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D Slater

Publications and source records attributed to D Slater.

At least 37 records · Page 2Linked to original sources
PubMed1994

Implication of mRNA binding proteins in the regulation of cyclo-oxygenase in human amnion at term.

The onset of labour is associated with an increase in prostaglandin synthesis in amnion which appears to be mediated at least in part by an increase in cyclo-oxygenase (COX) expression. We have tested the hypothesis that COX expression is controlled in amnion by the binding of a protein to the COX mRNA which may inhibits its translation, as has been seen in vascular smooth muscle cells. Using differential RNA extraction protocols which extract either total mRNA or only mRNA which is not protein bound, we have found that, in amnion, the increase in COX-2 expression seen after the onset of labour is entirely in the protein bound fraction. Unlike in vascular smooth muscle, increased expression of COX-2 in amnion cells is therefore associated with increased rather than decreased protein binding to the mRNA. This protein may be involved in translation initiation or elongation or in mRNA stability. There does not appear to be a protein bound COX-1 mRNA fraction.

Amnion↗
PubMed1994

The relative abundance of type 1 to type 2 cyclo-oxygenase mRNA in human amnion at term.

The onset of labor in humans is associated with an increase in prostaglandin production. One of the key steps is the conversion of arachidonic acid to prostaglandin E2 by cyclo-oxygenase (Cox). Cox has been found to exist as two distinct genes, Cox-1 and Cox-2. We have used RT-PCR to study the relative abundance of mRNA from each Cox gene in amnion at term. Quantitation of PCR efficiency indicated an approximate 100 fold excess of Cox-2 messenger RNA over that for Cox-1. These data point to the importance of Cox-2 in the increased prostaglandin synthesis associated with labor. Further studies should therefore focus on the control mechanisms for Cox-2.

Amnion↗
PubMed1994

The expression of phospholipase A2 and lipocortins (annexins) I, II and V in human fetal membranes and placenta in association with labour.

We have studied the expression of the cellular, type two phospholipase A2 and lipocortins (annexins) I, II and V in human amnion, chorion-decidua and placenta using northern analysis. We found no difference in the expression of phospholipase A2 or lipocortin V in tissues obtained before or after labour. Lipocortin I expression was found to decrease in amnion and placenta but increase in chorion decidua with the onset of labour, while expression of lipocortin II increased only in amnion. These results support the hypothesis that the increased phospholipase A2 activity in the fetal membranes and placenta which is associated with labour is not due to increased phospholipase A2 gene expression, but that post translational control of phospholipase A2 activity may be mediated through changes in lipocortin I expression.

Annexin A1↗
PubMed1993

Production of biologically active light chain of tetanus toxin in Escherichia coli. Evidence for the importance of the C-terminal 16 amino acids for full biological activity.

The activity of the light (L) chain of tetanus toxin, and of mutants constructed by site-directed mutagenesis, was studied by expression and purification of the proteins from E. coli. Wild-type recombinant L chain (pTet87) was active in the inhibition of exocytosis from cultured bovine adrenal chromaffin cells, although at a level 5-15% of that of L chain purified from tetanus toxin. L chain mutants which terminated at Leu-438 (pTet89), or which contained a Cys-to-Ser mutation at residue 439 (pTet88) were equally as active as the full-length recombinant protein. The reduced activity of pTet87 L chain correlated with C-terminal proteolysis of the protein upon purification. A tryptic fragment derived from native light chain and which terminated at Leu-434 also showed reduced activity in the exocytosis assay, consistent with a requirement of the C-terminal region of the L chain for maximal activity. pTet87 L chain, but neither of the mutants, could be associated with purified H (heavy) chain to form a covalent dimer which induced the symptoms of tetanus in mice. The ability to form biologically active toxin using recombinant L chain will be of great value in structure-function studies of tetanus toxin.

Adrenal Medulla↗
PubMed1993

Effective control of hypercholesterolemia in children with dietary interventions based in pediatric practice.

BACKGROUND: Based on recent recommendations, the number of hypercholesterolemic children who would require dietary therapy could overwhelm current preventive pediatric cardiology resources. No previous studies have established the efficacy of such therapy in the pediatrician's office. The purpose of this study was to evaluate two programs of office-based therapy. METHODS: We randomly assigned 295 children with hypercholesterolemia (> 185 mg/dl) two interventions: one single or four multiple 90-min sessions of family-oriented nutritional education, based in pediatric practices. We examined total cholesterol, 3-day food records, height and weight, and in the multisession group high-density lipoprotein cholesterol and triglycerides at the beginning and at intervals of 8.5-9 and 21 to 33 weeks (single-session and multisession groups, respectively). RESULTS: Total cholesterol was lowered equally in both treatment groups over the course of the study. This was accompanied by dietary changes: a decrease in calories derived from total and saturated fats, and increased intake of fiber, protein, and carbohydrate. However, more single-session patients withdrew from the program during the study. CONCLUSIONS: The two interventions were equally effective in lowering total and low-density lipoprotein cholesterol and in reducing intake of total and saturated fat. However, the higher completion rate of the multisession group suggests that this approach may be the more effective.

Adolescent↗
PubMed1993

Expression of a common cellular phospholipase A2 by human intrauterine tissues.

A subclone of the three prime (3') end of a human extrapancreatic phospholipase cDNA has been generated using the polymerase chain reaction. This has been used to detect mRNA transcripts in RNA extracted from human amnion, chorion-decidua, placenta and myometrium. The carboxyl-terminus of phospholipases A2 is poorly conserved but hybridisation remained stable under conditions of high stringency. This supports the hypothesis that these tissues express a common cellular phospholipase A2 which is identical to that expressed in platelets.

Amnion↗
PubMed1993

Changes in amniotic arachidonic acid metabolism associated with increased cyclo-oxygenase gene expression.

OBJECTIVES: To study the differences in the metabolism of arachidonic acid, to prostaglandins and other eicosanoids, between amnion cells before and after labour. To study the changes in the expression of the type 1 cyclo-oxygenase gene associated with the changes in arachidonic acid metabolism. DESIGN: Amnion cells collected before labour, at elective caesarean section, and following spontaneous labour and delivery were established in mono-layer culture. Intracellular arachidonic acid pools were radio-labelled and the metabolic fate of endogenous archidonic acid was then studied using high performance liquid chromatography. RNA was extracted from the cell cultures and expression of the cyclooxygenase gene was studied using northern hybridisation to a sheep cyclo-oxygenase cDNA. RESULTS: Metabolism of endogenous arachidonic acid in amnion cells established in culture prior to labour is principally via lipoxygenase and epoxygenase enzyme pathways to di- and mono-HETEs and EET with little cyclo-oxygenase metabolism to prostaglandins. Following labour there is a large increase in arachidonic acid metabolism with a change in the cyclo-oxygenase: lipoxygenase enzyme pathway ratio in favour synthesis of prostaglandin E2. Whilst synthesis of lipoxygenase metabolites doubles, the increase in prostaglandin E2 synthesis is ten fold. Expression of the cyclo-oxygenase gene is significantly greater in cell cultures established following spontaneous labour and delivery than in those established following elective caesarean section prior to labour. CONCLUSIONS: In association with labour there is an increase in arachidonic acid metabolism in amnion cells and a change in the ratio of metabolism via cyclo-oxygenase and lipoxygenase enzyme pathways to increase synthesis of prostaglandin E2. This change is associated with increased expression of the cyclooxygenase gene.

Amnion↗
PubMed1993

Particulate air pollution and hospital emergency room visits for asthma in Seattle.

Recent studies have associated short-term exposure to respirable particulate matter (PM10) exposure with peak flow decrements, increased symptoms of respiratory irritation, increased use of asthma medications, and increased hospitalization for asthma. Increased mortality from chronic respiratory disease has also been reported. To help confirm whether PM10 exposure is a risk factor for the exacerbation of asthma, we compiled daily records of asthma emergency room visits from eight hospitals in the Seattle area. In Poisson regressions controlling for weather, season, time trends, age, hospital, and day of the week, the daily counts of emergency room visits for persons under age 65 were significantly associated with PM10 exposure on the previous day. The mean of the previous 4 days' PM10 was a better predictor (p < 0.005). The relative risk for a 30 micrograms/m3 increase in PM10 was 1.12 (95% confidence interval 1.20 to 1.04). Daily PM10 concentrations never exceeded 70% of the current ambient air quality standards during the period. The consistency of investigations of the health effects of PM10 suggest that increased attention should be given to the control of particulate matter air pollution.

Adolescent↗