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Biomedical subjects

L Walters

Publications and source records attributed to L Walters.

At least 55 records · Page 3Linked to original sources
PubMed1988

Vitamin B6 nutritional status in asthma: the effect of theophylline therapy on plasma pyridoxal-5'-phosphate and pyridoxal levels.

Plasma pyridoxal-5'-phosphate concentrations were significantly lower (p less than 0.001) in a group of 28 asthmatic women when compared to 33 controls. Plasma pyridoxal levels in the two groups were not different. Theophylline was administered to a group of 17 volunteers and resulted in large reductions in plasma pyridoxal-5'-phosphate levels, while plasma pyridoxal levels and urinary 4-pyridoxic acid excretion were unaffected by theophylline therapy. An in vitro study showed that theophylline did not interfere with the high performance liquid chromatography assay for pyridoxal-5'-phosphate, indicating that theophylline could affect liver metabolism of vitamin B6.

Adolescent↗
PubMed1988

The effects of anticholinergics on the photopalpebral reflex, memory and mood.

This study investigated central anticholinergic drug effects on: (1) the Randt Memory Test, a relatively new instrument which measures the acquisition and recall of verbal and pictorial information; (2) the averaged photopalpebral reflex (PPR), an electrophysiological parameter, the validity of which needs to be further investigated in pharmacological research and; (3) mood as measured by a 16-item visual analogue scale. Atropine (1 mg and 2 mg), pirenzepine (20 mg) and a placebo were administered intramuscularly in a double-blind cross-over trial in eight healthy volunteers. There were no inter-treatment differences on the Randt Memory Test. This finding is seemingly in contrast to those reported by some authors using other memory tests. In contrast to the reported effects of some benzodiazepines, the anticholinergics used in the present study did not prolong the latencies of the PPR, but reduced the amplitudes. Visual analogue scales indicated central effects for both pirenzepine and atropine. This implies pirenzepine's penetration of the blood-brain barrier and a physiological function for central muscarinic-1-receptors. The significant anticholinergic effects were exclusive to the "alertness" factor.

Adult↗
PubMed1987

Test-tube babies: ethical considerations.

This essay reviews 15 statements on the ethics of in vitro fertilization (IVF) and embryo transfer that were produced between 1979 and 1985. The statements represent the deliberations and conclusions of committees from Australia, Western Europe (including the United Kingdom), Canada, and the United States. From 1979 through the early 1980s, 18 first-generation issues predominated in the ethical discussion. In the mid-1980s eight second-generation issues involving clinical IVF have emerged.

Advisory Committees↗
PubMed1986

Ethical issues in intrauterine diagnosis and therapy.

This essay considers ethical problems raised by recent developments in intrauterine diagnosis and therapy. Diagnostic and therapeutic innovations applicable to the previable fetus and to the possibly viable or viable fetus are briefly described. A central ethical issue prior to viability is whether intrauterine therapy for fetal health problems should be attempted or whether selective abortion should be chosen as an alternative. Beyond viability, an important question is the extent to which a pregnant woman is morally obligated to accept risks to her own life or health for the sake of the fetus.

Congenital Abnormalities↗
PubMed1984

When is termination of pregnancy during the third trimester morally justifiable?

The question whether to terminate pregnancy during the third trimester involves a moral conflict. We argue that such termination is morally justifiable if two conditions are fulfilled: first, that the fetus is afflicted with a condition that is either incompatible with postnatal survival for more than a few weeks or characterized by the total or virtual absence of cognitive function; and second, that highly reliable diagnostic procedures are available for determining prenatally that the fetus fulfills either of the two parts of the first condition. At present, one entity, anencephaly, clearly fulfills both conditions. We studied 10 cases involving fetuses with sonographically diagnosed anencephaly that were aborted during the third trimester. We also examined other fetal disorders and conclude that they do not clearly fulfill our two conditions for the justifiable termination of pregnancy in the third trimester.

Abortion, Induced↗
PubMed1984

A career ladder for radiological technologists.

A career ladder is a mechanism for employee progression within a chosen field. This paper describes the design and implementation of such a system in a large community radiology department. The career ladder system included integrated job descriptions, salary scales and evaluation procedures for radiology technologists. The implementation of this new system had a positive effect on employee morale manifested in decreased turnover, less absenteeism and increased job satisfaction.

Career Mobility↗
PubMed1983

Beta-adrenergic blocking drugs and renal function.

A baboon model was used to investigate the effects of atenolol, nadolol, sotalol and labetalol on renal function. The glomerular filtration rate (GFR) and renal blood flow (RBF) were measured, using radionuclides and a gamma camera, before and after 1 week's oral administration of these drugs. All the drugs caused an increase in the GFR, but this reached statistical significance only in the cases of sotalol (P less than 0,025) and labetalol (0,05 less than P less than 0,10). The RBF was not significantly changed, although it decreased in all cases.

Adrenergic beta-Antagonists↗
PubMed1983

Pharmacokinetics of ceftazidime in male and female volunteers.

The pharmacokinetic behavior of ceftazidime was assessed after single bolus intravenous injections of 1 g to 12 male and 12 female volunteers. The kinetic handling of the drug was essentially identical in the two sexes, exhibiting two-compartment model characteristics. However, the peripheral compartment volume of distribution of ceftazidime was smaller in the females (mean 3.95 liters, compared with 6.15 liters), and this was attributed to a smaller extracellular fluid volume. Eight volunteers in each group also received single 1-g doses of ceftazidime into the vastus lateralis and gluteus maximus muscles. The time to peak concentration was longer in the women, and it was longer after injection into the gluteus maximus in both sexes, presumably because of differences in local blood flow. The bioavailability of ceftazidime may have been slightly reduced by delays in absorption. Again, body and renal clearances were similar for both sexes when allowance was made for differences in distribution volume.

Absorption↗
PubMed1982

The effects of lithium on the functions of human neutrophils and lymphocytes in vitro and in vivo.

The effects of lithium sulphate (LiSO4) at concentrations ranging from 10(-7)M to 10(-2)M on human polymorphonuclear leucocyte (PMNL) and lymphocyte functions in vitro were investigated. The leucocyte function assessed were PMNL motility, post-phagocytic hexose-monophosphate shunt activity, myeloperoxidase-mediated iodination of Candida albicans and lymphocyte transformation to mitogens. These same functions as well as the results of serological studies were assessed in normal volunteers prior to ingestion of lithium carbonate (LiCO3), 2 hours and 24 hours after the ingestion of a single oral dose of 480 mg LiCO3, and on the 4th day of ingestion of 2 X 480 mg LiCO3 tablets daily. Incubation of PMNL with LiSO4 at concentrations up to 10(-3)M had no detectable effects on motility or post-phagocytic metabolic activity. Higher concentrations (10(-3)M) inhibited these functions. Likewise, at concentrations up to 1 X 10(-4)M LiSO4 had no effects on mitogen-induced transformation of lymphocytes, although higher concentrations did inhibit this activity. These same leucocyte functions were unaffected by ingestion of LiCO3. Levels of serum immunoglobulins and complement components, total haemolytic complement activity and salivary IgA values also remained unaltered. In vitro investigations showed that at a concentration of 10(-3)M LiSO4 had no inhibitory effects on the stimulation of PMNL motility mediated by ascorbate, levamisole and thiamine.

Adult↗
PubMed1982

[Drug kinetics in patients with renal failure].

Dosages must be adjusted in patients with renal failure because they absorb, distribute and eliminate drugs differently from healthy people. There is a danger of accumulation of drugs or their active metabolites in these patients. A normal loading dose is required in order to achieve a therapeutic drug concentration within a reasonable time. The maintenance doses of drugs with a narrow therapeutic index should be adjusted according to the changes in the serum drug levels. The maintenance doses of other drugs could be calculated according to the patient's glomerular filtration rate.

Absorption↗
PubMed1982

Preventing hyperphagia normalizes 3-hydroxy-3-methylglutaryl-CoA reductase activity in small intestine and liver of diabetic rats.

Rats with streptozotocin-induced diabetes stop growing, develop high cholesterol and triacylglycerol levels in plasma, and have decreased activity of the rate-limiting enzyme in cholesterol synthesis, 3-hydroxy-3-methylglutaryl CoA reductase (EC 1.1.1.34), in liver and increased activity in small intestine. They also eat more than normal. To determine the contribution of hyperphagia to these changes in lipid metabolism, we restricted intake of chow to the amount eaten ad lib by normal rats. Rats were meal-fed for 8 or 22 days from the time diabetes was induced. This regimen normalized reductase activity in both liver and intestine at mid-dark and mid-light, and all but eliminated high plasma cholesterol and triacylglycerol levels, although plasma insulin remained low and glucose remained high. Activation of hepatic reductase by endogenous phosphatase in vitro was reduced in hyperphagic diabetic rats but was normal in diabetic rats eating a normal amount of food. We conclude that hyperphagia, rather than direct effects of insulin deficiency as is usually assumed, is responsible for perturbations of lipid metabolism in chronically diabetic rats. These results support the proposal that hyperphagia increases the input of dietary and newly synthesized cholesterol from the small intestine, and that this increased input raises plasma cholesterol level and inhibits reductase activity in liver.

Animals↗
PubMed1981

Pharmacological requirements of patients during alcohol withdrawal.

A randomly selected group of alcoholics who reported for treatment was tested for blood alcohol and benzodiazepine values. Only 30% of patients had significantly high alcohol levels, but 20% had concomitant significantly high alcohol and benzodiazepine levels. These factors should be taken into account if pharmacotherapy is to be instituted for similar patients.

Alcoholism↗
PubMed1981

[The addiction potential of benzodiazepines. Application of the results of treatment of alcohol withdrawal syndrome].

A benzodiazepine withdrawal syndrome was demonstrated in this study. It occurred more frequently with use of the short-acting type of benzodiazepine and approximately 26 hours after discontinuing the regular intake of the drug as compared with approximately 4 days after stopping the regular intake of the long-acting type of benzodiazepine. These findings have a special significance in the treatment of the alcohol withdrawal syndrome, since 30% of alcoholics have been shown to have a regular intake of one of the benzodiazepines and since these are the drugs of choice in the treatment of the syndrome.

Alcohol Withdrawal Delirium↗