Jacinthe Mathey

Classic scrapie in sheep with the ARR/ARR prion genotype in Germany and France

We report 2 natural scrapie cases in sheep carrying the ARR/ARR prion genotype, which is believed to confer resistance against classic scrapie and bovine spongiform encephalopathy.

Olive oil and its main phenolic micronutrient (oleuropein) prevent inflammation-induced bone loss in the ovariectomised rat

The present study was designed to evaluate the effect of olive oil and its main polyphenol (oleuropein) in ovariectomised rats with or without inflammation. Rats (6 months old) were ovariectomised or sham-operated as control. Ovariectomised rats were separated into three groups receiving different diets for 3 months: a control diet with 25 g peanut oil and 25 g rapeseed oil/kg (OVX), the control diet with 50 g olive oil/kg or the control diet with 0.15 g oleuropein/kg. The sham-operated group was given the same control diet as OVX. Inflammation was induced 3 weeks before the end of the experiment by subcutaneous injections of talc (magnesium silicate) in one-half of each group. The success of ovariectomy was verified at necropsy by the atrophy of uterine horns. Inflammation, oleuropein or olive oil intakes did not have any uterotrophic activity, as they had had no effect on uterus weight. The plasma concentration of alpha-1-acid glycoprotein (an indicator of inflammation) was increased in OVX rats with inflammation. With regard to bone variables, osteopenia in OVX was exacerbated by inflammation, as shown by a decrease in metaphyseal and total femoral mineral density. Both oleuropein and olive oil prevented this bone loss in OVX rats with inflammation. At necropsy, oleuropein and olive oil consumption had had no effect on plasma osteocalcin concentrations (marker of bone formation) or on urinary deoxypyridinoline excretion (marker of bone resorption). In conclusion, oleuropein and olive-oil feeding can prevent inflammation-induced osteopenia in OVX rats.

Bone Mass in Obese Diabetic Zucker Rats: Influence of Treadmill Running

Some controversy exists in the literature concerning bone mineral densitry (BMD) in obese, diabetic, leptin-resistant Zucker rats. To investigate this question further, we measured body composition and femoral bone mineral density (BMD) (by dual energy X-ray absorptiometry) in 10 male and 10 female 6 month-old Zucker rats and their homozygous lean controls. Fat mass (percent from body weight) was about 3 times higher in fatty rats than in lean controls. Total, diaphyseal, and distal metaphyseal BMD, total femoral Ca content, and femoral failure load were lower in Zucker rats than in controls. Moderate treadmill running (35% - 40% VO2 max, 20-50 minutes day, 6 days/ week, for 89 days) increased BMD in these animals, possibly by inhibiting bone resorption, as evidenced by no change in plasma osteocalcin concentration but decreased urinary deoxypyridinoline excretion in fatty runners.

Prevention of Bone Loss by Phloridzin, an Apple Polyphenol, in Ovariectomized Rats under Inflammation Conditions

Aging and sex hormones related changes lead to inflammatory and oxidant conditions, which are involved in the pathogenesis of osteoporosis. Recent studies have suggested that polyphenols may exert a protective effect in such conditions. We assessed the effect of phloridzin (Phlo), a flavonoid exclusively found in apple, on bone metabolism in ovariectomized (OVX) or sham-operated (SH) rats with and without inflammation. Six-month-old Wistar rats were allocated to two equal groups that received either a control diet or a diet supplemented with 0.25% Phlo for 80 days. Three weeks before necropsy, inflammation was induced by subcutaneous injection of talc in 10 animals of each group. At necropsy, ovariectomy decreased both total (T-BMD) and metaphyseal (M-BMD) femoral bone mineral density (P < 0.01). Inflammation conditions, checked by an increase in the spleen weight and α1-acid glycoprotein concentration in OVX rats, exacerbated the decrease in T-BMD (g/cm2) (as well as M-BMD) observed in castrated animals (P < 0.05). Daily Phlo intake prevented ovariectomy-induced bone loss in conditions of inflammation as shown by T-BMD and M-BMD (P < 0.05). At the diaphyseal site, BMD was improved by Phlo in OVX rats with or without inflammation (P < 0.05). These results could be explained by changes in bone remodeling as the increased urinary deoxypyridinoline excretion in OVX and OVXinf animals was prevented by the polyphenol-rich diet (P < 0.001), while plasma osteocalcin concentration was similar in all experimental groups. In conclusion, Phlo consumption may provide protection against ovariectomy-induced osteopenia under inflammation conditions by improving inflammation markers and bone resorption.

A simple, versatile and sensitive cell-based assay for prions from various species.

Detection and quantification of prion infectivity is a crucial step for various fundamental and applied aspects of prion research. Identification of cell lines highly sensitive to prion infection led to the development of cell-based titration procedures aiming at replacing animal bioassays, usually performed in mice or hamsters. However, most of these cell lines are only permissive to mouse-adapted prions strains and do not allow titration of prions from other species. In this study, we show that epithelial RK13, a cell line permissive to mouse and bank vole prion strains and to natural prion agents from sheep and cervids, enables a robust and sensitive detection of mouse and ovine-derived prions. Importantly, the cell culture work is strongly reduced as the RK13 cell assay procedure designed here does not require subcultivation of the inoculated cultures. We also show that prions effectively bind to culture plastic vessel and are quantitatively detected by the cell assay. The possibility to easily quantify a wider range of prions, including rodent experimental strains but also natural agents from sheep and cervids, should prompt the spread of cell assays for routine prion titration and lead to valuable information in fundamental and applied studies.

Isoflavone Consumption Does Not Increase the Bone Mass in Osteopenic Obese Female Zucker Rats

Some controversy exists in the literature concerning the effects of leptin on bone metabolism. Thus we have compared femoral bone density and biochemical markers of bone metabolism in male and female fatty (leptin-resistant) Zucker rats and their lean homozygous controls at 3 and 6 months of age. At 3 months, no differences concerning total, diaphyseal (cortical bone), and distal metaphyseal (trabecular bone) femoral bone densities, plasma osteocalcin concentrations, and urinary deoxypyridinoline excretion were observed between fatty and lean rats. On the opposite, at 6 months of age, in both males and females, total, diaphyseal, and distal metaphyseal femoral bone densities and plasma osteocalcin concentrations were lower in Zucker than in lean rats. Soybean isoflavone consumption (40 µg/g body weight/day for 90 days, a dose which prevents osteopenia following ovariectomy both in lean Zucker homozygous controls and in Wistar rats) by obese female Zucker rats had no significant effect upon their bone mass.