Arsenic-induced enhancement of ultraviolet radiation carcinogenesis in mouse skin: a dose-response study

The present study was designed to establish the form of the dose-response relationship for dietary sodium arsenite as a co-carcinogen with ultraviolet radiation (UVR) in a mouse skin model. Hairless mice (strain Skh1) were fed sodium arsenite continuously in drinking water starting at 21 days of age at concentrations of 0.0, 1.25, 2.5, 5.0, and 10 mg/L. At 42 days of age, solar spectrum UVR exposures were applied three times weekly to the dorsal skin at 1.0 kJ/m2 per exposure until the experiment ended at 182 days. Untreated mice and mice fed only arsenite developed no tumors. In the remaining groups a total of 322 locally invasive squamous carcinomas occurred. The carcinoma yield in mice exposed only to UVR was 2.4 +/- 0.5 cancers/mouse at 182 days. Dietary arsenite markedly enhanced the UVR-induced cancer yield in a pattern consistent with linearity up to a peak of 11.1 +/- 1.0 cancers/mouse at 5.0 mg/L arsenite, representing a peak enhancement ratio of 4.63 +/- 1.05. A decline occurred to 6.8 +/- 0.8 cancers/mouse at 10.0 mg/L arsenite. New cancer rates exhibited a consistent-with-linear dependence on time beginning after initial cancer-free intervals ranging between 88 and 95 days. Epidermal hyperplasia was elevated by arsenite alone and UVR alone and was greater than additive for the combined exposures as were growth rates of the cancers. These results demonstrate the usefulness of a new animal model for studying the carcinogenic action of dietary arsenite on skin exposed to UVR and should contribute to understanding how to make use of animal data for assessment of human cancer risks in tissues exposed to mixtures of carcinogens and cancer-enhancing agents.     

海带多糖对紫外线辐射小鼠皮肤胶原蛋白及微血管内皮细胞的影响

目的 探讨海带多糖对紫外线辐射小鼠皮肤胶原蛋白及微血管内皮细胞(microvascular endothelial cells,MVEC)的影响.方法 昆明小鼠背部剃毛,随机分为对照组、模型组、海带多糖低剂量组(1 mg/kg)、海带多糖高剂量组(5 mg/kg)、维生素E(Vit E)组(100 mg/kg).除对照组外,其他各组每日予以紫外线照射1h,每周5次,连续8周.造模后,各组小鼠取背部暴露皮肤,检测皮肤组织过氧化氢(H2O2)、丙二醛(MDA)、超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、谷胱甘肽过氧化酶(GSH-Px)、羟脯氨酸(Hyp)的含量及皮肤组织Ⅰ型胶原蛋白mRNA的相对定量,同时检测血清NO水平,行透射电镜观察皮肤MVEC的超微结构.结果 与模型组比较,海带多糖高剂量组及Vit E组皮肤组织MDA、H2O2水平降低(P＜0.01),皮肤组织SO、GSH-Px、CAT、Hyp、Ⅰ型胶原蛋白mRNA及血清NO水平均升高(P＜0.05).超微电镜显示,模型组MVEC细胞膜模糊,胞质内出现大小不等的空泡,线粒体嵴模糊不清;海带多糖高剂量组MVEC细胞膜完整,线粒体嵴清晰.结论 海带多糖可以增强受紫外线辐射皮肤的抗氧化能力,保护皮肤MVEC,调节皮肤胶原蛋白的合成.     

长波紫外线对人皮肤成纤维细胞生长的影响

[目的 ]　观察长波紫外线 (UVA)对人皮肤成纤维细胞生长的影响 ,探讨皮肤光老化机制。　 [方法 ]　将原代培养的人皮肤成纤维细胞经UVA照射后 ,采用细胞成像、四唑盐比色实验 (MTT)、乳酸脱氢酶 (LDH)检测UVA对皮肤细胞的损伤。　 [结果 ]　随UVA照射剂量增加 ,成纤维细胞由正常细长梭状逐渐变圆、皱缩 ;UVA照射剂量为 9J/cm2 时 ,LDH从 ( 5 6.82± 4.78)U /dl上升至 ( 12 0 .40± 7.16U ) /dl;UVA照射剂量为 45J/cm2 时 ,成纤维细胞抑制率达到67.12 %。　 [结论 ]　UVA可损伤原代培养的人皮肤成纤维细胞     

Germicidal ultraviolet irradiation in air conditioning systems: effect on office worker health and wellbeing: a pilot study

OBJECTIVES: The indoor environment of modern office buildings represents a new ecosystem that has been created totally by humans. Bacteria and fungi may contaminate this indoor environment, including the ventilation systems themselves, which in turn may result in adverse health effects. The objectives of this study were to test whether installation and operation of germicidal ultraviolet (GUV) lights in central ventilation systems would be feasible, without adverse effects, undetected by building occupants, and effective in eliminating microbial contamination. METHODS: GUV lights were installed in the ventilation systems serving three floors of an office building, and were turned on and off during a total of four alternating 3 week blocks. Workers reported their environmental satisfaction, symptoms, as well as sickness absence, without knowledge of whether GUV lights were on or off. The indoor environment was measured in detail including airborne and surface bacteria and fungi. RESULTS: Airborne bacteria and fungi were not significantly different whether GUV lights were on or off, but were virtually eliminated from the surfaces of the ventilation system after 3 weeks of operation of GUV light. Of the other environmental variables measured, only total airborne particulates were significantly different under the two experimental conditions--higher with GUV lights on than off. Of 113 eligible workers, 104 (87%) participated; their environmental satisfaction ratings were not different whether GUV lights were on or off. Headache, difficulty concentrating, and eye irritation occurred less often with GUV lights on whereas skin rash or irritation was more common. Overall, the average number of work related symptoms reported was 1.1 with GUV lights off compared with 0.9 with GUV lights on. CONCLUSION: Installation and operation of GUV lights in central heating, ventilation and air conditioning systems of office buildings is feasible, cannot be detected by workers, and does not seem to result in any adverse effects.

 

     

A study on the activity of fibroblast cells in connection with tissue recovery in the wounds of skin injury after whole-body irradiation

The 6 Gy of whole-body irradiation (WBI) with gamma rays results in an impairment of injured skin tissue recovery and renders a delay in the healing process. For an understanding of whether WBI has damaging effects on fibroblasts in wounds, fibroblasts in wounds combined with WBI and those of simple incision were isolated and cultivated, and abilities connected with tissue repair, including proliferation, attachment, adhesion, and apoptosis, were determined by direct cell count, immunohistochemical staining for proliferation cell nuclear antigen (PCNA), and TUNEL assay. The results showed that the abilities of proliferation and the attachment and adhesion of fibroblasts from wounds combined with WBI significantly decreased in comparison with those having simple incisions on the 3rd and 5th days of posttrauma, whereas the apoptotic ratio of fibroblasts from wounds combined with WBI significantly increased. These data suggest that WBI may exert damaging effects on fibroblasts in wounds, which might be one of the dominant reasons for the impaired healing of wounds combined with WBI.     

Effect of cupric ions on the initiation protein synthesis rate in the human endometrium

The effect of cupric ions on the initiation protein synthesis rate of the human endometrium was studied. Addition of copper to the complete ribosomal system decreased the binding of [³H]Met-tRNA(i) to the isolated ribosomes with a plateau at about 70% inhibition with concentrations higher than 150 μM.

The initiation activity was GTP-dependent with a maximum at 2 mM. This activity was very rapid, requiring 5 min to complete the reaction. Incubation of isolated initiation factors with copper (300 μM) inhibited the formation of the ternary complex. When the complete system was reconstituted with salt-washed ribosomes after ternary complex formation, no significant change on the inhibition pattern was observed. Addition of initiation factors to 5-min preincubated salt-washed ribosomes with 300 μM copper, after the elimination of excess copper, induced only a 12% decrease on Met-tRNA(i) binding. This effect was not modified by the presence of Sparsomycin, an elongation inhibitor. It was concluded that copper interferes with the initiation process, probably at the ternary complex formation level.     

Effect of methylmercury and inorganic mercury on protein synthesis in mammalian cells

Effects of methylmercury and inorganic mercury on protein synthesis in several mammalian cells and cell-free systems were studied. Inorganic mercury showed about a 10 times stronger inhibitory effect on protein synthesis than methylmercury in the cell-free systems prepared from mouse glioma, Yoshida ascites sarcoma cells, and rabbit reticulocytes. Methylmercury inhibited protein in intact cells of Yoshida ascites sarcoma more strongly than inorganic mercury and exerted nearly the same inhibitory effect on protein synthesis in mouse glioma and rabbit reticulocytes as inorganic mercury.     

The effects of topical and oral L-selenomethionine on pigmentation and skin cancer induced by ultraviolet irradiation.

This study was conducted to determine whether oral and/or topical selenium (Se) supplementation can reduce the incidence of acute and/or chronic damage to the skin (i.e., sunburn and pigmentation and/or skin cancer, respectively) induced by ultraviolet (UV) irradiation in mice. Groups of 38 BALB:c female mice or 16 Skh:2 hairless pigmented mice were treated with 1) lotion vehicle, 2) 0.02% L-selenomethionine (SeMet) lotion, or 3) vehicle and 1.5 ppm SeMet in the drinking water. Within each group, 30 BALB:c mice or 12 Skh:2 mice were given UV irradiation (Westinghouse FS 40 bulbs) three times per week in doses of 0.575 and 0.24 J/cm2, respectively. The animals' weights and food intakes and the Se concentrations of skin and liver were measured. Skin biopsies were taken from the backs and abdomens of all animals to evaluate the relative amounts of Se and the damage by UV irradiation. Skin pigmentation was scored, and the total number of clinically detectable skin tumors per animal was counted weekly. Results showed that the skin Se concentrations in areas of application of the lotion containing SeMet were greater than those of animals given comparable oral doses, while the Se concentrations of untreated skin and liver were similar to those of animals receiving oral Se. Mice treated with Se showed no signs of toxicity and had significantly less skin damage by UV irradiation, as indicated by reduced inflammation and pigmentation and by later onset and lesser incidence of skin cancer.     

Effect of amino acid infusion on human postoperative colon protein synthesis in situ

BACKGROUND: Amino acids are an integral part of parenteral nutrition because of their anabolic action helping to conserve body protein after surgical stress. At the gastrointestinal tract, an adequate supply of amino acids may be particularly important because of the gut's high rate of protein turnover, cell division, and proliferation. However, no information is available about the effects of amino acids on human intestinal protein metabolism after surgery. METHODS: Studies were performed in postabsorptive patients 8-10 days after major abdominal surgery. Mass spectrometry techniques (capillary gas chromatography/combustion isotope ratio mass spectrometry) were used to directly determine the incorporation rate of 1-[13C]-leucine into colon mucosal protein. All subjects had a colostomy, which allowed easy access to the colon mucosa, and consecutive sampling from the same tissue was performed during continuous isotope infusion (0.16 micromol/kg min). Isotopic enrichments were determined at baseline and after a 4-hour infusion of amino acids or after infusion of saline (control group). RESULTS: Compared with baseline, infusion of amino acids reduced fractional colon protein synthesis significantly by -29.2 +/- 8.3%. This decrease was also significantly different from the corresponding (insignificant) change during saline infusion (+19.4 +/- 26.9%, p < .05 vs amino acid group). CONCLUSIONS: After surgery, an amino acid infusion acutely reduces postoperative colon protein synthesis. This effect possibly may be attributed to interactions of specific amino acids (glutamine) with an altered intestinal immune system and enterocyte activity.     

Effect of ultraviolet irradiation on calcium, sodium and potassium levels in albino rats

Data presented by the authors testifies to the fact that neither 2 weeks, nor one month after the 10-day course of ultraviolet irradiation (UVR) with an intensity from 1/4 up to 2 biodoses daily changes in calcium, sodium and potassium content in blood serum of laboratory animals (white rats) were detected. At the same time, 2 weeks following the cessation of UVR course a tendency towards calcium accumulation in the whole organism of laboratory animals was observed, which was most noticeable+ after daily 10-day exposure to UVR with an intensity from 1/2 up to 1 biodose. The tendency was still present one month following the termination of UVR course. The total sodium and potassium store in the whole organism of laboratory animals did not practically change either immediately, or 2 weeks, or 1 month after the termination of 10-day UVR course with the intensity from 1/4 to 2 biodoses daily.     

X射线对人肝癌血管内皮细胞迁移的影响及其机制

目的 探讨X射线对人肝癌血管内皮细胞（TEC）迁移的影响并探讨其机制。方法 细胞划痕实验检测TEC细胞迁移能力,实时荧光PCR法检测Plk1 mRNA表达水平,免疫印迹法检测Plk1、STAT3及磷酸化STAT3（p-STAT3Y705）水平。结果 2 Gy X射线照射后24 h TEC迁移距离为（114.37±35.12）像素,对比未受照射TEC迁移距离（78.89±24.67）显著升高（P<0.01）;2 Gy X射线照射后Plk1 mRNA表达水平显著升高（P<0.05）,BI2536抑制Plk1激酶活性后p-STAT3Y705水平降低;2 Gy X射线照射后Plk1和p-STAT3Y705水平显著升高。结论 2 Gy X射线通过Plk1磷酸化STAT3（而非增加STAT3表达水平）来发挥其促进TEC迁移作用。     

Effects of topical and oral vitamin E on pigmentation and skin cancer induced by ultraviolet irradiation in Skh:2 hairless mice

This study investigates whether supplementation with topical RRR-alpha-tocopherol (Eol), topical RRR-alpha-tocopheryl succinate, and oral RRR-alpha-tocopheryl acetate can reduce the incidence of acute and chronic damage to the skin (i.e., sunburn and pigmentation and skin cancer, respectively) induced by ultraviolet (UV) irradiation to mice. Groups of twenty Skh:2 female hairless pigmented mice were treated with 1) lotion vehicle, 2) 5% Eol lotion, 3) 5% topical RRR-alpha-tocopheryl succinate lotion, or 4) lotion vehicle and oral RRR-alpha-tocopheryl acetate. Within each group, 15 mice were exposed to 0.24 J/cm2 of UV-B radiation three times per week. The animals' weights and food intakes were monitored, and the vitamin E concentrations of skin, liver, and adipose tissue were measured to determine whether the topical Eol resulted in significant tissue levels. Skin pigmentation was scored, and the total number of clinically detectable skin tumors per animal was counted weekly. Results showed that the skin concentrations of Eol, as well as levels in the adipose tissue, were increased after topical application. Mice treated with each form of vitamin E showed no signs of toxicity and had significantly less acute and chronic skin damage induced by UV irradiation, as indicated by reduced inflammation and pigmentation and by later onset and lesser incidence of skin cancer.