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Biomedical subjects

R S Greene

Publications and source records attributed to R S Greene.

At least 19 recordsLinked to original sources
PubMed1993

Mitotic CDC2 kinase is negatively regulated by cAMP-dependent protein kinase in mouse fibroblast cell free extracts.

CDC2 kinase activity was decreased by up to 75% when mitotic cell free extracts from mouse fibroblasts were incubated with cAMP and ATP. This effect was blocked by PKI, the heat stable inhibitor of cAMP-dependent protein kinase (PKA). An acidic, heat stable protein from G1 cells, consistent with inhibitor-1 of protein phosphatase 1, mimicked the effect of cAMP, but was not antagonized by PKI. Okadaic acid, another inhibitor of protein phosphatase 1, also downregulated CD2 activity, and the effect was independent of both cAMP and PKI. The evidence suggests that PKA exerts its effect by activating inhibitor-1 by phosphorylation, and that the next step in the regulatory pathway requires the inactivation of one or more protein phosphatase 1 isoenzymes. Non-denaturing gel electrophoresis suggested that the size and/or charge density of the CDC2 kinase complex was changed when the activity was downregulated by cAMP or G1 extracts.

Amino Acid Sequence↗
PubMed1990

Identification of mitotic (CDC2) and interphase histone H1 kinases by nondenaturing gel electrophoresis and peptide assays.

A new method of nondenaturing gel electrophoresis and a specific peptide based assay were used to study the histone kinases in mitotic and interphase mouse fibroblasts. The gels resolved four activities, one of which was shown to be the mitotic (CDC2) H1 kinase by virtue of its antigenicity. A new peptide substrate for the CDC2 kinase was phosphorylated by both S-phase and mitotic cell extracts and reacted with two protein kinases in the gels. Since the interphase enzyme did not react with the antibody, the results suggest that it is either a "masked" form of CDC2 or a second enzyme, functionally related to CDC2, which is responsible for the interphase phosphorylation of H1.

Animals↗
PubMed1990

Retinoid induced changes in cAMP-dependent protein kinase activity detected by a new minigel assay.

A new method for the resolution of protein kinases in nondenaturing minigels was used to analyze the type of PKA induced by retinyl acetate in transformed mouse 10T1/2 cells. Protein kinases in 0.5 microliters aliquots of cell extracts were resolved on nondenaturing gradient Phastgels and assayed for PKA activity in situ using a specific peptide substrate and [32P]ATP. Retinyl acetate caused a decrease in type I and an increase in type II PKA isoforms after about 36 h in culture. The system provides a quick and sensitive means for analyzing the activity of PKA isoforms from small numbers of cells.

Animals↗
PubMed1989

Segregation of relaxed replicated dimers when DNA ligase and DNA polymerase I are limited during oriC-specific DNA replication.

An in vitro Escherichia coli oriC-specific DNA replication system was used to investigate the DNA replication pathways of oriC plasmids. When this system was perturbed by the DNA ligase inhibitor nicotinamide mononucleotide (NMN), alterations occurred in the initiation of DNA synthesis and processing of intermediates and DNA products. Addition of high concentrations of NMN soon after initiation resulted in the accumulation of open circular dimers (OC-OC). These dimers were decatenated to open circular monomers (form II or OC), which were then processed to closed circular supercoiled monomers (form I or CC) products. After a delay, limited ligation of the interlinked dimers (OC-OC to CC-OC and CC-CC) also occurred. Similar results were obtained with replication protein extracts from polA mutants. The presence of NMN before any initiation events took place prolonged the existence of nicked template DNA and promoted, without a lag period, limited incorporation into form II molecules. This DNA synthesis was nonspecific with respect to oriC, as judged by DnaA protein dependence, and presumably occurred at nicks in the template DNA. These results are consistent with oriC-specific initiation requiring closed supercoiled molecules dependent on DNA ligase activity. The results also show that decatenation of dimers occurs readily on nicked dimer and represents an efficient pathway for processing replication intermediates in vitro.

Bacterial Proteins↗
PubMed1985

In vitro RNA polymerase interaction with a restriction fragment containing the Escherichia coli origin of replication.

The interaction of RNA polymerase with a restriction fragment containing the origin of Escherichia coli replication (oriC) was examined by methods used to investigate transcription promoter activities. Interactions of RNA polymerase with oriC were determined and characterized by agarose gel exclusion under conditions of polymerase binding and RNA synthesis initiation. These interactions were further demonstrated and defined by nitrocellulose retention experiments under various reaction conditions. The binding of RNA polymerase to the oriC fragment was compared to binding to the tetracycline promoter (tet), a known strong promoter of transcription. Specific localization of the RNA polymerase-oriC interaction was determined by restriction protection experiments. The binding of RNA polymerase was determined to be located near the HindIII site of oriC. These methods allowed the observation and characterization of a specific association of RNA polymerase with the origin of E. coli DNA replication.

DNA Replication↗
PubMed1984

Detection of proteins which recognize and bind oriC sequences.

Extracts from E. coli capable of supporting in vitro oriC-dependent DNA replication have been examined with a protein blotting protocol to identify DNA-binding proteins. Four polypeptide chains with apparent affinity for oriC DNA were detected.

Chromosomes, Bacterial↗
PubMed1984

The relation of cytomegalovirus and Epstein-Barr virus antibodies to T-cell subsets in homosexually active men.

Eighty-nine homosexual men participated in a study of sexual practices, T-cell subsets, and antibody titers to cytomegalovirus (CMV) and Epstein-Barr virus (EBV). The prevalence of antibody to CMV was 96% and to EBV, 94%. Titers to CMV were higher in those practicing receptive anal intercourse. The CMV antibody titers were positively correlated with the T-helper/suppressor ratio, number of partners and venereal disease episodes, number of T-suppressor cells, and EBV titers. Twelve percent of the participants had a low ratio only, 18% T-suppressor augmentation, and 3% T-helper deficiency. The CMV titer and prevalence of receptive anal intercourse were higher in those with a low ratio only, T-suppressor augmentation, and T-helper deficiency. These results suggest that CMV infection is acquired through receptive anal intercourse and is associated with an increase in T-suppressor cells and, in some persons, a decrease in T-helper cells.

Adult↗
PubMed1983

Relation between sexual practices and T-cell subsets in homosexually active men.

27% of 89 young, non-ill, homosexually active men in Los Angeles had a Leu-3(OKT4)/Leu-2(OKT8) ratio less than or equal to 0 . 8. The low ratio was due to a significantly raised mean number of Leu-2 cells, whereas individuals with acquired immune deficiency syndrome had a decrease in both Leu-3 and Leu-2 cells. The term "acquired immune augmentation" may be appropriate for those with a low ratio due to raised numbers of Leu-2 cells. Those practising passive (receptive) anal intercourse had a significantly higher mean number of Leu-2 cells than did those practising only active (insertive) anal intercourse or no anal intercourse. The results of this study suggest that two distinct conditions occur in homosexually active men. Whether acquired immune augmentation is a precursor of the rarer acquired immune deficiency syndrome or is an unrelated disorder needs to be determined. In this study passive anal intercourse was associated with acquired immune augmentation.

Acquired Immunodeficiency Syndrome↗
PubMed1983

In vitro effects of acridine intercalation on RNA polymerase interactions with supercoiled DNA.

In vitro transcription of supercoiled DNA by purified E. coli RNA polymerase was inhibited by Acridine Orange in a bimodal manner while N-10 benzyl substituted Acridine Orange is about one-third as inhibitory and effects monophasic inhibition. The inhibition correlates with the supercoil unwinding abilities of these two intercalators with Acridine Orange unwinding supercoiled DNA at 1/3 the concentration required for the substituted acridine orange. Direct visualization of DNA-RNA polymerase complex on agarose gels showed that these intercalators directly interfere with this association and the more effective the drug is in unwinding DNA supercoils the more effective it is in interfering with the DNA-enzyme complex. In addition, specific intercalators differentially affect the stability of DNA-RNA polymerase-RNA ternary complexes.

Acridine Orange↗
PubMed1983

Review of colostomy in a community hospital.

This review of 193 colostomies was carried out to assess the procedure in our institution from standpoints of indications, technique, complications, and results. The study revealed colostomy was most commonly performed for obstruction, abdominoperineal resection, and infection or fistula associated with carcinoma, diverticulitis, and trauma in that order of frequency. The mortality rate was 2.6 per cent. Complications were observed in 22 per cent with 11 per cent being directly related to the colostomies themselves. Colostomy closure was accompanied by a 17 per cent complication rate and 1.5 per cent mortality. These overall results compare well with those of other investigators. Higher complication rates were found for colostomy for diverticulitis vs carcinoma; abscess or fistula vs obstruction or abdominoperineal resection; and for colostomy in the operative incision vs separate incision. The lowest rate was for colostomy for trauma. No significant difference in complication rate between transverse and sigmoid colostomies and colostomy closure by resection and anastomosis vs simple closure were noted.

Adolescent↗
PubMed1978

Study of structural analysis: comparing differential diagnoses based on psychiatric evaluation, the MMPI, and structural analysis of the Hand Test and Rorschach.

Experimental investigation of Structural Analysis compared diagnoses of 30 psychiatric inpatients derived independently from psychiatric evaluations, MMPI analyses, and Structural Analysis interpretation of Hand Test and Rorschach data. Results yielded positive preliminary implications for the use of Structural Analysis in psychodiagnostics.

Adolescent↗
PubMed1977

Contemporary dilemmas in personality assessment illustrated in a diagnostic case study.

Hand Test and California Psychological Inventory data produced by two nonviolent sex offenders are presented in case study format. Marked similarities in personality of these subjects are noted and discussed in relation to difficulties which plague the field of measurement and evaluation. Social relevancy is noted and the need for systematic study of large samples is emphasized.

Adult↗