Biomedical subjects

J Du Toit

Publications and source records attributed to J Du Toit.

4 recordsLinked to original sources

PubMed1992

Personality traits of a group of young adults from different family structures.

The impact of parental divorce and remarriage and young adults' gender on second-order personality traits, such as extraversion, anxiety, tough poise and independence, was examined. The responses of 227 young adults on the Sixteen Personality Factor Questionnaire (16PF; Cattell, Eber, & Tatsuoka, 1970) were subjected to a parametric multivariate analysis of variance. Results revealed significant differences between the anxiety scores of the young men and women as well as between those of the three different family-structure groups, but divorce and remarriage was not associated with either positive or negative personality development in this sample.

Adolescent↗

PubMed1992

Nedocromil sodium inhibits the airway response to hyperosmolar challenge in patients with asthma.

We studied 16 asthmatic subjects sensitive to changes in airway osmolarity to determine whether nedocromil sodium has any effect on airway narrowing caused by hypertonic saline challenges. Nedocromil sodium (10 mg) or its vehicle was inhaled 10 min before a challenge with ultrasonically nebulized 4.5% NaCl. FEV1 was measured before challenge and 1 min after each challenge period of 0.5, 1, 2, 4, 8, 8 and 8 min. The challenge was stopped when there was a 20% fall in FEV1 from baseline or after the final challenge period. We measured airway sensitivity, that is, the provoking dose of 4.5% NaCl required to induce a 20% reduction in FEV1 (PD20FEV1) and calculated the fold difference in PD20FEV1 after the intervention. After inhaling nedocromil sodium there was a 3.95-fold improvement in PD20 (p < 0.001) when compared with the vehicle day. After pretreatment with nedocromil sodium two of the 16 subjects were completely protected against 4.5% NaCl challenge, and six developed a plateau in their response. We conclude that nedocromil sodium is effective in reducing airway narrowing in response to 4.5% NaCl challenge in asthmatic subjects, and it appears to be unique in its ability to produce a plateau in response to acute administration of a drug before a bronchial challenge.

Administration, Inhalation↗

PubMed1991

Duration of protection by inhaled salmeterol in exercise-induced asthma.

Beta-adrenoceptor agonists such as albuterol are very effective in preventing exercise-induced asthma (EIA) when they are given as an aerosol immediately before exercise. However, their duration of protection against EIA is usually less than 2 h. This may be due partly to their rapid clearance from the airways. Salmeterol is a highly lipophylic compound that is thought to bind to an exoreceptor near the beta-receptor. The objective of this study was to compare the protective effect of salmeterol with albuterol against EIA. Exercise was performed 0.5, 2.5, 4.5, and 6.5 hours after administration of the active drugs. Subjects attended the laboratory on four days within six weeks and cycled for 8 min breathing dry compressed air. We studied 17 asthmatic subjects (aged 19 to 49 years) with moderate to severe EIA. Salmeterol (50 micrograms) or albuterol (200 micrograms) was given from a metered dose inhaler via a spacer (Volumatic). On the control day, the mean work load +/- 1 SD was 174 +/- 47 W, ventilation (VE) was 77.9 percent +/- 11.2 percent of the target ventilation (60 percent maximum voluntary ventilation [MVV]), and heart rate was 170 +/- 14 beats per minute. This intensity was maintained for all tests. FEV1 was measured before and after exercise and was expressed as percent predicted and as percentage of the preexercise value (percentage of fall). Thirty minutes after treatment, both drugs were effective in inhibiting EIA--percentage of fall in FEV1, 17 +/- 12 after salmeterol; percentage of fall in FEV1, 15 +/- 15 after albuterol. At 2.5, 4.5, and 6.5 hours, the reduction in FEV1 was significantly less (p less than 0.01) after salmeterol compared with albuterol. At 6.5 hours, the percentage of fall in FEV1 was 20 +/- 10 after salmeterol and 36 +/- 12 after albuterol. Salmeterol also had a more prolonged action as a bronchodilator and values for FEV1 were significantly higher compared with those on albuterol at 4.5 and 6.5 hours. At 6.5 hours, the FEV1 percent predicted was 96 +/- 10 after salmeterol and 84 +/- 12 after albuterol (p less than 0.01). We conclude that the extent of protection against EIA and the bronchodilation induced by both drugs was similar, but that salmeterol has a longer duration of action compared with albuterol. The reason for its superior duration of action may be due to a slower clearance of the drug from the airways.

Administration, Inhalation↗

PubMed1989

Phenytoin auto-induction? Case reports.

Auto-induction of phenytoin metabolism is considered by many to be insignificant. Two cases, in which elimination of phenytoin apparently increased with continuous use, are presented. The first patient showed an increase in elimination capacity (Vmax) from 511 mg/d to 613 mg/d over a period of 5 months. The second patient showed an increase in Vmax from 512 mg/d to 570 mg/d over a period of 1 year. In neither case was compliance in question. The recognition that therapeutic failure may be due to enzyme induction could obviate expensive diagnostic procedures as well as narrow down the therapeutic alternatives.

Adolescent↗