Expression of cathepsin K in the human embryo and fetus.
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Cathepsin K is a protease with high collagenolytic and elastinolytic activity. Its cellular expression was previously thought to be restricted to osteoclasts and osteoclast-mediated bone resorption. In this study, the expression of cathepsin K in the human embryo and fetus was demonstrated by immunohistochemistry, in situ hybridization, and by Northern blotting of fetal tissue extracts. Besides osteoclasts and chondroclasts and their precursors, epithelial cells of various organ systems expressed significant amounts of this enzyme. Respiratory and gastrointestinal mucosa, including bile duct epithelia and urothelia, showed high levels of cathepsin K expression. With the exception of the urothelium, showing a more homogenous expression pattern, the protease was usually accentuated in the surface cell layers of pithelia. In summary, these findings in the human embryo and early fetus demonstrated a significant expression of cathepsin K in different epithelial cell types besides osteoclasts. The functional aspects of cathepsin K expression in nonosteoclastic cells and potential conclusions on physiological and pathological conditions in the embryo-fetal or adult organism remain to be investigated. Dev Dyn 1999;216:89-95. (+info)
Regulation of T helper cell differentiation by respiratory tract dendritic cells.
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Studies on dendritic cells (DC) of the respiratory and gastric mucosae have identified an extensive network of cells that represent the predominant antigen-presenting cell type at these sites. Under steady-state conditions, respiratory tract DC (RTDC) are specialized for antigen uptake and spontaneously migrate to local lymph nodes, although in vivo transfer studies have shown that the T-cell priming activity of these cells is restricted to low-level, Th2-skewed responses. Following exposure to inflammatory stimuli, the migration of RTDC to lymph nodes is accelerated and is associated with a rapid and dramatic increase in the ability of these cells to induce both Th1- and Th2-dependent immunity. Under normal circumstances, however, responsiveness of epithelial RTDC to maturation stimuli is regulated by locally produced micro-environmental factors, including pro-inflammatory cytokines, reactive oxygen species and prostanoids. These studies have led to a greater understanding of airway DC function and their role in T helper cell differentiation and provide the basis for future studies to determine the role of the cells in the aetiology and pathogenesis of respiratory immunoinflammatory disorders. (+info)
The effects of 5-HT on cholinergic contraction in human airways in vitro.
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Inhaled 5-hydroxytryptamine (5-HT) causes bronchoconstriction in asthmatics, and 5-HT plasma levels are elevated in asthma. Electrical field stimulation (EFS) of human airways, in vitro, evokes cholinergic contraction mediated by the release of acetylcholine (Ach) from postganglionic cholinergic nerves. The present study investigates whether selective 5-HT agonists and antagonists can modulate EFS-induced cholinergic contraction in human airways in vitro. Human airways, obtained from resections for bronchial carcinoma or organ transplant donors, were suspended under 2-g tension, between two platinum wire electrodes, in carbogenated Krebs solution at 37 degrees C and EFS was applied (1-32 Hz, 50 V, 0.5 ms, 15 s every 4 min) to elicit cholinergic contractions. 5-HT (10 microM-0.3 mM) produced frequency- and concentration-dependent facilitation of cholinergic contraction, but did not displace the concentration/response curve to Ach. Tropisetron (1 microM), a 5-HT3 and 5-HT4 antagonist, completely blocked the facilitatory effect of 5-HT (100 microM), whereas both ondansetron (1 microM) and GR 125478D (1 microM), a selective 5-HT3 and 5-HT4 antagonist, respectively, also attenuated the 5-HT-induced enhancement of cholinergic contraction. This facilitatory effect of 5-HT was partially mimicked by both selective 5-HT3 (2-methyl-5-HT) and 5-HT4 (RS 67333 and 5-methoxytryptamine) agonists. Fluoxetine (10 microM), a 5-HT uptake inhibitor, had no effect on the 5-HT (10-100 microm) induced potentiation of cholinergic contraction. These findings suggest that 5-HT facilitates cholinergic contraction in human airways in vitro through stimulation of both prejunctional 5-HT3 and 5-HT4 receptors. This may implicate a role of 5-HT in asthma. (+info)
Chemoprophylaxis of influenza A virus infections, with single doses of zanamivir, demonstrates that zanamivir is cleared slowly from the respiratory tract.
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Zanamivir (4-guanidino-2,4-dideoxy-2,3-dehydro-N-acetylneuraminic acid; Relenza; GG167) is a potent and highly specific neuraminidase (sialidase) inhibitor with inhibitory activity in vivo against both influenza A and B viruses. This compound has been extensively tested in both mouse and ferret models of influenza and has recently been approved for the treatment of influenza in Europe and Australasia. The compound markedly reduces the clinical course of disease in humans when given therapeutically by inhalation directly into the respiratory tract. In addition, experimental influenza infections in phase I clinical trials have shown the benefit of giving a single prophylactic dose of zanamivir in addition to a therapeutic regime. The studies reported here were designed to determine the persistence of zanamivir, as assessed by its antiviral activity in vivo, in the respiratory tracts of infected animals. We have shown that the prophylactic administration of zanamivir, when the drug is given in a single dose by the intranasal route, can significantly reduce lung virus titers in the mouse and can reduce both viral titers and symptoms in the ferret. Whole-body autoradiographical analyses of mice have indicated a long retention time for this compound in respiratory tract tissues when it is given in a single dose by the intranasal route. These results indicate that zanamivir may have clinical value as a prophylactic agent in protecting at-risk groups from influenza virus infection. In addition, these data may be useful in the design of prophylactic protocols for humans, in that the dosing schedule may only need to be intermittent to provide protection. (+info)
Antioxidant transport modulates peripheral airway reactivity and inflammation during ozone exposure.
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We examined the effects of ozone (O(3)) and endogenous antioxidant transport on canine peripheral airway function, central airway function, epithelial integrity, and inflammation. Dogs were either untreated or pretreated with probenecid (an anion-transport inhibitor) and exposed for 6 h to 0.2 parts/million O(3). Peripheral airway resistance (Rpa) and reactivity (DeltaRpa) were monitored in three sublobar locations before and after exposure to either air or O(3). Pulmonary resistance and transepithelial potential difference in trachea and bronchus were also recorded. Bronchoalveolar lavage fluid (BALF) was collected before, during, and after exposure. O(3) increased Rpa and DeltaRpa only in probenecid-treated dogs and in a location-dependent fashion. Pulmonary resistance and potential difference in bronchus increased after O(3) exposure regardless of treatment. O(3) markedly increased BALF neutrophils only in untreated dogs. With the exception of hexanal, O(3) did not alter any BALF constituent examined. Probenecid reduced BALF ascorbate, BALF protein, and plasma urate. We conclude that 1) a 6-h exposure to 0.2 parts/million O(3) represents a subthreshold stimulus in relation to its effects on peripheral airway function in dogs, 2) antioxidant transport contributes to the maintenance of normal airway tone and reactivity under conditions of oxidant stress, 3) O(3)-induced changes in Rpa and DeltaRpa are dependent on location, and 4) peripheral airway hyperreactivity and inflammation reflect independent responses to O(3) exposure. Finally, although anion transport mitigates the effect of O(3) on peripheral airway function, it contributes to the development of airway inflammation and may represent a possible target for anti-inflammatory prevention or therapy. (+info)
Comparison of a nonradiometric liquid-medium method (MB REDOX) with the BACTEC system for growth and identification of mycobacteria in clinical specimens.
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Early identification of tuberculosis in the clinical setting is of great importance in order for specific therapy to be swiftly initiated. MB REDOX (Heipha Diagnostika), a growth-based medium without radioactive materials, was evaluated and was compared to the BACTEC system for detection of mycobacteria, including the Mycobacterium tuberculosis complex and atypical mycobacteria. MB REDOX consists of a Kirchner medium enriched with growth-promoting additives, antibiotic compounds, and a redox indicator which can be monitored to detect growth of mycobacteria with the naked eye. MB REDOX only detects growth and cannot differentiate the M. tuberculosis complex (M. tuberculosis, M. bovis, and M. africanum) from other species of Mycobacterium. Therefore, PCR-restriction fragment length polymorphism analysis (PRA) was used in this investigation to identify to the species level organisms showing positive growth with MB REDOX. Our data demonstrate the usefulness of MB REDOX for the detection of mycobacteria in clinical specimens. The rate of detection of M. tuberculosis complex with MB REDOX (84. 3%) was higher than that with the BACTEC system (68.6%). When combined with PRA for species identification, MB REDOX is easy to perform and is suited to most clinical laboratory settings for the detection and identification of mycobacteria. (+info)
Cord formation in MB/BacT medium is a reliable criterion for presumptive identification of Mycobacterium tuberculosis complex in laboratories with high prevalence of M. tuberculosis.
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We evaluated cord formation in MB/BacT broth as a rapid method for presumptive identification of the Mycobacterium tuberculosis complex. Kinyoun acid-fast-stained smears from 370 positive MB/BacT bottles were examined for the presence of serpentine cording. The smears were examined independently by two observers. Observer 1 (the supervisor of the mycobacteriology laboratory) examined all of the smears while observer 2 (a clinical microbiologist not familiar with acid-fast bacillus [AFB] microscopy) examined 148 randomly chosen smears that were read by observer 1 without knowledge of which smear was which. The sensitivity, specificity, and positive and negative predictive values of cording for the presumptive identification of M. tuberculosis read by observer 1 were 88.2, 97.4, 99.2, and 69.7%, respectively. These values were reported at 90.6, 52.3, 82.8, and 69. 7%, respectively, by observer 2. Our laboratory prevalence of M. tuberculosis among positive cultures was 78% during the time this study was conducted. At the time of positive signal of the MB/BacT bottles, the broth of the bottles had sufficient cell mass to allow for observation of the presence or absence of serpentine cording. The presence of cords in MB/BacT broth is a reliable criterion for rapid, predictive identification of the M. tuberculosis complex for laboratories with a high proportion of the M. tuberculosis complex when the smears are examined by a microbiologist who has experience with AFB staining. (+info)
Identification of MUC5B, MUC5AC and small amounts of MUC2 mucins in cystic fibrosis airway secretions.
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To investigate the genetic identities of the mucins secreted in cystic fibrosis (CF) airways, sputum was collected from five individuals. Samples were separated into gel and sol phases by high-speed centrifugation and the gel phase was extracted in 6 M guanidinium chloride. The 'insoluble' residue remaining after extraction of the gel phase was brought into solution by reduction/alkylation. Density-gradient centrifugation in CsCl revealed polydisperse distributions of sialic acid-containing mucins in the gel phase, insoluble residue and sol phase fractions and the degree of variation between the different individuals was low. Antibodies recognizing MUC5AC and MUC5B identified these mucins in each of the fractions. MUC2, however, was present only as a component of the insoluble residue from the gel which accounted for less than 4% by mass of the total mucins. MUC5B and MUC5AC from the gel phase were large oligomeric species composed of disulphide-bond linked subunits and MUC5B was present as two populations with different charge densities which are likely to correspond to MUC5B 'glycoforms'. The sol phase contained, in addition to MUC5AC and MUC5B, mainly smaller mucins which did not react with the antisera and which were probably degraded. MUC5AC appeared to be enriched in the sol, suggesting that this mucin may be more susceptible to proteolytic degradation than MUC5B. The mucins present in sputum remained broadly similar during acute exacerbation and following antibiotic treatment, although the relative amount of an acidic MUC5B glycoform was decreased during infection. (+info)