The effect of pH on the Km values for ammonia was studied in its oxidation by Nitrosomonas cells and cell-free extracts. The Km values decreased markedly with increasing pH, suggesting (NH3) rather than (NH,+) as the actual substrate for oxidation. Nitrosomonas europaea and other nitrifying bacteria are normally considered to use ammonium ion (NH,+) as substrate for oxidation to

The oxidation of elemental sulfur by Thiobacillus thiooxidans was studied at pH 2.3, 4.5, and 7.0 in the presence of different concentrations of various anions (sulfate, phosphate, chloride, nitrate, and fluoride) and cations (potassium, sodium, lithium, rubidium, and cesium). The results agree with the expected response of this acidophilic bacterium to charge neutralization of colloids by ions, pH-dependent membrane permeability of ions, and osmotic pressure.

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Pulmonary alveolar proteinosis (PAP) is a disease characterized by the filling of alveolar spaces with periodic acid-Schiff-positive proteinaceous material and by the hypertrophy of type II pneumocytes in the alveolar interstitium. To examine if KL-6, a mucinlike glycoprotein, is useful for the diagnosis of PAP and the estimation of its activity, serum KL-6 levels in patients with PAP were measured by an enzyme-linked immunosorbent assay and compared with those of patients with other lung diseases. Furthermore, to estimate the origin of KL-6 in some patients, measurements of KL-6 levels in bronchoalveolar lavage (BAL) fluid and immunohistochemical staining of the lung tissues with a monoclonal antibody to KL-6 antigen were performed. Serum KL-6 levels in patients with PAP were extremely high and were significantly higher than those in patients with interstitial lung diseases in which elevation of serum KL-6 has been recognized. BAL-fluid KL-6 levels in patients with PAP were higher than serum levels. Both serum and BAL-fluid KL-6 levels in patients with PAP correlated well with the disease activity. Immunohistochemically, positive staining was observed in proliferating type II pneumocytes. These results suggest the usefulness of KL-6 measurement in the diagnosis and estimation of disease activity of PAP.

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