αN-catenin expression in the normal and regenerating chick sciatic nerve

Summary The Ca²⁺-dependent intercellular adhesion molecule cadherin is known to be linked to the cytoskeleton by the protein catenin, an association of which appears to be important for the cell-adhesion function of cadherin. Catenin consists of three subtypes-, , and . In our previous study, N-cadherin was shown to be localized on the plasmalemma of normal and regenerating chick peripheral nerve. Thus, as N-catenin is a subtype of -catenin (which is specifically associated with N-cadherin), we investigated the immunolocalization of N-catenin in normal and regenerating chick sciatic nerve. In normal nerve, unmyelinated axons exhibited either intense or weak N-catenin immunoreactivity throughout the axoplasm, whereas myelinated axons were completely immunonegative. Regenerating axons, including those derived from parent myelinated axons, showed N-catenin immunoreactivity of variable intensities in growth cones and axon shafts. Schwann cells were invariably devoid of immunoreactivity. Thus N-catenin is not necessarily bound to the surface plasmalemma, but is distributed throughout the cytoplasm, suggesting that most N-catenin molecules are dissociated from N-cadherin.     

Is the cranial accessory nerve really a portion of the accessory nerve? Anatomy of the cranial nerves in the jugular foramen

The accessory nerve is traditionally described as having both spinal and cranial roots, with the spinal root originating from the upper cervical segments of the spinal cord and the cranial root originating from the dorsolateral surface of the medulla oblongata. The spinal rootlets and cranial rootlets converge either before entering the jugular foramen or within it. In a recent report, this conventional view has been challenged by finding no cranial contribution to the accessory nerve. The present study was undertaken to re-examine the accessory and vagus nerves within the cranium and jugular foramen, with particular emphasis on the components of the accessory nerve. These nerves were traced from their rootlets attaching to the spinal cord and the medulla and then through the jugular foramen. The jugular foramen was exposed by removing the dural covering and surrounding bone. A surgical dissecting microscope was used to trace the roots of the glossopharyngeal nerve (CN IX), vagus nerve (CN X) and accessory nerve (CN XI) before they entered the jugular foramen and during their travel through it. The present study demonstrates that the accessory nerve exists in two forms within the cranial cavity. In the majority of cases (11 of 12), CN XI originated from the spinal cord with no distinct contribution from the medulla. However, in one of 12 cases, a small but distinct connection was seen between the vagus and the spinal accessory nerves within the jugular foramen.     

Early manifestations of pancreatic cancer: The effect of cancer–nerve interaction

Clinical manifestation is important for the diagnosis of pancreatic cancer (PanCa). No typical symptoms have been identified that clearly indicate the early stage of PanCa, although most patients with PanCa have symptoms before the cancer is diagnosed. These symptoms are often regarded as common gastrointestinal symptoms and are ignored. The pancreas is richly supplied with nerves, and neuro-cancer interactions begin prior to PanCa cell migration. We hypothesise that the cancer–nerve interaction does generate typical symptoms such as pseudomorphous satiety and mild pain in early PanCa. Constant satiety leads to weight loss. This biological behaviour allows the cancer to progress without attention from the cancer-bearing host. Cancer cells also target the endocrine pancreas, generating a hyperglycaemic state that results in increased energy for cancer cells. The combination of the so-called common gastrointestinal symptoms and diabetes may represent early typical symptoms of PanCa that can be used to improve early diagnosis.     

Masseteric nerve: A possible donor for facial nerve anastomosis?

In the medical treatment of facial nerve paralysis a large number of different techniques have been developed to restore the function of the facial nerve. These include (a) the ipsilateral nerve grafting (e.g., partial hypoglossal-facial, spinal accessory-facial, partial glossopharyngeal-facial), (b) crossfacial nerve grafting and (c) temporal muscle flaps or even free muscle transfers. None of these techniques uses the masseteric nerve as a graft for reconstruction of the facial nerve. This preliminary report deals with the anatomical basis, which could lead to a new technique. The masseteric nerve leaves the infratemporal fossa through the mandibular notch, accompanied by the masseteric artery. At this level the nerve consists in nine of 36 cases studied of only one branch (25.0%), in 17 cases of two branches (47.0%), in nine cases of three (25.0%), and in the remaining case of four branches (2.8%). There are three main reasons for considering the masseteric nerve as a possible donor for at least the orbicular branch of the facial nerve: (1) The approach to the mandibular notch is quite simple; (2) since the nerve consists of two or more branches in 75.0% of the cases, severe dysfunction of the masseter muscle should not occur; (3) if there is complete denervation of the masseter muscle, its function may be taken over by the temporalis muscle. Clin. Anat. 11:396–400, 1998. © 1998 Wiley-Liss, Inc.     

Strategies for inducing the formation of bands of Büngner in peripheral nerve regeneration

Peripheral human nerves fail to regenerate across longer tube implants (>2 cm), most likely because implants lack the microarchitecture of native nerves, including bands of Büngner. Bands of Büngner comprise longitudinally aligned Schwann cell strands that guide selectively regrowing axons. We aim to optimize tubular implants by integrating artificial bands of Büngner. Three principle strategies for inducing the formation of bands of Büngner were investigated: (a) an aligned extracellular matrix, (b) polarizing differentiation factors, and (c) microstructured biomaterial filaments. In vitro oriented collagen and a combination of differentiation factors (NGF, neuregulin-1, TGF-β) induced Schwann cell alignment to some extent. The most pronounced Schwann cell alignment was evident on ultrathin, endless poly-?-caprolactone (PCL) filaments with longitudinal microgrooves. Precoated PCL filaments proved to be non-cytotoxic, displayed good cell attachment, and supported Schwann cell proliferation as well as guided axonal outgrowth. In vitro on PCL filaments Schwann cells displayed a polarized expression of the cell adhesion molecule L1 similar to that seen in vivo in bands of Büngner after sciatic nerve crush in adult rats. In summary, the integration of bioengineered bands of Büngner based on microstructured polymer filaments in nerve conduits promises to be the most valuable approach to initiating a more efficient regeneration across longer nerve lesions.     

A case of Sjögren's syndrome presenting as trigeminal nerve palsy

We herein report the case of a female with Sjogren's syndrome (SS) complicated with trigeminal nerve palsy. Although her sicca symptoms had been unnoticed, head magnetic resonance imaging (MRI) for detecting brain abnormalities revealed parotid gland changes associated with SS. SS should be considerd as a possible cause of trigeminal nerve disturbances. In addition, parotid gland changes related to SS should be aware in examination of cranial nerve disturbances with MRI.     

Morphometric study of Intratemporal course of facial nerve in relation to pneumatization of temporal bone—An original study

Introduction

Facial nerve (C.N VII) is the nerve of facial expression and communication. The intratemporal part of this nerve comprising tympanic and mastoid segments, is very vulnerable to injury during ear surgeries. Hence to safely navigate around this part of the nerve one has to be very familiar with 3D anatomy of the temporal bone and crucial landmarks present in relation to the nerve. Aim of this study is to know the exact morphometry of Intratemporal part of the facial nerve in relation to Pneumatization of temporal bone.

Selective stimulation of smaller nerve fibers by single electrode using Biphasic Rectangular Pulses

INTRODUCTION　　Selectivestimulationofsmallernervefibersinacompoundnervetrunkisanim-portantprobleminFunctionalElectricalStimulation(FES)ofthemotorsysteminpatientshavinguppermotorneuroninjures.Undernormalphysiologicalconditions,theneverfibersinacompoundner…     

Interleukin-1β of Red nucleus involved in the development of allodynia in spared nerve injury rats

Previous studies have indicated that interleukin-1β (IL-1β) is involved not only in immune modulation, but also in the modulation of pain in both the peripheral and central nervous systems. The current study investigated the expression of IL-1β in the brain of rats with spared nerve injury (SNI), using immunohistochemical technique. The results showed that immunoreactive-like IL-1β protein was significantly elevated in the Red nucleus (RN) 2 weeks after SNI. To further study the function of IL-1β in RN, different doses of IL-1β neutralizing antibody (10, 1.0 and 0.1 ng) were microinjected into the RN contralateral to the nerve injury side of neuropathic rats. The results indicated that the higher doses of anti-IL-1β antibody (10 and 1.0 ng) significantly attenuated the mechanical allodynia of neuropathic rats. However, administration of 0.1 ng anti-IL-1β antibody did not show anti-allodynia effect. These results suggest that IL-1β of RN is involved in the development of neuropathic pain in SNI rats.     

Anatomy of right recurrent nerve node: why does early metastasis of esophageal cancer occur in it?

Early, distant and/or skip metastasis of squamous-cell thoracic esophageal cancer frequently occurs in the right recurrent nerve node (recR). However, the specific lymphatic route without a nodal relay, such as the submucosal ascending route, was not known for the recR afferent. Using 20 donated cadavers, macroscopic, and histological observations were performed on the recR and its surrounding lymphatics, especially afferent routes from the esophagus to the recR. Most afferent vessels of the recR originated from the right paratracheal node. However, the recR often (12/20) received a major submucosal lymphatic drainage route ascending along the thoracic esophagus. The submucosal vessel came out of the esophagus and ran in a longitudinal connective tissue mass along the right tracheo-esophageal groove. A direct drainage route was often (13/20) seen from the recR to the venous system. Moreover, because of the specific histology, collaterals seemed to be present around the recR. In the regional nodes of the intrathoracic esophagus, the recR histology was characterized by the high proportion of lymphocyte accumulating areas or the cortex. From the midthoracic level, metastatic cancer cells seemed to reach the recR via esophageal submucosal vessels in the early stage. Large lymphocyte accumulating areas of the recR suggested higher filtration capacity than other distal nodes. However, the collateral of the recR and its direct drainage to the venous system suggested that the recR involvement often corresponds to a systemic disease.     

Does the motor branch of the long head of the triceps brachii arise from the radial nerve?

Anatomy textbooks say that the motor branch of the long head of the triceps brachii (LHT) arises from the radial nerve. Some clinical observations of traumatic injuries of the axillary nerve with associated paralysis of the LHT have suggested that the motor branch of the LHT may arise from the axillary nerve. This anatomic study was performed, using both cadaver anatomical dissections and a surgical study, to determine the exact origin of the motor branch of the LHT. From the adult cadaver specimens (group I), 20 posterior cords were dissected from 10 subjects (eight embalmed, two fresh) using 3.5× magnification. The axillary nerve was followed from its onset to the posteromedial part of the surgical neck of the humerus and the radial nerve. We looked for the origin of the proximal branch of the LHT by a meticulous double anterior and posterior dissection. From the surgical group (group II), 15 posterior cords were dissected from 15 patients suffering from a C5-C6 injured paralysis, without paralysis of the LHT. During the surgical procedure, we looked for the origins of the motor branch of the LHT with a nerve stimulator. In group I, the motor branch of the LHT arose in 13 cases from the axillary nerve near its origin, in five cases from the terminal division of the posterior cord itself, and in two cases from the posterior cord 10 mm before its terminal division into the radial and axillary nerves. In no case did we find the motor branch of the LHT arising from the radial nerve. In eight cases, we found some accessory branches that arose near the principal branch. In group II, the motor branch of the LHT arose in 11 cases from the axillary nerve near its origin and in four cases from the terminal division of the posterior cord itself. The motor branch of the LHT never originated from the radial nerve. In four cases, we found some accessory branches that arose near the principal branch of the LHT. These results reveal that the motor branch of the LHT seems to originate most often from the axillary nerve. This contribution could be relevant for surgical treatment of traumatic nerve injuries.     

A recurrent variant branch of the inferior alveolar nerve: Is it unique?

The only named branch of the inferior alveolar nerve (IAN) before it enters the mandibular foramen is the mylohyoid nerve. However, several variations have been reported in the literature. In this study, a recurrent variant branch of the IAN arising just below the origin of the mylohyoid nerve was investigated in adult Indian cadavers allotted for dissection to the first year dental students of Government Dental College, Ahmedabad (India). The dissection was performed by the lateral approach to the infratemporal fossa. The nerve was found in 12 of 35 sides (34.3%) and 8 of 18 cadavers (44.4%). Thus, in our study it was not a rare variation of the IAN, where in most cases it innervated the lateral pterygoid muscle. In some cases, it terminated in the lateral pterygoid muscle. In others, it penetrated the muscle to join the anterior or posterior division of the mandibular nerve or its branches; thus, the variant nerve in such cases might be regarded as an additional root of the IAN. Because the concerned primordia of the nerves and muscles migrate extensively during development and growth, alternative routes of migration may bring about variants like the one under study. The variant appeared to be unique in some of its features. It may be a source of neuropathic and referred pain. Failure of the conventional inferior alveolar nerve block anesthesia and the peripheral neurectomy used for the treatment of trigeminal neuralgia may be partly due to the presence of this variation.     

Copolymers of trimethylene carbonate and ε-caprolactone for porous nerve guides: Synthesis and properties

Copolymers of trimethylene carbonate and ε-caprolactone were synthesized and characterized with the aim of assessing their potential in the development of a flexible and slowly degrading artificial nerve guide for the bridging of large nerve defects. The effect of the monomer ratio on the physical properties of the polymers and its influence on the processability of the materials was investigated. Under the applied polymerization conditions (130°C, 3 days using stannous octoate as a catalyst) high molecular weight polymers (Mn above 93 000) were obtained. All copolymers had glass transition temperatures below room temperature. At trimethylene carbonate contents higher than 25 mol% no crystallinity was detected. A decrease in crystallinity resulted in the loss of strength and decrease in toughness, as well as in an increased polymer wettability. Amorphous poly(trimethylene carbonate), however, showed excellent ultimate mechanical properties due to strain-induced crystallization (T_m = 36°C). Low crystallinity copolymers could be processed into dimensionally stable porous structures by means of immersion precipitation and by combination of this technique with the use of porosifying agents. Porous membranes of poly(trimethylene carbonate) could be prepared when blended with small amounts of high molecular weight poly(ethylene oxide). Poly(trimethylene carbonate) and poly(trimethylene carbonate-co-ε-caprolactone) copolymers with high ε-caprolactone content possess good physical properties and are processable into porous structures. These materials are most suitable for the preparation of porous artificial nerve guides.     

A study on peripheral nerve regeneration via biomimetic conduits loadedwith Schwann cells and nerve growth factor

Guided tissue regeneration is a new approach in the reconstructive surgery of pe-ripheral nerves. Biomimetic conducts were construct from the expanded vein onwhose inner surface composited with amnion filaments( cf.Fig1 ) .F ig.1　 The Scheme of biomim etic conduit1 .Proximal nerve2 . Nerve growth factor ( NGF)3.Schwann cell( SC)4 . Amnion filaments with 1 mm in width and 1 5mm in length5.The expanded vein( V) with1 8mm in length6. Distal nerve　　 Conduit made from( 1 ) the expanded vei…