[Medical care of chronic kidney disease after kidney transplantation]

Kidney transplantation is the treatment of choice to enhance survival, morbidity and quality of life perceived by the patient. Despite improvements in short-term outcomes, a gap persists comparing with health of general population. A stringent collaboration between the family physician, the community nephrologists, the transplant center and others specialists is required. Recent recommendations have been published in France.

Nectar sugar composition and concentration in relation to pollination syndromes in Bromeliaceae

A first comprehensive dataset of nectar sugar composition and concentration in Bromeliaceae is presented, covering 111 species belonging to all three subfamilies. Based on this dataset, we examined the relationship between nectar traits and pollination syndromes in the family. Sugars in samples were assayed by high pressure liquid chromatography. All sampled species were grouped into three broad categories (trochilophilous, chiropterophilous, or lepidopterophilous) according to their main pollination mode. Significant differences between the different pollination syndromes were found in nectar sugar composition as well as concentration. For a total of four genera (Guzmania, Pitcairnia, Tillandsia and Vriesea), a comparison of nectar composition showed significant differences between trochilophilous and chiropterophilous species. Data presented here indicate that the characteristics of nectar in Bromeliaceae are predominantly determined by putative adaptations of nectar sugars to preferences of the pollinators rather than by phylogenetic relations.

Probabilistic model-based methodology for the conformational study of cyclic systems: application to copper complexes double-bridged by phosphate and related ligands

A methodology for the conformational study of cyclic systems through the statistical analysis of torsion angles is presented. It relies on a combination of different methods based on a probabilistic model which takes into account the topological symmetry of the structures. This methodology is applied to copper complexes double-bridged by phosphate and related ligands. Structures from the Cambridge Structural Database (CSD) are analyzed and the chair, boat-chair and boat conformations are identified as the most frequent conformations. The output of the methodology also provides information about distortions from the ideal conformations, the most frequent being: chair ↔ twist-chair, chair ↔ twist-boat-chair and boat ↔ twist-boat. Molecular mechanics calculations identify these distortions as energetically accessible pathways.

Pharmacology of ampakine modulators: from AMPA receptors to synapses and behavior

Ampakines are drugs structurally derived from aniracetam that potentiate currents mediated by AMPA type glutamate receptors. These drugs slow deactivation and attenuate desensitization of AMPA receptor currents, increase synaptic responses and enhance long-term potentiation. This review focuses mainly on recent physiological studies and on evidence for two distinct subfamilies. Type I compounds like CX546 are very effective in prolonging synaptic responses while type II compounds like CX516 mainly increase response amplitude. Type I and II drugs do not compete in binding assays and thus presumably act through separate sites. Their differences are likely to have consequences also for synaptic plasticity and behavior. Thus, while all ampakines facilitated long-term potentiation, only CX546 enhanced long-term depression. Further discussed are studies showing that ampakine effects vary substantially between neurons, with increases in EPSCs being larger in CA1 pyramidal cells than in thalamus and in hippocampal interneurons. In behavioral tests, ampakines facilitate learning in many paradigms including odor discrimination, spatial mazes, and conditioning, and they improved short-term memory in a non-matching-to-sample task. Positive results were also obtained in various psychological tests with human subjects. The drugs were effective in correcting behaviors in various animal models of schizophrenia and depression. Lastly, evidence is discussed that ampakines have few adverse effects at therapeutically relevant concentrations and that they protect neurons against neurotoxic insults, in part by mobilizing growth factors like BDNF. Type II drugs like CX516 in particular appear to be inherently safe since their ability to prolong responses is kinetically limited.

Darbepoetin alfa once every 2 weeks for treatment of anemia in dialysis patients: a combined analysis of eight multicenter trials

AIM

Darbepoetin alfa has a longer half-life than epoetin-(EPO) alfa or beta, allowing administration at less frequent intervals for the treatment of renal anemia. The aim of the present analysis was to evaluate the efficacy and tolerability of an every-2-week (Q2W) schedule of darbepoetin alfa in a large cohort of dialysis patients.

METHODS

Data were combined from eight similarly designed 24-week phase 3b European studies, in which patients receiving EPO alfa or beta once-weekly were converted to Q2W darbepoetin alfa. Darbepoetin alfa dosage was titrated to maintain hemoglobin (Hb) between 10 and 13 g/dl and efficacy was evaluated during a 4-week evaluation period.

RESULTS

In the 1,101 patients assigned to Q2W darbepoetin alfa (i.v., n = 196, s.c., n = 905), mean (SD) Hb levels were 11.53 (0.77) g/dl at baseline and 11.35 (1.04) g/dl at evaluation (mean change in Hb -0.27 g/dl, 95% confidence interval 0.34, -0.20). Hb levels were maintained between 10 and 13 g/dl during evaluation in 85% of patients. Darbepoetin alfa doses were similar at baseline and evaluation, and the i.v. and s.c. routes were associated with similar efficacy and dose requirements. Darbepoetin alfa was well-tolerated.

CONCLUSIONS

Q2W darbepoetin alfa is effective in maintaining Hb levels in dialysis patients switched from weekly rHuEPO, regardless of the route of administration and with no notable increase in the weekly equivalent dose.

Factors associated with anemia among incident pre-dialysis patients managed within a French care network

BACKGROUND AND AIMS

Despite guidelines concerning the management of renal anemia, the international literature reports that a large proportion of pre-dialysis patients have hemoglobin values lower than the recommended level. The present study analyzed the evolution of pre-dialysis Hb levels and erythropoietin use over a 4-year period and investigated factors associated with anemia.

METHODS

A total of 1315 patients initiating dialysis in Lorraine, France, were enrolled since 2001-2004. For each year, anemia, defined by Hb <11 g/dl, and erythropoietin use were investigated in three groups: all patients, patients whose dialysis was planned and patients whose dialysis was unplanned.

RESULTS

At initiation of dialysis, all groups showed increases over time in mean hemoglobin levels, proportion of patients without anemia and with erythropoietin therapy. Among patients whose first dialysis was planned in 2004, 43.8% had anemia and 67.9% had received erythropoietin, compared with 75.4% and 29.4%, respectively, when dialysis was unplanned. Patients receiving unplanned dialysis were more likely to have anemia (odds ratio (OR) = 2.6), as were those with a serum albumin level < 3.5 g/dl (OR = 2.1), body mass index < 30 kg/m2 (OR = 1.9) (all p < 0.001) or glomerular filtration rate < 10 ml/min/1.73 m2 (OR = 1.4, p = 0.04). The year of dialysis initiation was also associated with anemia (p = 0.024).

CONCLUSION

The proportion ofpatients starting dialysis with anemia might be reduced by earlier nephrology referral leading to erythropoietin administration, planned first dialysis while residual renal function remains, and greater attention to nutritional status.

Tolerability of enteric-coated mycophenolate sodium to 1 year in combination with cyclosporine and corticosteroids in renal transplant recipients

Enteric-coated mycophenolate sodium (EC-MPS) is therapeutically equivalent to mycophenolate mofetil, but delays release of mycophenolic acid until it reaches the small intestine. De novo renal transplant patients taking part in a 12-month, multicenter, randomized study received cyclosporine microemulsion (CsA-ME, early or delayed to day 6), EC-MPS, steroids, and interleukin-2 antagonist induction. Tolerability data relating to EC-MPS are reported. Ninety-seven patients were randomized to early CsA-ME and 100 patients to delayed CsA-ME. Median daily dose of EC-MPS was 1440 mg at all time points throughout the 12-month period. The most frequently reported adverse events were constipation, anemia, urinary tract infection, abdominal pain, leukopenia, and cytomegalovirus infection; there were four malignancies. Fifty patients (24.6%) discontinued EC-MPS prematurely by 12 months, including 42 patients (84%) who discontinued owing to adverse events. No patient discontinued treatment because of gastrointestinal adverse events. Two-thirds of patients (137 [67.5%]) maintained full EC-MPS dose throughout the 12-month study and did not require any dose reduction or dose interruption. EC-MPS is well tolerated in de novo renal transplant recipients when administered in combination with CsA-ME and steroids, with low rates of dose reductions or interruptions. Gastrointestinal adverse events were responsible for dose reduction or interruption in only 5% of patients.