Enrique Hong

Effect of losartan on vascular function in fructose-fed rats: the role of perivascular adipose tissue.

Recent studies have shown the effect of perivascular adipose tissue (PVAT) on the regulation of vascular function; however, its role in the model of metabolic syndrome remains unclear. The aim of this study was to examine the effect of losartan on PVAT-derived vascular dysfunction in fructose-induced hypertensive rats. Rats were fed with either water, 10% fructose, or 10% fructose with 10mg/kg losartan for 8 weeks. In the isolated aorta with PVAT and endothelium, contraction induced by norepinephrine (NE) was more potent in fructose-fed rats compared to control rats. Losartan normalized blood pressure, insulin resistance, and NE-induced vasoconstriction in fructose-fed rats. In the aortic rings with/without endothelium and with/without PVAT, losartan could not improve the acetylcholine-induced relaxation in fructose-fed rats. The observation suggested that losartan partly improved the PVAT-associated vascular regulation in fructose-induced hypertensive rats.

Lipid peroxidation by nitric oxide supplements after spinal cord injury: effect of antioxidants in rats

To determine the extent to which exogenous nitric oxide (NO) might affect hemodynamics and/or increase oxidative damage after acute spinal cord (SC) injury, rats were submitted to SC contusion, and given a NO donor or NO precursor. Intravenous isosorbide dinitrate (10 microg/kg per min) or L-arginine (300 mg/kg per 23 h) showed a tendency to increase lipid peroxidation (LP), although without reaching significance compared to non-treated injured rats 24 h post-injury, and without affecting mean arterial pressure and heart rate importantly. LP due to injury and exogenous NO was significantly inhibited by the co-administration of a cocktail of antioxidants (12 mg/kg superoxide dismutase mimetic, 27000 U/kg catalase, and 12 mg/kg glutathione), but less effectively for the injury-L-arginine condition. These results demonstrate that in order to further test the potential neuroprotective effect of NO enhancing reagents after SC injury, antioxidants must be included in the treatment scheme.

Mechanisms involved in the cardiovascular alterations immediately after spinal cord injury.

The early cardiovascular effects resulting from an acute spinal cord injury (SCI) produced by a contusion procedure at T5-T6 were evaluated in anaesthetized rats. The mean arterial pressure (MAP) and heart rate (HR) were measured during one hour after the injury. A marked decrease in MAP and HR was observed immediately after injury, followed by an abrupt increase in MAP. These changes were observed between 3 and 9 min and the basal values were recovered after 20 min. Fall in the MAP and HR and increase in MAP induced by SCI were abolished by atropine. The interruption of the parasympathetic outflow by vagotomy also significantly diminished the fall and increase in MAP and the fall in HR. Likewise, pre-treatment with nitric oxide synthase inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME) completely abolished the effects produced by SCI. These data suggest that after SCI the decrement in MAP and HR was probably due to acetylcholine release from parasympathetic fibers and NO from endothelial source probably by a cholinergic stimulation. Additionally, the MAP increase observed was probably due to a reflex compensatory vasoconstriction.

Endothelial activation and systemic inflammation in obese asthmatic children.

Asthma and obesity are prevalent disorders, each with a significant impact on the public health. The causality relating obesity and asthma has not been established. The objective of this article is to investigate whether asthma could exacerbate the endothelial activation and to determine the relationship between systemic inflammation and endothelial activation in obese asthmatic children. Eighty-nine children (10-16 years old) were divided according to their diagnosis (asthma, obese nonasthmatic, and obese asthmatic children). Twenty healthy children formed the control group. Three adhesion molecules (E-selectin, sICAM-1, and sVCAM-1) and C-reactive protein (CRP) were measured in serum samples. The levels of sICAM-1 were significantly higher in obese nonasthmatic and obese asthmatic children versus control and lean asthmatic children (414.7+/-154.7, 434.9+/-181.1, 238.6+/-117.8, and 351.2+/-153.5 ng/mL, respectively). No difference was observed between obese nonasthmatic and obese asthmatic groups. No difference of the levels of CRP, E-selectin, and sVCAM-1 was found among the study groups. Correlation analysis showed that E-selectin associated significantly with body mass index (BMI), CRP and the other two adhesion molecules. CRP depended on BMI. sICAM-1 associated with CRP, BMI, and triglycerides. Correlations were verified in multiple regression analysis models in the whole study groups: CRP levels depended on sICAM-1, E-selectin, and sICAM-1 concentrations depended on BMI. Correlations were verified in asthmatic subjects: CRP depended on sICAM-1. These results confirmed the endothelial activation in obese children. Mild nonallergic asthma in our study did not exacerbate the endothelial activation in obese or lean asthmatic children. Significant association between systemic inflammation and endothelial activation was observed in asthmatic children.

Weight loss induced by 6‐month lifestyle intervention improves early endothelial activation and fibrinolysis in obese adolescents

BACKGROUND Adolescent obesity is associated with an increased risk of adult obesity and subsequent cardiovascular diseases. The present study aimed to assess the effect of weight loss after 6-month lifestyle intervention in obese adolescents on biomarkers of endothelial activation and fibrinolytic system. METHODS Eighty-five obese adolescents aged 10 to 16 years were assigned to a 6-month lifestyle intervention and 61 completed the programme. We examined the effect of the intervention on adhesion molecules (selectin E, soluble intercellular adhesion molecule 1 and soluble vascular adhesion molecule 1) and fibrinolytic parameters [plasminogen activator inhibitor-1 (PAI-1) and fibrinogen]. Thirty-six lean adolescents were studied only at baseline as a comparison group. RESULTS Compared with lean participants, obese adolescents at baseline demonstrated significantly higher levels of triglycerides, glucose, insulin, homeostasis model assessment, soluble intercellular adhesion molecule 1, PAI-1 and fibrinogen. After 6-month lifestyle intervention, those obese adolescents with decreased standard deviation score-body mass index (SDS-BMI) displayed significant decreases in insulin (19.2 ± 11.2 vs. 26.8 ± 13.2 mU/L, P≤ 0.01), homeostasis model assessment (4.24 ± 3.19 vs. 6.58 ± 4.08, P≤ 0.01), selectin E (100.2 ± 60.9 vs. 116.0 ± 69.0 ng/mL, P≤ 0.01) and PAI-1 (39.6 ± 38.0 vs. 51.8 ± 25.6 ng/mL, P≤ 0.05) with respect to the baseline levels. No changes in these parameters were observed in the obese adolescents with stable or increased SDS-BMI. The changes of triglycerides after intervention in subgroup with decreased SDS-BMI were significantly greater than those in subgroup with stable SDS-BMI. CONCLUSIONS The present study demonstrated increased endothelial activation and impairment of the fibrinolytic system in early life, which is in part reversible by a 6-month lifestyle intervention.

Sympathetic blockade significantly improves cardiovascular alterations immediately after spinal cord injury in rats.

Immediately after an experimental spinal cord injury (SCI) in rats, there is a large fall in mean arterial pressure (MAP) and heart rate (HR), followed by an abrupt increase in MAP. To better understand the mechanism involved in these early cardiovascular alterations, we tested the effect of treatment with ganglionic and sympathetic blockers in anesthetized rats subjected to T-5 SCI. Fall in MAP was partially diminished by propranolol and pentolinium, while increase in MAP was abolished by propranolol and pentolinium. Adrenalectomy did not diminish the fall in MAP and HR, however, the increase in MAP was significantly reduced. Likewise, propranolol and pentolinium completely abolished the effects in HR. These data suggest that the early cardiovascular alterations secondary to SCI results from an increased parasympathetic activity and a sympathetic withdrawal.

Plasminogen Activator Inhibitor-1, Fibrinogen, and Lung Function in Adolescents with Asthma and Obesity

Background. Obesity promotes a low-grade systemic inflammatory state that may act on the lung to exacerbate asthma. There is little information on the relationship between systemic inflammation and lung function in children and adolescents. Objectives. To explore the relationship among fibrinogen, plasminogen activator inhibitor-1 (PAI-1), lung function in adolescents with the presence of asthma, and/or obesity. Methods. Totally 178 adolescents (boys and girls) were involved; four groups were divided according to their diagnosis: non-obese and non-asthmatic controls (n = 38), non-obese asthmatics (n = 31), obese non-asthmatics (n = 62), obese asthmatics (n = 47). The levels of PAI-1 and fibrinogen were determined in blood samples. The lung function was evaluated with spirometry by measuring forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC), and forced expiratory flows between 25 and75% (FEF25–75%). Results. Compared to healthy controls, obese adolescents with or without asthma show higher levels of fibrinogen (289.2 ± 61.5, 328.4 ± 54.9, and 324.9 ± 68.9 mg/dL, respectively), PAI-1 (36.0 ± 17.3, 53.2 ± 22.3, and 52.6 ± 24.7 ng/mL, respectively), and the reduced FEV1/FVC ratio (87.7 ± 7.7, 81.6 ± 8.6, and 81.7 ± 6.9, respectively). In the whole studied subjects, FEV1/FVC ratio shows significant inverse correlation with PAI-1 (r = −0.185), fibrinogen (r = −0.157), body mass index (BMI; r = −0.303), insulin(r = −0.198), and HOMA (r = −0.173). In the 78 asthmatic subjects, FVC correlates positively with BMI. Conclusion. Our data demonstrate that the degree of systemic inflammation and the degree of obesity in the whole studied adolescents groups correlate negatively with lung function, suggesting an obstructive pulmonary pattern. Further studies are needed to identify the pathophysiological mechanism for such association.

Effect of Early Diabetes on the Response to Norepinephrine and Dopamine in Pithed Wistar Kyoto and Spontaneously Hypertensive Rats

Diabetes has been related to changes in vascular responses, mainly an increase in the vasoconstrictor responses and a decrease in the vasodilator responses. The literature has now begun to study the effects of diabetes in the early stages of development; the first studies on these stages indicate that diabetes produces different changes compared to the advanced stages. For that reason, the aim of this work was to evaluate the responses to norepinephrine and dopamine on normotensive and hypertensive rats with 4 weeks of diabetes evolution. The results showed that 4 weeks of diabetes produces a decrease of the vasopressor response to both agents (norepinephrine and dopamine). These results suggest that in the early stages, there are changes that help to decrease the pressor responses and these changes could disappear in the advanced stages.

Early changes in nitric oxide synthase activity in atrial intramural arteries following experimental spinal cord injury in rats

Previously, we have shown that immediately after an experimental spinal cord injury (SCI) in anaesthetized rats, there is a large fall in mean arterial pressure (MAP) and heart rate (HR), followed by an abrupt increase in MAP. To evaluate the participation of nitric oxide (NO), we evaluated the activity of nitric oxide synthase (NOS) using Nicotinamide adenine dinucleotide phosphate (NADPH) diaphorase histochemistry in sections of atria at several post-injury time-intervals. Staining increased at 3 min, reached a maximum at 9 min and diminished 30 min after injury. Pretreatment with atropine prevented changes in MAP, HR and NADPH-d staining suggesting that such modifications result from an increased vagal stimulation. In conclusion, the NOS activity is transiently elevated in the atrial intramural arteries of rats subjected to an SCI.

Adipokines, asymmetrical dimethylarginine, and pulmonary function in adolescents with asthma and obesity.

Abstract Objective: This study was to investigate whether the metabolic abnormalities of adipokines and asymmetrical dimethylarginine (ADMA) associate with pulmonary function deficits in adolescents with obesity and asthma. Methods: This study enrolled 28 obese adolescents with asthma, 46 obese adolescents without asthma, 58 normal-weight adolescents with asthma, and 63 healthy control subjects. Serum levels of leptin, high-molecule-weight (HMW) adiponectin, retinol binding protein 4 (RBP4), asymmetrical dimethylarginine (ADMA), and pulmonary function were qualified. Results: The obese subjects had higher levels of leptin and ADMA but lower levels of HMW adiponectin than the normal-weight subjects with or without asthma. The subjects with asthma had higher levels of RBP4 than those without asthma. The obese adolescents with asthma had lowest forced expiratory lung volume in the first second (FEV1)/forced vital capacity (FVC) ratio among the four study groups. In all the study subjects and in the subjects with asthma alone, the FEV1/FVC ratio associated negatively with leptin, however, such association was rendered non-significant when adjusted for BMI. The pulmonary function deficits associated inversely with BMI percentile in the subjects with asthma. However, the decreased FEV1/FVC ratio was not correlated with HMW adiponectin, RBP4 or ADMA. Conclusions: Our present study confirmed obstructive pattern of pulmonary function characterized by the reduced FEV1/FVC ratio in the obese adolescents with asthma. These pulmonary deficits were associated inversely with the increased BMI percentile.