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Biomedical subjects

R Brown

Publications and source records attributed to R Brown.

At least 451 records · Page 25Linked to original sources
PubMed1993

A comparison of two systems for assessing cerebral venous oxyhaemoglobin saturation during cardiopulmonary bypass in humans.

The Somanetics Invos 3,100 cerebral oximeter is a new noninvasive device which measures the regional oxygen saturation of haemoglobin within the cerebral microvasculature by infrared spectroscopy. It was used in nine patients undergoing elective cardiac surgery and its results were compared with measurements of jugular venous bulb saturations obtained by the Oximetrix Opticath oximetry system. The index value of jugular venous bulb saturation was obtained by analysis of jugular bulb blood in an Il282 cooximeter. The cerebral oximeter was less accurate and precise (standard deviation of difference 14.1%) than the Oximetrix system (standard deviation of the difference 2.65%) and also demonstrated a systematic error in bias unrelated to cerebral perfusion pressure. The cerebral oximeter may therefore be less useful than jugular venous bulb saturation in the clinical management of patients undergoing cardiopulmonary bypass.

Adult↗
PubMed1993

Clinic blood pressure measurements and blood pressure load in the diagnosis of hypertension.

We have retrospectively compared the blood pressure load derived from 24 hour ambulatory blood pressure monitoring in patients with all clinic blood pressure readings elevated with those with only some elevated pressures to establish whether clinic readings alone are good predictors of blood pressure status. Fifty-seven patients attending a district general hospital hypertension clinic who were not on anti-hypertensive treatment were selected. Between two and six clinic readings were taken over a period of 1-6 months. Forty out of 57 patients had at least one clinic diastolic blood pressure reading of < 90 mmHg and, of these, 14 (35%) had a high blood pressure load and 26 (65%) had a normal blood pressure load. Patients with all diastolic blood pressure readings > 90 mmHg totalled 17 and of these 11 (65%) had high load and six (35%) had normal load. Patients with clinic diastolic blood pressure > 90 mmHg were significantly more likely to be truly hypertensive on the basis of blood pressure load than if one or more clinic readings was below 90 mmHg (P < 0.05). Diastolic pressures have some predictive power as to the blood pressure status defined by blood pressure load, but even consistently raised diastolic pressures do not necessarily indicate hypertension. Likewise one or more clinic diastolic blood pressure < 90 mmHg does not assuredly indicate normotension. Twenty-four hour ambulatory blood pressure monitoring may have an increasingly important role in the assessment of hypertension.

Adolescent↗
PubMed1993

Rational behavior training effectiveness for white and nonwhite incarcerated felons.

45 incarcerated male felons in a medium-security state correctional institution participated in a Rational Behavior Training treatment outcome study. 58% of the subjects were white, 18% were African-American, 17% were Hispanic, and 7% were classified as other. Subjects were selected from an institutional group-therapy waiting list and randomly assigned to one of four group facilitators. The Novaco Provocation Inventory, Buss-Durkee Hostility Inventory, and Rational Behavior Training Concepts Test were administered before and after the 10-wk. treatment period. No differences in gain scores (pretest minus posttest) were observed although the slightly greater improvement on the concepts test by subjects of ethnic minority encourages further study.

Adult↗
PubMed1993

Synthesis and structure-activity relationships of new cephalosporins with aminoimidazoles at C-7. Effect of the pKa of the C-7 aminoimidazole on antibacterial spectrum and beta-lactamase stability.

Cephalosporins with new aminoimidazole heterocycles at C-7 have been synthesized by reaction of anti-alpha-aminooximes with C-7 dihaloisocyanocephalosporins esters or by direct condensation of 2-fluoroimidazoles with C-7 aminocephalosporins esters. These compounds combine a broad spectrum of antibacterial activity, including Gram-negative and Gram-positive organisms with a good beta-lactamase stability. Activity is discussed in terms of its relationship to the pKa of the C-7 aminoimidazole heterocycle, basic C-7 aminoimidazole residues gave cephalosporins with the best beta-lactamase stability but the poorest activity against Gram-positive organisms. An additional interesting property of the C-7 imidazolylaminocephalosporins is the oral activity present in some compounds of this series.

Animals↗
PubMed1993

Perception of need for child psychiatry services among parents and general practitioners.

Previous research has found the prevalence of child psychiatric disorder in the general population to be between 7% and 25%, and higher among attenders at some general practitioners' surgeries. This survey examines the perception of need among general practitioners and parents of general practice attenders, and compares this with the prevalence of disorder found using the Rutter A Questionnaire for Parents. The results support claims that the services for children with psychiatric disorders are inadequate. However, many children with disorders are presented to other professionals by their parents. Ways to extend the service synergistically to meet some of the unmet need are discussed. The need for further research to be undertaken, which would effectively target such scarce resources, is identified.

Adolescent↗
PubMed1993

A genetic linkage map of chromosome 21: a look at meiotic phenomena.

We have developed a genetic linkage map of chromosome 21 using 17 microsatellite marker polymorphisms. The markers span virtually the entire length of 21q, and define a sex-equal map of 56 cM. Extensive error checking has been used to provide an accurate map. All recombination events have been identified, allowing us to place within a small interval any new markers by genotyping only a few critical individuals. The resulting segregation data has been examined for several meiotic phenomena, including sex differences in recombination, age differences in recombination, interference, and segregation distortion.

Alzheimer Disease↗
PubMed1993

Effects of acute graded strain on efferent conduction properties in the rabbit tibial nerve.

This study examines effects of acute stretch on electrophysiologic properties of rabbit tibial nerve. Compound motor action potentials (CMAP) were measured in 30 rabbits, during and after two hours of acute, graded strain. The rabbits were assigned to one of three groups defined by the degree of stretch (0%, 8%, or 15%) beyond original resting length. These groups were subdivided according to ankle position during nerve strain (ankle dorsiflexion or ankle plantar flexion). Two hours of 8% strain did not significantly decrease CMAP amplitude. Fifteen percent strain with the ankle in dorsiflexion produced a significant and profound drop (99%) in CMAP amplitude. These findings are clinically relevant to nerve stretch injuries and to surgical procedures that induce acute nerve strain.

Action Potentials↗
PubMed1993

A computer modelling system for the biomechanical interaction in product design.

We introduce our system approach to rehabilitation engineering in which the user product interaction is emphasised. We then discuss a computer based approach to the problems of design making use of analysis software for the mechanical interaction. Our developing system for design, making use of anthropometric data and mechanisms analysis, is placed in the context of ergonomics and occupational biomechanics. We report our initial case study of this approach.

Anthropometry↗
PubMed1993

Percutaneous renal biopsy in the district general hospital.

This paper reports a retrospective study of the clinical value of percutaneous renal biopsy in secondary referral centres. Between 1984-90, 205 patients over the age of 16 had 218 biopsies at three district general hospitals. Adequate tissue was obtained in 194 patients (95%, 89% of the biopsies). Significant complications occurred in only four patients. In 170 patients (83%) the biopsy yielded information of diagnostic and prognostic value and influenced management. The main indications for biopsy were nephrotic syndrome, in 63 patients, and chronic renal failure, in 58 patients. The most frequent findings were minimal change disease, focal segmental glomerulosclerosis, IgA nephropathy, membranous glomerulonephritis and mesangiocapillary glomerulonephritis. The most obvious association between indication and histology was between haematuria and IgA nephropathy. Percutaneous renal biopsy in the district general hospital in patients selected by a nephrologist and performed by experienced or supervised operators is a safe procedure. There is a high yield of renal tissue which is of clinical value in patient care.

Adolescent↗
PubMed1993

Differential lung ventilation. Applications beyond the operating room.

Mechanical ventilatory support in the setting of unilateral lung disease offers unique problems in management. When the difference in airway resistance or lung compliance between the two lungs is exaggerated, conventional mechanical ventilation might lead to preferential ventilation with hyperexpansion of one lung and gradual collapse of the other. Differential ventilation has been advocated to avert this problem. We illustrate the use of this technique in the management of two patients with different underlying pathologic conditions.

Adult↗
PubMed1993

Arsenic in the sera of gallium arsenide-exposed mice inhibits bacterial growth and increases host resistance.

The objective of the present investigations was to evaluate whether the presence of gallium arsenide (GaAs) in the sera of exposed mice was sufficient to retard bacterial growth. Host resistance studies demonstrated that exposure of GaAs (50-200 mg/kg) produced an increased resistance to Streptococcus pneumoniae and Listeria monocytogenes (50-100 mg/kg GaAs) when microbial challenge occurred 24 hr after exposure. In contrast, exposed mice exhibited a profound and dose-related decrease in resistance to the B16F10 melanoma. Serial dilutions of GaAs (0.039-5 mg/ml) were added to BHI broth and cultures were innoculated with either S. pneumoniae or L. monocytogenes. GaAs slowed the growth of both organisms with a minimal inhibitory concentration (MIC) of 0.625 mg/ml. Sera from mice euthanized at various time intervals after exposure to vehicle (0.05% Tween 80 in saline) or GaAs (200 mg/kg) was also capable of retarding the growth of both organisms with the maximal inhibition noted for euthanization 24 hr after exposure. However, sera from GaAs-exposed mice (24 hr after exposure) was incapable of slowing the growth of the B16F10 melanoma. Addition of the arsenic-binding compound meso-2,3-dimercaptosuccinic acid (100 microM) to sera from mice exposed to GaAs followed by innoculation with L. monocytogenes resulted in growth of this organism, which was comparable to growth observed in vehicle cultures.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Binding of human single-stranded DNA binding protein to DNA damaged by the anticancer drug cis-diamminedichloroplatinum (II).

The chemotherapeutic drug cis-diamminedichloroplatinum (II) covalently binds to DNA resulting in a variety of adducts and cross-links which are thought to be responsible for the toxicity of the drug. We have used the gel mobility shift assay to detect proteins which bind to DNA treated in vitro with cis-diamminedichloroplatinum (II) and have identified two complexes which bind with increased affinity to cis-diamminedichloroplatinum (II)-damaged DNA. Using monoclonal antibodies we have shown that one complex, B1, contains human single-stranded DNA binding protein, a protein known to be involved in the in vitro repair synthesis assay of mammalian excision repair.

Antibodies, Monoclonal↗
PubMed1992

Glutathione depletion in chronic lymphocytic leukemia B lymphocytes.

Glutathione (GSH) content may be the major determinant of a cell's sensitivity to cytotoxic alkylating agents. In the present study, the GSH concentration was determined in lymphocytes isolated from the blood of normal subjects and patients with chronic lymphocytic leukemia (CLL). Comparable levels were found in both types of cells. Incubation for 20 hours led to a decrease in GSH to 51% of baseline values in CLL B cells. Under the same conditions, normal B- or T-lymphocyte GSH content remained constant. GSH depletion was shown to be a characteristic of the B-CLL B lymphocyte. It was not found in the T cells of patients with B-CLL or in cells from patients with T-CLL. Chlorambucil (CLB) contributes to the decrease in GSH in B-CLL lymphocytes; after incubation with the drug, lower levels of GSH were found than in the normal B or T lymphocytes, B-CLL T cells, or T-CLL (CD4 or CD8) cells. GSH depletion of CLL B lymphocytes may be related to the greater therapeutic efficacy of CLB in B-CLL than in T-CLL.

B-Lymphocytes↗
PubMed1992

Immunochemiluminometric assays (ICMA) specific for growth hormone releasing hormone 1-44 NH2 and 1-40 OH.

We describe specific two-site immunochemiluminometric assays able to directly measure human growth hormone-releasing hormone 1-44 NH2 and 1-40 OH concentrations in unextracted plasma. A common N-terminal antibody was purified from polyclonal rabbit antisera to growth hormone-releasing hormone 1-44 NH2 on a growth hormone-releasing hormone 1-29 NH2 linked affinity column and labelled with chemiluminescent acridinium ester. C-terminal specific monoclonal antibodies to growth hormone-releasing hormone 1-44 NH2 and 1-40 OH were raised in Balb/C mice and used as solid phase antibodies. Assay of fasting specimens from normal individuals gave medians (and ranges) of 23 pg/ml (2-200) and 30 pg/ml (3-134) for growth hormone-releasing hormone 1-44 NH2 and 1-40 OH, respectively. Samples from a series of acromegalics showed that most have values in the normal range though median values were higher, 56 pg/ml for growth hormone-releasing hormone 1-44 NH2 (P < 0.001) and 52 pg/ml for 1-40 OH (P < 0.001). Using these assays it will be possible for the first time to directly study the physiology and pathophysiology of these two peptides.

Acromegaly↗
PubMed1992

Autoantibodies to thrombomodulin: development of an enzyme immunoassay and a survey of their frequency in patients with the lupus anticoagulant.

In order to investigate the possibility that autoantibodies to thrombomodulin (TM) may exist in patients with the lupus anticoagulant (LA) and perhaps be implicated in the pathogenesis of recurrent thrombosis seen in such patients, we developed an enzyme-immunoassay to screen serum samples for anti-human TM activity. The major technical problem encountered in developing this assay was to reduce the non-specific binding of serum components from both the LA positive and the negative population. Considerable reduction of non-specific binding was achieved by use of a phosphate/citrate buffer at pH 8.0 and the use of an optimal sample dilution of 1/40. In addition, samples were always tested in parallel in blank wells and results are expressed as an OD ratio. Samples from 113 patients with the LA were assayed and compared to 78 patients referred for LA testing but found to be negative. The mean OD values for the LA positive patients (+/- SD) was 1.36 (0.44) with a range of 0.78-2.57. This was virtually identical to the values for the LA negative population (1.38 +/- 0.40, range 0.76-2.77). The results of this study indicate that there is no evidence for the presence of a significant autoantibody activity to TM in patients with the LA when compared to LA negative patients. If such autoantibodies do exist their frequency must be quite low.

Autoantibodies↗
PubMed1992

Characteristics of peak aerobic capacity in symptomatic and asymptomatic subjects with left ventricular dysfunction. The Studies of Left Ventricular Dysfunction (SOLVD) Investigators.

Expired gas analysis was used to determine the aerobic exercise performance of subjects with depressed left ventricular (LV) systolic function and congestive heart failure (CHF). To determine whether subjects with no or minimal CHF have better aerobic exercise performance than do those with overt CHF, oxygen consumption (VO2) at anaerobic threshold (AT) and peak exercise was measured in 184 subjects with LV ejection fraction less than or equal to 0.35 who participated in the Studies of Left Ventricular Dysfunction. Subjects were divided into those with overt CHF needing treatment (treatment trial; n = 20) and those who had neither overt CHF nor treatment for CHF (prevention trial; n = 164). Treatment trial subjects had a lower LV ejection fraction (0.25 +/- 0.07) than did prevention trial ones (0.29 +/- 0.05; p = 0.001), but there were no differences in age, gender, body weight, resting heart rate and blood pressure. Treadmill exercise testing was performed after 2 to 3 weeks of placebo (no angiotensin-converting enzyme inhibitor) treatment. Treatment trial subjects exercised for a shorter time (493 +/- 160 seconds) and attained a lower peak VO2 (13 +/- 4 ml/kg/min) and VO2 at AT (11 +/- 4 ml/kg/min) than did prevention trial ones (842 +/- 277 seconds, and 20 +/- 6 and 16 +/- 5 ml/kg/min, respectively). Analysis of covariance showed that the differences in peak VO2 and VO2 at AT were statistically significant between the 2 trials after adjusting for age, gender, LV ejection fraction and New York Heart Association functional class.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗