Search PubMed⌕ Search

Biomedical subjects

C Williams

Publications and source records attributed to C Williams.

At least 541 records · Page 30Linked to original sources
PubMed1986

Preservation of endothelium-dependent vascular relaxation in cholesterol-fed rabbit by treatment with the calcium blocker PN 200110.

We tested the effects of low doses of a dihydropyridine calcium antagonist, PN 200110, on endothelium-dependent vascular relaxation in rabbits fed a 1% cholesterol diet. The drug was given orally, 1 mg/day, and control rabbits received placebo. Plasma total cholesterol after 10 weeks, was similar in the placebo- and PN 200110-treated groups. The respective values averaged 2140 +/- 116 (n = 14; mean +/- SEM) and 2012 +/- 115 mg/dl (n = 13). In placebo-treated rabbits, sudanophilic aortic lesions covered 52 +/- 5% of the intimal surface, and the aortic cholesterol concentration was 72 +/- 6 mg/g protein. Corresponding values in aortas from PN 200110-treated rabbits were significantly lower [36 +/- 5% (P less than 0.03) and 52 +/- 3 mg/g protein (P less than 0.03)]. Maximal endothelium-dependent cholinergic relaxation of aortic strips in untreated (n = 14) and treated cholesterol-fed rabbits (n = 13) differed significantly (P less than 0.01) and averaged 31 +/- 4% and 61 +/- 7% of the value in normocholesterolemic controls (n = 13). We conclude that cholesterol feeding suppresses endothelium-dependent relaxation evoked by acetylcholine, and that PN 200110 reduces the severity of atherosclerosis and impairment of endothelium-dependent relaxation.

Animals↗
PubMed1986

The relationship between fluoride effects on bone histology and on bone mass in patients with postmenopausal osteoporosis.

Twenty-one patients with postmenopausal osteoporosis were studied for 4 years after initiation with sodium fluoride (NaF), 20-25 mg b.i.d., elemental calcium, 1.0 g/day, and vitamin D2, 50,000-100,000 I.U. weekly. Histomorphometry was carried out on bone biopsies taken prior to and while on NaF treatment. The total bone mineral mass of the central third of the skeleton was measured by neutron activation analysis at 0.5-1.0 year intervals, and the result expressed as the Calcium Bone Index (CaBI), which normalizes the mineral mass to values for normal subjects of the same size. Twelve patients (57%) who developed, within the first 2 years of treatment, histological effects of fluoride (F) (increased bone formation surfaces together with thickened osteoid seams or hyperosteoidosis) increased their CaBI significantly (P less than 0.01) over the 4 year period, from 0.64 +/- 0.02 to 0.78 +/- 0.03 (or 21.0 +/- 2.9%). No other agent is known to stimulate bone growth to this degree. The remaining nine patients showed no histological evidence of F stimulation and no increase in CaBI (from 0.67 +/- 0.03 to 0.66 +/- 0.03 over 4 years). The results suggest that the histological findings of hyperosteoidosis are prerequisite for the increases in bone mass of osteoporotic patients. Although serum and bone F levels were higher in patients with F response compared to those without response, there was considerable overlap in values between the two groups so that these parameters of F retention were not reliable for predicting F response. Histological evidence of hyperosteoidosis appears to be a more reliable predictor of subsequent increase in bone mass. The effect on fracture prevention of the hyperosteoidosis associated with the increases in bone mass remains to be shown.

Aged↗
PubMed1986

Analysis of pharmacokinetic profiles in 232 renal and 87 cardiac allograft recipients treated with cyclosporine.

Analyses of cyclosporine (CsA)-related compounds (Cs) using the radioimmunoassay method were performed by 232 profiles in renal and 87 profiles in cardiac allograft recipients. Cardiac allograft recipients tended to have an increased, dose-corrected area under the concentration (AUC) v time curves after oral and, particularly, intravenous CsA administration, to display a slower drug clearance rate, and to have a slightly smaller volume of distribution. The impact of age, sex, hepatic impairment, nephrotoxicity, and concomitant corticosteroid dose could be discerned within the large number of studies in renal recipients. Only nephrotoxic cardiac transplant patients showed a significant alteration of increased AUC:dose and drug half-life compared with patients with normal renal function, a similar change to that observed in nephrotoxic renal transplant patients. Pediatric compared with adult renal recipients showed a threefold increased rate of mean drug clearance, namely 39.6 mL/min/kg in children v 12.3 mL/min/kg in adults, which may explain the almost 50% reduction in area under the plasma concentration curve v the time curve. There also appeared to be somewhat better oral absorption of CsA by children. Study of greater numbers of cardiac transplant recipients will be necessary to detect the subtle impact of demographic factors on pharmacokinetic parameters.

Adult↗
PubMed1985

Comparison of eight phenytoin dosing methods in institutionalized patients.

Until now, no evaluation of phenytoin dosing methods has been undertaken in a large group of patients, to our knowledge. The goal of this study was to determine which of eight different dosing methods most accurately predicts a phenytoin steady-state concentration. Seventy-six patients were chosen, retrospectively, from a state-funded institution for the mentally retarded. Eligibility criteria included two or more different doses of phenytoin and corresponding plasma concentrations. Relative predictive performance was determined by comparing results of simple linear regression. Also, relative bias and precision were determined by comparing mean prediction errors, root mean squared errors, and respective 95% confidence intervals. Of the methods requiring one dose-concentration pair, Rambeck's nomogram was the best predictor of phenytoin concentrations. The methods requiring two known doses and plasma concentrations were more accurate. Their predictive performance was equivalent, although use of the Tozer equation might be preferred for its convenience. None of the methods tested were sufficiently precise to substitute for confirmatory serum phenytoin concentrations.

Adolescent↗
PubMed1985

Paradoxical air embolism during neurosurgery.

Four cases of air embolism which occurred during neurosurgical procedures in the sitting position are described, in whom the signs could be due to air in the coronary or cerebral arteries. It is suggested that, during venous air embolism in the sitting position, a significant number of patients are haemodynamically at risk from paradoxical air embolism, and that the serious consequences of venous air embolism in neurosurgery may be due to this.

Aged↗
PubMed1985

Is the scrotal testis normal in unilateral cryptorchidism?

Bilateral testicular biopsies were performed on 66 children undergoing orchiopexy for unilateral cryptorchidism and the tubular fertility index (TFI) recorded. The results in both the descended and undescended testes at various ages were compared with previously reported control data. There were no significant differences between the germ cell activity of the scrotal testis in cases with unilateral cryptorchidism and that of controls. By contrast, the mean TFI of the undescended testis was significantly less than that of control patients of all ages. In neither group was there evidence of a progressive loss of germ cell activity during childhood. It is concluded that there is little to be gained from very early orchiopexy, performed before the third year of life.

Adolescent↗
PubMed1985

Teaching nursing homes: their impact on public policy, patient care, and medical education.

In summary, teaching nursing homes can be expected to have an impact on public policy development, patient care, and physician training. It is anticipated that research into the important public policy issues regarding relationships between costs and proprietary status and quality of care will be enhanced by developing teaching nursing homes. It will be important to coordinate efforts and evaluations between pilot projects with different funding bases in order to provide research projects with adequate controls. Many results regarding cost-quality comparisons may be of limited applicability to community institutions because of the higher costs inherent to teaching facilities. Nursing home patients living in teaching facilities can expect to be directly benefitted in terms of receiving increased medical attention. They will reside in model facilities providing what is hoped to be the optimal services in all aspects of nursing home care. Possible detrimental aspects for such patients include increased exposure to heroic interventions and possibly poorer care as a result of medical interference with established nursing home team approaches to patient care. As a result of living in a research environment, patients also may be pressured to participate in protocols to which they are not normally exposed. In addition, because many of the geriatric fellowships are based in Veterans Administration facilities (with their predominantly male patient population), it will be important to ensure that current research adequately studies the common problems of elderly women, who represent 70 per cent of those who are in nursing homes.(ABSTRACT TRUNCATED AT 250 WORDS)

Education, Medical↗
PubMed1985

A laboratory running test: metabolic responses of sprint and endurance trained athletes.

A laboratory-based sprint running test has been devised to examine the performance characteristics and metabolic responses of an individual to 30 seconds of maximal exercise. A non-motorised treadmill was used so that the individual was able to sprint at his own chosen speed and also to vary his speed as fatigue occurred. The treadmill was instrumented so that the chosen speeds as well as the equivalent distance travelled could be monitored by micro-computer throughout the test. The test-retest reliability of the procedure was investigated with 14 recreational runners who performed the test on different days. A good correlation (r = 0.93) was found between the values obtained for peak running speeds on the two occasions. In an attempt to establish whether or not this test could be used to identify the differences in the performance characteristics of highly trained individuals, the responses to the test of eleven sprint trained and eleven endurance trained athletes were examined. The sprint trained athletes covered a greater distance (162.2 +/- 5.95 m vis 153.51 +/- 12.32 m; p less than 0.01) and had higher blood lactate concentrations (16.52 +/- 1.23 mM vis 12.98 +/- 1.77 mM; p less than 0.01) than the endurance trained athletes. Therefore this laboratory sprint running test offers an additional way of investigating human responses to brief periods of high intensity exercise.

Adult↗
PubMed1985

Monocyte procoagulant activity in glomerulonephritis associated with systemic lupus erythematosus.

Monocyte infiltration and activation of the coagulation system have been implicated in the pathophysiology of glomerulonephritis. In this study, spontaneous procoagulant activity (PCA) was measured in circulating mononuclear cells to determine whether elevated PCA correlated with the presence of proliferative glomerulonephritis in patients with systemic lupus erythematosus (SLE). No increase in PCA was found in 20 patients with end-stage renal failure, 8 patients with glomerulonephritis without SLE, and 10 patients undergoing abdominal surgical or orthopedic procedures as compared with 20 normal controls. In eight patients with SLE but with no apparent active renal disease, PCA was not elevated above normal basal levels. Seven additional patients with SLE who had only mesangial proliferation on biopsy also had no increase in PCA. In contrast, eight patients with focal or diffuse proliferative lupus nephritis, and one patient with membranous nephritis who ultimately developed a proliferative lesion, had a marked increase in PCA with greater than 100 times the base-line levels. The activity was shown to originate in the monocyte fraction of the mononuclear cells and was shown to be capable of cleaving prothrombin directly. The prothrombinase activity was not Factor Xa, because it was not neutralized by anti-Factor X serum and was not inhibited by an established panel of Factor Xa inhibitors. Monocyte plasminogen activator determinations did not correlate with renal disease activity. We conclude that monocyte procoagulant activity, a direct prothrombinase, seems to correlate with endocapillary proliferation in lupus nephritis and could be a mediator of tissue injury.

Blood Coagulation Factors↗
PubMed1985

Two successive outbreaks of Clostridium perfringens at a state correctional institution.

An outbreak of acute gastrointestinal illness of short duration involving 100 inmates at a correctional institution followed a similar outbreak among the same population by eight days. Clostridium perfringens was the specific etiology in both outbreaks; the vehicle was roast beef in the first outbreak, ham in the second. Direct observation of food handling practices revealed that the meats were not cooled quickly enough following cooking; not reheated adequately prior to serving, and; held at improper temperatures prior to serving.

Animals↗