Protein kinase C is required for the disappearance of MPF upon artificial activation in mouse eggs

The aim of the present study was to investigate the implication of protein kinase C (PKC) in the mouse egg activation process. We used OAG (1-oleoyl-2-acetyl-sn-glycerol) as a PKC activator, calphostin C as a specific PKC inhibitor, and the calcium ionophore A23187 as a standard parthenogenetic agent. The exposure of zona-free eggs to 150 microM or 50 microM OAG for 10 min resulted in meiosis II completion in approximately 80% of instances. By contrast, at a lower concentration (25 microM), the PKC stimulator was ineffective as parthenogenetic agent. Shortly after the application of 150 microM OAG, the cytosolic Ca2+ concentration ([Ca2+]i) increased transiently in all the eggs examined, whereas after the addition of 50 microM OAG, [Ca2+]i remained unchanged for at least 20 min. During this period, the activity of M-phase promoting factor (MPF) dramatically decreased and most of the eggs entered anaphase except when the PKC was inhibited by calphostin C. Similarly, MPF inactivation and meiosis resumption were prevented in calphostin C-loaded eggs following treatment with A23187, even though the ionophore-induced Ca2+ signalling was not affected. Taken together, our results indicate that stimulation of PKC is a sufficient and necessary event to induce meiosis resumption in mouse eggs and strongly suggest that, in this species, the mechanism by which a transient calcium burst triggers MPF inactivation involves a PKC-dependent pathway.     

Oral administration of arginine enhances the growth hormone response to growth hormone releasing hormone in short children

We have evaluated the effect of oral administration of arginine chlorhydrate on the growth hormone response to growth hormone releasing hormone in a group of nine short prepubertal children (six boys and four girls). Arginine chlorhydrate 10 g, administered orally 60 min before an i.v. bolus injection of growth hormone releasing hormone 1-29, 1 microgram/kg, significantly enhanced the growth hormone response to the neuropeptide, confirming the results of previous studies which used the i.v. route. Furthermore, our data strengthen the view that the effects of arginine chlorhydrate on growth hormone secretion are mediated by inhibition of endogenous somatostatin release.     

Release of the mitogen lysophosphatidylinositol from H-Ras-transformed fibroblasts; a possible mechanism of autocrine control of cell proliferation

Lysophosphatidylinositol (LysoPtdIns) is formed by a constitutively-active phosphoinositide-specific phospholipase A2 in Ras-transformed cells and can stimulate cell proliferation. To evaluate whether LysoPtdIns could function as an autocrine modulator of cell growth, we examined whether LysoPtdIns can be released in the medium of Ras-transformed FRT-Fibro fibroblasts and thyroid cells. Here, we report that LysoPtdIns accumulates in the extracellular space of these lines and reaches levels up to tenfold higher than in the case of normal cells. Moreover, the ionophore A23187 increased the levels of the lysolipid in the extracellular medium. Extracellular LysoPtdIns was rapidly hydrolyzed to inositol 1:2-cyclic phosphate. LysoPtdIns induced thymidine incorporation in FRT-Fibro Ha-Ras fibroblasts, whereas inositol cyclic 1:2-cyclic phosphate did not affect cell growth per se, nor did it interfere with the LysoPtdIns mitogenic activity. We hypothesize that in Ras-transformed fibroblasts the formation and release of LysoPtdIns may function as an autocrine mechanism that participates in the Ras-dependent stimulation of cell growth.     

Differentiation of HL-60 promyelocytic leukemia cells is accompanied by a modification of magnesium homeostasis

The concentrations of ammonia in the plasma of the mudskipper Boleophthalmus boddaerti exposed to cyanide for 1-6 days were significantly greater than the respective values of the controls. This was due to an increase in the production of NH3 in the muscle and an increase in the retention of NH3 and/or NH4+ in the blood of the cyanide-exposed fish when compared to controls. Cyanide exposure significantly increased the specific activity of muscle AMP deaminase. Since adenylosuccinate synthetase and lyase were also present in the muscle, exposure to cyanide might increase the production of NH3 from the catabolism of purine nucleotides. B. boddaerti exposed to cyanide excreted significantly less ammonia than the control fish. Results indicate changes in the permeability of the epithelial surfaces of the cyanide-exposed fish to NH3 and/or NH4+. Since the tissues and organs needed time to activate the inducible cyanide detoxification mechanisms, the increase in the production of NH3 might be an important defensive mechanism for B. boddaerti during the early phase of cyanide exposure.     

BashDungeon

We present here the first of a series of video-games designed for teaching fundamentals of computer science to university students. We built the game as an adventure inside a dungeon, which aims at reproducing the topology of a Unix file system. Inside the different rooms, the players can learn how to use several Unix commands, from simple file system actions to complex text manipulations, to complete the quests and win the game. We performed a user test on a class of B.Sc. students at the University of Cagliari. The results show a good acceptance of the game metaphor and its effectiveness in supporting the learning process. We plan to expand this game and to design similar games for teaching object-oriented programming and algorithms and data structures.

     

Real-Time Deformation with Coupled Cages and Skeletons

Skeleton-based and cage-based deformation techniques represent the two most popular approaches to control real-time deformations of digital shapes and are, to a vast extent, complementary to one another. Despite their complementary roles, high-end modelling packages do not allow for seamless integration of such control structures, thus inducing a considerable burden on the user to maintain them synchronized. In this paper, we propose a framework that seamlessly combines rigging skeletons and deformation cages, granting artists with a real-time deformation system that operates using any smooth combination of the two approaches. By coupling the deformation spaces of cages and skeletons, we access a much larger space, containing poses that are impossible to obtain by acting solely on a skeleton or a cage. Our method is oblivious to the specific techniques used to perform skinning and cage-based deformation, securing it compatible with pre-existing tools. We demonstrate the usefulness of our hybrid approach on a variety of examples.     

Autonomic dysfunction and upper digestive functional disorders in untreated adult coeliac disease

There is recent evidence that upper-gut motor abnormalities may be present in coeliac disease. However, to date, the pathophysiological mechanisms responsible for the above have not been explored. The purpose of the present study was to investigate upper-gut motor activity in coeliac disease and explore the role played by the autonomic nervous system in motility disturbances. Thirty untreated adult coeliac patients were recruited into the study. Oesophageal manometry and cardiovascular autonomic tests were performed in all patients; oesophageal pH-metry was carried out in 20 patients, gastrointestinal manometry in eight and scintigraphic gastric emptying in 13. Oesophageal motor abnormalities were detected in about 50% of patients, pH-metry was abnormal in 30% of them, and up to 75% of coeliac patients displayed gastrointestinal motility alterations. Delayed gastric emptying was documented in about 50% of patients and was correlated with manometric post-prandial hypomotility. Autonomic tests were positive in 45% of patients as a group, and reached pathological score in 19% of them. Autonomic score correlated significantly with the percentage of bi-peaked waves and with the number of fasting intestinal clusters. This study confirms that upper-gut motor abnormalities are frequently present in adult coeliac disease. Extrinsec autonomic neuropathy may play a role, although other pathophysiological mechanisms are likely to occur.     

Hydrogen peroxide decreases pHi in human aortic endothelial cells by inhibiting Na+/H+ exchange

Postischemic endothelial dysfunction may occur as a result of the effects of endogenous oxidants like hydrogen peroxide. Since endothelium-dependent vasodilator function may be affected by pHi, the effect of hydrogen peroxide on endothelial pHi was examined. Hydrogen peroxide (100 micromol/L for 10 minutes) decreased pHi from 7.24+/-0.01 to 7.02+/-0.02 and inhibited recovery from an ammonium chloride-induced intracellular acid load in carboxy SNARF 1 (c-SNARF 1)-loaded human aortic endothelial cells in bicarbonate-free solution. Prior inhibition of Na+/H+ exchange with 5-(N-ethyl-N-isopropyl)amiloride (10 micromol/L), by removal of extracellular Na+, or by glycolytic inhibition with iodoacetic acid blocked the subsequent effect of hydrogen peroxide on pHi. A 2-minute exposure to 100 micromol/L H2O2 decreased intracellular ATP levels by approximately 40%; this was prevented by 3-aminobenzamide and nicotinamide (1 mmol/L each), inhibitors of the DNA repair enzyme poly(ADP-ribose) polymerase. Both 3-aminobenzamide and nicotinamide significantly inhibited the hydrogen peroxide-induced intracellular acidification and the effect of hydrogen peroxide on recovery from an intracellular acid load. Hydrogen peroxide decreases pHi in human endothelial cells by inhibiting Na+/H+ exchange. This appears to be mediated by activation of the DNA repair enzyme poly(ADP-ribose) polymerase and subsequent depletion of intracellular ATP. Since a decrease in pHi in this range may alter the activity of NO synthase or affect the synthesis of vasodilator prostaglandins, the effect of hydrogen peroxide on the endothelial Na+/H+ exchanger may be important in the pathogenesis of postischemic endothelial dysfunction.     

Characterization of Fiore Sardo cheese manufactured with the addition of autochthonous cultures

This work evaluated the effect of adjunct autochthonous cultures on the chemical, microbiological and sensory characteristics of Fiore Sardo cheese during ripening. A total of twelve batches of cheeses were manufactured according to the technical Disciplinary of Fiore Sardo cheese, with and without different combinations of autochthonous strains isolated from the native microflora of artisanal Fiore Sardo. There were no significant differences in the cheese compositional parameters between experimental and control cheeses, but the addition of cultures led to a statistically significant decrease in pH values in experimental cheeses. The evolution of total mesophilic bacteria, total coliforms and lactic acid bacteria were significantly influenced by the addition of autochthonous cultures in most of the experimental cheeses. As for sensory characteristics, all the experimental cheeses reported significantly higher scores especially for shape, texture, interior openings, taste and aftertaste. This study demonstrated the beneficial effect of the addition of selected autochthonous cultures in accelerating the disappearance of undesirable flora and improving the typical sensory characteristics of the cheese, and confirmed the importance of ewes' milk as a source of technologically interesting strains that could be used to ensure a higher quality of artisanal cheese productions.