Quercetin is a typical flavonoid present mostly as glycosides in plant foods; it has attracted much attention for its potential beneficial effects in disease prevention. In this study, we examined human volunteers after the short-term ingestion of onion, a vegetable rich in quercetin glucosides. The subjects were served diets containing onion slices (quercetin equivalent: 67.6-93.6 mg/day) with meals for 1 wk. Quercetin was only found in glucuronidase-sulfatase-treated plasma, and its concentration after 10 h of fasting increased from 0.04 +/- 0.04 microM before the trial to 0.63 +/- 0.72 microM after the 1-wk trial. The quercetin content in low-density lipoprotein (LDL) after glucuronidase-sulfatase treatment corresponded to <1% of the alpha-tocopherol content. Human LDL isolated from the plasma after the trial showed little improvement of its resistance to copper ion-induced oxidation. It is therefore concluded that conjugated metabolites of quercetin accumulate exclusively in human blood plasma in the concentration range of 10(-7) approximately 10(-6) M after the short-term ingestion of vegetables rich in quercetin glucosides, although these metabolites are hardly incorporated into plasma LDL.

We investigated the cell kinetics of the endometrium in hysterectomy specimens taken for leiomyoma from 22 women with regular ovulatory menstrual cycles. Formalin-fixed, paraffin-embedded tissue sections were examined for proliferating activity using histone H3 messenger RNA in situ hybridization (H3 mRNA-ISH) and immunostaining for the Ki-67 antigen. The relationship of the proliferative activity of endometrial cells to the immunohistochemical expression of the estrogen receptor (ER) and the progesterone receptor (PR) was also examined. During the menstrual cycle, H3 mRNA expression was observed in both the epithelial cells and the stromal cells of the endometrium. In the functional layer, the labeling indices for H3 mRNA (H3 mRNA-LIs) in the epithelial cells peaked in the late proliferative phase, decreased sharply in the early secretory phase, and remained unchanged thereafter. On the other hand, H3 mRNA-LIs of stromal cells displayed two peaks: one in the midproliferative phase and the other in the late secretory phase, the former peak being the greater. In the basal layer, epithelial cells and stromal cells showed low H3 mRNA-LIs and no significant variation throughout the menstrual cycle. The H3 mRNA-LIs correlated well with the Ki-67-LIs and were lower than the corresponding Ki-67-LIs. The regression coefficient (H3 mRNA-LIs against the Ki-67-LIs) was 0.33 for epithelial cells and 0.49 for stromal cells, suggesting that the cell cycle time was longer for epithelial cells than for stromal cells. The proliferative activity of endometrial cells showed close relationships with the expressions of ER and PR in the endometrium. When used in combination with other proliferative markers in paraffin-embedded tissue sections, H3 mRNA-ISH could open broader perspectives on the cell kinetics of the endometrium. Anat Rec 266: 234 -240, 2002.