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Biomedical subjects

A J Collins

Publications and source records attributed to A J Collins.

At least 55 records · Page 3Linked to original sources
PubMed1995

A comparison of coronary angioplasty and coronary artery bypass grafting outcomes in chronic dialysis patients.

The objective of this study was to compare the outcomes of angina, myocardial infarction (MI), cardiac death, and all-cause death following percutaneous transluminal coronary angioplasty (PTCA) or coronary artery bypass grafting (CABG). The study design was based on retrospective, nonrandomized analysis and was set in referral teaching hospitals and community hospitals. Eighty-four chronic dialysis patients with symptomatic coronary artery disease without prior revascularization were included in the study. Twenty-four patients underwent PTCA of one or more vessels, and 60 patients underwent CABG. Recurrence of angina, MI, cardiac death, and all-cause death following revascularization as well as the number of inpatient days preprocedure and postprocedure were recorded. The two patient groups were comparable in terms of age, sex, history of MI, left ventricular mass and function, and angina severity. Diabetes mellitus was more prevalent in the PTCA group. The CABG group had more severe coronary artery disease. The 2-year survival rate of the CABG patients (66%; 95% confidence interval = 53.79) did not differ from that of the PTCA patients (51%; 95% confidence interval = 27.65). Thirteen PTCA patients were restudied 106 +/- 108 days after recurrence of angina; nine (69%) of these patients were found to have angiographic restenosis. The postprocedure risk of angina and the combined endpoints of angina, MI, and cardiovascular death were significantly greater following PTCA than CABG. Percutaneous transluminal coronary angioplasty was the only consistent predictor of outcomes; the adjusted relative risks (compared with CABG) of postprocedure angina and combined endpoints were 16.4 and 10.2, respectively, and were several-fold higher than the unadjusted risks. We conclude that in chronic dialysis patients with symptomatic coronary disease, patients undergoing PTCA have a higher risk of subsequent angina and combined angina, MI, and cardiovascular death than those undergoing CABG. The optimal approach to coronary revascularization in this patient population remains to be determined.

Adult↗
PubMed1995

Pharmacologic profile of diaspirin cross-linked hemoglobin in hemodialysis patients.

Various hemoglobin compounds have been evaluated as potential oxygen-carrying, blood volume expanders, but toxicity has prevented clinical application. Diaspirin cross-linked hemoglobin (DCLHb) represents a modified hemoglobin compound that is derived from human red blood cells and maintained in a tetrameric configuration by cross-linkages between the two alpha chains of the hemoglobin molecule. In a randomized, placebo-controlled, single-blind, cross-over trial, DCLHb's safety and pharmacologic parameters were evaluated in 18 subjects receiving chronic hemodialytic therapy. A 30-minute infusion of 25, 50, or 100 mg/kg DCLHb or placebo was given at the start of routine hemodialysis. One week later, the alternate treatment (placebo or DCLHb) was administered. Maximum plasma hemoglobin concentrations and terminal half-life values were calculated for each dosage group. Dialysate was collected and assayed for hemoglobin. Changes in systolic and diastolic blood pressure from baseline and the volume of hypertonic saline administered for treatment of hypotension during hemodialysis were measured. The maximum plasma hemoglobin concentrations increased with DCLHb dose and occurred at the end of DCLHb infusion. The mean (+/- SD) terminal half-life ranged from 2.1 +/- 1.0 hours in the 25 mg/kg DCLHb group to 4.3 +/- 1.4 hours in the 100 mg/kg group, but did not differ significantly between groups. Mean baseline plasma hemoglobin corrected areas under the plasma concentration-time curves increased from 89 to 1,136 mg/hr/dL across the fourfold dose range. Diaspirin cross-linked hemoglobin was not dialyzable as none was detected in dialysate. The maximum increase in systolic blood pressure from baseline increased significantly with DCLHb dose compared with placebo (P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Compulsory random drug testing of prisoners in England and Wales: design flaws in the system.

The Home Office has recently introduced compulsory testing of prisoners in England and Wales for drug abuse. From 1996 all prisons in the UK will be involved. Urine samples from approximately 10% of the prison population will be collected each month. The method of drug analysis selected by the Home Office is fast and economical but readily prone to interference from common substances giving false results. An elaborate procedure has therefore been evolved including a rigorous personal search of the prisoner to prevent sample adulteration. The definitive test gas chromotography - mass spectrometry (GC-MS), is more expensive but is resistant to sample adulteration, and currently all positive samples are confirmed by this method. In view of the proportion of samples that have tested positive, the extent of the unknown number of false negatives, and the possible rejection of the collection protocol by prisoners, savings could be made if the method of analysis employed in the first instance was GC-MS. This paper illustrates the inaccuracies produced in an assay technique similar to that used by the Home Office when urine is contaminated by simple, commonly available substances.

Journal Article↗
PubMed1995

Characteristics of ulcers of the small bowel induced by non-steroidal anti-inflammatory drugs in the rat: implications for clinical practice.

Small bowel ulcers were created in the rat after the oral administration of non-steroidal anti-inflammatory drugs (NSAIDs). Of the six NSAIDs tested, indomethacin and diclofenac alone were associated with such damage which did not occur in a simple dose-related fashion. Bacteria were observed by electron microscopy in an active state of division in the base of the ulcers. When grown aerobically these were shown to be strains of Escherichia coli and Proteus mirabilis. Anatomically, NSAID-induced ulcers were found throughout the length of the bowel although more abundant in the proximal half. In vivo and in vitro sensitivity to antibiotics suggested that in addition to the bacteria identified, anaerobic beta-lactamase-producing organisms also have an important role in ulcer production in this model. This rat model of NSAID-induced gut toxicity is discussed in relation to the human situation, particularly for patients who take NSAIDs and who have an iron-deficiency anaemia and blood in their faeces, but no lesions in either the upper or lower bowel.

Animals↗
PubMed1995

Pyomyositis: characteristics at CT and MR imaging.

PURPOSE: To establish imaging criteria for pyomyositis (PM). MATERIALS AND METHODS: Twenty-seven computed tomographic (CT) scans and 11 magnetic resonance (MR) images obtained in 32 patients with PM were reviewed. Images in 10 patients with PM and 16 with soft-tissue masses were evaluated blindly. RESULTS: At CT, all 27 patients had muscle enlargement with heterogeneous attenuation; 26 patients had a focal fluid collection, with rim enhancement in all 18 patients who underwent contrast material-enhanced CT. Twenty-four patients had cellulitis. At MR imaging, all 11 patients had both a subtle increase in signal intensity in the affected muscle(s) on T1-weighted images and cellulitis. Nine patients had a focal fluid collection, which had high signal intensity and a hypointense rim on T2-weighted images. In six patients, a rim of increased signal intensity was seen around the collection on T1-weighted images. Six gadolinium-enhanced examinations demonstrated rim enhancement. Eight patients had fluid in the distal joint. All patients with PM were correctly identified when evaluated with the control subjects; however, there were four false-positive results. CONCLUSION: CT and MR imaging can help characterize changes that are suspicious for PM.

Adolescent↗
PubMed1994

Selective regulation of epithelial gene expression in rabbit Peyer's patch tissue.

The physiological mechanisms that regulate epithelial gene expression during enterocyte migration and differentiation are still poorly understood. The present study has used a combination of quantitative in situ hybridisation, immunohistochemistry and enzyme cytochemistry to examine epithelial cell differentiation in rabbit small intestine. We have measured and compared the levels of mRNA and enzyme activity of the enterocyte brush border markers alkaline phosphatase, amino-peptidase N and lactase in normal villus epithelia and in epithelial cells exposed directly to the Peyer's patch immune environment. All three genes appeared to be expressed in parallel, but in each epithelial population examined, the pattern of gene expression was different. The level of these mRNAs was markedly reduced in Peyer's patch-associated epithelia, this being most pronounced in the follicle-associated epithelium, compared with normal villi. The activities of alkaline phosphatase and aminopeptidase N approximated the expression of their genes, whereas additional post-transcriptional events were shown to clearly contribute to the level of lactase activity in these tissues. These findings demonstrate that the reduced brush border hydrolase activity in Peyer's patch tissue that has been observed previously, is due to a down-regulation of epithelial gene expression in this location. These observations have been used to discuss epithelial differentiation in Peyer's patch tissue and the possible role of local immune factors in regulating such events.

Alkaline Phosphatase↗
PubMed1994

Urea index and other predictors of hemodialysis patient survival.

The mortality of dialysis patients in the United States has been a concern since the US Renal Data System 1989 report, which showed a lower survival rate in the United States compared with Europe. The differences were thought to be multifactorial, including case mix, malnutrition, and adequacy of dialysis. We reviewed the Regional Kidney Disease Program's 1976 to 1989 database for the pattern of co-morbidity, dialysis therapy, and low serum albumin in 1,082 nondiabetic and 691 diabetic patients followed to September 15, 1991. The number of patients over 60 years of age has increased by 15% to 20% per year since 1982. The primary renal diagnoses for nondiabetic patients have shifted from 26% glomerulonephritis, 18% vascular and hypertension, and 15% interstitial kidney disease cases during the period from 1976 to 1982 to 19% glomerulonephritis, 35% vascular and hypertension, and 10% interstitial disease cases during the period from 1986 to 1989. Co-morbidity as single and multiple conditions has increased from 66% to 85% in diabetic patients and from 57% to 66% in nondiabetic patients. The number of patients with two or more co-morbid conditions has increased 1.5-fold in nondiabetic patients and twofold in diabetic patients from the 1976 to 1982 period to the 1986 to 1989 period. Urea index and albumin were determined for these patients and were averaged as a risk factor. A Cox regression analysis was used to determine the relative risk of death of such characteristics as age, renal diagnosis, co-morbidity, urea index (KT/V), and albumin in nondiabetic and diabetic patients. Urea index was divided into ranges of less than 1.0 (mean, 0.9), 1.0 to less than 1.2, 1.2 to less than 1.4, and > or = 1.4 (mean, 1.6). The relative risk of death in nondiabetic patients was 0.65 (P = 0.0012) for KT/V 1.2 to less than 1.4 and 0.67 (P = 0.0029) for KT/V > or = 1.4 (mean, 1.6) compared with 1.0 to less than 1.2 as the baseline. In the diabetic patients, the relative risk of death was 0.70 (P = 0.009) for KT/V 1.2 to less than 1.4 and 0.59 (P = 0.0001) for KT/V > or = 1.4 (mean, 1.6) compared with 1.0 to less than 1.2. In the diabetic patients, KT/V > or = 1.4 also was significantly different from 1.2 to less than 1.4 as it impacted on death rates.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1994

Influence of co-morbidity on mortality and morbidity in patients treated with hemodialysis.

It has been established that mortality among US end-stage renal disease patients is higher than in many other developed countries. The explanation for this apparent difference in outcome results has caused considerable concern. The explanations for this difference are complex and could include differences in case mix as well as indices of severity of illness. To evaluate potential patient-based explanations for these discrepancies, we have evaluated existing reports as well as the available database at the Regional Kidney Disease Program at Hennepin County Medical Center, with particular emphasis on medical co-morbidity present in US end-stage renal disease patients. These data indicate that increasing age, a greater prevalence of diabetes mellitus patients, and a greater proportion of end-stage renal disease patients with complex medical co-morbidity contribute to the higher mortality seen in US patients receiving hemodialytic therapies.

Comorbidity↗
PubMed1993

Genetic regulation of enterocyte function: a quantitative in situ hybridisation study of lactase-phlorizin hydrolase and Na(+)-glucose cotransporter mRNAs in rabbit small intestine.

The enterocyte undergoes sequential changes in its structure and function as it migrates rapidly from the small intestinal crypts to the villus tip. The mechanisms by which these changes are regulated "in tune" with ontogenic and dietary changes in the luminal environment are currently under investigation. This study has employed oligonucleotide probes to follow the expression of the lactase-phlorizin hydrolase (LPH) and Na(+)-glucose cotransporter (SGLT1) genes in rabbit small intestine using quantitative in situ hybridisation histochemistry. The profiles of LPH mRNA and SGLT1 mRNA accumulation along the crypt-villus axis were found to be very similar. Although mRNA was undetectable in the crypt. LPH and SGLT1 mRNA levels rose rapidly at the crypt-villus junction, reaching a maximum between 210 microns and 330 microns above this point. Further up the villus the level of mRNAs declined. SGLT1 mRNA was present in all small intestinal segments (duodenum, jejunum and ileum), whereas LPH mRNA was absent from the ileum. LPH activity rose and fell in conjunction with mRNA, but SGLT1 activity was greatest at the villus tip where mRNA levels were considerably reduced. These data have been used to discuss the genetic regulation of enterocyte differentiation and function.

Animals↗
PubMed1993

Posterior interosseous nerve compression due to an enlarged bicipital bursa confirmed by MRI.

Posterior interosseous nerve compression is a well-described clinical entity with many aetiologies. Fewer than 12 documented cases of the condition due to an enlarged bicipital bursa exist in the literature. We describe a case in which magnetic resonance imaging (MRI) was used in the preoperative assessment of a mass in the proximal forearm with a clinical diagnosis of partial posterior interosseous nerve compression.

Adult↗
PubMed1992

Structured approach to the investigation of anaemia in patients with rheumatoid arthritis.

A group of 28 patients with rheumatoid arthritis who were severely anaemic were investigated for iron deficiency. On the basis of bone marrow studies, the patients were divided into two groups, those with and those without signs of stainable iron in the marrow. This grouping did not distinguish between the severity of their rheumatoid arthritis measured by clinical parameters. Measurement of the red cell count and biochemical parameters in the peripheral blood showed a statistical difference in red cell size, haemoglobin content, and iron binding capacity between the two groups. The statistical variation of these parameters, however, did not allow these measurements to predict bone marrow iron deficiency in any subject. Investigation of the upper gastrointestinal tract by endoscopy showed that acute macroscopic lesions were infrequently associated with anaemia. It was concluded that anaemia in association with rheumatoid arthritis may mimic iron deficiency anaemia, and that simple investigations of the peripheral blood do not accurately show the iron status of the reticuloendothelial system in the presence of a chronic inflammatory disease. For the investigation of severe anaemia in rheumatoid arthritis, bone marrow assessment of iron status should be performed as the initial investigation. In addition, iron deficient patients require investigation of the lower and the upper gastrointestinal tract.

Administration, Oral↗
PubMed1991

The comparative pharmacokinetics of acemetacin in young subjects and elderly patients.

Single and multiple dose pharmacokinetics of acemetacin in 10 young healthy subjects and 10 elderly patients with osteoarthritis were studied. Peak plasma concentrations of acemetacin and its metabolite, indomethacin, were found between 2.4 and 4 h after an oral dose of the drug. After dosing to steady state (7 days), the mean plasma elimination half-life for acemetacin was 1.1 h and 1.0 h, and for indomethacin 7.1 h and 7.2 h in the young and elderly groups respectively. Statistical analysis of tmax, AUC, plasma t1/2 and residual drug concentrations for acemetacin or indomethacin revealed no significant differences (P greater than 0.05) between young subjects and elderly patients after acute or chronic dosing. The results suggest that drug accumulation did not occur in the elderly subjects over the time period studied and that, on pharmacokinetic grounds, dose adjustment in the elderly is unlikely to be required.

Adult↗
PubMed1991

Renal failure in disasters.

This article focuses on the steps that both search and rescue teams and advanced medical teams may use to reduce the potential for acute renal failure from crush injury in disasters and provides guidelines for the deployment of dialytic resources in the disaster setting.

Acute Kidney Injury↗