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Biomedical subjects

M Mandel

Publications and source records attributed to M Mandel.

At least 109 records · Page 6Linked to original sources
PubMed1980

Mutagens in extracts of human gastric mucosa.

Extracts of mucosa from 53 stomachs were tested for mutagenicity with the use of Salmonella typhimurium strains TA98 and TA100. Mutagenic activity was observed in nonneoplastic mucosa from seven stomachs with S. typhimurium strain TA98 without the S-. mix (a rat liver microsomal enzyme preparation) and in three stomachs with TA100 without S-. mix. All of the TA98 mutagenic samples were derived from stomachs showing evidence of intestinal metaplasia. The exception was an extract of corpus mucosa that was mutagenic with strain TA100. "Transnitrosoase" activity was found in 12 of 53 samples, all of which showed TA98 mutagenicity. Whether the presence of mutagens and transnitrosoase activity causes intestinal metaplasia or results from it is uncertain.

Gastric Mucosa↗
PubMed1979

Genetic transformation of Pseudomonas phaseolicola by R-factor DNA.

The bacterium Pseudomonas phaseolicola was successfully transformed, for the first time, with R-factors RSF1010 and pBR322 DNA by a calcium-shock and heat-pulse technique. Frequency of transformation for RSF1010 ranged from 0.8 x 10(-7) to 3.1 x 10(-6) and was ca. 0.4 x 10(-8) for pBR322.

DNA, Bacterial↗
PubMed1979

Multi-user system for analysis of data from flow cytometry.

A new program is described for the analysis of DNA histograms from flow cytometry. The fundamental model representing the cell population is similar to one described previously. It assumes the population is grouped into compartments, each consisting of cells having approximately the same DNA content. After staining the cells with an appropriate fluorochrome, the fluorescence distribution of cells within each compartment is assumed to be Gaussian. In the present algorithm, the parameters of the model can either be computed directly by the program from the data, or can be specified as input by the user. When synchronous cell populations lacking distinct G1 and G2/M phases are analyzed, the parameter values must first be obtained using an appropriate control. Percentages of cells in the various compartments are computed using a gradient search method described by Bevington.

Computers↗
PubMed1979

Electric permittivity and dielectric dispersion of low-molecular weight DNA at low ionic strength.

The dielectric properties of sonicated calf-thymus DNA (MW approximately 3 X 10(5) g mol-1) have been investigated in a frequency range between a few kHz and 100 MHz. Two samples, sonicated in a different way were used after proper characterization including light-scattering, viscometry and contour length distribution by electron microscopy. Dielectric measurements were performed at several concentrations between 10(-4) and 3 X 10(-3) monomol 1-1 and 22 degrees C. Under all circumstances two separated dispersion regions were observed, the corresponding specific increments of which decreased with increasing concentration. The same was observed with the mean relaxation time of the high frequency dispersion. Both the frequency and concentration dependence was largely analogous to what is observed with other polyelectrolytes. Values of the dielectric parameters extrapolated to infinite dilution could also be interpreted in the same manner as for more simple, charged macromolecules and no specific effects had to be taken into account.

DNA↗
PubMed1979

Apparent Involvement of a Plasmid in Phaseotoxin Production by Pseudomonas phaseolicola.

Three naturally occurring toxigenic strains (HB-36, G-50, and HB-33), one nontoxigenic strain (HB-20), and one ultraviolet light-induced toxinless mutant (G-50 Tox) of Pseudomonas phaseolicola were examined by dye-buoyant density equilibrium centrifugation for the presence of plasmid deoxyribonucleic acid. All strains contained plasmid deoxyribonucleic acid. Comparison of the plasmid deoxyribonucleic acid of different strains by agarose gel electrophoresis showed that strain G-50 harbored three plasmids, whereas the rest of the strains contained two plasmids each. Irrespective of their toxigenicity, all strains shared the large-sized first plasmid band, but differed with respect to other plasmids. Restriction endonuclease analyses of the plasmids indicated that a 22.50-megadalton plasmid was common to two of the toxigenic strains (HB-36 and G-50). However, strain HB-33, which is also toxigenic, contained a much smaller plasmid (4.23 megadaltons). It is hypothesized that this small plasmid may have arisen by a recombination event from a larger plasmid.

Journal Article↗
PubMed1979

[Carbon assimilation and taxonomic study of Bacillus subtillis and B. licheniformis].

All 14 strains of B. subtilis can use the following 17 sources of carbon and energy: D-glucose, D-mannose, D-glucosamine, salicin, D-ribose, maltose, sucrose, cellobiose, trehalose, arbutin, starch, mannitol, glycerol, glycerate, pyruvate, fumarate, and L-proline. All 15 strains of B. licheniformis can use the following 41 sources of carbon and energy: D-glucose, D-galactose, D-mannose, D-fructose, D-glucosamine, alpha-methyl-D-glucoside, beta-methyl-D-glucoside, salicin, D-gluconate, saccharate, D-xylose, L-arabinose, L-rhamnose, D-ribose, maltose, sucrose, cellobiose, melibiose, trehalose, arbutin, raffinose, starch, inulin, mannitol, D-sorbitol, glycerol, glycerate, citrate, L-malate, D-malate, mucate, pyruvate, fumarate, alpha-L-alanine, alpha-D-alanine, asparagine, L-glutamate, L-arginine, DL-ornithine, L-proline, and 4-amino-n-butyrate. The 29 strains form two distinct groups. Group A includes the 15 strains of B. licheniformis and 2 strains of B. subtilis; group B is formed of 11 strains of B. subtilis; the remaining strain of B. subtilis belongs to neither group. Bacillus licheniformis is a more homogeneous species than B. subtilis. The percentage of guanine + cytosine in the DNA of all 29 strains was determined. In the 14 strains of B. subtilis the average is 46.3% +/- 1.5. In the 15 strains of B. licheniformis the average is 46.4% +/- 0.9.

Bacillus↗
PubMed1979

Colon cancer: its precursors and companions in Hawaii Japanese.

Following migration to Hawaii, the Japanese have acquired the same risk of developing large bowel cancer as that experienced by Caucasians. This tumor is uncommon in Japan. Other conditions are also more common in Hawaii Japanese, e.g., myocardial infarction, severe atherosclerosis, diverticulosis, and polyposis of the colon. Comparative studies in Hawaii and Japan suggest that the basis of these differences is probably related to the consumption of characteristically western foods by Hawaii Japanese.

Aged↗
PubMed1978

Saltatory thermal denaturation of double-stranded viral RNAs.

The double-stranded RNAs from bacteriophage phi6 and the replicative form of mengovirus denature upon heating in a series of abrupt steps which resemble the subtransitions (thermalites) observed within the high resolution profiles of small, naturally occurring DNA molecules. Such RNA thermalites are approximately an order of magnitude narrower than typical thermal subtransitions of nominally single-stranded RNA. We conclude that the same features of nucleotide sequence that give rise to cooperative denaturation in DNA genomes are to be found also in RNA genomes. Thus, high resolution thermal denaturation profiles are useful for characterizing double-stranded RNA molecules as well as native DNA in the size range of common viruses. A medium containing dimethylsulfoxide was required to lower the Tm of the RNA samples to a satisfactory temperature range. For double-stranded RNA in 50% dimethylsulfoxide, the dependence of Tm on G . C composition was greater than that of DNA in the same medium and also greater than that of double-stranded RNA in an aqueous medium. The fact that RNA thermalites are broader than DNA thermalites and that the melting temperature of double-stranded RNA has a greater dependence on base composition than that of DNA, indicates that at least one of the thermodynamic parameters for double helix formation in RNA is different from that in DNA.

Bacteriophages↗
PubMed1978

[Isolation of bacteria that use that use nitric oxide as a respiratory electron acceptor under anaerobiosis].

Ten bacteria of the genus Bacillus were isolated from pasteurized soils, in anaerobiosis and at 32 degrees C, on peptone broth containing 0.5% KNO2. They are Gram variable rods producing oval spores. They are oxidase positive and have catalase. They grow, in anaerobiosis, on NO-3, NO-2, N2O, and NO as respiratory electron acceptors. These compounds are reduced to N2.

Anaerobiosis↗
PubMed1978

Characterization of DNA binding protein from rat liver chromatin which decreases during growth.

A nuclear nonhistone protein which decreases in chromatin during growth (Yeoman, L. C., et al. (1975) Cancer Res. 35, 1249) has been isolated in high purity from the chromatin of normal rat liver nuclei by gel electrophoresis and column chromatography. This protein, designated BA (Yeoman, L.C., et al. (1973) Biochem Biophys. Res. Commun. 53, 1067), has a molecular weight of 31 000, an acidic to basic amino acid composition ratio of 0.9, and contains one tryptophan residue per molecule. Hydrazinolysis indicated protein BA has a lysine carboxyl terminus; however, the amino terminal is blocked as no reaction occurred with dansyl chloride. Maps of tryptic peptides of protein BA contained 46 spots. Protein BA binding to various DNAs was examined by the nitrocellulose filter assay. Binding was slightly enhanced by 2mM Mn2+ion; Mg2+, however, decreased binding. Binding was optimal at neutral pH and an ionic strength of 0.2 M [NaCl]. Equilibrium competition binding studies indicated a binding preference of protein BA for dA-dT rich DNA.

Aging↗
PubMed1978

Biosynthesis of 5-(4'5'-dihydroxypentyl) uracil as a nucleoside triphosphate in bacteriophage SP15-infected Bacillus subtilis.

The nucleoside triphosphate of 5-(4',5'-dihydroxypentyl)uracil (DHPU) was detected in the acid-soluble extract from bacteriophage SP15-infected Bacillus subtilis W23. No uracil was found in the DNA of either replicating or mature phage. Labeled thymidine added during phage DNA synthesis was incorporated into phage DNA. The presence of DHPU as a nucleoside triphosphate in the acid-soluble pool and the incorporation of thymidine into phage DNA suggest that both DHPU and thymine are incorporated into SP15 DNA via their nucleoside triphosphates. 5-Fluorodeoxyuridine inhibited biosynthesis of SP15 DNA, and this inhibition was reversed by thymidine, resulting in the synthesis of a DNA containing reduced amounts of fully modified DHPU. It is proposed that 5-fluorodeoxyuridine, or its metabolic product, inhibits a step in the biosynthetic pathway to the nucleoside triphosphate of DHPU.

Bacillus subtilis↗
PubMed1978

Incorporation of label from ribose into 5-(4',5'-dihydroxypentyl) uracil of bacteriophage SP15 DNA.

Radioactively labeled ribose was incorporated into the glucosylated deoxynucleoside monophosphate of 5-(4',5'-dihydroxypentyl)uracil of bacteriophage SP15 DNA to a greater extent than into the other pyrimidine deoxynucleoside monophosphates. Results from formic acid hydrolysis of the deoxynucleoside monophosphates to their bases suggest that label from ribose is incorporated into the dihydroxypentyl side chain of 5-(4',5'-dihydroxypentyl)uracil.

Bacillus subtilis↗
PubMed1978

[Physiological study and taxonomy of Alcaligenes species: A denitrificans, A. odorans and A faecalis].

We have studied 43 strains of the species Alcaligenes dentrificans, A. odorans, and A. faecalis. Twenty-five of them were isolated by enrichment culture on minimal medium containing an organic acid (L-malate, succinate, tartrate, adipate, or itaconate) and N2O as a respiratory electron acceptor. These constitute a single phenon with the A. dentrificans strain type and 9 other strains isolated from clinical specimens. However, strain 4 differs from the other 34 strains in 12 nutritional characters, in its ability to effect a meta cleavage of diphenols, and by the absence of tetrathionate reductase. The percentages of G + C are the following: strains isolated from soil, 66.4 +/- 1.1; collection strains, 67.0 +/- 1.3. The 5 strains of A. odorans differ from the 34 strains of A. denitrificans (not including strain 4) in their inability to denitrify nitrate and use D-saccharate, adipate, pimelate, suberate, beta-hydroxy-beta-methylglutarate meso-tartrate, azelate, and itaconate. Their percentage of G + C is much lower: 56.1 +/- 0.4. From the nutritional point of view the 3 strains of A. faecalis resemble A. dentrificans. However, they differ from the latter by their inability to grow anaerobically on NO3-, NO2-, N2O, and by a slightly lower percentage of G+ C: 64.3 +/- 0.0. The 43 strains synthesize poly-beta-hydroxybutyric acid. None of them is chemolithotrophic.

Alcaligenes↗
PubMed1978

Experience with low-dose insulin infusion in diabetic ketoacidosis and diabetic hyperosmolarity.

Forty patients with diabetic ketoacidosis and eight patients with the diabetic hyperosmolar state were treated with low-dose insulin infusion in four teaching hospitals in the Cleveland area. The clinical and biochemical responses observed support previous favorable reports on this treatment modality. Two elderly patients with the hyperosmolar syndrome died. The advantages of this form of treatment over intermittent insulin schedules are emphasized. Early potassium administration, unless otherwise contraindicated, is recommended. Rarely, increasing doses of insulin may be required if insulin resistance is encountered.

Adolescent↗
PubMed1978

[Morphological, physiological and taxonomic studies of Bacillus azotoformans].

Seventeen strains of the new species Bacillus azotoformans were isolated by enrichment culture in peptone broth inoculated with pasteurized soil and then incubated under N2O at 32 degrees C. The bacterium is a Gram-negative rod, motile with peritrichous flagella, which produces oval spores without exosporia in swollen sporangia. However, the cells have thick walls, mesosomes, and persistent septa characteristic of Gram-positive bacteria. The bacterium lacks fermentative activity, does not attack carbohydrates, has complex growth requirements, and will grow anaerobically only if one of the following electron acceptors is present: NO3-, NO2-, N2O, S4O6--, or fumarate. Nitrate, nitrite, and nitrous oxide are denitrified with the production of N2. The microorganism is mesophilic, gives a positive oxidase reaction, synthesizes a type c cytochrome, and does not hydrolyse gelatin, starch, or "Tween 80." Poly-beta-hydroxybutyric acid is snythesized when the bacterium is grown in a medium containing DL-3-hydroxybutyrate. The following enzymes are present: nitrate reductase A, respiratory nitrite reductase, tetrathionate and fumarate reductases, and L-glutamate dehydrogenase. The following enzymes are absent: thiosulfate reductase, urease, lecithinase, arginine dihydrolase, phenylalanine deaminase, and catalase. For the 17 strains, the mean value of the G = C percent of the DNA is 39.8 +/- 1.2. All the strains are highly similar.

Anaerobiosis↗
PubMed1977

Deoxyribonucleic acid base composition of Simonsiellaceae.

The molar percentages of guanine plus cytosine in the DNA of 51 strains of Simonsiellaceae were determined by buoyant density ultracentrifugation of cell lysates in CsCl. The DNA base ratios ranged from 41-55 mole-% guanine plus cytosine. These values fall within the range known for the Order Cytophagales, the non-fruiting gliding bacteria, and are outside the range of the Order Myxobacterales, the fruiting myxobacteria. Among the strains of the genus Simonsiella, four distinct group can be delineated on the basis of source of origin (sheep, dog, cat, human) and GC content. The neotype of Alysiella filiformis has a GC content of 45.4 mole-%.

Animals↗