Gadolinium and nephrogenic systemic fibrosis: time to tighten practice

Nephrogenic systemic fibrosis (NSF) is a relatively new entity, first described in 1997. Few cases have been reported, but the disease has high morbidity and mortality. To date it has been seen exclusively in patients with renal dysfunction. There is an emerging link with intravenous injection of gadolinium contrast agents, which has been suggested as a main triggering factor, with a lag time of days to weeks. Risk factors include the severity of renal impairment, major surgery, vascular events and other proinflammatory conditions. There is no reason to believe that children have an altered risk compared to the adult population. It is important that the paediatric radiologist acknowledges emerging information on NSF but at the same time considers the risk:benefit ratio prior to embarking on alternative investigations, as children with chronic kidney disease require high-quality diagnostic imaging

Regulated viral BDNF delivery in combination with Schwann cells promotes axonal regeneration through capillary alginate hydrogels after spinal cord injury.

Grafting of cell-seeded alginate capillary hydrogels into a spinal cord lesion site provides an axonal bridge while physically directing regenerating axonal growth in a linear pattern. However, without an additional growth stimulus, bridging axons fail to extend into the distal host spinal cord. Here we examined whether a combinatory strategy would support regeneration of descending axons across a cervical (C5) lateral hemisection lesion in the rat spinal cord. Following spinal cord transections, Schwann cell (SC)-seeded alginate hydrogels were grafted to the lesion site and AAV5 expressing brain-derived neurotrophic factor (BDNF) under control of a tetracycline-regulated promoter was injected caudally. In addition, we examined whether SC injection into the caudal spinal parenchyma would further enhance regeneration of descending axons to re-enter the host spinal cord. Our data show that both serotonergic and descending axons traced by biotinylated dextran amine (BDA) extend throughout the scaffolds. The number of regenerating axons is significantly increased when caudal BDNF expression is activated and transient BDNF delivery is able to sustain axons after gene expression is switched off. Descending axons are confined to the caudal graft/host interface even with continuous BDNF expression for 8weeks. Only with a caudal injection of SCs, a pathway facilitating axonal regeneration through the host/graft interface is generated allowing axons to successfully re-enter the caudal spinal cord. Recovery from spinal cord injury is poor due to the limited regeneration observed in the adult mammalian central nervous system. Biomaterials, cell transplantation and growth factors that can guide axons across a lesion site, provide a cellular substrate, stimulate axon growth and have shown some promise in increasing the growth distance of regenerating axons. In the present study, we combined an alginate biomaterial with linear channels with transplantation of Schwann cells within and beyond the lesion site and injection of a regulatable vector for the transient expression of brain-derived neurotrophic factor (BDNF). Our data show that only with the full combination axons extend across the lesion site and that expression of BDNF beyond 4weeks does not further increase the number of regenerating axons

Distribution of nitric oxide synthase in normal and cirrhotic human liver

Chronic liver disorders represent a serious health problem, considering that 300 million people worldwide are hepatitis B virus carriers, and 8,000–10,000 patients per year, in the U.S. alone, die as a result of liver failure caused by hepatitis C infection. Nitric oxide synthase (NOS) regulates hepatic vasculature; however, the patterns of expression and activity of NOS proteins in healthy and diseased human livers are unknown. Sections of diseased (n = 42) and control livers (n = 14) were collected during orthotopic liver transplants and partial hepatectomy. The diseased sections included alcoholic cirrhosis, viral hepatitis, cholestasis, acute necrosis, and uncommon pathologies including α(1)-anti-trypsin disorder. The endothelial NOS (eNOS), inducible NOS (iNOS), and neuronal NOS (nNOS) were studied by using the citrulline assay, Western immunoblot, immunohistochemistry, and in situ hybridization. The systemic generation of plasma NO metabolites was measured by HPLC. In control livers, Ca(2+)-dependent and –independent NOS activities were identified by Western analysis as eNOS and iNOS, respectively. The eNOS was uniformly distributed in the hepatocytes and also detected in the endothelium of hepatic arteries, terminal hepatic venules, sinusoids, and in biliary epithelium. The iNOS was detected in hepatocytes and localized mainly in the periportal zone of the liver acinus. This pattern of distribution of eNOS and iNOS in normal liver was confirmed by in situ hybridization. In diseased livers, there was a significant increase in Ca(2+)-independent NOS with the corresponding strong appearance of iNOS in the cirrhotic areas. The eNOS was translocated to hepatocyte nuclei. Thus, eNOS and iNOS proteins are differentially expressed in healthy human liver, and this expression is significantly altered in cirrhotic liver disorders