The norpurpureine alkaloid from inhibits human platelet activation in vitro.

Background: The leaves of have yielded several alkaloids with anti-aggregation activities against rabbit platelets. This is promising in the search for agents that might act against platelets and reduce the incidence of cardiovascular diseases. Since significant differences in platelet function have been reported between human and animal platelets, a study focusing on the effect of extracts against human platelet activation is necessary.

IFN-gamma alters the human sperm membrane permeability to Ca(2+).

Inflammation in the male genitourinary tract has been associated with the release of pro-inflammatory cytokines such as interferon-gamma (IFN-γ) and elevated reactive oxygen species, which affects spermatozoa capacitation, motility, and the acrosome reaction, along with functions regulated by the concentration of cytoplasmic Ca(2+) ([Ca(2+)]cyto). Though Ca(2+) signaling is of particular significance in sperm, the effect of IFN-γ intracellular calcium on these cells is still unknown. The present study evaluated the effect of IFN-γ on the [Ca(2+)]cyto and Ca(2+) permeability on human sperm.

Effect of tumor necrosis factor-α on the intracellular Ca(2+) homeostasis in human sperm.

Problem: Inflammation and genital infections promote the increase in leukocytes, pro-inflammatory cytokines, and oxygen reactive species, impairing sperm functions such as motility, capacitation, and acrosome reaction. All these functions are primarily regulated by cytoplasmic concentration of Ca(2+) ([Ca(2+) ]cyto ). This study evaluated the effect of tumor necrosis factor (TNF)-α on the [Ca(2+) ]cyto and its regulation in human sperm.

Rotavirus infection of cells in culture induces activation of RhoA and changes in the actin and tubulin cytoskeleton.

Rotavirus infection induces an increase in [Ca(2+)](cyto), which in turn may affect the distribution of the cytoskeleton proteins in the infected cell. Changes in microfilaments, including the formation of stress fibers, were observed starting at 0.5 h.

Dissecting the Ca²⁺ entry pathways induced by rotavirus infection and NSP4-EGFP expression in Cos-7 cells.

Rotavirus infection modifies Ca(2+) homeostasis provoking an increase in Ca(2+) permeation, cytoplasmic Ca(2+) concentration ([Ca(2+)](cyto)), total Ca(2+) pools and, a decrease of Ca(2+) response to agonists. These effects are mediated by NSP4. The mechanism by which NSP4 deranges Ca(2+) homeostasis is not yet known.

Molecular biology of rotavirus entry and replication.

Rotavirus is a nonenveloped, double-stranded, RNA virus belonging to the Reoviridae family and is the major etiological agent of viral gastroenteritis in young children and young animals. Remarkable progress in the understanding of the rotavirus cycle has been made in the last 10 years. The knowledge of viral replication thus far acquired is based on structural studies, the expression and coexpression of individual viral proteins, silencing of individual genes by siRNAs, and the effects that these manipulations have on the physiology of the infected cell.

Expression of nonstructural rotavirus protein NSP4 mimics Ca2+ homeostasis changes induced by rotavirus infection in cultured cells.

Rotavirus infection modifies Ca(2+) homeostasis, provoking an increase in Ca(2+) permeation, the cytoplasmic Ca(2+) concentration ([Ca(2+)](cyto)), and total Ca(2+) pools and a decrease in Ca(2+) response to agonists. A glycosylated viral protein(s), NSP4 and/or VP7, may be responsible for these effects. HT29 or Cos-7 cells were infected by the SA11 clone 28 strain, in which VP7 is not glycosylated, or transiently transfected with plasmids coding for NSP4-enhanced green fluorescent protein (EGFP) or NSP4.

Heterogeneity of acid secretion induced by carbachol and histamine along the gastric gland axis and its relationship to [Ca2+]i.

The gastric glands of the mammalian fundic mucosa are constituted by different cell types. Gastric fluid is a mixture of acid, alkali, ions, enzymes, and mucins secreted by parietal, chief, and mucous cells. We studied activation of acid secretion using LysoSensor Yellow/Blue in conjunction with fluo 3 to measure changes in pH and Ca(2+) in isolated rabbit gastric glands.

Intracellular disassembly of infectious rotavirus particles by depletion of Ca2+ sequestered in the endoplasmic reticulum at the end of virus cycle.

Rotavirus infection is characterized by a number of Ca(2+) dependent virus-cell interactions. The structure of rotavirus triple-layered particles (TLP) is dependent on Ca(2+) concentration. Acquisition of the capsid outer layer requires a high Ca(2+) concentration inside the ER.

Stomach lysozymes of the three-toed sloth (Bradypus variegatus), an arboreal folivore from the Neotropics.

Lysozymes are antimicrobial defences that act as digestive enzymes when expressed in the stomach of herbivores with pre-gastric fermentation. We studied this enzyme in the complex stomach of the three-toed sloth (Bradypus variegatus), a folivore with pre-gastric fermentation. Lysozymes were identified by SDS-PAGE and immunoblotting in all portions: diverticulum, pouch, glandular and muscular prepyloric area with 14.

Resistance of rumen bacteria murein to bovine gastric lysozyme.

Background: Lysozymes, enzymes mostly associated with defence against bacterial infections, are mureinolytic. Ruminants have evolved a gastric c type lysozyme as a digestive enzyme, and profit from digestion of foregut bacteria, after most dietary components, including protein, have been fermented in the rumen. In this work we characterized the biological activities of bovine gastric secretions against membranes, purified murein and bacteria.

I, 2. Physiology and pathophysiology of the gut in relation to viral diarrhea.

Many advances have been made in the understanding of intestinal electrolyte transport from the molecular to the whole-tissue level. This chapter discusses the molecular mechanisms of intestinal epithelial ion transport processes, as well as the intra- and extracellular factors involved in their regulation, as a framework for the understanding of virus-induced gastroenteritis. Based on the present knowledge of the effects of rotavirus (RV) infection on the physiology of the intestine at different levels of organization, a working model for the pathogenesis of RV diarrhea is presented in the chapter.

Antibodies to rotavirus outer capsid glycoprotein VP7 neutralize infectivity by inhibiting virion decapsidation.

The rotavirus capsid is composed of three concentric protein layers. Proteins VP4 and VP7 comprise the outer layer. VP4 forms spikes, is the viral attachment protein, and is cleaved by trypsin into VP8* and VP5*.