RESUMO
Autoimmune diseases and thrombophilic disorders, notably antiphospholipid syndrome (APS) and protein S deficiency, present a formidable challenge in pregnancy, substantially increasing the risk of thromboembolic complications by up to 20%. Pulmonary thromboembolism (PTE), characterized by a significantly higher maternal mortality rate, is of particular concern. APS, defined by the presence of antiphospholipid antibodies, emerges as a pivotal risk factor for PTE during pregnancy, especially in women exhibiting triple negativity. Concurrently, protein S deficiency further amplifies vulnerability to thromboembolic events, establishing a high-risk scenario for pregnant individuals. In a case involving a 29-year-old pregnant woman with a history of generalized lupus erythematosus, triple-negative antiphospholipid syndrome, and protein S deficiency, sudden-onset dyspnea prompted thorough investigation. Despite her complex medical history, a multidisciplinary approach led to the accurate diagnosis and successful management of subsegmental pulmonary thromboembolism, ensuring the well-being of both mother and fetus. Effectively managing PTE during pregnancy demands a comprehensive, multidisciplinary approach involving collaboration among obstetricians, internists, rheumatologists, and hematologists. Accurate diagnosis, tailored anticoagulation strategies, and continuous monitoring stand as indispensable pillars for maternal and fetal well-being.
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The human milk microbiota (HMM) of healthy women can vary substantially, as demonstrated by recent advances in DNA sequencing technology. However, the method used to extract genomic DNA (gDNA) from these samples may impact the observed variations and potentially bias the microbiological reconstruction. Therefore, it is important to use a DNA extraction method that is able to effectively isolate gDNA from a diverse range of microorganisms. In this study, we improved and compared a DNA extraction method for gDNA isolation from human milk (HM) samples to commercial and standard protocols. We evaluated the extracted gDNA using spectrophotometric measurements, gel electrophoresis, and PCR amplifications to assess its quantity, quality, and amplifiability. Additionally, we tested the improved method's ability to isolate amplifiable gDNA from fungi, Gram-positive and Gram-negative bacteria to validate its potential for reconstructing microbiological profiles. The improved DNA extraction method resulted in a higher quality and quantity of the extracted gDNA compared to the commercial and standard protocols and allowed for polymerase chain reaction (PCR) amplification of the V3-V4 regions of the 16S ribosomal gene in all the samples and the ITS-1 region of the fungal 18S ribosomal gene in 95% of the samples. These results suggest that the improved DNA extraction method demonstrates better performance for gDNA extraction from complex samples such as HM.
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In most Latin American countries, there are significant numbers of missing people and forced disappearances, over 120,000 in Colombia alone. Successful detection of shallow buried human remains by forensic search teams is difficult in varying terrain and climates. Previous research has created controlled simulated clandestine graves of murder victims to optimize search techniques and methodologies. This paper reports on a study on controlled test site results over four simulated dismembered victims' clandestine graves as this is sadly a common scenario encountered in Latin America. Multispectral images were collected once post-burial, electrical resistivity surveys were collected 4 times, and ground penetrating radar (GPR) surveys were collected three times up to the end of the 371 day survey monitoring period. After data processing, results showed that the multispectral data set could detect the simulated clandestine and control graves, with electrical resistivity imaging relative high resistances over some of the simulated graves but not over the empty control graves. GPR results showed good imaging on the Day 8 surveys, medium imaging on the Day 294 surveys, and medium to good imaging on the Day 371 surveys. Study implications suggest that, while clandestine graves of dismembered homicide victims would likely result in smaller-sized graves when compared to graves containing intact bodies, these graves can still potentially be detected using remote sensing and geophysical methods.
Assuntos
Sepultamento , Radar , Colômbia , Impedância Elétrica , Fenômenos Geológicos , Direitos Humanos , Humanos , América do Sul , TomografiaRESUMO
Para alcançar o desempenho reprodutivo ótimo nos equinos precisamos que o animal tenha saúde, conforto e viva em uma condição pouco estressante. O manejo nutricional é fundamental para alcançar esta condição. A dieta dos animais é composta por água, sal mineral e volumoso. Quando a combinação destes nutrientes não atinge o requerimento da categoria do animal complementamos esta diferença com ração concentrada. Baseamos nossas recomendações no NRC (National Research Council). As categorias mais fáceis de alimentar são as éguas vazias e garanhões fora do período de monta e as categorias mais difíceis de nutrir são as éguas a partir do 5º mês de gestação, garanhões durante a temporada de monta e as categorias mais exigentes é o das éguas paridas. Os requerimentos nutricionais para os garanhões são muito dependentes do comportamento destes animais e variam muito de um animal para outro e precisam ser individualizados, já a dieta das receptoras é influenciada pelo custo dos componentes da dieta, sendo esta a categoria onde mais se utiliza as dietas alternativas e estas muitas vezes oferecem riscos à saúde das éguas. A variação na qualidade e preço do volumoso durante o ano nos obriga a analisar periodicamente a composição bromatológica das diferentes fontes de volumosos disponíveis, sendo que o uso do NIR (Near Infrared) uma ferramenta útil e confiável para esta função.
Horses healthy, comfortable and low-stress condition live are essential to get optimal reproduction index. Nutritional management is the key to achieve this condition. The animals' diet consists of water, mineral salt and roughage. When the combination of those nutrients does not reach the requirement of the animal we should supplement this difference with grains. We base our recommendations on the NRC (National Research Council). Barren mares and stallions out of season are the easiest to feed. Pregnant mares (> 5 months) and Active stallions have high nutrient demand and the most demanding categories are lactating mares. Nutritional requirements for stallions are highly dependent of stallion behavior. The recipientes diet must be cost effective. Alternatives feeds are not well known and more research must be done. The quality and price oscilation of roughage during the year demands periodically analyzes and NIR ("Near Infrared") is a useful and reliable tool for it.
Assuntos
Masculino , Animais , Cavalos/fisiologia , Fenômenos Fisiológicos da Nutrição Animal , Silagem/análise , Zea maysRESUMO
BACKGROUND: Trichoderma spp. can establish beneficial interactions with plants by promoting plant growth and defense systems, as well as, antagonizing fungal phytopathogens in mycoparasitic interactions. Such interactions depend on signal exchange between both participants and can be mediated by effector proteins that alter the host cell structure and function, allowing the establishment of the relationship. The main purpose of this work was to identify, using computational methods, candidates of effector proteins from T. virens, T. atroviride and T. reesei, validate the expression of some of the genes during a beneficial interaction and mycoparasitism and to define the biological function for one of them. RESULTS: We defined a catalogue of putative effector proteins from T. virens, T. atroviride and T. reesei. We further validated the expression of 16 genes encoding putative effector proteins from T. virens and T. atroviride during the interaction with the plant Arabidopsis thaliana, and with two anastomosis groups of the phytopathogenic fungus Rhizoctonia solani. We found genes which transcript levels are modified in response to the presence of both plant fungi, as well as genes that respond only to either a plant or a fungal host. Further, we show that overexpression of the gene tvhydii1, a Class II hydrophobin family member, enhances the antagonistic activity of T. virens against R. solani AG2. Further, deletion of tvhydii1 results in reduced colonization of plant roots, while its overexpression increases it. CONCLUSIONS: Our results show that Trichoderma is able to respond in different ways to the presence of a plant or a fungal host, and it can even distinguish between different strains of fungi of a given species. The putative effector proteins identified here may play roles in preventing perception of the fungus by its hosts, favoring host colonization or protecting it from the host's defense response. Finally, the novel effector protein TVHYDII1 plays a role in plant root colonization by T, virens, and participates in its antagonistic activity against R. solani.
Assuntos
Arabidopsis/microbiologia , Proteínas Fúngicas/genética , Rhizoctonia/fisiologia , Trichoderma/fisiologia , Biologia Computacional , Resistência à Doença , Perfilação da Expressão Gênica , Regulação Fúngica da Expressão Gênica , Interações Hospedeiro-Patógeno , Raízes de Plantas/microbiologia , Trichoderma/genéticaRESUMO
O tratamento da mordida aberta é sempre um grande desafio para o clínico, principalmente quando o fator estabilidade em longo prazo é levado em consideração, pois, na maioria das vezes, os indivíduos que apresentam este tipo de maloclusão estão acometidos de disfunção lingual, a qual, se não for corrigida satisfatoriamente, será o fator da recidiva da mordida aberta anterior. Tendo isso em vista, este trabalho tem como objetivo apresentar uma variação introduzida no desenho original do aparelho quadrihélice de Ricketts, o qual, além de permitir obter excelentes resultados na reeducação da língua durante os seus movimentos peristálticos, serve também como guia para a sua posição de repouso.
The open bite treatment is always a great challenge for the clinician, especially when the long-term stability factor is taken into consideration, because in most cases, individuais who present this type of malocclusion are affected lingual dysfunction, which, if not corrected satisfactorily, will be the factor of anterior open bite relapse. Thus, this paper aims to present a variation introduced in the original design of the Ricketts Quad-Helix appliance, which allows obtaining excellent results in the rehabilitation of the tongue during his peristaltic movements as well as serving as a guide to its rest position.
Assuntos
Humanos , Feminino , Adulto Jovem , Respiração Bucal , Mordida Aberta/reabilitação , Transtornos de Deglutição/reabilitação , Dimensão VerticalRESUMO
El tratamiento de la mordida abierta es siempre un gran desaf¡o para el cl¡nico, principalmente cuando el factor estabilidad a largo plazo es tomado en consideraci¢n, pues en la mayor¡a de las veces, los individuos que presentan este tipo de maloclusiones est n sometidos a disfunci¢n lingual, la cual, si no fuera corregida satisfactoriamente, ser un factor de recidiva de la mordida abierta anterior. Siendo as¡, este trabajo tiene como objetivo, presentar una variaci¢n introducida en el dise¤o original del aparato Quadri hlix de Ricketts, el cual, permite obtener excelentes resultados en la reeducaci¢n de la lengua durante sus movimientos perist lticos, as¡ como, servir de gu¡a para su posici¢n de reposo.
The open bite treatment is always a great challenge for the clinician, especially when the long term stability factor is taken into consideration, because in most cases, individuals who present this type of malocclusion are affected lingual dysfunction, which, if not corrected satisfactorily, will be the factor of anterior open bite relapse. Thus, this paper aims to present a variation introduced in the original design of the Ricketts Quad-Helix appliance, which allows obtaining excellent results in the rehabilitation of the tongue during his peristaltic movements, as well as serving as a guide to its rest position.
Assuntos
Humanos , Masculino , Adolescente , Má Oclusão , Mordida Aberta/terapia , Reabilitação Bucal , Cirurgia Bucal , OrtodontiaRESUMO
A ancoragem, em conjunto com o fator cooperação, éum elemento que contribui para o sucesso do tratamento ortodôntico.Devido a isso, sempre houve por parte da comunidade ortodônticauma preocupação em elaborar dispositivos intra e/ou extrabucal quemantenham a unidade de ancoragem passiva durante o movimentotridimensional da unidade ativa. Dentre tais dispositivos, o mais recentee mais utilizado atualmente é o microimplante, que recebeu novadenominação: ancoragem absoluta. No entanto, este trabalho tevepor finalidade mostrar que a ancoragem cortical continua sendo umaexcelente alternativa para atender a esse objetivo, e que, por intermédiode uma modificação no arco utilidade de Ricketts proposta pelo autor,é possível obter resultados satisfatórios, evitando procedimentosinvasivos e laboratoriais.
The anchorage, together with the cooperation factor,are elements that contribute to the success of orthodontic treatment.Because of this, there has always been part of the community by aconcern to develop orthodontic devices within andjor extraoral tomaintain passive the anchorage unit during three-dimensional movementof the active unit. Among these devices, the latest and most used todayis the microimplant, which received the compound adjective: absoluteanchorage. However, this work aims to show that the cortical anchorageremains an excellent alternative to meet this goal and, through amodified Ricketts utility arch proposed by the author, it is possible toobtain highly satisfactory results and thus prevent, invasive proceduresand laboratory work.
Assuntos
Humanos , Feminino , Procedimentos de Ancoragem Ortodôntica , Ortodontia Corretiva , Extração DentáriaRESUMO
Non-synaptic mechanisms are being considered the common factor of brain damage in status epilepticus and alcohol intoxication. The present work reports the influence of the chronic use of ethanol on epileptic processes sustained by non-synaptic mechanisms. Adult male Wistar rats administered with ethanol (1, 2 e 3 g/kg/d) during 28 days were compared with Control. Non-synaptic epileptiform activities (NEAs) were induced by means of the zero-calcium and high-potassium model using hippocampal slices. The observed involvement of the dentate gyrus (DG) on the neurodegeneration promoted by ethanol motivated the monitoring of the electrophysiological activity in this region. The DG regions were analyzed for the presence of NKCC1, KCC2, GFAP and CD11b immunoreactivity and cell density. The treated groups showed extracellular potential measured at the granular layer with increased DC shift and population spikes (PS), which was remarkable for the group E1. The latencies to the NEAs onset were more prominent also for the treated groups, being correlated with the neuronal loss. In line with these findings were the predispositions of the treated slices for neuronal edema after NEAs induction, suggesting that restrict inter-cell space counteracts the neuronal loss and subsists the hyper-synchronism. The significant increase of the expressions of NKCC1 and CD11b for the treated groups confirms the existence of conditions favorable to the observed edematous necrosis. The data suggest that the ethanol consumption promotes changes on the non-synaptic mechanisms modulating the NEAs. For the lower ethanol dosage the neurophysiological changes were more effective suggesting to be due to the less intense neurodegenertation.
Assuntos
Alcoolismo/fisiopatologia , Antígeno CD11b/metabolismo , Neuroglia/metabolismo , Membro 2 da Família 12 de Carreador de Soluto/metabolismo , Estado Epiléptico/fisiopatologia , Alcoolismo/complicações , Alcoolismo/metabolismo , Alcoolismo/patologia , Animais , Giro Denteado/efeitos dos fármacos , Giro Denteado/patologia , Giro Denteado/fisiopatologia , Etanol/efeitos adversos , Humanos , Técnicas In Vitro , Masculino , Potenciais da Membrana , Neuroglia/efeitos dos fármacos , Ratos , Ratos Wistar , Estado Epiléptico/etiologia , Estado Epiléptico/metabolismo , Estado Epiléptico/patologiaRESUMO
Structural rearrangement of the dentate gyrus has been described as the underlying cause of many types of epilepsies, particularly temporal lobe epilepsy. It is said to occur when aberrant connections are established in the damaged hippocampus, as described in human epilepsy and experimental models. Computer modelling of the dentate gyrus circuitry and the corresponding structural changes has been used to understand how abnormal mossy fibre sprouting can subserve seizure generation observed in experimental models when epileptogenesis is induced by status epilepticus. The model follows the McCulloch-Pitts formalism including the representation of the nonsynaptic mechanisms. The neuronal network comprised granule cells, mossy cells, and interneurons. The compensation theory and the Hebbian and anti-Hebbian rules were used to describe the structural rearrangement including the effects of the nonsynaptic mechanisms on the neuronal activity. The simulations were based on neuroanatomic data and on the connectivity pattern between the cells represented. The results suggest that there is a joint action of the compensation theory and Hebbian rules during the inflammatory process that accompanies the status epilepticus. The structural rearrangement simulated for the dentate gyrus circuitry promotes speculation about the formation of the abnormal mossy fiber sprouting and its role in epileptic seizures.
Assuntos
Giro Denteado/fisiopatologia , Epilepsia/fisiopatologia , Rede Nervosa/fisiologia , Redes Neurais de Computação , Vias Neurais/fisiologia , Sinapses/fisiologia , Algoritmos , Simulação por Computador , Fenômenos Eletrofisiológicos , Humanos , Interneurônios/fisiologia , Modelos Neurológicos , Fibras Musgosas Hipocampais/fisiologia , Agonistas Muscarínicos/farmacologia , Neurônios/fisiologia , Pilocarpina/farmacologia , Receptores de GABA-A/fisiologia , Estado Epiléptico/fisiopatologia , Transmissão SinápticaRESUMO
RESUMO O objetivo da presente pesquisa foi avaliar alguns aspectos relevantes, com potencial de interferência nos índices de fertilidade, de um Centro Comercial de Transferência de Embriões em éguas da raça Brasileiro de Hipismo. A análise dos dados correspondeu às temporadas reprodutivas de 2003/2004, 2004/2005, 2005/2006 e 2006/2007, perfazendo 699 dados de colheitas de embrião de 120 animais doadores. Dentre as 120 éguas doadoras de embrião, havia animais saudáveis sob o aspecto reprodutivo assim como animais com certas dificuldades na manutenção da gestação. Avaliou-se a conservação do sêmen gerador dos embriões, meses do ano de execução das colheitas, idade embrionária e ovulação (simples ou múltipla). Foram observadas diferenças (p 0,05) relativas ao tipo de sêmen empregado nas inseminações artificiais (IAS), somando-se ao expressivo uso de sêmen congelado nas transferências de embrião (TEs); não houve diferença entre o percentual de embriões colhidos dentro ou fora da estação reprodutiva; observou-se diferença (p 0,01), nas colheitas feitas no dia 7, 8 e 9 pós ovulação ao se comparar com as taxas de recuperação dos dias 6 e 10; relativamente ao tipo de ovulação das éguas (ovulação simples ou múltipla), verificou-se que nas ovulações múltiplas colheu-se maior número de embriões (p 0,01) do que nas simples. Palavras-chave: égua doadora; raça Bras
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RESUMO O objetivo da presente pesquisa foi avaliar alguns aspectos relevantes, com potencial de interferência nos índices de fertilidade, de um Centro Comercial de Transferência de Embriões em éguas da raça Brasileiro de Hipismo. A análise dos dados correspondeu às temporadas reprodutivas de 2003/2004, 2004/2005, 2005/2006 e 2006/2007, perfazendo 699 dados de colheitas de embrião de 120 animais doadores. Dentre as 120 éguas doadoras de embrião, havia animais saudáveis sob o aspecto reprodutivo assim como animais com certas dificuldades na manutenção da gestação. Avaliou-se a conservação do sêmen gerador dos embriões, meses do ano de execução das colheitas, idade embrionária e ovulação (simples ou múltipla). Foram observadas diferenças (p 0,05) relativas ao tipo de sêmen empregado nas inseminações artificiais (IAS), somando-se ao expressivo uso de sêmen congelado nas transferências de embrião (TEs); não houve diferença entre o percentual de embriões colhidos dentro ou fora da estação reprodutiva; observou-se diferença (p 0,01), nas colheitas feitas no dia 7, 8 e 9 pós ovulação ao se comparar com as taxas de recuperação dos dias 6 e 10; relativamente ao tipo de ovulação das éguas (ovulação simples ou múltipla), verificou-se que nas ovulações múltiplas colheu-se maior número de embriões (p 0,01) do que nas simples. Palavras-chave: égua doadora; raça Bras
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A sobremordida profunda presente na curva de Spee acentuada é uma característica comum nas maloclusões dento-esqueletais exigindo do profissional muita acuidade e intervenção precoce para se evitar que problemas funcionais e disfunções das articulações temporomandibulares sejam instalados, bem como, o restabelecimento da normalidade do crescimento mandibular. É largamente aceito pela comunidade ortodôntica, como meta de tratamento, a rotação horária da mandíbula no propósito de aumentar a altura facial inferior e, consequentemente, corrigir a sobremordida profunda. Assim, esse protocolo, passa a ser o grande paradigma, pois este trabalho tem como proposta elucidar que a rotação anti-horária da mandíbula deve ser considerada quando estamos diante de um paciente adulto com sobremordida profunda e disfunção articular.
The deep bite present in the Spee accentuated curve is a common characteristic in the dentoskeletal malocclusions demanding from the professional very criterion and earlyintervention to avoid that functional problems and TMJ dysfunctions are installed, as well as, the reestablishment of the mandible growth normality. It is widely accepted by the orthodontics community, as the treatment goals, the mandible clockwise rotation in thepurpose of the increase the lower face height and consequently, to correct the deep bite. And this protocol, passes the being the great (or and this protocol become the great) paradigm, because this work has a proposal to elucidate that the mandible counterclockwise rotation should be considered when we are before an adult patient with deep bite and TMJ dysfunction.
Assuntos
Humanos , Feminino , Adulto , Oclusão Dentária , Aparelhos Ortodônticos , Ortodontia CorretivaRESUMO
K(+) has been appointed as the main physiological inhibitor of the palytoxin (PTX) effect on the Na(+)/K(+) pump. This toxin acts opening monovalent cationic channels through the Na(+)/K(+) pump. We investigate, by means of computational modeling, the kinetic mechanisms related with K(+) interacting with the complex PTX-Na(+)/K(+) pump. First, a reaction model, with structure similar to Albers-Post model, describing the functional cycle of the pump, was proposed for describing K(+) interference on the complex PTX-Na(+)/K(+) pump in the presence of intracellular ATP. A mathematic model was derived from the reaction model and it was possible to solve numerically the associated differential equations and to simulate experimental maneuvers about the PTX induced currents in the presence of K(+) in the intra- and extracellular space as well as ATP in the intracellular. After the model adjusting to the experimental data, a Monte Carlo method for sensitivity analysis was used to analyze how each reaction parameter acts during each experimental maneuver involving PTX. For ATP and K(+) concentrations conditions, the simulations suggest that the enzyme substate with ATP bound to its high-affinity sites is the main substate for the PTX binding. The activation rate of the induced current is limited by the K(+) deocclusion from the PTX-Na(+)/K(+) pump complex. The K(+) occlusion in the PTX induced channels in the enzymes with ATP bound to its low-affinity sites is the main mechanism responsible for the reduction of the enzyme affinity to PTX.
Assuntos
Acrilamidas/farmacologia , Potássio/farmacologia , ATPase Trocadora de Sódio-Potássio/biossíntese , Venenos de Cnidários , Modelos Teóricos , Sensibilidade e EspecificidadeRESUMO
PURPOSE: The aim of this work is to study, by means of computational simulations, the induction and sustaining of nonsynaptic epileptiform activity. METHODS: The computational model consists of a network of cellular bodies of neurons and glial cells connected to a three-dimensional (3D) network of juxtaposed extracellular compartments. The extracellular electrodiffusion calculation was used to simulate the extracellular potential. Each cellular body was represented in terms of the transmembrane ionic transports (Na(+)/K(+) pumps, ionic channels, and cotransport mechanisms), the intercellular electrodiffusion through gap-junctions, and the neuronal interaction by electric field and the variation of cellular volume. RESULTS: The computational model allows simulating the nonsynaptic epileptiform activity and the extracellular potential captured the main feature of the experimental measurements. The simulations of the concomitant ionic fluxes and concentrations can be used to propose the basic mechanisms involved in the induction and sustaining of the activities. DISCUSSION: The simulations suggest: The bursting induction is mediated by the Cl(-) Nernst potential overcoming the transmembrane potential in response to the extracellular [K(+)] increase. The burst onset is characterized by a critical point defined by the instant when the Na(+) influx through its permeable ionic channels overcomes the Na(+)/K(+) pump electrogenic current. The burst finalization is defined by another critical point, when the electrogenic current of the Na(+)/K(+) pump overcomes its influx through the channels.
Assuntos
Encéfalo/fisiopatologia , Epilepsia/epidemiologia , Epilepsia/fisiopatologia , Encéfalo/metabolismo , Simulação por Computador , Epilepsia/diagnóstico , Junções Comunicantes/fisiologia , Humanos , Potenciais da Membrana/fisiologia , Rede Nervosa/metabolismo , Rede Nervosa/fisiopatologia , Neuroglia/fisiologia , Neurônios/fisiologia , Canais de Potássio/metabolismoRESUMO
A mathematical description of the restoring ionic mechanisms in a compartmentalized electrochemical model of neuronal tissues was developed aiming at studying the essential conditions for refractoriness of Leão's spreading depression (SD). The model comprehends the representation of a plexiform layer, composed by synaptic terminals and glial process immersed in an extracellular space where the space-temporal variations of the ionic concentrations were described by electrodiffusion equations. The synaptic transmission was described by differential equations representing the corresponding chemical reactions associated with the neurotransmitter release, diffusion, binding to its receptor in the postsynaptic membrane and the uptake by the presynaptic terminals. The effect of the neurotransmitter binding to the receptor induces changes in the permeability of the postsynaptic membrane and the corresponding transmembrane fluxes were calculated. The fluxes promote changes in the external ionic concentrations, changing the ionic electrodiffusion through the extracellular space. The description of these mechanisms provides the reaction-diffusion structure of the model and allows simulating the wave propagation. The simulations of experimental maneuvers of application of two consecutive stimuli for inducing SD suggest: (i) the extracellular space acts coupling the postsynaptic terminals and glial cells recovery mechanisms in such a way that the extracellular ionic concentrations change only during the wave front; (ii) the potassium removed from the extracellular by the glial cells, originated from the depolarization of the synaptic terminals returns slowly limited by the glial release, contributing for the refractoriness of the tissue; (iii) critical points for sodium and potassium transmembrane fluxes could be identified, allowing proposing specific conditions for the interplay between channels and pumps fluxes for determining the absolute and relative refractory periods.
Assuntos
Simulação por Computador , Potenciais da Membrana/fisiologia , Modelos Neurológicos , Neurotransmissores/metabolismo , Terminações Pré-Sinápticas/fisiologia , Transmissão Sináptica/fisiologia , Algoritmos , Difusão , Campos Eletromagnéticos , Espaço Extracelular/metabolismo , Neuroglia/metabolismo , Potássio/metabolismo , Sódio/metabolismoRESUMO
The ATP hydrolysis reactions responsible for the Na(+)/K(+)-ATPase phosphorylation, according to recent experimental evidences, also occur for the PTX-Na(+)/K(+) pump complex. Moreover, it has been demonstrated that PTX interferes with the enzymes phosphorylation status. However, the reactions involved in the PTX-Na(+)/K(+) pump complex phosphorylation are not very well established yet. This work aims at proposing a reaction model for PTX-Na(+)/K(+) pump complex, with similar structure to the Albers-Post model, to contribute to elucidate the PTX effect over Na(+)/K(+)-ATPase phosphorylation and dephosphorylation. Computational simulations with the proposed model support several hypotheses and also suggest: (i) phosphorylation promotes an increase of the open probability of induced channels; (ii) PTX reduces the Na(+)/K(+) pump phosphorylation rate; (iii) PTX may cause conformational changes to substates where the Na(+)/K(+)-ATPase may not be phosphorylated; (iv) PTX can bind to substates of the two principal states E1 and E2, with highest affinity to phosphorylated enzymes and with ATP bound to its low-affinity sites. The proposed model also allows previewing the behavior of the PTX-pump complex substates for different levels of intracellular ATP concentrations.
Assuntos
Acrilamidas/química , Modelos Biológicos , ATPase Trocadora de Sódio-Potássio/química , Venenos de Cnidários , Simulação por Computador , FosforilaçãoRESUMO
O presente artigo objetivou mostrar a eficiência dos vários desenhos do aparelho quadrihélice, de Ricketts, na correção das desarmonias dentoalveolares. Devido às suas várias formas de confecção, assim como de sua ativação, o quadrihélice tornou-se um acessório útil não somente na sobrecorreção da discrepância transversal e sagital, mas também no tratamento das más oclusões da Classe II, divisão 1, de Angle, principalmente nos casos em que a rotação do molar é desejada como parte do tratamento. Também é relevante o seu efeito no tratamento das mordidas abertas anteriores, atuando como coadjuvante no tratamento dos fatores ambientais que contribuem, muitas vezes, para exacerbar o desenvolvimento das más oclusões. Em relação ao alinhamento do arco dentário, o quadrihélice abrevia essa fase do tratamento em 4 a 5 meses (o tratamento convencional levaria muito mais tempo e pelo menos uma grande série de troca de arcos em mecânicas de nivelamento). Portanto, este trabalho tem a intenção de mostrar algumas das ativações possíveis do aparelho quadrihélice, bem como algumas de suas variações, que contribuem para conseguir resultados estáveis em longo prazo.