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Biomedical subjects

C V Dang

Publications and source records attributed to C V Dang.

121 records · Page 7Linked to original sources
PubMed1983

Hydrodynamic properties and structure of the rat liver 12 S arginyl- and lysyl-tRNA synthetase complex.

Eukaryotic aminoacyl-tRNA synthetases occur in multienzyme complexes in contrast to their prokaryotic counterparts. A core 12 S rat liver complex (Mr 290,000) was recently purified to homogeneity consisting of two polypeptides with Mr 73,000 and 65,000 identified as lysyl- and arginyl-tRNA synthetase, respectively (Dang et al. (1982) Biochemistry 21,1959-1966). Using the modified hydrodynamic theory of Kirkwood (Kirkwood, J.R. (1954) J. Polym. Sci. 12,1-14), we have determined that the model most consistent with the hydrodynamic properties of the 12 S complex is a tetrameric tetrahedral model.

Amino Acyl-tRNA Synthetases↗
PubMed1983

Characterization of a homogeneous arginyl- and lysyl-tRNA synthetase complex isolated from rat liver. Kinetic mechanism for lysyl-tRNA synthetase.

Bisubstrate kinetics and end product and dead end inhibition studies were performed on lysyl-tRNA synthetase isolated from rat liver. The kinetic patterns obtained are consistent with a sequential ordered mechanism of substrate addition, tRNA bound first, followed by lysine, and then by ATP. Pyrophosphate and AMP are released in a random fashion with aminoacylated tRNA the last product to dissociate from the enzyme. This is the first report of a kinetic mechanism for lysyl-tRNA synthetase.

Amino Acyl-tRNA Synthetases↗
PubMed1983

Multienzyme complexes of eukaryotic aminoacyl-tRNA synthetases.

Eukaryotic aminoacyl-tRNA synthetases, unlike their prokaryotic counterparts, may occur as high-Mr multienzyme complexes. Recently, successful purification of synthetase complexes makes possible the elucidation of the structural organization of these high-Mr complexes. Although their physiological significance remains unknown, recent studies suggest some possible functional roles for these complexes.

Amino Acids↗
PubMed1983

Association of methionyl-tRNA synthetase with detergent-insoluble components of the rough endoplasmic reticulum.

Using fluorescent antibody staining, we have established the association of methionyl-tRNA synthetase with the endoplasmic reticulum in PtK2 cells. After Triton X-100 extraction, 70% of the recovered aminoacyl-tRNA synthetase activity was found in the detergent-insoluble fraction. This fraction of the enzyme remained localized with insoluble endoplasmic reticulum antigens and with ribosomes, which were stained with acridine orange. By both fluorescence microscopy and electron microscopy the organization of the detergent-insoluble residue was found to depend on the composition of the extracting solution. After extraction with a microtubule-stabilizing buffer containing EGTA, Triton X-100, and polyethylene glycol (Osburn, M., and K. Weber, 1977, Cell, 12:561-571) the ribosomes were aggregated in large clusters with remnants of membranes. After extraction with a buffer containing Triton X-100, sucrose, and CaCl2 (Fulton, A. B., K. M. Wang, and S. Penman, 1980, Cell, 20:849-857), the ribosomes were in small clusters and there were few morphologically recognizable membranes. In both cases the methionyl-tRNA synthetase and some endoplasmic reticulum antigens retained approximately their normal distribution in the cell. Double fluorochrome staining showed no morphological association of methionyl-tRNA synthetase with the microtubule, actin, or cytokeratin fiber systems of PtK2 cells. These observations demonstrate that detergent-insoluble cellular components, sometimes referred to as "cytoskeletal" preparations, contain significant amounts of nonfilamentous material including ribosomes, and membrane residue. Caution is required in speculating about intermolecular associations in such a complex cell fraction.

Amino Acyl-tRNA Synthetases↗
PubMed1982

Trauma of the colon: early drop-back of exteriorized repair.

Exteriorized repair of selected colonic injuries has been reported to be successful. Eighty-two colonic injuries were reviewed to determine the indications for primary repair, exteriorized repair, or colostomy and to assess the feasibility of early drop-back of the exteriorized repaired colon. Injuries were graded into three stages: stage 1, good risk; stage 2, moderate risk; and stage 3, bad risk. Sixty-seven percent of patients with stage 1 injuries underwent primary repair, 61% of patients with stage 2 injuries underwent exteriorized repair, and 61% of patients with stage 3 injuries received a colostomy. Of 38 patients who had exteriorized repair, 29 (76%) had their colon successfully dropped back on an average of five days postoperatively. Nine patients had their exteriorized colon converted to a colostomy on an average of 5.5 days postoperatively. The overall mortality was 2.4%; however, the mortality of the patients with exteriorized repair was 0%. Exteriorized repair with early drop-back is safe and economical for most patients with stage 2 injuries and selected patients with stage 3 injuries.

Adolescent↗
PubMed1982

Severe liver trauma in the face of coagulopathy. A case for temporary packing and early reexploration.

Most liver injuries lend themselves to satisfactory hemostasis and drainage, with or without resectional debridement. A small number of injuries will necessitate massive blood transfusion with clinically significant coagulopathy developing in about half of these patients despite prophylactic infusion of fresh frozen plasma and platelet concentrates. In our experience, after major, discrete arterial and venous vessels are individually ligated, the diffuse ooze from the raw surfaces can be effectively controlled by temporary packing of the liver. Packing provides time for coagulopathy and hypothermia to be corrected and for urgent diagnostic maneuvers to be completed safely. Packs should be removed early (within 24 to 48 hours postoperatively), and surgery performed as indicated by the injury. No intraabdominal abscesses have been encountered among our 12 patients who underwent temporary packing of their liver injuries.

Adolescent↗
PubMed1981

Tobacco-alcohol amblyopia: a proposed biochemical basis for pathogenesis.

Tobacco-alcohol or nutritional amblyopia is a rare disorder of decreased central vision associated with nutritional deficiencies and tobacco smoking. although folate deficiency is common in patients with tobacco-alcohol amblyopia, the role of folic acid in this disorder has been underplayed. The role of cyanide from tobacco smoke, folate and other dietary deficiencies will be reviewed. A new model of the pathogenesis of tobacco-alcohol amblyopia is proposed based on the presumptive alteration of methionine and S-adenosyl-L-methionine metabolism.

Alcoholism↗
PubMed1978

Splenic function following experimental dearterialization injury in the suckling rat.

An experimental splenic dearterilization injury was created in 1-wk-old rats to study the effect of vascular trauma on splenic function. Splenic weight significantly decreased 1 wk following injury but returned to control values within a month. Total splenic nuclear activity diminished initially but increased to above control values 1 mo after injury, and finally returned to normal at 2 mo. Survival rate after an intraperitoneal challenge with pneumococcus in groups 1 wk following total splenectomy and partial dearterlization was not significantly different than controls. This study confirmed the clinical impression that vascular injury to the spleen causes only a transient impariment of splenic size and function and provides further incentive to perform splenorrhaphy following splenic trauma.

Animals↗