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Biomedical subjects

D Grenet

Publications and source records attributed to D Grenet.

At least 19 recordsLinked to original sources
PubMed2003

Phagocytosis and intracellular fate of Aspergillus fumigatus conidia in alveolar macrophages.

Aspergillus fumigatus is the most prevalent airborne fungal pathogen responsible for fatal invasive aspergillosis in immunocompromised patients. Upon arrival in the lung alveolus, conidia of A. fumigatus are phagocytosed by alveolar macrophages, the major phagocytic cells of the lung. Engulfment and intracellular trafficking of A. fumigatus conidia in alveolar macrophages of two different origins, the murine cell line MH-S and human pulmonary alveolar macrophages, were analyzed by electron microscopy and immunofluorescence. Phagocytosis of A. fumigatus conidia required actin polymerization and phosphatidylinositol 3-kinase activity. Fusion of A. fumigatus phagosomes with early and late endosomes was shown by immunolabeling with specific markers for the transferrin receptor, early endosome antigen, and Rab7. Maturation of A. fumigatus phagolysosomes was monitored by using a fixable acidotropic probe, LysoTracker Red DND-99, and an anti-cathepsin D antibody. Bafilomycin A-induced inhibition of lysosomal acidification abolished the conidial killing by the macrophages. These data suggest that the maturation of A. fumigatus phagosomes results from fusion with the compartments of the endocytic pathway and that the killing of conidia depends on phagolysosome acidification. A model for the phagocytosis of A. fumigatus conidia by alveolar macrophages is proposed on the basis of these results.

Actins↗
PubMed2002

[Mucoviscidosis in adults].

FROM CHILDREN TO ADULTS: Mucoviscidosis, a genetic autosomal recessive disease, is not only a paediatric disease, but with the progress in therapy, has become a disease of adults. Today, median survival of patients is of 30 years and, in France, more than one third of patients are adults. CLINICAL SYMPTOMS IN ADULTS: Are predominantly respiratory, with dilatation of the bronchi and characteristic colonization flora. Chronic bronchial Pseudomonas aeruginosa colonisation is frequently encountered in adults. It develops in successive episodes towards chronic respiratory failure. Other than this typical form, diagnosed in the first years of life, the discovery of the CFTR (Cystic Fibrosis Transmembrane conductance Regulator) gene and its mutations permits diagnosis of mucoviscidosis in patients presenting with mild, or even monosymptomatic forms of the disease. Today, diagnosis of mucoviscidosis relies on the association of characteristic organ damage and an abnormality in CFTR (sweat test and/or difference in nasal potential) or the revelation of gene mutations on each allele. REGARDING TREATMENT: Respiratory failure is the core of daily therapeutic efforts. Respiratory physical therapy, effort re-education and muscle exercising are essential. Antibiotherapy is aimed at treating, spacing out or preventing the infectious exacerbations, in order to stall the functional degradation. Repeated, sequential cycles of intravenous infusions of antibiotics are required in P. aeruginosa chronic bronchial colonization. Treatment of the primary pyocyanic colonisation and inhaled antiobiotherapy appear promising. Pulmonary transplantation is a recognized and efficient therapeutic in advanced stages of respiratory failure. The discomfort and time the patient has to spend on daily treatments requires regular monitoring, to improve compliance and to improve the quality of life of these patients.

Adult↗
PubMed2001

Increased endothelin-1 associated with bacterial infection in lung transplant recipients.

BACKGROUND: Endothelin-1 (ET-1) has fibrogenic and inflammatory properties. Its pathogenic role in pulmonary fibrosis and certain inflammatory airway diseases is now well known. Its production is, in part, triggered by infectious processes. Episodes of infection are suspected to be involved in the development of bronchiolitis obliterans syndrome (BOS), which is the main feature of chronic lung rejection and the major factor limiting the long-term survival of transplanted patients. We postulated that ET-1 is upregulated during infectious complications arising from the graft and that this could partly explain the remodeling of airway structures observed in BOS. We, therefore, set up this study to assess ET-1 expression in relation to complications of the graft in human lung transplant recipients. METHODS: ET-1 mRNA was quantified by reverse transcription-competitive polymerase chain reaction in cells from 119 samples of bronchoalveolar lavage (BAL) fluid from 17 lung transplant recipients. ET-1 and big ET-1 proteins were assessed in BAL cell culture supernatants by enzyme immunoassay. Transbronchial biopsies (n=21) were stained immunohistochemically for ET-1 receptors. RESULTS: Episodes of bacterial infection strongly correlated with increased ET-1 mRNA and protein expression. ET-1 receptors were also upregulated during these episodes, especially on endothelial and smooth muscle cells. Five of the seven patients with the highest ET-1 levels subsequently developed BOS. CONCLUSIONS: These results raise the possibility that ET-1, part of whose production is triggered by infectious postgraft complications, might play a role in the development of BOS through its potential effects on airway remodeling.

Adult↗
PubMed2001

[Bone mineral density in patients with chronic lung diseases].

PURPOSE: We evaluated bone mineral density and phosphorus calcium status in patients with chronic lung diseases. PATIENTS AND METHODS: A prospective study was conducted in 58 patients (43 men and 15 women, mean age 44 years, age range 16-68 years) who were classed in three groups: chronic obstructive diseases (25 patients), cystic fibrosis (19 patients), and other lung diseases (14 patients). Fifteen percent of the patients were receiving corticosteroid therapy. Bone mineral density of the lumbar spin and the femoral neck was measured. RESULTS: Serum calcium, phosphate, creatinine, osteocalcin and parathyroid hormone were normal. The 25-hydroxyvitamin D (normal=9-40 ng/ml) level was in the lower limits of normal (12 ng/ml) and was severely decreased in 12 patients (<7 ng/ml). CONCLUSION: Chronic lung disease can lead to osteoporosis. Corticosteroids, low vitamin D level, sedentary lifestyle, smoking, and in cystic fibrosis nutritional deficiencies, delayed puberty and hypogonadism are risk factors. Bone density must be measured in order to prevent and treat osteoporosis.

Adolescent↗
PubMed2000

Insulinlike growth factor-1 in lung transplants with obliterative bronchiolitis.

Bronchiolitis obliterans syndrome (BOS) is the major complication limiting survival of lung transplant recipients (Tx patients). The mechanisms underlying this fibrotic process are not known. We assessed IGF-1 and IGFBP-3 expression, critical mediators in different models of pulmonary fibrosis, in nine Tx patients. Three of them developed a BOS at 8, 14, and 17 mo postgraft, respectively. Two of the remaining six displayed a recurrent cytomegalovirus (CMV) infection, and four are in stable condition. IGF-1 mRNA expression was quantitated by RT-PCR in cells from four to six BAL per patient performed during the first 6 mo postgraft. Contrasting with a constantly low expression of IGF-1 mRNA in BAL cells from the six patients without BOS, the three patients with BOS presented marked peaks of IGF-1 on two to five occasions during the study period. These peaks, 3- to 13-fold increased compared with values from the former patients, preceded the diagnosis of BOS by 7, 13, and 17 mo, respectively. On the other hand, IGFBP-3 was highly and exclusively expressed in the three patients with BOS, the mRNA as well as the gene product as demonstrated by Western blotting. Our data strongly argue for a role of IGF-1 and IGFBP-3 in the fibrotic process underlying BOS, and for their possible value as an early marker of this complication.

Biopsy↗
PubMed2000

[Specific aspects and care of lung involvement in adults with cystic fibrosis].

Respiratory impairment is present in almost all adult cystic fibrosis patients and makes the prognosis. Viscous, infected and abundant secretions, inflammation and bronchial oedema, bronchoconstriction and respiratory muscle fatigue lead to airway obstruction, bronchiectasis and respiratory failure. The disease is preferentially located in the upper lobes. Exacerbations of the disease are due to bronchial infections and are often responsible for drops of the respiratory function. Regular spirometric surveillance is fundamental for the prognosis and the assessment of the effects of the treatment. Among adult patients chronic colonisation with mucoid and often multiresistant strains of Pseudomonas Aeruginosa are common. It is treated with i.v. high doses antibiotic courses and nebulized antibiotics between i.v. courses. Respiratory failure may require long term oxygen and non invasive mechanical ventilation. Systemic hypervascularization around the bronchiectasis may lead to moderate to severe hemoptysis, which may require embolization. Pneumothorax are associated with poor prognosis and are treated by pleural drainage and if failure by thoracoscopy.

Adrenal Cortex Hormones↗
PubMed2000

[Lung transplantation in cystic fibrosis in adults. Patient selection criteria].

Lung transplantation (LT) became during the ten past years an important therapeutic option for cystic fibrosis adult patients with end-stage chronic lung disease. LT clearly improves both survival and long term quality of life. A rigorous selection of the candidates is of paramount importance to improve the results of LT because of the lack of shortage of organs. This selection requires a multidisciplinary assessment to refuse patients with absolute exclusion criteria or general medical conditions that impact negatively on short- and long-term outcome. One of the major difficulties is to determine the best time to refer patients to transplantation, arguing the comparison between the predicted survival time of the candidate, under optimal medical therapy, with or without LT. The selection period is also an active process to prepare the patients to the postoperative follow-up and includes a nutritional and rehabilitation program with an educational and psychological preparation. The aim of the present work is to gather the worldwide principles of the selection of the CF patients for LT, commonly used by the LT centers. These recommendations should provide the CF center practitioners with the main elements to prepare their patients to an LT project before a relentless end-stage clinical condition.

Adolescent↗
PubMed1998

[Reduction of native lung volume after single-lung transplantation for emphysema].

We report three cases of volume reduction surgery in three single lung transplant recipients with emphysema. Each patient had a late decline in lung function with hyper-inflation of the native lung. Lung function was improved post-operatively for two patients. The relief of thoracic overdistension may be considered in single lung transplant recipients who exhibit clinical significant functional deterioration.

Adult↗
PubMed1997

Predictive value of cytomegalovirus DNA detection by polymerase chain reaction in blood and bronchoalveolar lavage in lung transplant patients.

BACKGROUND: Despite promising results, the efficacy of polymerase chain reaction (PCR) for clinical management of cytomegalovirus (CMV) infection in transplanted patients is still controversial. METHODS: A prospective study of CMV detection, with concurrent shell vial cultures and PCR in blood and bronchoalveolar lavage (BAL), was conducted in 13 lung transplant recipients, monitored for 15 months (range: 1-42 months). CMV DNA was detected by PCR amplification of a 406-bp fragment in the Us region and a 290-bp fragment in the immediate early region of the viral genome. RESULTS: When comparing PCR to viral culture, the sensitivity and specificity of CMV DNA detection were 100% and 65.7% in blood (n=122) and 100% and 75% in BAL (n=104). The positive and negative predictive values of PCR for a forthcoming diagnosis of CMV infection were 50% and 97% in blood, and 67% and 85% in BAL. Seventeen CMV infections were evaluated at the end of treatment: when PCR was still positive either in blood or BAL, CMV infection relapsed within 35+/-5 days; when PCR was negative, CMV infection relapsed after 142+/-57 days (P=0.01). CONCLUSIONS: Negative CMV detection by PCR strongly advocates against a forthcoming CMV infection. PCR assay seems to be a good predictor for early recurrence of CMV infection, and would be useful for monitoring the response to antiviral therapy.

Adolescent↗
PubMed1997

Failure of ganciclovir treatment associated with selection of a ganciclovir-resistant cytomegalovirus strain in a lung transplant recipient.

We report the case of a lung transplant recipient with progressive cytomegalovirus (CMV) disease due to a resistant CMV strain emerging under ganciclovir (GCV) therapy. A discriminative polymerase chain reaction (PCR) assay, designed to detect the resistance-related V460 mutation within the viral enzyme UL97, revealed the presence of a mutated strain in a heterogeneous isolate 51 days after transplantation. The conventional antiviral susceptibility assay had failed to demonstrate resistance to GCV. Under prolonged GCV therapy, the mutated strain dominated the wild-type strain, as shown by the PCR assay. This domination led to laboratory resistance, associated with recurrent fever and progressively severe retinitis. As this discriminative PCR assay was shown to be effective in detecting mutated strains that constitute a minority in the virus load, it should allow better management of patients with CMV disease.

Adult↗
PubMed1994

[Antiphospholipid syndrome. 20 cases].

OBJECTIVES: We analyzed the clinical and biological characteristics as well as the clinical course and outcome observed in 20 patients with antiphospholipid antibodies and clinical signs including thrombosis or repeated spontaneous abortion to better identify the recently described antiphospholipid syndrome. METHODS: We retrospectively studied all patients observed in our unit from 1981 to 1992 who fulfilled the following inclusion criteria: a) at least one episode of arterial or venous thrombosis and/or repeated spontaneous abortions, b) positive for antiphospholipid antibodies. RESULTS: Twenty patients were included, 3 with systemic lupus erythematosus (according to the American Rheumatism Association criteria). Arterial or venous thrombosis occurred in 9 and 16 respectively, including exceptional cases of cerebral phlebitis and thrombosis of dermal capillaries. High blood pressure was recorded in 8. Only 1 or 2 types of antiphospholipid antibodies were found in most patients. Anticardiolipin, a circulating anticoagulant and a false-positive Bordet-Wassermann reaction were found together in only 3 out of 16. In addition, the antibody level varied independently from the thrombotic events. There was no case with a clinical course from primary antiphospholipid syndrome to systemic erythromatosus lupus. The effect to treatment on occurrence of new thrombotic events was studied. Three patients suffered one or more haemorrhagic events during antivitamin K treatment. CONCLUSION: It is difficult to establish a differentiation between primary antiphospholipid syndrome, systemic lupus erythematosus and lupus-like syndromes, and precise methods of identifying antiphospholipid antibodies should be further developed.

4-Hydroxycoumarins↗
PubMed1994

Treatment of systemic vasculitis with cyclophosphamide and steroids: daily oral low-dose cyclophosphamide administration after failure of a pulse intravenous high-dose regimen in four patients.

The efficacy of cyclophosphamide (CY) in the treatment of severe systemic vasculitis has been demonstrated, but its optimal administration regimen remains to be defined. The four patients described participated in prospective therapeutic trials of polyarteritis nodosa (PAN) without hepatitis B infection markers, Churg-Strauss syndrome (CSS) and Wegener's granulomatosis (WG) and received daily oral low-dose CY after failure of a monthly pulse regimen. These patients were included in this study because of failure to induce clinical remission (two patients) and relapse during the course of treatment (two patients). The results were good with initial clinical remission in three patients and stabilization in one. One patient with WG relapsed 10 months after changing therapeutics. The advantages of the different administration protocols are discussed.

Administration, Oral↗
PubMed1991

Urea gradient/SDS-PAGE; a useful tool in the investigation of signal transducing G proteins.

We describe an updated and improved protocol to perform urea gradient/SDS-PAGE in which proteins are electrophoresed through 9% polyacrylamide gel slabs in the presence of a linear 4 M to 8 M gradient of urea using Laemmli's separation buffers. We provide examples of this technique to separate PTX labeled G protein alpha subunits, as well as unlabeled alpha and beta subunits of G proteins. Applications of the technique are exemplified in which (1) the chromatographic separations of G proteins in DEAE-Toyopearl and MonoQ columns are compared, (2) the complexity of PTX substrates expressed in human erythrocytes, bovine brain, dog ventricle, FRTL-5 cells, HIT cells, GH4C1 cells and RIN cells are compared, and (3) the polypeptide composition of G protein beta gamma subunits, as expressed in several tissues and found in three distinct G proteins from a single cell population, are analyzed.

Adenosine Diphosphate Ribose↗
PubMed1987

Identification of a new GTP-binding protein. A Mr = 43,000 substrate for pertussis toxin.

In purified preparations of human erythrocyte GTP-binding proteins, we have identified a new substrate for pertussis toxin, which has an apparent molecular mass of 43 kDa by silver and Coomassie Blue staining. Pertussis toxin-catalyzed ADP-ribosylation of the 43-kDa protein is inhibited by Mg2+ ion and this inhibition is relieved by the co-addition of micromolar amounts of guanine nucleotides. GTP affects the ADP-ribosylation with a K value of 0.8 microM. Addition of a 10-fold molar excess of purified beta gamma subunits (Mr = 35,000 beta; and Mr = 7,000 gamma) of other GTP-binding proteins results in a significant decrease in the pertussis toxin-mediated ADP-ribosylation of the 43-kDa protein. Treatment of the GTP-binding proteins with guanosine 5'-O-(thiotriphosphate) and 50 mM MgCl2 resulted in shifting of the 43-kDa protein from 4 S to 2 S on sucrose density gradients. Immunoblotting analysis of the 43-kDa protein with the antiserum A-569, raised against a peptide whose sequence is found in the alpha subunits of all of the known GTP-binding, signal-transducing proteins (Mumby, S. M., Kahn, R. A., Manning, D. R., and Gilman, A. G. (1986) Proc. Natl. Acad. Sci. U. S. A. 83, 265-259) showed that the 43-kDa protein is specifically recognized by the common peptide antiserum. A pertussis toxin substrate of similar molecular weight was observed in human erythrocyte membranes, bovine brain membranes, membranes made from the pituitary cell line GH4C1, in partially purified GTP-binding protein preparations of rat liver, and in human neutrophil membranes. Treatment of neutrophils with pertussis toxin prior to preparation of the membranes resulted in abolishment of the radiolabeling of this protein. From these data, we conclude that we have found a new pertussis toxin substrate that is a likely GTP-binding protein.

Adenosine Diphosphate Ribose↗
PubMed1987

Hormonal regulation of pituitary GH3 cell K+ channels by Gk is mediated by its alpha-subunit.

The resolved alpha-GTP gamma S (alpha*) and beta gamma-subunits of human erythrocyte Gk, the stimulatory regulatory component of hormone-responsive K+ channels, were tested for their potential stimulatory activities on the K+ channel of the endocrine GH3 cell. Concentrations as low as 0.5 pM alpha k* consistently activated K+ channels in isolated membrane patches, and saturating effects were obtained with 50 pM alpha k*. In contrast 2000-4000 pM beta gamma was without effect. We conclude that Gk acts on K+ channels through its alpha-subunit in a manner akin to that of Gs acting on adenylyl cyclase and transducin acting on cGMP-specific phosphodiesterase of photo-receptor cells.

Animals↗