Search PubMed⌕ Search

Biomedical subjects

M Welch

Publications and source records attributed to M Welch.

At least 91 records · Page 5Linked to original sources
PubMed1993

Acute ischaemia of the lower limb: an unusual presenting feature of acute lymphoblastic leukaemia.

Malignant disease is often complicated by coagulation disorders presenting as abnormal clotting or bleeding, acute leukaemia being more often associated with the latter. Acute lymphoblastic leukaemia presenting with peripheral arterial thromboembolism, previously unreported in the literature, is presented. Aetiology, clinical features, and management of coagulation disturbances associated with malignancy are also reviewed.

Adult↗
PubMed1993

The preservation of renal function by isovolemic hemodilution during aortic operations.

PURPOSE: In an investigation of the effects of isovolemic hemodilution, 39 consecutive patients undergoing elective infrarenal aortic operation had detailed measurements of renal function, renal artery blood flow, and cardiac hemodynamics. METHODS: The patients were randomly allocated to receive acute preoperative isovolemic hemodilution to a hematocrit of 28%, with 20 patients receiving hemodilution and 19 being control subjects. RESULTS: Twelve (63%) of the control group had renal impairment, compared with only four (20% in the group receiving hemodilution (p < 0.01). Hemodilution also prevented the fall in cardiac output induced by cross-clamping (p < 0.01) and significantly reduced the need for transfusion of donor blood (p < 0.01). CONCLUSIONS: Acute isovolemic hemodilution is clearly a useful adjunct in the management of patients undergoing elective aortic operation.

Acute Kidney Injury↗
PubMed1992

Acetyladenylate or its derivative acetylates the chemotaxis protein CheY in vitro and increases its activity at the flagellar switch.

CheY, a key protein in the mechanism of bacterial chemotaxis, is known to interact with the flagellar switch and thereby cause clockwise rotation. This activity of CheY was significantly increased by producing acetyladenylate (AcAMP) within cytoplasm-free bacterial envelopes containing purified CheY. This was achieved by including in the envelopes the enzyme acetyl-CoA synthetase (ACS) and ATP, and adding acetate externally. The fraction of clockwise-rotating envelopes, tethered to glass by their flagella, increased from 14% to 58% by the presence of AcAMP (or its derivative). In parallel experiments carried out with [14C]acetate under similar conditions, CheY became acetylated: [1-14C]acetate was as effective as [2-14C]acetate in labeling CheY, and ACS-dependent labeling of CheY by [alpha-32P]ATP was not detected. The switch proteins, FliG, FliM, and FliN, isolated to purity, were not acetylated. The acetylation was specific for CheY and dependent on its native conformation. The acetylated form the CheY was estimated to be more active than its nonacetylated form by 4-5 orders of magnitude. Acetylated CheY was stable in the presence of the strong nucleophiles hydroxylamine or ethanolamine, indicative of N-acetylation. There was a correlation between the activity of CheY in vivo and its ability to be acetylated in vitro. Thus, proteins with a single substitution at their active site, CheY57DE and CheY109KR, are not active in vivo and accordingly were not acetylated in vitro; in contrast, the protein CheY13DK is active in vivo and was normally acetylated in vitro. The possibility that CheY acetylation plays a role in bacterial chemotaxis is discussed.

Acetylation↗
PubMed1992

Steroidogenic potential of lyophilized mitochondria from bovine adrenocortical tissue.

When incubated with [3H]cholesterol, a bovine adrenocortical mitochondrial pellet obtained by centrifugation at 12,000 x g yielded, as expected, only the C21O2 metabolites progesterone and pregnenolone. However, the steroidogenic potential of the 12,000 x g pellet fraction was augmented significantly by lyophilization. After lyophilization, the 12,000 x g pellet converted the sterol into C19 androgens and corticosteroids, in addition to C21O2 pregnane derivatives. Leaching the lyophilized mitochondrial fraction with either hexane or acetone increased substantially the yields of the metabolites. It did not change qualitatively the array of metabolites formed during in vitro incubation, but 5 alpha-reductase activity was unmasked by the washings, particularly with acetone. Thus, the fraction sedimented at 12,000 x g contains the complete complement of steroidogenic enzymes required for the biosynthesis of the aforementioned adrenal hormones. These results cast doubt upon the widely held belief that the various enzymes required for adrenocortical steroidogenesis are distributed between two different subcellular compartments, the mitochondrion and the endoplasmic reticulum.

Adrenal Cortex↗
PubMed1992

Role of topical lignocaine during carotid endarterectomy.

Forty carotid endarterectomies were undertaken in 34 patients. Operations were prospectively randomized to periarterial application of either 1 per cent lignocaine (n = 19) or normal saline (n = 21), and detailed measurements taken of intraoperative pulse rate and blood pressure. Patients receiving lignocaine demonstrated a lower pulse rate, and lower systolic and mean blood pressures than those receiving placebo, with significance in relation to clamp application and shunt removal (P < 0.05). It was particularly noticeable that patients receiving lignocaine demonstrated less intraoperative variation in pulse rate and blood pressure. Topical lignocaine stabilizes pulse rate and blood pressure during carotid endarterectomy.

Administration, Topical↗
PubMed1992

Endothelial cell seeding: a review.

The concept of endothelial cell seeding, designed to provide vascular grafts with a nonthrombogenic lining, has progressed from crude animal experiments during the past two decades to detailed in vitro functional studies using human cells. Although favorable results have been obtained in animal studies this has yet to be translated to humans, where current application of these techniques has been limited to a very few clinical trials. The history, current status and future directions are reviewed herein.

Animals↗
PubMed1992

An analysis of the concept of homesickness.

This report analyzes the concept of homesickness, using the pattern for concept analysis presented by Chinn and Jacobs. Concept analysis is a process used to better understand a concept that has been first identified through clinical practice. This concept analysis clarifies and defines the concept of homesickness, and distinguishes homesickness from other concepts, including separation anxiety, school phobia, translocation syndrome, and relocation effects. By carefully defining what homesickness is and what it is not, criteria have emerged so that other instances of similar characteristics can be appropriately labeled. In addition, arising from the literature review and criteria are research questions and nursing interventions.

Adaptation, Psychological↗
PubMed1992

Fibronectin binding to gelatin-impregnated Dacron (Gelseal) prostheses.

Endothelial cell adherence to uncoated gelatin-impregnated Dacron (Gelseal) is poor but can be significantly improved by precoating with a suitable basement membrane such as fibronectin. To assess the suitability of fibronectin-coated Gelseal for endothelial cell seeding, fibronectin binding to Gelseal and its dissociation kinetics were investigated. Fibronectin binding was quantified by radiolabeling human fibronectin with iodine 125, concentrations of 10, 25, 50, 150, and 250 micrograms/ml being used to coat Gelseal at 30, 60, and 90 min of incubation. The amount of fibronectin bound was directly proportional to the concentration used and increased with time of incubation (p < 0.05). However, the percentage attachment decreased with increasing concentration (p < 0.001). The number of molecules bound per centimeter squared of graft was calculated. In the first 30 min, 75% of bound fibronectin was lost after exposure to a flow rate of 200 ml/min in a pulsatile artificial circulation; thereafter, the fibronectin-Gelseal bond was stable for up to 2 h.

Blood Vessel Prosthesis↗
PubMed1991

Improvement of hepatitis B vaccine by the use of a new adjuvant.

Humoral and cellular immune responses of mice and guinea-pigs to hepatitis B virus surface antigen when alum-precipitated or administered with Syntex Adjuvant Formulation (SAF) were compared. Two doses of HBsAg in SAF were sufficient to elicit antibody responses, and using SAF the dose of antigen could be reduced to one-tenth of that required to elicit antibody responses by alum-adjuvanted HBsAg. The use of SAF increased and made more consistent the antibody responses in young mice and in strains of mice with inherited low responses to HBsAg. Cellular responses to HBsAg were more consistently observed when SAF was used than when alum was used. SAF increased the formation of IgG2a antibodies in mice except in the B10.M strain; antibodies of this isotype activate complement and act synergistically with antibody-dependent effector cells more efficiently than antibodies of other isotypes. If SAF proves acceptable for human use it could improve vaccines against hepatitis B virus.

Adjuvants, Immunologic↗
PubMed1991

Gambling and pathological gambling among university students.

Students from six colleges and universities in five states in the U.S. (New York, New Jersey, Oklahoma, Texas, and Nevada) were surveyed concerning their gambling behavior and the rate of pathological gambling. Type of gambling varied by state, with students in the northeast and Nevada gambling more than students in Oklahoma and Texas. Over 90% of males and 82% of females had gambled. One third of the males and 15% of females gambled once a week or more. Rates of pathological gambling ranged from 8% in New York to 4% in Nevada. The incidence of pathological gambling was high among males, Hispanics, Asians, and Italian-Americans (compared with among other whites), students with non-traffic arrests, those with parents who have gambling problems, and those who abuse alcohol and other drugs. Pathological gambling was only weakly correlated with age, religion, lower grade point average in school, overeating, living in neighborhoods that are "poorer than most," family income, and parental drug use. It was not correlated with academic year in college, marital status, parental occupation, parental alcohol, and bulimic behavior. The implications of the findings for further research and social policy are discussed.

Achievement↗
PubMed1991

In vitro adherence and kinetics studies of adult human endothelial cell seeded polytetrafluoroethylene and gelatin impregnated Dacron grafts.

Lining the luminal surface of small diameter vascular prostheses with living endothelial cells reduces thrombogenicity, decreases infection and improves patency. In vitro adherence and kinetics studies of adult human endothelial cell seeded Polytetrafluoroethylene (ePTFE) and Gelatin impregnated Dacron (Gelseal) were performed. Endothelial cell adherence on ePTFE and Gelseal coated with collagen IV, fibronectin and preclot matrices was compared. Untreated ePTFE and Gelseal were also used. Ten graft segments in each group coated with these matrices were incubated with radio-labelled adult human endothelial cells for 30, 60 and 90 min. Labelled endothelial cells seeded in supra-confluent densities on fibronectin coated ePTFE and Gelseal grafts were used for kinetic studies. Resultant endothelial cell monolayers were then exposed to varying shear stress at flow rates of 200 and 300 ml/min in an artificial flow circuit. Endothelial cell attachment to untreated grafts was poor and a suitable matrix significantly improved adherence with fibronectin and preclot but less so with collagen. A 30 min incubation was sufficient for optimum cell attachment. Cell adherence to ePTFE was significantly better than Gelseal. Scanning electron micrographs (SEM) of ePTFE showed preferential attachment to the nodes whilst on Gelseal, cells conformed to Dacron fibres at different levels and directions. Rapidly formed endothelial cell monolayers on ePTFE and Gelseal grafts resisted shear stress of flow with significant cell retention at 2 h. There was patchy coverage of both grafts with evidence of bridging of gaps between individual fibres in Gelseal.

Blood Vessel Prosthesis↗
PubMed1991

The Dieulafoy gastric malformation: an under-recognized cause of massive upper gastrointestinal haemorrhage.

The Dieulafoy gastric malformation is a rare cause of upper gastrointestinal haemorrhage. When no obvious bleeding lesion is seen at laparotomy this diagnosis ought to be considered. Three such cases were identified and treated with simple underrunning of the lesion with no mortality and minimal morbidity. Follow-up endoscopy in each patient showed complete healing of the lesion.

Aged↗