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White H.E.,National Genetics Reference Laboratory Wessex | Matejtschuk P.,Public Health England | Rigsby P.,Public Health England | Gabert J.,Biochemistry and Molecular Laboratory | And 32 more authors.

Serial quantitation of BCR-ABL mRNA levels is an important indicator of therapeutic response for patients with chronic myelogenous leukemia and Philadelphia chromosome-positive acute lymphoblastic leukemia, but there is substantial variation in the real-time quantitative polymerase chain reaction methodologies used by different testing laboratories. To help improve the comparability of results between centers we sought to develop accredited reference reagents that are directly linked to the BCR-ABL international scale. After assessment of candidate cell lines, a reference material panel comprising 4 different dilution levels of freezedried preparations of K562 cells diluted in HL60 cells was prepared. After performance evaluation, the materials were assigned fixed percent BCR-ABL/control gene values according to the International Scale. A recommendation that the 4 materials be established as the first World Health Organization International Genetic Reference Panel for quantitation of BCR-ABL translocation by real-time quantitative polymerase chain reaction was approved by the Expert Committee on Biological Standardization of the World Health Organization in November 2009. We consider that the development of these reagents is a significant milestone in the standardization of this clinically important test, but because they are a limited resource we suggest that their availability is restricted to manufacturers of secondary reference materials. © 2010 by The American Society of Hematology. Source

Soudani A.,University of Tunis | Hadjfredj S.,Biochemistry and Molecular Laboratory | Zribi M.,University of Tunis | Messaoud T.,Biochemistry and Molecular Laboratory | And 3 more authors.
Clinical Microbiology and Infection

Fluoroquinolones are increasingly used for the treatment of infections caused by multidrug-resistant Mycobacterium tuberculosis. Our study was designed to determine the frequency of the emergence of ciprofloxacin-resistant isolates in a university hospital (Rabta University Hospital Tunis, Tunisia) and to characterize the mutations responsible for the resistance phenotype. A total of 495 clinical M. tuberculosis isolates obtained from January 2005 to July 2008 were investigated for their susceptibility to ciprofloxacin, using the standard proportion method, PCR and DNA sequencing. Four resistant isolates (0.8%) were identified. Among these, only two carried point mutations in gyrA leading to amino acid changes other than the phenotypically silent S95T substitution. No gyrB missense mutations were found in any of the clinical isolates. Although fluoroquinolone resistance is still rare in Tunisia, accurate surveillance is needed in order to control the possible emergence of resistance to fluoroquinolones, which are essential for the successful treatment of multidrug-resistant tuberculosis. © 2010 The Authors. Journal Compilation © 2010 European Society of Clinical Microbiology and Infectious Diseases. Source

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