Temporal bone study of Down's syndrome

OBJECTIVE

To study temporal bone histopathologic characteristics of the inner ear and middle ear cleft of patients with Down's syndrome.

DESIGN

Sixteen temporal bones from eight patients with Down's syndrome were studied. Ten temporal bones from subjects without pathologic ear lesions but with congenital heart disease served as controls. The two-dimensional graphic reconstruction method proposed by Guild and modified by Schuknecht was used to study the cochleas; measurement of the vestibules was based on Igarashi's method.

SETTING

The temporal bone collection of the Otitis Media Research Center, Department of Otolaryngology, University of Minnesota School of Medicine, Minneapolis.

RESULTS

Six bones showed short cochlea, and four of six had Mondini's cochlea. The overall cochlear lengths in this study group were notably shorter than those of the controls. The spiral ganglion cell population and two of three vestibular dimensions also were notably less than the controls. Middle ear findings included residual mesenchyme, stapes abnormality, otitis media, and large facial canal dehiscence.

CONCLUSIONS

The difficulties encountered in rehabilitation of patients with Down's syndrome caused by mental retardation can be compounded by the hearing loss caused by middle and inner ear abnormalities. A complete evaluation of hearing loss and therapy before starting the rehabilitation gives the most favorable outcome.

Duration of ventilating tubes: a test for comparing two clustered samples of censored data

A study of otitis media that requires a test for the comparison of two clustered samples of censored data is described. A method is proposed taking into account the within-subject correlation in the formation of the log-rank statistic.

High frequency hearing loss associated with otitis media

OBJECTIVE

Long-term effects of otitis media (OM) on hearing in both conventional and high frequency (HF) regions in children were studied.

DESIGN

Children with OM were enrolled in a prospective study of sequelae after tympanostomy tube insertion (intubation) and were examined serially at 6-mo intervals with audiometry and multifrequency tympanometry, and every 3 mo with tympanometry and otoscopy for at least 3, and up to 5 yr. Hearing thresholds in conventional and HF regions were compared with those of an age-matched control group of children who had 2 or fewer documented episodes of any type of OM since birth. Frequency of OM during follow-up, number of intubations, use of ototopical eardrops, age, and sex along with several other factors were analyzed for a relationship to HF hearing loss.

RESULTS

Otitis media history was associated with poorer HF hearing, but the presence of subtle residual middle ear dysfunction was not associated with an additional effect on HF hearing. Active middle ear disease significantly affected both conventional and HF thresholds. The number of intubations and frequency of OM during follow-up were significantly and positively associated with poorer HF thresholds. Several other factors, including middle ear appearance at intubation, presence of tympanosclerosis, age, male gender, and use of ototopical eardrops, were also associated with poorer HF hearing but failed to reach significance after their intercorrelation with number of intubations and frequency of OM was considered.

CONCLUSIONS

High frequency hearing loss was associated with OM after middle ear disease resolved and after middle ear dysfunction was excluded. Relatively poorer HF hearing thresholds found for older children with OM histories appeared to be attributable to time spent with ear disease. Children at greatest risk for HF hearing loss were those who required multiple intubations. Older children tended to have poorer hearing in both conventional and HF regions, suggesting that the effects of OM on hearing thresholds may be progressive.

The family study of otitis media: design and disease and risk factor profiles

Recurrent acute otitis media (RAOM) and chronic otitis media with effusion (COME) exhibit familial aggregation, but environmental risk factors (day care attendance, cigarette smoke exposure, and bottle feeding) are also important in their development. The Family Study of OM was designed to ascertain the RAOM/ COME status of families whose children participated in Otitis Media Research Center studies between 1978 and 1984. Probands were treated with tympanostomy tubes, and had their RAOM/COME status ascertained as criteria for entry into these studies. For the Family Study of OM parents were interviewed about their otitis media and risk factor history; mothers were interviewed about their children's history, and pertinent medical records were obtained. Members of 173 families were examined with otomicroscopy and multifrequency tympanometry; 19% of parents and 32% of siblings were classified as affected, which is substantially higher than RAOM/COME rates from previous reports. Risk factor profiles differed significantly (P < .001) between parents and their children. Younger generation (adjusted odds ratio [OR] = 4.18, 95% confidence interval [CI], 2.74, 6.36) day care attendance (OR = 1.96, 95% CI, 1.32, 2.91) and male gender (OR = 1.42, 95% CI, 1.03, 1.97) were significantly related to RAOM/ COME using logistic regression. Analyses confirm 1) higher disease rates in families with an affected member compared to existing studies of the general population, 2) increased risk of RAOM/COME associated with known risk factors, and 3) increased risk for parents irrespective of risk factors. Additional analyses will explore competing models of disease susceptibility using genetic models and known risk factors.

Immunogenicity and efficacy of Streptococcus pneumoniae polysaccharide-protein conjugate vaccines against homologous and heterologous serotypes in the chinchilla otitis media model

Cross-protection among pneumococcal serotypes within serogroups was measured in the chinchilla otitis media (OM) model because several serotypes that cause OM in children are closely related biochemically. Chinchillas were given tetravalent vaccine composed of pneumococcal capsular polysaccharides (PS; types 6B, 14, 19F, 23F) conjugated to an outer membrane protein complex, and 89% to 96% developed a > or = 2-fold serum IgG rise against vaccine PS. Vaccine efficacy was tested by inoculating middle ear hypotympanic bullae with Streptococcus pneumoniae types 6B, 6A, 19F, or 19A. OM severity in the vaccinated groups challenged with types 6B, 6A, and 19F but not 19A was significantly better than in the respective placebo groups. Culture-positive pneumococcal OM occurred in 38%, 62%, 0, and 78% of vaccinated chinchillas challenged with types 6B, 6A, 19F, and 19A, respectively, but in 88% of type 6B- and 100% of type 6A-, 19A-, and 19F-challenged placebo chinchillas.

Randomized trial of the efficacy of trimethoprim-sulfamethoxazole and prednisone in preventing post-tympanostomy tube morbidity

This study was designed to determine whether treatment with prednisone and trimethoprim-sulfamethoxazole would reduce first year post-operative morbidity in children with chronic otitis media with effusion undergoing tympanostomy tube insertion (intubation). Eighty children ages 6 months to 8 years were enrolled at intubation and randomized from age strata to receive active drugs or placebos for 14 days after surgery. They were examined with pneumatic otoscopy and tympanometry preoperatively and at 3 weeks and 3, 6, 9 and 12 months after surgery. Active drug treatment significantly reduced tube obstruction or extrusion in the first 3 postoperative months compared with placebos (4% vs. 17%, P = .01). However, rates of repeat intubation, otorrhea and recurrence of otitis media did not differ significantly in the two groups. Children with chronic otitis media with effusion treated with intubation may benefit from a 2-week course of prednisone and trimethoprim-sulfamethoxazole at the time of surgery. However, there is no apparent long term benefit of this treatment.

Protection of myocytes against free radical-induced damage by accelerated turnover of the glutathione redox cycle

The primary defence mechanism of myocytes against peroxides and peroxide-derived peroxyl and alkoxyl radicals is the glutathione redox cycle. The purpose of the present study was to increase the turnover rate of this cycle by stimulating the glutathione peroxidase catalysed reaction (2GSH-->GSSG), the glutathione reductase catalysed reaction (GSSG-->2GSH), or both. Neonatal rat heart cell cultures were subjected to a standardized protocol of oxidative stress using 80 mumol.l-1 cumene hydroperoxide (CHPO) for 0-90 min. The consequences of this protocol were described in terms of cellular concentrations of GSH, GSSG, NADPH and ATP, formation of malondialdehyde (MDA), release of GSSG and of ATP catabolites, depression of contraction frequency, cellular calcium overload, and enzyme release. Trolox-C, an analogue of vitamin E, accelerated the glutathione peroxidase reaction leading to lowering of GSH concentration and the GSH/GSSG ratio, less MDA formation, diminished negative chronotropy, delayed calcium overload, and less enzyme release. Glucose was used to accelerate the glutathione reductase reaction by supplying NADPH, leading to higher GSH concentration and a higher GSH/GSSG ratio, less MDA formation, diminished negative chronotropy, unchanged development of calcium overload, and less enzyme release. As a full turn of the glutathione redox cycle involves both the peroxidase and the reductase reactions, the combination of Trolox-C and glucose was superior to either of the two alone: 90 min following addition of CHPO together with Trolox-C and glucose, the GSH concentration and the GSH/GSSG ratio were almost normal, MDA formation was extremely low, calcium overload was markedly delayed, and enzyme release hardly occurred at all. Cells remained beating in the observation period of 30 min. We conclude that the capacity of the glutathione redox cycle to withstand oxidative stress can be increased by stimulation of either the peroxidase reaction or the reductase reaction, and that optimal redox cycling is achieved by stimulation of both reactions.

Desferrioxamine protects myocytes against peroxide-induced myocyte damage without affecting glutathione redox cycle turnover

The primary defense mechanism of myocytes against peroxide-derived free radicals is the glutathione redox cycle. The purpose of the present study was to investigate whether desferrioxamine protects myocytes against peroxide-induced cell damage, and if so, whether the turnover rate of the glutathione redox cycle is involved in this protection. Neonatal rat heart cell cultures were subjected to a standardized oxidative stress by a 90 min incubation with 80 mumol/l cumene hydroperoxide. The consequences of this stress protocol were described in terms of cellular concentrations of GSH, GSSG, ATP, ATP-catabolites, and Ca2+, formation of malondialdehyde to quantify lipid peroxidation, and enzyme release to quantify the relative number of irreversibly injured cells. Following pretreatment of cell cultures with 10 mmol/l desferrioxamine mesylate for 1 h, 80 mumol/l cumene hydroperoxide caused less malondialdehyde formation (at 90 min: 0.34 v 2.35 nmol), less ATP depletion (at 60 min: 16.7 v 3.6 nmol), less Ca2+ overload (at 30 min: 40 v 1500 nM) and less enzyme release (at 90 min: 4.6 v 60.5% of the cells) compared to cell cultures subjected to cumene hydroperoxide without pretreatment. However, in desferrioxamine pretreated cell cultures cumene hydroperoxide caused cellular GSH depletion (at 60 min: 19.5 v 20.8 nmol) and GSSG efflux (at 60 min: 6.3 v 6.0 nmol) which was not different from cell cultures subjected to cumene hydroperoxide without pretreatment. Added to the finding that in a cell-free system cumene hydroperoxide is a substrate for glutathione peroxidase, we conclude that desferrioxamine, by chelating free iron ions (1), prevented the formation of cumene alkoxyl and peroxyl radicals associated with protection of the myocytes, and (2) did not diminish rapid glutathione redox cycling leading to GSH depletion and GSSG efflux.

Comparison of two otitis media models for the study of middle ear antimicrobial pharmacokinetics

We compared two models of acute otitis media that estimate middle ear antimicrobial pharmacokinetics. Using a crossover study design, we compared a systemic drug administration model with a diffusion model we devised that measures the disappearance of antimicrobials from the middle ear. We induced acute otitis media in 14 chinchillas by inoculating S. pneumoniae into the middle ear, then administered 3 antimicrobials: amoxicillin, trimethoprim, and sulfamethoxazole. Next we collected middle ear fluid samples to analyze drug concentrations and compare rate constants for the systemic and diffusion models by analysis of variance. We found that amoxicillin K values were not affected by model testing sequence (p = 0.827) or model type (systemic versus diffusion, p = 0.310), nor were sulfamethoxazole K values: model testing sequence (p = 0.917), model type (p = 0.963). Trimethoprim K values were also not affected by model testing sequence (p = 0/760), but were by model type (p = 0.0001). Trimethoprim elimination from the diffusion model was faster (K = 0.33 +/- 0.17 versus 0.57 +/- 0.09 hr-1) than from the systemic model, although it appears this was caused by sampling before drug distribution into the middle ear was complete. In conclusion, it appears K values derived from either systemic antimicrobial administration or direct middle ear instillation are similar for assessing middle ear antimicrobial pharmacokinetics, and these models can be used interchangeably to study factors affecting otitis media treatment response.

A clinical profile of otitis media without an intact tympanic membrane

An otitis media with effusion algorithm developed by Paradise et al has become the basis for many studies of otitis media. However, it has been shown to be too ambitious (low specificity) and too optimistic (absence of fluid does not necessarily mean normal ears). We developed a four-point profile to characterize the condition of the middle ear, but it cannot be used when the eardrum is perforated (with a functioning tube or chronic perforation). We propose a three-point profile for use without an intact tympanic membrane, and we report the validation of the profile by findings at myringotomy and by the preoperative profile. This postoperative profile and the previously described profile for ears with an intact tympanic membrane should increase the accuracy of middle ear assessment in following the course of otitis media over time.

Determining otitis media severity from middle ear fluid analysis

Otitis media has a complex multifactorial pathogenesis, and the middle ear inflammatory response is typified by the accumulation of cellular and chemical mediators in middle ear effusion. However, specific biochemical and immunochemical factors that may be responsible for the severity or chronicity of otitis media have not been identified. Identification of factors involved in chronicity appears to be an essential step in the treatment and ultimate prevention of chronic otitis media. We analyzed 70 effusion samples from patients 1 to 10 years of age who had chronic otitis media with effusion for two cytokines (interleukin-1 beta and tumor necrosis factor alpha) and total collagenase. The highest concentrations of all three inflammatory mediators were found in purulent otitis media, and concentrations were higher in younger than in older patients. Mediator concentrations were similar in samples obtained from patients having their first myringotomy for otitis media with effusion and in those who had had multiple previous myringotomies. The multiresponse star, which incorporates several biochemical parameters in one graphic illustration, may best characterize the complex nature of middle ear inflammation.

Treatment evaluation in otitis media research

OBJECTIVE

An application of the clinical otitis media profile is proposed for the evaluation of treatments in clinical studies of otitis media.

METHODS

Methods include a statistical test of significance and measures of "treatment difference." This article focuses on the method, not any particular study; however, an example is given to illustrate the ideas.

CONCLUSIONS

The proposed method substantially increases powers of statistical tests, as compared with the use of a two-point scale algorithm, when applied to study changes of the middle ear condition over time or to compare treatment effects. The proposed evaluation method is applicable to any medical drug treatment for groups that may not be comparable, even with randomization, for baseline severity. Applied to surgical treatment, it can be used for long-term evaluation; however, short-term evaluation is impossible because the needed tympanometric, static admittance, and width measurements cannot be obtained in the presence of functioning tubes. To achieve this objective, it is necessary to use another profile or diagnostic procedure.

Piecewise exponential survival curves with smooth transitions

Several models of a population survival curve composed of two piecewise exponential distributions are developed. In one formulation the hazard rate changes at a point that is an unobservable random variable that varies between individuals. The population hazard function may decrease with age even when all individuals' hazards are increasing. In a second formulation, the population hazard function is modeled directly. Several models are fit to the survival history of a cohort of 5751 highly inbred male Drosophila melanogaster and the British coal mining disaster data.

Association between survival time and ordinal covariates

An application of the method of rank correlation is proposed for testing independence between a censored survival time and an ordinal covariate. The test statistic counts the number of concordances minus the number of discordances at each time with event(s) and adds across times; it is expressible as a score statistic within the proportional hazards framework. The proposed test includes, as a special case, a generalization of Jonckheere's test against ordered alternatives and as applied to the analysis of categorical data, it can be seen as a generalization of the Mantel-Haenszel procedure.

Acute otitis media increases middle ear susceptibility to nasal injection of Pseudomonas aeruginosa

Pseudomonas aeruginosa was injected intranasally into four groups of chinchillas to determine if these bacteria can invade the middle ear by way of the eustachian tube. One group completed penicillin treatment of bilateral penumococcal otitis media (POM), and the second group started penicillin treatment of bilateral POM at the time of P. aeruginosa injection. A third group had no POM, but completed a course of penicillin treatment before P. aeruginosa injection, and a fourth group had no POM and received no penicillin. Middle ear susceptibility to nasally injected P. aeruginosa was significantly higher in animals with POM (61%) than in animals without POM (32%, p = 0.001). Forced eustachian tube opening pressures did not correlate with P. aeruginosa susceptibility. Thus, P. aeruginosa, the principle pathogen of chronic suppurative otitis media, can invade the middle ear by way of the eustachian tube, and acute otitis media predisposes to middle ear infection by P. aeurginosa.

A test for linear trend in constant hazards and its application to a problem in occupational health

A score test is derived for testing a linear trend in constant hazards. The test is applied to prove the attenuation of healthy worker effects in the analysis of occupational mortality.

Buthionine sulfoximine reduces the protective capacity of myocytes to withstand peroxide-derived free radical attack

Mammalian heart myocytes have a limited capacity to withstand the deleterious effects of free radical generating compounds. To assess the role of the glutathione redox cycle relative to this capacity, rat heart cell cultures were subjected for 90 min to 80 mumol/l cumene hydroperoxide (CHPO) without and with prior glutathione depletion by buthionine sulfoximine. Preincubation of cultures with 125 mumol/l buthionine sulfoximine for 2 h and 17 h caused a reduction of glutathione by 33% and 82%, respectively, without concomitant increase of glutathione disulfide. Subsequent incubation with CHPO for 90 min caused slowing of NADPH consumption (in the first 20 min 27 pmol vs 68 pmol without pretreatment with buthionine sulfoximine for 17 h), which indicates that glutathione depletion reduced the turnover rate of the glutathione redox cycle. Pretreatment with buthionine sulfoximine for 17 h exaggerated the negative chronotropic effects of CHPO: the time elapsed to 50% of baseline contraction frequency fell from 5.7 +/- 1.4 min without buthionine sulfoximine to 3.7 +/- 0.4 min after pretreatment with buthionine sulfoximine (P < 0.02). The severity of CHPO-induced lipid peroxidation as assessed by malondialdehyde formation (2.23 +/- 0.51 vs 0.99 +/- 0.05 nmol in the first 20 min; P < 0.05) was increased by buthionine sulfoximine pretreatment, as was the extent of cell necrosis as assessed by release of alpha-hydroxybutyrate dehydrogenase (39.5 +/- 5.1 vs 29.0 +/- 12.9% in the first 45 min). A "sublethal" dose of 10 microM CHPO for 60 min caused no substantial HBDH release, no formation of malondialdehyde, and no exhaustion of cellular GSH (35 nmol/U HBDHt = 0). However, following pretreatment with buthionine sulfoximine, 10 microM CHPO for 60 min produced 12% HBDH release and extensive lipid peroxidation (1.95 nmol malondialdehyde/U HBDHt = 0). As the deleterious effects of CHPO were aggravated by glutathione depletion, we conclude that the glutathione redox cycle plays a major role in the protection of myocytes against peroxide-induced free radical attack.

Pneumococcal capsular polysaccharide-meningococcal outer membrane protein complex conjugate vaccines: immunogenicity and efficacy in experimental pneumococcal otitis media

Vaccines composed of pneumococcal capsular polysaccharides (PS) conjugated to outer membrane protein complex (OMPC) from Neisseria meningitides group B bacteria were tested in the chinchilla otitis media model. Monovalent (types 6B and 23F), bivalent (6B+23F), and tetravalent (6B+14+19F+23F) PS-OMPC conjugate vaccines elicited significant total serum antibody responses against all four PS. Type 6B vaccine elicited IgG, IgM, and IgA antibodies after a single dose and an anamnestic IgG response after a second vaccine dose on day 28. Type 6B and 19F vaccines prevented or greatly attenuated pneumococcal otitis media after direct middle ear challenge with the immunizing serotype, type 14 vaccine was not protective by this challenge route, and type 23F pneumococci were not sufficiently virulent in chinchillas to test vaccine effectiveness. The promising results with two serotypes suggest the PS-OMPC conjugates may be useful in human infants.

A clinical profile of otitis media

An otitis media with effusion algorithm developed by Paradise et al and tested by Cantekin et al has become the basis for many studies of otitis media. However, a two-point scale algorithm (otitis media with effusion-no otitis media with effusion) may be too ambitious (ie, low specificity) and too optimistic (ie, absence of fluid does not necessarily mean normal ear). We propose a four-point profile that characterizes the condition of the middle ear, and we report the validation of the profile against findings at myringotomy. Statistically, a four-point scale profile would substantially increase powers of statistical tests, compared with a two-point scale algorithm (in studies of the same size), when used to study changes of the middle-ear condition over time or to compare treatment effects.