Treatment of human monocyte U937 and promyelocyte HL-60 cultures with agents known to induce differentiation (12-0-tetradecanoylphorbol 13-acetate, calcitriol and dimethylsulfoxide) accelerates the maturation of cathepsin D and enhances the incorporation of [ 35 S]methionine into cathepsin D. The most pronounced effects are obtained with calcitriol, which at a concentration of 10~7M increases the incorporation of [ 35 S]methionine into cathepsin D from 0.08% to 0.4% of the detergent-soluble radioactivity. In addition, this treatment enhances the secretion of cathepsin D from about 8% to > 16% of the newly synthesized enzyme. In the presence of 1 OmM NH 4 C1 approximately half of the produced cathepsin D is secreted in both control and calcitriol-treated cells. It appears that in U937 cells two mechanisms are involved in sorting of cathepsin D. One of these is sensitive to NH 4 C1 and its efficiency is selectively decreased in cells pretreated with calcitriol. Synthese, Reifung und Sekretion von Cathepsin D in differenzierungsinduzierten U937-undHL-60-ZellenZusammenfassung: Induktion der Differenzierung in humanen Monozyten U937 und Promyelozyten HL-60 mit 12-O-Tetradecanoylphorbol-13-acetat, Dimethylsulfoxid und Calcitriol fuhrt zu einer Beschleunigung der Reifung von Cathepsin D. Zusätzlich kommt es zu einer unterschiedlich ausgeprägten Steigerung des Einbaus von [ 35 S]Methionin in Cathepsin D. Eine mehrfache Steigerung der apparenten Synthesegeschwindigkeit wird insbesondere durch Behandlung von U937-Zellen mit Calcitriol erzielt. Der Anteil des Cathepsins D an der gesamten Markierung des extrahierbaren Proteins steigt von etwa 0.08% auf 0.4%. Außerdem steigt der Anteil des sezernierten Cathepsins von etwa 8% auf > 16%. Ammoniumchlorid, l OmM, induziert in unbehandelten sowie in Calcitriolbehandelten Zellen die Sekretion etwa der Hälfte des neu-synthetisierten Cathepsins D. Die Ergebnisse weisen auf die Existenz von zwei Sortierungsmechanismen für Cathepsin D in U937-Zellen hin, von denen der eine NH 4 Cl-sensitiv ist. Behandlung mit Calcitriol reduziert den Anteil des NH 4 Cl-sensitiven Mechanismus am Transport vom Cathepsin D.

The oncolytic effects of encephalomyocarditis (EMC) virus were examined in human retinoblastoma cell (Y79) cultures which were infected with 10(4 )tissue culture infectious doses (TCIDs) of the E variant of EMC (EMC-E) virus. The TCIDs were used to titer the maximum effect of EMC virus on L-929 cells. In-vitro studies showed 90% cytopathic effect (CPE) at 24 h and 100% CPE at 52 h. The CPE was used to observe pathologic effects of the cells. In-vivo studies employing human retinoblastoma grown as a tumor in nude mice, revealed degeneration of 80% of the tumor cells at 3 days and total destruction at 4 days following inoculation with the EMC-E virus. The virus is highly neurotropic in mice, but is usually not pathogenic in man. These studies suggest a possible new direction in the treatment of retinoblastoma and other malignant tumors using the viral technology.

SUMMARY Studies were made on the components of lysosomes. Analyses were based upon the distribution of constituents between the insoluble fraction containing the membrane and bound proteins and tbe soluble fraction containing released enzymes. Results were compared with those obtained for mitochondria and microsomes. The composition of the lysosomal membrane was characteristic of a unit phospholipid‐protein membrane. The sialic acid content of lysosomes was not much greater than that found in other subcellular fractions, suggesting that sialopolymers are not involved in a special role in lysosomes. The released enzyme fraction, which contained about myc of the total protein, also contained free flavins and free amino acids in amounts very much larger than those observed for mitochondria. Fe, Zn, Cu, Mn, and MO were the principal metals concentrated in lysosomes. The relationship between the chemical composition, structure, and function of lysosomes is discussed.

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