A computational analysis of substrate binding strength by phosphorylase kinase and protein kinase A

Protein kinases exhibit various degrees of substrate specificity. The large number of different protein kinases in the eukaryotic proteomes makes it impractical to determine the specificity of each enzyme experimentally. To test if it were possible to discriminate potential substrates from non-substrates by simple computational techniques, we analysed the binding enthalpies of modelled enzyme-substrate complexes and attempted to correlate it with experimental enzyme kinetics measurements. The crystal structures of phosphorylase kinase and cAMP-dependent protein kinase were used to generate models of the enzyme with a series of known peptide substrates and non-substrates, and the approximate enthalpy of binding assessed following energy minimization. We show that the computed enthalpies do not correlate closely with kinetic measurements, but the method can distinguish good substrates from weak substrates and non-substrates. Copyright (C) 2002 John Wiley Sons, Ltd.

Relationship of interleukin-6 and tumor necrosis factor-alpha with muscle mass and muscle strength in elderly men and women: The health ABC study

Background. A decline in muscle mass and muscle strength characterizes normal aging. As clinical and animal studies show it relationship between higher cytokine levels and low muscle mass, the aim of this study was to investigate whether markers, of inflammation are associated with muscle mass and strength in well-functioning elderly persons. Methods. We Used baseline data (1997-1998) of the Health, Aging, and Body Composition (Health ABC) Study on 3075 black and white men and women aged 70-79 years. Midthigh muscle cross-sectional area (computed tomography), appendicular muscle mass (dual-energy x-ray ab absorptiometry). isokinetic knee extensor strength (KinCom). and isometric inip strength were measured. plasma levels of interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-alpha) were assessed by enzyme-linked immunosorbent assay (ELISA). Results. Higher cytokine levels were generally associated with lower muscle mass and lower muscle strength. The most consistent relationship across the gender and race groups was observed for IL-6 and grip strength: per SD increase in IL-6, grip strength was 1.1 to 2.4 kg lower (p < .05) after adjustment for age, clinic Site. health status, medications, physical activity. smoking. height. and body fat. Ail overall measure of elevated cytokine level was created by combining the levels of IL-6 and TNF-alpha. With the exception of white men, elderly persons having high levels of IL-6 (> 1.80 pg/ml) as well as high levels of TNF-alpha (> 3.20 pg/ml) had a smaller muscle area, less appendicular mass. a lower knee extensor strength. and a lower grip strength compared to those with low levels of both cytokines. Conclusions. Higher plasma concentrations of IL-6 and TNF-alpha are associated with lower muscle mass and lower muscle strength in well-functioning older men and women. Higher cytokine levels. as often observed in healthy older persons. may contribute to the loss Of muscle mass and strength that accompanies aging.

ERP 'old/new' effects: memory strength and decisional factor(s)

Event-related potentials (ERPs) were recorded while subjects made old/new recognition judgments on new unstudied words and old words which had been presented at study either once ('weak') or three times ('strong'). The probability of an 'old' response was significantly higher for strong than weak words and significantly higher for weak than new words. Comparisons were made initially between ERPs to new, weak and strong words, and subsequently between ERPs associated with six strength-by-response conditions. The N400 component was found to be modulated by memory trace strength in a graded manner. Its amplitude was most negative in new word ERPs and most positive in strong word ERPs. This 'N400 strength effect' was largest at the left parietal electrode (in ear-referenced ERPs). The amplitude of the late positive complex (LPC) effect was sensitive to decision accuracy (and perhaps confidence). Its amplitude was larger in ERPs evoked by words attracting correct versus incorrect recognition decisions. The LPC effect had a left > right, centro-parietal scalp topography (in ear-referenced ERPs). Hence, whereas, the majority of previous ERP studies of episodic recognition have interpreted results from the perspective of dual-process models, we provide alternative interpretations of N400 and LPC old/new effects in terms of memory strength and decisional factor(s). (C) 2002 Elsevier Science Ltd. All rights reserved.

Examining the influence of biological and psychological factors on cognitive performance in chronic fatigue syndrome: A randomized, double-blind, placebo-controlled, crossover study

The pathophysiology of chronic fatigue syndrome (CFS) remains unclear; however, both biological and psychological factors have been implicated in establishing or maintaining this condition. People with CFS report significant and disabling cognitive difficulties such as impaired concentration that in some cases are exacerbated by exposure to chemical triggers. The aim of this study was to determine if neuropsychological deficits in CFS are triggered by exposure to chemicals, or perceptions about the properties of these substances. Participants were 36 people with a primary diagnosis of CFS, defined according to Centers for Disease Control (CDC) criteria. A randomized, double-blind, placebo-controlled, crossover design was used, with objective assessment of neuropsychological function and participant rating of substance type, before and after exposure to placebo or chemical trigger. Results showed decrements in neuropsychological tests scores on three out of four outcome measures when participants rated the substance they had been exposed to as chemical. No change in performance was found based on actual substance type. These results suggest that cognitive attributions about exposure substances in people with CFS may be associated with worse performance on neuropsychological tasks. In addition, these findings suggest that psychological interventions aimed at modifying substance-related cognitions may reduce some symptoms of CFS.

Bond strength of an adhesive system irradiated with Nd : YAG laser in dentin treated with Er : YAG laser

The purpose of this in vitro study was to verify through micro tensile bond test the bond strength of an adhesive system irradiated with Nd:YAG laser in dentine previously treated with Er:YAG laser. Twenty caries free extracted human third molars were used. The teeth were divided in four experimental groups (n = 5): (G1) control group; (G2) irradiation of the adhesive system with the Nd:YAG laser; (G3) dentin treatment with Er:YAG laser; (G4) dentin treatment with Er:YAG laser followed by the irradiation of the adhesive system with Nd:YAG laser. The Er:YAG laser fluency parameter for the dentin treatment was of 60 J/cm(2). ne adhesive system was irradiated with the Nd:YAG laser with fluency of 100 J/cm(2). Dental restorations were performed with Adper Single Bond 2/Z250. One tooth from each group was prepared for the evaluation of the adhesive interface under SEM and bond failure tests were also performed and evaluated. The statistical analysis showed statistical significant difference between the groups G1 and G3, G1 and G4, G2 and G3, and G2 and G4; and similarity between the groups G1 and G2, and G3 and G4. The adhesive failures were predominant in all the experimental groups. The SEM analysis showed an adhesive interface with features confirming the results of the mechanical tests. The Nd:YAG laser on the adhesive system did not influence the bond strength in dentin treated or not with the Er:YAG laser.

Adsorption of cholate anions on layered double hydroxides: effects of temperature, ionic strength and pH

Layered Double Hydroxides are a class of materials that can be described as positively charged planar layers consisting of divalent and trivalent cations in the center of edge-sharing octahedra. The positive charge in the LDH layers must be compensated by anion intercalation. These materials have applications that include adsorption and/or sorption of anionic species. Cholic acid is one of the main acids produced by the liver. It promotes transport of lipids through aqueous systems. This work reports on the adsorption of Cholic acid anions in MgAl-CO3-LDH taking ionic strength, pH, and temperature effects into account. The adsorbent was characterized by different techniques. Cholate anion adsorption was performed at two different temperatures (298 and 323 K), two different ionic strength conditions (0.0 and 0.1 M of NaCl), and two different pH values (7.0 and 10.0). The results show that the sorption of Cholate anions in calcined LDH can remove a considerable amount of these anions from the medium. Cholate anion adsorption in the LDH with no calcining also occurs, but at a lower amount.

Adsorption of phenylalanine on layered double hydroxides: effect of temperature and ionic strength

In this work we report the adsorption of phenylalanine (Phe) on Magnesium Aluminum Layered Double Hydroxides (Mg-Al-CO(3)-LDH) at two different temperatures (298 and 310 K) and under two distinct ionic strength conditions (with and without the addition 0.1 M of NaCl). The adsorption isotherms exhibit the same profile in all conditions, and they only differ in the amount of removed Phe. At lower ionic strength, the isotherms are almost identical at both temperatures, except for the last points, where the increase in temperature causes a decrease in the amount of adsorbed Phe. An increase in ionic strength results in a decrease in Phe adsorption. The electrokinetic potential decreases as the amount of adsorbed Phe increases, and only positive values are observed. This indicates that the surface of the adsorbent is not totally neutralized and suggests that more Phe could be removed by adsorption. The presence of Phe on the solid is confirmed by FTIR spectra, which present the specific bands assigned to Phe. The hydrophobicity of the amino acid probably contributes to its extraction, thus enabling the removal of a great amount of Phe. In conclusion, LDH is potentially applicable in the removal of Phe from wastewater.

The Strength of Weak Parties

The Strength of Weak Parties The aim of this article is to fill some gaps in research on the Brazilian electoral arena. The current literature, by neglecting the study of party organization, ends up overlooking fundamental questions for understanding how the electoral process works. This study addressed two questions: How do Brazilian parties work? What is the impact of party organization on a party`s decision to launch or withhold a candidate in a given election? We intend to show that the parties have more life than many studies on our political system tend to show. This partisan life helps understand one of the central aspects of the electoral arena, that is, how pre-election coordination occurs.

Adenotonsillectomy improves the strength of respiratory muscles in children with upper airway obstruction

Objective: The aim of this paper is to study the respiratory muscle strength by evaluating the maximal inspiratory pressure (MIP), maximal expiratory pressure (MEP) and lung volume before and 3 and 6 months after adenotonsillectomy. This is an interventional, before and after trial. It was set at the Department of Otolaryngology. University of Sao Paulo, School of Medicine. We included 29 children (6-13 years old), both genders, consecutively recruited from the waiting list for adenotonsillectomy. Children were submitted to maximal inspiratory pressures (MIP), maximal expiratory pressure (MEP) evaluation using an analog manovacuometer, lung volume, using incentive expirotometer and thoracic and abdominal perimeter using a centimeter tape. Children were evaluated in 3 different moments: 1 week before and 3 and 6 months after surgery. Results: MIP improved significantly 3 months (p < 0.001) after adenotonsillectomy and MEP did not change (p = 1). There were increases in lung volume (p = 000), chest (p = 0.017) and abdominal perimeter (p = 0.05). Six months after surgery, all parameters improved. MIP (p = 0), MEP (p = 0), lung volume (p = 0.02), chest (p = 0.034) and abdominal perimeter (p = 0.23). Conclusion: This study suggests that there was an improvement in respiratory muscular strength, once there was a significant improvement in maximal inspiratory pressure, lung volume and other parameters after adenotonsillectomy. (C) 2010 Elsevier Ireland Ltd. All rights reserved.

Analysis of the Strength of the Abdominal Fascia in Different Sutures Used in Abdominoplasties

Protrusion of the abdominal wall secondary to abdominoplasty may occur in patients with weakness of the aponeurotic structures. The anterior layer of the rectus abdominis muscle consists of fibers that are transverse rather than vertical. Based on this anatomical feature, vertical sutures are suggested for the correction of diastasis recti, since they include a greater amount of fascial fibers and thus would be more resistant to tensile strength than horizontal ones. The anterior layers of the rectus abdominis muscles of 15 fresh cadavers were dissected. Two vertical lines were marked on each side of the linea alba, corresponding to the site where plication is usually performed in abdominoplasties. Three abdominal levels were evaluated: the supraumbilical, umbilical, and infraumbilical levels. A simple suture was placed in the vertical direction in one group and in the horizontal direction in the other group, at each of the three levels previously described. These sutures were connected to a dynamometer, which was pulled medially toward the linea alba until rupture of the aponeurosis occurred. The mean strength required to rupture the aponeurotic structures in which the vertical sutures had been placed was greater than for the horizontal ones (p < 0.0001). The vertical suture of the rectus abdominis sheaths was stronger than the horizontal suture because of the more transversal arrangement of its aponeurotic fibers. Thus, routine use of the vertical suture in plications of the aponeurosis of the rectus abdominis muscles is suggested.

The relationship between plasma potassium concentration and muscle torque during recovery following intense exercise

The present study investigated the relationship between plasma potassium ion concentration ([K+]) and skeletal muscle torque during three different 15-min recovery periods after fatigue induced by four 30-s sprints. Four males and one female completed the multiple sprint exercise on three separate days; recovery was passive, i.e. no cycling exercise (PRec), active cycling at 30% peak oxygen consumption (V) over dot(2peak) (30% Rec) and active cycling at 60% (V) over dot(2peak) (60% Rec). Plasma [K+] was measured from blood sampled from an antecubital vein of subjects at rest and at 0, 3, 5, 10 and 15 min into each recovery. Isokinetic leg strength was measured at rest and at 1, 6, 11 and 16 min during each recovery. Following the exhaustive sprints; [K+] increased significantly from an average mean (SEM) resting value of 3.81 (0.07) mmol.l(-1) to 4.48 (0.19) mmol.l(-1) (P < 0.01). In all recovery conditions, plasma [K+] returned to resting levels within 3 min following the fourth sprint. However, in the two active recovery conditions plasma [K+] increased over the remainder of the recovery periods to 4.36 (0.12) mmol.l(-1) in the 30% Rec condition and 4.62 (0.12) mmol.l(-1) in the 60% Rec condition, the latter being significantly higher than the former (P < 0.01). The maximum torque measured following the sprints decreased significantly, on average, to 61.1 (8.36)% of peak levels (P < 0.01). After 15 min of recovery, maximum torque was highest in the 30% Rec condition at 92.13 (3.06)% of peak levels (P < 0.01), compared to 85.23 (3.64)% and 85.71 (0.82)% for the PRec and 60% Rec conditions, respectively. In contrast to the significant differences in plasma [K+] across all three recovery conditions, muscle torque recovery was significantly different in only the 30% Rec condition. In summary, recovery of peak levels of muscle torque following fatiguing exercise does not appear to follow changes in plasma [K+].

Hemodynamic response in one session of strength exercise with and without electrostimulation in heart failure patients: A randomized controlled trial

Background: Studies have investigated the influence of neuromuscular electrostimulation on the exercise/muscle capacity of patients with heart failure (HF), but the hemodynamic overload has never been investigated. The aim of our study was to evaluate the heart rate (HR), systolic and diastolic blood pressures in one session of strength exercises with and without neuromuscular electrostimulation (quadriceps) in HF patients and in healthy subjects. Methods: Ten (50% male) HF patients and healthy subjects performed three sets of eight repetitions with and without neuromuscular electrostimulation randomly, with one week between sessions. Throughout, electromyography was performed to guarantee the electrostimulation was effective. The hemodynamic variables were measured at rest, again immediately after the end of each set of exercises, and during the recovery period. Results: Systolic and diastolic blood pressures did not change during each set of exercises among either the HF patients or the controls. Without electrostimulation: among the controls, the HR corresponding to the first (85 +/- 13 bpm, p = 0.002), second (84 +/- 10 bpm, p < 0.001), third (89 +/- 17, p < 0.001) sets and recuperation (83 +/- 16 bpm, p = 0.012) were different compared to the resting HR (77 bpm). Moreover, the recuperation was different to the third set (0.018). Among HF patients, the HR corresponding to the first (84 +/- 9 bpm, p = 0.041) and third (84 +/- 10 bpm, p = 0.036) sets were different compared to the resting HR (80 +/- 7 bpm), but this increase of 4 bpm is clinically irrelevant to HF. With electrostimulation: among the controls, the HR corresponding to the third set (84 +/- 9 bpm) was different compared to the resting HR (80 +/- 7 bmp, p = 0.016). Among HF patients, there were no statistical differences between the sets. The procedure was well tolerated and no subjects reported muscle pain after 24 hours. Conclusions: One session of strength exercises with and without neuromuscular electrostimulation does not promote a hemodynamic overload in HF patients. (Cardiol J 2011; 18,1: 39-46)

Test-retest reliability of isokinetic strength and endurance tests in patients with intermittent claudication

The objective was to determine the reliability of isokinetic strength and endurance testing in the ankle joints of patients with intermittent claudication. Twenty-three patients with peripheral artery disease (PAD) and symptoms of intermittent claudication participated in the study. Isokinetic strength and endurance testing of the ankle joint were performed in symptomatic and asymptomatic legs on 3 separate days. Intraclass coefficient correlation of peak torque (PT) and total work (TW) ranged from 0.77 to 0.92 and 0.89 to 0.96, respectively. PT and TW increased significantly and similarly in both legs from day 1 to day 2 (PT: +42 +/- 84% in the symptomatic leg and +33 +/- 51% in the asymptomatic leg, p < 0.05;TW: +38 +/- 26% in the symptomatic leg and +26 +/- 50% in the asymptomatic leg, p < 0.05). In conclusion, isokinetic strength and endurance testing in the ankle joints of patients with PAD presents reliability coefficients ranging from 0.77 to 0.96. However, strength and endurance increased between the first and the other test sessions performed on separate days, suggesting that two test sessions are necessary for the accurate evaluation of strength and endurance in patients with PAD.

MENISCAL INJURY DUE TO FATIGUE

Objective: The purpose of the present study was to review a group of patients with meniscal injuries resulting from structural failure unrelated to trauma or degenerative problems to which was given the name ""meniscal injury due to fatigue"". Material and Method: Evaluations were made on 140 patients with meniscal injuries without any apparent cause, who were therefore considered to have meniscal injuries due to fatigue. Among these, 85 patients were male and 55 were female. The medial meniscus was the most affected site (92% of the cases). Results: All these injuries were diagnosed by means of clinical examination and magnetic resonance imaging. The patients underwent meniscectomy by means of arthroscopy and the results were divided into two types: good and poor. Poor results were found in 27% of the cases, among which nine patients progressed to idiopathic osteonecrosis. Conclusion: We conclude that injuries due to fatigue must be assessed as injuries caused by failure and, therefore, constituting a syndromic pathological condition that may progress to idiopathic osteonecrosis.

Comparative epidemiology of chronic fatigue syndrome in Brazilian and British primary care: prevalence and recognition

Background Although fatigue is a ubiquitous symptom across countries, clinical descriptions of chronic fatigue syndrome have arisen from a limited number of high-income countries. This might reflect differences in true prevalence or clinical recognition influenced by sociocultural factors. Aims To compare the prevalence, physician recognition and diagnosis of chronic fatigue syndrome in London and Sao Paulo. Method Primary care patients in London (n=2459) and Sao Paulo n=3914) were surveyed for the prevalence of chronic fatigue syndrome. Medical records were reviewed for the physician recognition and diagnosis. Results The prevalence of chronic fatigue syndrome according to Centers for Disease Control 1994 criteria was comparable in Britain and Brazil, 2.1% v. 1.6% (P=0.20). Medical records review identified 11 diagnosed cases of chronic fatigue syndrome in Britain, but none in Brazil (P<0.001). Conclusions The primary care prevalence of chronic fatigue syndrome was similar in two Culturally and economically distinct nations. However, doctors are unlikely to recognise and label chronic fatigue syndrome as a discrete disorder in Brazil. The recognition of this illness rather than the illness itself may be culturally induced.