Alterações da Rigidez Arterial em Pacientes com Estenose Aórtica Grave Submetidos à Cirurgia de Troca Valvar / Arterial Stiffness Changes in Severe Aortic Stenosis Patients Submitted to Valve Replacement Surgery

Resumo Fundamento: Pouco se sabe sobre o impacto da estenose aórtica (EA) grave na rigidez aórtica e se ocorre alguma alteração após a remoção da barreira de EA com a cirurgia de substituição da válvula aórtica (SVA). Objetivo: Estimar as mudanças na velocidade de onda de pulso carotídeo-femoral (VOP) após a cirurgia de SVA e definir os preditores de VOP alta em pacientes com EA grave. Métodos: Estudo de coorte retrospectivo unicêntrico, incluindo pacientes com EA grave submetidos à cirurgia de SVA com bioprótese, entre fevereiro de 2017 e janeiro de 2019, e medições da VOP (Complior®) antes e depois do procedimento (2±1 meses). Antes e depois da SVA, os valores da VOP foram comparados por meio de testes pareados. foram analisadas as associações de VOP com dados clínicos, bem como aplicados modelos de regressão linear multivariada para estimar os preditores independentes da VOP pré- e pós-operatória. O nível de significância foi estabelecido em 5%. Resultados: Foram incluídos na amostra 150 pacientes, com média de idade de 72±8 anos, sendo 51% deles do sexo masculino. Identificamos um aumento estatisticamente significativo nos valores de VOP após a cirurgia (9,0 ± 2,1 m/s vs. 9,9 ± 2,2, p<0,001, antes e depois da SVA, respectivamente) e uma associação inversa com as variáveis de gravidade da EA. No modelo de regressão linear multivariada, idade e pressão arterial sistólica (PAS) foram estabelecidas como preditores independentes da VOP pré- e pós-operatória mais alta, enquanto o gradiente valvar médio mais alto foi considerado um determinante da VOP pré-SVA mais baixa. Conclusão: Identificamos uma correlação inversa da rigidez arterial com a gravidade da EA em pacientes acometidos, e um aumento significativo nos valores da VOP após a cirurgia de SVA. Idade avançada e PAS elevada foram associadas a valores mais altos da VOP, embora as medidas de função arterial estivessem dentro da normalidade. (Arq Bras Cardiol. 2021; 116(3):475-476)

Abstract Background: Little is known about the impact of severe aortic stenosis (AS) in aortic stiffness and if there is any change after removing AS barrier with aortic valve replacement (AVR) surgery. Objective: To estimate carotid-femoral pulse wave velocity (PWV) changes after AVR surgery and to define PWV predictors in severe AS patients. Methods: Single-center retrospective cohort, including patients with severe AS who underwent AVR surgery with bioprostheses, between February 2017 and January 2019 and performed PWV measurements (Complior®) before and after the procedure (2±1 months). Before and after AVR, PWV values were compared through paired tests. The associations of PWV with clinical data were studied and linear regression models were applied to estimate pre and postoperative PWV independent predictors. The significance level was set at 5%. Results: We included 150 patients in the sample, with mean age of 72±8 years, and 51% being males. We found a statistically significant increase in PWV values after surgery (9.0±2.1 m/s vs. 9.9±2.2, p<0.001, before and after AVR, respectively) and an inverse association with AS severity variables. In the linear regression model, age and systolic blood pressure (SBP) were established as independent predictors of higher pre- and postoperative PWV, while higher mean valvular gradient emerged as a determinant of lower pre-AVR PWV. Conclusion: We documented an inverse correlation of arterial stiffness with the severity of AS in patients with AS, and a significant increase in PWV values after AVR surgery. Advanced age and higher SBP were associated with higher PWV values, although arterial function measurements were within the normal range. (Arq Bras Cardiol. 2021; 116(3):475-482)

Population structure and genetic variability of mainland and insular populations of the Neotropical water rat, Nectomys squamipes (Rodentia, Sigmodontinae)

Seven microsatellite loci were used to investigate the genetic variability and structure of six mainland and two island populations of the Neotropical water rat Nectomys squamipes, a South American semi-aquatic rodent species with a wide distribution. High levels of variability were found within mainland populations while island populations were less variable but the more differentiated in respect to allele number and frequency. The time of biological divergence between mainland and island populations coincided with geological data. A significant geographic structure was found in mainland populations (q = 0.099; r = 0.086) although the degree of differentiation was relatively low in respect to the distance between surveyed localities (24 to 740 km). Genetic and geographic distances were not positively correlated as previously found with random amplified polymorphic DNA (RAPD) markers. Significant but low genetic differentiation in the mainland and lack of isolation by distance can be explained by large population size and/or recent population expansion. Additionally, the agreement between the age of geologic events (sea level fluctuations) and divergence times for insular populations points to a good reference for molecular clock calibration to associate recent environmental changes and the distribution pattern of small mammals in the Brazilian Atlantic Forest

Experimental evidence and ecological perspectives for the adaptation of Schistosoma mansoni Sambon, 1907 (Digenea: Schistosomatidae) to a wild host, the water-rat, Nectomys squamipes Brants, 1827 (Rodentia: Sigmodontinae)

Due to the semi aquatic habits and the overlap of the geographical distribution of the water-rat, Nectomys spp., with schistosomiasis endemic areas, these wild rodents are very likely to acquire Schistosoma mansoni infection in their daily activities. The role of the water-rat in the S. mansoni cycle would be substantiated if one could prove that these rodents acquire the parasite during their own activity time, a completely independent time schedule of human activities. To pursue this goal, we performed two field experiments in the municipality of Sumidouro, State of Rio de Janeiro, Brazil, a schistosomiasis endemic area where N. squamipes is found naturally infected. One experiment was devised as a series of observations of activity time of the water-rat. The other experiment was a test of the occurrence of late transmission of S. mansoni to the water-rat. The daily activity pattern showed that the water-rat is active chiefly just after sunset. At both diurnal and late exposition essays the water-rat sentinels got infected by S. mansoni. These findings clarify ecological and behavioral components necessary to the adaptation of S. mansoni to the water-rat as a non human definitive host and the existence of a transmission cycle involving this animals as a reservoir

Density dependence in within-habitat spatial distribution: contrasting patterns for a rodent and a marsupial in southeastern Brazil

We investigated the relationship between population densities of two species of small mammals and the degree of aggregation in their spatial distributions within a habitat at the Restinga de Barra de Maric , in Rio de Janeiro State. The distribution of the redent Akodon cursor was more clumped at low than at high densities. On the other hand, the aggregation of the marsupial Philander opossum was independent of its abundance. Population density must be included as a variable in quantitative analyses of habitat preferences of those species which, like A. cursor but not P. opossum, show different degrees of habitat selectivity at different population densities.