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1.
Glob Cardiol Sci Pract ; 2015: 10, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26779498

RESUMO

The heart is subject to multiple sources of stress. To maintain its normal function, and successfully overcome these stresses, heart muscle is equipped with fine-tuned regulatory mechanisms. Some of these mechanisms are inherent within the myocardium itself and are known as intrinsic mechanisms. Over a century ago, Otto Frank and Ernest Starling described an intrinsic mechanism by which the heart, even ex vivo, regulates its function on a beat-to-beat basis. According to this phenomenon, the higher the ventricular filling is, the bigger the stroke volume. Thus, the Frank-Starling law establishes a direct relationship between the diastolic and systolic function of the heart. To observe this biophysical phenomenon and to investigate it, technologic development has been a pre-requisite to scientific knowledge. It allowed for example to observe, at the cellular level, a Frank-Starling like mechanism and has been termed: Length Dependent Activation (LDA). In this review, we summarize some experimental systems that have been developed and are currently still in use to investigate cardiac biophysical properties from the whole heart down to the single myofibril. As a scientific support, investigation of the Frank-Starling mechanism will be used as a case study.

2.
Transplantation ; 74(2): 194-202, 2002 Jul 27.
Artigo em Inglês | MEDLINE | ID: mdl-12151731

RESUMO

BACKGROUND: Posttransplant lymphoproliferative disease (PTLD) is a common Epstein-Barr virus (EBV)-associated complication of transplantation which, despite treatment, is often fatal. This study was undertaken to monitor persistent EBV infection in transplant recipients, to compare EBV load and gene expression in healthy individuals and EBV-associated diseases, and to highlight differences in PTLD that could be used to define those at risk of the disease. METHODS: A cohort of 96 cardiothoracic transplant recipients was monitored posttransplant for up to 1110 days (median 268 days). Levels of EBV DNA and viral mRNA transcripts in peripheral blood mononuclear cells (PBMs) were measured at regular intervals and compared with those found in healthy individuals, infectious mononucleosis (IM) patients, and 12 PTLD patients bled at the time of diagnosis. Overall posttransplant levels were significantly higher than pretransplant and healthy subjects, and correlate with dose of immunosuppression. EBV DNA levels in both IM and PTLD were significantly higher than in healthy recipients, with the highest levels in PTLD patients. Individual measurements in 12 healthy transplant recipients reached levels seen in PTLD, and thus single estimations are not of predictive significance for PTLD development. RESULTS: Analysis of viral gene expression in peripheral blood mononuclear cells showed a restricted (LMP 2 only) pattern in healthy subjects, and an unrestricted (latency 3) pattern with lytic replication in 14% of IM blood and 45% of cases of PTLD. A total of 55% of healthy transplant recipients had additional transcripts in one or more blood samples, and this finding correlated with high viral load. Analysis of the 12 samples from healthy recipients with viral loads equivalent to those seen in PTLD showed additional transcripts in all cases and latency 3 with lytic replication in 33%. Thus, an isolated finding of high viral load and/or unrestricted latent and lytic gene expression is not indicative of PTLD.


Assuntos
Transplante de Coração/efeitos adversos , Herpesvirus Humano 4/genética , Transplante de Pulmão/efeitos adversos , Adolescente , Adulto , Idoso , DNA Viral/análise , Feminino , Dosagem de Genes , Expressão Gênica , Humanos , Terapia de Imunossupressão , Transtornos Linfoproliferativos/virologia , Masculino , Pessoa de Meia-Idade , RNA Viral/análise , Carga Viral
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