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Search Results: 1 - 10 of 540936 matches for " Spencer L. M.;Segato "
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Controle genético das células-tronco humanas cultivadas
Pay?o, Spencer L. M.;Segato, Rosimeire;Santos, Ricardo R.;
Revista Brasileira de Hematologia e Hemoterapia , 2009, DOI: 10.1590/S1516-84842009005000021
Abstract: stem cells have a high capacity of self-regeneration, as well as a potential to differentiate into several cell types. these cells can be classified as embryonic or adult. in spite of having inherent properties of stem cells, mesenchymal cells show a certain degree of difficulty to establish cultures. this might induce a loss of the expression of the telomerase enzyme which is considered to be a biological clock or an indicator of the senescence of the cells. the most current and intriguing question for researchers is whether the presumed division potential of cultivated stem cells, over a period of time could result in an accumulation of genetic alterations and consequently, in a neoplastic process. for this reason, cytogenetic techniques are very important to guarantee the control and safety of cultivated stem cells to be used in human therapy. structural chromosomal alterations, such as for example, deletions, translocations and inversions represent an important mechanism by which cells might gradually transform in a neoplastic process. thus, these chromosomal alterations could result in an abnormal expression of the genes and lead to cancer.
Estresse psicológico de velejadores de alto nível esportivo em competi??o
Segato,L.; Brandt,R.; Liz,C.M.; Vasconcellos,D.I.C.; Andrade,A.;
Motricidade , 2010,
Abstract: the purpose of this work was to investigate the psychological stress present in elite sailors in a competition. based on a descriptive field research, 31 elite sailors volunteered to participate. they answered the perceived stress scale (cohen & williamson, 1988) and also specific questions on self-control, sources and strategies of coping. data were analyzed by using descriptive and inferential (student t test and pearson's correlation) statistics. these athletes revealed low and moderate scores (m = 20.00, dp = 6.83) of stress originated from both intrinsic (ship troubles, team disorders) and extrinsic (study, working and training, family and financial problems) sources. the group reported good stress control during competition through the use of cognitive (avoidance) and somatic (listening music, resting/sleeping, talk to friends) strategies. it is important that sailors are able to control and cope with high levels of psychological stress and to understand how to proceed when under unstable and unexpected situations that arise during competition.
Psychological stress in high level sailors during competition
L. Segato,R. Brandt,C.M. Liz,D.I.C. Vasconcellos
Motricidade , 2010,
Abstract: The purpose of this work was to investigate the psychological stress present in elite sailors in a competition. Based on a descriptive field research, 31 elite sailors volunteered to participate. They answered the Perceived Stress Scale (Cohen & Williamson, 1988) and also specific questions on self-control, sources and strategies of coping. Data were analyzed by using descriptive and inferential (Student t test and Pearson's correlation) statistics. These athletes revealed low and moderate scores (M = 20.00, DP = 6.83) of stress originated from both intrinsic (ship troubles, team disorders) and extrinsic (study, working and training, family and financial problems) sources. The group reported good stress control during competition through the use of cognitive (avoidance) and somatic (listening music, resting/sleeping, talk to friends) strategies. It is important that sailors are able to control and cope with high levels of psychological stress and to understand how to proceed when under unstable and unexpected situations that arise during competition.
Two structurally discrete GH7-cellobiohydrolases compete for the same cellulosic substrate fiber
Fernando Segato, Andre R.L. Damasio, Thiago A Goncalves, Mario T Murakami, Fabio M Squina, Maria L.T.M. Polizeli, Andrew Mort, Rolf A Prade
Biotechnology for Biofuels , 2012, DOI: 10.1186/1754-6834-5-21
Abstract: Cellobiohydrolases Cbh1 and CelD have similar catalytic domains but only Cbh1 contains a carbohydrate-binding domain (CBD) that binds to cellulose. Structural superpositioning of Cbh1 and CelD on the Talaromyces emersonii Cel7A 3-dimensional structure, identifies the typical tunnel-like catalytic active site while Cbh1 shows an additional loop that partially obstructs the substrate-fitting channel. CelD does not have a CBD and shows a four amino acid residue deletion on the tunnel-obstructing loop providing a continuous opening in the absence of a CBD. Cbh1 and CelD are catalytically functional and while specific activity against Avicel is 7.7 and 0.5 U.mg prot-1, respectively specific activity on pNPC is virtually identical. Cbh1 is slightly more stable to thermal inactivation compared to CelD and is much less sensitive to glucose inhibition suggesting that an open tunnel configuration, or absence of a CBD, alters the way the catalytic domain interacts with the substrate. Cbh1 and CelD enzyme mixtures on crystalline cellulosic substrates show a strong combinatorial effort response for mixtures where Cbh1 is present in 2:1 or 4:1 molar excess. When CelD was overrepresented the combinatorial effort could only be partially overcome. CelD appears to bind and hydrolyze only loose cellulosic chains while Cbh1 is capable of opening new cellulosic substrate molecules away from the cellulosic fiber.Cellobiohydrolases both with and without a CBD occur in most fungal genomes where both enzymes are secreted, and likely participate in cellulose degradation. The fact that only Cbh1 binds to the substrate and in combination with CelD exhibits strong synergy only when Cbh1 is present in excess, suggests that Cbh1 unties enough chains from cellulose fibers, thus enabling processive access of CelD.
Prevalence of Helicobacter pylori cagA and sabA Genotypes in Patients with Gastric Disease  [PDF]
Jéssica Nunes Pereira, Wilson A. Orcini, Rita L. Peruquetti, Marilia A. C. Smith, Spencer L. M. Pay?o, Lucas T. Rasmussen
Advances in Microbiology (AiM) , 2019, DOI: 10.4236/aim.2019.93017
Abstract: Gastric cancer is one of the most common types of cancer worldwide. Helicobacter pylori is considered one of the most important causes of this condition specially because of its virulence markers as sabA and cagA. Therefore, we aim to investigate the relation between these markers and the gastric diseases in 400 patients who underwent upper digestive endoscopy. To detect the bacteria and its genes by Polymerase Chain Reaction (PCR), the presence of H. pylori was significant when comparing the groups control vs. cancer (p value < 0.0001) OR [95% CI] 12.73 (5.45 - 29.69) and the groups control vs. chronic gastritis (p value < 0.0001) OR [95% CI] 12.99 (7.44 - 22.66). cagA was statistically significant considering its presence when comparing the chronic gastritis vs. cancer groups (p value = 0.0434) OR [95% CI] 2.44 (1.021 - 5.845). Associating both sabA and cagA, we found a statistically significant result (p value < 0.0001) OR [95% CI] 13.68 (3.95 - 47.33) considering the gastritis vs. cancer groups. Helicobacter pylori is directly associated to gastric diseases such as gastritis and cancer and its virulence markers: sabA and cagA increase the injury process to the gastric epithelium making the host more susceptible to cancer.
Novel Aspects of Nonfasting Lipemia in relation to Vascular Biology
M. Castro Cabezas,Kathleen M. Botham,John C. L. Mamo,Spencer D. Proctor
International Journal of Vascular Medicine , 2012, DOI: 10.1155/2012/419015
Abstract:
Novel Aspects of Nonfasting Lipemia in relation to Vascular Biology
M. Castro Cabezas,Kathleen M. Botham,John C. L. Mamo,Spencer D. Proctor
International Journal of Vascular Medicine , 2012, DOI: 10.1155/2012/419015
Abstract:
Polyparasitism Is Associated with Increased Disease Severity in Toxoplasma gondii-Infected Marine Sentinel Species
Amanda K. Gibson,Stephen Raverty,Dyanna M. Lambourn,Jessica Huggins,Spencer L. Magargal,Michael E. Grigg
PLOS Neglected Tropical Diseases , 2011, DOI: 10.1371/journal.pntd.0001142
Abstract: In 1995, one of the largest outbreaks of human toxoplasmosis occurred in the Pacific Northwest region of North America. Genetic typing identified a novel Toxoplasma gondii strain linked to the outbreak, in which a wide spectrum of human disease was observed. For this globally-distributed, water-borne zoonosis, strain type is one variable influencing disease, but the inability of strain type to consistently explain variations in disease severity suggests that parasite genotype alone does not determine the outcome of infection. We investigated polyparasitism (infection with multiple parasite species) as a modulator of disease severity by examining the association of concomitant infection of T. gondii and the related parasite Sarcocystis neurona with protozoal disease in wild marine mammals from the Pacific Northwest. These hosts ostensibly serve as sentinels for the detection of terrestrial parasites implicated in water-borne epidemics of humans and wildlife in this endemic region. Marine mammals (151 stranded and 10 healthy individuals) sampled over 6 years were assessed for protozoal infection using multi-locus PCR-DNA sequencing directly from host tissues. Genetic analyses uncovered a high prevalence and diversity of protozoa, with 147/161 (91%) of our sampled population infected. From 2004 to 2009, the relative frequency of S. neurona infections increased dramatically, surpassing that of T. gondii. The majority of T. gondii infections were by genotypes bearing Type I lineage alleles, though strain genotype was not associated with disease severity. Significantly, polyparasitism with S. neurona and T. gondii was common (42%) and was associated with higher mortality and more severe protozoal encephalitis. Our finding of widespread polyparasitism among marine mammals indicates pervasive contamination of waterways by zoonotic agents. Furthermore, the significant association of concomitant infection with mortality and protozoal encephalitis identifies polyparasitism as an important factor contributing to disease severity in marine mammals.
Modeling a Snap-Action, Variable-Delay Switch Controlling Extrinsic Cell Death
John G. Albeck,John M. Burke,Sabrina L. Spencer,Douglas A. Lauffenburger,Peter K. Sorger
PLOS Biology , 2012, DOI: 10.1371/journal.pbio.0060299
Abstract: When exposed to tumor necrosis factor (TNF) or TNF-related apoptosis-inducing ligand (TRAIL), a closely related death ligand and investigational therapeutic, cells enter a protracted period of variable duration in which only upstream initiator caspases are active. A subsequent and sudden transition marks activation of the downstream effector caspases that rapidly dismantle the cell. Thus, extrinsic apoptosis is controlled by an unusual variable-delay, snap-action switch that enforces an unambiguous choice between life and death. To understand how the extrinsic apoptosis switch functions in quantitative terms, we constructed a mathematical model based on a mass-action representation of known reaction pathways. The model was trained against experimental data obtained by live-cell imaging, flow cytometry, and immunoblotting of cells perturbed by protein depletion and overexpression. The trained model accurately reproduces the behavior of normal and perturbed cells exposed to TRAIL, making it possible to study switching mechanisms in detail. Model analysis shows, and experiments confirm, that the duration of the delay prior to effector caspase activation is determined by initiator caspase-8 activity and the rates of other reactions lying immediately downstream of the TRAIL receptor. Sudden activation of effector caspases is achieved downstream by reactions involved in permeabilization of the mitochondrial membrane and relocalization of proteins such as Smac. We find that the pattern of interactions among Bcl-2 family members, the partitioning of Smac from its binding partner XIAP, and the mechanics of pore assembly are all critical for snap-action control.
Receptor chimeras demonstrate that the C-terminal domain of the human cytomegalovirus US27 gene product is necessary and sufficient for intracellular receptor localization
Lance K Stapleton, Kathleen L Arnolds, Angela P Lares, Tori M Devito, Juliet V Spencer
Virology Journal , 2012, DOI: 10.1186/1743-422x-9-42
Abstract: In transiently transfected cells, wild type US27 was found primarily in intracellular compartments, in striking contrast to the cell surface distribution seen for the human cellular chemokine receptor CXCR3. When the N-terminal extracellular domains of the two receptors were swapped, no change in protein localization was observed. However, swapping of the C-terminal intracellular domains resulted in a significant change in receptor distribution. A chimera that contained US27 fused to the C-terminal intracellular tail of CXCR3 exhibited surface distribution similar to that of wild-type CXCR3. When the C-terminal domain of US27 was fused to CXCR3, this chimeric receptor (CXCR3/US27-CT) was found in the same intracellular pattern as wild-type US27. In addition, a US27 mutant lacking the C-terminus (US27ΔCT) failed to accumulate inside the cell and exhibited cell surface distribution. Co-localization with organelle-specific markers revealed that wild-type US27 was found predominantly in the Golgi apparatus and in endosomal compartments, whereas the US27/CXCR3-CT chimera, US27ΔCT and US27Δ348 mutants were not localized to endosomal compartments.The results indicate that the C-terminal domain of the HCMV US27 protein, which contains a di-leucine endocytic sorting motif, is both necessary and sufficient for intracellular localization, which may also help explain why no cellular ligands have yet been identified for this viral receptor.Human cytomegalovirus (HCMV) is a herpesvirus that is ubiquitous in the population with a seroprevalence of 50-95% [1]. Primary infection is usually asymptomatic, but more serious disease can occur in the immune-compromised patient. HCMV pneumonitis greatly impacts the morbidity and mortality of transplant recipients, and increasing numbers of HIV patients have been diagnosed with severe HCMV retinitis [2]. HCMV can also be transmitted from mother to child during pregnancy and remains the most common viral cause of congenital defects, includin
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