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Biomedical subjects

J Stein

Publications and source records attributed to J Stein.

At least 433 records · Page 24Linked to original sources
PubMed1982

Analysis of histone gene expression during the cell cycle in HeLa cells by using cloned human histone genes.

Although it is generally agreed that histone protein synthesis is restricted to the S phase of the cell cycle--and therefore parallels DNA replication--both transcriptional and posttranscriptional levels of control have been invoked. Using blot hybridization with several cloned genomic human histone sequences representing different histone gene clusters as probes, we have assessed the steady-state level of histone RNAs in the nucleus and cytoplasm of G1 and S phase HeLa S3 cells. The representation of histone mRNA sequences of G1 compared with S phase cells was less than 1% in the cytoplasm and approximately 1% in the nucleus. These data are consistent with transcriptional control, but we cannot completely dismiss the possibility that regulation of histone gene expression is, to some extent, mediated posttranscriptionally. If histone gene transcription does occur in G1, the RNAs must either be rapidly degraded or be transcribed to a limited extent compared with S phase. An unexpected result was obtained when a blot of cytoplasmic RNA from G1 and S phase cells was hybridized with lambda HHG 41 DNA (containing H3 and H4 human genomic histone sequences). Although hybridization with histone mRNAs was observed for RNAs from S phase but not from G1 cells, hybridization with a nonhistone RNA of approximately 330 nucleotides present predominantly in G1 was also observed.

Bacteriophage lambda↗
PubMed1982

Organization of human histone genes.

We describe the isolation and initial characterization of seven independent lambda Charon 4A recombinant phages which contain human histone genomic sequences (designated lambda HHG). Restriction maps of these clones and localization of the genes coding for histones H2A, H2B, H3, and H4 are presented. The presence of histone encoding regions in the lambda HHG clones was demonstrated by several independent criteria including hybridization with specific DNA probes, hybrid selection/in vitro translation, and hybridization of lambda HHG DNAs to reserve Southern blots containing cytoplasmic RNAs from G1-, S-, and arabinofuranosylcytosine (cytosine arabinoside)-treated S-phase cells. In addition, the lambda HHG DNAs were shown to protect in vivo labeled H4 mRNAs from S1 nuclease digestion. Based on the analysis of the lambda HHG clones, human histone genes appear to be clustered in the genome. However, gene clusters do not seem to be present in identical tandem repeats. The lambda HHG clones described in this report fall into at least three distinct types of arrangement. One of these arrangements contains two coding regions for each of the histones H3 and H4. The arrangement of histone genes in the human genome, therefore, appears to be different from that in the sea urchin and Drosophila genomes in which each of the five histone-encoding regions (H1, H2A, H2B, H3, and H4) is present only once in each tandemly repeated cluster. At least one clone, lambda HHG 41, contains, in addition to the histone genes, a region that hybridizes with a cytoplasmic RNA approximately 330 nucleotides in length. This RNA is not similar in size to known histone-encoding RNAs and is present in the cytoplasm of HeLa cells predominantly in the G1 phase of the cell cycle.

Bacteriophage lambda↗
PubMed1982

Studies of a human growth hormone preparation used for clinical treatment in Great Britain.

This report describes some of the properties of a clinical-grade preparation of human growth hormone (hGH) extracted from acetone-preserved autopsy human pituitary glands and used in Great Britain from 1967 to 1980. Gel filtration of this hGH on Sephadex G-100 yielded (on a weight basis) an average of 48% of a high molecular weight fraction, 10% of an intermediate fraction expected to contain dimeric forms of the hormone and 33% of a fraction considered to be the hGH monomer. The immunoassay potency of the monomer fraction was twice that of the clinical-grade preparation and the amino-acid composition of the monomer fraction agreed well with that obtained from published hGH sequence data. The results of polyacrylamide-gel electrophoresis (under reducing and dissociating conditions) and amino-acid analysis of the high molecular weight fraction suggest that it contains around 30% of aggregated hGH as well as other material not separated from hGH by the purification procedure.

Amino Acids↗
PubMed1981

Cross-linking of chromosomal non-histone proteins to DNA by UV radiation and some antitumor drugs.

Antibodies reacting specifically with HeLa cell chromatin can be elicited by immunization with dehistonized HeLa chromatin preparations. The nature of these chromatin-associated antigens was investigated by cross-linking with UV irradiation or by in vitro exposure of chromatin to 1-methyl-1-nitrosourea (MNU) or 1,3-bis-(2-chloroethyl)-1-nitrosourea (BCNU). With the exception of 1-methyl-1-nitrosourea the described treatment of chromatin (native or dehistonized) significantly increased its immunological reactivity. Dissociation of the chromosomal proteins from DNA by concentrated salt-urea solutions essentially abolished the immunological reactivity of the residual chromatin pellets. The immunological activity was found in the supernatant protein fraction after its reconstitution with purified human placenta DNA. UV irradiation or alkylation of chromatin cross-linked the active proteins to DNA and prevented their dissociation. It is concluded that the immunologically cell-specific antigens in HeLa chromatin exist as closely associated complexes of chromosomal protein(s) with DNA.

Antigen-Antibody Complex↗
PubMed1981

Mutagenesis of lambda phage: weigle mutagenesis is induced by coincident lesions in the double helical DNA of the host cell genome.

We have studied the increase in mutation in mutagenized lambda phage when the host cells are also irradiated with ultraviolet light, "Weigle mutagenesis." The increase in mutation is induced mainly on coincidences between a radiation-produced lesion in one strand of the host cell DNA and a second lesion in the complementary strand. This conclusion is based on experiments in which incorporation of the base analog bromouracil sensitized the host cells to ultraviolet light. For the same number of bromouracil incorporated per cell, uniform substitution gave a higher level of Weigle mutagenesis than did substitution in only one strand of the DNA double helix. The data also show some induction of Weigle mutagenesis by processes linear in ultraviolet fluence; possibility include: lesions involving both complementary strands such as crosslinks, lesions in one strand opposite pre-existing discontinuities in the complementary strand, and very small contributions to induction from lesions in one strand only of the DNA.

Bacteriophage lambda↗
PubMed1981

[Experience with special-type pacemaker leads (author's transl)].

The dislodgement rate of endocardially placed pacemaker leads can be decreased by the use of special-type electrodes. Since 1963 a total of 2100 pacemaker implantations was performed. Since 1970 we have been using special-type electrodes in 15 to 20% of our patients each year. The complication rate of all pacemaker leads implanted in the period 1974 to 1978 was 7.6%, the rate of the special type electrodes alone came up to 15%. The lead IE--65--I had the greatest deal of this - 11 out of 43 leads had to be removed. 152 electrodes type IVE--85--armed with metal hooks - were implanted, 18 of which had to be revised and 17 of 117 rigid leads type IE--60--KS--10 revealed failure which made revision necessary. In contrast, 54 screw-in leads type 6957, Medtronik and AE--60--YR, Biotronik caused only one perforation - a lethal one. Primary experiences with a porous tip lead (CPII--4116) are good enough to recommend the use of this electrode as a lead of first choice. We saw 2 dislodgements in 50 implantations. Failure to sense or to pace were never seen (time of observation 2 to 18 months).

Arrhythmias, Cardiac↗
PubMed1980

Does psychotherapy really work? The government tries to find out.

The federal government has paid little attention to the growing list of psychotherapies even though it covers some of the costs through its medicare and medicaid programs. Now, however, it is beginning to assess some 250 different types of therapy to determine which of them actually work.

Humans↗
PubMed1980

Limited funds, unlimited demands.

Should the government pay the enormous costs of heart transplants for all patients who might benfit from them? It's difficult for the government to turn anyone down, although heart transplants might divert funds from other good--and less expensive--causes.

Health Policy↗
PubMed1980

Deregulation fever spreads to HEW's rules on using human guinea pigs.

The federal deregulation effort has reached all the way to the use of human guinea pigs in medical and social science experiments. But in the views of many critics, the Health, Education and Welfare Department hasn't gone far enough with its current proposal to add flexibility to the operations of the boards that review experiments involving human subjects at institutions that receive HEW research money.

Human Experimentation↗