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Biomedical subjects

J Thompson

Publications and source records attributed to J Thompson.

At least 523 records · Page 29Linked to original sources
PubMed1990

Surgery offers no more than medical treatment in the management of transient ischaemic attack.

This paper debates the motion that 'Surgery offers no more than medical treatment in the management of transient ischaemic attack' (TIA). The arguments in support of this motion are that surgical treatment has a high morbidity and mortality, and that even the investigation of patients by angiography prior to surgery entails a risk of stroke; that TIA is a marker of generalised vascular disease, and that medical treatment can reduce the incidence of stroke after TIA. The counter arguments are that TIA is associated with an increased risk of stroke and this risk can be reduced by surgery; that recent surgical results show an acceptable complication rate, and that modern methods of investigation permit accurate non-invasive assessment of patients at risk of stroke.

Aspirin↗
PubMed1990

The elusive colonic malignancy. A need for definitive preoperative localization.

Colonoscopy with biopsy is the standard of practice for the diagnosis of colonic malignancies. Unfortunately, the inability of endoscopy to obtain precise distance measurements from the anal verge can make localization of lesions at operation difficult. For this reason, preoperative barium enema or intraoperative colonoscopy have been advocated to further pinpoint the sites of those lesions not thought to be easily located at operation. Five patients are presented in whom malignant lesions of the colon were diagnosed and verified histologically, but were later undetectable at operation or subsequent colonoscopic examinations. Four of these patients underwent laparotomy and three received colon resections. None of these patients' tumors were identified during intraoperative colonoscopy, in the resected bowel on pathologic examination, or on follow-up colonoscopy. A fifth patient is presented who spontaneously passed a polyp containing invasive adenocarcinoma, but multiple colonoscopic examinations have failed to identify the site of the lesion. To date, none of these tumors have recurred with periods of follow-up ranging from 6 months to 2 years. These patients demonstrate a poorly documented and little understood aspect of the behavior of colonic malignancies, i.e., the ability to spontaneously regress or slough from the bowel wall. Based on these instances, localization of potentially malignant colon lesions is recommended with submucosal dye injections at initial endoscopy or with colonoscopy in the operating room immediately prior to operation.

Aged↗
PubMed1990

Particle release from haemodialysers.

Release of particles from eight makes of hollow-fibre and one make of flatplate dialyser have been studied, and the relationship between rinsing volume and particles recovered established. In a supplementary study the effect on the number of particles released was assessed when striking the dialyser header during priming. Particle size distribution indicated that the majority of the particles recovered were less than 5 microns in diameter. A separate analysis of the particles in the 5-30 micron size range showed two different patterns of particle release. In the dialysers containing ethylene vinyl acetate (EVAL) or Cellulate the number of particles recovered were within the 95% range of the particles in the rinsing fluid and did not alter with increasing rinsing volume. In the dialysers containing Cuprophan and Hemophan the initial particle numbers were higher but fell rapidly up to a 450 ml rinse volume; increasing the rinse volume to 1050 ml did not alter particle recovery. Analysis of variance failed to differentiate between individual dialysers. Striking the header during priming resulted in a transient statistically nonsignificant increase in the number of particles recovered.

Biocompatible Materials↗
PubMed1990

Histamine, histamine formation capacity and gastrin in cysteamine-induced peptic ulcer.

We attempted to induce chronic peptic ulcer in the rat by injection of consecutive doses of cysteamine. We investigated the incidence of peptic ulceration and measured gastric mucosal histamine, histamine formation capacity (HFC), plasma gastrin and tissue (oesophagus, duodenum, liver and lung) histamine in rats 1, 7, 14, 21, and 28 days after injection of cysteamine-HCl (300 mg/kg s.c. and 100 mg/kg 8 h later). Saline injections were used in control rats. After 24 h all rats given cysteamine had duodenal ulcers and the ulcer incidences after 7 and 14 days were 60 and 40%, respectively. After Day 21 no ulcers were found. Microscopy revealed ulcer healing seen as epithelialized scars from Day 14 onwards. A rising incidence of gastric metaplasia of the duodenal mucosa was noted from Day 7 after cysteamine treatment, which may have pathophysiological significance. Gastric mucosal histamine was higher and plasma gastrin was lower after 24 h compared with controls and values obtained later in the study. Rats with duodenal ulceration had significantly higher gastric mucosal histamine than those without lesions and control rats. A direct relationship was found between plasma gastrin and HFC in rats given cysteamine. A small but significant increase in histamine content of the liver was also observed after 24 h. No significant changes were found in other tissue specimens. Thus, a rise in gastric histamine is associated with duodenal ulcers in this model.

Animals↗
PubMed1990

Playing at work.

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Child Development↗
PubMed1990

Eczema.

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Child↗
PubMed1990

Particle spallation and plasticiser (DEHP) release from extracorporeal circuit tubing materials.

Particle spallation and plasticiser (DEHP) release from medical grade polyvinylchloride (PVC), co-extruded PVC-polyurethane (PIVIPOL)R and an experimentally produced co-extruded PVC-ethylene vinyl acetate (EVA) has been studied when used with manually occluded and self-occluding peristaltic pumps over a six hour pumping period. The shore hardness of the tubings studied were similar but the luminal coating thickness differed (0.2 mm polyurethane, 0.99 mm EVA). The pattern of particle release was similar for all materials on the pump type used with the majority of particles released being less than 5 microns in diameter. The number of particles greater than 5 microns released was independent of the tubing material but depended on the pump type. Particle release with self-occluding pumps was significantly higher (p less than 0.001) than for the manually occluded pump. Scanning electron microscopy indicated that the particles released originate from the repeated compression and flexing of the insert during pumping which leads to material structural failure. The higher release observed in the case of self-occluding pumps is suggestive of over-occlusion by the springs utilised in the pump. DEHP release (ppm) over a six hour period while perfused at 300 ml/min was significantly reduced for co-extruded tubing (0.56 +/- 0.05 mg (PVC-polyurethane) and 0.12 +/- 0.04 mg (PVC-EVA) compared with PVC (0.74 +/- 0.05 mg).

Diethylhexyl Phthalate↗
PubMed1989

Sequence and characteristics of IS900, an insertion element identified in a human Crohn's disease isolate of Mycobacterium paratuberculosis.

The complete sequence of an insertion element IS900 in Mycobacterium paratuberculosis is reported. This is the first characterised example of a mycobacterial insertion element. IS900 consists of 1451bp of which 66% is G + C. It lacks terminal inverted and direct repeats, characteristic of Escherichia coli insertion elements but shows a degree of target sequence specificity. A single open reading frame (ORF 1197) coding for 399 amino acids is predicted. This amino acid sequence, and to a lesser extent the nucleotide sequence, show significant homologies to IS110, an insertion element of Streptomyces coelicolor A3(2). It is proposed that IS900, IS110, and similar insertion elements recently identified in disease isolates of Mycobacterium avium are members of a phylogenetically related family. IS900 will provide highly specific markers for the precise identification of Mycobacterium paratuberculosis, useful in defining its relationship to animal and human diseases.

Amino Acid Sequence↗
PubMed1989

Procoagulant activity of endocardial vegetations and blood monocytes in rabbits with Streptococcus sanguis endocarditis.

To investigate activation of the coagulation system in bacterial endocarditis, we determined the procoagulant activity of blood monocytes isolated from rabbits with Streptococcus sanguis-infected or sterile catheter-induced endocardial vegetations. This activity was determined directly after isolation from the peripheral blood and after stimulation in vitro by either endotoxin or by phagocytosis of S. sanguis. The procoagulant activity of the vegetations of these rabbits was also determined. The procoagulant activity of blood monocytes of rabbits with S. sanguis endocarditis was found to be similar to the activity of monocytes of rabbits with sterile vegetations, both at the time of isolation and after stimulation in vitro by exposure to endotoxin or phagocytosis of bacteria. The procoagulant activity of infected vegetations was significantly higher than that of sterile vegetations. We conclude that in bacterial endocarditis the coagulation system is activated locally at the site of the vegetation. Triggering probably occurs by thromboplastin generated by monocytes activated by phagocytosis of bacteria on the vegetational surface.

Animals↗
PubMed1989

Immunisation.

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Adolescent↗
PubMed1989

N5-(L-1-carboxyethyl)-L-ornithine:NADP+ oxidoreductase from Streptococcus lactis. Purification and partial characterization.

N5-(L-1-Carboxyethyl)-L-ornithine:NADP+ oxidoreductase (EC 1.5.1.-) from Streptococcus lactis K1 has been purified 8,000-fold to homogeneity. The NADPH-dependent enzyme mediates the reductive condensation between pyruvic acid and the delta- or epsilon-amino groups of L-ornithine and L-lysine to form N5-(L-1-carboxyethyl)-L-ornithine and N6-(L-1-carboxyethyl)-L-lysine, respectively. The five-step purification procedure involves ion-exchange (DE52 and phosphocellulose P-11), gel filtration (Ultrogel AcA 44), and affinity chromatography (2',5'-ADP-Sepharose 4B). Approximately 100-200 micrograms of purified enzyme of specific activity 40 units/mg were obtained from 60 g of cells, wet weight. Anionic polyacrylamide gel electrophoresis revealed a single enzymatically active protein band, whereas three species (pI 4.8-5.1) were detected by analytical electrofocusing. The purified enzyme is active over a broad pH range of 6.5-9.0 and is stable to heating at 50 degrees C for 10 min. Substrate Km values were determined to be: NADPH, 6.6 microM; pyruvate, 150 microM; ornithine, 3.3 mM; and lysine, 18.2 mM. The oxidoreductase has a relative molecular mass (Mr = 150,000) as estimated by high pressure liquid chromatography exclusion chromatography and by polyacrylamide gradient gel electrophoresis. Conventional gel filtration indicated an Mr = 78,000, and a single protein band of Mr = 38,000 was revealed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The enzyme is composed of identical subunits of Mr = 38,000, which may associate to yield both dimeric and tetrameric forms. Polyclonal antibody to the purified protein inhibited enzyme activity. The amino acid composition of the enzyme is reported, and the sequence of the first 37 amino acids from the NH2 terminus has been determined by stepwise Edman degradation.

Amino Acid Sequence↗
PubMed1989

DNA probes demonstrate a single highly conserved strain of Mycobacterium avium infecting AIDS patients.

Strains of the Mycobacterium avium intracellulare complex (MAIC) have become important colonisers of patients with acquired immunodeficiency syndrome (AIDS). Restriction fragment length polymorphisms were used to study the DNA from 88 MAIC isolates, including 51 derived from 47 AIDS patients. MAIC isolates from 33 of 45 AIDS patients were identical at the molecular level and distinct from the mycobacteria isolated from the stools of healthy subjects. The study also showed that serotyping correlates poorly with the genetic identity of these organisms. Mycobacterium paratuberculosis, which has been implicated in Crohn's disease, was not identified in any of the cultures studied.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Xenon computed tomography measuring cerebral blood flow in the determination of brain death in children.

Local cerebral blood flow was measured using stable xenon computed tomography in 21 children, 10 of whom were clinically brain dead and had electrocerebral silence as determined by electroencephalography. Radioisotopic brain scanning in 9 patients showed no visible cerebral activity in all patients and minimal residual sagittal sinus activity in 4. In this population, mean cerebral blood flow as measured by xenon computed tomography was 1.3 +/- 1.6 ml/min/100 gm. Respiratory support was discontinued in 8 patients, and 2 patients had cardiac arrest. Eleven profoundly comatose children who did not meet all clinical criteria for brain death and who had markedly suppressed but not isoelectric electroencephalograms had an average cerebral blood flow of 33.5 +/- 16.3 ml/min/100 gm. There was no difference in cerebral blood flow in those children who survived (30.4 +/- 16.3 ml/min/100 gm; n = 7) compared with those who died acutely (38.3 +/- 14.3 ml/min/100 gm; n = 4). Two patients who survived had average total flows of only 11.8 and 12.1 ml/min/100 gm. Our findings suggest that in infants and children older than 1 month, (1) cerebral blood flow below approximately 10 ml/min/100 gm is consistent with clinical brain death, (2) cerebral blood flow of less than 5 ml/min/100 gm is consistent with no flow as demonstrated by radionuclide techniques, and (3) flow of more than 10 to 15 ml/min/100 gm is associated with the potential for survival.

Brain Death↗
PubMed1989

Quantitation of HIV-1 RNA in blood cells of ARC and AIDS patients.

Peripheral blood mononuclear cells from HIV-1-infected persons were mixed with 5 M guanidine thiocyanate, and HIV-1-specific probes were hybridized with target RNA directly in the lysate. No RNA purification was needed. Hybrids were purified by repeated capture on superparamagnetic beads coated with oligo(dT) in a device-assisted format, a procedure termed "reversible target capture." Blood mononuclear cells from 70 ARC and AIDS patients were examined and found to have an average of 1.8 x 10(5) molecules of HIV-1 RNA per 2 x 10(6) cells.

AIDS-Related Complex↗