Biomedical subjects

A M Mustafa

Publications and source records attributed to A M Mustafa.

6 recordsLinked to original sources

PubMed2006

Mechanisms of the anti-hypertensive effect of Hibiscus sabdariffa L. calyces.

Previous studies have demonstrated the anti-hypertensive effects of Hibiscus sabdariffa L. (HS) in both humans and experimental animals. To explore the mechanisms of the anti-hypertensive effect of the HS, we examined the effects of a crude methanolic extract of the calyces of HS (HSE) on vascular reactivity in isolated aortas from spontaneously hypertensive rats. HSE relaxed, concentration-dependently, KCl (high K(+), 80 mM)- and phenylephrine (PE, 1 microM)-pre-contracted aortic rings, with a greater potency against the alpha(1)-adrenergic receptor agonist. The relaxant effect of HSE was partly dependent on the presence of a functional endothelium as the action was significantly reduced in endothelium-denuded aortic rings. Pretreatment with atropine (1 microM), L-NAME (10 microM) or methylene blue (10 microM), but not indomethacin (10 microM), significantly blocked the relaxant effects of HSE. Endothelium-dependent and -independent relaxations induced by acetylcholine and sodium nitroprusside, respectively, were significantly enhanced in aortic rings pretreated with HSE when compared to those observed in control aortic rings. The present results demonstrated that HSE has a vasodilator effect in the isolated aortic rings of hypertensive rats. These effects are probably mediated through the endothelium-derived nitric oxide-cGMP-relaxant pathway and inhibition of calcium (Ca(2+))-influx into vascular smooth muscle cells. The present data further supports previous in vivo findings and the traditional use of HS as an anti-hypertensive agent.

Acetylcholine↗

PubMed2004

Genetic polymorphism of cytochrome P450 2C19 in healthy Malaysian subjects.

AIMS: Impaired S-mephenytoin 4'-hydroxylation is a well-described genetic polymorphism affecting drug metabolism in humans. Although ethnic differences in its distribution of polymorphism has been described, it is not known whether there is an ethnic heterogeneity of the structure and expression of the CYP2C19 enzyme in the Malaysian population. METHODS: Study subjects were 142 healthy, unrelated Malaysians aged 18-29 years. Baseline omeprazole and 2-h postingestion omeprazole and 5'-hydroxyomeprazole concentrations were measured for CYP2C19 phenotype determination. Identification of CYP2C19 genotypes was performed with the use of polymerase chain reaction. RESULTS: Phenotyping of CYP2C19 revealed that the prevalence of poor metabolizers (PMs) in the Malaysian population was 14.1%, whereas prevalence of PMs in genotyping was 12.6%. The PM genotypic prevalence rate was 5.6% in Malays, 19.1% in Chinese and 10.0% in Indian subjects. There were significant differences in PM genotypic prevalence rates among the three primary ethnic groups (P < or = 0.05). CONCLUSIONS: Phenotyping and genotyping revealed significant differences in the prevalence rates among the three ethnic groups in Malaysia, with Chinese recording highest prevalence.

2-Pyridinylmethylsulfinylbenzimidazoles↗

PubMed2003

Evidence of an interaction between nifedipine and nafcillin in humans.

AIMS: Nafcillin (Wyeth Laboratories, Philadelphia, PA, USA) has been reported to induce the metabolism of cyclosporin and warfarin, which are known substrates of cytochrome P-450 (CYP). However, there has not been any report to date on its possible interaction with nifedipine, an index substrate of the enzyme, CYP3A4. METHODS: Nine healthy normotensive subjects participated in this randomized placebo-controlled two-way crossover study examining the effects of 5 days' pretreatment of nafcillin 500 mg or placebo four times daily on the pharmacokinetics of an oral dose of nifedipine 10 mg. Plasma nifedipine concentrations were measured by gas chromatography-mass spectro. RESULTS: The area under the plasma nifedipine concentration-time curve (AUC0-alpha) in nafcillin-pretreated subjects (80.9 +/- 32.9 micro g l-1 h-1) was significantly decreased compared with subjects who received only nifedipine (216.4 +/- 93.2 micro g l-1 h-1) (P < 0.001). Total plasma clearance of nifedipine (CL/F) was significantly increased with nafcillin pretreatment (138.5 +/- 42.0 l h-1 vs 56.5 +/- 32.0 l h-1) (P < 0.002). CONCLUSIONS: The results show that nafcillin pretreatment markedly increased the clearance of nifedipine and suggest that nafcillin is a potent inducer of CYP enzyme.

Adult↗

PubMed2003

Leaching of bisphenol A from new and old babies' bottles, and new babies' feeding teats.

Bisphenol A is the monomer used in the manufacture of polycarbonate. Bisphenol A is also known to mimic the female hormone estrogen. In this study, the possibility of the leaching of bisphenol A from polycarbonate babies' bottles and feeding teats was investigated. Bisphenol A was extracted from water samples exposed to the bottles and teats using liquid-liquid extraction. Bisphenol A was analysed by gas chromatograph-mass spectrometer with quadrapole detector in selected ion monitoring mode. Mean leaching of bisphenol A from 100 used babies' bottles when filled with water at 25 degrees C and 80 degrees C were 0.71 +/- 1.65 ng/cm2 (mean +/- standard deviation) and 3.37 +/- 5.68 ng/cm2 respectively. Mean leaching of bisphenol A from 30 new babies' bottles when filled with water at 25 degrees C and 80 degrees C were 0.03 +/- 0.02 ng/cm2 and 0.18 degrees 0.30 ng/cm2 respectively. Bisphenol A was observed to have leached from babies' feeding teats into 37 degrees C water ranged from non-detectable to 22.86 ng/g. The technique employed in this study is fast, reliable and economical.

Benzhydryl Compounds↗

PubMed2001

Comparative pharmacokinetics of theophylline in camels (Camelus dromedarius) and goats (Caprus hircus).

A comparative randomized crossover study was conducted to determine the pharmacokinetics of theophylline in male and female camels (Camelus dromedarius) and goats (Caprus hircus). Theophylline is an established 'probe drug' to evaluate the drug metabolizing enzyme activity of animals. It was administered by the intravenous (i.v.) route and then intramuscularly (i.m.) at a dose of 2 mg/kg. The concentration of the drug in plasma was measured using a high-performance liquid chromatography (HPLC) technique on samples collected at frequent intervals after administration. Following i.v. injection, the overall elimination rate constant (lambda z,) in goats was 0.006 +/- 0.00076/min and in camels was 0.0046 +/- 0.0008/min (P < 0.01). The elimination half-life (t 1/2 lambda z) in goats (112 .7 min) was lower than in camels (154.7 min) (P < 0.01). The apparent volume of distribution (Vz) and the total body clearance (Cl) in goats were 1440.1 +/- 166.6 ml/kg and 8.9 +/- 1.4 ml/min/kg, respectively. The corresponding values in camels were 1720.3 +/- 345.3 ml/kg and 6.1 +/- 1.0 ml/min/kg, respectively. After i.m. administration, theophylline reached a peak plasma concentration (Cmax) of 1.8 +/- 0.1 and 1.7 +/- 0.2 microg/ml at a post-injection time (Tmax) of 67.5 +/- 8.6 and 122.3 +/- 6.7 min in goats and camels, respectively. The mean bioavailability (T) in both goats and camels was 0.9 +/- 0.2. The above data suggest that camels eliminate theophylline at a slower rate than goats.

Animals↗

PubMedDate not supplied

Imaging techniques in patients with biliary obstruction.

The most frequent causes of cholestasis include choledocholithiasis and neoplasms (pancreatic head carcinoma, ampullary carcinoma, cholangiocarcinoma). The authors discussed imaging modalities currently applied in the diagnostics of patients with suspected obstruction biliary tract obstruction. Special attention was paid to the efficacy of these techniques in detecting the obstruction and determining its level and nature. In general, US or CT are first performed in patients with cholestasis. The use of percutaneous cholangiography and retrograde cholangiopancreatography is often limited to therapeutic interventions. Magnetic resonance offers images similar to both conventional cholangiography and computed tomography. This technique offers complex evaluation of bile ducts and other abdominal organs.

Bile Duct Neoplasms↗