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Biomedical subjects

E Woo

Publications and source records attributed to E Woo.

13 recordsLinked to original sources

Myasthenia gravis in Hong Kong Chinese. 1. Epidemiology and adult disease.

A territory-wide study of myasthenia gravis (MG) was conducted in Hong Kong. Two hundred and sixty-two Chinese patients (159 adult and 103 paediatric onset) were identified, corresponding to a point prevalence and period prevalence of 53.5 and 62.2 per million respectively, and an average annual incidence of 4.0 per million population. Nine patients died, 7 from MG, giving a case fatality rate of 0.027. Female predominance was present in the whole group of patients (female to male ratio 1.6:1) and in those with adult disease (ratio 2.1:1), but not in those with onset in childhood (ration 1.1:1). Onset of disease was most common in the first 3 decades of life, and became less common in subsequent decades. Juvenile onset MG occurred in 39.3% of patients and restricted ocular MG in 47.9%. Familial occurrence was found in 5 patients. In the 159 adult onset patients, ocular disease was most common (32.7%), followed by mild generalised (29.6%), moderately severe generalised (24.5%), fulminating (11.9%) and late severe disease (1.3%). The mean age of onset of symptoms was 36.7 years. The symptomatology was similar to that of Caucasoid populations. Autoimmune thyroid disease was the commonest associated disease, and the incidence of thymoma among thymic abnormalities was high at 38%.

Adolescent

High prevalence of undiagnosed diabetes among Chinese patients with ischaemic stroke.

We reviewed the prevalence of diabetes mellitus, hypertension and cigarette smoking in 176 Chinese patients with acute stroke, classified, on computed tomographic findings, as intracerebral haemorrhage or cerebral infarction. In all patients with no known history of diabetes, a 75 g OGTT was done 3-6 months after ictus and interpreted using WHO criteria. The overall prevalence of diabetes and impaired glucose tolerance (IGT) was 33.5% and 21.0%, respectively, with a higher prevalence being found in patients with cerebral infarction (P less than 0.05). Forty percent of those with diabetes were previously undiagnosed - all but 2 had ischaemic stroke. Compared to reported findings in the general population, an increased prevalence of hypertension, and possibly also cigarette smoking was found in patients with both stroke categories. On the other hand, significant hypercholesterolaemia was not found in patients of either category. In view of the high prevalence of undiagnosed diabetes among these stroke patients and the increased morbidity and mortality associated with diabetes mellitus, screening for diabetes is recommended especially in those with ischaemic stroke. If a fasting plasma glucose of greater than or equal to 6 mmol/l was used for the initial screening of undiagnosed diabetes in this group of patients, the sensitivity and specificity values would have been 78% and 94%, respectively. Whether this cut-off value can be cost-effectively employed for mass screening remains to be confirmed by studies involving larger numbers of stroke patients.

Blood Glucose

Massive benzodiazepine requirements during acute alcohol withdrawal.

Severe alcohol withdrawal developed in an abstinent chronic alcoholic man. Massive doses of benzodiazepines (2,335 mg of diazepam intravenously, 21,225 mg of oxazepam orally) achieved only marginal control of delirium and agitation. Analysis of multiple blood samples drawn during and after the withdrawal episode indicated, as expected, very high concentrations of diazepam and metabolites and of oxazepam. There was no evidence of an abnormal pharmacokinetic profile. Benzodiazepine resistance in withdrawing alcoholics probably reflects a receptor-site phenomenon rather than an abnormal drug disposition.

Adult

Rapid recovery from massive diazepam overdose.

Two patients were hospitalized in moderately deep coma after ingestion of large doses of diazepam (500 and 2,000 mg) with suicidal intent. Neither patient experienced important complications; both recovered fully and were discharged within 48 hours. Concentrations of diazepam and its three pharmacologically active metabolites (desmethyldiazepam, temazepam, and oxazepam) were determined in multiple samples drawn during and after hospitalization. High concentrations of all four compounds were present in early samples, then declined slowly during the next one to two weeks. Rapid clinical recovery after diazepam overdose is not attributable to rapid elimination of active compounds from the body, but more likely to adaptation or tolerance to their depressant effects.

Adult

Reduced quinidine clearance in elderly persons.

The influence of age on quinidine pharmacokinetics was assessed in 22 healthy male and female volunteers; 14 of the subjects were young (aged 23 to 34 years) and 8 elderly (aged 60 to 69 years). All subjects received 180 to 300 mg of quinidine base by constant rate intravenous infusion over 10 to 15 minutes. The concentration of total and unbound quinidine in multiple serum samples and in urine collected within 48 hours after the administration of quinidine qas determined with spectrophotofluorometric assay. Mean kinetic values for total quinidine in the young subjects were: elimination half-life (t 1/2 beta), 7.3 hours; total volume of distribution (Vd), 2.39 liters/kg; total clearance, 4.04 ml/min per kg; renal clearance 1.43 ml/min per kg; and percent unbound, 24.6 In the elderly subjects, the values for Vd (2.18 liters/kg) and percent unbound (28.2) did not differ significantly from these values in the young subjects. However, in the elderly subjects t 1/2 beta was significantly longer (9.7 hours, P less than 0.05) and total quinidine clearance significantly less (2.64 ml/min per kg, P less than 0.005) than in the young subjects. Renal clearance of quinidine in the elderly was also significantly less (0.99 ml/min per kg, P less than 0.05) than in the young and was associated with lower rates of creatinine clearance in the elderly (r = 0.66). Reduced clearance of quinidine and prolongation of its elimination half-life could predispose to toxicity in the elderly unless the dose were appropriately adjusted.

Adult

Chronic effects of phenytoin on brain-stem auditory evoked potentials in man.

The effects of phenytoin (PHT) on brain-stem auditory evoked potentials (BAEPs) were studied in 65 epileptic patients who received long-term PHT monotherapy at therapeutic and supra-therapeutic levels with no clinical evidence of brain-stem toxicity. Abnormal BAEPs were found in 7.5% and 33.3% of patients with therapeutic and supra-therapeutic PHT levels respectively. Serum PHT levels had a trend towards a positive relationship with the I-V interpeak latency (IPL), and a significant negative relationship with the amplitudes of waves I and V. At supra-therapeutic levels, both I-V and I-III IPLs were significantly prolonged while at therapeutic levels only I-III IPLs were prolonged. The absolute latency of wave I was prolonged in both the therapeutic and the supra-therapeutic groups. These results suggest that PHT acts both peripherally on either the auditory nerve or the cochlea, and centrally on brain-stem conduction.

Adolescent