Nerve recovery from treatment with a vascularized nerve graft compared to an autologous non-vascularized nerve graft in animal models: A systematic review and meta-analysis

Background

Treatment of nerve injuries proves to be a worldwide clinical challenge. Vascularized nerve grafts are suggested to be a promising alternative for bridging a nerve gap to the current gold standard, an autologous non-vascularized nerve graft. However, there is no adequate clinical evidence for the beneficial effect of vascularized nerve grafts and they are still disputed in clinical practice.

Objective

To systematically review whether vascularized nerve grafts give a superior nerve recovery compared to non-vascularized nerve autografts regarding histological and electrophysiological outcomes in animal models.

Material and methods

PubMed and Embase were systematically searched. The inclusion criteria were as follows: 1) the study was an original full paper which presented unique data; 2) a clear comparison between a vascularized and a non-vascularized autologous nerve transfer was made; 3) the population study were animals of all genders and ages. A standardized mean difference and 95% confidence intervals for each comparison was calculated to estimate the overall effect. Subgroup analyses were conducted on graft length, species and time frames.

Results

Fourteen articles were included in this review and all were included in the meta-analyses. A vascularized nerve graft resulted in a significantly larger diameter, higher nerve conduction velocity and axonal count compared to an autologous non-vascularized nerve graft. However, during sensitivity analysis the effect on axonal count disappeared. No significant difference was observed in muscle weight.

Conclusion

Treating a nerve gap with a vascularized graft results in superior nerve recovery compared to non-vascularized nerve autografts in terms of axon count, diameter and nerve conduction velocity. No difference in muscle weight was seen. However, this conclusion needs to be taken with some caution due to the inherent limitations of this meta-analysis. We recommend future studies to be performed under conditions more closely resembling human circumstances and to use long nerve defects.

Exercise induced hypoalgesia profile in rats is associated with IL-10 and IL-1 β levels and pain severity following nerve injury

BACKGROUND

Pain may undergo modulation in the central nervous system prior to reaching the primary somatosensory cortex and being perceived as pain. Faulty pain modulation mechanisms have been linked to various chronic pain conditions. Cytokines such as IL-10 and IL-1beta, are known to be involved in initiation and maintenance of neuropathic pain. In this study, we investigated the association between pain modulation profile, pain intensity and cytokines (IL-10 and IL-1beta) levels in a rat model of neuropathic pain.

METHODS

Exercise-Induced Hypoalgesia (EIH) was assessed by evaluating the percentage of responses to a train of 60g mechanical stimuli before and after 180 seconds of exercise on a rotating rod. The differences in the response rates before and after the exercise were used to divide the rats into low and high EIH responders. Rats from low and high EIH groups underwent constriction injury of the left sciatic nerve. Pain behavior (allodynia and hyperalgesia) were assessed by measuring responses to mechanical and thermal stimuli applied to the plantar surface of the foot. Serum, sciatic nerve and the related Dorsal Root Ganglia (DRG) levels of IL-10 and IL-1beta were determined by ELISA. The DRG mRNA levels of IL-10 and IL-1beta measured with PCR. A comparison between the low and high EIH rats of all measured parameters was made.

RESULTS

The low EIH rats developed significantly more severe allodynia and hyperalgesia in the affected paw and allodynia in the contralateral paw compared to the high EIH rats, 7 days following the injury. The low EIH rats had higher IL-1beta protein levels in serum prior to and following injury, higher affected and contralateral sciatic nerve IL-1beta levels following injury and higher IL-1beta levels in the contralateral DRG (protein and mRNA) following injury when compared to high EIH rats. The high EIH rats had higher affected sciatic nerve IL-10 levels following nerve injury and higher IL-10 levels of both protein and mRNA in the affected and contralateral DRG at baseline and following injury.

CONCLUSION

EIH profile was found to be predictive of pain behavior following nerve injury, low EIH rats developed more severe allodynia and hyperalgesia. IL-1beta may be associated with painful neuropathy developed in rats with low EIH while the anti-inflammatory cytokine IL-10 may have a protective role, inhibiting the development of painful.

Genomic Action of Sigma-1 Receptor Chaperone Relates to Neuropathic Pain

Sigma-1 receptors (Sig-1Rs) are endoplasmic reticulum (ER) chaperones implicated in neuropathic pain. Here we examine if the Sig-1R may relate to neuropathic pain at the level of dorsal root ganglia (DRG). We focus on the neuronal excitability of DRG in a "spare nerve injury" (SNI) model of neuropathic pain in rats and find that Sig-1Rs likely contribute to the genesis of DRG neuronal excitability by decreasing the protein level of voltage-gated Cav2.2 as a translational inhibitor of mRNA. Specifically, during SNI, Sig-1Rs translocate from ER to the nuclear envelope via a trafficking protein Sec61β. At the nucleus, the Sig-1R interacts with cFos and binds to the promoter of 4E-BP1, leading to an upregulation of 4E-BP1 that binds and prevents eIF4E from initiating the mRNA translation for Cav2.2. Interestingly, in Sig-1R knockout HEK cells, Cav2.2 is upregulated. In accordance with those findings, we find that intra-DRG injection of Sig-1R agonist (+)pentazocine increases frequency of action potentials via regulation of voltage-gated Ca2+ channels. Conversely, intra-DRG injection of Sig-1R antagonist BD1047 attenuates neuropathic pain. Hence, we discover that the Sig-1R chaperone causes neuropathic pain indirectly as a translational inhibitor.

Leptin Contributes to Neuropathic Pain via Extrasynaptic NMDAR-nNOS Activation

Leptin is an adipocytokine that is primarily secreted by white adipose tissue, and it contributes to the pathogenesis of neuropathic pain in collaboration with N-methyl-D-aspartate receptors (NMDARs). Functional NMDARs are a heteromeric complex that primarily comprise two NR1 subunits and two NR2 subunits. NR2A is preferentially located at synaptic sites, and NR2B is enriched at extrasynaptic sites. The roles of synaptic and extrasynaptic NMDARs in the contribution of leptin to neuropathic pain are not clear. The present study examined whether the important role of leptin in neuropathic pain was related to synaptic or extrasynaptic NMDARs. We used a rat model of spared nerve injury (SNI) and demonstrated that the intrathecal administration of the NR2A-selective antagonist NVP-AAM077 and the NR2B-selective antagonist Ro25-6981 prevented and reversed mechanical allodynia following SNI. Administration of exogenous leptin mimicked SNI-induced behavioral allodynia, which was also prevented by NVP-AAM077 and Ro25-6981. Mechanistic studies showed that leptin enhanced NR2B- but not NR2A-mediated currents in spinal lamina II neurons of naïve rats. Leptin also upregulated the expression of NR2B, which was blocked by the NR2B-selective antagonist Ro25-6981, in cultured dorsal root ganglion (DRG) neurons. Leptin enhanced neuronal nitric oxide synthase (nNOS) expression, which was also blocked by Ro25-6981, in cultured DRG cells. However, leptin did not change NR2A expression, and the NR2A-selective antagonist NVP-AAM077 had no effect on leptin-enhanced nNOS expression. Our data suggest an important cellular link between the spinal effects of leptin and the extrasynaptic NMDAR-nNOS-mediated cellular mechanism of neuropathic pain.

Effect of Paroxetine on the Neuropathic Pain: A Molecular Study

Background

Neuropathic pain, due to peripheral nerve damage, has influenced millions of people living all over the world. It has been shown that paroxetine can relieve neuropathic pain. Recently, the role of certain proteins like brain-derived neurotrophic factor (BDNF), GABAA receptor, and K+-Cl- cotransporter 2 (KCC2) transporter in the occurrence of neuropathic pain has been documented. In the current study, the expression of these proteins affected by paroxetine was evaluated.

Methods

Male Wistar rats were allocated into two main groups of pre- and post-injury. Rats in each main group received paroxetine before nerve injury and at day seven after nerve damage till day 14, respectively. The lumbar spinal cord of animals was extracted to assess the expression of target genes and proteins.

Results

In the preventive study, paroxetine decreased BDNF and increased KCC2 and GABAA gene and protein expression, while in the post-injury paradigm, it decreased BDNF and increased KCC2 genes and protein expression. In this regard, an increase in the protein expression of GABAA was observed.

Conclusion

It seems that paroxetine with a change in the expression of three significant proteins involved in neuropathic pain could attenuate this type of chronic pain.

Pain-Relieving Effects of mTOR Inhibitor in the Anterior Cingulate Cortex of Neuropathic Rats

The anterior cingulate cortex (ACC) is a well-known brain area that is associated with pain perception. Previous studies reported that the ACC has a specific role in the emotional processing of pain. Chronic pain is characterized by long-term potentiation that is induced in pain pathways and contributes to hyperalgesia caused by peripheral nerve injury. The mammalian target of rapamycin (mTOR) signaling, which is involved in synaptic protein synthesis, could be a key factor controlling long-term potentiation in neuropathic pain conditions. Until now, there have been no reports that studied the role of mTOR signaling in the ACC involved in neuropathic pain. Therefore, this study was conducted to determine the relationship of mTOR signaling in the ACC and neuropathic pain. Male Sprague-Dawley rats were subjected to cannula implantation and nerve injury under pentobarbital anesthesia. Microinjection with rapamycin into the ACC was conducted under isoflurane anesthesia on postoperative day (POD) 7. A behavioral test was performed to evaluate mechanical allodynia, and optical imaging was conducted to observe the neuronal responses of the ACC to peripheral stimulation. Inhibition of mTOR by rapamycin reduced mechanical allodynia, down-regulated mTOR signaling in the ACC, and diminished the expressions of synaptic proteins which are involved in excitatory signaling, thereby reducing neuropathic pain-induced synaptic plasticity. These results suggest that inhibiting mTOR activity by rapamycin in the ACC could serve as a new strategy for treating or managing neuropathic pain before it develops into chronic pain.

Testing the effectiveness and the contribution of experimental supercharge (reversed) end-to-side nerve transfer

OBJECTIVE

Supercharge end-to-side (SETS) transfer, also referred to as reverse end-to-side transfer, distal to severe nerve compression neuropathy or in-continuity nerve injury is gaining clinical popularity despite questions about its effectiveness. Here, the authors examined SETS distal to experimental neuroma in-continuity (NIC) injuries for efficacy in enhancing neuronal regeneration and functional outcome, and, for the first time, they definitively evaluated the degree of contribution of the native and donor motor neuron pools.

METHODS

This study was conducted in 2 phases. In phase I, rats (n = 35) were assigned to one of 5 groups for unilateral sciatic nerve surgeries: group 1, tibial NIC with distal peroneal-tibial SETS; group 2, tibial NIC without SETS; group 3, intact tibial and severed peroneal nerves; group 4, tibial transection with SETS; and group 5, severed tibial and peroneal nerves. Recovery was evaluated biweekly using electrophysiology and locomotion tasks. At the phase I end point, after retrograde labeling, the spinal cords were analyzed to assess the degree of neuronal regeneration. In phase II, 20 new animals underwent primary retrograde labeling of the tibial nerve, following which they were assigned to one of the following 3 groups: group 1, group 2, and group 4. Then, secondary retrograde labeling from the tibial nerve was performed at the study end point to quantify the native versus donor regenerated neuronal pool.

RESULTS

In phase I studies, a significantly increased neuronal regeneration in group 1 (SETS) compared with all other groups was observed, but with modest (nonsignificant) improvement in electrophysiological and behavioral outcomes. In phase II experiments, the authors discovered that secondary labeling in group 1 was predominantly contributed from the donor (peroneal) pool. Double-labeling counts were dramatically higher in group 2 than in group 1, suggestive of hampered regeneration from the native tibial motor neuron pool across the NIC segment in the presence of SETS.

CONCLUSIONS

SETS is indeed an effective strategy to enhance axonal regeneration, which is mainly contributed by the donor neuronal pool. Moreover, the presence of a distal SETS coaptation appears to negatively influence neuronal regeneration across the NIC segment. The clinical significance is that SETS should only employ synergistic donors, as the use of antagonistic donors can downgrade recovery.

Is there a reasonable excuse for not providing post-operative analgesia when using animal models of peripheral neuropathic pain for research purposes?

Introduction

The induction of neuropathic pain-like behaviors in rodents often requires surgical intervention. This engages acute nociceptive signaling events that contribute to pain and stress post-operatively that from a welfare perspective demands peri-operative analgesic treatment. However, a large number of researchers avoid providing such care based largely on anecdotal opinions that it might interfere with model pathophysiology in the longer term.

Objectives

To investigate effects of various peri-operative analgesic regimens encapsulating different mechanisms and duration of action, on the development of post-operative stress/welfare and pain-like behaviors in the Spared Nerve Injury (SNI)-model of neuropathic pain.

Methods

Starting on the day of surgery, male Sprague-Dawley rats were administered either vehicle (s.c.), carprofen (5.0mg/kg, s.c.), buprenorphine (0.1mg/kg s.c. or 1.0mg/kg p.o. in Nutella^®), lidocaine/bupivacaine mixture (local irrigation) or a combination of all analgesics, with coverage from a single administration, and up to 72 hours. Post-operative stress and recovery were assessed using welfare parameters, bodyweight, food-consumption, and fecal corticosterone, and hindpaw mechanical allodynia was tested for assessing development of neuropathic pain for 28 days.

Results

None of the analgesic regimes compromised the development of mechanical allodynia. Unexpectedly, the combined treatment with 0.1mg/kg s.c. buprenorphine and carprofen for 72 hours and local irrigation with lidocaine/bupivacaine, caused severe adverse effects with peritonitis. This was not observed when the combination included a lower dose of buprenorphine (0.05mg/kg, s.c.), or when buprenorphine was administered alone (0.1mg/kg s.c. or 1.0mg/kg p.o.) for 72 hours. An elevated rate of wound dehiscence was observed especially in the combined treatment groups, underlining the need for balanced analgesia. Repeated buprenorphine injections had positive effects on body weight the first day after surgery, but depressive effects on food intake and body weight later during the first week.

Conclusion

Post-operative analgesia does not appear to affect established neuropathic hypersensitivity outcome in the SNI model.

Recruitment of dorsal midbrain catecholaminergic pathways in the recovery from nerve injury evoked disabilities

BACKGROUND

The periaqueductal gray region (PAG) is one of several brain areas identified to be vulnerable to structural and functional change following peripheral nerve injury. Sciatic nerve constriction injury (CCI) triggers neuropathic pain and three distinct profiles of changes in complex behaviours, which include altered social and sleep-wake behaviours as well as changes in endocrine function. The PAG encompasses subgroups of the A10 dopaminergic and A6 noradrenergic cell groups; the origins of significant ascending projections to hypothalamic and forebrain regions, which regulate sleep, complex behaviours and endocrine function. We used RT-PCR, western blots and immunohistochemistry for tyrosine hydroxylase to determine whether (1) tyrosine hydroxylase increased in the A10/A6 cells and/or; (2) de novo synthesis of tyrosine hydroxylase, in a 'TH-naïve' population of ventral PAG neurons characterized rats with distinct patterns of behavioural and endocrine change co-morbid with CCI evoked-pain.

RESULTS

Evidence for increased tyrosine hydroxylase transcription and translation in the constitutive A10/A6 cells was found in the midbrain of rats that showed an initial 2-3 day post-CCI, behavioural and endocrine change, which recovered by days 5-6 post-CCI. Furthermore these rats showed significant increases in the density of TH-IR fibres in the vPAG.

CONCLUSIONS

Our data provide evidence for: (1) potential increases in dopamine and noradrenaline synthesis in vPAG cells; and (2) increased catecholaminergic drive on vPAG neurons in rats in which transient changes in social behavior are seen following CCI. The data suggests a role for dopaminergic and noradrenergic outputs, and catecholaminergic inputs of the vPAG in the expression of one of the profiles of behavioural and endocrine change triggered by nerve injury.

Separated interface nerve electrode prevents direct current induced nerve damage

Direct current, DC, can be used to quickly and reversibly block activity in excitable tissue, or to quickly and reversibly increase or decrease the natural excitability of a neuronal population. However, the practical use of DC to control neuronal activity has been extremely limited due to the rapid tissue damage caused by its use. We show that a separated interface nerve electrode, SINE, is a much safer method to deliver DC to excitable tissue and may be valuable as a laboratory research tool or potentially for clinical treatment of disease.

[Restoration of erectile function by reconstructing cavernous nerves with small intestinal submucosa grafts]

OBJECTIVE

To investigate the restoration of erectile function by reconstructing cavernous nerves (CN) with small intestinal submucosa (SIS) grafts.

METHODS

We prepared SIS grafts, established rat models and divided the models into a CN ablation, a sham-operation and an SIS graft group. The CNs at both sides were severed with 1 cm ablated in the first group, and 0.5 cm removed in the third, followed by reconstruction with the SIS grafts. Three months after surgery, the apomorphine test was performed to evaluate the erectile function, and then all the rats were sacrificed to detect the expression of nNOS in the penis.

RESULTS

Penile erection was observed in 72.73% (8/11) of the rats for (1.07 +/- 0.89) times within 30 min in the SIS graft group, as compared with 0% (0/11) of the rats for (0.00 +/- 0.00) times in the CN ablation group (P < 0.01), and 90.91% (10/11) of the rats for (2.19 +/- 1.17) times in the sham-operation group (P < 0.01). The number of nNOS nerve fibers was significantly larger in the SIS graft than in the CN ablation group (70.36 +/- 10.09 versus 22.09 +/- 4.76, P < 0.01), but both were significantly smaller than that of the sham-operation group (90.81 +/- 5.69, P < 0.01).

CONCLUSION

The SIS grafting technique contributes to the recanalization of the severed CN and restoration of erectile function in rats after surgical injury.

Pulsed radiofrequency for the treatment of chronic ilioinguinal neuropathy

BACKGROUND

Ilioinguinal neuropathy is a rare but disabling condition. The condition may arise spontaneously or in the setting of pelvic surgery. To date, most therapeutic options have been limited to neuropathic pain medications, anti-inflammatory medications, nerve blocks with local anesthetics, or neurectomy. Long-term results of non-surgical interventions are fair at best. We present a case of chronic ilioinguinal neuropathy treated with pulsed radiofrequency.

OBJECTIVE

To examine the efficacy of pulsed radiofrequency (PRF) lesioning on pain in ilioinguinal neuropathy.

METHOD

A 58-year old man with chronic ilioinguinal neuropathy was treated with PRF and was followed for 3 months.

RESULTS

The patient had significant pain relief at 3 months follow up.

CONCLUSION

Pulsed radiofrequency lesioning may be a good treatment for chronic ilioinguinal neuropathy in cases refractory to conservative management.

Pulsed radiofrequency for the treatment of ilioinguinal neuralgia after inguinal herniorrhaphy

BACKGROUND AND PURPOSE

Ilioinguinal neuralgia secondary to inguinal hernia repair is frequently a chronic, debilitating pain. It is most often due to destruction or entrapment of nerve tissue from staples, sutures, or direct surgical trauma. Treatment modalities, including oral analgesics, nerve blocks, mesh excision, and surgical neurectomy, have varied success rates. Pulsed radiofrequency (PRF) has recently been described as a successful method of treating chronic groin pain. Unlike conventional radiofrequency, PRF is non-neurodestructive and therefore less painful and without the potential complications of neuritis-like reactions and neuroma formation. Although the mechanism is unknown, it appears that the interaction of an electromagnetic field and c-fos proteins may alter normal transmission of painful impulses. Our study examines five patients treated with PRF for ilioinguinal neuralgia secondary to inguinal herniorrhaphy.

METHOD

Five patients were diagnosed with chronic ilioinguinal neuralgia secondary to inguinal hernia repair at our institution. Each patient was treated at vertebral T12, L1, and L2 with root PRF at 42 degrees C for 120 seconds per level.

RESULTS

Four out of five patients reported pain relief lasting from four to nine months on follow-up visits. Only one patient reported no pain relief whatsoever.

CONCLUSION

Ilioinguinal neuralgia is challenging to treat. We have demonstrated the successful use of PRF for four out of five patients seen in our office.

The effect of ventral nerve cord severance and male castration on female mating behavior, clutch size, and maternal care in the ring-legged earwig

Mating is critical for the expression of oviposition and maternal care in the earwig, Euborellia annulipes; additionally, mating diminishes receptivity to additional mating and promotes a decline in juvenile hormone synthesis at the end of the gonadotrophic cycle (in contrast to most insect species wherein mating stimulates juvenile hormone production). We report here that severance of the ventral nerve cord of virgin females similarly promoted egg deposition and maternal care of eggs, diminished mating receptivity, and elicited a timely decline in juvenile hormone biosynthesis. Mating of intact females to adult males that were castrated as larvae did not abolish oviposition; however, clutch size was reduced, and no eggs developed. Such castrated males had smaller seminal vesicles than did intact males, presumably attributable to lack of sperm in castrated males. In contrast, mating of intact females to males castrated on day 1 of adult life did not reduce clutch size compared with those of sham-operated animals and did not abolish fertilization; in fact, these castrated males produced viable offspring after six matings. These results are consistent with the notion that ventral nerve cord severance mimicked mating in intact animals. Following mating, the ventral nerve cord likely is a conduit to release the brain from inhibiting oviposition and maternal care. The presence of sperm in the spermatheca is not necessary for release of this inhibition but may modulate clutch size.

N-(4-Tertiarybutylphenyl)-4-(3-cholorphyridin-2-yl)tetrahydropyrazine -1(2H)-carbox-amide (BCTC), a novel, orally effective vanilloid receptor 1 antagonist with analgesic properties: II. in vivo characterization in rat models of inflammatory and neuropathic pain

The vanilloid receptor 1 (VR1) is a cation channel expressed predominantly by nociceptive sensory neurons and is activated by a wide array of pain-producing stimuli, including capsaicin, noxious heat, and low pH. Although the behavioral effects of injected capsaicin and the VR1 antagonist capsazepine have indicated a potential role for VR1 in the generation and maintenance of persistent pain states, species differences in the molecular pharmacology of VR1 and a limited number of selective ligands have made VR1 difficult to study in vivo. N-(4-Tertiarybutylphenyl)-4-(3-cholorphyridin-2-yl)tetrahydropryazine-1(2H)-carbox-amide (BCTC) is a recently described inhibitor of capsaicin- and acid-mediated currents at rat VR1. Here, we report the effects of BCTC on acute, inflammatory, and neuropathic pain in rats. Administration of BCTC (30 mg/kg p.o.) significantly reduced both mechanical and thermal hyperalgesia induced by intraplantar injection of 30 micro g of capsaicin. In rats with Freund's complete adjuvantinduced inflammation, BCTC significantly reduced the accompanying thermal and mechanical hyperalgesia (3 mg/kg and 10 mg/kg p.o., respectively). BCTC also reduced mechanical hyperalgesia and tactile allodynia 2 weeks after partial sciatic nerve injury (10 and 30 mg/kg p.o.). BCTC did not affect motor performance on the rotarod after administration of doses up to 50 mg/kg p.o. These data suggest a role for VR1 in persistent and chronic pain arising from inflammation or nerve injury.

[The rat model of erectile dysfunction caused by cavernous nerve injury]

OBJECTIVES

To identify rat cavernous nerve and establish a rat model of erectile dysfunction (ED) caused by injury of cavernous nerve.

METHODS

Twenty rats were undergone dissections. Cavernous nerves were identified with the aid of operating microscope and confirmed by electrical stimulation. Then, 42 experimental rats were randomized into 3 groups, including sham operated controls, unilateral and bilateral cavernous nerve ablation groups. Three weeks after surgery, rat models were evaluated with Apomorphine Test.

RESULTS

The major pelvic ganglion lies on either side of the dorsolateral lobes of the prostate. It includes 2 inflows, one called hypogastric nerve and another is pelvic nerve. The largest outflow is termed as cavernous nerve. Stimulus parameters which could induce obvious penile erection were 5 volts, frequency of 20 Hertz and duration of 5 milliseconds. Three weeks after surgery, apomorphine could induce penile erection of each rat in controls with mean (2.57 +/- 1.40) erections in 30 minutes, while there were no erections (0.00 +/- 0.00) either in unilateral or bilateral group.

CONCLUSIONS

The rat of larger ganglion and its cavernous nerve can be easily identified, obvious response to electrical stimulation, low cost of animal purchase, easy housing and availability made rat as an ideal animal for establishing ED model caused by cavernous nerve injury. In addition, our study showed in the early period of cavernous nerve injury, either unilateral or bilateral, all rats lost their erectile function.

[Morphogenic processes in dosed distraction]

Dosed distraction of bone regenerate is paralleled by distraction of soft tissues (skin, muscles, nerves, etc.), which is particularly obvious during liquidation of medium-sized and extensive mandibular defects. Such distraction of soft tissues leads to their regeneration and growth. However regeneration of soft tissues is paralleled by dystrophic processes, which are never observed in bone regenerate. Dosed distraction can be used in repair of combined bone and soft tissue defects and deformations of the face of different etiology.

Medical and surgical advances in the radical prostatectomy patient

Maintaining the quality of life after surgery in the radical prostatectomy patient is of paramount importance. One of the major dilemmas in surgical management of radical retropubic prostatectomy (RRP) is preservation of the neurovascular bundle and, hence, erectile function and the continence mechanism. This manuscript addresses anatomical considerations for the surgeon and discusses the following issues with regard to medical and surgical therapies: (1) incidence of erectile dysfunction solely due to complications during RRP; (2) nerve damage during RRP; (3) vascular damage during RRP; (4) current medical and surgical therapies for restoring or maintaining potency; and (5) new advances on the horizon for management of the prostatectomy patient. International Journal of Impotence Research (2000) 12, Suppl 4, S47-S52.

Injury-related factors and conditions down-regulate the thrombin receptor (PAR-1) in a human neuronal cell line

Previous studies have demonstrated that thrombin can induce potent effects on neural cell morphology, biochemistry, and viability. Nearly all of these effects are mediated by proteolytic activation of the thrombin receptor (PAR-1). Mechanisms of PAR-1 regulation in several nonneural cell types have been shown to be novel and cell type specific; however, little is known about PAR-1 regulation in neural cells. In the present study, PAR-1 cell surface expression and regulation were examined in a transformed retinoblast (Ad12 HER 10) cell line using radioiodinated anti-PAR-1 monoclonal antibodies ATAP2, which recognizes intact and cleaved receptors, and SPAN12, which is specific for the intact form of the receptor. Scatchard analysis revealed high-affinity, specific binding to a single affinity class of receptors: K(D) = 3.13 and 5.25 nM, Bmax = 190.1 and 67.8 fmol/mg of protein for 125I-ATAP2 and 125I-SPAN12, respectively. Specificity for PAR-1 was confirmed by demonstrating rapid and near complete decreases for both antibodies following treatment with thrombin or PAR-1 activating peptide (SFLLRN). Differential antibody binding was used to demonstrate rapid and near complete thrombin-induced PAR-1 cleavage and internalization, with protein synthesis-dependent replacement of intact receptors occurring over longer time intervals, but only minimal recycling of cleaved receptors. A variety of factors and conditions were screened for their effects on PAR-1 expression. Significant decreases in PAR-1 expression were induced by the protein kinase C activator phorbol 12-myristate 13-acetate (87% at 3 h), the phospholipid inflammatory mediator lysophosphatidic acid (32% at 3 h), and the injury-related condition hypoglycemia (64 and 100% at 24 h in the absence and presence of dibutyryl cyclic AMP, respectively). The effect of hypoglycemia was shown by RNase protection to be at least partially pretranslational. Finally, thrombin's ability to enhance hypoglycemia-induced cell killing correlated temporally with PAR-1 cell surface expression.

Studies of neuroplasticity with transcranial magnetic stimulation

In recent years, there has been increasing interest in studies of brain plasticity. Although still loosely defined, this term describes the ability of the brain to change. Cortical plasticity encompasses a wide variety of phenomena and mechanisms, including modifications in cortical properties such as strength of internal connections, representational patterns, or neuronal modifications, either morphological or functional (Donoghue et al., 1996). We focus on the description of different ways in which transcranial magnetic stimulation (TMS) can be used to study patterns of reorganization and some of the mechanisms involved in these changes. Correlation between TMS and neuroimaging studies in humans and animal studies addressing similar questions is discussed. It is important to identify in each situation whether plasticity plays a beneficial role or is maladaptive in terms of functional compensation. The understanding of patterns, mechanisms, and functional relevance of cortical plasticity will hopefully lead to the design of effective strategies to enhance plasticity when it is beneficial and to down-regulate it when it is maladaptive. An example of a possible strategy, using TMS, is discussed.

The neurotrophins and neuropoietic cytokines: two families of growth factors acting on neural and hematopoietic cells

Recent progress has revealed similarities between the receptors and signaling systems used by neurotrophic factors as compared to other growth factors and cytokines. The neurotrophins use a family of receptor tyrosine kinases known as the Trk receptors, whereas ciliary neurotrophic factor (CNTF) uses a "cytokine receptor" system that shares receptor components with a number of distantly related cytokines. We have used a human embryonal carcinoma cell line and human leukemia cell lines to examine the actions of the neurotrophins and CNTF on cellular differentiation. Our findings demonstrate that specific combinations of neurotrophic factors are required to influence the neuronal progenitor cells to become postmitotic mature CNS neurons. Such synergistic interactions may play an important role in modulating the differentiation of a wide assortment of neuronal precursors in the developing nervous system. Furthermore, our studies with leukemia cells suggest that neurotrophic factors may play a similar role in hematopoietic differentiation and that these factors may have therapeutic application in leukemia differentiation.

Bepridil exacerbates glutamate-induced deterioration of calcium homeostasis and cultured nerve cell injury

Application of 50 microM bepridil (BPD) to cultured nerve cells did not greatly affect the resting cytoplasmic Ca2+ concentration ([Ca2+]i) but caused its pronounced increase both during prolonged glutamate (GLU, 100 microM) treatment and, especially, in the postglutamate period in case of partial [Ca2+]i recovery. In contrast, in cells exhibiting a high [Ca2+]i plateau in the postglutamate period, BPD application either did not cause any additional elevation of [Ca2+]i or caused a very small increase. Under identical conditions replacement of external Na+ by Li+ or N-methyl-D-glucamine (NMDG) either did not change [Ca2+]i or produced a very small increase, strongly indicating that the BPD-evoked Ca2+ responses could not be explained solely by Na+/Ca2+ exchange inhibition but resulted from some other BPD effects. Indeed, in experiments with Rhodamine 123-loaded neurons it has been shown that 50 microM BPD induced prominent mitochondrial depolarization which is known to abolish the mitochondrial Ca2+ uptake. Finally it was revealed that BPD application to the cell culture either in the period of a prolonged (15 min) GLU action or, especially, in the postglutamate period greatly exacerbated delayed neuronal death, apparently due to a complex inhibitory action of the drug on both Ca2+ buffering and Ca2+ extrusion systems.

Activation of metabotropic glutamate receptor subtype mGluR1 contributes to post-traumatic neuronal injury

The role of phospholipase C-coupled (group I) metabotropic glutamate receptors (mGluR1 and mGluR5) in post-traumatic neuronal injury was examined using rat in vivo and in vitro models. Traumatic injury to mixed neuronal/glial cultures induced phosphoinositide hydrolysis and caused neuronal death. Pharmacological blockade of group I receptors significantly reduced these effects in vitro and decreased neurological deficits as well as neuronal loss produced by traumatic brain injury in vivo. In contrast, activation of group I receptors by a specific agonist in vitro exacerbated post-traumatic neuronal death in a dose-dependent manner. Antisense oligodeoxynucleotide directed to mGluR1, but not to mGluR5, was neuroprotective in vitro, although each oligodeoxynucleotide reduced the respective receptor-stimulated accumulation of inositol phosphates to a similar degree. Together, these findings suggest that activation of mGluR1 contributes to post-traumatic neuronal injury and that mGluR1 antagonists may have therapeutic potential in brain injury.

Isolated injury to a major branch of the posterior interosseous nerve of the forearm with surgical repair

We report the case of a patient who sustained an isolated injury to one of the two main branches of the posterior interosseous nerve of the forearm. Repair by epineurial suture was followed by complete recovery.

Trophic factor response to neuronal stimuli or injury

Neurotrophic factors are produced by CNS neurons, and have both paracrine and autocrine activities. In nerve cells, expression of neurotrophic factors is regulated by physiological afferent activity, which implies that these factors play a role in activity-dependent plasticity and survival. Neurotrophic factor levels are also altered following injury, which suggests that they play a part in the neurodegenerative response and synaptic reorganization as well. Recent studies have examined extensively the regulation and functional roles of the neurotrophin family, and have also identified other neurotrophic factors present in brain that are regulated by different, as well as similar mechanisms.

[Significance of magnetic resonance imaging in diffuse axonal injury]

Advantages of magnetic resonance imaging (MRI) to computed tomography (CT) on a diagnosis of diffuse axonal injury (DAI) were discussed. Sixteen patients diagnosed as DAI defined by the criteria of Gennarelli were studied with CT and MRI. Lesions were demonstrated as high intensity areas on MRI of T2 weighted imaging (SE 2000/111) in all of the patients. These lesions were located only in a cerebral white matter in the cases of mild DAI, whereas in the cases of severe DAI located in a basal ganglia, corpus callosum, dorsal part of the brain stem as well as in the cerebral white matter. As for the findings of CT, these parenchymal lesions were not visualized in nine cases including six cases without any pathological findings. Our series suggest that MRI is superior to CT on the diagnosis of DAI and provides some information to evaluate the severity of DAI.

Traumatic neuronal injury in vitro is attenuated by NMDA antagonists

Pure traumatic neuronal injury was modeled in dispersed neocortical cell cultures derived from fetal mice. A plastic stylet was used to tear the neuronal and glial cell layer; medium oxygen content, pH, and glucose remained unchanged. Adjacent to this local disruption, many neurons developed acute swelling and went on to degenerate over the next day, but glia were relatively spared. If the same mechanical insult was delivered in the presence of the N-methyl-D-aspartate (NMDA) antagonists dextrorphan or D-2-amino-5-phosphonovalerate, resultant neuronal degeneration was markedly reduced. The protective effect of these NMDA antagonists was concentration-dependent between 1 and 100 microM, with EC50 near 10 microM for both compounds. Present findings suggest that endogenous excitatory amino acids may participate significantly in the propagation of central neuronal cell loss in response to a purely mechanical insult.

Causes of neurologic deterioration following surgical treatment of cervical myelopathy

Neurologic deterioration was analyzed in 110 patients with surgically treated cervical myelopathy secondary to soft disc hernia or spondylosis. Follow-up periods ranged from 2 to 14 years, with an average of 6 years. Of 110 patients, 29 suffered neurologic deterioration. In most of the patients, deterioration occurred within the first year after surgery. Causes of deterioration were divided into three categories: direct trauma to neural tissue during surgery (a preventable complication); instability of the spine, progression of spondylotic changes above or below the level of fusion, and non-union (apparently unpreventable but treatable); and nonsurgery-related accidental trauma (unavoidable and often irreversible). Countermeasures for the deterioration are discussed.

[Soft tissue injuries of the shoulder joint]

In contrast to rare occurrence of blood vessel and nerve injuries the frequency of tendinous lesions of the shoulder is high. The clinical diagnosis of the ruptured tendon of the M. biceps brachii is obvious. On the other hand only arthrography or arthroscopy can verify the diagnosis of a ruptured supraspinatus tendon. The best access for tenosuture and tenoplasty of the latter is the transacromeal method.

Hand injuries and disorders. Principles of management for the family physician

Hand injuries and disorders constitute a major cause of disability and time lost from work. Viewed as relatively minor, they are often neglected until permanent disability and restriction of function occur. The first physician to evaluate and treat an injured hand often determines the ultimate outcome of the patient's hand function. Skillful diagnosis and appropriate treatment are necessary. Neglected or mistreated injury may result in significant impairment in a person whose livelihood depends on the skillful, integrated function of both hands.