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Biomedical subjects

G Oliver

Publications and source records attributed to G Oliver.

171 records · Page 10Linked to original sources
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Isolation and properties of beta-galactosidase of a strain of Lactobacillus helveticus isolated from natural whey starter.

beta-Galactosidase has been isolated from Lactobacillus helveticus of a strain isolated from natural starters for the manufacture of Argentine hard cheeses and its properties have been studied. The enzyme was purified 14-fold (by chromatography on DEAE-cellulose and Sepharose 6B-DEAE-cellulose columns and by affinity chromatography in agarose-p-aminophenyl-beta-D-thiogalactoside). The purified extract exhibited a single band following polyacrylamide gel electrophoresis. Maximum enzymatic activity was observed at 42 degrees C and pH 6.5 in 50 mM phosphate buffer. At pH values substantially different from the optimum, a positive cooperativity between substrate molecules was observed. The Km's for o-nitrophenylgalactoside (ONPG) and ONPG + 10 mM of lactose were 4.46 X 10(-5) and 8.9 X 10(-5) M, respectively. Glucose, galactose, galactose 6-phosphate, and lactate acted as noncompetitive inhibitors; MgCl2 protected the enzyme from thermal denaturation. The activation energy of enzymatic hydrolysis of ONPG was 11,400 cal/mol. The Mr was estimated to be 250,000. It is an oligomeric enzyme made of 4 subunits of Mr 65,000.

Animals↗
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Purification and properties of malolactic enzyme from Lactobacillus murinus CNRZ 313.

The malolactic enzyme of Lactobacillus murinus was purified 79 fold. Mr = 220,000 as determined by gel filtration and gradient gel electrophoresis. The enzyme consists of two apparently identical subunits (Mr = 110,000) that were observed after treatment with sodium dodecyl sulfate. NAD protected the enzyme against inactivation and its addition, after dissociation, restored the malolactic activity. The apparent Km's for malate, NAD, and Mn2+ were 2.31 X 10(-2), 4.5 X 10(-4), and 1.4 X 10(-4) mM, respectively. Maximum enzymatic activity was observed at 37 degrees C and pH 5.5 in 0.2 M phosphate buffer. At pH values substantially different from the optimum, a positive cooperativity between substrate molecules was observed. The activation energy of the reaction was 8000 and 16,200 cal mol-1 for the temperature values more than and less than 30 degrees C, respectively. Malolactic enzyme catalyzes the NAD and manganese-dependent reaction L-malate----L-lactate + CO2. Therefore, this enzyme can be distinguished from the well-known malic enzymes [L-malate: NAD+ oxidoreductase, oxaloacetate decarboxylating (EC 1.1.1.38) or decarboxylating (EC 1.1.1.39)].

Chlorides↗
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[Endoscopic-histopathological correlation in gastric lymphoma diagnosis: the experience of an oncologic institute].

Among the Gastric Lymphoma' chief features are the varied endoscopic appearances and the difficulty for its conventional bioptic diagnosis. In order to focusing on this problem we analyzed 15 years of experience on this matter at the "Luis Razetti" Oncological Institute. 10 cases were morphologicaly classified as follow: a) Exophytic type 5/50%. The most difficult morphology for its endoscopic diagnosis was the infiltrative type, in its large gastric folds category 2/20%, yielding a 33% of bening diagnosis. Histopathologicaly a 66% of bening diagnosis was obtained and a 33% of uncertain diagnosis. The exophytic type in its erosive protruding mass category was the second most difficult morphology fot both endoscopic and histopathologic diagnosis. When the last two categories were associated with ulceration, the malignant diagnosis increased. 40 of the cases were operated on without preoperative histological diagnosis. All the cases were operated on without preoperative histological diagnosis. All the cases corresponded with Large cells diffuse type of Non Hodgkin's Lymphoma, a diagnosis reached in only one opportunity by endoscopic biopsy. No correlation between tumoral morphology and intraparietal growth was found. 3 patients survived for more than 1 years. It can be concluded that video endoscopic methods could help to improve the endoscopic knowledge in gastric lymphoma diagnosis, while polipectomy snare biopsy, dye methods like Indigo Carmin and special techniques like mucosectomy could help to improve the histologic diagnosis, because conventional biopsy provides small and superficial samples.

Adolescent↗