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[Reduced natural killer function in children with recurrent respiratory tract infections].

Respiratory infections are the major cause of disease in childhood in the industrialized areas of the world. This essentially depends on two factors: immunological immaturity and immunological naivety. In most cases a virus has been considered the causative agent in respiratory infection. A defect in immune responses has been described in children with recurrent respiratory infections and in particular a decrease in CD4/CD8 T lymphocyte ratio or in IL-2 and IFN-gamma production. Our results show that Natural Killer (NK) cell activity is defective in children with recurrent respiratory infections. That is particularly noteworthy since NK cells play an important role in host defense against viral infections. At present it is difficult to understand whether the NK defect is a primary defect or it is secondary to viral infections. Further studies will help to clarify whether NK decreased activity depends on a cell damage directly caused by virus or it depends on the decreased levels of cytokines.

Adolescent↗
PubMed1990

Acrolein depletes the neuropeptides CGRP and substance P in sensory nerves in rat respiratory tract.

The mammalian respiratory tract is densely innervated by autonomic and sensory nerves around airways and blood vessels. Subsets of these nerves contain a number of putative neurotransmitter peptides, such as substance P and calcitonin gene-related peptide (CGRP) in sensory nerves and vasoactive intestinal polypeptide (VIP), possibly serving autonomic functions. CGRP is also found in endocrine cells in rat airway epithelium. These peptides are all pharmacologically potent effectors of bronchial and vascular smooth muscle and bronchial secretion. Their functions in vivo are less well established. We have therefore examined the effects of inhaled acrolein, a sensory irritant, on three pulmonary neuropeptides: CGRP, substance P, and VIP. Groups of rats (n = 3 each) were exposed for 10 min to acrolein in air (Ct = 510, 1858, and 5693 mg.min/m3) or to air alone. Fifteen minutes later they were killed (pentabarbitone IP) and their respiratory tracts were dissected and fixed in 0.4% p-benzoquinone solution. Cryostat sections were stained by indirect immunofluorescence for a general nerve marker (PGP 9.5) and neuropeptides. The acrolein-treated animals had a dose-related decrease in tracheal substance P- and CGRP-immunoreactive nerve fibers compared with controls. No change was seen in total nerve fiber distribution and number (PGP 9.5) or VIP immunoreactivity, nor in CGRP-immunoreactive epithelial endocrine cells. It is concluded that the rat tracheal peptidergic nerves are a sensitive indicator of inhaled irritant substances. Their reduced immunoreactivity may be because of a release of sensory neuropeptides that could play a role in the physiological response to irritant or toxic compounds.

Acrolein↗
PubMed2004

Deposition of inhaled particles in the human respiratory tract and consequences for regional targeting in respiratory drug delivery.

Particle behavior in the human respiratory tract is well understood and can be used to (1) estimate particle deposition in all regions of the respiratory tract for any aerosol respired at any pattern, and (2) optimize targeting of all regions of the respiratory tract in respiratory drug delivery. Extrathoracic and alveolar regions can effectively be targeted with mono- and polydisperse aerosols respired steadily. Effective targeting of the bronchial region can only be achieved with bolus inhalations. When particles are suspended in a gas heavier than air, targeting the alveolar region can be enhanced.

Administration, Inhalation↗
PubMed1996

[Efficacy of sulbactam/cefoperazone in respiratory tract infections in elderly patients with underlying respiratory diseases].

We examined the clinical effect of sulbactam/cefoperazone (SBT/CPZ) on respiratory tract infections in elderly patients (from 65 to 91, average 70.8) with underlying respiratory diseases. Thirty (30) patients (25 men and 5 women) were registered and SBT/CPZ (2 g/day) divided into two doses, was administered intravenously through drip infusion. The efficacy rate was 63% (excellent in 1 patient and good in 18 patients). No significant difference in efficacy was found among patient's age groups (group 1: 65-69, group 2: 70-74, group 3: 75-79, group 4: > 80). Bacterial eradication rate was 50% (6 out of 12 strains). An adverse reaction occurred in one patient, who experienced uticaria. Laboratory abnormalities, which were increasing with their ages, were observed in 12 patients during the study. These results suggest that SBT/CPZ was effective, but we found it is important to use caution in the treatment of elderly patients on respiratory tract infections with underlying respiratory diseases.

Aged↗
PubMed2005

The clinical presentation and outcomes of children infected with newly identified respiratory tract viruses.

Numerous emerging respiratory tract viruses have been identified as significant causes of acute upper and lower respiratory tract illness in children. Human metapneumovirus is a paramyxovirus discovered in 2001 in the Netherlands, with a seasonal occurrence and spectrum of clinical illness most similar to the closely related respiratory syncytial virus. Several new members of the corona-virus family have been identified, including the truly novel agent of severe acute respiratory syndrome and others that probably have been circulating undetected. Avian influenza strains have caused numerous outbreaks with high mortality, including children, and are potential causes of pandemic influenza. Several zoonotic paramyxoviruses, including Nipah and Hendra viruses, have emerged as occasional causes of sever outbreaks of respiratory tract illness in children and adults.

Child↗
PubMed1986

Regulatory peptides of the gastrointestinal and respiratory tracts.

The gastrointestinal and respiratory tracts contain numerous regulatory peptides produced by and released from specialised epithelial cells and the organ innervation. This complex system of endocrine cells and nerves is generally called "the diffuse neuroendocrine system". Markers are now available which permit the visualisation of the diffuse neuroendocrine system or its individual components. These include antibodies to neuron-specific enolase, chromogranin, neurofilament triplet proteins, the brain protein S100 and antibodies to a variety of regulatory peptides. Peptides present in the gut and lung innervation include: vasoactive intestinal polypeptide (VIP), peptide histidine isoleucine (PHI), galanin, substance P, calcitonin gene-related peptide (CGRP), neuropeptide tyrosine (NPY), somatostatin and cholecystokinin (the latter two are also localised to endocrine cells of the gut). Bombesin-immunoreactivity is found in nerves in the gut and in endocrine cells of the foetal/neonatal lung. Neuropeptides of the gut and lung originate either from local neurons (e.g. VIP, PHI, galanin) or extrinsic neurons localised in sensory ganglia (e.g. substance P and CGRP) or the sympathetic chain (e.g. NPY). Recent studies point to the involvement of regulatory peptides in diseases of the gut and lung. These, together with detailed distribution studies, provide supportive data on the putative role of the peptides in the control of normal bowel and respiratory functions. The gastrointestinal and respiratory tracts were within the systems investigated by Feyrter during his original observations on the existence of specialised epithelial cells with a putative regulatory function (Feyrter, 1938). These "endocrine/paracrine" cells were found to be scattered in epithelial organs throughout the body. In fact, endocrine cells of the respiratory tract are frequently referred to as "Feyrter's cells". The term "regulatory peptides" was introduced as a generic term (Polak and Bloom, 1983) after the finding that active peptides are produced both by cells of the diffuse endocrine or APUD (amine precursor uptake and decarboxylation) system (Pearse, 1983) and autonomic/sensory nerves. These peptides are released into the circulation from endocrine cells or locally from nerve terminals or paracrine cells. The concept of "gut/brain" peptides was dispelled after the findings that the respiratory tract was provided abundantly with numerous active peptides produced by and released from mucosal endocrine cells and/or the innervation.

Animals↗
PubMed2004

Atypical pathogens and respiratory tract infections.

The atypical respiratory pathogens Chlamydia pneumoniae, Mycoplasma pneumoniae and Legionella pneumophila are now recognised as a significant cause of acute respiratory-tract infections, implicated in community-acquired pneumonia, acute exacerbations of chronic bronchitis, asthma, and less frequently, upper respiratory-tract infections. Chronic infection with C. pneumoniae is common among patients with chronic obstructive pulmonary disease and may also play a role in the natural history of asthma, including exacerbations. The lack of a gold standard for diagnosis of these pathogens still handicaps the current understanding of their true prevalence and role in the pathogenesis of acute and chronic respiratory infections. While molecular diagnostic techniques, such as polymerase chain reaction, offer improvements in sensitivity, specificity and rapidity over culture and serology, the need remains for a consistent and reproducible diagnostic technique, available to all microbiology laboratories. Current treatment guidelines for community-acquired pneumonia recognise the importance of atypical respiratory pathogens in its aetiology, for which macrolides are considered suitable first-line agents. The value of atypical coverage in antibiotic therapy for acute exacerbations of chronic bronchitis and exacerbations of asthma is less clear, while there is no evidence to suggest that atypical pathogens should be covered in antibiotic treatment of upper respiratory-tract infections.

Anti-Bacterial Agents↗
PubMed2005

Altered expression of immune surface markers in children with recurrent infections of respiratory tract.

Infections of the respiratory tract are very common in young children. They may affect the quality of life and have a great economic impact. On the other hand, respiratory tract infections through MALT system play a positive role in the maturation and development of the immune system. The aim of the study was to examine quantitative and qualitative changes of T and B cells and granulocytes surface molecules in 24 children with recurrent (more than 8 episodes per year) infections of the respiratory tract and in 18 healthy children. The expression of CD2, CD3, CD4, CD8 on T cells; HLA-DR, CD19, CD5/CD20 on B cells, and CD11a/CD18, CD11b/CD18, CD62L, CD16 on granulocytes from peripheral blood was evaluated by a flow cytometry method. We observed a significant increase in the CD5+/CD20+ positive cells on B cells. We also observed a decreased expression of CD11c+/CD18+ cells, CD11a, and CD62L on granulocytes. The expression of other structures on lymphocytes and the CD11b/CD18+ on granulocytes remained unchanged. CD5+/CD20+ cells constitute a filogenetically old population responsible for the production of IgM of low specificity and affinity for specific antigens. The prevalence of this fetal phenotype population may be explained as a delayed maturation of the humoral immune system leading to increased susceptibility to infections. A lower percentage of CD11a may be related to the blockade of that molecule by rhinoviruses.

Antibody Formation↗
PubMed2000

Lower respiratory tract infections in adolescents.

Lower respiratory tract infections are an important cause of morbidity and occasional mortality in adolescents. This article reviews lower respiratory tract infections by anatomic location. Laryngotracheitis, tracheitis, bronchitis, pneumonia, and parapneumonic effusions are discussed. Specific viral, bacterial, mycoplasmal, and chlamydial etiologies are discussed. The epidemiology and clinical manifestations of lower respiratory tract infections in adolescents are presented according to anatomic site. Treatment for the spectrum of lower respiratory tract infections is also reviewed. Treatment options include supportive care, humidification, corticosteroids, antivirals, antibiotics, and appropriate drainage. Appropriate drainage of parapneumonic effusions includes thoracentesis, closed-tube thoracostomy, and surgery (thoracoscopy or thoracotomy). Imaging modalities include conventional radiography, computed tomography, and ultrasonography. Emphasis is placed on the common lower respiratory tract infections that affect the normal adolescent population.

Adolescent↗
PubMed1984

Penetration of erythromycin in respiratory tract infections.

Successful treatment of respiratory tract infections with erythromycin may depend upon adequate penetration of the drug to the site of infection. The delivery of antibiotics into respiratory tract secretions is a simple passive diffusion process along a concentration gradient according to Fick's principle. A number of other factors including physicochemical characteristics of the drug and host defence mechanisms may further modify the tissue penetration. A common feature of penetration studies in respiratory tract infections is the wide range of results. This is due to the numerous variables involved in this kind of study. However, the studies performed at steady state, and after oral administration of erythromycin, show a rapid increase in drug concentrations in adenoid and tonsillar tissue homogenates and sustained levels equal to or higher than in serum. In secretions of the middle ear, paranasal sinuses and bronchiae the penetration and elimination of erythromycin is much slower. The drug levels were equal to--or in some cases even higher than--steady state serum concentrations. Fluctuations, however, were less pronounced. In lung tissue homogenates erythromycin concentrations higher than the serum levels have generally been found. In respiratory tract secretions and tissues the penetration of erythromycin is good. Sufficient levels are reached to inhibit in vitro the growth of most common pathogens involved in respiratory tract infections with the exception of some strains of Haemophilus influenzae.

Bacterial Infections↗