Search PubMed⌕ Search

Biomedical subjects

L M Fabbri

Publications and source records attributed to L M Fabbri.

At least 127 records · Page 7Linked to original sources
PubMed1993

Activated T-lymphocytes and macrophages in bronchial mucosa of subjects with chronic bronchitis.

To examine the nature and the degree of leukocyte infiltration and to determine the state of activation of cells in bronchial mucosa of subjects with chronic bronchitis, bronchoscopy was performed in 10 subjects with a history of cigarette smoking and chronic sputum production and in six normal nonsmoking control subjects. Lobar bronchial biopsies were examined using histochemical and immunohistochemical techniques. Subjects with chronic bronchitis had an increased number of total leukocytes (CD45 positive cells), both in the epithelium and in the lamina propria, than did the control subjects (p < 0.05), whereas the numbers of neutrophils, eosinophils, and mast cells were similar in the two groups. There was a significant increase in the numbers of macrophages (p < 0.01) and of T-lymphocytes (CD3 positive cells) (p < 0.05) in the lamina propria of chronic bronchitics, whereas the relative proportions of CD4 and CD8 positive cells were similar in the bronchitics and the control subjects. Subjects with chronic bronchitis also had an increased expression of markers of lymphocyte activation, i.e., an increased number of interleukin-2 receptor positive cells (CD25 positive cells) (p < 0.05) and an increased number of very late activation antigen (VLA-1) positive cells (p < 0.05). In conclusion, the present study provides evidence for mononuclear cell infiltration and for T-cell activation in bronchial mucosa of subjects with chronic bronchitis, supporting the involvement of these cells in the pathogenesis of the disease.

Adult↗
PubMed1993

Mast cells in the airway mucosa and rapid development of occupational asthma induced by toluene diisocyanate.

We examined lobar bronchial biopsies taken from 18 subjects with occupational asthma induced by toluene diisocyanate (TDI) and from nine nonasthmatic control subjects. Two groups of asthmatics were identified on the basis of the duration of exposure to TDI before the onset of symptoms of asthma. Group A (n = 8) developed asthma after 2.4 +/- 0.4 yr of exposure to TDI, and Group B (n = 10) developed asthma after 21.6 +/- 3.1 yr of exposure to TDI. Both groups of asthmatic subjects had increased numbers of inflammatory cells in the airway mucosa compared with subjects in the nonasthmatic control group. Comparison between Groups A and B showed that subjects who developed asthma after short-term exposure had a significantly increased number of mast cells both in epithelium and in lamina propria than did subjects who developed asthma after long-term exposure to TDI (p < 0.01). Interestingly, the numbers of mast cells both in the epithelium (rs = -0.52, p < 0.05) and in the lamina propria (rs = -0.81, p < 0.001) were inversely correlated with the length of exposure to TDI before the onset of asthma. In conclusion, subjects who develop asthma after short-term exposure to TDI have an increased number of mast cells in the airway mucosa, suggesting that these cells may be associated with individual susceptibility differences to offending agents.

Adult↗
PubMed1993

Effects of inhaled beclomethasone on airway responsiveness in occupational asthma. Placebo-controlled study of subjects sensitized to toluene diisocyanate.

We investigated the effect of 5 months of treatment with inhaled beclomethasone dipropionate (BDP) on the airway responsiveness to methacholine (PD20 FEV1) and to toluene diisocyanate (TDI) in 15 sensitized asthmatic subjects who had been removed from occupational exposure to TDI. After the diagnosis was established by a positive inhalation challenge with TDI, each subject was removed from occupational exposure to isocyanates and treated with either BDP (1 mg twice per day, n = 7) or placebo (n = 8) for 5 months. The study was double blind for parallel groups. P20 FEV1 methacholine was measured before and three times during treatment and then at 6 months, that is, 4 wk after cessation of treatment. Airway sensitivity to TDI was assessed with specific inhalation challenge before treatment and at 6 months. Beclomethasone reduced the airway hyperresponsiveness to methacholine but did not affect the response to TDI. In fact, in the subjects on BDP, P20 FEV1 increased from 0.145 to 0.485 mg (p < 0.05) after 2 months of treatment. A further increase was observed at 4 and 5 months (0.548 and 0.629 mg, respectively, p < 0.01), and the improvement in nonspecific airway responsiveness was maintained after a 1-month washout period (0.637 mg, p < 0.01). In contrast, in the subjects on placebo, P20 FEV1 did not change significantly. At the end of the study, the severity of asthmatic reactions induced by bronchial challenge with TDI was significantly reduced in both groups, but no differences were observed between placebo and BDP.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

Identification of epithelial cells in bronchoalveolar lavage.

1. Damage to the bronchial epithelium occurs after the inhalation of toxic substances and allergens, and through virus infections and it may lead to increased desquamation of epithelial cells in bronchoalveolar lavage (BAL). 2. In this study we compared two methods of staining the epithelial cells of BAL, the conventional cytochemical May Grunwald-Giemsa stain (MGG) and an immunocytochemical technique using a monoclonal antibody anti-human cytokeratin (CK) detected with APAAP immuno-alkaline phosphatase. BAL was obtained from 13 subjects and the epithelial cells were cytocentrifuged either immediately after collection (fraction A) or after washing (fraction B). 3. Higher percentages of epithelial cells were identified in fraction A with CK (20.0 +/- 5.1%) than in fraction A with MGG (11.2 +/- 2.3%), which recognized only ciliated epithelial cells. In fact a proportion of CK-positive cells (34%) in fraction A were not ciliated. Underestimation of epithelial cells by MGG compared to CK was more pronounced in fraction B (8.0 +/- 2.9% and 22.9 +/- 3.0%, respectively) as there was a relative loss of ciliated CK+ cells after washings. 4. These results suggest that immunocytochemical staining with an anti-cytokeratin monoclonal antibody is more sensitive than using the MGG stain in detecting epithelial cells in BAL.

Adolescent↗
PubMed1992

The products of the reaction between toluene diisocyanate and water contract isolated guinea pig bronchi.

We have investigated the ability of the products of the reaction between toluene diisocyanate (TDI) and water to contract bronchial smooth muscle. The experiments were performed in isolated guinea pig bronchi. TDI, both 2,4- and 2,6-toluenediamine (TDA) and mixtures of 2,4- and 2,6-TDA (ratio 80:20 and 20:80) caused concentration-dependent contraction in the isolated bronchi. The mixture of disubstituted urea and biuret also contracted the bronchi, but not in a concentration-dependent fashion. Our results provide evidence that all products of the reaction between toluene diisocyanate and water have the ability to contract isolated bronchial smooth muscle in guinea pigs. Whatever the role of toluenediamine in the adverse respiratory effects induced by exposure to isocyanates, our findings reveal the necessity of in vivo studies on the metabolism of inhaled toluene diisocyanate in humans to improve our understanding of the mechanism of action of isocyanates.

Animals↗
PubMed1992

Theophylline inhibits late asthmatic reactions induced by toluene diisocyanate in sensitised subjects.

Toluene diisocyanate (TDI)-induced asthma is a frequent occupational airway disease. To determine whether a calibrated dosage of oral slow-release theophylline inhibits asthmatic reactions and the associated increase of airway responsiveness to methacholine induced by TDI, we examined six asthmatic subjects who developed a late or a dual asthmatic reaction after TDI inhalation challenge. We administered oral slow-release theophylline or placebo to each subject for 7 days according to a double-blind, randomized, cross-over study design. When the subjects received a placebo, TDI caused a late or a dual asthmatic reaction. When the subjects received theophylline. TDI caused significantly reduced late asthmatic reactions. Mean serum theophylline concentrations were within the therapeutic range. Theophylline neither modified the baseline airway responsiveness to methacholine, nor the increase of airway responsiveness to methacholine induced by TDI. These results suggest that slow-release theophylline may improve TDI-induced late asthmatic reactions, but it does not change the baseline airway responsiveness to methacholine and the increase of airway responsiveness to methacholine induced by TDI.

Administration, Inhalation↗
PubMed1992

Activated T-lymphocytes and eosinophils in the bronchial mucosa in isocyanate-induced asthma.

We have studied the phenotype and activation status of leukocytes in the bronchial mucosa in patients with isocyanate-induced asthma. Fiberoptic bronchial biopsy specimens were obtained from nine subjects with occupational (five toluene- and four methylene diisocyanate-sensitive) asthma, 10 subjects with extrinsic asthma, and 12 nonatopic healthy control subjects. Bronchial biopsy specimens were examined by immunohistology with a panel of monoclonal antibodies and the alkaline phosphatase-antialkaline phosphatase method. There was a significant increase in the number of CD25+ cells (interleukin-2 receptor-bearing cells, presumed "activated" T-lymphocytes; p less than 0.01) in isocyanate-induced asthma compared with that of control subjects. There were also significant increases in major basic protein (BMK-13)-positive (p less than 0.02) and EG2-positive (p less than 0.01) cells that represent total and "activated" eosinophil cationic protein-secreting eosinophils, respectively. In agreement with our previous findings, CD25+ (p less than 0.01), BMK-13 (p less than 0.03), and EG2+ (p less than 0.01) cells were also elevated in extrinsic asthma. No significant differences were observed in the numbers of T-lymphocyte phenotypic markers (CD3, CD4, and CD8) between subjects with asthma (isocyanate-induced and extrinsic) and control subjects. Similarly, no significant differences in immunostaining for neutrophil elastase (neutrophils) or CD68 (macrophages) were observed. The results suggest that isocyanate-induced occupational asthma and atopic (extrinsic) asthma have a similar pattern of inflammatory cell infiltrate. The results support the view that T-lymphocyte activation and eosinophil recruitment may be important in asthma of diverse etiology.

Adult↗
PubMed1992

Increase in vascular permeability produced in rat airways by PAF: potentiation by adrenalectomy.

1. The effect of bilateral adrenalectomy on the sensitivity of blood vessels in rat airways to mediators that increase vascular permeability was examined. 2. An increase in vascular permeability was induced by intravenous platelet activating factor (PAF, 50, 100, 500, 1000 ng kg-1) and measured by quantifying the extravasation of Evans blue dye. 3. PAF consistently increased the amount of Evans blue extravasation in the larynx, trachea, main bronchi and intrapulmonary airways in sham-operated rats. 4. The magnitude of this extravasation was significantly greater in the larynx (P less than 0.05), trachea (P less than 0.05) and main bronchi (P less than 0.05) of the adrenalectomized rats than it was in these tissues of the sham-operated rats. 5. When adrenalectomized rats were given subcutaneous dexamethasone (0.2 mg kg-1 4 h before PAF) the amount of plasma extravasation produced by PAF was decreased to the level of the sham-operated rats. 6. We conclude that adrenalectomy potentiates the increase in airway vascular permeability induced by PAF in rats and that this effect may be due to the depletion of endogenous corticosteroids.

Adrenalectomy↗
PubMed1992

Airway mucosal inflammation in occupational asthma induced by toluene diisocyanate.

We examined the light and electron microscopic structure of lobar bronchial biopsies of nine subjects with occupational asthma induced by toluene diisocyanate (TDI) and of four control nonasthmatic subjects who had never been exposed to TDI. Inflammatory cell numbers were separately assessed in the intact epithelium, in the more superficial layer of the submucosa, and in the total submucosa. Asthmatic subjects had an increased number of inflammatory cells in the airway mucosa compared with control subjects. Eosinophils were significantly increased in all compartments, CD45-positive cells were significantly increased in the epithelium and in the more superficial layer of the submucosa, and mast cells were significantly increased only in epithelium. By electron microscopy eosinophils and mast cells appeared degranulated only in asthmatic patients. In the areas of epithelium that appeared intact by light microscopy, electron microscopy showed that, although the intercellular spaces between columnar cells were similar in asthmatic and control groups, the intercellular spaces between basal cells were significantly wider in patients with asthma. Patients with TDI-induced asthma also had a thicker subepithelial reticular layer, where immunohistochemistry showed the presence of collagen III. In conclusion, in patients with asthma induced by TDI, the airway mucosa shows pathologic features, such as inflammatory cell infiltrate and thickening of subepithelial collagen, similar to those described in atopic asthma.

Adolescent↗
PubMed1992

Effect of cessation of exposure to toluene diisocyanate (TDI) on bronchial mucosa of subjects with TDI-induced asthma.

The effect of cessation of exposure to toluene diisocyanate (TDI) was studied in six patients with TDI-induced asthma, proved by a positive inhalation challenge with TDI. Bronchial challenges with TDI and methacholine were performed, and lobar bronchial biopsies were taken at diagnosis and 6 months later, after cessation of exposure. Biopsies from four nonasthmatic control subjects were also examined. At diagnosis, asthmatic subjects had thickened reticular basement membrane (p less than 0.05) and increased numbers of mononuclear cells (p less than 0.05) and eosinophils (p less than 0.05) in the lamina propria when compared with control subjects. Electron microscopy showed degranulation of eosinophils and mast cells in asthmatics. Six months after cessation of exposure, the thickness of reticular basement membrane was significantly reduced compared with that at diagnosis (p less than 0.05), and it decreased to values similar to those of control biopsies. Inflammatory cell numbers in bronchial mucosa of asthmatic subjects did not change significantly 6 months after removal from exposure, and degranulation of eosinophils and mast cells was still present. At the end of the study, airway hyperresponsiveness to methacholine and/or sensitivity to TDI persisted in most of the asthmatic patients despite the cessation of exposure and the disappearance of asthmatic symptoms. In conclusion, in patients with occupational asthma induced by TDI, the avoidance of exposure to the sensitizing agent for 6 months is able to reverse the reticular basement membrane thickening in the bronchial mucosa, but the inflammatory cell infiltrate, the specific sensitivity to TDI, and the nonspecific airway hyperreactivity may persist.

Adult↗
PubMed1992

The effect of phosphoramidon and epithelium removal on toluene diisocyanate-induced contractions in guinea-pig bronchi.

To evaluate the role of airway neutral endopeptidase 24.11 (NEP) and epithelium removal in the contraction of airway smooth muscle in response to toluene diisocyanate (TDI), we studied the effects of the NEP inhibitor, phosphoramidon, on TDI-induced contractions of guinea-pig bronchial rings with intact epithelium and without epithelium. In preparations with intact epithelium, phosphoramidon (10 microM) potentiated the contractile response to TDI (0.3 mM) (mean +/- SEM, 23.7 +/- 2.5% versus 67.9 +/- 10.3%, p less than 0.01). Phosphoramidon also increased TDI-induced contractions in tissues without epithelium (36.9 +/- 4.9% versus 52.5 +/- 7.1%, p less than 0.05). Removal of the epithelium increased the contractile response to TDI (23.7 +/- 2.5% versus 36.9 +/- 4.9%, p less than 0.05). These results demonstrate the response to TDI is increased in epithelium-free compared to intact bronchi and that NEP 24.11 modulates the effects of endogenously released tachykinins by TDI at all of the sites where NEP is found in the airways.

Animals↗
PubMed1991

Bronchial smooth muscle responses evoked by toluene diisocyanate are inhibited by ruthenium red and by indomethacin.

We have investigated the ability of ruthenium red, an inorganic dye with Ca2+ entry-blocking properties and a selective antagonist of capsaicin, and of indomethacin, a cyclooxygenase inhibitor, to inhibit bronchial smooth muscle responses evoked by toluene diisocyanate in guinea pigs. Previous exposure of isolated guinea pig bronchi to ruthenium red significantly decreased the response produced by toluene diisocyanate. Further, the response to toluene diisocyanate was significantly decreased by pretreatment with indomethacin. These findings provide evidence that toluene diisocyanate-induced contractions of guinea pig bronchi are produced indirectly by generation of a prostanoid that activates capsaicin-sensitive afferents via a ruthenium red-sensitive mechanism.

Animals↗
PubMed1991

Salbutamol plus beclomethasone dipropionate, but not salbutamol alone, completely prevent early and late asthmatic responses to allergen.

The effect of a week treatment with inhaled salbutamol plus placebo (S+P) vs. salbutamol combined with beclomethasone dipropionate (S+BDP) on early and late asthmatic responses to inhaled allergen was studied in ten atopic patients in a randomized, double-blind, cross-over study. All patients had previously shown a dual type response to the specific bronchial provocative test (sBPT). Each patient performed two periods of treatment for a week, with a 15 day interval between them: (a) salbutamol 0.3 mg, tid + placebo; (b) salbutamol 0.3 mg+BDP 0.2 mg, tid; at the end of each treatment period, sBPT was performed and the last treatments were given 1.5-2 h before and 3-4 h after allergen challenge. S + BDP completely prevented both early and late responses to allergen, while S + P reduced but did not completely inhibit early and late responses. The difference between the two treatments was significant for early and late asthmatic responses. Non-specific bronchial hyperresponsiveness to methacholine was performed before each treatment period, after 6 days of treatment before sBPT and the day after sBPT at the end of the treatment period; there was only a mild increase in PD15FEV1 methacholine after 6 days of treatment with S + BDP in comparison with S + P treatment. These results suggest that salbutamol plus beclomethasone may be used effectively in the prophylaxis of early and late asthmatic reactions induced by allergen in sensitized subjects.

Adolescent↗