Cover Image

Abstract

The cover image, by Wen‐qing Zhu et al., is based on the Research Article Effect of titanium ions on the Hippo/YAP signaling pathway in regulating biological behaviors of MC3T3‐E1 osteoblasts, DOI: .

Biocorrosion of pure and SLA titanium surfaces in the presence of Porphyromonas gingivalis and its effects on osteoblast behavior

“…In our previous study, it was found that excessive titanium ions were capable of suppressing osteoblasts growth and inhibiting the osteogenic differentiation via the Hippo/YAP signaling pathway. 36 Changes in the characteristics of titanium surfaces can directly inuence cell adhesion behavior. 37,38 In this study, the decreased adherent MC3T3-E1 cells and poor cell spreading on the Ti-pg and SLA-pg surfaces were observed.…”

Safety Aspects of the Use of Quercetin as a Dietary Supplement

“…In male hamsters, quercetin doses of 0.3 or 3 % in the diet (corresponding to around 150 and 1500 mg per kg bw and day, respectively) for around 6 months caused an increase in the number of larger tumors in the kidney (> 5 mm) and an increase in abdominal metastases compared to the estradiol group. [121] The other study with female rats reported especially enhanced cell proliferation and shortening of the tumor latency of mammary glands by quercetin at a dose of 0.25 % in the diet (corresponding to around 150 mg per kg bw) in animals co-treated with estradiol for 8 months compared to the estradiol control group. [122] Both working groups suggested a direct inhibition of the catechol-Omethyltransferase activity by quercetin as a possible mechanism resulting in an elevated formation of the carcinogenic estradiol metabolite 4-hydroxyestradiol and an accompanied reduction of the anti-carcinogenic metabolite 2-methoxyestradiol.…”

“…Most studies revealed no or even chemo-preventive effects of quercetin (details see [30] ). However, a few studies using different carcinogens (N-ethyl-N'-nitro-N-nitrosoguanidin, azoxymethane, nitrosomethylurea or 17β-estradiol) reported also an enhanced tumor development in duodenum, [117] colon, [118] pancreas, [119,120] kidney [121] or mammary glands [122] of rodents after quercetin treatment with 0.2 to 3.4 % in feed (corresponding to approximately 150 to 3400 mg per kg bw and day). Two of these studies started the quercetin treatment in pregnant rats continuing in their offspring and investigated the tumorigenesis in the offspring.…”

“…Two of these studies started the quercetin treatment in pregnant rats continuing in their offspring and investigated the tumorigenesis in the offspring. [119,120] Furthermore, two other studies investigated the effects of quercetin on the tumor-development mediated by exogenously applied estradiol, [121,122] the results of which are described in more detail in a separate chapter (section 4.3.2.3).…”

“…[122] Both working groups suggested a direct inhibition of the catechol-Omethyltransferase activity by quercetin as a possible mechanism resulting in an elevated formation of the carcinogenic estradiol metabolite 4-hydroxyestradiol and an accompanied reduction of the anti-carcinogenic metabolite 2-methoxyestradiol. [121,122] The described animal studies used certain artificial conditions by inducing tumor development with application of high exogenous estradiol doses which does not necessarily reflect the human condition. However, there is an open question whether quercetin may also promote estrogen dependent tumor diseases in humans which should be persued in further human intervention studies e.g.…”