Deciphering an AgRP-serotoninergic neural circuit in distinct control of energy metabolism from feeding.

Contrasting to the established role of the hypothalamic agouti-related protein (AgRP) neurons in feeding regulation, the neural circuit and signaling mechanisms by which they control energy expenditure remains unclear. Here, we report that energy expenditure is regulated by a subgroup of AgRP neurons that send non-collateral projections to neurons within the dorsal lateral part of dorsal raphe nucleus (dlDRN) expressing the melanocortin 4 receptor (MC4R), which in turn innervate nearby serotonergic (5-HT) neurons. Genetic manipulations reveal a bi-directional control of energy expenditure by this circuit without affecting food intake. Fiber photometry and electrophysiological results indicate that the thermo-sensing MC4RdlDRN neurons integrate pre-synaptic AgRP signaling, thereby modulating the post-synaptic serotonergic pathway. Specifically, the MC4RdlDRN signaling elicits profound, bi-directional, regulation of body weight mainly through sympathetic outflow that reprograms mitochondrial bioenergetics within brown and beige fat while feeding remains intact. Together, we suggest that this AgRP neural circuit plays a unique role in persistent control of energy expenditure and body weight, hinting next-generation therapeutic approaches for obesity and metabolic disorders.

Abnormal Neuronal Response to Rectal and Anal Stimuli in Patients Treated for Distal Rectal Cancer With High-Dose Chemoradiotherapy Followed By Watchful Waiting.

BACKGROUND: Watchful waiting in patients with rectal cancer with complete clinical response after chemoradiation therapy has gained increased popularity to avoid morbidity and mortality associated with surgery. Irradiation of the pelvis causes bowel dysfunction, but the effect on anorectal sensory function remains obscure in this patient category. OBJECTIVE: The aim of this study was to characterize the sensory pathways of the gut-brain axis in patients with rectal cancer treated solely with chemoradiation therapy (nonconventional regime/dose) compared with healthy volunteers. DESIGN: This is an explorative study. SETTINGS: Sensory evaluation by rectal distension was performed and cortical evoked potentials were recorded during rapid balloon distensions of the rectum and anal canal. Latencies and amplitudes of cortical evoked potentials were compared, and the relative amplitude of 5 spectral bands from recorded cortical evoked potentials was used as an additional proxy of neuronal processing. PATIENTS: Patients with rectal cancer solely with chemoradiation therapy (n = 13) a median of 3.2 years ago (range, 2.3-5.6 y) and healthy volunteers (n = 13) were included. MAIN OUTCOME MEASURES: Cortical evoked potentials were measured. RESULTS: Patients had 35% lower rectal capacity at a maximum tolerable volume (p = 0.007). We found no differences in rectal cortical evoked potential latencies (p = 0.09) and amplitudes (p = 0.38) between groups. However, spectral analysis of rectal cortical evoked potentials showed a decrease in θ (4-8 Hz) and an increase in ß (12-32 Hz) band activity in patients (all p < 0.001). Anal cortical potentials showed an increase in α (8-12 Hz) and ß and a decrease in γ (32-70 Hz) band activity (all p < 0.001) in patients compared with healthy volunteers. LIMITATIONS: This is an explorative study of limited size. CONCLUSIONS: Chemoradiation therapy for distal rectal cancer causes abnormal cortical processing of both anal and rectal sensory input. Such central changes may play a role in symptomatic patients, especially when refractory to local treatments. See Video Abstract at http://links.lww.com/DCR/B270. RESPUESTA NEURONAL ANORMAL A ESTÍMULOS RECTALES Y ANALES, EN PACIENTES TRATADOS POR CÁNCER RECTAL DISTAL, CON QUIMIORRADIOTERAPIA DE DOSIS ALTA, SEGUIDA DE ESPERA VIGILANTE: La espera vigilante en pacientes de cáncer rectal, con respuesta clínica completa después de la quimiorradiación, ha ganado una mayor popularidad en evitar la morbilidad y mortalidad asociadas con la cirugía. La irradiación de la pelvis causa disfunción intestinal, pero el efecto sobre la función sensorial ano-rectal sigue siendo no claro, en esta categoría de pacientes.El objetivo de este estudio, fue caracterizar las vías sensoriales del eje intestino-cerebro en pacientes con cáncer rectal, tratados únicamente con quimiorradiación (régimen / dosis no convencional), en comparación con voluntarios sanos.Es un estudio exploratorio.Se realizó una evaluación sensorial por distensión rectal y se registraron los potenciales evocados corticales, durante las distensiones rápidas con balón en recto y canal anal. Se compararon las latencias y amplitudes de los potenciales evocados corticales, y la amplitud relativa de cinco bandas espectrales registradas, de potenciales evocados corticales, se usaron como proxy adicional del procesamiento neuronal.Pacientes de cáncer rectal, únicamente con terapia de quimiorradiación (n = 13) mediana de 3.2 años (rango 2.3-5.6) y voluntarios sanos (n = 13).Potenciales evocados corticales.Pacientes tuvieron una capacidad rectal menor del 35%, al volumen máximo tolerable (p = 0.007). No encontramos diferencias en las latencias potenciales evocadas corticales rectales (p = 0.09) y amplitudes (p = 0.38) entre los grupos. Sin embargo, el análisis espectral de los potenciales evocados corticales rectales, mostró una disminución en theta (4-8 Hz) aumento en beta (12-32 Hz), y actividad en banda en pacientes (todos p <0.001). Los potenciales evocados corticales anales mostraron un aumento en alfa (8-12 Hz) y beta, disminución en gamma (32-70 Hz), y actividad en banda (todos p <0.001), en pacientes comparados a voluntarios sanos.Este es un estudio exploratorio de tamaño limitado.La quimiorradiación para el cáncer rectal distal, ocasiona procesos corticales sensoriales anormales anales y rectales. Tales cambios centrales pueden desempeñar un papel en pacientes sintomáticos, especialmente cuando son refractarios a tratamientos locales. Consulte Video Resumen en http://links.lww.com/DCR/B270.

Dose-dependent effect of the pulsed Nd:YAG laser in the treatment of crushed sciatic nerve in Wister rats: an experimental model.

The objective of the study was to investigate the efficacy of three energy densities 4, 10, and 50 J/cm2 of pulsed Nd:YAG laser for the treatment of crushed sciatic nerve in Wister rats by evaluating changes in the sciatic functional index and the electrophysiology.A total of 180 Wistar rats were involved in the study. Rats were randomly assigned to five groups. Rats were subjected to the sciatic nerve crushing. Control negative (CONT-ve), which received no crushing; control positive (CONT+ve), which received crushing with no laser; and HILT-4, HILT-10, and HILT-50 groups, which received pulsed Nd:YAG laser (10 Hz, 360 mJ/cm2) with energy densities 4, 10, and 50 J/cm2, respectively. The SFI, the amilitude of compound motor action potential (CMAP) and sciatic motor nerve conduction velocity (MNCV) were measured before and after seven, 14, and 21 days after crushing. For the SFI and electrophysiological analysis, repeated measures ANOVA is used, followed by Bonferroni's repeated-measures test. Statistical significance was set at p < 0.05. After one week, there was no significant difference in SFI, CMAP, and MNCV among the three laser groups with significant changes between them and CONT-ve and CONT+ve groups. There was a significant increase in either CMAP amplitude or MNCV after 14 days with significant decrease in the SFI after 21 days among all treatment groups. The pulsed Nd:YAG laser applied with energy densities 4, 10, and 50 J/cm2 significantly decreased the SFI and increased the CMAP and MNCV of the crushed sciatic nerve in Wister rats. Among laser doses, the difference in the rate of recovery in the electrophysiology was found after two weeks while in the SFI after three weeks. The improvement after the nerve injury was time and dose dependent.

Are there optical communication channels in the brain?

Despite great progress in neuroscience, there are still fundamental unanswered questions about the brain, including the origin of subjective experience and consciousness. Some answers might rely on new physical mechanisms. Given that biophotons have been discovered in the brain, it is interesting to explore if neurons use photonic communication in addition to the well-studied electro-chemical signals. Such photonic communication in the brain would require waveguides. Here we review recent work (S. Kumar, K. Boone, J. Tuszynski, P. Barclay, and C. Simon, Scientific Reports 6, 36508 (2016)) suggesting that myelinated axons could serve as photonic waveguides. The light transmission in the myelinated axon was modeled, taking into account its realistic imperfections, and experiments were proposed both in vivo and in vitro to test this hypothesis. Potential implications for quantum biology are discussed.

Skin thermophysiological effects of 448 kHz capacitive resistive monopolar radiofrequency in healthy adults: A randomised crossover study and comparison with pulsed shortwave therapy.

Radiofrequency-based electrophysical agents (EPA) have been used in therapy practice over several decades (e.g., shortwave therapies). Currently, there is insufficient evidence supporting such devices operating below shortwave frequencies. This laboratory-based study investigated the skin physiological effects of 448 kHz capacitive resistive monopolar radiofrequency (CRMRF) and compared them to pulsed shortwave therapy (PSWT). In a randomised crossover study, seventeen healthy volunteers received four treatment conditions - High, Low and Placebo dose conditions receiving 15-min CRMRF treatment and a Control condition receiving no intervention. Fifteen participants also received high dose PSWT for comparison. Treatment was applied to the right lower medial thigh. Pre, post and 20-min follow-up measurements of skin temperature (SKT), skin blood flow (SBF) and nerve conduction velocity (NCV) were obtained using Biopac MP150 system. Group data were compared using the ANOVA model. Statistical significance was set at p ≤ 0.05 (0.8P, 95%CI). Significant increase and sustenance of SKT with both high and low dose CRMRF was demonstrated over the other groups (p < 0.001). PSWT increased SKT significantly (p < 0.001) but failed to sustain it over the follow-up. However, among the five conditions, only high dose CRMRF significantly increased and sustained SBF (p < 0.001). Overall, the CRMRF physiological responses were significantly more pronounced than that of PSWT. No significant changes in NCV were noted for any condition. Physiological changes associated with CRMRF were more pronounced when compared to PSWT, placebo or control. Any potential stronger therapeutic benefits of CRMRF need to be confirmed by comparative clinical studies.

Red LED photobiomodulation reduces pain hypersensitivity and improves sensorimotor function following mild T10 hemicontusion spinal cord injury.

BACKGROUND: The development of hypersensitivity following spinal cord injury can result in incurable persistent neuropathic pain. Our objective was to examine the effect of red light therapy on the development of hypersensitivity and sensorimotor function, as well as on microglia/macrophage subpopulations following spinal cord injury. METHODS: Wistar rats were treated (or sham treated) daily for 30 min with an LED red (670 nm) light source (35 mW/cm(2)), transcutaneously applied to the dorsal surface, following a mild T10 hemicontusion injury (or sham injury). The development of hypersensitivity was assessed and sensorimotor function established using locomotor recovery and electrophysiology of dorsal column pathways. Immunohistochemistry and TUNEL were performed to examine cellular changes in the spinal cord. RESULTS: We demonstrate that red light penetrates through the entire rat spinal cord and significantly reduces signs of hypersensitivity following a mild T10 hemicontusion spinal cord injury. This is accompanied with improved dorsal column pathway functional integrity and locomotor recovery. The functional improvements were preceded by a significant reduction of dying (TUNEL(+)) cells and activated microglia/macrophages (ED1(+)) in the spinal cord. The remaining activated microglia/macrophages were predominantly of the anti-inflammatory/wound-healing subpopulation (Arginase1(+)ED1(+)) which were expressed early, and up to sevenfold greater than that found in sham-treated animals. CONCLUSIONS: These findings demonstrate that a simple yet inexpensive treatment regime of red light reduces the development of hypersensitivity along with sensorimotor improvements following spinal cord injury and may therefore offer new hope for a currently treatment-resistant pain condition.

New treatment alternatives in the ulnar neuropathy at the elbow: ultrasound and low-level laser therapy.

Ulnar nerve entrapment at the elbow (UNE) is the second most common entrapment neuropathy of the arm. Conservative treatment is the treatment of choice in mild to moderate cases. Elbow splints and avoiding flexion of the involved elbow constitute majority of the conservative treatment; indeed, there is no other non-invasive treatment modality. The aim of this study was to investigate the efficacy of ultrasound (US) and low-level laser therapy (LLLT) in the treatment of UNE to provide an alternative conservative treatment method. A randomized single-blind study was carried out in 32 patients diagnosed with UNE. Short-segment conduction study (SSCS) was performed for the localization of the entrapment site. Patients were randomized into US treatment (frequency of 1 MHz, intensity of 1.5 W/cm(2), continuous mode) and LLLT (0.8 J/cm(2) with 905 nm wavelength), both applied five times a week for 2 weeks. Assessments were performed at baseline, at the end of the treatment, and at the first and third months by visual analog scale, hand grip strength, semmes weinstein monofilament test, latency change at SSCS, and patient satisfaction scale. Both treatment groups had significant improvements on clinical and electrophysiological parameters (p < 0.05) at first month with no statistically significant difference between them. Improvements in all parameters were sustained at the third month for the US group, while only changes in grip strength and latency were significant for the LLLT group at third month. The present study demonstrated that both US and LLLT provided improvements in clinical and electrophysiological parameters and have a satisfying short-term effectiveness in the treatment of UNE.

Effects of early and delayed laser application on nerve regeneration.

The aim of this study is to analyze the differences between early and delayed use of low-level laser therapy (LLLT) in functional and morphological recovery of the peripheral nerve. Thirty male Wistar rats were divided into three groups after the sciatic nerve was crushed: (1) control group without laser treatment, (2) early group with laser treatment started immediately after surgery and lasted 14 days, and (3) delayed group with laser treatment starting on the postoperative day 7 and lasted until day 21. A 650-nm diode laser (model: DH650-24-3(5), Huanic, China) with an output power of 25 mW exposed transcutaneously at three equidistant points on the surgical mark corresponding to the crushed nerve. The length of the laser application was calculated as 57 s to satisfy approximately 10 J/cm(2). A Sciatic Functional Index (SFI) was used to evaluate functional improvement in groups at pre- and post-surgery (on days 7, 14, and 21). Compound action potential (CAP) was measured after the sacrifice and histological examination was performed for all groups. SFI results showed that there was no significant difference between groups at different days (p > 0.05). On the other hand, the latency of CAP decreased significantly (p < 0.05) in the delayed group. Histological examination confirmed that the number of mononuclear cells was lower (p < 0.05) in both early and delayed groups. In conclusion, results supported the hypothesis that LLLT could accelerate the rate of recovery of injured peripheral nerves in this animal model. Though both laser groups had positive outcomes, delayed group showed better recovery.

Evolución de la conducción nerviosa y discapacidad en niños con sindrome de guillain-barré, Honduras, 2012-2013 / Evolution of nerve conduction and disability in children with Guillain-Barré Syndrome, Honduras, 2012-2013

Antecedentes: El Síndrome Guillain-Barré conjunto de trastornos de tipo polirradículoneuropatía, cursa con parálisis flácida aguda ascendente más arreflexia. El 40% de niños pierde la marcha durante la enfermedad y 15% requiere ventilación mecánica. La mayoría logra recuperación total o parcial en semanas o meses. Objetivo: Describir la evolución electrofisiológica y de discapacidad en pacientes <15 años con SGB atendidos en Hospital General San Felipe (HGSF) e Instituto Hondureño de Seguridad Social (IHSS),Tegucigalpa, periodo Junio 2012-Septiembre 2013. Metodología: Estudio descriptivo longitudinal de la neuroconducción y el grado de discapacidad inicial según CIF (Clasificación Internacional del Funcionamiento, Discapacidad y Salud, OMS), en dos evaluaciones. Se realizó seguimiento hasta aproximadamente 8 meses. Pacientes captados en sala de rehabilitación pediátrica de HGSF e IHSS y casos documentados en el Programa Ampliado de Inmunizaciones, Secretaría de Salud. Se utilizó ficha de recolección de datos. Se obtuvo consentimiento y asentimiento informado escrito. Resultados: Se evaluaron 12 casos, 75% (9) captado en HGSF y 25% (3) en Programa Ampliado de Inmunizaciones. El seguimiento se realizó 58% (7) en HGSF y 42% (5) en IHSS. El tiempo promedio entre evaluaciones fue 34 semanas (17-43 semanas). La recuperación de discapacidad no guardó relación con la evolución electrofisiológica en tiempo o grado de afectación nerviosa inicial y fue completa en 58% (7) de casos. Solo 33% (4) de casos demostró completa recuperación nerviosa. Discusión: El seguimiento de este grupo de casos con síndrome Guillain-Barré evidenció buen pronóstico funcional que no parece estar estrictamente ligado al daño nervioso...

The effect of ultrasound on the expression of CNTF gene, a possible cause of ultrasound influence on the rate of injured peripheral nerve regeneration.

In this article we evaluate the effects of ultrasound radiation and its causes on the rate of injured peripheral nerve regeneration by crushing the sciatic nerve of rats with hemostatic forceps. The rats were divided into three test and one control groups. The test groups were radiated using three different types of ultrasound parameters while the control group just received sham expose. The amount of nerve regeneration was measured via functional test by extracting sciatic functional index from rats paw prints. The results showed that one of the test group parameters had the best functional results compared to other groups. Obtaining this outcome, the investigations continued by 50 rats with crushed sciatic nerve. These rats again divided into two test and control groups while for the test group the best parameters were assigned. In different time intervals compound muscle action potential wave was recorded from five rats of each group. Then their sciatic nerves were extracted to measure the amount of ciliary neurotropic factor gene expression by real time polymerase chain reaction. Crush injury sets the sciatic functional index to about -90 and compound muscle action potential to 6.8 mV in both control and test groups. After the period of treatment with ultrasound, the sciatic functional index reached the value of -25 in control group and -10 in test group and compound muscle action potential value reached 11 in control and 18 in test group. The results of electrophysiological tests confirmed the results of functional tests. At the end of the second, third and fourth weeks, the outcomes of real time polymerase chain reaction showed that the expression of ciliary neurotropic factor gene in test group was higher than control group as well as the amount in test group was approximately 11, 2 and 6 times higher than test group in corresponding weeks. Hence we can conclude that increase in the expression of ciliary neurotropic factor gene, as a nerve growth factor, following ultrasound radiation, can be considered as the reason of the effect of ultrasound on the rate of injured nerve regeneration.

Preliminary study of sural nerve morphological changes in uremic hemodialysis patients using 22-MHz high-frequency ultrasound.

INTRODUCTION: The aim of this study was to evaluate the ultrasound (US) morphological changes of sural nerves (SNs) of uremic patients on hemodialysis. METHODS: Sixty-six SNs in 33 uremic patients were examined by 22-MHZ high-frequency US and routine nerve conduction studies (NCS), and 76 SNs in 38 controls were also examined. Cross-sectional area (CSA) and maximal fascicular thickness (MFT) of the SNs were measured. RESULTS: The inner parts of the SN were clearly identified in all participants. There were significant increases in CSA and MFT in the patient group (1.86 ± 0.53 mm(2) and 0.37 ± 0.08 mm, respectively) compared with the control group (1.38 ± 0.25 mm(2) and 0.32 ± 0.03 mm, respectively) (P < 0.001). Fifty-seven SNs (86.36%) had abnormal CSAs, and 51 SNs (77.27%) had abnormal MFTs in the patient group, which was higher than NCS abnormalities (66.67%). CONCLUSIONS: A 22-MHZ US can show morphological changes in the SNs of uremic patients and may be a valuable tool.

Electrophysiological effects of single point transcutaneous 650 and 808 nm laser irradiation of rat sciatic nerve: a study of relevance for low-level laser therapy and laser acupuncture.

OBJECTIVE: The purpose of this study was to evaluate effects of transcutaneous 650 and 808 nm laser irradiation (LI) to a single point overlying rat sciatic nerve; a comparison to four point LI and relevance to the clinical application of low-level laser therapy (LLLT) and laser acupuncture (LA). BACKGROUND DATA: Transcutaneous LI inhibits somatosensory and motor conduction when delivered to four points overlying sciatic nerve; however, effects of the same total energy delivered to a single point over the nerve, equating to laser acupuncture, are undefined. METHODS: Transcutaneous 808 nm, 450 mW, (13.5 or 54 J) continuous wave (cw) mode or 650 nm, 35 mW, (1.1 or 4.4 J), cw LI or sham LI, was applied for 30 or 120 sec to a single point overlying the midpoint of rat sciatic nerve. Somatosensory evoked potentials (SSEPs) and compound muscle action potentials (CMAPs) were then recorded after 10 and 20 min, and after 24 and 48 h. RESULTS: 120 sec of 808 nm LI increased SSEP amplitudes only at 10 min, with no effect of 30 or 120 sec at other time points on SSEPs or on CMAPs. LI 650 nm for 30 or 120 sec did not alter SSEPs or CMAPs at any time point. CONCLUSIONS: Localized transcutaneous 808 LI to a single point overlying sciatic nerve increases SSEP amplitudes when compared with delivery of the same total energy to four points, which causes decreased SSEP amplitudes and conduction block. Therefore, the area and duration of delivery are important, independent variables with implications for clinical delivery of both LLLT and LA.

Mechanical bioeffects of pulsed high intensity focused ultrasound on a simple neural model.

PURPOSE: To study how pressure pulses affect nerves through mechanisms that are neither thermal nor cavitational, and investigate how the effects are related to cumulative radiation-force impulse (CRFI). Applications include traumatic brain injury and acoustic neuromodulation. METHODS: A simple neural model consisting of the giant axon of a live earthworm was exposed to trains of pressure pulses produced by an 825 kHz focused ultrasound transducer. The peak negative pressure of the pulses and duty cycle of the pulse train were controlled so that neither cavitation nor significant temperature rise occurred. The amplitude and conduction velocity of action-potentials triggered in the worm were measured as the magnitude of the pulses and number of pulses in the pulse trains were varied. RESULTS: The functionality of the axons decreased when sufficient pulse energy was applied. The level of CRFI at which the observed effects occur is consistent with the lower levels of injury observed in this study relative to blast tubes. The relevant CRFI values are also comparable to CRFI values in other studies showing measureable changes in action-potential amplitudes and velocities. Plotting the measured action-potential amplitudes and conduction velocities from different experiments with widely varying exposure regimens against the single parameter of CRFI yielded values that agreed within 21% in terms of amplitude and 5% in velocity. A predictive model based on the assumption that the temporal rate of decay of action-potential amplitude and velocity is linearly proportional the radiation force experienced by the axon predicted the experimental amplitudes and conduction velocities to within about 20% agreement. CONCLUSIONS: The functionality of axons decreased due to noncavitational mechanical effects. The radiation force, possibly by inducing changes in ion-channel permeability, appears to be a possible mechanism for explaining the observed degradation. The CRFI is also a promising parameter for quantifying neural bioeffects during exposure to pressure waves, and for predicting axon functionality.

The effects of low-dose radiation in the treatment of sciatic nerve injury in rats.

AIM: Peripheral nerve regeneration is often blocked by scar formation and misdirection of axon sprouts. The aim of this study is to evaluate electrophysiological and histopathological effects of low-dose radiation therapy on the prevention of intraneural scar formation in peripheral nerve injury. MATERIAL AND METHODS: In this experimental study, twenty rats were randomly divided into two groups. Left sciatic nerves were exposed and clipped by temporary aneurysm clip for 5 minutes in both groups. In all animals, electrophysiological recordings were performed between 22-24 hours after sciatic nerve injury. The control group was not given any treatment. In the experimental group, 700 cGy low-dose radiation was administered on the left sciatic nerves 24 hours after clipping. Six weeks after injury, electrophysiological recordings were performed in both groups and animals were sacrificed to evaluate the injured nerves histopathologically. RESULTS: We observed that low-dose radiotherapy increased the amplitude and improved latency measurements in electrophysiological examinations. Histopathologically, more axonal degeneration and vacuolization was observed in the control group comparing with the experimental group. Endoneural space increased slightly more in the control group than the experimental group. CONCLUSION: It was observed that low-dose radiotherapy may prevent intraneural scar formation and may improve electrophysiological recovery in sciatic nerve injury performed in rats.

Diabetic distal symmetric polyneuropathy: effect of low-intensity laser therapy.

Low-intensity laser therapy (LILT) has been considered as a treatment modality in diabetic distal symmetric polyneuropathy (DSP). The aim of this study is to determine the effectiveness of LILT on DSP. We examined 107 subjects with type 2 diabetes for detection of DSP using the Michigan Neuropathy Screening Instrument (MNSI). Seventeen subjects were eligible to be enrolled in the study. Nerve conduction studies (NCS) were performed in all eligible subjects as an objective method to confirm neuropathy. The participants received LILT three times a week for ten sessions. NCSs were reevaluated after completion of the treatment. The absolute changes in NCS parameters were considered to establish the effectiveness of the treatment. Baseline demographics were similar in all participants. The mean differences of NCV parameters were considered for comparison. At the end of the study, the subjects showed a significant increase in neural potential amplitudes (p < 0.05). This study clearly demonstrated a significant positive effect of LILT on improvement of nerve conduction velocity on diabetic distal symmetric polyneuropathy (DSP). This finding supports the therapeutic potential of LILT in DSP.

Upgraded nerve growth factor expression induced by low-intensity continuous-wave ultrasound accelerates regeneration of neurotometicly injured sciatic nerve in rats.

Low-intensity ultrasound (LIU) can stimulate injured nerve regeneration but the mechanism is still unclear. We investigated the stimulating effect and its mechanism of continuous-wave LIU on neurotometic injury of sciatic nerve. The right sciatic nerves of 64 adult Wistar rats were first crushed and then exposed (32 rats) or sham-exposed (32 rats) to LIU at the crush site. The LIU had a spatial averaged and temporal averaged intensity of 0.25 W/cm(2) operated at 1.0 MHz for 1 min every other day. At various stages (the second, fourth, sixth and eighth weeks) after LIU exposure, the sciatic nerve function index (SFI), the sensory nerve conduction velocity (SNCV), the expression of nerve growth factor (NGF) and sample histology were studied. It was found that the density of nerve fibers with myelin sheath, SFI, SNCV and NGF expression of the treatment group were higher than that of control group (p < 0.05). It has been determined that LIU treatment can accelerate the regeneration and functional recovery of neurotometic injured sciatic nerve at earlier stages after injury, the upgraded expression of NGF induced by LIU may be the primary mechanism of the acceleration effects.

[Rules of application and mode of action of transcranial direct current stimulation in neurorehabilitation: primary motor cortex]. / Zasady stosowania i mechanizm dzialania przezczaszkowej stymulacji pradem stalym w neurorehabilitacji: dane z badan kory ruchowej.

Transcranial direct current stimulation (tDCS) is an emerging technique of non-invasive brain stimulation that has been found useful in facilitating treatment of various neurological disorders, especially stroke. Currently available criteria for single application of several minutes-long stimulation at 1-2 mA have been considered safe. However, knowledge regarding safety parameters of repeated and long-term electrical stimulation is so far limited. Studies on the use of tDCS focus predominantly on the motor cortex. They demonstrate that weak direct current is capable of eliciting cortical excitability changes which occur during and after stimulation. The nature of these changes is specific for current polarity - anodal stimulation enhances excitability, and cathodal reduces it. Studies indicate that tDCS effects are generated by polarity-driven alterations of membrane potentials and efficacy modulations of specific neuronal receptors. According to interhemispheric competition models, possible mechanisms underlying functional improvements due to stimulation in patients with stroke are attributed to tDCS-induced modification of inappropriate interhemispheric inhibition.

Mechanisms of neuropathic pain in patients with Charcot-Marie-Tooth 1 A: a laser-evoked potential study.

Charcot-Marie-Tooth (CMT) disease is the most common inherited neuropathy. The CMT1A type can be considered the typical phenotype of this disease. Although pain is not considered a relevant symptom in CMT patients by physicians and no study assessed it comprehensively, this symptom is frequently complained by patients. The objective of the present study was to investigate the nociceptive system in a sample of CMT1A patients suffering from pain by laser-evoked potentials (LEPs). Moreover, we also used a pain specific questionnaire in order to obtain patient-oriented data about their painful symptoms, the Neuropathic Pain Diagnostic Questionnaire (DN4). We evaluated 16 patients affected by CMT1A and 14 controls. All subjects underwent a standard LEP recording session (foot, hand, and face stimulation) and filled in the DN4. While the N2/P2 amplitude to foot stimulation was lower in CMT patients than in controls (p=0.003), no difference in LEP amplitude to both hand and face stimulation was found between patients and healthy subjects (p>0.05). This result is probably due to a length-dependent Adelta-fiber loss which involves mostly the longer fibers coming from the lower limb. In our patients, there was a significant association between a reduced N2/P2 amplitude to foot stimulation and a high DN4 score (p=0.03), meaning that patients with highly probable neuropathic pain had also low N2/P2 amplitude values to painful foot stimulation. This suggests that in our CMT1A patients neuropathic pain is probably related to a reduction of the Adelta afferents.

Novel wavelengths for laser nerve stimulation.

BACKGROUND: Laser light is known to stimulate nerves. This study investigated alternative wavelengths for nerve stimulation. MATERIALS AND METHODS: The sciatic nerves of rats were irradiated with four different lasers-a Ho:YAG (2100 nm), a Yb:glass fiber laser (1495 nm) and diode lasers (1450 nm and 1540 nm). RESULTS: All lasers evoked a visible leg twitch response, and electromyography confirmed muscle activation. The Yb:glass laser at 1495 nm delivered through a single mode fiber was found to be the most effective stimulus. The stimulation threshold for a 2 millisecond pulse from the Yb:glass laser was determined to be 3.7+/-2.8 mJ/cm(2). CONCLUSIONS: The Yb:glass laser has the potential for use in neurostimulation, as an alternative to electrical stimulation.

Effects of low-power laser irradiation on the threshold of electrically induced paroxysmal discharge in rabbit hippocampus CA1.

In acute experiments using adult rabbits, we measured the paroxysmal discharge threshold (PADT) elicited by stimulation to the apical dendritic layer of the hippocampal CA1 region before and after low-power laser irradiation. Nd:YVO(4) laser irradiation (wavelength: 532 nm) was introduced into the same region as the stimulation site. The average PADT was 247 +/- 13 microA (n = 18) before laser irradiation, while after 5-min laser irradiation with 50, 75, and 100 mW, PADT was 333 +/- 40 (n = 4), 353 +/- 33 (n = 4) and 367 +/- 27 microA (n = 6), respectively. The latter two increments were statistically significant compared to the control (p < 0.05 and p < 0.01). After 10-min laser irradiation with 75 and 100 mW, PADT was 340 +/- 47 (n = 9) and 480 +/- 60 microA (n = 11; p < 0.01), respectively. Laser irradiation with a specific wavelength and average power offers the potential to suppress the generation of paroxysmal discharges in rabbit hippocampus CA1. Correlation analyses suggest that PADT increments are based on photochemical as well as photothermal effects of laser irradiation.