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[Analysis of the risk factors and drug resistance of lower respiratory tract infection by Flavobacteria].

OBJECTIVE: To investigate risk factors of 26 cases with lower respiratory tract infection caused by Flavobacteria and its antimicrobial susceptibility in vitro. METHODS: Retrospective study of the clinical materials of 26 cases of lower respiratory tract infection caused by Flavobacteria. Antimicrobial susceptibility (MIC) was determined with the method of agar dilution. RESULTS: All of 26 cases suffered from underlying diseases, among them malignant tumors were most common (31%) illness. 50% of the cases were mixed infections. Risk factors of infections were application of multiple antibiotics (81%), host immune suppression (77%), invasive manasements (31%), and prolonged hospitalization. No specific clinical manifestations and chest X-ray appearance revealed. Isolates were highly resistant to most of antimicrobial agents. Ciprofloxacin, trimethoprim-sulfamethoxazole and piperacillin are the most sensitive agents. CONCLUSIONS: Lower respiratory tract infection caused by Flavobacteria developed most commonly in patients who suffered from various underlying diseases, immunodeficiency, and longtime antibiotic overuse. Clinical isolates were highly resistant to most kinds of antimicrobial agents.

Adolescent↗

An adult model of exclusive viral wheeze: inflammation in the upper and lower respiratory tracts.

BACKGROUND: We have previously reported an experimental infection of young adults with a history of episodic and exclusive viral wheeze (EVW) using human coronavirus, in which 16 of 24 with EVW (15 atopic) and 11 of 19 healthy controls (seven atopic) developed a symptomatic cold with evidence of infection, but only those with EVW developed lower respiratory tract symptoms and increased airway responsiveness. OBJECTIVE: The aim of this study was to compare the EVW and control groups from this study for inflammatory changes occurring in the upper and lower respiratory tracts during the experimental infection, in particular, to determine whether eosinophil-driven inflammation was associated with EVW. METHODS: Nasal lavage and induced sputum were collected prior to inoculation (day 0) and 2, 4 and 17 days later. Differential cell counts were performed and supernatant was assayed for IL-8, IL-5, IFN-gamma, and eosinophilic cationic protein (ECP). RESULTS: There was no difference between the two groups in any measurement at baseline. In both groups, during colds the volume of nasal secretion increased as did leucocyte counts in both upper and lower respiratory tracts. A modest increase in nasal neutrophil count was seen in both EVW and control groups with symptomatic colds on day 2 (median (quartile) difference from baseline 5.4 (0.0, 11.0) and 1.8 (-1.1, 2.2)x10(4)/mL of secretions, respectively). The change in nasal neutrophil counts in all subjects correlated with nasal symptom scores. A significant relative increase in sputum differential neutrophil count was seen on day 4 in the EVW group with a cold but not in controls (mean difference (95% confidence interval) 20.4 (9.6, 31.1)% and 3.1 (-8.2, 14.5)%, respectively, P<0.01); however, this increase did not correlate with lower respiratory tract symptom scores. IL-8 increased in both the upper and lower respiratory tracts in both EVW and control subjects with colds, the largest change being seen on day 4 in the sputum of those with EVW (mean difference from baseline (95% confidence interval) 2.5 (0.55-4.46) ng/mL). Only modest changes were seen in IFN-gamma and no changes were seen in IL-5 or ECP. None of the results was influenced by the atopic status of the subjects in either group. CONCLUSIONS: EVW wheeze is characterized by neutrophilic inflammation in both the upper and lower respiratory tracts without eosinophilia (even in atopic subjects). IL-8 is likely to be an important chemokine in this process. Symptoms and airway responsiveness were correlated with change in neutrophils.

Common Cold↗

Postnatal maturation of mast cell subpopulations in the rat respiratory tract.

The distribution and enumeration of mast cell subpopulations within the respiratory tract of a high- and low-Ige responder rat strain was determined during postnatal development. Mast cells were identified in adjacent sections by the alcian blue (AB)/safranin (SAF) staining sequence, or using immunoperoxidase to detect the rat mast cell proteinases I (RMCPI) or II (RMCPII). At birth both mucosal mast cells (MMC) and connective tissue mast cells (CTMC) were represented in very low numbers at distinct locations throughout the respiratory tract. The total number of mast cells increased with age. MMC (AB+/RMCPII+ mast cells) were the predominant phenotype in the epithelium and lamina propria of the trachea and the major conducting airways of the lung in all age groups. In contrast, CTMC (AB+/RPMCPI+ and SAF+/RMCPI+ mast cells) predominated in the submucosa of the trachea and major conducting airways as well as in the parenchyma and visceral pleura of the peripheral lung. Both phenotypes co-exist in similar proportions in peribronchial adventitial tissue and adventitia surrounding large blood vessels in neonates as well as adults. In rats the tracheal epithelium is densely populated by MMC from around the time of weaning (3 weeks) and a small but generalized increase in the number of MMC at all sites within the respiratory tract is noted from this time. This increase in MMC frequency in tissue sections with increasing age is mirrored by the levels of circulating serum RMCPII. The number of bone marrow-derived MMC also increased with increasing age prior to weaning, with a significant drop (P less than 0.01) at 4 weeks of age before returning to the peak numbers in 3-week-old rats. The high-IgE responder Brown Norwegian (BN) rat strain constitutively produces significantly more IgE than the low-IgE responder White albino Glaxo (WAG) strain (P less than 0.001) at all ages studied. In contrast, only minor differences between the number and distribution of mast cells in the two strains were observed.

Aging↗

Anthropometric measures and risk of cancers of the upper digestive and respiratory tract.

Data from a case-control study on the upper digestive and respiratory tract cancers were analyzed to investigate the relationship with anthropometric measures. The data set included 538 oropharyngeal, 410 esophageal, and 388 laryngeal cancer cases and 2,102 controls in hospital for acute nonneoplastic diseases, unrelated to tobacco or alcohol use, recruited in the same catchment areas as the cases. Lower body weight appeared to be an indicator of oropharyngeal and esophageal cancer and, more moderately, of laryngeal cancer. The multivariate odds ratio (OR) for oropharyngeal cancer was 5.0 for subjects in the lowest compared with the highest quartile of weight. The corresponding ORs were 6.2 for esophageal and 2.2 for laryngeal cancer. When quartiles of body mass index (BMI) were considered, the ORs in the lowest quartile were 4.0 for oropharyngeal, 6.3 for esophageal, and 2.4 for laryngeal cancer. Subjects in the lowest quartile of height had ORs of 2.0 for oropharyngeal, 1.6 for esophageal, and 1.4 for laryngeal cancer. When all the upper digestive and respiratory tract neoplasms were considered together, the OR for subjects with lower BMI who were also current smokers compared with never-smokers with higher BMI was 11.4. The OR was 5.0 for those consuming six or more drinks/day and with low BMI. Although the nature of the association needs to be clarified, these data suggest that leanness may be involved in the process of upper digestive and respiratory tract carcinogenesis.

Adult↗

Significance of particle size of benzo(a)pyrene for the induction of respiratory tract tumours in hamsters.

To study the role of particle size of benzo(a)pyrene (BP) in the induction of respiratory tract tumours, goups of hamsters were given 52 weekly intratracheal instillation of fine (77% less than 5.2 micron; 3% less than 1.3 micron) or coarse (77 less than 42 micron; 0% less than 10 micron) BP particles suspended in gelatin-0.9% NaCl solution. Both the fine and coarse particles were given at two different dose levels, viz., 0.5 and 1.0 mg BP/instillation. Another group of hamsters received 52 weekly intratracheal instillations each consisting of 1.0 mg BP particles of a wide size range (90% less than 50 micron; 3% less than 5.0 micron) suspended in 0.9% NaCl solution without gelatin. The retention of BP in the respiratory tract was studied in separate groups of hamsters receiving a single instillation of BP particles of the different size ranges. Coarse BP particles cleared less rapidly from the lungs and induced a much stronger tumour response in the respiratory tract than did fine BP particles. These findings demonstrated the crucial significantce of particle size for the effectiveness of BP as a respiratory tract carcinogen. No appreciable differences in site of tumour formation were observed between treatment with fine and coarse BP particles, which led to the conclusion that the size of the particles did not play an important role in determining the location of the induced respiratroy tract tumours. The elimination rate of the BP particles with a wide size range appeared to be in between those of the fine and the coarse particles. The tumour response found after administration of the BP particles of wide size range was very similar to that obtained with the high dose of coarse PB particles.

Animals↗

Branhamella catarrhalis and croup: toxicity in the upper respiratory tract.

Branhamella catarrhalis has gained increasing recognition as a pathogen in the respiratory tract. During the past 18 years, since its transfer from the genus Neisseria, it has been associated with infection in cavities of the respiratory tract (sinuses and middle ear). It has been recognized as playing a role in laryngitis. Its isolation in large numbers from the surface and core of acutely and chronically infected tonsils indicates a possible role in these infections. Croup (two patients reported here) can now be added to this list. The toxic potential of B catarrhalis, its movement from commensal to pathogen for the upper respiratory tract, and the pathogenic mechanisms by which this has occurred are reviewed.

Bacterial Infections↗

[Value of quinolones in the treatment of lower respiratory tract infections caused by intracellular organisms, excluding mycobacteria].

In vitro studies of quinolones against intracellular pathogens responsible for lower respiratory tract infections have shown that growth inhibition varies with the strain and with the drug. Following administration of quinolones, drug levels in the lower respiratory tract are similar to or greater than serum levels. Quinolones penetrate readily into cells. The effectiveness of quinolones in lower respiratory tract infections has been demonstrated in both in vitro intracellular infection models and in vivo animal models. These data show that quinolones are a valid therapeutic alternative for lower respiratory tract infections due to intracellular organisms.

Anti-Infective Agents↗

Mycoplasma pneumoniae and other pathogens in the aetiology of lower respiratory tract infections among Japanese children.

The causes of lower respiratory tract infections in 1544 children attending a Japanese hospital over a period of 7 years were investigated. Both cultivation and two serological techniques were used to detect Mycoplasma pneumoniae whereas viral involvement was investigated only by serology. Pathogens were identified in 52% of 1175 patients with pneumonia and 36% of 369 patients without pneumonia. Mycoplasma pneumoniae infection was specifically diagnosed in 414 (26.8%) of the 1544 patients. Respiratory syncytial virus (RSV) was dominant in children up to 2 years of age. By the age of 3 years, M. pneumoniae was equalling it in incidence and became the main pathogen in older groups. It is suggested that M. pneumoniae may be more important in the 3-6 years age group than hitherto suspected. These observations may influence the choice of antibiotics for treating lower respiratory tract infections in childhood.

Adenovirus Infections, Human↗

Modifying effect of dietary fat on benzo[a]pyrene-induced respiratory tract tumours in hamsters.

Groups of 40 Syrian golden hamsters of both sexes were fed diets containing either 5% fat (control), 20% saturated fat (beef tallow) or 20% unsaturated fat (sunflower seed oil) from weaning and during the whole experimental period (up to 656 days). Respiratory tract tumours were induced by intratracheal instillation of benzo[a]pyrene attached to ferric oxide and suspended in saline. Mortality was slightly, but not statistically significantly higher in the high fat groups than in the low fat control group. Microscopic examination of the respiratory tract revealed an increased number of tumour bearing animals, an increased multiplicity of respiratory tract tumours and an increased total number of respiratory tract tumours in animals fed high fat diets. The tumour enhancing effect of fat was most pronounced in the high unsaturated fat group. Especially epidermoid papillomas, epidermoid carcinomas and combined epidermoid and adenocarcinomas contributed to the observed differences in tumour response amongst groups. It was concluded that dietary fat enhances benzo[a]pyrene-induced respiratory tract carcinogenesis in hamsters.

Adenocarcinoma↗

Recovery of gut-associated lymphoid tissue and upper respiratory tract immunity after parenteral nutrition.

OBJECTIVE: The authors characterize the recovery of parenteral nutrition-induced changes in gut-associated lymphoid tissue (GALT) and upper respiratory tract immunity with enteral nutrition and provide further information defining the effects of enteral feeding on mucosal immunity. SUMMARY BACKGROUND DATA: The small intestine plays a prominent role in development and maintenance of mucosal immunity, both intestinal and extraintestinal, primarily through immunoglobulin A (IgA)-mediated mechanisms. Prior research has shown that mice fed total parenteral nutrition (TPN) have reduced GALT T and B cells, the cells responsible for IgA production, as well as impaired upper respiratory tract immunity to viral challenge of previously immunized animals. The recovery of TPN-induced changes in GALT and upper respiratory tract immunity after enteral refeeding is studied. METHODS: Male institute of Cancer Research mice received 5 days of TPN followed by 0 to 4 days of chow. Small intestinal GALT was characterized by flow cytometry. In a second experiment, animals were immunized intranasally with moused-adapted influenza virus. Three weeks later, one group received a 5-day course of TPN followed by enteral refeeding for 5 days. A second group received TPN alone. Both groups were challenged with intranasal virus and killed 40 hours postchallenge to determine viral shedding from the upper respiratory tract. RESULTS: Animals fed TPN only had significantly fewer GALT lymphocytes compared with those chow-fed control subjects. Peyer's patch counts increased after a single day of refeeding, returning to normal levels by 48 hours. Lamina propria counts remained significantly depressed after 24 hours of refeeding, but also returned to normal after 48 hours of refeeding. The T-cell and B-cell populations mimicked total cell patterns. Lamina propria CD4+/CD8+ ratio returned to normal only after 72 hours of refeeding. None of the 9 animals refed enterally for 5 days were positive for viral shedding, compared with 8 of 12 matched TPN-fed animals. CONCLUSIONS: Enteral refeeding after TPN is associated with rapid repletion of GALT cellularity, initially within Peyer's patches and subsequently within the lamina propria. Refeeding corrects the impairment of IgA-mediated upper respiratory tract antiviral immunity occurring with TPN administration. This work further enhances the authors' knowledge of the underlying immunologic differences influenced by routes of nutrition.

Animals↗

CD4(+) T-cell-mediated antiviral protection of the upper respiratory tract in BALB/c mice following parenteral immunization with a recombinant respiratory syncytial virus G protein fragment.

We analyzed the protective mechanisms induced against respiratory syncytial virus subgroup A (RSV-A) infection in the lower and upper respiratory tracts (LRT and URT) of BALB/c mice after intraperitoneal immunization with a recombinant fusion protein incorporating residues 130 to 230 of RSV-A G protein (BBG2Na). Mother-to-offspring antibody (Ab) transfer and adoptive transfer of BBG2Na-primed B cells into SCID mice demonstrated that Abs are important for LRT protection but have no effect on URT infection. In contrast, RSV-A clearance in the URT was achieved in a dose-dependent fashion after adoptive transfer of BBG2Na-primed T cells, while it was abolished in BBG2Na-immunized mice upon in vivo depletion of CD4(+), but not CD8(+), T cells. Furthermore, the conserved RSV-A G protein cysteines and residues 193 and 194, overlapping the recently identified T helper cell epitope on the G protein (P. W. Tebbey et al., J. Exp. Med. 188:1967-1972, 1998), were found to be essential for URT but not LRT protection. Taken together, these results demonstrate for the first time that CD4(+) T cells induced upon parenteral immunization with an RSV G protein fragment play a critical role in URT protection of normal mice against RSV infection.

Adoptive Transfer↗

[Bacteriological and mycological analysis of material taken from lower respiratory tract in patients with malignancy].

UNLABELLED: The immunosuppression and incorrect function of the natural protection mechanisms are conducive to lower respiratory tract infections. The patients with malignancy, especially with lung cancer, belong to the group at higher risk to develop an infection due to accumulation of numerous risk factors. OBJECTIVE: The aim of this study was to assess the occurrence of bacteria and fungi in materials taken from lower respiratory tract from the patients treated in Thoracic Surgery and Clinical Department of Thoracic Surgery and Tumours from 2000 to 2004. The frequency of occurrence of alert-pathogens was also analyzed. MATERIAL AND METHODS: The retrospective analysis was carried out among 102 positive samples (sputum--68, bronchial secretion--32 and bronchoalveolar lavage--2). The material was obtained from patients treated due to lung cancer (n=84), pulmonary metastases (n=6), primary neoplasms of the chest wall (n=2), lymphoma of the mediastinum (n=3), mesothelioma (n=1) and other malignancies (n=6). The examinations were conducted in compliance with the current procedures, generally accepted in microbiological laboratories. RESULTS: Seventy examined patients (68.63%) had bronchial colonization with bacteria being the potential etiologic agents of lower respiratory tract infections. The presence of yeast-like fungi was confirmed in 62 patients (60.78%). The most frequent strains isolated were: Enterobacteriaceae (40.86%), followed by Staphylococcus aureus (21.51%), Haemophilus influenzae (16.13%) and Streptococcus pneumoniae (7.53%). The nonfermenting gram-negative rods Pseudomonas spp. and Acinetobacter spp. occurred as follows: 6.45% and 3.23%. Among yeast-like fungi the most common species isolated was Candida albicans (63.77%) which occurred more frequently in sputum than in bronchial secretion (p < 0.0004). The strains of Enterobacteriaceae and nonfermenting gram-negative bacillus producing extended-spectrum beta lactamase (ESBL) were not discovered like MBL (metallo- beta lactamase) positive strains. All of the Staphylococcus aureus strains were sensitive to the methicillin. Haemophilus influenzae did not show ampicillin resistance. We observed two strains Streptococcus pneumoniae which were penicillin intermediate but susceptible to the third-generation cephalosporins. CONCLUSIONS: Identification of the potential etiological agents of lower respiratory tract infections can be useful in the rational management of the antibiotics policy in the patients with maliganacy.

Bronchoalveolar Lavage Fluid↗

Nosocomial respiratory tract infection and colonization with Acinetobacter calcoaceticus. Epidemiologic characteristics.

Nosocomial respiratory tract infection with Acinetobacter calcoaceticus occurs frequently in many hospitals. An outbreak of respiratory tract infections in an intensive care unit provided an opportunity to study clinical and epidemiologic characteristics of such infections. Retrospective studies demonstrated that A. calcoaceticus in sputum was significantly associated with endotracheal intubation (p = 0.03) and continuous positive pressure ventilation (p less than 0.02). After control measures had interrupted the outbreak, a prospective microbiologic investigation demonstrated that one third of the hospital personnel had transient hand colonization with multiple strains of A. calcoaceticus. Pharyngeal, vaginal and rectal carriage was rare. A pulmonary therapist with chronic dermatitis had persistent hand colonization with the epidemic strain, and he contaminated respiratory therapy equipment. Cross contamination of respiratory therapy equipment occurred while in use, but no other inanimate reservoir was demonstrated. Although previous studies have implied that the inanimate hospital environment has unique reservoirs of A. calcoaceticus, these reservoirs were not implicated in this outbreak. Human skin must be considered an important reservoir of A. calcoaceticus.

Acinetobacter↗

Amoxicillin/clavulanate therapy of respiratory tract infections: a microbiologic perspective.

The development of beta-lactamase-producing strains of the common respiratory tract pathogens Hemophilus influenzae and Moraxella catarrhalis has caused increasing resistance to a number of antimicrobial agents, including ampicillin and amoxicillin, that are traditionally used to treat respiratory tract infections. Because antimicrobial therapy for upper and lower respiratory tract infections is usually empiric, an understanding of beta-lactamase-mediated resistance and its implications for antibiotic therapy is critical for the successful treatment of these infections.

Amoxicillin↗

Sites for xenobiotic activation and detoxication within the respiratory tract: implications for chemically induced toxicity.

Results of in situ immunohistochemical investigations on several enzymes which participate in the bioactivation and detoxication of xenobiotics and of histochemical studies on aryl hydrocarbon hydroxylase activity summarized in this report clearly demonstrate that there are numerous sites within the respiratory tract at which xenobiotics can be bioactivated and detoxicated. The data presented, however, also reveal that xenobiotic-metabolizing enzymes and benzo[a]pyrene hydroxylase activity may not be distributed uniformly within individual segments (e.g., the nasal mucosa) of this organ system. Thus, it should be apparent from these findings that one cannot generalize as to how a given xenobiotic-metabolizing enzyme or xenobiotic monooxygenase activity normally is distributed either within or among the different segments of the respiratory tract. Additionally, since enzymes catalyzing the bioactivation and detoxication of xenobiotics usually are present within the same respiratory tract cells, it obviously is difficult to predict from these results which cell types within individual segments of this organ system most likely would be damaged as a consequence of exposure to xenobiotics which are biotransformed into cytotoxic metabolites by cytochrome(s) P-450. Although the cellular localizations and intercellular distributions of cytochromes P-450 BNF-B and MC-B parallel those of benzo[a]pyrene hydroxylase activity within the different segments of the respiratory tract in untreated rats, immunohistochemical findings on the inductions of these cytochrome P-450 isozymes are not entirely consistent with histochemical observations on the enhancement of benzo[a]pyrene hydroxylase activity by Aroclor 1254 within the nasal mucosa and by both Aroclor 1254 and 3-methylcholanthrene within the lung. It must be appreciated, however, that other cytochrome P-450 isozymes undoubtedly are present and inducible in the nasal mucosa and lung and, further, that these hemeproteins, although being immunochemically unrelated to the cytochrome P-450 isozymes studied, also could catalyze aryl hydrocarbon hydroxylase activity. Nevertheless, these immunohistochemical and histochemical findings do demonstrate that one cannot generalize as to how chemicals which induce the same xenobiotic-metabolizing enzyme will affect that enzyme within different segments of the respiratory tract and, moreover, that inducers of cytochromes P-450 can alter differentially the extents to which different cells within a given segment of the respiratory tract (e.g., the nasal mucosa) participate in the oxidative metabolism of xenobiotics.

Animals↗

Influenza vaccination in patients with asthma: effect on the frequency of upper respiratory tract infections and exacerbations.

Influenza epidemics of variable extent and severity occur every winter and are frequently associated with exacerbations of asthma. Accordingly, annual vaccination against influenza is recommended for patients with asthma. However, there are very limited data concerning its protective effect in this group of patients. The aim of this study was to assess the effect of influenza vaccination on the frequency of upper respiratory tract infections and also asthma-related outcomes such as exacerbation rates, hospital admissions, and rescue courses of oral corticosteroids in patients with stable asthma. Between September 15 and November 7, 2001, a total of 128 patients with asthma were randomly assigned to receive (n = 86) and not to receive vaccine (n = 42). The primary outcome measures were frequency of upper respiratory tract infections and exacerbations of asthma during the winter following vaccination. Study subjects were asked to record the presence and duration of symptoms suggestive of an upper respiratory tract infection and call their physician in the presence of conditions suggestive of an exacerbation until March 2002. Among the vaccinated group, 48% of the patients reported that they had no upper respiratory tract infection during the winter following injection, whereas 57% of nonvaccinated participants were upper respiratory symptom free during the same period (p > 0.05). The frequency of upper respiratory tract infection was also not different between the two groups in all severity forms of asthma (p > 0.05). There was no significant difference in the frequency of exacerbations of asthma between the two groups during the study period (p > 0.05). None of the vaccinated group was hospitalized due to an asthma attack; however, two patients (4.8%) in the nonvaccinated group had to be hospitalized following an exacerbation (p > 0.05). In summary, our findings do not support the protective effect of influenza vaccination for patients with asthma. However, no firm conclusions on this effect of the vaccine can be made without the data on the rate of influenza epidemic in that season and without the knowledge of the cause of upper respiratory tract infections in those patients. Therefore, we believe randomized, double-blind, placebo-controlled studies, including larger subgroups of severe asthmatics, are needed to evaluate the protective effect of influenza vaccination in asthma.

Adult↗

[Recurrent respiratory tract infections: how should we investigate and treat?].

Recurrent respiratory tract infections are a common reason for visits to primary care practitioners or hospital physicians. They are placed at the junction of several medical specialities: paediatrics, ENT, pneumology, allergology, immunology, infectiology. The great diversity of the laboratory tests requested and on the other hand the proposed treatments, are the consequences of the diversity of the patients encountered and the paucity of the evidence based-medicine studies in this setting. The dilemma is how to identify the child for which recurrent respiratory tract infections are the witness of underlying condition, without performing repeated medical examinations, laboratory tests and treatments for normal children for which immunologic development occurs normally. The essential tools are the history analysis, physical examination and few laboratory tests. The other questions are how to include, for these patients, influenza and pneumococcal vaccines in the immunization program and how to assess the benefit/risk ratio and the cost of surgical treatments. This paper presents the thought of an expert group trying to define the situations where biological tests or treatments are useful.

Child↗

Distribution of capsaicin-sensitive substance P- and calcitonin gene-related peptide-immunoreactive nerves in bovine respiratory tract.

The distribution of nerve fibers immunoreactive for substance P (SP) and calcitonin gene-related peptide (CGRP) was examined by means of immunohistochemical methods in the respiratory tract from nose to lung of normal and capsaicin-treated cattle. SP- and CGRP-immunoreactive (IR) nerve fibers with varicosities were detected in all portions. They were more numerous in calves than in cows. They were abundant in the nasal and laryngeal mucosae and tracheal bronchus, and few in number in the lung. SP- and CGRP-IR nerve fibers were mainly seen in the epithelium, in connective tissue beneath the epithelium and around blood vessels, and in the glands throughout the respiratory tract. In contrast, SP- and CGRP-IR nerve fibers were sparse in the smooth muscle layer. Capsaicin treatment of neonates caused a remarkable reduction in the number of SP- and CGRP-IR nerve fibers in the respiratory tract of calves. Double immunofluorescence experiments showed the colocalization of SP and CGRP in most of the nerve fibers. The present findings suggest that SP- and CGRP-IR nerve fibers are involved in the regulation of the bovine respiratory tract, and that capsaicin-sensitive SP- and CGRP-IR nerve fibers are sensory neurons of the bovine respiratory tract.

Aging↗