Dorsal spinal venous occlusion in the rat.

Occlusion of the major components of the spinal venous system is usually associated with spinal arteriovenous malformations or systemic thrombophlebitis. Although spinal venous system dysfunction has been implicated in compressive cord syndromes, myelopathies from decompression sickness, and spinal cord trauma, its pathophysiology remains unclear. To characterize disorders associated with spinal venous occlusion, we developed a model in the rat produced by focally coagulating the dorsal spinal vein transdurally at the T7 and T10 vertebral levels. Following such occlusion, venous stasis, sludging and perivascular hemorrhages in the small venous branches were observed. By 1 week postocclusion, animals developed hindlimb paralysis from which they partially recovered over time. Histologic examination in the acute phase disclosed tissue necrosis, edema, and hemorrhages predominantly in the dorsal aspect of the spinal cord. This was gradually replaced by an intense macrophagic infiltration and the partial formation of a cystic cavity by 1 month. These findings indicate that dorsal spinal vein occlusion in the rat causes significant neurologic and pathologic alterations. We conclude that this procedure produces a relevant animal model for the study of the pathophysiology of spinal venous occlusion, and it allows the characterization of its effects on spinal cord blood flow, the blood-spinal cord barrier, and the development of edema independent of cord compression. Our findings in this model provide an insight into one of the mechanisms of injury extension in spinal cord trauma and other disorders associated with spinal venous dysfunction.

Malnutrition: organic and functional consequences.

Malnutrition in its various forms is without doubt the commonest disease. Acute malnutrition resulting from a total lack of ingestion clearly shows that not only are water and electrolytes a priority for survival but also energy reserves. It also shows that the maximum wasting that the lean body mass can withstand is around 40% before the organism collapses and death occurs. Malnutrition is more often the results of insufficient ingestion, and the term protein-calorie malnutrition has been suggested for the most frequently occurring type. This can give rise to confusion because the deficiency in these patients is not limited to these macronutrients but extends, rather, to micronutrients, which are equally important to the functioning of the body. A useful approach for the surgeon is to analyze how the various organs and systems have been affected. The effects on the gastrointestinal tract, the immunologic system, and formation of scar tissue are reviewed.

Reinnervation of adult rat gastrocnemius muscle by embryonic motoneurons transplanted into the axotomized tibial nerve.

In some cases of spinal cord injury and in certain motoneuron diseases, such as amyotrophic lateral sclerosis and spinal muscular atrophies, lower motoneurons are destroyed and muscle function cannot be restored except by reinnervation from alternate motoneuron sources. We have tested the feasibility of employing local transplantation of embryonic motoneurons to restore innervation to denervated somatic muscle as a first step in salvaging muscle function and enabling use of functional electric stimulation. Dissociated ventral spinal cord cells from Embryonic Days 14 and 15 rats were transplanted into the distal stump of axotomized tibial nerves of adult rats. Animals were killed 3-18 weeks after transplantation. After 3 weeks large multipolar cells, resembling alpha motoneurons, were observed within the transplant site surrounded by myelinated and unmyelinated axons and dendrites. Axons emanating from these transplanted motoneurons were identified within the nerve stump and within the previously denervated gastrocnemius muscle, forming neuromuscular junctions. Transplanted motoneurons survived up to 18 weeks and were labeled after intramuscular injection of fast blue. This study demonstrates that embryonic spinal motoneurons, transplanted into the distal adult peripheral nerve stump, are able to survive and reinnervate the denervated target muscle. We are now exploring the possibility of using this experimental approach to retard the atrophy of denervated skeletal muscle, thus providing a muscle capable of useful response to functional electrical stimulation.

Predicción del CO2 arterial a partir del CO2 espirado en pacientes con probable alteración de la relación ventilación perfusión / Multivariable model to predict PaCO2 using PETCO2 and some patients variables

Objetivos: Evaluar la asociación entre edad, género, peso, estado físico ASA, enfermedad pulmonar o cardiovascular previa, otros antecedentes médicos, historia de tabaquismo, tipo de cirugía, función pulmonar preoperatoria, posición, volumen de líquidos administrados, transfusión sanguínea y temperatura, con la PaCO2; generar un modelo multivariado de predicción a partir de la PETCO2 y algunas variables del paciente. Métodos: Estudio de dos fases; 1. Búsqueda de la literatura, para identificar variables potencialmente predictoras y 2. Se obtuvieron 152 muestras de gases arteriales de pacientes mayores de 15 años, ambos géneros, durante cualquier cirugía exceptuando las cardiovasculares con circulación extracorpórea, bajo anestesia general. Se recolectó información sobre: edad, género, peso, estado físico ASA, enfermedad pulmonar o cardiovascular previa, otros antecedentes médicos, historia de tabaquismo, tipo de cirugía, función pulmonar preoperatoria, posición, volumen de líquidos administrados, transfusión sanguínea y temperatura y PETCO2, antes de tener los resultados de PaCO2, para generar el modelo multivariado de predicción. De 21 predictores clínicos evaluados en el análisis univariado inicial, solamente 9 se encontraron asociados estadísticamente con la PaCO2, a saber: PETCO2, cirugía ortopédica, peso, antecedente de enfermedad pulmonar, posición de Trendelemburg, otros antecedentes médicos, extabaquismo, transfusión y volumen de cristaloides. El modelo derivado en el análisis multivariado tuvo un R2 de 0.565 (p< 0.000). Solamente 9 variables clínicas estuvieron asociadas con variaciones en la PaCO2 durante cirugía, pero tienen en conjunto una pobre capacidad predictiva para PaCO2