Randomized prospective crossover study of interstim lead wire placement with curved versus straight stylet.

AIMS: To assess whether InterStim lead wire placement with the curved stylet achieves motor response at lower amplitudes compared to straight stylet use. METHODS: This was a prospective, randomized, crossover study of patients scheduled for InterStim lead wire placement. All patients underwent lead wire testing with both the curved and straight stylets. Patients were randomized to determine stylet order, and then crossed-over to the alternate. Intra-operatively, the amplitude achieving motor response at each electrode was recorded. The stylet with lowest overall amplitudes was used for final placement. Primary outcome measure was amplitude requirement in the two deepest (0 and 1) electrodes. Secondary outcomes included amplitudes at the number 2 and 3 electrodes, combined amplitudes, stylet order, and adverse outcomes. RESULTS: Forty-two patients were enrolled, 40 of whom were included in the final analysis. Mean age was 69 years (SD = 12.8) and mean BMI 27 (SD = 5.6). Indications for placement included: urge urinary incontinence (N = 26), urge/frequency (N = 25), non-obstructive urinary retention (N = 5), and fecal incontinence (N = 10). There were no significant differences between randomized groups. Regardless of order, the curved stylet achieved a motor response at lower amplitudes in the deepest electrodes (P < 0.001). Combined amplitudes of all electrodes were also significantly lower with the curved stylet (P < 0.001). Subsequently, 88% underwent final "optimal" placement with curved stylet (N = 35). CONCLUSIONS: The curved stylet for InterStim lead wire placement consistently achieved motor response at lower amplitudes. A brief intra-operative exchange of stylets represents a minor procedural alteration that could maximize Implantable Pulse Generator battery life and facilitate programming.

In vivo recovery of the injured anal sphincter after repair and injection of myogenic stem cells: an experimental model.

OBJECTIVE: This study aims to evaluate in vivo function of the external anal sphincter after transection and repair augmented with myogenic stem cells, and to establish normative electromyography parameters of the rodent external anal sphincter. DESIGN AND SETTING: Thirty-three Sprague-Dawley rodents underwent baseline needle electromyography of the external anal sphincter. Motor unit action potentials were obtained and normative parameters established. Animals were randomly assigned to a myogenic stem cell group (n = 24) or control group (n = 9). All underwent proctoepisiotomy. The control group underwent layered repair with phosphate-buffered saline injection to the external anal sphincter. The treatment group underwent identical repair with injection of myogenic stem cells 5.0 × 10. Baseline anal pressure recordings were collected and repeated 2 weeks postintervention, and electromyography was repeated at 2 and 4 weeks. Groups were compared across 3 time points with the use of repeated measures ANOVA. MAIN OUTCOME MEASURES: The primary outcomes measured were the functional recovery of rat anal sphincters after stem cell transplantation as assessed by objective electromyography and anal pressure measures. RESULTS: A mean of 17 motor unit action potentials were sampled per animal. At 2 weeks postrepair, there was a significant difference between control and transplant groups with respect to amplitude, duration, turns, and phases (p < 0.01 for each). No significant electromyography differences were seen at 4 weeks. Resting and peak anal pressures declined significantly at 2 weeks postinjury in the control but not in the stem cell group. LIMITATIONS: Use of a murine animal population limited the subjective feedback and wider applicability. CONCLUSIONS: In vivo functional studies show recovery of anal sphincter pressures and electromyography to preinjury levels by day 14 in the myogenic stem cell group but not controls. At 4 weeks, all electromyography parameters returned to baseline irrespective of group. Restoration of function may be accelerated by the transplantation of myogenic stem cells and associated trophic factors.

Targeting the NMDA receptor subunit NR2B for treating or preventing age-related memory decline.

INTRODUCTION: Age-related memory loss is believed to be a result of reduced synaptic plasticity, including changes in the NR2 subunit composition of the NMDA receptor. It is known that endogenous NR2B subunits decrease as the brain ages, whereas transgenic upregulation of NR2B enhances synaptic plasticity and learning and memory in several animal species. Accumulating evidence suggests that elevated brain magnesium levels, via dietary supplementation, can boost NR2B in the brain, consequently reversing memory deficits and enhancing cognitive abilities. AREAS COVERED: This review highlights the convergent molecular mechanisms via the NR2B pathway as a useful strategy for treating age-related memory loss. A dietary approach, via oral intake of a novel compound, magnesium L-threonate (MgT), to boost NR2B expression in the brain is highlighted. EXPERT OPINION: Direct upregulation of the NR2B subunit expression can enhance synaptic plasticity and memory functions in a broad range of behavioral tasks in rodents. Other upregulation approaches, such as targeting the NR2B transporter or surface recycling pathway via cyclin-dependent kinase 5, are highly effective in improving memory functions. A dietary supplemental approach by optimally elevating the [Mg²âº] in the brain is surprisingly effective in upregulating NR2B expression and improving memories in preclinical studies. MgT is currently under clinical trials.

Safety assessment of myogenic stem cell transplantation and resulting tumor formation.

OBJECTIVES: To assess for stem cell migration to liver and lung after transplantation in injured rat anal sphincters. To evaluate histological findings of unanticipated ectopic foci of growth. METHODS: This is a prospective study involving 33 female virginal Sprague-Dawley rats. Anal sphincters were transected and repaired under sterile technique. Animals received injections of 5.0 × 10 myogenic stem cells (24 rats) or sham control (9 rats) and were killed on day 30. Liver and lung samples were obtained. Upon encountering abnormal foci of growth, further staining protocols were employed. Enzyme-linked immunosorbent assay studies evaluated stem cell media for in vitro growth factor secretion. RESULTS: No evidence of cell migration to liver or lung was found at the time of euthanasia in any study animal. Ectopic foci of growth were noted in 2 transplant rats. Further histological evaluations of these growths were consistent with benign tumors: no nuclear abnormalities and no evidence of proliferation at day 30. Enzyme-linked immunosorbent assay studies demonstrated positive secretion of vascular endothelial growth factor and insulin growth factor into the media of cultured rat myogenic stem cells. CONCLUSIONS: Whereas distant migration was not encountered in the liver or lung, 2 transplanted rats developed abnormal foci of growth, that is, tumors, from the external anal sphincter-raising further safety questions. Additional evaluation of these foci seemed benign. Possible explanations include cell trapping, stem cell overgrowth, and/or paracrine factors. The lack of cell migration supports that future investigation of safety parameters could focus locally.

genetic overexpression of NR2B subunit enhances social recognition memory for different strains and species.

The ability to learn and remember conspecifics is essential for the establishment and maintenance of social groups. Many animals, including humans, primates and rodents, depend on stable social relationships for survival. Social learning and social recognition have become emerging areas of interest for neuroscientists but are still not well understood. It has been established that several hormones play a role in the modulation of social recognition including estrogen, oxytocin and arginine vasopression. Relatively few studies have investigated how social recognition might be improved or enhanced. In this study, we investigate the role of the NMDA receptor in social recognition memory, specifically the consequences of altering the ratio of the NR2B:NR2A subunits in the forebrain regions in social behavior. We produced transgenic mice in which the NR2B subunit of the NMDA receptor was overexpressed postnatally in the excitatory neurons of the forebrain areas including the cortex, amygdala and hippocampus. We investigated the ability of both our transgenic animals and their wild-type littermate to learn and remember juvenile conspecifics using both 1-hr and 24-hr memory tests. Our experiments show that the wild-type animals and NR2B transgenic mice preformed similarly in the 1-hr test. However, transgenic mice showed better performances in 24-hr tests of recognizing animals of a different strain or animals of a different species. We conclude that NR2B overexpression in the forebrain enhances social recognition memory for different strains and animal species.