A microbial metabolite remodels the gut-liver axis following bariatric surgery

1. Download : Download high-res image (198KB)
2. Download : Download full-size image

     

17-beta-Hydroxysteroid dehydrogenase in rabbit bone marrow

Because of the general presence of 17-B-hydroxysteroid dehydrogenase (17-B-HSD) in animals and human erythrocytes, it is very likely that this enzyme is also present in the erythrocyte precursor cells in bone marrow. Adult male white New Zealand rabbits were used to demonstrate the existence of the 17-B-HSD in bone marrow cells and to evaluate the biological function of 17-B-HSD in the erythropoietic system in bone marrow. Anemia was artificially induced in these animals in order to stimulate the proliferation of erythropoietic cells. This was accomplished by bleeding or by intra-peritoneal injection of 40 mg/kg of phenylhydrazine. The 17-B-HSD activities were then examined by histochemical and biochemical assays. The results showed a two to three-fold increase of the enzyme activities in both peripheral erythrocytes and bone marrow cells of anemic animals. Our experiments further demonstrate the fine control of erythropoiesis. The enzyme, which favors the conversion of oestradiol to oestrone, is itself boosted by an anemic state. As a result, the inhibitory action of hemopoiesis by oestradiol was relieved.     

Production of beta-fructofuranosidase with transfructosylating activity for fructooligosaccharides synthesis by Aspergillus japonicus NTU-1249.

Microbial beta-fructofuranosidases with transfructosylating activity can catalyze the transfructosylation of sucrose and synthesize fructooligosaccharides. Aspergillus japonicus NTU-1249 isolated from natural habitat was found to produce a significant amount of beta-fructofuranosidase with high transfructosylating activity and to have the potential for industrial production of fructooligosaccharides. In order to improve it's enzyme productivity, the medium composition and the cultivation conditions for A. japonicus NTU-1249 were studied. A. japonicus NTU-1249 can produce 83.5 units of transfructosylating activity per ml broth when cultivated in a shaking flask at 28 degrees C for 72 hours with a modified medium containing 80 g/l sucrose, 15 g/l soybean flour, 5 g/l yeast extract and 5 g/l NaCl at an initial pH of 6.0. The enzyme productivity was also optimized by submerged cultivation in a 5-litre jar fermentor with aeration at 1.5 vvm and agitation at 500 rpm. Under these operating conditions, the productivity of transfructosylating activity increased to 185.6 U/ml. Furthermore, the transfructosylating activity was improved to 256.1 U/ml in 1,000-litre pilot-scale fermentor. Enzymatic synthesis of fructooligosaccharides by beta-fructofuranosidase from A. japonicus NTU-1249 was performed in batch type by adding 5.6 units of transfructosylating activity per gram of sucrose to a 50% (w/v) sucrose solution at pH 5.0 and 50 degrees C. The yield of fructooligosaccharides was about 60% after reaction for 24 hours, and the syrup produced contained 29.8% (w/v) fructooligosaccharides, 15.2% (w/v) glucose and 5.0% (w/v) sucrose.     

Role of pentoxifylline in preventing radiation damage to epiphyseal growth plate chondrocytes.

Radiation therapy plays an important role as part of multimodality treatment for a number of childhood malignancies. The damaging effects of radiation on bone formation in children have been well documented. Recent work suggests that the postirradiation increase in cytosolic calcium is probably responsible for the deleterious effects of radiation on growth plate chondrocytes because it causes a specific suppression of the mitogen PTHrP. Using an in vitro model of avian growth plate chondrocytes, this study demonstrates that pentoxifylline is effective in increasing basal PTHrP mRNA levels and partially preventing the radiation-induced decrease in PTHrP mRNA. This effect of pentoxifylline is probably due to its ability to lower basal levels of cytosolic calcium and the radiation-induced increase in cytosolic calcium in chondrocytes. Pentoxifylline also prevented the radiation-induced decreases in [3H]thymidine uptake and BCL2 and PTHrP receptor mRNA levels in chondrocytes. The effects of pentoxifylline appear to be specific for the PTHrP signaling pathway because it did not alter basal TGFB mRNA levels or TGFB mRNA expression in irradiated chondrocytes. The results of the current study suggest that by decreasing basal cytosolic calcium levels and curtailing the radiation-induced increase in cytosolic calcium levels in chondrocytes, pentoxifylline is able to sustain PTHrP signaling in chondrocytes and maintains the proliferative signal that is necessary to prevent chondrocytes from undergoing apoptosis.     

Production of isomaltooligosaccharides by a-glucosidase immobilized in chitosan beads and by polyethyleneimine-glutaraldehyde treated mycelia of Aspergillus carbonarious

Partially purified a-glucosidase from Aspergillus carbonarious, immobilized on glutaraldehyde-activated chitosan beads in a packed bed reactor, produced isomaltooligosaccharides at a yield of 60% (w/w) using 30% (w/v) maltose solution. Using intact mycelia attached with polyethyleneimine-glutaraldehyde, produced isomaltooligosaccharides at a yield of 46% (w/w) using 30% (w/v) maltose solution. Batchwise reaction stabilities were improved for chitosan beads immobilized enzyme and polyethyleneimine-glutaraldehyde treated mycelia as compared to mycelia without any treatment.     

Zinc coadministration attenuates melatonin’s effect on nitric oxide production in mice

Both melatonin (MEL) and zinc (Zn) are considered beneficial for anti-immunosenescence. MEL’s effects on immune functions are partly attributed to an interaction with Zn. However, the augmentation of or interference with MEL’s effects by coadministration of Zn remains unclear. In this study, adult older mice received either MEL (10 μg/mL), Zn (22 μg/mL), MEL+Zn, or null supplementation from drinking water for 3 mo. The results showed that treated mice, irrespective of the type of added chemicals, had higher body-weight gain and body-fat content than control mice. MEL- and Zn-treated mice also had increased serum free fatty acid levels. In addition, the MEL group had decreased serum NO_X (nitrite+nitrate) values. Serum tumor necrosis factor-alpha levels were increased, although nonsignificantly, in mice that received either MEL or Zn supplementation. However, the differences described were not retained in the mice that received MEL+Zn treatment. We conclude that a high-dose Zn coadministration might exert negative influences on MEL’s regulatory effects, at least on nitric oxide production.