The influence of CYP3A,PPARA, and POR genetic variants on the pharmacokinetics of tacrolimus and cyclosporine in renal transplant recipients

Purpose

Tacrolimus (Tac) and cyclosporine (CsA) are mainly metabolized by CYP3A4 and CYP3A5. Several studies have demonstrated an association between the CYP3A5 genotype and Tac dose requirements. Recently, CYP3A4, PPARA, and POR gene variants have been shown to influence CYP3A metabolism. The present study investigated potential associations between CYP3A5*3, CYP3A4*22, PPARA c.209-1003G>A and c.208?+?3819A>G, and POR*28 alleles and dose-adjusted concentrations (C/D) of Tac and CsA in 177 renal transplant patients early post-transplant.

Methods

All patients (n?=?177) were genotyped for CYP3A4*22, CYP3A5*3, POR*28, PPARA c.209-1003G>A, and PPARA c.208?+?3819A>G using real-time polymerase chain reaction (PCR) and melting curve analysis with allele-specific hybridization probes or PCR restriction fragment length polymorphisms (RFLP) methods. Drug concentrations and administered doses were retrospectively collected from patient charts at Oslo University Hospital, Rikshospitalet, Norway. One steady-state concentration was collected for each patient.

Results

We confirmed a significant impact of the CYP3A5*3 allele on Tac exposure. Patients with POR*28 and PPARA variant alleles demonstrated 15 % lower (P?=?0.04) and 19 % higher (P?=?0.01) Tac C₀/D respectively. CsA C₂/D was 53 % higher among CYP3A4*22 carriers (P?=?0.03).

Conclusion

The results support the use of pre-transplant CYP3A5 genotyping to improve initial dosing of Tac, and suggest that Tac dosing may be further individualized by additional POR and PPARA genotyping. Furthermore, initial CsA dosing may be improved by pre-transplant CYP3A4*22 determination.     

Case reports

The clinical presentation of lead intoxication may vary widely and in the absence of a high clinical index of suspicion, the diagnosis may be missed. The effects of lead on mitochondrial oxidative phosphorylation and its interaction with calcium-mediated processes explain the heterogenous presentation. In this case report, the diagnosis was finally made when bilateral wrist drop developed on top of abdominal cramps and anemia. Before, ascites raised the suspicion of a tumor. Therefore, each element of the triad of unexplained anemia, abdominal cramps, and bilateral wrist (or foot) drop should lead any physician to consider the diagnosis of lead intoxication. This case also illustrates the importance of a careful and meticulous social history in patient management.     

Basolateral ClC-2 chloride channels in surface colon epithelium: regulation by a direct effect of intracellular chloride

BACKGROUND & AIMS: The principal function of the colon in fluid homeostasis is the absorption of NaCl and water. Apical membrane Na(+) channels, Na(+)/H(+), and Cl(-)/HCO(3)(-) exchangers have been postulated to mediate NaCl entry into colonocytes. The basolateral exit pathway for Cl(-) has recently been proposed to be via ClC-2 channels present in that membrane domain in surface epithelium. The aim of this report is to obtain functional data for a basolateral localization of ClC-2 and explore a possible direct regulation by intracellular Cl(-). METHODS: Guinea pig colon epithelium with the apical membrane perforated with nystatin in Ussing chambers is used to show a basolateral Cl(-) conductance. Gramicidin D perforated-patch configuration of the patch-clamp technique is used on isolated surface colonocytes. Heterologous expression of the recombinant channel and the whole-cell configuration are used to investigate a direct regulation by intracellular Cl(-). RESULTS: A basolateral membrane conductance with the characteristics of ClC-2 channels, including Cd(2+) sensitivity, selectivity, and inhibition by extracellular alkalinization, is present in distal colon epithelium. The effect of intracellular Cl(-) on this conductance suggests activation by the permeant anion. Using the recombinant ClC-2 channel, a strong dependence of its activity on intracellular Cl(-) is shown, with a shift of activation to more positive voltages as [Cl(-)](i) is increased. CONCLUSIONS: It is suggested that ClC-2 serves as an exit pathway for Cl(-) in the basolateral membranes of the distal colon and that its dependence on [Cl(-)](i) might provide a cross-talk mechanism to match fluxes at the apical and basolateral domains of these epithelial cells.     

Cell-based resurfacing of large cartilage defects: long-term evaluation of grafts from autologous transgene-activated periosteal cells in a porcine model of osteoarthritis

OBJECTIVE: To investigate the potential of transgene-activated periosteal cells for permanently resurfacing large partial-thickness cartilage defects. METHODS: In miniature pigs, autologous periosteal cells stimulated ex vivo by bone morphogenetic protein 2 gene transfer, using liposomes or a combination of adeno-associated virus (AAV) and adenovirus (Ad) vectors, were applied on a bioresorbable scaffold to chondral lesions comprising the entire medial half of the patella. The resulting repair tissue was assessed, 6 and 26 weeks after transplantation, by histochemical and immunohistochemical methods. The biomechanical properties of the repair tissue were characterized by nanoindentation measurements. Implants of unstimulated cells and untreated lesions served as controls. RESULTS: All grafts showed satisfactory integration into the preexisting cartilage. Six weeks after transplantation, AAV/Ad-stimulated periosteal cells had adopted a chondrocyte-like phenotype in all layers; the newly formed matrix was rich in proteoglycans and type II collagen, and its contact stiffness was close to that of healthy hyaline cartilage. Unstimulated periosteal cells and cells activated by liposomal gene transfer formed only fibrocartilaginous repair tissue with minor contact stiffness. However, within 6 months following transplantation, the AAV/Ad-stimulated cells in the superficial zone tended to dedifferentiate, as indicated by a switch from type II to type I collagen synthesis and reduced contact stiffness. In deeper zones, these cells retained their chondrocytic phenotype, coinciding with positive staining for type II collagen in the matrix. CONCLUSION: Large partial-thickness cartilage defects can be resurfaced efficiently with hyaline-like cartilage formed by transgene-activated periosteal cells. The long-term stability of the cartilage seems to depend on physicobiochemical factors that are active only in deeper zones of the cartilaginous tissue.     

Activation of vascular smooth muscle cells by TNF and PDGF: overlapping and complementary signal transduction mechanisms

OBJECTIVE: Because tumor necrosis factor-alpha (TNF) has been implicated in the pathogenesis of vein graft neointimal hyperplasia, we sought to determine mechanisms by which TNF could induce proliferative and migratory responses in smooth muscle cells (SMCs). METHODS AND RESULTS: In rabbit jugulocarotid interposition vein grafts, SMCs expressed TNF as early as four days postoperatively. In rabbit aortic SMCs, TNF and platelet-derived growth factor (PDGF) elicited comparable migration (1.7-fold/basal), and their effects were partially additive. In contrast, while TNF failed to promote SMC [(3)H]thymidine incorporation alone, it doubled the [(3)H]thymidine incorporation observed with PDGF alone. To gain mechanistic insight into these phenomena, we found that TNF and PDGF each activated p38(mapk) equivalently in SMCs, but that PDGF was two to three times more efficacious than TNF in activating SMC extracellular signal-regulated kinases (ERK) 1 and 2 and phosphoinositide 3-kinase. However, only TNF activated NF kappa B. SMC [(3)H]thymidine incorporation that depended on TNF, but not PDGF, was abolished by overexpression of a dominant-negative I kappa B alpha mutant. Inhibition of ERK activation by U0126 reduced SMC migration stimulated only by PDGF (by 35%, P<0.05), but not by TNF. Inhibition of phosphoinositide 3-kinase by LY294002, however, significantly reduced both TNF- and PDGF-stimulated chemotaxis (by 38-54%, P<0.05). In contrast, both U0126 and LY294002 abolished SMC [(3)H]thymidine incorporation induced by either TNF, PDGF, or both agonists. CONCLUSIONS: In primary rabbit SMCs, TNF promotes migration and mitogenesis through signaling mechanisms that are both distinct from and overlapping with those employed by PDGF. TNF-induced SMC mitogenesis requires complementary co-stimulation with other growth factors.     

Limited Literacy and Poor Health: The Role of Social Mobility in Germany and the United States

The Organization for Economic Cooperation and Development (OECD) implemented the Program for the International Assessment of Adult Competencies (PIAAC) to provide policymakers with nationally representative profiles of knowledge, skills, and competencies. Results among participating countries indicate that the United States and Germany stand out as having the strongest relationship between literacy skills and self-reported health. Our analysis addresses factors that could mediate the particularly strong link between low literacy and poor health in these two countries and possible remedies for the problem. In particular, PIACC results also reveal that the United States and Germany share the most entrenched multigenerational literacy problem among the countries in the PIAAC survey. In spite of the many social differences that currently distinguish Germany and the United States, these countries share the lowest level of social mobility for education. Promoting social mobility by making higher education more accessible for those whose parents did not have the chance to access it might thus not only promote literacy and social capital, but indirectly also promote public health. Given the PIACC findings, the concept of social mobility and opportunities to dissolve the educational stratification merit more attention in public health research.