Stress vulnerability during adolescence: comparison of chronic stressors in adolescent and adult rats

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

Modulação autonômica cardíaca em crianças com transtorno de linguagem

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Attività autonomica cardiaca e funzioni neurocognitive nei pazienti affetti da sindrome delle gambe senza riposo (RLS): effetto dei farmaci dopamino agonisti in acuto e a lungo termine

Several studies showed that sleep loss/fragmentation may have a negative impact on cognitive performance, mood and autonomic activity. Specific neurocognitive domains, such as executive function (i.e.,prefrontal cortex), seems to be particularly vulnerable to sleep loss. Pearson et al.(2006) evaluated 16 RLS patients compared to controls by cognitive tests, including those particularly sensitive to prefrontal cortical (PFC) functioning and sleep loss. RLS patients showed significant deficits on two of the three PFC tests. It has been recently reported that RLS is associated with psychiatric manifestations. A high prevalence of depressive symptoms has been found in patients with RLS(Rothdach AJ et al., 2000). RLS could cause depression through its adverse influences on sleep and energy. On the other hand, symptoms of depression such as sleep deprivation, poor nutrition or lack of exercise may predispose an individual to the development of RLS. Moreover, depressed patients may amplify mild RLS, making occasional RLS symptoms appear to meet threshold criteria. The specific treatment of depression could be also implicated, since antidepressant compounds may worsen RLS and PLMD(Picchietti D et al., 2005; Damsa C et al., 2004). Interestingly, treatments used to relieve RLS symptoms (dopamine agonists) seem to have an antidepressant effects in RLS depressed patients(Saletu M et al., 2002&2003). During normal sleep there is a well-regulated pattern of the autonomic function, modulated by changes in sleep stages. It has been reported that chronic sleep deprivation is associated with cardiovascular events. In patients with sleep fragmentation increased number of arousals and increased cyclic alternating pattern rate is associated with an increase in sympathetic activity. It has been demonstrated that PLMS occurrence is associated with a shift to increased sympathetic activity without significant changes in cardiac parasympathetic activity (Sforza E et al., 2005). An increased association of RLS with hypertension and heart disease has been documented in several studies(Ulfberg J et al., 2001; Ohayon MM et al., 2002).

Endothelial cell antibody-mediated rejection and successful retransplantation in a heart transplanted patient

Antibody-mediated rejection (AMR) plays a significant role in cardiac allograft dysfunction, and recently a consensus regarding the diagnosis of AMR has been published. To our knowledge, it has not previously been reported that acute graft failure related to AMR, and antiendothelial cell antibodies can successfully be diagnosed to allow the patient to receive the outlined treatment and undergo a subsequent retransplantation.

Unexplained syncope--is screening for carotid sinus hypersensitivity indicated in all patients aged >40 years?

OBJECTIVE: To determine the frequency, age distribution and clinical presentation of carotid sinus hypersensitivity (CSH) among 373 patients (age range 15-92 years) referred to two autonomic referral centres during a 10-year period. METHODS: Carotid sinus massage (CSM) was performed both supine and during 60 degree head-up tilt. Beat-to-beat blood pressure, heart rate and a three-lead electrocardiography were recorded continuously. CSH was classified as cardioinhibitory (asystole > or = 3 s), vasodepressor (systolic blood pressure fall > or = 50 mm Hg) or mixed. All patients additionally underwent autonomic screening tests for orthostatic hypotension and autonomic failure. RESULTS: CSH was observed in 13.7% of all patients. The diagnostic yield of CSM was nil in patients aged < 50 years (n = 65), 2.4% in those aged 50-59 years (n = 82), 9.1% in those aged 60-69 years (n = 77), 20.7% in those aged 70-79 years (n = 92) and reached 40.4% in those > 80 years (n = 57). Syncope was the leading clinical symptom in 62.8%. In 27.4% of patients falls without definite loss of consciousness was the main clinical symptom. Mild and mainly systolic orthostatic hypotension was recorded in 17.6%; evidence of sympathetic or parasympathetic dysfunction was found in none. CONCLUSIONS: CSH was confirmed in patients > 50 years, the incidence steeply increasing with age. The current European Society of Cardiology guidelines that recommend testing for CSH in all patients > 40 years with syncope of unknown aetiology may need reconsideration. Orthostatic hypotension was noted in some patients with CSH, but evidence of sympathetic or parasympathetic failure was not found in any of them.

Sex differences in heart rate variability: a longitudinal study in international elite cross-country skiers

PURPOSE: Exercise-related sudden cardiac deaths (SCD) occur with a striking male predominance. A higher sympathetic tone in men has been suggested as risk factor for SCD. Elite athletes have the highest risk for exercise-related SCD. We aimed to analyze the autonomic nervous system of elite cross-country skiers from Norway, Russia and Switzerland in supine position and after orthostatic challenge in various training periods (TP). METHOD: Measurements of heart rate variability (HRV) were performed on a weekly basis over 1 year using an orthostatic challenge test with controlled breathing. Main outcome parameters were the high-frequency power in supine position (HFsupine) as marker of cardiac parasympathetic activity and the low-frequency/high-frequency power ratio after orthostatic challenge (LF/HFstand) as marker of cardiac sympathetic activation. Training intensity and duration were recorded daily and expressed as training strain. The training year was divided into three TPs. An average of weekly HRV measurements was calculated for each TP. RESULT: Female (n = 19, VO2max 62.0 +/- 4.6 ml kg(-1) min(-1), age 25.8 +/- 4.3 years) and male (n = 16, VO2max 74.3 +/- 6.3 ml kg(-1) min(-1), age 24.4 +/- 4.2 years) athletes were included. Training strain was comparable between sexes (all p > 0.05) and changed between TPs (all p < 0.05) while no HRV parameters changed over time. There were no sex differences in HFsupine while the LF/HFstand was significantly higher in male athletes in all TPs. CONCLUSION: For a comparable amount of training, male athletes showed constantly higher markers of sympathetic activity after a provocation maneuver. This may explain part of the male predominance in sports-related SCD.

Adaptation and maladaptation of heart and skeletal muscle to different diets in a rodent model of human obesity

Obesity and diabetes are metabolic disorders associated with fatty acid availability in excess of the tissues' capacity for fatty acid oxidation. This mismatch is implicated in the pathogenesis of cardiac contractile dysfunction and also in skeletal muscle insulin resistance. My dissertation will present work to test the overall hypothesis that "western" and high fat diets differentially affect cardiac and skeletal muscle fatty acid oxidation, the expression of fatty acid responsive genes, and cardiac contractile function. Wistar rats were fed a low fat, "western," or high fat (10%, 45%, or 60% calories from fat, respectively) diet for acute (1 day to 1 week), short (4 to 8 weeks), intermediate (16 to 24 weeks), or long (32 to 48 weeks) term. With high fat diet, cardiac oleate oxidation increased at all time points investigated. In contrast, with western diet cardiac oleate oxidation increased in the acute, short and intermediate term, but not in the long term. Consistent with a maladaptation of fatty acid oxidation, cardiac power (measured ex vivo) decreased with long term western diet only. In contrast to the heart, soleus muscle oleate oxidation increased only in the acute and short term with either western or high fat feeding. Transcript analysis revealed that several fatty acid responsive genes, including pyruvate dehydrogenase kinase 4, uncoupling protein 3, mitochondrial thioesterase 1, and cytosolic thioesterase 1 increased in heart and soleus muscle to a greater extent with high fat diet, versus western diet, feeding. In conclusion, the data implicate inadequate induction of a cassette of fatty acid responsive genes in both the heart and skeletal muscle by western diet resulting in impaired activation of fatty acid oxidation, and the development of cardiac dysfunction. ^

Rat Adipose Tissue-Derived Stem Cells Transplantation Attenuates Cardiac Dysfunction Post Infarction and Biopolymers Enhance Cell Retention

Background: Cardiac cell transplantation is compromised by low cell retention and poor graft viability. Here, the effects of co-injecting adipose tissue-derived stem cells (ASCs) with biopolymers on cell cardiac retention, ventricular morphometry and performance were evaluated in a rat model of myocardial infarction (MI). Methodology/Principal Findings: (99m)Tc-labeled ASCs (1 x 10(6) cells) isolated from isogenic Lewis rats were injected 24 hours post-MI using fibrin a, collagen (ASC/C), or culture medium (ASC/M) as vehicle, and cell body distribution was assessed 24 hours later by gamma-emission counting of harvested organs. ASC/F and ASC/C groups retained significantly more cells in the myocardium than ASC/M (13.8+/-2.0 and 26.8+/-2.4% vs. 4.8+/-0.7%, respectively). Then, morphometric and direct cardiac functional parameters were evaluated 4 weeks post-MI cell injection. Left ventricle (LV) perimeter and percentage of interstitial collagen in the spare myocardium were significantly attenuated in all ASC-treated groups compared to the non-treated (NT) and control groups (culture medium, fibrin, or collagen alone). Direct hemodynamic assessment under pharmacological stress showed that stroke volume (SV) and left ventricle end-diastolic pressure were preserved in ASC-treated groups regardless of the vehicle used to deliver ASCs. Stroke work (SW), a global index of cardiac function, improved in ASC/M while it normalized when biopolymers were co-injected with ASCs. A positive correlation was observed between cardiac ASCs retention and preservation of SV and improvement in SW post-MI under hemodynamic stress. Conclusions: We provided direct evidence that intramyocardial injection of ASCs mitigates the negative cardiac remodeling and preserves ventricular function post-MI in rats and these beneficial effects can be further enhanced by administrating co-injection of ASCs with biopolymers.

Cell Therapy Attenuates Cardiac Dysfunction Post Myocardial Infarction: Effect of Timing, Routes of Injection and a Fibrin Scaffold

Background: Cell therapy approaches for biologic cardiac repair hold great promises, although basic fundamental issues remain poorly understood. In the present study we examined the effects of timing and routes of administration of bone marrow cells (BMC) post-myocardial infarction (MI) and the efficacy of an injectable biopolymer scaffold to improve cardiac cell retention and function. Methodology/Principal Findings: (99m)Tc-labeled BMC (6x10(6) cells) were injected by 4 different routes in adult rats: intravenous (IV), left ventricular cavity (LV), left ventricular cavity with temporal aorta occlusion (LV(+)) to mimic coronary injection, and intramyocardial (IM). The injections were performed 1, 2, 3, or 7 days post-MI and cell retention was estimated by gamma-emission counting of the organs excised 24 hs after cell injection. IM injection improved cell retention and attenuated cardiac dysfunction, whereas IV, LV or LV* routes were somewhat inefficient (< 1%). Cardiac BMC retention was not influenced by timing except for the IM injection that showed greater cell retention at 7 (16%) vs. 1, 2 or 3 (average of 7%) days post-MI. Cardiac cell retention was further improved by an injectable fibrin scaffold at day 3 post-MI (17 vs. 7%), even though morphometric and function parameters evaluated 4 weeks later displayed similar improvements. Conclusions/Significance: These results show that cells injected post-MI display comparable tissue distribution profile regardless of the route of injection and that there is no time effect for cardiac cell accumulation for injections performed 1 to 3 days post-MI. As expected the IM injection is the most efficient for cardiac cell retention, it can be further improved by co-injection with a fibrin scaffold and it significantly attenuates cardiac dysfunction evaluated 4 weeks post myocardial infarction. These pharmacokinetic data obtained under similar experimental conditions are essential for further development of these novel approaches.

Changes in cardiac heparan sulfate proteoglycan expression and streptozotocin-induced diastolic dysfunction in rats

Background: Changes in the proteoglycans glypican and syndecan-4 have been reported in several pathological conditions, but little is known about their expression in the heart during diabetes. The aim of this study was to investigate in vivo heart function changes and alterations in mRNA expression and protein levels of glypican-1 and syndecan-4 in cardiac and skeletal muscles during streptozotocin (STZ)-induced diabetes. Methods: Diabetes was induced in male Wistar rats by STZ administration. The rats were assigned to one of the following groups: control (sham injection), after 24 hours, 10 days, or 30 days of STZ administration. Echocardiography was performed in the control and STZ 10-day groups. Western and Northern blots were used to quantify protein and mRNA levels in all groups. Immunohistochemistry was performed in the control and 30-day groups to correlate the observed mRNA changes to the protein expression. Results: In vivo cardiac functional analysis performed using echocardiography in the 10-day group showed diastolic dysfunction with alterations in the peak velocity of early (E) diastolic filling and isovolumic relaxation time (IVRT) indices. These functional alterations observed in the STZ 10-day group correlated with the concomitant increase in syndecan-4 and glypican-1 protein expression. Cardiac glypican-1 mRNA and skeletal syndecan-4 mRNA and protein levels increased in the STZ 30-day group. On the other hand, the amount of glypican in skeletal muscle was lower than that in the control group. The same results were obtained from immunohistochemistry analysis. Conclusion: Our data suggest that membrane proteoglycans participate in the sequence of events triggered by diabetes and inflicted on cardiac and skeletal muscles.

Exercise training reduces cardiac angiotensin II levels and prevents cardiac dysfunction in a genetic model of sympathetic hyperactivity-induced heart failure in mice

The role of exercise training (ET) on cardiac renin-angiotensin system (RAS) was investigated in 3-5 month-old mice lacking alpha(2A-) and alpha(2C-)adrenoceptors (alpha(2A)/alpha(2C)ARKO) that present heart failure (HF) and wild type control (WT). ET consisted of 8-week running sessions of 60 min, 5 days/week. In addition, exercise tolerance, cardiac structural and function analysis were made. At 3 months, fractional shortening and exercise tolerance were similar between groups. At 5 months, alpha(2A)/alpha(2C)ARKO mice displayed ventricular dysfunction and fibrosis associated with increased cardiac angiotensin (Ang) II levels (2.9-fold) and increased local angiotensin-converting enzyme activity (ACE 18%). ET decreased alpha(2A)/alpha(2C)ARKO cardiac Ang II levels and ACE activity to age-matched untrained WT mice levels while increased ACE2 expression and prevented exercise intolerance and ventricular dysfunction with little impact on cardiac remodeling. Altogether, these data provide evidence that reduced cardiac RAS explains, at least in part, the beneficial effects of ET on cardiac function in a genetic model of HF.

Exercise training delays cardiac dysfunction and prevents calcium handling abnormalities in sympathetic hyperactivity-induced heart failure mice

Exercise training (ET) is a coadjuvant therapy in preventive cardiology. It delays cardiac dysfunction and exercise intolerance in heart failure (HF); however, the molecular mechanisms underlying its cardioprotection are poorly understood. We tested the hypothesis that ET would prevent Ca2+ handling abnormalities and ventricular dysfunction in sympathetic hyperactivity-induced HF mice. A cohort of male wildtype (WT) and congenic (alpha 2A/alpha 2C)-adrenoceptor knockout ((alpha 2A/alpha 2C)ARKO) mice with C57BL6/J genetic background (3-5 mo of age) were randomly assigned into untrained and exercise-trained groups. ET consisted of 8-wk swimming session, 60 min, 5 days/wk. Fractional shortening (FS) was assessed by two-dimensional guided M-mode echocardiography. The protein expression of ryanodine receptor (RyR), phospho-Ser(2809)-RyR, sarcoplasmic reticulum Ca2+ ATPase (SERCA2), Na+/Ca2+ exchanger (NCX), phospholamban (PLN), phospho-Ser(16)-PLN, and phospho-Thr(17)-PLN were analyzed by Western blotting. At 3 mo of age, no significant difference in FS and exercise tolerance was observed between WT and (alpha 2A/alpha 2C)ARKO mice. At 5 mo, when cardiac dysfunction is associated with lung edema and increased plasma norepinephrine levels, (alpha 2A/alpha 2C)ARKO mice presented reduced FS paralleled by decreased SERCA2 (26%) and NCX (34%). Conversely, (alpha 2A/alpha 2C)ARKO mice displayed increased phospho-Ser(16)-PLN (76%) and phospho-Ser(2809)-RyR (49%). ET in (alpha 2A/alpha 2C)ARKO mice prevented exercise intolerance, ventricular dysfunction, and decreased plasma norepinephrine. ET significantly increased the expression of SERCA2 (58%) and phospho-Ser(16)-PLN (30%) while it restored the expression of phospho-Ser(2809)-RyR to WT levels. Collectively, we provide evidence that improved net balance of Ca2+ handling proteins paralleled by a decreased sympathetic activity on ET are, at least in part, compensatory mechanisms against deteriorating ventricular function in HF.

Cardiac troponin T as a biochemical marker of cardiac dysfunction and ductus venosus Doppler velocimetry

Objectives: The aim of this study was to determine the correlation between ductus venosus (DV) Doppler velocimetry and fetal cardiac troponin T (cTnT). Study design: Between March 2007 and March 2008, 89 high-risk pregnancies were prospectively studied. All patients delivered by cesarean section and the Doppler exams were performed on the same day. Multiple regression included the following variables: maternial age, parity, hypertension, diabetes, gestational age at delivery, umbilical artery (UA) S/D ratio, diagnosis of absent or reversed end-diastolic flow velocity (AREDV) in the UA, middle cerebral artery (MCA) pulsatility index (131), and DV pulsatility index for veins (PIV). Immediately after delivery, UA blood samples were obtained for the measurement of pH and cTnT levels. Statistical analysis included the Kruskal-Wallis test and multiple regressions. Results: The results showed a cTnT concentration at birth >0.05 ng/ml in nine (81.8%) of AREDV cases, a proportion significantly higher than that observed in normal UA S/D ratio and UA S/D ratio >p95 with positive diastolic blood flow (7.7 and 23.1%, respectively, p < 0.001). A positive correlation Was found between abnormal DV-PIV and elevated cTnT levels in the UA. Multiple regression identified DV-PIV and a diagnosis of AREDV as independent factors associated with abnormal fetal cTnT levels (p < 0.0001, F(2.86) = 63.5, R = 0.7722). Conclusion: DV-PIV was significantly correlated with fetal cTnT concentrations at delivery. AREDV and abnormal DV flow represent severe cardiac compromise, with increased systemic venous pressure, and a rise in right ventricular afterload, demonstrated by myocardial damage and elevated fetal cTnT. (C) 2009 Elsevier Ireland Ltd. All rights reserved.

Intramyocardial transplantation of fibroblasts expressing vascular endothelial growth factor attenuates cardiac dysfunction

In this study, we analyzed whether transplantation of cardiac fibroblasts (CFs) expressing vascular endothelial growth factor (VEGF) mitigates cardiac dysfunction after myocardial infarction (MI) in rats. First, we observed that the transgene expression lasts longer (45 vs 7 days) when fibroblasts are used as vectors compared with myoblasts. In a preventive protocol, induction of cardiac neovascularization accompanied by reduction in myocardial scar area was observed when cell transplantation was performed 1 week before ischemia/reperfusion and the animals analyzed 3 weeks later. Finally, the therapeutic efficacy of this approach was tested injecting cells in a fibrin biopolymer, to increase cardiac retention, 24 h post-MI. After 4 weeks, an increase in neovascularization and a decrease in myocardial collagen were observed only in rats that received cells expressing VEGF. Basal indirect or direct hemodynamic measurements showed no differences among the groups whereas under pharmacological stress, only the group that received cells expressing VEGF showed a significant reduction in end-diastolic pressure and improvement in stroke volume and cardiac work. These results indicate that transplantation of CFs expressing VEGF using fibrin biopolymer induces neovascularization and attenuates left ventricle fibrosis and cardiac dysfunction in ischemic heart. Gene Therapy (2010) 17, 305-314; doi:10.1038/gt.2009.146; published online 10 December 2009

Matrix Metalloproteinase Inhibition Improves Cardiac Dysfunction and Remodeling in 2-Kidney, 1-Clip Hypertension

Background: Enhanced cardiac matrix metalloproteinase activity (MMPs) has been associated with ventricular remodeling and cardiac dysfunction. It is unknown whether MMPs contribute to systolic/diastolic dysfunction and compensatory remodeling in 2-kidney, 1-clip (2K1C) hypertensive rats. To test this hypothesis, we used 2K1C rats after 2 weeks of surgery treated or not with a nonspecific inhibitor of MMPs (doxycycline). Methods and Results: We found that blood pressure and +/-dP/dt increased in 2K1C rats compared with sham groups, and these parameters were attenuated by doxycycline treatment (P < .05). Doxycycline also reversed cardiac hypertrophy observed in 2K1C rats (P < .05). Hypertensive rats showed increased MMP-2 levels in zymograms and in the tissue by immunofluorescence (P < .05) compared with sham groups. Increased total gelatinolytic activity was observed in untreated 2K1C rats when compared with sham groups (P < .05). Doxycycline decreased total gelatinolytic activity in 2K1C rats to control levels (P < .05). Conclusion: An imbalance in gelatinolytic activity, with increased MMP-2 levels and activity underlies the development of morphological and functional alterations found in the compensatory hypertrophy observed in 2K1C hearts. Because function and structure were restored by doxycycline, the inhibition of MMPs or their modulation may provide beneficial effects for therapeutic intervention in cardiac hypertrophy. (J Cardiac Fail 2010;16:599-608)