Fernando Augusto Lavezzo Dias

Desensitization of Myofilaments to Ca2+ as a Therapeutic Target for Hypertrophic Cardiomyopathy with Mutations in Thin Filament Proteins

Background—Hypertrophic cardiomyopathy (HCM) is a common genetic disorder caused mainly by mutations in sarcomeric proteins and is characterized by maladaptive myocardial hypertrophy, diastolic heart failure, increased myofilament Ca2+ sensitivity, and high susceptibility to sudden death. We tested the following hypothesis: correction of the increased myofilament sensitivity can delay or prevent the development of the HCM phenotype. Methods and Results—We used an HCM mouse model with an E180G mutation in &agr;-tropomyosin (Tm180) that demonstrates increased myofilament Ca2+ sensitivity, severe hypertrophy, and diastolic dysfunction. To test our hypothesis, we reduced myofilament Ca2+ sensitivity in Tm180 mice by generating a double transgenic mouse line. We crossed Tm180 mice with mice expressing a pseudophosphorylated cardiac troponin I (S23D and S24D; TnI-PP). TnI-PP mice demonstrated a reduced myofilament Ca2+ sensitivity compared with wild-type mice. The development of pathological hypertrophy did not occur in mice expressing both Tm180 and TnI-PP. Left ventricle performance was improved in double transgenic compared with their Tm180 littermates, which express wild-type cardiac troponin I. Hearts of double transgenic mice demonstrated no changes in expression of phospholamban and sarcoplasmic reticulum Ca2+ ATPase, increased levels of phospholamban and troponin T phosphorylation, and reduced phosphorylation of TnI compared with Tm180 mice. Moreover, expression of TnI-PP in Tm180 hearts inhibited modifications in the activity of extracellular signal-regulated kinase and zinc finger-containing transcription factor GATA in Tm180 hearts. Conclusions—Our data strongly indicate that reduction of myofilament sensitivity to Ca2+ and associated correction of abnormal relaxation can delay or prevent development of HCM and should be considered as a therapeutic target for HCM.

Identification of peripheral arterial disease in diabetic patients and its association with quality of life, physical activity and body composition

BACKGROUND: Diabetes mellitus (DM) is a risk factor for peripheral arterial disease (PAD). Neither the prevalence of PAD in type 2 (T2) DM nor its detrimental effects on quality of life (QoL) or physical activity (PA) have been well described in the Brazilian population. OBJECTIVES: To evaluate the prevalence of newly diagnosed PAD and its associations with QoL, PA and body composition in a sample of T2DM patients from a University Hospital. METHODS: Seventy-three (73) T2DM patients without previous diagnoses of major complications related to T2DM were enrolled. PAD was assessed using the ankle-brachial index (ABI); QoL was measured using a translated and validated SF-36 questionnaire; PA was measured using a modified Baecke questionnaire; and body composition was measured by segmental multi-frequency bioelectrical impedance. RESULTS: PAD prevalence was 13.7%, predominantly of mild severity (ABI between 0.8-0.9). The ABI results correlated with age (ρ=-0.26, P=0.03), DM duration (ρ=-0.28, P=0.02) and systolic and diastolic blood pressure (ρ=-0.33, P=0.007 and ρ=-0.28, P=0.02; respectively). Scores for the SF-36 physical component summary (PCS) were below the normal range, but no negative impact from PAD was identified by the PCS scores (normal-ABI 42.9±11.2 vs. PAD-ABI 38.12±11.07) or the Baecke PA results. Body composition analysis detected excessive body fat, especially in women, but there was no difference between groups. CONCLUSIONS: The prevalence of previously undiagnosed PAD in this population of T2DM patients was 13.7%, predominantly mild and asymptomatic forms, and was not yet associated with worsened QoL, PA levels or body composition variables.

Educational interventions for improving control of blood pressure in patients with hypertension: a systematic review protocol

Introduction The aim of this review is to evaluate the effectiveness of educational interventions on improving the control of blood pressure in patients with hypertension. Methods Randomised controlled trials including patients over 18 years of age, regardless of sex and ethnicity, with a diagnosis of hypertension (either treated or not treated with antihypertensive medications) will be assessed in our analysis. We will electronically search four databases: MEDLINE, CINAHL, PEDro and ScienceDirect. There will be no language restrictions in the search for studies. The data will be extracted independently by two authors using predefined criteria. Disagreements will be resolved between the authors. The risk of bias will be assessed using the Cochrane risk of bias tool. After searching and screening of the studies, we will run a meta-analysis of the included randomised controlled trials. We will summarise the results as risk ratio for dichotomous data and mean differences for continuous data. Ethics and dissemination The review will be published in a journal. The findings from the review will also be disseminated electronically and at conference presentations. Trial registration number PROSPERO CRD4201401071.

Noninvasive assessment of respiratory muscle strength and activity in Myotonic dystrophy

Objective To evaluate sensitivity/specificity of the maximum relaxation rate (MRR) of inspiratory muscles, amplitude of electromyographic activity of the sternocleidomastoid (SCM), scalene (SCA), parasternal (2ndIS) and rectus abdominis (RA) muscles; lung function and respiratory muscle strength in subjects with Myotonic dystrophy type 1 (DM1) compared with healthy subjects. Design and methods Quasi-experimental observational study with control group. MRR of inspiratory muscles, lung function and amplitude of the electromyographic activity of SCM, SCA, 2ndIS and RA muscles during maximum inspiratory pressure (PImax), maximum expiratory pressure (PEmax) and sniff nasal inspiratory pressure (SNIP) tests were assessed in eighteen DM1 subjects and eleven healthy. Results MRR was lower in DM1 group compared to healthy (P = 0.001) and was considered sensitive and specific to identify disease in DM1 and discard it in controls, as well as SNIP% (P = 0.0026), PImax% (P = 0.0077) and PEmax% (P = 0.0002). Contraction time of SCM and SCA was higher in DM1 compared to controls, respectively, during PImax (P = 0.023 and P = 0.017) and SNIP (P = 0.015 and P = .0004). The DM1 group showed lower PImax (P = .0006), PEmax (P = 0.0002), SNIP (P = 0.0014), and higher electromyographic activity of the SCM (P = 0.002) and SCA (P = 0.004) at rest; of 2ndIS (P = 0.003) during PEmax and of SCM (P = 0.02) and SCA (P = 0.03) during SNIP test. Conclusions MD1 subjects presented restrictive pattern, reduced respiratory muscle strength, muscular electrical activity and MRR when compared to higher compared to controls. In addition, the lower MRR found in MD1 subjects showed to be reliable to sensitivity and specificity in identifying the delayed relaxation of respiratory muscles.

Association between anthropometric indicators of adiposity and hypertension in a Brazilian population: Baependi Heart Study.

Background Recently, some studies have evaluated the role of adiposity measures in the prediction of hypertension risk, but the results are conflicting. Thus, the aim of this study was to compare which of the four indicators of adiposity (waist circumference–WC, body mass index–BMI, body adiposity index–BAI, and visceral adiposity index–VAI) were better associated with hypertension in a Brazilian population. Methods and findings For this study, were selected 1627 individuals (both genders, and aged over 18 years) resident in the municipality of Baependi, a city located in the Southeast of Brazil. WC, BMI, BAI and VAI were determined according to a standard protocol. Hypertension was defined as mean systolic blood pressure ≥ 140 mmHg and/or diastolic blood pressure ≥ 90 mmHg, and/or antihypertensive drug use. The indicators of adiposity WC, BMI, BAI, and VAI were higher in hypertensive when compared to non-hypertensive individuals. In addition, WC and BMI were most strongly associated with hypertension in men and women, respectively. The area under the curve (AUC) of WC was significantly higher than VAI in men. In women, both AUC of BMI and WC showed higher discriminatory power to predict hypertension than BAI and VAI. Conclusions The indicators of adiposity WC and BMI were better associated with hypertension than BAI and VAI, in both genders, and it could be a useful tools for the screening of hypertensive patients.

Effects of diaphragmatic control on the assessment of sniff nasal inspiratory pressure and maximum relaxation rate

OBJECTIVE: To assess the influence of diaphragmatic activation control (diaphC) on Sniff Nasal-Inspiratory Pressure (SNIP) and Maximum Relaxation Rate of inspiratory muscles (MRR) in healthy subjects. METHOD: Twenty subjects (9 male; age: 23 (SD=2.9) years; BMI: 23.8 (SD=3) kg/m2; FEV1/FVC: 0.9 (SD=0.1)] performed 5 sniff maneuvers in two different moments: with or without instruction on diaphC. Before the first maneuver, a brief explanation was given to the subjects on how to perform the sniff test. For sniff test with diaphC, subjects were instructed to perform intense diaphragm activation. The best SNIP and MRR values were used for analysis. MRR was calculated as the ratio of first derivative of pressure over time (dP/dtmax) and were normalized by dividing it by peak pressure (SNIP) from the same maneuver. RESULTS: SNIP values were significantly different in maneuvers with and without diaphC [without diaphC: -100 (SD=27.1) cmH2O/ with diaphC: -72.8 (SD=22.3) cmH2O; p<0.0001], normalized MRR values were not statistically different [without diaphC: -9.7 (SD=2.6); with diaphC: -8.9 (SD=1.5); p=0.19]. Without diaphC, 40% of the sample did not reach the appropriate sniff criteria found in the literature. CONCLUSION: Diaphragmatic control performed during SNIP test influences obtained inspiratory pressure, being lower when diaphC is performed. However, there was no influence on normalized MRR.

Prevalence of Peripheral Artery Disease and Associated Risk Factors in a Brazilian Rural Population: The Baependi Heart Study

Mailing Address: Rafael de Oliveira Alvim Rua Alaor de Queiroz Araújo, 135. Postal Code: 29050-245, Enseada do Suá, Vitória (ES) Brazil. E-mail: r.alvim@hotmail.com Prevalence of Peripheral Artery Disease and Associated Risk Factors in a Brazilian Rural Population: The Baependi Heart Study Rafael de Oliveira Alvim,1 Fernando Augusto Lavezzo Dias,2 Camila Maciel de Oliveira,2 Andréa Roseli Vançan Russo Horimoto,3 Anderson Zampier Ulbrich,2 José Eduardo Krieger,3 Alexandre da Costa Pereira3 Universidade Federal do Espírito Santo (UFES),1 Vitória, ES Brazil Universidade Federal do Paraná (UFPR),2 Curitiba, PR Brazil Instituto do Coração (InCor) Faculdade de Medicina da Universidade de São Paulo,3 São Paulo, SP Brazil

Reference values for the bilateral heel-rise test

Highlights • Bilateral HRT reference values were established, stratified by age and gender.• Bilateral HRT reference values may be used as a basis for research and clinical practice.

Exercise training ameliorates matrix metalloproteinases 2 and 9 messenger RNA expression and mitigates adverse left ventricular remodeling in streptozotocin-induced diabetic rats☆

BACKGROUND The aim was to investigate whether exercise training (ExT) would ameliorate expression of key genes for myocardial morphostructure and mitigate adverse left ventricular (LV) remodeling in experimental type 1 diabetes (T1D). METHODS AND RESULTS Male Wistar rats were divided into four groups: sedentary control (SC, n=9), trained control (TC, n=13), sedentary diabetic (SD, n=20), and trained diabetic (TD, n=17). T1D was induced by 40 mg/kg streptozotocin (single dose, i.v.). Training program consisted of 4-week treadmill running (60 min/day, 5 days/wk). Structure of the LV was evaluated using histomorphometric techniques. Gene expression changes of LV collagens I and III, metalloproteinases (MMPs) 2 and 9, and transforming growth factor-β1 were detected by reverse transcriptase quantitative polymerase chain reaction. Compared with SC, SD rats presented LV eccentric remodeling, myocyte hypertrophy, and fibrosis, whereas TD animals showed normal LV geometry and collagen content but thinner myocytes. Expression of collagens and type I/III collagen messenger RNA (mRNA) ratio were diminished in diabetic hearts compared with SC. MMP-2 gene was down-regulated in SD, whereas TD group showed decreased MMP-9 mRNA levels and MMP-2 expression comparable to that of SC rats. CONCLUSIONS Attenuation of MMP-2 down-regulation and reduction in MMP-9 mRNA expression may constitute an underlying mechanism by which ExT counteracts progression of adverse LV remodeling in T1D.