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Biomedical subjects

Marc Humbert

Publications and source records attributed to Marc Humbert.

At least 55 records · Page 3Linked to original sources
PubMed2004

Bosentan for the treatment of human immunodeficiency virus-associated pulmonary arterial hypertension.

Clinical studies have shown the importance of endothelin as a pathogenic mediator in pulmonary arterial hypertension (PAH). We describe the effects of bosentan, an oral dual endothelin receptor antagonist, in patients with PAH associated with human immunodeficiency virus (HIV) infection. In this prospective study, 16 patients with PAH associated with HIV infection in stable condition received bosentan for 16 weeks. Efficacy endpoints included exercise capacity, cardiopulmonary hemodynamics, Doppler echocardiography, New York Heart Association functional class, and quality of life (SF-36 and EQ-5D). Safety was assessed by laboratory tests, vital signs, and adverse events. Improvements were observed from baseline to Week 16 in all efficacy parameters: 6-minute walk distance (+91 +/- 60 m, p < 0.001), New York Heart Association class (14 patients improved), hemodynamics (cardiac index: +0.9 +/- 0.7 L/minute/m(2), p < 0.001), Doppler echocardiographic variables, and quality of life. During the study, no patient died and none required epoprostenol treatment. Hepatic tolerability was similar to that reported in patients with PAH. Bosentan had no negative impact on control of HIV infection. Although limited by uncontrolled design, small sample size and short duration, this study suggests that bosentan may benefit patients with PAH associated with HIV infection, and that endothelin is an important pathogenic mediator in this disease.

Adult↗
PubMed2004

Cellular and molecular pathobiology of pulmonary arterial hypertension.

Pulmonary arterial hypertension (PAH) has a multifactorial pathobiology. Vasoconstriction, remodeling of the pulmonary vessel wall, and thrombosis contribute to increased pulmonary vascular resistance in PAH. The process of pulmonary vascular remodeling involves all layers of the vessel wall and is complicated by cellular heterogeneity within each compartment of the pulmonary arterial wall. Indeed, each cell type (endothelial, smooth muscle, and fibroblast), as well as inflammatory cells and platelets, may play a significant role in PAH. Pulmonary vasoconstriction is believed to be an early component of the pulmonary hypertensive process. Excessive vasoconstriction has been related to abnormal function or expression of potassium channels and to endothelial dysfunction. Endothelial dysfunction leads to chronically impaired production of vasodilators such as nitric oxide and prostacyclin along with overexpression of vasoconstrictors such as endothelin (ET)-1. Many of these abnormalities not only elevate vascular tone and promote vascular remodeling but also represent logical pharmacological targets. Recent genetic and pathophysiologic studies have emphasized the relevance of several mediators in this condition, including prostacyclin, nitric oxide, ET-1, angiopoietin-1, serotonin, cytokines, chemokines, and members of the transforming-growth-factor-beta superfamily. Disordered proteolysis of the extracellular matrix is also evident in PAH. Future studies are required to find which if any of these abnormalities initiates PAH and which ones are best targeted to cure the disease.

Endothelium, Vascular↗
PubMed2004

Pathologic assessment of vasculopathies in pulmonary hypertension.

Pulmonary arterial hypertension (PAH) includes various forms of pulmonary hypertension of different etiology but similar clinical presentation and functional derangement. Histopathological vascular changes in all forms of PAH are qualitatively similar but with quantitative differences in the distribution and prevalence of pathological changes in various portions of the pulmonary vascular bed. The documentation of these topographic variations in the response of the pulmonary vasculature to injury may be important to understand the pathogenesis of the various subsets of PAH. To standardize the precise histopathological documentation of the pulmonary vasculopathy in PAH we propose a histopathological classification that includes both the predominant segment of the pulmonary vasculature affected and the possible coexistence of pathological changes in other vascular segments.

Humans↗
PubMed2004

Serotonin-induced smooth muscle hyperplasia in various forms of human pulmonary hypertension.

Hyperplasia of pulmonary artery smooth muscle cells (PA-SMCs) is a hallmark pathological feature of pulmonary hypertension (PH). Serotonin (5-HT) is involved in the hyperplasia through its interactions with specific receptors and internalization by a specific plasma membrane transporter. We investigated the expression and role of the 5-HT transporter (5-HTT) and 5-HT1B, 5-HT2A, and 5-HT2B receptors in lungs and isolated PA-SMCs from patients with primary PH (n=14), pulmonary veno-occlusive disease (n=4), or secondary PH (SPH, n=8) and nonpulmonary hypertensive control subjects. Whereas strong immunostaining for the three receptor types and 5-HTT was seen in remodeled pulmonary vessels from patients in all PH categories, only 5-HTT expression was increased in lungs and cultured PA-SMCs from patients versus controls. The increased growth response of PA-SMCs from patients with primary PH, pulmonary veno-occlusive disease, or SPH to 5-HT or serum was entirely attributable to 5-HTT overexpression, because 5-HTT inhibitors but not 5-HT receptor antagonists abolished 5-HT mitogenic activity and reduced the serum-induced growth response to similar levels in patients as in controls. The L-allelic variant of the 5-HTT gene promoter, which is associated with 5-HTT overexpression, was present homozygously in 14 of 25 (56%) lung transplantation patients with SPH but in only 27% of controls. Polymorphism of the 5-HTT gene promoter was only partly responsible for the increased 5-HTT expression in PH, because PA-SMCs from patients exhibited higher 5-HTT levels than same-genotype cells from controls and no additional promoter sequence alterations were found. We conclude that 5-HTT overexpression is a common pathogenic mechanism in various forms of PH.

Adolescent↗
PubMed2004

[Pulmonary arterial hypertension].

Pulmonary arterial hypertension (PAH) is a rare condition characterised by elevated pulmonary arterial resistance leading to right heart failure. PAH can be sporadic (idiopathic PAH, or primary pulmonary hypertension), familial (caused by germline BMPR2 mutations, a type II member of the TGFbeta receptor superfamily), or related to other conditions including connective tissue disease, congenital heart disease, human immunodeficiency virus infection, portal hypertension, appetite suppressant exposure... Idiopathic PAH has a prevalence of 2 per million per year in France. The lack of specificity of PAH symptoms (mostly dyspnea) presumably lead to underdiagnosis of this condition. Echocardiography is the investigation of choice for non-invasive screening. Measurement of hemodynamic parameters during right-heart catheterism is mandatory to establish the diagnosis (mean pulmonary artery pressure >25 mmHg and pulmonary artery wedge pressure <12 mmHg). Acute pulmonary vasodilator testing should be performed with nitric oxide or prostacyclin during right-heart catheterization. Recent advances in the management of PAH including continuous intravenous prostacyclin infusion and endothelin receptor antagonists have improved markedly the patients' prognosis. Novel treatments such as inhaled iloprost and type 5 phosphodiesterase inhibitors have to be further evaluated in this setting. Lung transplantation is the last option for patients deteriorating despite medical treatment.

Cardiac Catheterization↗
PubMed2004

New formula for predicting mean pulmonary artery pressure using systolic pulmonary artery pressure.

STUDY OBJECTIVES: Mean pulmonary artery pressure (MPAP) and systolic pulmonary artery pressure (SPAP) are used interchangeably to define pulmonary hypertension (PH). We tested the hypothesis that the measurement of MPAP and SPAP is redundant in resting humans over a wide pressure range. DESIGN: Prospective, observational study. SETTING: Catheterization laboratory in a university hospital. PATIENTS: This study involved 31 patients, as follows: primary PH, nine patients; chronic pulmonary thromboembolism, seven patients; venous PH, six patients; and control subjects with normal pulmonary artery pressure, nine patients. INTERVENTIONS: None. MEASUREMENTS AND RESULTS: High-fidelity pulmonary artery pressures were obtained when patients were at rest. Over the wide MPAP range that was under study (10 to 78 mm Hg), MPAP and SPAP were strongly related (r(2) = 0.98). Regression analysis performed on the first 16 subjects (test sample) allowed us to propose a formula (MPAP = 0.61 SPAP + 2 mm Hg), the accuracy of which was confirmed in the remaining 15 subjects (validation sample bias, 0 +/- 2 mm Hg). If PH was defined by an SPAP in excess of 30 or 40 mm Hg, this corresponded to an MPAP in excess of 20 or 26 mm Hg. If PH was defined by an MPAP of > 25 mm Hg, this corresponded to an SPAP of > 38 mm Hg. CONCLUSIONS: In resting humans, MPAP can be accurately predicted from SPAP over a wide pressure range. The new formula may help to refine the threshold pressure values used in the diagnosis of PH. Further studies are needed to test the hypothesis that our formula may allow the noninvasive prediction of MPAP from Doppler-derived SPAP values.

Blood Pressure Determination↗
PubMed2004

Ciclesonide: a novel inhaled corticosteroid.

Inhaled corticosteroids (ICS) are a mainstay in the treatment of persistent asthma, a disease with increasing prevalence and cost implications worldwide. However, long-term use of currently available ICS is associated with local adverse effects that include hoarseness and oral candidiasis. In addition, systemic adverse effects including adrenal cortical suppression, osteoporosis, growth retardation, cataracts and glaucoma are also present. Ciclesonide is a novel ICS, which promises to provide airway anti-inflammatory efficacy that is comparable with that of the available ICS in addition to reducing the risk for local and systemic adverse events. Ciclesonide is an agent that is inactive until it reaches its target site, the lung, where it is converted to its active metabolite desisobutyryl-ciclesonide. In addition, other favourable pharmacokinetic and pharmacodynamic characteristics such as high protein binding, low oral bioavailability and rapid clearance contribute to the efficacy and improved systemic safety profile of ciclesonide.

Administration, Inhalation↗
PubMed2004

Pulmonary hypertension: CT of the chest in pulmonary venoocclusive disease.

OBJECTIVE: Pulmonary venoocclusive disease is a rare cause of pulmonary hypertension that is often difficult to distinguish from severe primary pulmonary hypertension. Unfortunately, medical treatment of primary pulmonary hypertension with prostacyclin can be fatal in patients with venoocclusive disease, and an early pretreatment diagnosis of this uncommon condition is critical. The aim of our study was to evaluate this disease noninvasively using CT of the chest. MATERIALS AND METHODS: We reviewed cross-referenced records from 1996 to 2001 in our departments of radiology and pathology and identified 15 patients with initial pretreatment CT scans who had pathologically confirmed pulmonary venoocclusive disease. Their CT scans were compared with the CT scans of 15 consecutive patients with pathologically confirmed primary pulmonary hypertension. All patients had undergone a postmortem or posttransplantation examination. RESULTS: Ground-glass opacities were significantly more frequent in pulmonary venoocclusive disease (p = 0.003); the opacities were abundant with random zonal predominance and preferentially centrilobular distribution (p = 0.03). Subpleural septal lines and adenopathy were also significantly more frequent (p < 0.0001). CONCLUSION: On the initial pretreatment chest CT scan, the presence of ground-glass opacities (particularly with a centrilobular distribution), septal lines, and adenopathy are indicative of pulmonary venoocclusive disease in patients displaying pulmonary hypertension. Caution should be exercised before vasodilator therapy is initiated in the patients whose scans show such radiologic abnormalities.

Adult↗
PubMed2003

Prognostic factors for survival in human immunodeficiency virus-associated pulmonary arterial hypertension.

We report a large monocentric case series of 82 patients with human immunodeficiency virus-associated pulmonary arterial hypertension (PAH). No germline mutations of the PPH1 gene (bone morphogenetic protein receptor-II) were found in any of the 19 patients tested. PAH was the direct cause of death in 72% of cases. Survival rates of the overall population at 1, 2, and 3 years were 73, 60, and 47%, respectively. Survival was significantly poorer in patients in New York Heart Association functional class III-IV at the time of diagnosis, as compared with those in functional class I-II with respective rates of 60, 45, and 28% versus 100, 90, 84% at 1, 2, and 3 years (p < 0.0001). Subsequently, we analyzed prognostic factors in patients in functional class III-IV. Univariate analysis indicated that CD4 lymphocyte count of more than 212 cells mm(-3), the use of combination antiretroviral therapy (CART), and epoprostenol infusion were related with a better survival. On multivariate analysis only CD4 lymphocyte count was an independent predictor of survival, presumably because CART and epoprostenol infusion were strongly linked in our patient population. These results suggest that patients with severe human immunodeficiency virus-associated PAH should be considered for long-term epoprostenol infusion in association with CART.

Adult↗
PubMed2003

The CX3C chemokine fractalkine in allergic asthma and rhinitis.

BACKGROUND: Unlike other chemokines, fractalkine is expressed as a membrane-bound form, mainly on endothelial and epithelial cells, and can be shed as a soluble chemotactic form. Fractalkine can capture leukocytes expressing its receptor (CX(3)CR(1)), including T lymphocytes, rapidly and firmly in an integrin-independent manner. Because of its dual activity, fractalkine plays a major role in the transendothelial and transepithelial migration of leukocytes during inflammation. OBJECTIVE: We sought to study the fractalkine-CX(3)CR(1) axis in patients with allergic airways diseases. METHODS: Plasma fractalkine levels were measured by means of ELISA in 19 control subjects and 55 patients with symptomatic allergic rhinitis, asthma, or both, and CX(3)CR(1) function was studied by using triple-color flow cytometry in circulating T-lymphocyte subpopulations. Segmental allergen challenge was performed in 16 allergic asthmatic patients to analyze fractalkine expression and inflammatory cell recruitment in bronchoalveolar lavage fluid and bronchial biopsy specimens. RESULTS: Compared with control subjects, patients with symptomatic allergic rhinitis and asthmatic patients had increased circulating fractalkine levels, and CX(3)CR(1) function was upregulated in circulating CD4(+) T lymphocytes. Twenty-four hours after segmental allergen challenge, bronchoalveolar lavage fluid soluble fractalkine concentrations increased and correlated with the total number of recruited cells. Bronchial epithelial and endothelial cells expressed high levels of the membrane-bound form of fractalkine before and after challenge. CONCLUSION: Allergic asthma and rhinitis are associated with systemic and bronchial upregulation of the chemotactic axis fractalkine-CX(3)CR(1). This might contribute to the rapid recruitment of circulating CD4(+) T lymphocytes in the airways after allergen stimulation.

Adolescent↗
PubMed2003

An extreme consequence of splenectomy in dehydrated hereditary stomatocytosis: gradual thrombo-embolic pulmonary hypertension and lung-heart transplantation.

Dehydrated hereditary stomatocytosis (DHS) belongs to the heterogeneous class of hemolytic anemias with leaky red cell membranes. Splenectomy is a highly deleterious treatment, because it favors, with virtually no exception, the occurrence of thromboembolic disease. We describe here the extreme case of a patient with DHS and an associated sickle cell trait. Splenectomy was carried out due to a splenic infarction that occurred during an airplane journey. About 12 years later, the patient noticed an exertional dyspnea, which gradually worsened to such a degree that she became severely incapacitated within 5 years. Eventually, the patient developed a cor pulmonale associated with chronic thromboembolic pulmonary hypertension (CTEPH) and successfully underwent a heart-lung transplant operation. This case ranks as one of the most severe examples ever recorded of the effect that splenectomy may have in DHS patients. Nonetheless, it represents the first case to receive a heart-lung transplant.

Adult↗
PubMed2003

Pathology and aspects of pathogenesis in pulmonary arterial hypertension.

Pulmonary Arterial Hypertension (PAH) is a term which has been recently defined at the WHO-meeting in Evian and includes Primary Pulmonary Hypertension (PPH), as well as PAH related to specific pathological conditions. The poor prognosis of the disease seems to be related to a peculiar pathological anatomy, consisting of characteristic lesions of small, muscular pulmonary arteries. In addition to common hypertrophy of the tunica media, other proliferative lesions such as intimal thickening or plexiform lesions are summarized under the term of plexogenic arteriopathy. Moreover, in situ thrombosis and rarely isolated pulmonary arteritis can be observed in lungs of patients displaying PAH. Different pathomechanisms explaining these morphological changes of pulmonary vasculature have been discussed in the past, including endothelial and thrombocytic dysfunction, deregulated vasoconstriction, coagulation abnormalities, or cancer-like growth. Furthermore, latest studies on the importance of inflammatory mediators, so-called chemokines, in the lungs of PAH patients have brought a possible inflammatory component of the disease into consideration. Finally, recent identification of responsible gene mutations in subgroups of patients, as well as latest developments in genetic screening have shed some light into the modus of inheritance. Nevertheless, the role and impact of these different pathomechanisms have yet to be better defined.

Cardiac Catheterization↗
PubMed2002

Long-term intravenous epoprostenol infusion in primary pulmonary hypertension: prognostic factors and survival.

OBJECTIVES: We sought to determine the factors associated with long-term survival in patients with primary pulmonary hypertension (PPH) treated with continuous epoprostenol infusion. BACKGROUND: Epoprostenol improves survival in patients with PPH in New York Heart Association (NYHA) functional class III or IV. However, some patients do not benefit from epoprostenol and must be considered for lung transplantation. The best timing for listing these patients on a lung transplantation program is currently unknown. METHODS: Between December 1992 and January 2001, 178 patients with PPH in NYHA functional class III or IV were treated with epoprostenol. The 6-min walk test (WT) and right-sided heart catheterization were performed at baseline, after three months on epoprostenol and thereafter once a year. RESULTS: Overall survival rates at one, two, three, and five years were 85%, 70%, 63%, and 55%, respectively. On univariate analysis, the baseline variables associated with a poor outcome were a history of right-sided heart failure, NYHA functional class IV, 6-min WT or=12 mm Hg, and mean pulmonary artery pressure <65 mm Hg. On multivariate analysis, including both baseline variables and those measured after three months on epoprostenol, a history of right-sided heart failure, persistence of NYHA functional class III or IV at three months, and the absence of a fall in total pulmonary resistance of >30%, relative to baseline, were associated with poor survival. CONCLUSIONS: Survival of patients with PPH treated with epoprostenol depends on the severity at baseline, as well as the three-month response to therapy. These findings suggest that lung transplantation should be considered in a subset of patients who remain in NYHA functional class III or IV or in those who cannot achieve a significant hemodynamic improvement after three months of epoprostenol therapy, or both.

Adult↗
PubMed2002

Prevention of gram-negative translocation reduces the severity of hepatopulmonary syndrome.

Hepatopulmonary syndrome (HPS) is characterized by intrapulmonary vascular dilatations and an increased alveoloarterial oxygen difference (AaPO(2)). These abnormalities are related to augmented pulmonary nitric oxide (NO) production, dependent primarily on increases in the expression and activity of inducible NO-synthase (iNOS) within pulmonary intravascular macrophages and, to a lesser extent, of endothelial NOS (eNOS). Production of iNOS by pulmonary intravascular macrophages might be related to translocated gut bacteria present in the pulmonary circulation. To test this hypothesis, we determined whether macrophage sequestration, lung iNOS expression and activity, and HPS severity were decreased after norfloxacin was given for 5 weeks to prevent Gram-negative bacterial translocation in rats with common bile duct ligation-induced cirrhosis. Norfloxacin decreased the incidence of Gram-negative translocation from 70 to 0% and the percentage of pulmonary microvessels containing more than 10 macrophages from 52 +/- 7 to 21 +/- 8% (p < 0.01). AaPO(2) and cerebral uptake of intravenous (99m)Tc-labeled albumin macroaggregates (reflecting intrapulmonary vascular dilatations) were intermediate to those of untreated cirrhotic and sham-operated rats. The activity and expression of lung iNOS, but not eNOS, were reduced to normal. Norfloxacin may reduce HPS severity by inhibiting Gram-negative bacterial translocation, thereby decreasing NO production by pulmonary intravascular macrophages. Bacterial translocation may be the key to the pathogenesis of HPS.

Animals↗
PubMed2002

Severe pulmonary arterial hypertension in type 1 glycogen storage disease.

Pulmonary arterial hypertension is characterised by the presence of pulmonary hypertension (mean pulmonary artery pressure >25 mmHg at rest or >30 mmHg during exercise ) and normal pulmonary wedge pressure (<12 mmHg). Several risk factors for pulmonary arterial hypertension have been described. In the absence of any factor or condition suspected to play a causal or facilitating role in the process, pulmonary hypertension is "unexplained" (primary pulmonary hypertension, PPH). PPH is a rare condition, with an estimated incidence of 2 per million people. Recent genetic studies have identified mutations in the bone morphogenetic protein receptor-II (BMPR-II) gene, a receptor member of the transforming growth factor-beta family, in a majority of familial cases of PPH. Interestingly, 25% of patients displaying sporadic PPH may also have mutations in the BMPR-II gene, emphasising the relevance of genetic susceptibility for this severe condition. Other molecular and biochemical processes behind the complex vascular changes associated with pulmonary arterial hypertension are currently investigated. Type 1a glycogen storage disease caused by a deficiency of glucose-6-phosphatase has an estimated incidence of 1 per 100000 with a few reported cases of unexplained severe pulmonary hypertension. The occurrence of pulmonary arterial hypertension in type 1a glycogen storage disease could be due to vasoconstrictive amines such as serotonin, a pulmonary vasoconstrictor and growth factor for vascular smooth muscle cells stored in platelets.

Adolescent↗
PubMed2002

CX(3)C chemokine fractalkine in pulmonary arterial hypertension.

Perivascular infiltrates composed of macrophages and lymphocytes have been described in lung biopsies of patients displaying pulmonary arterial hypertension (PAH), suggesting that circulating inflammatory cells can be recruited in affected vessels. CX(3)C chemokine fractalkine is produced by endothelial cells and promotes leukocyte recruitment, but unlike other chemokines, it can capture leukocytes rapidly and firmly in an integrin-independent manner under high blood flow. We therefore hypothesized that fractalkine may contribute to pulmonary inflammatory cell recruitment in PAH. Expression and function of the fractalkine receptor (CX(3)CR1) were studied by use of triple-color flow cytometry on circulating T-lymphocyte subpopulations in freshly isolated peripheral blood mononuclear cells from control subjects and patients with PAH. Plasma-soluble fractalkine concentrations were measured by enzyme-linked immunosorbent assay. Finally, fractalkine mRNA and protein expression were analyzed in lung samples by reverse transcriptase-polymerase chain reaction or in situ hybridization and immunohistochemistry, respectively. In patients with PAH, CX(3)CR1 expression and function are upregulated in circulating T-lymphocytes, mostly of the CD4+ subset, and plasma soluble fractalkine concentrations are elevated, as compared with control subjects. Fractalkine mRNA and protein product are expressed in pulmonary artery endothelial cells. We conclude that inflammatory mechanisms involving chemokine fractalkine and its receptor CX(3)CR1 may have a role in the natural history of PAH.

Adult↗