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Biomedical subjects

D Sompolinsky

Publications and source records attributed to D Sompolinsky.

At least 73 records · Page 4Linked to original sources
PubMed1975

Infections with mycoplasma and bacteria in induced midtrimester abortion and fetal loss.

Placentas and fetuses from cases of induced midtrimester abortion and fetal loss (13 weeks of pregnancy or more) were examined microbiologically. In the series of midtrimester fetal loss, bacteria were isolated in 14 per cent and genital Mycoplasma in 37 per cent of the placentas. In induced abortion, 18 per cent of the placentas grew bacteria and in only one case out of 27 was a Mycoplasma strain isolated. Fetal organs yielded cultures positive for bacteria in 16 per cent and for genital Mycoplasma in 23 per cent of the spontaneous fetal loss material, whereas pyogenic cocci were isolated from fetal organs in 18 per cent and Mycoplasma in no case of induced abortion. In the positive cases, the fetal lungs were most often infected (in 34 out of 37 positive cases of spontaneous and 4 out of 5 positive cases of induced abortion). On the other hand, microorganisms could be isolated from the brain in only 5 out of 28 cases of spontaneous and none of induced abortion. In the series of fetal loss, positive microbiologic findings from the fetal organs seemed correlated to prolonged bleeding before abortion or labor and to premature rupture of membranes.

Abortion, Induced↗
PubMed1974

Growth of Chlamydia trachomatis in McCoy cells treated with cytochalasin B.

When the fungal metabolite cytochalasin B was added to McCoy cells, multinucleated giant cells developed. Monolayers of these cells proved as efficient as irradiated cells for the growth of three different serotypes of Chlamydia trachomatis and for the primary isolation of chlamydiae from clinical specimens obtained from patients attending a venereal disease clinic. Cytochalasin treatment of McCoy cells provides a convenient alternative to irradiation and should be of value in the isolation of chlamydiae from the eye and genital tract.

Cell Nucleus↗
PubMed1974

Epidemiological and biochemical studies on thiamine-less dwarf-colony variants of Staphylococcus aureus as etiological agents of bovine mastitis.

Dwarf-colony (D) variants of Staphylococcus aureus are relatively widespread etiological agents of bovine mastitis in Israel. D strains grow on ordinary solid nutrient media with pinpoint, transparent colonies. An epidemiological study indicated that these variants are more communicable than normal (N) S. aureus strains. Biochemically, several types of metabolic defects have been demonstrated among the D strains: strains from one herd were pantothenate-less, most of the other isolates were thiamine-less, and a few of them were both thiamine-and pantothenate-less. Among the thiamineauxotrophs were a few (from one herd) which were unable to concentrate thiamine-thiazole, whereas all of the other strains required thiamine-pyrimidine (HMP) in the form of pyrophosphate (HMP-PP). At least some of these D strains were defective in three functions: concentrative uptake of HMP, phosphorylation of HMP, and phosphorylation of HMP-monophosphate. Since mutants with normal growth occurred readily, we assumed that the information for these three functions exists on a polycistronic operon. Quantitative requirements for HMP-PP varied highly among the D strains, and other data also indicated that HMP-PP-requiring strains had not developed from a common source.

Animals↗
PubMed1973

Action of 12 tetracyclines on susceptible and resistant strains of Staphylococcus aureus.

The relative growth inhibition caused by 12 tetracyclines in a susceptible strain of Staphylococcus aureus (111-elim) and in the same strain carrying a resistance-plasmid (111) showed entirely different patterns. For four of the tetracyclines (minocycline, anhydrotetracycline, chelocardin, and desdimethylaminotetracycline), the strain with the tetracycline plasmid (111) had virtually the same tolerance as the susceptible strain (111-elim). A resistant mutant of strain 111-elim showed a third pattern of relative growth inhibition, and another distinct pattern was observed in a veterinary wild strain of S. aureus. Of the 12 tetracyclines, 11 were effective inducers of higher tetracycline resistance in S. aureus 111, but no correlation was found between the efficacy of the tetracyclines as inducers and as inhibitors of growth of 111-elim or 111. At external drug concentrations causing doubling of the generation time (K(i)), 111-elim accumulated tetracycline, oxytetracycline, and minocycline to a degree corresponding to several thousand molecules per coccus. At a fixed external drug concentration, 111 accumulated less tetracycline and oxytetracycline than 111-elim, whereas comparison at their respective K(i) values showed accumulation to be significantly higher for 111 than for 111-elim. The accumulation of tetracyclines is assumed to involve both surface sorption and active membrane transport. Resistance is probably due to decreased accumulation of the drugs, and a hypothesis explaining the mechanism of resistance is offered.

Cells, Cultured↗
PubMed1972

Influence of magnesium and manganese on some biological and physical properties of tetracycline.

Accumulation of (3)H-tetracycline in nonproliferating cells of susceptible and resistant strains of Escherichia coli and Staphylococcus aureus in tris(hydroxymethyl)aminomethane (Tris) buffer (10 mm, pH 7.5) was significantly decreased in the presence of 5 to 40 mm MgCl(2) and increased in the presence of 5 to 10 mm MnCl(2). When the bacteria first accumulated (3)H-tetracycline in plain Tris.HCl, and the metal salts were thereafter added, a prompt decrease or increase in radioactivity of the cells was observed after the addition of Mg(2+) or Mn(2+), respectively. In phosphate buffer (10 mm, pH 7.5), the effect of Mg(2+) was delayed. Three minutes after addition of (3)H-tetracycline, uptake was as in the control cell suspension, but thereafter it dropped rapidly. When (3)H-tetracycline was incubated with Mg(2+) before addition to the bacterial suspension, uptake was scarcely measurable. The addition of Mg(2+) to growing cultures of S. aureus and E. coli caused a marked decrease in susceptibility; in contrast, no increase in susceptibility could be demonstrated when Mn(2+) was added. It was also demonstrated that Mg(2+) and Mn(2+) had distinct influences on the absorption spectrum, the optical rotatory dispersion, the circular dichroism, and the lipid solubility of tetracycline.

Absorption↗