Mycophenolate mofetil treatment following renal transplantation decreases GTP concentrations in mononuclear leucocytes

MMF (mycophenolate mofetil) has been proven to provide an effective immunosuppression by non-competitive selective reversible inhibition of IMPDH (inosine monophosphate dehydrogenase), the enzyme playing a crucial role in GTP biosynthesis. However, the exact metabolic changes induced by inhibition of IMPDH in target cells of the immune system have been the subject of recent debate. The aim of the present study was to evaluate whether MMF treatment produced sustained changes in the guanosine nucleotide pool of MNLs (mononuclear leucocytes) in vivo. Sixty-two renal failure patients were divided into three groups: chronic renal failure patients undergoing haemodialysis (CRF-HD; n=20) and two groups of patients after renal transplantation, the first on AZA (azathioprine; TN-AZA; n=23) and the second treated with MMF (TN-MMF; n=19). In addition, MNLs from 25 healthy subjects were analysed as controls. Anion-exchange HPLC was used to quantify purine and pyrimidine nucleotides in MNLs. We report a significant decrease in GTP and the total MNL guanine nucleotide pool in the TN-MMF group (P<0.05) compared with control, CRF-HD and TN-AZA groups, although no significant differences were found between any of the other groups. Adenine nucleotide concentrations in MNLs were decreased in the TN-AZA group, but not in the TN-MMF group compared with the CRF-HD group and controls. There were no differences in CTP concentrations, but UTP concentrations were decreased in the CRF-HD, TN-AZA and TN-MMF groups compared with controls. MMF caused a significant and sustained decrease in the guanine nucleotide pool in MNLs from renal transplant recipients. This decrease contrasts with the elevation in GTP reported in erythrocytes of MMF-treated patients.     

Synthesis and cytostatic properties of some 6H-Indolo[2, 3-b][1, 8]naphthyridine derivatives

The new and efficient synthesis of the title heterocyclic ring system is described starting from suitable 2-chloro-1, 8-naphthyridines. The synthesized 6H-indolo[2, 3-b][1, 8]naphthyridine derivatives were tested in vitro on 55 tumor cell lines for their anticancer properties. The presence of the acetylamino moiety at position 3 in the main ring system proved to be crucial for the cytostatic activity of this class of compounds.     

C34T AMP deaminase 1 gene mutation protects cardiac function in donors

Dysfunction of the donor heart is an important clinical problem that could be affected by genetic factors. We tested the hypothesis that possession of the C34T nonsense mutation in AMPD1 gene, which is known to improve survival in chronic heart failure, protects against cardiac dysfunction in donors. Genetic analysis for C34T mutation was performed by single-stranded conformational polymorphism (SSCP) in 22 donor hearts used for transplantation, 10 unused donor hearts with acute heart failure (HF), 37 patients with chronic HF, and 207 healthy controls. We found a significantly higher frequency of the mutation among donors with healthy hearts used for transplantation (31.8%) as compared to control population (13.5%, P < 0.001) and a lower frequency in dysfunctional donor hearts (5.0% P = 0.025); the frequency of the C34T mutation in patients with chronic heart failure (14.8%) was not different from that of a control population. The presence of the C34T mutation in AMPD1 gene appears to be protective against acute heart failure in cardiac donors.     

Association between cerebrospinal fluid levels of asymmetric dimethyl-L-arginine, an endogenous inhibitor of endothelial nitric oxide synthase, and cerebral vasospasm in a primate model of subarachnoid hemorrhage

OBJECT: Decreased availability of nitric oxide (NO) has been proposed to evoke delayed cerebral vasospasm after sub-arachnoid hemorrhage (SAH). Asymmetric dimethyl-L-arginine (ADMA) inhibits endothelial NO synthase (eNOS) and, therefore, may be responsible for decreased NO availability in cases of cerebral vasospasm. The goal of this study was to determine whether ADMA levels are associated with cerebral vasospasm in a primate model of SAH. METHODS: Twenty-two cynomolgus monkeys (six control animals and 16 with SAH) were used in this study. The levels of ADMA, L-arginine, L-citrulline, nitrites, and nitrates in cerebrospinal fluid (CSF) and serum were determined on Days 0, 7, 14, and 21 following onset of SAH. Cerebral arteriography was performed to assess the degree of vasospasm. Western blot analyses of the right and left middle cerebral arteries (MCAs) were performed to assess the expression of eNOS, type I protein-arginine methyl transferase (PRMT1) and dimethylarginine dimethylaminohydrolase (DDAH2). Cerebrospinal fluid levels of ADMA remained unchanged in the control group (six animals) and in animals with SAH that did not have vasospasm (five animals; p = 0.17), but the levels increased in animals with vasospasm (11 animals) on Day 7 post-SAH (p < 0.01) and decreased on Days 14 through 21 (p < 0.05). Cerebrospinal fluid levels of ADMA correlated directly with the degree of vasospasm (correlation coefficient = 0.7, p = 0.0001; 95% confidence interval: 0.43-0.83). Levels of nitrite and nitrate as well as those of L-citrulline in CSF were decreased in animals with vasospasm. Furthermore, DDAH2 expression was attenuated in the right spastic MCA on Day 7 post-SAH, whereas eNOS and PRMT1 expression remained unchanged. CONCLUSIONS: Changes in the CSF levels of ADMA are associated with the development and resolution of vasospasm found on arteriograms after SAH. The results indicate that endogenous inhibition of eNOS by ADMA may be involved in the development of delayed cerebral vasospasm. Inhibition of ADMA production may provide a new therapeutic approach for cerebral vasospasm after SAH.     

Uretero-uterine fistula as complication of the cesarean section

Case presentation: 26 y.o woman 3 weeks after cesarean section complained of urine leakage from vagina. Urography revealed uretero-uterine fistula. Surgery was performed--3 dexon sutures attaching strictured ureter to the uterine were localized and then cut off. Distally obliterated ureter was separated out of adjacent tissues. The strictured part of ureter was then incised on the length of ca 8 cm, pig tail catheter was induced and human dura mater allograft was put on and sewed in into the strictured segment. In the long term follow-up the woman gave birth to two more children in the vaginal delivery without any complications. Urographies revealed no fistula, no stricture recurrency and normal urine passage.     

Determination of in vitro activity renin inhibitors by HPLC method

A high-performance liquid chromatographic assay has been developed to the separation of angiotensin I, tetradecapeptide and the tetrapeptide Leu-Val-Tyr-Ser. This purpose is achieved in a single step, using HPLC technique in the reversed phase system. The method is based on enzymatic hydrolysis of a substrate renin (TDP) with formation of angiotensin I (DP). After 1 h incubation at 37 degrees C the reaction mixture is introduced directly into the chromatographic system. A 200 microl reaction mixture is needed for analysis. Acetonitrile gradient in 0.01 M ammonium acetate buffer allows a satisfactory separation of hydrolysis products. The application of this technique for the determination of in vitro renin activity and evaluation the potency of human renin inhibitors, employing the artificial renin substrate tetradecapeptide, is demonstrated.