Effect of insulin on triacylglycerol synthesis and secretion by chicken hepatocytes in primary culture

Organophosphates are the most widely used pesticides throughout the world. The considerable amount brought out to the environment poses a risk on the whole population. As organophosphates are neurotoxic substances and their residues can persist in the environment for several weeks, their influence on the nervous system of humans and animals is of principal interest. In the present study, we investigated the alterations induced by dichlorvos, a common pesticide substance, in parameters of somatosensory evoked potentials and hippocampal evoked population spikes of rats. The changes of the cortical vs. hippocampal evoked responses were opposite and only hippocampal effects could be directly explained through an increased cholinergic activity.     

Study of Undersaturated C60 Solutions in Cs2 by Small Angle Neutron Scattering

We measured precisely, using the Small Angle Neutron Scattering (SANS) technique, the radius of the carbon nuclei shell of the C₆₀ molecule, in spite of its small value. For this purpose, controlled undersaturated solutions of C₆₀ in CS₂, where theC₆₀ molecules are individually distributed, were studied in the room temperature range. Absolute measurements also allowed us to extract from the contrast in scattering length the partial molecular volume of the molecule C₆₀ in solution in CS2.     

Intraepithelial carcinoma of the cervix uteri. 1) Cytologic detection in gynecologic practice. Our exerience with 15,000 smears

The best results in screening for subclinical cancer of the cervix are given by cytological studies. The authors in reviewing their experience in this method of screening studied the result of 15,000 smears which gave a diagnosis of 37 cases of intra-epithelial carcinoma of the cervix, which means 1 case of carcinoma in situ diagnosed in every 400 smears. Although the technique is very simple it has to be carried out according to strict criteria at the time of taking the smear, of fixing it immediately and of staining it. There is a group of patients who are at high risk about the age of forty, when there is a marked influence due to parity. But only a systematic policy will bring about diagnosis of pre-invasive carcinoma in cases where the cervix is clinically healthy. The cytology is usually characteristic, though the diagnosis may be difficult during pregnancy, or when hormone contraception is being used or when there is a trichomonas infection present. This explains why we find false positives in 0.03 per cent of cases in this study and false negatives in 0.03 per cent of cases. Their rarity means that the method is 99.94 per cent reliable. Finally, the cervical smear gives an opportunity for studying the vaginal microbial flora as well as the cyto-hormonal state.     

Real-time software specification and validation with Transnet

The paper presents the executable specification method for real-time (embedded) systems Transnet. The method is based on an extension to Petri nets. A specification is developed by a problem decomposition into a set of parallel processes. Each process is defined by an extended Petri net with functions assigned to transitions, and conditions and time constants assigned to arcs. It is shown that Transnet matches with the characteristics of the intended class of applications. The available specification languages and the internal representation of data which describe the functional as well as nonfunctional requirements are outlined. The advantages of the Petri net-based representation and the possibilities of automatic net analysis and early validation are discussed.     

Analyse des effets thermiques sur le comportement mécanique des bétons destinés aux revêtements de tunnels

Résumé Le problème de la fissuration des revêtements de tunnels en béton non armé, notamment en l'absence de causes externes est étroitement lié aux caractéristiques physico-chimiques du matériau. La connaissance de la cinétique d'hydratation du béton, à partir d'essais quasi-adiabatiques, nous a permis de déterminer le terme source de l'équation classique de Fourier pour le transfert de la chaleur. La résolution de celle-ci se fait à l'aide du module Texo qui simule d'une manière satisfaisante les champs de températures se développant au cours de la fabrication des pièces en béton. La détermination de ces champs de températures nous a conduit à localiser les zones à fortes élévations de température. A partir d'une loi de comportement thermo-élastique vieillissante, nous déterminons les contraintes qui en résultent. Le résultat, en terme de contraintes, fait appara?tre que la fissuration transversale des revêtements de tunnels en béton non armé est pratiquement inéluctable et surtout qu'elle est traversante. L'ouverture de ces fissures est notamment dépendante de la présence ou non des hors profils géométriques et du dosage en ciment du béton.

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Summary The use of an unreinforced sectional concrete lining in rock excavated tunnels presently appears to be technically and economically appropriate for ensuring good stability and effective operation. However, this type of structure suffers from systematic crack formation. In the absence of external loads, cracking in this type of lining is closely related to the physico-chemical characteristics of the material and to the environment in which this material is ageing. The phenomenon is worsened by conditions particular to tunnels, viz., on the one hand, the strains hindered by the surrounding ground, and on the other the pre-cast invert; also, the presence of geometric overbreaks can lead to variations in the lining thickness. The importance of the heat and hydration gradients resulting from the above phenomena is demonstrated by field tests. Numerical simulations based on laboratory tests let us assess the resulting stresses. (i) Practically unavoidable transverse crack formation can result from the effects of heat. The width of this type of crack and the frequency depend especially on the outer shape and on the proportion of cement in the concrete. (ii) Surface skin cracking can occur, resulting from the effects of hydration. Checks made in the tunnels investigated revealed the cracks expected from our computations. However, these results, in terms of thermal stresses, should not be overestimated especially bearing in mind the numerical model currently used, which does not consider creep effects during the setting and initial hardening of the concrete.

     

Pregnancy-related modifications of rat myometrial Gs proteins: ADP ribosylation, immunoreactivity and gene expression studies

Previous studies from our laboratory have suggested that post-receptor events at the level of beta-adrenergic receptor-adenylate cyclase interaction could be altered in myometrium by steroid hormones or pregnancy. In this study, we have addressed this question by performing a direct evaluation of rat myometrial Gs proteins at various stages of pregnancy or 24 h after administration of progesterone. In the 50,000 g myometrial plasma membrane fraction, in the presence of 32P-labelled NAD, cholera toxin ribosylated three predominant proteins with apparent molecular masses of 42, 47 and 55 kDa. Western blot analysis using the RM/1 antibody recognized the 42 and 47 kDa cholera toxin ADP-ribosylated bands but not the 55 kDa band. Thus, the 42 and 47 kDa immunoreactive bands were interpreted as being the small (Gs alpha-S) and large (Gs alpha-L) forms of Gs respectively. With a more purified myometrial plasma membrane fraction (105,000 g) an additional minor band of 44 kDa could be observed with both techniques. Treatment of late pregnant rats with 5 mg progesterone resulted in a significant increase in both Gs alpha subunits: +25% and +30% after ADP-ribosylation, +50% and +60% after Western blot analysis for Gs alpha-L and Gs alpha-S respectively. Pretreatment with the antiprogestin RU 486 completely suppressed the effect of progesterone, suggesting that the expression of Gs alpha subunits may be under the control of progesterone. However, changes in the myometrial content of Gs in progesterone-treated rats were not associated with concomitant variations in the steady-state levels of mRNA as demonstrated by Northern blot analysis. These data suggest a post-translational regulation of Gs expression by progesterone. Amounts of ADP-ribosylated Gs showed characteristic changes during the course of pregnancy with a fourfold or threefold increase (P < 0.05) on day 15 versus day 12 or delivery respectively. During pregnancy, or after progesterone administration, myometrial alterations of Gs strongly correlated (r = 0.913, P < 0.01) with the cholera toxin-stimulated adenylate cyclase activity. These findings provide evidence that changes in myometrial amounts of functional Gs i) are controlled by the hormonal status of pregnancy and progesterone and ii) play an important role in the transduction pattern of adenylate cyclase activity during the course of pregnancy.     

The master-slave paradigm with heterogeneous processors

We revisit the master-slave tasking paradigm in the context of heterogeneous processors. We assume that communications are handled by a bus and, therefore, at most one communication can take place at a given time step. We present a polynomial algorithm that gives the optimal solution when a single communication is needed before the execution of the tasks on the slave processors. When communications are required both before and after the processing of the tasks, we show that the problem is strongly NP-complete. In this case, we present a guaranteed approximation algorithm. Finally, we present asymptotically optimal algorithms when communications are required before the processing of each task, or both before and after the processing of each task.     

Gambiertoxin (CTX-4B), purified from wild Gambierdiscus toxicus dinoflagellates, induces Na(+)-dependent swelling of single frog myelinated axons and motor nerve terminals in situ

The effects of gambiertoxin (CTX-4B), purified from the dinoflagellate Gambierdiscus toxicus, were assessed on the morphology of both frog myelinated axons and motor nerve terminals, using confocal laser scanning microscopy. During the action of the toxin (24 and 30 nM), a marked swelling of nodes of Ranvier and motor nerve terminals was observed. The CTX-4B-induced swelling could be prevented by blocking voltage-dependent Na+ channels with tetrodotoxin, and could be partly reversed by an external hyperosmotic solution containing 100 mM D-mannitol. The results suggest that CTX-4B, by modifying voltage-dependent Na+ channels, increases internal Na+ concentration of axons and nerve terminals and consequently induces water influx to compensate such an increase. It is suggested that stimulated transmitter release by CTX-4B, as well as by hyperosmotic dmannitol, contribute also to the swelling of the terminals through an increase in their surface area.