Endoneurial Capillaries Research Articles

Abstract P5-07-14: A pilot study of novel approach of intraneural facilitation versus standard physical therapy for prevention of chemotherapy induced peripheral neuropathy

Abstract Background Chemotherapy-induced peripheral neuropathy (CIPN) is a frequent side effect of commonly used chemotherapy (CT) regimens and often results in dose reduction or cessation of treatment which can adversely affect cancer outcomes. Treatment options for CIPN are limited and no standard approaches exist to prevent CIPN. A novel therapy, Intraneural Facilitation (INF) has been developed by physical therapists at our institution’s neuropathy treatment center as a preventative and treatment modality for CIPN. INF therapy involves physical maneuvers and systematic application of pressure to improve peripheral microvascular circulation to the endoneurial capillaries of the extremities. We conducted a randomized pilot study evaluating INF versus standard physical therapy (PT) maneuvers as a non-invasive treatment modality for preventing CIPN during participants’ ongoing chemotherapy. This study was supported by an intramural (GRASP) grant and registered on clinicaltrials.gov (NCT0327919). Methods Newly diagnosed patients with breast cancer stages I to III and CT naive gynecologic cancers without preexisting peripheral neuropathy planning to receive treatment with platinum-based compounds and/or taxanes were eligible for this study. Participants were randomized into two treatment groups. Group one received INF and group two received a standardized program of PT including muscle stretching and strengthening exercises. Each group received two (45-minute) treatments twice a week for six weeks under the supervision of trained physical therapists. Participants were evaluated at baseline, week 3, week 6, and 3 months after the date of initiation of chemotherapy. The use of neuropathy medications, CT dose reductions, and treatment discontinuation was compared between the two treatment groups. Vascular perfusion was also evaluated at the same intervals using ultrasound to measure volume flow and pulsatility of the popliteal and posterior tibial arteries. Participants completed a survey at the end of treatment evaluating the effectiveness and satisfaction of the intervention. Results 44 out of 104 patients screened met the eligibility criteria and were randomized to either of the two therapy modalities from July 2017 to June 2022. A total of 38 participants received the allocated intervention and were included in the analysis (n=20 in the INF arm and n=18 in the PT arm). CT dose reduction due to CIPN grade 2 or higher occurred in 6/18 (33%) and 4/20 (20%) participants who received standard PT and INF, respectively. 2/18 (11%) participants required discontinuation of CT prematurely due to CIPN in the standard PT arm when compared to 1/20 (5.0%) in the INF arm. Pharmacologic interventions were required to manage CIPN in 4/18 (22%) participants in the standard PT arm vs 2/20 (10%) in the INF arm at the end of CT. Participants reported more control over their health (95.2% INF arm vs. 83.3% PT arm) and decreased nerve discomfort (75% in the INF arm vs. 61.1% in the PT arm). Participants reported high levels of satisfaction overall at the end of each intervention (95% in the INF arm vs. 83% in the PT arm). Conclusion Our pilot study evaluated the feasibility and potential for INF therapy compared to standard PT for the prevention of CIPN during ongoing chemotherapy. Based on the patient satisfaction survey, the burden and satisfaction with the assigned therapy modality between the two arms were favorable overall. Our results showed that CT dose reduction and early cessation in addition to pharmacologic interventions for CIPN were numerically less prevalent in the INF arm compared to the standard PT arm; however, further studies are needed to validate these findings. Citation Format: Dani Ran Castillo, Won Jin Jeon, Carvy Floyd Luceno, Mark Bussell, Ron Coleman, Karla Pieters, Jamie Hankins, Annette Boggs, Lorena Garcia, Salem Dehom, Ellen D’Errico, Gayathri Nagaraj. A pilot study of novel approach of intraneural facilitation versus standard physical therapy for prevention of chemotherapy induced peripheral neuropathy [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P5-07-14.

Structure and barrier functions of the perineurium and its relationship with associated sensory corpuscles: A review.

Peripheral nerves are provided with a blood-nerve barrier which prevents the invasion of harmful substances and pathogens, and also regulates metabolic and ionic homeostasis within nerve fascicles. The barrier functions are attributed to both the concentric layer of flattened cells in the perineurium and blood vessels running in the endoneurium. The perineurial cells develop continuous tight junctions as a diffusion barrier. In order to take up a predominant nutrient, glucose, the perineurium as well as endoneurial capillaries expresses GLUT1, a glucose transporter. An axon-Schwann cell complex within peripheral nerves utilizes glucose as a major energy source via the GLUT1, as does the brain. Under conditions of a reduced utilization of glucose, only the perineurial cells can transfer other nutrients, namely monocarboxylates such as ketone bodies and lactate via MCT1. Thus, MCT1 colocalizes with GLUT1 in the perineurium but not in endoneurial capillaries. To identify the cellular origins of the nerve sheath, marker proteins such as glial specific S100 protein, GLUT1, endoneurial CD34, and EMA (epithelial membrane antigen) are useful. Immunohistochemical findings for these markers are reviewed in this paper, focusing on the perineurium and endoneurium and their derivatives, Pacinian and Meissner corpuscles. Growing evidence throws light on the critical involvement of the nerve sheaths in the development, maintenance, and diseases of peripheral nerves.

Гистоморфометрические характеристики передней большеберцовой мышцы и малоберцового нерва при экспериментальном замещении пострезекционного дефекта голени аппаратом Илизарова в комбинации с методом Masquelet

Objective Explore structural changes in the tibialis anterior muscle (TAM) and the peroneal nerve (PN) in repair of postresection tibial defect using the Ilizarov external fixation and a cement spacer. Material and methods A defect-nonunion was simulated in the proximal tibia of 10 mongrels using the Ilizarov external fixation followed by use of a cement spacer to fill the 2.5 cm defect-diastasis. The spacer was removed after 30 days and tibia distraction commenced with the rate of 1 mm performed 4 times/day following transverse osteotomy in the distal tibia to achieve docking of bone fragments. Animals were sacrificed after 60-day fixation (F60) and 30 days after frame removal (FR30). Histomorphometric parameters of the TAM and PN samples were examined. Results TAM appeared to be denervated with death or decreased size of myons and angular contours noted at F60 and FR30. Degenerated and intact muscle fibers (MF) were shown to increase by 32.5 % and by 1 %, respectively, at FR30. The peak of histogram distributing MF by diameters at F60 indicated to ischemic muscles, and a 2-fold decrease in muscle diameter and the histogram skewed to the left by 4 classes showed increase in muscle atrophy at FR30. Reactive destructive changes were noted in at least 5.4 % of myelinated nerve fibres of the PN at F60 and FR30. A 1.6-to-1.7 times decrease in larger and a 1.6-to-1.8 times increase in smaller fibers, the presence of regenerative clusters indicated to previous destruction of a large number of motor and sensory nerves. Changes in the population structure, destruction of myelinated fibers and loss of non-myelinated fibers were associated with obliteration of epineurial vessels and loss of endoneurial capillaries at F60. Conclusion Reactive destructive changes in the TAM and PN revealed in bone defects repaired with the Ilizarov external fixation and the Masquelet technique should be considered in planning of postoperative pharmacologic thearapy and rehabilitation.

Vasa nervorum angiogenesis in prostate cancer with perineural invasion.

Perineural invasion (PNI) is generally accepted as a major route of cancer dissemination in malignancies associated with highly enervated organs. However, the effect of cancer cells on vasa nervorum remains unknown. We studied this effect in locally advanced prostate cancer, a high-risk feature associated with approximately 20% of prostate cancer specific mortality. We used immunohistochemistry for CD34, fibroblast growth factor-2 (FGF-2), FSHR, podoplanin, vascular endothelial growth factor (VEGF), and VEGFR-2 as well as histochemical methods to examine the vasa nervorum of nerves invaded by cancer cells in tissue samples from 85 patients. The percentage of the nerve area occupied by CD34-positive vasa nervorum endothelial cells in nerves with PNI was much higher than in nerves without PNI (7.3 ± 1.2 vs 1.9 ± 0.4; P < 0.001 and 5.8 ± 0.6 vs 1.23 ± 0.8; P < 0.001 in pT3a and pT3b prostate cancer specimens, respectively). In 19/85 of the patients the CD34-positive vasa nervorum microvessels have a thick basement membrane, similar to the vessels in diabetic microangiopathy. This subendothelial layer contains collagen fibers. Vasa nervorum endothelia and Schwann cells express FGF-2 (nuclear localization) and FSHR (plasma membrane and cytoplasmic staining). Prostate cancer cells invading nerves express VEGF, a critical cytokine in tumor angiogenesis. The vasa nervorum of prostatic nerves with PNI did not express detectable levels of VEGFR-2. No podoplanin-positive lymphatic vessels were seen in nerves. In locally advanced prostate cancer, PNI of cancer cells is associated with formation of new endoneurial capillaries and changes of vasa nervorum morphology.

Longitudinal study of neuropathy, microangiopathy, and autophagy in sural nerve: Implications for diabetic neuropathy.

ObjectivesThe progression and pathophysiology of neuropathy in impaired glucose tolerance (IGT) and type 2 diabetes (T2DM) is poorly understood, especially in relation to autophagy. This study was designed to assess whether the presence of autophagy‐related structures was associated with sural nerve fiber pathology, and to investigate if endoneurial capillary pathology could predict the development of T2DM and neuropathy.Patients and MethodsSural nerve physiology and ultrastructural morphology were studied at baseline and 11 years later in subjects with normal glucose tolerance (NGT), IGT, and T2DM.ResultsSubjects with T2DM had significantly lower sural nerve amplitude compared to subjects with NGT and IGT at baseline. Myelinated and unmyelinated fiber, endoneurial capillary morphology, and the presence and distribution of autophagy structures were comparable between groups at baseline, except for a smaller myelinated axon diameter in subjects with T2DM and IGT compared to NGT. The baseline values of the subjects with NGT and IGT who converted to T2DM 11 years later demonstrated healthy smaller endoneurial capillary and higher g‐ratio versus subjects who remained NGT. At follow‐up, T2DM showed a reduction in nerve conduction, amplitude, myelinated fiber density, unmyelinated axon diameter, and autophagy structures in myelinated axons. Endothelial cell area and total diffusion barrier was increased versus baseline.ConclusionsWe conclude that small healthy endoneurial capillary may presage the development of T2DM and neuropathy. Autophagy occurs in human sural nerves and can be affected by T2DM. Further studies are warranted to understand the role of autophagy in diabetic neuropathy.

Impaired Hedgehog signalling-induced endothelial dysfunction is sufficient to induce neuropathy: implication in diabetes.

Microangiopathy, i.e. endothelial dysfunction, has long been suggested to contribute to the development of diabetic neuropathy, although this has never been fully verified. In the present paper, we have identified the role of Hedgehog (Hh) signalling in endoneurial microvessel integrity and evaluated the impact of impaired Hh signalling in endothelial cells (ECs) on nerve function. By using Desert Hedgehog (Dhh)-deficient mice, we have revealed, that in the absence of Dhh, endoneurial capillaries are abnormally dense and permeable. Furthermore, Smoothened (Smo) conditional KO mice clarified that this increased vessel permeability is specifically due to impaired Hh signalling in ECs and is associated with a down-regulation of Claudin5 (Cldn5). Moreover, impairment of Hh signalling in ECs was sufficient to induce hypoalgesia and neuropathic pain. Finally in Lepr(db/db) type 2 diabetic mice, the loss of Dhh expression observed in the nerve was shown to be associated with increased endoneurial capillary permeability and decreased Cldn5 expression. Conversely, systemic administration of the Smo agonist SAG increased Cldn5 expression, decreased endoneurial capillary permeability, and restored thermal algesia to diabetic mice, demonstrating that loss of Dhh expression is crucial in the development of diabetic neuropathy. The present work demonstrates the critical role of Dhh in maintaining blood nerve barrier integrity and demonstrates for the first time that endothelial dysfunction is sufficient to induce neuropathy.

Cochleotopy of human cochlear nucleus

IntroductionThe human peripheral auditory pathway in infants is a relatively less explored domain in auditory research. In the present study, the cochlea, auditory nerve (AN) and the cochlear nucleus (CN) were examined using immunohistochemistry and light and electron-microscopy. MethodsThe study was performed on specimens retrieved from a 40-day-old infant who could not survive after corrective surgery for congenital cyanotic heart disease. The donation was done in accordance with the protocol approved by the Human Ethics Committee, All India Institute of Medical Sciences (AIIMS), New Delhi, India. ResultsThe AN revealed degeneration of nerve fascicles originating from the spiral ganglion neurons of the middle and basal turns of the cochlea. The proximal and middle segments of the nerve showed varying degrees of degenerating fibers with macrophages whereas the most distal part of the nerve showed dilated endoneurial capillaries without any degeneration. On electron-microscopy, the nerve revealed features of acute myelinopathy. The differential perisomatic synaptophysin immunoreactivity was observed in the CN. The unaffected neurons showed strong microtubule-associated protein 2 (MAP-2) immunoreactivity, while those denervated revealed decreased staining. The VCN showed varying degree of parvalbumin (PV) and calbindin (CB) immunostaining with AN fibers and terminals showing strong immunoreactivity for PV. The AN revealed strong immunoreactivity for CB on the affected side. The spiral ganglion neurons did not reveal any pathological changes. DiscussionThe results provide a cochleotopic map of the human CN that maybe relevant in better understanding of the tonotopic organization and will be helpful during auditory implants in children.

Familial amyloid polyneuropathy: A clinico-pathologic study

In familial amyloid polyneuropathy (FAP), destruction of nerve fibres is related to accumulation of mutated transthyretin (mTTR) derived amyloid deposits (AD) in the endoneurium. Liver transplantation (LT), which removes the main source of mTTR, does not prevent deterioration of the clinical condition in all recipients. Material and methodsWe evaluated the distribution of AD in the central and peripheral nervous system in order to better understand the pathophysiology of FAP and the potential role of lesions of nerve blood vessels and of mTTR released by choroid plexuses (CP). Forty nerve biopsy specimens and 3 autopsy cases, including 7 patients who underwent liver transplantation, all from patients with symptomatic FAP and DNA mutation of the TTR gene, were included. ResultsPatients were ranged into three categories:Group 1:Patients with early neuropathic manifestations. Five patients carrying an amyloidogenic mutation closely followed to detect early neuropathic manifestations experienced paresthesiae with stockings temperature and pains deficit in two; uncertain changes in the others. Sensory nerve action potentials (SNAPs) were normal. Biopsy was performed to detect morphological changes as an indication for early therapeutic intervention. Only one patient had decreased MF and unmyelinated fiber (UF) density.Group 2:Patients with marked sensory-motor and dysautonomic polyneuropathy (35 patients). Non dissociated sensory loss prevailed in distal limbs, while sensory defect predominated on temperature and pain sensations in proximal limbs and anterior trunk. Weakness and amyotrophy predominated in distal lower limbs. Fiber loss massively predominated on UF.Group 3:Patients at terminal stage of the disease. All 3 patients had been bedbound for months with flaccid quadriplegia and non dissociated sensory deficit affecting all four limbs, up to proximal thighs, arms and anterior trunk along with severe autonomic dysfunction. There was virtually no surviving nerve fibers in distal nerves. Morphological changesAmyloid predominated around endoneurial capillaries in 37 patients, with occlusion/destruction of endoneurial capillaries in 15 nerves at late stages of the disease. Post-mortem examination showed amyloid in choroid plexuses and perivascular spaces in the brain and around blood vessels penetrating the endoneurium, following arachnoid and connective tissue septae. Destruction of endoneurial blood vessels is a late event in the natural course of FAP. Morphological findings were similar in patients who underwent liver transplantation and in those who did not. The distribution of amyloid in areas communicating with the subarachnoid space suggests that mutated TTR released in the CSF may move to the endoneurial fluid and accumulate in peripheral nerves, accounting for lack of efficacy of liver transplantation in some individuals.

Severe acute multineuropathy in Churg-Strauss syndrome in a patient with a history of melanoma

We describe the clinicopathologic features of a 69-year-old man affected with acute onset Churg-Strauss syndrome with major peripheral nerve involvement. At admission the patient presented a one-week history of distal upper-limb asymmetrical paresthesias. Asthma had been present since the age of 55 and treated with leukotriene receptor antagonists (LTAs, Montelukast) for a few years. Multiple pulmonary infiltrates had been diagnosed during follow-up for melanoma. During hospitalization he showed rapidly progressive weakness worsening within a few hours; cerebrospinal fluid analysis, cervical MRI, head CT scan, nerve conduction studies and peripheral nerve and skeletal muscle biopsies were performed. Blood analysis showed leukocytosis and marked eosinophilia; p-ANCA were positive. Sural nerve biopsy showed a marked loss of myelinated fibers, thrombosed vessels surrounded by mononuclear and eosinophilic cells, necrotizing and hyaline degeneration. Eosinophilic infiltrates were shown in May-Grunwald-Giemsa stained sections. The eosinophils mostly occupied the outer zone of the adventitia at the margin of the active lesion. Perivascular cellular infiltrates within the epineurium were immunoreactive for T-lymphocytes and macrophages. Strong HLA-DR immunostaining was present in the perineurium and membrane attack complex deposition was present in a few endoneurial capillaries. Muscle biopsy showed neurogenic changes and one vessel surrounded by mononuclear cells. After a few days of corticosteroid therapy leukocytosis and eosinophilia normalized and the patient's clinical features stabilized.

Endoneurial microvascular pathology in feline diabetic neuropathy

Endoneurial capillaries in nerve biopsies from 12 adult diabetic cats with varying degrees of neurological dysfunction were examined for evidence of microvascular pathology and compared to nerves obtained at necropsy from 7 adult non-diabetic cats without clinical evidence of neurological dysfunction. As reported previously [Mizisin, A.P., Nelson, R.W., Sturges, B.K., Vernau, K.M., LeCouteur, R.A., Williams, D.C., Burgers, M.L., Shelton, G.D., 2007. Comparable myelinated nerve pathology in feline and human diabetes mellitus. Acta Neuropathol. 113, 431–442.], the diabetic cats had elevated glycosylated hemoglobin and serum fructosamine levels, decreased motor nerve conduction velocity and compound muscle action potential (CMAP) amplitude, and markedly decreased myelinated nerve fiber densities. Compared to non-diabetic cats, there was a non-significant 26% increase in capillary density and a significant ( P < 0.009) 45% increase in capillary size in diabetic cats. Capillary luminal size was also significantly ( P < 0.001) increased, while an index of vasoconstriction was significantly decreased ( P < 0.001) in diabetic cats compared to non-diabetic controls. No differences in endothelial cell size, endothelial cell number or pericyte size were detected between non-diabetic and diabetic cats. In diabetic cats, basement membrane thickening, seen as a reduplication of the basal lamina, was significantly ( P < 0.0002) increased by 73% compared to non-diabetic controls. Regression analysis of either myelinated nerve fiber density or CMAP amplitude against basement membrane size demonstrated a negative correlation with significant slopes ( P < 0.03 and P < 0.04, respectively). These data demonstrate that myelinated nerve fiber injury in feline diabetic neuropathy is associated with microvascular pathology and that some of these changes parallel those documented in experimental rodent and human diabetic neuropathy.

Nonviral Gene Transfer of Human Hepatocyte Growth Factor Improves Streptozotocin-Induced Diabetic Neuropathy in Rats

Peripheral neuropathy is common and ultimately accounts for significant morbidity in diabetes. Recently, several neurotrophic factors have been used to prevent progression of diabetic neuropathy. In this study, we gave repeated intramuscular injections of the human hepatocyte growth factor (HGF) gene percutaneously, using liposomes containing the hemagglutinating virus of Japan (HVJ), to examine therapeutic efficacy of nonviral gene transfer of HGF for experimental diabetic sensorimotor neuropathy in rats. Experimental diabetes induced by intraperitoneal injection of streptozotocin resulted in a marked tactile allodynia (but not in a thermal hyperalgesia), in a reduction of both the conduction velocity and the amplitude, and in a decreased laser Doppler flux of the nerve and the muscle at 6 weeks after the induction. All these changes were significantly reversed by repeated gene transfer of HGF. Furthermore, we analyzed the density of endoneurial capillaries and morphometrical changes of the nerve. The density of endoneurial capillaries, disclosing marked reduction in diabetic rats, was also reversed significantly by repeated gene transfer of HGF; however, no considerable differences were observed morphometrically in either myelinated or unmyelinated axons. These results suggest that nonviral HVJ liposome-mediated gene transfer of human HGF has potential for the safe effective treatment of diabetic sensorimotor neuropathy.

Sural nerve pathology in diabetic patients with minimal but progressive neuropathy

The early pathological features of human diabetic neuropathy are not clearly defined. Therefore we quantified nerve fibre and microvascular pathology in sural nerve biopsies from diabetic patients with minimal neuropathy. Twelve diabetic patients underwent detailed assessment of neuropathy and fascicular sural nerve biopsy at baseline, with repeat assessment of neuropathy 8.7+/-0.6 years later. At baseline, neuropathic symptoms, neurological deficits, quantitative sensory testing, cardiac autonomic function and peripheral nerve electrophysiology showed minimal abnormality, which deteriorated at follow-up. Myelinated fibre density, fibre and axonal area, and g-ratio were normal but teased fibre studies showed paranodal abnormalities (p<0.001), segmental demyelination (p<0.01) and remyelination (p<0.01) without axonal degeneration. Unassociated Schwann cell profile density (p<0.04) and unmyelinated axon density (p<0.001) were increased and axon diameter was decreased (p<0.007). Endoneurial capillaries demonstrated basement membrane thickening (p<0.006), endothelial cell hyperplasia (p<0.004) and a reduction in luminal area (p<0.007). The early pathological features of human diabetic neuropathy include an abnormality of the myelinated fibre Schwann cell and unmyelinated fibre degeneration with regeneration. These changes are accompanied by a significant endoneurial microangiopathy.

Pathology of lumbar nerve root compression: Part 1: Intraradicular inflammatory changes induced by mechanical compression

Study design: This study is to investigate the intraradicular inflammation induced by mechanical compression using in vivo model. Objectives: The relationship between the intraradicular edema and nerve fiber degeneration induced by mechanical compression was determined in the nerve root. Summary of background data: Recently some studies reported that mechanical compression increased microvascular permeability of the endoneurial capillaries and resulted in an intraradicular inflammation. These changes may be an important factor of the pathogenesis of radiculopathy. However, the natural courses of the intraradicular inflammation after mechanical compression are still poorly understood. Methods: In dogs, laminectomy was performed at L7 and the seventh nerve root was exposed to compression at 7.5 gram force (gf) clipping power. The animals were evaluated at 1 and 3 weeks after clipping. After the appropriate period of nerve root compression, Evans blue albumin (EBA) was injected intravenously. The nerve root sections were divided into two groups. The sections were used to investigate the status of the blood–nerve barrier function under the fluorescence microscope. The other sections were used for light and transmission electron microscopic study. Results: After 1 and 3 weeks, intraradicular edema was observed not only at the site of compression but also in the peripheral zone of a compressed anterior root and in the central zone of a compressed posterior root. The evidence of active Wallerian degeneration was also seen in the area of intraradicular edema. In addition, the nerve roots showing Wallerian degeneration were infiltrated by inflammatory cells, such as macrophages and mast cells. Conclusions: Inflammatory reaction, such as Wallerian degeneration, breakdown of blood–nerve barrier and appearance of macrophage, may be deeply involved in radiculitis arising from mechanical compression, and these factors seem to be important in the manifestation of radiculopathy.

Nerve pathology in the type 1 diabetic dog: effects of treatment with sulindac.

The purpose of this study was to define pathological abnormalities in the peripheral nerve of a large animal model of long-duration type 1 diabetes and also to determine the effects of treatment with sulindac. Detailed morphometric studies were performed to define nerve fiber and endoneurial capillary pathology in 6 control dogs, 6 type 1 diabetic dogs treated with insulin, and 6 type 1 diabetic dogs treated with insulin and sulindac for 4 years. Myelinated fiber and regenerative cluster density showed a non-significant trend toward a reduction in diabetic compared to control animals, which was prevented by treatment with sulindac. Unmyelinated fiber density did not differ among groups. However, diabetic animals showed a non-significant trend toward an increase in axon diameter (p < 0.07), with a shift of the size frequency distribution towards larger axons, which was not prevented by treatment with sulindac. Endoneurial capillary density and luminal area showed a non-significant trend toward an increase in diabetic animals, which was prevented with sulindac treatment. Endoneurial capillary basement membrane area was significantly increased (p < 0.05) in diabetic animals, but was not prevented with sulindac treatment. We conclude that the type 1 diabetic dog demonstrates minor structural abnormalities in the nerve fibers and endoneurial capillaries of the sciatic nerve, and treatment with sulindac ameliorates some but not all of these abnormalities.

Quantitative analysis of edema in the dorsal nerve roots induced by acute mechanical compression.

Edema in the dorsal nerve roots caused by acute compression was assessed quantitatively in the lumbar spine of the adult dog. To establish quantitative evaluation of edema in the dorsal nerve roots and to observe changes after acute compression with time. Mechanical compression induces an increase in microvascular permeability of the endoneurial capillaries and results in intraneural edema. However, there are no quantitative studies on edema in the nerve roots. The seventh lumbar nerve root was compressed with a 60-g force clip for 10 minutes. The nerve roots were removed immediately and at 24 hours, 1 week, and 3 weeks after compression. Nerve roots from the control and the sham groups were also obtained. Before removing the nerve roots, Evans blue albumin was injected intravenously. Changes in edema were examined using fluorescence microscopy. Evans blue albumin emits a bright red fluorescence. The relative red fluorescent area was calculated using computer image analysis, and the data were used to indicate the degree of edema. In the compressed segment, edema was most pronounced just after decompression and reduced in nerves removed at 24 hours. In nerves removed at 1 week, edema was pronounced but was reduced at 3 weeks. In the segments closest to the spinal cord, edema was seen after 1 week and was significant after 3 weeks. In the segments closest to the dorsal root ganglion, edema was not detected at any time. In the dorsal nerve roots the degree and the area of edema changed with time elapsed after acute compression. The degree of edema 24 hours after decompression was one third the degree immediately after decompression. These results show that edema induced by mechanical compression can recover after decompression.

T-cell-mediated epineurial vasculitis and humoral-mediated microangiopathy in cryoglobulinemic neuropathy

We used immunohistochemistry to assess the role of humoral and cellular factors in endoneurial microangiopathy and epineurial vasculitis in 15 nerve biopsies of patients with axonal neuropathy and monoclonal or mixed cryoglobulinemia (CG). Deposition of immunoglobulins and cytolytic complement was detected in endoneurial capillaries of patients with mixed CG. Epineurial inflammatory infiltrates containing β2-integrin-positive lymphocytes and monocytes surrounded arterioles expressing cell adhesion molecules, thus suggesting a cell-mediated pathogenesis of the epineurial vasculitis. On the other hand, the absence of immune complex deposition and polymorphonuclear elements suggests a minor role for the humoral mechanisms in the formation of the vasculitic lesions. This study indicates that both cell-mediated mechanisms and immune complexes/cryoglobulins are involved, although at different levels, in the pathogenesis of CG neuropathy.

Glucose transporters in rat peripheral nerve: Paranodal expression of GLUT1 and GLUT3

Peripheral nerve depends on glucose oxidation to energize the repolarization of excitable axonal membranes following impulse conduction, hence requiring high-energy demands by the axon at the node of Ranvier. To enter the axon at this site, glucose must be transported from the endoneurial space across Schwann cell plasma membranes and the axolemma. Such transport is likely to be mediated by facilitative glucose transporters. Although immunohistochemical studies of peripheral nerves have detected high levels of the transporter GLUT1 in endoneurial capillaries and perineurium, localization of glucose transporters to Schwann cells or peripheral axons in vivo has not been documented. In this study, we demonstrate that the GLUT1 transporter is expressed in the plasma membrane and cytoplasm of myelinating Schwann cells around the nodes of Ranvier and in the Schmidt-Lanterman incisures, making them potential sites of transcellular glucose transport. No GLUT1 was detected in axonal membranes. GLUT3 mRNA was expressed only at low levels, but GLUT3 polypeptide was barely detected by immunocytochemistry or immunoblotting in peripheral nerve from young adult rats. However, in 13-month-old rats, GLUT3 polypeptide was present in myelinated fibers, endoneurial capillaries, and perineurium. In myelinated fibers, GLUT3 appeared to be preferentially expressed in the paranodal regions of Schwann cells and nodal axons, but was also present in the internodal aspects of these structures. The results of the present study suggest that both Schwann cell GLUT1 and axonal and Schwann cell GLUT3 are involved in the transport of glucose into the metabolically active regions of peripheral axons.

Molecular characterization of anionic sites on the luminal front of endoneurial capillaries in sciatic nerve

The distribution of anionic microdomains has been described in cerebral vessels and more recently in capillaries of peripheral nerve. Evidence is accumulating that these sites play a role in the barrier function of vascular endothelia in the PNS and CNS. The chemical nature of anionic sites has been at least partly determined for cerebral vessels but not in peripheral nerve. This study reports our preliminary investigations to determine the nature of endothelial anionic sites in sciatic nerve. The effects of digestion of ultra-thin sections of nerve with a battery of proteolytic and glycolytic enzymes (papain, trypsin, proteinase K, hyaluronidase, heparinase, heparitinase and neuraminidase) on the distribution of anionic sites was determined using the label, cationic colloidal gold. Papain, a proteolytic enzyme of broad specificity, succeeded in removing the majority of cationic colloidal gold-binding sites on the luminal surface of vascular endothelia. In contrast trypsin and proteinase K were less effective, reflecting their narrower specificity. Hyaluronidase, heparinase and heparitinase did not significantly affect cationic colloidal gold-labelling. However, a considerable reduction in cationic colloidal gold-binding occurred following neuraminidase digestion. These results suggest that, as in cerebral vessels, sialic acid-containing glycoproteins are largely responsible for the negatively charged domains on the luminal membrane of endothelial cells in peripheral nerve.

Endoneurial localisation of microvascular damage in human diabetic neuropathy.

Twenty diabetic patients with neuropathy underwent clinical and neurophysiological evaluation together with a detailed morphometric assessment of capillary pathology in endoneurial and epineurial microvascular beds of the sural nerve. Morphological data were compared with ten non-diabetic control subjects. There were no significant differences in control subjects between basement membrane area, endothelial cell area, endothelial cell profile number or luminal area of endoneurial when compared with epineurial capillaries. In contrast, when compared with epineurial capillaries, endoneurial capillaries from diabetic patients demonstrated a significant increase in basement membrane (p < 0.001) and endothelial cell (p < 0.001) area and a significant reduction in luminal area (p < 0.001). There was no significant difference in endothelial cell profile number between endoneurial and epineurial capillaries amongst diabetic patients. Previous studies have demonstrated a good correlation between the degree of microangiopathy and measures of neuropathic severity. In the present study increased endoneurial capillary basement membrane area was significantly related to reduced peroneal nerve conduction velocity (p < 0.001), myelinated fibre density (p < 0.001) and elevated vibration (p < 0.05) and thermal (p < 0.001) perception. Increased endothelial cell area and reduced luminal size were related to a reduced peroneal nerve conduction (p < 0.05, p < 0.01, respectively), reduced myelinated fibre density (p < 0.05, p < 0.01) and elevated thermal perception (p < 0.05, p < 0.001). Epineurial capillary basement membrane, endothelial cell and luminal area failed to relate to measures of neuropathic severity.(ABSTRACT TRUNCATED AT 250 WORDS)

Expression of glucose transporter 1 in adult and developing human peripheral nerve.

Northern hybridization of total RNA isolated from adult human sciatic nerve demonstrated a readily detectable hybridization signal for glucose transporter 1 (GLUT 1) mRNA. Western blot analysis demonstrated that GLUT 1 proteins extracted from adult human and from mature rat sciatic nerves had different electrophoretical mobilities. The migration positions of human and rat GLUT 1 proteins corresponded to 60-70 kDa and 55-60 kDa, respectively, as estimated by markers with known molecular masses. Indirect immunofluorescence staining localized GLUT 1 to the perineurium in the adult human sciatic nerve. Only a few endoneurial capillaries of human adult nerve stained positively for GLUT 1, which was in contrast to rat peripheral nerve where most endoneurial capillaries were positive for GLUT 1. In developing human nerves, the staining pattern for GLUT 1 was markedly different from that of the adult nerves: at 14 weeks, the perineurial cells were entirely negative for GLUT 1. Between 22 and 26 weeks of gestation, the staining reaction for GLUT 1 in the perineurium became markedly more prominent, and by 35 weeks the intense perineurial staining resembled that observed in the adult human nerves. In contrast to adult nerves, both endo- and epineurial blood vessels stained intensely for GLUT 1 in the fetal samples. Thus, the immunoreactivity for GLUT 1 in the perineurium seems to increase concomitant with the maturation of barrier properties of perineurium, whereas the transient expression of GLUT 1 in the vasculature of developing nerve may have a specific role in the proliferating endothelial cells.