72 research outputs found
Efeito do modelo da suspensão do caminhão sobre comportamento dos suÃnos durante o perÃodo de descanso no frigorÃfico.
Projeto/Plano de Ação: 03.08.06.008
Fractal correlation property of heart rate variability in chronic obstructive pulmonary disease
Background: It was reported that autonomic nervous system function is altered in subjects with chronic obstructive pulmonary disease (COPD). We evaluated short-and long-term fractal exponents of heart rate variability (HRV) in COPD subjects.Patients and methods: We analyzed data from 30 volunteers, who were divided into two groups according to spirometric values: COPD (n = 15) and control (n = 15). for analysis of HRV indices, HRV was recorded beat by beat with the volunteers in the supine position for 30 minutes. We analyzed the linear indices in the time (SDNN [standard deviation of normal to normal] and RMSSD [root-mean square of differences]) and frequency domains (low frequency [LF], high frequency [HF], and LF/HF), and the short-and long-term fractal exponents were obtained by detrended fluctuation analysis. We considered P < 0.05 to be a significant difference.Results: COPD patients presented reduced levels of all linear exponents and decreased short-term fractal exponent (alpha-1: 0.899 +/- 0.18 versus 1.025 +/- 0.09, P = 0.026). There was no significant difference between COPD and control groups in alpha-2 and alpha-1/alpha-2 ratio.Conclusion: COPD subjects present reduced short-term fractal correlation properties of HRV, which indicates that this index can be used for risk stratification, assessment of systemic disease manifestations, and therapeutic procedures to monitor those patients.Fundação para o Desenvolvimento da UNESP (FUNDUNESP)Univ Estadual Paulista, Fac Ciencias & Tecnol, Dept Fisioterapia, São Paulo, BrazilUniversidade Federal de São Paulo, Disciplina Cardiol, Dept Med, São Paulo, BrazilFac Med Sao Jose do Rio Preto, Dept Cardiol & Cirurgia Cardiovasc, São Paulo, BrazilUniv Estadual Londrina, Lab Pesquisa Fisioterapia Pulm, Dept Fisioterapia, Londrina, BrazilFac Med ABC, Dept Morfol & Fisiol, Santo Andre, BrazilUniversidade Federal de São Paulo, Disciplina Cardiol, Dept Med, São Paulo, BrazilFUNDUNESP: 00704/08 - DFPWeb of Scienc
Polyamine Sharing between Tubulin Dimers Favours Microtubule Nucleation and Elongation via Facilitated Diffusion
We suggest for the first time that the action of multivalent cations on
microtubule dynamics can result from facilitated diffusion of GTP-tubulin to the
microtubule ends. Facilitated diffusion can promote microtubule assembly,
because, upon encountering a growing nucleus or the microtubule wall, random
GTP-tubulin sliding on their surfaces will increase the probability of
association to the target sites (nucleation sites or MT ends).
This is an original explanation for understanding the apparent discrepancy
between the high rate of microtubule elongation and the low rate of tubulin
association at the microtubule ends in the viscous cytoplasm. The mechanism of
facilitated diffusion requires an attraction force between two tubulins, which
can result from the sharing of multivalent counterions. Natural polyamines
(putrescine, spermidine, and spermine) are present in all
living cells and are potent agents to trigger tubulin self-attraction. By using
an analytical model, we analyze the implication of facilitated diffusion
mediated by polyamines on nucleation and elongation of microtubules. In
vitro experiments using pure tubulin indicate that the promotion of
microtubule assembly by polyamines is typical of facilitated diffusion. The
results presented here show that polyamines can be of particular importance for
the regulation of the microtubule network in vivo and provide
the basis for further investigations into the effects of facilitated diffusion
on cytoskeleton dynamics
Strength gain through eccentric isotonic training without changes in clinical signs or blood markers
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