Repetitive short-span application of extracellular calcium is osteopromotive to osteoprogenitor cells.

Extracellular calcium ([Ca2+ ]E ) concentration has been suggested to stimulate osteoblastic activity; thus, calcium can be used to enhance fracture healing. However, systemic administration of calcium at high dose levels may cause physiological problems such as hypercalcaemia. Short-span application of single or repetitive [Ca2+ ]E stimulus may be suggested as a novel regimen to reduce such side effects. However, osteopromotive effect of such short-term [Ca2+ ]E stimulus on osteoprogenitor cells has not yet been evaluated yet. This study investigated the effects of [Ca2+ ]E dose (6 and 18 mM) and regimen (single, repetitive, and continuous) on viability, proliferation, osteogenic gene expression, and mineral formation by osteoprogenitor cells. BMP-2 treatment was set as the positive control group. It was observed that repetitive and continuous calcium stimulation resulted in significant enhancement of osteoblastic activity. A 6 mM [Ca2+ ]E significantly increased cell viability and proliferation in all three regimens, and the expression of osteogenic transcription factors was significantly upregulated by continuous application of 6 mM [Ca2+ ]E . It was observed that application of [Ca2+ ]E repetitively at 18 mM had an osteopromotive effect to an extent that was as pronounced as BMP-2. Continuous application of 18 mM [Ca2+ ]E provided the greatest degree of osteogenic activity among all groups. This study demonstrated that repetitive [Ca2+ ]E exposure from the basal aspect of cells resulted in upregulation of osteogenic transcription factor and bone formation. The knowledge gained from the dose and treatment regimen of calcium therapy is important in setting the guidelines for developing approaches to treat fractures.

Anthocyanin-rich black currant (Ribes nigrum L.) extract affords chemoprevention against diethylnitrosamine-induced hepatocellular carcinogenesis in rats.

Anthocyanins are known to possess potent anticarcinogenic properties against several cancers thus demonstrating potential for cancer prevention. Black currant (Ribes nigrum L., Grossulariaceae) fruits have a high anthocyanin content. This "superfruit" is known to possess various pharmacological effects including alleviation of chronic oxidative stress and inflammation. In contrast to a large volume of literature on the health benefits of black currant, limited evidence on antitumor effects of black currant exists with virtually no data on the prevention of experimental carcinogenesis. In the current study, we have investigated the chemopreventive effects of an anthocyanin-rich black currant skin extract (BCSE) utilizing our well-characterized model of rat liver carcinogenesis. Initiation of hepatocarcinogenesis was done by intraperitoneal injection of diethylnitrosamine (DENA) followed by promotion with phenobarbital. The rats were exposed to dietary BCSE for 4 weeks prior to initiation, and the treatment was continued for 22 consecutive weeks. BCSE dose-dependently decreased the incidence, total number, multiplicity, size and volume of preneoplastic hepatic nodules. The antihepatocarcinogenic effect of BCSE was confirmed by histopathological examination of liver sections. Immunohistochemical analysis of proliferating cell nuclear antigen and DNA fragmentation revealed BCSE-mediated inhibition of abnormal cell proliferation and induction of apoptosis in DENA-induced rat liver tumorigenesis respectively. Mechanistic studies revealed that BCSE-mediated proapototic signal during experimental hepatocarcinogenesis may be propagated via the up-regulation of Bax and down-regulation of Bcl-2 expression at the translational level. These results along with a safety profile of BCSE encourage the development of black currant bioactive constituents as chemopreventive agents for human liver cancer.

Anthocyanin-rich black currant extract suppresses the growth of human hepatocellular carcinoma cells.

Dietary antioxidants, such as anthocyanins, are helpful in the prevention and control of various diseases by counteracting the imbalance of oxidative and antioxidative factors in the living systems. Black currant (Ribes nigrum L., Grossulariaceae) is known to contain high amounts of anthocyanins (250 mg/100 g fresh fruit). Black currant fruits have been used in Asian and European traditional medicine for the treatment of a variety of diseases. Black currant extract has recently been found to be the second most effective amongst nine different berry extracts studied for their free radical scavenging activity. Constituents present in black currant juice have been found to exert a number of health-promoting effects, including immunomodulatory, antimicrobial and antiinflammatory actions, inhibition of low-density lipoprotein, and reduction of cardiovascular diseases. Although antioxidant and antiinflammatory effects of black currant juice could be of value in preventing and treating oxidative stress- and inflammation-driven cancers, no experimental evidence is available to now. The objective of the present study was to evaluate the potential antiproliferative effects of black currant fruit skin extract against HepG2 human liver cancer cells. The aqueous extract yielded an anthocyanin-rich fraction with cyanidin-3-O-rutinoside as one of the major anthocyanins. This fraction exhibited a potent cytotoxic effect on HepG2 cells and this effect was more pronounced than that of delphinidin and cyanidin, two major aglycones of anthocyanins present in black currant. Our results indicate, for the first time, that black currant skin containing an anthocyanin-rich fraction inhibits the proliferation of liver cancer cells, possibly due to additive as well as synergistic effects. This product could be useful in the prevention and treatment of human hepatocellular carcinoma.