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Biomedical subjects

R Davies

Publications and source records attributed to R Davies.

At least 217 records · Page 12Linked to original sources
PubMed1989

Secretion of fibronectin by mineral dust-derived alveolar macrophages and activated peritoneal macrophages.

The in vitro secretion of fibronectin by rat alveolar macrophages recovered following the intratracheal instillation of various mineral dusts was examined using a competitive enzyme-linked immunoassay (CELIA) method. Cells derived with the fibrogenic dusts DQ12 quartz and UICC crocidolite asbestos had elevated rates of fibronectin secretion when compared ith those derived from titanium dioxide or saline. The in vitro culture of alveolar macrophages with dusts did not lead to elevated rates of fibronectin secretion, suggesting that mechanisms other than the direct interaction between dusts and macrophages may be responsible for elevated rates of fibronectin secretion by cells exposed to fibrogenic dusts. This suggests that fibronectin deposition seen in pneumoconiotic lesions in immunohistochemical studies may in part have been derived from macrophages. Thioglycollate-induced activated mouse peritoneal macrophages secreted significantly less fibronectin than resident peritoneal macrophages, a finding contrasting with those of Tsukamoto et al. [7].

Animals↗
PubMed1989

Modification of fibrous Oregon erionite and its effects on in vitro activity.

A sample of erionite, a fibrous zeolite, was modified by milling to reduce the number and length of the fibres and by extraction with cyclohexane. The in vitro activities of this mineral were found to depend on the presence of long fibres. The erionite contained fewer of these fibres than the UICC asbestos samples but, unlike these materials, erionite can cause the transformation of C3H 10T1/2 cells. Erionite did not increase the activities of benzo[a]pyrene in this cell transformation assay. The cytotoxic activities of both asbestos and erionite have a similar dependence on the number of long fibres. Extraction with cyclohexane did not affect the activity of erionite.

Aluminum Silicates↗
PubMed1988

The economy, the health sector and child health in Zimbabwe since independence.

This paper examines the changes in the economic environment which have taken place in Zimbabwe since independence in April 1980, concentrating on those which are relevant to health. It also describes the post-independence restructuring of the health sector itself. Finally, it considers some changes which have taken place in the health status of children. Despite a prolonged drought, economic recession and the imposition of economic stabilisation measures, there is evidence of a sharp improvement in infant and young child mortality. This has resulted almost certainly from an energetic expansion and reorientation of health care provision, and particularly from greatly improved access to immunisation and oral rehydration therapy. The adverse effects of drought and stabilisation measures have been partially offset by aid-supported relief feeding and particular health programmes. However, the economic crisis has resulted in a decline in real incomes for a large number of households since the immediate post-independence boom. This is reflected in high levels of childhood undernutrition which seem to have remained static despite the health care drive. This emerging divergence between death rates and quality of life as reflected by nutrition levels is reflective on the one hand of rapid expansion in effective health care provision, and on the other of little change in socio-economic conditions for the majority of the population.

Child↗
PubMed1988

Tracheal aspirates from neonates during endotracheal intubation: detection of surfactant by polarized light microscopy.

A technique for detecting the presence of pulmonary surfactant in the tracheal aspirates obtained from preterm babies is described. The specimens were examined by means of polarized light microscopy. Surfactant could be simply and rapidly identified by its appearance as birefringent particles in volumes of aspirate as little as 1 microliter. Tracheal aspirate specimens from 108 babies, obtained on the first day of life, were examined without knowledge of the patient's clinical details. When the samples from each baby were subdivided into three groups on the basis of the amount of surfactant particles seen, this subgrouping corresponded well with the babies' ventilatory requirements at the time of sample collection. This method of detecting surfactant material may prove valuable in determining the degree of surfactant deficiency in individual preterm babies with respiratory illness.

Humans↗
PubMed1987

Effects of rifampicin on the peripheral turnover kinetics of thyroid hormones in mice and in men.

The induction of mixed function hepatic oxygenases by rifampicin is known to increase the metabolic clearance rate (MCR) of T4. By performing T3 and rT3 kinetics we have shown that rifampicin also increases the MCR of T3 and rT3. Using the fall of serum T4 during TSH suppression as an indirect marker of the production rate (PR) of T4, we have demonstrated that there was no major change in monodeiodination nor any shift to either 5'- or 5-monodeiodination. Rifampicin stimulates in mice the mixed function hepatic oxygenases. However, we were unable to increase hepatic deiodinase activity (deiodinase type I) in this species. It is therefore possible that the increased MCR of T4 in man is not mediated by an increased conversion rate either. As mixed function hepatic oxygenases are known to increase hepatic conjugation it is suggested that rifampicin increases the biliary excretion of iodothyronine conjugates.

Adult↗
PubMed1987

A simulation model for planning services for renal patients in Europe.

A discrete-event simulation model is being developed to provide information for national and regional health planners about the effect of different treatment policies and practices on the increasing numbers of patients with irreversible kidney failure. The simulation program, written in Pascal using Pascal-SIM, describes the activities of individual patients whose progress through treatment depends on their characteristics and treatment history, as well as on treatments availability. Programming techniques have been developed to cope with the multiple scheduling of patient entities and the resultant queue-management problems. In order to provide simulation runs on request, for any population group, appropriate data is selected from the European Dialysis and Transplant Association Registry data base for use in the simulation program. Results are shown on a computer screen while the simulation is running, and are saved for further analysis to provide feedback to the requesting organization.

Computer Simulation↗
PubMed1986

Prospective study of alcohol-related admissions in an inner-city hospital.

Of 2598 acute admissions to the intensive therapy unit and medical, surgical, orthopaedic, and casualty wards of a general hospital in London, 313 (12%) were definitely alcohol related. Over half (163) the patients concerned were aged between 14 and 40 and 70% (219) were male. The proportion of alcohol-related admissions varied from 7.2% for a general surgical ward up to 26.3% for the casualty overnight observation ward. Substantially higher than average rates of alcohol-related admission were seen in Irish, Scottish, and Polish patients. Of the 23 deaths in the beds under scrutiny in patients aged 17-60 years, 9 were directly attributable to acute or chronic alcohol abuse.

Adult↗
PubMed1986

Shoshin beriberi: an underdiagnosed condition?

Shoshin beriberi, a fulminant form of heart failure due to thiamine deficiency has a different presentation to the classical form of beriberi heart failure. It is characterized by a cold periphery, low blood pressure, renal shutdown and a severe metabolic acidosis. The true incidence is unknown. Two patients were seen within a few months in a general hospital and in both dietary deficiency of thiamine was a major factor.

Acute Disease↗
PubMed1986

Countercontrol treatment of sleep-maintenance insomnia in relation to age.

We administered countercontrol behavioral therapy for sleep-maintenance insomnia to 34 insomniacs--ranging in age from 35 to 78 years--in small groups. Twenty-two subjects received immediate and 12 received delayed treatment. Three self-report measures of sleep disruption were collected on daily sleep diaries at baseline, termination of treatment, 1-month follow-up, and 12-month follow-up. Although amount of time awake at night was correlated with age (r = .50), response to treatment was not. Even though older people experienced more time awake after sleep onset prior to treatment, they were able to profit from therapy as well as the younger insomniacs. Countercontrol therapy reduced the sleep complaint for the total group by about 30% at the end of treatment, with gradual improvement continuing through a 4-week follow-up. Nevertheless, it appears that sleep-maintenance insomnia may be more difficult to treat than sleep-onset problems.

Adult↗
PubMed1986

Measuring success in asthma care.

One hundred and twenty-six asthmatics in a practice of 4012 patients were interviewed at home by an undergraduate medical student. A questionnaire revealed a poor level of knowledge about asthma and its treatment. Inadequate understanding was found in 68% of parents with affected children and in 78% of adults with the disease. Treatment was thought to be sub-optimal in 32% of children and 37% of adults. Patients' symptoms were assessed on an asthma disability score of exercise limitation, night cough, wheezing episodes, time in hospital, and time off work or school. This enabled a profile of symptom severity in the sample to be constructed. The study has prompted the practice to re-examine its care of asthmatics so that diagnosis, treatment, education and supervision can become better organized.

Adolescent↗
PubMed1986

Mechanisms of triple stress-mediated damage in stationary phase cells of Salmonella typhimurium exposed to succinate-acidified hypochlorite system at 5 degrees C.

Exposure for 20 min of stationary phase cells of Salmonella typhimurium to a combined triple stress system (TSS) treatment comprising hypochlorite derived 5 ppm free available chlorine in solution acidified with 1% succinate (pH 2.5) and at a chill shock temperature of 5 degrees C resulted in symptoms of injury. Cells became sensitive to 40 micrograms/ml lysozyme, 50 micrograms/ml actinomycin D and 100 micrograms/ml ribonuclease B, to which control cells were resistant. Metabolic injury was indicated by reduction in colony forming ability of stressed cells on minimal salts glucose agar M9 medium. There was no detectable leakage loss of 260-280 nm-absorbing materials. This was also confirmed by assay of the cellular RNA material components. Loss of alkaline phosphatase activity was observed in the stressed cells. The intensity of induced cellular damage as measured by lysozyme sensitivity was greatest in the cells exposed to the complete TSS, followed by those stressed in 1% succinate at 5 degrees C, then 5 ppm chlorine at 5 degrees C and the singular chill shock stress at 5 degrees C, respectively. The magnitudes of cellular damage, however, were suggestive of synergistic interactions among the component stress factors of the TSS. The findings obtained indicated impairment of the structural integrity and functional capabilities of the permeability barriers and the inactivation of certain periplasmic enzymes. The resultant cumulative cellular damage from the TSS exposure may therefore enhance greater sensitivity of treated cells to subsequent stress factors.

Alkaline Phosphatase↗
PubMed1986

The destruction of Salmonella typhimurium in chicken exudate by different freeze-thaw treatments.

Antibacterial treatments for frozen poultry, including holding at -5 degrees C and slow thawing at 4 degrees C to which exponential phase cells of Salmonella typhimurium were susceptible, were found to be relatively ineffective against stationary phase cells. Exposure of the latter, however, to a pre-freezing triple stress treatment of cold-shock exposure at 5 degrees C to a solution containing 5 mg/l of free available chlorine in 1% succinic acid (pH 2.5) for 20 min substantially lowered the resistance of the cells to subsequent freezing, storage and thawing in poultry flesh exudate. Cell survival was further decreased by storage of exudate at -18 degrees C for 28 d and this reduced the proportion of stationary phase cells to less than 1% of initial numbers, with a concomitant increase in sensitivity to deoxycholate. Such a combined pre-treatment may have practical potential for salmonella decontamination in the production of frozen poultry.

Animals↗
PubMed1986

Relationship between growth and function of human thyroid cells in culture.

Subconfluent human thyroid cells in monolayer, isolated from thyrotoxic tissue or non-toxic goitres obtained at surgery, responded to the addition of epidermal growth factor (EGF) with an increase in cell growth as measured by increased incorporation of [3H]thymidine into trichloroacetic acid-precipitable material. The growth response to EGF was concentration-dependent and the characteristics of the responses were the same using EGF from murine or human sources. With concentrations which stimulated growth, EGF was found to inhibit human thyroid cell function as measured by the release of radioimmunoassayable tri-iodothyronine into the incubation medium. Thyrotrophin (TSH) was also found to stimulate human thyroid cell growth but at concentrations far lower than those used to stimulate thyroid cell function in this system. The effect of EGF on the differentiating action of TSH on human thyroid cells in culture was also investigated; the association of thyroid cells into two-dimensional follicular structures produced by the incubation of thyroid cells at a high cell density with TSH was found to be inhibited by the addition of EGF.

Cells, Cultured↗
PubMed1986

A low voltage diathermy loop for taking cervical biopsies: a qualitative comparison with punch biopsy forceps.

Twenty patients attending a colposcopy clinic because of a cytological suspicion of dyskaryosis were entered into a 'paired' biopsy study. A low voltage diathermy loop biopsy and a punch biopsy were taken from the cervix of each patient. In a second 'unpaired' study loop biopsies taken from 20 patients were compared with punch biopsies taken from 20 different patients. The length and depth of the loop biopsies were greater than those of the punch biopsies. There was no difference in the amount of artefactual damage. These findings held for both the paired and the unpaired studies. We conclude that biopsies taken with the low voltage diathermy loop are more likely to reveal microinvasive disease.

Biopsy↗
PubMed1985

An altered ratio of 18:2 (9,11) to 18:2 (9,12) linoleic acid in plasma phospholipids as a possible predictor of pre-eclampsia.

As a part of a larger study, 15 healthy primigravidas were studied from 28 weeks gestation until 3 days after deliver. In 6 of these women pre-eclampsia (PET) developed; the remaining 9 subjects, who were age matched had normal pregnancies. Plasma phospholipid-esterified 18:2(9,11):18:2(9,12)fatty acids were measured by high performance liquid chromatography (HPLC). The ratio of 18:2(9,11):18:2(9,12)linoleic acid was significantly higher in the PET group than in the normotensive group at 28 weeks' gestation--that is before the onset of symptoms and signs of PET. The ratio remained significantly higher in the PET group than in the normotensive group until deliver, except at 30 weeks when the difference between the ratios just failed to reach statistical significance. It is suggested that measurement of the ratio of 18:2(9,11) to 18:2(9,12)linoleic acid in plasma phospholipids may be useful as a predictor of the likely development of PET.

Chromatography, High Pressure Liquid↗