Nanochitin/manganese oxide-biodegradable hybrid sorbent for heavy metal ions.

The article presents the results of the synthesis and research of a new biodegradable hybrid nanosized polymer-inorganic system possessing the double nature of heavy metal ions extraction from solutions. Firstly, the sorption of metal ions takes place by the ion-exchange properties of porous manganese oxide and, secondly, due to specific interaction and chelating with functional groups of polysaccharides in terms of nanochitin (ChNC). The synthesis is based on the colloid-chemical processes of interaction between polysaccharide and manganese oxide nanosized particles. Using the mathematical model of the Derjaguin, Landau, Verwey, and Overbeek (DLVO) theory, it has been shown that this interaction occurs due to the formation of hydrogen bonds and electrostatic interactions of oppositely charged particles. Hybrid sorbents were characterised by X-ray diffraction, Fourier transform infrared spectroscopy, Transmission electron and Atomic force microscopy. The highest value of sorption capacity for hybrid materials was obtained for Ni2+ extraction and reached 114.0 ± 1.1 mg/g. It was shown that biodegradation of hybrid sorbents increases with the concentration of manganese oxide nanoparticles and almost complete degradation of the organic part can be performed within 6 days. The obtained biodegradable sorbents were designed to address ecological problems connected with the pollution of natural waters by toxic metallic ions.

Effects of progesterone on serum levels of IGF-1 and on femur IGF-1 mRNA in ovariectomized rats.

Local and systemic insulin-like growth factors (IGFs) may be involved in the regulation of bone formation by sex hormones. The present studies describe the in vivo effects of estradiol, progesterone, or both on IGF-1 mRNA abundance in bone, serum IGF-1 levels, and bone formation. Rats were sham-operated (SHAM) or ovariectomized (OVX) at 12 weeks of age and used a week later in three experiments. First, OVX rats were treated with vehicle, estradiol, and/or medroxyprogesterone (MPA) for 3 weeks, and bone formation was assessed in the tibial metaphysis. Second, OVX rats were treated in the same manner and serum IGF-1 levels measured. Third, OVX rats were treated with an injection of vehicle, estradiol, and/or progesterone, and 24 h later, levels of IGF-1 mRNA in the femur were analyzed. The mineralized surface, mineral opposition rate, and bone formation rate (BFR) were higher in OVX than in SHAM rats. The BFR was decreased in estrogen-treated but increased in MPA-treated rats compared with vehicle-treated OVX rats. Circulating levels of IGF-1 were higher in OVX than in SHAM rats but were not affected by sex hormones in a 3-week experiment, whereas these levels were not different among groups in a 24-h experiment. Northern analysis detected 7.5 and 0.8 kb IGF-1 mRNA transcripts. The abundance of IGF-1 mRNA was higher in OVX than in SHAM rats. IGF-1 transcripts 7.5 and 0.8 kb were decreased by 72 and 29%, respectively, in estrogen-treated and increased by 44 and 43%, respectively, in progesterone-treated rats compared with vehicle-treated OVX rats. We conclude that in the short term, estrogen lowers and progesterone raises bone IGF-1 mRNA and these changes are followed by coordinated changes in bone formation rate.

Osteoporosis and coronary atherosclerosis in asymptomatic postmenopausal women.

Estrogen deficiency is a risk factor for osteoporosis and coronary artery disease. Osteoporosis can be evaluated by measuring bone mineral density (BMD). Coronary atherosclerotic burden can be evaluated by measuring coronary calcium using electron beam computed tomography (EBT) of the heart. We compared coronary calcium scores in 45 asymptomatic postmenopausal women with normal and low BMD. BMD of the lumbar spine and proximal femur was measured by dual X-ray absorptiometry (DXA), and coronary calcium was measured quantitatively by EBT. Women were divided into control, osteopenia, and osteoporosis groups based on the T score of the lumbar spine. Women were similar in age, years since menopause, height, weight, and body mass index (BMI). BMD +/- SD (g/cm2) of L1-L4 was 0.96 +/- 0.11, 0.83 +/- 0.03, and 0.73 +/- 0.05, in control, osteopenia, and osteoporosis group, respectively. The total coronary calcium score +/- SD (relative units) was 41.9 +/- 83.1, 115.1 +/- 181.9, and 221.7 +/- 355.4 for control, osteopenia, and osteoporosis group, respectively; the score was significantly higher in the osteoporosis than in the control group. This study provides initial data suggesting that women with osteoporosis may have a higher risk of developing coronary atherosclerosis.