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Biomedical subjects

P Stewart

Publications and source records attributed to P Stewart.

At least 73 records · Page 4Linked to original sources
PubMed1997

Drawover vaporizers for sedation in intensive care.

OBJECTIVE: We have undertaken a laboratory study to determine whether a drawover vaporizer in the inspiratory limb of an intensive care ventilator circuit can produce safe and therapeutic concentrations of isoflurane. DESIGN: An Oxford Miniature Vaporizer (OMV) and Ohmeda TEC vaporizer were assessed over the range of inspired isoflurane concentrations, airway pressures and tidal volumes experienced in the ICU. CONCLUSIONS: The experimental findings suggest that the OMV inhaler in plenum mode can be relied upon to produce safe concentrations of isoflurane over a clinically useful range of inspired concentrations. Furthermore, it behaves predictably over the range of airway pressures likely to be encountered in the patient admitted with acute severe asthma. However, we found that the Ohmeda TEC vaporizer did not perform reliably in this setting.

Anesthetics, Inhalation↗
PubMed1997

Injuries among children in home and out-of-home care.

UNLABELLED: As the number of children receiving care in out-of-home settings increases in the United States, the risk of injury in such settings has become the subject of intense research. OBJECTIVES: This study examined the relative safety of out-of-home care compared with care in a child's own home. METHODS: This community based prospective cohort study of 656 families in three adjacent counties in the Piedmont region of North Carolina characterizes the patterns and rates of injuries among children less than 5 years of age in three child care settings, home care (HC), center based care (CBC), and other out-of-home care (OOHC). Information about minor and severe injuries was obtained from parents using monthly telephone interviews over a one year period. Statistical modeling designed to handle unbalanced data with correlated observations was used as the primary tool for analysis. RESULTS: Rate of minor injuries was highest in CBC, followed by HC, and then OOHC. However, these differences for OOHC may have been due to reporting biases and errors in rate estimates. There were no significant differences in severe injury rates among the three settings. CONCLUSIONS: The risk of serious injury among children under 5 in CBC is not different from that of children in HC or OOHC despite the fact that the risk of minor injury is higher.

Accidents, Home↗
PubMed1997

Metabolic basis of hypotriglyceridemic effects of insulin in normal men.

The mechanism by which acute insulin administration alters VLDL apolipoprotein (apo) B subclass metabolism and thus plasma triglyceride concentration was evaluated in 7 normolipidemic healthy men on two occasions, during a saline infusion and during an 8.5-hour euglycemic hyperinsulinemic clamp (serum insulin, 490 +/- 30 pmol/L). During the insulin infusion, plasma triglycerides decreased by 22% (P < .05), and serum free fatty acid decreased by 85% (P < .05). The plasma concentration of VLDL1 apo B fell 32% during the insulin infusion, while that of VLDL2 apo B remained constant. A bolus injection of [3-(2)H]leucine was given on both occasions to trace apo B kinetics in the VLDL1 and VLDL2 subclasses (Svedberg flotation rate, 60-400 and 20-60, respectively), and the kinetic basis for the change in VLDL levels caused by insulin was examined using a non-steady-state multicompartmental model. The mean rate of VLDL1 apo B synthesis decreased significantly by 35% (P < .05) after 0.5 hour of the insulin infusion (523 +/- 87 mg/d) compared with the saline infusion (808 +/- 91 mg/d). This parameter was allowed to vary with time to explain the fall in VLDL1 concentration. After 8.5 hours of hyperinsulinemia, the rate of VLDL1 apo B synthesis was 51% lower (321 +/- 105 mg/d) than during the saline infusion (651 +/- 81 mg/d, P < .05). VLDL2 apo B production was similar during the saline (269 +/- 35 mg/d) and insulin (265 +/- 37 mg/d) infusions. No significant changes were observed in the fractional catabolic rates of either VLDL1 or VLDL2 apo B. We conclude that acute hyperinsulinemia lowers plasma triglyceride and VLDL levels principally by suppressing VLDL1 apo B production but has no effect on VLDL2 apo B production. These findings indicate that the rates of VLDL1 and VLDL2 apo B production in the liver are independently regulated.

Adult↗
PubMed1996

Infertility may sometimes be associated with NSAID consumption.

Non-steroidal anti-inflammatory drugs are widely used in the treatment of inflammatory joint diseases. Many patients suffering from these disorders are young women during their childbearing years. We report three cases of infertility where the cause may have been NSAID-induced 'luteinized unruptured follicle' syndrome. This phenomenon is well recognized in obstetric circles, and we would like to bring it to the attention of rheumatologists since it is not documented in the rheumatological literature.

Adult↗
PubMed1996

Efficient expression of a Phanerochaete chrysosporium manganese peroxidase gene in Aspergillus oryzae.

A manganese peroxidase gene (mnp1) from Phanerochaete chrysosporium was efficiently expressed in Aspergillus oryzae. Expression was achieved by fusing the mature cDNA of mnp1 with the A. oryzae Taka amylase promoter and secretion signal. The 3' untranslated region of the glucoamylase gene of Aspergillus awamori provided the terminator. The recombinant protein (rMnP) was secreted in an active form, permitting rapid detection and purification. Physical and kinetic properties of rMnP were similar to those of the native protein. The A. oryzae expression system is well suited for both mechanistic and site-directed mutagenesis studies.

Aspergillus oryzae↗
PubMed1996

Sensitive methods to study human apolipoprotein B metabolism using stable isotope-labeled amino acids.

The objective of the study was to develop a sensitive method using stable isotope-labeled tracers that would permit the determination of apolipoprotein B (apoB) metabolism in very low-density lipoprotein subfractions (VLDL1, Sf 60-400; VLDL2, Sf 20-60), intermediate-density lipoprotein (IDL, Sf 12-20), and low-density lipoprotein (LDL, Sf 0-12). Six normolipidemic subjects were given trideuterated leucine, and its clearance from plasma and appearance in the four apoB-containing lipoprotein fractions were followed by use of a highly sensitive gas chromatography-mass spectrometry technique in which the m + 3-to-m + 2 ion ratio was selectively monitored. This analytic approach permitted the precise measurement of low enrichments in IDL and LDL and extension of the turnover out to 250-300 h. A compartmental model was developed to derive rate constants from the plasma and apoB enrichment curves. The model was uniquely identifiable once parameter dependencies had been introduced to reduce the number of unknowns. Values were obtained for apoB input into all lipoprotein density intervals, together with rates of interconversion and catabolism; these agreed well with results from radioiodinated tracer experiments. An alternative model structure was also explored in which input occurred only into VLDL1. Altering the protocol of tracer administration (bolus vs. primed constant infusion) and dose (over a 10-fold range) had no influence on the results obtained. The analytic and modeling approach described will permit stable isotopes to be used to elucidate key features of apoB metabolism in normal and pathological states.

Adult↗
PubMed1996

Accumulation of large very low density lipoprotein in plasma during intravenous infusion of a chylomicron-like triglyceride emulsion reflects competition for a common lipolytic pathway.

Very low density lipoproteins (VLDL) are produced in the liver and contain apolipoprotein (apo) B-100 and endogenous lipids. By contrast, ingestion of fat leads to formation of chylomicrons containing apoB-48 secreted from the intestine. In this study, a 60-min intravenous infusion of a chylomicron-like triglyceride emulsion was given to healthy young men to examine whether competition between chylomicrons and VLDL for the same lipolytic pathway explains the increase in VLDL seen after meals. The responses of two major VLDL subfractions were determined by measuring the concentrations of apoB-100 in fractions of triglyceride-rich lipoproteins with Svedberg flotation rates of 60-400 (large VLDL) and 20-60 (small VLDL) that were separated from plasma by density gradient ultracentrifugation. A threefold elevation in plasma triglycerides was observed during the infusion together with a consistent linear increase of large VLDL. The rate at which large VLDL accumulated in plasma differed markedly among individuals and was not enhanced by doubling of the infusion rate. The response of small VLDL was more heterogeneous; however, a decrease was seen in most subjects. The combined pattern for the two VLDL species is what would be expected if large VLDL particles are the precursors of smaller VLDL species and if lipolysis of large VLDL is inhibited through competition from the triglyceride emulsion. The extent to which the triglyceride emulsion inhibited the lipolysis of VLDL and/or influenced the synthesis rate of large VLDL was estimated from simultaneous stable isotope studies. The emulsion caused a 75-90% block of the conversion of large VLDL apoB to small VLDL apoB and there was no sign of enhanced synthesis of large VLDL after infusion of the triglyceride emulsion. The corollary of these findings is that chylomicrons and their remnants impede the normal lipolytic degradation of VLDL and could thereby be indirectly implicated in the generation of atherogenic remnant lipoproteins.

Adult↗
PubMed1995

Quantitation of fungal mRNAs in complex substrates by reverse transcription PCR and its application to Phanerochaete chrysosporium-colonized soil.

Thorough analysis of fungi in complex substrates has been hampered by inadequate experimental tools for assessing physiological activity and estimating biomass. We report a method for the quantitative assessment of specific fungal mRNAs in soil. The method was applied to complex gene families of Phanerochaete chrysosporium, a white-rot fungus widely used in studies of organopollutant degradation. Among the genes implicated in pollutant degradation, two closely related lignin peroxidase transcripts were detected in soil. The pattern of lignin peroxidase gene expression was unexpected; certain transcripts abundant in defined cultures were not detected in soil cultures. Transcripts encoding cellobiohydrolases and beta-tubulin were also detected. The method will aid in defining the roles of specific genes in complex biological processes such as organopollutant degradation, developing strategies for strain improvement, and identifying specific fungi in environmental samples.

Base Sequence↗
PubMed1995

Does renal impairment protect from gout?

OBJECTIVE: To test whether renal impairment protects from the development of gout. METHODS: We conducted a retrospective cohort study in which 40 hyperuricemic patients (serum uric acid > 0.54 mM/l) with renal impairment (serum creatinine > 200 microM/l) and 40 equally hyperuricemic patients with normal renal function (serum creatinine < 120 microM/l) were given a telephone questionnaire eliciting a history of gout, its pattern and severity, and other features of medical and family history. RESULTS: There was no significant difference among the prevalence of gout (relative risk 1.1, confidence interval 0.73-1.67), the pattern and severity of gout, and the presence of tophi between the 2 groups. A positive family history of gout was significantly increased in the patients with gouty arthritis (p < 0.05). CONCLUSION: Renal impairment does not protect from gout. There may be a familial factor in the development of gout that is independent from the familial tendency for hyperuricemia.

Adult↗
PubMed1994

Total body nitrogen as a predictor of clinical status in anorexia nervosa.

It has been demonstrated that clinical outcome is positively correlated with depletion of total body nitrogen (TBN) and therefore of body protein in certain serious medical conditions such as cystic fibrosis or patients receiving dialysis for chronic renal failure. Patients with anorexia nervosa are not suffering from medical illness per se yet the illness can be chronic and severely debilitating requiring numerous hospitalizations for refeeding and/or management of medical complications. The prediction of chronicity remains an important and difficult issue that this study seeks to address by examining the correlation between several clinical indices in 18 patients suffering from anorexia nervosa with parameters of body composition, namely TBN and percentage body fat. TBN was measured using the technique of in vivo neutron-activation analysis (IVNAA) and expressed as nitrogen index. Percentage body fat was estimated using skinfold measurements. The highest correlation was between nitrogen index and number of hospitalizations (r = -.80). The data support a relationship between depletion of body nitrogen/protein and chronicity in anorexia nervosa.

Adolescent↗
PubMed1994

Establishment of genetic linkage by allele-specific polymerase chain reaction: application to the lignin peroxidase gene family of Phanerochaete chrysosporium.

Determining linkage is problematic for genes lacking easily identifiable phenotypes and for organisms without well-defined genetic recombination systems. Phanerochaete chrysosporium with its lignin peroxidase (LiP) gene family typifies these difficulties. We describe an experimental approach whereby the segregation of specific alleles is directly monitored during sexual fruiting. The method establishes linkage relationships among genes for which there are no mutations, and it is applicable to a wide range of genes, gene families and organisms. Using this approach, five P. chrysosporium linkage groups were identified. Ten LiP genes were distributed among three of these groups. One co-segregating group contained eight closely linked LiP genes. Another LiP gene was linked to a cellobiohydrolase gene cluster. These genetic linkages were consistent with physical mapping by pulsed field gel electrophoresis. Based on the identification of allelic relationships, a uniform nomenclature for LiP genes is also described.

Alleles↗