Relative bioavailability of selenium in rice using a rat model and its application to human health risk assessment.

Deficiencies of selenium (Se), a necessary microelement for humans, can be remedied by appropriately supplying Se-enriched rice. However, overconsumption of Se-enriched rice poses a potential risk. To accurately assess Se human health risks associated with Se-enriched rice consumption, we developed a rat in vivo model to systematically explore the relative bioavailability of Se (Se-RBA) from Se-enriched rice from a wide geographic range. Se concentrations were in the range of 0.06 ± 0.05 to 0.15 ± 0.15 mg kg-1, averaging 0.12 ± 0.11 mg kg-1, in 196 rice samples from 21 Chinese provinces, and selenomethionine (SeMet) was the dominant Se fraction (58.0-96.5%). The Se-RBA of Se-enriched rice calculated from urine ranged from 34.86% to 102.29%, averaging 62.27% (n = 12), and was positively correlated with the proportion of SeMet in rice (p < 0.05, R2 = 0.51). Furthermore, the Se intake calculated based on the Se-RBA indicated that the Se intake of consumers of Se-enriched rice was far less than the tolerable upper intake level. Thus, the limits established by law assume overestimates of the actual nutritional value of the Se content in Se-enriched rice, and it is important to consider Se bioavailability. The current study offers suggestions for future research and provides methods to reduce the uncertainty in estimating the health risks associated with Se intake from rice.

[Effect of electroacupuncture of "Mingmen" (GV 4) on bone morphogenetic protein-2 expression in osteoporosis rats].

OBJECTIVE: To observe the effect of electroacupuncture (EA) stimulation of "Mingmen" (GV 4) on the bone morphogenetic protein-2 (BMP-2) content and biomechanics in osteoporosis rats so as to explore its mechanism underlying improvement of osteoporosis. METHODS: Fifty female SD rats were randomized into sham operation (sham), model, EA-GV 4, EA-non-acupoint (non-acupoint) and estrogen (medication) groups, with 10 rats in each group. Postmenopausal osteoporosis model was established by removing the rats' bilateral ovaries under anesthesia. EA (2 Hz/15 Hz, 1.0 mA) was applied to "Mingmen" (GV 4) or non-acupoint for 20 min, once daily for 30 times, with one day's interval between every two 10 times. Rats of the medication group were lavaged with Pentanoic Acid Estradiol (25 microg/mL, 2 mL/500 g), once every day (the dosage of estradiol was adjusted according to their body weight) continuously for 1 month. Rats of the model and sham groups experienced the fixing and fastening procedures as the other rats in the EA and medication groups. After intervention, the BMP-2 expression level of the femoral bone tissue, and bone biomechanical values were determined by immunohistochemistry and three-point bending tests, respectively. RESULTS: (1) In comparison with the sham operation group, the femoral biochemical maximum load and fracture load values were significantly decreased in the model group (P < 0.05). While compared with the model group, the biochemical maximum load and fracture load values were obviously increased in the EA-GV 4 and medication groups (P < 0.05), but not in the non-acupoint group (P > 0.05). (2) Compared with the sham group, the femoral BMP-2 expression of model group was significantly decreased (P < 0.05), compared with the model group, the expression of BMP-2 of GV 4 and medication groups significantly increased (P < 0.05). CONCLUSION: EA-GV 4 intervention can improve bone biomechanical changes in osteoporosis rats.

[Our considerations about non-acupoint selection for experimental studies in rats].

Researches on the specificity of acupoints need a contrast of non-acupoint. However, there have been no uniform standards for locating the non-acupoint in both human body and animals. In the present paper, the authors make a review about the methods for locating the non-acupoint in rats during acupuncture experiments in recent decade. Till now, four methods were frequently used, i.e., 1) selecting a spot beside the known acupoint at the same level, 2) selecting the mid point between two meridian running courses, 3) choosing a spot at the tail, and 4) choosing a spot below the costal region. The authors hold that of the 4 methods, the last one, i.e., taking the spot below the costal region as the non-acupoint is probably the most reasonable approach, if it is far from the observed acupoint, and on the same or the adjacent spinal nerve segment.

[Discussion on method for locating acupoint "Mingmen" (GV 4) in adult rats].

"Mingmen" (GV 4) is one of the most frequently used acupoints in acupuncture clinic. In recent years, more and more experimental researches have been focusing on GV 4 or acupoint recipe containing GV 4 in rats. Accurate location of GV 4 is probably not only related to fully display its therapeutic effect, but also to help study its underlying mechanisms. However, there has been no unified standard about the accurate location of GV 4 in the adult rat at present. In the present paper, the authors review related literature about GV 4 location in experimental studies in recent 10 years, and put forward a practical method for locating GV 4 in the rat by combining their own experience. That is, GV 4 is taken according to the relative relationship of ilium and spinous process of the lumbar vertebra. In addition, the authors also recommend some matters needing attention in locating GV 4 in rats.