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Biomedical subjects

U Bachrach

Publications and source records attributed to U Bachrach.

At least 91 records · Page 5Linked to original sources
PubMed1976

Studies on phage internal proteins: formation of internal protein - T2 DNA complexes in vivo.

Internal proteins, synthesized in T2-infected Escherichia coli B cells were recovered from bacterial membranes during the early stages of infection. Approx. 15 min after the onset of infection, T2 and T4 internal proteins were released from the bacterial membranes and sedimented along with newly synthesized phage DNA. Internal protein-DNA complexes were also obtained by chromatography on hydroxylapatite columns. Internal proteins were not released from bacterial membranes after infection with amber mutants defective in genes 21, 22 and 23. It has been suggested that these complexes are intermediates in T-even phage morphogenesis.

Cell Membrane↗
PubMed1976

Cleavage of T4-induced proteins during phage morphogenesis: characterization of peptides.

Polypeptides of low mol. wt. have been extracted from T4 coliphages and from Escherichia coli B cells infected with a wild type and various amber mutants of bacteriophage T4. Six peptides were fractionated by chromatography on phosphocellulose: three of them were cleaved from proteins synthesized late in infection and related to phage head. The remaining three peptides have been shown to arise from early-labelled phage-induced proteins. Two of these six small petide fragments were found in the head of the T4 phage.

Amino Acids↗
PubMed1975

Cyclic AMP-mediated induction of ornithine decarboxylase of glioma and neuroblastoma cells.

The activity of ornithine decarboxylase (EC 4.1.1.17; L-ornithine carboxy-lyase) of C6-BU-1 glioma and N115 neuroblastoma cells increases significantly when confluent cultures are treated with compounds that increase cellular cAMP levels. These include norepinephrine or isoproterenol, and prostaglandin E1 or adenosine, which stimulate ornithine decarboxylase activity in C6-BU-1 glioma and N115 neuroblastoma cells, respectively. Ornithine decarboxylase activity is also elevated in confluent C6-BU-1 glioma cells treated with dibutyrylcAMP and theophylline, or after the glioma cells are fed with a serum-depleted medium in the presence of catecholamines and inhibitors of cyclic nucleotide phosphodiesterase. The activity of the enzyme increases 500- to 1000-fold, 2-6 hr after stationary-phase N115 neuroblastoma cells are fed with a serum-free medium, supplemented with phosphodiesterase inhibitors, adenosine, or prostaglandin E1. This stimulation is antagonized by carbamoyl choline and is blocked by actinomycin D or cycloheximide. These results suggest that the synthesis of ornithine decarboxylase of C6-BU-1 glioma and N115 neuroblastoma cells is controlled by cAMP.

4-(3-Butoxy-4-methoxybenzyl)-2-imidazolidinone↗
PubMed1975

Occurrence of polyamines in coliphages T5, phiX174 and in phage-infected bacteria.

The polyamine spermidine and the diamine putrescine have been detected in coliphages T5 and phiX174. Polyamines were identified by thin-layer chromatography and mass-spectrometry of dansyl derivatives, as well as by ion-exchange chromatography. In phiX174 phages, polyamines were sufficient to neutralize 0.5% of DNA phosphates. The polyamine content of T5 phages depended on growth media and purification procedures, but at least 1% of DNA phosphates were neutralized by polyamines. After infection, an increase in cellular polyamine was noticed. This increase paralleled variations in ornithine decarboxylase activity.

Carboxy-Lyases↗
PubMed1975

Specific increase in polyamine levels in chick embryo cells transformed by Rous sarcoma virus.

Chick embryo fibroblasts and chorioallantoic membranes of chick embryos infected with oncogenic or nononcogenic viruses were analyzed for polyamines. Nononcogenic viruses (influenze, Newcastle disease, or vaccinia virus) had no effect on the polyamine content of chorioallantoic membranes. Transformation of chorioallantoic membranes by a wild-type or temperature-sensitive mutant strain of Rous sarcoma virus under permissive conditions (37 degrees) caused a 2- to 4-fold increase in cellular spermidine and putrescine content. Only putrescine accumulated in chick embryo fibroblasts transformed by Rous sarcoma virus at 37 degrees. At the nonpermissive temperature (42 degrees), the temperature-sensitive mutant, unlike the wild-type strain, did not alter cellular morphology or polyamine content.

Allantois↗
PubMed1975

Polyamine metabolism in normal and in virus-transformed chick embryo fibroblasts.

The effect of transformation by Rous sarcoma virus on the ornithine decarboxylase levels of chick embryo fibroblasts was studied. Infection with Rous sarcoma virus resulted in increased ornithine decarboxylase activity which preceded morphological alterations by at least 24 hr. The ornithine decarboxylase levels of normal controls, unlike those in Rous sarcoma virus-infected cells, declined with age, so that the enzyme activity of transformed cells was increased twentyfold 5 days postinfection. Infection with a temperature-sensitive mutant of Rous sarcoma virus, T5, stimulated ornithine decarboxylase activity of chick embryo fibroblasts at the permissive (37 degrees) but not at the nonpermissive (42 degrees) temperature. The ornithine decarboxylase activity of T5-infected cells shifted from 42 degrees to 37 degrees increased within 2 hr and reached the levels of wild-type, Schmidt-Ruppin-17A-transformed cells in 11 hr. When T5-transformed fibroblasts were shifted to the nonpermissive temperature, ornithine decarboxylase activity decreased fivefold within 4 hr and paralleled the levels of normal controls in 11 hr. Shifting of temperatures of incubation caused comparable alterations in cellular putrescine but not in spermine or spermidine content.

Avian Sarcoma Viruses↗
PubMed1974

Radiometric method for the detection of coliform organisms in water.

A new radiometric method for the detection of coliform bacteria in water has been described. The method is based on the release of (14)CO(2) from [(14)C]lactose by bacteria suspended in growth medium and incubated at 37 C. The evolved (14)CO(2) is trapped by hyamine hydroxide and counted in a liquid scintillation spectrometer. The method permits the detection of 1 to 10 organisms within 6 h of incubation. Coliform bacteria suspended in water for several days recover from starvation and may be quantitated by the proposed method. Bacteria from water samples may also be concentrated by filtration through membrane filters and detected by the radiometric assay.

Bacteriological Techniques↗
PubMed1972

Effect of oxidized spermine and other aldehydes on the infectivity of vaccinia virus.

The antiviral activity of oxidized spermine was compared with that of other aldehydes. Suspensions of vaccinia virus were incubated at 37 C with various concentrations of the aldehydes, and the infectivity of the viruses was determined by the plaque assay. Oxidized spermine at a concentration of 0.82 mM completely inactivated a suspension of vaccinia virus (1.4 x 10(8) plaque-forming units) after incubation at 37 C for 10 hr. Glutaraldehyde and formaldehyde were less active when compared on a molar basis, but acrolein resembled oxidized spermine in its antiviral activity. Because acrolein is produced from oxidized spermine at only 20 to 30% yield, it is unlikely that the biological activity of the latter is due to acrolein formed during the spontaneous degradation of oxidized spermine.

Aldehydes↗