1.
Calibration and data processing in gas chromatography combustion isotope ratio mass spectrometry.
Zhang, Y, Tobias, HJ, Sacks, GL, Brenna, JT
Drug testing and analysis. 2012;(12):912-22
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Abstract
Compound-specific isotope analysis (CSIA) by gas chromatography combustion isotope ratio mass spectrometry (GCC-IRMS) is a powerful technique for the sourcing of substances, such as determination of the geographic or chemical origin of drugs and food adulteration, and it is especially invaluable as a confirmatory tool for detection of the use of synthetic steroids in competitive sport. We review here principles and practices for data processing and calibration of GCC-IRMS data with consideration to anti-doping analyses, with a focus on carbon isotopic analysis ((13)C/(12)C). After a brief review of peak definition, the isotopologue signal reduction methods of summation, curve-fitting, and linear regression are described and reviewed. Principles for isotopic calibration are considered in the context of the Δ(13)C = δ(13)C(M) - δ(13)C(E) difference measurements required for establishing adverse analytical findings for metabolites (M) relative to endogenous (E) reference compounds. Considerations for the anti-doping analyst are reviewed.
2.
Mycophenolate mofetil therapy for children with steroid-resistant nephrotic syndrome.
Li, Z, Duan, C, He, J, Wu, T, Xun, M, Zhang, Y, Yin, Y
Pediatric nephrology (Berlin, Germany). 2010;(5):883-8
Abstract
Treating children with steroid-resistant nephrotic syndrome (SRNS) has been a clinical challenge for pediatricians. We recruited 24 children (18 boys and six girls) with steroid-resistant idiopathic nephrotic syndrome (SRINS) who were <2 years. All patients were administered prednisone 2 mg/kg per day prior to mycophenolate mofetil (MMF). By the end of the eighth week, MMF was initiated at 25-30 mg/kg daily for 6- 12 months. Prednisone dose was reduced stepwise. Biochemical assays were performed every 2 months. Complete remission was achieved in 15 patients, partial remission in six, and no response to MMF was noted in three. With MMF treatment, the levels of urinary protein and serum cholesterol decreased and that of serum albumin increased in a time-dependant manner. We demonstrated the MMF could reduce proteinuria in SRINS children <2 years. Our study suggests that MMF therapy might be an effective strategy for treating SRINS in children <2 years.