Mohamed Zaki

In this study, we describe a newly developed and simple analytical method using high-performance liquid chromatography coupled to fluorescence detector (HPLC-FLD) for the determination of enrofloxacin, ciprofloxacin, and danofloxacin in porcine plasma. A single-step sample preparation, including extraction with acidic acetonitrile, coagulation with ammonium acetate, and centrifugation made possible the direct analysis of plasma samples without the need for any further cleanup procedure. The developed method was validated with specificity, linearity, limit of detection (LOD), limit of quantitation (LOQ), accuracy, and precision. All results were fully adequate. In the study using porcine plasma incurring enrofloxacin, the developed method proved capable of quantifying concentrations below its maximum residue limit, and its time-course residues were excreted within the 10-day withdrawal time.

A novel two-step, SYBR Green I based real-time RT-PCR assay was developed for detection and quantification of BCoV using ABI PRISM 7500 sequence detection system. The assay was carried out using two sets of primers designed to amplify highly conserved sequences of the nucleocapsid gene of BCoV and
the internal control, bovine glyceraldehyde-3-phosphate dehydrogenase, RNA. Specific identification of both targets was elucidated by melt curve analysis, in which the BCoV amplified product generated a melt peak at 78.35
0.26 C and the internal control RNA at 82.54
0.32 C. The assay was highly specific since all negative controls and other viruses of clinical and structural relevance failed to develop any positive results. The detection limit of the reaction was 103 plasmid copies and 1.17  103 TCID50 of the tissue culture propagated virus. Standard deviation and coefficient of variation was low for bothintra-assay and inter-assay variability. The assay performance on field samples was evaluated on 103 (68 fecal and 35 nasal) swab specimens and compared with the conventional RT-PCR assay. The results of both assays matched for the diagnosis of 65 fecal and 33 nasal samples. However, three fecal and two nasal samples tested negative in gel-based assay were positive for the real-time RT-PCR. The robustness and a high-throughput performance of the developed assay make it a powerful tool in diagnostic applications and in BCoV research.

Sustained release matrix pellets of the freely water soluble drug, betahistine dihydrochloride (BH), were prepared using freeze pelletization technique. Different waxes and lipids (cetyl alcohol, beeswax, glyceryl tripalmitate (GTP) and glyceryl tristearate) were evaluated for the preparation of matrix pellets. A D-optimal design was employed for the optimization and to explore the effect of drug loading (X1), concentration of lipophilic surfactant (X2), concentration of co-surfactant (X3) and wax type (X4) on the release extent of the drug from matrix pellets. The entrapment efficiency (Y1), pellet diameter (Y2), and the percentage drug released at given times were selected as dependent variables. Results revealed a significant impact of all independent variables on drug release from the formulated pellets. The lipophilic surfactant significantly increased both the entrapment efficiency and the in vitro drug release and significantly decreased the pellet size. The optimized BH-loaded pellets were composed of 19.95% drug loading, 9.95% Span® 80 (surfactant), 0.25% Capmul® (co-surfactant) using glyceryl tripalmitate as a matrix former. The release profiles of the drug from hard gelatin capsule containing optimized pellets equivalent to 32 mg BH was similar to that of target release model for once-daily administration based on similarity factor. It could be concluded that a promising once-daily capsule containing sustained release pellets of BH was successfully designed.

n/a

n/a

To prevent engine failure it is essential to change lubricating oil regularly before it loses its protective properties. It is also necessary to monitor the physical and chemical conditions of the oil to reliably determine the optimum oil-change intervals. The present work focuses on studying evolution of the cyanide (CN) and carbon (C2) molecular spectral emission lines in the laser induced breakdown spectra of lubricating oil as a function of its consumption.