Heavy and trace metals in carcinoma of the gallbladder.

BACKGROUND: Carcinoma of the gallbladder is the commonest malignancy of the biliary tract in northern India The etiologic relation of specific metals (heavy and trace) and their compounds to neoplasia has been a topic of investigation for some time but not adequately described for carcinoma of the gallbladder. The aim of the present study was to evaluate the relation of heavy and trace metals to this malignancy. METHODS: The levels of selenium, zinc, copper, manganese, cadmium, chromium, lead, and nickel were estimated in serum, bile, gallstones, and gallbladder tissue using atomic absorption spectrophotometry. The tests were carried out in 30 patients with gallbladder cancer and 30 sex-matched patients with cholelithiasis. RESULTS: Selenium and zinc levels were significantly reduced (p < 0.001) and copper concentration was found to be significantly higher (p < 0.001) in serum, bile, and gallbladder tissue from patients with carcinoma of the gallbladder. Lead, cadmium, chromium, and nickel levels were elevated in serum and bile in patients with carcinoma of the gallbladder. CONCLUSIONS: The present study demonstrated a significant decrease in serum, biliary, and tissue levels of selenium and zinc but increased copper, lead, cadmium, chromium, and nickel levels in patients with carcinoma of the gallbladder, indicating a strong relation between the concentrations of these metals and gallbladder cancer.

Identification of maltooligosyltrehalose synthase and maltooligosyltrehalose trehalohydrolase enzymes catalysing trehalose biosynthesis in Anabaena 7120 exposed to NaCl stress.

Anabaena 7120 cells were exposed to NaCl (25-175 mM) stress. Maximum growth was recorded in media containing 150mM NaCl. Short-term exposure (48h) of the cyanobacterial biomass to 150mM NaCl, induced highest trehalose level (37mM). Control cells lacking NaCl did not show any trace of trehalose as ascertained by NMR and HPLC analysis. Trehalose biosynthesis observed with NaCl plus high temperature (40 degrees C) indicated that its production was specifically triggered by NaCl, not temperature. The increase in trehalose level during NaCl stress was the result of overexpression of the trehalose-forming enzymes maltooligosyltrehalose synthase (MTSase), EC 5.4.99.15 (114kDa) and maltooligosyltrehalose trehalohydrolase (MTHase), EC 3.2.1.141 (68 kDa) as evidenced by SDS-PAGE analysis. To our knowledge this is the first report of induced trehalose biosynthesis in Anabaena 7120 during salt-stress, accompanied by identification of MTSase and MTHase enzymes on gel. It is suggested that Anabaena 7120 cells synthesize the osmolyte trehalose to withstand osmotic fluctuations.

Trehalose-producing enzymes MTSase and MTHase in Anabaena 7120 under NaCl stress.

Salt tolerance, a multigenic trait, necessitates knowledge about biosynthesis and function of candidate gene(s) at the cellular level. Among the osmolytes, trehalose biosynthesis in cyanobacteria facing NaCl stress is little understood. Anabaena 7120 filaments exposed to 150 mM: NaCl fragmented and recovered on transfer to -NaCl medium with the increased heterocysts frequency (7%) over the control (4%). Cells failed to retain Na+ beyond a threshold [2.19 mM/cm3 (PCV)]. Whereas NaCl-stressed cells exhibited a marginal rise in K+ (1.1-fold) only at 30 h, for Na+ it was 130-fold at 48 h over cells in control. A time-course study (0-54 h) revealed reduction in intracellular Na+ beyond 48 h [0.80 mM/cm3 (PCV)] suggestive of ion efflux. The NaCl-stressed cells showed differential expression of maltooligosyltrehalose synthase (MTSase; EC 5.4.99.15) and maltooligosyltrehalose trehalohydrolase (MTHase; EC 3.2.1.141) depending on the time and the extent of intracellular Na+ buildup.