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Biomedical subjects

C Hurwitz

Publications and source records attributed to C Hurwitz.

48 records · Page 3Linked to original sources
PubMed1969

Time lapse cinemicrographic studies of x-irradiated HeLa S3 cells. I. Cell progression and cell disintegration.

Time-lapse cinemicrographs of synchronous HeLa S3 cells irradiated with 220 kv X-rays at various stages of interphase provided data for constructing pedigrees, measuring the duration of both generation cycles and mitoses, and scoring events associated with cell disintegration for up to seven postirradiation generations. The onset of the first mitosis after doses of 500 rads was delayed as expected from previous studies of the age dependence of "mitotic delay." The interval between this first mitosis and the next was indistinguishable from that for unirradiated control cells, while the subsequent two generations were again prolonged, on the average, though not so severely as was the irradiated generation. The duration of mitosis was increased proportionally more than interphase. Cell disintegration took place by way of two morphologically distinct processes. In three-quarters of the cases the cells were rounded and apparently trapped in metaphase when they disintegrated; the remaining disintegrations occurred in spread, interphase cells. In cells disintegrating from the rounded configuration, the generation preceding disintegration was prolonged relative to that in cells which divided; in cells disintegrating from either configuration, the penultimate generation was also prolonged. The mitotic times were disproportionately increased in both of these generations. It is suggested that in this system X-ray damage is preferentially expressed as derangement of the mitotic process; such damage ultimately brings about permanent mitotic arrest in the majority of cells.

HeLa Cells↗
PubMed1969

Time-lapse cinemicrographic studies of x-irradiated HeLa S3 cells. II. Cell fusion.

Analysis of time-lapse cinemicrographs of X-irradiated HeLa S3 cells has shown that the incidence of cell fusion was increased from 0.9% (following 1267 divisions) in control cells to an average of 22% (following 655 divisions) in cells irradiated with 500 rad doses of 220 kv X-rays. The incidence depended on the stage of the generation cycle at which the parent cells were irradiated. It was nearly constant in the first three postirradiation generations. Fusion occurred at all stages of the generation cycle, but preferentially during the first 20%. Cells undergoing fusion progressed more slowly through the generation cycle and had a higher probability of disintegrating than did irradiated cells that did not fuse. The occurrence of fusion was clonally distributed in the population. It took place only between sister (or closely related) cells. Protoplasmic bridges were often visible between sister cells prior to fusion. Giant cells arose only as a result of fusion. The incidence of multipolar divisions, though higher than in unirradiated cells, was only 5.5% in cultures irradiated with 500 rads. Fusion occurred following 85% of the multipolar divisions and was often followed by a multipolar division.

Cell Biology↗
PubMed1967

Measurement of binding of chloramphenicol by intact cells.

The binding of chloramphenicol to intracellular components of intact cells was measured by procedures based on a silicone-wash technique. The number of stereospecifically bound molecules of chloramphenicol increased with external concentration to a saturation value equal to the number of ribosomes per cell. Chloramphenicol is therefore believed to be attached stereospecifically by a weak bond, most probably to a single site on the 50S ribosome. This bond was found to be temperature-dependent and appeared to be responsible for inhibition of protein synthesis.

Bacterial Proteins↗
PubMed1965

Evidence for a streptomycin permease.

Hurwitz, Charles (Veterans Administration Hospital, Albany, N.Y.), and Carmen L. Rosano. Evidence for a streptomycin permease. J. Bacteriol. 90:1233-1237. 1965.-The hypothesis that an induced streptomycin permease is required for entry of the antibiotic into cells is further supported by the finding that proflavine and borate, which inhibit transcription, also block the lethal action of streptomycin. Furthermore, if ribonucleic acid (RNA) synthesis is permitted to proceed in the presence of streptomycin and chloramphenicol, and chloramphenicol is then replaced with either proflavine or borate, these inhibitors of transcription no longer block the lethal action of streptomycin. This finding is interpreted to mean that, if induced messenger RNA for streptomycin-permease is formed before transcription is blocked, inhibitors of transcription no longer block the lethal action of streptomycin by preventing formation of the permease.

Acridines↗
PubMed1965

Washing bacteria by centrifugation through a water-immiscible layer of silicones.

Hurwitz, Charles (Veterans Administration Hospital, Albany, N.Y.), Catherine B. Braun, and Richard A. Peabody. Washing bacteria by centrifugation through a water-immiscible layer of silicones. J. Bacteriol. 90:1692-1695. 1965.-A method is described which enables the separation of cells from aqueous suspension without altering the internal aqueous environment of the cells. The method consists of centrifuging the cells from the aqueous environment through a more dense, immiscible solvent consisting of a mixture of two silicones. A thin film of the aqueous environment equal to 7 x 10(-13) ml per cell remains with the bacteria during the separation procedure. The method by which this volume was determined is described. The procedure itself has no measurable effect on viability or permeability of the cells and permits recovery of about 90% of the cells from the aqueous environment. With this method, it has been found that the intracellular water volume of Escherichia coli ML 35 accessible to sucrose or inositol is 1.96 x 10(-12) ml +/- 6%, or 85% of the total volume of the cell determined by visual measurement.

Bacteriological Techniques↗
PubMedDate not supplied

The clinical significance of protein-bound hydroxyproline fractions in sera of patients with adult rheumatoid arthritis.

Clq levels in sera of adult patients with rheumatoid arthritis (RA) were found to be significantly higher than corresponding levels of normal subjects (p less than 10(-3)) The increase in Clq observed in RA was not seen in systemic lupus erythematosus, chronic polyarticular gouty arthritis, ankylosing spondylitis, Paget's disease of bone, or Hodgkin's disease. Clq levels were determined both chemically (calculated) from the protein-bound hydroxyproline content of the euglobulin fraction) and by radial immunodiffusion. Although the estimates of Clq by these 2 methods did not agree, the increase of Clq in RA was found by the use of either method.

Adult↗
PubMedDate not supplied

Cell cycle inhibition in human BE-13 T cell leukemia cells by haptoglobin-related (HPR) antisense cDNA.

We have recently cloned and sequenced a human haptoglobin-related cDNA. Hpr expression was found in various tumor cell lines. To determine whether the haptoglobin related protein (hpr) affects the growth of an established T-cell leukemia cell line, an Hpr antisense expression vector that specifically reduces hpr production was constructed. The vector was transfected into BE-13 cells, an established T-cell leukemia cell line in which Hpr is expressed. Three stable clones were isolated in which hpr protein expression was reduced. These established cell lines proliferated more slowly than vector transfected cells in proportion to Hpr antisense mRNA expression and the reduction in hpr protein production. Following a BrdU pulse, flow cytometric analysis was performed to estimate the fraction of cells in S phase. Hpr antisense transfected cells contained less cells in S phase compared to vector transfected cells. Also in soft agar, cells expressing the antisense cDNA insert, formed on average at least 7-fold fewer colonies than cells transfected with the vector alone. The data suggest that Hpr inhibitors might be of therapeutic value for T-cell leukemia.

Base Sequence↗