Sympathetic Activation and Baroreflex Function during Intradialytic Hypertensive Episodes

BACKGROUND: The mechanisms of intradialytic increases in blood pressure are not well defined. The present study was undertaken to assess the role of autonomic nervous system activation during intradialytic hypertensive episodes. METHODOLOGY/PRINCIPAL FINDINGS: Continuous interbeat intervals (IBI) and systolic blood pressure (SBP) were monitored during hemodialysis in 108 chronic patients. Intradialytic hypertensive episodes defined as a period of at least 10 mmHg increase in SBP between the beginning and the end of a dialysis session or hypertension resistant to ultrafiltration occurring during or immediately after the dialysis procedure, were detected in 62 out of 113 hemodialysis sessions. SBP variability, IBI variability and baroreceptor sensitivity (BRS) in the low (LF) and high (HF) frequency ranges were assessed using the complex demodulation technique (CDM). Intradialytic hypertensive episodes were associated with an increased (n = 45) or decreased (n = 17) heart rate. The maximal blood pressure was similar in both groups. In patients with increased heart rate the increase in blood pressure was associated with marked increases in SBP and IBI variability, with suppressed BRS indices and enhanced sympatho-vagal balance. In contrast, in those with decreased heart rate, there were no significant changes in the above parameters. End-of-dialysis blood pressure in all sessions associated with hypertensive episode was significantly higher than in those without such episodes. In logistic regression analysis, predialysis BRS in the low frequency range was found to be the main predictor of intradialytic hypertension. CONCLUSION/SIGNIFICANCE: Our data point to sympathetic overactivity with feed-forward blood pressure enhancement as an important mechanism of intradialytic hypertension in a significant proportion of patients. The triggers of increased sympathetic activity during hemodialysis remain to be determined. Intradialytic hypertensive episodes are associated with higher end-of-dialysis blood pressure, suggesting that intradialytic hypertension may play a role in generation of interdialytic hypertension

A Reflection on Economic Uncertainty and Fertility in Europe: The Narrative Framework

none5openVignoli, Daniele; Guetto, Raffaele; Bazzani, Giacomo; Pirani, Elena; Minello, AlessandraVignoli, Daniele; Guetto, Raffaele; Bazzani, Giacomo; Pirani, Elena; Minello, Alessandr

Gonadal development in the freshwater crab Sylviocarcinus pictus (H. Milne Edwards, 1853) (Brachyura: Trichodactylidae) from the Guamá river, state of Pará, Brazil

The development stages of male and female gonads in the freshwater crab Sylviocarcinus pictus (H. Milne Eduards, 1853) were described through macroscopic and microscopic (histology) examinations. The histological description was based on 40 specimens (20 each sex). Four gonadal development stages were found for females: immature, ripening, mature and spawned. The following female cells were found: ovogonia, oocytes in initial vitellogenesis, oocytes in advanced vitellogenesis, follicular cells and post-ovulatory follicles. Three development stages were found for males: immature, maturing and mature, with the indication of: spermatogonia, spermatocytes, spermatids, spermatozoids and spermatophores. These data suggest the pattern described in the literature. Size at sexual maturity was 32.3 mm of carapace width for males and 31.5 mm for females. The gonadal stages observed macroscopically by volume and color were validated through histological analysis and proved to be useful method for the rapid identification of sexual maturity in the species. The present study offers previously unpublished data on the reproductive biology of Sylviocarcinus pictus.<br>Os estádios de desenvolvimento das gônadas de machos e fêmeas de caranguejos Sylviocarcinus pictus (H. Milne Eduards, 1853) foram descritos por meio de observações macroscópicas e microscópicas (técnica histológica). A descrição histológica foi baseada em 40 espécimes (20 de cada sexo). Foram identificados quatro estádios de desenvolvimento para as fêmeas: imaturo, em maturação, maturo e em reabsorção. As seguintes células foram encontradas: ovogônias, ovócitos em vitelogênese inicial, ovócitos em vitelogênese avançada, células foliculares e folículos pós-ovulatórios. Três estádios de desenvolvimento foram encontrados para os machos: imaturo, em maturação e maturo, com indicação de: espermatogônias, espermatócitos, espermátides, espermatozóides e espermatóforos. Tais dados sugerem o padrão descrito na literatura. O tamanho da maturidade sexual foi de 32,3 mm de largura da carapaça para machos e 31,5 mm para fêmeas. Os estádios gonadais observados macroscopicamente por meio do volume e da coloração das gônadas foram validados pela análise histológica, sendo um critério útil e ágil para a identificação da maturidade sexual para a espécie. O presente estudo oferece informações inéditas sobre a biologia reprodutiva de Sylviocarcinus pictus