The present study indicated that PPPs could be used in foods as natural antioxidants with strong antioxidant activity. Copyright © 2007 Society of Chemical Industry.

Previously pleiotrophin (PTN) was identified among proteins secreted by Swiss 3T3 cells as a mitogen for cultured adult rat hepatocytes. The present study showed that the growth of rat hepatocytes was enhanced when cultured with rat hepatic stellate cells (HSCs). HSCs expressed PTN mRNA and secreted its protein in the co-cultures. Recombinant PTN enhanced the growth of hepatocytes in culture, suggesting that HSCs stimulate the growth of hepatocytes through the action of PTN. To know the biological role of PTN in the growth of hepatocytes in vivo, we examined the expression of PTN in four regeneration models of adult liver and embryonic liver of rat. The expression of PTN mRNA in the liver was markedly up-regulated by the treatment with D-galactosamine (GalN) or with acetylaminofluorene followed by partial hepatectomy. HSCs expressed PTN mRNA in response to GalN treatment and its protein was found on hepatocytes. The mRNA expression of N-syndecan, a PTN receptor, was up-regulated in GalN-treated hepatocytes. The mesenchymal cells in the septum transversum enclosing the embryonic liver, but not embryonic HSCs, expressed PTN mRNA. We suggest that PTN is secreted from activated adult HSCs and embryonic mesenchymal cells as a mitogen of parenchymal cells in adult and embryonic liver, respectively.

The protective effects of hen egg yolk phosvitin phosphopeptides (PPPs) against hydrogen peroxide (H2O2)-induced oxidative stress were evaluated in an in vitro assay using human intestinal epithelial cells. Caco-2 cells were stimulated with 1 mM H2O2 for 6 h, and the secretion of IL-8, a proinflammatory mediator, was determined by ELISA as a biomarker of oxidative stress. The inhibition of H2O2-induced IL-8 secretion from Caco-2 cells was observed by pretreatment for 2 h with PPPs, but not with phosvitin. PPPs also suppressed the formation of malondialdehyde in H2O2-treated Caco-2 cells. Furthermore, intracellular glutathione levels and glutathione reductase activity were elevated by the addition of PPPs. The protective effects of PPPs against H2O2-induced oxidative stress were almost the same as that of glutathione, and PPPs with a high content of phosphorus exhibited higher protective activity than PPPs without phosphorus; however, phosphoserine itself did not show any significant antioxidative stress activity. These findings suggest that oligophosphopeptides from hen egg yolk phosvitin possess novel antioxidative activity against oxidative stress in intestinal epithelial cells and that phosphorus and peptide structure seem to have a key role in the activity.

The present study was performed to determine whether hepatocytes show a size-dependent growth in vivo using as a growth assay system, a retrorsine/ partial hepatectomy model of dipeptidyl dipeptidase IV-deficient (DPPIV ؊ ) mutant Fischer rats. Nearly pure populations of small hepatocytes (SHs) and parenchymal hepatocytes (PHs) were prepared from DPPIV ؉ rats. The same number of these SHs and PHs was transplanted into the liver of retrorsine-treated and two-thirds partial hepatectomized DPPIV ؊ rats. At 21 days after transplantation, colonies derived from donor hepatocytes were detected as DPPIV Since a two-step collagenase perfusion method to isolate parenchymal hepatocytes (PHs) was established by Seglen, 1 extensive studies have been performed aiming at understanding the proliferation and differentiation of the hepatocytes using disaggregated and cultured rat hepatocytes. However, these cells cannot generally be maintained for a long term as replicating differentiated cells.Recently, we have developed a culture method by which hepatocytes can grow forming clonal colonies for a long term.2 This culture focused on small hepatocytes (SHs) present in the nonparenchymal cell fraction. We showed that the SHs have a higher growth potential than PHs. 3 We further characterized SHs and PHs by subjecting them to fractionation by a fluorescent-activated cell sorter (FACS).3 SHs produced two cell populations, SH-R2s and SH-R3s. 3 The former showed a higher granularity and autofluorescence than the latter.3 In contrast, PHs produced only one population (PH-R2s) whose FACS characteristics were similar to the SH-R2s. 3 The size of hepatocytes of SH-R3s (17.1 Ϯ 0.2 m, mean Ϯ SE) as measured by diameter was smaller than those of SH-R2s (22.6 Ϯ 0.5 m) and PH-R2s (24.1 Ϯ 0.1 m), and there was not a significant overlap in the size distribution between the two groups.3 SH-R3s were highly replicative in vitro, their growth potential being four or five times higher than that of SH-R2s and PH-R2s.3 Apparently, the extent of cytoplasmic granularity and autofluorescence of hepatocytes was reversely related to their growth potential. Although little is known about the relationship between the extent of autofluorescence and the maturation of hepatocytes, there has been a report that related the increased granularity to the maturation of endoplasmic reticula, Golgi apparatus, lysosomes, and mitochondria of hepatocytes. 4Sigal and colleagues 5 actually compared the extent of autofluorescence and granularity of hepatocytes among embryos, sucklings, and adults by FACS. Hepatocytes increased their granularity and autofluorescence as the liver developed from fetus to suckling, and to adult. 5Conversely the proportion of S-phase cells progressively declined during this developmental process. 5 They also showed that the adult liver contains small and mononuclear hepatocytes whose granularity and autofluorescence were comparable to fetal hepatocytes. 5 Our previous studies support the results obtained by the cited authors and suggest that not on...

Chlorogenic acid (CGA) is a natural chemical ester composed of caffeic acid and (-)-quinic acid, and is further metabolized into active compounds in the living body. Here, we aimed to provide fundamental information on the antimicrobial action of CGA and related compounds against the Gram-negative bacterium Escherichia coli IFO 3301. Bacteriostatic effects were assessed by spectrophotometry, and bactericidal effects were determined by enumerating viable cells on MacConkey agar plates. CGA and related compounds exhibited specific antimicrobial activity and corresponding reduction in log survival ratio, in which ferulic, isoferulic, benzoic, and hydroxybenzoic acids exhibited obvious antimicrobial activity against E. coli. In a timekill assay, it was observed that bactericidal effects were associated with treatment time, temperature, and dose. A reduction in log survival ratio was observed at low pH as well as under thermal stress condition. Thus, we demonstrated that CGA and related compounds have not only bacteriostatic effects but also bactericidal effects. Keywords bactericidal effect • bacteriostatic effect • chlorogenic acid • polyphenol Materials and MethodsMaterials. Dimethyl sulfoxide, quinic acid, and ferulic acid were purchased from WAKO Pure Chemical Industries Ltd. (Japan). Luria broth (LB), and benzoic, hydroxybenzoic, caffeic, and hippuric acids were purchased from SIGMA-ALDRICH (Japan).

No abstract

This study validates, for the first time, the use of OVA-glycated mannose and glucomannan for potential beneficial dietary interventions for allergy.

The protective effects of amino acids against H 2O 2-induced oxidative stress were investigated in an in vitro assay using human intestinal epithelial cells. Caco-2 cells were pretreated with amino acids (1, 2, and 5 mM) for 2 h and then stimulated with 1 mM H 2O 2 for 6 h. The secretion of IL-8, a proinflammatory mediator, was determined by ELISA as an indicator of tissue oxidative stress. The inhibition of H 2O 2-induced IL-8 secretion from Caco-2 cells was observed by pretreatment with Cys, Val, Ile, Leu, Trp, His, Lys, and Ala. Cys enhanced glutathione (GSH) biosynthesis enzyme activity and increased cellular GSH levels. Branched-chain amino acids such as Val, Ile, and Leu elevated activities of GSH S-transferase (GST) and catalase. Trp, His, and Lys caused increases in GST activity. Ala enhanced GSH reductase activity. These data suggest that specific amino acids exert protective effects against tissue oxidative stress in intestinal epithelial cells based on the structure.