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Biomedical subjects

J Douglas

Publications and source records attributed to J Douglas.

At least 109 records · Page 6Linked to original sources
PubMed1986

Estimation of vitamin D3 and 25-hydroxyvitamin D3 in muscle and adipose tissue of rats and man.

An assay is described based on a high pressure liquid chromatography system for measurement of vitamin D3 and 25-hydroxyvitamin D3 concentration in adipose tissue and muscle. The sensitivity of the assay is less than 1 ng/g of tissue. Neither vitamin D3 nor 25-hydroxyvitamin D3 were found in tissues of vitamin D-deficient rats using this method. 25-Hydroxyvitamin D3 could not be detected in adipose tissue and very little was found in muscle of normal rats. The mean vitamin D3 concentrations in 15 samples of human perirenal adipose tissue was 45.3 ng/g +/- 22.2 (SD) and in 6 samples of axillary tissue 115.6 ng/g +/- 52.4 (SD). Human adipose tissue contains a substantial amount of vitamin D3 and its contribution to the maintenance of vitamin D status is discussed.

Adipose Tissue↗
PubMed1986

Interrelationships in rats of tissue pools of cholecalciferol and 25-hydroxycholecalciferol formed in u.v. light.

Vitamin D-deficient rats were irradiated with u.v. light three times weekly for 30 min for several weeks. D3 (cholecalciferol) and 25(OH)D3 (25-hydroxycholecalciferol) concentrations in skin, plasma, muscle and adipose tissue were measured. In other experiments, isolated skin or the whole animal was irradiated once and the cholecalciferol response monitored. Only a small fraction of the 7-dehydrocholesterol in skin is converted into D3 (less than 2%), and the presence of fur decreases the proportion converted into 20% of that occurring in shaved rat skin. D3 formed in the skin disappears relatively slowly, so that about 90% has gone after 7 days. In normal rats 10 micrograms of D3 formed over 2 h irradiation only caused a small rise in plasma D3 concentration over the following week, indicative of a high rate of clearance from this tissue. Irradiation of vitamin D-deficient rats for a prolonged period raised plasma D3 and 25(OH)D3 concentrations to a constant value. D3, but not 25(OH)D3, could be found in adipose tissue and muscle. Prolonged irradiation of normal rats showed these tissues and plasma could hold very large amounts of D3. Pharmacokinetic analysis of the changes in D3 concentration in rats showed that the disposition kinetics of D3 was explained by a two-compartment model with half-lives of 13.8 and 7.7 days. The volume of distribution of the more-slowly-turning-over compartment was 500 ml, which presumably reflects the large amounts of D3 that can accumulate in adipose tissue. Rat skin can synthesize about 0.85 ng of D3/mJ of u.v. light energy, but it seems that not all this is available to the rat. Adipose-tissue D3 is available for use by the rat, the t1/2 being 12.0 days.

Adipose Tissue↗
PubMed1985

Behavioural methods in the treatment of sleep disorders--a pilot study.

The efficacy of behavioural methods of treatment for severe sleep disorders was examined in a pilot study involving 35 children aged 1-5 years. Improvement occurred in 77%. Methodological issues concerning the selection of children for treatment, selecting adequate controls and outcome measures, and using parents as therapists, are discussed.

Behavior Therapy↗
PubMed1984

Hypothetical entropy-driven mechanism for self-regulation of the size and division of primitive cells, suggesting the origin and nature of mesosomes.

It is proposed that, when a critical cell radius was reached, spontaneous invaginations caused by adhesion of adjacent nodes in membranes rippled by Brownian bombardment, became progressive due to re-orientation of self-seeking molecules. Some circumstantial bacteriological evidence is adduced; the significance of mesosomes is discussed.

Animals↗
PubMed1984

The general utility of a glycerophosphate-Tris buffered medium.

An easily prepared medium, originally designed for the cultivation of lactic phages, has been found to have much wider application. Experience in its use over a ten year period with a range of physiologically diverse bacteria, for teaching and research are summarized and evaluated.

Antigens, Bacterial↗
PubMed1984

To catheterise or not to catheterise? An approach based on decision theory.

To determine whether or not patients require cardiac catheterisation before surgery a computer based mathematical model was constructed based on decision theory. The model was specifically applied to sick infants under 3 months of age with suspected coarctation of the aorta, and a three way sensitivity analysis was carried out to assess the effects on the model of changes in the probabilities that underlie the decision itself. The optimal decision (that with the greater survival rate) was moved away from cardiac catheterisation to confirm the diagnosis towards operating without cardiac catheterisation by the following factors: a higher probability of survival of operation both in the presence and absence of coarctation; a higher probability of survival if there was no coarctation and no operation performed; a lower sensitivity of catheterisation; a greater incremental risk of operation resulting from previous catheterisation; and a higher relative risk of catheterisation in patients without as opposed to with coarctation. Factors that tended significantly to move the decision towards catheterisation to rule out coarctation rather than neither to operate nor to catheterise were: a lower risk of surgery for coarctation if present; a higher risk of failing to operate on a patient who had coarctation; a high specificity of cardiac catheterisation; a lower incrementation of surgical risk by previous cardiac catheterisation; and a lower relative risk of catheterisation if coarctation was absent. In this institution, the model argues strongly against cardiac catheterisation in the great majority of sick infants with coarctation.

Aortic Coarctation↗
PubMed1984

Effect of prostaglandin on early surgical mortality in obstructive lesions of the systemic circulation.

To examine the effect of preoperative prostaglandin infusion on surgical mortality the records of all patients aged less than or equal to 28 days operated between January 1979 and December 1981 for obstructive lesions of the systemic circulation were reviewed. Forty patients had coarctation of the aorta, five interrupted aortic arch, and seven critical aortic stenosis. Fourteen patients received intravenous prostaglandin before operation. Among preoperative variables low cardiac output was identified as a possible risk factor for hospital death, whereas the presence of a raised blood urea concentration was possibly significantly associated with hospital mortality only in patients not treated with prostaglandin. The preoperative administration of prostaglandin had a strongly favourable influence: 11 out of 38 (29.0%) patients who did not receive prostaglandin died compared with none of 14 treated with prostaglandin. The two groups were otherwise comparable with respect to the incidence of coagulopathy, urgency of operation, associated anomalies, and other medical treatment. Mean age at operation was younger and mean admission blood urea concentration higher in the group treated with prostaglandin, whereas the incidence of preoperative low cardiac output was probably higher. It is concluded that short term preoperative infusion of prostaglandin in associated with a significant reduction in early surgical mortality in this high risk group of infants.

Alprostadil↗
PubMed1983

Treatment of primary first-episode genital herpes simplex virus infections with acyclovir: results of topical, intravenous and oral therapy.

Three double-blind, placebo-controlled evaluations of acyclovir were performed in first-episode genital herpes infections. In one trial intravenous acyclovir or saline was administered in hospital over 5 days. In the other two trials, 10-day courses of oral, or 7-day courses of topical acyclovir and respective placebos were followed up in the outpatient department. Regular assessments included staging examinations, culture of lesions and blood and serum analyses. No patient discontinued medication because of an adverse reaction, although one quarter of topically treated patients complained of local irritation on application. The placebo-controlled evaluations indicate that, if given within the first 7 days after the onset of lesions, topical, intravenous and oral acyclovir are useful in shortening the course of first-episode primary genital herpes. The clinical and virological effects of intravenous and oral acyclovir were more marked than those of topical treatment in the reduction of viral shedding; the time to complete healing of lesions; and in the reduction of new lesion formation. Systemic preparations of acyclovir also decreased the symptoms of herpes simplex virus urethritis and intravenous acyclovir those of herpes simplex virus cervicitis. Neither systemic treatment, however, was effective in delaying or reducing the frequency of subsequent recurrences, which may be related to the development of early ganglionic infection. Despite this, acyclovir treatment is a significant advance in the management of primary genital herpes.

Acyclovir↗
PubMed1983

Should coronary arteries with less than 60% diameter stenosis be treated by angioplasty?

We evaluated all patients receiving percutaneous transluminal coronary angioplasty (PTCA) in the past year for mild stenosis (60% or less diameter narrowing, n = 64, group 1) and compared them with a random sample of 330 patients with greater than 60% stenosis (n = 66, group 2) treated during the same year. The degree of coronary stenosis before PTCA was 52 +/- 7% (mean +/- SD) in group 1 and 79 +/- 11% in group 2. The primary success rate was 90% (58 of 64 patients) in group 1 vs 86% (57 of 66 patients) in group 2. The incidence of complications requiring coronary surgery after PTCA failed was similar in both groups (3 of 64 in group 1, 4 of 66 in group 2), but there were four occurrences of myocardial infarction in group 1 and none in group 2 (p less than .05). Recurrence of stenosis was judged on the basis of objective data, 76% of which were angiographic data, in 97% of the patients with primary success. At a mean interval of 5 months with a mean follow-up period of 7 months, 17 of 58 patients (29%) with primary success in group 1 and 24 of 57 patients (42%) in group 2 developed restenosis. In group 1, restenosis was markedly more severe (73 +/- 15%) than initial stenosis (p less than .005), which was not the case in group 2. In conclusion, PTCA in mild stenosis has favorable primary and long-term results, yet carries the risk of myocardial infarction and emergency operation and may, in some cases, even accelerate the disease process.

Adult↗
PubMed1983

Influence of augmented Hageman factor (Factor XII) titers on the cryoactivation of plasma prorenin in women using oral contraceptive agents.

Prolonged cold storage of plasma may induce the conversion of plasma prorenin (inactive renin) to renin. This phenomenon is exaggerated in oral contraceptive (OC) users; the titer of Hageman factor (HF, Factor XII) in OC users is higher than in nonusers. The present study relates these observations. The increment in plasma renin activity (PRA) during cold storage, as measured by generation of angiotensin I, correlated strongly with the initial plasma titer of HF. Increasing the HF titer of nonusers to that observed in OC users by addition of purified HF increased cold-induced PRA at least twofold, while reducing the plasma HF titer of OC users correspondingly decreased cold-induced PRA. Thus, in OC users, the enhanced conversion of plasma prorenin to renin during cold storage reflects the elevated plasma titer of HF.

Angiotensin I↗
PubMed1982

A method for isolation and culture of lymphocytes from endoscopic biopsies.

Human small and large intestinal lamina propria lymphocytes have been successfully prepared from endoscopic biopsies by a combined enzymatic and mechanical method which gives higher yields of viable mucosal lymphocytes than previously reported, despite the small size of the biopsy samples. Viability of the cells was demonstrated by dye exclusion and they could be satisfactorily maintained in short-term culture. Phytohaemagglutinin-P (PHA-P) transformation characteristics of intestinal lymphoid cells and those of peripheral blood were studied in 20 patients with Crohn's disease and 10 control subjects. Peripheral blood lymphocytes were separated according to this technique, no decrease in viability being observed when compared to a standard Ficoll-Hypaque gradient technique. Endoscopically abnormal (EA) and endoscopically normal (EN) Crohn's tissue showed significantly different responses to PHA-P (P less than 0.001), EA tissue lymphocytes giving lower blastogenic responses.

Adolescent↗
PubMed1982

Electron microscopy of Streptococcus lactis phage plaque margins.

Ultrathin sections of plaques produced by Streptococcus lactis phages O712 and m13 were examined by transmission electron microscopy. The clear central area of the plaque was found to contain hardly any cellular material but the turbid margin contained abundant plasma membranes and some partially lysed cells whose appearance suggests a novel mechanism for the termination of plaque growth.

Bacteriolysis↗