Heterologous fibrin sealant potentiates axonal regeneration after peripheral nerve injury with reduction in the number of suture points.

The use of suture associated with heterologous fibrin sealant has been highlighted for reconstruction after peripheral nerve injury, having the advantage of being safe for clinical use. In this study we compared the use of this sealant associated with reduced number of stitches with conventional suture after ischiatic nerve injury. 36 Wistar rats were divided into 4 groups: Control (C), Denervated (D), ischiatic nerve neurotmesis (6 mm gap); Suture (S), epineural anastomosis after 7 days from neurotmesis, Suture + Fibrin Sealant (SFS), anastomosis with only one suture point associated with Fibrin Sealant. Catwalk, electromyography, ischiatic and tibial nerve, soleus muscle morphological and morphometric analyses were performed. The amplitude and latency values of the Suture and Suture + Fibrin Sealant groups were similar and indicative of nerve regeneration.The ischiatic nerve morphometric analysis in the Suture + Fibrin Sealant showed superior values related to axons and nerve fibers area and diameter when compared to Suture group. In the Suture and Suture + Fibrin Sealant groups, there was an increase in muscle weight and in fast fibers frequency, it was a decrease in the percentage of collagen compared to group Denervated and in the neuromuscular junctions, the synaptic boutons were reestablished.The results suggest a protective effect at the lesion site caused by the fibrin sealant use. The stitches reduction minimizes the trauma caused by the needle and it accelerates the surgical practice. So the heterologous fibrin sealant use in nerve reconstruction should be considered.

Effects of low-level laser therapy on autogenous bone graft stabilized with a new heterologous fibrin sealant.

Autogenous bone grafts are used to repair bone defects, and the stabilization is needed for bone regeneration. Laser photobiomodulation is a modality of treatment in clinical practice for tissue regeneration, and it has therapeutic effects as an anti-inflammatory, analgesic and modulating cellular activity. The aim of the present study was to evaluate the effects of low-level laser therapy (LLLT) on an autogenous bone graft integration process stabilized with a new heterologous fibrin sealant. Forty rats were divided into two groups: Autogenous Fibrin Graft (AFG, n=20), in which a 5mm dome osteotomy was conducted in the right parietal bone and the graft was adhered to the left side using fibrin sealant; and Autogenous Fibrin Graft Laser (AFGL, n=20), which was subjected to the same procedures as AFG with the addition of LLLT. The treatment was performed immediately following surgery and then three times a week until euthanasia, using an 830nm laser (30mW, 6J/cm(2), 0.116cm(2), 258.6mW/cm(2), 2.9J). Five animals from each group were euthanized at 10, 20, 30 and 40days postoperative, and the samples were submitted to histomorphological and histomorphometric analysis. Partial bone regeneration occurred, with new bone tissue integrating the graft to the recipient bed and small areas of connective tissue. Comparative analysis of the groups at the same intervals revealed minor interfaces in group AFGL, with statistically significant differences (p<0.05) at all of the analyzed intervals (10days p=0.0087, 20days p=0.0012, 30days p<0.0001, 40days p=0.0142). In conclusion, low-level laser therapy stimulated bone regeneration and accelerated the process of integration of autogenous bone grafts.

Effect of low-level laser therapy (LLLT) on peripheral nerve regeneration using fibrin glue derived from snake venom.

OBJECTIVES: The purpose of this study was to assess whether the adhesive permits the collateral repair of axons originating from a vagus nerve to the interior of a sural nerve graft, and whether low-level laser therapy (LLLT) assists in the regeneration process. MATERIALS AND METHODS: Study sample consisted of 32 rats randomly separated into three groups: Control Group (CG; n=8), from which the intact sural nerve was collected; Experimental Group (EG; n=12), in which one of the ends of the sural nerve graft was coapted to the vagus nerve using the fibrin glue; and Experimental Group Laser (EGL; n=12), in which the animals underwent the same procedures as those in EG with the addition of LLLT. Ten weeks after surgery, the animals were euthanized. Morphological analysis by means of optical and electron microscopy, and morphometry of the regenerated fibers were employed to evaluate the results. RESULTS: Collateral regeneration of axons was observed from the vagus nerve to the interior of the autologous graft in EG and EGL, and in CG all dimensions measured were greater and presented a significant difference in relation to EG and EGL, except for the area and thickness of the myelin sheath, that showed significant difference only in relation to the EG. CONCLUSIONS: The present study demonstrated that the fibrin glue makes axonal regeneration feasible and is an efficient method to recover injured peripheral nerves, and the use of low-level laser therapy enhances nerve regeneration.

Comparison of results obtained with standard and inside out vein graft techniques and their implication on neurotrophin expression in repair of nerve defect: an experimental study.

Standard vein graft (SVG) and inside out vein graft (IOVG) techniques to promote peripheral nerve regeneration have been widely studied since last two decades. In this experimental study, we attempted to compare these two techniques and analyze the differences in the expression of the neurotrophins during peripheral nerve regeneration. Thirty-six male Wistar rats were used in this sciatic nerve transection model and were divided into two experimental groups (SVG and IOVG) and one sham operated control group. An overall defect of 10 mm was made in the sciatic nerve of the animals in the experimental groups. Each group consisted of two time intervals of 6 and 12 weeks (n = 6). After each experimental interval, sciatic functional index (SFI) along with area and diameter of the axons and fibers of each group were calculated. Muscle mass measurements were also evaluated to see any functional recovery in the groups. Expression of neurotrophins in the graft and distal stump were analyzed with the help of RT-PCR. SFI obtained from walking track analysis showed poor motor recovery in the experimental groups during both time intervals. No significant differences in the histological, morphometric (P > 0.05), and muscle mass measurements (P > 0.05) between the two experimental groups were observed. Analysis of RT-PCR data exhibited an increase in the expression of NT-3 with time in both the grafts (6 weeks 0.428 ± 0.392, 12 weeks 1.089 ± 0.455, P < 0.05) and distal stump (6 weeks 0.411 ± 0.306, 12 weeks 0.807 ± 0.303, P < 0.05) of the SVG group. The study concludes that there is no substantial difference in the nerve regeneration ability between both the techniques. Also, the difference in the level of NT-3 between SVG and IOVG suggests a distinct regulation of NT-3 in peripheral nerve regeneration.

Morphologic and biomechanical changes of thoracic and abdominal aorta in a rat model of cigarette smoke exposure.

BACKGROUND: Smoking is the most relevant environmental factor that affects the development of aortic aneurysm. Smokers have elevated levels of elastase activity in the arterial wall, which leads to weakening of the aorta. The aim of this study was to verify whether cigarette smoke exposure itself is capable of altering the aortic wall. METHODS: Forty-eight Wistar rats were divided into 2-, 4-, and 6-month experimental periods and into 2 groups: smokers (submitted to smoke exposure at a rate of 40 cigarettes/day) and nonsmokers. At the end of the experimental periods, the aortas were removed and cross-sectioned to obtain histologic specimens for light microscopic and morphometric analyses. The remaining longitudinal segments were stretched to rupture and mechanical parameters were determined. RESULTS: A degenerative process (i.e., a reduction in elastic fibers, the loss of lamellar arrangement, and a reduction of smooth muscle cells) was observed, and this effect was proportional in intensity to the period of tobacco exposure. We observed a progressive reduction in the yield point of the thoracic aorta over time (P < 0.05). There was a decrease in stiffness (P < 0.05) and in failure load (P < 0.05) at 6 months in the abdominal aorta of rats in the smoking group. CONCLUSIONS: Chronic exposure to tobacco smoke can affect the mechanical properties of the aorta and can also provoke substantial structural changes of the arterial wall.

Surgical anatomy of the human middle ear: an insight into cochlear implant surgery.

PURPOSE: This research was designed to aid practical otologic studies of the human middle ear. The topographic anatomy access of the middle ear was described with special focus to the cochlear implant procedure. It was conducted in an attempt to elucidate factors that would ultimately determine the ease of insertion of an electrode array. METHODS: Fifteen right and 12 left temporal bones were dissected under the surgical microscope. After performing appropriate incisions, the distances between the stapedius muscle tendon, incus long crus and the cochleostomy were measured with the help of a digital microscope (Dino-Lite plus(®)). RESULTS: After performing statistical analysis, we found that strong relationship exists in the distances between the measured anatomical landmarks. CONCLUSION: Microscopic anatomical studies of the temporal bone are essential to safely perform surgical intervention within the middle ear. The results shows that morphometric data concerning different anatomical structures inside the middle ear, particularly distances, is an important contribution towards the planning of safe surgical procedures.

Incidence, morphology and morphometry of the foramen of Vesalius: complementary study for a safer planning and execution of the trigeminal rhizotomy technique.

BACKGROUND: The foramen of Vesalius (FV) is located in the greater wing of the sphenoid bone between the foramen ovale (FO) and the foramen rotundum in an intracranial view. The FO allows the passage of the mandibular branch of trigeminal nerve, which is the target of the trigeminal radiofrequency rhizotomy. OBJECTIVE: We analyzed its location, morphology, morphometry and interrelation among other foramina. MATERIALS AND METHODS: 400 macerated adult human skulls were examined. A digital microscope (Dino-Lite plus) was used to capture images from the FV. A digital caliper was used to perform the measurements of the distance between the FV and other foramina (FO, foramen spinosum and the carotid canal) in an extracranial view of the skull base. RESULTS: In the 400 analyzed skulls, the FV was identified in 135 skulls (33.75%) and absent on both sides in 265 skulls (66.25%). The FV was observed present bilaterally in 15.5% of the skulls. The incidence of unilateral foramen was 18.25% of the skulls of which 7.75% on right side and 10.5% on left side. The diameter of the FV was measured and we found an average value of 0.65 mm, on right side 0.63 mm and on the left side 0.67 mm. We verified that positive correlations were statistically significant among the three analyzed distances. CONCLUSIONS: This study intends to offer specific anatomical data with morphological patterns (macroscopic and mesoscopic) to increase the understanding of the FV features as frequency, incidence and important distances among adjacent foramina.

Fat cell invasion in long-term denervated skeletal muscle.

There are several differences between red and white muscles submitted to different experimental conditions, especially following denervation: a) denervation atrophy is more pronounced in red than white muscles; b) the size of the fibers in the red muscles does not vary between different parts of the muscle before and after denervation, when compared to white muscles; c) the regional difference in the white muscles initially more pronounced after denervation than red muscle; d) red muscle fibers and fibers of the deep white muscle present degenerative changes such as disordered myofibrils and sarcolemmal folds after long-term denervation; e) myotube-like fibers with central nuclei occur in the red muscle more rapidly than white after denervation. Denervation of skeletal muscles causes, in addition to fibers atrophy, loss of fibers with subsequent regeneration, but the extent of fat cell percentage invasion is currently unknown. The present article describes a quantitative study on fat cell invasion percentage in red m. soleus and white m. extensor digitorum longus (EDL) rat muscles at 7 weeks for up to 32 weeks postdenervation. The results indicate that the percentage of fat cells increase after denervation and it is steeper than the age-related fat invasion in normal muscles. The fat percentage invasion is more pronounced in red compared with white muscle. All experimental groups present a statistically significant difference as regard fat cell percentage invasion.

Myonuclei and satellite cells in denervated rat muscles: an electron microscopy study.

The study and description of a separated cell type have been dependent on the evolution of the electron microscope. There have been few experiments designed to induce changes in myonucleus and satellite-cell populations in vivo without physically injuring muscle. In this regard, the most practical method to experimentally alter myonucleus and satellite-cell populations is denervation. The sciatic nerve was sectioned in order to observe myonuleus and satellite-cell behavior. After 7, 16, and 38 weeks postdenervation, the soleus and extensor digitorum longus muscles were observed under electron microscopy. In each studied period, the pattern, distribution, and possible cellular alterations were observed in the studied muscles. Myonuclei exhibited alterations such as shrinkage, nuclear membrane separation, condensed chromatin, ghost nuclei as well as normal ones, and disorganized myofibrils. The maximum and minimum myonucleus diameters were measured in each studied period. In both muscles, the maximum diameters decreased. On the other hand, the minimum myonucleus diameters did not show any differences. Regarding satellite cells, activation characteristics were observed. In both muscles, the satellite cells were located distant of capillary after denervation. Characterization of the different types of nuclei abnormalities, especially in chromatin condensation, should provide useful information for future morphological studies.

Description of nodal fibers in the cranial vein cava walls of the bovine (bos indicus)

Muchas investigaciones han estudiado la presencia de fibras musculares estriadas cardíacas, con características de fibras nodales en las paredes de la vena cava y del seno coronario de mamíferos. Sin embargo no hay un consenso sobre la localización exacta de estas fibras. El objetivo de este trabajo fue identificar estas fibras en la vena cava craneal de bovino. Para este propósito, utilizando 10 corazones bovinos con los vasos de la base, fijados en formol 10 por ciento. Después de la fijación, el segmento intrapericárdico fue aislado e incluido en paraplástico. Se obtuvieron cortes transversales y longitudinales los que fueron sometidos a coloración con tricrómicos de Masson y Mallory, orceína clorhídrica de Unna-Taenzer y Calleja. Los resultados microscópicos revelaron que estas fibras nodales están localizadas en las paredes ventral e izquierda de la vena cava craneal a nivel de la desembocadura en el atrio derecho. Concluimos que estas fibras presentes en las paredes de la vena craneal, transmiten el estímulo eléctrico originado en el nodo sinoatrial para toda musculatura atrial, hasta las paredes venosas, causando la constricción del ostio venoso impidiendo el reflujo venoso durante la sístole atrial