Acta cientifica venezolana最新文献

{"title":"[Simulation through the method of finite element of alendronate in a model of bone remodeling based on damage mechanics].","authors":"María Elvira Zeman,&nbsp;J M García,&nbsp;Manuel Doblaré","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>Mechanical loads are one of the main factors that affect bone remodelling process. This phenomenon is widely applied to the study of prosthetic replacement, for example hip prosthesis. Elderly people are the most common patient to receive a hip replacement surgery. Alendronate is a drug that is being used to increase bone mineral content in patients with poor bone quality. This work uses a mechanical model based on damage mechanics, which considers bone's porosity as the damage variable, a mechanical stimulus associated thermodynamically to this variable, a damage criterion and an evolution damage law. Our approach simulates the degree of mineralization changes as well as the decrease of BMU activation frequency due to Alendronate doses. The biological changes generated by the drug directly affect the damage's evolution law. As a first approach the two biological parameters to be modeled are the surface of remodelling as well as the degree of mineralization (ash fraction) of the bone. Results show a good correlation with experimental data from alendronate's treatments for short term simulations (1-2 years).</p>","PeriodicalId":75378,"journal":{"name":"Acta cientifica venezolana","volume":"54 1","pages":"36-42"},"PeriodicalIF":0.0,"publicationDate":"2003-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"40828808","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"[Factors involved in coastal lagoons formation in Colombian southwest Caribbean].","authors":"Ricardo Alvarez-León,&nbsp;Luis Alberto Mendoza-Mazzeo,&nbsp;Georges Vernette","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>Based on origin, geomorphological evolution and environmental characteristics, four of the main types of coastal lagoons were identified in colombian southwest Caribbean. The following are examples of each type: (1) Terrigenous sediment inputs in delta environment (Lagoons from Sinu River Delta, Cordoba Department), (2) Shore sand bars in coastal flat (Tesca Lagoon, Bolivar Deparment), (3) bar built by organisms such as coral reefs, (Isla Grande Lagoons, Bolivar Deparment) and, (4) bars controlled by tectonism (Cartagena Bay, Bolivar Deparment).</p>","PeriodicalId":75378,"journal":{"name":"Acta cientifica venezolana","volume":"54 3","pages":"180-8"},"PeriodicalIF":0.0,"publicationDate":"2003-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41008807","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"[Participation of dexamethasone and E and C vitamins in the modulation of the hepatotoxic effect induced by fomesafen and 2,4-D amino herbicides, in rats ].","authors":"Luz Orfila,&nbsp;Solangela Mendoza,&nbsp;Jesús Rodríguez,&nbsp;Francisco Arvelo","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>The fomesafen and 2,4-D amine herbicide induce cytotoxic effects at hepatic level in rats, such as: hepatomegaly, hyperplasia and increase in the enzymes activity which participate in the processes of peroxisomal beta-oxidation of fatty acids. In this work, the effect of vitamin E and C was evaluated, as well as, the dexamethasone in the modulation of these hepatotoxic effects. Sprague-Dawley rats were treated with the herbicides and with the agents to be evaluated. The different treatments were given during 15 days orally route. The herbicides combined with the dexamethasone and antioxidant agents were administrated only and simultaneously with the herbicides. Once concluded the different treatment, the rats were weighed and sacrificed. It was evaluated the liver size and liver fragments were obtained to determine the enzymatic activity of Fatty Acyl CoA-oxidase (FACO) and cellular number. The results showed that the hepatomegaly induced by fomesafen was inhibited by the vitamins and by the dexamethasone, while any effect was not observed in the group of rats treated with 2,4-D amine. None of the agents modulated the FACO activity induced by herbicides in treated rats. However, the dexamethasone showed a protective effect in the hyperplasia induced by two herbicides. The hepatotoxic effects induced by the herbicides responded to a different mechanism due to the differences of the effects observed at the antioxidant agents. On the other hand, the inhibition of the cellular proliferation by the dexamethasone does not keep relation with the responsible mechanisms of inducing the oxidant stress into FACO activity. Under experimental conditions of this study, the use of these agents does not guarantee protection against the hepatotoxic effects induced by the herbicides.</p>","PeriodicalId":75378,"journal":{"name":"Acta cientifica venezolana","volume":"53 1","pages":"60-5"},"PeriodicalIF":0.0,"publicationDate":"2002-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"21978027","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"[The tongue mast cells of Bufo marinus L. toad: characterization of glycoconjugates with conventional and lectin methods].","authors":"Miren Alatzne González-Elorriaga,&nbsp;Gloria Canepa","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>Mast cell populations in mammals have been recognized as morphologically and functionally heterogeneous. In situ characterization of these cell type carbohydrates with conventional histochemical techniques and with lectin histochemistry has not been afforded in amphibian species. Different conventional staining methods for complex carbohydrates and 18 different, biotin or peroxidase conjugated, lectins were used in paraffin embedded Rossman fluid-fixed sections of mid-central region of the toad tongue. Conventional carbohydrate histochemistry showed a single type of mast cells with a variable concentration of highly sulphated glycosaminoglycans. Lectin histochemistry showed partial heterogeneity in the mast cell population. Most cells contain N-linked and O-linked oligosaccharides with variable quantities of Man but high of GlcNAc and terminal Gal-beta (1,3)-GaINAc residues. A considerable number of mast cells showed proteins or oligosaccharides with terminal sialic acid residues but only few mast cells contain terminal fucose. Discussion is made comparing these results with similar histochemical studies and with functional experimental studies performed in human and rat mast cells.</p>","PeriodicalId":75378,"journal":{"name":"Acta cientifica venezolana","volume":"53 3","pages":"183-94"},"PeriodicalIF":0.0,"publicationDate":"2002-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"22309371","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"[Comparative studies of oat cultivars from Southern Brazil: effect of grain morphology on industrial yield].","authors":"Alicia de Francisco,&nbsp;Rosane Costa Beber,&nbsp;R Gary Fulcher,&nbsp;Tom Medin,&nbsp;Antonio Carlos Alves","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>The purpose of this work was to study the effect of grain morphology of oats on their industrial yield. The five cultivars studied: CTC3, UFRGS7, UFRGS14, UPF7 and UPF16 were grown in three localities with different soil and climate conditions, for two consecutive years. The parameters evaluated in the oat samples before and after dehulling were grain size and shape (by image analysis), comparing them to industrial yield, weight of a thousand kernels and hectoliter weight. The results showed that image analysis of oat samples (with hulls), does not have any relation to industrial yield, different from what was observed with groat samples (dehulled). Industrial yield varied according to genotype, locality and year, while area, minimum and maximum diameters and grain shape were only affected by the genetic factor. It was observed that longer grains (UPF16) had the highest industrial yield, differently to rounder and shorter grains (UFRGS14) which had a lower yield due to the ease of breakage during hulling; the smallest grains also gave a low industrial yield.</p>","PeriodicalId":75378,"journal":{"name":"Acta cientifica venezolana","volume":"53 3","pages":"195-201"},"PeriodicalIF":0.0,"publicationDate":"2002-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"22309372","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Enhancement of insulin secretory response to glucose-dependent insulinotropic polypeptide (GIP) by growth hormone in dogs.","authors":"José Pierluissi,&nbsp;Raiza de Pierluissi,&nbsp;Angela de Martínez","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>In the present work we examined the incretin role of gut glucose-dependent insulinotropic polypeptide (GIP) in the insulin over-response to meal ingestion found in states of hypersomatotrophism. In this context, we studied IRI secretion after i.v. infusion of glucose alone (0.6 g/kg/h) and also combined with GIP (0.4 microgram/kg/h) in dogs during the control period and after subcutaneous administration of bovine growth hormone (bGH, 1 mg/kg), in randomized experiments at fortnightly intervals. Plasma levels of immunoreactive b-GH (IR-bGH) showed a comparable elevation at 24 h from each bGH injection. Coinciding with this rise, fasting plasma glucose was within the normal range and basal plasma levels of immunoreactive GIP (IR-GIP) remained unchanged. When GIP was given, there was a significant increase in IR-GIP plasma levels after 10 min of infusion, to a plateau near 200 pmol/l; the values were not influenced by concurrent administration of glucose with or without prior treatment with bGH. In the control observations, glucose infusion caused an insulin response area (IRA, pmol.min.l-1) of 3150 +/- 733. When GIP was co-infused with glucose, the IRA was enhanced to 6203 +/- 1380, p < 0.005. After the administration of bGH, the infusion of glucose alone increased the IRA to 9580 +/- 1446 (p < 0.001) and to 15,906 +/- 2943 (p < 0.001) when GIP was co-infused with glucose. The data suggest that in this state of high circulating levels of growth hormone of short duration, the secretion of insulin in response to the stimulus of glucose alone and also combined with GIP is clearly enhanced. The findings therefore lend support for the explanation of the high insulin secretion evoked by food intake in growth hormone-treated dogs.</p>","PeriodicalId":75378,"journal":{"name":"Acta cientifica venezolana","volume":"53 1","pages":"29-35"},"PeriodicalIF":0.0,"publicationDate":"2002-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"21977444","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"[Leishmania major lipophosphoglycan modulates the expression of receptors involved in parasite internalization in skin Langerhans cells].","authors":"Alicia Ponte-Sucre,&nbsp;Anabel Scharner,&nbsp;Heidrun Moll","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>Despite the immunological changes recognized to be produced during Leishmania infection and the central role played by Langerhans cells, it is not known whether Leishmaina lipophosphoglycan, the most abundant glycolipid on the parasite surface, affects the functions of Langerhans cells. Here, we provide evidence that exposure of Langerhans cells to Leishmaina (L.) major lipophosphoglycan has consequences for the expression of surface receptors. Down-regulation of receptors involved in host cell-parasite interaction are observed after 4 h exposure of Langerhans cells to lipophosphoglycan. Many of the changes are also induced in Langerhans cells incubated with L. major-conditioned medium, indicating that the observed effects may be mediated by soluble factors released by the parasite into the culture, as it is the case for the carbohydrate moiety of lipophosphoglycan. Taken together, these results indicate that the changes in surface molecule expression induced by the exposure of Langerhans cells to lipophosphoglycan might reflect changes in their signalling functions from the infected skin.</p>","PeriodicalId":75378,"journal":{"name":"Acta cientifica venezolana","volume":"53 3","pages":"218-24"},"PeriodicalIF":0.0,"publicationDate":"2002-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"22308149","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Cocaine long-term administration induces myocardial depressant effects and adrenoceptors desensitization.","authors":"Eduardo Romero Vecchione,&nbsp;José Vázquez,&nbsp;Mélida Bermudez,&nbsp;Domingo Negrín,&nbsp;Rafael Antequera","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>Cocaine as a drug of abuse can cause many cardiovascular toxic effects. The objective of this work was to study the mechanism of the negative inotropic effect of cocaine on isolated right ventricle strips and its relationship with myocardial catecholamines desensitization after long- term cocaine administration. Right ventricle strips were incubated in oxygenated Krebs solution at 37 degrees C, and driven with 2 ms, 15 mA, 1.8 Hz electric square pulses. Beat tension force was recorded with a force-displacement transducer. In control long-term saline (0.9% NaCl) treated rats (0.1 mL/Kg x 15 days, s.c.), in vitro 0.1-30 microM cocaine progressively increased the ventricle strip force up to 53% over baseline value. On the contrary, a negative inotropic effect of cocaine was observed in strips obtained from long-term cocaine treated rats (3 mg/Kg x 15 days, s.c.). The contractile force change (\"Bowditch\" phenomenon) induced by short (30s) rising of myocardial stimulating frequency to 2.7, 3.5 and 4.3 Hz respectively, was completely reversed in ventricular strips obtained from long-term cocaine treated rats. Myocardial desensitization to isoproterenol (saline 4.67 nM Vs cocaine 13.17 nM DE50) and to phenylephrine (saline 5.44 nM Vs cocaine 8.6 nM DE50) was observed in long term cocaine treated rats when compared to the control group. Aorta desensitization to phenylephrine-induced constriction in long-term cocaine treated rats was also observed; phenylephrine DE50 increased from 1.9 nmol/l in control rats to 15.5 nmol/l in long-term cocaine treated ones. Cocaine metabolites, benzoylecgonine and ecgonine methyl ester were excreted (121.6 micrograms/ml) in urine samples from all cocaine treated rats and not in the saline treated group. Long-term cocaine treatment seems to interfere with the cytosolic calcium increase that normally occurs during systole; this could explain its negative inotropic effect observed during in vitro cocaine reexposure. The adrenergic receptor desensitization induced by chronic cocaine administration could lead to a full expression of the negative inotropic effect of this drug. Extrapolated to clinical grounds, this mechanism could explain some clinical cases of heart failure reported in cocaine overdosed addicts.</p>","PeriodicalId":75378,"journal":{"name":"Acta cientifica venezolana","volume":"53 3","pages":"225-31"},"PeriodicalIF":0.0,"publicationDate":"2002-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"22308150","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"[Morphology and anatomy od the development of the anthocarp and fruit of Pisonia aculeata L. (Nyctaginaceae)].","authors":"Sônia M da Rosa,&nbsp;Luiz A de Souza,&nbsp;Ismar S Moscheta","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>Pisonia aculeata L. is a widespread species that occurs frequently in tropical and subtropical forests in the South of Brazil. This paper presents a morphological and anatomical study of the development of its anthocarps and the fruits. Flowers in pre and post anthesis and fruits in different stages of development were collected in the Horto Florestal of Maringá, Paraná State, Brazil. The anthocarp originates in the perigone and it can be characterized by the presence of an uniseriate epidermis on the abaxial surface, presence of glandular emergences, a glabrous epidermis on the adaxial surface and a parenchymatous mesophyll. This last tissue presents a great number of cellular strata due to the action of a ventral meristema installed still in the perigone phase. The pericarp develops from the wall of the ovary. The ovule is anatropous, bitegmic and crassinucellate. The mature seed presents a thin testa with thickened cell walls just in the rafe region, perisperm and endosperm with nuclear origin, without development of tegmen. The anthocarp has great importance in the process of dispersion of this species (epizoochory). This study confirms that the fruit is an achene and not a caryopsis as affirmed in the literature.</p>","PeriodicalId":75378,"journal":{"name":"Acta cientifica venezolana","volume":"53 4","pages":"245-50"},"PeriodicalIF":0.0,"publicationDate":"2002-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"22552328","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"[Suggestive evidences for a microanatomical relationship between mast cells and nerve in the tongue of the toad Bufo marinus demonstrated by means of high resolution light microscopy].","authors":"Miren Alatzne González-Elorriaga,&nbsp;Gloria Canepa","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>Mast cells are connective tissue cells, present in all vertebrates and characterized by the metachromatic stain of their granules. Nowadays mast cells have been recognized as a potent cellular source of multiple cytokines, suggesting an important role in immunoregulation and host defense. These cells have been described as preferentially located around blood vessels but more recently close spatial relationship between mast cells and nerves has been reported mostly in mammalian species. The microanatomy of nerve tissue and associated mast cells in the toad Bufo marinus tongue have been studied here by means of high resolution light microscopy. Mast cell population was identified by the metachromatic staining of their cytoplasm granules in Epon embedded semithin sections counterstained with Toluidine Blue and Azure A. Numerous mast cells were observed scattered throughout the submucosal region, adjacent and/or within of nerve bundles and nerve ganglia, near skeletal muscle fibers and adjacent of blood vessels. Additionally, mast cells adjacent to single but conspicuous myelinated nerve fibers were seen under endothelia of lymphatic vessels wall and this is apparently a unreported event. Results suggest nerve-mast cell associations are functionally important in the toad tongue.</p>","PeriodicalId":75378,"journal":{"name":"Acta cientifica venezolana","volume":"53 4","pages":"258-65"},"PeriodicalIF":0.0,"publicationDate":"2002-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"22552331","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}