Acute exposure to Catha edulis depresses contractility and induces myocardial infarction in spontaneously contracting, isolated rabbit's heart.

Khat chewing is a recreational habit known to pose major socio-economic and medical problems in countries of Southern Arabia and the Horn of Africa. Among other adverse health effects, khat chewing has been associated with an increased risk of myocardial infarction (MI) in heavy consumers. This study was carried out to examine the direct effects of Catha edulis extract on contractility of spontaneously contracting, isolated rabbit heart and to investigate its mechanism of action. Isolated six rabbit's hearts attached to a Langendorff apparatus were perfused with extract at a constant flow rate and continuously bubbled with a 95% O2/5% CO2 gas mixture. Each heart served as its own control, as responses were recorded before and after administration of C. edulis extract. Varying concentrations of extract (50, 100 and 250 mg/ml) were loaded in the perfusate, their effects recorded and effluent fluid collected for assay of cardiac enzymes. Histological examination of the cardiac tissue was performed at the end of perfusion with 250 mg/ml extract. This study revealed that acute exposure to C. edulis extract exerted negative inotropic and chronotropic effects on isolated hearts. The extract also had a vasoconstrictor effect on coronary vessels, independent of α1 adrenergic receptor stimulation. Histological examination of hearts perfused with 250 mg/ml C. edulis extract revealed the presence of histological changes unique to myocardial infarction, a finding consistent with observed increased levels of cardiac enzymes in perfusates. Thus, we have demonstrated experimentally a direct cardiac depressant- and MI inducing effects of C. edulis extract. These results are consistent with the earlier reported deleterious effects of khat on cardiovascular function among khat chewers.

In vivo acute effects of orally administered hydro-ethanol extract of Catha edulis on blood glucose levels in normal, glucose-fed hyperglycemic, and alloxan-induced diabetic rats.

OBJECTIVE: To investigate the blood glucose lowering effect of khat (Catha edulis) extract in normal, glucose-loaded, and alloxan diabetic rats. METHODS: Three experimental protocols were used in this study. In each of the first 2 protocols, 3 groups of rats (6 rats per group) were used as control group (NS), Catha edulis (CE) treated, and glibenclamide treated groups. This study was carried out at the Physiological Laboratory of the Medical School of King Khalid University, Abha, Saudi Arabia between October and November, 2009. Normal rats were used in the first protocol while alloxan diabetic rats were used in the second protocol. Blood glucose levels were measured in all 3 groups after single dose injections of saline, CE or glibenclamide. In the third protocol, another 6 groups of rats (6 rats per group) were prepared as in the first 2 protocols and oral glucose tolerance test (OGTT) was performed on each rat after oral administration of glucose (1.5 g/kg). RESULTS: Oral administration of a hydro-ethanol extract of CE caused no statistically significant change in blood glucose levels in normal rats with or without glucose loading. There were slight, non significant increases in blood glucose levels of extract-treated diabetic rats, with and without glucose loading, as compared to the corresponding untreated rats. CONCLUSION: Oral administration of CE extract does not exert a hypoglycemic effect in normal, glucose-loaded, and diabetic rats.

Construction of intrauterine growth curves in a high altitude area of Saudi Arabia.

OBJECTIVE: The aim of the present study was to construct intrauterine percentile growth curves for body weight, length and head circumference for local use in a high altitude area of Saudi Arabia. METHODS: This is a cross-sectional study of all Saudi births from Abha General Hospital over a 6-year period from 1999 to 2004. We included a total of 6,035 Saudi births in the present study after eliminating babies that were stillbirths, twins or those with major congenital anomalies. The gestational age of the infants ranged from 26-42 weeks. The anthropometric measurements included birth weight, crown-heel length and head circumference. We calculated the 10th, 25th, 50th, 75th, and 90th percentiles for weight, length and head circumference against the periods of gestation. We also calculated the mean weight and mean +/- 2SD. We determined the curves of best fit for weight, length and head circumference measurements at different weeks of gestation by polynomial regression of the following general form to construct the clinical curves: Y=a + bX + cX2. RESULTS: We derived intrauterine growth curves for weight, length and head circumference from measurements made on infants born at each week of gestation in the latter half of pregnancy. By calculating mean values and deviations around these (expressed either as centiles or standard deviations), we constructed distance (size attained) growth curves. The mean values for weight and length of births of the present study are lower than those of published charts in all gestational periods. However, for head circumference, evident appeared only before 32 weeks of gestation. The mean values of head circumference were nearly comparable. CONCLUSION: Constructed smoothed gestational curves are a useful tool for assessing the intrauterine growth of births in high altitude areas of Saudi Arabia.

The body surface area of Saudi newborns.

Cancer chemotherapy drugs, fluids and electrolytes are best dosed per square meter of body surface area (BSA). Since newborns have an exceptionally large surface to mass ratio, their BSA needs to be accurately estimated, if it is to serve as a safe denominator for drugs and fluids. In this study, BSA was measured directly in 15 full-term Saudi newborns, using a coating technique. The data was used to construct a BSA weight-length prediction formula. Mean body mass index (BMI +/-SD) of our subjects was 12.56 +/- 1.29 kg/m2 and surface to mass ratio, .068 +/- .005 m2/kg. The closest fit to measured values was given by the regression equation: BSA (m2) = 0.03614H(0.294)W(0.529) +/- 0.0027 (SEE) A simplified formula based on weight alone: BSA = 7.4 + 4.2W +/- 0.0022(SEE) was derived for bedside use, in urgent situations. Our formulae may be applicable to non-Saudi newborns, if as expected, body size and shape variations in different populations develop after birth.

A formula for the estimation of the body surface area of Saudi male adults.

OBJECTIVE: Human body surface area (BSA) is the preferred denominator for physiological indices of body metabolism and for drug dosages. The Du Bois and Du Bois height/weight nomogram, used for fast and convenient estimation of patients BSA, is not suitable for all populations due to ethnic differences in body shape and build. The purpose of this study was to obtain direct measurements of BSA and use the data to construct a prediction formula for Saudi male adults. METHODS: Body surface area was measured in 21 adult male Saudis at Assir Central Hospital in Abha, Kingdom of Saudi Arabia between 2000 and 2003, using a coating technique. Areas of the coating material were determined with a compensating planimeter. Other anthropometric indices were measured or calculated according to standard procedures. Measured values of BSA were subjected to linear regression analysis using the least squares method to obtain a formula for predicting BSA from heights and weights. RESULTS: Mean body mass index (BMI) was 25.1 +/- 1.6 kg/m2; linearity, 2.46 +/- 0.13 cm/kg; surface to mass ratio, 0.025 +/- 0.0008 m2/kg; relative sitting height (RSH), 0.51 +/- 0.005. The closest fit to measured BSA values was given by the biexponential regression equation: BSA=0.02036 x H(0.516) x W(0.427) +/- 0.01283. This formula predicts BSA of Saudi male adults more accurately than all existing equations tested and yields a convenient BSA table for Saudis. CONCLUSION: The use of our formula, with prediction accuracy superior to those of existing formulae, should facilitate the establishment of normal values of other physiological indices. It should also lead to more reliable and precise drug dosages and expedite rapid decision making in critical care situations.