Respuestas fotosintéticas y zonación de tres especies de Gelidiales de Tenerife, Islas Canarias

Three species of Gelidiales (Gelidium arbuscula, Gelidium canariense and Pterocladiella capillacea) (Rhodophyta) were selected due to their abundance in the marine lower intertidal of the north coast of the island of Tenerife (Canary Islands), to assess, using PAM fluorescence, the importance of irradiance and exposure to air on vertical distribution. We compared tolerance to emersion by air-drying fronds under simulated emersion, and results suggest that recovery of photosynthesis after emersion plays a major role in the vertical distribution of these three species. Morphological traits such as clumped fronds explain the higher tolerances, and reduced water loss of the species upper on the shore. Local differences between sites may be related to slight differences in the light regime related to topography.Se han seleccionado tres especies de Gelidiales (Gelidium arbuscula, Gelidium canariense y Pterocladiella capillacea) que son abundantes en los niveles inferiores del intermareal de la costa N de Tenerife para establecer, utilizando fluorescencia tipo PAM, la importancia de la cantidad de luz y la exposición al aire en su zonación vertical. Se ha comparado la tolerancia a la emersión en frondes expuestas al aire, y los resultados sugieren que la capacidad de recuperación de la fotosíntesis tras la emersión tiene un papel fundamental en la explicación de la posición vertical de estas tres especies. Además, características morfológicas como el apelotonamiento de las frondes pueden coadyuvar a la mayor tolerancia, al reducir la pérdida de agua en emersión en las especies de niveles más altos. Las variaciones entre sitios se pueden deber a desigualdades locales en la cantidad de luz provocadas por diferencias topográficas

Giant sacral schwannoma: A report of six cases

Sacral and presacral schwannomas are often found incidentally, because they present with vague symptoms or symptomless. Schwannoma occurring in this area occasionally presents with enormous dimensions, known as a giant schwannoma. The tumor removal is a surgical challenge due to the difficult approach and abundant vascularity. The aim of this study is to review cases of giant sacral schwannomas focusing the surgical management and outcome. Six patients with sacral and presacral schwannoma were treated surgically. The patients included two males and four females, and the mean age was 47.8 years. All patients experienced pain at the time of presentation. The tumors were classified as intraosseous type in one case, dumb-bell type in four cases, and retroperitoneal type in one case. The tumors were removed with a piecemeal subtotal excision in three patients, a partial excision in two patients, and enucleation in one patient. The surgeries were performed by the combination of an anterior and posterior approach in three patients, a posterior approach in two patients, and an anterior approach in one patient. The mean surgical time was 7.8 hrs, and the mean blood loss was 2572 g. The tumor recurred in one patient after the partial excision and was removed completely in a second surgery. No patient, including the patient who underwent the second surgery, presented with pain and obvious neurological deficit at the final follow-up. The surgical treatment of the giant sacral schwannoma with a piecemeal subtotal excision can achieve a good outcome, avoiding unnecessary neurological deficit