The question addressed was whether stimulation of cell proliferation could be responsible for tumor induction in the forestomach by styrà ̈ne 7,8-oxide (SO). Male F344 rats were treated for 4 weeks with 0, 137, 275, and 550 mg/kg SO by p.o. gavage 3 times/week. Positive controls received 0, 0.5, 1, and 2% butylated hydroxyanisole (BHA) in the diet for 4 weeks. Twenty-four h before termination of...

by genes 62 and 44 (Jarvis et al., 1989). The bacterial, eukaryotic, and T4 bacteriophage proSummary cessivity factors are all structurally similar, even though they do not share significant sequence similarity (Kong The crystal structure of the d9 subunit of the clampet al., 1992; Krishna et al., 1994; I. Moarefi and J. K., loader complex of E. coli DNA polymerase III has been unpublished data...

Thoracic outlet syndrome (TOS) is one of the most controversial subjects in entrapment neuropathies. Views differ regarding the pathogenesis, diagnosis, and management of TOS. Some authorities even question its existence. In spite of lack of understanding of the disease, clinicians often encounter patients whose pain or neurologic deficits in the upper limb cannot be explained after ruling out ...

The hypothesis was tested that expression of bcl-2 could provide pro tection against apoptosis induced by cytotoxic drugs via a mechanism which was different from the classical determinants of drug resistance. Sensitivity and resistance to inhibitors of thymidylate synthase (EC 2.1.1. 45) were chosen for study since these drugs have a well-defined and quantifiable locus of action with similarly...

Tissue culture affords a method for the study of the direct effects of cytotoxins separated from the cellular defense, vascular reactions, clotting mech anism, and other mediators of resistance and homeostasis that exist in vivo. Lambert and Hanes in 1911 were the first to utilize this technic for such study (19). They reported that rat sarcoma would not grow in plasma coaguluni from guinea pig...

The hypothesis was tested that expression of bcl-2 could provide pro tection against apoptosis induced by cytotoxic drugs via a mechanism which was different from the classical determinants of drug resistance. Sensitivity and resistance to inhibitors of thymidylate synthase (EC 2.1.1. 45) were chosen for study since these drugs have a well-defined and quantifiable locus of action with similarly...

Mechanisms of tumor resistance to 4-hydroperoxycyclophosphamide (4-HC) were studied by using a panel of human medulloblastoma cell lines either passaged in the laboratory for resistance to 4-HC or estab lished from tumors showing clinical resistance to cyclophosphamide. Multiple distinct mechanisms of resistance were demonstrated. Daoy (4-HCR), a line that was 6-fold more resistant than Daoy, c...

In a previous paper on heterologous trans plantation of tumors, we (2) reported successful growth and serial propagation of a carcinoma of the human colon in irradiated and cortisonetreated weanling Wistar rats. The fact that 205 other malignant tumors failed to grow simply served to emphasize the well known presence of a highly effective protective mechanism normally possessed by animals again...

Leszek A. Kleczkowski Plant Physiology Department, University of Urnea, 901-87 Urnea, Sweden Z. Naturforsch. 50c, 21-28 (1995); received October 21/November 21, 1994 Alternative Substrate, Cyanide, Cytosol, Glycolate Pathway, Glyoxylate Reductase Kinetic mechanism of purified spinach leaf NAD(P)H glyoxylate reductase (GR-1) was studied using either NADPH and NADH as alternative substrates with ...

The selective action of vincristine (VCR) has been correlated with longer retention of the drug in neoplastic tissue compared with normal tissues of the mouse (J. A. Houghton, L. G. Williams, P. M. Terranee, and P. J. Houghton, Cancer Res., 44: 582-590, 1984). In order to examine the basis for this differential, the stability of drug-protein complexes was examined further. The stability of drug...