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Biomedical subjects

J Bignon

Publications and source records attributed to J Bignon.

At least 73 records · Page 4Linked to original sources
PubMed1992

Bronchoalveolar disease in dyskeratosis congenita.

Dyskeratosis congenita (DC) is an unusual familial disorder primarily affecting the skin and its appendages. We report the case of a DC patient with chronic respiratory tract involvement, confirming the features previously reported by a small number of authors: 1) chronic bronchoalveolar involvement is not unusual in this disorder; 2) the main features are early sputum production with subsequent bronchial and alveolar destruction; 3) after onset of dyspnoea the course is rapidly fatal, with progressive respiratory failure. Immune deficiency and repeated bronchoalveolar infections may be involved in the pathogenesis of these manifestations.

Adult↗
PubMed1991

Biochemical characteristics of alveolar macrophage-specific peroxidase activities in the rat.

The biochemical characteristics of endogenous macrophage peroxidases (Po), and their relationship to myeloperoxidase (MPO), have heretofore been poorly understood and were examined in the current study. Rat alveolar macrophages (AM) were homogenized and fractionated by differential centrifugation into lysosomal and microsomal fractions. The Po activities in both fractions were separated using HPLC gel-filtration and two main activities were detected. One, in the lysosomal fraction, had a relative molecular mass (Mr) of 58,000, while the other, associated with the microsomal fraction corresponded to Mr 74,000. By comparison, MPO from rat polymorphonuclear neutrophils (PMN) had Mr 140,000. The 58- and 74-kDa Po activities also differed from MPO with respect to their apparent Km for H2O2 and optimum pH of activity. Using o-dianisidine as a substrate, the Km for H2O2 of the 58- and 74-kDa Po species was 0.4 and 0.19 mM, respectively, compared to 0.011 mM for MPO. Using monochlorodimedon, the corresponding values were 0.22 and 0.195 mM for the 58- and 74-kDa activities and 0.026 mM for MPO. With either substrate, MPO exhibited optimum activity at pH 5.4, compared to 5.2 for the 58-kDa activity and 4.8 for the 74-kDa species. Thus, rat AM contain two endogenous Po activities with biochemical characteristics distinct from those of MPO. Our findings suggest that these activities represent novel peroxidases that may play an important role in the oxidative metabolism of AM.

Animals↗
PubMed1991

Sialidase in the guinea pig pulmonary parenchyma. Increased activity in the cytosolic and microsomal subcellular fractions after stimulation with Bacillus Calmette Guérin.

The sialidase activity was assayed in the guinea pig pulmonary parenchyma after removal of bronchoalveolar cells by washing. After differential centrifugation of the crude tissue homogenate, sialidase activities were measured in the subcellular fractions using the fluorogenic substrate 2-(4-methylumbelliferyl)-alpha-D-N-acetylneuraminate. Sialidase activities were found in the lysosomal-enriched (17,000 x g pellet), in the microsomal (105,000 x g pellet) and in the cytosolic (105,000 x g supernatant) fractions. Microsomal and lysosomal forms of sialidase had an optimum activity at pH 3.6-3.8, whereas the optimum for the cytosolic form was pH 4.6. The activity of all three forms was inhibited by Cu2+, whereas 1 mM Zn2+ and 0.5 mM Ca2+ activated the lysosomal and the cytosolic forms, respectively. In the crude homogenate taken from lungs of Bacillus Calmette Guérin-(BCG-) stimulated guinea pigs, the sialidase activity was increased by 43% (p = 0.025) 3 weeks after the end of the treatment. The cytosolic (+246%) and microsomal (+51%) sialidase activities were significantly increased, whereas the lysosomal sialidase activity was not changed significantly by BCG stimulation.

Animals↗
PubMed1991

Silica and lung cancer: a controversial issue.

The role of crystalline silica in lung cancer has long been the subject of controversy. In this article, we review the main experimental and epidemiological studies dealing with this problem. Some evidence for a genotoxic potential of crystalline silica has been obtained in the rare in vitro studies published to date. In vivo studies have shown that crystalline silica is carcinogenic in the rat; the tumour types appear to vary according to the route of administration. In addition, an association between carcinogenic and fibrogenic potency has been observed in various animal species exposed to crystalline silica. An excess of lung cancer related to occupational exposure to crystalline silica is reported in many epidemiological studies, regardless of the presence of silicosis. However, most of these studies are difficult to interpret because they do not correctly take into account associated carcinogens such as tobacco smoke and other occupational carcinogens. An excess of lung cancer is generally reported in studies based on silicosis registers. Overall, experimental and human studies suggest an association between exposure to crystalline silica and an excess of pulmonary malignancies. Although the data available are not sufficient to establish a clear-cut causal relationship in humans, an association between the onset of pneumoconiosis and pulmonary malignancies is probable. In contrast, experimental observations have given rise to a pathophysiological mechanism that might account for a putative carcinogenic potency of crystalline silica.

Animals↗
PubMed1991

Inherited factors in diffuse bronchiectasis in the adult: a prospective study.

To evaluate the prevalence of inherited respiratory ciliary structure and underlying mucus abnormalities in the diffuse bronchiectasis syndrome, we investigated 53 subjects comprising 38 patients with diffuse bronchiectasis confirmed by high-resolution thoracic computed tomography, ten with chronic bronchitis and no diffuse bronchiectasis and five healthy nonsmoking control subjects. The clinical history was determined by means of a standardized questionnaire. Axonemal abnormalities of respiratory cilia were evaluated on bronchial or nasal mucosa samples by transmission electron microscopy (structure) and stroboscopic observation (function). Cystic fibrosis (CF) and Young's syndrome were detected by means of the sweat test and semen analysis when male infertility was suspected. Among the 38 patients with diffuse bronchiectasis, a primary ciliary dyskinesia (PCD) was detected in five (13%) with a high proportion (range: 55-100%) of cilia showing axonemal ultrastructural abnormalities always involving the dynein arms. The prevalence of this inherited condition was higher in North African (36%) than in European patients (4%) (p less than 0.01). After exclusion of the five patients with PCD, the patients with diffuse bronchiectasis showed axonemal ultrastructural abnormalities similar to those with chronic bronchitis. The diagnosis of underlying mucus disorders was based on two types of criterion, i.e. for CF, sweat chloride levels greater than 80 mmol.l-1, or the combination of diagnostic criteria proposed by Stern et al. Respectively, five (three Young's syndrome and two CF) and seven (one Young's syndrome and six CF) cases of inherited mucus disorders were suspected. Our results showed that PCD was highly prevalent among the adult North African patients with diffuse bronchiectasis but relatively rare in the Europeans.

Adult↗
PubMed1990

Recurrent chromosome aberrations in human lung squamous cell carcinomas.

Cytogenetic study of seven cases of previously untreated lung squamous cell carcinomas (SQC) is reported. Chromosome numbers vary from 38 to 538, with a majority of hypotriploid karyotypes with complex rearrangements. The numbers of recurrent imbalances were evaluated in considering the average number of chromosomes or chromosome segments in each analyzed metaphase and for each case. In decreasing order of frequency, deficiencies for 3p, 5q, 8p, Y, 5p, 10p, 13, and, to a lesser degree, for 8q, 9, 10q, 11pter, 14, 15, and 21 were observed; the excesses principally involve 1q, 3q, and 7q. In three tumors, homogeneously staining regions were observed at various chromosome sites. Most chromosome rearrangements occurred after breakage in constitutive heterochromatin, and no recurrent breakpoints were found in euchromatin except 11p15. The major consequences of these anomalies may be chromosomal imbalances, leading to hemizygosity and perhaps related to gene dosage, rather than to alterations of genes.

Adult↗
PubMed1990

[The mesothelial cells].

Mesothelial cells are described in situ at the surface of the pleura. Their functions are discussed, in relation with the inflammatory response to different agents (infectious agents, mineral fibres...) and with the carcinogenic transformation, particularly in relation to asbestos exposure. The mechanisms of fibrogenesis, either symphysis or pleural plaques, are not clearly understood. The numerous studies now in progress on the different steps and mechanisms of mesothelial transformation and mesothelioma genesis are summarized focusing on the most recent cytogenetic and molecular biology findings.

Animals↗
PubMed1990

Asbestos: scientific developments and implications for public policy.

Asbestos is a commercial term for a group of fibrous minerals often associated with the development of pulmonary interstitial fibrosis (asbestosis), lung cancer, and malignant mesothelioma in occupationally exposed individuals. The pathogenicity of different forms of asbestos varies--long, thin amphibole fibers are most pathogenic, particularly in the induction of mesothelioma. Available data do not support the concept that low-level exposure to asbestos is a health hazard in buildings and schools. The concentration of asbestos fibers in air, type of asbestos, and size of fibers must be considered in evaluation of potential health risks.

Animals↗
PubMed1990

Anticarbohydrate autoantibodies to sialidase-treated erythrocytes and thymocytes in serum from patients with pulmonary sarcoidosis.

PURPOSE: The presence of immunoglobulins and complement in sarcoid granulomata and bronchoalveolar lavage from patients with sarcoidosis suggests that humoral mechanisms may be of importance in granuloma formation. To test this hypothesis, we examined the possibility that antibodies to specific tissue carbohydrates causing alterations and/or dysfunction of immunocompetent cells might be present during sarcoidosis. Because we had previously shown the presence of sialidase activity in bronchoalveolar lavage from these patients, we have looked for the presence of antibodies that recognize sialidase-treated erythrocytes (mostly antigalactose) in the serum of patients with sarcoidosis. Since thymocytes are spontaneously recognized by peanut agglutinin, a lectin that binds galactose, the reactivity of serum from sarcoidosis patients with normal or neuraminidase-treated thymocytes has also been studied. PATIENTS AND METHODS: Serum samples were obtained from the venous blood of patients with biopsy-proven sarcoidosis, most of whom had no extrathoracic symptoms. The mean patient age was 31 years, with a range from 21 to 57 years. There were 12 women and 19 men, and 10% of the patients were smokers. Sarcoidosis was classified as recent if symptoms had been present for less than 1 year and chronic if symptoms had been present for longer than this. Control serum samples were obtained from patients with idiopathic pulmonary fibrosis (n = 9) and from healthy volunteers (n = 15). Furthermore, serum from patients who had previously had sarcoidosis but in whom cures had been achieved was also studied (n = 6). RESULTS: Sialidase-treated erythrocytes were lysed in autologous serum upon incubation at 37 degrees C providing that the serum came from a patient with active disease. Serum from either normal volunteers or patients with resolved sarcoidosis had no significant cytotoxic activity. Lysis proceeded through activation of the classical complement pathway following fixation of autoantibodies. These antibodies were predominantly of the IgM class. They were able to agglutinate neuraminidase-treated thymocytes, whereas untreated thymocytes did not fix the antibodies. Carbohydrate inhibition experiments demonstrated that these antibodies are mostly galactose specific. As this sugar is located immediately below the sialic acid residues in the carbohydrate moiety of membrane glycoconjugates, it is unmasked following sialidase treatment. CONCLUSION: Since galactose has been shown to be present on the membrane of certain subsets of immunocompetent cells (e.g., lymphocytes and macrophages either spontaneously or after stimulation), it is possible that antigalactose antibodies may affect the metabolism of these cells, leading to some of the immune dysfunctions that are observed during sarcoidosis.

Adrenal Cortex Hormones↗
PubMed1990

Effects of local anaesthetics (lidocaine) on the structure and function of ciliated respiratory epithelial cells.

Sampling for nasal or bronchial ciliated cells requires the use of anaesthetic agents, but such drugs may interfere with the morphological or functional results. Lidocaine is the most frequently used local anaesthetic. In order to study the morphological and functional effects of lidocaine hydrochloride, we designed an experimental study on ciliated cells from guinea pig and bovine trachea. On guinea pig tracheal specimens, different lidocaine concentrations (0.05, 0.25 and 1%) were tested. Tracheal rings were immersed in either culture medium alone (control) or in different lidocaine concentrations. Measurements of ciliary beat frequency (CBF) were performed by the stroboscopic method. Tracheal rings were consecutively incubated in culture medium alone and a second set of measurements was performed. Tracheal rings were studied by light microscopy after incubation in either 1% lidocaine or in culture medium alone. On bovine tracheal specimens, a cotton wool swab impregnated with different lidocaine concentrations (0, 0.25, 1, 2.5 and 5%) was placed in contact with the tracheal mucosa. Three different kinds of samples were collected: the first one was used to study CBF, the second one (0.1 and 5%) was studied by scanning electron microscope (SEM) and the third (0.1 and 5%) by transmission electron microscopy (TEM). The results on guinea pig specimens show a significant but reversible CBF diminution for concentrations of 0.25 and 1% lidocaine and cellular lesions for the concentration of 1%.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Sister chromatid exchanges in human lymphocytes treated with silica.

The abilities of Min U Sil quartz or tridymite particles to induce sister chromatid exchanges (SCEs) in cultures of human lymphocytes plus monocytes or of human purified lymphocytes were investigated. With cultures of lymphocytes plus monocytes the level of SCEs was significantly enhanced after treatment with tridymite at the highest dose tested (50 micrograms/cm2). No effect was observed with purified lymphocytes. Quartz did not give clear cut results. Complementary experiments with tridymite filtrates suggested that phagocytosis of tridymite particles by monocytes was a necessary step for the induction of SCEs in human lymphocytes.

Cells, Cultured↗
PubMed1990

Interactions between cigarette smoking and the natural history of idiopathic pulmonary fibrosis.

Idiopathic pulmonary fibrosis is characterized by an inflammation of the walls of the respiratory airspaces that proceed to fibrotic alveolar derangement. Smoking habits are associated with changes in the number and the activation state of immune and inflammatory alveolar cells. Cigarette smoke could interact with the course of this disease. To evaluate the effects of smoking on IPF, 11 smokers and 16 nonsmokers were compared. Clinical presentation, PFTs, BAL cell populations, short-term glucocorticoid responsiveness and survival were evaluated. Similar PFT results were observed in both groups. Lymphocyte cells were higher in nonsmokers than in smokers. Glucocorticoid responsiveness was mainly observed in nonsmokers. Nonsmoking status was not associated with survival advantage. We conclude that the subset of IPF characterized by an aggressive onset, a BAL fluid high lymphocyte count and a substantial PFT improvement after therapy began, occurs predominantly in the absence of cigarette smoking habits.

Bronchoalveolar Lavage Fluid↗
PubMed1990

[Cost effectiveness of inpatient hospital care, day hospital care and outpatient consultation in pneumology. Apropos of 162 patients].

The authors report the results of a non-randomised study comparing the efficacy (in terms of confirmation of the diagnosis, the extent of disease, and measurements of airflow obstruction, and of the therapeutic index), and the efficiency in 58 patients suffering from lung cancer as well as 62 patients suffering from chronic airflow obstruction, and 42 asthmatics. These patients were seen in one of three possible services of a respiratory medicine department of a university hospital. The possibilities were inpatient stay in hospital, day hospital, or outpatient consultation. All the patients except one were totally independent, and could be taken into anyone of the three hospital services. The diagnostic efficacy for lung cancer was independent of the type of service used. The day hospital was four times more efficient than inpatient care for lung cancer, and consultation was 3.5 and 4.6 times more efficient than the day hospital for asthma and chronic airflow obstruction respectively. The balance of efficiency and the index of satisfaction experienced by the patients on the service used accentuated these differences.

Ambulatory Care↗
PubMed1990

[Apropos of 2 cases of hemolytic anemia in mycoplasma pneumonia].

The authors present 2 cases of mycoplasmal pneumonia associated with severe haemolysis. Haemolytic anaemia is a well-known and habitually mild complication of the disease. It is related to a peak of cold agglutinins, which are antibodies that agglutinate red blood cells usually at low temperatures but sometimes at 37 degrees C when they are present in high concentrations. The pathogenesis of cold agglutinins is thought to involve the secretion of peroxides by Mycoplasma pneumoniae with alteration of ed cell antigens which become immunogenic.

Adult↗
PubMed1989

Interactions of attapulgite (fibrous clay) with human red blood cells.

The haemolytic potential of attapulgite (Senegal) has been investigated. When the particles were pretreated with dipalmitoyl phosphatidylcholine (DPPC) or with bovine serum albumin (BSA) at a concentration that would obtain maximum coverage of the particles by adsorption, a change in haemolysis was observed. The results indicate that haemolysis is strongly dependent on the surface state of the particles.

1,2-Dipalmitoylphosphatidylcholine↗