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Chondroitin sulfate (CS) has antioxidative, anti-inflammatory, anti-osteoarthritic and hypoglycemic effects. However, whether it has antidiabetic osteoporosis effects has not been reported. Therefore, in this study, we established a STZ-induced diabetic rat model, CS (500 mg kg&minus, 1 d&minus, 1) was orally administrated for eight weeks to study its preventive effects on diabetic osteoporosis. The results showed that eight weeks of CS treatment improved the symptoms of diabetes, the CS-treated group has increased body weight, decreased water or food intake, decreased blood glucose, increased bone-mineral density, repaired bone morphology and decreased femoral osteoclasts and tibia adipocytes numbers. After CS treatment, bone histomorphometric parameters returned to normal, the levels of serum inflammatory cytokines (IL-1&beta, IL-6 and TNF-&alpha, ) decreased significantly, serum SOD, GPX and CAT activities increased and MDA level increased. In the CS-treated group, the levels of serum ALP, CTX-1, TRACP 5b, osteocalcin and RANKL decreased and the serum RUNX 2 and OPG levels increased. Bone immunohistochemistry results showed that CS can effectively increase the expression of OPG and RUNX2 and reduce the expression of RANKL in diabetic rats. All of these indicate that CS could prevent STZ induced diabetic osteoporosis&mdash, mainly through decreasing blood glucose, antioxidative stress, anti-inflammation and regulation of OPG/RANKL expression. CS can therefore effectively prevent bone loss caused by diabetes.

To optimize the beta-carotene fermentation medium of the mutant RG-6p (derived from Rhodotorula glutinis RG-6 with high hydrostatic pressure treatment), a response surface methodology (RSM) approach was used in conjunction with a factorial design and a central composite design. The maximum yield of beta-carotene (13.4 mg/L) was obtained at a pH of 6.7 with an optimum medium (40 mL/250 mL) of yeast extract (4.23 g/L), glucose (12.11 g/L), inoculum (30 mL/L), tomato extract (2.5 mL/L), peanut oil (0.5 mL/L), and (NH 4 ) 2 SO 4 (5 g/L). Validity of the RSM approach was also confirmed by experiments.

The effects of ultra high-pressure (UHP) on the growth and its ability of beta-carotene biosynthesis of Rhodotorula glutinis RG-8 were studied. After the treatments of 5 repeated cycles at 300 MPa for 15 min, the barotolerant mutant RG-8-9 was obtained from this strain. The survival ratio of the parent strain RG-8 was increased from 1.40times10 -3 % after the treatment of first cycle to 1.47times10 -1 % after the treatment of fifth cycle. The biomass of mutant RG-8-9 was 22.8 g/L after 72 h of culture, decreased by 2.6% compared with 23.4 g/L from the parent strain RG-8, but its beta-carotene production could reach 20.6 mg/L, increased by 63.5% compared with 12.6 mg/L from the parent strain RG-8. The genetic quality of mutant strain RG-8-9 was proved to be stable by experiments. The result of restriction fragment length polymorphism analysis suggested that mutant strain RG-8-9 was likely to change in nucleic acid level, and thus enhanced beta-carotene production should be a result of gene mutation induced by UHP.

The effects of high hydrostatic pressure (HHP) on the biomass and β-carotene biosynthesis of Rhodotorula glutinis R68 were studied. After treatment with five repeated cycles at 300 MPa for 15 min, the barotolerant mutant PR68 was obtained. After 72 h of culture, the biomass of mutant PR68 was 21.6 g/l, decreased by 8.5% compared to the parental strain R68, but its β-carotene production reached 19.4 mg/l, increased by 52.8% compared to the parental strain R68. The result of restriction fragment length polymorphism (RFLP) analysis suggested that mutant strain PR68 was likely to change in nucleic acid level, and thus enhanced β-carotene production in this strain as a result of gene mutation induced by HHP treatment. Copyright © 2008 John Wiley & Sons, Ltd.