In Vitro Antiplasmodial Activity of Phospholipases A2 and a Phospholipase Homologue Isolated from the Venom of the Snake Bothrops asper

The antimicrobial and antiparasite activity of phospholipase A₂ (PLA₂) from snakes and bees has been extensively explored. We studied the antiplasmodial effect of the whole venom of the snake Bothrops asper and of two fractions purified by ion-exchange chromatography: one containing catalytically-active phospholipases A₂ (PLA₂) (fraction V) and another containing a PLA₂ homologue devoid of enzymatic activity (fraction VI). The antiplasmodial effect was assessed on in vitro cultures of Plasmodium falciparum. The whole venom of B. asper, as well as its fractions V and VI, were active against the parasite at 0.13 ± 0.01 µg/mL, 1.42 ± 0.56 µg/mL and 22.89 ± 1.22 µg/mL, respectively. Differences in the cytotoxic activity on peripheral blood mononuclear cells between the whole venom and fractions V and VI were observed, fraction V showing higher toxicity than total venom and fraction VI. Regarding toxicity in mice, the whole venom showed the highest lethal effect in comparison to fractions V and VI. These results suggest that B. asper PLA₂ and its homologue have antiplasmodial potential.     

Presence of matrix vesicles in the body of odontoblasts and in the inner third of dentinal tissue: A scanning electron microscopyc study

Objectives: The aim of this report is to present the results of a scanning electron microscopic study on the presence of matrix vesicles (MVs) found in human dentine. Study Design: Dentin tissue from 20 human bicuspids was analyzed by means of scanning electron microscopy. Results: MVs were found as outgrowths of the cellular membrane of the odontoblastic body, the more proximal portion of the odontoblastic process before entering the dentinal tubule and in the odontoblastic process within the inner third of the dentin. Size of MVs varied depending on location. In the inner third of dentin, they were seen in diverse positions; as membranal outgrowths, deriving from the odontoblastic process, lying free in the intratubular space and attached to the dentinal wall. Sometimes, they were seen organized forming groups of different sizes and shapes or as multivesicular chains running from the surface of the odontoblastic process to the tubular wall. MVs were present in places never considered: 1) the body of odontoblasts; 2) the most proximal part of the odontoblastic processes before entering the circumpulpal dentine and also: 3) in the inner third of dentinal tissue. Conclusions: According to our results, MVs not only participate during mantle dentin mineralization during early dentinogenesis, they also contribute during the mineralization process of the inner dentin. Key words:Dentin, microvesicles, secretory vesicles, dentin formation, dentin secretion.     

Considerations on pancreatic exocrine function after pancreaticoduodenectomy

The pancreaticoduodenectomy (PD) procedure may lead to pancreatic exocrine and endocrine insufficiency. There are several types of reconstruction for this kind of operation. Pancreaticogastrostomy (PG) was introduced to reduce the rate of postoperative pancreatic fistula. Although some randomized control trials have shown no differences regarding pancreatic leakage between PG and pancreaticojejunostomy (PJ), recently some reports reveal benefits from the PG over the PJ. Some surgeons concern about the performing of the PG and inactivation of pancreatic enzymes being in contact with the gastric juice, and the detrimental results over the exocrine pancreatic function. The pancreatic exocrine function can be measured with direct and indirect tests. Direct tests have the highest sensitivity and specificity for detection of exocrine insufficiency but require tube placement. Among the tubeless indirect tests, the van de Kamer stool fat analysis remains the standard to diagnose fat malabsorption. The patient compliance and time consuming makes it not so suitable for its clinical use. Fecal immunoreactive elastase test is employed for screening of exocrine insufficiency, is not cumbersome, and has been used to study pancreatic function after resection. We analyze the FE1 levels in our patients after the PD with two types of reconstruction, PG and PJ, and we discuss some considerations about the pancreaticointestinal drainage method after pancreaticoduodenectomy.