Critical analysis of autoregressive and fast Fourier transform markers of cardiovascular variability in rats and humans

The autonomic nervous system plays an important role in physiological and pathological conditions, and has been extensively evaluated by parametric and non-parametric spectral analysis. To compare the results obtained with fast Fourier transform (FFT) and the autoregressive (AR) method, we performed a comprehensive comparative study using data from humans and rats during pharmacological blockade (in rats), a postural test (in humans), and in the hypertensive state (in both humans and rats). Although postural hypotension in humans induced an increase in normalized low-frequency (LFnu) of systolic blood pressure, the increase in the ratio was detected only by AR. In rats, AR and FFT analysis did not agree for LFnu and high frequency (HFnu) under basal conditions and after vagal blockade. The increase in the LF/HF ratio of the pulse interval, induced by methylatropine, was detected only by FFT. In hypertensive patients, changes in LF and HF for systolic blood pressure were observed only by AR; FFT was able to detect the reduction in both blood pressure variance and total power. In hypertensive rats, AR presented different values of variance and total power for systolic blood pressure. Moreover, AR and FFT presented discordant results for LF, LFnu, HF, LF/HF ratio, and total power for pulse interval. We provide evidence for disagreement in 23% of the indices of blood pressure and heart rate variability in humans and 67% discordance in rats when these variables are evaluated by AR and FFT under physiological and pathological conditions. The overall disagreement between AR and FFT in this study was 43%.FINEPFAPESPZerbini Foundatio

The Removal Of Cu(ii) And Co(ii) From Aqueous Solutions Using Cross-linked Chitosan-evaluation By The Factorial Design Methodology

A 23 factorial design was employed to evaluate the quantitative removal of Cu(II) and Co(II) on glutaraldehyde-cross-linked chitosan from kinetic isotherms, using chitosan masses of 100 and 300 mg and temperatures of 25 and 35 °C. The adsorption parameters were analyzed statistically using modeling polynomial equations and a cumulative normal probability plot. The results indicated the higher quantitative preference of the chitosan for Cu(II) in relation to Co(II). Increasing the chitosan mass decreases the adsorption/mass ratio (mol g-1) for both metals. The principal effect of the temperature did not show statistical importance. The adsorption thermodynamic parameters, namely ΔadsH, ΔadsG and ΔadsS, were determined. Exothermic and endothermic results were found in relation to a specific factorial design experiment. A comparison of ΔadsH values was made in relation to some metal-adsorbent interactions in literature. It is suggested that the adsorption thermodynamic parameters are determined by the influence of the principal and interactive experimental parameters and not by the temperature changes alone. © 2006 Elsevier B.V. All rights reserved.14301/02/15816United States Environmental Protection Agency (USEPA), (1992) National Primary Drinking Water Regulations, , USEPA, USACrini, G., Recent developments in polysaccharide-based materials used as adsorbents in wastewater treatment (2005) Prog. Polym. Sci., 30, pp. 38-70Guibal, E., Interactions of metal ions with chitosan-based sorbents: a review (2004) Separ. Purif. Technol., 38, pp. 43-74Guibal, E., Heterogeneous catalysis on chitosan-based materials: a review (2005) Prog. Polym. Sci., 30, pp. 71-109Varma, A.J., Deshpande, S.V., Kennedy, J.F., Metal complexation by chitosan and its derivatives: a review (2004) Carbohydr. 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Acute AT1 receptor blockade does not improve the depressed baroreflex in rats with chronic renal hypertension

To assess the role of angiotensin II in the sensitivity of the baroreflex control of heart rate (HR) in normotensive rats (N = 6) and chronically hypertensive rats (1K1C, 2 months, N = 7), reflex changes of HR were evaluated before and after (15 min) the administration of a selective angiotensin II receptor antagonist (losartan, 10 mg/kg, iv). Baseline values of mean arterial pressure (MAP) were higher in hypertensive rats (195 ± 6 mmHg) than in normotensive rats (110 ± 2 mmHg). Losartan administration promoted a decrease in MAP only in hypertensive rats (16%), with no changes in HR. During the control period, the sensitivity of the bradycardic and tachycardic responses to acute MAP changes were depressed in hypertensive rats (~70% and ~65%, respectively) and remained unchanged after losartan administration. Plasma renin activity was similar in the two groups. The present study demonstrates that acute blockade of AT1 receptors with losartan lowers the MAP in chronic renal hypertensive rats without reversal of baroreflex hyposensitivity, suggesting that the impairment of baroreflex control of HR is not dependent on an increased angiotensin II level

In Vivo Study Of Lyophilized Bioprostheses: 3 Month Follow-up In Young Sheep [estudo In Vivo Do Comportamento De Bioprótese Liofilizada: Seguimento De 3 Meses Em Carneiros Jovens]

Objective: Glutaraldehyde is currently used in bovine pericardium bioprosthesis to improve mechanical and immunogenic properties. Lyophilization is a process that may decrease aldehyde residues in the glutaraldehyde treated pericardium decreasing cytotoxicity and enhancing resistance to calcification. The aim of this study is to evaluate bioprosthetic heart valves calcification in adolescent sheep and to study the potential of lyophilization as a mechanism to protect calcification. Methods: Two groups were evaluated: a control group in which a bovine pericardium prosthetic valve was implanted in pulmonary position and a lyophilized group in which the bovine pericardium prosthetic valve was lyophilized and further implanted. Sixteen sheeps 6 months old were submitted to the operation procedure. After 3 months the sheeps were euthanized under full anesthesia. Results: Six animals of the control group reached 95.16 ± 3.55 days and six animals in the lyophilized group reached 91.66 ± 0.81 days of postoperative evolution. Two animals had endocarditis. Right ventricle/pulmonary artery (RV/PA) mean gradient, in the control group, at the implantation was 2.04 ± 1.56 mmHg, in the lyophilization group, the RV/PA mean gradient, at the implantation was 6.61 ± 4.03 mmHg. At the explantation it increased to 7.71 ± 3.92 mmHg and 8.24 ± 6.25 mmHg, respectively, in control and lyophilization group. The average calcium content, after 3 months, in the control group was 21.6 ± 39.12 μg Ca+2/mg dry weight, compared with an average content of 41.19 ± 46.85 μg Ca+2/mg dry weight in the lyophilization group (P=0.662). Conclusion: Freeze drying of the bovine pericardium prosthesis in the pulmonary position could not demonstrate calcification mitigation over a 3 month period although decreased inflammatory infiltration over the tissue.274592599Rahimtoola, S.H., Choice of prosthetic heart valve in adults an update (2010) J Am Coll Cardiol., 55 (22), pp. 2413-2426David, T.E., Armstrong, S., Maganti, M., Hancock II bioprosthesis for aortic valve replacement: The gold standard of bioprosthetic valves durability? (2010) Ann Thorac Surg., 90 (3), pp. 775-781Clark, J.N., Ogle, M.F., Ashworth, P., Bianco, R.W., Levy, R.J., Prevention of calcification of bioprosthetic heart valve cusp and aortic wall with ethanol and aluminum chloride (2005) Ann Thorac Surg., 79 (3), pp. 897-904Ruel, M., Kulik, A., Rubens, F.D., Bédard, P., Masters, R.G., Pipe, A.L., Late incidence and determinants of reoperation in patients with prosthetic heart valves (2004) Eur J Cardiothorac Surg., 25 (3), pp. 364-370Poirer, N.C., Pelletier, L.C., Pellerin, M., Carrier, M., 15-year experience with the Carpentier-Edwards pericardial bioprosthesis (1998) Ann Thorac Surg., 66 (6 SUPPL.), pp. S57-S61Duran, C.G., Gunning, A.J., Whitehead, R., Experimental aortic valve heterotransplantation (1967) Thorax., 22 (6), pp. 510-518Duran, C.M., Whitehead, R., Gunning, A.J., Implantation of homologous and heterologous aortic valves in prosthetic vascular tubes (1969) Thorax., 24 (2), pp. 142-147Borgognoni, C.F., Maizato, M.J., Leirner, A.A., Polakiewicz, B., Beppu, M.M., Higa, O.Z., Effect of freeze-drying on the mechanical, physical and morphological properties of glutaraldehyde-treated bovine pericardium: Evaluation of freeze-dried treated bovine pericardium properties (2010) J Appl Biomater Biomech., 8 (3), pp. 186-190Maizato, M.J., Higa, O.Z., Mathor, M.B., Camillo, M.A., Spencer, P.J., Pitombo, R.N., Glutaraldehyde-treated bovine pericardium: Effects of lyophilization on cytotoxicity and residual aldehydes (2003) Artif Organs., 27 (8), pp. 692-694Flameng, W., Meuris, B., Yperman, J., de Visscher, G., Herijgers, P., Verbeken, E., Factors influencing calcification of cardiac bioprostheses in adolescent sheep (2006) J Thorac Cardiovasc Surg., 132 (1), pp. 89-98Schoen, F.J., Levy, R.J., Calcification of tissue heart valve substitutes: Progress toward understanding and prevention (2005) Ann Thorac Surg., 79 (3), pp. 1072-1080McClure, R.S., Narayanasamy, N., Wiegerinck, E., Lipsitz, S., Maloney, A., Byrne, J.G., Late outcomes for aortic valve replacement with the Carpentier-Edwards pericardial bioprosthesis: Up to 17-year follow-up in 1,000 patients (2010) Ann Thorac Surg., 89 (5), pp. 1410-1416Jamieson, W.R., Lewis, C.T., Sakwa, M.P., Cooley, D.A., Kshettry, V.R., Jones, K.W., St Jude Medical Epic porcine bioprosthesis: Results of the regulatory evaluation (2011) J Thorac Cardiovasc Surg., 141 (6), pp. 1449e2-1454e2The Italian study on the Mitroflow postoperative results (ISTHMUS): A 20-year, multicentre evaluation of Mitroflow pericardial bioprosthesis (2011) Eur J Cardiothorac Surg., 39 (1), pp. 18-26. , ISTHMUS InvestigatorsBeauchamp Jr., R.O., St Clair, M.B., Fennell, T.R., Clarke, D.O., Morgan, K.T., Kari, F.W., A critical review of the toxicology of glutaraldehyde (1992) Crit Rev Toxicol., 22 (3-4), pp. 143-174Golomb, G., Schoen, F.J., Smith, M.S., Linden, J., Dixon, M., Levy, R.J., The role of glutaraldehyde-induced cross-links in calcification of bovine pericardium used in cardiac valve bioprostheses (1987) Am J Pathol., 127 (1), pp. 122-130Guldner, N.W., Jasmund, I., Zimmermann, H., Heinlein, M., Girndt, B., Meier, V., Detoxification and endothelialization of glutaraldehyde-fixed bovine pericardium with titanium coating: A new technology for cardiovascular tissue engineering (2009) Circulation., 119 (12), pp. 1653-1660Clark, J.N., Ogle, M.F., Ashworth, P., Bianco, R.W., Levy, R.J., Prevention of calcification of bioprosthetic heart valve cusp and aortic wall with ethanol and aluminum chloride (2005) Ann Thorac Surg., 79 (3), pp. 897-904Hahn, S.K., Ohri, R., Giachelli, C.M., Anti-calcification of bovine pericardium for bioprosthetic heart valves after surface modi-fication with hyaluronic acid derivatives (2005) Biotechnol Bioprocess Eng., 10, pp. 218-224Zilla, P., Fullard, L., Trescony, P., Meinhart, J., Bezuidenhout, D., Gorlitzer, M., Glutaraldehyde detoxification of aortic wall tissue: A promising perspective for emerging bioprosthetic valve concepts (1997) J Heart Valve Dis., 6 (5), pp. 510-520Weissenstein, C., Human, P., Bezuidenhout, D., Zilla, P., Glutaraldehyde detoxification in addition to enhanced amine cross-linking dramatically reduces bioprosthetic tissue calcification in the rat model (2000) J Heart Valve Dis., 9 (2), pp. 230-240Santibáñez-Salgado, J.A., Olmos-Zúñiga, J.R., Pérez-López, M., Aboitiz-Rivera, C., Gaxiola-Gaxiola, M., Jasso-Victoria, R., Lyophilized glutaraldehyde-preserved bovine pericardium for experimental atrial septal defect closure (2010) Eur Cell Mater., 19, pp. 158-165Zilla, P., Brink, J., Human, P., Bezuidenhout, D., Prosthetic heart valvae: Catering for the few (2008) Biomaterials., 29 (4), pp. 385-40

Oxidative stress in the latissimus dorsi muscle of diabetic rats

The purpose of the present study was to investigate the effects of experimental diabetes on the oxidant and antioxidant status of latissimus dorsi (LD) muscles of male Wistar rats (220 ± 5 g, N = 11). Short-term (5 days) diabetes was induced by a single injection of streptozotocin (STZ, 50 mg/kg, iv; glycemia >300 mg/dl). LD muscle of STZ-diabetic rats presented higher levels of thiobarbituric acid reactive substances (TBARS) and chemiluminescence (0.36 ± 0.02 nmol/mg protein and 14706 ± 1581 cps/mg protein) than LD muscle of normal rats (0.23 ± 0.04 nmol/mg protein and 7389 ± 1355 cps/mg protein). Diabetes induced a 92% increase in catalase and a 27% increase in glutathione S-transferase activities in LD muscle. Glutathione peroxidase activity was reduced (58%) in STZ-diabetic rats and superoxide dismutase activity was similar in LD muscle of both groups. A positive correlation was obtained between catalase activity and the oxidative stress of LD, as evaluated in terms of TBARS (r = 0.78) and by chemiluminescence (r = 0.89). Catalase activity also correlated inversely with glutathione peroxidase activity (r = 0.79). These data suggest that an increased oxidative stress in LD muscle of diabetic rats may be related to skeletal muscle myopathy