Search

An approach for the synthesis of carbonic anhydrase (CA, EC 4.2.1.1) inhibitor coated gold nanoparticles is reported. This nanomaterial selectively inhibited the tumor-associated isoform CA IX overexpressed in hypoxic cancers over the ubiquitous, cytosolic housekeeping isozymes CA I and II and was membrane impermeant. As CA IX has an extracellular active site, the new nanomaterial which is confined to the extracellular space may be useful for imaging and treatment of hypoxic tumors.

Cell-to-cell adhesion is mediated by cadherins (integral membrane proteins), which form a complex with catenins (cytoplasmatic proteins). While E-cadherin expression has been extensively studied in many human skin diseases, less is known about the expression levels of catenins in oral blistering diseases. The purpose of this study was to evaluate the role of these proteins in the pathogenesis of acantholysis in oral pemphigus vulgaris. We evaluated by immunohistochemistry beta- and gamma-catenin expression in 7 cases of oral pemphigus vulgaris (PV) at various stages of the disease and, as controls, in 18 healthy patients. Healthy cases showed, as reported in the literature, a strong reactivity with both beta- and gamma-catenins, with the intensity of staining progressively decreasing from the spinous to the keratinised layers of epithelium, which had a prevalent cellular membrane expression. In PV patients, we detected a loss of membrane expression of these molecules with a progressive displacement of the signal toward the cytosol and, for gamma-catenin, nuclear dislocation, particularly in areas with intense acantholysis.

Incubation of rat liver cytosolic or microsomal fractions with chromium(VI) led to a dramatic decrease in chromium(VI) mutagenicity, as determined by the Ames Salmonella assay using the TA100 tester strain. The cytosol-dependent decrease in chromium(VI) mutagenicity was found to be counteracted in the presence of dicumarol, an inhibitor of the cytosolic enzyme NAD(P)H:quinone oxidoreductase (DT-diaphorase). In order to determine whether DT-diaphorase is a significant factor in enzymatic reduction of chromium(VI) in rat liver tissue, cytosolic and microsomal fractions were analyzed for NAD(P)H-dependent chromium (VI) reductase activity leading to chromium(V) formation by using electron paramagnetic resonance (EPR) spectroscopy. Reaction of chromium(VI) with NADH or NADPH in the presence of either cytosolic or microsomal fractions led to the formation of stable chromium(V)--NAD(P)H complexes. When glucose 6-phosphate (G6P) was present in the reaction as part of a NADPH-generating system, stable chromium(V)--G6P complexes were formed in addition to the chromium(V)--NAD(P)H complexes. The chromium(V) complexes had g values of 1.980-1.982 and superhyperfine splitting constants of 0.8-0.9 characteristic of bis(diol)oxochromium(V) complexes. Inhibition of 90% of the cytosolic DT-diaphorase activity by dicumarol led to only partial (20-22%) inhibition of chromium(V) formation. Visible and EPR spectroscopic studies showed that purified DT-diaphorase had no detectable chromium(VI) reductase activity and did not catalyze formation of chromium(V). Inhibition of 69% of microsomal aryl hydrocarbon hydroxylase activity by ketoconazole led to partial (10%) inhibition of chromium(V) formation. These results indicate that intracellular NAD(P)H-dependent enzymatic reduction of chromium(VI) in rat liver cannot be attributed to the activity of any one enzyme in the cytosolic or microsomal fractions. DT-diaphorase appears to play an indirect role in decreasing chromium(VI)-induced mutagenicity in Salmonella, possibly through interaction with other redox active cellular components. The involvement of diols such as sugars and pyridine nucleotides in stabilizing intracellularly generated chromium(V) is discussed.

Specimens of the seawater fish annular seabream (Diplodus annularis) were caught from a polluted harbor area and from a clean reference area. Seawater concentrates and fish-muscle extracts were not mutagenic in the Salmonella reversion test. Liver preparations of fish from the 2 sources were comparatively assayed for microsomal mixed-function oxidases and cytosolic biochemical parameters, as well as for the ability of S12 fractions to activate promutagens or to detoxify direct-acting mutagens. A shift of the cytochrome P-450 peak from 450.3 to 448.5 was accompanied by a 4.5-fold increase in arylhydrocarbon hydroxylase activity in fish living in the polluted environment. At the same time, glucose 6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase were doubled in the cytosol of the same animals, while reduced glutathione (GSH) peroxidase and GSH S-transferase were slightly yet significantly depressed. No significant difference was recorded for other biochemical parameters, including GSH, oxidized glutathione (GSSG) reductase, NADH- and NADPH-dependent diaphorases, and DT diaphorase. In parallel, fish exposed to polluted seawater exhibited a significant and marked enhancement of the metabolic activation of the pyrolysis product Trp-P-2 and of benzo[a]pyrene-trans-7,8-diol, and at the same time were less efficient in detoxifying the antitumor compound ICR 191. Liver S12 fractions from both sources efficiently decreased the direct mutagenicity of sodium dichromate, and failed to activate benzo[a]pyrene and aflatoxin B1 to mutagenic metabolites. These results provide evidence that both biochemical parameters and the overall capacity of fish liver to activate or detoxify certain mutagens can be assumed to be sensitive indicators of exposure to mixed organic pollutants in the marine environment.