Heart rate variability and perception of mental stress among medical students and residents at an emergency department

BACKGROUND

When Medical Residents (MR) and Medical Students (MS) are assigned to the demanding environment of an Emergency they inevitably encounter stress. The aims of this study are to measure short-term heart rate variability (HRV) before and after shifts, estimate perceived stress levels, and assess the recovery patterns after their shifts.

METHODS

We assessed HRV parameters in MS and MR using the wristband physiological monitor Polar® Verify Sense before and after day (DS) and night shifts (NS). Perceived stress levels were evaluated using the simplified State Trait Anxiety Inventory (STAI-S6) and the Subjective Units of Distress Scale.

RESULTS

This study included 60 participants of which 55% were female with a mean age of 26 years. MS presented significant reduction in sympathetic nervous system index after DS [0.68 (0.01-2.42) vs -0.22 (-0.75-1.13), p < 0.01] and NS [0.87 (-0.28-1.45) vs 0.06 (-0.70-1.04), p < 0.01], while MR maintained the same levels of sympathetic activity [DS: 1.17 (0.04 -2.88) vs 0.93 (0.50-1.41), p = 0.14; NS: 1.37 (0.76-2.21) vs 1.29 (0.35-2.18), p = 0.40]. Psychological data from STAI-S6 showed statistically significant differences when comparing before and after DS in both groups, with more perceived stress after than before DS (MS: 12 ± 4 vs 14 ± 4, p = 0.04; MR: 14 ± 4 vs 16 ± 4, p = 0.04), which was not observed at NS (MS: 12 ± 3 vs 12 ± 3, p = 0.84; MR: 15 ± 3 vs 15 ± 4, p = 0.40).

CONCLUSIONS

Short-term HRV recordings before and after day or night shifts among MR and MS revealed heightened sympathetic activity preceding each shift, with a more sustained increase observed in the MR population and more perceived stress after day shifts in both groups.

Effects of Vitamin D Supplementation on Central Hemodynamic Parameters and Autonomic Nervous System in Obese or Overweight Individuals

BACKGROUND

Previous studies have been inconsistent in demonstrating beneficial cardiovascular effects of vitamin D supplementation.

OBJECTIVE

To evaluate the effects of vitamin D3 supplementation on central hemodynamic parameters and autonomic activity in obese/overweight individuals with low vitamin D levels (<30ng/dl).

METHODS

Adults 40-65 years old with body mass index ≥25<40 kg/m2 were enrolled in this prospective, randomized, double-blind clinical trial (NCT05689632). Central hemodynamics was assessed using the oscillometric method (Mobil-O-Graph®), and heart rate variability using a Polar heart rate monitor (Kubios® software). Patients (n=53) received a placebo in the control group (CO, n=25) or vitamin D3 (VD, n=28) 7000 IU/day, and were evaluated before (W0) and after 8 weeks (W8) with a significance level of 0.05.

RESULTS

The groups were homogeneous regarding age (51±6 vs 52±6 years, p=0.509) and vitamin D levels (22.8±4.9 vs 21.7±4.5ng/ml, p=0.590). At W8, the VD group had significantly higher levels of vitamin D (22.5 vs 35.6ng/ml, p<0.001). Only the VD group showed a significant reduction in systolic blood pressure (SBP; 123±15 vs 119±14mmHg, p=0.019) and alkaline phosphatase (213±55 vs 202±55mg/dl, p=0.012). The CO group showed an increase in augmentation pressure (AP: 9 vs 12 mmHg, p=0.028) and augmentation index (AIx: 26 vs 35%, p=0.020), which was not observed in the VD group (AP: 8 vs 8 mmHg, AIx: 26 vs 25%, p>0.05). VD group showed an increase in the parasympathetic nervous system index (PNSi) (-0.64±0.94 vs -0.16±1.10, p=0.028) and the R-R interval (866±138 vs 924±161 ms, p= 0.026).

CONCLUSION

In this sample, eight weeks of daily vitamin D supplementation resulted in an improvement in blood pressure levels and autonomic balance.

Acute Effects of Coffee Consumption on Blood Pressure and Endothelial Function in Individuals with Hypertension on Antihypertensive Drug Treatment: A Randomized Crossover Trial

INTRODUCTION

Coffee is a complex brew that contains several bioactive compounds and some of them can influence blood pressure (BP) and endothelial function (EF), such as caffeine and chlorogenic acids (CGAs).

AIM

This study aimed to evaluate the acute effects of coffee on BP and EF in individuals with hypertension on drug treatment who were habitual coffee consumers.

METHODS

This randomized crossover trial assigned 16 adults with hypertension to receive three test beverages one week apart: caffeinated coffee (CC; 135 mg caffeine, 61 mg CGAs), decaffeinated coffee (DC; 5 mg caffeine, 68 mg CGAs), and water. BP was continuously evaluated from 15 min before to 90 min after test beverages by digital photoplethysmography. Reactive hyperemia index (RHI) assessed by peripheral arterial tonometry evaluated EF before and at 90 min after test beverages. At the same time points, microvascular reactivity was assessed by laser speckle contrast imaging. Repeated-measures-ANOVA evaluated the effect of time, the effect of beverage, and the interaction between time and beverage (treatment effect).

RESULTS

Although the intake of CC produced a significant increase in BP and a significant decrease in RHI, these changes were also observed after the intake of DC and were not significantly different from the modifications observed after the consumption of DC and water. Microvascular reactivity did not present significant changes after the 3 beverages.

CONCLUSION

CC in comparison with DC and water neither promoted an acute increase in BP nor produced an improvement or deleterious effect on EF in individuals with hypertension on drug treatment who were coffee consumers.

Pilot of Outpatient Preoperative Evaluation Through Teleassistance

The pilot project of pre-anesthetic evaluation through telemedicine at the Pedro Ernesto University Hospital (HUPE) of the State University of Rio de Janeiro (UERJ) is a commendable initiative that aims to address the challenges faced by patients in accessing preoperative care. The objective of this study was to reduce the waiting time between the surgical recommendation and its clinical clearance for the procedure. A service flow was established to enable patients to undergo a comprehensive evaluation, including examination and complementary tests, during a single visit with a general practitioner. Based on the type of surgery and the patient's comorbidities, the Teleconsultants Center assessed the case and provided the necessary guidance. A total of 20 patients were attended to in face-to-face sessions during morning shifts, with the participation of Internal Medicine and Anesthesiology. Subsequently, these patients' evaluations were scheduled for teleconsultation to assess their surgical risk. There has been a significant reduction in the time between the surgical recommendation and the clearance for the procedure with a notable improvement compared to the previous protocol. These initial outcomes demonstrate the project's potential to enhance the efficiency and effectiveness of the preoperative evaluation process through teleassistance.

Use of fractional exhaled nitric oxide as a potential predictor of bronchodilator response

Nitric oxide (NO) is an important product of eosinophilic metabolism, and its increase is associated with bronchial remodeling and airway hyperresponsiveness. Fractional exhaled NO (FENO) in the expired air of patients with suspected or diagnosed asthma has been used as a marker for eosinophilic inflammation. This cohort study included asthmatic patients classified under steps 3, 4, or 5 of the global strategy for asthma management and prevention. In the morning of the same day, all patients underwent blood collection for eosinophil counts, followed by FENO measurement and spirometry. We considered 2 groups based on the bronchodilation (BD) response on spirometry (>10% of FVC or FEV1): positive (BD+) and negative (BD-). Differences between the 2 groups were analyzed for demographic features, FENO values, and predictive correlations between FENO and BD. Both groups of patients showed an increase in the eosinophil count (BD+, P = .03; BD-, P = .04) and FENO values (P = .015 for both) with an increase in the asthma severity from step 3 to step 5 of the global strategy for asthma management and prevention. The correlations of FENO and eosinophils as well as FENO values and BD + were 0.127 (95% confidence interval,-0.269 to -0.486) and 0.696 (95% confidence interval, 0.246-0.899; P = .007), respectively. Measuring FENO levels may be useful for identifying patients with BD+.

Randomized controlled trials reporting the effects of probiotics in individuals with overweight and obesity: a critical review of the interventions and body adiposity parameters

Obesity is a complex chronic metabolic disease that impairs health and reduces lifespan. Therefore, effective strategies for the prevention and treatment of obesity are necessary. Although several studies have demonstrated that gut dysbiosis is associated with obesity it, remains controversial whether the altered gut microbiota is a risk factor for or a consequence of obesity. Recent randomized clinical trials (RCTs) evaluating if gut microbiota modulation with probiotics favors weight loss present conflicting results, which can be attributed to the heterogeneity in the study designs. The aim of this paper is to make a comprehensive review describing the heterogeneity of interventions and body adiposity assessment methods of RCTs that evaluated the effects of probiotics on body weight and body adiposity in individuals with overweight and obesity. Thirty-three RCTs were identified through a search strategy. As main results we observed that ∼30% of the RCTs reported a significant decrease in body weight and body mass index (BMI) and ∼50% found a significant reduction in waist circumference and total fat mass. The beneficial effects of probiotics were more consistent in trials with ≥12 weeks, probiotics dose ≥10¹⁰ CFU/day, in capsules, sachets or powder, and without concomitant energy restriction. The evidence of probiotics effects on body adiposity may improve and be more consistent in future RCTs which include methodological characteristics such as longer duration, higher dose, non-dairy vehicle, non-concurrent energy restriction and use of more accurate measures of body fat deposits (e.g., body fat mass and waist circumference) instead of body weight and BMI.

Early Vascular Aging in Obese Individuals with Low Cardiovascular Health

INTRODUCTION

The American Heart Association updated the original recommendations for cardiovascular health (CVH) promotion, defining the Life's Essential 8 (L8).

AIM

the aim of this cross-sectional study was to compare vascular function, central hemodynamics and autonomic modulation in obese individuals with low and moderate CVH-L8.

METHODS

Both sexes, aged 40-70 years and Body Mass Index ≥ 30 and < 40 kg/m², were submitted to anthropometric and biochemical evaluation, assessment of heart rate variability, endothelial function by flow-mediated dilatation (FMD) and central parameters by oscillometry. The CVH-L8 score was determined using the eight metrics defined in the new classification.

RESULTS

Patients (n = 82) were divided according to CVH-L8 classification: moderate group (score CVH-L8 ≥ 50 ≤ 79 points, n = 47) and low group (score CVH-L8 ≤ 49 points, n = 35). Peripheral (119 ± 10 vs 125 ± 15 mmHg, p = 0.048) and central (111 ± 10 vs 118 ± 15 mmHg; p = 0.016) systolic blood pressures and pulse wave velocity (PWV) adequacy (- 0.08 ± 0.34 vs 0.15 ± 0.42 m/s, p = 0.008) were significantly higher in low CVH-L8 group. Brachial FMD (9.24 ± 5.41 vs 6.79 ± 4.74%, p = 0.043) were lower in this same group. Only in the low CVH-L8 group low frequency/high frequency (LF/HF) ratio was significantly correlated with PWV (r = 0.338, p = 0.047) and atherogenic index of plasma with Framingham risk score (r = 0.446, p = 0.008), even after adjustment for age and sex.

CONCLUSION

In this sample of obese individuals, low CVH-L8 was associated with higher peripheral and central blood pressures, and evidence of early vascular aging with arterial stiffness and endothelial dysfunction.

Acute Effects of Dietary Nitrate on Central Pressure and Endothelial Function in Hypertensive Patients: A Randomized, Placebo-Controlled Crossover Study

BACKGROUND

The diet's inorganic nitrate (NO3-) may provide a physiological substrate for reducing nitrate (NO2-) to NO independent of the endothelium. Studies suggest that inorganic NO3- has beneficial effects on cardiovascular health.

OBJECTIVE

This study evaluated the acute effects of 500 mL nitrate-rich beetroot juice (BRJ; containing 11.5mmol NO3-) on blood pressure and endothelial function in treated hypertensive patients.

METHODS

A randomized, placebo-controlled, crossover study was conducted in treated hypertensive patients (n=37; women=62%) who underwent clinical and nutritional evaluation and assessment of central hemodynamic parameters and microvascular reactivity. The significance level was p<0.05.

RESULTS

The mean age was 59±7 years, and mean systolic and diastolic blood pressures were 142±10/83±9mmHg. There was a significant increase in the subendocardial viability ratio (SEVR; 149±25 vs. 165±30%, p<0.001) and reduction in ejection duration (ED; 37±4 vs. 34±4%, p<0.001) in the beetroot phase but no significant SEVR difference in the control phase. The % increase in perfusion (155 vs. 159 %, p=0.042) was significantly increased in the beetroot phase, which was not observed in the control phase. In the beetroot phase, the change in SEVR showed a significant correlation with the change in the area under the curve of post-occlusive reactive hyperemia (AUC-PORH) (r=0.45, p=0.012). The change in ED showed a significant correlation with the post-intervention perfusion peak (r=-0.37, p=0.031) and AUC-PORH (r=-0.36, p=0.046).

CONCLUSIONS

The acute ingestion of BRJ by hypertensive patients resulted in an improvement of endothelial function, which was associated with higher subendocardial viability and performance in myocardial contraction.

Effects of weight loss through lifestyle changes on heart rate variability in overweight and obese patients: A systematic review

BACKGROUND & AIMS

The effects of calorie restriction and physical activity on autonomic regulation and cardiac vagal control in overweight and obese individuals remain inconsistent. Thus, this systematic review aimed to evaluate the weight loss effects through lifestyle changes on heart rate variability (HRV) markers in overweight and obese subjects.

METHODS

A systematic search for studies published up to November 2021 was conducted in MEDLINE, Embase, EBSCO host and VHL REGIONAL/LILACS. The main outcomes were changes in HRV indices from pre- and post-nutritional intervention and exercise in overweight and obese individuals. This review was registered in PROSPERO: CRD42021274467.

RESULTS

The literature search retrieved 959 articles, of which 12 were included in this review. The intervention in nine studies was diet only, in two studies was diet and exercise, and in one study diet was compared to diet and exercise. The weight loss was greater than 10% in four studies and between 5 and 10% in three studies. Most of the studies revealed that weight loss through lifestyle changes seems to promote beneficial effects on HRV, restoring sympathovagal balance by increasing parasympathetic activity and reducing sympathetic activation.

CONCLUSION

This systematic review exhibited the beneficial effects of weight loss through lifestyle changes on cardiac autonomic control in overweight and obese individuals. Future investigations need standardization of HRV indices for better interpretation of autonomic function in different clinical situations.

Effects of probiotics on body adiposity and cardiovascular risk markers in individuals with overweight and obesity: A systematic review and meta-analysis of randomized controlled trials

BACKGROUND & AIMS

Evidence suggests that gut microbiota is a potential factor in the pathophysiology of both obesity and related metabolic disorders. While individual randomized controlled trials (RCTs) have evaluated the effects of probiotics on adiposity and cardiovascular disease (CVD) risk factors in subjects with overweight and obesity, the results are inconsistent. Thus, this systematic review and meta-analysis aimed to evaluate the effects of probiotic supplementation on body weight, body adiposity and CVD risk markers in overweight and obese subjects.

METHODS

A systematic search for RCTs published up to December 2020 was conducted in MEDLINE (via PubMed), EMBASE, Scopus and LILACS. Meta-analysis using a random-effects model was chosen to analyze the impact of combined trials.

RESULTS

Twenty-six RCTs (n = 1720) were included. Data pooling showed a significant effect of probiotics in reducing body weight (MD:-0.70 kg; 95%CI:-1.04,-0.35 kg; P < 0.0001), body mass index (BMI) (MD:-0.24 kg/m²; 95%CI:-0.35,-0.12 kg/m²; P = 0.0001), waist circumference (WC) (MD:-1.13 cm; 95%CI:-1.54,-0.73 cm; P < 0.0001), fat mass (MD:-0.71 kg; 95%CI:-1.10,-0.32 kg; P = 0.0004), tumor necrosis factor-α (MD:-0.16 pg/ml; 95%CI:-0.24,-0.08 pg/ml; P = 0.0001), insulin (MD:-0.85mcU/ml; 95%CI:-1.50,-0.21mcU/ml; P = 0.010), total cholesterol (MD:-0.16 mmol/l; 95%CI:-0.26,-0.05 mmol/l; P = 0.003) and LDL (MD:-0.09 mmol/l; 95%CI:-0.16,-0.03 mmol/l; P = 0.006) compared with control groups. There was a significant decrease in body weight, BMI and WC in studies using both single and multi-bacterial species. Decreases in body adiposity parameters were only observed in studies using a probiotic dose of ≥ 10¹⁰ CFU and for ≥8 weeks duration.

CONCLUSIONS

The present meta-analysis suggests that probiotics consumption may be helpful for improving body weight, body adiposity and some CVD risk markers in individuals with overweight and obesity. The review was registered on PROSPERO (International prospective register of systematic reviews): CRD42020183136.

Microvascular Reactivity in Hypertensive Patients with High Body Adiposity

Fundamento:

Diversos índices antropométricos têm sido propostos para determinar a associação entre excesso de peso e fatores de risco cardiovascular.

Objetivo:

Avaliar a relação entre adiposidade corporal e reatividade microvascular em pacientes hipertensos sob terapia anti-hipertensiva.

Métodos:

Pacientes hipertensos tratados de 40 a 70 anos foram submetidos à avaliação de índices antropométricos: conicidade (IC), adiposidade corporal (IAC), adiposidade visceral (IAV) e relação cintura-estatura (RCE). Os participantes foram divididos pelos tercis de percentual de gordura (%G) obtido pela bioimpedância elétrica (BIA) e submetidos a teste de reatividade microvascular (laser speckle contrast image), medida da velocidade da onda de pulso (VOP). O valor de p < 0,05 foi considerado estatisticamente significativo.

Resultados:

A variação da área sob a curva (ASC) da perfusão cutânea foi inferior no tercil superior (97 ± 57% vs. 67 ± 36%; p = 0,027). O %G apresentou correlação significativa com RCE (r = 0,77; p < 0,001), IAV (r = 0,41; p = 0,018), IC (r = 0,60; p < 0,001) e IAC (r = 0,65; p < 0,001) nos homens e somente com RCE (r = 0,55; p < 0,001) e IAC (r = 0,60; p < 0,001) nas mulheres. Na regressão linear, a ASC mostrou associação independente com o %G (β =–3,15; p = 0,04) nas mulheres e com a glicemia (β = –1,15; p = 0,02) nos homens. Não houve diferença nas medidas de VOP.

Conclusão:

Os índices antropométricos de obesidade foram mais associados ao %G nos homens. A maior adiposidade corporal foi relacionada com menor reatividade microvascular, o que foi mais evidente nas mulheres. Não houve diferença na rigidez arterial, o que pode ter sido influenciado pelo tratamento anti-hipertensivo.

Evaluation of endothelial function and arterial stiffness in obese individuals with insulin resistance

BACKGROUND

Obesity is associated with metabolic imbalance, including insulin resistance and endothelial dysfunction.

AIM

We aimed to evaluate clinical and vascular parameters in obese with or without insulin resistance.

METHODS

Participants ( n=39) were divided into two groups according to Homeostasis Model Assessment - Insulin Resistance lower (group 1) or higher (group 2) than 2.7. All patients were submitted to clinical, anthropometric, biochemical, vascular structure and endothelial function assessment.

RESULTS

The mean age (53±9 vs. 52±7 years, p=0.784) and body mass index (34.3±4.1 vs. 35.2±3.9 kg/m², p=0.464) were similar in both groups, and 74.4% were treated hypertensive subjects. Fasting glucose (84±7 vs. 97±18 mg/dl, p=0.004) and insulin (9.32±2.48 vs. 22.74±7.49 μU/ml, p<0.001) were higher in group 2. Group 2 presented lower HDL-cholesterol (59±14 vs. 42±12 mg/dl, p<0.001) and higher triglycerides (122±87 vs. 191±112 mg/dl, p=0.042) levels compared with group 1. HOMA-IR was correlated with abdominal circumference ( r=0.51, p=0.001), abdominal/hip ratio ( r=0.57, p<0.001) and triglycerides/HDL ratio ( r=0.53, p=0.001). Differences in brachial flow-mediated dilation did not reach statistical significance (10.2±6.2 vs. 7.9±4.7%, p=0.245). Carotid intima-media thickness, carotid-femoral pulse wave velocity (8.5±1.9 vs. 9.1±1.5 m/s, p=0.334) and central hemodynamic parameters were also similar between groups.

CONCLUSION

Obese individuals with insulin resistance have higher visceral adiposity associated with impaired glucose and lipid metabolism. Endothelial function and arterial stiffness were similar between the groups, perhaps because of antihypertensive treatment in most of these subjects.

The Role of Renin-Angiotensin-Aldosterone System and Its New Components in Arterial Stiffness and Vascular Aging

Many cardiovascular diseases present renin-angiotensin-aldosterone system (RAAS) hyperactivity as an important pathophysiological mechanism to be target in the therapeutic approaches. Moreover, arterial stiffness is currently considered as a new independent risk factor for cardiovascular disease in different clinical conditions, including hypertension and chronic kidney disease. In fact, excessive stimulation of angiotensin type 1 (AT1) receptors, as well as mineralocorticoid receptors, results in cellular growth, oxidative stress and vascular inflammation, which may lead to arterial stiffness and accelerate the process of vascular aging. In the last decades, a vasoprotective axis of the RAAS has been discovered, and now it is well established that new components with antioxidant and anti-inflammatory properties play important roles promoting vasodilation, natriuresis and reducing collagen deposition, thus attenuating arterial stiffness and improving endothelial function. In this review, we will focus on these pathophysiological mechanisms and the relevance of RAAS inhibition by different strategies to increase arterial compliance and to decelerate vascular aging.

Beneficial effects of acute trans-resveratrol supplementation in treated hypertensive patients with endothelial dysfunction

Endothelial dysfunction is a surrogate marker of cardiovascular risk. Resveratrol is known to improve endothelial function in animals, however, clinical trials are limited. We hypothesized that the acute trans-resveratrol supplementation improves endothelial function in treated hypertensive patients with endothelial dysfunction. Twenty-four hypertensive patients between 45 and 65 years-old with baseline endothelial dysfunction were enrolled in a randomized, cross-over, double-blind, placebo-controlled trial. Individuals received either a single dose of trans-resveratrol (300 mg) or placebo and were crossed-over after a one-week washout period. Blood pressure (BP) measurements, aortic systolic blood pressure (SBP) and brachial flow-mediated dilation (FMD) were performed before and 1.5 hours after the intervention. FMD was significantly increased in women (4.2 ± 0.5 vs 7.1 ± 1.3%, p = 0.026) but not in men (4.4 ± 0.9 vs 4.9 ± 0.8%, p = 0.588) in the trans-resveratrol group. There was no statistical difference between baseline and final values of brachial BP and also no changes in aortic SBP. Patients with higher low-density lipoprotein (LDL) cholesterol had better FMD response to trans-resveratrol than patients with lower LDL cholesterol (7.4 ± 1.2 vs 4.3 ± 1.0%, p = 0.004). Our study demonstrated that the acute supplementation of trans-resveratrol promoted an improvement in endothelial function, especially in women and those with higher LDL-cholesterol, despite no changes in BP. List of Abbreviation: Aix: augmentation index; AP: augmentation pressure; BP: blood pressure; BMI: body Mass Index; CVD: cardiovascular disease; FMD: flow-mediated dilation; FRS: Framingham Risk Score; HDL: high-density lipoprotein; LDL: low-density lipoprotein; NO: nitric oxide; SPSS: Statistical Package for Social Sciences; ROS: reactive oxygen species; SBP: systolic blood pressure; TG: triglycerides.

Potential Role of Endothelin in Early Vascular Aging

Early vascular aging is a process associated with gradual alterations in the vessels, regarding their structure and function, taking a more rapid course than normal biological aging in the arteries. In the presence of cardiovascular disease, these age-associated alterations are accelerated, contributing in the appearance or the progression of cardiovascular disease, such as high blood pressure, dyslipidemia, smoking and diabetes. Endothelin-1 (ET-1) is the most abundant and important endothelin produced by vascular cells. ET-1 exerts its biological actions through the activation of two receptors: ETA and ETB. Many important functions are mediated by the activation of these receptors, such as cardiovascular remodeling, vasoconstriction, cell proliferation and differentiation, production of extracellular matrix, and water and sodium secretion control. ETA receptor seems to participate in the pathogenesis and development of diseases, such as diabetes, atherosclerosis, systemic and pulmonary hypertension, and cardiac remodeling after myocardial ischemia, whereas ETB receptor seems to prevent the overstimulation of ETA receptor, acting as a clearance receptor. Increased ET-1 system activity may contribute to vascular dysfunction in aging via multiple pathways, such as direct hemodynamic effects, vascular oxidative stress, inflammatory activity, mitogenic stimulation of the vascular smooth muscle cells and fibrotic processes. Endothelin receptor antagonists were considered to be used for the treatment of some diseases like hypertension, diabetes and chronic kidney disease. However, besides pulmonary hypertension, this class is not in clinical use because of the side effects and the availability of safer drugs for the treatment of these diseases.

Correlation between Diastolic Function and Endothelial Function in Patients with Type 2 Diabetes and Hypertension

BACKGROUND

Endothelial dysfunction may be involved in the pathophysiology of cardiac abnormalities in patients with diabetes mellitus (DM). A correlation between endothelial dysfunction and diastolic dysfunction in patients with type 1 DM has been demonstrated, but this relationship has not been well investigated in type 2 DM.

OBJECTIVE

Compare groups of patients with type 2 DM and hypertension with and without diastolic dysfunction using endothelial function indexes, and to assess whether correlations exist between the diastolic function and the endothelial function indexes.

METHOD

This was a cross-sectional study of 34 men and women with type 2 DM and hypertension who were aged between 40 and 70 years and were categorized based on assessments of their Doppler echocardiographic parameters as having normal (14 patients) and abnormal (20 patients) diastolic function. Flow-mediated dilatation (FMD) assessments of the brachial artery evaluated the patients' endothelial function.

RESULTS

The mean maximum FMD was 7.15 ± 2.80% for the patients with diastolic dysfunction and it was 11.85 ± 4.77% for the patients with normal diastolic function (p = 0.004). Correlations existed between the maximum FMD and the E/e' ratio (p = 0.040, r = -0.354) and the early wave velocity (e') at the lateral mitral annulus (p = 0.002, r = 0.509).

CONCLUSION

The endothelial function assessed by FMD was worse in hypertensive diabetic patients with diastolic dysfunction. There were correlations between the diastolic function indexes and the endothelial function indexes in our sample.

Omega-3 fatty acids supplementation improves endothelial function and arterial stiffness in hypertensive patients with hypertriglyceridemia and high cardiovascular risk

Association between hypertriglyceridemia and cardiovascular (CV) disease is still controversial. The purpose of this study was to compare omega-3 and ciprofibrate effects on the vascular structure and function in low and high CV risk hypertensive patients with hypertriglyceridemia. Twenty-nine adults with triglycerides 150-499 mg/dL were divided into low (<7.5%) and high (≥7.5%) CV risk, randomized to receive omega-3 fatty acids 1800 mg/d or ciprofibrate 100 mg/d for 12 weeks. Treatment was switched after 8-week washout. Clinical evaluation and vascular tests were assessed at baseline and after intervention. Peripheral (131 ± 3 to 125 ± 3 mm Hg, P < .05) and aortic (124 ± 3 to 118 ± 2 mg/dL, P < .05) systolic blood pressure were decreased by ciprofibrate in low-risk patients. In high-risk patients, pulse wave velocity was reduced (10.4 ± 0.4 to 9.4 ± 0.3 m/s, P < .05) and flow-mediated dilation was increased (11.1 ± 1.6 to 13.5 ± 1.2%, P < .05) by omega-3. In conclusion, omega-3 improved arterial stiffness and endothelial function, pointing out the beneficial effect of this therapy on vascular aging, in high-risk patients.

Assessment of the impact of changes in temperature in Biomphalaria glabrata (Say, 1818) melanic and albino variants infected with Schistosoma mansoni (Sambon, 1907)

Fluctuations in population density of planorbid hosts of S. mansoni are influenced by climatic factors. The knowledge about interference from changes in water temperature in these populations is an important aspect of the epidemiology of schistosomiasis. In this experiment, it is explored the influence of different temperatures on the development of Schistosoma mansoni in Biomphalaria glabrata melanic and albino variants. The results indicated an intrinsic relationship between temperature and development of the parasite in the intramollusc phase, independent of the pigmentation of the mantle of the molluscs. The higher the temperature, the shorter the period necessary for the development of the parasite was while the higher the mortality of infected mollusks. It is concluded that, in the presence of climate change, the increasement of temperature in cold and flooded regions may encourage the establishment of new foci of transmission of schistosomiasis by changing the geographic extent and extending the epidemiological transmission potential. In warm climates, higher temperatures, however, could compromise the transmission of the disease because of biological stress suffered by parasite and host. Under these conditions, it can result in the death of the parasite or a change in their ability to infect new host species of molluscs in new areas. Mantle pigmentation patterns in molluscs have not shown significant interference in the development of the parasite.

Host-parasite relationship between Biomphalaria amazonica (Paraense, 1966) and Schistosoma mansoni (Sambon, 1907)

Biomphalaria amazonica is a planorbid species considered a potential host of Schistosoma mansoni. It is widely distributed in the Neotropical zone, particularly in the North and Centre-West of Brazil and in the North of Bolivia. The aim of the present study was to determine the host-parasite relationship between B. amazonica and S. mansoni (BH and SJ strains). Specimens of B. amazonica and their snail-conditioned water were examined in terms of their ability to attract miracidia. The infectivity of the mollusks was determined by exposing them to 20 miracidia of both strains. Sporocyst development and amebocyte reactions were studied after each mollusk specimen was exposed to 100 miracidia. Although no cercariae were eliminated, specimens of B. amazonica proved capable of attracting 77% of the miracidia they were exposed to. Viable sporocysts with no amebocyte reaction were found 96 hours after the exposure to miracidia. These results indicate the susceptibility of B. amazonica to the BH and SJ strains of S. mansoni, and therefore demonstrate the importance of this planorbid species as a potential vector of the trematode in the areas where it occurs.

Beneficial Effects of Dietary Nitrate on Endothelial Function and Blood Pressure Levels

Poor eating habits may represent cardiovascular risk factors since high intake of fat and saturated fatty acids contributes to dyslipidemia, obesity, diabetes mellitus, and hypertension. Thus, nutritional interventions are recognized as important strategies for primary prevention of hypertension and as adjuvants to pharmacological therapies to reduce cardiovascular risk. The DASH (Dietary Approach to Stop Hypertension) plan is one of the most effective strategies for the prevention and nonpharmacological management of hypertension. The beneficial effects of DASH diet on blood pressure might be related to the high inorganic nitrate content of some food products included in this meal plan. The beetroot and other food plants considered as nitrate sources account for approximately 60-80% of the daily nitrate exposure in the western population. The increased levels of nitrite by nitrate intake seem to have beneficial effects in many of the physiological and clinical settings. Several clinical trials are being conducted to determine the broad therapeutic potential of increasing the bioavailability of nitrite in human health and disease, including studies related to vascular aging. In conclusion, the dietary inorganic nitrate seems to represent a promising complementary therapy to support hypertension treatment with benefits for cardiovascular health.

Functional vascular study in hypertensive subjects with type 2 diabetes using losartan or amlodipine

Background

Antihypertensive drugs are used to control blood pressure (BP) and reduce macro- and microvascular complications in hypertensive patients with diabetes.

Objectives

The present study aimed to compare the functional vascular changes in hypertensive patients with type 2 diabetes mellitus after 6 weeks of treatment with amlodipine or losartan.

Methods

Patients with a previous diagnosis of hypertension and type 2 diabetes mellitus were randomly divided into 2 groups and evaluated after 6 weeks of treatment with amlodipine (5 mg/day) or losartan (100 mg/day). Patient evaluation included BP measurement, ambulatory BP monitoring, and assessment of vascular parameters using applanation tonometry, pulse wave velocity (PWV), and flow-mediated dilation (FMD) of the brachial artery.

Results

A total of 42 patients were evaluated (21 in each group), with a predominance of women (71%) in both groups. The mean age of the patients in both groups was similar (amlodipine group: 54.9 ± 4.5 years; losartan group: 54.0 ± 6.9 years), with no significant difference in the mean BP [amlodipine group: 145 ± 14 mmHg (systolic) and 84 ± 8 mmHg (diastolic); losartan group: 153 ± 19 mmHg (systolic) and 90 ± 9 mmHg (diastolic)]. The augmentation index (30% ± 9% and 36% ± 8%, p = 0.025) and augmentation pressure (16 ± 6 mmHg and 20 ± 8 mmHg, p = 0.045) were lower in the amlodipine group when compared with the losartan group. PWV and FMD were similar in both groups.

Conclusions

Hypertensive patients with type 2 diabetes mellitus treated with amlodipine exhibited an improved pattern of pulse wave reflection in comparison with those treated with losartan. However, the use of losartan may be associated with independent vascular reactivity to the pressor effect.

Risk factors related to low ankle-brachial index measured by traditional and modified definition in hypertensive elderly patients

Peripheral arterial disease (PAD) increases with age and ankle-brachial index (ABI) ≤ 0.9 is a noninvasive marker of PAD. The purpose of this study was to identify risk factors related to a low ABI in the elderly using two different methods of ABI calculation (traditional and modified definition using lower instead of higher ankle pressure). A cross-sectional study was carried out with 65 hypertensive patients aged 65 years or older. PAD was present in 18% of individuals by current ABI definition and in 32% by modified method. Diabetes, cardiovascular diseases, metabolic syndrome, higher levels of systolic blood pressure and pulse pressure, elevated risk by Framingham Risk Score (FRS), and a higher number of total and antihypertensive drugs in use were associated with low ABI by both definitions. Smoking and LDL-cholesterol were associated with low ABI only by the modified definition. Low ABI by the modified definition detected 9 new cases of PAD but cardiovascular risk had not been considered high in 3 patients when calculated by FRS. In conclusion, given that a simple modification of ABI calculation would be able to identify more patients at high risk, it should be considered for cardiovascular risk prediction in all elderly hypertensive outpatients.

Erectile dysfunction and hypertension: impact on cardiovascular risk and treatment

Erectile dysfunction (ED) is a common complaint in hypertensive men and can represent a systemic vascular disease, an adverse effect of antihypertensive medication or a frequent concern that may impair drug compliance. ED has been considered an early marker of cardiovascular disease. The connection between both conditions seems to be located in the endothelium, which may become unable to generate the necessary dilatation in penile vascular bed in response to sexual excitement, producing persistent impairment in erection. On the other hand, the real influence of antihypertensive drugs in erectile function still deserves discussion. Therefore, regardless of ED mechanism in hypertension, early diagnosis and correct approach of sexual life represent an important step of cardiovascular evaluation which certainly contributes for a better choice of hypertension treatment, preventing some complications and restoring the quality of life.

Cardiac fibrosis and vascular remodeling are attenuated by metformin in obese rats

BACKGROUND

Human obesity has been associated with alterations of vascular structure, especially in large and medium arteries, but the effects of insulin-sensitizers are not well known.

METHODS

Twenty-five male Wistar rats received subcutaneous injections of monosodium glutamate (MSG) or an equivalent volume of vehicle from the second to the sixth day after birth, At 16 weeks of age, five MSG rats started receiving an oral treatment with metformin (300 mg/kg) which was maintained for six weeks, composing five groups: control 16 weeks (CON-16), MSG 16 weeks (MSG-16), control 22 weeks (CON-22), MSG 22 weeks (MSG-22), and MSG plus metformin 22 weeks (MET-22). Systolic blood pressure (BP) was verified weekly. The lumen diameter and media thickness, media cross-sectional area (CSA) and growth index of the intramyocardial arterioles were measured. Cardiac interstitial and perivascular collagen density were also evaluated.

RESULTS

Systolic BP was significantly increased in the MSG-22 comparing to MSG-16 group. Insulin resistance was confirmed by HOMA-IR index and metformin-treated group presented reduction of insulin levels at week 22. The morphology analysis showed greater media-to-lumen ratio and CSA in the obese groups, which were reduced by the metformin treatment. Connective tissue deposition in the perivascular region of the left ventricle was significantly higher in the obese groups which was attenuated by metformin.

CONCLUSIONS

Hypertrophic vascular remodeling and cardiac collagen deposition were significantly evident in MSG-induced obese rats. Metformin treatment was able to reduce insulin resistance and attenuated this adverse cardiac and vascular remodeling.

Resistance artery mechanics and composition in angiotensin II-infused mice: effects of cyclooxygenase-1 inhibition

AIMS

The aim of this study was to investigate the role of cyclooxygenase (COX)-1 on vascular alterations in structure, mechanics, and extracellular matrix (ECM) components induced by angiotensin (Ang) II in mesenteric arteries from wild-type (WT) and COX-1 knockout (COX-1(-/-)) mice.

METHODS AND RESULTS

Animals were infused with vehicle or Ang II (400 ng/kg/min, s.c.) ± SC-560 (COX-1 inhibitor), DFU (COX-2 inhibitor), or SQ-29548 (TP receptor antagonist). After 2 weeks, vessels were isolated and exposed to intraluminal pressures (3-140 mmHg, pressurized myograph) to determine mechanical properties. Angiotensin II-induced vascular hypertrophic remodelling in WT was reversed by SC-560 or SQ-29548, but unaffected by DFU. Angiotensin II increased vessel stiffness (P< 0.01), this effect being ameliorated by SC-560 or SQ-29548, but unmodified by DFU. Angiotensin II failed to modify vessel elasticity in COX-1(-/-) mice. In WT vessels, Ang II enhanced COX-1 immunostaining, induced collagen and fibronectin depositions and decreased elastin content (P< 0.01). These effects were reversed by SC-560 or SQ-29548, but unaffected by DFU. In COX-1(-/-) mice, Ang II did not affect ECM contents. In WT, Ang II increased COX-1 and decreased COX-2 expression, and enhanced the vascular release of 6-keto-PGF1α which was prevented by COX-1 blockade. Human coronary artery smooth muscle cells, incubated with Ang II, showed an increased expression of procollagen I, which was abrogated by SC-560 or SQ-29548.

CONCLUSION

Angiotensin II-induced alterations of resistance arteries in structure, mechanics, and ECM composition were prevented by COX-1 inhibition and TP receptor antagonism, indicating that Ang II-mediated vascular damage is mediated by COX-1-derived prostanoid prostacyclin, activating TP receptors.

Prevalência e fatores de risco da doença arterial periférica sintomática e assintomática em hospital terciário, Rio de Janeiro, Brasil

CONTEXTO: Doença arterial periférica é caracterizada pelo índice tornozelo-braquial (ITB) < 0,90, em indivíduos ≥ 40 anos, aumentando a prevalência com a idade. OBJETIVO: Detectar a prevalência de doença arterial periférica assintomática e sintomática, com introdução do ITB, associada a fatores de risco demarcados. MÉTODOS: Coorte descritiva identificada em unidade hospitalar terciária de angiologia, de dezembro de 2006 a dezembro de 2007, com idade ≥ 30 anos. Doenças pregressas e fatores de risco foram analisados associados à prevalência. ITB < 0,90 e questionário padronizado definiram doença arterial periférica sintomática com claudicação e assintomática com ausência de claudicação, ambas comparadas aos sem doença arterial periférica (ITB 0,90-1,30). A análise estatística utilizou programa SPSS, com significância de p < 0,05. RESULTADOS: Dos 407 pacientes, 248 apresentaram doença arterial periférica, sendo 52,2% do sexo feminino, com média de idade de 70,1±10,2 anos (p < 0,005). A prevalência de 60,9% (IC95% 56-66) foi subdividida em: assintomática, 10,1% (IC95% 6,3-13,8); e sintomática, 89,9% (IC95% 86,2-93,7). Destes, 32,2% (IC95% 26,4-38,1) apresentaram isquemia crítica. Ajustada por sexo e idade, a prevalência aumenta significativamente entre 55-74 anos, com predomínio do feminino (1,35:1) nos indivíduos acima de 74 anos. A prevalência dos assintomáticos e sintomáticos foi influenciada por tabagismo, hipertensão, diabéticos autorreferidos e confirmados, sobrepeso, infarto agudo do miocárdio e acidente vascular encefálico (p < 0,005). A média do ITB foi mais baixa nos sintomáticos (0,57±0,17) (p < 0,005). CONCLUSÃO: O ITB detectou doença arterial periférica com graus variáveis de gravidade associada a fatores de risco, identificando os assintomáticos não-claudicantes e os sintomáticos em unidade terciária.

Allopurinol attenuates L-NAME induced cardiomyopathy comparable to blockade of angiotensin receptor

It is widely recognized that L-NAME exposed rats develop myocardial fibrosis and hypertrophy. The aim of this study was to evaluate the contribution of xanthine oxidase (XO) to these phenomena using allopurinol, isolated or associated with olmesartan. Thirty adult male Wistar rats were divided into 5 groups (n=6) and studied for 5 weeks: L group (L-NAME, 40mg/kg/day); L+A group (L-NAME and allopurinol, 40 mg/kg/day); L+O group (L-NAME and olmesartan, 15mg/kg/day); L+A+O group (L-NAME, allopurinol, and olmesartan); and control group. L-NAME caused arterial hypertension and cardiomyocyte hypertrophy. Hypertension was prevented by olmesartan, but not by allopurinol. There was an increase of left ventricular mass index in the L-NAME group that was prevented by allopurinol, olmesartan and by the combination of both. The increase in mean cardiomyocyte transversal area caused by L-NAME was prevented by the allopurinol and olmesartan combination, or by olmesartan used as monotherapy, but not by allopurinol alone. There was a reduction in the myocardial vascularization index caused by L-NAME which was abolished by allopurinol or by olmesartan, but not by the association. L-NAME caused a reduction in the total number of cardiomyocyte nuclei. This was prevented by olmesartan alone or associated with allopurinol, but not by allopurinol alone. We conclude that XO has an important contribution to adverse cardiac remodeling in L-NAME exposed animals. Moreover, allopurinol acts without interfering with L-NAME induced hypertension. The protective action of this drug is comparable to the results obtained with olmesartan. Antioxidative mechanisms are proposed to account for the pressure independent effects of allopurinol.

Treatment of essential hypertension does not normalize capillary rarefaction

OBJECTIVES

To determine if capillary rarefaction persists when hypertension is treated with angiotensin converting enzyme inhibitor, thiazidic diuretic and/or beta-blocker, and to identify which microcirculatory alterations (structural and functional) persist after anti-hypertensive treatment.

METHODS

We evaluated 28 well-controlled essential hypertensive patients and 19 normotensive subjects. Nailfold videocapillaroscopy examination of the fourth finger of the left hand was used to determine the functional capillary densities at baseline, during post-occlusive hyperemia, and after venous congestion. Capillary loop diameters (afferent, apical and efferent) and red blood cell velocity were also quantified.

RESULTS

Compared with normotensive subjects, hypertensive patients showed lower mean functional capillary density at baseline (25.1 +/- 1.4 vs. 33.9 +/- 1.9 cap/mm(2), p<0.01), during post-occlusive reactive hyperemia (29.3 +/- 1.9 vs. 38.2 +/- 2.2 cap/mm(2), p<0.01) and during venous congestion responses (31.4 +/- 1.9 vs. 41.1 +/- 2.3 cap/mm(2), p<0.01). Based on the density during venous congestion, the estimated structural capillary deficit was 25.1%. Mean capillary diameters were not different at the three local points, but red blood cell velocity at baseline was significantly lower in the hypertensive group (0.98 +/- 0.05 vs. 1.17 +/- 0.04 mm/s, p<0.05).

CONCLUSIONS

Patients treated for essential hypertension showed microvascular rarefaction, regardless of the type of therapy used. In addition, the reduced red blood cell velocity associated with capillary rarefaction might reflect the increased systemic vascular resistance, which is a hallmark of hypertension.

Angiotensin II induces vascular dysfunction without exacerbating blood pressure elevation in a mouse model of menopause-associated hypertension

BACKGROUND

Follitropin-receptor knockout (FORKO) mice are estrogen-deficient, hyperandrogenic and exhibit features of menopause and elevated blood pressure (BP). Because the renin-angiotensin system has been implicated in menopause-associated hypertension, we questioned whether angiotensin II (Ang II) challenge would further increase BP in FORKO mice and whether this is associated with cardiovascular remodeling and inflammation.

RESULTS

Ang II (400 ng/kg per min) increased BP, assessed by radiotelemetry, similarly in female FORKO and wild-type (WT) mice. Acetylcholine-induced vasodilation was attenuated and Ang II-induced contraction was enhanced in FORKO mice (P < 0.05). This was associated with increased expression of vascular Ang type 1 receptors (AT1R) and estrogen receptor alpha (ERalpha). Vascular structure (media/lumen ratio) was similar in both groups. Abundance of gp91, nitrotyrosine formation and superoxide production, indices of inflammation and cardiac collagen content were increased in Ang II-treated FORKO compared to Ang II-treated WT mice (P < 0.05).

CONCLUSIONS

Thus, in FORKO mice Ang II exacerbates endothelial dysfunction, augments contractility, increases oxidative stress, and promotes cardiac fibrosis without worsening vascular remodeling or BP elevation compared to Ang II-treated WT controls. Our findings suggest that in FORKO mice Ang II may be more important in influencing vascular tone and endothelial function, possibly through oxidative stress and altered ERalpha signaling, than in arterial remodeling and BP elevation.

Eplerenone offsets cardiac and aortic adverse remodeling in spontaneously hypertensive rats

BACKGROUND

Several studies have shown beneficial effects of eplerenone in hypertension and left ventricular dysfunction, but its action on cardiac and vascular changes secondary to blood pressure elevation are not clear yet.

METHODS

Twenty-five male spontaneously hypertensive rats (SHR) were assigned into five groups: young SHR (16 weeks), control SHR (22 weeks), and SHR treated by eplerenone (50 mg/kg/day), enalapril (10 mg/kg/day) or eplerenone+enalapril during 6 weeks. Five Wistar male rats were used as reference group. Cardiac structure and aorta were analyzed by stereology and image analysis.

RESULTS

The raise of blood pressure (202+/-3 mm Hg in control SHR) was significantly attenuated by eplerenone (169+/-2 mm Hg) or enalapril (170+/-2 mm Hg, P<0.001 versus control SHR), and more intensely by combined therapy (160+/-2 mm Hg, P<0.01 versus eplerenone or enalapril). The number of cardiomyocytes in left ventricle was preserved in enalapril group (35,660+/-910 versus 16,220+/-730x10(3) in control SHR, P<0.01) but more significantly in eplerenone, alone or combined, groups (38,380+/-439 and 38,660+/-374x10(3), respectively, P<0.001 versus control). The increased connective tissue volume density (35.8+/-1.2%) noted in the left ventricle of control SHR was significantly attenuated by eplerenone (7.4+/-0.8%), enalapril (8.0+/-0.6%) or eplerenone+enalapril (6.0+/-1.1%, P<0.01 treated versus control SHR). Media-to-lumen ratio of intramyocardial arteries was reduced by enalapril, but more significantly by eplerenone alone or combined with enalapril. The increase of media cross-sectional area of aorta in control SHR was attenuated by eplerenone and/or enalapril.

CONCLUSIONS

Eplerenone is effective in attenuating cardiovascular remodeling in SHR, confirming the important role of aldosterone in this process.

Role of aldosterone in angiotensin II-induced cardiac and aortic inflammation, fibrosis, and hypertrophy

Activation of the renin-angiotensin-aldosterone system is associated with increased extracellular matrix and inflammatory markers in the cardiovascular system. We evaluated the effects of aldosterone antagonism on cardiovascular structure, collagen deposition, and expression of inflammatory markers in 2-week angiotensin (Ang) II-infused rats (120 ng.kg-1.min-1, s.c.)+/-spironolactone or hydralazine (25 mg.kg-1.d-1). Aortic and cardiac collagen density was evaluated with Sirius red staining. NFkappaB and AP-1 were measured by a electrophoretic mobility shift assay, and ED-1 (macrophage marker) and vascular cell adhesion molecule-1 (VCAM-1) were measured by immunohistochemistry. Ang II increased blood pressure (176+/-2 mmHg vs. 115+/-1 mmHg in controls, p<0.01), which was attenuated by spironolactone (147+/-4 mmHg, p<0.01) and prevented by hydralazine (124+/-2 mmHg, p<0.01). Ang II enhanced left ventricular interstitial collagen type I/III deposition (4.1%+/-0.1% vs. 3.1%+/-0.2%, p<0.05), and this was attenuated by spironolactone but not hydralazine. Ang II-induced cardiac perivascular fibrosis was prevented by spironolactone and hydralazine. Ang II significantly increased cardiac AP-1 activity and ED-1 expression, which was prevented by spironolactone only. Ang II-enhanced NFkappaB activity, and VCAM-1 expression was reduced by spironolactone and hydralazine, whereas aortic hypertrophy was prevented by spironolactone and slightly reduced by hydralazine. In conclusion, blockade of mineralocorticoid receptors with spironolactone inhibited Ang II-induced aortic hypertrophy, cardiac transcription factor activation, upregulation of downstream inflammatory markers, and collagen deposition, thus preventing Ang II-induced cardiovascular damage.

Endothelium-Restricted Overexpression of Human Endothelin-1 Causes Vascular Remodeling and Endothelial Dysfunction

Background— Endothelin (ET)-1 is a potent vasoconstrictor that contributes to vascular remodeling in hypertension and other cardiovascular diseases. Endogenous ET-1 is produced predominantly by vascular endothelial cells. To directly test the role of endothelium-derived ET-1 in cardiovascular pathophysiology, we specifically targeted expression of the human preproET-1 gene to the endothelium by using the Tie-2 promoter in C57BL/6 mice.

Methods and Results— Ten-week-old male C57BL/6 transgenic (TG) and nontransgenic (wild type; WT) littermates were studied. TG mice exhibited 3-fold higher vascular tissue ET-1 mRNA and 7-fold higher ET-1 plasma levels than did WT mice but no significant elevation in blood pressure. Despite the absence of significant blood pressure elevation, TG mice exhibited marked hypertrophic remodeling and oxidant excess-dependent endothelial dysfunction of resistance vessels, altered ET-1 and ET-3 vascular responses, and significant increases in ET B expression compared with WT littermates. Moreover, TG mice generated significantly higher oxidative stress, possibly through increased activity and expression of vascular NAD(P)H oxidase than did their WT counterparts.

Conclusions— In this new murine model of endothelium-restricted human preproET-1 overexpression, ET-1 caused structural remodeling and endothelial dysfunction of resistance vessels, consistent with a direct nonhemodynamic effect of ET-1 on the vasculature, at least in part through the activation of vascular NAD(P)H oxidase.

Humoral immune response of water buffalo monitored with three different antigens of Toxocara vitulorum

Humoral immune response of water buffalo naturally infected with Toxocara vitulorum was monitored using three different antigens of this parasite in serum and colostrum of buffalo cows and calves. Soluble extract (Ex) and excretory/secretory (ES) larval antigens and perienteric fluid antigen (Pe) of adult T. vitulorum were used to measure the antibody levels by an indirect ELISA. Serum of 7-12 buffalo cows for the first 365 days and colostrum of the same number of buffalo cows for the first 60 days of parturition, and serum of 8-10 buffalo calves for the first 365 days after birth were assayed. The ELISA detected antibodies against all three T. vitulorum antigens in the colostrum and serum of 100% of buffalo cows and calves examined. The highest antibody levels against Ex, ES and Pe antigens were detected in the buffalo cow sera during the perinatal period and were maintained at high levels through 300 days after parturition. On the other hand, colostrum antibody concentrations of all three antigens were highest on the first day post-parturition, but decreased sharply during the first 15 days. Concomitantly to the monitoring of immune response, the parasitic status of the calves was also evaluated. In calves, antibodies passively acquired were at the highest concentrations 24 h after birth and remained at high levels until 45 days coincidentally with the peak of T. vitulorum infection. The rejection of the worms by the calves occurred simultaneously with the decline of antibody levels, which reached their lowest levels between 76 and 150 days. Thereafter, probably because of the presence of adults/larvae stimulation, the calves acquired active immunity and the antibodies started to increase slightly in the serum and plateaued between the days 211 and 365. All three antigens were detected by the serum antibodies of buffalo calves; however, the concentration of anti-Pe antibody was higher than anti-EX and anti-ES, particularly after 90 days of age. By conclusion, the buffalo cows develop immunity and keep high levels of antibodies against T. vitulorum-Ex, ES and Pe antigens and these antibodies are transferred to their calves through the colostrum. This passively acquired immunity does not protect the calves against the acquisition of the infection, but these antibodies, passively or actively acquired, may have an important role during worm rejection by the calves and prevention of intestinal reinfection.