Running after the clock

The way we currently understand vertebrate development is undoubtedly associated with the research undertaken at the "Institut d'Embryologie Cellulaire et Moleculaire" at Nogent-sur-Marne during the last decades. Working in this Institute has been a privilege for many junior and senior researchers. Eight years ago, in this stimulating environment, an exciting observation followed by a series of revealing experiments gave rise to a novel field of research. This study provided evidence for the existence of a molecular clock underlying chick somite formation. In this review, we focus on the cascade of studies that have followed this discovery. Thus far, it has been demonstrated that the molecular clock is operating in several vertebrate models namely chick, mouse, zebrafish, frog and medaka, probably functioning to provide cells with multidimensional positional information. Loss and gain of function experiments and detailed gene promoter analyses have proved very useful in understanding how the clock machinery works. Recent data has also led to the fascinating hypothesis that the clock might not be an exclusive property of somitic cells, but rather a mechanism used by a wide range of embryonic tissues. Meanwhile, the clock "keeps ticking" and many questions are still waiting for an answer.     

Sensibility of the abdomen after abdominoplasty

Abdominal skin hypesthesia may occur after abdominoplasty. The purpose of this study was to find out (1) which sensibility modalities are decreased and (2) which areas of the abdominal wall are affected, so that patients can be warned preoperatively about this condition. Forty patients were divided in two groups of 20 patients each. In the control group, patients had no previous abdominal incisions. The sensibility evaluation of patients from the experimental group was made from 12 to 60 months after abdominoplasty, with an average of 31.5 months. These patients were divided into two groups of 10 patients each, a short-term follow-up group (12 to 30 months postoperatively) and a long-term follow-up group (31 to 60 months postoperatively). The abdominal skin was divided into 12 areas; nine were above the abdominoplasty incision and three were below it. Sensibility to superficial touch, superficial pain, and hot and cold modalities was recorded as positive in all areas by a variable number of patients of the experimental group. However, in area 8 (hypogastric area), a statistically significant number of patients had decreased sensibility in all sensibility modalities (Fisher's test and t test). Patients in the experimental group also showed decreased sensibility to hot and cold temperature in area 11 (pubic area). Sensibility to pressure decreased significantly in all areas of the abdomen when compared with the control group (t test). When patients of the short-term follow-up group were compared with those of the long-term follow-up group, there was no statistically significant difference for all modalities of sensibility in the areas studied, except for area 5. In this area it was found that long-term follow-up patients recovered sensibility to cold and hot temperatures. These findings help plastic surgeons to orient their patients about possible risk of exposure to injuries in the areas with decreased sensibility after abdominoplasty. Most importantly, as these patients have decreased sensibility to pressure and hot temperature in a more extensive area of the abdomen, they are exposed to a higher risk of burn injury.