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Search Results: 1 - 10 of 22737 matches for " Al-Obaid Omar "
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Gallstone Ileus: A forgotten rare cause of intestinal obstruction
Al-Obaid Omar
Saudi Journal of Gastroenterology , 2007,
Abstract: Gallstone ileus is an uncommon complication of cholelithiasis, with a high morbidity and mortality rate - usually related to the delayed diagnosis of intestinal obstruction. Diagnosing gallstone ileus needs a high index of suspicion. A case of a gallstone ileus is reported. The clinical presentation, radiological features, intraoperative findings, operative procedure and literature review are presented.
rac-2-Methylamino-1,2-diphenylethanol
Ahmed Bari,Abdulrahman M. Al-Obaid,Seik Weng Ng
Acta Crystallographica Section E , 2012, DOI: 10.1107/s1600536812002012
Abstract: The dihedral angle between the two phenyl rings in the title compound, C15H17NO, is 52.9 (1)°. In the crystal, the molecules are connected by O—H...N hydrogen bonds into centrosymmetric dimers. The amino H atom is not involved in hydrogen bonding.
rac-2-Amino-1,2-diphenylethanol
Ahmed Bari,Abdulrahman M. Al-Obaid,Seik Weng Ng
Acta Crystallographica Section E , 2012, DOI: 10.1107/s1600536812002000
Abstract: In the title compound, C14H15NO, the torsion angle about the two Csp3 atoms adopts a partially eclipsed conformation [ 61.5 (1)°]. The dihedral angle between the two rings is 48.1 (1)°. In the crystal, the molecules are connected by O—H...N and N—H...O hydrogen bonds into zigzag chains running along [010]. One of the amino H atoms is not involved in hydrogen bonding.
Generation of polyclonal antibody with high avidity to rosuvastatin and its use in development of highly sensitive ELISA for determination of rosuvastatin in plasma
Ibrahim A Darwish, Abdul-Rahman M Al-Obaid, Hamoud A Al-Malaq
Chemistry Central Journal , 2011, DOI: 10.1186/1752-153x-5-38
Abstract: Rosuvastatin (ROS); (3R,5S,6E)-7-[4-((4-fluorophenyl)-6-(1-methylethyl)-2-[methyl (methylsulphonyl) amino]-5-pyrimidinyl]-3, 5-dihydroxy-6-heptenoic acid (Figure 1), is an effective 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitor and it is widely prescribed in the treatment of patients with hypercholesterolaemia [1]. ROS is available as Crestor in tablet form (5, 10, 20, or 40 mg) for oral administration. In clinical studies, ROS (1-80 mg) produced highly significant dose-dependent reductions in low-density lipoprotein cholesterol (up to 65%) and was well tolerated. The pharmacokinetics of ROS following single and multiple-dose administration of the drug to healthy volunteers have been investigated. The absolute oral bioavailability is greater than 20%, and the elimination half-life is ~ 20 hrs. The reported ROS plasma therapeutic concentration was 19 ng/ml, after 40 mg-daily dosing. The elimination of ROS is primarily via the liver. In a clinical trial, ~ 90% of the orally administered dose of ROS is recovered in feces as unchanged drug [2].Because of the clinical success of ROS, several methods have been developed for its quantitative determination in plasma samples. Almost all of these methods are liquid chromatography [3-9]. These methods involved tedious steps for the pre-treatment of the samples, pre-derivatization with critical derivatizing reagents, and use of expensive detectors (e.g. tandem mass spectrometry) that are not available in most laboratories. For these reasons, the development of new alternative analytical technology for determination of ROS in plasma with adequate sensitivity, improved simplicity, and lower cost was seriously needed.Immunoassays have been widely used in pharmaceutical and clinical analysis because of their inherent specificity, applicability for a wide range of analytes, high-throughput, and low cost [10]. ELISA is the most versatile format of the immunoassays. ELISA is remarkably quick, easily performed, an
3,3-Diethoxy-5-fluoro-2,3-dihydro-1H-indol-2-one
Ahmed Bari,Abdulrahman M. Al-Obaid,Ali Syed Saeed,Seik Weng Ng
Acta Crystallographica Section E , 2012, DOI: 10.1107/s1600536812001857
Abstract: The title ketal, C12H14FNO3, crystallized with two independent molecules in the asymmetric unit. In each molecule the fused ring system is essentially planar [maximum deviations of 0.0169 (11) and 0.0402 (13) ]. The molecules are each hydrogen bonded across a center of inversion into a dimer; adjacent dimers are linked by another N—H...O hydrogen bond, forming a chain running along [100].
2-(2-{[4-Oxo-3-(2-phenylethyl)-3,4-dihydroquinazolin-2-yl]sulfanyl}ethyl)-2,3-dihydro-1H-isoindole-1,3-dione
Adel S. El-Azab,Alaa A.-M. Abdel-Aziz,Abdulrahman M. Al-Obaid,Seik Weng Ng
Acta Crystallographica Section E , 2012, DOI: 10.1107/s1600536812025883
Abstract: In the title compound, C26H21N3O3S, the quinazolinyl group is essentially planar [r.m.s. deviation for the 10 non-H atoms = 0.057 ]. The isoindoline-1,3-dione group is linked by an SCH2CH2 chain to the pyrimidinyl C atom that lies between the two N atoms. Also, the phenyl group is linked by a CH2CH2 chain at the N atom adjacent to the carbonyl group. This results in a conformation with these substituents lying to either side of the central quinazolinyl unit, with the former being approximately parallel [dihedral angle = 4.93 (7)°], and the phenyl group being inclined [dihedral angle = 71.61 (9)°] to the central quinazolinyl fused-ring system. In the crystal, molecules are consolidated into a three-dimensional architecture by C—H...O interactions, involving all three carbonyl-O atoms, and π–π interactions occurring between the pyrimidinyl and isoindole-benzene rings [inter-centroid distance = 3.5330 (13) ].
5-Isopropylimidazolidine-2,4-dione monohydrate
Alaa A.-M. Abdel-Aziz,Adel S. El-Azab,Abdulrahman M. Al-Obaid,Madhukar Hemamalini
Acta Crystallographica Section E , 2012, DOI: 10.1107/s1600536812002838
Abstract: In the title compound, C6H10N2O2·H2O, the imidazole ring is essentially planar, with a maximum deviation of 0.012 (2) . In the crystal, molecules are connected via N—H...O and O—H...O hydrogen bonds, forming a supramolecular tape along the a axis.
3-Acetyl-1-(3-methylphenyl)-5-phenyl-1H-pyrazole-4-carbonitrile
Hatem A. Abdel-Aziz,Abdul-Rahman M. Al-Obaid,Hazem A. Ghabbour,Madhukar Hemamalini
Acta Crystallographica Section E , 2012, DOI: 10.1107/s160053681200181x
Abstract: In the title compound, C19H15N3O, the central pyrazole ring makes dihedral angles of 35.52 (12) and 62.21 (11)° with the attached phenyl and methyl-substituted phenyl rings, respectively. The corresponding angle between the phenyl and methyl-substituted phenyl rings is 62.90 (11)°. In the crystal, molecules are connected by weak C—H...O hydrogen bonds, forming supramolecular chains propagating along the a-axis direction.
New Sensitive HPLC Method for Evaluation of the Pharmacokinetics of New Amantadine Prodrugs as Hepatic Delivery Systems to Enhance its Activity against HCV
Ibrahim A. Darwish, Tarek Aboul-Fadl, Nasr Y. Khalil, Ashraf M. Mahmoud, Abdul-Rahman M. Al-Obaid
International Journal of Research in Pharmaceutical Sciences , 2010,
Abstract: To improve the efficacy of amantadine (AMD) in chronic hepatitis C therapy, various prodrugs were designed and synthesized to enhance its hepatic delivery based on the incorporation of AMD into modified bile acid or cysteine derivatives. A new sensitive and selective HPLC method with fluorescence detection has been developed and validated for determination of AMD in human plasma for evaluation of the pharmacokinetics of these prodrugs. Betaxolol hydrochloride (BTX) was used as internal standard. AMD and BTX were isolated from plasma by protein precipitation with acetonitrile and derivatized by heating with 1,2-naphthoquinone-4-sulphonate (NQS) in alkaline medium (0.01 M NaOH) at 90±5 °C for 45 min. Separations were performed in isocratic mode on Nucleosil CN column (250 mm length × 3.9 mm i.d., 5 μm particle diameter) using a mobile phase consisting of acetonitrile:10 mM sodium acetate buffer (pH 3.5):methanol (20:70:10, v/v) at a flow rate of 1.5 mL min 1. The derivatized samples were extracted with chloroform and reduced with 0.03% potassium borohydride. The reduced fluorescent AMD-NQS derivative was monitored at emission wavelength of 382 nm after excitation at 293 nm. Under the optimum chromatographic conditions, a linear relationship with good correlation coefficient (r = 0.9989, n = 5) was found between the peak area ratio of AMD to BTX and AMD concentration in the range of 30–3200 ng mL 1. The limit of detection and limit of quantification were 6.7 and 21 ng mL 1, respectively. The intra and inter-assay precisions were satisfactory; the relative standard deviations did not exceed 1.57%. The accuracy of the method was proved; the recovery of AMD from spiked human plasma were 97.51 100.95 ± 0.26 1.57%. The method had higher throughput as it involved simple sample preparation procedure and short run-time (<15 min). The results demonstrated that the proposed method would have a great value in the pharmacokinetic studies for AMD released from the synthesized produgs.
Antibacterial resistance and their genetic location in MRSA isolated in Kuwait hospitals, 1994-2004
Edet E Udo, Noura Al-Sweih, Eiman Mokaddas, Molly Johny, Rita Dhar, Huda H Gomaa, Inaam Al-Obaid, Vincent O Rotimi
BMC Infectious Diseases , 2006, DOI: 10.1186/1471-2334-6-168
Abstract: Between April 1994 and December 2004, 5644 MRSA isolates obtained from different clinical samples were studied for resistance to antibacterial agents according to guidelines from the National Committee for Clinical Laboratory Standards and the British Society for Antimicrobial Chemotherapy. The genetic location of their resistance determinants was determined by curing and transfer experiments.They were resistant to aminoglycosides, erythromycin, tetracycline, trimethoprim, fusidic acid, ciprofloxacin, chloramphenicol, rifampicin, mupirocin, cadmium acetate, mercuric chloride, propamidine isethionate and ethidium bromide but susceptible to vancomycin, teicoplanin and linezolid. The proportion of the isolates resistant to erythromycin, ciprofloxacin and fusidic acid increased during the study period. In contrast, the proportion of isolates resistant to gentamicin, tetracycline, chloramphenicol and trimethoprim declined. High-level mupirocin resistance increased rapidly from 1996 to 1999 and then declined. They contained plasmids of 1.9, 2.8, 3.0, 4.4, 27 and 38 kilobases. Genetic studies revealed that they carried plasmid-borne resistance to high-level mupirocin resistance (38 kb), chloramphenicol (2.8 – 4.4 kb), erythromycin (2.8–3.0 kb) and cadmium acetate, mercuric chloride, propamidine isethionate and ethidium bromide (27 kb) and chromosomal location for methicillin, the aminoglycosides, tetracycline, fusidic acid, ciprofloxacin and trimethoprim resistance. Thus, the 27 kb plasmids had resistance phenotypes similar to plasmids reported in MRSA isolates in South East Asia.The prevalence of resistance to erythromycin, ciprofloxacin, high-level mupirocin and fusidic acid increased whereas the proportion of isolates resistant to gentamicin, tetracycline, chloramphenicol and trimethoprim declined during the study period. They contained 27-kb plasmids encoding resistance to cadmium acetate, mercuric chloride, propamidine isethionate and ethidium bromide similar to plasm
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