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Biomedical subjects

C E Georgi

Publications and source records attributed to C E Georgi.

8 recordsLinked to original sources
PubMed1972

Effect of maltose on glucoamylase formation by Aspergillus niger.

Low levels of glucoamylase are produced when Aspergillus niger is grown on sorbitol, but substitution of the latter by glucose, maltose, or starch results in greater formation of glucoamylase as measured by enzymatic activity. Both glucoamylase I and glucoamylase II are formed in a yeast extract medium; however, glucoamylase I appears to be the only form produced when ammonium chloride is the nitrogen source. Maltose or isomaltose (1.4 x 10(-4)m), but no other disaccharides or monosaccharides, dextrins, dextrans, or starches, stimulated glucoamylase formation when added to mycelia pregrown on sorbitol-ammonium salts. The induction of glucoamylase by maltose was independent of sulfate concentration but showed a dependency on low pH and the absence of utilizable carbon sources.

Aspergillus↗
PubMed1969

Transferable drug resistance among Enterobacteriaceae isolated from human urinary tract infections.

Fifteen sulfonamide-resistant cultures isolated from urinary tract infections in eastern Nebraska were screened for transferable drug resistance by three methods. Seven of the 15 resistant cultures could transfer resistance of varying levels to two or more chemotherapeutic agents. Transfer of drug resistance occurred without accompanying transfer of chromosomal traits and required cell to cell contact. In mixed culture, the number of drug-resistant recipients increased exponentially, reaching a plateau 2 hr after mixing. Spontaneous or artificial elimination of resistance was found to be a rare event. In addition, several drug-sensitive isolates from urinary tract infections were shown to be competent recipients of drug resistance determinants. From these data, it appears that the transferable drug resistance observed was mediated by R factors.

Chloramphenicol↗
PubMed1969

Transfer of infectious drug resistance in microbially defined mice.

Germ-free mice were intentionally associated with drug-resistant donor strains of Escherichia coli known to carry R factors and with drug-sensitive recipient strains. In vivo transfer of R factors was observed in all experiments, involving five different donor-recipient combinations. The number of converted recipients varied, depending upon the donor-recipient combination, but in all cases it was restricted by limiting numbers of either recipient or donor strains in the digestive tract of the microbially defined mice. Converted recipients were detected in fecal material as early as 5.5 hr after mice were associated with donor and recipient bacteria. Donors, recipients, and converted recipients were detectable in the stomach, small intestine, cecum, and large intestine of the microbially defined mice and their suckling young.

Animals↗
PubMed1969

Phospholipids from Bacillus stearothermophilus.

The lipids of Bacillus stearothermophilus strain 2184 were extracted with chloroform-methanol and separated into neutral lipid and three phospholipid fractions by chromatography on silicic acid columns. The phospholipids were identified by specific staining reactions on silicic acid-impregnated paper, by chromatography of alkaline and acid hydrolysis products, and by determination of acyl ester:glycerol:nitrogen:phosphorus molar ratios. The total extractable lipid was 8% of the dry weight of whole cells and consisted of 30 to 40% neutral lipid and 60 to 70% phospholipid. The phospholipid consisted of diphosphatidyl glycerol (23 to 42%), phosphatidyl glycerol (22 to 39%), and phosphatidyl ethanolamine (21 to 32%). The concentrations of diphosphatidyl glycerol and phosphatidyl glycerol were lower in 2-hr cells than in 4- and 8-hr cells. Whole cells were fractionated by sonic treatment and differential centrifugation. The total lipid content, expressed in per cent of dry weight of each fraction was: whole protoplasts, 10%; membrane fraction, 18%; 30,000 x g particulate fraction, 22%; and 105,000 x g particulate fraction, 26%. The relative phospholipid concentrations in each fraction were about the same. As had been previously reported, none of the phospholipid was stable to alkaline hydrolysis.

Alkalies↗