Scielo RSS <![CDATA[Biological Research]]> http://www.scielo.cl/rss.php?pid=0716-976020110003&lang=es vol. 44 num. 3 lang. es <![CDATA[SciELO Logo]]> http://www.scielo.cl/img/en/fbpelogp.gif http://www.scielo.cl <![CDATA[<strong>Protective effect of <i>Hypericum calabricum </i>Sprengel on oxidative damage and its inhibition of nitric oxide in lipopolysaccharide-stimulated RAW 264.7 macrophages</strong>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-97602011000300001&lng=es&nrm=iso&tlng=es The present study shows for the first time the phenolic composition and the in vitro properties (antioxidant and inhibition of nitric oxide production) of Hypericum calabricum Sprengel collected in Italy. The content of hypericins (hypericin and pseudohypericin), hyperforin, flavonoids (rutin, hyperoside, isoquercetrin, quercitrin, quercetin and biapigenin) and chlorogenic acid of H. calabricum, have been determined. The ethyl acetate fraction from the aerial parts of H. calabricum exhibited activity against the radical 1,1-diphenyl-2-picrylhydrazyl (DPPH) with IC50 value of 1.6 jig/ml. The test for inhibition of nitric oxide (NO) production was performed using the murine monocytic macrophage cell line RAW 264.7. The ethyl acetate fraction had significant activity with an IC50 value of 102 jig/ml and this might indicate that it would have an anti-inflammatory effect in vivo. <![CDATA[<strong>Mechanical ventilation and volutrauma</strong>: <strong>study <i>in vivo </i>of a healthy pig model</strong>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-97602011000300002&lng=es&nrm=iso&tlng=es Mechanical ventilation is essential in intensive care units. However, it may itself induce lung injury. Current studies are based on rodents, using exceptionally large tidal volumes for very short periods, often after a "priming" pulmonary insult. Our study deepens a clinically relevant large animal model, closely resembling human physiology and the ventilator setting used in clinic settings. Our aim was to evaluate the pathophysiological mechanisms involved in alveolo/capillary barrier damage due to mechanical stress in healthy subjects. We randomly divided 18 pigs (sedated with medetomidine/tiletamine-zolazepam and anesthetised with thiopental sodium) into three groups (n=6): two were mechanically ventilated (tidal volume of 8 or 20 ml/kg), the third breathed spontaneously for 4 hours, then animals were sacrificed (thiopental overdose). We analyzed every 30' hemogasanalysis and the main circulatory and respiratory parameters. Matrix gelatinase expression was evaluated on bronchoalveolar lavage fluid after surgery and before euthanasia. On autoptic samples we performed zymographic analysis of lung, kidney and liver tissues and histological examination of lung. Results evidenced that high Vt evoked profound alterations of lung mechanics and structure, although low Vt strategy was not devoid of side effects, too. Unexpectedly, also animals that were spontaneously breathing showed a worsening of the respiratory functions. <![CDATA[<strong>Testis-mediated gene transfer in mice</strong>: <strong>comparison of transfection reagents regarding transgene transmission and testicular damage</strong>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-97602011000300003&lng=es&nrm=iso&tlng=es Testis-mediated gene transfer (TMGT) has been used as in vivo gene transfer technology to introduce foreign DNA directly into testes, allowing mass gene transfer to offspring via mating. In this study, we used plasmid DNA (pEGFP-N1) mixed with dimethylsulfoxide (DMSO), N,N-dimethylacetamide (DMA) or liposome (Lipofectin) in an attempt to improve TMGT. Males receiving consecutive DNA complex injections were mated to normal females to obtain F0 progeny. In vivo evaluation of EGFP expression, RT-PCR and PCR were used to detect the expression and the presence of exogenous DNA in the progeny. We also evaluated possible testicular damage by histological procedures. PC R and RT-PCR analyses revealed that liposome and DMSO increased the rate of TMGT. Histological analyses demonstrated that repeated (4 times) injections of DNA complexes can affect spermatogenesis. DMSO was the most deleterious among the reagents tested. In this study, we detected the presence of transgene in the progeny, and its expression in blood cells. Consecutive injections of DNA complexes were associated with impaired spermatogenesis, suggesting requirement of optimal conditions for DNA delivery through TMGT. <![CDATA[<strong>Association of the infusion of <i>Heteropterys aphrodisiaca </i>and endurance training brings spermatogenetic advantages</strong>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-97602011000300004&lng=es&nrm=iso&tlng=es The species Heteropterys aphrodisiaca is commonly used as a stimulant by popular medicine in the Cerrado, a savanna-like biome, Brazil. Recent studies have proved its protective effects on testes of animals submitted to treatment using Cyclosporine A, as well as its stimulus effect in increasing testosterone secretion. Therefore, the present study was designed to analyze whether the association of the plant infusion and endurance exercise could potentiate the stimulating effect. The animals were separated into 4 groups: two control (sedentary and trained) receiving water and two treated (sedentary and trained) receiving the plant infusion daily (104mg/day). The proportion of the seminiferous tubule compartment and interstitium was analyzed. Within the seminiferous epithelium, the number of Sertoli and germ cells were counted in order to evaluate whether the treatment would alter the spermatogenic dynamics, analyzing: the spermatogenic yield, the mitotic and meiotic indexes, the total number of germ cells and the Sertoli cell support capacity. Trained and treated animals showed increased spermatogenic yield and spermatogonia mitosis, and no significant differences in apoptotic indexes. Despite the results showing the same pattern regarding yield and mitotic index, the meiotic index was higher in the sedentary/treated group. Therefore, the H. aphrodisiaca infusion increased both the testosterone production and the spermatogonia mitosis, thus increasing the spermatogenic yield. <![CDATA[<strong>Effect of the standardized <i>Cimicifuga foetida </i>extract on Hsp 27 expression in the MCF-7 cell line</strong>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-97602011000300005&lng=es&nrm=iso&tlng=es Cimicifuga foetida, an Asian Cimicifuga species, has been employed as a cooling and detoxification agent in traditional Chinese medicine since ancient times. For this herb, two cycloartane triterpene glycosides isolated from the rhizomes have demonstrated cytotoxicity on rat tumor and human cancer cell lines. Since human Hsp27 is increased in various human cancers and exhibits cytoprotective activity that affects tumorigenesis and the susceptibility of tumours to cancer treatment, the purpose of this research was to study the expression of this protein in MCF-7 breast cancer cells. To accomplish this aim, MCF-7 cells were exposed to different concentrations of Cimicifuga foetida extract showing a reduction in cell number measured by the sulforhodamine assay. In addition, the expression of Hsp-27 mRNA detected by RT-PCR and Hsp-27 protein detected by immnofluorescence was present in all conditions, except when using the highest concentration of Cimicifuga foetida extract (2,000 jig /L). We conclude that Hsp 27 expression at 2,000 jig /L Cimicifuga foetida extract is diminished. This is the first report showing the Hsp-27 expression after exposure to Cimicifuga foetida extract in MCF-7 cells. <![CDATA[<strong>Insulin signaling proteins in pancreatic islets of insulin-resistant rats induced by glucocorticoid</strong>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-97602011000300006&lng=es&nrm=iso&tlng=es Chronic administration of glucocorticoids induces insulin resistance that is compensated by an increase in p-cell function and mass. Since insulin signaling is involved in the control of p-cell function and mass, we investigated the content of insulin pathway proteins in pancreatic islets. Rats were made insulin resistant by daily administration of dexamethasone (1mg/kg, b.w., i.p.) for 5 consecutive days (DEX), whilst control rats received saline (CTL). Circulating insulin and insulin released from isolated islets were measured by radioimmunoassay whereas the content of proteins was analyzed by Western blotting. DEX rats were hyperinsulinemic and exhibited augmented insulin secretion in response to glucose (P < 0.01). The IRa-subunit, IRS-1, Shc, AKT, p-p70S6K, ERK1/2, p-ERK1/2, and glucocorticoid receptor protein levels were similar between DEX and CTL islets. However, the IRp-subunit, p-IRp-subunit, IRS-2, PI3-K, p-AKT and p70S6K protein contents were increased in DEX islets (P < 0.05). We conclude that IRS-2 may have a major role, among the immediate substrates of the insulin receptor, to link activated receptors to downstream signaling components related to islet function and growth in this insulin-resistant rat model. <![CDATA[<strong>Rat dorsal prostate is necessary for vaginal adhesion of the seminal plug and sperm motility in the uterine horns</strong>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-97602011000300007&lng=es&nrm=iso&tlng=es The rat prostate comprises dorsal, ventral and lateral lobes that are morphologically and biochemically distinct. Lesions to these structures are expected to affect the quality of the ejaculate and male fertility. In experiment 1, we analyzed ejaculate parameters of males that had chemical lesions of the dorsal or ventral lobes. At pre-lesion and at 5 and 20 days post-lesion males were mated, and after ejaculation, seminal fluid and seminal plug were obtained from the mated females. In experiment 2, the ventral lobes were ablated, and the ejaculate was analyzed. In experiment 3, the fertility of males with chemically-lesioned dorsal lobes or ablation of the ventral lobes was evaluated. Chemical lesion of the dorsal lobe prevented the adhesion of the seminal plug to vaginal walls. When these males were tested at 5-days postlesion, no sperm were found in uterus, and at 20-days post-lesion, the few sperm encountered showed slow progressive motility. None of the females that mated with dorsal lobe-lesioned males became pregnant. However, chemical lesion or ablation of the ventral lobes did not affect ejaculate or fertility. Our results indicate that the dorsal prostatic lobes are indispensable for reproductive success in males, and define parameters of ejaculate with which fertility can be estimated. <![CDATA[<strong>The subsidiary GntII system for gluconate metabolism in <i>Escherichia coli</i></strong>: <strong>Alternative induction of the <i>gntV </i>gene</strong>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-97602011000300008&lng=es&nrm=iso&tlng=es Two systems are involved in the transport and phosphorylation of gluconate in Escherichia coli. GntI, the main system, consists of high and low-affinity gluconate transporters and a thermoresistant gluconokinase for its phosphorylation. The corresponding genes, gntT, gntU and gntK at 76.5 min, are induced by gluconate. GntII, the subsidiary system, includes IdnT and GntV, which duplicate activities of transport and phosphorylation of gluconate, respectively. Gene gntV at 96.8 min is divergently transcribed from the idnDOTR operon involved in L-idonate metabolism. These genetic elements are induced by the substrate or 5-keto-D-gluconate. Because gntV is also induced in cells grown in gluconate, it was of interest to investigate its expression in this condition. E. coli gntK, idnOokan mutants were constructed to study this question. These idnO kan-cassete inserted mutants, unable to convert gluconate to 5-keto-D-gluconate, permitted examining gntV expression in the absence of this inducer and demonstrating that it is not required when the cells grow in gluconate. The results suggest that E. coli gntV gene is alternatively induced by 5-keto-D-gluconate or gluconate in cells cultivated either in idonate or gluconate. In this way, the control of gntV expression would seem to be involved in the efficient utilization of these substrates. <![CDATA[<strong><i>tlpA </i></strong><strong>gene expression is required for arginine and bicarbonate chemotaxis in <i>Helicobacter pylori</i></strong>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-97602011000300009&lng=es&nrm=iso&tlng=es About half of the human population is infected with Helicobacter pylori, a bacterium causing gastritis, peptic ulcer and progression to gastric cancer. Chemotaxis and flagellar motility are required for colonization and persistence of H. pylori in the gastric mucus layer. It is not completely clear which chemical gradients are used by H. pylori to maintain its position. TlpA, a chemotaxis receptor for arginine/ bicarbonate, has been identified. This study aimed to find out whether tlpA gene expression is required for the chemotactic response to arginine/bicarbonate. Wild-type motile H. pylori ATCC 700392 and H. pylori ATCC 43504, a strain having an interrupted tlpA gene, were used. Also, a tlpA-knockout mutant of H. pylori 700392 (H. pylori 700-tlpA::cat) was produced by homologous recombination. Expression of tlpA was assessed by a Reverse Transcriptase-Polymerase Chain Reaction (RT-PCR) assay. Chemotaxis was measured as a Relative Chemotaxis Response (RCR) by a modified capillary assay. H. pylori 700392 presented chemotaxis to arginine and sodium bicarbonate. H. pylori 700-tlpA::cat showed neither tlpA gene expression nor chemotaxis towards arginine and bicarbonate. Besides confirming that TlpA is a chemotactic receptor for arginine/bicarbonate in H. pylori, this study showed that tlpA gene expression is required for arginine/bicarbonate chemotaxis. <![CDATA[<strong>Heterogeneous periodicity of drosophila mtDNA</strong>: <strong>new refutations of neutral and nearly neutral evolution</strong>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-97602011000300010&lng=es&nrm=iso&tlng=es We found a consistent 3-site periodicity of the X²9 values for the heterogeneity of the distribution of the second base in relation to the first base of dinucleotides separated by 0 (contiguous), 1, 2, 3 ... 17 (K) nucleotide sites in Drosophila mtDNA. Triplets of X²9 values were found where the first was over 300 and the second and third ranged between 37 and 114 (previous studies). In this study, the periodicity was significant until separation of 2011K, and a structure of deviations from randomness among dinucleotides was found. The most deviant dinucleotides were G-G, G-C and C-G for the first, second and third element of the triplet, respectively. In these three cases there were more dinucleotides observed than expected. This inter-bases correlation and periodicity may be related to the tertiary structure of circular DNA, like that of prokaryotes and mitochondria, to protect and preserve it. The mtDNA with 19.517 bp was divided into four equal segments of 4.879 bp. The fourth sub-segment presented a very low proportion of G and C, the internucleotide interaction was weaker in this sub-segment and no periodicity was found. The maintenance of this mtDNA structure and organization for millions of generations, in spite of a high recurrent mutation rate, does not support the notion of neutralism or near neutralism. The high level of internucleotide interaction and periodicity indicate that every nucleotide is co-adapted with the residual genome. <![CDATA[<strong>Habituation of the eyeblink response in humans with stimuli presented in a sequence of incremental intensity</strong>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-97602011000300011&lng=es&nrm=iso&tlng=es In an experiment we examined whether the repeated presentation of tones of gradually increasing intensities produces greater decrement in the eyeblink reflex response in humans than the repetition of tones of constant intensities. Two groups of participants matched for their initial level of response were exposed to 110 tones of 100-ms duration. For the participants in the incremental group, the tones increased from 60- to 90- dB in 3-dB steps, whereas participants in the constant group received the tones at a fixed 90-dB intensity. The results indicated that the level of response in the last block of 10 trials, in which both groups received 90-dB tones, was significantly lower in the incremental group than in the constant group. These findings support the data presented by Davis and Wagner (7) with the acoustic response in rats, but differ from several reports with autonomic responses in humans, where the advantage of the incremental condition has not been observed unambiguously. The discussion analyzes theoretical approaches to this phenomenon and the possible involvement of separate neural circuits. <![CDATA[<strong>Insulin is secreted upon glucose stimulation by both gastrointestinal enteroendocrine K-cells and L-cells engineered with the preproinsulin gene</strong>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-97602011000300012&lng=es&nrm=iso&tlng=es Transgenic mice carrying the human insulin gene driven by the K-cell glucose-dependent insulinotropic peptide (GIP) promoter secrete insulin and display normal glucose tolerance tests after their pancreatic p-cells have been destroyed. Establishing the existence of other types of cells that can process and secrete transgenic insulin would help the development of new gene therapy strategies to treat patients with diabetes mellitus. It is noted that in addition to GIP secreting K-cells, the glucagon-like peptide 1 (GLP-1) generating L-cells share/ many similarities to pancreatic p-cells, including the peptidases required for proinsulin processing, hormone storage and a glucose-stimulated hormone secretion mechanism. In the present study, we demonstrate that not only K-cells, but also L-cells engineered with the human preproinsulin gene are able to synthesize, store and, upon glucose stimulation, release mature insulin. When the mouse enteroendocrine STC-1 cell line was transfected with the human preproinsulin gene, driven either by the K-cell specific GIP promoter or by the constitutive cytomegalovirus (CMV) promoter, human insulin co-localizes in vesicles that contain GIP (GIP or CMV promoter) or GLP-1 (CMV promoter). Exposure to glucose of engineered STC-1 cells led to a marked insulin secretion, which was 7-fold greater when the insulin gene was driven by the CMV promoter (expressed both in K-cells and L-cells) than when it was driven by the GIP promoter (expressed only in K-cells). Thus, besides pancreatic p-cells, both gastrointestinal enteroendocrine K-cells and L-cells can be selected as the target cell in a gene therapy strategy to treat patients with type 1 diabetes mellitus.