REASSESSMENT OF THE DIFFERENTIAL EFFECTS OF ULTRAVIOLET AND IONIZING RADIATION ON HIV PROMOTER: THE USE OF CELL SURVIVAL AS THE BASIS FOR COMPARISONS

Abstract: Effects of different radiation treatments on the human immunodeficiency virus-1 (HIV) promoter were reassessed for exposures comparable to those encountered in clinical or cosmetic practice, using survival of the host cell as a basis for comparisons. The exposures were performed with two ultraviolet radiation sources commonly used as medical or cosmetic devices (UVASUN 2000 and FS20 lamps), a germicidal (G15T8) lamp and an X-ray machine. The UVC component of the FS20 lamp was filtered out. The emission spectra of the lamps were determined. The characteristics of these sources allowed us to discriminate among effects of UVA1 (340–400 nm), UVB + UVA2 (280–340 nm) and UVC (254 nm) radiations. Effects of irradiation were ascertained using cultures of HeLa cells stably transfected with the HIV promoter linked to a reporter—chloramphenicol acetyl transferase—gene. The exposures used caused at least two logs of cell killing. In this cytotoxicity range, UVA1 or X radiations had no effect on the HIV promoter, whereas UVB + UVA2 or UVC radiations activated the HIV promoter in a fluence-dependent manner. Survivals following exposure to UVB + UVA2 or UVC radiation were (1) at the lowest measurable HIV promoter activation, 30 and 20%, respectively, (2) at one-half maximal activation, 6 and 3%, respectively and (3) at the maximal activation, 0.5 and 0.2%, respectively. The results suggest that, among the radiations studied, UVB is the most important modality from the viewpoint of its potential effects on HIV-infected individuals, since (1) UVA1 or X radiations have no effects on the HIV promoter, (2) human exposure to UVC radiation is infrequent and (3) human UVB exposure is very common.     

Bystander Effect Induced by UVC Radiation in Chinese hamster V79 cells

In past decades, researches on radiation‐induced bystander effect mainly focused on ionizing radiation such as α‐particle, β‐particle, X‐ray and γ‐ray. But few researches have been conducted on the ability of ultraviolet (UV) radiation‐induced bystander effect, and knowledge of UVC‐induced bystander effect is far limited. Here, we adopted medium transfer experiment to detect whether UVC could cause bystander effect in Chinese hamster V79 cells. We determined the cell viability, apoptosis rate, chromosome aberration and ultrastructure changes, respectively. Our results showed that: (1) the viability of UVC‐irradiated V79 cells declined significantly with the dosage of UVC; (2) similar to the irradiated cells, the main death type of bystander cells cultured in irradiation conditioned medium (ICMs) was also apoptosis; (3) soluble factors secreted by UVC‐irradiated cells could induce bystander effect in V79 cells; (4) cells treated with 4 h ICM collected from 90 mJ cm^?2 UVC‐irradiated cells displayed the strongest response. Our data revealed that UVC could cause bystander effect through the medium soluble factors excreted from irradiated cells and this bystander effect was a novel quantitative and kinetic response. These findings might provide a foundation to further explore the exact soluble bystander factors and detailed mechanism underlying UVC‐induced bystander effect.     

Structural characterization and biological activity of galactoglucan from Castanea mollissima Blume

Abstract

A galactoglucan (HCPA) was extracted from C. mollissima Blume fruits using hot water, which was composed of glucose and galactose, with a molecular weight of 5.5?kDa. Methylation and 1?D, 2?D NMR spectroscopy analysis showed that HCPA contained [→4)-α-D-Glcp(1→], [→4,6)-α-D-Glcp(1→], [→4)-β-D-Galp(1→] and [α-D-Glcp(1→] motifs in a molar ratio of approximately 6.11:1.08:1.00:1.03. HCPA showed a spherical-like structure as detected by scanning electron microscope (SEM). HCPA biological activity was investigated in vitro. The results showed that HCPA inhibited the proliferation of HeLa, MCF-7 and MGC-803 cells, induced HeLa cells apoptosis and arrested cell cycle in G2/M phase of HeLa cells. HCPA also enhanced the viability and phagocytic ability of RAW 264.7 cells and stimulated the production of NO, TNF-α and IL-6. The results demonstrated that HCPA had a potent antitumor and immunomodulating effects in vitro, suggesting its potential use as functional food and drug products.     

ACTIVATION OF THE HUMAN IMMUNODEFICIENCY VIRUS PROMOTER BY UVA RADIATION IN COMBINATION WITH PSORALENS OR ANGELICINS

Abstract— The effects of mono- and bifunctional furocoumarins plus UVA radiation (PUVA and related treatments) on the human immunodeficiency virus-1 (HIV-1) promoter were studied using HeLa cells stably transfected with the chloramphenicol acetyl transferase gene under the control of the HIV-1 promoter. The experiments were performed with three psoralens (5-methoxypsoralen, 5-MOP; 8-methoxypsoralen, 8-MOP; and 4′-aminomethyl-4,8,5′-trimethyl-psoralen, AMT) and four angelicins (angelicin; 4,5′-diniethylangclicin, 4,5′-DMA; 6,4′-dimethylangelicin, 6,4′-DMA; and 4,6,4′-trimethylangelicin, TMA). The drugs alone and UVA radiation alone showed no erect on the HIV promoter. However, when the cells were incubated with the furocoumarins at 0.1–40 μg/mL and then irradiated. the HIV promoter was activated in distinct fluence ranges, i.e. (1) no promoter activity was discernible at low fluences (e.g. at 0.1 μg/mL of 8-MOP up to 100 kJ/m²), (2) as the fluence was increased, the promoter activity increased to reach a maximum (10–50-fold with respect to the unexposcd samples), and (3) as the fluence was further increased, the promoter activity decreased. Similar (although shifted on the fluence scale) pattcrns were observed with either > 340-nm UVA radiation or with UVA radiation contaminated with a small amount of UVB radiation (typical for PUVA lamps). The effective fluences were inversely related to the drug concentration. Experiments with 5-MOP and 8-MOP indicated reciprocity of the drug concentration and radiation hence. The HIV promoter response patterns were similar for monofunctional angelicins and bifunctional psoralens. This indicated that the furocoumarin-DNA crosslinks are not a prerequisite for the promoter activation and that the monoadducts suffice to elicit the HIV promoter response. The HIV promoter-activating effectiveness of diKcrent drugs correlated with their photosensitizing potential. Thus, among psoralens the effectiveness order was AMT >. 5-MOP >8-MOP, and among angelicins: TMA > 6,4′-DMA > 4,5′-DMA > angelicin. The ektiveness did not vary substantially for 5-MOP, 8-MOP, 4,5′-DMA, and 6,4′-DMA. The combined drug and UVA radiation doses were higher than those that elicit cellular responses or those that may be received by the human white blood cells during cxtracorporeal PUVA therapy (photopheresis).     

Photoprotective and Antigenotoxic Effects of the Flavonoids Apigenin,Naringenin and Pinocembrin

This work evaluated the photoprotective and antigenotoxic effects against ultraviolet B (UVB) radiation of flavonoid compounds apigenin, naringenin and pinocembrin. The photoprotective efficacy of these compounds was estimated using in vitro photoprotection indices, and the antigenotoxicity against UVB radiation was evaluated using the SOS chromotest and an enzymatic (proteinase K/T4 endonuclease V enzyme) comet assay in UV‐treated Escherichia coli and human (HEK‐293) cells, respectively. Naringenin and pinocembrin showed maximum UV‐absorption peak in UVC and UVB zones, while apigenin showed UV‐absorption capability from UVC to UVA range. These compounds acted as UV filters reducing UV‐induced genotoxicity, both in bacteria and in human cells. The enzymatic comet assay resulted highly sensitive for detection of UVB‐induced DNA damage in HEK‐293 cells. In this work, the photoprotective potential of these flavonoids was widely discussed.     

Isolation of a new natural kingiside aglucone derivative and other anti-inflammatory constituents from Syringa reticulata

Abstract

A new secoiridoid, (1R,5S,8S,9R)-1-methyl-kingiside aglucone (1), along with nine known compounds (2–10), were isolated from the ethanol extract of the stem bark of Syringa reticulata (Bl.) Hara. The structure of compound 1 was elucidated using HR-ESI-MS, 1D and 2D NMR spectroscopy. Compounds 1–10 were evaluated for their inhibitory activity against NO, TNF-α and IL-6 production. Compounds 1, 3, 5 and 7–10 significantly inhibited the levels of NO, TNF-α and IL-6 in LPS-induced RAW264.7 cells from concentrations of 3 to 30?μM.     

In vitro DEMONSTRATION OF A FUNDAMENTAL DIFFERENCE IN THE PROLIFERATION OF MURINE and HUMAN BONE MARROW and LYMPHOCYTES FOLLOWING ULTRAVIOLET IRRADIATION: RELEVANCE TO BONE MARROW TRANSPLANTATION

Exposure of rodent allogeneic donor marrow and splenocyte grafts to ultraviolet radiation (UVR) has been shown to permit durable engraftment at doses that abolish graft-versus-host disease (GVHD) and graft rejection. We have compared both murine and human alloreactive and mitogen-induced lymphoid responses and bone marrow proliferation in mixed lymphocyte culture (MLC), phy-tohemagglutinin (PHA)-induced proliferation and colony-forming unit-granulocyte/macrophage (CFU-GM) assays using germicidal UVC (200–290nm), broadband and narrowband UVB (290–320nm) and UVA (320^100 nm) sources. Our data show a wavelength and dose-dependent reduction in lymphoid proliferation in the mouse with CFU-GM survival of50–75% of control at doses required to abolish allogeneic lymphocyte responses for all lamps. In contrast, human lymphocyte responses are more resistant to UVC with CFU-GM proliferation reduced to zero when allostimulation is abolished. Mito-gen-induced lymphoid responses show a similar wavelength-dependent sensitivity. Abolition of response in MLC using UV-irradiated stimulator cells was less sensitive than proliferation with UV-irradiated responder cells at all wavelengths in both species. With all sources, murine CFU-GM proliferation is less susceptible to UVR than human marrow at doses required to abolish lymphoid responses.     

Bystander Me45 Melanoma Cells Increase Damaging Effect in UVC‐irradiated Cells

The aim of our study was to investigate the possible mechanism(s) of the bystander effect induced by UVC light in malignant melanoma Me45 cells that were co‐incubated with irradiated cells of the same line. We have found that the UVC band effectively generated apoptosis, premature senescence, single and double DNA strand breaks and reduced clonogenic survival of bystander cells. However, in the feedback response, the bystander cells intensified damage in directly irradiated cells, especially seen at the level of apoptosis and survival of clonogenic cells. Pretreatment of bystander cells with inhibitor of inducible nitric oxide synthase blocks this signaling. It seems that the mediators of this phenomenon produced and secreted by neighboring cells are superoxide, nitric oxide and TGF‐β. The reverse deleterious effect caused by cells not exposed to UVC in directly exposed cells is opposed to the protective/rescue effect exerted by the bystander cells in the case of ionizing radiation known in the literature. Whether this opposite adverse effect is a feature of only Me45 melanoma cells or whether it is a general phenomenon occurring between cells of other types exposed to ultraviolet radiation requires further research.     

Lignans from Schisandra chinensis rattan stems suppresses primary Aβ1-42-induced microglia activation via NF-κB/MAPK signaling pathway

Microglia cells play important roles in neurodegenerative diseases for clearing amyloid-β and reducing the occurrence of inflammation. In this study, the neuroinflammatory effect and the mechanism of lignans from Schisandra chinensis rattan stems (rsSCH-L) were evaluated by Aβ_1-42-induced primary microglia cell model. The results have shown that rsSCH-L could reduce the levels of pro-inflammatory cytokines, including IL-1β, TNF-α and NO. Moreover, rsSCH-L suppressed the phosphorylations of NF-κB and IκBα as well as p38, JNK and ERK proteins in Aβ_1-42-induced microglia cells. Taken together, rsSCH-L could attenuate microglia cells from neuroinflammation by activating the NF-κB/MAPK signaling pathway.     

ACTIVATION OF NF-KB IN HUMAN SKIN FIBROBLASTS BY THE OXIDATIVE STRESS GENERATED BY UVA RADIATION

We have examined the role of the nucleus and the membrane in the activation of nuclear factor (NF)-KB by oxidant stress generated via the UVA (320–380nm) component of solar radiation. Nuclear extracts from human skin fibroblasts that had been irradiated with UVA at doses that caused little DNA damage contained activated NF-KB that bound to its recognition sequence in DNA. The UVA radiation-dependent activation of NF-KB in enucleated cells confirmed that the nucleus was not involved. On the other hand, UVA radiation-dependent activation of NF-KB appeared to be correlated with membrane damage, and activation could be prevented by a-tocopherol and butylated hydroxytol-uene, agents that inhibited UVA radiation-dependent peroxidation of cell membrane lipids. The activation of NF-KB by the DNA damaging agents UVC (200–290nm) and UVB (290–320nm) radiation also only occurred at doses where significant membrane damage was induced, and, overall, activation was not correlated with the relative levels of DNA damage induced by UVC/UVB and UVA radiations. We conclude that the oxidative modification of membrane components may be an important factor to consider in the UV radiation-dependent activation of NF-KB over all wavelength ranges examined.     

Long-term Effects of 222-nm ultraviolet radiation C Sterilizing Lamps on Mice Susceptible to Ultraviolet Radiation

Germicidal lamps that emit primarily 254 nm ultraviolet radiation (UV) are routinely utilized for surface sterilization but cannot be used for human skin because they cause genotoxicity. As an alternative, 222-nm UVC has been reported to exert sterilizing ability comparable to that of 254-nm UVC without producing cyclobutane pyrimidine dimers (CPDs), the major DNA lesions caused by UV. However, there has been no clear evidence for safety in chronic exposure to skin, particularly with respect to carcinogenesis. We therefore investigated the long-term effects of 222-nm UVC on skin using a highly photocarcinogenic phenotype mice that lack xeroderma pigmentosum complementation group A (Xpa-) gene, which is involved in repairing of CPDs. CPDs formation was recognized only uppermost layer of epidermis even with high dose of 222-nm UVC exposure. No tumors were observed in Xpa-knockout mice and wild-type mice by repetitive irradiation with 222-nm UVC, using a protocol which had shown to produce tumor in Xpa-knockout mice irradiated with broad-band UVB. Furthermore, erythema and ear swelling were not observed in both genotype mice following 222-nm UVC exposure. Our data suggest that 222-nm UVC lamps can be safely used for sterilizing human skin as far as the perspective of skin cancer development.     

A novel icariin type flavonoid from Epimedium pseudowushanense

A novel icariin type flavonoid glycoside with a malonaldehydic acid intramolecular ester and two known flavonoid glycosides were isolated from Epimedium pseudowushanense. Their structures were elucidated on the basis of spectroscopic analysis and comparison of their data to the values reported in the literatures. The anti-inflammatory activities of these compounds icariin 3′′′-O-malonaldehydic acid intramolecular 1′′′′, 2′′′ ester (1), icariin (2) and epimedin C (3) were tested. The results indicated that compounds 1, 2 and 3 showed maximal inhibitory ratio of 27.91, 44.80 and 46.61%, respectively in in vitro anti-inflammatory activity on LPS-induced TNF-α secretion in RAW264.7 cells. Compounds icariin (2) and epimedin C (3) were found to inhibit the secretion of TNF-α to a comparable degree as quercetin.     

Induction of 8-Oxo-7,8-Dihydro-2'-Deoxyguanosine by Ultraviolet Radiation in Calf Thymus DNA and HeLa Cells

Abstract— The levels of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodGuo) in purified calf thymus DNA and HeLa cells were measured following exposure to either UVC, UVB or UVA wavelengths. This DNA damage was quantitated using HPLC coupled with an electrochemical detector. The 8-oxodGuo was induced in purified DNA in a linear dose-dependent fashion by each portion of the UV spectrum at yields of 100, 0.46 and 0.16 8-oxodGuo per 10⁵ 2'-deoxyguanosine (dGuo) per kJ/m² for UVC, UVB and UVA, respectively. However, the amount of 8-oxodGuo in HeLa cells irradiated with these UV sources decreased to approximately 2.0, 0.013 and 0.0034 8-oxodGuo per 10⁵ dGuo per kJ/m², respectively. In contrast, the levels of cyclobutyl pyrimidine dimers were similar in both irradiated DNA and cells. Therefore, 8-oxodGuo is induced in cells exposed to wavelengths throughout the UV spectrum although it appears that protective precesses exist within cells that reduce the UV-induced formation of this oxidative DNA damage. Cell survival was also measured and the number of dimers or 8-oxodGuo per genome per lethal event determined. These calculations are consistent with the conclusion that dimers play a major role in cell lethality for UVC- or UVB-irradiated cells but only a minor role in cells exposed to UVA wavelengths. In addition, it was found that the relative yield of 8-oxodGuo to dimers increased nearly 1000-fold in both UVA-irra-diated cells and DNA compared with cells subjected to either UVC or UVB. These results are supportive of the hypothesis that 8-oxodGuo, and possible other forms of oxidative damage, play an important role in the induction of biological effects caused by wavelengths in the UVA portion of the solar spectrum.     

Induction of phr gene expression in E. coli strain KY706/pPL-1 by He–Ne laser (632.8 nm) irradiation

We have observed that He–Ne laser irradiation of E. coli strain KY706/pPL-1 leads to induction of photolyase gene, phr. The magnitude of induction was found to depend on the He–Ne laser fluence, fluence rate and post-irradiation incubation period in the nutrient medium. The optimum values for fluence and fluence rate were 7×10³ J/m² and 100 W/m², respectively, and the induction of phr gene was observed to saturate beyond an incubation period of 2 h. Experiments carried out with singlet oxygen quenchers and with D₂O suggest that the effect is mediated via singlet oxygen. Photoreactivation studies carried out after UVC exposure of both the He–Ne laser-exposed as well as unexposed cells showed a larger surviving fraction in the He–Ne laser pre-irradiated cells. This can be attributed to He–Ne laser irradiation-induced induction of phr expression. However, since even without photoreactivating light He–Ne laser pre-irradiated cells show higher survival against UVC radiation it appears that He–Ne laser irradiation induces both light-dependent as well as dark DNA repair processes.     

Cell Cycle Kinetics Following UVA Irradiation in Comparison to UVB and UVC Irradiation

Abstract— There is limited information about the carcinogenic effect of longwave ultraviolet radiation (UVA: 315-400 nm). In particular very little is known about the relevant genotoxic damage caused by physiological doses of UVA radiation. A general response of cells to DNA damage is a delay or arrest of the cell cycle. Conversely, such cellular responses after UVA irradiation would indicate significant genotoxic damage. The aim of this study is to compare cell cycle kinetics of human fibroblasts after UVC (190-280 nm radiation), UVB (280-315 nm radiation) and UVA irradiation. Changes in the cell cycle kinetics were assessed by bivariate flow cytometric analysis of DNA synthesis and of DNA content. After UVC, UVB or UVA irradiation of human fibroblasts a suppression was seen of bromodeoxyuridine (BrdU) incorporation at all stages of S phase. The magnitude of this suppression appeared dose dependent. Maximum suppression was reached at 5-7 h after UVB exposure and directly after UVA exposure, and normal levels were reached 25 h after UVB and 7 h after UVA exposure. The lowered BrdU uptake corresponded with a lengthening of the S phase. No dramatic changes in percentages of cells in G₁, S and G₂/M were seen after the various UV irradiations. Apparently, UVA irradiation, like UVB and UVC irradiation, can temporarily inhibit DNA synthesis, which is indicative of genotoxic damage.     

The Proteins from Sika deer antler as potential modulators on cisplatin-induced cytotoxicity in human embryonic kidney 293 cells

Our study aimed to investigate the protective role of SDAPR on cisplatin-induced cytotoxicity and its’ possible mechanism in HEK293 cells. Cell viability was measured by MTT assay. Oxidative stress (SOD, GSH, LDH and MDA), inflammatory factors (TNF-α and IL-6) and apoptosis-related proteins (caspase-3, Bax, Bcl-2) expression were measured. The apoptotic cells were observed by TUNEL staining. Our study results indicated that non-cytotoxic levels of SDAPR significantly increased viability rate (LD₅₀ value of cisplatin is 20 μM), which improved antioxidant defence, attenuated apoptosis by decreasing expression levels of cleaved-caspase-3 and Bax, increasing Bcl-2 expression and inhibiting apoptotic positive cells in HEK 293 cells. In addition, SDAPR treatment markedly inhibited the levels of TNF-α and IL-6. In conclusion, Sika deer antler protein, a potential modulator, could alleviate cisplatin-induced cytotoxicity in HEK 293 cells.