38 research outputs found
Stress-controlled hysteresis and long-time dynamics of implicit differential equations arising in hypoplasticity
summary:A long-time dynamic for granular materials arising in the hypoplastic theory of Kolymbas type is investigated. It is assumed that the granular hardness allows exponential degradation, which leads to the densification of material states. The governing system for a rate-independent strain under stress control is described by implicit differential equations. Its analytical solution for arbitrary inhomogeneous coefficients is constructed in closed form. Under cyclic loading by periodic pressure, finite ratcheting for the void ratio is derived in explicit form, which converges to a limiting periodic process (attractor) when the number of cycles tends to infinity
Extremal solutions of systems of measure differential equations and applications in the study of Stieltjes differential problems
We use lower and upper solutions to investigate the existence of the greatest and the least solutions for quasimonotone systems of measure differential equations. The established results are then used to study the solvability of Stieltjes differential equations; a recent unification of discrete, continuous and impulsive systems. The applicability of our results is illustrated in a simple model for bacteria population
Induction of Heme Oxygenase-1 Can Halt and Even Reverse Renal Tubule-Interstitial Fibrosis
Background: The tubule-interstitial fibrosis is the hallmark of progressive renal disease and is strongly associated with inflammation of this compartment. Heme-oxygenase-1 (HO-1) is a cytoprotective molecule that has been shown to be beneficial in various models of renal injury. However, the role of HO-1 in reversing an established renal scar has not yet been addressed. Aim: We explored the ability of HO-1 to halt and reverse the establishment of fibrosis in an experimental model of chronic renal disease. Methods: Sprague-Dawley male rats were subjected to unilateral ureteral obstruction (UUO) and divided into two groups: non-treated and Hemin-treated. To study the prevention of fibrosis, animals were pre-treated with Hemin at days -2 and -1 prior to UUO. To investigate whether HO-1 could reverse established fibrosis, Hemin therapy was given at days 6 and 7 post-surgery. After 7 and/or 14 days, animals were sacrificed and blood, urine and kidney tissue samples were collected for analyses. Renal function was determined by assessing the serum creatinine, inulin clearance, proteinuria/creatininuria ratio and extent of albuminuria. Arterial blood pressure was measured and fibrosis was quantified by Picrosirius staining. Gene and protein expression of pro-inflammatory and pro-fibrotic molecules, as well as HO-1 were performed. Results: Pre-treatment with Hemin upregulated HO-1 expression and significantly reduced proteinuria, albuminuria, inflammation and pro-fibrotic protein and gene expressions in animals subjected to UUO. Interestingly, the delayed treatment with Hemin was also able to reduce renal dysfunction and to decrease the expression of pro-inflammatory molecules, all in association with significantly reduced levels of fibrosis-related molecules and collagen deposition. Finally, TGF-beta protein production was significantly lower in Hemin-treated animals. Conclusion: Treatment with Hemin was able both to prevent the progression of fibrosis and to reverse an established renal scar. Modulation of inflammation appears to be the major mechanism behind HO-1 cytoprotection.Fundacao de Amparo Pesquisa do Estado de Sao Paulo-FAPESP[07/07139-3]Coordenaco de Aperfeioamento de Pessoal de Nivel Superior-CAPESInstituto Nacional de Ciencia e Tecnologia de Complexos Fluidos (INCT)Conselho Nacional de Desenvolvimento Cientifico e Tecnologico-CNP
Diretriz da Sociedade Brasileira de Cardiologia sobre Diagnóstico e Tratamento de Pacientes com Cardiomiopatia da Doença de Chagas
This guideline aimed to update the concepts and formulate the standards of conduct and scientific evidence that support them, regarding the diagnosis and treatment of the Cardiomyopathy of Chagas disease, with special emphasis on the rationality base that supported it.
Chagas disease in the 21st century maintains an epidemiological pattern of endemicity in 21 Latin American countries. Researchers and managers from endemic and non-endemic countries point to the need to adopt comprehensive public health policies to effectively control the interhuman transmission of T. cruzi infection, and to obtain an optimized level of care for already infected individuals, focusing on diagnostic and therapeutic opportunistic opportunities.
Pathogenic and pathophysiological mechanisms of the Cardiomyopathy of Chagas disease were revisited after in-depth updating and the notion that necrosis and fibrosis are stimulated by tissue parasitic persistence and adverse immune reaction, as fundamental mechanisms, assisted by autonomic and microvascular disorders, was well established. Some of them have recently formed potential targets of therapies.
The natural history of the acute and chronic phases was reviewed, with enhancement for oral transmission, indeterminate form and chronic syndromes. Recent meta-analyses of observational studies have estimated the risk of evolution from acute and indeterminate forms and mortality after chronic cardiomyopathy. Therapeutic approaches applicable to individuals with Indeterminate form of Chagas disease were specifically addressed. All methods to detect structural and/or functional alterations with various cardiac imaging techniques were also reviewed, with recommendations for use in various clinical scenarios. Mortality risk stratification based on the Rassi score, with recent studies of its application, was complemented by methods that detect myocardial fibrosis.
The current methodology for etiological diagnosis and the consequent implications of trypanonomic treatment deserved a comprehensive and in-depth approach. Also the treatment of patients at risk or with heart failure, arrhythmias and thromboembolic events, based on pharmacological and complementary resources, received special attention. Additional chapters supported the conducts applicable to several special contexts, including t. cruzi/HIV co-infection, risk during surgeries, in pregnant women, in the reactivation of infection after heart transplantation, and others.
Finally, two chapters of great social significance, addressing the structuring of specialized services to care for individuals with the Cardiomyopathy of Chagas disease, and reviewing the concepts of severe heart disease and its medical-labor implications completed this guideline.Esta diretriz teve como objetivo principal atualizar os conceitos e formular as normas de conduta e evidĂȘncias cientĂficas que as suportam, quanto ao diagnĂłstico e tratamento da CDC, com especial ĂȘnfase na base de racionalidade que a embasou.
A DC no sĂ©culo XXI mantĂ©m padrĂŁo epidemiolĂłgico de endemicidade em 21 paĂses da AmĂ©rica Latina. Investigadores e gestores de paĂses endĂȘmicos e nĂŁo endĂȘmicos indigitam a necessidade de se adotarem polĂticas abrangentes, de saĂșde pĂșblica, para controle eficaz da transmissĂŁo inter-humanos da infecção pelo T. cruzi, e obter-se nĂvel otimizado de atendimento aos indivĂduos jĂĄ infectados, com foco em oportunização diagnĂłstica e terapĂȘutica.
Mecanismos patogĂȘnicos e fisiopatolĂłgicos da CDC foram revisitados apĂłs atualização aprofundada e ficou bem consolidada a noção de que necrose e fibrose sejam estimuladas pela persistĂȘncia parasitĂĄria tissular e reação imune adversa, como mecanismos fundamentais, coadjuvados por distĂșrbios autonĂŽmicos e microvasculares. Alguns deles recentemente constituĂram alvos potenciais de terapĂȘuticas.
A histĂłria natural das fases aguda e crĂŽnica foi revista, com realce para a transmissĂŁo oral, a forma indeterminada e as sĂndromes crĂŽnicas. MetanĂĄlises recentes de estudos observacionais estimaram o risco de evolução a partir das formas aguda e indeterminada e de mortalidade apĂłs instalação da cardiomiopatia crĂŽnica. Condutas terapĂȘuticas aplicĂĄveis aos indivĂduos com a FIDC foram abordadas especificamente. Todos os mĂ©todos para detectar alteraçÔes estruturais e/ou funcionais com variadas tĂ©cnicas de imageamento cardĂaco tambĂ©m foram revisados, com recomendaçÔes de uso nos vĂĄrios cenĂĄrios clĂnicos. Estratificação de risco de mortalidade fundamentada no escore de Rassi, com estudos recentes de sua aplicação, foi complementada por mĂ©todos que detectam fibrose miocĂĄrdica.
A metodologia atual para diagnĂłstico etiolĂłgico e as consequentes implicaçÔes do tratamento tripanossomicida mereceram enfoque abrangente e aprofundado. TambĂ©m o tratamento de pacientes em risco ou com insuficiĂȘncia cardĂaca, arritmias e eventos tromboembĂłlicos, baseado em recursos farmacolĂłgicos e complementares, recebeu especial atenção. CapĂtulos suplementares subsidiaram as condutas aplicĂĄveis a diversos contextos especiais, entre eles o da co-infecção por T. cruzi/HIV, risco durante cirurgias, em grĂĄvidas, na reativação da infecção apĂłs transplante cardĂacos, e outros.
Por fim, dois capĂtulos de grande significado social, abordando a estruturação de serviços especializados para atendimento aos indivĂduos com a CDC, e revisando os conceitos de cardiopatia grave e suas implicaçÔes mĂ©dico-trabalhistas completaram esta diretriz. 
On Kurzweil-Stieltjes equiintegrability and generalized BV functions
summary:We present sufficient conditions ensuring Kurzweil-Stieltjes equiintegrability in the case when integrators belong to the class of functions of generalized bounded variation