A B S T R A C T Alveolar macrophages (AM) and peritoneal macrophages (PM) originate from common precursor cells, but function in different 02 environments. In the present studies, the impact of different 02 tensions on cell metabolism has been quantitatively determined, an enzymatic basis for these differences established, and a mechanism which regulates enzymatic differences demonstrated. 02 consumption and lactate production were compared in rabbit AM and PM in air and nitrogen. In air, AM demonstrate significantly greater 02 utilization. In nitrogen, (where glycolysis is the major source of energy provision) lactate production is two-to threefold greater in the PM.A comparison of several enzymes of energy metabolism in AM and PM indicate that one basis for the differences in cell energetics is a difference in activity of key enzymes of both the oxidative phosphorlylative and the glycolytic sequences.Exposure of cultivated AM to hypoxic conditions results in changes in the activity of these enzymes such that the AM closely resembles the PM. A key enzyme in oxidative phosphorylation (cytochrome oxidase) shows decreased activity and reaches values similar to those found in the PMI. A key enzyme in glycolysis (pyruvate kinase) shows increased activity to values resembling those found in the PM. These alterations in enzyme pattern occur in isolated cell systems, suggesting that molecular 02 modifies the Dr.

To identify clinical risk factors that predict a higher incidence of hearing loss in children with bacterial meningitis, to determine the overall incidence of hearing loss in a large group of children proven by culture findings to have bacterial meningitis, and to compare clinical characteristics among patients with Streptococcus pneumoniae meningitis and Neisseria meningitidis meningitis. Design: Retrospective review Setting: Tertiary pediatric hospital. Patients: A total of 171 children identified with bacterial meningitis who met inclusion criteria over a consecutive 10-year period. Main Outcome Measure: Presence of sensorineural hearing loss. Results: Of 134 patients who underwent audiologic testing during their initial hospitalization, 41 (30.6%) were found to have at least a unilateral mild sensorineural hearing loss. The incidence of hearing loss was greater in patients with S pneumoniae meningitis than in patients with N meningitidis meningitis (35.9% and 23.9%, respectively). Length of hospitalization, development of seizures, elevated cerebrospinal fluid protein, and decreased cerebrospinal fluid glucose were significant predictors for hearing loss in children with bacterial meningitis. These factors were not found to be as strong a predictor for hearing loss in patients with N meningitidis meningitis. Stability of hearing was demonstrated with limited follow-up audiometry. Conclusions: Sensorineural hearing loss is a common sequela in children with bacterial meningitis. Identification of hearing loss in children with bacterial meningitis and early rehabilitation will lessen the long-term educational and social difficulties these children may experience.

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