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Biomedical subjects

P A Edwards

Publications and source records attributed to P A Edwards.

At least 55 records · Page 3Linked to original sources
PubMed1997

Identification of glycerol-3-phosphate acyltransferase as an adipocyte determination and differentiation factor 1- and sterol regulatory element-binding protein-responsive gene.

We demonstrate that the mRNA levels of glycerol-3-phosphate acyltransferase (GPAT), a mitochondrial enzyme catalyzing the initial step in glycerolipid synthesis, are induced during the differentiation of 3T3-L1 preadipocytes to adipocytes and following ectopic expression of rat adipocyte determination and differentiation factor 1 (ADD1), a protein with high homology to the human sterol regulatory element-binding protein-1 (SREBP-1). The increase in GPAT mRNA levels that occurs during differentiation is partially prevented by ectopic expression of a dominant negative form of ADD1. Nucleotide sequences corresponding to the proximal promoter of the murine mitochondrial GPAT gene (Jerkins, A. A., Liu, W. R., Lee, S., and Sul, H. S. (1995) J. Biol. Chem. 270, 1416-1421) bound SREBP-1a and NF-Y in electromobility shift assays. In addition, GPAT promoter-luciferase reporter genes were stimulated by co-expression of SREBP-1a. This increase was attenuated when either a dominant negative form of NF-Y was co-transfected into the cells or when the GPAT promoter contained mutations in the putative binding sites for SREBP-1a or NF-Y. These studies demonstrate that the regulated expression of the mitochondrial GPAT gene requires both NF-Y and ADD1/SREBPs. Thus, SREBPs/ADD1 regulate not only genes involved in cholesterol homeostasis and fatty acid synthesis but also a key enzyme in glycerolipid synthesis.

Adipocytes↗
PubMed1997

Cytogenetic analysis of three breast carcinoma cell lines using reverse chromosome painting.

Chromosome painting was used to determine the copy number and identity of virtually all the chromosomes in three breast cancer cell lines, T-47D, MDA-MB-361, and ZR-75-1. The karyotypes of all three cell lines were very complex, and were consistent with the monosomic pattern of evolution suggested by Dutrillaux, in which nonreciprocal translocations cause an initial reduction in chromosome number, followed by duplication of the entire genome and further chromosome loss. Twenty distinct abnormal chromosomes were identified in T-47D, seven of which were present as two copies. MDA-MB-361 had 27 abnormal chromosomes each as a single copy. Thirteen abnormal chromosomes in ZR-75-1 occurred singly, two were paired, and one was present as three copies. Most of the aberrant chromosomes were nonreciprocal translocations, although deletions, duplications, isochromosomes, and amplifications (HSR of 1q) were also found. Chromosome arms present in abnormal chromosomes in all three lines were 1q, 6p, 7p, 8p, 8q, 10q, 11p, 11q, 12p, 13q, 14q, 15q, 16p, 16q, 17q, and 20q. The only chromosome arms present in four or more copies in all three lines were 8q and proximal 12p, while 1p, 17p, and bands 11q12--13 were the only chromosome regions consistently reduced to two copies. The most striking feature common to all three lines was a translocation breakpoint on the short arm of chromosome 8 at 8p12.

Breast Neoplasms↗
PubMed1996

Fuel identification by neural network analysis of the response of vapor-sensitive sensor arrays.

Neural network analysis of the response of an array of vapor-sensitive detectors has been used to identify six different types of aviation fuel. The data set included 96 samples of JP-4, JP-5, JP-7, JP-8, JetA, and aviation gasoline (AvGas). A sample of each neat fuel was injected into a continuous stream of breathing air through an injection port from a gas chromatograph. The aspirated sample was then swept from the injection port to the chamber without separation. In the chamber, the sample was exposed to an array of eight vapor-sensitive detectors. The analog output of each detector was digitized and stored while the sample was swept into and through the chamber. The response of each detector was then averaged and stored as the final response or pattern of each sample. It was clear from a visual inspection of each of the radar plots that there was a characteristic pattern in the response of the array to five of the six different fuel types. This was confirmed using neural network analysis to study the entire data set. A two-step procedure was developed to separate the patterns of all six fuel tyes into their respective classes. In the first step, fuels were separated into one of five groups: JP-4, JP-5, JP-7, AvGas, or a combined JP-8/JetA group. In the second step, the fuels in the combined group were separated into either JP-8 or JetA groups.

Chromatography, Gas↗
PubMed1996

Synergistic binding of sterol regulatory element-binding protein and NF-Y to the farnesyl diphosphate synthase promoter is critical for sterol-regulated expression of the gene.

Sterol-regulated transcription of the farnesyl diphosphate (FPP) synthase gene is dependent on two cis elements in the proximal promoter. These elements, an inverted CCAAT box and sterol regulatory element 3 (SRE-3), bind NF-Y and sterol regulatory element-binding protein 1 (SREBP-1), respectively. We now demonstrate that the binding of recombinant SREBP-1 to its cognate site (SRE-3) within the FPP synthase promoter in vitro is enhanced by binding of NF-Y to the upstream inverted CCAAT box. Using an FPP synthase promoter fragment containing the binding sites for both NF-Y and SREBP-1 in gel mobility shift assays, we demonstrate that the addition of NF-Y increases the binding of SREBP-1 to SRE-3 over 20-fold. In contrast, NF-Y does not stimulate the binding of SREBP-1 to SRE-3 when the inverted CCAAT box is either mutated or 4 base pairs (bp) are inserted between the inverted CCAAT box and SRE-3. Promoter-reporter genes, containing either the wild-type FPP synthase promoter sequence or containing the 4-bp insertion between the inverted CCAAT box and SRE-3, were transiently transfected into cells. The activity of the wild-type promoter-reporter gene increased when the cells were either incubated in sterol-depleted medium or were co-transfected with an expression vector encoding transcriptionally active SREBP-1. This increase in activity was attenuated when the promoter contained the 4-bp insert, consistent with defective binding of SREBP to the promoter in vivo. These studies suggest that the binding of SREBP-1 to SRE-3 in the FPP synthase promoter, and subsequent stimulation of transcription, is dependent on synergistic binding and a functional interaction between SREBP-1 and NF-Y.

Alkyl and Aryl Transferases↗
PubMed1996

Sterol regulatory element binding protein binds to a cis element in the promoter of the farnesyl diphosphate synthase gene.

Sterol-regulated transcription of the gene for rat farnesyl diphosphate (FPP) synthase (geranyl-diphosphate:isopentenyl-diphosphate geranyltranstransferase, EC 2.5.1.10) is dependent in part on the binding of the ubiquitous transcription factor NF-Y to a 6-bp element within the proximal promoter. Current studies identify a second element in this promoter that is also required for sterol-regulated transcription in vivo. Mutation of three nucleotides (CAC) within this element blocks the 8-fold induction of FPP synthase promoter-reporter genes that normally occurs when the transfected cells are incubated in medium deprived of sterols. Gel mobility-shift assays demonstrate that the transcriptionally active 68-kDa fragment of the sterol regulatory element (SRE-1)-binding protein assays (SREBP-1) binds to an oligonucleotide containing the wild-type sequence but not to an oligonucleotide in which the CAC has been mutated. DNase 1 protection pattern (footprint) analysis indicates that SREBP-1 binds to nucleotides that include the CAC. Both the in vivo and in vitro assays are affected by mutagenesis of nucleotides adjacent to the CAC. Coexpression of SREBP with a wild-type FPP synthase promoter-reporter gene in CV-1 cells results in very high levels of reporter activity that is sterol-independent. In contrast, the reporter activity remained low when the promoter contained a mutation in the CAC trinucleotide. We conclude that sterol-regulated transcription of FPP synthase is controlled in part by the interaction of SREBP with a binding site that we have termed SRE-3. Identification of this element may prove useful in the identification of other genes that are both regulated by SREBP and involved in lipid biosynthesis.

Alkyl and Aryl Transferases↗
PubMed1996

Genetic manipulation of mammary epithelium by transplantation.

Genes can be introduced into mammary epithelium in vivo by the 'tissue reconstitution' method. Primary cultures of mammary epithelial cells are prepared, a gene introduced using retrovirus vectors, and the cells transplanted into a mammary fat pad from which the normal epithelium has been removed. The cells reform an epithelium in which some cells express the introduced gene. The technique is reviewed and compared with the mammary-specific expression of genes in transgenic mice. To model the development of neoplasia, particularly the preneoplastic changes caused by a single oncogene alone, several oncogenes have been expressed this way--myc, Ha-ras, erbB, erbB2, Wnt-1, and hst/FGF-4. Each caused a different alteration to the growth pattern of the epithelium, such as altered branching, premature alveolus development, distorted duct structure, or altered hormone sensitivity. Insights into normal development have also been obtained by inappropriate expression of genes such as Wnt-4.

Animals↗
PubMed1996

Are nurse managers ready for the current challenges of healthcare?

In a study at four teaching hospitals, nurse managers rated themselves most competent in activities related to the management of their unit, and believed these activities were most important. Nurse managers lacked some of the skills and knowledge needed to relate to the larger organization and external environment, activities that they rated as less important. Selection, education, and development efforts should be targeted to newly important roles and skills for which nurse managers have little preparation.

Adult↗
PubMed1996

The Yin and Yang of oxidation in the development of the fatty streak. A review based on the 1994 George Lyman Duff Memorial Lecture.

Recent data support the hypothesis that the fatty streak develops in response to specific phospholipids contained in LDL that become trapped in the artery wall and become oxidized as a result of exposure to the oxidative waste of the artery wall cells. The antioxidants present within both LDL and the microenvironments in which LDL is trapped function to prevent the formation of these biologically active, oxidized lipids. Enzymes associated with LDL and HDL (eg, platelet activating factor acetylhydrolase) or with HDL alone (eg, paraoxonase) destroy these biologically active lipids. The regulation and expression of these enzymes are determined genetically and are also significantly modified by environmental influences, including the acute-phase response or an atherogenic diet. The balance of these multiple factors leads to an induction or suppression of the inflammatory response in the artery wall and determines the clinical course.

Animals↗
PubMed1996

Necrotizing sialometaplasia: literature review and case reports.

The authors describe necrotizing sialometaplasia, a benign inflammatory lesion primarily involving the minor salivary glands of the hard palate. The lesion presents itself as a deep-seated palatal ulcer with clinical and histologic features mimicking those of a malignant neoplasm. The lesion is believed to be the result of vascular ischemia initiated by trauma. An incisional biopsy is required to confirm the diagnosis, and the lesion heals by secondary intention within four to 10 weeks.

Adult↗
PubMed1996

Role for sterol regulatory element binding protein in the regulation of farnesyl diphosphate synthase and in the control of cellular levels of cholesterol and triglyceride: evidence from sterol regulation-defective cells.

In order to define the factors involved in the regulation of farnesyl diphosphate (FPP) synthase, we used sterol regulation-defective (SRD) cell lines that constitutively express either high (SRD-2) or low (SRD-6) levels of transcriptionally active sterol regulatory element binding protein (SREBP). FPP synthase mRNA levels were high in SRD-2 cells and low in SRD-6 cells and were unaffected by the addition or removal of sterols from the media. In contrast, the mRNA levels in parental CHO-7 cells were regulated by sterols. SRD-2, SRD-6, and CHO-7 cells were also transiently transfected with plasmids containing FPP synthase promoter-reporter genes. Reporter gene activity was significantly higher in SRD-2 cells than in either SRD-6 or CHO-7 cells, consistent with a higher rate of transcription of the reporter gene in SRD-2 cells. The high expression of the reporter gene in SRD-2 cells was not observed when the FPP synthase promoter contained a three base pair mutation within an SREBP binding site, termed sterol regulatory element-3 (SRE-3). These observations are consistent with the hypothesis that high levels of transcription of the FPP synthase gene are dependent on the availability of transcriptionally active SREBP. We also demonstrate that the incorporation of radioactive acetate into both cholesterol and fatty acids was enhanced in SRD-2 cells as compared to CHO-7 or SRD-6 cells. Finally, we demonstrate that the concentrations of cholesterol, cholesteryl ester, and triglyceride were all significantly elevated in SRD-2 cells. We conclude that SREBP is involved not only in the regulation of FPP synthase and cholesterogenesis but also in fatty acid and triglyceride synthesis.

Acetates↗
PubMed1996

Health promotion through fitness for adolescents and young adults following spinal cord injury.

A study by Warms (1987) sought to determine both the health care actually received by individuals following a spinal cord injury and the services they desired but did not obtain. The findings suggest that the general health promotion needs of these individuals are the same as for the general population and, though disability related topics are discussed with health care providers, information on health promotion is not received. The leading two services desired by the respondents but not obtained were planning an exercise program (43%) and referral to a fitness center (26%). A plan for health promotion through fitness was designed for individuals with physical disabilities to assist in meeting the identified needs. The program provides several benefits which include: improved function, a positive impact on lifestyle, and a decrease in the risk of complications. The plan includes a general health appraisal and fitness assessment as well as an exercise and fitness prescription with adapted physical activity and sports participation as integral parts. Evaluation methodology is incorporated to demonstrate that health promotion activities positively effect function and lifestyle and decrease severity of complications.

Adolescent↗
PubMed1995

Pathogenesis of atherosclerosis.

The earliest lesion in the development of an atherosclerotic plaque is the fatty streak. This chronic inflammatory reaction results from a sequence of events that begins with the trapping of low density lipoprotein (LDL) in the subendothelial space of the artery wall. The trapped LDL is seeded with oxidative species released by the overlying endothelium, and lipid oxidation is initiated within the LDL particle. Some of the lipids that result lead to the activation of NFkB-like transcription factors that cause the expression of genes whose protein products mediate monocyte binding, monocyte chemotaxis into the subendothelial space, and conversion into macrophages. At least 1 major gene modulates the oxidation of LDL lipids and/or the biologic response to these lipids. The inverse relation between high density lipoprotein (HDL) and atherosclerotic events may in part be due to enzymes associated with HDL that destroy the biologically active lipids generated in LDL.

1-Alkyl-2-acetylglycerophosphocholine Esterase↗
PubMed1995

NF-Y has a novel role in sterol-dependent transcription of two cholesterogenic genes.

The transcription of farnesyl diphosphate (FPP) synthase is regulated up to 30-fold by the sterol status of the cell. Point mutations in a 6-base pair ATTGGC sequence in the promoter disrupt both sterol-dependent transcription in vivo as well as binding of the transcription factor NF-Y in vitro. Co-transfection of cells with NF-YA29, a dominant negative form of NF-Y, and various promoter-reporter genes specifically inhibits the sterol-dependent regulation of FPP synthase and 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) synthase. In contrast, NF-YA29 does not affect the regulation of reporter genes under the control of promoters derived from either the HMG-CoA reductase or the low density lipoprotein receptor gene. Transient expression of the 68-kDa transcriptionally active fragment of sterol regulatory element-binding protein in cells stimulates an HMG-CoA synthase-reporter gene over 90-fold. This induction is blocked in cells co-expressing NF-YA29. We hypothesize that NF-Y plays a novel role in sterol-dependent regulation of two key genes in the cholesterol biosynthetic pathway and that this role requires a specific interaction with the sterol regulatory element-binding protein or related transcription factors.

Alkyl and Aryl Transferases↗
PubMed1995

Atherosclerosis: basic mechanisms. Oxidation, inflammation, and genetics.

The clinical events resulting from atherosclerosis are directly related to the oxidation of lipids in LDLs that become trapped in the extracellular matrix of the subendothelial space. These oxidized lipids activate an NF kappa B-like transcription factor and induce the expression of genes containing NF kappa B binding sites. The protein products of these genes initiate an inflammatory response that initially leads to the development of the fatty streak. The progression of the lesion is associated with the activation of genes that induce arterial calcification, which changes the mechanical characteristics of the artery wall and predisposes to plaque rupture at sites of monocytic infiltration. Plaque rupture exposes the flowing blood to tissue factor in the lesion, and this induces thrombosis, which is the proximate cause of the clinical event. There appear to be potent genetically determined systems for preventing lipid oxidation, inactivating biologically important oxidized lipids, and/or modulating the inflammatory response to oxidized lipids that may explain the differing susceptibility of individuals and populations to the development of atherosclerosis. Enzymes associated with HDL may play an important role in protecting against lipid oxidation in the artery wall and may account in part for the inverse relation between HDL and risk for atherosclerotic clinical events.

Arteriosclerosis↗
PubMed1995

Wnt-4 expression induces a pregnancy-like growth pattern in reconstituted mammary glands in virgin mice.

Expression of Wnt-4, a member of the Wnt gene family, is induced during early pregnancy in the mouse mammary gland. To investigate the function of Wnt-4, we used a recombinant retrovirus to constitutively express the gene in transplanted mammary epithelium grown in virgin animals. In fully grown glands, Wnt-4 expression resulted in ducts that were more highly branched than normal and caused some premature alveolar development. These changes resembled those seen during pregnancy, suggesting that endogenous Wnt-4 expression may regulate epithelial branching in early pregnancy. The modified growth pattern induced by Wnt-4 expression was similar to that induced by Wnt-1, one of the members of the Wnt gene family activated by mouse mammary tumour virus. As Wnt-1 is not normally expressed in the mammary gland, it may exert its effect on the mammary gland by activating a developmental pathway normally regulated by Wnt-4.

Animals↗