A rat model of otitis media with effusion caused by eustachian tube obstruction with and without Streptococcus pneumoniae infection: methods and disease course.

OBJECTIVE: To describe the clinical and histopathologic progression of a rat model of otitis media with effusion caused by eustachian tube obstruction (ETO) with and without Streptococcus pneumoniae infection. METHODS: In 164 rats, the left, bony eustachian tube was approached via a ventral incision and obstructed with dental material. Then 108 rats were infected via an intrabullar injection with S pneumoniae. At 48 hours, the infected rats were treated for 5 days with ampicillin. All ears were evaluated by weekly otomicroscopy. On each of days 1, 2, 7, 21, 35, 56, and 112, four rats were killed for histologic study. All effusions were cultured for bacteria. RESULTS: Fourteen rats died of surgical complications; effusion resolved by 2 weeks in 9 rats. During the first few days, infected ears with ETO had bulging tympanic membranes, followed by tympanic membrane retraction, purulent effusion, and otorrhea (50%) over the next few weeks, whereas uninfected ears with ETO developed retraction and serous effusion during the same time frame. At later times, all ears with ETO presented with retraction and serous or serous-mucoid effusion. S pneumoniae was recovered only from the infected ears with ETO (days 1 and 2), with some colonization by nonpathogenic microorganisms observed equally in both groups of ears. Histology showed a typical acute inflammatory reaction in the challenged ears with ETO through day 14 and then a chronic inflammation for all ears with ETO. CONCLUSION: The experimental methods provoked reproducible pathologic signs similar to those for otitis media with effusion. Given the availability of rat-specific reagents, this model is well suited for studies of cytokine elaboration during disease pathogenesis.     

Rate of nitrous oxide exchange across the middle ear mucosa in monkeys before and after blockage of the mastoid antrum.

OBJECTIVES: We tested the hypothesis that mastoid volume buffers the rate of change in middle ear pressure caused by transmucosal, inert gas exchange. STUDY DESIGN: Twelve monkeys were randomly assigned to group 1 or group 2. Right ears of group 1 had sham surgery and of group 2 had obstruction of the mastoid antrum. Before and after surgery, the time constant for transmucosal N(2)O exchange was estimated from N(2)O breathing experiments. The hypothesis predicts that the postoperative time constant measured for right ears of group 2 but not group 1 is greater than that measured before surgery. RESULTS: Mastoid antrum block significantly decreased right middle ear volume but did not affect the time constant for transmucosal N(2)O exchange. CONCLUSION: A mastoid gas-reserve function is not supported by the experimental data. SIGNIFICANCE: These results for monkeys and the theory developed to explain the effect of mastoid volume on transmucosal inert gas exchange suggest that the results for previous experiments in humans interpreted as evidencing a mastoid gas-reserve function are consistent with alternative explanations.     

The effect of varying impact energy on diffuse axonal injury in the rat brain: a preliminary study

Diffuse axonal injury (DAI) is seen as widespread damage in the white matter of brain characterized by morphological changes to axons throughout the brain and brain stem. The current study attempted to investigate the effect of increasing impact energy on the presence and severity of DAI in corpus callosum (CC). DAI was induced in adult male Sprague-Dawley rats using an injury model adapted from Marmarou et al. in 1994. A 450-g cylindrical brass weight was dropped from three different heights (2.0 m, 1.5 m and 1.0 m) on to a metal helmet affixed to the skull of the rats. In the sham group, rats underwent a surgical procedure with no impact. After a 24-h survival period the animals were transcardially perfused. The brain was removed and the cerebral hemispheres were sectioned with a vibrotome and stained by silver impregnation technique. The CC of all the impacted rats showed DAI in the form of beaded axons, retraction balls and vacuole-like enlargements. The axonal injury was most severe in the 2-m group, while mildest in the 1-m group. In the sham group, axons appeared to be normal. This study demonstrates evidence of graded DAI depending on the impact energy. Such data is useful for mathematical modeling of axonal injury in rat brain using the same impact parameters and potential determination of injury thresholds for neural trauma. Electronic Publication     

Matrix Metalloproteinase‐2 and ‐9 Levels in Patients with Dilated Ascending Aorta and Bicuspid Aortic Valve

Background: Predictors of aortic dilatation are not well‐described in patients with bicuspid aortic valve (BAV). Changes in extracellular matrix composition in the aortic wall may play an important role. Our study aimed to examine the relationship between ascending aortic dilatation and biochemical markers for collagen metabolism, such as matrix metalloproteinase‐2 (MMP‐2) and matrix metalloproteinase‐9 (MMP‐9) levels in patients with BAV. Methods: All patients underwent cardiac echocardiography using a standard protocol, and aortic measurements were made in end‐diastole. One hundred twelve BAV patients with no or mild valvular impairment were recruited and grouped according to the aortic dimensions corrected for body surface area (BSA) and age. There were 54 patients with dilated ascending aorta (Group 1) and 58 patients with nondilated ascending aorta (group 2). The plasma levels of MMP‐2 and MMP‐9 were determined by ELISA. Results: The mean ascending aorta diameter was 4.49 ± 0.49 mm in group 1 and 3.51 ± 0.46 mm in group 2 (P < 0.001). There were no significant difference in gender, BSA, presence of hypertension, diabetes mellitus, hyperlipidemia, and smoking between the 2 groups. Nevertheless, no significant difference was observed in the levels of MMP‐2 and MMP‐9 between the 2 groups. The ascending aorta diameter correlated significantly with age (r = 0.438 P < 0.001). No significant correlation was observed between plasma MMP‐2 and MMP‐9 concentration and ascending aorta diameter, respectively (r = ?0.005 P = 0.58, r = ?0.106 P = 0.07). Multivariate analysis showed that age was independent predictor of aortic dilatation (P ≤ 0.001). Conclusion: Age was an independent predictor of aortic dilatation in patients with BAV, whereas MMP‐2 and 9 levels were not relevant by aortic dilatation.     

Distinct temperament and character profiles in first onset vitiligo but not in alopecia areata

Alopecia areata (AA) and vitiligo (V) are diseases that are correlated with psychiatric disorders before, during and after diagnosis. The Temperament and Character Inventory (TCI) is a well‐established approach for investigating personality traits in various psychosomatic diseases. The aim of this study is to compare and investigate the differences in the TCI between patients with first onset AA, patients with V and healthy controls (HC). Participants in the study included 42 patients with first onset AA, 50 adult patients with V and 60 HC who had no history or diagnoses of psychiatric or dermatological disorders. All participants were assessed with the TCI and the Dermatology Life Quality Index (DLQI). Among the temperament traits, the extravagance, disorderliness and total novelty‐seeking scores were lower, and the worry and pessimism scores were higher in patients with V compared with patients with AA and the HC. The mean score of the enlightened second nature and the total self‐directedness score of the character traits were higher in patients with V compared with patients with AA and the HC group. In the AA group, there was a negative correlation only between the reward dependence total score and the DLQI score. This study suggests that patients with first onset V have a distinct temperament, such as being unenthusiastic and unemotional, and character profiles, such as worry and pessimism, independent of their psychiatric comorbidities, and patients with AA do not have a different personality from the non‐affected population.