Crushed Area Research Articles

A Study on the Rock-Breaking Characteristics of an Arcing-Blade Cutter under Different Cutting Parameters

To analyze the rock-breaking characteristics of an arcing-blade cutter in cutting red sandstone, a two-cutter cutting model was established based on the finite element method. Then, the cutting processes of the arcing-blade cutter at penetrations of 2 mm, 4 mm, and 6 mm with different cutter spacings were investigated, and the changing rules of the rock-breaking load, rock crushing state, and rock-breaking efficiency were obtained. Subsequently, the obtained simulation results were validated through linear cutting experiments. The research results showed that, as the penetration of the arcing-blade cutter increased, the rock-breaking load also increased; specifically, under 2 mm penetration, the rock-breaking load remained stable, irrespective of the cutter spacing. However, under 4 mm and 6 mm penetration, the vertical and rolling force increased and then stabilized with an increase in the cutter spacing, while the lateral force decreased and then stabilized, attributed to the synergistic effect between the cutters. At 2 mm penetration, the absence of interaction between the cutting of two cutters in sequence resulted in two separate crushed areas on the rock surface. However, at 4 mm and 6 mm penetration, the rock ridge could be crushed under a smaller cutter spacing. Meanwhile, with an increase in the cutter spacing, the synergistic effect between the cutters diminished, causing the rock ridge between two cuttings to remain uncrushed. The specific energy at the 4 mm and 6 mm penetrations decreased initially with an increase in the cutter spacing, then increased, and eventually stabilized. The optimal cutter spacings at these penetrations were determined as 50 mm and 60 mm, respectively. Conversely, at 2 mm penetration, the specific energy remained almost unchanged with an increase in the cutter spacing, maintaining at a high level and resulting in a low efficiency in cutting rock.

FEM-SPH adaptive method for analysis protection mechanism of B4C ceramics

To simulate the collision of a tungsten heavy alloy projectile with different velocities on the B4C ceramic target, an adaptive conversion model from Lagrangian elements to SPH particles is developed due to the limitations of the traditional finite element method (FEM) with the element erosion technique. By comparing the simulation results with experimental data and FEM simulation results, the accuracy and effectiveness of the model were validated. According to the damage morphological characteristics, the target damage was classified into the central crush area, cone cracks area, radial/circular area, and fragment falling area by analyzing the damage nephogram, and the formation causes of each area were discussed in detail. According to the simulation results, the impact process between the projectile and target is split into three stages: initial impact stage, erosion stage, and crack propagation stage, and the energy dissipation in each phase was computed and examined. Finally, the protection mechanism is summarized in detail. This study contributes to improve the protection mechanism system of B4C ceramic target.

Experimental study of deep-burial underground structures subjected to multiple 45° side–top far-field explosions

A deeply buried straight-walled round-arch structure in a rock medium is taken as the research object in this study. Model tests of the underground structure subjected to multiple 45° side–top far-field explosions, with a scale of 1:20 and a proportional explosion distance of 1.68, are designed and carried out to study the dynamic responses, failure modes and damage mechanisms of the deep-burial underground structure after ground shocks induced by explosions. The macroscopic phenomena and measured data of the tests are reported and analyzed. The results show that after the first explosion and the second explosion, the surface of the surrounding rock model and the reserved charging port are seriously damaged. In contrast, the damage to the underground structure is relatively slight. The overall structure produces downward-bending deformation, and an axial crack occurs on the inner surface of the vault. The peak accelerations of the underground structure after the explosions are significant, with values reaching 2400 g, and the corresponding prototype value can exceed 120 g. After the first explosion, the damage to the upper part of the surrounding rock and the axial crack at the vault lead to a decrease in local stiffness. The crushed areas and cracks of the surrounding rock formed by the first explosion intensify the attenuation and leakage of shock wave energy during the second explosion, resulting in reductions in the ground shock pressure on the structure, the structural strain and the acceleration response. It is also found that on the floor of the prototype structure, the maximum spectral acceleration in the range of the natural vibration period of the human body exceeds 10 g, which poses a safety threat to the usage of underground structures. The research results in this study provide an experimental reference for the anti-explosion design of deeply buried underground structures and provide a basis for the establishment of performance and vulnerability indicators for straight wall round arch underground structures subjected to far-field explosions.

Value of immunohistochemistry in crushed areas of pulmonary neuroendocrine carcinoma

Immunohistochemical demonstration of neuroendocrine differentiation is often performed in routine diagnostic practice for lung neuroendocrine carcinoma. However, these carcinomas are often crushed, especially on small specimens. The value of immunohistochemistry on crushed areas is not known. We aimed to assess the value of immunohistochemical markers in crushed areas. We performed a retrospective study of 299 patients with a diagnosis of pulmonary neuroendocrine carcinoma. We showed that the markers TTF-1, synaptophysin, chromogranin A, CD56, and INSM1 were more often negative in crushed areas compared with well-preserved areas. The proliferation index with anti-Ki67 was decreased but remained on average around 90%. For all markers, the percentage of labeled cells was lower than in the preserved areas. Finally, we show that cases without labeling in the crushed areas and maintained labeling in the non-crushed areas have a lower percentage of labeling than cases without this labeling mismatch. Finally, there were no false positives of these stains.Neuroendocrine markers are valid in crushed areas when positive. However, the percentage of labeled cells may be lower than on preserved areas and lead to false negatives. Finally, the proliferation index, although decreased, remains close to that on preserved areas.

Relationships between body temperatures and behaviours in lactating dairy cows

The welfare of dairy cows is sometimes compromised by anxiety that could be indicated by changes in body temperature. We hypothesized that there was an association between external body surface infrared temperature (IRT) of lactating cows and behavioural responses to anxiety, using rectal temperature as a reference point. Approximately 50 cows were examined individually once a month for 3 consecutive months. Cows were excluded from the evaluation if > 300 d in milk, somatic cell counts exceeded 400 × 1000′s cells/mL, or if dried-off, and so numbers declined over time. Monthly IRT thermograms of each cow’s head and coronary bands of forelimbs were taken, and we collected data deemed indicative of anxiety (behaviour in a forced lateralisation test, behaviour in the crush, flight speed and rectal temperature) as well as potential confounders: temperature humidity index (THI) in the parlour and crush area and lactation variables. The hypothesized positive association between IRT and behavioural indicators of anxiety was found in the first month only, between IRT of both eyes and cows’ sniffing behaviour in the forced lateralisation test. Associations between rectal temperature and behavioural indicators occurred in month 3, when rectal temperature was positively associated with both flight speed and crush score. Cow waiting time prior to being milked was negatively associated with limb IRT in each of the 3 months, and positively associated with the ratio of eyes to limb IRT in 2 of the 3 months, whereas no such associations were detected with rectal temperature. In the analysis across months there were associations between IRT and behavioural indicators, which suggested that limb IRT may relate to cow behaviour: limb IRT was negatively related to slow to medium walking, and the ratio of IRT of eyes to limbs was positively associated with a vertical, rather than horizontal, tail. No associations were detected between laterality and IRT or rectal temperature. The adjusted R2 of the regressions across months was higher for IRT (eyes 86 %; limbs 78 %) than rectal temperature (63 %). IRT had a high repeatability, particularly for both eyes, across the 3 months, whereas rectal temperature was not repeatable. We conclude that there are potential relationships between IRT and cow emotions, but it is important to account for confounders.

Examination of alteration and metasomatic zones based on the tectonic setting of the Kamoo region (northeast of Isfahan, Iran)

Kamoo region (northeast of Isfahan) has an anticline structure with a northwest-southeast trend. The exposed part of this anticline consists of siltstone-sandstone and Jurassic shale, which is located below the Cretaceous formation as an unconformity. Penetration by magmatic masses (dikes) and mineralization events are mainly related to fault systems and fractures in the region and follow the trend of the anticline. In addition, the intensity and variety of alterations are affected by tectonic factors, with alteration and metasomatic haloes having developed next to crushed areas. The alteration process is the main controller of mineral mass grade in the study area; therefore, iron grade in the Kamoo ore has increased by the effects of alteration. The alteration effects include propylitic haloes, iron hydroxides (limonite), and clay mineralization (argillic). The host rock consists of Jurassic shales with siltstone, sandstone, and Cretaceous limestone. Calcareous formations adjacent to granodiorite masses are the main hosts of iron skarns. The results of this study showed that the mineral samples from Kamoo were relatively rich in Light Rare Earth Elements (LREEs); the average La/Yb ratio is about 18.61 and Eu anomaly is between 0.52 and 1.94. Based on the findings of this study, the origin for Kamoo skarn was consistent with the model presented by Meinert, and the region’s mineralization and alteration characteristics correspond to the conditions prevailing in oceanic subduction and back-arc basin environments.

Dynamics of Rolling Stock Wheels and Track Interaction in Areas of Welded Rail Joints Crush

Finite element models of a rail crushed in a welded joint area and fixed on an elastic damping foundation and a car wheel have been developed. An algorithm has been developed to calculate quasistatic and impact forces during a wheel rolling at different speeds. Experimental studies have been carried out to determine vertical forces in the crushed area of the welded joint at a depth of 1.8 mm using the strain measurement method on the rail web neutral axis.

A Numerical Gas Fracturing Model of Coupled Thermal, Flowing and Mechanical Effects

Gas fracturing, which overcomes the limitation of hydraulic fracturing, is a potential alternative technology for the development of unconventional gas and oil resources. However, the mechanical principle of gas fracturing has not been learned comprehensively when the fluid is injected into the borehole. In this paper, a damagebased model of coupled thermal-flowing-mechanical effects was adopted to illustrate the mechanical principle of gas fracturing. Numerical simulation tools Comsol Multiphysics and Matlab were integrated to simulate the coupled process during the gas fracturing. Besides, the damage evolution of drilling areas under several conditions was fully analyzed. Simulation results indicate that the maximum tensile stress, which occurs in the upper and lower of the injection hole, decreases with the increase of the tectonic stress coefficient (TSC). As the TSC increases, shear fractures increase, a crushed area is gradually formed and the seepage area increases rapidly. The influence of TSC on fracture expansion is concluded as follows: with the decrease of TSC, the relative width of fractures decreases whilst the depth increases. It indicates that thermal stress and pore pressure promote the expansion of tensile fractures but restrain the expansion of shear fractures. Therefore, a relatively lower injection gas pressure is required to obtain the same degree of fracturing with a coupled thermal gradient.

34BetaE12 and Alfa-Methylacyl Coenzyme A Racemase (AMACR) Antibodies Better Than p63 Antibody Distinguish Normal and Neoplastic Glands in Prostatic Tissue With Thermal Artifacts.

The occurrence of inked margins with crush artifact derived from the electrocauterization in radical prostatectomy and/or the presence of crushed areas with distorted glands in prostatic samples after transurethral resection of prostate (TURP) can induce a significant interobserver variability during histopathologic evaluation of specimens. The specific immunostaining for basal cell markers 34BetaE12 and p63 and for alfa-methylacyl coenzyme A racemase (AMACR) in neoplastic cells is commonly used as an ancillary tool to establish benign and malignant glands. In this study we carried out the immunohistochemical reactions for p63, 34BetaE12, and AMACR on 3 different and successive paraffin sections to discriminate malignant and benign prostatic glands, distorted and crushed by the thermal artifacts in 60 radical prostatectomies and 50 TURP samples. All prostatic acinar adenocarcinoma showed the loss of basal cell markers and expression of AMACR, whereas p63 failed to stain the basal cell layer in benign crushed prostatic glands. The same cauterized glands were steadily positive for 34BetaE12. The high percentage of p63 false negative cases in benign distorted and crushed glands could be explained by the thermal artifacts which might cause lack of p63 antigenicity. In contrast, the antigenicity of 34BetaE12 and AMACR seem not to be affected by cautery artifacts. Thus, in cauterized suspicious prostatic glands an immunohistochemistry panel including, p63, 34BetaE12, and AMACR or only 34BetaE12 is recommended. In addition, after the first evaluation with only p63, we suggest that a separate and confirmatory staining for 34BetaE12 is strongly recommended.

Numerical study of the contributions of shock wave and detonation gas to crack generation in deep rock without free surfaces

Abstract Explosion gas pressure, combined with the action of an explosive stress wave, has a significant effect on the production and propagation of cracks in deep rock without a free surface. Thus, it is necessary to investigate the corresponding fracturing mechanisms and contributions of the shock wave and detonation gas towards inducing rock damage during blasting. In this work, the rock stratum is simplified as a square model with a circular borehole at its centre and modelled as a particle assembly based on the discrete element method. The shock wave is simulated as a time-varying pressure applied to the particles of the borehole. The action of the detonation gas is imitated as a quasi-static pressure on the fractures connected with the blasthole. To distinguish the role of the detonation gas in the formation and development of cracks, two primary simulation scenarios are studied: first, both the shock wave and detonation gas are simultaneously considered to simulate the blasting-induced rock damage; second, only the explosive stress wave is considered in rock blasting. Moreover, the coupling charge and decoupling charge are simulated in each scenario. In particular, based on the undirected graph theory, the authors present a new approach to efficiently determine the fracture clusters connected to the blasthole at each time-step to apply the quasi-static loads on the cracks. The results show that the shock wave plays a major role in crushing the rock near the wall of the blasthole and manufacturing a few primary radius cracks further away from the blasthole, whereas the detonation gas further extends the fractures to increase the crushed area (the additional stress caused by detonation gas is greater than the tensile strength of the rock) or separates the already formed rock fragments to increase the aperture of the cracks (the additional stress caused by the detonation gas is less than the tensile strength of the rock).

Coupled thermal−gas−mechanical (TGM) model of tight sandstone gas wells

The mechanism of CO2 fracturing under coupled thermal−gas−mechanical (TGM) conditions is important for gas production in tight sandstone gas wells. In this study, a coupled TGM model was proposed on the basis of the elastic damage principal, and the coupling relationships were expressed by the governing equations. The proposed model was then tested through comparison between the numerical uniaxial compressive test and the laboratory test. COMSOL MULTIPHYSICS was adopted to calculate the coupled numerical model; the impact of injection rate and injection gas temperature was fully investigated. The research results showed that the initiation pressure stayed stable with the increase of the breakdown pressure and injection rate over a certain range (0.106 m3 s−1–0.848 m3 s−1). The seepage area under the injection rate of 0.848 m3 s−1 was 3.45 times that under the injection rate of 0.106 m3 s−1, which resulted from the gradual destruction of the samples and the formation of new fractures at higher injection rate. The initiation pressure and the breakdown pressure decreased, since tensile cracks tended to form with the increase of injection temperature. Shear cracks formed around the hole—the crush area. The tensile cracks propagated much deeper into the surrounding rock under the higher injection temperature. This research provides a study of unconventional oil and gas extraction for reference.

Management of the crush syndrome in critical patients: 10 cases

Introduction: Crush trauma may be life threating in extremities. Crush syndrome leads to a systemic disorder through muscle cytolysis and the spread of metabolic substance into the circulatory system. In the present study, we summarized the follow-up and treatment of 10 cases with intensive care unit (ICU) crush injury. Materials and Methods: We have analyzed the clinical data of 10 patients with crush injury who were under treatment in the intensive care unit of our clinic. Age, sex, diagnosis, APACHE II score, sepsis, intensive care complications, treatment parameters in intensive care and arterial blood gases parameters, routine blood biochemistry, alanine aminotransferase, lactate dehydrogenase, creatine kinase, creatinine, existence of blood urea nitrogen, urinary protein and severity score of the patients have been recorded. Patients have been closely monitored for symptoms of crush injury, changes, crush area, urination and dangerous complications. Results: The mean age of 10 patients (10 male) was 41.3 ± 8.7 years. APACHE II score was 21,7. 8 out of 10 patients had traumatic shock, one showed acute renal failure and one presented with multiple organ dysfunction syndrome (MODS). In 3 patients presenting the criteria for crush syndrome, the symptoms of extremity distension and sensory function disorder were regulated with rapid surgical operation and hemodialysis, and urination increased, even in some patients, it reached the normal level. Serologic parameters were regulated in most of the patients after application. Amputation was applied to 5 (50%) patients in our group for serious infection and crush. 2 (20%) patients died, one because of MODS and one because of acute renal failure. Conclusion: Early and aggressive resuscitation, emergency treatment and close monitoring of serious complications are of great importance for saving the lives of the patients with crush syndrome under intensive care.

Accounting of the thread embedment in timber structures dowel-type joints. Load–slip relationship

This work is devoted to the development of a calculation proposal for dowel-type joints in timber structures that takes into account the increase in load capacity due to the use of threaded dowels. While the method is based on acknowledged criteria of structural standards, it also considers the crushed areas that appear in the timber near the zone of contact with the dowel’s thread. Thereby, it comes closer to the actual mechanical behaviour of the whole joint when it suffers a relative displacement between its different parts under an external load. The equations proposed in this study to define the load capacity of the joint take into account the rope effect produced by the axial forces arising on the dowel due to the combined effect of bending of the dowel and compression of the timber fibres embedded in its thread. A comparison of the results of the new analytical method proposed with those of a battery of experimental tests is shown.

Sox10 Expression in Goldfish Retina and Optic Nerve Head in Controls and after the Application of Two Different Lesion Paradigms.

The mammalian central nervous system (CNS) is unable to regenerate. In contrast, the CNS of fish, including the visual system, is able to regenerate after damage. Moreover, the fish visual system grows continuously throughout the life of the animal, and it is therefore an excellent model to analyze processes of myelination and re-myelination after an injury. Here we analyze Sox10+ oligodendrocytes in the goldfish retina and optic nerve in controls and after two kinds of injuries: cryolesion of the peripheral growing zone and crushing of the optic nerve. We also analyze changes in a major component of myelin, myelin basic protein (MBP), as a marker for myelinated axons. Our results show that Sox10+ oligodendrocytes are located in the retinal nerve fiber layer and along the whole length of the optic nerve. MBP was found to occupy a similar location, although its loose appearance in the retina differed from the highly organized MBP+ axon bundles in the optic nerve. After optic nerve crushing, the number of Sox10+ cells decreased in the crushed area and in the optic nerve head. Consistent with this, myelination was highly reduced in both areas. In contrast, after cryolesion we did not find changes in the Sox10+ population, although we did detect some MBP- degenerating areas. We show that these modifications in Sox10+ oligodendrocytes are consistent with their role in oligodendrocyte identity, maintenance and survival, and we propose the optic nerve head as an excellent area for research aimed at better understanding of de- and remyelination processes.

Effect of mining on shear sidewall groundwater inrush hazard caused by seepage instability of the penetrated karst collapse pillar

Mining-induced groundwater inrush, a type of serious hazard for underground coal extraction, occurs in tunnel or coal face combined with a large volume of groundwater gushing. It has an impartible relationship with geological structures such as karst collapse pillar (KCP), which is widely distributed in North China. To analyze the effect of coal mining on groundwater inrush caused by seepage instability of the penetrated KCP (PKCP), stress and seepage coupling equations are used to model the seepage rule, and a numerical FLAC3D model is conducted to determine the shear stress, damage zone, pore pressure, seepage vectors and effect of damage zone on seepage field development. The results indicate that when PKCP and the surrounding rocks show dislocation, shear failure may occur, which leads to a shear sidewall channel for groundwater inrush. As mining advances, the damage zone in the PKCP and its crushed area develop gradually, and the simulated damage zone development was consistent with observed thicknesses of crushed rocks. Under the effect of the support pressure and unloading of the coal face, an obvious seepage concentrate channel with greater hydraulic head and seepage vectors will form within the edge of the PKCP; then, the shear sidewall channel will gradually move to the other side with the coal face near and away. When the damage zones are crushed through, the connected fractures will become a strong seepage channel in PKCP, named as pipe flow, which may cause groundwater inrush.

Affect evaluation of a new medical posture mat in the prevention of pressure ulcer in pediatric orthopedics

Objective To evaluate the application effect on preventing pressure ulcers of modern medical position pad in orthopaedic. Methods A total of 124 patients with congenital dislocation of the hip, pelvis fractures and femoral fractures were selected between January 2013 and December 2013. They were divided into 2 groups by random digits table method with 62 cases each. The observation group was given modern medical position pad nursing after operation, and the control group was given routine postoperative nursing. Postoperative 2 hours, 4 hours after operation, postoperative 1 day, 2 days, 3 days and before discharge pressure situation, children crushed area skin comfort, families of children with pain on pressure parts skin care satisfaction and turn the situation were analyzed and compared. Results The observation group postoperative 2 hours did not appear the skin red and bruised, there was no crushed in 4 hours, only 4 cases of skin red, no 1 case skin crushed before leaving hospital. Twelve cases of the control group in postoperative 2 hours appeared red skin pressure, 4 hour after crush skin in 4 cases, 6 cases of skin crushed before leaving hospital. The comfortable children for 56 cases, mild discomfort for 6 cases in the observation group,and 31, 23 cases in the control group. The satisfaction was 100.0%(62/62) in the observation group, and 93.5%(58/62) in the control group. The degree of turn the situation pain in the observation group was lower than that in the control group. Conclusions New medical position mat can effectively extend the pediatric orthopaedic congenital dislocation of the hip, pelvis fracture and femoral fracture with roll over time, reduce the stimulation of the skin, sweat for pressure parts effectively prevent the occurrence of pressure sores, improve the crushed area comfort children and families of children with satisfaction, greatly reduce the postoperative pain when rolled over, worth clinical promotion. Key words: Child; Fractures, bone; Hip dislocation; Pressure ulcer; Medical posture mat

Detection of faults position and possible crushed zones by using electrical resistivity and microgravity methods: Application to the Lar Dam area, Iran

The main purposes of this study are to determine the fault position and possible crushed zones, general position and qualitative image of injection curtain, topology of cavities, and weak areas, and also examine deep extension of existing cracks in Berm. Geophysical examinations were performed by using the combination of electrical resistivity and microgravimetry data in Lar Dam. These studies include measurements of 420 electrical soundings with 1,000 m maximum length of current transmitter and measuring 1,081 microgravimetry stations. Also, in order to examine the possible density contrasts, this study discussed three-dimensional modeling by microgravimetry method to obtain Bouguer anomaly and residual anomaly, and determine the edge of residual anomaly. The result of these studies identified four crushed and weak areas with maximum water flight potential. Due to priority and importance degree of geological anomalies, these four weak areas are in the south part of the dam body, north of Berm, south of Berm, and west and southwest of Berm. The observed cracks in Berm are results of Berm subsidence that is due to fault activities or falling developed cavities along faults. It is presented that these cavities which are extended to depth of 70 m can have significant effect on the stability of the dam body.

Impaired slow axonal transport in diabetic peripheral nerve is independent of RAGE

Diabetic peripheral nerve dysfunction is a common complication occurring in 30-50% of long-term diabetic patients. The pathogenesis of this dysfunction remains unclear but growing evidence suggests that it might be attributed, in part, to alteration in axonal transport. Our previous studies demonstrated that RAGE (Receptor for Advanced Glycation Endproducts) contributes to the pathogenesis of diabetic peripheral neuropathy and impairs nerve regeneration consequent to sciatic nerve crush, particularly in diabetes. We hypothesize that RAGE plays a role in axonal transport impairment via the interaction of its cytoplasmic domain with mammalian Diaphanous 1 (mDia1) - actin interacting molecule. Studies showed that mDia1-RAGE interaction is necessary for RAGE-ligand-dependent cellular migration, AKT phosphorylation, macrophage inflammatory response and smooth muscle migration. Here, we studied RAGE, mDia1 and markers of axonal transport rates in the peripheral nerves of wild-type C57BL/6 and RAGE null control and streptozotocin-injected diabetic mice at 1, 3 and 6h after sciatic nerve crush. The results show that in both control and diabetic nerves, the amount of RAGE accumulated at the proximal and distal side of the crush area is similar, indicating that the recycling rate for RAGE is very high and that it is evenly transported from and towards the neuronal cell body. Furthermore, we show that slow axonal transport of proteins such as Neurofilament is affected by diabetes in a RAGE-independent manner. Finally, our study demonstrates that mDia1 axonal transport is impaired in diabetes, suggesting that diabetes-related changes affecting actin binding proteins occur early in the course of the disease.

Hyaluronic Acid Promotes the Peripheral Nerve Regeneration in the Experimental Rabbit Model of Common Peroneal Nerve Crush Injury

This study demonstrated that hyaluronic acid (HA) accelerated peripheral nerve regeneration after crush injury to common peroneal nerve in experimental rabbit model. Ten male New Zealand White rabbits, weighing 1.8 to 2.0 kg, were used. After creating the nerve crushed model in every right legs, rabbits were divided into two groups. Group A was the HA application into surrounding crushed nerve area, and group B was the sham control. Electrophysiological assessment was estimated every weeks. After 10 weeks, nerve histological examination, muscle weight and muscle histology were used to evalutate the regeneration of injured common peroneal nerve. There were no differences in the electrophysiological assessment between two groups. The peripheral nerve histology showed that myelinated nerve fibers were observed more frequently and connective tissue was less in the crushed nerve of group A. Muscle degenerative changes such as fibrosis, atrophy and centrally located myonuclei were less detected in group A than group B. In conclusion, the HA could become a potential neuroprotective agent for improvement of peripheral nerve regeneration after the crush injury.

Bone marrow mononuclear cells migrate to the demyelinated sciatic nerve and transdifferentiate into Schwann cells after nerve injury: Attempt at a peripheral nervous system intrinsic repair mechanism

In the present work, we analyzed whether endogenous and/or transplanted bone marrow mononuclear cells (BMMC) migrate spontaneously to the crushed sciatic nerve and whether they transdifferentiate into Schwann cells (SC) in order to help repair the damaged tissue. We also studied both the immunohistochemical evolution of myelin proteins MBP and P(0) and the myelin composition of both the proximal and distal stumps of the crushed sciatic nerve to determine the demyelination-remyelination period. Immunohistochemical analysis of crushed animals showed that the degeneration process consists of loss of nerve fiber integrity accompanied by degradation of myelin basic proteins MBP and P(0) , which is anticipated by protein cluster formation. The remyelination process appears as a recovery in nerve fiber structure as well as in MBP and P(0) immunoreactivity; results obtained studying isolated myelin from the crushed sciatic nerve show a strong correlation between them. As opposed to demyelination, axonal damage is observed for a short period of time and takes place mostly in the crush area and the segments adjacent to the lesion. Evidence of spontaneous migration of endogenous or intravascularly transplanted BMMC (CD34(+) and vimentin(+) ) is found during the demyelination period exclusively to the injured sciatic nerve. Once migration takes place, transdifferentiation to SC is observed. Such migration and transdifferentiation processes might be inferred to constitute a spontaneous repair mechanism after nerve injury.