Effect of standard skin care treatments on skin barrier function in X-irradiated hairless mice.

Objective: The effectiveness of skin care to radiation dermatitis (RD) on patients who received radiotherapy for cancer has not been clarified. The purpose of this study was to investigate the effect of moisturizers and skin washing on skin barrier function possibly leading to the development of RD using X-ray irradiated hairless mice. Methods: Nine-week-old hairless mice were irradiated with 10 â€‹Gy of X-rays, and the skin care group had moisturizers applied or skin washing with soap from the day of irradiation during observations. The condition of the skin was observed to evaluate RD. Skin barrier function was evaluated by measuring skin temperature and transepidermal water loss (TEWL) once every two days until 25 days after X-ray irradiation. Results: RD was not observed in all groups until 25 days after X-ray irradiation. Skin temperature tended to increase in all groups regardless of irradiation or skin care. However, unlike the control group, the measured value of TEWL in the no skin care group tended to increase in the days after the X-ray irradiation. On the other hand, TEWL was increased in the skin care group compared with the no skin care group a few days after X-ray irradiation. While TEWL was constant in the moisturizer group, the skin washing groups showed an increasing tendency of TEWL and it reached a peak at 13 days after X-ray irradiation. Conclusions: These results suggested that the decrease in skin barrier function was caused by X-ray irradiation and also that skin washing could contribute to the deterioration of skin barrier function after X-ray irradiation.

Detoxication of Citrinin with Kojic Acid by the Formation of the Citrinin-Kojic Acid Adduct, and the Enhancement of Kojic Acid Production by Citrinin via Oxidative Stress in Aspergillus parasiticus

Our previous work showed that citrinin (CTN) produced bay Penicillium citrinum inhibited the production of aflatoxin by Aspergillus parasiticus. We also reported that CTN was non-enzymatically converted to a novel CTN-KA adduct with kojic acid (KA) in aqueous condition. We herein observed that unlike CTN, the CTN-KA adduct does not show antimicrobial activity against Escherichia coli or Bacillus subtilis or any cytotoxic effect on HeLa cells, suggesting that CTN was detoxified by KA by the formation of the CTN-KA adduct. To examine the function of KA production by fungi, we isolated A. parasiticus mutants with impaired KA production. When the mutants were incubated in either liquid or agar medium supplemented with CTN, they were more susceptible to CTN than the wild KA-producing strain. The same results were obtained when we used the A. oryzae KA-producing strain RIB40 and KA-non-producing strains. When KA was added to the CTN-containing agar medium, the inhibition of growth by CTN was remarkably mitigated, suggesting that the production of KA protected the fungal growth from CTN's toxicity. We also observed that CTN enhanced the production of KA by A. parasiticus as well as A. oryzae strains. Reverse transcription-PCR showed that CTN enhanced the expression of KA biosynthetic genes (kojA, kojR, and kojT) of A. parasiticus. However, the enhancement of KA production with CTN was repressed by the addition of α-tocopherol or butylated hydroxy anisole, suggesting that KA production is enhanced by oxidative stress via the formation of reactive oxygen species caused by CTN. In contrast, α-tocopherol did not affect inhibition of AF production as well as fungal growth by CTN, suggesting that the regulation of these inhibitions with CTN might be different from that of KA production. We propose a regulation scheme of CTN for each of KA production, AF production, and fungal growth in A. parasiticus.

Early and Delayed Induction of DSBs by Nontargeted Effects in ICR Mouse Lymphocytes after In Vivo X Irradiation.

The goal of this study was to determine whether in vivo X irradiation induces nontargeted effects, such as delayed effects and bystander effects in ICR mouse lymphocytes. We first examined the generation of DNA double-strand breaks (DSBs) in lymphocytes, isolated from ICR mice exposed to 1 Gy X irradiation, by enumeration of p53 binding protein 1 (53BP1) foci, and observed that the number of 53BP1 foci reached their maximum 3 days postirradiation and decreased to background level 30 days postirradiation. However, the number of 53BP1 foci was significantly increased in lymphocytes isolated from ICR mice 90-365 days postirradiation. This result indicates that in vivo X irradiation induced delayed DSBs in ICR mouse lymphocytes. We next counted the number of 53BP1 foci in lymphocytes isolated from sham-irradiated ICR mice that had been co-cultured with lymphocytes isolated from 1 Gy X-irradiated ICR mice, and observed a significant increase in the number of 53BP1 foci 1-7 days postirradiation. This result indicates that in vivo X irradiation induced bystander effects in ICR mouse lymphocytes. These findings suggest that in vivo X irradiation induces early and delayed nontargeted effects in ICR mouse lymphocytes.

Rubratoxin B induces signs of fatty acid oxidation disorders (FAODs) in mice.

Rubratoxin B is a mycotoxin that causes hypoglycemia and fatty liver. We investigated the effect of rubratoxin B on hepatic glycogen content and regulation, because blood glucose levels are associated with hepatic glycogen storage. Mice were treated with 1.5mg/kg rubratoxin B for 24h. Stomachs of treated mice became extremely swollen, and the contents were significantly heavier than those of controls. Hypoglycemia stimulates appetite; therefore, rubratoxin B may perturb satiation. Rubratoxin B evidently depleted hepatic glycogen stores. Phosphoenolpyruvate carboxykinase (PEPCK) activity and mRNA levels in treated mice were reduced, indicating that rubratoxin B caused hepatic glycogen depletion by inhibiting PEPCK. PEPCK activity and mRNA levels were reduced to similar degrees; it appears that PEPCK activity is regulated transcriptionally. Levels of the PEPCK gene trans-activators phospho-CREB (active form) and C/EBPα were significantly reduced in the livers of treated mice, suggesting that these factors are important for PEPCK gene transcription. Rubratoxicosis and fatty acid oxidation disorders (FAODs) share characteristic signs, such as robust appetite, hypoglycemia, hepatic glycogen depletion, and fatty liver. Although FAODs are generally considered genetic deficiencies, our results indicate that a chemical can also cause FAOD-like signs in mice.

Rubratoxin B induces interleukin-6 secretion in mouse white adipose tissues and 3T3-L1 adipocytes.

Rubratoxin B is a mycotoxin that causes hepatic fatty changes. We examined whether white adipose tissue (WAT) contributes to rubratoxin B toxicity through effects on interleukin (IL)-6. Rubratoxin B was intraperitoneally injected into mice at 1.5mg/kg. Urinary albumin and macrophage inflammatory protein (MIP)-2 secretion were increased 24h after treatment with rubratoxin B. Rubratoxin B was previously reported to induce IL-6 secretion, although the secreting tissue was unknown. Here, rubratoxin B prominently augmented IL-6 transcription in epididymal WAT and to a lesser extent in perirenal WAT and liver. Rubratoxin B may thus exert its toxicity partly through IL-6 secretion from WATs. In contrast, MIP-2 gene expression increased only in liver. To examine the specific involvement of adipocytes, we used mouse 3T3-L1 cells, an in vitro differentiation model of adipocytes. Expression of IL-6 and MIP-2 mRNA in 3T3-L1 adipocytes after 24h of rubratoxin B treatment increased dose-dependently. Rubratoxin B also increased IL-6 and MIP-2 secretion from 3T3-L1 adipocytes. The increase in IL-6 secretion was markedly higher than the increase in IL-6 gene transcription, indicating that rubratoxin B-induced secretion of IL-6 from 3T3-L1 adipocytes is chiefly controlled post-transcriptionally. Rubratoxin B is thus the first mycotoxin known to exert its toxicity through effects on WATs.

Induced secretion of insulin-like growth factor binding protein-1 (IGFBP-1) in human hepatoma cell HepG2 by rubratoxin B.

The induction of insulin-like growth factor binding protein-1 (IGFBP-1) secretion by rubratoxin B was investigated using human hepatoma cell line HepG2; we also documented the involvement of stress-activated MAP kinases [c-Jun-N-terminal kinases (JNKs) and p38s] in this process. Rubratoxin B dramatically enhanced IGFBP-1 secretion, which peaked at a concentration of 40 microg/ml. The amount of IGFBP-1 mRNA increased with time and plateaued at 6 h. Compared with the amounts of IGFBP-1 secreted, the induction ratios of transcription were much smaller, indicating that IGFBP-1 secretion is regulated chiefly post-transcriptionally. The result of concomitant treatment with rubratoxin B and JNK inhibitor indicated that JNKs do not affect rubratoxin B-induced IGFBP-1 secretion. Alternatively, rubratoxin B-associated induction of IGFBP-1 secretion was marked in the absence of p38 inhibitor but attenuated in its presence. Therefore, p38s appear to stimulate rubratoxin B-induced IGFBP-1 secretion. Treatment with p38 inhibitor slightly increased the amount of rubratoxin B-induced IGFBP-1 mRNA. However this induction ratio was smaller than that of rubratoxin B-induced secretion, suggesting that p38s regulate IGFBP-1 secretion both transcriptionally and post-transcriptionally. In this study, we showed that rubratoxin B induces IGFBP-1 levels in HepG2 cells and p38s contribute to this process.

Induction of apoptosis in cancer cells by Bilberry (Vaccinium myrtillus) and the anthocyanins.

Among ethanol extracts of 10 edible berries, bilberry extract was found to be the most effective at inhibiting the growth of HL60 human leukemia cells and HCT116 human colon carcinoma cells in vitro. Bilberry extract induced apoptotic cell bodies and nucleosomal DNA fragmentation in HL60 cells. The proportion of apoptotic cells induced by bilberry extract in HCT116 was much lower than that in HL60 cells, and DNA fragmentation was not induced in the former. Of the extracts tested, that from bilberry contained the largest amounts of phenolic compounds, including anthocyanins, and showed the greatest 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity. Pure delphinidin and malvidin, like the glycosides isolated from the bilberry extract, induced apoptosis in HL60 cells. These results indicate that the bilberry extract and the anthocyanins, bearing delphinidin or malvidin as the aglycon, inhibit the growth of HL60 cells through the induction of apoptosis. Only pure delphinidin and the glycoside isolated from the bilberry extract, but not malvidin and the glycoside, inhibited the growth of HCT116 cells.