Pathophysiology of bronchial smooth muscle remodelling in asthma.

Whereas the role of bronchial smooth muscle remains controversial in healthy subjects its role is well established in asthmatics. Bronchial smooth muscle contraction induces airway narrowing. The smooth muscle also contributes to bronchial inflammation by secreting a range of inflammatory mediators, recruiting and activating inflammatory cells, such as mast cells or T-lymphocytes. In addition, bronchial smooth muscle mass is significantly increased in asthma. Such an increase has been related to a deposition of extracellular matrix proteins, and an increase in both cell size and number. However, the mechanisms of this smooth muscle remodelling are complex and not completely understood. The article will review recent data regarding the pathophysiology of bronchial smooth muscle remodelling in asthma.

Mast cell adhesion to bronchial smooth muscle in asthma specifically depends on CD51 and CD44 variant 6.

BACKGROUND: Mast cells infiltrate the bronchial smooth muscle (BSM) in asthmatic patients, but the mechanism of mast cell adhesion is still unknown. The adhesion molecules CD44 (i.e. hyaluronate receptor) and CD51 (i.e. vitronectin receptor) are widely expressed and bind to many extracellular matrix (ECM) proteins. The aims of the study are (i) to identify the role of ECM in mast cell adhesion to BSM and (ii) to examine the role of CD51 and CD44 in this adhesion. METHODS: Human lung mast cells, human mast cell line (HMC-1), and BSM cells from control donors or asthmatic patients were cultured in the presence/absence of various cytokines. Mast cell-BSM interaction was assessed using (3)H-thymidine-pulsed mast cells, confocal immunofluorescence, or electron microscopy. Adhesion molecules expression and collagen production on both cell types were evaluated by quantitative RT-PCR, western blot, and flow cytometry. RESULTS: Mast cell adhesion to BSM cells mostly involved type I collagen of the ECM. Such an adhesion was increased in normal BSM cells under inflammatory condition, whereas it was maximal in asthmatic BSM cells. Blockade of either CD51 or CD44 significantly decreased mast cell adhesion to BSM. At the molecular level, protein and the transcriptional expression of type I collagen, CD51 or CD44 remained unchanged in asthmatic BSM cells or in mast cells/BSM cells under inflammatory conditions, whereas that of CD44 variant isoform 6 (v6) was increased. CONCLUSIONS: Mast cell-BSM cell adhesion involved collagen, CD44, and CD51, particularly under inflammatory conditions. CD44v6 expression is increased in asthmatic BSM cells.

[Characteristics of private and irregular prescription for oral antibiotics in Spanish community pharmacies]. / Perfil de las solicitudes de antibióticos en farmacia comunitaria con receta privada y prescripción irregular.

OBJECTIVE: To quantify the proportion of oral antibiotics through private prescription (PP) and irregular prescription (IP) in the Community Pharmacy (CP). MATERIAL AND METHODS: Cross-sectional multicentre study carried out in Spanish community pharmacies over a 4week period, one in each season of the year. An analysis was made of private and irregular prescriptions of oral J01 antibacterials for systemic use (Anatomical Therapeutic Chemical [ATC] classification). The study variables used were prescription and consultation characteristics. RESULTS: A total of 3569 PP (71% followed legislation) and 833 IP were recorded by 365 pharmacists working in 247 CP. PP were prescribed by dentists (43.7%), general practitioners (GP) (26.20%), and paediatricians (10.3%), to treat teeth infections (39.8%), upper respiratory infections (25.6%), lower respiratory infections (10.3%), and urinary infections (7.7%). The most prescribed antibiotics were amoxicillin (27.9%) and amoxicillin-clavulanic (25.2%). IP came from Emergency Departments (32.8%), oral/phone prescriptions (20.4%), and patient demand due to insufficient quantity of antibiotic to complete treatment (10%). Prescriptions came from GP (25.2%), dentists (24.7%), and paediatricians (12%) to treat upper respiratory infections (32.5%), teeth infections (25.8%), urinary infections (14.2%), and lower respiratory infections (10.8%). The most prescribed antibiotics were amoxicillin-clavulanic (27.4%) and amoxicillin (21.6%). Since every patient with IP was referred to the GP, 45.4% of them accepted the recommendations of the pharmacists. CONCLUSIONS: This study obtained PP and IP characteristics, unknown and needed data in Spain for future health policy plans.

[Oral antibiotic request without prescription in community pharmacies. Description of pharmacists' intervention]. / Demanda de antibióticos sin prescripción en la farmacia comunitaria. Descripción de la intervención del farmacéutico.

OBJECTIVES: To quantify the proportion of oral antibiotics requests without prescription in Community Pharmacy (CP) and to analyse it causes. METHOD: Cross-sectional multicentre study carried out in Spanish community pharmacies during 4 weeks, one in each season of the year. Oral J01 antibiotics (Anatomical Therapeutic Chemical classification, ATC) requested for self-medication were analysed. RESULTS: 247 pharmacies and 365 pharmacists participated in the study, 1172 antibiotic requests were recorded. More frequent requests for antibiotic self-medication were: previous treatment for the same symptoms (63.1%), insufficient time for a general practitioner (GP) consultation (12.1%) and patient belief that GP is going to prescribe the antibiotic (4.9%). Higher number of generic medication were requested compared to brand medication (41.1 versus 34.9%). Active ingredients commonly requested were amoxicillin (28.2%), amoxicillin-clavulanic (14.9%) and phosphomycin (21.8%) to treat upper respiratory related infections (35.1%), urinary infections (28.1%) and teeth infections (20.2%). 2406 pharmacists' interventions were carried out: referring to the GP (40.8%), information for correct use of medication (31.3%), non-pharmacological treatment (15.7%), and recommendation of a different medication (6.9%) or a different product (5.3%). CONCLUSIONS: Nowadays higher number of active ingredients than brands are requested when selecting a treatment for an infection, mainly ß-lactams and macrolides. Majority of self-medication tried to treat upper respiratory infections, urinary and teeth infections. Most frequent pharmacists' intervention was referring to the GP to obtain a correct diagnosis and treatment.

Masitinib, a c-kit/PDGF receptor tyrosine kinase inhibitor, improves disease control in severe corticosteroid-dependent asthmatics.

BACKGROUND: Masitinib is a tyrosine kinase inhibitor targeting stem cell factor receptor (c-kit) and platelet-derived growth factor (PDGF) receptor, which are expressed on several cell types including mast cells and bronchial structural cells, respectively. We hypothesized that c-kit and PDGF receptor inhibition may decrease bronchial inflammation and interfere with airway remodeling, which are crucial features of severe asthma. OBJECTIVES: The primary endpoint was the percent change from baseline in oral corticosteroids after 16 weeks of treatment. Change in asthma control (asthma control questionnaire), exacerbation rate, pulmonary function tests, rescue medication requirement and safety were secondary endpoints. METHODS: A 16-week randomized, dose-ranging (3, 4.5, and 6 mg/kg/day), placebo-controlled study was undertaken in 44 patients with severe corticosteroid-dependent asthma who remained poorly controlled despite optimal asthma management. RESULTS: At 16 weeks of treatment, a comparable reduction in oral corticosteroids was achieved with masitinib and placebo (median reduction of -78% and -57% in the masitinib and placebo arms, respectively). Despite this similar reduction, the Asthma Control Questionnaire score was significantly better in the masitinib arm as compared to placebo with a reduction by 0.99 unit at week 16 (P < 0.001) vs 0.43 unit in the placebo arm. Masitinib therapy was associated with more transient skin rash and edema. CONCLUSIONS: Masitinib, a c-kit and PDGF-receptor tyrosine kinase inhibitor, may represent an innovative avenue of treatment in corticosteroid-dependent asthma. These preliminary results warrant further long-term clinical studies in severe asthma

Langevin simulation of rf collisional multipactor breakdown of gases.

The thresholds for the electron multiplication in both multipactor and the so-called collisional multipactor microwave discharges are calculated by means of an individual particle model. The simulations are restricted to low and intermediate gas pressures, where the collisional mean-free path of electrons is of the same order or larger than the characteristic dimension of the system. Thus, the charge multiplication is caused by both the electron impact ionization of the neutral gas and the secondary electron emission by electron collisions at the surfaces. The charge avalanche is simulated by the numerical integration of the trajectories of electrons up to the characteristic time for the space-charge buildup. The electron dynamics is described by the stochastic Langevin equations where the collisional scatter of electrons is incorporated by means of a random force, while the microwave electric field and the friction are deterministic forces. The physical properties of materials at the walls are considered by means of realistic models deduced from experimental data fitting, while the constant collision frequency model is used for elastic and inelastic electron collisions with neutral atoms. Previous results for low pressure electron multipactor are recovered, and for pressures corresponding to collisional multipactor the predictions of this simple model are in agreement with both the experimental results and particle in cell and Monte Carlo simulations. Finally, physical conditions under which the charge multiplication develops and the limitations for higher pressures of the proposed model are also discussed.

[Atopic dermatitis aggravates the allergic airways inflammation in acute viral bronchiolitis]. / La dermatite atopique aggrave l'inflammation allergique dans la bronchiolite aiguë virale.

INTRODUCTION: Exhaled nitric oxide (FeNO) is a putative non-invasive marker of eosinophilic airway inflammation with a good predictive value for allergic asthma in preschool children. The aim of the present study was to compare FeNO after acute viral bronchiolitis (AVB) in children aged less than 2 years without atopic dermatitis (AD) vs those with atopic dermatitis, as well as children with AD without any history of AVB. METHODS: Forty-two children (mean age +/- SD: 12.3 +/- 5.2 months; range 5.0-23.5; sex-ratio M: F=1.3: 1) were included in this prospective study, > 8 wks after an episode of AVB. The patients' atopic status was assessed both by clinical phenotype and IgE- mediated response to inhaled and/or food allergens. FeNO (ppb) was measured off-line by the chemoluminescence method on samples obtained from gas collected in a balloon during tidal breathing. RESULTS: There was a significant difference between the AVB/AD (23.4 +/- 14.3 ppb, n=15) vs the AVB without AD group (13.5 +/- 10. 1 ppb, n=13) or the AD without AVB group (11.0 +/- 8.3 ppb, n=14). Maternal feeding for more than 2 months decreased FeNO by 50%. CONCLUSION: Atopic children below 2 years with AD produce more NO after AVB than non-atopic children or atopic children without any history of AVB. Maternal feeding decreases FeNO.

Bone fractures after cardiac transplantation.

OBJECTIVE: Bone loss and bone fractures are disabling complications after heart transplantation. Severe bone loss happens mainly during the first year posttransplantation. Steroids and cyclosporine alter bone metabolism in several ways. To counterbalance these effects, antiresorptive therapy is provided to these patients. The objective of this study was to assess the frequency of bone fractures after heart transplantation, considering previous comorbidities, immunosuppressive therapy, and osteoprotective treatment. METHODS: From 1993 to 2005, 443 consecutive heart transplant recipients were followed for the occurrence of bone fractures, immunosuppressive therapy, clinical conditions, and antiresorptive treatment. RESULTS: There were 41 fractures in 34 patients (7.6%, group I). The remainder of patients formed group II. Fractures commonly involved the lumbar spine. Postmenopausal women had more fractures than other patients (20.6% vs 7.8%, P = .02). When the initial immunosuppressive regimen included tacrolimus, fractures did not happen (P = .01, vs other regimens). Osteoprotective therapy was administered to 91.2% of patients in group I and 79% in group II (P = .08). Mean interval from transplantation to the first fracture was 1131.5 days. Overweight patients had a 61.8% incidence of fracture. CONCLUSIONS: Our series showed a low frequency of bone fractures. Postmenopausal women and overweight patients had more fractures. An initial immunosuppressive regimen using tacrolimus was associated with lower fracture rates.

Análisis coste-efectividad del implante percutáneo de válvula aórtica SAPIEN 3 en pacientes con estenosis aórtica grave sintomática / Cost-effectiveness analysis of the SAPIEN 3 transcatheter aortic valve implant in patients with symptomatic severe aortic stenosis

Introducción y objetivos: El implante percutáneo de la válvula aórtica se ha consolidado como tratamiento de la estenosis aórtica grave inoperable o de alto riesgo quirúrgico. Recientemente las indicaciones se han ampliado a riesgo intermedio y bajo. Nuestro objetivo es evaluar la eficiencia de SAPIEN 3 frente al tratamiento médico conservador (TMC) o el reemplazo quirúrgico de válvula aórtica (RVA) en pacientes sintomáticos inoperables con riesgo alto e intermedio.´Métodos: Análisis de coste-efectividad de SAPIEN 3 frente a RVA/TMC mediante un modelo de Markov (ciclos mensuales) adaptado con 8 estados definidos por la New York Hearth Association y resultados a 15 años, incluidos las complicaciones mayores y el tratamiento tras el alta hospitalaria, desde la perspectiva del Sistema Nacional de Salud. Los parámetros de efectividad se basan en los estudios PARTNER. Se incluyeron costes sanitarios (en euros de 2019) derivados del procedimiento, hospitalización, complicaciones clínicas y seguimiento. Se aplicó una tasa de descuento anual del 3% en costes y beneficios. El análisis de sensibilidad fue determinístico y probabilístico (Monte Carlo). Resultados: En comparación con el RVA (riesgo alto e intermedio) y el TMC (inoperables), el SAPIEN 3 implicó mejores resultados en las 3 poblaciones y menor estancia. Las tasas de coste-utilidad incremental fueron 5.471 (riesgo alto), 8.119 (riesgo intermedio) y 9.948 (inoperables) euros/años de vida ajustados por calidad ganados. En el análisis probabilístico, el SAPIEN 3 resultó coste-efectivo por encima del 75% de las simulaciones en los 3 perfiles. Conclusiones: En nuestro medio, el SAPIEN 3 permite un tratamiento eficiente de la estenosis aórtica grave tanto en pacientes inoperables como en riesgo alto e intermedio (AU)

Introduction and objectives: Transcatheter aortic valve implant has become a widely accepted treatment for inoperable patients with aortic stenosis and patients at high surgical risk. Its indications have recently been expanded to include patients at intermediate and low surgical risk. Our aim was to evaluate the efficiency of SAPIEN 3 vs conservative medical treatment (CMT) or surgical aortic valve replacement (SAVR) in symptomatic inoperable patients at high or intermediate risk. Methods: We conducted a cost-effectiveness analysis of SAPIEN 3 vs SAVR/CMT, using a Markov model (monthly cycles) with 8 states defined by the New York Heart Association and a time horizon of 15 years, including major complications and management after hospital discharge, from the perspective of the National Health System. Effectiveness parameters were based on the PARTNER trials. Costs related to the procedure, hospitalization, complications, and follow-up were included (euros in 2019). An annual discount rate of 3% was applied to both costs and benefits. Deterministic and probabilistic sensitivity analyses (Monte Carlo) were performed. Results: Compared with SAVR (high and intermediate risk) and CMT (inoperable), SAPIEN 3 showed better clinical results in the 3 populations and lower hospital stay. Incremental cost-utility ratios (€/quality-adjusted life years gained) were 5471 (high risk), 8119 (intermediate risk) and 9948 (inoperable), respectively. In the probabilistic analysis, SAPIEN 3 was cost-effective in more than 75% of the simulations in the 3 profiles. Conclusions: In our health system, SAPIEN 3 facilitates efficient management of severe aortic stenosis in inoperable and high- and intermediate-risk patients (AU)

Tryptase-stimulated human airway smooth muscle cells induce cytokine synthesis and mast cell chemotaxis.

Asthmatic patients have higher numbers of mast cells in the smooth muscle layer of airways than normal subjects. Human airway smooth muscle cells (HASMCs) are a source of various cytokines including transforming growth factor beta1 (TGF-beta1), which is chemotactic for mast cells. We have thus examined the potential for interaction between HASMCs and mast cells and have investigated, in particular, the hypothesis that after stimulation, HASMCs can induce mast cell chemotaxis through the production of cytokines. Supernatants of HASMCs treated with the major mast cell product tryptase had increased chemotactic activity for the HMC-1 mast cell line. The effect depended on an intact catalytic site for tryptase and could be induced by a peptide agonist for protease activated receptor 2. Chemotactic activity was related to the synthesis of TGF-beta1 by HASMCs and, to a lesser extent, to stem cell factor. The number of mast cells within the smooth muscle layer of asthmatic patients was closely related to TGF-beta1 expression by smooth muscle. HASMCs may thus be able to stimulate the accumulation of mast cells, and these cells may, in turn, stimulate the secretion of chemotactic factors by HASMCs.

[Development of a questionnaire concerning the knowledge of COPD]. / Développement d'un questionnaire de connaissances sur la BPCO.

INTRODUCTION: The level of a patient's knowledge about his disease and its treatment is an essential part of an educational assessment. It is useful therefore to make use of a rapid, easy and valid method to collect the information necessary to develop an educational programme adapted to the needs of the patient. The aim of this study is to validate, in a structured way, a knowledge questionnaire on chronic obstructive pulmonary disease (COPD). METHODS: Following a revue of the literature an initial questionnaire was constructed. It included of four domaines: biomedical aspects; symptoms and signs of severity; general knowledge and treatments. The questionnaire was tested on 35 subjects with COPD in order to assess its clarity and comprehensibility. It was reviewed and modified in both content and format by 11: French experts. The reproducibility was studied by repeat testing. RESULTS: The first version of the questionnaire developed by the working party consisted of 50 items. It was reduced to 41 items after interviews with 35 COPD patients and evaluation by 11 experts. The questionnaire appeared to be reproducible: mean concordance 79.5%; minimum 53.3%; maximum 100% and intra-class correlation coefficient 0.53. CONCLUSION: This study lead to the development of a French language COPD knowledge questionnaire.

[IgE and respiratory disease]. / Immunoglobuline E et maladies respiratoires.

INTRODUCTION: IgE is known to provide the biological basis for allergy and immediate hypersensitivity. However, recent data provide some evidence that IgE responses are involved in other inflammatory processes apart from allergy, including several respiratory diseases. STATE OF THE ART: IgE binds to mast cells and basophils but also to other inflammatory cells, which are involved in non-allergic processes. IgE has a role in antigen presentation and is implicated in a number of other immune mechanisms. In the airways, IgE plays an important role in bronchial hyperactivity, even in the absence of an allergen. Epidemiological studies have demonstrated that IgE response is related not only to allergy but also to asthma symptoms, in the presence or absence of atopy, as well as exposure to cigarette smoke. IgE response is altered in several respiratory diseases including extrinsic and intrinsic asthma and allergic bronchopulmonary aspergillosis. CONCLUSION AND PERSPECTIVES: Since anti-IgE monoclonal antibodies are now available for administration to humans, a better understanding of the IgE response may allow the identification of novel therapeutic targets in the field of respiratory disease.

Hemodynamic, platelet and clinical responses to prostacyclin in unstable angina pectoris.

The hemodynamic and platelet effects of prostacyclin (PGI2) were investigated in 27 patients with unstable angina (14 treated patients; 13 control subjects) given a 72-hour infusion (5 ng/kg/min) or placebo. This randomized study was double-blind and conducted as a substudy of a multicenter trial testing the clinical efficacy of PGI2. The clinical and angiographic features were identical in the 2 groups. Blood pressure and heart rate were not modified significantly by PGI2. A recurrence of angina during infusion occurred in 8 treated patients (57.1%) and in 8 control subjects (61.5%). Two patients receiving PGI2 and none in the control group developed a myocardial infarction. Levels of 6-keto-prostaglandin F1 alpha, a stable metabolite of PGI2, increased from baseline values (less than 20 pg/ml) to 605 +/- 41 pg/ml during infusion. Levels of fibrinopeptide A, beta-thromboglobulin, platelet factor 4, thromboxane B2 and the platelet aggregates ratio in blood were similar between the 2 groups before, during and after PGI2 infusion. Prostacyclin reduced ex vivo platelet aggregation to adenosine diphosphate and thromboxane B2 generation by approximately 50% during the infusion period with return of aggregation to baseline and platelet thromboxane B2 production to above baseline after the discontinuation of PGI2. Thus, despite favorable effects of PGI2 upon platelet aggregation and systemic hemodynamics, the prostanoid failed to improve the clinical evolution of unstable angina.

Spontaneous pneumothorax associated with Pneumocystis carinii pneumonia. Successful treatment with talc pleurodesis.

Spontaneous pneumothoraces occur in patients with acquired immunodeficiency syndrome and Pneumocystis carinii pneumonia. However, treatment with tube insertion and tetracycline sclerosis often fails to prevent recurrence. We present a single case of such a patient successfully treated with talc sclerosis.

Selected contribution: tryptase-induced PAR-2-mediated Ca(2+) signaling in human airway smooth muscle cells.

Tryptase, the major mast cell product, is considered to play an important role in airway inflammation and hyperresponsiveness. Tryptase produces different, sometimes opposite, effects on airway responsiveness (bronchoprotection and/or airway contraction). This study was designed to examine the effect of human lung tryptase and activation of protease-activated receptor (PAR)-2 by synthetic activated peptide (AP) SLIGKV-NH(2) on Ca(2+) signaling in human airway smooth muscle (HASM) cells. Immunocytochemistry revealed that PAR-2 was expressed by HASM cells. Tryptase (7.5--30 mU/ml) induced a concentration-dependent transient relative rise in cytoplasmic Ca(2+) concentration ([Ca(2+)](i)) that reached 207 +/- 32 nM (n = 10) measured by indo 1 spectrofluorometry. The protease inhibitors leupeptin or benzamidine (100 microM) abolished tryptase-induced [Ca(2+)](i) increase. Activation of PAR-2 by AP (1-100 microM) also induced a concentration-dependent transient rise in [Ca(2+)](i), whereas the reverse peptide produced no effect. There was a homologous desensitization of the [Ca(2+)](i) response on repeated stimulation with tryptase or AP. U-73122, a specific phospholipase C (PLC) antagonist, xestospongin, an inositol trisphosphate (IP(3))-receptor antagonist, or thapsigargin, a sarcoplamic Ca(2+)-ATPase inhibitor, abolished tryptase-induced [Ca(2+)](i) response, whereas Ca(2+) removal, in the additional presence of EGTA, had no effect. Calphostin C, a protein kinase C inhibitor, increased PAR-2 [Ca(2+)](i) response. Our results indicate that tryptase activates a [Ca(2+)](i) response, which appears as PAR-2 mediated in HASM cells. Signal transduction implicates the intracellular Ca(2+) store via PLC activation and thus via the IP(3) pathway. This study provides evidence that tryptase, which is increasingly recognized as an important mediator in airway inflammation and hyperresponsiveness, is also a potent direct agonist at the site of airway smooth muscle.

Tryptase and agonists of PAR-2 induce the proliferation of human airway smooth muscle cells.

Airway remodeling with smooth muscle cell (SMC) hyperplasia is a feature of chronic asthma. We investigated the potential for tryptase, the major secretory product of human mast cells, to act as a growth factor for human airway SMCs. Because this serine protease can activate proteinase-activated receptor-2 (PAR-2), we also examined the actions of SLIGKV, a peptide agonist of PAR-2. Incubation with lung tryptase provoked a twofold increase in [(3)H]thymidine incorporation; a similar increase in cell numbers was found when we used the MTS assay. The effect was catalytic site dependent, being abolished by the protease inhibitors leupeptin and benzamidine and by heat inactivation of the enzyme. Tryptase-induced DNA synthesis was inhibited by preincubation of the cells with pertussis toxin, calphostin C, or genistein. Transduction mechanisms are thus likely to involve a pertussis toxin-sensitive G protein, protein kinase C, and tyrosine kinase. SLIGKV elicited a response on SMCs similar to that of tryptase. Tryptase could provide an important stimulus for SMC proliferation in asthmatic airways, by acting on PAR-2.

Asthma phenotypes according to the timing of smoking onset in young adults.

SETTING: Whether and how cigarette smoking influences asthma are still matters of debate. OBJECTIVE: To identify risk factors associated with asthma according to whether individuals began active smoking before or after asthma onset. DESIGN: A sample of 544 individuals was examined using the protocol of the European Community Respiratory Health Status, Phase 1. RESULTS: Current active smoking (43.6%) was associated with wheezing during the past year (15.2%, OR 3.7; 95% CI 1.7-8.4), but not with asthma (17.6%, OR 0.78; 95% CI 0.48-1.26). However, active smoking modulated risk factors for asthma. Asthma that developed before smoking and asthma without smoking were both significantly related to nasal allergy, parental asthma and atopy (as assessed by skin prick test positivity and increased total and specific IgE levels). Only a lower FEV1 level was significantly associated with asthma that initiated after beginning smoking. CONCLUSIONS: Our data put forward different phenotypes of asthma according to the timing of smoking onset and suggest that asthma either never accompanied by smoking or followed by smoking onset might be characterised by an allergic pattern. Longitudinal studies are warranted to further clarify the relationships among asthma phenotypes according to the sequence of disease onset and smoking.

Structure of the rRNA genes in the hamster sperm nucleus.

We have examined the structure of the major ribosomal RNA (rRNA) genes in the hamster sperm nucleus, using fluorescent in situ hybridization (FISH). The rRNA genes are present as tandemly repeated clusters located at the telomeric ends of the short arms of five pairs of acrocentric chromosomes in the Syrian golden hamster (as they are in humans). In somatic cells, these five chromosome pairs come together to form the nucleolus, the site of rRNA synthesis. The nucleolus remains intact through S phase of the cell cycle, breaking apart only during late G2 and mitosis when the chromosomes condense. Mammalian sperm nuclei are the final products of meiotic division and morphological differentiation that includes a dramatic chromatin condensation. Consequently, it was not immediately obvious whether the rRNA genes would be condensed into a nucleolus-like structure in the mature spermatozoa, or separated, as they are in mitotic chromosomes. We found that of 117 sperm nuclei examined, 91.5% contained between two and five FISH signals for the rRNA gene clusters, and 64.0% contained four (29%) or five (35%) signals. In decondensed hamster sperm nuclei, the rRNA hybridized signals were separated into independent strands. These data collectively indicate that the chromosomes containing the rRNA genes are not bound together into a pre-nucleolar structure in fully condensed mammalian sperm nuclei.

DNA organization in human spermatozoa.

Previous studies from this laboratory on hamster spermatozoa have demonstrated that rodent sperm DNA is packaged into the sperm nucleus in a specific manner by nuclear structures. The entire genome is organized into DNA loop domains attached at their bases to a sperm nuclear matrix, the skeletal structure of the nucleus. When nuclei are completely decondensed, the nuclear matrix dissipates, and the entire genome remains anchored to a single structure located at the base of the tail, termed the nuclear annulus. Here, we have extended these studies to human sperm nuclei, which were found to be similar to hamster. Human sperm DNA was found to be organized into loop domains attached at their bases to a nuclear matrix. The average size of the human sperm halo of DNA surrounding the extracted sperm nucleus (made up of DNA loop domains) was about 50% smaller than those that have been reported for somatic cells (this corresponds to an approximate loop domain size of 26.8 +/- 2.1 kb). Human sperm DNA also remained anchored to the base of the tail when completely decondensed, indicating the existence of a nuclear annulus-like structure in human spermatozoa; but, unlike the hamster nuclear annulus, the human annulus could not be isolated because of its structural instability when separated from the tail. Using human centromere repeats as a probe for in situ hybridization, we examined the packaging of individual DNA sequences within the sperm nucleus. These studies demonstrate that human sperm DNA is highly organized by nuclear structures.

Practical evaluation of asthma exacerbation self-management in children and adolescents.

The objective of this study was to describe asthma exacerbation self-management in children and adolescents. We used a cross-sectional study population enrolled in the International Study of Asthma and Allergies in Childhood (ISAAC) in Bordeaux. Subjects answered an additional questionnaire on utilization of health services, self-evaluation of usual asthma exacerbation severity and home management of asthma exacerbation. Criteria used for selecting patients were both having asthma confirmed by a physician and having had suffered from symptoms during the past year. Children and adolescents attended similar health services for managing their asthma but compliance to anti-asthmatic treatment was better in children than in adolescents. Among the children 4.8% had asthma and 6.2% of adolescents had asthma, as diagnosed by a doctor. Of the children, 72.3% and of the adolescents 54.7% had less than one asthma attack per month. In cases of mild asthma exacerbation, 38.7% of adolescents and 9.3% of children waited until the end of exacerbation without taking any medication. The proportion of children not receiving any treatment was lower when symptoms were more severe but this was not the case in adolescents. Although most of the patients used were taking beta2-agonist, we found that 21-43% of children or adolescents did not receive appropriate medication in the event of asthma exacerbation. These results demonstrate that (i) asthma exacerbation self-management is related to self-assessed severity of symptoms and that (ii) a large proportion of asthmatic children in the community, and particularly adolescents, do not therefore receive appropriate treatment in the event of asthma exacerbation.