Azathioprine is associated with enhanced skin photosensitivity to ultraviolet A (UVA) and leads to incorporation of 6-thioguanine (6-TG) into DNA of dividing cells. Unlike canonical DNA, 6-TG DNA is damaged by UVA, which comprises more than 90% of the ultraviolet reaching earth. Skin photosensitivity to UVA and UVB was measured in 48 kidney transplant patients immunosuppressed either by azathioprine (n = 32) or mycophenolate (n = 16). In 23 patients, azathioprine was subsequently replaced by mycophenolate and skin photosensitivity, DNA 6-TG content in peripheral blood mononuclear cells, and susceptibility to UVA-induced DNA damage were monitored for up to 2 years. The mean minimal erythema dose to UVA on azathioprine was twofold lower than on mycophenolate. Three months after replacing azathioprine by mycophenolate mofetil, the minimal erythema dose to UVA had increased from 15 to 25 J/cm 2 (p < 0.001) accompanied by reduced DNA 6-TG content. P53 protein expression in irradiated skin indicated reduced susceptibility to UVA-induced DNA damage. 6-TG DNA in peripheral blood mononuclear cells remained measurable for over 2 years. Replacing azathioprine selectively reduced the skin photosensitivity to UVA, attenuated UVA-induced skin DNA damage, and is likely based on incorporated 6-TG in DNA.
ammonium citrate and citric acid serves not only to keep iron in solution but as an efficient buffer solution; that the results obtained by the use of citric acid-ammonium citrate as a buffer are comparable to those obtained by the Waring-Fales-Ware method and have a precision of 1 part in 1000; that zinc cannot be determined by weighing as zinc sulfide; and that 50 ml. of a 20 per cent solution of ammonium thiocyanate serve to salt out zinc sulfide and to minimize the postprecipitation of cobalt sulfide.
N. J. NUMEROUS chemical and microbiological methods for the separate determination of thiamin and riboflavin have appeared in the literature. The procedure described below makes it possible to determine both vitamins on the same sample, and has enabled the authors to make complete analyses on as many as 8 to 12 samples in the course of a 7-hour day. The number is limited only by the extraction units in operation and available personnel. The method is an extension of the one proposed for thiamin (2), which includes a review of the literature on the determination of this vitamin.
Bronchoscopic lung volume reduction (BLVR) has been demonstrated an efficient and safe alternative to surgery in multiple randomized trials and retrospective cohort studies. However, despite its minimal invasiveness BLVR is not without potential harm. Complications and their incidents differ significantly between the individual BLVR techniques (valves, coils, vapour or sealant) which are bearing varying device- and intervention-dependent risks. Interventional pulmonologists must be aware of potential side effects and their management to anticipate and ensure highest quality treatment of the severely ill emphysema patient.
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