PubMed Health⌕ Search

Biomedical subjects

S Samaan

Publications and source records attributed to S Samaan.

6 recordsLinked to original sources
PubMed1997

Changes in hemodynamics, ventricular remodeling, and ventricular contractility during normal pregnancy: a longitudinal study.

OBJECTIVE: To investigate the hemodynamic changes occurring in normal pregnancy and to see if these changes were associated with an increase in myocardial contractility. METHODS: In a longitudinal study, primigravidas were studied with echocardiography in early (15 +/- 1.8 weeks), mid (26 +/- 1.2 weeks), and late (36 +/- 1.0 weeks) gestation, as well as at 6 weeks postpartum. Cardiac dimensions were measured with two-dimensional and M-mode echocardiography and hemodynamic indices were calculated. All measurements were made with subjects in the left lateral decubitus position. Statistical analysis was performed with repeated measures analysis of variance. RESULTS: Seventy-six women with normal pregnancy outcomes completed all four studies. From the baseline study to late gestation, an increase in cardiac output of 27% (from [mean +/- standard error] 4.2 +/- 0.1 to 5.8 +/- 0.2 L/min, P = .001), and a decrease in total peripheral resistance of 33% (from 1356 +/- 69 to 941 +/- 37 dynes/second cm-5, P = .001) occurred. Over this same time period, left ventricular function, while demonstrating a small and non-significant increase in velocity of circumferential fiber shortening (from 1.25 +/- 0.02 to 1.27 +/- 0.02 cm/second), revealed a 12% decrease in wall stress (from 36.3 +/- 1.0 to 31.9 +/- 1.0 g/cm2, P = .001) and a 13% decrease in the load-independent wall stress to velocity of circumferential fiber shortening ratio (from 30.0 +/- 1.2 to 26.1 +/- 1.0, P = .01), implying enhanced intrinsic myocardial contractility. CONCLUSION: Normal pregnancy is characterized by enhanced myocardial performance.

Adult↗
PubMed1989

The effect of smoking on theophylline kinetics in healthy and asthmatic elderly males.

The effect of smoking on theophylline kinetics was investigated in four groups of males over the age of 65 yr. The first group consisted of 14 healthy non-smoking males, the second group consisted of 8 healthy smoking males. The first and the second groups were administered a single oral dose of 300 mg tablet of sustained-release anhydrous theophylline product and serial blood samples were collected over 24 hr. The third group consisted of 22 clinically stable asthmatic non-smoking males, the fourth group consisted of 9 clinically stable asthmatic smoking males. The third and the fourth groups, were administered multiple oral doses equivalent to 300 mg of anhydrous theophylline from sustained-release Oxtriphylline every 12 hr for 72 hr; and blood samples were collected every two hours between 72-82 hrs. Serum theophylline concentrations were determined by HPLC. There were no significant differences between the smokers and non-smokers in observed maximum concentration (Cmax), its time (tmax), the area under the time-concentration curve (AUCo-t), and total body clearance rate (Cl). Aging appears to offset the known smoking inducing effect on the hepatic microsomal enzymes.

Aged↗
PubMed1983

Theophylline kinetics in a geriatric group.

The influence of age, sex, and smoking on theophylline disposition was studied in 38 healthy subjects ranging in age from 26 to 81 yr. There were 8 young (less than 60 yr) and 30 geriatric (greater than 60 yr) subjects, including 28 men (8 smokers) and 10 women (3 smokers). A crossover experimental design was used. A single dose of theophylline elixir (5 mg/kg lean body weight [LBW]) was given as a reference product to all subjects. One week later a sustained-release (SR) theophylline tablet (8 and 6 mg/kg LBW) was given to the young and the geriatric subjects. Serum theophylline concentrations were determined by HPLC. Theophylline elimination (t1/2 beta) is shorter in the geriatric group (6.93 and 8.14 hr); total body theophylline clearance is greater in the geriatric group (44.39 and 32.97 ml/kg/hr), and the apparent volume of distribution is also greater in the geriatric group (26.29 and 22.97 l). Sex and smoking did not influence any of the parameters studied. In 93% of the geriatric subjects, serum theophylline levels of 8 to 20 micrograms/ml were reached at steady state with the SR tablet. Theophylline dose reduction based on an arbitrary age limit is not, therefore, invariably indicated.

Adult↗