612 resultados para Bundle


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Conselho Nacional de Desenvolvimento Científico e Tecnológico(CNPq)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Increase in lower anterior crowding is a general problem among adult Caucasians. The tooth movement responsible for this phenomenon, however, is not fully elucidated. Aim of this study was to describe signs of ongoing tooth movement reflected in the thickness of the bundle bone around mandibular teeth and the distribution of eroding surfaces of the alveolar wall in human autopsy material. The distribution of bundle bone and eroding surfaces was assessed histomorphometrically on 106 mandibular teeth, and the surrounding bone obtained at autopsy from 35 deceased persons ranging from 19 to 55 years of age. By examining the mesio-distal and bucco-lingual aspects at the cervical and apical levels of the roots, a pattern of tooth movements could be established. The distribution of the bundle bone thickness and the vectors of eroding surfaces enabled the direction of tooth movement to be reconstructed. Mesial and lingual displacement was prevalent for the anterior teeth. The signs of ongoing displacement of lower teeth support the concept of crowding occurring in adult individuals and support the maintenance of retainers, even following cessation of growth.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Amlodipine is a dihydropyridine calcium channel antagonist extensively used for the treatment of arterial hypertension, with predominant effect on the peripheral vascular territory. In most cases of severe intoxication, important hypotension and reflex tachycardia are usually observed. We report a case of young man with severe amlodipine intoxication that developed important bradyarrhythmias, such as low atrial rhythm, prolonged PR interval, atrioventricular block, and left bundle branch block. These rhythm disturbances suggest that, during acute intoxication, dihydropyridine loses its selective action on the vascular territory and can depress automatism and conduction of cardiac electrical stimulus.

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In the present study, we investigated the involvement of beta-adrenoceptors in the medial amygdaloid nucleus (MeA) in cardiovascular responses evoked in rats submitted to an acute restraint stress. We first pretreated Wistar rats with the nonselective beta-adrenoceptor antagonist propranolol microinjected bilaterally into the MeA (10, 15, and 20 nmol/100 nL) 10 min before exposure to acute restraint. The pretreatment with propranolol did not affect the blood pressure (BP) increase evoked by restraint. However, it increased the tachycardiac response caused by acute restraint when animals were pretreated with a dose of 15 nmol, without a significant effect on the BP response. This result indicates that beta-adrenoceptors in the MeA have an inhibitory influence on restraint-evoked heart rate (HR) changes. Pretreatment with the selective beta(2)-adrenoceptor antagonist ICI 118,551 (10, 15, and 20 nmol/100 nL) significantly increased the restraint-evoked tachycardiac response after doses of 15 and 20 nmol, an effect that was similar to that observed after the pretreatment with propranolol at a dose of 15 nmol, without a significant effect on the BP response. Pretreatment of the MeA with the selective beta(1)-adrenoceptor antagonist CGP 20712 (10, 15, and 20 nmol/100 nL) caused an opposite effect on the HR response, and a significant decrease in the restraint-evoked tachycardia was observed only after the dose of 20 nmol, without a significant effect on the BP response. Because propranolol is an equipotent antagonist of both beta(1) and beta(2)-adrenoceptors, and opposite effects were observed after the treatment with the higher doses of the selective antagonists ICI 118,551 and CGP 20712, the narrow window in the dose-response to propranolol could be explained by a functional antagonism resulting from the simultaneous inhibition of beta(1) and beta(2)-adrenoceptors by the treatment with propranolol. The present results suggest that beta(2)-adrenoceptors have an inhibitory influence on the restraint-evoked tachycardiac response, whereas beta(1)-adrenoceptors have a facilitatory influence on the restraint-evoked tachycardiac response. (c) 2012 IBRO. Published by Elsevier Ltd. All rights reserved.

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Scanning (SEM) and transmission (TEM) electron microscopy were used to elucidate the morphology of the rostrum, as well as the mandibular and maxillary stylets of the psyllid Diaphorina cirri, vector of phloem-inhabiting bacteria associated with citrus huanglongbing (HLB) disease. D. cirri has a cone-shaped rostrum that extends behind the pair of prothoracic coxae. The stylet bundle comprises a pair of mandibular (Md) and maxillary (Mx) stylets with a mean length of 513.3 mu m; when retracted, their proximal portions form a loop and are stored in the crumena (Cr). Serial cross-sections of the rostrum revealed that the mandibles are always projected in front of the maxillary stylets. The two maxillary stylets form the food and salivary canals, with diameters of 0.9 mu m and 0.4 mu m respectively. These two canals merge at the end of the stylets forming a common duct with a length of 4.3 mu m and a mean diameter of 0.9 mu m. The acrostyle, a distinct anatomical structure present in the common duct of aphid maxillary stylets, was not observed by TEM in the ultrathin cross-sections of the common duct (CD) of D. citri. This study provides new information on D. citri mouthparts that may help to understand the behaviour of this important vector of HLB-associated bacteria. (C) 2011 Elsevier Ltd. All rights reserved.

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There are fibers in the left ventricle (LV) (LV middle network) that in around one third of cases may be considered a true septal fascicle that arises from the common left bundle. Its presence and the evidence that there are 3 points of activation onset in the LV favor the quadrifascicular theory of the intravantricular activation of both ventricles. Since the 70s, different authors have suggested that the block of the left middle fibers (MS)/left septal fascicle may explain different electrocardiographic (ECG) patterns. The 2 hypothetically based criteria that are in some sense contradictory include: a) the lack of septal "q" wave due to first left and later posteriorly shifting of the horizontal plane loop and b) the presence of RS in lead V-2 (V-1-V-2) due to some anterior shifting of the horizontal plane vectorcardiogram loop. However, there are many evidence that the lack of septal q waves can be also explained by predivisional first-degree left bundle-branch block and that the RS pattern in the right precordial leads may be also explained by first-degree right bundle-branch block. The transient nature of these patterns favor the concept that some type of intraventricular conduction disturbance exists but a doubt remains about its location. Furthermore, the RS pattern could be explained by many different normal variants. To improve our understanding whether these patterns are due to MF/left septal fascicle block or other ventricular conduction disturbances (or both), it would be advisable: 1) To perform more histologic studies (heart transplant and necropsy) of the ventricular conduction system; 2) To repeat prior experimental studies using new methodology/technology to isolate the MF; and 3) To change the paradigm: do not try to demonstrate if the block of the fibers produces an ECG change but to study with new electroanatomical imaging techniques, if these ECG criteria previously described correlate or not with a delay of activation in the zone of the LV that receives the activation through these fibers or in other zones. (C) 2012 Elsevier Inc. All rights reserved.

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BACKGROUND: The fiber dissection technique provides unique 3-dimensional anatomic knowledge of the white matter. OBJECTIVE: To examine the optic radiation anatomy and its important relationship with the temporal stem and to discuss its findings in relation to the approaches to temporal lobe lesions. METHODS: We studied 40 cerebral hemispheres of 20 brains that had been fixed in formalin solution for 40 days. After removal of the arachnoid membrane, the hemispheres were frozen, and the Klingler technique was used for dissection under magnification. Stereoscopic 3-dimensional images of the dissection were obtained for illustration. RESULTS: The optic radiations are located deep within the superior and middle temporal gyri, always above the inferior temporal sulcus. The mean distance between the cortical surface and the lateral edge of the optic radiation was 21 mm. Its fibers are divided into 3 bundles after their origin. The mean distance between the anterior tip of the temporal horn and the Meyer loop was 4.5 mm, between the temporal pole and the anterior border of the Meyer loop was 28.4 mm, and between the limen insulae and the Meyer loop was 10.7 mm. The mean distance between the lateral geniculate body and the lateral margin of the central bundle of the optic radiation was 17.4 mm. CONCLUSION: The white matter fiber dissection reveals the tridimensional intrinsic architecture of the brain, and its knowledge regarding the temporal lobe is particularly important for the neurosurgeon, mostly because of the complexity of the optic radiation and related fibers.

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Psittaciformes are one of the most endangered groups of birds, and several Brazilian species are classified between vulnerable and critically endangered. It is thus necessary to identify agents that cause infections in captive wild animals and to assess the risks posed thereof and to design interventions to minimize the possibility of disease outbreaks, leading to the conservation of endangered species. The purpose of this study was to identify enteropathogenic Escherichia coli (EPEC) cloacal isolates from asymptomatic psittacines in captivity and evaluate the distribution of the EPEC pathotype. Cloacal swabs were obtained from 46 asymptomatic birds, and resulting isolates were tested by polymerase chain reaction (PCR) for the presence of the attaching and effacing gene (eae) and bundle-forming pilus structural gene (bfpA) of EPEC. Samples from several species were tested, and three samples were found to be positive for the eae and bfpA genes and characterized as typical EPEC. This is the first report of this pathotype in asymptomatic psittacines. Although certain E. coli strains are more pathogenic than others, various factors should be considered when determining the potential of E. coli isolates to cause disease in captive psittacines. Birds that are positive for the EPEC (typical) strain could be zoonotic sources of infection, and may have acquired these strains through contact with humans or domestic animals. These findings may also be valuable for the long-term management of endangered species ex situ as one EPEC sample was isolated from a Red-tailed Amazon (Amazona brasiliensis).

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The neurovascular bundle may be vulnerable during surgical procedures involving the mandible, especially when anatomical variations are present. Increased demand of implant surgeries, wider availability of three-dimensional exams, and lack of clear definitions in the literature indicate that features of anatomical variations should be revisited. The objective of the study was to evaluate features of anatomical variations related to mandibular canal (MC), such as bifid canals, anterior loop of mental nerve, and corticalization of MC. Additionally, bone trabeculation at the submandibular gland fossa region (SGF) was assessed and related to visibility of MC. Cone beam computed tomography exams from 100 patients (200 hemimandibles) were analyzed and the following parameters were registered: diameter and corticalization of MC; trabeculation in SGF region; presence of bifid MC, position of bifurcations, diameter, and direction of bifid canals; and measurement of anterior loops by two methods. Corticalization of the MC was observed in 59% of hemimandibles. In 23%, MC could be identified despite absence of corticalization. Diameter of MC was between 2.1 and 4 mm for nearly three quarters of the sample. In 80% of the sample trabeculation at the SGF was either decreased or not visible, and such cases showed correlation with absence of MC corticalization. Bifid MC affected 19% of the patients, mostly associated with additional mental foramina. Clinically significant anterior loop (> 2 mm of anterior extension) was observed in 22-28%, depending on the method. Our findings, together with previously reported limitations of conventional exams, draw attention to the unpredictability related to anatomical variations in neurovascularization, showing the contribution of individual assessment through different views of three-dimensional imaging prior to surgical procedures in the mandible.