Membrane-bound ß-catenin degradation is enhanced by ETS2-mediated Siah1 induction in Helicobacter pylori-infected gastric cancer cells.

ß-catenin has two different cellular functions: intercellular adhesion and transcriptional activity. The E3 ubiquitin ligase Siah1 causes ubiquitin-mediated degradation of the cytosolic ß-catenin and therefore, impairs nuclear translocation and oncogenic function of ß-catenin. However, the effect of Siah1 on the cell membrane bound ß-catenin has not been studied. In this study, we identified that the carcinogenic bacterium H. pylori increased ETS2 transcription factor-mediated Siah1 protein expression in gastric cancer cells (GCCs) MKN45, AGS and Kato III. Siah1 protein level was also noticeably higher in gastric adenocarcinoma biopsy samples as compared to non-cancerous gastric epithelia. Siah1 knockdown significantly decreased invasiveness and migration of H. pylori-infected GCCs. Although, Siah1 could not increase degradation of the cytosolic ß-catenin and its nuclear translocation, it enhanced degradation of the membrane-bound ß-catenin in the infected GCCs. This loss of membrane-bound pool of ß-catenin was not associated with the proteasomal degradation of E-cadherin. Thus, this work delineated the role of Siah1 in increasing invasiveness of H. pylori-infected GCCs.

Salt tolerance in aquatic macrophytes: possible involvement of the antioxidative enzymes.

Possible involvement of the antioxidative enzymes in salt tolerance was investigated in three submerged aquatic macrophytes, viz. Hydrilla verticillata, Najas indica and Najas gramenia, which differed in their tolerance to salinity. NaCl in light resulted in significant decrease in the chlorophyll a/b ratio in H. verticillata, which was significantly neutralized by the presence of DABCO (diazabicyclo[2.2.2]octane), sodium benzoate or mannitol along with the NaCl in the exposure medium indicating induction of oxidative stress upon salt treatment. All the three test species showed enhanced activity of superoxide dismutase (SOD; EC 1.15.1.1) and peroxidases (EC 1.11.1.7) upon exposure to either NaCl or SWS (seawater salinity); the increases in their activity in response to NaCl were positively correlated with the salt tolerance of the plants. Only N. gramenia showed considerable increase in the activity of catalase (EC 1.11.1.6), while only H. verticillata exhibited significant increase in the activity of ascorbate peroxidase (EC 1.11.1.11) in response to the salt treatment. A higher constitutive level of the antioxidative enzymes in the salt-tolerant N. gramenia than in the salt-sensitive H. verticillata coupled with significant increase in the activity of these enzymes, particularly of catalase and SOD, in the former upon salinity treatment suggested their active involvement in salt tolerance. The oxidative stress induced upon the salt treatment also indicated a possible involvement of the antioxidative enzymes in the process. The ion interaction study revealed significant modifying effect of Ca(2+), and also of Mg(2+) and K(+), on the changes induced by Na(+) in the activity of catalase and SOD suggesting that relative build-up of these ions inside cells could be of much importance in regulation of synthesis of antioxidative enzymes.

Effect of aluminum on superoxide dismutase, catalase and lipid peroxidation of rat liver.

Results of the present study suggest that aluminum treatment to rats resulted in elevation of microsomal lipid peroxidation along with inhibition of catalase activity in the liver. Aluminum treatment to rats has no significant effect on rat liver superoxide dismutase activity. A 25% inhibition in catalase activity was observed when liver supernatant was incubated with A1C13 at 5 x 10(-3) M concentration and above.

Rapid cytodiagnosis of endoscopic biopsy specimens in gastrooesophageal malignancy.

Squash cytology has been used extensively in examining central nervous system lesions. Recently this technique has been employed in examining endoscopic biopsy specimens. This study was conducted to assess the diagnostic value of squash cytology of biopsy samples from gastrooesophageal malignancies, and to evaluate the efficacy of Leishman's stain for rapid cytologic evaluation of squash preparations. One hundred and fifty five patients with oesophageal or gastric malignancy were subjected to endoscopic biopsy. The first biopsy specimen from each patient was crushed between two glass slides for cytologic evaluation. The smears were stained with Leishman's and Papanicolaou's stains. The results of squash cytology were then compared with histopathology. A positive diagnosis of malignancy was obtained by histology in 146 cases (94.2%) and by squash cytology in 141 cases (90.9%), by both Leishman's and Papanicolaou's staining. In 12 cases (7%) cytology revealed 'suspicious cells'. Histology plus squash cytology together gave a positive yield in 153 cases (98.7%). In 7 cases (4.5%) although squash cytology was positive for malignancy, hispathologic study failed to reveal malignancy. Squash cytology is a useful adjunct to conventional endoscopic biopsy for gastrooesophageal malignancy. This technique which does not require any additional effort or equipment may add to the diagnostic yield besides expediting the workup. Leishman's staining, which is simple, quick and inexpensive is as efficacious as Papanicolaou's method for squash cytology.

Experimental pheohyphomycosis and mycotoxicosis by Curvularia lunata in albino rats.

A rice contaminating fungus 'Curvularia lunata' yields 'Curvularin', a potent mycotoxin. Experimental Pheohyphomycosis and Mycotoxicosis were observed in albino rats. Spore suspension produced localised lesion; with simultaneous steroid therapy produced lesion in distant organs. Mycotoxin, Curvularin, produced hepatic necrosis.