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Biomedical subjects

D Richardson

Publications and source records attributed to D Richardson.

At least 163 records · Page 9Linked to original sources
PubMed1992

Effects of kwashiorkor malnutrition on measured capillary filtration rate in forearm.

This study investigated the effects of kwashiorkor malnutrition on blood tissue fluid exchange by measuring the rate of capillary filtration (CFR) in response to a 60-mmHg increment in venous pressure in the forearms of 1- to 3-yr-old native African children within the Transkei Homeland. They were divided into the following subject groups: kwashiorkor patients (K); kwashiorkor patients who were at various stages of recovery (RK); marasmus patients (M); patients with edema of nonkwashiorkor origin (E); and control children (C). Measurements of CFR were significantly lower in the K subjects compared with any of the other groups (P less than 0.05), whereas, the RK, M, E, and C subjects were not significantly different from each other. This latter finding indicates that the lower CFR of the K patients is reversible and is not due to malnutrition or edema per se. Measurements of forearm cutaneous blood flow by laser Doppler flowmetry (LDF) in C and K subjects showed only a slightly lower value for the K patients (P greater than 0.20), and there was no relationship between CFR and LDF for either group (r = 0.073). These results suggest that the lower CFR of the K patients is not secondary to peripheral vasoconstriction.

Anthropometry↗
PubMed1992

Blunt cardiac injury.

Explore the source record for details and available documents.

Abbreviated Injury Scale↗
PubMed1992

Women, AIDS and reproduction.

Relatively little has been written about how Aids affects women. When women are mentioned it is primarily as carers of people with Aids or as possible transmitters of the HIV virus, with the focus largely on prostitutes and pregnant women. The concern overwhelmingly is about how to protect the health of men and children, writes Diane Richardson. Here she examines the implications of Aids and HIV infection for women's health and reproductive rights.

Acquired Immunodeficiency Syndrome↗
PubMed1991

The uptake of inorganic iron complexes by human melanoma cells.

The human melanoma cell line, SK-MEL-28, expresses high levels of melanotransferrin. The uptake of inorganic iron (Fe) complexes compared to transferrin-bound Fe by these cells has been investigated to determine whether melanotransferrin has a role in Fe uptake. The mechanisms of Fe uptake have been characterised using 59Fe complexes of citrate, nitrilotriacetate, desferrioxamine, and 59Fe added to Eagle's minimum essential medium (MEM) and compared with human transferrin (Tf) labelled with 59Fe and iodine-125. Iron uptake from the Fe complexes of citrate, nitrilotriacetate and MEM were similar, and far greater than that from Tf at the same Fe concentration (2.5 microM). Ammonium chloride and a monoclonal antibody to the transferrin receptor (42/6), had no effect on the uptake of Fe from inorganic Fe complexes, suggesting that receptor-mediated endocytosis of Tf was not involved. The monoclonal antibody, 96.5, specific for melanotransferrin did not alter total Fe uptake but slightly increased the proportion of Fe internalised, possibly due to the modulation of the antigen by the antibody. However, from the time required for modulation to occur (approximately 2 h), the small increase in internalisation observed and the fact that no increase in total cell Fe occurred, it is suggested that melanotransferrin has little role in Fe uptake.

Ammonium Chloride↗
PubMed1991

Repair of shoulder luxation in a horse.

Shoulder luxation in a 3-year-old Thoroughbred filly was treated by closed reduction, using a calf jack to provide traction on the limb. Arthroscopic examination of the shoulder allowed removal of soft tissue and bony debris. After surgery, the filly was confined to a box stall for 6 months. Eight months after surgery, the filly was doing light work and was not lame. Muscular atrophy present before surgery had resolved. Use of a calf jack may allow reduction of shoulder luxation under field conditions.

Animals↗
PubMed1991

The cutaneous microcirculation of the forearm in young and old subjects.

Previous studies have shown a reduced cutaneous circulatory response to direct heat stress in the forearm circulations of older (60 to 80 year) subjects. The purpose of this study was to test the hypothesis that this aging effect is due to a reduced ability of the cutaneous microvessels in the forearm to respond to direct heat. Two groups of male subjects consented to participate; a group of 15 young individuals (Y; 20-39 year) and a group of 11 older (O; 60-79 year) individuals. The subjects rested in a supine position with the right forearm situated on the stage of a Leitz epiilumination microscope which was used to view the superficial cutaneous microvessels. The width of the red cell column (WRC), an index of vascular diameter, and the blood cell velocity (BCV) within the microvessels were measured by videomicroscopy at the presenting skin temperature (Ts) of 32 degrees, and then again after Ts had been elevated to 35 degrees then 40 degrees. At a Ts of 32 degrees, WRC and BCV for the Y group, respectively, averaged 6.6 microns and 0.22 mm/sec. Corresponding averages for the O subjects were 8.4 microns and 0.17 mm/sec. Between-group differences were not significant. At a skin temperature of 40 degrees, BCV was significantly higher compared to that at 32 degrees and 35 degrees for both groups (P less than 0.05); whereas, WRC did not significantly change. There were no significant between-group differences in BCV at the higher two temperatures. These results argue against a diminished blood flow response of superficial microvessels being responsible for the reduced cutaneous circulatory response to heat stress in older individuals.

Adult↗
PubMed1991

Anterior maxillary osteoplasty to broaden the narrow maxillary ridge.

The application of endosseous implants has extended the range of options and effectiveness of reconstructive preprosthetic surgery. Placement of endosseous implants in the edentulous maxilla is often restricted due to lack of available bone. Exposure of the underlying anterior maxillary bone frequently reveals a ridge form which is adequate in height but too narrow to accommodate endosseous implants. A horseshoe type osteotomy extending from the ridge crest into the floor of nose has been developed which allows advancement of the outer cortex to restore lost facial form and placement of an interpositional bone graft and endosseous implants to restore lost function.

Adolescent↗
PubMed1991

Effects of invariant sympathetic activity on cutaneous circulatory responses to heat stress.

This study investigated the role of sympathetic withdrawal on blood flow responses in cutaneous arteriovenous anastomoses (AVAs) and capillaries to direct and indirect heat stress. This was achieved by clamping sympathetic activity (SC) to the tail of anesthetized rats so that constrictor tone remained invariant during exposure of either the animal's tail (direct heating) or body (indirect heating) to a 35 degrees C environment. Flow through the AVAs in the tail was evaluated by laser-Doppler flowmetry (LDF), while capillary flow was investigated by videodensitometry measurements of blood cell velocity (CBV) in single capillaries within the subepidermal vascular plexus. Both direct and indirect heating significantly increased LDF and CBV. In comparison to blood flow responses in sham-operated control rats, the SC procedure resulted in significantly lower LDF responses to both direct and indirect heat stress. By contrast, the response of CBV was not significantly affected by SC during either mode of heating. These results indicate that the withdrawal of sympathetic constrictor tone plays a role in the response of cutaneous AVAs, but not precapillary arterioles, to direct as well as indirect heat stress. Additional studies on unanesthetized animals showed that superimposing body heating on a base of local heating elicited a further increase in LDF, suggesting that local heating does not deplete neural mediated dilatory reserve.

Animals↗
PubMed1991

Studies on yeast nucleoside triphosphate-nucleoside diphosphate transphosphorylase (nucleoside diphosphokinase). IV. Steady-state kinetic properties with thymidine nucleotides (including 3'-azido-3'-deoxythymidine analogues).

A study of the steady-state kinetics of the crystalline brewer's yeast (Saccharomyces carlsbergensis) nucleoside diphosphokinase, with the magnesium complexes of the adenine and thymidine nucleotides as reactants, has led to a postulated kinetic mechanism which proceeds through a substituted enzyme. This agrees with the earlier conclusions of Garces and Cleland [Biochemistry 1969; 8:633-640] who characterized a reaction between the magnesium complexes of the adenine and uridine nucleotides. An advantage of using thymidine nucleotides as reactants is that they permit accurate, rapid and continuous assays of the enzymatic activity in coupled-enzymatic tests. Through measurements of the initial velocities and product inhibition studies, the Michaelis constants, maximum velocities, and inhibition constants could be evaluated for the individual substrates. Competitive substrate inhibition was encountered at relatively high substrate concentrations, which also permitted an evaluation of their ability to act as 'dead-end' inhibitors. The Michaelis constants for the 3'-azido-3'-deoxythymidine (AzT) analogues were also evaluated and, although these values were only somewhat higher than those of their natural substrates, the Km's for the adenine nucleotides as paired substrates were lower and the Vmax's were drastically reduced. The pharmacological implications of these observations are touched upon and extrapolated to the cases where therapeutic doses of AzT may be employed.

Adenine Nucleotides↗
PubMed1991

Age-related potentiation of the cutaneous capillary blood flow response to heat stress.

This study tested the hypothesis that the rarefaction of cutaneous capillaries with age is compensated by an increase in the response of remaining capillaries to heat stress. Experiments were performed on unanesthetized male Sprague Dawley rats of the following age groups: young (Y--age 4 mo.), middle aged (M--age 16 mo.) and old (O--age 27 mo.). The subepidermal vascular plexus of the tail was viewed by video microscopy from which measurements of blood cell velocity (BCV) in single plexus capillaries and the density of flowing capillaries (DFC) were made. The animal's body and tail were housed in separate chambers for respectively indirect and direct heat stress trials. At a neutral temperature of 25 degrees C there were no significant age differences in BCV, but DFC was decreased from the Y to the M to the O groups. During an indirect heat stress of 35 degrees C, there was a modest increase in DFC and the Y greater than M greater than O rank order persisted. By contrast, all groups experienced a marked increase in BCV during both indirect and direct heat stress, and the degree of the response was significantly greater for the O rats compared to the M or Y groups. These results support the hypothesis being tested.

Aging↗
PubMed1990

Long distance travel for routine elective surgery: questionnaire survey of patients' attitudes.

OBJECTIVE: To carry out an audit and assess the acceptability of long distance travel to patients on a lengthy surgical waiting list. DESIGN: Audit and questionnaire survey. SETTING: Military hospital in Wiltshire. PATIENTS: 116 Patients on a general surgical waiting list at Leighton Hospital near Crewe. INTERVENTIONS: Preselection for medical fitness at a waiting list review clinic. RESULTS: Roughly half of patients offered the facility of travelling 120 miles (190 km) for their routine elective operation at the health authority's expense accepted. The average waiting list time declared by the patients who travelled was 28 months, and 13 patients stated that their condition prevented them from working. Only four patients regretted their decision to participate in the scheme. Lack of visitors did not cause undue concern. CONCLUSIONS: Some patients did not agree to travel for their operation but almost all of those who did so found the scheme satisfactory. Some minor problems were encountered but these could probably be overcome by ensuring use of appropriate transport, extending the postoperative stay when necessary, and more careful selection of patients for an anaesthetic. For efficient use of theatre time in such schemes it is crucial that the operating consultant surgeon should be in charge of case selection.

Attitude to Health↗
PubMed1990

A semi-automated neutral red based chemosensitivity assay for drug screening.

A semi-automated colorimetric chemosensitivity assay was developed. The assay utilizes the vital stain neutral red for the rapid screening of potential anticancer agents using solid tumor cell lines. The cell lines used in this assay and presented in this report are CX-1 colon adenocarcinoma and A549 lung carcinoma. The assay, performed in 96 well tissue culture plates, allows for short drug exposure times (3 hrs.) followed by quantitation of cell number (neutral red absorbance) following four cell doubling times. Cell number directly correlated with absorbance of eluted neutral red at 540 nm. However, optimal amounts of dye and staining times varied between cell lines. IC50 concentrations (for inhibition of cell growth) determined using this assay were in good agreement with results from clonogenic assays using similar drug treatment conditions. The assay technique was determined to be capable of detecting antineoplastic compounds operating by a wide variety of mechanisms.

Adenocarcinoma↗