The functional morphology of the metapleural gland of the leaf-cutting ant Atta laevigata (Formicidae: Attini)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

FUNCTIONAL AND ULTRASTRUCTURAL EVALUATION OF MYOCARDIAL PROTECTION PROVIDED BY INTERMITTENT CORONARY SINUS PERFUSION IN THE ISOLATED DOG HEART

1. The protection offered by intermittent perfusion of of cardioplegic solution through the coronary sinus was investigated in isovolumic blood-perfused dog heart preparations submitted to 60 min of ischemia and 45 min of reperfusion.2. The preparations were divided into three treatment groups: a) coronary sinus, consisting of preparations (N = 10) perfused through the coronary sinus under 40 cm water pressure; b) aortic, consisting of preparations (N = 10) perfused through the aortic stump under 100 mmHg pressure; c) control, consisting of hearts (N = 9) that were not perfused with cardioplegic solution.3. Properties of contractile capacity and relaxation were markedly impaired in the control group but were preserved to a comparable extent in the groups perfused with cardioplegic solution through the aorta and coronary sinus. Developed pressure decreased in the control group (before ischemia: 70 +/- 5.5 mmHg; after reperfusion: 35 +/- 12 mmHg; P < 0.05) and didn't vary in the aortic group (from 69 +/- 4 mmHg to 65 +/- 13 mmHg; P > 0.05) and coronary sinus group (from 69 +/- 4.6 mmHg to 60 +/- 10 mmHg; P > 0.05). Myocardial relaxation was evaluated by the +/- dp/dt ratio. In the control group there was impairment of myocardial relaxation as indicated by an increase of this index after reperfusion (from 1.05 +/- 0.05 to 1.46 +/- 0.23; P < 0.05), whereas in the aortic (from 1.10 +/- 0.13 to 1.15 +/- 0.20; P > 0.05) and the coronary sinus (from 1.03 +/- 0.14 to 1.08 +/- 0.16; P > 0.05) groups there was no variation. Ultrastructural changes in the myocardium were negligible in all three groups at the end of reperfusion.4. We conclude that intermittent perfusion of a hypothermic cardioplegic solution through the coronary sinus is effective for the protection of the myocardium during total ischemia.

FUNCTIONAL ALPHA-TROPOMYOSIN PRODUCED IN ESCHERICHIA-COLI - A DIPEPTIDE EXTENSION CAN SUBSTITUTE THE AMINO-TERMINAL ACETYL GROUP

Unlike the muscle protein, alpha-tropomyosin expressed in Escherichia coli does not bind actin, does not exhibit head-to-tail polymerization, and does not inhibit actomyosin ATPase activity in the absence of troponin. The only chemical difference between recombinant and muscle tropomyosins is that the first methionine is not acetylated in the recombinant protein (Hitchcock-DeGregori, S. E., and Heald, R. W. (1987) J. Biol. Chem. 262, 9730-9735). We expressed three fusion tropomyosins in E. coli with 2, 3, and 17 amino acids fused to its amino terminus. Ah three fusions restored actin binding, head-to-tail polymerization, and the capacity to inhibit the actomyosin ATPase to these unacetylated tropomyosins. Unlike larger fusions, the small fusions of 2 and 3 amino acids do not interfere with regulatory function. Therefore the presence of a fused dipeptide at the amino terminus of unacetylated tropomyosin is sufficient to replace the function of the N-acetyl group present in muscle tropomyosin. A structural interpretation for the function of the acetyl group, based on our results and the coiled coil structure of tropomyosin, is presented.

Alterations in pulmonary structure by elastase administration in a model of emphysema in mice is associated with functional disturbances

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Fatigue and rapid hamstring/quadriceps force capacity in professional soccer players

The aim of this study was to investigate the effect of fatigue induced by an exhaustive laboratory-based soccer-specific exercise on different hamstrings/quadriceps (H:Q) ratios of soccer players. Twenty-two male professional soccer players (23·1 ± 3·4 year) performed maximal eccentric (ecc) and concentric (con) contractions for knee extensors (KE) and flexors (KF) at 60° s-1 and 180° s-1 to assess conventional (Hcon:Qcon) and functional (Hecc:Qcon) ratios. Additionally, they performed maximal voluntary isometric contraction for KE and KF, from which the maximal muscle strength, rate of force development (RFD) and RFD H:Q strength ratio (RFDH:Q) were extracted. Thereafter, subjects were performed an exhaustive laboratory-based soccer-specific exercise and a posttest similar to the pretest. There was significant reduction in Hcon:Qcon (0·60 ± 0·06 versus 0·58 ± 0·06, P<0·05) and in Hecc:Qcon (1·29 ± 0·2 versus 1·16 ± 0·2, P<0·01) after the soccer-specific exercise. However, no significant difference between Pre and Post exercise conditions was found for RFDH:Q at 0-50 (0·53 ± 0·23 versus 0·57 ± 0·24, P>0·05) and 0-100 ms (0·53 ± 0·17 versus 0·55 ± 0·17, P>0·05). In conclusion, H:Q strength ratios based on peak force values are more affected by fatigue than RFDH:Q obtained during early contraction phase. Thus, fatigue induced by soccer-specific intermittent protocol seems not reduce the potential for knee joint stabilization during the initial phase of voluntary muscle contraction. copy; 2012 Scandinavian Society of Clinical Physiology and Nuclear Medicine.

Diastolic function is associated with quality of life and exercise capacity in stable heart failure patients with reduced ejection fraction

Exercise capacity and quality of life (QOL) are important outcome predictors in patients with systolic heart failure (HF), independent of left ventricular (LV) ejection fraction (LVEF). LV diastolic function has been shown to be a better predictor of aerobic exercise capacity in patients with systolic dysfunction and a New York Heart Association (NYHA) classification >II. We hypothesized that the currently used index of diastolic function E/e' is associated with exercise capacity and QOL, even in optimally treated HF patients with reduced LVEF. This prospective study included 44 consecutive patients aged 55±11 years (27 men and 17 women), with LVEF,0.50 and NYHA functional class I-III, receiving optimal pharmacological treatment and in a stable clinical condition, as shown by the absence of dyspnea exacerbation for at least 3 months. All patients had conventional transthoracic echocardiography and answered the Minnesota Living with HF Questionnaire, followed by the 6-min walk test (6MWT). In a multivariable model with 6MWT as the dependent variable, age and E/e' explained 27% of the walked distance in 6MWT (P=0.002; multivariate regression analysis). No association was found between walk distance and LVEF or mitral annulus systolic velocity. Only normalized left atrium volume, a sensitive index of diastolic function, was associated with decreased QOL. Despite the small number of patients included, this study offers evidence that diastolic function is associated with physical capacity and QOL and should be considered along with ejection fraction in patients with compensated systolic HF.

Oxidation of Bovine Albumin by Hypochlorous and Hypobromous Acids: Structural and Functional Alterations

Aims: Hypochlorous (HOCl) and hypobromous (HOBr) acids are among the most powerful oxidants produced by the innate immune cells. Albumin is the predominant protein in most body fluids and is considered the most important antioxidant of blood plasma. Study Design: Oxidation of bovine albumin (BSA) and study of its structural and functional alterations. Place and Duration of Study: Faculty of Science and Faculty of Pharmaceutical Science, University of the State of Sao Paulo UNESP, between June and December 2012. Methodology: BSA was oxidized with excess of HOCl or HOBr and its structural and functional alterations were analyzed by spectroscopic techniques as UV-Vis absorption, intrinsic and synchronous fluorescence, fluorescence quenching, Rayleigh scattering and circular dichroism. Results: Both oxidants were able to deplete the intrinsic fluorescence of BSA, but HOBr was more effective than HOCl. The alterations in the synchronous fluorescence, UV-Vis absorption, and the appearance of a fluorescence band centered at 450 nm confirmed the difference between the oxidants. The oxidation did not induce aggregation of BSA as measured by Rayleigh scattering. The far-UV circular dichroism spectra showed a loss in the helical content and the near-UV-circular dichroism showed an alteration in the tertiary structure; HOBr was the more effective of the oxidants in this case. However, the oxidations did not induce significant alterations in the binding capacity of BSA, which was evaluated using hydrophobic (norfloxacin) and hydrophilic (ascorbic acid) drugs. Conclusion: These results suggest that, although highly susceptible to oxidation, the alterations did not inhibit BSA’s physiological function as a transport protein.