Efficacy assessment of novel methanimine derivatives in chronic constriction injury-induced neuropathic model: An in-vivo, ex-vivo and In-Silico approach.

The multicomponent etiology, complex clinical implications, dose-based side effect and degree of pain mitigation associated with the current pharmacological therapy is incapable in complete resolution of chronic neuropathic pain patients which necessitates the perpetual requirement of novel medication therapy. Therefore, this study explored the ameliorative aptitude of two novel methanimine imitative like (E)-N-(4-nitrobenzylidene)-4­chloro-2-iodobenzamine (KB 09) and (E)-N-(4-methylbenzylidene)-4­chloro-2-iodobenzamine (KB 10) in chronic constriction injury (CCI) of sciatic nerve induced neuropathic pain in rat model. Standard behavioral tests like dynamic and static allodynia, cold, thermal and mechanical hyperalgesia along with rotarod activity were performed at various experimental days like 0, 3, 7, 14 and 21. Enzyme linked immunosorbent assay (ELISA) on spinal tissue and antioxidant assays on sciatic nerve were executed accompanied by molecular docking and simulation studies. Prolonged ligation of sciatic nerve expressively induced hyperalgesia as well as allodynia in rats. KB 09 and KB 10 substantially attenuated the CCI elicited hyperalgesia and allodynia. They significantly reduced the biomarkers of pain and inflammation like Interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α) in ELISA and while enhanced the GSH, SOD and CAT and diminished the MDA levels during antioxidant assays. KB 09 displayed -9.62 kcal/mol with TNF-α and -7.68 kcal/mol binding energy with IL-6 whereas KB 10 exhibited binding energy of -8.20 kcal/mol with IL-6 while -11.68 kcal/mol with TNF-α and hence both trial compounds ensured stable interaction with IL-6 and TNF-α during computational analysis. The results advocated that both methanimine derivatives might be novel candidates for attenuation of CCI-induced neuropathic pain prospects via anti-nociceptive, anti-inflammatory and antioxidant mechanisms.

In vivo assessment of a nanofibrous silk tube as nerve guide for sciatic nerve regeneration.

A nanofibrous silk nerve conduit has been evaluated for its efficiency based on the promotion of peripheral nerve regeneration in rats. The designed tubes with or without Schwann cells were implanted into a 10 mm gap in the sciatic nerves of the rats. Four months after the surgery, the regenerated nerves were monitored and evaluated by macroscopic assessments and histology. The results demonstrated that the nanofibrous grafts, especially in the presence of Schwann cells, enabled reconstruction of the rat sciatic nerve trunk with a restoration of nerve continuity and formation of nerve fibres with myelination. Histological data demonstrated the presence of Schwann and glial cells in regenerated nerves. This study strongly supports the feasibility of using artificial nerve grafts for peripheral nerve regeneration by bridging large defects in a rat model.

A novel endpoint for the assessment of chemotherapy-induced peripheral neuropathy in rodents: biomechanical properties of peripheral nerve.

Chemotherapy-induced peripheral neuropathy (CiPN) is a frequent adverse effect in patients and a leading safety consideration in oncology drug development. Although behavioral assessment and microscopic examination of the nerves and dorsal root ganglia can be incorporated into toxicity studies to assess CiPN risk, more sensitive and less labor-intensive endpoints are often lacking. In this study, rats and mice administered vincristine (75 µg kg-1  day-1 , i.p., for 10 days in rats and 100 µg kg-1  day-1 , i.p., for 11 days in mice, respectively) were employed as the CiPN models. Behavioral changes were assessed during the dosing phase. At necropsy, the sural or sciatic nerve was harvested from the rats and mice, respectively, and assessed for mechanical and histopathological endpoints. It was found that the maximal load and the load/extension ratio were significantly decreased in the nerves collected from the animals dosed with vincristine compared with the vehicle-treated animals (P < 0.05). Additionally, the gait analysis revealed that the paw print areas were significantly increased in mice (P < 0.01), but not in rats following vincristine administration. Light microscopic histopathology of the nerves and dorsal root ganglia were unaffected by vincristine administration. We concluded that ex vivo mechanical properties of the nerves is a sensitive endpoint, providing a new method to predict CiPN in rodent. Gait analysis may also be a useful tool in these pre-clinical animal models.

Functional outcome and cost-effectiveness of outpatient vs inpatient care for complex hind-foot and ankle surgery. A retrospective cohort study.

STUDY OBJECTIVE: To compare the postoperative functional outcome and the total cost associated with outpatient vs inpatient care following complex hind-foot and ankle surgery. DESIGN: Retrospective, cohort study. SETTING: Tertiary care center. PATIENTS: Forty patients, American Society of Anesthesiologists 1-3, of either sex undergoing elective complex hind-foot and ankle surgery (fusion, osteotomy, or multiple ligament repair). INTERVENTIONS: Both inpatients and outpatients received a continuous perineural infusion of local anesthetic for 48 hours at the core of a multimodal analgesic regimen. Patients were retrospectively identified, and an outpatient cohort was matched to an inpatient cohort in a 1:1 ratio for age, sex, baseline functional score, and type of surgery. MEASUREMENTS: The primary outcome was functional outcome upon discharge of the surgical program as measured by the Lower Extremity Functional Score. Secondary outcomes were the incidence of surgical or anesthetic complications and the total perioperative cost of care. RESULTS: Patients in both cohorts had similar functional outcome on discharge of the surgical program. Analgesia was effective in both groups, and no complications were reported. The cost of care for outpatients was 54% lower than that for inpatients. CONCLUSION: This retrospective study suggests that outpatient care including an ambulatory perineural infusion of local anesthetic may be a cost-effective alternative to inpatient care after complex foot and ankle surgery.

Assessment of neuroregenerative effect of dihydrotestosterone, on peripheral nerve regeneration using allografts: a rat sciatic nerve model.

OBJECTIVES: Effects of dihydrotestosterone on nerve allograft were studied in a rat sciatic nerve model. METHODS: 30 healthy male white Wistar rats were castrated and randomised into three experimental groups (n = 10): Normal control group (NC), autograft group (AUTO), allograft group (ALLO) and dihydrotestosterone-treated group (ALLO/DHT). In NC group, left sciatic nerve was exposed and left intact. In autograft group, a segment of sciatic nerve was transected and reimplanted reversely. In the ALLO group, the left sciatic nerve was exposed and transected where a 10-mm segment was excised. The same procedure was performed in the ALLO/DHT group. The harvested nerves of the rats of ALLO group were served as allograft for ALLO/DHT group and vice versa. The NC, AUTO and ALLO groups received 300 µl phosphate buffered saline (PBS) intraperitoneally once a day for 1 week and the ALLO/DHT group received 300 µl DHT (1 mg/kg/day) interaperitoneally once a day for 1 week. RESULTS: The results showed earlier regeneration of axons in ALLO/DHT than in ALLO group (P < 0.05). Histomorphometic and immunohistochemical studies also showed earlier regeneration of axons in ALLO/DHT than in ALLO group (P < 0.05). DISCUSSIONS: Administration of DHT could accelerate functional recovery after nerve allografting in sciatic nerve and may have implications in clinical practice.

Multimodal assessment of painful peripheral neuropathy induced by chronic oxaliplatin-based chemotherapy in mice.

BACKGROUND: A major clinical issue affecting 10-40% of cancer patients treated with oxaliplatin is severe peripheral neuropathy with symptoms including cold sensitivity and neuropathic pain. Rat models have been used to describe the pathological features of oxaliplatin-induced peripheral neuropathy; however, they are inadequate for parallel studies of oxaliplatin's antineoplastic activity and neurotoxicity because most cancer models are developed in mice. Thus, we characterized the effects of chronic, bi-weekly administration of oxaliplatin in BALB/c mice. We first studied oxaliplatin's effects on the peripheral nervous system by measuring caudal and digital nerve conduction velocities (NCV) followed by ultrastructural and morphometric analyses of dorsal root ganglia (DRG) and sciatic nerves. To further characterize the model, we examined nocifensive behavior and central nervous system excitability by in vivo electrophysiological recording of spinal dorsal horn (SDH) wide dynamic range neurons in oxaliplatin-treated mice RESULTS: We found significantly decreased NCV and action potential amplitude after oxaliplatin treatment along with neuronal atrophy and multinucleolated DRG neurons that have eccentric nucleoli. Oxaliplatin also induced significant mechanical allodynia and cold hyperalgesia, starting from the first week of treatment, and a significant increase in the activity of wide dynamic range neurons in the SDH. CONCLUSIONS: Our findings demonstrate that chronic treatment with oxaliplatin produces neurotoxic changes in BALB/c mice, confirming that this model is a suitable tool to conduct further mechanistic studies of oxaliplatin-related antineoplastic activity, peripheral neurotoxicity and pain. Further, this model can be used for the preclinical discovery of new neuroprotective and analgesic compounds.

Allopregnanolone prevents and suppresses oxaliplatin-evoked painful neuropathy: multi-parametric assessment and direct evidence.

Oxaliplatin (OXAL) is a platinum-based drug used for the treatment of colorectal, lung, breast and ovarian cancers. OXAL does not cause renal or hematologic toxicity. However, OXAL induces neuropathic pain which hampers the chemotherapy success. Attempts with neuroprotective agents including anticonvulsivants and antidepressants were made to prevent OXAL-induced painful neuropathy but the clinical data are controversial and the tested neuroprotectors are able to evoke themselves undesirable effects. Here, we demonstrated that the natural neurosteroid allopregnanolone (3α,5α-THP), known to be devoid of toxic side-effects in humans and experimental models, prevented and suppressed OXAL-induced painful neuropathic symptoms. Indeed, 3α,5α-THP repaired OXAL-evoked neurochemical and functional alterations in peripheral nerves and intra-epidermal nerve fibers (IENF). Behavioral analyses showed that prophylactic or corrective 3α,5α-THP treatment (4mg/kg/2days) respectively prevented or abolished OXAL-induced cold allodynia, mechanical allodynia and hyperalgesia by reversing to normal decreased thermal and mechanical pain thresholds of OXAL-treated rats. Electrophysiological investigations revealed that 3α,5α-THP restored control values of sciatic nerve conduction velocity and action potential peak amplitude drastically reduced by OXAL-treatment. Furthermore, immunohistochemistry and confocal microscopic quantifications demonstrated that 3α,5α-THP repaired OXAL-induced neurochemical/cellular alterations by restoring IENF control density and normal level of neurofilament 200kDa that was strongly repressed by OXAL in dorsal root ganglion neurons and sciatic nerve axons. OXAL showed no toxicity for the non-compact myelin protein 2',3'-cyclic-nucleotide-3'-phosphodiesterase whose expression level was similarly increased by 3α,5α-THP in controls and OXAL-treated rat nerves. Together, these results may be interesting for the development of natural or safe neurosteroid-based neuroprotective strategy against anticancer drug-evoked painful neuropathy.

Assessment of 3-nitropropionic acid-evoked peripheral neuropathy in rats: neuroprotective effects of acetyl-l-carnitine and resveratrol.

Oxidative stress and secondary excitotoxicity, due to cellular energy deficit, are major factors playing roles in 3-nitropropionic acid (3-NPA) induced mitochondrial dysfunction. Acute or chronic exposure to 3-NPA also leads to neuronal degeneration in different brain regions. The present study quantitatively assessed peripheral neuropathy induced by chronic exposure to 3-NPA in rats. The neuroprotective abilities of two antioxidants, acetyl-l-carnitine and resveratrol, were investigated as well. Rats were exposed for up to four weeks to 3-NPA alone or 3-NPA combined with acetyl-l-carnitine or resveratrol, administered peripherally. The experimental outcome was evaluated by neurophysiological, histological, and morphometric analyses. Rats exposed to 3-NPA developed hind limb paresis. Furthermore, a significant decrease in motor nerve conduction velocity (MCV) was detected in tail nerves and axonal degeneration in sciatic nerves (p<0.05). Treatment with resveratrol prevented the functional effects of 3-NPA exposure, whereas treatment with acetyl-l-carnitine, preventing paresis, was not effective to MCV and morphological changes. These data suggest that resveratrol is a good candidate for treatment of metabolic neuropathy. The experimental outcome of this study shows that chronic treatment with 3-NPA in rats is relevant in development of an experimental model of toxic neuropathy.

Is ultrasound guidance mandatory when performing paediatric regional anaesthesia?

PURPOSE OF REVIEW: Since Kapral in 1994 first described the use of real-time ultrasound-guided regional anaesthesia, this novel technique has gained widespread recognition in adult practice and has been shown to be associated with clinically relevant advantages. The aim of this manuscript is to review the currently published paediatric data associated with the use of ultrasound-guided regional anaesthesia. RECENT FINDINGS: Compared with alternative techniques ultrasound guidance is associated with an increased success rate, reduced onset time, moderately prolonged duration, reduced need for local anaesthetics and lower costs, and may also be considered to reduce the risk for complications. SUMMARY: Based on current data the use of ultrasound guidance is strongly recommended when performing peripheral nerve blocks in infants and children. Concerning ultrasound assistance in relation to paediatric neuroaxial blocks there is currently not enough supporting evidence to issue a general recommendation regarding its routine use.

In vitro assessment of the effects of cadmium and zinc on mammalian nerve fibres.

Zinc and cadmium are environmental contaminants that have a wide range of effects on the nervous system, but zinc is also considered to be an important metal in the human body. In this study the effect of CdCl(2) and ZnCl(2), at concentrations of 50,150, 250 and 500 microM, on the nerve fibres of the sciatic nerve of the rat isolated in a three-chamber recording bath were studied. At the same concentrations, CdCl(2) and ZnCl(2) were found to have almost the same inhibitory effect on the compound action potential (CAP) of the nerve fibres. Their concentration-effect curves almost overlap and there was no significant difference in their EC(50) which for CdCl(2) is 250.1+/-18 microM (n=5) and for ZnCl(2) is 282.2+/-25 microM (n=5) correspondingly (P>0.05). The no-observed-effect concentration (NOEC) was estimated to be 50-100 microM for both metals. The identical inhibitory effect of both metals on the sciatic nerve fibres indicates a common mode of action which is related to their potential to generate reactive oxygen species (ROS).

Pathological assessment of the nervous and male reproductive systems of rat offspring exposed maternally to acrylamide during the gestation and lactation periods - a preliminary study.

To evaluate the developmental effects of exposure to acrylamide (ACR) on the nervous and male reproductive systems, pregnant Sprague-Dawley rats were given ACR at 0, 50, 100 or 200 ppm in the drinking water from gestational day 10 to postnatal day 21 and histopathological assessment of offspring was performed at weaning and postnatal week 11. Neurotoxicity was quantitatively assessed with reference to nerve fiber density, percentages of degenerated and small caliber axons in the sciatic nerves, and numbers of aberrant dot-like structures immunoreactive for synaptophysin in the cerebellar molecular layer. Although maternal neurotoxicity was evident from 100 ppm, no changes suggestive of neurotoxicity or testicular toxicity were observed in offspring. However, lowering of body weights was dose-dependently observed from birth at the dose levels of > or =50 ppm in males and > or =100 ppm in females. Maternal malnutrition was apparent at >/=100 ppm during the lactation period. Therefore, poor lactational ACR-exposure due to maternal toxicity might account for the lack of ACR-induced offspring toxicity other than retarded body growth.

Assessment of long- and short-term neurotoxic effects of glass ionomer bone cement by electromyography and histopathologic examination: experimental study.

OBJECTIVE: The objective of this study was to investigate the possible neurotoxic effects of bone cement on the peripheral nerves. STUDY DESIGN: Experimental study. SETTING: Teaching and research hospital. METHODS: Twenty New Zealand rabbits were included in this study. The sciatic nerves of both legs of the 10 rabbits were exposed surgically under general anesthesia and closed primarily without any intervention and constituted the control group (group 1). Following surgical exploration, glass ionomer cement (GIC) was applied to the left sciatic nerves of the 10 rabbits for 10 seconds and then aspirated (group 2). GIC material was also applied to the right sciatic nerves of these rabbits but without aspiration (group 3). OUTCOME MEASURES: All rabbits were sacrificed at the end of 8 weeks postoperatively following electromyographic investigation. The sections were stained with hematoxylin-eosin and Immune Olig 2 staining technique for histopathologic examination under light microscopy. RESULTS: There was no statistically significant difference in distal latency, which indicates the conduction speed of the nerve, between all groups by electromyography. Histopathologic examination of all specimens revealed no demyelinization or axonal degeneration, and all had an intact myelin structure. There was no statistically significant difference in inflammation of the specimens between groups. (p>.05). CONCLUSION: GIC has no neurotoxic effects on the nerves in short- and long-term applications.

In vitro assessment of the neurotoxic and neuroprotective effects of N-acetyl-L-cysteine (NAC) on the rat sciatic nerve fibers.

N-acetyl-L-cysteine (NAC), at a concentration of 1-60mM, has been previously used extensively for protection in a variety of cell cultures against the deleterious effects of various compounds. The results of this in vitro study show that NAC has certain unusual effects on the evoked compound action potential (CAP) of the rat sciatic nerve fibers. Firstly, at concentrations of 5.0, 3.5 and 2.5mM, concentrations used by others as a protectant for cell cultures, NAC inhibits the action potentials of the sciatic nerve fibers completely in a concentration-dependent manner within a few minutes or hours (2.5mM). Secondly, the acute inhibitory action of NAC on the CAP of the nerve fibers was not spontaneously reversible, but as soon as NAC was replaced with saline there was a partial (approximately 75%) recovery in the function of the nerve fibers. Thirdly, the no observed effect concentration for NAC was estimated to be 1mM. The paradox is that NAC at 1 mM not only had no effect on the nerve fibers, but it became an excellent neuroprotective compound, giving almost 100% neuroprotection against cadmium-induced neurotoxicity. The results show a possible effect of NAC on voltage-gated sodium and potassium channels. The observed neuroprotective-neurotoxic properties of NAC require careful reconsideration of its use in either in vitro studies or in vivo pharmaceutical applications.

Stimulating or conventional perineural catheters after hallux valgus repair: a double-blind, pharmaco-economic evaluation.

BACKGROUND: We prospectively evaluated direct analgesia-related costs of continuous sciatic nerve block using either a stimulating or conventional catheter after hallux valgus repair. METHODS: The perineural catheter was inserted through a stimulating introducer either blindly (group Conventional, n= 38) or while stimulating via the catheter (group Stimulating, n= 38). Nerve block was induced with 25 ml of mepivacaine 15 mg/ml, and was followed 3 h later by a patient-controlled infusion of ropivacaine 2 mg/ml (basal infusion: 3 ml/h; incremental dose: 5 ml; lock-out time: 30 min). Rescue tramadol [100 mg intravenous (i.v.)] was given if required. Local anesthetic consumption, need for rescue tramadol and post-operative nausea and vomiting (PONV) treatment, and patient's satisfaction were recorded during first 24-h infusion. Cost calculations were based on the acquisition cost of drugs and devices. RESULTS: Both techniques were similarly effective, but local anesthetic consumption and need for rescue analgesics were lower in the Stimulating group [respectively, 120 vs. 153 ml (P= 0.004) and 21% vs. 60% (P= 0.001)]. The analgesia-related costs for 24 h were similar when 100-ml bags of ropivacaine 2 mg/ml were used (66 euro vs. 67 euro; P= 0.26). When 200-ml bags of ropivacaine were used, the analgesia-related costs were higher in the Stimulating group than the Conventional group (75 euro vs. 55 euro; P= 0.0005). CONCLUSIONS: Direct costs of continuous sciatic nerve block ranged from 55 to 75 euro. Stimulating catheters reduced local anesthetic consumption and need for rescue analgesics. This was only cost effective when 100-ml bags of 2 mg/ml ropivacaine were used, while the cheapest combination was the use of conventional catheters and 200-ml bags of ropivacaine.

Assessment of motoneuron death during development following neonatal nerve crush and Mg2+ treatment.

BACKGROUND: Sciatic nerve injury in neonatal rats impairs muscle recovery and significantly reduces the number of surviving motoneurons. We examined the rate of motoneuron death after sciatic nerve crush in neonatal rats, as well as the neuroprotective effect of systemic MgSO4 administration, by assessing the number of horseradish peroxidase -labelled motoneurons in the spinal cord ventral horn, after injecting EDL and TA muscles. MATERIAL/METHODS: Left sciatic nerve crush was performed on the 2nd postnatal day. MgSO4 (0.05 ml of 1 M solution/10 g body weight) was administered subcutaneously, daily for twelve days. Animals were examined for the number of motoneurons of EDL and TA muscles, in the spinal cord ventral horns at 14, 21, and 28 days postnatally (P) and adulthood. 24 h to 48 h after intramuscular HRP injection, the animals were perfused transcardially with a fixative containing glutaraldehyde. Serial sections of the spinal cords were cut and processed for Hanker-Yates staining, and the number of labeled motoneurons was measured under a camera lucida. RESULTS: Nerve crush resulted in 37% motoneuron survival at P14, 33% at P21, 28% at P28 and 21% in adult rats. Following MgSO4 administration motoneuron survival rates of 51%, 47%, 44% and 39% were observed respectively, for the different age groups. The values obtained in magnesium-treated rats proved to be significantly different (p<0.05), compared to non-treated rats of the same age group. CONCLUSIONS: Nerve crush after birth resulted in significant motoneuron death, established already at P14. MgSO4 administration induced significant motoneuron survival.

Overall assessment of regeneration in peripheral nerve lesion repair using fibrin glue, suture, or a combination of the 2 techniques in a rat model. Which is the ideal choice?

BACKGROUND: Nerve repair with fibrin glue is an alternative to conventional suture technique, although there is no definitive experimental evaluation of the 2 techniques. This experimental study was undertaken to evaluate nerve regeneration after sciatic nerve repair with fibrin glue and to compare it with repair performed with suture and a combination of both techniques. METHODS: Eighty-six male Wistar rats were subjected to right sciatic nerve transection and immediate repair with 4-stitch nylon suture (group A), fibrin glue (group B), or a combination of both techniques (group C). Walking track analysis to access functional recovery was performed preoperatively and 12 weeks postoperatively. Before nerve section and after a 24-week interval, the nerve and motor action potentials (MAPs) were evaluated. Histomorphometric evaluation was carried out 24 weeks after nerve section. Differences between groups were evaluated for significance using the Kruskal-Wallis or analysis of variance methods. RESULTS: Animals of group B presented better results than those of group A when the functional evaluation was applied (P < .05). When nerve conduction velocity was evaluated at reoperation and the ratio between conduction velocity at reoperation and before the nerve section in MAP evaluation were measured and compared in the 3 groups, the rats of group B presented better results than those of group A (P < .05). Animals of group C presented better results than those of group A when the ratio between nerve conduction velocities was considered. There was no difference between the nerve repair methods when histomorphometric evaluation was performed. CONCLUSION: In a rat model, nerve repair using fibrin glue provided better conditions for regeneration than suture after sciatic nerve transection.

Assessment of effects of pinealectomy and exogenous melatonin administration on rat sciatic nerve suture repair: an electrophysiological, electron microscopic, and immunohistochemical study.

BACKGROUND: Collagen scar formation at the cut end of a nerve, an important problem in clinical practice for neurosurgeons in peripheral nerve surgery, obstructs sprouting of axons into appropriate distal fascicles, and thereby limits nerve regeneration. Researchers attempt to control collagen accumulation in the formation of neuroma by various physical and chemical methods, but these have yielded only limited functional success. This is the first experimental study investigating the effects of melatonin (MLT) on nerve repair and neuronal regeneration in rat sciatic nerve suture repair. METHODS: The hypothesis that exogenous MLT administration may inhibit the formation of neuroma in peripheral nerve surgery was investigated in rat sciatic nerve model. In this study, a total of 80 rats were used for control groups (Groups Ia, Ib, IIa, and IId), MLT group (Group Ic), surgical pinealectomy (Px) groups (Groups IIb and IIc), and group of MLT treatment following Px procedure (Group IIe). All animals underwent a surgical intervention consisting of bilateral sciatic nerve section and primary suture repair. At 8 weeks after repair, the animals were killed following completion of recording of nerve action potentials (NAPs). Then, unilateral sciatic nerve specimens including the suture repair region were carefully removed and the excised segments were processed for electron microscopy examination. Afterwards, contralateral sciatic nerve specimens from two animals from each group were removed and stained for immunohistochemical analysis. RESULTS: Results of morphometric analysis revealed that Px procedure caused an elevation of collagen content of the sciatic nerve and macroscopic neuroma formation, and that there was a statistically significant reduction in collagen content of the same region in pinealectomized animals treated with MLT (p<0.001). Accordingly, electrophysiological findings demonstrated that the stimulus intensities required to excite a NAP response were increased in surgical Px group, but the presence of a reduced threshold response was found in the group treated with MLT following Px procedure (p<0.01). Immunohistochemical staining for Type I collagen and Type III collagen was markedly more intense in the epineurium of animals after Px. Virtually no or only weak staining was observed in animals in control groups and the MLT treatment group. Results of immunohistochemical analysis revealed that surgical Px procedure caused a strong immunoreactivity for Type I collagen and Type III collagen in all connective tissue planes of the nerve, especially in the epineurium, and there was a statistically significant reduction in immunoreactivity of the repair region in animals receiving MLT treatment after Px procedure (p<0.001). CONCLUSION: This study demonstrates that exogenous MLT administration significantly inhibits collagen accumulation in the formation of neuroma in the suture repair site and thereby improves nerve regeneration. From a clinical standpoint, the positive effect of MLT administration on neuroma formation and nerve regeneration seems a particularly attractive treatment option. Therefore, we believe that nerve repair with addition of MLT may be a worthwhile option in addition to other treatment modalities in case of MLT deficiency, such as aging. However, further experimental and clinical studies using functional analysis warranted to confirm this result in future.

Comparison of two screening bioassays, based on the frog sciatic nerve and yeast cells, for the assessment of herbicide toxicity.

Two different test systems, one based on the isolated sciatic nerve of an amphibian and the other on a microbial eukaryote, were used for the assessment of herbicide toxicity. More specifically, we determined the deleterious effects of increasing concentrations of herbicides of different chemical classes (phenoxyacetic acids, triazines, and acetamides), and of 2,4-dichlorophenol (2,4-DCP), a degradation product of the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D), on electrophysiological parameters and the vitality of the axons of the isolated sciatic nerve of the frog (Rana ridibunda) and on the growth curve of the yeast Saccharomyces cerevisiae based on microtiter plate susceptibility assays. The no-observed-effect-concentration (NOEC), defined as the maximum concentration of the tested compound that has no effect on these biological parameters, was estimated. In spite of the different methodological approaches and biological systems compared, the NOEC values were identical and correlated with the lipophilicity of the tested compounds. The relative toxicity established here, 2,4-DCP > alachlor, metolachlor >> metribuzin > 2,4-D, 2-methyl-4-chlorophenoxyacetic acid (MCPA), correlates with the toxicity indexes reported in the literature for freshwater organisms. Based on these results, we suggest that the relatively simple, rapid, and low-cost test systems examined here may be of interest as alternative or complementary tests for toxicological assessment of herbicides.

Assessment of differential blockade by amitriptyline and its N-methyl derivative in different species by different routes.

BACKGROUND: Increasing the duration of local anesthesia and/or creating greater differential blockade (i.e., selective block of pain-transmitting nerve fibers) has been attempted by modifying currently available agents. Most drugs show a different profile depending on the model or species studied. This study was designed to investigate the differential nerve-blocking properties of amitriptyline and its quaternary ammonium derivative in rats and sheep. METHODS: The Na+ channel-blocking properties of N-methyl amitriptyline were determined with the patch clamp technique in cultured GH(3) cells. Various functions (motor, nociception, proprioception-ataxia) were compared in rats (spinal and sciatic nerve blockade) and sheep (spinal blockade) with amitriptyline, N-methyl amitriptyline, lidocaine, and bupivacaine (partially from historical data). RESULTS: In vitro testing revealed N-methyl amitriptyline to be a potent Na+ channel blocker similar to amitriptyline but with a much longer duration of action. All drug concentrations tested in both the sciatic nerve model and the spinal block model produced no significant differential blockade in rats. Three of six rats in the 20-mM N-methyl amitriptyline group showed residual blockade 4 days after sciatic nerve injection. However, in the sheep spinal model, amitriptyline and in particular N-methyl amitriptyline displayed significant differential blockade at most time points. Sheep data for lidocaine and bupivacaine seemed to be more comparable to the clinical experience in humans than did rat data. CONCLUSIONS: Amitriptyline and N-methyl amitriptyline are potent Na+ channel blockers and show greater differential blockade in sheep than in rats. This differential blockade in sheep is greater than that produced by lidocaine or bupivacaine.

[An assessment of neuronal regeneration in neural anastomoses by synthetic guide and biological systems and insulin administration: an experimental study in the rat]. / Valutazione della rigenerazione neuronale nelle anastomosi nervose mediante sistemi tutoriali sintetici, biologici e somministrazione di insulina: studio sperimentale sul ratto.

The synthetic and biological nerve guide regeneration gives interesting perspective of use in making artificial conduits for peripheral nerve reconstruction. In sixty Wistar rats, under general anesthesia and with microsurgical technique, the ischiatic nerve was isolated. On the right side a segment of the nerve was removed in order to create a 10 mm gap. The defect then repaired using the conduit. Control were performed at 20, 90, 180 days and consisted in histological microscopy and electromyography investigation. The regeneration of the nerve fibers in the lumen of the conduit was not significantly different on the contralateral nerve limb.