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Biomedical subjects

A R Williams

Publications and source records attributed to A R Williams.

At least 163 records · Page 9Linked to original sources
PubMed1984

The biochemical changes in pericardial fluid after death. An investigation of the relationship between the time since death and the rise or fall in electrolyte and enzyme concentrations and their possible usefulness in determining the time of death.

This paper reports the biochemical changes that occur in pericardial fluid after death. Significant changes in relation to the time since death occurred in potassium, sodium, phosphate, protein and several commonly measured enzymes. The variation in individual results at similar times since death would limit the use of pericardial fluid biochemistry in determining the time of death.

Body Fluids↗
PubMed1984

A model system to demonstrate the role of cavitational activity in ultrasonic scaling.

A model system consisting of vacuum-deposited aluminum on glass was developed to demonstrate the effectiveness of cavitational activity (occurring within the cooling water supply of a dental ultrasonic scaler) in the removal of particulate material from solid surfaces. The amount of solid material removed from the model system by this cavitational activity was quantified by a spectrophotometric technique. It was shown that cavitational activity occurring within the cooling water is an important contributory factor in the cleaning efficacy of the ultrasonic scaler operated under conditions similar to those employed clinically.

Aluminum↗
PubMed1982

Polyps and cancer of the large bowel: a necropsy study in Liverpool.

In a prospective necropsy study of the large bowel in 365 cases, the commonest polyp identified was the hyperplastic (metaplastic) variety, of which 86.1% of the total were located in the rectum. The other main type of polyp found, and of much greater importance because of its malignant potential, was the neoplastic adenoma. These were present, either singly or multiply, in 73 of 198 male cases (36.9%) and in 48 of 167 female cases (28.7%). Their prevalence and their tendency to be multiple rose with increasing age in both sexes. Most adenomas had a tubular growth pattern and 88.8% of these were under 1 cm in diameter. There was a fairly even distribution of adenomas throughout the large bowel but a higher proportion of adenomas over 1 cm in diameter occurred in the caecum, sigmoid colon, and rectum than at other sites. In the whole series nine adenocarcinomas were present, two of which were arising in adenomas.

Adenocarcinoma↗
PubMed1982

Effect of weight, smoking, and estrogen use on the risk of hip and forearm fractures in postmenopausal women.

From the practices of approximately two thirds of the orthopedic surgeons in King County, Washington, the authors identified white women ages 50 to 74 who had sustained a fracture of the hip or forearm between 1976 and 1979. The women were interviewed concerning factors associated with levels of endogenous estrogens. Their responses were compared to those of a random sample of white female residents of King County in the same age range. The risk of hip fracture was elevated in thin women and in those who smoked cigarettes, particularly among nonusers of estrogen. Neither weight nor smoking affected the risk of forearm fracture in estrogen users, although among nonusers smoking increased the risk, particularly among those who were thin. The beneficial effect of estrogen use in preventing both types of fracture varied considerably according to the woman's weight and smoking status, being greatest in thin women who smoked cigarettes and near zero in heavy nonsmokers. Body weight and cigarette smoking history offer important information concerning the probable degree of protection against fracture afforded by estrogen use.

Aged↗
PubMed1981

The use of beta-thromboglobulin to detect platelet damage by therapeutic ultrasound in vivo.

Three sequential blood samples were drawn from arms of adult human volunteers by means of a cannula technique, and the plasma levels of beta-thromboglobulin (beta-TG an index of platelet damage) were measured. Ultrasound (0.75 MHz, continuous wave; spatially averaged intensity 0.34 to 0.5 W/cm-2) was applied to the blood vessels while the second sample of each series was being taken. No elevation of beta-TG was detected, indicating that under these conditions ultrasonic irradiation had not damaged an appreciable number of platelets. There was, however, an indication of decreased platelet sensitivity following insonation; and it is postulated that this may be the result of either increased production or secretion of the potent endothelial platelet inhibitor, prostacyclin, or both.

Adult↗
PubMed1980

Decreased risk of fractures of the hip and lower forearm with postmenopausal use of estrogen.

We interviewed 327 women who had been 50 to 74 years of age when treated for fracture of the hip of lower forearm, to determine their use (or lack of use) of estrogen preparations. Their responses were compared with those in a random sample of 567 women who were of similar age and from the same region. The risk of fracture was 50 to 60 per cent lower in women who had used these drugs for six years or longer than in women who hadnot used them (95 per cent confidence interval of relative risk, 0.3 to 0.6); those using them for shorter periods received less benefit, if any. A decreased risk of fracture was clearly evident only in women still taking estrogens and evident at either common daily dose (0.625 and 1.25 mg). In conjunction with the finding that estrogens can retard the development of osteoporosis in postmenopausal women, our data argue that lowering of the risk of hip and forearm fractures must be weighed as a benefit of long-term estrogen use.

Aged↗
PubMed1980

The internal viscosity of the human erythrocyte may determine its lifespan in vivo.

Young red cells obtained by high-speed centrifugation of a normal blood sample had an MCHC of 31.7 g/dl which corresponds to an internal viscocity of about 9 cP. Old red cells from the same blood sample had an average MCHC of 37.5 g/dl which is equivalent to a mean internal viscosity of about 54 cP. This increased internal viscocity of old cells must result in a prolonged transit time through the narrow channels of the splenic microvasculature and consequently an increased probability of contact with a phagocytic macrophage. This probability of contact increases as the internal viscosity of the cell is further increased and may represent one of the major factors associated with the detection and subsequent elimination of senescent cells by the spleen.

Erythrocyte Aging↗
PubMed1980

A forward look.

Explore the source record for details and available documents.

Forecasting↗
PubMed1979

The effects of suspending medium viscosity on erythrocyte deformation and haemolysis in vitro.

Fresh adult human erythrocytes were suspended in isotonic pH adjusted solutions containing various concentrations of Dextran T.500. The cells were subjected to uniform hydrodynamic shear stress in a Ferranti Shirley Cone and Plate Viscosimeter. The amount of lysis incurred at any given combination of exposure parameters was markedly affected by the viscosity of the suspending medium. Optical diffraction patterns obtained whilst the cells were undergoing shear demonstrated that cellular deformation was also a function of viscosity. Consequently, the distorted shape of the stressed cell may play a crucial role in the haemolytic process.

Adult↗