Chronic electrical stimulation of transected peripheral nerves preserves anatomy and function in the primary somatosensory cortex

The structure and function of the central nervous system strongly depend on the organization and efficacy of the incoming sensory input. A disruption of somesthetic input severely alters the metabolic activity, electrophysiological properties and even gross anatomical features of the primary somatosensory cortex. Here we examined, in the rat somatosensory cortex, the neuroprotective and therapeutic effects of artificial sensory stimulation after irreversible unilateral transection of a peripheral sensory nerve (the infraorbital branch of the trigeminal nerve). The proximal stump of the nerve was inserted into a silicon tube with stimulating electrodes, through which continuous electrical stimulation was applied for 12 h/day (square pulses of 100 μs, 3.0 V, at 20 Hz) for 4 weeks. Deafferented animals showed significant decreases in cortical evoked potentials, cytochrome oxidase staining intensity (layers II–IV), cortical volume (layer IV) and number of parvalbumin‐expressing (layers II–IV) and calbindin‐D28k‐expressing (layers II/III) interneurons. These deafferentation‐dependent effects were largely absent in the nerve‐stimulated animals. Together, these results provide evidence that chronic electrical stimulation has a neuroprotective and preservative effect on the sensory cortex, and raise the possibility that, by controlling the physical parameters of an artificial sensory input to a sectioned peripheral nerve, chronically deafferented brain regions could be maintained at near‐‘normal’ conditions. Our findings could be important for the design of sensory neuroprostheses and for therapeutic purposes in brain lesions or neural degenerative processes.     

Fetal phenotypes in otopalatodigital spectrum disorders

Otopalatodigital spectrum disorders (OPDSD) include OPD syndromes types 1 and type 2 (OPD1, OPD2), Melnick–Needles syndrome (MNS), and frontometaphyseal dysplasia (FMD). These conditions are clinically characterized by variable skeletal dysplasia associated in males, with extra‐skeletal features including brain malformations, cleft palate, cardiac anomalies, omphalocele and obstructive uropathy. Mutations in the FLNA gene have been reported in most FMD and OPD2 cases and in all instances of typical OPD1 and MNS. Here, we report a series of 10 fetuses and a neonatally deceased newborn displaying a multiple congenital anomalies syndrome suggestive of OPDSD and in whom we performed FLNA analysis. We found a global mutation rate of 44%. This series allows expanding the clinical and FLNA mutational spectrum in OPDSD. However, we emphasize difficulties to correctly discriminate OPDSD based on clinical criteria in fetuses due to the major overlap between these conditions. Molecular analyses may help pathologists to refine clinical diagnosis according to the type and the location of FLNA mutations. Discriminating the type of OPDSD is of importance in order to improve the genetic counseling to provide to families.     

Pulmonary metastasectomy for pediatric solid tumors

Most pediatric thoracic malignancy is pulmonary disease secondary to solid tumors of childhood. The management of isolated pulmonary metastases in adulthood is well documented. Little has been published to document the long-term outcome of pulmonary metastasectomy in childhood. A retrospective study was undertaken to assess the results of surgery for isolated pulmonary metastases. Twenty children underwent surgery over 12 years (mean follow-up 8 years). Five had Wilms tumor (mean age 51 months), eight had osteogenic sarcoma (mean age 141 months), three had rhabdomyosarcoma (mean age 92 months), two had hepatoblastoma (mean age 30 months) and two had teratoma (mean age 72 months). Four had bilateral synchronous metastases and thoracotomies, and one had bilateral metachronous metastases and thoracotomies. Nineteen children were discharged well within 10 days of surgery. There was one early complication: a death due to pneumonia. Four children subsequently died postoperatively with cranial metastases (mean 29 months postoperatively). The remaining 16 children remain alive and well. As part of the combined therapy, these results would support an aggressive surgical approach to this disease. Preoperative assessment should include contrast enhanced computed tomogram of the head and chest as well as chest X-ray taken immediately preoperatively to exclude metastases. Bilateral synchronous and metachronous thoracotomy is well tolerated in childhood.     

Influence of selected wound dressings on PMN elastase in chronic wound fluid and their antioxidative potential in vitro

Exudates from non-healing wounds contain elevated levels of proteolytic enzymes, like elastase from polymorphonuclear granulocytes (PMN elastase), reactive oxygen species (ROS) and reactive nitrogen species (RNS). The overproduction of proteolytic enzymes leads to reduced concentrations of growth factors and proteinase inhibitors, resulting in an imbalance between degradation and remodelling processes. Thus, the reduction of protein-degrading enzymes and scavenging of ROS and RNS seem to be suitable ways to support the healing process of chronic stagnating wounds. The aim of this study was to test selected wound dressings from different biomaterials (collagen, oxidized regenerated cellulose (ORC) and ORC/collagen mixture), regarding their antioxidative potential in vitro and their influence on the concentration and activity of PMN elastase in chronic wound fluid. Antioxidant capacity of the investigated wound dressing was determined by a pholasin-based chemiluminescent assay. PMN elastase concentration was determined by means of ELISA. Enzyme activities could be measured by a fluorescence assay. As the presented data demonstrates, all tested materials showed antioxidant capacity. In addition, the investigated materials were able to reduce the concentration and activity of PMN elastase. Beside other aspects, such as biocompatibility, biodegradability, fluid absorption and clinical effects (e.g. angiogenesis and microcirculation), the understanding of these properties may help to support the further refinement of wound dressings for improved wound healing.     

Sequence variation in the 3'-untranslated region of the dopamine transporter gene and attention-deficit hyperactivity disorder (ADHD).

The dopamine transporter gene (DAT1) has been reported to be associated with attention-deficit hyperactivity disorder (ADHD) in a number of studies [Cook et al. (1995): Am J Human Genet 56(4):9993-998; Gill et al. (1997): Mol Psychiatry 2(4):311-313; Waldman et al. (1998): Am J Human Genet 63(6):1767-1776; Barr et al. (2001): Biol Psychiatry 49(4):333-339; Curran et al. (2001): Mol Psychiatry 6(4):425-428; Chen et al. (2003): Mol Psychiatry 8(4):393-396]. Specifically, the 10-repeat allele of the 40-bp variable number of tandem repeats (VNTR) polymorphism located in the 3' untranslated region (UTR) of the gene has been found to be associated with ADHD. There is evidence from in vitro studies indicating that variability in the repeat number, and sequence variation in the 3'-UTR of the DAT1 gene may influence the level of the dopamine transporter protein [Fuke et al. (2001): Pharmacogenomics J 1(2):152-156; Miller and Madras (2002): Mol Psychiatry 7(1):44-55]. In this study, we investigated whether DNA variation in the DAT1 3'UTR contributed to ADHD by genotyping DNA variants around the VNTR region in a sample of 178 ADHD families. These included a MspI polymorphism (rs27072), a DraI DNA change (T/C) reported to influence DAT1 expression levels, and a BstUI polymorphism (rs3863145) in addition to the VNTR. We also screened the VNTR region by direct resequencing to determine if there was sequence variation within the repeat units that could account for the association. Our results indicate that DAT1 is associated with ADHD in our sample but not with alleles of the VNTR polymorphism. We did not find any variation in the sequence for either the 10- or 9-repeat alleles in the probands screened nor did we observe the reported DraI (T/C) variation. Our results therefore refute the possibility of the reported DraI variation or alleles of the VNTR as the functional variants contributing to the disorder.     

Induction of intervertebral disc-like cells from adult mesenchymal stem cells

The potential of adult mesenchymal stem cells (MSCs) to differentiate towards cartilage, bone, adipose tissue, or muscle is well established. However, the capacity of MSCs to differentiate towards intervertebral disc (IVD)-like cells is unknown. The aim of this study was to compare the molecular phenotype of human IVD cells and articular chondrocytes and to analyze whether mesenchymal stem cells can differentiate towards both cell types after transforming growth factor beta (TGF beta)-mediated induction in vitro. Bone marrow-derived MSCs were differentiated in spheroid culture towards the chondrogenic lineage in the presence of TGF beta(3) dexamethasone, and ascorbate. A customized cDNA-array comprising 45 cartilage-, bone-, and stem cell-relevant genes was used to quantify gene expression profiles. After TGF beta-mediated differentiation, MSC spheroids turned positive for collagen type II protein and expressed a large panel of genes characteristic for chondrocytes, including aggrecan, decorin, fibromodulin, and cartilage oligomeric matrix protein, although at levels closer to IVD tissue than to hyaline articular cartilage. Like IVD tissue, the spheroids were strongly positive for collagen type I and osteopontin. MSC spheroids expressed more differentiation markers at higher levels than culture-expanded IVD cells and chondrocytes, which both dedifferentiated in monolayer culture. In conclusion, mesenchymal stem cells adopted a gene expression profile that resembled native IVD tissue more closely than native joint cartilage. Thus, these cells may represent an attractive source from which to obtain IVD-like cells, whereas modification of culture conditions is required to approach the molecular phenotype of chondrocytes in hyaline cartilage.     

Genetic dissection of immunity in leprosy

Leprosy is a chronic infectious disease caused by Mycobacterium leprae that affects an estimated 700,000 new individuals each year. A strong contribution of host genetics to susceptibility to leprosy has long been suggested to account for the considerable variability observed between individuals exposed to M. leprae. As there is no relevant animal model for human leprosy, forward genetics is the main strategy used to identify the genes and, consequently, the immunological pathways involved in protective immunity to M. leprae. With respect to genome-wide screens, a major breakthrough has been reported this year; variants in the regulatory region shared by PARK2 and PACRG have been identified as being common risk factors for leprosy.