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Biomedical subjects

N W White

Publications and source records attributed to N W White.

26 records · Page 2Linked to original sources
PubMed1989

Venous thrombosis and rifampicin.

In a retrospective analysis of clinically diagnosed and lower limb deep vein thrombosis (DVT) proven by contrast venography, DVT complicated admissions in 46 (3.4%) of 1366 adult patients treated in a tuberculosis hospital during 1986. Analysis of 7542 admissions during 1978-86 showed a relative risk of 4.74 in patients treated with regimens including rifampicin compared with other regimens. DVT was significantly more common in winter months and usually occurred within 2 weeks of treatment being started. This probable association between rifampicin and DVT does not contraindicate use of this drug, but measures to prevent DVT should be taken in inpatients receiving rifampicin.

Adolescent↗
PubMed1989

Byssinosis in South Africa. A survey of 2411 textile workers.

The first study of the prevalence of byssinosis in the South African cotton textile industry is described. Questionnaires were administered to 2411 subjects from six textile mills. Height and weight were measured and pulmonary function was tested before and after the first shift of a working week. Dust concentrations were measured using a Lumsden-Lynch vertical elutriator sampler. The prevalence of byssinosis (all grades) according to work departments was as follows: spinning 11.2%, winding 6.1%, and weaving 6.4%. Subjects with symptoms of byssinosis had a significantly reduced forced expiratory volume in 1 second (FEV1) and FEV1/forced vital capacity ratio when compared with controls matched for age, height and weight. Dust concentrations in many areas of the preparation and spinning processes exceeded the World Health Organisation's recommended permissible exposure limit for cotton dust in spinning operations. The prevalence of byssinosis in this study appears to be lower than that documented elsewhere. The mill design, machinery in use and environmental conditions in the South African cotton textile industry appear to be similar to those in Egypt and the USA before 1978. South Africa differs from these and other countries, including the UK, in having an exceptionally high labour turnover rate, which has reduced exposure periods. The subjects were found to have a high prevalence of previously treated pulmonary tuberculosis (3.4% for males and 2.2% for females), and in this population this disease appeared to cause more respiratory impairment than byssinosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Intravascular ultrasound: catheter-based Doppler and two-dimensional imaging.

Intracoronary Doppler and two-dimensional imaging devices have been developed to aid in the search for more precise information about vessel pathology and local vessel hemodynamics. Measurement of coronary flow reserve using Doppler catheters has been well-validated experimentally and is being used clinically in certain groups of patients. Current designs using Fast-Fourier Transform of the signal and real-time video spectral display allows for instantaneous modification in positioning of the catheter within the artery to minimize artifacts. Studies are underway to assess whether measurement of coronary flow reserve and estimations of absolute flow add practical information to the quantitative assessment of vascular disease. Contrast angiography has been the "gold standard" for in vivo study of vascular disease. The recent development of two-dimensional imaging catheters has potentially opened up a new frontier of clinical assessment of vessel pathology. Imaging catheters can be used in a diagnostic role as a means of guiding therapeutic interventions. Direct analysis of the radiofrequency output of the catheter may allow for more precise characterization of plaque composition.

Angioplasty, Balloon↗
PubMed1985

Pharmacokinetic evaluation of the digoxin-amiodarone interaction.

Amiodarone is known to raise serum digoxin levels. This study was designed to evaluate the pharmacokinetic basis of this interaction in 10 normal subjects. The pharmacokinetic variables for digoxin were determined after a 1.0 mg intravenous dose of digoxin in each subject, before and after oral amiodarone, 400 mg daily for 3 weeks. During amiodarone administration, systemic clearance of digoxin was reduced from 234 +/- 72 ml/min (mean +/- standard deviation) to 172 +/- 33 ml/min (p less than 0.01). This was due to reductions in both renal clearance (from 105 +/- 39 to 84 +/- 15 ml/min) (p less than 0.05) and nonrenal clearance (from 130 +/- 38 to 88 +/- 20 ml/min) (p less than 0.01). Digoxin half-life of elimination was prolonged from 34 +/- 13 to 40 +/- 16 hours (p less than 0.05). Digoxin volume of distribution was not significantly changed. Amiodarone caused a three- to fivefold increase in serum reverse triiodothyronine levels, but changes in thyroid function were not quantitatively related to the changes in digoxin pharmacokinetics. These alterations in digoxin pharmacokinetics produced by amiodarone explain the increase in serum digoxin level that has been observed when this drug combination has been used clinically.

Adult↗
PubMed1982

Lead absorption in Cape children: a preliminary report.

There is little information on environmental lead absorption in childhood in southern Africa. The concentration of lead in the dentine of shed teeth was measured as a cumulative marker of long-term absorption in 80 children attending a Cape Town dental clinic. Blood lead levels were determined in 226 children, 114 from the Red Cross War Memorial Children's Hospital, Cape Town, 23 from Ciskei and 89 from a dental clinic. This small survey reports on the precision of laboratory technique and indicates that some children living in urban Cape Town have accumulated lead to an extent comparable to that in large Western cities.

Age Factors↗