The Experts below are selected from a list of 549 Experts worldwide ranked by ideXlab platform
Lauren O Bakaletz - One of the best experts on this subject based on the ideXlab platform.
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The DNABII family of proteins is comprised of the only nucleoid associated proteins required for nontypeable Haemophilus influenzae biofilm structure
MicrobiologyOpen, 2017Co-Authors: Aishwarya Devaraj, Lauren O Bakaletz, John Buzzo, Christopher J. Rocco, Steven D. GoodmanAbstract:Biofilms play a central role in the pathobiology of otitis media (OM), bronchitis, sinusitis, conjunctivitis, and pneumonia caused by nontypeable Haemophilus influenzae (NTHI). Our previous studies show that extracellular DNA (eDNA) and DNABII proteins are essential components of biofilms formed by NTHI. The DNABII protein family includes integration host factor (IHF) and the histone-like protein HU and plays a central role in NTHI biofilm structural integrity. We demonstrated that immunological targeting of these proteins during NTHI-induced experimental OM in a Chinchilla Model caused rapid clearance of biofilms from the middle ear. Given the essential role of DNABII proteins in maintaining the structure of an NTHI biofilm, we investigated whether any of the other nucleoid associated proteins (NAPs) expressed by NTHI might play a similar role, thereby serving as additional target(s) for intervention. We demonstrated that although several NAPs including H-NS, CbpA, HfQ and Dps are present within the biofilm extracellular matrix, only the DNABII family of proteins is critical for the structural integrity of the biofilms formed by NTHI. We have also demonstrated that IHF and HU are located at distinct regions within the extracellular matrix of NTHI biofilms formed in vitro, indicative of independent functions of these two proteins.
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ModA2 Phasevarion Switching in Nontypeable Haemophilus influenzae Increases the Severity of Experimental Otitis Media
The Journal of Infectious Diseases, 2016Co-Authors: Kenneth L. Brockman, John M. Atack, Yogitha N. Srikhanta, Joseph A. Jurcisek, Michael P. Jennings, Lauren O BakaletzAbstract:Several human-adapted bacterial pathogens use a phasevarion (ie, a phase-variable regulon) to rapidly and reversibly regulate the expression of many genes, which include known virulence factors, yet the influence of phasevarion-mediated regulation in pathogenesis remains poorly understood. Here we examine the impact of the nontypeable Haemophilus influenzae (NTHI) ModA2 phasevarion on pathogenesis and disease severity in a Chinchilla Model of experimental otitis media. Chinchillas were challenged with NTHI variant populations that were either inoculated ON and remained ON, inoculated OFF and shifted ON, or inoculated OFF and remained OFF, within the middle ear. We show that populations that shift from OFF to ON within the middle ear induce significantly greater disease severity than populations that are unable to shift. These observations support the importance of phasevarion switching in NTHI pathogenesis and the necessity to considered phasevarion regulation when developing methods to treat and prevent infection.
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Selection and Counterselection of Hia Expression Reveals a Key Role for Phase-Variable Expression of Hia in Infection Caused by Nontypeable Haemophilus influenzae
The Journal of Infectious Diseases, 2015Co-Authors: John M. Atack, Lauren O Bakaletz, Joseph A. Jurcisek, Linda E. Winter, Stephen J. Barenkamp, Michael P. JenningsAbstract:Hia is a major adhesin of nontypeable Haemophilus influenzae (NTHi) and has long been investigated as a vaccine candidate. Here we show that Hia phase variation is controlled by changes in the length of a polythymidine tract located in the hia promoter. Studies of an invasive clinical isolate (strain R2866) show that strains expressing high Hia levels are more efficiently killed by opsonophagocytosis. An opsonophagocytic assay was used to select for a subpopulation of variants that expressed a low level of Hia, which facilitated their escape from killing by anti-Hia antisera. Conversely, a subpopulation of variants expressing a high level of Hia was selected for during passaging through Chang cells. In both cases, phase variation of Hia expression corresponded directly with discrete modal changes in polythymidine tract length. In the Chinchilla Model of NTHi infection, we observed consistent selection for high Hia expression upon nasopharyngeal colonization, confirming the key role of phase-variable expression of Hia within a specific niche in vivo.
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Role of the Nuclease of Nontypeable Haemophilus influenzae in Dispersal of Organisms from Biofilms
Infection and Immunity, 2014Co-Authors: Aroon T. Chande, Lauren O Bakaletz, Joseph A. Jurcisek, Lokesh Gakhar, Margaret R. Ketterer, Jian Shao, Kenji Gotoh, Eric D. Foster, Jason HuntAbstract:Nontypeable Haemophilus influenzae (NTHI) forms biofilms in the middle ear during human infection. The biofilm matrix of NTHI contains extracellular DNA. We show that NTHI possesses a potent nuclease, which is a homolog of the thermonuclease of Staphylococcus aureus. Using a biofilm dispersal assay, studies showed a biofilm dispersal pattern in the parent strain, no evidence of dispersal in the nuclease mutant, and a partial return of dispersion in the complemented mutant. Quantitative PCR of mRNA from biofilms from a 24-h continuous flow system demonstrated a significantly increased expression of the nuclease from planktonic organisms compared to those in the biofilm phase of growth (P < 0.042). Microscopic analysis of biofilms grown in vitro showed that in the nuclease mutant the nucleic acid matrix was increased compared to the wild-type and complemented strains. Organisms were typically found in large aggregates, unlike the wild-type and complement biofilms in which the organisms were evenly dispersed throughout the biofilm. At 48 h, the majority of the organisms in the mutant biofilm were dead. The nuclease mutant formed a biofilm in the Chinchilla Model of otitis media and demonstrated a propensity to also form similar large aggregates of organisms. These studies indicate that NTHI nuclease is involved in biofilm reModeling and organism dispersal.
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use of the Chinchilla Model for nasopharyngeal colonization to study gene expression by moraxella catarrhalis
Infection and Immunity, 2012Co-Authors: Todd C Hoopman, Lauren O Bakaletz, Stephanie N Joslin, Christine Pybus, Jennifer L Sedillo, Maria Labandeirarey, Cassie A Laurence, Wei Wang, James A Richardson, Eric J HansenAbstract:Young adult Chinchillas were atraumatically inoculated with Moraxella catarrhalis via the nasal route. Detailed histopathologic examination of nasopharyngeal tissues isolated from these M. catarrhalis-infected animals revealed the presence of significant inflammation within the epithelium. Absence of similar histopathologic findings in sham-inoculated animals confirmed that M. catarrhalis was exposed to significant host-derived factors in this environment. Twenty-four hours after inoculation, viable M. catarrhalis organisms were recovered from the nasal cavity and nasopharynx of the animals in numbers sufficient for DNA microarray analysis. More than 100 M. catarrhalis genes were upregulated in vivo, including open reading frames (ORFs) encoding proteins that are involved in a truncated denitrification pathway or in the oxidative stress response, as well as several putative transcriptional regulators. Additionally, 200 M. catarrhalis genes were found to be downregulated when this bacterium was introduced into the nasopharynx. These downregulated genes included ORFs encoding several well-characterized M. catarrhalis surface proteins including Hag, McaP, and MchA1. Real-time reverse transcriptase PCR (RT-PCR) was utilized as a stringent control to validate the results of in vivo gene expression patterns as measured by DNA microarray analysis. Inactivation of one of the genes (MC ORF 1550) that was upregulated in vivo resulted in a decrease in the ability of M. catarrhalis to survive in the Chinchilla nasopharynx over a 3-day period. This is the first evaluation of global transcriptome expression by M. catarrhalis cells in vivo.
Thomas F Demaria - One of the best experts on this subject based on the ideXlab platform.
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Effect of Adenovirus Type 1 and Influenza a Virus on Streptococcus Pneumoniae Nasopharyngeal Colonization and Otitis Media in the Chinchilla
Annals of Otology Rhinology and Laryngology, 2020Co-Authors: Hua Hua Tong, Gregory M. Kosunick, Lisa M. Fisher, Thomas F DemariaAbstract:Considerable evidence has implicated respiratory tract virus potentiation of bacterial adherence, colonization, and superinfection as a significant factor contributing to the pathogenesis of otitis media (OM). Influenza A and B viruses, adenovirus, and respiratory syncytial virus are the primary respiratory tract viruses associated with this disease. Investigations have established a dramatic increase in the development of experimental OM in Chinchillas co-inoculated with influenza A virus and Streptococcus pneumoniac (Spn). The mechanism underlying this phenomenon was suggested to involve, in part, viral compromise of eustachian tube mucosal integrity and function. This study was designed to assess and compare the effect of adenovirus and influenza A virus infection on adherence, the kinetics of colonization, and invasion of the middle ear by Spn in the Chinchilla Model of OM. Cohorts were inoculated intranasally with adenovirus type I or influenza A virus, and then inoculated intranasally 7 days later with Spn 6A. All cohorts were observed over a 14-day period after challenge with Spn, and the incidence and severity of OM were assessed by several methods, including culture of the nasopharynx and middle ear effusions. The data indicated that influenza A virus promotes a significant increase in nasopharyngeal colonization by Spn, an increased incidence and severity of OM, and a sustained presence of Spn in the effusions. Adenovirus infection, however, did not enhance colonization by Spn or result in an increased incidence or severity of OM.
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sortase a contributes to pneumococcal nasopharyngeal colonization in the Chinchilla Model
Fems Microbiology Letters, 2005Co-Authors: Shu Chen, Gavin K Paterson, Hua Hua Tong, Timothy J Mitchell, Thomas F DemariaAbstract:Sortase A (SrtA) is required to anchor neuraminidase, β-galactosidase, and possibly other LPXTG motif proteins to the pneumococcal cell surface. We examined the role of SrtA in Streptococcus pneumoniae nasopharyngeal (NP) colonization in the Chinchilla Model. The srtA mutant colonized the nasopharynx at a significantly lower level than the D39 parent strain during the second and third week of the carriage, and was eliminated from nasopharynx one week earlier than the D39 pneumococci. Our data indicate that SrtA contributes to pneumococcal NP colonization in this animal Model.
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Immunization with recombinant Streptococcus pneumoniae neuraminidase NanA protects Chinchillas against nasopharyngeal colonization
Infection and Immunity, 2005Co-Authors: H H Tong, Shu Chen, D. Li, J. P. Long, Thomas F DemariaAbstract:Immunization with recombinant S. pneumoniae neuraminidase NanA (rNanA) resulted in a significant reduction in pneumococcal colonization in the Chinchilla Model. The bacteria were eliminated from the nasopharynx 1 week earlier than that from the control cohort. Our data suggest that rNanA affords protection against pneumococcal nasopharyngeal colonization.
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effect of influenza a virus infection on nasopharyngeal colonization and otitis media induced by transparent or opaque phenotype variants of streptococcus pneumoniae in the Chinchilla Model
Infection and Immunity, 2001Co-Authors: H H Tong, M A James, Jeffrey N Weiser, Thomas F DemariaAbstract:Phase variation in the colonial opacity of Streptococcus pneumoniae has been implicated as a factor in bacterial adherence, colonization, and invasion in the pathogenesis of pneumococcal disease. Additionally, the synergistic effects of influenza A virus and S. pneumoniae in the development of otitis media (OM) have been reported. This study examined the ability of opaque or transparent S. pneumoniae from the same strain in combination with an antecedent influenza A virus infection to colonize the nasopharynx and invade the middle ear in the Chinchilla Model. Our data indicated that there was no significant difference in the level of nasopharyngeal colonization and induction of OM between the opaque and transparent variants unless there was a prior challenge with influenza A virus. Subsequent to influenza A virus infection, there was a significant difference between the variants in the ability to colonize and persist in the nasopharynx and middle ear. The concentrations of the opaque variant in nasopharyngeal-lavage samples and middle-ear fluid remained consistently higher than those of the transparent variant for 10 days postinoculation. Data from this study indicate that the effects of influenza A virus on the pathogenesis of experimental S. pneumoniae-induced OM differ depending on the opacity phenotype involved.
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evaluation of phase variation of nontypeable haemophilus influenzae lipooligosaccharide during nasopharyngeal colonization and development of otitis media in the Chinchilla Model
Infection and Immunity, 2000Co-Authors: H H Tong, L E Blue, M A James, Yiping Chen, Thomas F DemariaAbstract:Nontypeable Haemophilus influenzae (NTHI) has four loci, lic-1 to lic-3 and lgtC, that generate phase-variable lipooligosaccharide (LOS) structures. lic-1, which is required for the expression of phosphorylcholine (ChoP), is the best characterized and is associated with an enhanced ability of H. influenzae to persist within the nasopharynges of infant rats. Recent data indicate that LOS impacts various aspects of NTHI virulence in the Chinchilla Model of nasopharyngeal colonization and otitis media (OM). In this study the effects of ChoP expression and the sequences of lic-1 to lic-3 and lgtC of NTHI strain 2019 were evaluated in the Chinchilla OM Model. Nasopharyngeal colonization data showed that a switch from the ChoP− to the ChoP+ phenotype was observed as early as day 3 after intranasal inoculation. Chinchillas colonized by strains with the ChoP+ phenotype demonstrated a significantly higher level of NTHI 2019 per milliliter of nasal lavage fluid than Chinchillas colonized with predominantly the ChoP− variant (P < 0.05). The concentration of cells with the ChoP+ phenotype in the middle ear was 3 log units higher than that of cells with the ChoP− variant (P < 0.01). There was a statistically significant association between ChoP+ expression in the nasal lavage and the development of OM with culture-positive middle ear fluids in this Model. These data suggest that expression of the ChoP+ phenotype promotes enhanced nasopharyngeal colonization and development of OM.
Daniel Tollin - One of the best experts on this subject based on the ideXlab platform.
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Conductive Hearing Loss Induced by Experimental Middle-Ear Effusion in a Chinchilla Model Reveals Impaired Tympanic Membrane-Coupled Ossicular Chain Movement
Journal of the Association for Research in Otolaryngology, 2013Co-Authors: Jennifer L. Thornton, Keely M. Chevallier, Kanthaiah Koka, Sandra A. Gabbard, Daniel TollinAbstract:Otitis media with effusion (OME) occurs when fluid collects in the middle-ear space behind the tympanic membrane (TM). As a result of this effusion, sounds can become attenuated by as much as 30–40 dB, causing a conductive hearing loss (CHL). However, the exact mechanical cause of the hearing loss remains unclear. Possible causes can include altered compliance of the TM, inefficient movement of the ossicular chain, decreased compliance of the oval window-stapes footplate complex, or altered input to the oval and round window due to conduction of sound energy through middle-ear fluid. Here, we studied the contribution of TM motion and umbo velocity to a CHL caused by middle-ear effusion. Using the Chinchilla as an animal Model, umbo velocity ( V _U) and cochlear microphonic (CM) responses were measured simultaneously using sinusoidal tone pip stimuli (125 Hz–12 kHz) before and after filling the middle ear with different volumes (0.5–2.0 mL) of silicone oil (viscosity, 3.5 Poise). Concurrent increases in CM thresholds and decreases in umbo velocity were noted after the middle ear was filled with 1.0 mL or more of fluid. Across animals, completely filling the middle ear with fluid caused 20–40-dB increases in CM thresholds and 15–35-dB attenuations in umbo velocity. Clinic-standard 226-Hz tympanometry was insensitive to fluid-associated changes in CM thresholds until virtually the entire middle-ear cavity had been filled (approximately >1.5 mL). The changes in umbo velocity, CM thresholds, and tympanometry due to experimentally induced OME suggest CHL arises primarily as a result of impaired TM mobility and TM-coupled umbo motion plus additional mechanisms within the middle ear.
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erratum to conductive hearing loss induced by experimental middle ear effusion in a Chinchilla Model reveals impaired tympanic membrane coupled ossicular chain movement
Jaro-journal of The Association for Research in Otolaryngology, 2013Co-Authors: Jennifer L. Thornton, Keely M. Chevallier, Kanthaiah Koka, Sandra A. Gabbard, Daniel TollinAbstract:Otitis media with effusion (OME) occurs when fluid collects in the middle-ear space behind the tympanic membrane (TM). As a result of this effusion, sounds can become attenuated by as much as 30–40 dB, causing a conductive hearing loss (CHL). However, the exact mechanical cause of the hearing loss remains unclear. Possible causes can include altered compliance of the TM, inefficient movement of the ossicular chain, decreased compliance of the oval window-stapes footplate complex, or altered input to the oval and round window due to conduction of sound energy through middle-ear fluid. Here, we studied the contribution of TM motion and umbo velocity to a CHL caused by middle-ear effusion. Using the Chinchilla as an animal Model, umbo velocity (VU) and cochlear microphonic (CM) responses were measured simultaneously using sinusoidal tone pip stimuli (125 Hz–12 kHz) before and after filling the middle ear with different volumes (0.5–2.0 mL) of silicone oil (viscosity, 3.5 Poise). Concurrent increases in CM thresholds and decreases in umbo velocity were noted after the middle ear was filled with 1.0 mL or more of fluid. Across animals, completely filling the middle ear with fluid caused 20–40-dB increases in CM thresholds and 15–35-dB attenuations in umbo velocity. Clinic-standard 226-Hz tympanometry was insensitive to fluid-associated changes in CM thresholds until virtually the entire middle-ear cavity had been filled (approximately >1.5 mL). The changes in umbo velocity, CM thresholds, and tympanometry due to experimentally induced OME suggest CHL arises primarily as a result of impaired TM mobility and TM-coupled umbo motion plus additional mechanisms within the middle ear.
Jennifer L. Thornton - One of the best experts on this subject based on the ideXlab platform.
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Conductive Hearing Loss Induced by Experimental Middle-Ear Effusion in a Chinchilla Model Reveals Impaired Tympanic Membrane-Coupled Ossicular Chain Movement
Journal of the Association for Research in Otolaryngology, 2013Co-Authors: Jennifer L. Thornton, Keely M. Chevallier, Kanthaiah Koka, Sandra A. Gabbard, Daniel TollinAbstract:Otitis media with effusion (OME) occurs when fluid collects in the middle-ear space behind the tympanic membrane (TM). As a result of this effusion, sounds can become attenuated by as much as 30–40 dB, causing a conductive hearing loss (CHL). However, the exact mechanical cause of the hearing loss remains unclear. Possible causes can include altered compliance of the TM, inefficient movement of the ossicular chain, decreased compliance of the oval window-stapes footplate complex, or altered input to the oval and round window due to conduction of sound energy through middle-ear fluid. Here, we studied the contribution of TM motion and umbo velocity to a CHL caused by middle-ear effusion. Using the Chinchilla as an animal Model, umbo velocity ( V _U) and cochlear microphonic (CM) responses were measured simultaneously using sinusoidal tone pip stimuli (125 Hz–12 kHz) before and after filling the middle ear with different volumes (0.5–2.0 mL) of silicone oil (viscosity, 3.5 Poise). Concurrent increases in CM thresholds and decreases in umbo velocity were noted after the middle ear was filled with 1.0 mL or more of fluid. Across animals, completely filling the middle ear with fluid caused 20–40-dB increases in CM thresholds and 15–35-dB attenuations in umbo velocity. Clinic-standard 226-Hz tympanometry was insensitive to fluid-associated changes in CM thresholds until virtually the entire middle-ear cavity had been filled (approximately >1.5 mL). The changes in umbo velocity, CM thresholds, and tympanometry due to experimentally induced OME suggest CHL arises primarily as a result of impaired TM mobility and TM-coupled umbo motion plus additional mechanisms within the middle ear.
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erratum to conductive hearing loss induced by experimental middle ear effusion in a Chinchilla Model reveals impaired tympanic membrane coupled ossicular chain movement
Jaro-journal of The Association for Research in Otolaryngology, 2013Co-Authors: Jennifer L. Thornton, Keely M. Chevallier, Kanthaiah Koka, Sandra A. Gabbard, Daniel TollinAbstract:Otitis media with effusion (OME) occurs when fluid collects in the middle-ear space behind the tympanic membrane (TM). As a result of this effusion, sounds can become attenuated by as much as 30–40 dB, causing a conductive hearing loss (CHL). However, the exact mechanical cause of the hearing loss remains unclear. Possible causes can include altered compliance of the TM, inefficient movement of the ossicular chain, decreased compliance of the oval window-stapes footplate complex, or altered input to the oval and round window due to conduction of sound energy through middle-ear fluid. Here, we studied the contribution of TM motion and umbo velocity to a CHL caused by middle-ear effusion. Using the Chinchilla as an animal Model, umbo velocity (VU) and cochlear microphonic (CM) responses were measured simultaneously using sinusoidal tone pip stimuli (125 Hz–12 kHz) before and after filling the middle ear with different volumes (0.5–2.0 mL) of silicone oil (viscosity, 3.5 Poise). Concurrent increases in CM thresholds and decreases in umbo velocity were noted after the middle ear was filled with 1.0 mL or more of fluid. Across animals, completely filling the middle ear with fluid caused 20–40-dB increases in CM thresholds and 15–35-dB attenuations in umbo velocity. Clinic-standard 226-Hz tympanometry was insensitive to fluid-associated changes in CM thresholds until virtually the entire middle-ear cavity had been filled (approximately >1.5 mL). The changes in umbo velocity, CM thresholds, and tympanometry due to experimentally induced OME suggest CHL arises primarily as a result of impaired TM mobility and TM-coupled umbo motion plus additional mechanisms within the middle ear.
G S Giebink - One of the best experts on this subject based on the ideXlab platform.
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Chapter 45 – Otitis Media: The Chinchilla Model
Handbook of Animal Models of Infection, 1999Co-Authors: David M Hajek, Z Yuan, Moses Quartey, G S GiebinkAbstract:Publisher Summary This chapter describes the Chinchilla otitis media (OM) Model, which has enhanced the understanding of every aspect of this common childhood disease, including pathogenesis, immunoprophylaxis, and therapy. This Model includes various methods used to induce middle ear (ME) inflammation under conditions of acute bacterial and viral infection, chronic inflammation, and eustachian tube dysfunction. The Chinchillas used in this Model are housed in stainless-steel wire cages except during experiments involving inoculation of respiratory virus, when filterbonneted microisolator cages are used during the period of viral shedding. Prior to the start of an experiment, ears should be examined by tympanometry and otoscopy to verify the absence of middle-ear effusions (MEE) or tympanic membrane pathology. Chinchillas are effectively sedated with 10 mg ketamine hydrochloride injected into the anterior thigh. Complete anesthesia ensues in about 5 minutes and lasts for about 25 minutes. Chinchillas should be observed carefully while anesthetized as ketamine occasionally causes respiratory depression. Access to the Chinchilla ME cavity is through the cephalad bulla underlying the dorsal aspect of the skull. The bone is very thin at the apex of the bulla, which allows to insert a needle into the ME cleft in a relatively atraumatic fashion. Chinchillas should be kept warm and observed closely until they have completely recovered from anesthesia. Following recovery, Chinchillas return to normal behavior and are given food and water ad lib.
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chapter 45 otitis media the Chinchilla Model
Handbook of Animal Models of Infection#R##N#Experimental Models in Antimicrobial Chemotherapy, 1999Co-Authors: David M Hajek, Z Yuan, Moses Quartey, G S GiebinkAbstract:Publisher Summary This chapter describes the Chinchilla otitis media (OM) Model, which has enhanced the understanding of every aspect of this common childhood disease, including pathogenesis, immunoprophylaxis, and therapy. This Model includes various methods used to induce middle ear (ME) inflammation under conditions of acute bacterial and viral infection, chronic inflammation, and eustachian tube dysfunction. The Chinchillas used in this Model are housed in stainless-steel wire cages except during experiments involving inoculation of respiratory virus, when filterbonneted microisolator cages are used during the period of viral shedding. Prior to the start of an experiment, ears should be examined by tympanometry and otoscopy to verify the absence of middle-ear effusions (MEE) or tympanic membrane pathology. Chinchillas are effectively sedated with 10 mg ketamine hydrochloride injected into the anterior thigh. Complete anesthesia ensues in about 5 minutes and lasts for about 25 minutes. Chinchillas should be observed carefully while anesthetized as ketamine occasionally causes respiratory depression. Access to the Chinchilla ME cavity is through the cephalad bulla underlying the dorsal aspect of the skull. The bone is very thin at the apex of the bulla, which allows to insert a needle into the ME cleft in a relatively atraumatic fashion. Chinchillas should be kept warm and observed closely until they have completely recovered from anesthesia. Following recovery, Chinchillas return to normal behavior and are given food and water ad lib.
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tobacco smoke and otitis media in the Chinchilla Model
Otolaryngology-Head and Neck Surgery, 1994Co-Authors: Patrick J Antonelli, K A Daly, S K Juhn, E J Veum, G L Adams, G S GiebinkAbstract:To determine whether tobacco smoke contributes to the pathogenesis of acute otitis media, Chinchillas were exposed to mainstream tobacco smoke or sham conditions (cigarettes not lit) in a Walton smoke exposure machine for 20-minute cycles two or three times daily. After 6 to 8 weeks of daily exposure, 12 Chinchillas were nasally injected with Streptococcus pneumoniae, and 18 Chinchillas were injected into both middle ears with nontypable Haemophilus influenzae. Smoke or sham exposures were continued for 2 to 4 weeks after injection. Otitis media developed in none of the 12 nasally injected Chinchillas and in all 18 Chinchillas whose middle ears were injected with nontypable Haemophilus influenzae. Persistence of middle ear effusion and persistence of nontypable Haemophilus influenzae in the middle ear effusion were not different between the smoke- and sham-exposed groups. This suggests that mainstream smoke exposure does not change the natural course of otitis media in the Chinchilla Model.
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Role of the bacterial cell wall in middle ear inflammation caused by Streptococcus pneumoniae.
Infection and Immunity, 1992Co-Authors: B D Carlsen, Alexander Tomasz, M Kawana, C Kawana, G S GiebinkAbstract:Abstract The pathogenesis of middle ear inflammation caused by Streptococcus pneumoniae was explored in the Chinchilla Model with different pneumococcal cell wall (CW) preparations, including isolated native CW, M1 muramidase CW (M1-CW) digest, amidase CW digest, and M1 peptidoglycan (M1-PG) digest. Inflammatory cell and lysozyme concentrations in middle ear fluid (MEF) were measured between 6 and 72 h after the middle ears were inoculated with one of the preparations or sterile saline. Middle ear histopathology was measured quantitatively at 72 h. Native CW, M1-CW digest, and amidase-CW digest caused significantly more inflammatory cell influx and lysozyme accumulation in MEF than saline did. M1-PG digest also caused more inflammatory cell influx and lysozyme accumulation in MEF than saline did but caused less inflammation than native CW or either CW digest. Epithelial metaplasia was significantly greater in ears inoculated with native CW than in ears inoculated with the CW or PG digest or with saline. Pneumococcal CW is, therefore, the principal factor that initiates middle ear inflammation in acute pneumococcal otitis media, and CW teichoication seems to be important in initiating this response.
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Enzyme immunoassay for detection of immunoglobulin G (IgG), IgM, and IgA antibodies against type 6B pneumococcal capsular polysaccharide and cell wall C polysaccharide in Chinchilla serum.
Journal of Clinical Microbiology, 1992Co-Authors: M Koskela, M Harris, G S GiebinkAbstract:Conjugation of the capsular polysaccharides of Streptococcus pneumoniae to protein carriers has introduced a new generation of pneumococcal vaccines which may be efficacious in preventing pneumococcal otitis media during infancy. The Chinchilla Model has been used extensively for studying the pathogenesis of pneumococcal otitis media and for testing the efficacy of early pneumococcal capsular polysaccharide (PCP) vaccines, but immunologic studies in the Chinchilla have been limited by the lack of antibodies against specific immunoglobulin isotypes. By using affinity-purified rabbit immunoglobulin G (IgG) anti-Chinchilla IgG, IgM, and IgA, we developed a sensitive enzyme immunoassay that is highly specific for IgG, IgM, and IgA antibodies against type 6B PCP (anti-6B) and against C polysaccharide in Chinchilla serum. Antibody titers increased in serum from five Chinchillas immunized with a type 6B outer membrane protein complex vaccine. Increases of anti-6B IgG and IgM antibody titers were more striking than increases of anti-6B IgA or anti-C polysaccharide IgG, IgM, or IgA titers were.