Endothelium-dependent and independent vasodilation in young males with previous myocardial infarction

INTRODUCTION: Flow-mediated vasodilatation of brachial arteries, a non-invasive parameter of endothelial function, is correlated with cardiovascular risk factors. An impairment of flow-mediated vasodilatation in the brachial artery is related to the extent of coronary artery disease. AIMS: The authors examined the relationship between flow-mediated vasodilatation and coronary artery disease morphology in young patients who had myocardial infarction. PATIENTS AND METHODS: 28 young patients (all men) with myocardial infarction (age 22-40, mean age: 35 years). Coronarography revealed one vessel disease in 16 patients (A group) and multivessel disease in 12 patients (B group). The control group was 14 healthy, young patients (age 18-36 years mean age: 30 years) (C group). The authors examined in all subjects flow-mediated, endothelium-dependent vasodilatation following reactive hyperaemia and nitroglycerin induced (NTG), endothelium-independent vasodilatation in the brachial artery with high resolution ultrasound (Acuson 128 X P/10). RESULTS: Patients after myocardial infarction showed impaired flow-mediated vasodilatation compared to those of controls. (p < 0.01). Flow-mediated vasodilatation was lower in multivessel disease compare to one vessel disease. Nitroglycerin induced similar degrees of vasodilatation in the myocardial infarction and control groups. CONCLUSION: Young patients with myocardial infarction may have impaired endothelium-dependent dilatation and the decrease of flow-mediated vasodilatation is related to the angiographic extent of coronary artery disease.     

Cyclo-oxygenase inhibition restores the attenuated vasodilation in manganese-deficient rat aorta

Previously we showed that manganese (Mn) deficiency enhances the arterial contractile response to alpha(1) adrenergic stimuli and affects vasomotor tone. The aim of this study was to test the hypothesis that dietary Mn deficiency inhibits the vasodilation pathways of rat aorta. Vascular ring studies were conducted in aortic rings from weanling male Sprague-Dawley rats that were fed either a Mn deficient (MnD) or a Mn adequate/control diet (MnA) (<1 and 12 mg/kg Mn, respectively) for a 14-wk period. We investigated endothelium-dependent vasodilation induced by acetylcholine (Ach; 10(-8) to 3 x 10(-6) mol/L) in isolated 3-mm aortic rings precontracted with l-phenylephrine (l-Phe; 10(-6) mol/L). Seven concentrations of Ach were used in the presence or absence of inhibitors of nitric oxide synthase and cyclo-oxygenase. After a second precontraction, 8 doses of sodium nitroprusside (SNP; 10(-8) to 10(-5) mol/L) were added to assess endothelium-independent vasodilation. We observed a decrease in Ach-induced and SNP-induced vasodilation in MnD rat aortas when compared with MnA rat aortas (P 相似文献   

Generation of heterogeneous memory T cells by live attenuated tularemia vaccine in humans

There is very limited evidence concerning the phenotype, function, and homing characteristics of memory T (T_M) cells elicited by vaccination against intracellular bacteria in humans. Here we studied T_M subsets elicited by exposure to Francisella tularensis in humans as a model of immunity to intracellular bacteria. To this end, T_M cells were evaluated in two groups: (1) subjects immunized with live attenuated tularemia vaccine by skin scarification and (2) tularemia naturally infected subjects. In both groups the immune responses were mediated by CD4⁺ and CD8⁺ effector T_M cells, mostly CD45RA⁻CD62L⁻ and CD45RA⁺CD62L⁻. Based on the expression of CD27, integrins α₄/β_7, and α₄/β₁, it is likely that some of these T_M cells have lytic potential and the ability to enter both mucosal and non-mucosal sites. Thus, regardless of whether by immunization or natural exposure, tularemia antigens elicited a broad spectrum of specific T_M subsets with diverse homing characteristics.     

Acute in vivo elevation of intravascular triacylglycerol lipolysis impairs peripheral T cell activation in humans

BACKGROUND: Previous studies have shown suppressive effects of polyunsaturated fatty acids (PUFAs) on T cell proliferation, but the precise mechanism for this effect has not been fully investigated in vivo in humans. OBJECTIVE: The objective was to determine whether this effect is the result of altered T cell membrane properties and impaired CD3- and CD28-mediated signaling in vivo in humans. DESIGN: Peripheral T cells were isolated from healthy subjects before and 2 h after an intravenous infusion of heparin plus a PUFA-rich lipid emulsion during a euglycemic hyperinsulinemic clamp to induce a 2.5-fold elevation in plasma linoleic acid concentration without significant change in plasma total free fatty acid concentrations. RESULTS: Intravenous infusion of heparin plus the lipid emulsion reduced peripheral T cell membrane fluidity and altered lipid raft organization, both of which were associated with reduced T cell proliferation after stimulation with CD3 plus CD28. Tyrosine phosphorylation of linker of activated T cells and activation of protein kinase B in T cells were also impaired without a reduction in T cell receptor expression. In addition, acute PUFA elevation was associated with a reduction in T cell membrane cholesterol exchange with the cellular milieu ex vivo. CONCLUSIONS: A selective increase in plasma linoleic acid concentration and in intravascular lipolysis has a suppressive effect on peripheral T cell CD28-dependent activation, and this effect is associated with changes in plasma membrane properties. Our results have important implications for nutritional therapy in patients at high risk of septic complications and may also be of relevance to postprandial lipid metabolism disorders such as insulin resistance and type 2 diabetes.     

Fish oil induced hyperlipidemia and oxidative stress in BioF1B hamsters is attenuated by elderberry extract

We have previously reported fish oil induced hyperlipidemia in BioF1B hamsters compared with Golden Syrian (GS) hamsters. Elderberry (Sambucus nigra L.) extract is abundant in anthocyanins and is believed to exert cardioprotective effects primarily by virtue of its hypolipidemic and antioxidant potential. In the current study, high-fat fish oil feeding increased oxidative stress in BioF1B hamsters compared with GS hamsters; this increase was associated with increased levels of omega-3 polyunsaturated fatty acids in plasma and liver. We then investigated whether cosupplementation with anthocyanin-rich elderberry extract would reverse fish oil induced hyperlipidemia and reduce lipid peroxidation in BioF1B hamsters. Plasma and hepatic lipids decreased significantly when hamsters were fed diets containing elderberry extract along with fish oil. Both plasma and liver thiobarbituric acid reactive substances showed significant reductions upon cosupplementation with elderberry extract in fish oil fed BioF1B hamsters. Our findings demonstrate that cosupplementation with elderberry extract reverses hyperlipidemia and lipid peroxidation observed with dietary fish oil alone in BioF1B hamsters.     

Flow-mediated vasodilation is not impaired when HDL-cholesterol is lowered by substituting carbohydrates for monounsaturated fat

Low-fat diets, in which carbohydrates replace some of the fat, decrease serum cholesterol. This decrease is due to decreases in LDL-cholesterol but in part to possibly harmful decreases in HDL-cholesterol. High-oil diets, in which oils rich in monounsaturated fat replace some of the saturated fat, decrease serum cholesterol mainly through LDL-cholesterol. We used these two diets to investigate whether a change in HDL-cholesterol would change flow-mediated vasodilation, a marker of endothelial function. We fed thirty-two healthy volunteers two controlled diets in a weeks' randomised cross-over design to eliminate variation in changes due to differences between subjects. The low-fat diet contained 59.7 % energy (en%) as carbohydrates and 25.7 en% as fat (7.8 en% as monounsaturates); the oil-rich diet contained 37.8 en% as carbohydrates and 44.4 en% as fat (19.3 en% as monounsaturates). Average (sd) serum HDL-cholesterol after the low-fat diet was 0.21 (sd 0.12) mmol/l (8.1 mg/dl) lower than after the oil-rich diet. Serum triacylglycerols were 0.22 (sd 0.28) mmol/l (19.5 mg/dl) higher after the low-fat diet than after the oil-rich diet. Serum LDL and homocysteine concentrations remained stable. Flow-mediated vasodilation was 4.8 (SD 2.9) after the low-fat diet and 4.1 (SD 2.7) after the oil-rich diet (difference 0.7 %; 95 % CI -0.6, 1.9). Thus, although the low-fat diet produced a lower HDL-cholesterol than the high-oil diet, flow-mediated vasodilation, an early marker of cardiovascular disease, was not impaired.     

Ethanol withdrawal in rats is attenuated by intracerebroventricular administration of neuropeptide Y

AIMS: The effects of intracerebroventricular administration of neuropeptide Y (NPY) on ethanol withdrawal were studied in rats. METHODS: Ethanol was administered intragastrically five times daily for 4 days. At 16-17 h after the last infusion of ethanol, rats were rated for withdrawal using a score based on three signs: irritability, tremor and rigidity. Subsequently, the rats received an injection of NPY (12 or 24 nmol) or vehicle and were rated for signs of withdrawal. RESULTS: At both doses, NPY significantly reduced ethanol withdrawal, the effect of the larger dose being more pronounced. CONCLUSIONS: Our results are consistent with the concept that NPY receptors are centrally involved in the regulation of neuronal excitability and might form a novel therapeutic target for treatment of ethanol withdrawal and other states of neuronal hyperexcitability.     

Cholesterol metabolism is affected by calcium phosphate supplementation in humans

Dietary calcium and phosphate precipitate in the small intestine to form insoluble amorphous calcium phosphate (ACP). The ability of ACP to bind and inactivate luminal bile acids might have an effect on cholesterol metabolism. To test this hypothesis, a placebo-controlled, double-blind, crossover study with pentacalcium hydroxy-triphosphate supplementation (CaP; 1.0 g elemental calcium) was conducted in 31 young healthy volunteers. The CaP was incorporated into bread. Serum cholesterol concentrations were lower after 4 wk of supplementation than after 4 wk of placebo (4.36 vs. 4.60 mmol/L; P = 0.008). Serum LDL cholesterol and the ratio of LDL:HDL cholesterol also tended to be lower after CaP supplementation than after placebo (-5.6%, P = 0.083 and -5.4%, P < 0.062, respectively). The participants' fat and cholesterol intakes and fecal fat excretion did not differ in the 2 periods. Although the analysis of fecal samples showed no difference in the excretion of total neutral sterols (sum of cholesterol and its transformation products), the excretion of cholesterol itself increased (9.64 vs. 5.80 micromol/g dry matter; P = 0.025; n = 25), whereas the excretion of the metabolite coprostanol decreased (18.5 vs. 21.0 mumol/g dry matter; P = 0.025; n = 25) in the CaP period. Bile acid excretion increased during the CaP period compared with the placebo period (25.4 vs. 22.9 micromol/g dry matter; P = 0.003). The observed beneficial effects on cholesterol metabolism are not the result of an increased excretion of cholesterol, but might be explained by an increased bile acid excretion and a subsequent regeneration of bile acids from endogenous cholesterol in the liver.     

Sympathetic regulation of glucose uptake by the alpha1-adrenoceptor in human obesity

OBJECTIVE: To investigate the involvement of alpha1-adrenoceptors in the sympathetic regulation of glucose uptake in human adipocytes. RESEARCH METHODS AND PROCEDURES: Twenty-four severely obese subjects participated in this study. The microdialysis technique was used to determine interstitial glucose concentration after stimulation of abdominal subcutaneous adipose tissue with the alpha1-agonist norfenefrine, the alpha1,2beta-agonist norepinephrine, and both agents in combination with the alpha1-antagonist urapidil. The effect of beta-adrenoceptor stimulation was assessed by orciprenaline. Changes in local blood flow were determined using the ethanol escape technique. RESULTS: Both norfenefrine and norepinephrine induced a concentration-dependent decrease of interstitial glucose concentration, with a greater decrease observed with norepinephrine. Preperfusion of adipose tissue with urapidil inhibited glucose decrease. The inhibition was overcome with high concentrations of norfenefrine and norepinephrine, respectively. Both adrenergic agents induced tachyphylaxia. Urapidil enhanced extracellular glucose level at high concentration. Blood flow decreased in the presence of norfenefrine and norepinephrine but increased in response to urapidil. The accelerated blood flow due to urapidil was counteracted by norepinephrine and norfenefrine. Orciprenaline decreased interstitial glucose concentration and increased nutritive blood flow. The observed changes in blood flow induced by adrenergic agents were not related to glucose uptake. DISCUSSION: The stimulatory effect of the sympathetic nerves on glucose uptake in subcutaneous adipose tissue appears to be mediated by the alpha1-adrenoceptor. Norepinephrine enhances glucose entry into adipocytes independently of insulin action. In obese subjects with insulin resistance, the alpha1-adrenergic receptor may provide an important alternative pathway for glucose uptake.     

Alcohol drinking in rats is attenuated by the mixed 5-HT1 agonist/5-HT2 antagonist FG 5893

Over the last three decades, the neurotransmitter serotonin (5-HT) has been implicated in the etiological mechanisms underlying the excessive drinking of ethyl alcohol. Recently, the 5-HT₂ antagonist amperozide was found to reduce selectively the high intake of alcohol in the cyanamide-induced drinking rat without any adverse side effects. The purpose of the present study was to determine the action on alcohol drinking of the novel second-generation amperozide-like drug, which is a mixed 5-HT₁ agonist/5-HT₂ antagonist, FG 5893 (2-[4-[4,4-bis(4-fluorophenyl)butyl]-1-piperazinyl]-3-pyridinecarboxylic acid methyl ester). To induce preference for alcohol in Sprague-Dawley rats, the enzyme aldehyde dehydrogenase was inhibited by cyanamide administered in the absence of alcohol in a dose of 10 mg/kg twice a day over three days. A standard three-bottle preference test was used in which water and a maximally preferred concentration of alcohol were offered to each animal. Following control tests of alcohol preference for 3 days, either a saline control vehicle or FG 5893 in a dose of 0.5, 1.0, or 2.5 mg/kg was administered subcutaneously at 1600 and 2200 for 3 consecutive days. Whereas control injections of saline were without effect on alcohol consumption, all doses of FG 5893 significantly reduced the 24-h intake of alcohol in terms of both absolute g/kg and proportion of alcohol to total fluid intake. Further, the 1.0 and 2.5 mg/kg doses of FG 5893 continued to suppress alcohol consumption over two 4-day tests immediately following the injection sequence and after a 40-day interval. Neither body weights nor intakes of food of the rats were affected by FG 5893 either during or after its administration. Thus, it is proposed that this putative anxiolytic and antidepressant drug causes a prolonged modification in the function of serotonergic synapses in the mesolimbic system of the brain. Because FG 5893 possesses combined 5-HT_1A agonist and 5-HT₂ antagonist characteristics, it is envisaged that the addictive property of alcohol may in part involve a concurrent perturbation in the function of these two subtypes of serotonergic receptors.     

The reduction in alcohol intake produced by enalapril is not attenuated by centrally administered angiotensin inhibitors

Angiotensin-converting enzyme (ACE) inhibitors, which prevent the conversion of angiotensin I to angiotensin II, reduce alcohol intake when injected peripherally. The mechanism by which ACE inhibitors produce this effect on alcohol intake is unknown. A rise in the biosynthesis of angiotensin II in the periphery is known to reduce alcohol intake. In this experiment, we examine the possibility that the reduction in alcohol intake produced by an ACE inhibitor, enalapril, is mediated by a rise in angiotensin II in the brain. Enalapril, 20 mg/kg, injected intraperitoneally, produced a 40% reduction in alcohol intake. This reduction was not attenuated by the concurrent administration into the lateral ventricle of either the ACE inhibitors captopril or ceranapril (1, 10, or 25 μg), or the angiotensin II receptor antagonist Sar¹-Thr⁸-Angiotensin II (5 μg). These findings suggest that the ACE inhibitors do not reduce alcohol intake by raising angiotensin II in the brain.     

Exercise-induced vasodilation is associated with menopause stage in healthy middle-aged women

Leg exercise hemodynamics during single-leg knee extensions were compared among healthy groups of early perimenopausal (n = 15), late perimenopausal (n = 12), and early postmenopausal (n = 11) women. Femoral blood flow (FBF) and vascular conductance (FVC) at rest and during very light work rates (0 and 5 W) were similar among all three menopause stage groups. Vascular responses at 10 W (FBF) and 20 W (FBF and FVC) were significantly higher (P?< 0.05) in early perimenopausal compared with late perimenopausal women. At 15 and 25 W, FBF and FVC were similar between late perimenopausal and early postmenopausal groups but higher (P?< 0.05) in early perimenopausal women as compared with the other two menopausal groups. In the combined sample of all three menopause stage groups, follicle-stimulating hormone was significantly correlated with vascular conductance during submaximal (15 W) exercise (R?= -0.56, P?< 0.001), even after adjustment for age, fitness, LDL cholesterol, and abdominal fat (R?= -0.46, P?= 0.005). Collectively, these findings suggest that in middle-aged women, there is an association between menopause stage and leg vascular responsiveness during exercise.     

Cardiopulmonary reflex is attenuated in iron overload conscious rats

Increased iron intake can lead to iron accumulation in serum and tissues. Its has been described that serum and tissue iron overload increase reactive oxygen species (ROS) levels and reduce the effectiveness of the cardiovascular neural mechanisms involved in the maintenance of the arterial blood pressure whithin a narrow range of variation, therefore, iron overload may disrupt cardiovascular homeostasis contributing to physiopathological status development. In the present study we evaluated whether iron accumulated in serum or tissue of awake animals affect the cardiovascular homeostasis through changes in the cardiopulmonary reflex (CPR). We observed that the CPR is reduced in both serum and tissue iron overloaded groups, but no changes were found in the left ventricular pressure measurements, suggesting that iron-related effects are restrict to the CPR neural pathways. We also observed that the serum overloaded group presented lower basal heart rate levels, suggesting an increased parasympathetic efferent activity directed to the heart in this group. Taken together, our data suggest an important role for the iron-generated ROS to the cardiovascular homeostasis, especially regarding the CPR in awake animals.     

Cardiopulmonary reflex is attenuated in iron overload conscious rats

Increased iron intake can lead to iron accumulation in serum and tissues. Its has been described that serum and tissue iron overload increase reactive oxygen species (ROS) levels and reduce the effectiveness of the cardiovascular neural mechanisms involved in the maintenance of the arterial blood pressure whithin a narrow range of variation, therefore, iron overload may disrupt cardiovascular homeostasis contributing to physiopathological status development. In the present study we evaluated whether iron accumulated in serum or tissue of awake animals affect the cardiovascular homeostasis through changes in the cardiopulmonary reflex (CPR). We observed that the CPR is reduced in both serum and tissue iron overloaded groups, but no changes were found in the left ventricular pressure measurements, suggesting that iron-related effects are restrict to the CPR neural pathways. We also observed that the serum overloaded group presented lower basal heart rate levels, suggesting an increased parasympathetic efferent activity directed to the heart in this group. Taken together, our data suggest an important role for the iron-generated ROS to the cardiovascular homeostasis, especially regarding the CPR in awake animals.     

Replication of live attenuated influenza vaccine viruses in human nasal epithelial cells is associated with H1N1 vaccine effectiveness

In the 2013–2014 and 2015–2016 influenza seasons, live attenuated influenza vaccine (LAIV) generated reduced vaccine effectiveness (VE) against circulating H1N1 strains. This reduced VE coincided with the introduction of pandemic 2009 H1N1 (A/H1N1pdm09) vaccine virus reassortants, in place of pre-2009 seasonal H1N1 strains. Here, we explored one specific hypothesis for reduced VE; decreased replicative fitness of A/H1N1pdm09 strains in humans. Two A/H1N1pdm09 strains with reduced VE, A/California/07/2009 (A/CA09) and A/Bolivia/559/2013 (A/BOL13), were compared to pre-2009 seasonal H1N1 strains, A/New Caledonia/20/1999 (A/NC99) and A/South Dakota/6/2007 (A/SD07). Initial results showed that A/H1N1pdm09 strains had reduced multi-cycle infectivity in Madin-Darby Canine Kidney (MDCK) cells, compared to their pre-2009 counterparts. The A/BOL13 viral titre was found to be 2.65 log₁₀/mL lower when measured by multi-cycle 50% tissue culture infectious dose (TCID₅₀) assay compared to single-cycle fluorescent focus assay (FFA). By contrast, clinically effective A/NC99 titres differed by only 0.54 log₁₀/mL. In human alveolar (A549) cells, A/H1N1pdm09 strains replicated less than pre-2009 strains, with A/CA09 and A/BOL13 generating lower peak viral titres over 5 days. This phenotype was corroborated in physiologically relevant, primary human nasal epithelial cells (hNECs). Here, peak titres for pre-2009 strains A/NC99 and A/SD07 were 8.43 log₁₀ TCID₅₀/mL and 8.52 log₁₀ TCID₅₀/mL, respectively, versus 6.89 log₁₀ TCID₅₀/mL and 6.06 log₁₀ TCID₅₀/mL for A/H1N1pdm09 strains A/CA09 and A/BOL13. This confirmed a reduced ability of A/H1N1pdm09 strains to sustain replication in human respiratory cells. Using this information, H1N1 candidate A/Slovenia/2903/2015 (A/SLOV15) was characterised for replacement of A/BOL13 in the 2017/18 LAIV. A/SLOV15 produced comparable single and multi-cycle infectivity titres (Δ 0.16 log₁₀/mL) and reached a peak titre 1.23 log₁₀ TCID₅₀/mL higher than that of A/BOL13 in hNEC cultures. Taken together, these data suggest a reduction in sustained multi-cycle replication in human cells as a plausible root cause for reduced A/H1N1pdm09 VE.     

The magnitude of the acute phase protein response is attenuated by protein deficiency in rats.

We assessed the growth rate and changes in plasma albumin, total protein and alpha 2-macroglobulin concentrations (a major acute phase protein in rats) before and after a subcutaneous injection of turpentine (0.5 mg/kg body wt) in groups of rats receiving one of a series of protein-deficient diets (protein concentrations of 0.5, 1.5, 3.0, 4.5 or 6.0 g/100 g) or a diet containing an adequate level of protein (20 g/100 g) for maximal growth. Increasing protein deficiency in the different groups of animals reduced the basal albumin and total protein concentrations and attenuated the total protein and alpha 2-macroglobulin responses to turpentine. Increasing protein deficiency delayed the time taken for alpha 2-macroglobulin to reach peak concentrations post-injection and its return to basal concentrations. The turpentine-induced hypoalbuminemia was similar in all groups of animals (approximately 10 g/L depression) but restoration to values that were present before turpentine injection was increasingly delayed with increasing protein deficiency. The magnitude of the acute phase response (peak alpha 2-macroglobulin concentration) was found to be directly related to growth rate (r = 0.70, P less than 0.001). We concluded that protein deficiency can alter the pattern and magnitude of the acute phase responses in circulating protein concentrations to an extent that is dependent on the severity of protein deficiency.     

Maternal low-protein diet-induced delayed reflex ontogeny is attenuated by moderate physical training during gestation in rats

We evaluated the effects of moderate- to low-intensity physical training during gestation on reflex ontogeny in neonate rats whose mothers were undernourished. Virgin female Wistar rats were divided into four groups as follows: untrained (NT, n 7); trained (T, n 7); untrained with a low-protein diet (NT+LP, n 7); trained with a low-protein diet (T+LP, n 4). Trained rats were subjected to a protocol of moderate physical training on a treadmill over a period of 4 weeks (5 d/week and 60 min/d, at 65 % of VO?max). After confirming the pregnancy, the intensity and duration of the exercise were reduced. Low-protein groups were provided with an 8 % casein diet, and controls were provided with a 17 % casein diet. Their respective offspring were evaluated (during the 10th-17th days of postnatal life) in terms of physical feature maturation, somatic growth and reflex ontogeny. Pups born to mothers provided with the low-protein diet during gestation and lactation showed delayed physical feature and reflex maturation and a deficit in somatic growth when compared with controls. However, most of these deficiencies were attenuated in pups of undernourished mothers undergoing training. In conclusion, physical training during gestation attenuates the effects of perinatal undernutrition on some patterns of maturation in the central nervous system during development.     

Immunogenicity of an HIV-1 gag DNA vaccine carried by attenuated Shigella

The use of live attenuated invasive bacteria as a carrier for DNA-based vaccines has been reported recently. In this study, we used a Shigella flexneri serotype 2a rfbF mutant for immunization of a DNA vaccine coding for HIV-1 SF2 Gag. The recombinant bacterial vector delivered gag DNA to mammalian cells in vitro resulting in Gag protein expression, and was found to have a low level of pathogenicity among a number of Shigella cell spread defective mutants tested. Intranasal immunization of mice with live recombinant bacterial cells induced a gag-specific cellular immune response similar to that seen with i.m. injection of naked DNA. Importantly, a strong boosting effect was observed in mice primed with DNA, suggesting utility of bacterial vectors in prime-boost vaccination regimens.