Research communications in chemical pathology and pharmacology最新文献

Hepatocyte growth factor (HGF) is a novel mitogen for mature hepatocytes. In the present study, we have measured immunoreactive (ir)-HGF concentration in tumor extracts of 82 primary human breast cancers using an enzyme-linked immunosorbent assay (ELISA). Ir-HGF was detectable in all tissue extracts, the concentration ranging from 1.4 to 306.5 ng/100 mg protein (median value: 11.2 ng/100 mg protein). Correlation analyses between ir-HGF concentration and clinicopathological factors showed that the ir-HGF level was significantly higher in tumors with sizes of more than 5.0 cm compared with those less than 5.0 cm. In contrast, no detectable amount of ir-HGF was secreted into culture medium of two breast cancer cell lines, MCF-7 and ZR-75-1, suggesting that the cancer cell itself has no ability to produce ir-HGF.

L-Ascorbic acid 2-(20 beta-11-oxo-olean-12-en-29-oic acid ethylester-3-beta-yl hydrogen phosphate) sodium salt (GEPC) is a newly synthesized compound representing a phosphate diester linkage of glycyrrhetic acid ethylester and ascorbic acid. In the present study, we found that GEPC effectively inhibited Fe(III)-ADP/NADPH-induced peroxidation of liver microsomes. The inhibitory effect was much greater than that of glycyrrhetic acid (GA), and contrasted with the stimulatory effect of ascorbic acid. An ESR study showed that GEPC appeared to have a great loss of the DPPH and superoxide radical scavenging effects of ascorbic acid. However, GEPC, like ascorbic acid, inhibited hydroxyl radicals generation in both Fe(II)-H2 O2 and Cr(VI)-H2 O2 systems. GEPC, unlike ascorbic acid, showed no pro-oxidant effect and acted as an effective iron-chelating agent in the ESR study or in the iron-induced deoxyribose and DNA degradation assays. The hydroxyl radical scavenging effect of GEPC was further demonstrated by its protective effect on the hydroxyl radical- induced degradation of certain biomolecules, i.e., carbohydrates, amino acids, and DNA. These results demonstrate that beside its protective effect on ascorbic acid autoxidation and increasing water solubility of GA, GEPC is also an antioxidant though not so powerful as ascorbic acid but more powerful than GA.

Isolated hepatocytes from rat liver in primary culture rapidly lost viability under hypoxic conditions. Hypoxic injury was significantly decreased by the calcium channel blockers nifedipine (5 microM) and diltiazem (10 microM). The concentrations of the inhibitors which afforded maximum protection also produced the maximum increase in the energy level of the hypoxic hepatocytes, as evidenced by their ATP, ADP, AMP, and total adenine nucleotide content and by their energy charge. The increased hypoxic energy level caused by these calcium channel blocking agents was not due to an increased rate of anaerobic glycolysis; nifedipine did not have any effect on lactate production while diltiazem slightly decreased its rate. During the first 2 h under hypoxic conditions the cytosolic Ca2+ concentration remained constant around 100 nM, subsequently increasing to 400 nM first slowly and later more rapidly. The calcium channel blockers delayed the Ca2+ increase by about 1 h but were without any effect on the rate of this increase. The results suggest that the well-known beneficial effects of calcium channel blockers on hypoxic liver injury are due in large measure to an improved energetic situation of the hepatocytes rather than to the increase in the cytosolic Ca2+ concentration being blocked.

Copper (Cu) accumulating in the liver of LEC (Long-Evans with a cinnamon-like coat color) rats due to a hereditary metabolic disorder is assumed to cause acute hepatitis with severe jaundice or chronic hepatitis leading to cancer. Changes in concentrations and distributions of Cu, zinc and iron in the liver of LEC rats were determined to find the relationship between the chemical forms and the toxicity. Female rats after delivery were used because of high susceptibility to acute hepatitis. They were divided into four stages according to the development of jaundice. Cu concentrations in the whole liver and the supernatant decreased with development of jaundice. Distribution profiles of Cu, zinc, iron and sulfur on a gel filtration column by HPLC-ICP showed that Cu in the liver supernatant was mostly bound to metallothionein (MT) before jaundice (stage 1), high molecular weight proteins and MT at the beginning of jaundice (stages 2 and 3), and then mostly to MT at severe jaundice (stage 4) though the concentration of Cu at this stage was decreased to about 50% of stage 1. The results suggest that Cu accumulating as MT in the liver is liberated drastically after exceeding the capacity of MT synthesis, and the liberated Cu causes acute hepatitis.

CCl4 is a hepatic carcinogen in male Osborne-Mendel (OM) but not in Sprague Dawley (SD) male rats. We demonstrate the occurrence of NADPH-dependent CCl4-promoted lipid peroxidation processes (LP) leading to malondialdehyde (MDA) formation in liver microsomal and nuclear preparations from OM and SD rats which do not correlate with the cancer susceptibility of both strains. Our results suggest that MDA production might not be a rate determining step in the carcinogenic process. However, the formation of this reactive aldehyde proximal to DNA and nuclear proteins might play a role that remains to be elucidated.

Copper (Cu) accumulating bound to metallothionein (MT) in the liver of LEC (Long-Evans with cinnamon-like coat color) rats due to a hereditary metabolic disorder is assumed to lead to acute hepatitis with severe jaundice. The metal was shown to be present in the liver in a form not bound to MT at the beginning of hepatitis after first delivery and lactation. Following this change in the distribution of Cu from MT-bound to non-MT bound form in the liver, changes in the concentrations and distributions of Cu, zinc (Zn) and iron in the plasma and kidneys of LEC rats were also observed. Cu plasma distribution on a gel filtration column by HPLC-ICP revealed that the holo-form of ceruloplasmin (Cp) was present before hepatitis and increased with its development, indicating the availability of Cu for Cp by hepatitis. Cu-binding proteins migrating at the same retention times as those of hepatic Cu-MT and Cu,Zn-superoxide dismutase (SOD) were detected in plasma during hepatitis. Albumin was largely present in the form of nonmercaptoalbumin, reflecting that the bloodstream was under oxidative stress. A sudden increase in the concentration of Cu in the kidneys occurred with hepatitis, and the metal came to be distributed more to high molecular weight proteins with its development.

We investigated the effects of 23 drugs on the metabolism of FK506 by human liver microsomes. Acyclovir, amphotericin B, cefixime, cefotaxime, ciprofloxacin, cyclosporin A, diltiazem, enoxacin, erythromycin, ethinyl estradiol, fluconazole, fosfomycin, kanamycin, lincomycin, loxoprofen, minocyclin, nifedipine, nilvadipine, norethindrone, ofloxacin, phenobarbital, prednisolone, or rifampicin was added to the reaction media at equimolar or at ten times an excess molar ratio of the substrate concentration; their effects on FK506 metabolism were examined. Drugs known to be the substrate of cytochrome P-450 3A inhibited the metabolism of FK506, and among the drugs tested, the inhibition by cyclosporin A and nifedipine was the strongest.

The anxiolytic properties of melatonin are revealed by two behavioral studies. In a free exploratory situation, the holeboard test, melatonin decreased head-dip performance. In an unconditioned conflict test, the light/dark box choice situation, melatonin increased the time spent in the lit box as well as the number of transitions between the two compartments. Melatonin was given in a dose range from 0.5 to 5.0 mg/kg body weight i.p. 30 minutes before testing in daytime. Moreover, the anxiolytic activity of diazepam (2.5 mg/kg i.p.) was evaluated and found to be completely inhibited by the specific benzodiazepine antagonist flumazenil (10 mg/kg i.p. 30 minutes before). In the same manner flumazenil counteracted melatonin activity in the two tests. Involvement of the benzodiazepine/GABAergic system in the anxiolytic activity of melatonin is discussed.

Glycerol enhances pulmonary tumorigenesis in mice treated with 4-nitroquinoline 1-oxide (4NQO). In order to evaluate factors that contribute to the enhancing effect of glycerol on 4NQO-induced pulmonary tumorigenesis, we selected alveolar macrophage (AM) as a source of active oxygen formation in the lung and investigated the effects of glycerol on active oxygen formation in AMs treated with 4NQO. AMs were stimulated with opsonized zymosan, and active oxygen formation in AMs was examined after stimulation. Continuous glycerol treatment within 4 weeks after 4NQO injection has no influence on the capacity of active oxygen generation in AMs (expressed as maximum count of chemiluminescence) and the total amount of active oxygen generation in AMs (expressed as total count of chemiluminescence). These results suggest that active oxygen formation in AMs does not contribute to enhance 4NQO-induced pulmonary tumorigenesis in mice treated with glycerol.

The excretion of urinary glycosaminoglycans by five occupationally exposed men with urinary cadmium levels of 1 to 6.5 micrograms/g creatinine did not differ significantly from that of six age-matched non-exposed controls (2.8 +/- 1.8 mg/mmol creatinine vs. 2.3 +/- 1.6 mg/mmol creatinine, +/- S.D.) as analyzed in random urine samples. However, there was a cadmium concentration-dependent increase in the excretion of 50 kD proteoglycan as analyzed by polyacrylamide electrophoresis of the isolated proteoglycan fraction in the same urine samples. This may represent the early dose-dependent effect of cadmium on renal tubules which leads to decrease in the renal cell sialic acid content and protein excretion at higher exposure levels.