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Biomedical subjects

J M Tunon de Lara

Publications and source records attributed to J M Tunon de Lara.

16 recordsLinked to original sources
PubMed2001

Spontaneous pneumothorax: pragmatic management and long-term outcome.

We prospectively considered 65 patients admitted for a spontaneous pneumothorax (SP) to describe the pragmatic management of SP, the first recurrence-free interval after medical therapeutic procedure and to specify the first recurrence risk factors over a 7-year period in these patients treated medically. The treatment options were observation alone (9%), needle aspiration (6%), small calibre chest tube (Pleurocatheter) drainage (28%) or thoracic tube drainage (49%), and pleurodesis with video-assisted thoracic surgery procedure (8%). Duration of the drainage and length of hospital stay were shorter in the Pleurocatheter group than in the thoracic tube group (P < 0.01). Among the 47 patients (72%) with a first SP and treated medically, nine patients (19%) had a first homolateral recurrence (FHR) during a mean follow-up of 84+/-13 months. Recurrence-free intervals ranged from 1 to 24 months (mean +/- SD: 9.3+/-8.4 months). FHR cases were more frequent in the Pleurocatheter group (P < 0 04). Analysis of potential risk factors showed that the patient's height and a previous homolateral SP episode are independent recurrence risk factors.

Adolescent↗
PubMed2000

[Response to IgE].

Over the last three decades, a good deal of work has focused on the IgE response due to the implication of these antibodies in allergic diseases. IgE antibodies, mediators of immediate hypersensitivity reactions, bind to specific high or low affinity receptors which are distributed on cell surfaces throughout the organism. Activation of receptors contributes to the different aspects of allergic inflammation. Regulation of the IgE response is complex and involves different factors modulating isotype synthesis, low-affinity receptor FcERII:CD23 and its soluble portion, and the Th1/Th2 balance. Allergic diseases are characterized by a dysregulated IgE response, probably related to an imbalance favoring Th2 leading to exaggerated reaction. The advent of anti-IgE treatments can be seen as a notable progress in the management of atopic diseases. Their contribution will depend on the exact role of the IgE response in inflammatory allergic reactions.

Antigens↗
PubMed1999

[Evolution of the management of lung diseases in general medicine in Bordeaux (1992-1995)].

Lower respiratory tract infections (LRTI) are very often managed by General Practitioners (GPs). In France, the 1991 Lille Consensus Conference set out guidelines for the management of respiratory tract infections; in 1994, the Ministry of Health published Official Medical Recommendations (OMR) to be applied to seasonal respiratory infections. The aim of the study is to evaluate the impact of these OMR in 1995 on GPs' attitude when confronted with a community-acquired pneumonia in a previously healthy 40-year-old adult, with no sign of complications. Sixty seven GPs took, part in the same study by questionnaire in 1992 and 1995; we observed an increase in the prescription of aminopenicillin without a beta-lactamase inhibitor (41% in 1992 vs 66% in 1995; p = 0.009), and a reduction in both the use of aminopenicillin with a beta-lactamase inhibitor (35% in 1992 vs 11% in 1995; p = 0.002) and the concomitant prescription of cortico-steroids (43% in 1992 vs 14% vs 14% in 1995; p = 0.0009). Between 1992 and 1995, general practitioners in the Bordeaux region have changed their therapeutic choices in community-acquired pneumonia. In 1995, antibiotic prescriptions followed consensus guidelines more closely.

Adult↗
PubMed1998

[Osmolarity of solutions used in nebulization].

Inhaled medications are widely used in patients suffering from bronchial diseases. Beside their pharmacological properties, nebulised solutions have physico-chemical characteristics that can alter bronchial reactivity. Non-isotonic solutions can induce a bronchial hyperresponsiveness and/or a severe bronchonconstriction. Nevertheless, multiple drugs are used for nebulisation despite their unknown osmolarity. The aim of this study was to measure the tonicity of drug solutions commonly used for nebulisation in patients suffering from bronchial disease. Drug solutions were prepared either according to manufacturer recommendations or by diluting the stock in 5 ml of NaCl (0.9%) or H2CO3 (0.14%). Although bronchodilatator solutions (i.e. salbutamol, terbulatine, ipratropium bromide) were nearly isotonic, some drugs prepared for nebulisation had either a very high (e.g. mesna, netilmicine) or a very low (e.g. gomenol, sodium cromoglycate) tonicity. These values may be responsible for bronchoconstriction. Some hypertonic solutions, prepared with drugs such as acetylcytein or netilmycin, are not commercialised for nebulisation but are commonly used for aerosol therapy. In addition, solutions initially isotonic could become significantly hypertonic towards the end of nebulisation. Taken together, these results suggest that non-isotonic solutions should be used with caution specially in patients with bronchial hyperresponsiveness, even when aerosol therapy is prescribed for upper airways.

Acetylcysteine↗
PubMed1997

[Bacterial infectious agents implicated in lower respiratory tract infections in general practice].

The consensus of the French Society of Infectious Diseases established in 1991 states that Streptococcus pneumoniae and Haemophilus influenzae are the main causal agents of community-acquired lower airway infections and that antibiotics constitute the "prudent" solution in case of acute bronchitis which persists more than one week or in case of pneumonia in "fragile" at-risk adults. The efficacy of these "probabilistic" recommendations depends on the epidemiology of the infectious agents. The objective of this study was to identify the causal germs in lower airway infections and determine their sensitivity to the antibiotics recommended in the consensus statement. The study was conducted from December to March, in 1992 and 1993. Expectoration samples were obtained from 111 cases including 29 patients with chronic bronchitis. Seventy different strains were isolated including 24 strains of H. influenzae (3 betalactamase producers), 15 strains of S. pneumoniae (1 with reduced sensitivity to peni G: MIC = 1 mu/ml), 9 strains of S. aureus (2 methicillin resistant), and 8 strains of Branhamella catarrhalis (6 betalactamase producers). The number of positive serologies was very low: 5 Chlamydiae pneumoniae, 2 Chlamydiae trachomatis and 1 Mycoplasma pneumoniae. In conclusion H. influenzae is the most frequent germ; S. pneumoniae infections with reduced peni-G sensitivity and atypical germs are uncommon. The consensus recommendations appear to be adapted to the bacterial flore causing community-acquired lower airway infection in healthy and at-risk subjects.

Adult↗
PubMed1996

[Immunoglobulins E and inflammatory cells].

Immunoglobulins E (IgE) have a privileged relationship with inflammatory cells due to the fact that there are different receptors for their Fc fragment expressed on the cell's surface. Currently one recognises at least three types of receptor: high affinity receptors (Fc epsilon RI) which are present on the surface of mast cells, basophils, and Langerhans cells. The receptors of low affinity (Fc epsilon RII) are represented on the surface of numerous inflammatory cells (eosinophils, lymphocytes, platelets...) and some lectine type (epsilon BP) receptors which are present on polymorpho-nuclear neutrophils and activated macrophages. The IgE interaction in the presence of specific antigens on the receptor may lead to cellular activation by transduction mechanism which are becoming better understood. This sequence of events, combined with the mechanisms of immediate hypersensitivity lead to the liberation of mediators and cytokines which nature varies according to the cell type and its environment. Polymorpho-nuclear eosinophils, mast cells, basophils and many other cells comply with this type of activation. However, the relationship between IgE and cells is not limited to this type of activation response. In the absence of specific antigen, IgE may sometimes play an inhibitory role on cellular functions; it is the case of blood platelets and polymorpho-nuclear neutrophils. Finally, IgE also participates in normal mechanisms of immune defence and may perhaps, by their presence on the surface of the dentritic cells, be determining factors in the function of antigen presentation. The diversity of IgE action at cellular level may equally be observed at the level of the bronchus, on organ which is implicated in allergic pathology. Passive sensitisation of the human bronchus by IgE may have at least two types of effect on the contractile response observed in vivo: in the presence of specific antigen it enables the contraction of bronchial smooth muscles and in the absence of antigen it could change the contractile response to non-specific agonists as it is observed in vivo in bronchial hyper-reactivity.

Asthma↗
PubMed1995

IgE-induced passive sensitization of human isolated bronchi and lung mast cells.

Passive sensitization of human isolated lung with serum from atopic asthmatic patients provides an opportunity to study the link between airway hyper-responsiveness and the allergic process. To directly demonstrate the role of immunoglobulin E (IgE) in the effect of the atopic serum, we have compared the effect of passively sensitizing both human bronchi and isolated lung mast cells with either serum from atopic asthmatic patients or human monoclonal IgE. Peripheral bronchi ( < 5 mm in internal diameter) were dissected out from human lung obtained at thoractomy and isometric contraction was studied in response to a variety of immunological stimuli according to the sensitization protocol. Mast cells were also isolated from human lung and histamine release was measured under similar experimental conditions. A contractile response was elicited by either the specific antigen or anti-IgE (0.6-600 ng.mL-1) but not anti-immunoglobulin G (IgG) 0.2-20 micrograms.mL-1) in airways sensitized with atopic serum (total IgE concentration of approximately 1,000 international units (IU).mL-1). The maximal contractile response to anti-IgE was 75 +/- 22% of the response to 1 mM acetylcholine. Similarly, anti-IgE released histamine from isolated lung mast cells sensitized with atopic serum up to 22.4 +/- 2% of total histamine measured within mast cells. When isolated airways or mast cells were sensitized with human monoclonal IgE (1,000 IU.mL-1), response to anti-IgE in terms of contractile response or histamine release, respectively, were not significantly different from those obtained following passive sensitization with atopic serum. Finally, the bronchial contractile response to anti-IgE depended not only on the concentration of anti-IgE but also on that of IgE (300-2,000 IU.mL-1) used to sensitize the airways. These results indicate that the effect of antigen or anti-IgE in peripheral bronchi passively sensitized with atopic serum is mimicked when sensitization is carried out directly with human monoclonal IgE.

Adult↗
PubMed1994

Salivary IgE in allergic patients and normal donors.

A prospective study was conducted on 73 allergic patients and 14 normal volunteers in order to measure the IgE concentration in both serum and saliva, and analyze salivary IgE according to the characteristics of the allergic disease. IgE was more frequently detected in saliva from allergic patients than from normal subjects, but its concentration was not significantly higher in the allergic group. The IgE concentration in saliva was not related to serum IgE or to the type of syndromes of the allergic disease, but increased with the symptoms during the pollen season in patients suffering from pollen-induced rhinitis and conjunctivitis.

Adolescent↗
PubMed1993

Sensitization decreases relaxation in human isolated airways.

Passively sensitized human isolated airways provide an opportunity to study some aspects of bronchial hyperresponsiveness in vitro. Since it has been suggested that excessive airway narrowing could be due to impaired relaxation, we examined the effect of a variety of agents producing relaxation via different mechanisms, i.e., verapamil and lemakalim (a calcium channel antagonist and a potassium channel opener, respectively) and isoproterenol, forskolin, and dibutyryl cAMP (modulators of the beta-adrenoceptor signal transduction pathway). Human bronchial rings, obtained at thoracotomy, were passively sensitized by incubation in serum from atopic asthmatic patients, and control rings were incubated in serum from nonatopic subjects. We also studied bronchial rings from five spontaneously sensitized human lung specimens. Responses to the relaxant compounds were measured isometrically. Passive sensitization significantly decreased the efficacy of verapamil in maximally contracted tissues from 60 +/- 10 to 45 +/- 7% of the maximal carbachol response (n = 6, p < 0.05) and that of lemakalim from 51 +/- 16 to 38 +/- 14% (n = 7, p < 0.05) in tissues at baseline tone. Similarly, spontaneously sensitized tissues relaxed less to lemakalim (64 +/- 6% of the maximal response to isoproterenol, n = 5, p < 0.05) than did nonsensitized tissues (80 +/- 4%). Sensitization did not alter responses to isoproterenol, forskolin, and dibutyryl cAMP. We conclude that sensitization of human isolated airways reduces relaxation responses that depend upon activation of ion channels but not those that depend upon activation of beta-adrenoceptors and transduction processes directly coupled to these receptors.

Asthma↗
PubMed1992

IgE binding inhibits arachidonic acid-induced chemiluminescence of human platelets.

Arachidonic acid (AA)-induced chemiluminescence (CHL) was studied in vitro by means of a luminometer in platelets from nine healthy volunteers and six allergic patients. The amplitude of the CHL signal increased with AA concentration from 250 microM to 7 mM. At a low AA concentration (250 microM), the CHL signal consisted of two peaks. The first one occurred at 6 +/- 3 sec and the second one at 90 +/- 15 sec (n = 9). The mean amplitude of these peaks was 1.95 +/- 0.61 mV/sec and 0.82 +/- 0.22 mV/sec for normal subjects, and 2.35 +/- 0.62 mV/sec and 0.78 +/- 0.26 mV/sec for allergic patients, respectively. Aspirin (a cyclooxygenase inhibitor) and baicalein (a lipoxygenase inhibitor) reduced in a concentration-dependent manner, the first and second peak, respectively. The binding of immunoglobulin E (IgE) alone to platelets from both normal and allergic subjects inhibited both the first and second peak of AA-induced CHL. This inhibitory effect was specifically due to the action of IgE as it was (i) concentration-dependent and (ii) not observed when immunoglobulin G (IgG) was substituted for IgE. It is concluded that in normal subjects, as well as in allergic patients, the binding of IgE alone to its specific receptor on human platelets could alter arachidonate metabolism that probably involves cyclooxygenase and lipoxygenase pathways.

Adult↗
PubMed1991

The inhibitory effect of immunoglobulin E on monoamine uptake in human platelets.

The uptake of the monoamine radiolabelled tracer 125I-meta-iodo-benzyl-guanidine (MIBG) was studied in vitro in platelets from 15 healthy volunteers and five allergic patients whose serum IgE concentration was 37 +/- 33 and 650 +/- 200 IU/ml, respectively. The MIBG uptake was determined by means of a gamma counter after incubation in a buffer. Binding of IgE to platelets significantly reduced MIBG uptake both in healthy subjects and in allergic patients. This reduction was significantly related to the action of IgE as it did not occur after binding of IgG. Moreover, MIBG uptake plotted versus increasing concentration of IgE (ranging from 10 to 3000 IU/ml) was fitted by a classical sigmoidal curve which was not significantly different between healthy subjects and allergic patients. Lastly, the effect of IgE on MIBG uptake was due to the binding of the sole IgE as it was not modified by subsequent addition of anti-IgE. It is concluded that the binding of the sole IgE to its specific receptor on platelets alters the transport of monoamines.

3-Iodobenzylguanidine↗
PubMed1991

[A new form of mushroom workers' lung].

The authors describe a new form of mushroom workers' lung after assessing the clinical situation and also the results of an immunological study. The case was related to the mushroom Poria megalopora. A new antigen has been identified and also its domiciliary origin, thus the ubiquitous nature of the antigen contributes to the interest of the case reported.

Alveolitis, Extrinsic Allergic↗