Radiolytic stability of N,N-dialkyl amide: effect on Pu(iv) complexes in solution.

The radiolytic degradation of three N,N-dialkyl amide ligands relevant to nuclear fuel reprocessing was studied. The degradation of these ligands: N,N di-2-ethyhexylbutyramide (DEHBA), N,N di-2-ethyhexylisobutyramide (DEHiBA) and N,N di-2-ethyhexyl-3-dimethylbutanamide (DEHDMBA) was examined to evaluate the effect of the structure on the formation of degradation products as well as to compare alpha induced degradation to gamma induced degradation. In situ alpha radiolysis by introduction of plutonium(iv) as the alpha source in the solution and ex situ gamma radiolysis with 60Co as the gamma source were compared. Upon identification of the main degradation products, a degradation scheme was proposed. The effects of radiation on the stability of Pu-monoamide complexes were discussed. Theoretical calculations were also performed to determine bond dissociation energy and estimate the relative strength of the bond in the molecule. The results show that neither the type of radiation (alpha vs. gamma) nor the structure modification (introduction of branching on the alkyl chain off the carbonyl carbon) of the molecule significantly impact the formation of degradation products under the conditions studied. Moreover, it was observed that the overall stability of the monoamide remains good and that Pu complexation is not greatly affected by either alpha or gamma irradiation.

[Hypertrichosis and gingival hypertrophy regression in renal transplants following the substitution of cyclosporin by tacrolimus]. / Régression de l'hypertrichose et de l'hypertrophie gingivale chez des greffés rénaux suite à la substitution de la cyclosporine par le tacrolimus.

Gingival Hyperplasia (GH) and hypertrichosis (HT) are two sides effects associated with the usage of cyclosporine (CyA) but not with tacrolimus (FK 506). The aim of this study is to evaluate the efficacy and security of the conversion from CsA to FK 506 to treat those two complications. From August 1996 to May 1997, 15 patients (9 males, 6 females) aged from 23 to 63 years old (38 +/- 14, mean +/- SD) were switched from CsA to FK 506, 12 for GH, 2 for HT and one for combined presentation. FK 506 was first initiated at a dose of 0.15 mg/kg/day and then adjusted to a level target of 8 ng/ml. The conversion was done on an out patient basis at average 35 (5-83) months after transplantation. Patients were followed prospectively for 12 months. There was a significant reduction in GH in all patients within 3 months. Five out 13 patients had a complete resolution of GH within three months of conversion, 9/12 within 6 months and all by 12 months. HT resolved completely within 6 months. No rejection episode occurred and the serum creatinin remain stable over one year post conversion. Conversion from CsA to FK 506 is thus a safe and valid option to treat CsA induced GH and HT.

Mycoplasma fermentans DNA is infrequently detected in urine specimens from renal transplant recipients.

Mycoplasma fermentans is a likely causative agent of HIV-associated nephropathy. In a pilot study, M. fermentans DNA was detected with polymerase chain reaction (PCR) in urine samples from renal allograft recipients; nine (39.1%) out of 23 renal allograft recipients (most of whom had chronic allograft rejection) and none of the 20 controls, were infected with M. fermentans. A cross-sectional study was conducted to investigate the prevalence of M. fermentans in urine samples from renal allograft recipients. Midstream urine samples were centrifuged at 13,000 x g, purified with QIAamp and tested with PCR using RW004/RW005 and an internal control to screen for the presence of inhibitors. Of the 264 participants recruited, 263 completed the questionnaire (172 men, 92 women); 53 had chronic renal allograft rejection, 106 had chronic renal dysfunction without rejection, 69 had a normal renal allograft for more than 3 months and 35 had a renal allograft for less than 3 months. All urine samples yielded positive results for the internal control. Mycoplasma fermentans DNA was detected once i prospectively collected urine samples. The only individual infected with M. fermentans was also seropositive for HIV-1. This study demonstrates that M. fermentans can be at most sporadically detected in urine from patients living with a renal allograft but is not implicated in chronic rejection of allograft.

[Acute tubular necrosis in patients after kidney transplantation: associated factors and impact on functional survival of the graft]. / Nécrose tubulaire aiguë chez les transplantés rénaux: facteurs associés et impact sur la survie fonctionnelle de la greffe.

Acute tubular necrosis (ATN) represents a serious problem in kidney transplantation. We have reviewed the causes and effects of ATN on kidney transplant patients treated in our hospital between June 1981 and December 1992. We analyzed 359 consecutive kidney transplants performed in 338 patients (213 male and 125 female). There were 311 first grafts. The actuarial functional graft survival (AFGS) was 85% at 1 year and 58.2% at 10 years. The incidence of long-term chronic rejection, the 1-year creatinine blood level (CBL) and the AFGS are summarized: [table: see text] The donor age and the PRA level were significantly correlated with ATN occurrence. ATN after transplantation was associated with a poorer function and survival of the kidney graft. Better donor and patient selection could decrease the occurrence of ATN, thus improving the graft outcome.