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L Savage

Publications and source records attributed to L Savage.

13 recordsLinked to original sources
PubMed2001

Gonadotropins decrease estrogen receptor-beta messenger ribonucleic acid stability in rat granulosa cells.

We have previously shown that the preovulatory LH surge down-regulates estrogen receptor-beta (ERbeta) messenger RNA (mRNA) levels selectively in the granulosa cells of preovulatory follicles. To gain insight into the underlying mechanisms, we examined whether the LH-induced loss of ERbeta mRNA expression in rat granulosa cells is attributable to the hormone-induced changes at the level of transcription and/or mRNA degradation. When the rate of ERbeta gene transcription was assessed in cultured granulosa cells, by nuclear run-off assays, we observed only a marginal effect of hCG on ERbeta gene transcription. In contrast, when ERbeta mRNA levels were estimated in granulosa cells that were cultured in the presence of 5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole (DRB), an RNA synthesis inhibitor, we observed a significant inhibitory effect of human CG (hCG) on ERbeta mRNA expression at a magnitude similar to that observed in the absence of DRB. Forskolin (FSK) and 2-O-tetradecanol-phorbol-13-acetate (TPA), pharmacological agents that mimic LH actions in granulosa cells, also showed similar effects. Thus, these results suggest that LH decreases ERbeta mRNA expression in the granulosa cells of preovulatory follicles, primarily by destabilizing the preexisting ERbeta mRNA. We next determined the decay rate of the ERbeta mRNA in granulosa cells that were cultured in the presence of DRB and additional hCG, FSK, or TPA for various time periods, by estimating ERbeta mRNA levels, using semiquantitative RT-PCR assays and subsequent linear regression analyses. The half-life of the ERbeta mRNA in the presence of vehicle was 17.87 +/- 1.2 h (n = 4). hCG dramatically decreased the half-life of the ERbeta mRNA (4.85 +/- 0.49 h, n = 4). Similarly, both FSK and TPA decreased the half-life of the ERbeta mRNA to 3.57 +/- 0.31 h and 4.02 +/- 0.13 h, respectively. We extended these findings by examining whether the LH-induced down-regulation of the ERbeta mRNA is cycloheximide-sensitive. When granulosa cells were cultured in the presence of cycloheximide, a protein synthesis inhibitor, the inhibitory effects of hCG, FSK, and TPA on ERbeta mRNA levels were abolished. Similar results were obtained in the presence or absence of DRB, indicating that the hormone-induced destabilization of the ERbeta mRNA is coupled with translation processes. Taken together, our results demonstrate that LH decreases ERbeta mRNA expression, predominantly at the posttranscriptional level, in a cycloheximide-sensitive manner.

Animals↗
PubMed1997

Targeting of the Arabidopsis homomeric acetyl-coenzyme A carboxylase to plastids of rapeseeds.

Acetyl-coenzyme A carboxylase (ACCase) occurs in at least two forms in rapeseed (Brassica napus): a homomeric (HO) and presumably cytosolic isozyme and a heteromeric, plastidial isozyme. We investigated whether the HO-ACCase of Arabidopsis can be targeted to plastids of B. napus seeds. A chloroplast transit peptide and the napin promoter were fused to the Arabidopsis ACC1 gene and transformed into B. napus, with the following results. (a) The small subunit transit peptide was sufficient to provide import of this very large protein into developing seed plastids. (b) HO-ACCase in isolated plastids was found to be biotinylated at a level comparable to extraplastidial HO-ACCase. (c) In vitro assays of HO-ACCase in isolated plastids from developing seeds indicate that it occurs as an enzymatically active form in the plastidial compartment. (d) ACCase activity in mature B. napus seeds is normally very low; however, plants expressing the SSU/ACC1 gene had 10- to 20-fold higher ACCase activity in mature seeds, suggesting that plastid localization prevents the turnover of HO-ACCase. (e) ACCase over-expression altered seed fatty acid composition, with the largest effect being an increase approximately 5% by the expression of HO-ACCase in plastids.

Acetyl-CoA Carboxylase↗
PubMed1997

Antisense expression and overexpression of biotin carboxylase in tobacco leaves.

The plastid acetyl-coenzyme A carboxylase (ACCase) catalyzes the first committed step of fatty acid synthesis and in most plants is present as a heteromeric complex of at least four different protein subunits: the biotin carboxylase (BC), the biotin carboxyl carrier protein, and the alpha and beta subunits of the carboxyltransferase. To gain insight into the subunit organization of this heteromeric enzyme complex and to further evaluate the role of ACCase in regulating fatty acid synthesis, BC expression was altered in transgenic plants. Tobacco (Nicotiana tabacum) was transformed with antisense-expression and overexpression tobacco BC constructs, which resulted in the generation of plants with BC levels ranging from 20 to 500% of wild-type levels. Tobacco plants containing elevated or moderate decreases in leaf BC were phenotypically indistinguishable from wild-type plants. However, plants with less than 25% of wild-type BC levels showed severely retarded growth when grown under low-light conditions and a 26% lower leaf fatty acid content than wild-type plants. A comparison of leaf BC and biotin carboxyl carrier protein levels in plants with elevated and decreased BC expression revealed that these two subunits of the plastid ACCase are not maintained in a strict stoichiometric ratio.

Acetyl-CoA Carboxylase↗
PubMed1995

Alteration of acyl-acyl carrier protein pools and acetyl-CoA carboxylase expression in Escherichia coli by a plant medium chain acyl-acyl carrier protein thioesterase.

Expression of a plant lauroyl-acyl carrier protein (ACP) thioesterase in an Escherichia coli strain deficient in beta oxidation results in the accumulation of free fatty acids in the culture. Overall fatty acid production by the cultures is increased severalfold, particularly in the late log and stationary stages of growth. In control E. coli cells, malonyl-ACP levels and rates of fatty acid synthesis are highest during rapid logarithmic growth and decline to undetectable levels in stationary stage. In contrast, in cells expressing plant acyl-ACP thioesterase, malonyl-ACP levels remain high in late log and stationary stage in association with the continued fatty acid production. In addition, the biotin carboxyl carrier protein component of acetyl-CoA carboxylase is expressed at higher levels in cultures expressing the acyl-ACP thioesterase. The data presented indicate that removal of the acyl-ACP products of fatty acid synthesis results in increased production of both malonyl-ACP and fatty acids, which may in turn result from higher activity and/or expression of acetyl-CoA carboxylase.

Acetyl-CoA Carboxylase↗
PubMed1989

Recruitment to the cytoplasm of a cellular lamin-like protein from the nucleus during a poxvirus infection.

Monoclonal antibodies (Mabs) directed against core proteins of rabbit poxvirus (RPV) have proven effective in the identification of host cell proteins such as RNA polymerase II (Pol II) that may play a role in the infectious process (D. K. Morrison and R. W. Moyer, 1986, Cell 44, 587-596). In this article we describe a Mab that has allowed the detection and characterization of a lamin-like protein derived from the nucleus of the infected cell, which like Pol II is recruited to the cytoplasm following RPV infection. A portion of the gene encoding this protein has been isolated through the screening of a lambda gt11 expression vector library. Sequence analysis of the gene shows it to be derived from a member of the HindIII 1.9-kb repetitive element, a family of mammalian repetitive sequences that are highly conserved. Immunoblot analysis and sequence analysis of the open reading frame show divergent relatedness to certain nuclear lamins. The protein is not, however, one of the three principal lamins characterized to date, but instead appears to be a perinuclear protein related to the highly conserved nuclear lamins that is recruited to the cytoplasm during the infectious process.

Amino Acid Sequence↗
PubMed1981

Purification and characterization of Escherichia coli formamidopyrimidine-DNA glycosylase that excises damaged 7-methylguanine from deoxyribonucleic acid.

A DNA glycosylase that excises 7-methylguanines with alkali-opened imidazole rings (formamidopyrimidines) from DNA has been purified more than 8000-fold from Escherichia coli cell extracts. The enzyme does not cleave 3-methyladenine, uracil, and intact 7-methylguanine from DNA. In assays containing pyrimidine analogues like oxauracil, 2,4,6-triaminopyrimidine, 2,5,6-triamino-2-hydroxypyrimidine sulfate, formamidopyrimidine, and 5-nitroso-2,4,6-triaminopyrimidine, only the two compounds showed end product inhibition of the enzyme. The enzyme has been named formamidopyrimidine-DNA glycosylase. It has a molecular weight of 30 000 and a Stokes radius of 26.4 A. The enzyme prefers double-stranded to single-stranded DNA and is stimulated by the presence of 0.1 M KCl in the reaction mixture.

DNA, Bacterial↗
PubMedDate not supplied

The incidence of gastrointestinal symptoms in cardiac surgery patients through six weeks after discharge.

OBJECTIVE: To determine the incidence and the effect of intraoperative and discharge variables on gastrointestinal (GI) symptoms after cardiac surgery during hospitalization and 2 and 6 weeks after discharge. DESIGN: Prospective and descriptive. SETTING: Two university-affiliated medical centers. PATIENTS: One hundred twenty-two adult patients undergoing cardiac surgery. OUTCOME MEASURES: Frequency of GI symptoms and level of distress caused by GI symptoms during hospitalization and 2 and 6 weeks after hospital discharge. INSTRUMENTS: GI symptoms were measured by The Gastrointestinal Symptom Frequency and Symptom Distress Scale. Depression was measured by The Center for Epidemiologic Studies Depression Scale. INTERVENTION: Demographic and physiologic variables were collected by chart review. Patients completed the Gastrointestinal Symptom Frequency and Symptom Distress Scale and The Center for Epidemiologic Studies Depression Scale in the hospital. Telephone interviews were used to collect 2- and 6-week data. RESULTS: Fifty-seven percent of patients after surgery reported poor appetite, 37% lack of taste, and 34% nausea during hospitalization. The frequency of all GI symptoms decreased with time; 19% of subjects reported poor appetite, 19% lack of taste, and 10% nausea at 6 weeks after discharge. Although poor appetite occurred with the greatest frequency, patients reported the greatest distress with lack of taste. When analyzed with a logistic regression model, use of antihypertensive agents was associated with lack of taste; use of diuretic and antiarrhythmic agents was associated with nausea; and level of depression was associated with all three GI symptoms. Length of cardiopulmonary bypass time mean arterial blood pressure during surgery, mixed venous oxygen saturation during surgery, and subject age did not significantly affect the frequency of GI symptoms at any data collection point. CONCLUSIONS: The incidence of GI symptoms after cardiac surgery is significant, but their etiology has yet to be determined.

Adult↗
PubMedDate not supplied

Seclusion in psychiatry.

The subject of seclusion will always generate professional, legal and moral debate. Lawrence Savage and Emad Salib examined the continuing and regular use of seclusion in a secure mental health unit, and suggest that the seclusion of some patients may continue to be a safe and effective intervention to control incidents of disturbed behaviour.

Adolescent↗