Project description:Idiopathic pulmonary arterial hypertension (IPAH) is a rare and progressive disease. Several processes are believed to lead to the fatal progressive pulmonary arterial narrowing seen in IPAH including vasoconstriction, cellular proliferation inflammation, vascular remodeling, abnormalities in the lung matrix, and in situ thrombosis. Nitric oxide (NO) produced by NO synthases (NOS) is a potent vasodilator and plays important roles in many other processes including platelet function. Reduced NO levels in patients with IPAH are known to contribute to the development of pulmonary hypertension and its complications. Platelet defects have been implied in IPAH, but original research supporting this hypothesis has been limited. Normal platelets are known to have NOS activity, but little is known about NOS expression and NO production by platelets in patients with IPAH. Here we characterized the phenotype of the platelets in IPAH and show a defect in their ability to be activated in vitro by thrombin receptor activating protein but not adenosine diphosphate. We also show that endothelial NOS (eNOS) levels in these platelets are reduced and demonstrate that NO is an important regulator of platelet function. Thus reduced levels of eNOS in platelets could impact their ability to regulate their own function appropriately.
Project description:Idiopathic Pulmonary arterial hypertension (IPAH) is a debilitating disease associated with very poor prognosis. The disease is characterised by endothelial dysfunction, smooth muscle proliferation and insitu thrombosis in the pulmonary artery, eventually leading to right ventricular failure. Two of the key endothelial mediators implicated in the pathogenesis of IPAH are endothelin-1 (EDN1) and nitric oxide (NO). EDN1 is a potent endogenous vasoconstrictor whereas NO is a vasodilator. In the present study screening of the EDN1 gene (EDN1) and NOS3 polymorphisms was taken up, to evaluate their association with IPAH. A significant association of EDN1 3A/4A polymorphism (+138 A; rs10478694) (OR-3.485; CI-1.254, 9.999; p=0.013) and EDN1 Lys198Asn polymorphism (G/T, rs5370) (OR-3.378, CI-1.104, 10.582; p=0.03) with IPAH was observed. Our results indicate that EDN1 polymorphisms in interaction with other genetic markers may play a significant role in individual's susceptibility to the disease and its clinical progression.
Project description:IntroductionSevere chronic obstructive pulmonary disease (COPD) is often associated with secondary pulmonary hypertension (PH), which worsens prognosis. PH can be lowered by oxygen, but also by inhaled nitric oxide (NO), which has the potential to improve the health status of these patients. NO is an important mediator in vascular reactions in the pulmonary circulation. Oral compounds can act through NO-mediated pathways, but delivering pulsed inhaled NO (iNO) directly to the airways and pulmonary vasculature could equally benefit patients. Therefore, a proof-of-concept study was performed to quantify pulmonary blood vessel caliber changes after iNO administration using computed tomography (CT)-based functional respiratory imaging (FRI).MethodsSix patients with secondary PH due to COPD received "pulsed" iNO in combination with oxygen for 20 minutes via a nasal cannula. Patients underwent a high-resolution CT scan with contrast before and after iNO. Using FRI, changes in volumes of blood vessels and associated lobes were quantified. Oxygen saturation and blood pressure were monitored and patients were asked about their subjective feelings.ResultsPulmonary blood vessel volume increased by 7.06%±5.37% after iNO. A strong correlation (Ω(2) 0=0.32, P=0.002) was obtained between ventilation and observed vasodilation, suggesting that using the pulsed system, iNO is directed toward the ventilated zones, which consequently experience more vasodilation. Patients did not develop oxygen desaturation, remained normotensive, and perceived an improvement in their dyspnea sensation.ConclusionInhalation of pulsed NO with oxygen causes vasodilation in the pulmonary circulation of COPD patients, mainly in the well-ventilated areas. A high degree of heterogeneity was found in the level of vasodilation. Patients tend to feel better after the treatment. Chronic use trials are warranted.
Project description:BackgroundThe aim of this study was to examine the action of inhaled nitric oxide in the patients with pulmonary hypertension administered with a face mask before anesthesia induction.MethodsTen adult patients scheduled for heart surgery with sternotomy were included in this prospective, interventional, single centre study. The inclusion criteria were patients scheduled for heart surgery with sternotomy with cardiopulmonary bypass (CPB), aged >18 years which presents a pulmonary hypertension (PH) (class 2 or 3 according to the Dana Point classification) with systolic pulmonary arterial pressure (PAPS) >40 mmHg diagnosed by preoperative right cardiac catheterization or by transthoracic echocardiography. The exclusion criteria were: heart transplant, PH of type 1, 4, 5, according to the Dana Point classification, methemoglobin reductase deficit, incapacity to understand the protocol and sign the consent.ResultsThe administration of iNO decrease pulmonary hypertension (P < 0,001 compared to room air; P = 0,01 compared to pure oxygen administration). The iNO administration did not improve arterial blood oxygenation. The hyperoxia, decrease the cardiac index even with right ventricular post charge decrease. The increased blood oxygenation content cause systemic vascular vasoconstriction and decrease the peripheral oxygen extraction showed with VO2 linear increase (P < 0,001).ConclusionsThe administration of inhaled nitric oxide with a face mask before anaesthesia induction is safe and effective method to reduce pulmonary hypertension. The oxygen and hyperoxia influences the systemic vascular resistance and peripheral oxygen consumption.
Project description:PurposeInhaled nitric oxide (iNO) selectively vasodilates the pulmonary circulation but the effects are sometimes insufficient. Available intravenous (iv) substances are non-selective and cause systemic side effects. The pulmonary and systemic effects of iNO and an iv mono-organic nitrite (PDNO) were compared in porcine models of acute pulmonary hypertension.MethodsIn anesthetized piglets, dose-response experiments of iv PDNO at normal pulmonary arterial pressure (n=10) were executed. Dose-response experiments of iv PDNO (n=6) and iNO (n=7) were performed during pharmacologically induced pulmonary hypertension (U46619 iv). The effects of iv PDNO and iNO were also explored in 5 mins of hypoxia-induced increase in pulmonary pressure (n=2-4).ResultsPDNO (15, 30, 45 and 60 nmol NO kg-1 min-1 iv) and iNO (5, 10, 20 and 40 ppm which corresponded to 56, 112, 227, 449 nmol NO kg-1 min-1, respectively) significantly decreased the U46619-increased mean pulmonary arterial pressure (MPAP) and pulmonary vascular resistance (PVR) to a similar degree without significant decreases in mean arterial pressure (MAP) or systemic vascular resistance (SVR). iNO caused increased levels of methemoglobin. At an equivalent delivered NO quantity (iNO 5 ppm and PDNO 45 nmol kg-1 min-1 iv), PDNO decreased PVR and SVR significantly more than iNO. Both drugs counteracted hypoxia-induced pulmonary vasoconstriction and they decreased the ratio of PVR and SVR in both settings.ConclusionIntravenous PDNO was a more potent pulmonary vasodilator than iNO in pulmonary hypertension, with no severe side effects. Hence, this study supports the potential of iv PDNO in the treatment of acute pulmonary hypertension.
Project description:Pulmonary vascular arterial remodeling is an integral and well-understood component of pulmonary hypertension (PH). In contrast, morphological alterations of pulmonary veins in PH are scarcely described. Explanted lungs (n = 101) from transplant recipients with advanced chronic obstructive pulmonary disease (COPD) and idiopathic pulmonary arterial hypertension (IPAH) were analyzed for venous vascular involvement according to a pre-specified, semi-quantitative grading scheme, which categorizes the intensity of venous remodeling in three groups of incremental severity: venous hypertensive (VH) grade 0 = characterized by an absence of venous vascular remodeling; VH grade 1 = defined by a dominance of either arterialization or intimal fibrosis; and VH grade 2 = a substantial composite of arterialization and intimal fibrosis. Patients were grouped according to clinical and hemodynamic characteristics in three groups: COPD non-PH, COPD-PH, and IPAH, respectively. Histological specimens were examined by a cardiovascular pathologist blinded to clinical and hemodynamic data. Pathological alterations of pulmonary veins were present in all hemodynamic groups, with the following incidences of VH grade 0/1/2: 34/66/0% in COPD non-PH; 19/71/10% in COPD-PH; and 11/61/28% in IPAH. In COPD, explorative correlation analysis of venous remodeling suggested a modest positive correlation with systolic and mean pulmonary artery pressure ( P = 0.032, respectively) and an inverse modest correlation with diffusion capacity for carbon monoxide ( P = 0.027). In addition, venous remodeling correlated positively with the degree of arterial remodeling ( P = 0.014). In COPD-PH and IPAH, advanced forms of pulmonary venous remodeling are present, emphasizing that the disease is not exclusively restricted to arterial lesions. In addition, venous remodeling may be related to the hemodynamic severity, but more rigorous analysis is required to clearly define potential relationships.
Project description:Vasoreactivity testing with inhaled NO is recommended for pulmonary arterial hypertension (PAH) because of its therapeutic and prognostic value. Sildenafil has acute pulmonary vasodilating properties, but its diagnostic and prognostic impact in PAH is unknown. Our objective was to compare acute vasodilating responses to sildenafil and those to NO during right heart catheterization and also their prognostic values in patients with PAH. Ninety-nine patients with idiopathic PAH and 99 with associated PAH underwent vasoreactivity testing with NO and sildenafil. Only mild adverse effects of sildenafil, in the form of hypotension, were observed, at a rate of 4.5%. The acute responder rate was 8.1% for NO and 11.6% for sildenafil. The NO-induced response in mean pulmonary arterial pressure and cardiac output correlated with the response to sildenafil. Thirteen patients were long-term responders to calcium channel blockers (CCBs), and 3 of them were correctly identified by acute vasoreactivity test with both drugs. The specificity of the vasoreactivity test for identifying long-term CCB responders was 88.9% for NO and 85.1% for sildenafil testing. A trend toward better survival was found in sildenafil and NO responders, compared with nonresponders. Use of sildenafil for vasoreactivity testing is safe. Sildenafil may be useful as alternative vasoreactivity-testing agent, identifying the same number of long-term CCB responders as NO. However, NO seems to be a more ideal testing drug because of its pharmacologic properties. Moreover, sildenafil vasoreactivity testing might contribute to an improved estimate of prognosis among patients with PAH.
Project description:One of the major obstacles hindering the clinical development of a cell-free, hemoglobin-based oxygen carrier (HBOC) is systemic vasoconstriction.Experiments were performed in healthy mice and lambs by infusion of either murine tetrameric hemoglobin (0.48 g/kg) or glutaraldehyde-polymerized bovine hemoglobin (HBOC-201, 1.44 g/kg). We observed that intravenous infusion of either murine tetrameric hemoglobin or HBOC-201 induced prolonged systemic vasoconstriction in wild-type mice but not in mice congenitally deficient in endothelial nitric oxide (NO) synthase (NOS3). Treatment of wild-type mice by breathing NO at 80 ppm in air for 15 or 60 minutes or with 200 ppm NO for 7 minutes prevented the systemic hypertension induced by subsequent intravenous administration of murine tetrameric hemoglobin or HBOC-201 and did not result in conversion of plasma hemoglobin to methemoglobin. Intravenous administration of sodium nitrite (48 nmol) 5 minutes before infusion of murine tetrameric hemoglobin also prevented the development of systemic hypertension. In awake lambs, breathing NO at 80 ppm for 1 hour prevented the systemic hypertension caused by subsequent infusion of HBOC-201.These findings demonstrate that HBOC can cause systemic vasoconstriction by scavenging NO produced by NOS3. Moreover, in 2 species, inhaled NO administered before the intravenous infusion of HBOC can prevent systemic vasoconstriction without causing methemoglobinemia.
Project description:AimsWe have previously reported that nano-selenium quantum dots (SeQDs) prevented endothelial dysfunction in atherosclerosis. This study is to investigate whether amorphous SeQDs (A-SeQDs) increase endogenous tetrahydrobiopterin biosynthesis to alleviate pulmonary arterial hypertension.ResultsBoth A-SeQDs and C-SeQDs were stable under physiological conditions, while the size of A-SeQDs was smaller than C-SeQDs by high resolution-transmission electron microscopy scanning. In monocrotaline-injected mice, oral administration of A-SeQDs was more effective to decrease pulmonary arterial pressure, compared to C-SeQDs and organic selenium. Further, A-SeQDs increased both nitric oxide productions and intracellular BH4 levels, upregulated dihydrofolate reductase activity in lungs, and improved pulmonary arterial remodeling. Gene deletion of dihydrofolate reductase abolished these effects produced by A-SeQDs in mice. Finally, the blood levels of tetrahydrobiopterin and selenium were decreased in patients with pulmonary arterial hypertension.ConclusionA-SeQDs increase intracellular tetrahydrobiopterin to prevent pulmonary arterial hypertension through recoupling endothelial nitric oxide synthase.MethodsTwo polymorphs of SeQDs and A-SeQDs, and a crystalline form of SeQDs (C-SeQDs) were prepared through self-redox decomposition of selenosulfate precursor. Mice were injected with monocrotaline to induce pulmonary arterial hypertension in vivo. Pulmonary arterial pressure was measured.
Project description:BackgroundTo elucidate further the pathogenesis of sporadic, idiopathic pulmonary arterial hypertension (IPAH) and identify potential therapeutic avenues, differential gene expression in IPAH was examined by suppression subtractive hybridisation (SSH).MethodsPeripheral lung samples were obtained immediately after removal from patients undergoing lung transplant for IPAH without familial disease, and control tissues consisted of similarly sampled pieces of donor lungs not utilised during transplantation. Pools of lung mRNA from IPAH cases containing plexiform lesions and normal donor lungs were used to generate the tester and driver cDNA libraries, respectively. A subtracted IPAH cDNA library was made by SSH. Clones isolated from this subtracted library were examined for up regulated expression in IPAH using dot blot arrays of positive colony PCR products using both pooled cDNA libraries as probes. Clones verified as being upregulated were sequenced. For two genes the increase in expression was verified by northern blotting and data analysed using Student's unpaired two-tailed t-test.ResultsWe present preliminary findings concerning candidate genes upregulated in IPAH. Twenty-seven upregulated genes were identified out of 192 clones examined. Upregulation in individual cases of IPAH was shown by northern blot for tissue inhibitor of metalloproteinase-3 and decorin (P < 0.01) compared with the housekeeping gene glyceraldehydes-3-phosphate dehydrogenase.ConclusionFour of the up regulated genes, magic roundabout, hevin, thrombomodulin and sucrose non-fermenting protein-related kinase-1 are expressed specifically by endothelial cells and one, muscleblind-1, by muscle cells, suggesting that they may be associated with plexiform lesions and hypertrophic arterial wall remodelling, respectively.