Hind limb sensory innervation in rats: comparison between sural and saphenous nerve morphometry / Inervación sensorial de los miembros posteriores en ratas: comparación morfométrica entre los nervios sural y safeno

Although numerous studies investigate sensory recovery of the hind paw of the rat after nerve damage, still no comprehensive overview of its normal innervation is present in the literature. We investigated the morphometry of myelinated fibers in the sural and saphenous nerves and analyzed their size distributions in young rats. Six 30-day-old female Wistar rats were perfused with 2.5% glutaraldehyde and their right and left sural and saphenous nerves were prepared for light microscopy and morphometry. Morphometric data were compared between segments (proximal versus distal) and sides (right versus left) for the same nerves. Also, segments from right or left sides were compared between nerves (sural versus saphenous). Both, the sural and saphenous nerves, exhibited proximal to distal symmetry on both sides as well as left-right symmetry. Histograms of the diameter of the myelinated fibers were unimodal in both nerves, regardless of segments or sides with the peaks of the fibers size occurring between 2.5 and 4.0 µm. The axon distributions reflected the myelinated fiber distributions, with the sural and saphenous nerves peaking between 1.5 and 2.0 µm. The G ratio (the ratio between the axon and fiber diameters) distributions were also unimodal, with peaks at 0.6 for both nerves. This study contributes to the literature with information on the myelinated fibers morphometry from the two sensory nerves responsible for the rat hind limb innervation. This information is valuable for a better understanding of the possible contribution of collateral sprouting from the sural or saphenous nerves on the paw sensory territory recovery observed after one of these nerves is damaged.

Aunque numerosos estudios investigan la recuperación sensorial del miembro pélvico o posterior de la rata después del daño en los nervios, aún no existe en la literatura una visión global de su inervación normal. Investigamos la morfometría de fibras mielínicas de los nervios sural y safeno y analizamos sus distribuciones de tamaño en ratas jóvenes. Seis ratas Wistar de 30 días de edad fueron perfundidas con 2,5% de glutaraldehído, se prepararon los nervios sural y safeno derecho e izquierdo para microscopía de luz y morfometría. Datos morfométricos fueron comparados entre los segmentos (proximal vs distal) y laterales (derecho vs izquierdo) para los mismos nervios. Además, los segmentos de los lados derecho e izquierdo se compararon entre los nervios (sural vs safeno). Ambos nervios sural y safeno exhibieron una simetría proximal a distal en ambos lados, así como una simetría izquierda-derecha. Histogramas del diámetro de las fibras mielinizadas eran unimodales en ambos nervios, independientemente de los segmentos o de los lados, siendo los peaks del tamaño de las fibras entre 2,5 y 4,0 micras. Las distribuciones de los axones reflejan las distribuciones de fibras mielinizadas, de los nervios sural y safeno que alcanzaban entre 1,5 and 2,0 µm. La relación de G (relación entre los diámetros de los axones y de fibra) eran también unimodales, alcanzando 0,6 para ambos nervios. Este estudio contribuye a la literatura con los datos de la morfometría de fibras mielinizadas de ambos nervios sensoriales responsables de la inervación de la extremidad pélvica de la rata. Esta información es valiosa para una mejor comprensión de los nervios sural y safeno en la recuperación sensorial del miembro después de que uno de estos nervios ha sido dañado.

Epidemiology of coronary artery bypass grafting at the Hospital Beneficência Portuguesa, São Paulo / Epidemiologia da cirurgia de revascularização miocárdica do Hospital Beneficência Portuguesa de São Paulo

Introduction: The knowledge of the prevalence of risk factors and comorbidities, as well as the evolution and complications in patients undergoing coronary artery bypass graft allows comparison between institutions and evidence of changes in the profile of patients and postoperative evolution over time. Objective: To profile (risk factors and comorbidities) and clinical outcome (complications) in patients undergoing coronary artery bypass graft in a national institution of great surgical volume. Methods: A retrospective cohort study of patients undergoing coronary artery bypass graft in the hospital Beneficência Portuguesa de São Paulo, from July 2009 to July 2010. Results: We included 3,010 patients, mean age of 62.2 years and 69.9% male. 83.8% of patients were hypertensive, 36.6% diabetic, 44.5% had dyslipidemia, 15.3% were smokers, 65.7% were overweight/obese, 29.3% had a family history of coronary heart disease. The expected mortality calculated by logistic EuroSCORE was 2.7%. The isolated CABG occurred in 89.3% and 11.9% surgery was performed without cardiopulmonary bypass. The most common complication was cardiac arrhythmia (18.7%), especially acute atrial fibrillation (14.3%). Pneumonia occurred in 6.2% of patients, acute renal failure in 4.4%, mediastinites in 2.1%, stroke in 1.8% and AMI in 1.2%. The in-hospital mortality was 5.4% and in isolated coronary artery bypass graft was 3.5%. The average hospital stay was 11 days with a median of eight days (3-244 days). Conclusion: The profile of patients undergoing coronary artery bypass graft surgery in this study is similar to other published studies. .

Introdução: O conhecimento da prevalência dos fatores de risco e comorbidades, bem como a evolução com complicações nos pacientes submetidos à cirurgia de revascularização miocárdica, permite a comparação entre instituições e a comprovação de modificações no perfil de pacientes e na evolução pós-operatória ao longo do tempo. Objetivo: Conhecer o perfil (fatores de risco e comorbidades) e a evolução clínica (complicações) nos pacientes submetidos à cirurgia de revascularização miocárdica em uma instituição nacional de grande volume cirúrgico. Métodos: Estudo de coorte retrospectivo de pacientes submetidos ao procedimento de cirurgia de revascularização miocárdica no Hospital Beneficência Portuguesa de São Paulo, no período de julho de 2009 a julho de 2010. Resultados: Foram incluídos 3010 pacientes, com idade média de 62,2 anos e 69,9% do sexo masculino. 82,8% dos pacientes eram hipertensos, 36,6% diabéticos, 44,5% dislipidêmicos, 15,3% tabagistas, 65,7% com sobrepeso/obesidade e 29,3% tinham antecedentes familiares de doença coronária. A mortalidade média esperada calculada pelo EuroSCORE logístico foi de 2,7%. A cirurgia de revascularização miocárdica isolada ocorreu em 89,3% e em 11,9% foi realizada cirurgia sem circulação extracorpórea. A complicação mais comum foi arritmia cardíaca (18,7%), especialmente a fibrilação atrial aguda (14,3%). Pneumonia ocorreu em 6,2% dos pacientes, lesão renal aguda em 4,4%, mediastinite em 2,1%, acidente vascular encefálico em 1,8% e infarto agudo do miocárdio em 1,2%. A mortalidade intra-hospitalar foi de 5,4% e na cirurgia de revascularização miocárdica isolada foi de 3,5%. O tempo de permanência hospitalar médio foi de 11 dias, com mediana de oito dias (3 - 244 dias). Conclusão: O perfil dos pacientes submetidos à cirurgia de revascularização miocárdica neste estudo assemelha-se ao de outros estudos publicados. .

Limb immobilization alters functional electrophysiological parameters of sciatic nerve

Immobilization, used in clinical practice to treat traumatologic problems, causes changes in muscle, but it is not known whether changes also occur in nerves. We investigated the effects of immobilization on excitability and compound action potential (CAP) and the ultrastructure of the rat sciatic nerve. Fourteen days after immobilization of the right leg of adult male Wistar rats (n=34), animals were killed and the right sciatic nerve was dissected and mounted in a moist chamber. Nerves were stimulated at a baseline frequency of 0.2 Hz and tested for 2 min at 20, 50, and 100 Hz. Immobilization altered nerve excitability. Rheobase and chronaxy changed from 3.13±0.05 V and 52.31±1.95 µs (control group, n=13) to 2.84±0.06 V and 59.71±2.79 µs (immobilized group, n=15), respectively. Immobilization altered the amplitude of CAP waves and decreased the conduction velocity of the first CAP wave (from 93.63±7.49 to 79.14±5.59 m/s) but not of the second wave. Transmission electron microscopy showed fragmentation of the myelin sheath of the sciatic nerve of immobilized limbs and degeneration of the axon. In conclusion, we demonstrated that long-lasting leg immobilization can induce alterations in nerve function.

Beneficial effects of treadmill training in experimental diabetic nerve regeneration

OBJECTIVES: We investigated the effects of treadmill training (10 weeks) on hindlimb motor function and nerve morphometric parameters in diabetic rats submitted to sciatic nerve crush. MATERIALS AND METHOD: Wistar rats (n = 64) were divided into the following groups: non-diabetic; trained non-diabetic; non-diabetic with sciatic nerve crush; trained non-diabetic with sciatic nerve crush; diabetic; trained diabetic; diabetic with sciatic nerve crush or trained diabetic with sciatic nerve crush. Diabetes was induced by streptozotocin injection (50 mg/kg, iv). Hindlimb motor function was evaluated weekly by assessing sciatic functional indices, and the proximal and distal portions of the sciatic nerve were used for morphometric analysis. RESULTS: At 13 weeks post-injury, the distal nerve portion of all injured groups and the proximal nerve portion of the diabetic with sciatic nerve crush group presented altered morphometric parameters such as decreased myelinated fiber diameter (~7.4 + 0.3μm vs ~4.8 + 0.2μm), axonal diameter (~5 + 0.2μm vs ~3.5 + 0.1μm) and myelin sheath thickness (~1.2 + 0.07μm vs ~0.65 + 0.07μm) and an increase in the percentage of area occupied by endoneurium (~28 + 3 percent vs ~60 + 3 percent). In addition, in the non-diabetic with sciatic nerve crush group the proximal nerve portion showed a decreased myelinated fiber diameter (7.4+0.3μm vs 5.8 + 0.3μm) and myelin sheath thickness (1.29 + 0.08μm vs 0.92 + 0.08μm). The non-diabetic with sciatic nerve crush, trained non-diabetic with sciatic nerve crush, diabetic with sciatic nerve crush and trained diabetic with sciatic nerve crush groups showed normal sciatic functional index from the 4th,4th,9th and 7th week post-injury, respectively. Morphometric alterations in the proximal nerve portion of the diabetic with sciatic nerve crush and non-diabetic with sciatic nerve crush groups were either prevented or reverted to values similar to the non-diabetic group by treadmill training. CONCLUSION: Diabetic condition promoted delay in sciatic nerve regeneration. Treadmill training is able to accelerate hindlimb motor function recovery in diabetic injured rats and prevent or revert morphometric alterations in proximal nerve portions in non-diabetic and diabetic injured rats.

Un sistema sencillo y de bajo costo para la reconstruccion tridimensional de estructuras embrionarias a partir de cortes seriados / A Simple and Cheap 3D Reconstruction System of Embryonic Structures from Serial Sections

En este trabajo se muestra el montaje y utilización de un sistema de reconstrucción tridimensional en estructuras embrionarias, utilizando equipos sencillos, de fácil adquisición y uso, utilizando como ejemplo la inervación del miembro posterior del embrión de rata de 19 días de gestación. Además, se muestra cómo pueden lograrse resultados de buen nivel, en cuanto a la forma, ubicación y distribución de las estructuras de interés, obteniendo adicionalmente información cuantitativa acerca de la forma y tamaño (volumen y área superficial), a partir de la utilización de software gratuitos de libre acceso en internet.