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Biomedical subjects

G E Austin

Publications and source records attributed to G E Austin.

84 records · Page 5Linked to original sources
PubMed1978

Purification and properties of polynucleotide kinase of calf thymus.

Polynucleotide kinase (ATP:5'-dephosphopolynucleotide 5'-phosphotransferase, EC 2.7.1.78) has been purified approx. 1500-fold from calf thymus. This enzyme phosphorylates 5'-hydroxyl termini in DNA using ATP as phosphate donor. RNA is phosphorylated at a much lower rate than DNA. The reaction requires the presence of a divalent cation, preferably Mg2+ or Mn2+ and is sensitive to sulfhydryl antagonists. The optimum pH for enzyme activity is 5.5. Enzyme activity is inhibited by low concentrations of inorganic sulfate and by some sulfate polymers. The kinase-catalyzed incorporation of the terminal phosphate of ATP into polynucleotides is inhibited by other nucleoside and deoxynucleoside triphosphates. The enzyme molecule has a molecular weight of about 70 000 and a Stokes radius of 4.3 nm. It has a frictional ratio of 1.44 indicating an asymmetrical structure. Calf thymus tissue should provide a useful alternative source for preparation of mammalian polynucleotide kinase.

Adenosine Triphosphate↗
PubMed1978

Signet ring cell carcinoma of bladder.

The ninth reported case of primary signet ring cell carcinoma of the bladder is described. This particular tumor, whose histology was examined repeatedly during its evolution, showed an interesting change in microscopic appearance after irradiation. The emerging features of signet ring cell carcinoma of the bladder are discussed.

Adenocarcinoma, Mucinous↗
PubMed1977

Binding of N-hydroxy acetylaminofluorene to eu- and heterochromatin fractions of rat liver in vivo.

The in vivo binding of N-hydroxy acetylaminofluorene (N-OH AAF) to rat liver DNA was studied in hetero- and euchromatin fractions prepared by sedimentation through sucrose gradients. The greater transcriptional capacity of the slowly sedimenting (euchromatin) fractions was confirmed by their enhanced incorporation of radioactive precursors into RNA in vivo and their increased template activity for in vitro RNA synthesis by purified RNA polymerase. N-OH AFF was bound in 4- to 5-fold greater amounts to euchromatin DNA than to heterochromatin 2 h after a single injection of the compound. However, the bound carcinogen appeared to be eliminated more rapidly from euchromatin than from heterochromatin by DNA repair processes.

Animals↗
PubMed1976

Cerebral embolization resulting from esophageal-atrial fistula.

A rare but catastrophic complication of nontraumatic esophageal perforation is the formation of an esophageal-left atrial fistula. Although surgical correction of this condition should be possible, failure to recognize it antemortem has thus far prevented such intervention. A woman with long-standing severe esophagitis, was admitted with hematemesis and acute neurologic abnormalities that progressed to coma and death. A similar picture of chronic esophagitis terminating in uppergastrointestinal-tract bleeding accompanied by neurologic signs was seen in the three previously reported cases as well. Recognition of this symptom complex should permit future cases to be diagnosed clinically, and, it is hoped, corrected.

Adult↗
PubMed1975

RNA polymerase isolated from bovine lymphosarcoma by sequential low- and high-salt extraction.

Bovine lymphosarcoma tissue has been extracted with low- and high-salt buffers [0.05 M Tris-C1 plus or minus 0.3 M (NH4) 2S04]. Diethylaminoethyl-Sephadex chromatography of both the high-salt and low-salt extracts yields RNA polymerases I and II, although low-salt extraction releases only one-third as much activity. Extraction by high salt of the residue from the low-salt extract, followed by diethylaminoethyl-Sephadex chromatography, yields additional enzyme activity with properties of Form II. Purification of the low-salt extract by protamine precipitation, elution with sodium succinate, and phosphocellulose chromatography yields a preparation of RNA polymerase (RNAP) with hybrid properties, combining the salt optimum of Form I, diethylaminoethyl-Sephadex elution pattern of form II, and alpha-amanitin sensitivity of Form III. RNAP. transcribes native D,A and chromatin efficiently. More RNAPL is recovered from lymphosarcoma tissue than from calf thymus.

Amanitins↗
PubMedDate not supplied

Serum lipoprotein levels fail to predict postangioplasty recurrent coronary artery stenosis.

A prospective study to explore the role of serum lipoproteins in the development of recurrent stenosis after percutaneous transluminal coronary angioplasty was conducted on serum samples from 103 patients. Serum was collected at the time of angioplasty and evaluated for total cholesterol, total triglycerides (TG), high-density lipoprotein (HDL) cholesterol, low-density lipoprotein (LDL) cholesterol, very low-density lipoprotein cholesterol, and apolipoproteins A1 and B. In addition, LDL cholesterol/HDL cholesterol ratios and apolipoprotein B/A1 ratios were calculated for each sample. Information was then gathered from four years of follow-up after angioplasty, which was sufficient to establish the presence or absence of recurrent stenosis in 87 patients (68 males and 19 females). Stenosis recurred in 31 of the 87 patients (36%); the rate was similar for males (35%) and females (37%). Univariate analysis of the total patient population revealed no statistically significant difference in values for any of these lipoprotein parameters between success and recurrence groups. Likewise, multivariate analysis revealed no combination of lipoprotein values to be associated with success or recurrence. Findings were similar for the males alone and the total group of males and females. The female group was too small for separate statistical analysis. The power of this study to detect meaningful differences in each of these parameters except TG was at least 80%. These results do not support the hypothesis that lipoprotein factors influence the development of recurrent stenosis in patients undergoing coronary angioplasty.

Angioplasty, Balloon↗
PubMedDate not supplied

Comparison of carcinoembryonic antigen in tissue and serum with grade and stage of colon cancer.

BACKGROUND: Serial plasma carcinoembryonic antigen (CEA) levels are routinely used to detect postoperative recurrence of colon cancers. However, levels of intrinsic CEA production by individual tumors, which might be helpful for interpreting serum CEA levels, are not routinely available. MATERIALS AND METHODS: CEA levels were determined in twenty tissue biopsy specimens of colon carcinoma and sixteen normal colonic tissue specimens from India, by immunohistochemistry (IH) and by quantitative enzyme immunoassay (EIA). Serum samples from 62 colon cancer patients and 25 healthy blood donors were analyzed for CEA by EIA. RESULTS: Tissue CEA levels were highest for well differentiated adenocarcinomas (5.2-37 micrograms/g protein) with progressively lower levels seen in moderately differentiated and poorly differentiated tumors, and in normals. The intensity of immunostaining paralleled the levels determined quantitatively. Mean serum CEA levels were 1.5 ng/ml for normals and 4.2, 6.4, 23, and 102 ng/ml for Dukes' A, B, C and D stage tumors, respectively. CONCLUSION: Preoperative serum CEA levels do not, in themselves, take into account differences in CEA production between individual tumors. Determination of tumor CEA content by quantitative or immunohistochemical methods, could be a useful adjunct for the clinical management of colon carcinoma, by improving interpretation of serum CEA levels.

Adenocarcinoma↗