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  • Author or Editor: Ashraf Ali x
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The advent of disposable micro-columns will be a hope of workers of chromatography-related laboratories. A very critical and important requirement is the formation of affordable inlet frits. Welding a metal screen to a column inlet is not recommended because of the risk of damage to stationary phase. In this study, the Tollens probe (silver mirror reaction) was adopted to make affordable frits. Silver is reduced on the particle surface and in an empty space among the particles, forming a solid silver network structure at the column inlet area by injecting the reaction solution into the packed column at a depth of one third (10 cm) of the packed bed (0.5 mm × 300 mm). The silver cement structure was successfully formed, and the silver cement frit endured mobile phase flow well when C18 modified ground silica monolith particles were used to make the packed bed. The formation of the silver cement frit was not successful when the stationary phase based on conventional spherical silica particles was used. Negligible reduction of chromatographic performance by the silver cemented frit was observed. This study serves as the first step toward realization of disposable micro-columns.

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Authors: Ahmad Hegazy, Shahira Ezzat, Iman Qasem, Mohamed Ali-Shtayeh, Mohammed Basalah, Hayssam Ali and Ashraf Hatamleh

The present study attempts to explore the phytochemical constituents of different extracts from Cynara cornigera and Cichorium endivia plant materials. The two species studied are native in Egypt. Five different solvents, viz., aqueous, methylene chloride, petroleum ether, ethyl acetate, and n-butanol were used. Phytochemical analysis revealed the presence of phenols, flavonoids, sterols (stigmasterol and beta-sitosterol), terpenes (α-amyrin, ursolic and oleanolic acid), and hydrocarbons (n-alkane), the latter found in low amount. The ethyl acetate and water extracts of C. cornigera root showed lower mass fractions of phenolic compounds ranged from 20 to 81 g/100 g, and higher amounts in ethyl acetate extract of the inflorescences and butanol extract of the root where values ranged from 195 to 399 g/100 g. The β-sitosterol and stigmasterol were present in all plant extracts. Oleanolic and ursolic acids were detected in roots, leaves and inflorescences of C. cornigera and in C. endivia shoot. The ethyl acetate extracts from C. cornigera leaf and inflorescence attained higher chemical diversity than the other extracts. Alternatively, sterols and triterpenes were the major constituents. The high chemical diversity of active constituents justifies the future potential use of the two species at commercial level.

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Abstract

This study was aimed to evaluate occurrence of antibiotic resistance and the presence of resistance determinants among clinical isolates of Acinetobacter baumannii. This cross-sectional study from January to September 2018 was performed on 59 A. baumannii strains isolated from clinical samples in the north of Iran. Isolates were identified by standard microbiologic tests and molecular method. Antimicrobial susceptibility testing was carried out by disk diffusion and broth microdilution methods. The presence of carbapenem resistance genes was detected by PCR method. All isolates were resistant to cefepime, meropenem, imipenem and ceftazidime. The lowest resistance rate was observed against doxycycline with 33.9%. Minimum inhibitory concentration (MIC) results showed that all carbapenem-resistant A. baumannii (CRAB) isolates were susceptible to colistin with MIC50 and MIC90 values of 1/2 µg/mL. Among 59 CRAB, bla OXA-23-like was the most prevalent gene (86.4%) followed by bla OXA-24-like (69.5%). Meanwhile, none of the clinical isolates harbored bla OXA-58-like gene. We found a high prevalence of CRAB strains harboring OXA-type carbapenemases in the north of Iran. Our results suggests that the presence of OXA-type genes was not directly correlated with the increase of imipenem MIC level, but can be clinically important as they contribute to the selection of CRAB strains.

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