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Biomedical subjects

V Subramanian

Publications and source records attributed to V Subramanian.

At least 73 records · Page 4Linked to original sources
PubMed1995

The mouse angiogenin gene family: structures of an angiogenin-related protein gene and two pseudogenes.

Angiogenin, a homologue of pancreatic ribonuclease, is a potent inducer of blood vessel formation. As an initial step toward investigating the in vivo functional role of this protein via gene disruption, we undertook the isolation of the angiogenin gene (Ang) from the 129 strain mouse, which will be used for generating targeting constructs. Unexpectedly, screening of a genomic library with an Ang gene probe obtained previously from the BALB/c strain yielded two new genes closely similar to Ang rather than Ang itself. One of these encodes a protein with 78% sequence identity to angiogenin and is designated "Angrp" for "angiogenin-related protein." The ribonucleolytic active site of angiogenin, which is critical for angiogenic activity, is completely conserved in Angrp, whereas a second essential site, thought to bind cellular receptors, is considerably different. Thus, the Angrp product may have a function distinct from that of angiogenin. The second gene obtained by library screening is a pseudogene, designated "Ang-ps1," that contains a frameshift mutation in the early part of the coding region. Although the Ang gene was not isolated from this library, it was possible to amplify this gene from 129 mouse genomic DNA by the polymerase chain reaction (PCR). Sequence analysis showed that the 129 strain Ang gene is identical to the BALB/c gene throughout the coding region. PCR cloning also yielded a second Ang-like pseudogene, designated "Ang-ps2." Southern blotting of genomic DNA confirmed the presence of Ang, Angrp, and at least one of the pseudogenes in an individual mouse and suggested that the mouse Ang gene family may contain more than the four members identified here.

Amino Acid Sequence↗
PubMed1992

Crystallization and preliminary X-ray analysis of human angiogenin.

Crystals of recombinant human angiogenin have been grown from solutions containing sodium potassium tartrate and polyethylene glycol as precipitants. They belong to the space group C222(1) (a = 83.36 A, b = 120.64 A, c = 37.72 A) and contain a single molecule in the asymmetric unit. The crystals diffract to at least 2.3 A resolution and are suitable for three-dimensional X-ray structural analysis.

Crystallization↗
PubMed1989

A malignant, stem cell-like somatic hybrid between a mouse teratocarcinoma and a rat ascitic hepatoma is differentiation competent.

A hybrid clone was developed by the fusion of a pluripotent mouse teratocarcinoma cell line PCC-4 AzaR to the Zajdela ascitic hepatoma (ZAH) of rat origin. This hybrid cell line, F2231A, possessed a predominantly teratocarcinoma morphology with a large nucleus and prominent nucleoli, and grew in nests. F2231A cells formed undifferentiated tumours in irradiated Sv/129 mice. It formed aggregates when subcultured at high densities in bacteriological Petri dishes. The hybrid cell line differentiated in response to retinoic acid and also underwent spontaneous differentiation upon overgrowth. Karyological analysis showed the presence of several rat chromosomes in the hybrid and upon isozyme analysis it was found that only the rat variant of the X-linked enzyme HGPRT was expressed. Analysis of the genomic DNA with a cloned probe, specific for rat repetitive sequences, gave strong positive signals in the hepatoma parent and F2231A cells while the parental embryonal carcinoma (EC) cells were negative. The hybrid cell line, like the PCC-4 cells, expressed the SSEA-1 surface marker but not SSEA-3, intercellular fibronectin and EGF receptors. Upon differentiation of F2231A cells there was a loss of expression of SSEA-1. The mRNA for alpha-fetoprotein was expressed by the hybrid cell line and in this respect it resembled the hepatoma parent. Albumin mRNA was not detectable in the hybrid cell line. The mRNA for the transformation-related protein, p53, was expressed at a high level in F2231A cells. The hybrid cell line F2231A retained several of the biochemical and immunological properties of the teratocarcinoma cells.

Animals↗
PubMed1985

Purification and properties of ferredoxinTOL. A component of toluene dioxygenase from Pseudomonas putida F1.

Toluene dioxygenase oxidizes toluene to (+)-cis-1(S),2(R)-dihydroxy-3-methylcyclohexa-3,5-diene. This reaction is catalyzed by a multienzyme system that is induced in cells of Pseudomonas putida F1 during growth on toluene. One of the components of toluene dioxygenase has been purified to homogeneity and shown to be an iron-sulfur protein that has been designated ferredoxinTOL. The molecular weight of ferredoxinTOL was calculated to be 15,300, and the purified protein was shown to contain 2 g of atoms each of iron- and acid-labile sulfur which appear to be organized as a single [2Fe-2S]cluster. Solutions of ferredoxinTOL were brown in color and showed absorption maxima at 277, 327, and 460 nm. A shoulder in the spectrum of the oxidized protein was discernible at 575 nm. Reduction with sodium dithionite or NADH and ferredoxinTOL reductase resulted in a decrease in visible absorbance at 460 and 575 nm, with a concomitant shift in absorption maxima to 382 and 438 nm. The redox potential of ferredoxinTOL was estimated to be -109 mV. In the oxidized state, the protein is diamagnetic. However, upon reduction it exhibited prominent electron paramagnetic resonance signals with anisotropy in g values (gx = 1.81, gy = 1.86, and gz = 2.01). Anaerobic reductive titrations revealed that ferredoxinTOL is a one-electron carrier that accepts electrons from NADH in a reaction that is mediated by a flavoprotein (ferredoxinTOL reductase). The latter is the first component in the toluene dioxygenase system. Reduced ferredoxinTOL can transfer electrons to cytochrome c or to a terminal iron-sulfur dioxygenase (ISP-TOL) which catalyzes the incorporation of molecular oxygen into toluene and related aromatic substrates.

Amino Acids↗
PubMed1984

Anthranilate hydroxylase from Aspergillus niger: new type of NADPH-linked nonheme iron monooxygenase.

Anthranilate hydroxylase from Aspergillus niger catalyzes the oxidative deamination and dihydroxylation of anthranilic acid to 2,3-dihydroxybenzoic acid. This enzyme has been purified to homogeneity and has a molecular weight of 89,000. The enzyme is composed of two subunits of 42,000 with 2 gram-atoms of nonheme iron per mol. Fe2+-chelators like alpha,alpha'-dipyridyl and o-phenanthroline are potent inhibitors of the enzyme activity. Absorption and fluorescence spectra of the enzyme offer no evidence for the presence of other cofactors like flavin. Flavins and flavin-specific inhibitors like atebrin have no effect on the activity of the enzyme. The enzyme incorporates one atom of oxygen each from 18O2 and H218O into the product 2,3-dihydroxybenzoic acid. Based on these studies, it is concluded that anthranilate hydroxylase from A. niger is a new type of NADPH-linked nonheme iron monooxygenase.

Aspergillus niger↗
PubMed1984

Isolation and characterization of Pseudomonas putida PpF1 mutants defective in the toluene dioxygenase enzyme system.

Pseudomonas putida PpF1 degraded toluene via a dihydrodiol pathway to tricarboxylic acid cycle intermediates. The initial reaction was catalyzed by a multicomponent enzyme, toluene dioxygenase, which oxidized toluene to (+)-cis-1(S),2(R)-dihydroxy-3-methylcyclohexa-3,5-diene (cis-toluene dihydrodiol). The enzyme consisted of three protein components: NADH-ferredoxintol oxidoreductase (reductasetol), ferredoxintol, and a terminal oxygenase which is an iron-sulfur protein (ISPtol). Mutants blocked in each of these components were isolated after mutagenesis with nitrosoguanidine. Mutants occurred as colony morphology variants when grown in the presence of toluene on indicator plates containing agar, mineral salts, a growth-supporting nutrient (arginine), 2,3,5-triphenyltetrazolium chloride (TTC), and Nitro Blue Tetrazolium (NBT). Under these conditions, wild-type colonies appeared large and red as a result of TTC reduction. Colonies of reductasetol mutants were white or white with a light blue center, ferredoxintol strains were light blue with a dark blue center, and strains that lacked ISPtol gave dark blue colonies. Blue color differences in the mutant colonies were due to variations in the extent of NBT reduction. Strains lacking all three components appeared white. Toluene dioxygenase mutants were characterized by assaying toluene dioxygenase activity in crude cell extracts which were complemented with purified preparations of each protein component. Between 40 and 60% of the putative mutants selected from the NBT-TTC indicator plates were unable to grow with toluene as the sole source of carbon and energy. This method should prove extremely useful in isolating mutants in other multicomponent oxygenase enzyme systems.

Genetic Complementation Test↗
PubMed1983

Differential inhibition by aspirin of vascular and platelet prostaglandin synthesis in atherosclerotic patients.

We studied the ability of a single oral dose of aspirin to inhibit prostacyclin synthesis by human arterial and venous tissue and to inhibit thromboxane A2 synthesis by platelets in 70 patients who were undergoing aortocoronary bypass. A dose of 40, 80, or 325 mg of aspirin was administered 12 to 16 hours before surgery. The generation of thromboxane in serum--which provides an estimate of platelet thromboxane production--was reduced from the control value by 77, 95, and 99 per cent after single doses of 40, 80, and 325 mg of aspirin, respectively. By contrast, prostacyclin production in aortic tissue that was removed at operation was reduced by only 35, 38, and 75 per cent, respectively, in response to these doses. Production of prostacyclin in saphenous-vein tissue (not tested after 40 mg of aspirin) fell only slightly and not significantly after 80 mg but was reduced by 85 per cent after 325 mg. These findings indicate that a low dose of aspirin (40 to 80 mg) can largely inhibit platelet aggregation and thromboxane synthesis but has much less effect on prostacyclin production in arterial and venous endothelium.

Administration, Oral↗
PubMed1982

Percutaneous wire-guided balloon pumping.

A percutaneous wire-guided double lumen intraaortic balloon pump was tested in 44 patients, 15 with cardiogenic shock. The balloon volume is 40 ml, the material is Avcothane, and the central lumen will pass a 0.035 inch (0.889 mm) wire guide. Standard Seldinger technique was followed by successful insertion in 40 patients (90 percent) with no recognized vascular trauma. Counterpulsation was excellent and central pressure monitoring through the balloon lumen showed good fidelity. Iliofemoral thrombosis occurred in 5 percent of patients. The overguide technique is simple, successful and atraumatic.

Adult↗
PubMed1982

Myocardial free-wall rupture after acute infarction: survival aided by percutaneous intraaortic balloon counterpulsation.

After his first acute myocardial infarction, a 69-year-old male suffered the usually lethal complication of ventricular free-wall rupture. Early suspicion of possible rupture and immediate percutaneous insertion of an intraaortic balloon pump assist device afforded sufficient hemodynamic stability to proceed with cardiac catheterization. The diagnosis of ventricular free-wall rupture was confirmed and the extent of coronary artery disease defined. The patient underwent repair of the free-wall rupture and coronary artery bypass grafting and has returned to full activity.

Aged↗
PubMed1981

Purification and properties of NADH-ferredoxinTOL reductase. A component of toluene dioxygenase from Pseudomonas putida.

Cells of Pseudomonas putida, after growth with toluene, contain a multicomponent enzyme system that oxidizes toluene to (+)-1(S),2(R)-dihydroxy-3-methyl-cyclohexa-3,5-diene. One of these components has been purified to homogeneity and shown to be a flavoprotein that contains FAD as the only detectable prosthetic group. Fad was removed from the enzyme during purification. However, equilibrium dialysis experiments showed that the enzyme can bind one mol of FAD/mol of enzyme protein. The apparent molecular weight of the enzyme is 46,000, as judged by gel filtration and polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate and mercaptoethanol. The latter result suggests the presence of a single polypeptide chain. The amino acid composition of the enzyme reveals a relatively high content of the hydrophobic amino acids leucine, isoleucine, and valine and is remarkably similar in composition to the flavoproteins that function in certain monooxygenase enzyme systems. The purified enzyme catalyzes the reduction of dichloroindophenol, nitrobluetetrazolium, ferricyanide, and ferredoxinTOL. Its ability to reduce cytochrome c and to function in the toluene dioxygenase enzyme system is absolutely dependent on the presence of ferredoxinTOL.

Amino Acids↗
PubMed1980

Splenic T and B lymphocytes and their mitogenic response in untreated Hodgkin's disease.

The splenic T and B cell distribution in 79 patients with untreated Hodgkin's disease was quite similar to that in 15 control patients with non-Hodgkin's lymphoma or carcinoma. The mean T lymphocyte percentage was slightly higher in involved spleens than in uninvolved spleens of patients with Hodgkin's disease. There was no significant difference in the T and B cell distribution between tumor area and tumor-free area of the same spleens of Hodgkin's disease patients. Splenic T and B cell distribution did not correlate well with the clinical features of Hodgkin's disease. The splenic T cell percentage was significantly lower than that of the peripheral blood T cell percentage (P less than 0.05), while the splenic B cell percentage was significantly higher than peripheral blood B cell percentage (P less than 0.01) in 13 patients with untreated Hodgkin's disease. The splenic T lymphocyte response to PHA was significantly higher than the peripheral blood T lymphocyte response (P less than 0.05), and the splenic B lymphocyte response to PHA, in the presence of irradiated autologous splenic T lymphocytes, was also significantly higher than the peripheral blood B lymphocyte response (P less than 0.05) in 8 and 6 patients with untreated Hodgkin's disease, respectively. Since the control splenic cells, utilized in this study were obtained not from patients with non-neoplastic disease, but from patients with neoplastic disease other than Hodgkin's disease, our data are not conclusive, but only suggestive of normal T and B cell distribution and function in uninvolved spleens of patients with untreated Hodgkin's disease.

Adolescent↗
PubMed1977

Managment of thoracic empyema.

Over a ten year period, 102 patients with thoracic empyemata were treated at Boston City Hospital. Only three patients died from the pleural infection while twenty-six succumbed to the associated diseases. Priniciples of management include: (1) thoracentesis; (2) antibiotics; (3) closed-tube thoracostomy; (4) sinogram; (5) open drainage; (6) empyemectomy and decortication in selected patients; and (7) bronchoscopy and barium swallow when the etiology is uncertain.

Adolescent↗