytes according to the procedure slightly modified from Kellermann et al. [Kellermann, O., Brevet, A., Tonetti, H., & Waller, J.-P. (1979) Eur. J. Biochem. 99, 541-550]. Three forms of the synthetase complex with slightly different protein compositions were identified, suggesting a microheterogeneity of the synthetase complex. The hydrodynamic properties and the protein composition of the purified complexes were determined. The electron micrographs of the complex showed mostly amorphous particles and some hollow rings with an outer diameter of 164 A and an inner diameter of 42 A. The predicted hydrodynamic properties of several models of the complex were calculated. The properties of a ring model appear to best fit with those of the synthetase complex.
Eight aminoacyl-tRNA synthetases together with three unidentified proteins are associated as a multi-enzyme complex in mammalian cells. Partial peptide sequences for lysyl- and aspartyl-tRNA synthetases are determined and no highly hydrophobic peptides are found. The partial amino acid sequences for two of the unidentified proteins in the complex are shown to have substantial homology and each has a number of unique sequences. The results suggest that the two unidentified proteins are fragments of synthetases. The partial sequences revealed the presence of PEST sequences in at least three proteins. Inasmuch as PEST sequences are signals for intracellular degradation, the mammalian synthetase complex may have evolved to protect these synthetases against intracellular proteolysis.
Valyl-tRNA synthetase from rat liver sediments at 15.5 S with a Stokes radius of 90 A, corresponding to a native molecular weight of 585,000. Purification of valyl-tRNA synthetase to homogeneity by a combination of conventional and affinity column chromatography yields a fully active monomeric form of valyl-tRNA synthetase with a sedimentation coefficient of 7.7 S and a Stokes radius of 45 A. The subunit molecular weight of the monomeric valyl-tRNA synthetase is 140,000, as determined by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. In the presence of 400 mM KCl, the purified monomeric valyl-tRNA synthetase associates to a high molecular weight form. The high molecular weight valyl-tRNA synthetase in the homogenate can be readily converted to the monomeric form by controlled trypsinization. The kinetic parameters of the two forms are nearly identical. The results suggest that the high molecular weight valyl-tRNA synthetase is a homotypic tetramer and converts to the monomeric valyl-tRNA synthetase after the cleavage of a small peptide.
We have developed a technique using a blood pool agent Tc-99m labeled red blood cells and a detector head set moving at a high speed to obtain total body arterial and blood pool images with only a single intravenous injection. Previously with an intravenous radiotracer injection, only regional arterial images could be obtained. Now, with this simple, non-invasive technique, we can evaluate the major arterial system, organs, and soft tissues in the whole body, as well as cardiac function. On reviewing 500 cases, more than 90% of the first-pass arterial phase images clearly demonstrated the aorta, ilio-femoral arteries, and, to a lesser extent, the more distal arteries in the lower extremities. The second-pass blood pool images revealed the anatomical and morphological status of the solid organs, as well as perfusion changes in various organs and soft tissues.
Radionuclide arthrography is becoming increasingly useful in the evaluation of femoral component loosening in patients with a painful total hip prosthesis. Additional potential advantages of radionuclide arthrography include detection of abnormal communications with the hip, such as bursae, abscess cavities, and fistulas. A case of cutaneous fistula communicating with the hip in a patient with loosening and infection of the femoral component of the total hip prosthesis that is clearly demonstrated by radionuclide arthrography is presented.
Recently the authors introduced a new technique of intravenous (IV) radionuclide total-body arteriography. The major arterial system, multiple organs of the whole body, and cardiac function can be evaluated with one small IV injection in the arm. After analyzing more than 1000 cases, they have found that many pathologies can be detected and/or confirmed in this procedure. This new technique may be used as a general whole-body screening test for those patients at high risk for disease.
Histidyl-tRNA synthetase is purified to near homogeneity from rat liver. The subunit molecular weight of histidyl-tRNA synthetase is 50,000, as determined by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. The Stokes radius and the sedimentation coefficient of histidyl-tRNA synthetase are 38 A and 6.0 S, respectively. The native molecular weight of histidyl-tRNA synthetase is calculated to be 96,000 on the basis of its hydrodynamic properties. The purified histidyl-tRNA synthetase reacts with the myositis-specific anti-Jo-1 antibodies. Anti-Jo-1 immunoglobulin G reacts with the native form of histidyl-tRNA synthetase and does not react or only weakly reacts with the denatured form. The anti-Jo-1 antibodies exhibit stronger inhibition toward histidyl-tRNA synthetase that has been preincubated with tRNA than that without preincubation. Anti-Jo-1 antibodies behave as a noncompetitive inhibitor with respect to tRNA in the aminoacylation reaction catalyzed by histidyl-tRNA synthetase. The structural features of the antigen of the anti-Jo-1 antibodies in light of these results are discussed.
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Ionophore (A23187) stimulated rat basophilic leukemia (RBL-1) cells produce a lipid mediator which caused rabbit platelets to aggregate and which by using platelet-activating factor (PAF)-acether antagonists and high-pressure liquid chromotography was shown to be PAF-acether. Thus RBL-1 cells represent a cell type suitable for studying the coordinated release of three mediators of anaphylaxis: histamine, leukotrienes C4/D4 (slow-reacting substances) and PAF-acether.
A fifty-five-year-old male demonstrated over a three-year period marked enlargement of pulmonary aneurysms. This can be a fatal condition owing to rupture of the aneurysms.