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Biomedical subjects

S Clark

Publications and source records attributed to S Clark.

At least 217 records · Page 12Linked to original sources
PubMed1994

Psychiatric and mental health concerns in the patient with sepsis.

This article describes the psychosocial responses and complications that nurses may encounter in the patient who is septic. The distinctions between behavioral responses as a result of physiologic alterations are compared to responses that are a result of psychological processes. The importance of a careful and routine mental status examination is emphasized.

Critical Care↗
PubMed1994

A comparison of whole cell protein profiles for sporadic human isolates of Streptococcus equisimilis and beta-haemolytic group G streptococci.

Whole cell protein profiles were resolved for Streptococcus equisimilis (group C) and large colony human biotype beta-haemolytic group G streptococci by the use of one dimensional sodium dodecyl sulphate-polyacrylamide gel electrophoresis. Strains of S. equisimilis (27 in toto) were distributed among eight patterns designated A to H. Pattern A represented 48.2% of the latter isolates. Strains of group G streptococci (59 in toto) were distributed among sixteen patterns designated 1-16, and there were no predominant patterns which represented more than 20% of all strains. Profiles were reproducible, not susceptible to strain passage, but susceptible to variation in growth media. Considerable homology was observed among bacteria in either Lancefield group.

Bacterial Proteins↗
PubMed1993

Activation of phospholipase D in CHO cells transfected with the human epidermal growth factor (EGF) receptor: differential effects of protein kinase C activation and EGF.

Multiple intracellular signal transduction pathways, including phospholipases A2 and D, can be activated by epidermal growth factor (EGF) in both a protein kinase C (PKC)-dependent and -independent manner. We investigated the activation of phospholipase D (PLD) by a PKC activator, phorbol myristate acetate (PMA) and by EGF in CHO cells transfected with the full-length EGF receptor. In cells labelled with arachidonic acid or linoleic acid, PMA activated a PLD, determined by formation of the transphosphatidylation product phosphatidylethanol in the presence of ethanol. A basal PLD activity was seen in linoleic acid-labelled cells but not in cells labelled with arachidonic acid. This basal activity was augmented by the protein phosphotyrosine phosphatase inhibitor vanadate and reduced by tyrosine kinase inhibition and was contributed to by PKC, as activity could not be elicited following prolonged exposure to phorbol ester, known to down-regulate some PKC isoforms. By contrast, EGF failed to stimulate formation of phosphatidylethanol in cells labelled with either fatty acid species. It is proposed that in the basal condition PKC-dependent PLD activation and protein tyrosine kinase phosphorylation are linked (possibly by a phospholipase C (PLC)-mediated formation of diacylglycerol); EGF which activated a phospholipase A2 (PLA2) but which failed to elicit PLC activation in these cells is without further effect on PLD.

Animals↗
PubMed1993

Characterization of a 50-kDa polypeptide in cytoplasmic dynein preparations reveals a complex with p150GLUED and a novel actin.

Earlier work identified a series of accessory polypeptides of 150, 74, 59, 57, 55, 53, 50, and 45 kDa copurifying with cytoplasmic dynein. In the present study immunoprecipitation of the 50-kDa polypeptide from bovine brain cytosol with a specific monoclonal antibody revealed coprecipitating components of 150, 135, 62, and 45 kDa, which were completely distinct from the polypeptides immunoprecipitated using an antibody to the well established 74-kDa cytoplasmic dynein subunit. The 150- and 135-kDa polypeptides reacted with an antibody to p150Glued, the mammalian homologue of the Drosophila Glued gene. N-terminal microsequencing of tryptic peptides of the major 45-kDa component of the complex revealed it to be the alpha-isoform of centractin, a novel form of actin. Immunoblotting of sucrose gradient-fractionated brain cytosol revealed p150Glued, p50, and centractin to cosediment exclusively at 20 S. Immunofluorescence microscopy using antibody to p150Glued revealed centrosomal staining, which was abolished by microtubule depolymerization. Together these results reveal the 50-kDa polypeptide to be part of a cytosolic complex distinct from cytoplasmic dynein. However, the immunolocalization data indicate an association with microtubule minus ends, suggesting a possible interaction with cytoplasmic dynein in the cell.

Actins↗
PubMed1993

Sulphydryl agents modulate insulin- and epidermal growth factor (EGF)-receptor kinase via reaction with intracellular receptor domains: differential effects on basal versus activated receptors.

Sulphydryl reagents have been shown to produce a variety of effects on insulin-receptor structure and function. However, localization of these effects to specific receptor domains has not been attempted. We have investigated this question with insulin- and epidermal growth factor (EGF)-receptors (both are receptor tyrosine kinases but have different sulphydryl/disulphide structures within the external domain), and the insulin receptor kinase (IRK) protein consisting solely of the insulin-receptor cytoplasmic domain and exhibiting constitutive kinase activity. Results showed a differential response between basal and activated receptors. The physiological reductant GSH stimulated basal receptor autophosphorylation, but was either without effect (EGF) or inhibited (insulin) activated receptors, and occurred without visible reduction of receptor structure. These results contrast with those obtained with dithiothreitol which appears to activate phosphorylation in association with reduction of the extracellular insulin-receptor disulphides, but is without effect on the EGF receptor or the IRK protein. Alkylating agents N-ethylmaleimide (NEM) and iodoacetamide (IAM) had opposing effects on receptor autophosphorylation. However, only in the basal state was IAM able to protect receptors from the inhibitory effect of NEM. Our results suggest that complex sulphydryl interactions can occur within the cytoplasmic domain of insulin- and EGF-receptors to alter receptor kinase activity. The basal and activated state of receptors is not the same with respect to sulphydryl reagent action, possibly due to conformational change in the receptor induced by ligand (insulin, EGF) or constitutive (IRK) activation.

Alkylation↗
PubMed1993

The oxygen consumption/oxygen delivery curve in severe preeclampsia: evidence for a fixed oxygen extraction state.

OBJECTIVE: Increased total body oxygen consumption requirements are usually met by increased oxygen delivery and increased oxygen extraction. In certain conditions (e.g., adult respiratory distress syndrome) the ability to increase oxygen extraction is lost, and any increase in oxygen consumption depends on increased oxygen delivery. The objective of this study was to investigate the oxygen delivery/oxygen consumption relationship in severe preeclampsia. STUDY DESIGN: Thirty-two patients with severe preeclampsia (blood pressure > 160/110 mm Hg; 3 to 4+ proteinuria) were monitored with a pulmonary artery catheter. Baseline oxygen consumption and delivery in a group without volume expansion or pharmacologic vasodilatation were compared with those in a group who had received a magnesium sulfate infusion. RESULTS: Oxygen consumption, oxygen delivery, arterial-venous-oxygen difference, and the oxygen extraction ratio were low when compared to that for normal 32 to 38 week pregnancy. The oxygen extraction ratio, defined as the ratio of oxygen consumption to oxygen delivery, was abnormally low for pregnancy, especially considering the low oxygen delivery levels in these patients. Oxygen consumption was dependent on oxygen delivery over the entire range of values seen. CONCLUSIONS: Severe preeclampsia is associated with an abnormality of tissue oxygen extraction, as evidenced by a low and unresponsive oxygen extraction ratio. Oxygen consumption increases proportionately with increases in oxygen delivery without reaching an oxygen delivery-independent state. Even at high oxygen delivery levels the oxygen consumption in preeclamptic patients is still abnormally low for pregnancy.

Adolescent↗
PubMed1993

Activity and distribution of tissue transglutaminase in association with nerve-muscle synapses.

We have measured, characterized, and localized calcium-dependent protein cross-linking activity in rat skeletal muscle, and in myotubes cultured independently or in coculture with spinal neurones, catalyzed by the enzyme tissue transglutaminase (tTG). The enzyme activity was present in both motor endplate and endplate-free zones of rat diaphragm muscle. tTG in the endplate zone was more tightly associated with the tissue. This form of association was absent in extracts of peripheral nerve. Cross-linking of endogenous proteins, as measured by the content of epsilon-(gamma-glutamyl)lysine isopeptide, was higher in the endplate than in the nonendplate zone. Cytosolic (C) and particulate (B) forms of tTG were separated by ion-exchange chromatography from both regions of the muscle. In the motor endplate zone, a higher proportion of tightly bound tTG was recovered as a separate (B1) particulate form. Km values for calcium activation of the three forms of tTG were in the range of 5-15 microM. Immunocytochemistry with polyclonal and monoclonal antibodies revealed the enzyme at motor endplates and at contacts between neurites of rat embryo spinal neurones and myotubes in primary cocultures. Appearance of the B1 transglutaminase could be induced by coculturing myotubes of the mouse C2C12 cell line with neurones. The results suggest that tTG is most concentrated and active at the motor endplate.

Animals↗
PubMed1993

Critical care by emergency physicians in American and English hospitals.

The object of this study was to compare emergency physician critical care services in an American (A) and an English (E) Emergency Department (ED). A prospective case comparison trial was used. The study was carried out at two university affiliated community hospitals, one in the U.S.A and one in England. Subjects were consecutive patients triaged as requiring critical care services and subsequently admitted to the hospital ward (A, n = 17; E, n = 18) or the intensive/critical care unit ([ICU] A, n = 14; E, n = 24). The study time period was randomly selected 8-h shifts occurring over a 4-week period. All patients were treated by standard guidelines for critical care services at the study hospital emergency department. For all study patients mean length of stay was significantly longer for the American (233 min, 95% CI 201, 264) than the English ED (24 min, 95% CI 23, 25). American emergency physicians spent less total time providing physician services (19.2 min, 95% CI 16.8, 21.6) vs. (23 min, 95% CI 21.6, 24.4) than English emergency physicians. American emergency physicians spent less time with the patient than English emergency physicians: 12.4 min (95% CI 10.3, 14.5) vs. 17 min (95% CI 15.8, 18.2). American emergency physicians spent more time on the telephone 1.8 min (95% CI 1.4, 2.2) vs. 1.2 min (95% CI 1.1, 1.3), and in patient care discussions/order giving 1.8 min (95% CI 1.4, 2.2) vs. 1.1 min (95% CI .8, 1.4), There was no significant difference in time charting (3.2 min, 95% CI 2.8, 3.6 vs. 3.5 min, 95% CI 3.2, 3.8). Results did not vary significantly whether analysed subgroups or the whole study group. American emergency physicians provided 81% of their service during the first hour. There were delays at the American hospital until the physician saw the patient: 4.9 min (95% CI 2.5, 7.3) for patients admitted to the ICU/CVU (Cardiovascular Unit), and 9.2 min (95% CI 4.6, 13.8) for patients admitted to the ward. At the American hospital, ICU/CVU physicians provided additional physician services in the emergency department whether the patient was admitted to the ward (6.7 min, 95% CI 5.5, 7.9) or the ICU/CVU (12.1 min, 95% CI 8.8, 15.9). For patients admitted to the ICU/CVU 47% of the length of stay was spent waiting for a bed to become available after the decision to admit had been made. Emergency physicians at E provided critical care services almost continuously during a short stay in the ED. Emergency physicians at A provided services intermittently with most services during an initial period of stabilization. Further study is necessary to identify what factors contribute to these different approaches to critical care in the ED.

Critical Care↗
PubMed1993

Comparison of an enzyme immuno assay (Antigenz Chlamydia) with cell culture for the detection of genital chlamydial infection in high and low risk populations.

OBJECTIVE: To evaluate a new enzyme immuno assay, Antigenz Chlamydia, for the detection of chlamydial antigen in urogenital samples using cell culture as the gold standard for comparison and direct immuno fluorescence to aid resolving the discrepancies. SUBJECTS: 212 men and 303 women attending an STD clinic and 404 women of child bearing age attending gynaecological clinics. RESULTS: Sensitivity, specificity, predictive value of positive result and predictive value of negative result of the new test were 77.6%, 99.0%, 94.3%, and 95.7% respectively in the high risk population with a prevalence of 16.5%. In the low risk population the figures were 84.2%, 94.5%, 43.2% and 99.2% respectively with a prevalence of 4.7%. CONCLUSION: Antigenz Chlamydia is an easy and quick test to perform. The test is suitable for use in high risk and low risk populations provided all positive samples are confirmed.

Adult↗
PubMed1993

Bias and variability in blood pressure measurement with ambulatory recorders.

This study sought to determine whether patient characteristics such as age, sex, blood pressure, and pulse pressure differently affect the accuracy of an oscillometric (SpaceLabs 90207) and a microphonic (TM2420 version 7) blood pressure monitor. Blood pressure recorded by two oscillometric and two microphonic ambulatory monitors was compared with simultaneous readings by two pairs of trained, blinded observers using random-zero sphygmomanometry. One hundred and eighteen subjects (53 men and 65 women, aged 17 to 94 years; systolic pressure, 89 to 211 mm Hg; diastolic, 44 to 116 mm Hg) were studied. There were no significant differences within each observer pair or between the two observer pairs as well as no correlation between interobserver differences and patient characteristics. The differences between the monitor and trained observers' readings were 2.8 +/- 9.9 mm Hg systolic and 3.9 +/- 6.8 mm Hg diastolic for the SpaceLabs and 5.0 +/- 5.2 mm Hg systolic and 3.4 +/- 6.1 mm Hg diastolic for the TM2420. Patient characteristics that predicted measurement error were defined by multiple regression. For oscillometry, systolic measurement error was highly correlated with systolic pressure, pulse pressure, and subject age. The diastolic error was significantly correlated with pulse pressure, diastolic pressure, and subject sex. For the oscillometric monitor, patient characteristics accounted for 36.6% of the variation of the systolic error and 34.7% of the variation of the diastolic error. For the microphonic monitor, only age correlated with diastolic error, and no significant correlations were seen with systolic error. Patient characteristics accounted for only 1.2% of the systolic and 8.9% of the diastolic error.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

Parathyroid hormone represses alpha 1(I) collagen promoter activity in cultured calvariae from neonatal transgenic mice.

We examined the effect of PTH on the activity of alpha 1(I) collagen promoter fusion genes in cultured calvariae from transgenic mice. The parent construct, ColCAT 3.6, contains 3520 basepairs of 5' rat alpha 1(I) collagen DNA, 115 basepairs of untranslated alpha 1(I) collagen-coding DNA, and the bacterial chloramphenicol acetyltransferase reporter gene, while the 5'-deletion ColCAT 2.3 contains 2296 kilobases of rat alpha 1(I) collagen promoter sequence. Transgenic mouse lines harboring these collagen promoter fusion genes were developed using the oocyte microinjection technique, and for each construct, three different lines of mice were tested. Calvariae from 6- to 8-day-old transgenic mice were cultured for 48 h with or without bovine PTH-(1-34). ColCAT 3.6 and ColCAT 2.3 were expressed at comparable levels in calvariae and were inhibited by PTH. There were parallel decreases in the incorporation of [3H]proline into collagen and levels of the endogenous alpha 1(I) collagen mRNA and transgene mRNA. Forskolin at 10 microM mimicked the inhibitory effect of PTH on promoter activity in ColCAT 3.6 and ColCAT 2.3 calvariae. A RNase protection assay showed that the transgene was initiated correctly from the transgene promoter. These data show that PTH and cAMP can repress collagen promoter activity in calvariae from transgenic mice, suggesting that the alpha 1(I) collagen promoter may contain cis elements down-stream of -2.3 kilobases that mediate PTH and cAMP repression of collagen gene expression in bone. Cultured bone explants from transgenic mice can be used as a model to study hormonal regulation of alpha 1(I) collagen promoter constructs.

Animals↗