Neural stimulators: a guide to imaging and postoperative appearances.

Implantable neural stimulators have been developed to aid patients with debilitating neurological conditions that are not amenable to other therapies. The aim of this article is to improve understanding of correct anatomical placement as well as the relevant imaging methods used to assess these devices. Potential complications following their insertion and an overview of the current indications and potential mechanism of action of these devices is provided.

Maintenance percutaneous posterior nerve stimulation for refractory lower urinary tract symptoms in patients with multiple sclerosis: an open label, multicenter, prospective study.

PURPOSE: Percutaneous tibial nerve stimulation is an effective second line therapy for lower urinary tract symptoms. Data on percutaneous tibial nerve stimulation maintenance treatment are scarce. In this study we evaluate its effectiveness and propose an algorithm of percutaneous tibial nerve stimulation maintenance treatment in patients with multiple sclerosis. MATERIALS AND METHODS: In this prospective, multicenter, open label trial consecutive patients with multiple sclerosis and lower urinary tract symptoms unresponsive to medical therapy were treated with 12 weekly sessions of percutaneous tibial nerve stimulation. Responder patients (50% or greater improvement of lower urinary tract symptoms as measured by the patient perception of bladder condition questionnaire) entered a maintenance phase with individualized treatment frequency based on patient response. Lower urinary tract symptoms were assessed using a 3-day frequency volume chart, urodynamics and patient perception of bladder condition questionnaire. Treatment satisfaction was evaluated using a global response assessment scale and a treatment satisfaction visual analog scale. RESULTS: A total of 83 patients were included in the study and 74 (89%) responded to initial treatment. Persistent efficacy occurred in all initial responders after a mean treatment of 24 months. The greatest frequency of maintenance percutaneous tibial nerve stimulation was every 2 weeks. Lower urinary tract symptoms and patient treatment satisfaction improved with time compared to initial treatment (p <0.05). Bladder diary parameters and voiding parameters improved compared to baseline (p <0.05). CONCLUSIONS: Prolonged percutaneous tibial nerve stimulation treatment leads to a persistent improvement of lower urinary tract symptoms in patients with multiple sclerosis.

The treatment of lower urinary tract symptoms in patients with multiple sclerosis: a systematic review.

This is a systematic review on the treatment of lower urinary tract symptoms (LUTS) in patients with multiple sclerosis (MS). The heterogeneity of the outcome criteria did not allow a meta-analysis of the published evidence. In the last few decades, the therapeutic options for neurogenic bladder dysfunction have broadened. Despite this, no consensus has been reached as to the management of LUTD and LUTS in patients with MS, and the subject remains controversial. Bladder dysfunction is common in MS, affecting 80 %-100 % of patients during the course of the disease. Several studies have shown that urinary incontinence has a severe effect on patients' quality of life, with 70 % of patients classifying the impact bladder symptoms had on their life as "high" or "moderate." Moreover, the progressive feature of MS makes its treatment complex, since any achieved therapeutic result may be short-lived, with the possibility that symptoms will recur or develop de novo.

Transplanted human neural precursor cells migrate widely but show no lesion-specific tropism in the 6-hydroxydopamine rat model of Parkinson's disease.

Parkinson's disease (PD), while primarily associated with degeneration of nigrostriatal dopamine neurons, is now increasingly recognized to have more widespread cell loss and so the most effective cell replacement therapy should target all these neuronal losses. Neural precursor cells might be ideal in this regard as in certain circumstances they have been shown to migrate widely following transplantation into the CNS. The aim of this study was to investigate whether transplanted human expanded neural precursor cells (hENPs) could migrate to sites of established or evolving pathology in the adult brain using the 6-hydroxydopamine (6-OHDA) rat model of PD. hENPs were grafted into the striatum prior to, at the same time as, or after the animals received a 6-OHDA lesion to the medial forebrain bundle. The presence of donor cells was then assessed in a distant site of cell loss (substantia nigra) or sites where cell death would not be expected (frontal cortex and globus pallidus). Donor cells were found distant from the site of implantation but the migration of these hENPs was not significantly greater in the 6-OHDA-lesioned brain and the cells did not specifically target the site of cell loss in the substantia nigra. The temporal relationship of grafting relative to the lesion, and therefore dopaminergic cell death, did not affect the migration of hENPs nor their differentiation. We conclude that while transplanted hENPs are capable of migration away from the site of implantation, they show no specific tropism for sites of ongoing or established nigral dopaminergic cell loss in this lesion model. Therefore, the use of such cells to replace the range of neurons lost in PD is likely to require a deeper understanding of the migratory cues in the damaged adult brain and some manipulation of these cells prior to transplantation.

P2X and P2X receptor expression in human bladder urothelium and changes in interstitial cystitis.

OBJECTIVE: To investigate whether the expression of P2X(3) receptors (implicated in the pathophysiology of pain) is altered in human bladder urothelium from patients with interstitial cystitis (IC, a major symptom of which is pain), and as P2X(2) receptors can be co-expressed with P2X(3) receptors, to assess their expression also. PATIENTS AND METHODS: Bladder tissue samples were collected from patients undergoing cystectomy or radical prostatectomy. Patients with IC were diagnosed using the international criteria. RNA protein expression levels of both receptors were evaluated using reverse transcription-polymerase chain reaction (PCR), real-time quantitative PCR and Western blot analysis. RESULTS: P2X(2) was expressed in the human urothelium, in a glycosylated form. There was less gene expression of P2X(3) in IC urothelium, whereas P2X(2) gene expression was unchanged. This contrasted with the protein expression, which was increased for both P2X(2) and P2X(3). CONCLUSION: This is the first report of the expression of the P2X(2) receptor in human bladder urothelium. There was greater protein expression of both P2X(2) and P2X(3) in IC bladder urothelium which did not directly correlate with the gene expression. Changes in expression of P2X(2) and P2X(3) receptors may contribute to the pain that patients with IC have, and might provide novel drug targets.

Staging and preparation of human fetal striatal tissue for neural transplantation in Huntington's disease.

Transplantation of human fetal central nervous system tissue has been shown to be of benefit in Parkinson's disease, and is currently being explored as a therapeutic option in Huntington's disease. The success of a neural transplant is dependent on a number of factors, including the requirement that donor cells are harvested within a given developmental window and that the cell preparation protocols take account of the biological parameters identified in animal models. Although many of the criteria necessary for a successful neural transplant have been defined in animal models, ultimately they must be validated in human studies, and some issues can only ever be addressed in human studies. Furthermore, because neural transplantation of human fetal tissue is limited to small numbers of patients in any one surgical center, largely due to practical constraints, it is crucial that tissue preparation protocols are clearly defined and reproducible, so that (i) multicenter trials are possible and are based on consistent tissue preparation parameters, and (ii) results between centers can be meaningfully analyzed. Here we describe the preparation of human fetal striatum for neural transplantation in Huntington's disease, and report on the validation of a method for estimating the developmental stage of the fetus based on direct morphometric measurements of the embryonic tissue.

Normal conduction of surface action potentials in detubulated amphibian skeletal muscle fibres.

1. The influence of the transverse (T) tubules on surface action potential conduction was investigated by comparing electrophysiological and confocal microscopic assessments of tubular changes in osmotically shocked and control fibres from frog sartorius muscle. 2. The membrane-impermeant fluorescent dye, di-8-ANEPPs spread readily from the bathing extracellular solution into the tubular membranes in control, intact fibres. Prior exposure of muscles to a hypertonic glycerol-Ringer solution, its replacement by an isotonic Ca(2+)-Mg(2+) Ringer solution and cooling sharply reduced such access. In contrast, dye application in the course of this osmotic shock procedure stained the large tubular vacuoles hitherto associated with successful muscle detubulation. 3. Conduction velocities in intact, control fibres (1.91 +/- 0.048 m s(-1), mean +/- S.E.M., n = 32 fibres) agreed with earlier values reported at room temperature (18-21 degrees C) and were unaffected by prior episodes of steady cooling to 8-10 degrees C (1.91 +/- 0.043 m s(-1), n = 30). 4. Cooling to 11.5 degrees C reduced these velocities (1.47 +/- 0.081 m s(-1), n = 25) but action potential waveforms still included early overshoots and the delayed after-depolarizations associated with tubular electrical activity. 5. In contrast, action potentials from cooled, superficial fibres in osmotically shocked muscles lacked after-depolarization phases implying tubular detachment. Their mean conduction velocities (1.62 +/- 0.169 m s(-1), n = 25) were not significantly altered from values obtained in untreated controls or in intact fibres in muscle similarly treated with glycerol, in direct contrast to earlier results. 6. Cooling produced similar reductions in maximum rates of voltage change dV/dt in action potentials from all fibre groups with lower rates of change shown by detubulated fibres. 7. Use of an antibody to a conserved epitope of the alpha-subunit of voltage-gated sodium channels suggested a concentration of sodium channels close to the mouths of the T tubules. 8. These electrophysiological and anatomical findings are consistent with a partial independence of electrical events in the transverse tubules from those responsible for the rapid conduction of surface regenerative activity. 9. The findings are discussed in terms of a partial separation of the electrical activity propagated over the surface membrane, from the initiation of propagated activity within the T tubules, by the triggering of the sodium channels clustered selectively around the mouths of the T tubules.

Distribution of P2X(1) and P2X(3) receptors in the rat and human urinary bladder.

Adenosine 5'-triphosphate (ATP) is known to play a significant role as a neurotransmitter in smooth muscle. There is evidence to show that ATP can cause bladder contractions and may also be involved in the processing of sensory information in the urinary bladder. These effects are likely to be mediated by P2X receptors, namely P2X(1) and P2X(3), respectively. This study set out to investigate their distribution in rat and human urinary bladders. P2X(1) receptor immunoreactivity was found on detrusor muscle fibres and P2X(3) receptor immunoreactivity was found in the urothelium of both species. This is the first demonstration of a non-neuronal localisation for P2X(3) receptors. No clear evidence was found for the presence of P2X(3) receptors on calcitonin gene-related peptide-containing sensory nerves and therefore P2X(3) receptors may not have a direct role in the mediation of sensory responses to ATP in the urinary bladder.

Comparison of connexin 43, 40 and 45 expression patterns in the developing human and mouse hearts.

The mouse is currently widely used as a model organism in the analysis of gene function but how developmentally regulated patterns of connexin gene expression in the mouse compare with those in the human is unclear. Here we compare the patterns of connexin expression in the heart during the development of the mouse (from embryonic day 12.5 to 6 weeks postpartum) and the human (at 9 weeks gestation and adult stage). The extent of connexin43 expression in the ventricles progressively increased during development of the mouse heart. The developmental pattern of expression for connexins 40 and 45 in the mouse heart was similar, but not identical, and in the ventricles showed a progressive and preferential expression in the conduction system. In general, these dynamic changes of connexins 43, 40 and 45 during mouse cardiac development appear to be mirrored in the human.

Activation of epithelial Na(+) channel activity in the rabbit urinary bladder by cAMP.

The rabbit urinary bladder actively absorbs Na(+) from the urine. The rate-limiting step in this process is the diffusion of Na(+) across the apical membrane of bladder epithelial cells, mediated by amiloride-sensitive epithelial Na(+) channels. We have investigated the effects of cAMP on epithelial Na(+) channel activity in the rabbit bladder by measuring the amiloride-sensitive short-circuit current across bladders mounted in Ussing chambers. Three agents that raise intracellular cAMP levels (forskolin, dibutyryl-cAMP and 3-isobutyl-1-methylxanthine (IBMX)) increased the amiloride-sensitive short-circuit current relative to control preparations. The forskolin-induced increase in amiloride-sensitive short-circuit current was significantly inhibited by the vesicle fusion inhibitor brefeldin A and the protein synthesis inhibitor cycloheximide. These findings, together with the magnitude and protracted time course of the cAMP effects, suggests that cAMP stimulates the insertion of new Na(+) channels into the apical membrane of the rabbit bladder epithelium.