Skin chemical carcinogenesis

Video Recording Can Conveniently Assay Mosquito Locomotor Activity

Anopheles gambiae and Aedes aegypti are perhaps the best studied mosquito species and important carriers of human malaria and arbovirus, respectively. Mosquitoes have daily rhythms in behaviors and show a wide range of activity patterns. Although Anopheles is known to be principally nocturnal and Aedes principally diurnal, details of mosquito activity are not easily assayed in the laboratory. We recently described FlyBox, a simple tracking system for assaying Drosophila locomotor activity rhythms and thought that it might also be applicable to monitoring mosquito activity. Indeed, we show here that FlyBox can easily, conveniently, affordably and accurately measure the activity of Anopheles as well as Aedes over several days. The resulting profiles under light-dark as well as constant darkness conditions are compatible with results in the literature, indicating that this or similar systems will be useful in the future for more detailed studies on a range of insect species and under more diverse laboratory conditions.

Investigating Therapeutic Potential of Trigonella foenum-graecum L. as Our Defense Mechanism against Several Human Diseases

Current lifestyle, stress, and pollution have dramatically enhanced the progression of several diseases in human. Globally, scientists are looking for therapeutic agents that can either cure or delay the onset of diseases. Medicinal plants from time immemorial have been used frequently in therapeutics. Of many such plants, fenugreek is one of the oldest herbs which have been identified as an important medicinal plant by the researchers around the world. It is potentially beneficial in a number of diseases such as diabetes, hypercholesterolemia, and inflammation and probably in several kinds of cancers. It has industrial applications such as synthesis of steroidal hormones. Its medicinal properties and their role in clinical domain can be attributed to its chemical constituents. The 3 major chemical constituents which have been identified as responsible for principle health effects are galactomannan, 4-OH isoleucine, and steroidal saponin. Numerous experiments have been carried out in vivo and in vitro for beneficial effects of both the crude chemical and of its active constituent. Due to its role in health care, the functional food industry has referred to it as a potential nutraceutical. This paper is about various medicinal benefits of fenugreek and its potential application as therapeutic agent against several diseases.

Nordihydroguiaretic acid attenuates skin tumorigenesis in Swiss albino mice with the condition of topical co-administration of an immunosuppressant

Drug and chemically-induced immunosuppression has been implicated as a confounding factor for cancer development. Management of cancer in such situation is often a challenging task. We tested the efficacy of nordihydroguiaretic acid (NDGA) against immunosuppressant tacrolimus-induced augmentation of mouse skin tumorigenesis. It was observed that topical administration of tacrolimus significantly accelerated the tumor promotion events in dimethylbenz(a)anthracene (DMBA)-initiated and 12-O-tetradecanoylphorbol-13-acetate (TPA) promoted two-stage mouse skin carcinogenesis, which were accompanied by reduced CD4(+)/CD8(+) ratio of lymph nodes and serum IL-2 level. NDGA pre-treatment before each TPA application reduced the tumor incidence, its multiplicity and volume together with improvement in histopathological alterations and decrease in proliferating cell nuclear antigen (PCNA) labeling index (LI). However, NDGA had no significant influence on the immunosuppressive effect of tacrolimus. The present study demonstrates chemopreventive effect of NDGA in normal as well as in the condition of immunosuppression. Thus, NDGA has the potential to inhibit or delay the onset of tumor development during immunosuppressive regimen.

[Modern light protection from the view of occupational dermatology]

UV-light induced skin cancer is being more and more accepted in Germany as an occupational disease for several jobs with increased UV-light exposure. Over the past 100 years sunscreens with filters against UVB- and UVA-light have been developed. Another development is the use of antioxidants such as vitamin E, vitamin C and herbal agents for additional photoprotection. The evidence supporting these products in their topical and systemic formulation is very variable. The recent changes in the recognition of UV-induced skin cancers as occupational diseases increases the need for preventive strategies which are supported by appropriate clinical studies.

Chemopreventive effect of Vitis vinifera extract on 12-O-tetradecanoyl-13-phorbol acetate-induced cutaneous oxidative stress and tumor promotion in murine skin

Vitis vinifera (grapes) is used as a fruit worldwide and known for its pharmacological properties. The present paper assesses the chemopreventive potential of Vitis vinifera against 12-O-tetradecanoyl-13-phorbol acetate (TPA)-mediated tumor promotion in 7,12-dimethyl-benz[a]anthracene (DMBA) initiated mice skin. Skin tumor initiation was achieved by a single topical application of DMBA (40 microg/animal/0.20 ml acetone) to mice. Two weeks after the initiation, promoting agent, TPA (5.0 microg/animal/0.2 ml acetone) was applied two times a week for 20 weeks. Pretreatment of Vitis vinifera 1h prior to each application of TPA resulted in protection against cutaneous tumorigenesis in dose-dependent manner. This inhibition was evident when tumor data was considered as the percentage of mice with tumor and the number of tumors per mouse. We have shown that typical application of Vitis vinifera prior to that of TPA resulted in significant inhibition against TPA-caused induction of epidermal ODC activity (P<0.001) and DNA synthesis. Application of Vitis vinifera at a dose level of 5.0 mg and 10.0 mg kg(-1) body weight in acetone prior to that of TPA treatment resulted in partial significant inhibition of oxidative stress in dose-dependent manner. The concomitant increase in the microsomal lipid peroxidation and xanthine oxidase activities were significantly reduced (P<0.001). In addition, the depleted level of glutathione and inhibited activities of antioxidant enzymes were recovered to the partial significant level. Hence, it can be suggested that Vitis vinifera can be used as a chemopreventive agent against oxidative stress and carcinogenesis.

Inhibitory effect of Hibiscus protocatechuic acid on tumor promotion in mouse skin

Hibiscus protocatechuic acid (PCA), a phenolic acid isolated from Hibiscus sabdariffa L., was evaluated for its ability to inhibit the 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced promotion in skin tumors of female CD-1 mice. Topical application of PCA (5, 10 or 20 micromol) 5 min prior to TPA (15 nmol) treatment twice weekly for 20 weeks to mice which were initiated with benzo[a]pyrene (B[a]P) inhibited the incidence of tumors in mice to 81.3, 62.5 and 56.3%, respectively, while all mice in the TPA-treated group developed tumors. The average number of tumors in mice pretreated with PCA was 2-4 and that of mice treated only with TPA was 6.6. The protection effects of PCA were also presented by its significant suppression on the TPA-induced hyperplasia in the skin and edema of mouse ears by 65 and 73% at doses of 10 and 20 micromol, respectively. When it was applied to the dorsal surface of CD-1 mice before TPA application, PCA (5, 10 or 20 micromol) inhibited the induction of epidermal ornithine decarboxylase (ODC) activity by 5 nmol TPA and myeloperoxidase (MPO) activity by 6.5 nmol TPA. The same doses of PCA also reduced the formation of hydrogen peroxide in the mouse skin to an inhibition of 61, 84 and 89%, respectively, when compared with that of the TPA-treated group. These results indicate that PCA possesses potential as a cancer chemopreventive agent against tumor promotion.

Identification of a novel cis-acting negative regulatory element affecting expression of the CYP1A1 gene in rat epidermal cells

Polycyclic aromatic hydrocarbons such as 3-methylcholanthrene are toxic to rat epidermal cells in low passages (3 to 6), but cultures of high passage (>/=15) are resistant. Since such compounds can be metabolically activated by cytochrome P4501A1, we have examined the regulation of this gene in low and high passage cells. Consistent with this difference, little or no 2,3,7, 8-tetrachlorodibenzo-p-dioxin (TCDD)-inducible P4501A1 mRNA or enzyme activity was observed in high passage as compared to low passage cultures. Similarly, transfection of a luciferase reporter construct containing -1317 to +256 base pairs of the 5'-flanking region of the murine CYP1A1 gene was TCDD-inducible in low but not high passage cells. Ligand binding and transfection experiments demonstrated the presence of functional Ah receptor complexes in both high and low passage cells. Deletion analysis identified a 26-base pair negative regulatory DNA (NeRD) element contained within the upstream regulatory region of the CYP1A1 gene responsible for this effect. Nuclear extracts from both low and high passage cells contain a protein which specifically binds to NeRD-containing DNA. Thus, the loss of polycyclic aromatic hydrocarbon sensitivity in high passage rat epidermal cells appears to be due to decreased expression of CYP1A1, and this effect may be mediated by an altered NeRD binding factor(s) present in these cells.