Differential regulation of platelet aggregation and aminophospholipid exposure by calpain

Aggregation, exposure of procoagulant phospholipids and shedding of microparticles are platelet responses that depend on activating conditions. To determine how these different responses are interconnected, we simultaneously measured fibrinogen (Fg) binding and aminophospholipid exposure on activated platelets by means of flow cytometry. Low calcium ionophore (A23187) concentrations induced Fg binding but not annexin V binding. In contrast, high A23187 concentrations induced annexin V binding but not Fg binding. Collagen, both alone and in the presence of thrombin, induced both Fg and annexin V binding. Dual labelling was found on 38 +/- 9% of platelets stimulated by thrombin plus collagen. The regulatory role of calpain in these platelet functions was investigated. When calpain was partially inhibited by 2 microg/ml calpeptin, Fg binding still occurred but aminophospholipid exposure was limited. By contrast, complete inhibition of calpain by 100 microg/ml calpeptin or E64d decreased Fg binding but enhanced aminophospholipid exposure. In these latter conditions, cytosolic calcium-extruding systems were inhibited. The results suggest that (i) conditions that favour aminophospholipid exposure tend to decrease the aggregation process and (ii) calpain determines the switch to either aggregation or aminophospholipid exposure by controlling intracellular calcium.     

Remittent hyperammonemia in congenital portosystemic shunt

Congenital portosystemic shunts (PSS) are rare vascular anomalies with different gross anatomy. Persistent patent ductus venosus (PDV) represents an uncommon cause of intrahepatic PSS. The diagnosis of this condition may not be obvious because of its wide spectrum of clinical manifestations, ranging from asymptomatic to life-threatening disease. We report the case of three boys with neuropsychological symptoms associated with mild fasting hyperammonemia. An oral protein load allowed the detection of a detoxication defect due to PSS related to PDV. This simple procedure can be worthwhile of attention in patients with mental retardation, behavior disturbances, and learning difficulties after exclusion of common causes of inherited hyperammonemia, namely, urea cycle disorders, organic acidemias, and fatty acid oxidation defects.     

Analysis of the histologic features in the differential diagnosis of intrahepatic neonatal cholestasis

AIM： To compare the histologic features of the liver in intrahepatic neonatal cholestasis （IHNC） with infectious, genetic-endocrine-metabolic, and idiopathic etiologies. METHODS： Liver biopsies from 86 infants with IHNC were evaluated. The inclusion criteria consisted of jaundice beginning at 3 mo of age and a hepatic biop- sy during the 1st year of life. The following histologic features were evaluated： cholestasis, eosinophilia, giant cells, erythropoiesis, siderosis, portal fibrosis, and the presence of a septum. RESULTS： Based on the diagnosis, patients were classified into three groups： group 1 （infectious; n = 18）, group 2 （genetic-endocrine-metabolic; n = 18）, and group 3 （idiopathic; n = 50）. There were no significant differences with respect to the following variables： cholestasis, eosinophilia, giant cells, siderosis, portal fibrosis, and presence of a septum. A significant dif- ference was observed with respect to erythropoiesis, which was more severe in group 1 （Fisher＇s exact test, P = 0.016）. CONCLUSION： A significant difference was observed in IHNC of infectious etiology, in which erythropoiesis was more severe than that in genetic-endocrine-meta- bolic and idiopathic etiologies, whereas there were no significant differences among cholestasis, eosinophilia, giant cells, siderosis, portal fibrosis, and the presence of a septum.     

A case of massive gastric necrosis in a young girl with Rett Syndrome

This is the unusual case of a 17-year-old girl affected by Rett Syndrome (RS) who suffered acute abdominal distension and constipation for a week. Laparotomy showed massive gastric dilatation, with total necrosis and perforation. Total gastrectomy and Y-Roux esophagojejunostomy were performed. We believe the clinical status was caused by the mechanism of air swallowing, present in our patient and typical in RS. In fact, as reported, massive air bloat may result in a decrease of the intramural blood flow with consequential ischemia of the gastric wall. We stress the importance of early detection of the gastroenterological symptoms in these patients, with timely positioning of nasogastric tube and gastrostomy, to prevent serious complications potentially life-threatening as massive gastric necrosis.