Functional and Physiological Methods of Evaluating Median Nerve Regeneration in the Rat.

The main goal of this investigation is to show how to create and repair different types of median nerve (MN) lesions in the rat. Moreover, different methods of simulating postoperative physiotherapy are presented. Multiple standardized strategies are used to assess motor and sensory recovery using an MN model of peripheral nerve lesion and repair, thus permitting easy comparison of the results. Several options are included for providing a postoperative physiotherapy-like environment to rats that have undergone MN injuries. Finally, the paper provides a method to evaluate the recovery of the MN using several noninvasive tests (i.e., grasping test, pin prick test, ladder rung walking test, rope climbing test, and walking track analysis), and physiological measurements (infrared thermography, electroneuromyography, flexion strength evaluation, and flexor carpi radialis muscle weight determination). Hence, this model seems particularly appropriate to replicate a clinical scenario, facilitating extrapolation of results to the human species. Although the sciatic nerve is the most studied nerve in peripheral nerve research, analysis of the rat MN presents various advantages. For example, there is a reduced incidence of joint contractures and automutilation of the affected limb in MN lesion studies. Furthermore, the MN is not covered by muscle masses, making its dissection easier than that of the sciatic nerve. In addition, MN recovery is observed sooner, because the MN is shorter than the sciatic nerve. Also, the MN has a parallel path to the ulnar nerve in the arm. Hence, the ulnar nerve can be easily used as the nerve graft for repairing MN injuries. Finally, the MN in rats is located in the forelimb, akin to the human upper limb; in humans, the upper limb is the site of most peripheral nerve lesions.

BD-2 and BD-3 increase skin flap survival in a model of ischemia and Pseudomonas aeruginosa infection.

The main aim of this work was to study the usefulness of human ß-defensins 2 (BD-2) and 3 (BD-3), which are part of the innate immune system, in the treatment of infected ischemic skin flaps. We investigated the effect of transducing rat ischemic skin flaps with lentiviral vectors encoding human BD-2, BD-3, or both BD-2 and BD-3, to increase flap survival in the context of a P. aeruginosa infection associated with a foreign body. The secondary endpoints assessed were: bacterial counts, and biofilm formation on the surface of the foreign body. A local ischemic environment was created by producing arterialized venous flaps in the left epigastric region of rats. Flaps were intentionally infected by placing underneath them two catheters with 105 CFU of P. aeruginosa before the surgical wounds were hermetically closed. Flap biopsies were performed 3 and 7 days post-operatively, and the specimens submitted to immunohistochemical analysis for BD-2 and BD-3, as well as to bacterial quantification. Subsequently, the catheter segments were analyzed with scanning electron microscopy (SEM). Flaps transduced with BD-2 and BD-3 showed expression of these defensins and presented increased flap survival. Rats transduced with BD-3 presented a net reduction in the number of P. aeruginosa on the surface of the foreign body and lesser biofilm formation.

Reconstruction of a 10-mm-long median nerve gap in an ischemic environment using autologous conduits with different patterns of blood supply: A comparative study in the rat.

The aim of this study was to evaluate in the Wistar rat the efficacy of various autologous nerve conduits with various forms of blood supply in reconstructing a 10-mm-long gap in the median nerve (MN) under conditions of local ischemia. A 10-mm-long median nerve defect was created in the right arm. A loose silicone tube was placed around the nerve gap zone, in order to simulate a local ischemic environment. Rats were divided in the following experimental groups (each with 20 rats): the nerve Graft (NG) group, in which the excised MN segment was reattached; the conventional nerve flap (CNF) and the arterialized neurovenous flap (ANVF) groups in which the gap was bridged with homonymous median nerve flaps; the prefabricated nerve flap (PNF) group in which the gap was reconstructed with a fabricated flap created by leaving an arteriovenous fistula in contact with the sciatic nerve for 5 weeks; and the two control groups, Sham and Excision groups. In the latter group, the proximal stump of the MN nerve was ligated and no repair was performed. The rats were followed for 100 days. During this time, they did physiotherapy. Functional, electroneuromyographic and histological studies were performed. The CNF and ANVF groups presented better results than the NG group in the following assessments: grasping test, nociception, motor stimulation threshold, muscle weight, and histomorphometric evaluation. Radial deviation of the operated forepaw was more common in rats that presented worse results in the other outcome variables. Overall, CNFs and ANVFs produced a faster and more complete recovery than NGs in the reconstruction of a 10-mm-long median nerve gap in an ischemic environment in the Wistar rat. Although, results obtained with CNFs were in most cases were better than ANVFs, these differences were not statistically significant for most of the outcome variables.

Outcomes of Different Methods for Analysis of Biliary Brush Cytology and of Factors Associated with Positive Diagnosis in an Age-Dependent Retrospective Review.

BACKGROUND AND AIMS: Brush cytology during endoscopic retrograde cholangiopancreatography (ERCP) is the most frequently used strategy for obtaining a tissue sample from an indeterminate biliary stricture. A recent study reported that age is a factor associated with positive yields, but further analysis of how age influences the results was lacking. We aimed to evaluate clinical effectiveness of biliary cytology and prognostic factors for a positive outcome, especially age. METHODS: This study was a single-center, retrospective, clinical study of 77 consecutive patients who underwent brush cytology during ERCP to obtain a diagnosis of an indeterminate biliary stricture. We compared 2 routine cytology techniques: A (smear); B (centrifugation of the cytological material collected and the cut-off brush + cell block when sufficient amount of material was available). The data were collected aiming to compare the accuracy of the different techniques used and the prognostic factors affecting the outcome, with a particular focus on age. The yield for brush cytology was compared with the gold standard defined as either definitive histology or the long-term clinical course. RESULTS: The overall accuracy of the 2 used methods was 75.3%. Sensitivity was 52.5%, specificity was 100%, positive predictive value was 100%, and negative predictive value was 66.1%. Although not statistically significant, there was a trend toward accuracy for method B compared with method A (80.4 vs. 65.4%; p = 0.153). Multiple logistic regression analysis showed that younger age was the only independent prognostic factor associated with a positive diagnosis (OR 0.95; 95% CI 0.90-0.99; p = 0.039). Receiver operating characteristic curves for age yielded an area under the curve value of 68.2%. On the basis of the Youden index, 69 years was found to be the optimal cutoff for age. CONCLUSIONS: In this series, the accuracy of routine biliary brush cytology was not equal for all methods and ages; in particular, younger patients (below 69 years) tended to have a higher probability of a correct diagnosis.

INTRODUÇÃO: a citologia biliar é a técnica mais utilizada durante a CPRE para o diagnóstico de uma estenose indeterminada. Um artigo recente refere a importância da idade como fator preditivo de um resultado positivo, embora sem analisar este dado. Pretendemos avaliar a acuidade da citologia biliar e dos factores associados para a obtenção de um resultado positivo com especial interesse na idade. MÉTODOS: análise retrospectiva de um único centro de 77 doentes consecutivos submetidos, durante CPRE a citologia biliar para esclarecer a etiologia de uma estenose biliar. A análise comparou 2 técnicas de rotina: A (esfregaço); B (centrifugação do material colectado e da escova+cell block quando existia material suficiente). Pretendeu-se comparar a acuidade diagnóstica dos 2 diferentes métodos e dos factores de prognóstico associados ao resultado em especial a idade. A acuidade da citologia foi comparada com o "gold standard" definido como a histologia definitiva ou o curso clínico a longo prazo. RESULTADOS: a acuidade global dos diferentes métodos foi 75.3%. A sensibilidade foi 52.5%, a especificidade foi 100%, VPP foi 100% e o VPN foi 66.1%. Apesar de não ser estatisticamente definitivo existiu maior acuidade do método B, em comparação com o A (80.4 vs. 65.4%; p = 0.153). A análise multivariada por regressão logística mostrou que a menor idade é o único fator de prognóstico independente associado a um resultado positivo (OR: 0.95; 95% CI: 0.90­0.99; p = 0.039). As curvas ROC para a idade apresentaram um valor para a AUC de 68.2%. O índice de Youden, determinou que os 69 anos seriam o "cutoff" ideal para a idade. CONCLUSÕES: nesta população a acuidade de citologia biliar não foi idêntica para todos os métodos e idades; em particular doentes com idade inferior a 69 anos apresentam maior probabilidade de obter um diagnóstico correto.

Optimization of an Arterialized Venous Fasciocutaneous Flap in the Abdomen of the Rat.

BACKGROUND: Although numerous experimental models of arterialized venous flaps (AVFs) have been proposed, no single model has gained widespread acceptance. The main aim of this work was to evaluate the survival area of AVFs produced with different vascular constructs in the abdomen of the rat. METHODS: Fifty-three male rats were divided into 4 groups. In group I (n = 12), a 5-cm-long and 3-cm-wide conventional epigastric flap was raised on the left side of the abdomen. This flap was pedicled on the superficial caudal epigastric vessels caudally and on the lateral thoracic vein cranially. In groups II, III, and IV, a similar flap was raised, but the superficial epigastric artery was ligated. In these groups, AVFs were created using the following arterial venous anastomosis at the caudal end of the flap: group II (n = 13) a 1-mm-long side-to-side anastomosis was performed between the femoral artery and vein laterally to the ending of the superficial caudal epigastric vein. In group III (n = 14), in addition to the procedure described for group II, the femoral vein was ligated medially. Finally, in group IV (n = 14), the superficial caudal epigastric vein was cut from the femoral vein with a 1-mm-long ellipse of adjacent tissue, and an end-to-side arterial venous anastomosis was established between it and the femoral artery. RESULTS: Seven days postoperatively, the percentage of flap survival was 98.89 ± 1.69, 68.84 ± 7.36, 63.84 ± 10.38, 76.86 ± 13.67 in groups I-IV, respectively. CONCLUSION: An optimized AVF can be produced using the vascular architecture described for group IV.

A Model of Free Tissue Transfer: The Rat Epigastric Free Flap.

Free tissue transfer has been increasingly used in clinical practice since the 1970s, allowing reconstruction of complex and otherwise untreatable defects resulting from tumor extirpation, trauma, infections, malformations or burns. Free flaps are particularly useful for reconstructing highly complex anatomical regions, like those of the head and neck, the hand, the foot and the perineum. Moreover, basic and translational research in the area of free tissue transfer is of great clinical potential. Notwithstanding, surgical trainees and researchers are frequently deterred from using microsurgical models of tissue transfer, due to lack of information regarding the technical aspects involved in the operative procedures. The aim of this paper is to present the steps required to transfer a fasciocutaneous epigastric free flap to the neck in the rat. This flap is based on the superficial epigastric artery and vein, which originates from and drain into the femoral artery and vein, respectively. On average the caliber of the superficial epigastric vein is 0.6 to 0.8 mm, contrasting with the 0.3 to 0.5 mm of the superficial epigastric artery. Histologically, the flap is a composite block of tissues, containing skin (epidermis and dermis), a layer of fat tissue (panniculus adiposus), a layer of striated muscle (panniculus carnosus), and a layer of loose areolar tissue. Succinctly, the epigastric flap is raised on its pedicle vessels that are then anastomosed to the external jugular vein and to the carotid artery on the ventral surface of the rat's neck. According to our experience, this model guarantees the complete survival of approximately 70 to 80% of epigastric flaps transferred to the neck region. The flap can be evaluated whenever needed by visual inspection. Hence, the authors believe this is a good experimental model for microsurgical research and training.

Segmental colitis caused by idiopathic myointimal hyperplasia of mesenteric veins

Diseases causing colonic ischemia may be mistaken with other causes of segmental colitis such as inflammatory bowel disease, especially in young patients. The authors present the case of a 47-year-old male with severe proctosigmoiditis. Assessment excluded infectious causes, thrombophilia and systemic vasculitis. The initial histological specimen was suggestive of inflammatory bowel disease and therapy was initiated with intravenous steroids and, at day 5, infliximab, with no response. The patient was proposed for surgery. Pathological examination of the surgical specimen revealed an idiopathic myointimal hyperplasia of mesenteric veins, a rare entity exhibiting necrotizing phlebitis with rapid progression to segmental necrosis in the rectosigmoid colon. In this paper the authors discuss the differential diagnosis of proctosigmoiditis in young ages and the approach to this exceptionally rare ischemic entity (AU)

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Segmental colitis caused by idiopathic myointimal hyperplasia of mesenteric veins.

Diseases causing colonic ischemia may be mistaken with other causes of segmental colitis such as inflammatory bowel disease, especially in young patients. The authors present the case of a 47-year-old male with severe proctosigmoiditis. Assessment excluded infectious causes, thrombophilia and systemic vasculitis. The initial histological specimen was suggestive of inflammatory bowel disease and therapy was initiated with intravenous steroids and, at day 5, infliximab, with no response. The patient was proposed for surgery. Pathological examination of the surgical specimen revealed an idiopathic myointimal hyperplasia of mesenteric veins, a rare entity exhibiting necrotizing phlebitis with rapid progression to segmental necrosis in the rectosigmoid colon. In this paper the authors discuss the differential diagnosis of proctosigmoiditis in young ages and the approach to this exceptionally rare ischemic entity.

Brachial plexus morphology and vascular supply in the wistar rat.

INTRODUCTION: The rat is probably the animal species most widely used in experimental studies on nerve repair. The aim of this work was to contribute to a better understanding of the morphology and blood supply of the rat brachial plexus. MATERIAL AND METHODS: Thirty adult rats were studied regarding brachial plexus morphology and blood supply. Intravascular injection and dissection under an operating microscope, as well as light microscopy and scanning electron microscopy techniques were used to define the microanatomy of the rat brachial plexus and its vessels. RESULTS: The rat brachial plexus was slightly different from the human brachial plexus. The arterial and venous supply to the brachial plexus plexus was derived directly or indirectly from neighboring vessels. These vessels formed dense and interconnected plexuses in the epineurium, perineurium, and endoneurium. Several brachial plexus components were accompanied for a relatively long portion of their length by large and constant blood vessels that supplied their epineural plexus, making it possible to raise these nerves as flaps. DISCUSSION: The blood supply to the rat brachial plexus is not very different from that reported in humans, making the rat a useful animal model for the experimental study of peripheral nerve pathophysiology and treatment. CONCLUSION: Our results support the homology between the rat and the human brachial plexus in terms of morphology and blood supply. This work suggests that several components of the rat brachial plexus can be used as nerve flaps, including predominantly motor, sensory or mixed nerve fibers. This information may facilitate new experimental procedures in this animal model.

Introdução: O rato é provavelmente a espécie animal mais utilizada em estudos experimentais de reparação nervosa. Com este trabalho pretendeu-se aprofundar o conhecimento da morfologia e da vascularização do plexo braquial do rato.Material e Métodos: Trinta ratos adultos foram estudados relativamente à morfologia e vascularização do plexo braquial. As técnicas usadas foram a injecção intravascular e dissecção sob microscópio operatório, bem como técnicas de microscopia óptica e microscopia electrónica de varrimento.Resultados: Morfologicamente, o plexo braquial do rato é um pouco diferente do plexo braquial humano. O suprimento arterial e venoso do plexo braquial do rato deriva direta ou indiretamente dos vasos vizinhos. Estes vasos formam plexos vasculares densos e interconectados no epinervo, perinervo e endonervo. Vários componentes do plexo braquial do rato são acompanhados durante um trajecto relativamente longo por vasos sanguíneos relativamente calibrosos e constantes que fornecem o seu plexo epineural, tornando o seu levantamento como retalhos nervosos possível.Discussão: A vascularização do plexo braquial do rato não é muito diferente da reportada na espécie humana, tornando o rato um modelo animal útil para o estudo experimental da fisiopatologia e tratamento da patologia do nervo periférico.Conclusão: Os nossos resultados apoiam a homologia entre o rato e o Homem em termos de morfologia e vascularização do plexo braquial. Este trabalho sugere que vários componentes do plexo braquial do rato podem ser utilizados como retalhos nervosos, incluindo fibras predominantemente motoras, sensitivas ou fibras mistas.