Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:2.7.7.49 (reverse transcriptase)
31,746 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The reverse transcriptase-polymerase chain reaction and the nested polymerase chain reaction were used for detection of respiratory syncytial virus (RSV) sequences in middle ear effusions collected from children with otitis media. Sequences of RSV were detected in 21 of 34 samples tested. These samples were collected during and/or after natural outbreaks of RSV infection in the community. In those patients from whose nasopharynges RSV was isolated, the viral sequences were highly detectable (75%) in the effusions. These observations suggest RSV as an important factor in the pathogenesis of otitis media with effusion.
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PMID:Detection of genomic sequences of respiratory syncytial virus in otitis media with effusion in children. 141 57

The most frequent viruses associated with respiratory infections are human rhinoviruses (HRVs). Although the majority of HRV infections are mild and self-limited, HRV is an important cause of respiratory disease across all age groups. Recent studies using reverse transcriptase polymerase chain reaction to detect HRV genomes have established the importance of HRVs in predisposing to or causing otitis media, sinusitis and exacerbations of asthma, as well as other lower respiratory tract disorders. Among elderly people, infants and immunocompromised hosts HRV infections are often associated with lower respiratory tract morbidity and rarely mortality. How often active viral replication occurs in the middle ear, sinuses or the lower respiratory tract remains to be determined. However, the high incidence of HRV infections and their frequent association with upper and lower respiratory tract complications highlight the need for more effective means of prevention and treatment.
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PMID:Rhinoviruses: important respiratory pathogens. 992 Mar 54

In the present study, pulmonary surfactant protein A (SP-A) messenger RNA (mRNA) and protein were characterized in adult rabbit middle ear and maxillary sinus. Fifteen adult rabbits were used for the study: 6 with evidence of acute middle ear infections and maxillary sinusitis, 6 with infections that were successfully treated with tetracycline, and 3 that were pathogen-free. We detected SP-A mRNA in maxillary sinus and middle ear tissues by Northern blot analysis and reverse transcriptase-polymerase chain reaction (RT-PCR). The RT-PCR also revealed the presence of SP-B and SP-C mRNA in middle ear and sinus tissues. We detected SP-A protein, of molecular weight approximately 29 and 70 kd, in middle ear and sinus tissues by immunoblot analysis. Unlike the SP-A protein present in the lung, the molecular weight of the SP-A protein present in the middle ear and paranasal sinus was not altered by digestion with an enzyme that cleaves N-linked carbohydrates. Immunostaining and in situ hybridization showed that SP-A protein and mRNA, respectively, were present in surface epithelial cells of the middle ear and in epithelial cells of submucosal glands in sinus tissues. These data provide the first evidence of the presence of pulmonary surfactant proteins in the paranasal sinuses and confirm previous reports of SP-A in the middle ear epithelium.
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PMID:Surfactant protein A in rabbit sinus and middle ear mucosa. 1052 45

For the advanced study of the cell and molecular biology of middle ear mucosa, an in vitro cell culture system is required. Although middle ear epithelial cells have been cultured from various species of laboratory animal, there have been no reports concerning a serial subculture system of human middle ear epithelial cells. In this paper, we describe the establishment of a primary culture system of human middle ear epithelial cells using a serum-free conditioned medium and the characterization of these cells by the expression of phenotypic characteristics of epithelial cells and mucin genes. Cultured cells were anchorage-dependent in terms of growth and showed a polygonal cobblestone-like appearance: desmosomes in the cell junction were observed by electron microscopy. In the immunocytochemical study, cytokeratin (epithelial cell marker) was expressed in all cultured cells. but von Willebrand factor (endothelial cell marker) was not. Unexpectedly, vimentin (fibroblast marker) was locally expressed, and a double stain showed the co-expression of both cytokeratin and vimentin in the same cell. The products of reverse transcriptase polymerase chain reaction from cultured cells yielded distinct bands compatible with the expected sizes of the MUC1, MUC2, MUC5AC and MUC5B genes. This culture system will allow us to prepare the cell line and to perform advanced studies of human middle ear mucosal biology.
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PMID:Mucin gene expression in cultured human middle ear epithelial cells. 1120 May 87

Tympanosclerosis is a condition leading to a calcification process in the middle ear, and often develops after chronic inflammation of the middle ear. Since osteopontin (OPN) has been shown to participate in the pathological calcification, we here investigated whether OPN is involved in the process of calcification in tympanosclerosis. The tympanic membrane and middle ear mucosa, obtained from patients of tympanosclerosis and chronic otitis media, were histologically classified depending on the calcification degree. In hyalinized tissues with macroscopic calcification and fibrous tissues with microscopic calcification, OPN was immunohistochemically found in the calcification sites. In inflammatory tissues with microscopic calcification, OPN was also found in the calcifying foci, and many OPN mRNA-expressing cells, determined by in situ hybridization, located around their foci. Moreover, immunohistochemical double staining of OPN and CD68 showed that the OPN-expressing cells were CD68-positive, indicating these cells were macrophages. In inflammatory tissues without calcification, immunohistochemistry of CD68 and in situ hybridization of OPN mRNA revealed that most OPN mRNA-expressing cells were CD68-positive. The expression of OPN mRNA in inflammatory tissues was also shown by reverse transcriptase polymerase chain reaction. These results suggest that OPN secreted by exudate macrophages might be an important regulator in the calcification of tympanosclerosis.
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PMID:Expression of osteopontin by exudate macrophages in inflammatory tissues of the middle ear: a possible association with development of tympanosclerosis. 1122

Hypersecretion of mucin is a common feature of chronic and mucoid otitis media which may play an important role in hearing loss. The mechanisms controlling mucin secretion in the middle ear are not completely understood. Our reverse transcriptase-polymerase chain reaction results demonstrate that mRNAs of MUC1, MUC2, MUC3, MUC4 and MUC5AC are expressed in normal rat middle ear mucosa. Moreover, the expression of mRNA of the secretory mucins MUC2, MUC3 and MUC5AC was threefold lower in normal middle ear mucosa than that in the intestine or trachea. In contrast, expression of the membrane-bound mucins MUC1 and MUC4 was approximately the same in both middle ear mucosa and the intestine or trachea. MUC5AC proteins were also identified immunohistochemically in normal rat middle car epithelium. The methodology used in this study provides useful baseline information for investigation of the mechanisms of regulation of mucin gene expression during otitis media.
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PMID:Detection of mucin gene expression in normal rat middle ear mucosa by reverse transcriptase-polymerase chain reaction. 1127 Apr 93

We investigated the expression levels of MUC5AC in endotoxin-induced otitis media with effusion (OME) in the rat using competitive polymerase chain reaction (PCR) and the morphology of middle ear mucosa using transmission electron microscopy (TEM). Experimental OME in the rat was induced after middle ear instillation of Escherichia coli lipopolysaccharides (LPS). Middle ear mucosa were obtained at 0 h, 12 h, Day 1, Day 3, Day 7 and Day 14 and reverse transcriptase (RT)-PCRs were then performed for the identification of MUC1, MUC2, MUC5AC and submandibular mucin 1 expression, followed by competitive PCRs for MUC5AC and beta2-microglobulin expression. Normal middle ear mucosa revealed no expression of mucin genes, whereas endotoxin upregulated the expression of MUC5AC mRNA between 12 h and Day 7, with maximal expression at Days 1 and 3. Middle ears treated three times with LPS upregulated more MUC5AC mRNA expression, by a factor of approximately 3.5, than those 1 day after one instillation. On TEM, dark granulated cells were observed at Day 3 after endotoxin instillation, but mixed granulated cells were seen on the ears treated three times with LPS. These results suggest that MUC5AC could be one of the major mucin genes in the middle ear mucosa related to otitis media.
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PMID:Up-regulation of MUC5AC mRNA expression in endotoxin-induced otitis media. 1142 2

The production of nitric oxide (NO) within the middle ear has not previously been characterized. The presence of NO synthase (NOS) transcripts was demonstrated using RNA amplification by reverse transcriptase-polymerase chain reaction in rat middle ear mucosa and in rat primary cultured middle ear epithelial cells. The expression of NOS was indirectly assessed by nitrite measurement in the supernatant of primary cultured cells. The effect of NO on ion transport was investigated in a previously described middle ear epithelial cell line using the short-circuit current (Isc) technique. NO per se had no effect on Isc. However, previous work has shown that sodium transport is stimulated by reactive oxygen species (ROS). NO blunted this stimulation, an inhibition probably related to the toxicity of peroxynitrite, ONOO-, a highly reactive compound. These results suggest that NO is produced by middle ear epithelial cells and that, in the presence of ROS, NO may be responsible for an inhibition of ion transport viaperoxynitrite formation.
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PMID:Production of nitric oxide by the middle ear epithelium and subsequent inhibition of sodium transport. 1142 3

Four-to-seven-week-old broilers with swollen head syndrome (SHS) from 4 different districts of Japan were examined for pathological, microbiological and biochemical findings. Periocular and mandibular subcutaneous swelling, sometimes accompanied by ocular, hepatic and cardiac lesions were observed. Histologically, diffuse fibrinopurulent inflammation with focal granulomatous lesions was characteristic of subcutaneous tissue of the head, especially periocular tissue. The air spaces of the cranial bones and middle ear showed fibrinopurulent inflammation. Upper respiratory lesions (rhinitis, sinusitis and tracheitis) were always present in chickens with SHS. The characteristic lesions of chicken colibacillosis, i.e. fibrinopurulent serositis, panophthalmitis, fibrinous thrombi in sinusoids of the liver and fibrinous exudation in the ellipsoids and lymphoid follicles of the spleen, were occasionally seen. No virological agents could be isolated. Turkey rhinotracheitis (TRT) virus gene was detected in tracheas from two flocks by reverse transcriptase polymerase chain reaction and serum antibodies against TRT virus were present. Escherichia coli and Staphylococcus aureus were isolated from subcutaneous lesions. Serum alpha(1)-acid glyco-protein, an acute phase protein, was present at high concentration in chickens with SHS. This study suggests that upper respiratory lesions induce E. coli invasion into subcutaneous connective tissue adjacent to the infraorbital sinus and nasal cavity, and SHS in this study may possibly be a local infection of E. coli in facial subcutaneous connective tissue.
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PMID:Swollen head syndrome in broiler chickens in Japan: Its pathology, microbiology and biochemistry. 1848 97

The hypoxia-inducible factor and vascular endothelial growth factor (HIF-VEGF) pathway in hypoxic conditions of the middle ear due to dysfunction of the eustachian tube is still unknown, but it is considered as one pathogenetic mechanism in otitis media. This study was designed to investigate the possible involvement of the HIF-VEFG pathway in otitis media with effusion induced by dysfunction of the eustachian tube. We adopted a soft palate approach to obstruct the orifice of the eustachian tube to establish otitis media in a rat model. Auditory evoked brainstem response and tympanometry were used as hearing function tests, hypoxia-related factors were examined by reverse transcriptase polymerase chain reaction (RT-PCR). The expression of hypoxia-related proteins was detected by Western blot and immunostaining. The model of otitis media with effusion was successfully induced by cauterizing the orifice of the eustachian tube. RT-PCR showed up-regulation of hypoxia-related factors in cauterized ears. Western blot and immunostaining showed that the expression of hypoxia-related proteins in cauterized ears was increased. Hypoxia-induced vascular proliferation and an increase in permeability may be one pathogenetic mechanism of otitis media due to dysfunction of the eustachian tube.
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PMID:Hypoxia-inducible factor and vascular endothelial growth factor pathway for the study of hypoxia in a new model of otitis media with effusion. 2290 20


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