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Biomedical subjects

S Mitchell

Publications and source records attributed to S Mitchell.

At least 163 records · Page 9Linked to original sources
PubMed1990

Cosmetic results of early breast carcinoma treated with wide local excision, external beam radiotherapy and iridium-192 boost.

Cosmetic results of 80 patients with axillary lymph node negative or unknown T1 and T2 carcinoma of the breast who were treated with wide local excision, external beam radiotherapy and iridium-192 boost, were evaluated by the patient and the radiotherapist at 18-36 months. Their overall cosmetic results were assessed as good, very good or excellent by 80% of the patients. The radiotherapist's assessment was similar but in general the patients score was more favourable. After a follow-up of 24-72 months recurrence was found in only one patient at 40 months. This approach offers good cosmesis with low local recurrence rates in early breast carcinoma patients with negative axillary lymph nodes.

Adult↗
PubMed1989

Computerized electrocardiographic interpretation: an analysis of clinical utility in 5110 electrocardiograms.

This study describes the initial experience with a computerized electrocardiographic interpretation system in a teaching hospital. The sensitivity and specificity of the 13,375 diagnostic statements that were used to describe the first 5110 electrocardiograms were analysed to determine the predictive accuracy of computerized electrocardiographic interpretation. Reviewing cardiologists inserted 1320 statements, deleted 1792 statements and modified 484 computerized statements. The over-all sensitivity and specificity (and standard error [SE]) of computerized diagnosis was 90.1% +/- 0.3% and 89.6% +/- 0.2%, respectively, with an over-all positive predictive accuracy (+/- SE) of 87.1% +/- 0.3% and a negative predictive accuracy (+/- SE) of 92.2% +/- 0.2%. Sensitivity and specificity were lowest for the category of ST-T wave changes (83.1% +/- 0.8% and 84.1% +/- 0.7%, respectively) and were highest for the category of sinus rhythm (96.6% +/- 0.3% and 97.0% +/- 0.6%, respectively). The positive predictive accuracy of computerized diagnosis was lowest for the category of hypertrophies (74.2% +/- 1.0%) and was highest for the category of sinus rhythm (99.5% +/- 0.1%), while for the category of myocardial infarctions it was 87.6% +/- 0.8%. The negative predictive accuracy ranged from 96.7% +/- 0.3% for the category of hypertrophies to 81.8% +/- 1.3% for the category of sinus rhythm. We conclude that the computerized analysis of electrocardiograms has a satisfactory predictive accuracy when used in an environment with a high prevalence of abnormalities. Electrocardiograms that are classified as normal by computerized analysis may not require checking; however, all electrocardiograms with abnormalities should be interpreted by a competent electrocardiographer.

Cardiology↗
PubMed1989

Ibotenate-induced total septal lesions reduce resistance to extinction but spare the partial reinforcement extinction effect in the rat.

Rats were given sham operations, vehicle injections, or injections of the axon-sparing excitotoxin ibotenic acid into the septum. In Experiment 1, behavioural testing commenced 16 days after the operation; in Experiment 2 behavioural testing commenced following testing on another task, 31 days after the operation. The rats were trained to run in an alley for food reward given on every trial (Continuous Reinforcement, CR) or on a random fifty percent of trials (Partial Reinforcement, PR) and then the running response was extinguished. All the experimental groups showed the normal partial reinforcement extinction effect (PREE) in that PR-trained animals were significantly more resistant to extinction than CR-trained animals. However the rats with ibotenic acid lesions also showed a significant decrease in resistance to extinction regardless of training condition. The same pattern of results was seen at each of the two post-operative testing times. The results were thus readily replicable, and entirely unlike previous reports of the behavioural effects on this task of conventional septal lesions of equivalent size. In Experiment 3, neurochemical analysis of the hippocampus in rats with ibotenic acid-induced lesions demonstrated that choline acetyl-transferase levels were reduced to the same extent as in rats with comparable conventional lesions.

Animals↗
PubMed1989

Interventional uroradiology.

Major interventional uroradiologic techniques including percutaneous nephrostomy, vascular augmentation and reduction procedures, percutaneous cyst aspiration, chronic peritoneal dialysis catheter manipulation and urethroplasty are reviewed. A brief history of the development and techniques for performing these procedures are included. The results of clinical series are assessed and their role in patient management is addressed. The development of these procedures has had a significant impact on patient care by providing effective nonoperative therapy.

Angioplasty, Balloon↗
PubMed1989

Changes in energy expenditure and work during response acquisition in rats.

The principle of least effort predicts that behavior will tend to maximum efficiency. To test this prediction, changes in the energy expended (VO2) and work performed per reinforcement were monitored continuously as rats learned to press a beam with a criterion force for liquid food rewards. All 12 subjects exhibited significant decreases in energy expended per reinforcement over the 16 days of observation. Of these, 10 subjects also decreased the work performed per reinforcement. Analyses of motor performance were undertaken to determine how motor programs for changing efficiency were generated. The 10 animals showing decreased work reinforcement also exhibited significant decreases in the variability of temporal and kinetic response features and in mean response magnitude (time integral of force or work per response) as a function of practice. Adjustments in work output were primarily accomplished by modifying temporal response features (response duration and, initially, interresponse time). The kinetic features (response recruitment and peak force) remained relatively constant for these animals. The remaining 2 subjects differed in that response recruitment increased after Day 9, resulting in progressively larger amounts of work being performed to earn each reinforcement, and the interval between successive reinforcements decreased.

Animals↗
PubMed1988

A proposed mechanism for chlorpromazine jaundice--defective hepatic sulphoxidation combined with rapid hydroxylation.

On the basis of previous experimental studies we postulated that individuals who were phenotypically good hydroxylators but poor sulphoxidisers would be susceptible to chlorpromazine jaundice. Sulphoxidation capacity was assessed in 12 subjects with a history of chlorpromazine jaundice, using S-carboxymethyl-L-cysteine as an in vivo probe. Following an oral dose of 750 mg, unchanged compound and sulphoxide metabolites were measured in urine. All 12 subjects (100%) were shown to be poor sulphoxidisers compared to 22% of normal controls (P less than 0.001) and 23.8% of liver disease controls (P less than 0.001). No subjects with a history of chlorpromazine jaundice had an impaired hydroxylation capacity as assessed by recovery of 4-hydroxydebrisoquine in urine following oral debrisoquine. The results support the hypothesis and demonstrate an inherent metabolic basis of susceptibility to chlorpromazine jaundice.

Adult↗
PubMed1988

The effects of two therapeutic communities on illicit drug users between 6 months and 1 year after treatment.

Thirty former residents of two different therapeutic communities for illicit drug users were interviewed between 6 months and 1 year after terminating treatment to determine how successfully they had been in adjusting to society. Two findings of this research concerned the amount of time the former residents spent in their therapeutic communities: Time in treatment was associated with fewer arrests once they graduated from these programs and was also associated with less drug use.

Adult↗
PubMed1988

Cadaveric renal transplantation at the University of Pittsburgh: a two and one-half-year experience with the point system.

From January 1, 1986 to July 30, 1988, 530 consecutive cadaver kidney transplantations were performed with patient selection by a point system that took into account time awaiting an organ, donor-recipient matching, degree of presensitization, and some less important factors. The effect of the system was to diminish judgmental factors in case selection which in the past, had probably operated to the disadvantage of "undesirable" potential recipients, including older ones. Primary 1-year graft survival (74%) and graft survival after retransplantation (71%) were lower than in the earlier time. However, the results with triple-drug therapy using CsA, AZA and P demonstrated 88% 1-year graft survival for primary graft recipients and 74% in highly sensitized patients, with comparable patient mortality. These latter observations provide some assurance that the concepts of equitable access and efficient utilization of a scarce resource are not mutually exclusive.

Actuarial Analysis↗
PubMed1988

A liver transplant center information management system.

A comprehensive microcomputer-based data management system has been developed to facilitate candidate selection and to track clinical performance for the liver transplant program at the University of Pittsburgh. A relational database manager, dedicated statistical analysis software, and presentation graphics are all elements that have been integrated into the system.

Humans↗
PubMed1987

Synthetic peptide immunoassay distinguishes HIV type 1 and HIV type 2 infections.

Efforts to solve the epidemiologic puzzle of AIDS in Africa are complicated by the presence of multiple human retroviruses. Simple serologic tests that unambiguously distinguish among infections by these retroviruses are essential. To that end, a partially conserved immunoreactive epitope was identified in the transmembrane glycoproteins of human immunodeficiency viruses (HIV) types 1 and 2. Synthetic peptides derived from these conserved domains were used in sensitive and specific immunoassays that detect antibodies in sera from patients infected with HIV-1 or HIV-2. By making single amino acid substitutions in the HIV-1 peptide, it was possible to demonstrate HIV-1 strain-specific antibody responses to this epitope. Such custom-designed peptides synthesized from this domain are likely to detect newly discovered HIV types, define infection with specific HIV strains, and allow detection of group-common antibodies.

Amino Acid Sequence↗
PubMed1987

Evaluation of balloon angioplasty of coarctation restenosis by magnetic resonance imaging.

Eight patients treated by balloon angioplasty for coarctation restenosis have been followed for 4 to 54 months (mean 40) by physical examination using Doppler pressures and by magnetic resonance imaging in a superconducting magnet operating at 0.6 tesla. Image analysis was performed by inspection and by measurement of the aorta, with particular attention to the angioplasty site and its relation to the ascending aorta at the same axial level. Similar measurements were made from immediate postangioplasty angiograms. Residual pressure gradients were 0 to 12 mm (mean 2), reflecting persistent absence of a gradient in 1 patient and further gradient reduction in 7. Images showed no aneurysm formation, mild residual or recurrent stenosis in 4 patients, minimal focal periaortic soft tissue thickening in 1 patient and an interval increase in the ratio of ballooned segment diameter to ascending aortic diameter in the 7 patients in whom it could be measured. Thus, intermediate-term results of balloon dilatation of coarctation restenosis are excellent and magnetic resonance imaging is well suited to the serial studies required in these patients.

Angioplasty, Balloon↗
PubMed1987

Gender and symptoms of depression and anxiety among Kikuyu secondary school students in Kenya.

Numerous studies have confirmed that patterns of mental illness are influenced by sociocultural factors such as socioeconomic status and gender. This study describes the patterning of symptoms of depression and anxiety on a 20 item self-report questionnaire, the Health Opinion Survey, completed by 159 Kikuyu secondary school students in Kenya. Significant quantitative differences in the responses of males and females to seven of the questions were found, including females reporting more depression symptoms than males. These results are compared to an earlier study of 116 Kikuyu adults in which the differences between males and females were greater. This paper contributes to the literature on the relationship between gender and depression while adding to the sparse descriptive literature on symptoms of depression and anxiety in normal African populations.

Adolescent↗