High peroxidative susceptibility of fish oil polyunsaturated fatty acid in cultured rat hepatocytes.

The peroxidative susceptibility in cultured rat hepatocytes of eicosapentaenoic acid (EPA) and other polyunsaturated fatty acids (PUFA) with different numbers of double bonds was examined. Lipid peroxidation was evaluated using a newly developed HPLC procedure which includes the determination of malondialdehyde (MDA). Following exposure to 0.25-1.0 mM EPA adsorbed to BSA (EPA-BSA), cultured hepatocytes produced MDA in the fatty acid concentration- and incubation time-dependent manner. The rate of MDA production by hepatocytes varied greatly with the degree of PUFA unsaturation, and ranked as follows: docosahexaenoic acid > EPA > arachidonic acid > alpha-linolenic acid = gamma-linolenic acid > linoleic acid > oleic acid. Prolonged exposure of cultured hepatocytes to 1.0 mM EPA-BSA resulted in substantial leakage of LDH into the medium. The cell injury was associated with the loss of cellular GSH and protein thiol groups. Cotreatment of the EPA-supplemented hepatocytes with a GSH-depleting agent, diethylmaleate, promoted the cellular protein thiol loss and LDH leakage. An iron chelator, deferoxamine, and other antioxidants such as N,N-diphenyl-p-phenylenediamine and gamma-tocopherol efficiently prevented MDA production and consequently LDH leakage in the EPA-supplemented hepatocytes. These results show that peroxidative deterioration in excess of GSH-dependent defense mechanisms may occur in hepatocytes loaded with highly peroxidizable fish oil PUFA.

Effect of cumene hydroperoxide on lipid peroxidation in cultured rat hepatocytes supplemented with eicosapentaenoic acid.

The present study was undertaken to examine whether the oxidative effect of organic hydroperoxide on cultured rat hepatocytes is enhanced by eicosapentaenoic acid (EPA). The cells were pretreated with 0.8 mM EPA which was complexed to bovine serum albumin (EPA-BSA) for 4 h, and then challenged to cumene hydroperoxide (CMHP). By the addition of CMHP to the cell culture, lipid peroxidation estimated as production of malondialdehyde (MDA) was provoked to a much greater extent in the EPA-loaded hepatocytes than in the non-loaded cells. The CMHP treatment also resulted in more severe cell injury in association with the decrease in intracellular levels of glutathione and protein thiols in the EPA-loaded cells as compared with results in the non-loaded cells. The addition of antioxidants such as N,N'-diphenyl-p-phenylenediamine (DPPD), promethazine and gamma-tocopherol to the culture medium prevented the CMHP-induced oxidative injury effectively for the EPA-loaded cells but had little effect for the non-loaded cells. The potency of other unsaturated fatty acids with different numbers of double bonds in enhancing the CMHP-induced lipid peroxidation and injury was also examined. The deleterious effects of CMHP were little affected by unsaturated fatty acids with one or two double bonds but were markedly intensified by those with more than 4 double bonds. These data showed that the supplementation with highly unsaturated fatty acids makes the cells susceptible to the drug-induced oxidative stress.

The influence of severe bone loss on mitral annular calcification in postmenopausal osteoporosis of elderly Japanese women.

We assessed the influence of aging bone calcium metabolism on mitral annular calcification (MAC) and aortic valve calcification (AVC) in 239 septua- and octogenarians (62 men, 177 women; 80.2 +/- 4.4 years). Osteoporosis was diagnosed by vertebral bone fracture. Both MAC and AVC were derived by 2-dimensional echocardiography. Bone mineral content (BMC) of the lumbar vertebral body was obtained by single-energy quantitative computed tomography using a calibration phantom. Serum calcium, phosphorus, parathyroid hormone, calcitonin, and osteocalcin were examined. Patients were classified into 3 age-matched groups in each sex: Group-C included patients with MAC (-) and AVC (-) (n = 96); Group-A was those with AVC (+) and MAC (-) (n = 80); Group-M consisted of those with MAC (+) and AVC (-) or AVC (+) (n = 63). Osteoporosis-frequency and BMC in women were significantly higher (p < 0.01) and lower (p < 0.001) respectively than those in men. Among men, osteoporosis-frequency and BMC showed no difference between the 3 groups. Among women, osteoporosis-frequency (52%) and BMC (32 +/- 23 mg/cm3) in Group-M were higher (NS) and significantly less (p < 0.01) than those (37%, 49 +/- 36) in Group-C, respectively. In both sexes, serum examinations revealed no differences between the 3 groups. These results suggest that: 1) MAC in elderly women can be attributed to ectopic calcium deposits, related to the severe bone loss caused by postmenopausal osteoporosis; 2) there is no significant relationship between the incidence of MAC or AVC and the humoral factors of calcium metabolism; and 3) AVC may be mainly caused by pressure or stress loading.

Distribution of fluoride in sound and periodontally diseased human cementum.

Fluoride distribution was investigated by an abrasive micro-sampling technique. The fluoride concentration increased with age in both sound and diseased cementum. In sound teeth, the fluoride profiles (distribution of fluoride from the surface to interior) of the middle and apical cementum were similar. In the diseased cementum the profile of the middle region tended to be more variable than that of the apical cementum, suggesting a possible effect of the oral environment on the fluoride profile at this site.

Enhanced small intestinal absorption of beta-lactam antibiotics in rats in the presence of monodesmosides isolated from pericarps of Sapindus mukurossi (Enmei-hi).

Monodesmoside, saponin A, B and C, isolated from pericarps of Sapindus mukurossi (Enmei-hi) have been shown to promote absorption of poorly absorbed beta-lactam antibiotics by the small intestine using an in situ loop method. Monodesmosides were solubilized with ginseng crude saponin extract, a mixture of bisdesmosides, saponin X, Y1 and Y2 which were isolated also from Sapindus mukurossi. These solubilizing agents were demonstrated not to influence the absorption promoting effect of monodesmosides. Among the monodesmosides, saponin B showed the greatest effect. No influence of osmolarity of the administered solution on the absorption promoting action was observed. The promoting functions of the three monodesmosides for the small intestinal absorption of antibiotics were suppressed by Ca2+ ion coexisting in the administered solution.

Enhanced rectal absorption of beta-lactam antibiotics in rat by monodesmosides isolated from pericarps of Sapindus mukurossi (Enmei-hi).

Monodesmosides, saponin A,B and C, isolated from pericarps of Sapindus mukurossi (Enmei-hi) were shown to promote the rectal absorption of beta-lactam antibiotics in rat, using an in situ loop method and an in vivo method. In the in situ loop method, monodesmosides were solubilized with a mixture of bisdesmosides, mukurozi-saponin X, Y1 and Y2, each of which was isolated from pericarps of Sapindus mukurossi. The promoting functions of the three monodesmosides for the rectal absorption of antibiotics were comparable and also suppressed by Ca2+ ion coexisting in the administered solution. Unlike the case of N-acylcollagenpeptides, which were also previously reported as absorption promoters, no influence of osmolarity of the administered solution on the absorption promoting action was observed. Absorption of beta-lactam antibiotics from suppositories was enhanced with the aid of either of monodesmosides without solubilizing agent.