Evaluation of P-glycoprotein expression in pain relevant tissues: understanding translation of efflux from preclinical species to human

<p class="ADMETabstracttext">Various efflux transporters, such as P-glycoprotein (P-gp) are now widely accepted to have profound influence on the disposition of substrates. Nevertheless, there is paucity of information about their expression and functionality in the pain relevant tissues (such as brain, spinal cord and dorsal root ganglia (DRG)) across various species. Therefore, our attempts were directed at evaluating P-gp expression in these tissues to understand its effect on the central nervous system (CNS) disposition. As a means of characterizing the normal tissue distribution of P-gp, immunohistochemistry was performed with two antibodies (C219 and H241) directed against different epitopes of MDR1 gene. Notable expression of P-gp was detected in the DRG of Sprague Dawley rat, Beagle Dog, Cynomolgous monkey as well as human. The expression of P-gp was observed in the CNS tissues with evident species differences, the expression of P-gp in human brain and spinal cord was lower than in rats and dogs but relatively comparable to that in monkeys. However, no species related differences were seen in the expression at the DRG level. Double-labelling using an antibody against a marker of endothelial cells confirmed that P-gp was exclusively localized in capillary endothelial cells. This study highlights the cross species similarities and differences in the expression of P-gp and thus serves as a vital step in understanding the translation of exposure of P-gp substrates to human.</p>

Motor neuron transduction after intracisternal delivery of AAV9 in a cynomolgus macaque

The image shows a section of the lumbar spinal cord from a cynomolgus macaque that had received AAV9.CB.EGFP via the cisterna magna. Expression of GFP in multiple motor neurons is visible. Injection into the cerebrospinal fluid has been shown to be an effective route of vector administration for neuron transduction.

A consideration of copyright for a national repository of humanities and social science data

In 2011 the Digital Repository of Ireland (DRI) began work on the development of an interactive national Trusted Digital Repository for contemporary and historical social and cultural data. Copyright and intellectual property rights were identified as essential areas which the DRI, as a content holder and data publisher, needed to investigate in order to develop workflows, policy and the Repository infrastructure. We established a Copyright and IP Task Force (CIPT) in January 2013 to capture and identify IP challenges from our stakeholder community and the DRI’s demonstrator collections. This report outlines the legislative context in which the CIPT worked, and how the CIPT addressed copyright challenges through the development of policies and a robust framework of legal documentation for the Repository. We also provide a case study on Orphan Works, detailing the process undertaken by the Clarke Stained Glass Studios Collection, one of DRI’s demonstrator projects, in preparing their content for online publication in the Repository.

A systematic review and meta-analysis of gene therapy in animal models of cerebral glioma: why did promise not translate to human therapy?

BACKGROUND

The development of therapeutics is often characterized by promising animal research that fails to translate into clinical efficacy; this holds for the development of gene therapy in glioma. We tested the hypothesis that this is because of limitations in the internal and external validity of studies reporting the use of gene therapy in experimental glioma.

METHOD

We systematically identified studies testing gene therapy in rodent glioma models by searching three online databases. The number of animals treated and median survival were extracted and studies graded using a quality checklist. We calculated median survival ratios and used random effects meta-analysis to estimate efficacy. We explored effects of study design and quality and searched for evidence of publication bias.

RESULTS

We identified 193 publications using gene therapy in experimental glioma, including 6,366 animals. Overall, gene therapy improved median survival by a factor of 1.60 (95% CI 1.53-1.67). Study quality was low and the type of gene therapy did not account for differences in outcome. Study design characteristics accounted for a significant proportion of between-study heterogeneity. We observed similar findings in a data subset limited to the most common gene therapy.

CONCLUSION

As the dysregulation of key molecular pathways is characteristic of gliomas, gene therapy remains a promising treatment for glioma. Nevertheless, we have identified areas for improvement in conduct and reporting of studies, and we provide a basis for sample size calculations. Further work should focus on genes of interest in paradigms recapitulating human disease. This might improve the translation of such therapies into the clinic.

Widespread gene transfer in the central nervous system of cynomolgus macaques following delivery of AAV9 into the cisterna magna

Adeno-associated virus serotype 9 (AAV9) vectors have recently been shown to transduce cells throughout the central nervous system of nonhuman primates when injected into the cerebrospinal fluid (CSF), a finding which could lead to a minimally invasive approach to treat genetic and acquired diseases affecting the entire CNS. We characterized the transduction efficiency of two routes of vector administration into the CSF of cynomolgus macaques—lumbar puncture, which is typically used in clinical practice, and suboccipital puncture, which is more commonly used in veterinary medicine. We found that delivery of vector into the cisterna magna via suboccipital puncture is up to 100-fold more efficient for achieving gene transfer to the brain. In addition, we evaluated the inflammatory response to AAV9-mediated GFP expression in the nonhuman primate CNS. We found that while CSF lymphocyte counts increased following gene transfer, there were no clinical or histological signs of immune toxicity. Together these data indicate that delivery of AAV9 into the cisterna magna is an effective method for achieving gene transfer in the CNS, and suggest that adapting this uncommon injection method for human trials could vastly increase the efficiency of gene delivery.

Contribution of TRPC3 to store-operated calcium entry and inflammatory transductions in primary nociceptors

BACKGROUND

Prolonged intracellular calcium elevation contributes to sensitization of nociceptors and chronic pain in inflammatory conditions. The underlying molecular mechanisms remain unknown but store-operated calcium entry (SOCE) components participate in calcium homeostasis, potentially playing a significant role in chronic pain pathologies. Most G protein-coupled receptors activated by inflammatory mediators trigger calcium-dependent signaling pathways and stimulate SOCE in primary afferents. The aim of the present study was to investigate the role of TRPC3, a calcium-permeable non-selective cation channel coupled to phospholipase C and highly expressed in DRG, as a link between activation of pro-inflammatory metabotropic receptors and SOCE in nociceptive pathways.

RESULTS

Using in situ hybridization, we determined that TRPC3 and TRPC1 constitute the major TRPC subunits expressed in adult rat DRG. TRPC3 was found localized exclusively in small and medium diameter sensory neurons. Heterologous overexpression of TRPC3 channel subunits in cultured primary DRG neurons evoked a significant increase of Gd3+-sensitive SOCE following thapsigargin-induced calcium store depletion. Conversely, using the same calcium add-back protocol, knockdown of endogenous TRPC3 with shRNA-mediated interference or pharmacological inhibition with the selective TRPC3 antagonist Pyr10 induced a substantial decrease of SOCE, indicating a significant role of TRPC3 in SOCE in DRG nociceptors. Activation of P2Y2 purinoceptors or PAR2 protease receptors triggered a strong increase in intracellular calcium in conditions of TRPC3 overexpression. Additionally, knockdown of native TRPC3 or its selective pharmacological blockade suppressed UTP- or PAR2 agonist-evoked calcium responses as well as sensitization of DRG neurons. These data show a robust link between activation of pro-inflammatory receptors and calcium homeostasis through TRPC3-containing channels operating both in receptor- and store-operated mode.

CONCLUSIONS

Our findings highlight a major contribution of TRPC3 to neuronal calcium homeostasis in somatosensory pathways based on the unique ability of these cation channels to engage in both SOCE and receptor-operated calcium influx. This is the first evidence for TRPC3 as a SOCE component in DRG neurons. The flexible role of TRPC3 in calcium signaling as well as its functional coupling to pro-inflammatory metabotropic receptors involved in peripheral sensitization makes it a potential target for therapeutic strategies in chronic pain conditions.

Comparison between laparoscopic and open radical nephrectomy for the treatment of primary renal tumors in children: single-center experience over a 5-year period

OBJECTIVES

To compare the outcomes of laparoscopic nephrectomy (LN) with open radical nephrectomy (ORN) in the management of consecutive pediatric neoplasms.

PATIENTS AND METHODS

Retrospective cohort study of consecutive children treated for primary renal tumors between 2006 and 2011, segregated based on surgical modality (LN/ORN). Pre-, intra- and postoperative data and outcomes were collected.

RESULTS

Demographics from the 45 patients (13 LN, 32 ORN) were similar, and tumors in the LN group were smaller [6.59 ± 1.8 cm vs. 10.99 ± 2.99 cm ORN (p < 0.05)]. Six patients had preoperative chemotherapy (two LN, four ORN). No tumor ruptures occurred with either technique. Wilms tumor (seven LN, 24 ORN) was the most common diagnosis, followed by renal cell carcinoma (four LN, four ORN). Procedure length was similar between groups (282 ± 79 LN, 263 ± 81 min ORN). Mean length of stay was significantly shorter for LN (2.9 vs. 5.9 days; p = 0.002). Postoperative narcotic requirements and use of nasogastric tube were higher in the ORN group. After a median follow-up of 18 (LN) and 33 months (ORN), 1 and 4 recurrences occurred, respectively.

CONCLUSIONS

LN is an attractive alternative to open surgery in carefully selected cases of pediatric renal tumors. Procedure length and incidence of intra-operative rupture were not increased, while post-operative recovery and hospital stay were shorter for LN. Longer follow-up is mandatory to confirm comparable oncological outcomes to ORN.