Studies on the iodinated surface membrane proteins and concanavalin A agglutination of transformed Syrian hamster cells.

Chemically transformed Syrian hamster cells exhibit marked agglutination in the presence of the plant lectin, concanavalin A. In this report, we describe conditions which can alter this concanavalin A agglutinability, and compare the surface proteins from transformed cells which express different degrees of agglutinability. Lactoperoxidase-catalyzed iodination of tertiary Syrian hamster cells reveals the major iodinatable protein to be approximately 220 000 daltons.

Some fundamental applications of the Law of La Place in Neurosurgery.

The Law of La Place is a simple principle of physics, applicable to any fluid-filled vessel, relating stress on the wall of the vessel to the radius and transmural pressure. This principle has major implications for neurosurgery and examples are provided relating La Place's Principle to the genesis and treatment of hydrocephalus, the surgical clipping of cerebral aneurysms and the technic of surgical sponge hemostatis.

In vitro correlates of transformation in C3H/10T1/2 clone 8 mouse cells.

Various potential in vitro correlates of malignancy were studied in four chemically transformed C3H/10T1/2 Clone 8 mouse cell lines and were compared with controls cells. The degree of tumorigenicity was best predicted by the relative plating efficiencies of the morphologically transformed cells in soft agar. All transformed cells also showed an increase in extracellular fibrinolytic activity which may be an additional marker for transformation.

Removal of basement membrane in the involuting breast.

Morphologic and immunohistochemical studies by light and electron microscopy indicated that basement membrane was removed during the process of involution of the murine breast. Removal of the basement membrane started 2 days postweaning, was maximal at 4 days, and correlated with degeneration of epithelial cells. There was no evidence of phagocytosis of basement membrane, so the removal of this antigen was attributed to enzymatic hydrolysis.

Localization of the beta chain of human chorionic gonadotropin on human tumor cells and placental cells.

With the use of peroxidase-labeled antibody to the beta chain of human chorionic gonadotropin, sections of ten human malignant tumors were found to react with this antibody. It is postulated that both selective host immunosuppression by tumors and selective maternal immunosuppression by fetal tissues may be mediated by human chorionic gonadotropin.

The effect of modification of T7 DNA by the carcinogen N-1-acetylaminofluorene: termination of transcription in vitro.

To study the effects of N-2-acetylaminofluorene (AAF) modification of DNA on transcription, purified DNA from bacteriophage T7 was modified in vitro to varying extent with AAF and transcribed by DNA-dependent RNA polymerase from Escherichia coli. The main effects of AAF modification on transcription are a marked inhibition of the rate and extent of trna synthesis with relatively little effect on initiation except at very high AAF doses. Calibration of the percent modification with [14-C]AAF and analysis of the size of the RNA product by double isotope labeling and polyacrylamide gel electrophoresis support the following mechanism of transcription inhibition: most of the AAF residues bound to the coding strand of the DNA cause premature termination of transcription, at or near the site of modification, with release of RNA polymerase.

Ripple Marks Show That Countercurrent Exists in Florida Straits.

About 60 percent of the area shown in photographs taken at the axis of Florida Straits exhibits well-defined current ripple marks. These ripples indicate a flow of water of at least 0.2 to 0.