Spinal cord repair: future directions

The role of the androgen receptor in the pathogenesis of obesity and its utility as a target for obesity treatments

Obesity is associated with hypothalamic-pituitary-testicular axis dysregulation in males. Here, we summarize recent evidence derived from clinical trials and studies in preclinical animal models regarding the role of androgen receptor (AR) signaling in the pathophysiology of males with obesity. We also discuss therapeutic strategies targeting the AR for the treatment of obesity and their limitations and provide insight into the future research necessary to advance this field.

Differential role of epigenetic modulators in malignant and normal stem cells: a novel tool in preclinical in vitro toxicology and clinical therapy

Adult stem cells are primitive cells that undergo asymmetric division, thereby giving rise to one clonogenic, self-renewing cell and one cell able to undergo multipotent differentiation. Disturbance of this controlled process by epigenetic alterations, including imbalance of histone acetylation/histone deacetylation and DNA methylation/demethylation, may result in uncontrolled growth, formation of self-renewing malignant stem cells and eventually cancer. In view of this notion, several epigenetic modulators, in particular those with histone deacetylase inhibiting activity, are currently being tested in phase I and II clinical trials for their promising chemotherapeutic properties in cancer therapy. As chromatin modulation is also involved in regulation of differentiation, normal development, embryonic and adult stem cell functions and maintenance of their plasticity during embryonic organogenesis, the question can be raised whether predestined cell fate can be modified through epigenetic interference. And if so, could this strategy enforce adult stem cells to differentiate into different types of functional cells? In particular, functional hepatocytes seem important for preclinical toxicity screening of candidate drugs. This paper reviews the potential use and relevance of epigenetic modifiers, including inhibitors of histone deacetylases and DNA methyltransferases (1) to change cell fate and 'trans'differentiate normal adult stem cells into hepatocyte-like cells and (2) to cure disorders, caused by uncontrolled growth of malignant stem cells.

Surface and epidural lumbosacral spinal cord evoked potentials in chronic spinal cord injury

Nine patients were examined in the chronic stage of spinal cord injury (12 to 56 months postinjury). Surface lumbosacral spinal cord evoked potentials (LSEPs) were obtained using electrodes placed over the S1, L2, L4, and T12 vertebral levels, referenced to a T6 surface electrode. Epidural LSEPs were obtained using a multielectrode lead placed percutaneously into the epidural space for evaluation of the efficacy of spinal cord stimulation for modification of pain and spasticity. The LSEPs resulting from supramaximal stimulation of the tibial nerve at the popliteal fossa were composed of propagating and stationary action potential components. Based on the surface LSEP amplitudes and latencies established in healthy subjects, the data was divided into normal (less than 2 SD), marginal (between 2 and 2.5 SD), and abnormal (greater than 2.5 SD) categories. Comparison of surface and epidural LSEPs at the T12 vertebral level for the normal group (n = 6, 4 incomplete and 2 complete) revealed a mean epidural/surface amplitude ratio of 9.44 and a latency for the major negative component of 15.2 +/- 0.6 ms for the epidural versus 14.8 +/- 0.6 ms for the surface LSEP. In cases where the lead was progressively removed and LSEPs recorded (n = 4) the propagating components rapidly attenuated and increased in duration while the stationary components attenuated but did not change in duration. The LSEPs for the marginal group (n = 2, 1 incomplete and 1 complete) showed similar epidural/surface amplitude ratios. In the abnormal case (n = 1, complete) surface LSEPs were absent but epidural LSEPs were present but with stationary and propagating components of low amplitude. This study demonstrates the ability of the epidural LSEP to provide more information than the surface LSEP of the functional condition of the lumbosacral spinal cord, particularly regarding the character of the propagating action potentials and in cases when the surface LSEPs appear to be of very low amplitude or absent.