NOPR Collection:

Role of mouse spleen cell HMG proteins and their poly-ADP-ribosylation in betelnut induced carcinogenesis

2002-04-01T00:00:00Z

Title: Role of mouse spleen cell HMG proteins and their poly-ADP-ribosylation in betelnut induced carcinogenesis Authors: Pariat, Theisara; Sharan, R N Abstract: The role of high mobility group (HMG) proteins and their poly-ADP-ribosylation (PAR) in betel nut induced initiation of carcinogenesis in mice has been studied. A known carcinogen, diethylnitrosamine (DEN) was used as a positive control. Swiss albino mice were chronically exposed to aqueous extract of betel nut (AEBN) or DEN at low doses for up to 4 weeks. The poly-ADP-ribosylation (PAR) of spleen cell HMG proteins was monitored using [32P]-NAD+. Parallel to this, chromatin was subjected to DNase I cleavage and the organizational state of the chromatin was monitored. The PAR of HMG proteins showed a marked progressive reduction at different times following AEBN- or DEN treatment. HMG proteins isolated from the control and carcinogen treated mice were allowed to reassociate with the untreated spleen cells chromatin. The reassociated chromatin showed progressive relaxation in its superstructure. The results suggest that under the influence of potential carcinogens AEBN or DEN, the mouse spleen cell HMG proteins created molecular conditions favourable to initiation of cancer. Page(s): 130-132

Oxidative burden and antioxidant defense system in polymorphonuclear leukocytes of human lung diseases

2002-04-01T00:00:00Z

Title: Oxidative burden and antioxidant defense system in polymorphonuclear leukocytes of human lung diseases Authors: Sharma, Rashmi N; Bhardwaj, A; Behera, D; Khanduja, K L Abstract: Superoxide anion (O2.^-) and hydrogen peroxide (H₂O₂) production was significantly higher in blood neutrophils (PMNs) of patients with lung cancer and non-malignant lung diseases when compared to the controls (p<0.001). Superoxide dismutase (SOD) activity was significantly decreased in PMNs of patients with lung cancer (p<0.00l). Similarly, catalase and glutathione peroxidase (GPx) activities were lower in PMNs of lung cancer patients as compared to non-malignant lung diseases and controls. There was an increase in HMP shunt activity as measured by rate of formation of ¹⁴CO₂ from [1-¹⁴C]-glucose in PMNs of lung cancer patients. Modifications in the antioxidant defense system in PMNs of malignant and non-malignant lung diseases, the changes being more in the malignancy are indicated. Page(s): 124-129

Effect of harmaline on rat intestinal brush border sucrase activity

2002-04-01T00:00:00Z

Title: Effect of harmaline on rat intestinal brush border sucrase activity Authors: Kaur, Navneet; Kaur, Jyotdeep; Mahmood, Akhtar Abstract: The effect of harmaline, a plant alkaloid has been studied on rat intestinal brush border sucrase activity. Stimulation of sucrase activity by Na+ was found to be pH-dependent. At neutral pH, 20 mM Na⁺ stimulated sucrase activity by reducing K_m by 30% while at acidic pH (5.2), the activity increased 4-fold compared to Na⁺-free enzyme. At 1.0 mM, harmaline markedly inhibited (67%) the enzyme activity at pH 5.2 in the absence of Na⁺. However, inhibition was reduced in presence of 20 mM sodium, whereas 4.0 mM harmaline was required to inhibit the enzyme activity by 65%. In the absence of Na⁺ ions, harmaline inhibition of sucrase activity was of competitive type, but it changed to non-competitive type in presence of 20 mM Na⁺ at pH 5.2. Sucrase-harmaline interactions as a function of pH, both in presence and absence of Na⁺ revealed a shift in pH optima of the enzyme towards a higher pH in presence of 4 mM and 1 mM harmaline respectively. The observed inhibition was reversible in nature and was only partially overcome by sodium, lithium, potassium, cesium, rubidium and ammonium ions. These findings suggest that harmaline also inhibits rat brush border sucrase and that the presence of Na⁺ site is not a pre-requisite for the inhibition. Page(s): 119-123

Characterization of a 59 kDa gelatin-binding fragment of buffalo plasma fibronectin

2002-04-01T00:00:00Z

Title: Characterization of a 59 kDa gelatin-binding fragment of buffalo plasma fibronectin Authors: Ahmed, Nizamuddin; Swamy, Naganath Abstract: Limited proteolysis of buffalo plasma fibronectin (FN) by thermolysin yielded four gelatin-binding fragments of which, the major 59 kDa fragment, GBFl, was isolated by gelatin-Sepharose and heparin-Sepharose affinity columns. GBFl appeared during early phase of thermolysin digestion and remained intact even after 4 hr of digestion. GBF1 may be similar to 56 kDa gelatin-binding fragment of FNs from human and hamster plasma. But, it is more resistant to thermolysin cleavage. The fragment binds to heparin with low affinity. On the basis of the structure of human plasma FN, the modular structure of GBFl may be given as: ⁶Fn1 ¹Fn2 ²Fn2 ⁷Fn1 ⁸Fn1 ⁹Fnl ¹Fn3. Biophysical properties of GBF1 suggest an expanded native conformation. The interaction of the fragment with gelatin is pH-dependent and independent of NaCl concentration. Page(s): 113-118