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Biomedical subjects

R Davies

Publications and source records attributed to R Davies.

At least 253 records · Page 14Linked to original sources
PubMed1983

Plasma vasopressin and blood pressure. Studies in normal subjects and in benign essential hypertension at rest and after postural challenge.

Plasma vasopressin levels were compared in three groups comprising normotensive, mildly hypertensive, and more severely hypertensive patients, both under basal conditions and following an 85 degrees head-up tilt, a stimulus known to provoke vasopressin release in man. Vasopressin levels increased two- to fivefold in all subjects after tilt; however, neither the basal levels nor the maximal levels attained at 45 to 60 minutes after tilt differed in the three groups. These data do not support the postulated role for vasopressin in the causation or perpetuation of non-accelerated essential hypertension in man.

Adult↗
PubMed1983

Effect of asbestos on the P388D1 macrophagelike cell line: preliminary ultrastructural observations.

The ultrastructural effects of mineral dusts on a macrophagelike cell line (P388D1) were studied by transmission electron microscopy. The cells were found to contain virus particles which probably did not exert a cytopathic effect toward the cells. During mitosis the asbestos fibers appeared to be pushed to the periphery of the cell. The distribution of the asbestos in the P388D1 cells was similar to that seen previously in cultured peritoneal macrophages, and it was concluded that the cytotoxic effect of asbestos towards the cells was due to mechanical effects, e.g., by penetrating structures such as the nucleus or phagosomes, by preventing the ordered movement of organelles with the cell or by disrupting the cytoskeletal framework of the cell.

Animals↗
PubMed1983

Factors involved in the cytotoxicity of UICC amosite towards macrophages.

The cytotoxicity of various ball-milled UICC amosite samples toward mouse peritoneal macrophages in vitro was examined. On increased ball milling, the cytotoxicity of the amosite samples fell. This decreased biological activity seemed to correlate best with number of fibers longer than 4 micron/micrograms dust, rather than total number of fibers or the electrophoretic mobility of the amosite samples.

Animals↗
PubMed1983

Factors involved in the cytotoxicity of kaolinite towards macrophages in vitro.

The cytotoxicity of a high purity Cornish kaolinite toward mouse peritoneal macrophages in vitro was examined. The material was cytotoxic towards these cells, the activity could be decreased substantially by pretreating the dust with poly(2-vinylpyridine N-oxide). Pretreatment of the dusts with poly(acrylic acid) had a small effect on cytotoxicity, but combinations of the polymer treatments virtually abolished the material's biological activity towards macrophages. These studies indicated that the cytotoxicity of kaolinite is not due to its flakelike morphology.

Acrylic Resins↗
PubMed1983

Investigation of hypertension.

Ferguson (1975) calculated that if 5 per cent of the estimated 20 million patients with hypertension in the USA had a secondary cause, the cost of their investigation would amount to $2 billion at 1975 prices. For the majority of patients a careful clinical appraisal together with simple biochemical screening tests and a baseline ECG and chest film are adequate before embarking on therapy. For those patients in whom there are clinical or other grounds to suspect a treatable secondary cause, a wide range of modern investigative techniques are available. Even if there are no clues to a secondary cause initially, the possibility of such a cause is occasionally suggested by failure of response to triple therapy with, for example, a thiazide, a beta blocker, and a vasodilator. Whether the hypertensives are being treated in general practice or in hospital, a careful initial assessment together with regular supervision is essential to allow the identification of those with potentially curable disease.

Adrenal Gland Neoplasms↗
PubMed1982

Rebreathing in a subject wearing an integral crash helmet.

The respired air of a volunteer was analysed while he was wearing a variety of integral crash helmets. Observations were made with and without a protective balaclava, bib or scarf, or both. Rebreathing occurred and the peak inspired oxygen tension fell as low as 16.0 kPa (120 mm Hg) with a minimum inspired carbon dioxide of 2.1 KPa (16.0 mm Hg). Accessories worn or attached to the helmet which restrict airflow into the helmet should not be used. Attention should be paid to the "air conditioning" of helmets when worn with flameproof balaclavas and bibs.

Carbon Dioxide↗
PubMed1982

Improvement in cardiac performance by oral long-acting theophylline in chronic obstructive pulmonary disease.

Although oral theophylline is a widely used bronchodilator in chronic obstructive pulmonary disease (COPD), its effects upon cardiac performance have not been fully established. The effect of slow release oral theophylline upon right ventricular and left ventricular ejection fraction was evaluated using first-pass quantitative radionuclide angiocardiography in 15 patients with COPD. After 72 hours of therapy, oral theophylline significantly increased right ventricular ejection fraction (42% to 48%, p less than 0.005). In 7 of 10 patients with depressed baseline right ventricular performance, including two with cor pulmonale, right ventricular ejection fraction normalized (greater than or equal to 45%). After long-term therapy, an average of 16 weeks, right ventricular fraction also increased (43% to 48%, p less than 0.005). Left ventricular ejection fraction improved significantly from 64% to 68% (p less than 0.05) at 72 hours and from 61% to 65% (p less than 0.025) after long-term therapy. These data indicate that oral theophylline produces a sustained modest enhancement of resting biventricular performance in COPD.

Administration, Oral↗
PubMed1982

Biological effects of tremolite.

Tremolite is an amphibole which has been implicated in a variety of disease patterns in different parts of the world. It occurs in a number of phases, which are chemically identical but have specific physical characteristics. In an attempt to clarify the epidemiological findings, tremolite fibres of 3 specific forms--A, B and C--were characterized and studied for biological activity by: (i) in vivo intrapleural injection of rats (2 separate experiments--1 with poor survival). (ii) in vitro enzyme release from mouse peritoneal macrophages (iii) in vitro giant-cell formation in A549 cultures (iv) in vitro cytotoxicity for V79-4 cells. Sample C, which contained more long thin fibres than A and B, was alone in producing mesotheliomas. C, but not A or B, induced LDH and B-glucuronidase enzyme release, and induced giant cells. A was not cytotoxic, B moderately cytotoxic and C as highly cytotoxic as UICC crocidolite. The in vivo studies were marred by being split between 2 experiments, of which the second had poor survival. We are aware of the weakness of our in vivo data, but as Tremolite C was being considered for commercial use on the European market we felt it timely to submit our findings for publication.

Animals↗
PubMed1982

Alterations in heart rate and rhythm at urography with sodium diatrizoate.

One hundred and thirty-five consecutive patients referred for urography were monitored electrocardiographically before, during and after injection of 60 ml Hypaque 45% (sodium diatrizoate 45% w/v) over 60 seconds. The injection produced a significant increase in heart rate, while venepuncture alone had no such effect. Twenty-nine (21%) patients developed minor arrhythmias and 6 (4.4%) major arrhythmias following the injection. Major arrhythmias occurred in the older age groups and were more frequent in males. An abnormal baseline rhythm strip had significant predictive value in determining the development of further arrhythmias.

Age Factors↗
PubMed1981

Present use of five-day wards.

A survey of five-day wards serving medical and surgical specialties indicated that 30 such units were operating in England in 1979. Six mixed surgical specialty, eight mixed specialty (medicine and surgery), four medical investigation, and 12 single specialty wards had opened since 1969. There was a varied, and often low, use of these wards. Nurse-staffing levels and allocation of operating theatre time also varied considerably. In busy wards nurse-staffing levels were high and access to operating theatre time reasonable. Medical investigation wards showed some of the highest levels of occupancy and throughput. The potential savings and service improvements that can result from five-day wards have yet to be realised on a wide scale.

Bed Occupancy↗
PubMed1981

Surface topography of the female bladder trigone.

Cystoscopic biopsy specimens of the bladder trigone of young women with recurrent urinary infections were examined by scanning electron microscopy. The superficial cells of the thickened squamous epithelium of the trigone have either a microridged, microvillous, or mixed pattern. In one case, bacteria were found adherent to all these types of surface. Some cells have a microvillous surface and a cobblestone pattern with long, clubbed microvilli and resemble the cells found in malignant and premalignant states.

Epithelium↗