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Biomedical subjects

A Heath

Publications and source records attributed to A Heath.

At least 73 records · Page 4Linked to original sources
PubMed1990

Report of a collaborative study for assessing the potency of hepatitis B vaccines.

A collaborative study was carried out to examine the suitability of a hepatitis B vaccine derived from plasma as an immunogenicity reference for vaccines produced by recombinant DNA technology in yeast. The use of a plasma derived vaccine as reference appeared satisfactory, although the use of homologous reference improved agreement in potency estimates. The use of a recombinant standard did not however improve agreement for a recombinant vaccine produced by a different manufacturer. The variation in the dilution of vaccine required to induce antibodies in 50% of test animals and in potency estimates varied widely between laboratories (25-fold and 10-fold respectively). However this was similar to the variation found in a previous collaborative study.

Animals↗
PubMed1988

Clinical and metabolic features of ethanol-methanol poisoning in chronic alcoholics.

The kinetics of methanol were examined in 84 chronic alcoholics admitted after drinking a cleansing solution containing 90% ethanol and 5% methanol. On admission, the average blood methanol concentration was 20 mmol/l (64 mg/dl) and blood ethanol concentration was 39 mmol/l (179 mg/dl). Although these patients were not treated with ethanol, and methanol concentrations remained high as blood ethanol concentrations fell to zero, no acidosis or other signs of classic methanol poisoning developed. The rate of metabolism of methanol was correlated to the initial ethanol concentration. To avoid unnecessary invasive therapy, treatment of methanol poisoning should be based on the case history, clinical signs, and laboratory features-not solely on blood methanol concentrations.

Adult↗
PubMed1988

Effects of naloxone and verapamil in experimental amitriptyline poisoning in rats.

The effects of verapamil and naloxone as potential antidotes for amitriptyline-induced cardiotoxicity were investigated in an experimental rat model. Amitriptyline was infused continuously at a dose of 37.5 mg/kg/h. After 15 minutes, the animals were given either naloxone (2 mg/kg + 3 mg/kg/h), verapamil (0.08 mg/kg + 0.08 mg/kg/h), or physiological saline. In the group given naloxone, a significant decrease in heart rate was seen. Although MAP and max dP/dT increased, there was no significant difference from controls. Naloxone did not decrease mortality. When the bolus dose of verapamil was given, a significant decrease in MAP and max dP/dT was obtained. Although the mean blood pressure was significantly higher in those animals treated with verapamil who survived 60 minutes, verapamil did not change the course of the amitriptyline poisoning. In conclusion, our findings indicate that naloxone lacks significant positive effects and that verapamil has an additional negative inotropic effect. Neither drug can be recommended for the treatment of amitriptyline poisoning.

Amitriptyline↗
PubMed1988

Activated charcoal in tricyclic antidepressant poisoning.

Tricyclic antidepressants (TCA) bind to activated charcoal both in vitro and in vivo in healthy volunteers after a therapeutic dose of TCA. These findings provide a basis for the routine use of activated charcoal in TCA poisoning. The object of this study was to examine the effect of a single dose of 20 g of activated charcoal in overdose patients. Ninety-one patients from four centres with suspected TCA overdose were entered into a randomized study. Gastric lavage was performed on all patients. Thirty-four received 20 g of activated charcoal and 43 served as controls. Fourteen patients were excluded. Plasma drug concentrations were taken on admission and at 1, 2, 4, 8 and 24 h. The incidence of toxic symptoms was registered during 24 h. There was no significant difference in the area under the plasma drug concentration versus time curve, the peak plasma concentrations or plasma half-lives between the two groups. Toxic symptoms were more frequent in the non-treated groups although this difference was not statistically significant. In patients with TCA overdose initially treated with gastric lavage, a single dose of 20 g of activated charcoal had no effect on the systemic absorption or elimination of TCA.

Antidepressive Agents, Tricyclic↗
PubMed1988

Severity grading in self-poisoning.

1. The reliability and validity of three different coma scales was studied in 26 patients with acute drug overdose. 2. A comparison of six painful stimulation techniques showed that sternal rubbing and retromandibular pressure were most effective. 3. The improper use of stimulation techniques may underestimate level of responsiveness in 4-19% of cases. 4. The Reaction Level Scale (RLS) was the most reliable scale. 5. Both the RLS and the Glasgow Coma Scale may be unnecessarily complicated for the evaluation of the drug overdose patient, but should be chosen if concomitant brain injury is suspected. 6. This study confirms the basic concepts and shows the reliability of the Matthew-Lawson scale for use in the poisoned patient.

Adult↗
PubMed1988

Clonidine interaction in amitriptyline poisoning.

The effect of clonidine on amitriptyline-induced cardiotoxicity was investigated in an experimental rat mode. A continuous infusion of amitriptyline (30 mg/kg/h) was given until the animal died, usually within 2 hours. Fifteen minutes after starting the amitriptyline infusion, 50 micrograms/kg of clonidine was given intravenously over five minutes. This led to an increase in blood pressure and left ventricular end-diastolic pressure. There was no significant change in cardiac contractility. Heart rate decreased. These changes can be explained by an increase in afterload due to peripheral vasoconstriction. No signs of reduced sympathetic outflow were seen on the ECG. The peripheral effects of clonidine dominated over the central effects, which may be due to a competitive inhibition of amitriptyline at central noradrenergic sites. An increased afterload pushes the heart towards failure and increases mortality. In this model, clonidine did not reverse amitriptyline-induced cardiovascular toxicity. It may even be potentially harmful if used to treat tricyclic antidepressant poisoning.

Amitriptyline↗
PubMed1987

Terbutaline concentrations in self-poisoning: a case report.

A young female patient was admitted twice within two months, each time after an overdose of 500 mg terbutaline. Clinical features included nausea, tachycardia, tremor, hyperglycemia and hypokalemia. Although plasma concentrations of terbutaline were at least 50 times the normal therapeutic level, after potassium substitution the outcome was uneventful.

Adult↗
PubMed1986

Symptoms of anxiety and depression in a volunteer twin population. The etiologic role of genetic and environmental factors.

We examined the etiologic role of genetic and environmental factors in 14 symptoms of anxiety and depression reported by 3,798 pairs of adult twins from the Australian National Health and Medical Research Council Twin Register. Multifactorial multiple-threshold models fit the individual symptom scores well. For a substantial majority of the symptoms, the variance in liability was best explained by only genetic factors and environmental influences specific to the individual, where 33% to 46% of the variance was due to genetic factors. For four symptoms, it was not possible to choose definitively between models that, in addition to specific environment, included genetic vs familial environmental effects. These results provide strong evidence for the role of genetic factors in the etiology of symptoms of anxiety and depression as reported in a general population. Evidence for an etiologic role of familial environmental factors was much weaker. If familial environmental factors play any role in the production of these symptoms, they are more important in symptoms of depression than of anxiety, and the factors that predispose to these symptoms are only modestly correlated in males and females.

Adult↗
PubMed1986

Haemoperfusion: a useful therapy for a severely poisoned patient?

Although it is many years since a haemodialysis and haemoperfusion over uncoated and later coated charcoal columns have been used for the treatment of intoxicated patients, the clinical efficacy of these extracorporeal techniques in the treatment of severely poisoned patients remains a matter of debate. Some of the reasons for this controversy may be the indiscriminate use of haemoperfusion in any form of intoxication, the lack of well-controlled studies and the wrong interpretation of the high haemoperfusion clearance values sometimes obtained. Simple pharmacokinetic principles are applied to this type of treatment and some practical guidelines as to how and when haemoperfusion should be applied or presented are reviewed. The limited place of haemoperfusion in the treatment of severe poisoning, its further declining use in the future, at least in its present design, and some promising new treatments are emphasized.

Forecasting↗
PubMed1986

Does alcohol absorb to activated charcoal?

Activated charcoal seldom is used in pure-alcohol poisoning since it is absorbed rapidly from the gut. Furthermore in early reports activated charcoal was found to adsorb alcohol poorly. However, in 1981 North et al. [North, D. S., Thompson, J. D. & Peterson, C. D. (1981). Am. J. Hosp. Pharm., 38, 864-866] demonstrated in dogs that charcoal given at the same time as alcohol can reduce the blood alcohol concentration significantly. To study whether charcoal is of value in a clinical situation, a randomized cross-over study in two phases was conducted. Each person drank 88 g of alcohol and 30 min after either 20 g of activated charcoal was taken or the same volume of water was drunk. There were no significant differences in plasma alcohol concentrations with or without charcoal.

Adsorption↗
PubMed1985

Thioridazine toxicity--an experimental cardiovascular study of thioridazine and its major metabolites in overdose.

Thioridazine, thioridazine side chain sulfoxide, side chain sulfone and ring sulfoxide were each given to two dogs in incremental doses. Profound changes in cardiac output and blood pressure were seen only in the dogs receiving the ring sulfoxide. Although all four drugs increased the QRS and Q-Tc interval, ventricular arrhythmias and "torsades de pointes" were seen only in dogs receiving the ring sulfoxide. Total plasma concentrations of thioridazine ring sulfoxide were in the same range as those seen in some patients on thioridazine therapy although the free concentrations were higher. Thioridazine ring sulfoxide appears to be the most toxic metabolite of thioridazine.

Animals↗