944 resultados para Human reproduction - Toxicology - Experimental studies


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Introduction: Open access publishing is becoming increasingly popular within the biomedical sciences. SciELO, the Scientific Electronic Library Online, is a digital library covering a selected collection of Brazilian scientific journals many of which provide open access to full-text articles. This library includes a number of dental journals some of which may include reports of clinical trials in English, Portuguese and/or Spanish. Thus, SciELO could play an important role as a source of evidence for dental healthcare interventions especially if it yields a sizeable number of high quality reports. Objective: The aim of this study was to identify reports of clinical trials by handsearching of dental journals that are accessible through SciELO, and to assess the overall quality of these reports. Material and methods: Electronic versions of six Brazilian dental Journals indexed in SciELO were handsearched at www.scielo.br in September 2008. Reports of clinical trials were identified and classified as controlled clinical trials (CCTs - prospective, experimental studies comparing 2 or more healthcare interventions in human beings) or randomized controlled trials (RCTs - a random allocation method is clearly reported), according to Cochrane eligibility criteria. Criteria to assess methodological quality included: method of randomization, concealment of treatment allocation, blinded outcome assessment, handling of withdrawals and losses and whether an intention-to-treat analysis had been carried out. Results: The search retrieved 33 CCTs and 43 RCTs. A majority of the reports provided no description of either the method of randomization (75.3%) or concealment of the allocation sequence (84.2%). Participants and outcome assessors were reported as blinded in only 31.2% of the reports. Withdrawals and losses were only clearly described in 6.5% of the reports and none mentioned an intention-to-treat analysis or any similar procedure. Conclusions: The results of this study indicate that a substantial number of reports of trials and systematic reviews are available in the dental journals listed in SciELO, and that these could provide valuable evidence for clinical decision making. However, it is clear that the quality of a number of these reports is of some concern and that improvement in the conduct and reporting of these trials could be achieved if authors adhered to internationally accepted guidelines, e. g. the CONSORT statement.

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Os estudos para a investigação de novas modalidades terapêuticas em biologia tumoral, deveriam passar por estudos experimentais prévios. Neste sentido dispõem-se hoje de uma grande variedade de modelos tumorais experimentais; em determinadas investigações faz-se necessária a adequação do modelo tumoral às necessidades biológicas, patológicas e experimentais dos estudos. Desta forma, em nosso serviço, buscávamos um modelo tumoral hepático para estudos experimentais que se adequasse às seguintes características: fácil manipulação, crescimento controlável, evolução e agressividade semelhantes aos seres humanos. Os dados da literatura nos levaram a busca do tumor hepático VX-2, em coelhos. Neste artigo discutimos as vantagens da utilização deste modelo experimental e a sua introdução em nosso país.

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A minimalist representation of protein structures using a Go- like potential for interactions is implemented to investigate the mechanisms of the domain swapping of p13suc1, a protein that exists in two native conformations: a monomer and a domain- swapped dimer formed by the exchange of a beta- strand. Inspired by experimental studies which showed a similarity of the transition states for folding of the monomer and the dimer, in this study we justify this similarity in molecular descriptions. When intermediates are populated in the simulations, formation of a domain- swapped dimer initiates from the ensemble of unfolded monomers, given by the fact that the dimer formation occurs at the folding/ unfolding temperature of the monomer ( T-f). It is also shown that transitions, leading to a dimer, involve the presence of two intermediates, one of them has a dimeric form and the other is monomeric; the latter is much more populated than the former. However, at temperatures lower than T-f, the population of intermediates decreases. It is argued that the two folded forms may coexist in absence of intermediates at a temperature much lower than T-f. Computational simulations enable us to find a mechanism, `` lock- and- dock'', for domain swapping of p13suc1. To explore the route toward dimer formation, the folding of unstructured monomers must be retarded by first locking one of the free ends of each chain. Then, the other free termini could follow and dock at particular regions, where most intrachain contacts are formed, and thus de. ne the transition states of the dimer. The simulations also showed that a decrease in the maximum distance between monomers increased their stability, which is explained based on confinement arguments. Although the simulations are based on models extracted from the native structure of the monomer and the dimer of p13suc1, the mechanism of the domain- swapping process could be general, not only for p13suc1.

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The involvement of neurotoxicants in the etiology of emotional pathologies is becoming an issue in neurotoxicology. Lead (Pb) exposure during childhood has been associated with increased impulsivity, aggressivity, and delinquency. Considering the paucity of experimental studies investigating the involvement of developmental Pb exposure in emotional disorders, our objective was to investigate whether Pb exposure during pregnancy and/or lactation could be related to depressive symptoms in adult male and female rats. Wistar dams received 10 mg of Pb, as Pb acetate, or 13.4 mg of Na acetate, by gavage, daily, during pregnancy and lactation. By cross-fostering at the time of birth, pups were either exposed to Ph or Na acetate during pregnancy only, lactation only, or during both pregnancy and lactation. At 70 days of age, animals were submitted to the open-field test followed by the forced swimming test. Ph levels were measured in the blood of dams (weaning) and pups (after behavioral evaluation). The results demonstrated that exposure to Ph during both pregnancy and lactation induced, in males, an increased emotionality state detected in the open-field test, and in females, depressive-like behavior detected in the forced swimming test. These alterations were observed at residual blood Pb levels (i.e., around 5 mug/dL).

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Recurrent abortion (RA) represents an intriguing problem in obstetric practice in which genetic and acquired factors may play a role. In the present investigation we sought to assess the possibility that inherited thrombophilia might determine the risk of RA. We therefore investigated the prevalence of two genetic abnormalities frequently associated with venous thrombosis [factor V Leiden (FVL) and factor II G20210A] in 56 patients with primary or secondary abortion and in 384 healthy control women. Polymerase chain reaction amplification followed by digestion with the restriction enzymes MnlI and HindIII was used to define the FVL and FII G20210A genotypes respectively. FVL was found in 4/56 patients (7.1%) and in 6/384 controls (1.6%), yielding an odds ratio (OR) for RA related to FVL of 4.9 [95% confidence interval (CI): 1.3-17.8]. FII G20210A was detected in 2/56 (3.6%) patients and in 4/384 (1%) controls (OR for RA: 3.5, CI: 0.6-19.7). In conclusion, FVL and FII G20210A mutations in patients with RA were more prevalent in comparison with controls. These data support a role for both mutations as determinants of the risk of RA and strengthen the notion that thrombophilia plays a role in this clinical entity.

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The urethra is the main place of entry for sexually transmitted pathogens. However, there is little literature on the morphology of the urogenital system, principally the urethra and ducts of the sex accessory glands. The Mongolian gerbil is an insectivorous, herbivorous and monogamous rodent with nocturnal habits; it has been used successfully as a laboratory animal since the 1960s. Therefore, the objective of the present paper was to describe the structure and ultrastructure of the urethra and its relations to the ducts of the accessory sex glands of the Mongolian gerbil (Meriones unguiculatus), contributing to the understanding of the reproductive biology of the rodent and aiming to provide data for future experimental studies. Conventional techniques of light and scanning electron microscopy were utilized. The urethra and ducts of the accessory sex glands are similar to those of the albino rat and the mouse. However, there is variation in drainage type among accessory sex glands for the inner urethra. The ducts of the seminal vesicle, the ductus deferens, drain their contents independently into the ampullary duct that opens in the urethra. The ducts of the prostate, coagulating and bulbourethral glands drain their contents independently into the urethra.

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The intestinal ischemia is unusual in vascular surgery emergency. Its main causes are embolisms and arterial thrombosis. In addition to severe ischemia, reperfusion of the ischemic tissues can lead to several complications that may worsen the ischemic lesion and produce a life threatening situation caused by systemic alterations. Intestinal tissue injuries due to ischemia and reperfusion have been demonstrated in clinical and experimental studies, in which pathophysiology and adequate treatment were also studied. The great variety of experimental models used and results achieved reflect the need for an intestinal ischemia and reperfusion experimental model that is simple, reproducible and consistent, in order to search for treatments that can reduce the damage caused by this situation. In this review, the main pathophysiologic aspects and the most used experimental models will be reviewed. Copyright © 2005 by Sociedade Brasileira de Angiologia e Cirurgia Vascular.

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Objectives: The purpose of this study was to investigate what effect the ingestion of sardines, rich in omega-3 series polyunsaturated fatty acids, has on the composition of breastmilk. Methods: This was a prospective study of 31 nursing mothers under observation at the Hospital Guilherme Álvaro. Each was given 2 kg of fresh sardines twice with a 15-day interval. Milk was sampled and a 24-hour dietary recall questionnaire was applied on days 0, 15 and 30. Milk was assayed for fatty acid content by gas chromatography. Statistical analysis of the results was performed using nonparametric tests with significance set at p < 0.05. Results: The results demonstrate that the nutritional intake of the nursing mothers was adequate at all three sample points. With regard to the omega-3 series fatty acid content of the breastmilk, it was observed that regular consumption and shorter intervals between ingestion and milk collection resulted in higher concentrations of docosapentaenoic acid and docosahexaenoic acid at 15 and 30 days into the study. Fatty acids from the omega-3 and omega-6 series exhibited a significant correlation, r 2 was 0.58 and 0.59 at 15 and 30 days, respectively. Conclusion: These results suggest that incorporating fish into the diets of nursing mother during lactation, in the form of 100 g of sardines two or three times a week, contributes to an increase in omega-3 series fatty acids. Copyright © 2006 by Sociedade Brasileira de Pediatria.

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The use of laboratory animals in conjunction with research on the human organism provides a basis for on understanding of several important physiological and pathological processes. Besides, the results of experimental studies enable technical and safety improvements to be made in surgical techniques used in the medical clinic. As living biological material is involved, we should guarantee its physical well-being, taking into account microbiological contamination and the genetics, nutrition and correct manipulation of the animals, in order to avoid incorrect conclusions from the experiments or unnecessarily large numbers of animals being used. In parallel with the concerns and legislation on the use of laboratory animals, there is also a growing preoccupation with the welfare and safety of those who handle the laboratory animals, since they run the risk of acquiring occupational diseases through contact with zoonotic pathogens or developing allergies. Prevention requires the application of modern technological advances in the design of the animal house and in the work routines. Unfortunately, few establishments in Brazil possess staff with adequate training and a basic infrastructure of research that includes the laboratory animal breeding centers, equivalent to those existing ones in the United States and Europe.

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To carry out the dating by the Fission Track Method (FTM) the international community that works with this method employs methodologies in which the mineral to be dated must be irradiated with neutrons. Such irradiation, performed in a nuclear reactor, demand a relatively long waiting time so that the activity of the sample attain a proper level for handling. The present work aims to establish a methodology that makes possible the dating by FTM using a mass spectrometer instead of a nuclear reactor. This methodology was applied to apatite samples from Durango, Mexico. © 2009 Elsevier Ltd. All rights reserved.

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The determination of the reflection coefficient of shear waves reflected from a solid-liquid interface is an important method in order to study the viscoelastic properties of liquids at high frequency. The reflection coefficient is a complex number. While the magnitude measurement is relatively easy and precise, the phase measurement is very difficult due to its strong temperature dependence. For that reason, most authors choose a simplified method in order to obtain the viscoelastic properties of liquids from the measured coefficient. In this simplified method, inconsistent viscosity results are obtained because pure viscous behavior is assumed and the phase is not measured. This work deals with an effort to improve the experimental technique required to measure both the magnitude and phase of the reflection coefficient and it intends to report realistic values for oils in a wide range of viscosity (0.092 - 6.7 Pa.s). Moreover, a device calibration process is investigated in order to monitor the dynamic viscosity of the liquid.

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The influence of soil drill rod length on the N value in the SPT-T test has been studied extensively by Mello (1971), Schmertmann & Palacios (1979), Odebrecht et al. (2002) and Cavalcante (2002). This paper presents an analysis of the Standard Penetration Test supplemented with torque measurement (SPT-T). A theoretical study of the resistance of the rod material to torsion and bending indicated that the shear stress caused by the rod self-weight represents less than 1% of that caused by the torsional moment. An experimental study with electric torquemeters attached to a horizontal rod system, as well as two field tests in the vertical direction, were also carried out to compare and substantiate the results. The purpose of these tests was to analyze changes along the length of the rod in response to successive increments at 1-meter intervals. Torque measurements were taken at each increment of the length to ascertain the accuracy of the theoretical data. The difference between the applied torque and the measured torque at the end of rod system was lower than the minimum scale of mechanical torquemeters used in practice.

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Aims: To discuss the importance of studying animal models to test hypotheses about the mechanisms of urinary continence and pathophysiology of diabetes and urinary incontinence. Source of Data: A literature review was conducted in PubMed and SciELO. The key words used were diabetes, urinary incontinence, urethra, human and rats. Summary of Findings: There is a strong relation between the genesis of urinary incontinence and diabetes mellitus. Due to the similarity of normal distribution of skeletal muscle and urethra anatomy between humans and rats, these animal models have been used in current research about these disorders. Conclusions: The use of rats as an animal model is suitable for experimental studies that test hypotheses about the mechanisms of continence and pathophysiology of the binomial diabetes mellitus and urinary incontinence, thus enabling solutions of great value in clinical practice.