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Search Results: 1 - 10 of 782453 matches for " A.M.B.; "
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Early myelin breakdown following sural nerve crush: a freeze-fracture study
Martinez, A.M.B.;Canavarro, S.;
Brazilian Journal of Medical and Biological Research , 2000, DOI: 10.1590/S0100-879X2000001200012
Abstract: in this study we describe the early changes of the myelin sheath following surgical nerve crush. we used the freeze-fracture technique to better evaluate myelin alterations during an early stage of wallerian degeneration. rat sural nerves were experimentally crushed and animals were sacrificed by transcardiac perfusion 30 h after surgery. segments of the nerves were processed for routine transmission electron microscopy and freeze-fracture techniques. our results show that 30 h after the lesion there was asynchrony in the pattern of wallerian degeneration, with different nerve fibers exhibiting variable degrees of axon disruption. this was observed by both techniques. careful examination of several replicas revealed early changes in myelin membranes represented by vacuolization and splitting of consecutive lamellae, rearrangement of intramembranous particles and disappearance of paranodal transverse bands associated or not with retraction of paranodal myelin terminal loops from the axolemma. these alterations are compatible with a direct injury to the myelin sheath following nerve crush. the results are discussed in terms of a similar mechanism underlying both axon and myelin breakdown.
Early myelin breakdown following sural nerve crush: a freeze-fracture study
Martinez A.M.B.,Canavarro S.
Brazilian Journal of Medical and Biological Research , 2000,
Abstract: In this study we describe the early changes of the myelin sheath following surgical nerve crush. We used the freeze-fracture technique to better evaluate myelin alterations during an early stage of Wallerian degeneration. Rat sural nerves were experimentally crushed and animals were sacrificed by transcardiac perfusion 30 h after surgery. Segments of the nerves were processed for routine transmission electron microscopy and freeze-fracture techniques. Our results show that 30 h after the lesion there was asynchrony in the pattern of Wallerian degeneration, with different nerve fibers exhibiting variable degrees of axon disruption. This was observed by both techniques. Careful examination of several replicas revealed early changes in myelin membranes represented by vacuolization and splitting of consecutive lamellae, rearrangement of intramembranous particles and disappearance of paranodal transverse bands associated or not with retraction of paranodal myelin terminal loops from the axolemma. These alterations are compatible with a direct injury to the myelin sheath following nerve crush. The results are discussed in terms of a similar mechanism underlying both axon and myelin breakdown.
Quantitative evidence for neurofilament heavy subunit aggregation in motor neurons of spinal cords of patients with amyotrophic lateral sclerosis
Mendon?a, D.M.F.;Chimelli, L.;Martinez, A.M.B.;
Brazilian Journal of Medical and Biological Research , 2005, DOI: 10.1590/S0100-879X2005000600015
Abstract: amyotrophic lateral sclerosis (als), a neurodegenerative disease of unknown etiology, affects motor neurons leading to atrophy of skeletal muscles, paralysis and death. there is evidence for the accumulation of neurofilaments (nf) in motor neurons of the spinal cord in als cases. nf are major structural elements of the neuronal cytoskeleton. they play an important role in cell architecture and differentiation and in the determination and maintenance of fiber caliber. they are composed of three different polypeptides: light (nf-l), medium (nf-m) and heavy (nf-h) subunits. in the present study, we performed a morphological and quantitative immunohistochemical analysis to evaluate the accumulation of nf and the presence of each subunit in control and als cases. spinal cords from patients without neurological disease and from als patients were obtained at autopsy. in all als cases there was a marked loss of motor neurons, besides atrophic neurons and preserved neurons with cytoplasmic inclusions, and extensive gliosis. in control cases, the immunoreaction in the cytoplasm of neurons was weak for phosphorylated nf-h, strong for nf-m and weak for nf-l. in als cases, anterior horn neurons showed intense immunoreactivity in focal regions of neuronal perikarya for all subunits, although the difference in the integrated optical density was statistically significant only for nf-h. furthermore, we also observed dilated axons (spheroids), which were immunopositive for nf-h but negative for nf-m and nf-l. in conclusion, we present qualitative and quantitative evidence of nf-h subunit accumulation in neuronal perikarya and spheroids, which suggests a possible role of this subunit in the pathogenesis of als.
Quantitative evidence for neurofilament heavy subunit aggregation in motor neurons of spinal cords of patients with amyotrophic lateral sclerosis
Mendon?a D.M.F.,Chimelli L.,Martinez A.M.B.
Brazilian Journal of Medical and Biological Research , 2005,
Abstract: Amyotrophic lateral sclerosis (ALS), a neurodegenerative disease of unknown etiology, affects motor neurons leading to atrophy of skeletal muscles, paralysis and death. There is evidence for the accumulation of neurofilaments (NF) in motor neurons of the spinal cord in ALS cases. NF are major structural elements of the neuronal cytoskeleton. They play an important role in cell architecture and differentiation and in the determination and maintenance of fiber caliber. They are composed of three different polypeptides: light (NF-L), medium (NF-M) and heavy (NF-H) subunits. In the present study, we performed a morphological and quantitative immunohistochemical analysis to evaluate the accumulation of NF and the presence of each subunit in control and ALS cases. Spinal cords from patients without neurological disease and from ALS patients were obtained at autopsy. In all ALS cases there was a marked loss of motor neurons, besides atrophic neurons and preserved neurons with cytoplasmic inclusions, and extensive gliosis. In control cases, the immunoreaction in the cytoplasm of neurons was weak for phosphorylated NF-H, strong for NF-M and weak for NF-L. In ALS cases, anterior horn neurons showed intense immunoreactivity in focal regions of neuronal perikarya for all subunits, although the difference in the integrated optical density was statistically significant only for NF-H. Furthermore, we also observed dilated axons (spheroids), which were immunopositive for NF-H but negative for NF-M and NF-L. In conclusion, we present qualitative and quantitative evidence of NF-H subunit accumulation in neuronal perikarya and spheroids, which suggests a possible role of this subunit in the pathogenesis of ALS.
Impacts of Shading on Flower Formation and Longevity, Leaf Chlorophyll and Growth of Bougainvillea glabra
M. Saifuddin,A.M.B.S. Hossain,O. Normaniza
Asian Journal of Plant Sciences , 2010,
Abstract: Bougainvillea plants were exposed to artificially reduced light intensity to capture different Photosynthetic Photon Flux Density (PPFD), 0% (direct sunlight), 30, 50 and 75% shading and to observe the effects of shading on flower formation and longevity, leaf chlorophyll and sugar content and quality of plants. Plant attained the greatest leaf size with maximum branching when seedlings were grown in 30 and 50% shading, whereas 0% shading showed the lowest value. Growth parameters related to the plant characteristics such as branch initiation, branch growth and potassium content increased under high shading treatments. Plants exposed to 0% shade showed the highest sugar content and the sugar content decreased by increasing shading. The low light intensity that results in decreased sugar and chlorophyll contents may be attributed to the reduction of flower initiation and in turn to the acceleration of flower abscission. In addition, more than 30% shading led to stop up flower initiation completely. Hence, it is suggested that 0% shading can be applied to maintain frequent flower initiation and flower longevity.
Effect of perimuscular injection of Bothrops jararacussu venom on plasma creatine kinase levels in mice: influence of dose and volume
Calil-Elias, S.;Thattassery, E.;Martinez, A.M.B.;Melo, P.A.;
Brazilian Journal of Medical and Biological Research , 2002, DOI: 10.1590/S0100-879X2002001000018
Abstract: the effect of dose and volume of a perimuscular injection of bothrops jararacussu venom on myonecrosis of skeletal muscle was studied in mice. an increase of the venom dose (0.25 to 2.0 μg/g) at a given volume (50 μl) resulted in an increase in plasma creatine kinase (ck) levels 2 h after injection. plasma ck activity increased from the basal level of 129.27 ± 11.83 (n = 20) to 2392.80 ± 709.43 iu/l (n = 4) for the 1.0 μg/g dose. histological analysis of extensor digitorum longus muscle 4 h after injection showed lesion of peripheral muscle fibers, disorganization of the bundles or the complete degeneration of muscle fibers. these lesions were more extensive when higher doses were injected. furthermore, an increase in volume (12.5 to 100 μl) by dilution of a given dose (0.5 μg/g) also increased plasma ck levels from 482.31 ± 122.79 to 919.07 ± 133.33 iu/l (n = 4), respectively. these results indicate that care should be taken to standardize volumes and sites of venom injections.
Effect of perimuscular injection of Bothrops jararacussu venom on plasma creatine kinase levels in mice: influence of dose and volume
Calil-Elias S.,Thattassery E.,Martinez A.M.B.,Melo P.A.
Brazilian Journal of Medical and Biological Research , 2002,
Abstract: The effect of dose and volume of a perimuscular injection of Bothrops jararacussu venom on myonecrosis of skeletal muscle was studied in mice. An increase of the venom dose (0.25 to 2.0 μg/g) at a given volume (50 μl) resulted in an increase in plasma creatine kinase (CK) levels 2 h after injection. Plasma CK activity increased from the basal level of 129.27 ± 11.83 (N = 20) to 2392.80 ± 709.43 IU/l (N = 4) for the 1.0 μg/g dose. Histological analysis of extensor digitorum longus muscle 4 h after injection showed lesion of peripheral muscle fibers, disorganization of the bundles or the complete degeneration of muscle fibers. These lesions were more extensive when higher doses were injected. Furthermore, an increase in volume (12.5 to 100 μl) by dilution of a given dose (0.5 μg/g) also increased plasma CK levels from 482.31 ± 122.79 to 919.07 ± 133.33 IU/l (N = 4), respectively. These results indicate that care should be taken to standardize volumes and sites of venom injections.
Diversity among satellite glial cells in dorsal root ganglia of the rat
Nascimento, R.S.;Santiago, M.F.;Marques, S.A.;Allodi, S.;Martinez, A.M.B.;
Brazilian Journal of Medical and Biological Research , 2008, DOI: 10.1590/S0100-879X2008005000051
Abstract: peripheral glial cells consist of satellite, enteric glial, and schwann cells. in dorsal root ganglia, besides pseudo-unipolar neurons, myelinated and nonmyelinated fibers, macrophages, and fibroblasts, satellite cells also constitute the resident components. information on satellite cells is not abundant; however, they appear to provide mechanical and metabolic support for neurons by forming an envelope surrounding their cell bodies. although there is a heterogeneous population of neurons in the dorsal root ganglia, satellite cells have been described to be a homogeneous group of perineuronal cells. our objective was to characterize the ultrastructure, immunohistochemistry, and histochemistry of the satellite cells of the dorsal root ganglia of 17 adult 3-4-month-old wistar rats of both genders. ultrastructurally, the nuclei of some satellite cells are heterochromatic, whereas others are euchromatic, which may result from different amounts of nuclear activity. we observed positive immunoreactivity for s-100 and vimentin in the cytoplasm of satellite cells. the intensity of s-100 protein varied according to the size of the enveloped neuron. we also noted that vimentin expression assumed a ring-like pattern and was preferentially located in the cytoplasm around the areas stained for s-100. in addition, we observed nitric oxide synthase-positive small-sized neurons and negative large-sized neurons equal to that described in the literature. satellite cells were also positive for nadph-diaphorase, particularly those associated with small-sized neurons. we conclude that all satellite cells are not identical as previously thought because they have different patterns of glial marker expression and these differences may be correlated with the size and function of the neuron they envelope.
Quiste nasolabial: reporte de un caso y revisión de la literatura Nasolabial cyst: a case report and review of the literature
B.R. Chrcanovic,R. López Alvarenga,L.N. Souza,A.M.B. De Paula
Avances en Odontoestomatología , 2011,
Abstract: El quiste nasolabial es un raro quiste no odontogénico, su origen embriológico es poco claro. Son lesiones de crecimiento extraóseo, que se presentan como una tumefacción que eleva el ala nasal, indoloro, desplazable y fluctuante. Se localiza en la apófisis alveolar cercana a la base del ala de la nariz. El tratamiento consiste en la enucleación quirúrgica de la lesión. En este artículo se presenta un caso de quiste nasolabial, que acomete a una paciente de sexo femenino de 51 a os de edad, de la cual se discuten los datos clínicos, aspectos diagnósticos, imagenológicos, histopatológicos, así como su tratamiento. The nasolabial cyst is a rare nonodontogenic cyst with its embryological origin little clear. They are extraosseous lesions with growth that appears like a swelling that lifts the nasal wing, painless, sliding and fluctuating. It is located in the alveolar apophysis near the base of the wing of the nose. The treatment consists of surgical enucleating of the lesion. This article presents a case of nasolabial cyst in a female patient of 46 years age, describing clinical, diagnostic, imaging, and histopathological aspects as well as the treatment employed.
Quiste nasolabial: reporte de un caso y revisión de la literatura
Chrcanovic,B.R.; López Alvarenga,R.; Souza,L.N.; De Paula,A.M.B.; Freire-Maia,B.;
Avances en Odontoestomatología , 2011, DOI: 10.4321/S0213-12852011000300002
Abstract: the nasolabial cyst is a rare nonodontogenic cyst with its embryological origin little clear. they are extraosseous lesions with growth that appears like a swelling that lifts the nasal wing, painless, sliding and fluctuating. it is located in the alveolar apophysis near the base of the wing of the nose. the treatment consists of surgical enucleating of the lesion. this article presents a case of nasolabial cyst in a female patient of 46 years age, describing clinical, diagnostic, imaging, and histopathological aspects as well as the treatment employed.
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