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The effects of kainic acid (KA) on neurogenesis in the developing rat hippocampus were investigated. Neonatal [postnatal day (P) 7] rats received a single bilateral intracerebroventricular infusion of KA (50 nmol in 1.0 microl) or vehicle. At P14, P25, P40, and P60, the spatial and temporal relationships between the neurodegeneration and neurogenesis induced by KA were explored using terminal deoxynucleotidyl transferase-mediated biotinylated UTP nick end labeling (TUNEL) to detect the dying cells and 5-bromodeoxyuridine (BrdU) to label newly generated cells. There was progressive loss of neurons in the cornu ammonis (CA) 1 and CA3 subfields of the hippocampus at all time points in KA-treated rats. TUNEL staining identified dying cells at P14 through P60, mainly in the CA3 subfield. The number of TUNEL-positive cells decreased with age. Neurogenesis also was observed in the KA-treated hippocampus. The number of BrdU-positive cells in the dentate gyrus was significantly decreased at P14, when the number of TUNEL-positive cells is highest. However, at later time points (P40 and P60) the number of BrdU-positive cells in the dentate gyrus was significantly increased. In addition, the number of BrdU-positive cells was increased in the CA3 subfield at P40 and P60 in KA-treated rats. A substantial proportion (40%) of the newly generated cells in CA3 also expressed markers of immature and mature neurons (class III beta-tubulin and neuronal nuclei). Newly generated cells in the CA3 subfield only rarely expressed glial markers (8%). These results suggest that a single exposure to KA at P7 has both immediate (inhibition) and delayed (stimulation) effects on neurogenesis within the dentate gyrus of developing rats. KA administration resulted in both neuronal apoptosis and neurogenesis within the CA3 subfield, suggesting that the purpose of neurogenesis in the CA3 is to replace neurons lost to apoptosis.

Time-driven activity-based costing allows detailed understanding of not only personnel costs but also how personnel time is used. This in turn allows testing of alternative staffing models to decrease unused personnel capacity and increase efficiency.

Objectives: (1) Compare the air-bone gap between patients with posterior epitympanic (attic) and posterior mesotympanic (tensa) cholesteatomas. (2) Correlate the air-bone gap and intraoperative ossicular chain findings.Methods: Cross-sectional study. In total, 262 patients with attic and tensa cholesteatomas treated at a tertiary hospital were included. Audiometry was performed, and the pure tone average air-bone gap (PTA-ABG) was compared between the 2 groups. In addition, ossicles were classified as normal, eroded, or absent based on intraoperative evaluation. Data were compared using the Mann-Whitney and Chi-square tests, and statistical analysis was performed using SPSS.Results: Attic cholesteatoma was diagnosed in 51.1% of patients and tensa cholesteatoma in 48.9%. The mean patient age was 33 ± 18.7 years, and 52.3% were male patients. The PTA-ABG was higher in tensa cholesteatoma cases than in attic cholesteatoma (30.25 ± 12.82 dB and 26.73 ± 13.08 dB, respectively, P = .031). There were no differences in the malleus erosion or absence prevalence and the stapes suprastructure prevalence (P = .09 and P = .17, respectively). The incus was normal in 17.6% of the attic and 6.3% of tensa cholesteatoma cases; eroded in 79.4% of tensa and 48.6% of attic cases; and absent in 33.8% of attic and 14.3% of tensa cholesteatoma cases (P < .01).Conclusions: The PTA-ABG was higher in tensa cholesteatoma cases and correlated with a lower normal incus prevalence and a higher eroded incus prevalence compared to attic cholesteatoma cases.

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