The error backpropagation (EBP) algorithm for training feedforward multilayer perceptron (FMLP) has been used in many applications because it is simple and easy to implement. However, its gradient descent method prevents EBP algorithm from converging fast. To overcome the slow convergence of EBP algorithm, the second order methods have adapted. Levenberg-Marquardt (LM) algorithm is estimated to...

To assess the role of protein kinase C (Ca2+/phospholipid-dependent enzyme) in the activation of the human neutrophil respiratory burst, we have utilized an ether lipid of the type 1-O-alkyl-2-O-methylglycerol (AMG), recently shown to be an inhibitor of this kinase. AMG-C16 (with an hexadecyl chain at the sn-1 position) was found to inhibit the respiratory burst induced by sub-optimal concentra...

When elicited murine peritoneal exudate cells were subjected to Percoll density gradient centrifugation, polymorphonuclear neutrophils (PMN) were found to distribute over a broad spectrum of buoyant densities (1.10-1.06 g/ml). PMN isolated between approximately 1.10 and 1.085 g/ml were referred to as high density PMN (HD-PMN), and those isolated at approximately 1.085-1.06 g/ml were designated ...

Objective: Aggressive periodontitis (AgP) is frequently associated with the presence of Aggregatibacter actinomycetemcomitans, a Gram-negative pathogen, which expresses leukotoxin (Ltx) as a virulence factor. Ltx is known to disturb neutrophil function and to activate these cells. This study was aimed at investigating the ability of Ltx to alter the chemotactic behaviour of neutrophils, the mos...

A variety of bacterial enterocolitis in their active stages are characterized by the migration of polymorphonuclear leukocytes (PMNs) across epithelial surfaces. These mechanisms could explain some effects of enterotoxins observed in the intestinal mucosae. Here, using specific inhibitors, we investigated the potential role of CD10 (E.C. 3.4.24.11), present at the surface of human neutrophils, ...

Agents which elevate cellular cAMP (prostaglandin E2, theophylline, and forskolin) or mimic cAMP action (dibutyryl cAMP) are known to inhibit human neutrophil activation (superoxide generation and secretion) by receptor-linked agonists such as formyl-methionyl-leucyl-phenylalanine (fMLP). Herein, we show that these agents also markedly inhibit fMLP-stimulated diradylglycerol generation (assayed...

Neutrophil degranulation is important in many inflammatory disorders, although the intracellular mechanisms underlying this process remain poorly understood. The Rho GTPase, Rac2, has been implicated in control of degranulation in earlier studies. We hypothesized that Rac2 selectively regulates neutrophil primary granule release. Using bone marrow and peritoneal exudate neutrophils from rac2(-/...

Little is known about the possible role of leukocytes in the pathogenesis of vasospasm. We hypothesized that vasoactive products released by leukocytes might produce constriction of atherosclerotic arteries. To test this hypothesis, we infused fmet-leu-phe (fMLP), a peptide that activates leukocytes to release their vasoactive products, into the perfused hind limb of normal and atherosclerotic ...

Neutrophil degranulation is important in many inflammatory disorders, although the intracellular mechanisms underlying this process remain poorly understood. The Rho GTPase, Rac2, has been implicated in control of degranulation in earlier studies. We hypothesized that Rac2 selectively regulates neutrophil primary granule release. Using bone marrow and peritoneal exudate neutrophils from rac2 / ...

Hemocyte migration toward infection and wound sites is an essential component of insect defense reactions, although the biochemical signal mechanisms responsible for mediating migration in insect cells are not well understood. Here we report on the outcomes of experiments designed to test the hypotheses that (1) insect hemocytes are able to detect and migrate toward a source of N-formyl-Met-Leu...