Hormesis response of marine and freshwater luminescent bacteria to metal exposure

The stimulatory effect of low concentrations of toxic chemicals on organismal metabolism, referred to as hormesis, has been found to be common in the widely used luminescence bioassay. This paper aims to study the hormesis phenomenon in both marine and freshwater luminescent bacteria, named Photobacterium phosphorem and Vibrio qinghaiensis. The effects of Cu (II), Zn (II), Cd (II) and Cr (VI) on luminescence of these two bacteria were studied for 0 to 75 minutes exposure by establishing dose- and time-response curves. A clear hormesis phenomenon was observed in all four testing metals at low concentrations under the condition of luminescence assays.

Effect of Diabetes Mellitus on the structure of skeletal muscle in adult male albino rats and the protective role of chromium: histological and immunohistochemical study

Diabetes may induce many physiological and biochemical changes in skeletal muscle fibers. These were supposed to be caused by hypoinsulineamia and hyperglyceamia. Chromium is trace element its effect on the body is related to carbohydrate and fat metabolism. Chromium improved the metabolism of skeletal muscle especially in athletes. We evaluate the histological and immunohistochemical changes induced by diabetes in the skeletal muscle and the protective role of chromium. Twenty five adult Sprague-Dawlery male albino rats were used. The rats were divided into two main groups; the control group [10 rats] and the diabetic group [15 rats]. The control group was divided in 2 subgroups 5 animals each. Subgroup Ia served as a control group while subgroup Ib was formed of animals that received oral chromium. Group II in which diabetes was induced using streptozotocin [STZ] was divided into 3 subgroups 5 animals each. Subgroup IIa formed of diabetic rats. Subgroup lib formed of diabetic rats that received insulin. Group IIe formed of diabetic rats that received insulin and chromium. The duration of experiment was 2 months. At the end of experiment, gastrocnemius muscles were dissected out and prepared for H and E stain, electron microscopic study and immunohistochemistry for CD[34] of endothelial cells of capillaries. Skeletal muscle of group IIa showed disruption and discontinuity. Mononuclear cellular infiltrate was detected among skeletal muscle fibers. Ultrathin sections showed damaged myofibrils, swollen irregular mitochondria and absent T tubules within the muscle fibers. Microvasculature of skeletal muscle was decreased as demonstrated by immunostaining for CD[34]. Group IIb showed improvement of skeletal muscle fibers and their microvasculature but not complete as that of the control. In group IIc, there was complete improvement of the skeletal muscle fibers and microvasculature among the muscle fibers. Significant decrease in thickness of muscle fibers in diabetic rats and insulin treated subgroup IIb could be measured. Intake of chromium was found to improve these changes in subgroup IIc. Significant increase in blood glucose was detected in subgroup IIa and was controlled in subgroups IIb and IIc. Diabetes produced marked structural changes in skeletal muscle but these changes could be prevented by intake of chromium in addition to the insulin

Contact of Entamoeba histolytica with baby hamster kidney-21 (BHK-21) cell line on cysteine proteinase activity.

BACKGROUND & OBJECTIVES: Entamoeba histolytica, the causative agent of amoebiasis and amoebic liver abscess, lyses host cells by direct contact using surface lectins and releases cysteine proteinase (CP). Virulence of E. histolytica is directly related to activity of its CP. The relationship of CP activity and cytotoxicity has not been established. The present study was carried out to explore the events following contact of E. histolytica with target cells. METHODS: Protease activity of E. histolytica was measured by azocaseine and haemoglobin assays, and cysteine proteinase activity was assessed by substrate gel electrophoresis. Target cell lysis was measured by chromium release assay. RESULTS: Protease activity of E. histolytica was increased 2.5-fold following contact with BHK-21 cell line. CP activity of trophozoites alone was visualized at position 56, 35 and 29 kDa in substrate gel electrophoresis. Contact of trophozoites with target cells augmented the cytotoxic activity of amoebic CP. The increase in CP activity seen by substrate gel electrophoresis and cytotoxicity assay was blocked by pretreatment with E 64, a specific CP inhibitor and GalNAc, a contact inhibitor. INTERPRETATION & CONCLUSION: The present data showed the involvement of amoebic CP in cytotoxicity and that the CP activity was enhanced on lectin-mediated contact of E. histolytica to the target cells. Further studies need to be done to understand the mechanism at the molecular level.

Effects chromium supplementation on glucose tolerance and lipid profile

To investigate chromium status of the adult population in the western region of Saudi Arabia and the possibility of using serum chromium status measurement as indicator of this status. The effect of chromium supplement on glucose tolerance and lipid profile was studied in 44 normal, free living adults. 200mg chromium/day as CrCL3 or a placebo was given in a double blind cross-over study, with 8 weeks experimental periods. Fasting, 1 hour and 2 hour post glucose challenge [75g of glucose] glucose, serum fructosamine, total cholesterol, high-density lipoprotein-cholesterol, triglycerides, chromium and dietary intakes were estimated at the beginning and the end of each stage. Mean serum chromium increased significantly after supplement [P<.001] indicating proper absorption of the element. Supplement did not effect the total cholesterol, however, the mean high-density lipoprotein-cholesterol level was significantly increased [P<.001], the mean triglycerides levels significantly decreased [P<.001], and the mean fructosamine level significantly decreased [P<.05]. In addition, chromium supplement effected 1 hour and 2 hour post glucose challenge glucose levels in subgroups of subjects with 2 hour glucose level > 10% above or below fasting level and significantly differing to it [P<.05 in both cases], by decreasing or increasing them significantly [P<.05 in all cases] so that the 2 hour mean became not significantly different to the fasting mean. Since no significant changes in weight, dietary intake or habits were found, and placebo had no effect, all noted biochemical changes were attributed to chromium. Improved glucose control, and lipid profile following chromium supplement suggests the presence of low chromium status in the studied population. However, serum chromium could not be recommended for use as an indicator of chromium status as subjects with widely varying levels responded favorably to the chromium supplement

Effect of chromium on growth of Pseudomonas aeruginosa.

Tolerance level to trivalent chromium-Cr(salen)(H2O)2+ and hexavalent chromium-K2Cr2O7 was assessed in P. aeruginosa isolated from tannery effluent soil. It could tolerate 80 and 100 ppm in liquid cultures and up to 100 and 200 ppm in plate count agar in the presence of trivalent and hexavalent chromium respectively. Unadapted cells took a longer time to grow than adapted cells in the presence of K2Cr2O7. Chromium influenced the cellular contents, morphology and respiration of P. aeruginosa. The chosen trivalent salt of chromium was more toxic than the hexavalent one.

Effect of chromium administration on glutathione cycle of rat intestinal epithelial cells.

Acute oral administration of K2Cr2O7 (1500 mg/kg body wt/day) for 3 days to rats led to the decrease in activities of glucose-6-phosphate dehydrogenase, glutathione peroxidase, glutathione reductase, glutathione-S-transferase, superoxide dismutase and catalase of intestinal epithelial cells. Glutathione and total thiol contents were decreased while lipid peroxidation was increased markedly using the whole homogenate of the intestinal epithelial cells. Chronic oral administration of K2Cr2O7 (300 mg/kg body wt/day) for 30 days to rats on the other hand, led to marked increase in superoxide dismutase and glutathione peroxidase activities with no appreciable change in glucose-6-phosphate dehydrogenase, glutathione reductase and catalase activities. However, glutathione-S-transferase activity was decreased significantly. In the whole homogenate of rat intestine, glutathione and total thiol contents were decreased not so significantly but there was a slight enhancement in lipid peroxidation value.