King Faisal Specialist Hospital & Research Centre

About: King Faisal Specialist Hospital & Research Centre is a healthcare organization based out in Riyadh, Saudi Arabia. It is known for research contribution in the topics: Detection limit & High-performance liquid chromatography. The organization has 58 authors who have published 157 publications receiving 3527 citations.

Validation of a solild phase extraction procedure for the gc-ms identification and quantitation of cocaine and three metabolites in blood, urine, and milk

Abstract: A simple and widely used solid-phase extraction procedure (United Chemical Technologies Method Handbook) was applied for the GC-MS identification and quantitation of cocaine (COC), benzoylecgonine (BE), cocaethylene (COCE), and m-hydroxy- benzoylecgonine (HBE) in blood, urine, and milk. The method which utilizes BSTFA as a derivatizing agent yielded abundant diagnostic ions with high m/z values. Linear quantitative response curves were generated for the analytes of interest over a concentration range of 5–1000 ng/mL. Linear regression analyses of the standard curve in the three specimen types exhibited correlation coefficients ranging from 0.997 to 1.000. The LOD values for COC, COCE, and derivatives of BE, and HBE in the three specimen types ranged from 2.5 to 5.0 ng/mL. The LOQ values, however, ranged from 5.0 to 10.0 ng/mL. Intra-assay and inter-assay precision studies reflected a high level of reliability and reproducibility of the method. The applicability of the method for the detection and quantita...

Mutations in codons 12 and 13 of K-ras exon 2 in colorectal tumors of Saudi Arabian patients: frequency, clincopathological associations, and clinical outcomes.

Abstract: Mutations in codons 12/13 of K-ras exon 2 are associated with reduced benefit from anti-epidermal growth factor receptor antibody treatment for metastatic colorectal cancer (CRC). Here, we evaluated the frequency of K-ras mutations and their relationship with clinicopathological features and treatment outcomes in Saudi Arabian patients with CRC. The genetic status of K-ras was determined in 300 patients diagnosed with CRC. Clinical information was collected retrospectively. K-ras was wild-type in 58% and mutated in 42% of the tumors. Most mutations were at codon 12 (89%) and were associated with metastasis [odds ratio (OR) = 1.38 (95%CI = 1.14-1.67] and occurrence of >40 µg/L carcinoembryonic antigen (CEA) [OR = 1.33 (1.1-1.74)] during diagnosis. Patients in stages I-III of the disease with wild-type K-ras tumors had a median relapse free survival (RFS) of 29 months in contrast to 22 months for those with the mutated K-ras tumor (P = 0.0357). In multivariate analysis, only the stage of the disease significantly predicted RFS (P = 0.001). Patients in stage IV of CRC with the wild-type K-ras tumor did not reach the median overall survival (OS), whereas patients with the mutated K-ras tumor survived for 23.5 months (P = 0.044). CEA level >40 µg/L (P = 0.004) and status of K-ras (P = 0.044) were independent predictors of OS. This is the largest study investigating K-ras mutations in patients with CRC in the Middle East. Mutations were associated with advanced stage of CRC, higher serum CEA, shorter RFS and OS.

Comparative study on the inclusion behaviour of cyclodextrin derivatives with venoruton and rutin by thin layer chromatography.

Abstract: The interaction of rutin and venoruton (troxerutin), with alpha-, beta- and gamma-cyclodextrin (CD), hydroxypropyl-beta-cyclodextrin (HP-beta-CD) and methyl-beta-cyclodextrin (M-beta-CD) was investigated by reversed-phase thin layer chromatography on polyamide plates. A mobile phase consisted of NH(4)OH; NH(4)Cl buffer solution containing various CD concentrations (pH = 9.7, 20 degrees C) was used as mobile phase. The equilibrium constants (K(f)) and the retention factor (R(f)) were determined and used to study the inclusion process. The in fluence of CDs on the solubility of rutin and venoruton was characterized by R(M) values and the increasing hydrophilicity of drugs. The results show that the inclusion capacity of cyclodextrins follows the order HP-beta-CD > M-beta-CD > beta-CD > gamma-CD, and rutin is more easily included by the studied cyclodextrins than venoruton. In addition, the thermodynamic parameters (Delta H, Delta S) for the formation of complexes were obtained from the van't Hoff equation, displaying the enthalpy-entropy compensation effect.

LC Determination of the Enantiomeric Purity of L‐Arginine Using a Teicoplanin Chiral Stationary Phase

Abstract: A direct enantioselective high‐performance liquid chromatography (HPLC) method was employed successfully for determination of the enantiomeric purity of L‐arginine. The elaborated method used teicoplanin macrocyclic antibiotic chiral stationary phase (CSP), known as Chirobiotic T, with a reversed‐phase mobile phase consisting of methanol:50 mM sodium dihydrogen phosphate buffer, pH 4.6 (2:8, v/v), at a flow rate of 1.0 mL/min and UV detection at 214 nm. Linearity, precision, accuracy, and the quantitation limit were determined. The method proved to be capable of determining 0.0025% (w/w) of D‐arginine (the enantiomeric impurity) contrary to the pharmacopoeial limit measurement, in which only amounts of D‐arginine higher than 1.5% (w/w) caused the measurement to fail.