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Biomedical subjects

M J Stark

Publications and source records attributed to M J Stark.

89 records · Page 5Linked to original sources
PubMed1979

Requirement for ribosomal protein BM-L11 in stringent control of RNA synthesis in Bacillus megaterium.

A spontaneously occurring thiostrepton-resistant mutant of Bacillus megaterium has been shown to yield ribosomes lacking protein BM-L11, a protein immunologically related to Escherichia coli ribosomal protein L11. Here we have demonstrated that the mutant strain has acquired the relaxed phenotype and is unable to synthesise guanosine tetraphosphate and pentaphosphate in vivo. Ribosomes from the mutant strain are unable to support the synthesis of these two compounds in vitro, but this deficiency can be overcome by re-addition of purified protein BM-L11 to the ribosomes. Thus protein BM-L11 appears to be indispensable for the synthesis of guanosine tetraphosphate and pentaphosphate; the implications of this observation are discussed.

Anti-Bacterial Agents↗
PubMed1978

Hepatic malonyl-CoA levels of fed, fasted and diabetic rats as measured using a simple radioisotopic assay.

A simple radioisotopic assay for malonyl-CoA is described. The method is based on the malonyl-CoA-dependent incorporation of labeled acetyl-CoA into palmitic acid catalyzed by fatty acid synthetase in the presence of NADPH. Its main advantages over the more conventional spectrophotometric procedure is that it is extremely sensitive and allows the simultaneous determination of picomole quantities of malonyl-CoA in multiple tissue extracts. It should prove particularly suitable for studies on the regulation of lipid metabolism in isolated hepatocytes where the quantity of tissue available for analysis is frequently very small. Application of the method to the measurement of malonyl-CoA in livers from fed, fasted, and diabetic rats yielded values that were consistent with the recently postulated role of malonyl-CoA in the regulation of hepatic ketone body production.

Acyl Coenzyme A↗
PubMed1978

Turnover of rat liver malic enzyme during induction by protein deprivation.

The half-lives of hepatic malic enzyme and total liver soluble proteins were determined in protein-sufficient and protein-deficient rats after injection of tracer doses of radioactively labeled leucine. The results obtained in these experiments have demonstrated that the increased levels of malic enzyme obtained under conditions of severe protein restriction are due to elevated rates of synthesis of the enzyme protein, with no apparent change in the rate of its degradation.

Animals↗
PubMedDate not supplied

Cloning and analysis of the Kluyveromyces lactis TRP1 gene: a chromosomal locus flanked by genes encoding inorganic pyrophosphatase and histone H3.

The TRP1 gene of the yeast Kluyveromyces lactis has been cloned from a genomic library by complementation of the Saccharomyces cerevisiae trp1-289 mutation. The gene was located within the clone by transposon mutagenesis and the coding region identified by DNA sequencing. This has indicated that K. lactis TRP1 encodes a 210-amino acid polypeptide which shows 53% identity to the homologous S. cerevisiae protein. The K. lactis TRP1 gene has been disrupted by substituting the S. cerevisiae URA3 gene for a large part of the TRP1 coding sequence. Replacement of the chromosomal TRP1 locus with this construction has enabled the production of non-reverting trp1- strains of K. lactis, while a genetic analysis of the disrupted allele confirmed that the TRP1 gene had been cloned. DNA sequencing has also shown that the K. lactis TRP1 sequence is flanked by genes encoding inorganic pyrophosphatase and histone H3, which we have designated IPP and HHT1 respectively. Hybridization studies have shown that in common with S. cerevisiae, K. lactis has two copies of the histone H3 gene. Each H3 gene is closely linked to a gene encoding histone H4 and in both yeast species the IPP gene is tightly linked to one of the histone gene pairs.

Amino Acid Sequence↗
PubMedDate not supplied

Intracellular expression of Kluyveromyces lactis toxin gamma subunit mimics treatment with exogenous toxin and distinguishes two classes of toxin-resistant mutant.

The Kluyveromyces lactis toxin is a heterotrimeric protein which irreversibly arrests proliferation of sensitive Saccharomyces cerevisiae cells in the G1 phase of the cell cycle. By expressing the gamma subunit of the toxin in sensitive yeast cells from a conditional promoter, it was previously demonstrated that it alone is required for inhibition (Tokunaga et al. (1989). Nucleic Acids Res. 17, 3435-3446). Here we show that, like native exogenous toxin, intracellular gamma subunit expression promotes a striking arrest of sensitive cells in G1. However, unlike the G1 arrest caused by native toxin, that induced by the gamma subunit alone does not result in reduced cellular viability and is fully and rapidly reversible, suggesting that the G1 arrest and the irreversibility of action may reflect different aspects of the toxin's interaction with sensitive cells. We have selected a large number of S. cerevisiae mutants which are highly resistant to the toxin in order to study its mode of action in more detail. Complementation analysis demonstrated that all but one of the mutants were recessive and these defined four separate genes. Members of two complementation groups concurrently acquired resistance to intracellular gamma subunit expression, suggesting that they contain a modified toxin target site. The other two genes appear to be required for entry of the gamma subunit into the sensitive cells since these mutants, while refractory to exogenous toxin, were fully sensitive to intracellular gamma subunit expression.

Culture Media↗
PubMedDate not supplied

Treating cigarette smoking in drug-abusing clients.

Clients in substance abuse treatment are at high risk for smoking-related illness due to higher rates and heavier smoking than the general population. Three myths widely held by both treatment staff and substance abusers in treatment-people in treatment do not want to quit smoking, people in treatment will relapse to other drug use if they attempt to quit smoking, and people in treatment are unable to quit smoking-make it difficult to broach the matter of smoking cessation. A 16-week, cognitive-behavioral group program with nicotine patches was conducted at Oregon's largest, private, nonprofit substance abuse treatment agency. Of 490 clients, approximately 85% of whom smoke, 106 (25% of the smokers) were interested enough in quitting to attend an orientation. Approximately 40% of these were methadone maintenance clients. The others were distributed among two residential and two outpatient drug-free treatment services. Of 90 assigned, 68 began voluntary treatment, and 21 were assigned to delayed treatment. Of the 66 smokers who began, 74% succeeded in quitting smoking for at least 1 day, and 23% were abstinent for at least 4 continuous weeks. At the end of the 16-week treatment, 7 subjects (11%) were abstinent. No control subjects quit smoking on their own. The article discusses issues of institutionalizing smoking cessation services in drug treatment agencies.

Administration, Cutaneous↗
PubMedDate not supplied

Smoking cessation for clients in chemical dependence treatment. A demonstration project.

A demonstration project was conducted to examine the factors that facilitate implementation of nicotine dependence treatment in a chemical dependence (cd) program. The project included: (a) staff education; (b) staff training to conduct nicotine dependence treatment groups; (c) voluntary smoking cessation treatment for smoking staff; and (d) smoking cessation treatment for client volunteers in outpatient and residential cd programs. A 12-week, cognitive/behavioral group program with nicotine patches was conducted separately for staff and client volunteers. Forty-two of approximately 70 staff returned smoking questionnaires, 10 of whom reported current smoking. Four staff members began treatment, in addition to four staff from a second treatment agency. There were three of eight staff (37.5%) who reported ongoing abstinence at the end of the 12-week program. There were 83 cd clients (approximately 20% of smoking clients) who volunteered to participate in smoking cessation treatment. Forty clients began treatment, 3 (7.5%) of whom were abstinent from smoking at the conclusion of the 12-week program. Staff smoking, lack of clinic resources devoted to the project, and voluntary client participation, which was adjunctive to other treatment components, were impediments to implementation and success. Success was greatest in a clinical setting in which smoking cessation treatment was staff supported and integrated with cd treatment. We recommend that (a) smoking cd staff be offered nicotine dependence treatment, (b) nicotine dependence treatment become a standard, integrated component of cd treatment, and (c) initiation of smoking cessation be individualized according to clients' needs and circumstances.

Adult↗
PubMedDate not supplied

Treating cigarette smoking in methadone maintenance clients.

Substance abusers in treatment have cigarette-smoking rates about three times that found in the general adult population, yet there is a paucity of published studies examining smoking-cessation programs for these clients. Accordingly, a behaviorally based smoking-cessation program for methadone maintenance clients was developed, and the efficacy of a methadone dose increase as a pharmacological adjunct was tested in a double-blind placebo-controlled study. While no significant difference between experimental and control subjects in reported abstinence rates was found, subjects receiving a methadone increase reported significantly more nicotine craving and other withdrawal symptoms during the first week of abstinence than did controls. Measures of smoking rates indicated that experimental subjects smoked significantly more than controls throughout the 10-week study period. Although the initial smoking abstinence rate of 65% was encouraging, most subjects returned to smoking by the end of the study period. These findings indicate that the development of smoking-cessation programs for methadone clients merits further study and that such programs should stress relapse prevention techniques tailored to the specific needs of this population. Also, while the use of a methadone dose increase as a pharmacological adjunct has not been found to be efficacious, other pharmacological strategies involving the use of nicotine should not be ruled out.

Adult↗
PubMedDate not supplied

From 12 solo practices to a hospital-based LMSG (large multispecialty group) in 100 easy steps.

In this final article, authors John Benvenuto, M.D., M.B.A., M.P.H., Michael Stark, D.O., and Richard Radoccia, M.B.S., M.P.H., describe how the visions of hospitals and physicians have remained virtually the same for the past century. What has changed is the business of health care and this change has impacted two areas they describe in detail--income and control.

Group Practice↗