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Biomedical subjects

R Hall

Publications and source records attributed to R Hall.

At least 163 records · Page 9Linked to original sources
PubMed1994

Hepatitis C.

Hepatitis C is particularly prevalent among injecting drug users. The infection is asymptomatic over 50% of the time. A significant proportion of those infected ultimately develop cirrhosis or carcinoma of the liver or both. While prevention is the best form of treatment, alpha interferon may benefit up to 30% of those with active infection.

Hepatitis C↗
PubMed1993

Characterisation of a glutamine- and proline-rich protein (QP protein) from Theileria parva.

We have isolated a clone from a Theileria parva infected lymphocyte cDNA library which has the potential to encode a protein of 480 amino acids. This protein is particularly rich in glutamine and proline and has some short repeated amino acid motifs based on the sequences QPXP and QPXQ. We have called it the 'QP protein'. Southern blotting suggests that the QP protein gene is present as a single copy in the T. parva Muguga genome. Northern blotting revealed that the gene is transcribed in both schizonts and piroplasms. We have expressed part of the QP protein as a fusion with glutathione S-transferase in Escherichia coli and used this product to raise an anti-QP protein serum. Western blots of T. parva lysates using this serum showed a major polypeptide of approximately 100 kDa and two further polypeptides of approximately 67 and 72 kDa. Indirect immunofluorescence assays using the anti-QP protein serum on infected cells showed that the protein is associated with the schizont. The pattern of staining in the indirect immunofluorescence assays and the structure of the protein suggest that it is a component of the schizont membrane.

Amino Acid Sequence↗
PubMed1993

O6-alkyltransferase activity in normal and abnormal gastric mucosa.

The activity of the DNA repair enzyme O6-alkyltransferase has been studied in a series of stomachs with abnormal gastric mucosa and the activities found compared with those in normal stomachs. Enzyme activities found in stomachs with the macroscopic abnormalities of gastric ulcer, duodenal ulcer or gastric cancer were not significantly different from normal. In those stomachs where there was histological evidence of chronic atrophic gastritis or intestinal metaplasia however enzyme activities (mean 398 fmole/mg) were significantly higher than normal (mean activity 228 fmole/mg activity P < 0.001). We speculate that the conditions which stimulate these histological changes also give rise to induction of O6-alkyltransferase.

Adult↗
PubMed1993

Retroperitoneal haemorrhage: a dangerous complication of common femoral arterial puncture.

Three cases of retroperitoneal haemorrhage resulting from femoral artery catheterizations are reported. The blood tracked up the femoral sheath and was not accompanied by local clinical signs. Two of the patients died. A high index of suspicion, and an early recourse to ultrasound examination and surgical intervention, might have saved the lives of those patients who died.

Aged↗
PubMed1993

Radiofrequency catheter ablation for paroxysmal supraventricular tachycardia: a report of 135 procedures.

BACKGROUND: Paroxysmal Supraventricular Tachycardia (PSVT) is a common condition which until recently has been treated with anti-arrhythmic drugs or surgery. Radiofrequency (RF) catheter ablation is a new mode of treatment which provides a cure of this condition. AIMS: To present our early experience of RF catheter ablation for PSVT. METHODS: One hundred and thirty-five procedures were performed in 117 patients. The diagnostic study and therapeutic catheter ablation were performed as a combined electrophysiological procedure in 74 patients (63%). In 58 patients (50%), PSVT was due to Atrio-ventricular junctional (nodal) re-entrant tachycardia (AVJRT). Twenty-five of the 58 patients underwent a fast pathway ablation while 33 had ablation of their slow pathway. The mean number of radiofrequency pulses delivered was ten for a mean duration of 25 seconds. Radiofrequency ablation of accessory pathways was attempted in 58 patients; pathways were left-sided in 29 patients, postero-septal in 21, midseptal in five, Mahaim connection in two, antero-septal in one and right free wall in one patient. One patient with incessant automatic atrial tachycardia also underwent a successful RF ablation. RESULTS: Using RF ablation cure of PSVT was achieved in 90% of patients. Cure of AVJRT was achieved in 95% (55/58) of patients using either fast or slow pathway ablation. Only one patient required permanent pacemaker implantation for Mobitz type I AV block following fast pathway ablation. The overall success rate for ablation of accessory pathways was 85%. There is an operator learning curve for this procedure suggested by the fact that the success rate for accessory pathway ablation at first attempt was 63% in the first 29 patients and 93% in the remaining 29. There was no significant morbidity or mortality during or after the procedure. In a mean follow-up of nine months in the patients with successful ablation only two patients with AVJRT had a recurrence of documented PSVT. Both these patients had successful repeat RF ablation. Catheter ablation using radiofrequency energy is an effective and safe therapeutic option for patients with symptomatic PSVT.

Adult↗
PubMed1993

Aggregative adherence fimbria I expression in enteroaggregative Escherichia coli requires two unlinked plasmid regions.

Adherence to HEp-2 cells by many enteroaggregative Escherichia coli (EAggEC) strains is associated with the expression of flexible, bundle-forming fimbriae 2 to 3 nm in diameter, designated aggregative adherence fimbriae I (AAF/I). We have previously reported the molecular cloning and TnphoA mutagenesis of AAF/I genes from the large plasmid of prototype EAggEC strain 17-2 (J. P. Nataro, Y. Deng, D. R. Maneval, A. L. German, W. C. Martin, and M. M. Levine, Infect. Immun. 60:2297-2304, 1992). Here, we report that further mapping and subcloning of AAF/I regions suggest that expression of the fimbriae requires two separate plasmid regions (designated regions 1 and 2). Approximately 9 kb of DNA unnecessary for fimbrial expression separates the two regions; this intervening segment encodes the EAggEC heat-stable enterotoxin (EAST1). Neither region was capable of conferring aggregative HEp-2 adherence (AA) when cloned individually; when the two regions were cloned as a single fragment or when each was cloned into a different vector and introduced into the same E. coli HB101 cell, AA was restored. AA-positive constructs also expressed human erythrocyte hemagglutination, autoagglutination in broth cultures, and the production of AAF/I as detected by immunogold electron microscopy.

Amino Acid Sequence↗
PubMed1993

Aldehyde disinfectants and health in endoscopy units. British Society of Gastroenterology Endoscopy Committee.

Summary of main recommendations(1) Glutaraldehyde, used in most endoscopy units in the United Kingdom for the disinfection of flexible gastrointestinal endoscopes, is a toxic substance being an irritant and a sensitiser; symptoms associated with glutaraldehyde exposure are common among staff working in endoscopy units.(2) The Control of Substances Hazardous to Health Regulations 1988 (COSHH) obliges the employer to make a systematic assessment of risk to staff of exposure to glutaraldehyde and institute measures to deal effectively with exposure.(3) At present glutaraldehyde remains the first line agent for the disinfection of flexible gastrointestinal endoscopes. Other agents are being developed; a standard means of assessment for flexible endoscope disinfectants should be devised.(4) Equipment and accessories that are heat stable should be sterilised by autoclaving; disposable accessories should be used wherever possible.(5) Flexible gastrointestinal endoscopes should be disinfected within automated washer/disinfectors; trays, bowls or buckets for this purpose are unacceptable.(6) Local exhaust ventilation must be used to control glutaraldehyde vapour. Extracted air may be discharged direct to the atmosphere or passed over special absorbent filters and recirculated. Such control measures must be regularly tested and records retained.(7) Endoscope cleaning and disinfection should be carried out in a room dedicated to the purpose, equipped with control measures to maintain the concentration of glutaraldehyde vapour at a level certainly below the current occupational exposure standard of 0.2 ppm and preferably below the commonly used working limit of 0.1 ppm. Sites other than the endoscopy unit where endoscopy is regularly performed, such as the radiology department, should have their own fully equipped cleaning and disinfection room.(8) COSHH limits the use of personal protective equipment to those situations where other measures cannot adequately control exposure. Such equipment includes nitrile rubber gloves, apron, chemical grade eye protection, and respiratory protective equipment for organic vapours.(9) Monitoring of atmospheric levels of glutaraldehyde should be performed by a competent person such as an occupational hygienist; the currently preferred method of sampling uses a filtration technique, the commercially available meters being less reliable.(10) Health surveillance of staff is mandatory; occupational health records must be retained for 30 years.(11) Endoscopy staff must be informed of the risks of exposure to glutaraldehyde and trained in safe methods of its control. Only staff who have completed such an education and training programme should be allowed to disinfect endoscopes.(12) The unsafe use of glutaraldehyde has significant health and legal consequences; the safe use of glutaraldehyde may have revenue consequences that contribute significantly to the cost of gastrointestinal endoscopy.

Aldehydes↗
PubMed1993

DNA damage in the stomach after vagotomy measured by 32P-postlabelling.

This study analysed gastric mucosal DNA by 32P-postlabelling in a series of patients who have had previous vagotomy for benign peptic ulcer disease. DNA adduct levels were found to be significantly higher in patients who had had previous truncal vagotomy than in those who had had previous highly selective vagotomy (p < 0.001). Intragastric bile concentrations were also considerably higher in patients after truncal vagotomy but there was no correlation between intragastric bile concentrations and DNA adduct levels. These results suggest that, although duodenogastric reflux may be a cause of gastric mucosal DNA damage in the stomach after vagotomy, measurement of total intragastric bile does not accurately reflect genotoxic insult.

Adult↗
PubMed1993

Apolipoprotein (a) concentrations and susceptibility to coronary artery disease in patients with peripheral vascular disease.

OBJECTIVE: To investigate the relation between apolipoprotein(a) concentrations and angiographically defined coronary artery disease in patients with atheromatous peripheral vascular disease. DESIGN: 40 consecutive patients were recruited at the time of admission for peripheral vascular surgery. All underwent clinical assessment and coronary arteriography. Apolipoprotein(a) concentrations were measured by an immunoradiometric assay. SETTING: Tertiary referral centre. SUBJECTS: Patients requiring surgical intervention for large vessel peripheral vascular disease. MAIN OUTCOME MEASURES: Presence or absence and severity and distribution of angiographically defined coronary artery disease. Measurement of circulating contractions of apolipoprotein(a) and other lipid indices. RESULTS: Coronary artery disease was absent in 11 patients (group 1), mild to moderate in 12 (group 2), and severe in 17 (group 3). The distribution of peripheral vascular disease and of standard lipid indices was similar in these three groups of patients. There was a significant difference in apolipoprotein(a) concentrations between the three groups, with concentrations progressively increasing with the severity of coronary artery disease (mean (95% confidence interval): group 1, 112 U/1 (52 to 242); group 2, 214 U/1 (129 to 355); group 3, 537 U/1 (271 to 1064) (analysis of variance p < 0.005). The prevalence of coronary artery disease was increased 7.4 fold in patients with apolipoprotein(a) concentrations that were greater than the cohort median (206 U/1) (p < 0.01). CONCLUSIONS: The results show an association between apolipoprotein(a) concentrations and angiographically defined coronary artery disease in patients with large vessel peripheral vascular disease. The findings imply differences in the pathogenesis of coronary and peripheral atheroma and suggest that the measurement of apolipoprotein(a) may prove a useful additional tool in the risk factor assessment of patients undergoing peripheral vascular surgery.

Aged↗