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Biomedical subjects

Marc Humbert

Publications and source records attributed to Marc Humbert.

At least 37 records · Page 2Linked to original sources
PubMed2006

Medical therapies for chronic thromboembolic pulmonary hypertension: an evolving treatment paradigm.

Pulmonary endarterectomy (PEA) is recommended as the treatment of choice for eligible patients with chronic thromboembolic pulmonary hypertension (CTEPH). However, only a proportion of patients fulfill the criteria for surgical intervention. In addition, operated patients with CTEPH may experience a gradual hemodynamic and symptomatic decline related to a secondary hypertensive arteriopathy in the small precapillary pulmonary vessels. It has also been questioned what can be done to reduce risks from PEA surgery to improve outcome in "high risk" patients with CTEPH with substantial impairment of pulmonary hemodynamics before surgery. Such patients may benefit from preoperative reduction of pulmonary vascular resistance by means of medical therapy. Conventional medical treatments, such as anticoagulation, diuretics, digitalis, and chronic oxygen therapy, show low efficacy in the treatment of CTEPH as they do not affect underlying disease processes. Over the last decade, several novel therapies have been developed for pulmonary arterial hypertension (PAH), including prostacyclin analogs (epoprostenol, beraprost, iloprost), endothelin receptor antagonists (bosentan, sitaxsentan, ambrisentan), and phosphodiesterase-5 inhibitors (sildenafil). Evidence of efficacy in PAH, coupled with studies showing histopathologic similarities between CTEPH and PAH, provides a rationale to extend the use of some of these medications to the treatment of CTEPH. However, direct evidence from clinical trials in CTEPH is limited to date. This article reviews evidence supporting, and issues surrounding, the possible use of novel PAH medications in CTEPH.

3',5'-Cyclic-GMP Phosphodiesterases↗
PubMed2006

Current understanding of the role of bosentan in inoperable chronic thromboembolic pulmonary hypertension.

Chronic thromboembolic pulmonary hypertension may occur in the context of incomplete lysis of acute pulmonary emboli, resulting in the obstruction of pulmonary blood flow, as well as progressive right ventricular dysfunction and failure. The treatment of choice for this condition is surgical removal of the obstructing material. However, in many patients, surgery is not possible due to either an unfavourable distribution of the disease, the development of a concurrent small vessel pulmonary arteriopathy, or the presence of significant comorbid conditions. There is increasing evidence that the medical therapies that are used in other forms of pulmonary hypertension may also be effective in inoperable chronic thromboembolic pulmonary hypertension. This article examines the rationale for the use of the oral dual endothelin receptor antagonist bosentan in this life-threatening condition.

Antihypertensive Agents↗
PubMed2005

Serotonin transporter polymorphisms in familial and idiopathic pulmonary arterial hypertension.

RATIONALE: Serotonin is a pulmonary vasoconstrictor and smooth muscle cell mitogen. The serotonin transporter (SERT) is abundant in pulmonary vascular smooth muscle. Compared with the short (S) allele, the long (L) SERT promoter allele is associated with increased SERT transcription and more severe pulmonary hypertension in a cohort of patients with chronic obstructive pulmonary disease, and was more prevalent in a cohort with idiopathic pulmonary arterial hypertension (IPAH), compared with control subjects. OBJECTIVE: We hypothesized that the SERT L allele would associate with an earlier age at diagnosis and/or shorter survival interval in pulmonary arterial hypertension (PAH) than the S allele. METHODS: SERT promoters from 166 familial PAH (FPAH), 83 IPAH, and 125 control subjects were sequenced. One hundred twenty-seven of the patients with FPAH had a known mutation in bone morphogenetic protein receptor 2 (BMPR2). RESULTS: The mean age at diagnosis was 35.8 yr in patients with FPAH and 41.1 yr in patients with IPAH (p = 0.02). There were no significant differences in distribution of the LL, LS, or SS genotypes in IPAH, FPAH, or unaffected BMPR2 mutation carriers. In FPAH, the LL genotype was associated with an earlier age at diagnosis (p < 0.02). CONCLUSIONS: In patients with IPAH, these SERT genotypes do not correlate with age at diagnosis or survival interval. In patients with FPAH, the LL genotype correlates with an earlier age at diagnosis than SL or SS, although survival among the groups was similar. The correlation of the SERT promoter polymorphism with age at diagnosis in FPAH suggests a possible relationship between the SERT and BMPR2.

Adult↗
PubMed2005

Asthma management: are GINA guidelines appropriate for daily clinical practice?

An international group of primary care asthma experts, as well as pulmonologists and allergists from Europe and the US, met to discuss asthma management focused on the primary care office. This paper summarizes their discussions. Accuracy of diagnosis and appropriateness of treatment is variable depending on the clinical circumstances and patient group. The value of classifying patients based on baseline or static asthma severity scores remains controversial, and asthma management decisions based on symptom control appear to have greater practical utility in a primary care setting. Furthermore, it must be recognized that patients, caregivers and physicians may have differing, and possibly conflicting, goals for therapy. There are many initiatives to improve the quality of asthma management, for example, primary care-focused guidelines being developed by the International Primary Care Respiratory Group, and several groups are working on asthma control scores. In addition, new therapies may improve the options available for increasing compliance and reducing side effects. In conclusion, asthma management should be patient-focused, with outcomes relevant to improving the quality of life for people with asthma.

Journal Article↗
PubMed2005

Long-term response to calcium channel blockers in idiopathic pulmonary arterial hypertension.

BACKGROUND: Characteristics of patients with idiopathic pulmonary arterial hypertension (IPAH) who benefit from long-term calcium channel blockers (CCB) are unknown. METHODS AND RESULTS: Acute pulmonary vasodilator testing with epoprostenol or nitric oxide was performed in 557 IPAH patients. Acute responders, defined by a fall in both mean pulmonary artery pressure (PAP) and pulmonary vascular resistance (PVR) >20%, received long-term oral CCB. Patients who benefit from long-term CCB were defined as those being in New York Heart Association (NYHA) functional class I or II after at least 1 year on CCB monotherapy. Among the 70 patients who displayed acute pulmonary vasoreactivity (12.6%; 95% CI, 9.8% to 15.3%) and received CCB therapy, only 38 showed long-term improvement (6.8%; 95% CI, 4.7% to 8.9%). Long-term CCB responders had less severe disease at baseline than patients who failed. During acute vasodilator testing, long-term CCB responders displayed a more pronounced fall in mean PAP (-39+/-11% versus -26+/-7%; P<0.0001), reaching an absolute value of mean PAP lower than that measured in patients who failed (33+/-8 versus 46+/-10 mm Hg; P<0.0001). After 7.0+/-4.1 years, all but 1 long-term CCB responders were alive in NYHA class I or II, with a sustained hemodynamic improvement. In the group of patients who failed on CCB, the 5-year survival rate was 48%. CONCLUSIONS: Long-term CCB responders represent <10% of IPAH patients evaluated in a pulmonary vascular referral center. During acute vasodilator testing, these patients showed significantly lower levels of both mean PAP and PVR, which reached near-normal values.

Adult↗
PubMed2005

[Physiopathology of pulmonary arterial hypertension. Cellular and molecular aspects].

The combined effects of vasoconstriction, remodelling of the pulmonary vessel walls and in situ thrombosis contribute to the increase in pulmonary vascular resistance during pulmonary arterial hypertension. Vascular remodelling involves all the sheaths of the vessel wall and all the cell types of which it is composed (endothelial cells, smooth muscle cells, fibroblasts, inflammatory cells and platelets). Excessive vasoconstriction has been related to a defect in the function of expression of the potassium channels and endothelial dysfunction. This leads to chronic insufficiency in the production of vasodilators, notably nitrogen monoxide and prostacyclin and the excessive production of vasoconstrictors such as endotheline-1. These defects contribute to the increase in vascular tonus and pulmonary vascular remodelling and represent pertinent pharmacological targets. Certain growth factors, including those of the super-family of transforming growth factor beta, angiopoietine-1 and serotonin, may play a part in the pathogenesis of pulmonary arterial hypertension.

Apoptosis↗
PubMed2005

Early detection of pulmonary arterial hypertension in systemic sclerosis: a French nationwide prospective multicenter study.

OBJECTIVE: Screening allows for early management of pulmonary arterial hypertension (PAH), a severe complication of systemic sclerosis (SSc). Since no consensus has been reached on the method and criteria for optimal screening, we sought to develop an algorithm based on symptoms, Doppler echocardiography, and right heart catheterization (RHC) for application to a nationwide multicenter SSc population in France. METHODS: This prospective study was conducted from September 2002 to July 2003 by experts at 21 SSc centers. At each center, SSc patients without severe pulmonary function abnormalities underwent Doppler echocardiography by an experienced cardiologist. Patients with a peak velocity of tricuspid regurgitation (VTR) of >3 meters/second or 2.5-3 meters/second with unexplained dyspnea were asked to undergo RHC to confirm PAH according to international guidelines. RESULTS: Of the 599 patients analyzed, 29 had known PAH and 33 had suspected PAH, based on Doppler echocardiography, and underwent RHC. Of these 33, 18 were found to have PAH, 3 had left ventricular dysfunction, and 12 had no PAH. Newly diagnosed cases of PAH were of mild severity (mean +/- SD pulmonary artery pressure [mPAP] 30 +/- 9 mm Hg, mean +/- SD total pulmonary resistance [TPR] 524 +/- 382 dynes x second/cm(5)). Hemodynamic findings in patients with known PAH were mPAP 49 +/- 17 mm Hg and TPR 1,007 +/- 615 dynes x second/cm(5). The estimate of PAH prevalence was 7.85% (95% confidence interval 5.70-10.00). CONCLUSION: This screening algorithm, based on dyspnea, Doppler echocardiographic evaluation of VTR, and RHC, enabled early detection of PAH at a mild stage. Whether mild PAH will evolve to severe PAH in reported cases and whether this early diagnosis translates into improved prognosis for patients with mild PAH will be evaluated in the ongoing 3-year followup of this cohort.

Adult↗
PubMed2005

New chemokine targets for asthma therapy.

Chemokines and chemokine receptors are part of a complex network of molecules that play a key role in leukocyte migration and activation. The chemokine family role is crucial in the immune system, orchestrating innate and acquired immune responses, but also in allergic inflammation. A subset of chemokines, including CCL11, CCL24, CCL26, CCL7, CCL13, CCL17, and CCL22 is highly expressed by the three main cell types involved in allergic inflammation: eosinophils, basophils, and Th2 lymphocytes. In vitro and in vivo experimental studies in murine models of asthma as well as evidence from patients with asthma confirm the role of these chemokines and their receptors, including CCR3, CCR4, and CCR8, establishing a subset of chemokine/chemokine receptor that is potentially important in allergic inflammation. Recent data support the concept that interfering with chemokines or chemokine receptors represents a new approach in allergy therapy. However, even if some of them have been shown to be effective in animal models, none is as yet used in human patients.

Asthma↗
PubMed2005

Drug Insight: endothelin-receptor antagonists for pulmonary arterial hypertension in systemic rheumatic diseases.

Rapid advances in the understanding of endothelin as a naturally occurring peptide with developmental and regulatory roles in normal physiology, along with a number of deleterious effects under pathologic conditions (including vasoconstriction, fibrosis, vascular hypertrophy, and inflammation) have led to the development of endothelin-receptor antagonists (ERAs). Bosentan, an antagonist with dual specificity for the endothelin-receptor subtypes A and B, has been shown to be efficacious and well tolerated in placebo-controlled clinical trials and is now approved in many countries, including the US, Canada, and Europe, for treatment of pulmonary arterial hypertension (PAH), including PAH associated with rheumatic diseases. ERAs with specificity for the endothelin-receptor subtype A, including sitaxsentan and ambrisentan, are currently undergoing investigation. This article reviews PAH associated with systemic rheumatic diseases and describes the role of ERAs in this setting.

Endothelin Receptor Antagonists↗
PubMed2005

Current insights on the pathogenesis of pulmonary arterial hypertension.

Regardless of the initial trigger, the elevated pulmonary arterial pressure and vascular resistance in patients with pulmonary arterial hypertension are primarily caused by remodeling and thrombosis of small- and medium-sized pulmonary arteries and arterioles, as well as sustained vasoconstriction. The process of pulmonary vascular remodeling involves all layers of the vessel wall and is complicated by cellular heterogeneity within each compartment. Indeed, each cell type (endothelial cells, smooth muscle cells, and fibroblasts), as well as inflammatory cells and platelets, may play significant roles in this condition. Recent studies have emphasized the relevance of several mediators in this condition, including prostaglandin-I (2) (prostacyclin), nitric oxide, endothelin-1, angiopoietin-1, 5-hydroxytryptamine (serotonin), cytokines, chemokines, and members of the transforming growth factor beta (TGF-beta) superfamily. Targeting some of these dysfunctional pathways (prostacyclin, nitric oxide, and endothelin-1) has been beneficial in subjects displaying pulmonary arterial hypertension.

Apoptosis↗
PubMed2005

Severe pulmonary hypertension during pregnancy: mode of delivery and anesthetic management of 15 consecutive cases.

BACKGROUND: Available literature on pregnant women with severe pulmonary hypertension (PH) relies mainly on anecdotal case reports and two series only. METHODS: The authors reviewed the charts of all pregnant women with severe PH who were followed up at their institution during the past 10 yr, to assess the multidisciplinary treatment and outcome of these patients. RESULTS: Fifteen pregnancies in 14 women with severe PH were managed during this period: There were 4 cases of idiopathic pulmonary arterial hypertension (PAH), 6 cases of congenital heart disease-associated PAH, 1 case of fenfluramine-associated PAH, 1 case of mixed connective tissue-associated PAH, 1 case of human immunodeficiency virus-associated PAH, and 2 cases of chronic thromboembolic PH. PH presented during pregnancy in 3 patients. Two patients died before delivery at 12 and 23 weeks' gestation. Four patients had vaginal deliveries with regional anesthesia: One died 3 months postpartum, one worsened, and two remained stable. Four had cesarean deliveries during general anesthesia: One died 3 weeks postpartum, one worsened, and two remained stable. Five had cesarean deliveries during low-dose combined spinal-epidural anesthesia: One died 1 week postpartum, and four remained stable. There were two fetal deaths: one related to therapeutic abortion at 21 weeks' gestation and one stillbirth at 36 weeks' gestation followed by the death of the mother 1 week later. CONCLUSIONS: Despite the most modern treatment efforts, the maternal mortality was 36%. Scheduled cesarean delivery during combined spinal-epidural anesthesia seemed to be an attractive approach, but there was no evidence of actual benefit. Therefore, pregnancy must still be discouraged in patients with severe PH.

Adult↗
PubMed2005

Cirrhotic rats with bacterial translocation have higher incidence and severity of hepatopulmonary syndrome.

BACKGROUND: Bacterial translocation, that is, extra-intestinal dissemination of gut bacteria, occurs in approximately 50% of humans and rats with cirrhosis and plays a significant role in enhanced tumor necrosis factor-alpha (TNF-alpha) production. The authors' previous studies have indicated that prevention of bacterial translocation with norfloxacine or inhibition of TNF-alpha with pentoxifylline treatment decreased both the incidence and severity of hepatopulmonary syndrome by attenuating the induction of pulmonary intravascular macrophages in cirrhotic rats. In the present study the hypothesis was tested that the cirrhotic rats with bacterial translocation had higher TNF-alpha production, higher level of sequestration of macrophages in pulmonary vessels, and increased incidence and severity of hepatopulmonary syndrome. METHODS: Rats were studied 5 weeks after common bile duct ligation or sham operation. Bacterial translocation was defined by positive mesenteric lymph node cultures. Hepatopulmonary syndrome was assessed by measurements of alveoloarterial oxygen difference (AaPO(2)) and intrapulmonary shunt. The TNF-alpha concentration in plasma was measured by ELISA. Pulmonary intravascular macrophage sequestration was assessed by lung morphometric analysis. RESULTS: Bacterial translocation occurred in 48% of cirrhotic rats. Plasma concentrations of TNF-alpha and the percentage of vessels with pulmonary intravascular macrophages were higher in the cirrhotic rats with bacterial translocation. Rats with bacterial translocation also had a higher incidence (9% vs 63%, P < 0.01) and severity of hepatopulmonary syndrome, as indicated by higher levels of both AaPO(2) and intrapulmonary shunt. CONCLUSIONS: These results suggest that bacterial translocation may play a role in the pathogenesis of hepatopulmonary syndrome by inducing pulmonary intravascular macrophages through TNF-alpha upregulation.

Animals↗
PubMed2005

Clinical challenges in pulmonary hypertension: Roger S. Mitchell lecture.

Despite major advances in our understanding of the pathophysiologic processes leading to pulmonary arterial hypertension and recent developments in therapeutic approaches, the long-term prognosis for patients with pulmonary arterial hypertension remains unsatisfactory. Early detection and adequate clinical classification of the disease, better assessment of patients' prognosis, and improved therapeutic strategies are important challenges for clinicians in coming years.

Humans↗
PubMed2005

Idiopathic pulmonary hypertension: what did we learn from genes?

Pulmonary arterial hypertension (PAH) is an uncommon disorder. PAH can be idiopathic, associated with other conditions or clustered in families. Indeed, at least 6% of individuals diagnosed with so-called "primary" pulmonary hypertension have a family history of the disorder. Familial PAH segregates as an autosomal dominant trait but with markedly reduced penetrance. Defects within bone morphogenetic protein receptor type II gene (BMPR2), coding for a type II receptor member of the transforming growth factor beta (TGF-beta) family, have been shown to underlie familial PAH. Germline BMPR2 mutations have been detected in at least 60% of the families studied to date. Disease-associated mutations are predicted to interrupt the BMP-mediated signalling pathway predisposing to proliferation of cells within small pulmonary arteries. Several lines of evidence point to the potential requirement of additional factors, either environmental or genetic, in the pathogenesis of the disease. In addition, a proportion of idiopathic PAH as well as anorexigen-associated PAH turn out to have an inherited basis, as demonstrated by detection of germline BMPR2 mutations. Analysis of other genes encoding TGF-beta receptor proteins, led to the demonstration that PAH in association with hereditary hemorrhagic telangiectasia, an autosomal dominant vascular dysplasia, can involve other TGF-beta receptor subtypes. These observations support the hypothesis that mutations in the TGF-beta superfamily may be a trigger for pulmonary vascular remodeling. Nevertheless, PAH pathobiology remains unclear and genomic approaches may identify additional molecular determinants for this disorder.

Bone Morphogenetic Protein Receptors, Type II↗