Influence of dietary menhaden oil upon carcinogenesis and various cutaneous responses to ultraviolet radiation

Abstract Recent reports suggest that eicosapentaenoic acid (EPA) inhibits growth of transplanted tumors and the formation of various chemically induced cancers in animals. Menhaden oil is a source of polyunsaturated lipid with a high content of EPA, an omega-3 fatty acid. We sought to explore the effects of menhaden oil on photocarcinogenesis by employing the hairless mouse/UV-carcinogenesis model. Five groups of 40 SKH-Hr-1 mice received (a) a semipurined equicaloric diet containing either 0.75% corn oil, 4% corn oil. 4% menhaden oil or 12% menhaden oil and (b) an escalating regimen of UV radiation to a cumulative dose of 70 J/cm². Additional animals were employed to further examine the role of menhaden oil in acute cutaneous responses to UV, i.e., erythema, edema, and ornithine decarboxylase (ODC) induction. After a 2-week feeding period UV-induced ODC activity in mice receiving 12 or 20% menhaden oil was 3 to 13-fold lower than that of corn oil fed animals. Further studies showed that edema was also markedly decreased. Animals receiving menhaden oil required twice the level of irradiance to evoke a comparable erythema as that which occurred in corn oil fed animals. Menhaden oil exerted significant influence upon carcinogenic expression, as manifested in significantly longer tumor latent periods and lower tumor multiplicities when compared to corn oil fed animals. Although the mechanism(s) of these menhaden oil effects remains unknown, it is clear that this unique lipid has a pronounced influence upon cutaneous photoresponses. 15th Annual Meeting of the American Society for Photobiology, Bal Harbor, FL, June, 1987.     

Outdoor ultraviolet polychromatic action spectra for growth responses of Bellis perennis and Cynosurus cristatus

Polychromatic ultraviolet (UV) action spectra for various growth responses of the dicotyledon Bellis perennis L. (daisy) and the grass Cynosurus cristatus L. (crested dog's-tail) have been measured. The plants were grown in the natural environment and ambient daylight was supplemented with five different UV irradiances centred at eight different wavelengths (313, 318, 320, 322, 339, 348, 356 and 377 nm). Destructive growth analysis was performed on B. perennis and C. cristatus after 300 and 122 days respectively. Dose response curves were created to construct action spectra for individual responses. Different spectral responses were observed in these two plant types. B. perennis exhibited a substantial action maximum at 313 nm for the inhibition of aerial, root and total dry weight; a similar action maximum at 313 nm for the inhibition of leaf expansion was observed. Longer wavelengths were relatively ineffective on these growth parameters, with the exception of a small but statistically significant (P < 0.05) response to 320 nm radiation. By contrast, C. cristatus showed negligible response to 313 nm radiation, for inhibition of aerial, root and total dry weight but substantial responses to longer wavelengths, especially at 339 and 348 nm. These action spectra add weight to suggestions in the literature that UV-A has a role to play in responses in this region of the spectrum. The possible implications of these observations are discussed.     

Attenuation of DNA damage in the dermis and epidermis of the albino hairless mouse by chronic exposure to ultraviolet-A and -B radiation

Mammalian skin is vulnerable to the photocarcinogenic and photoaging effects of solar UV radiation and defends itself using a variety of photoprotective responses including epidermal thickening, tanning and the induction of repair and antiradical systems. We treated Skh-1 albino hairless mice for 60 days with ultraviolet-A (UVA) or ultraviolet-B (UVB) radiation and measured the frequency of cyclobutane pyrimidine dimers and pyrimidine(6-4)pyrimidone photoproducts induced by a single acute sunburn dose of UVB at different stages of the chronic treatment. We found that both UVA and UVB exposure produced a photoprotective response in the dermis and epidermis and that the degree of photoproduct attenuation was dependent on dose, wavelength and the type of damage induced. Although epidermal thickening was important, our data suggest that UV protective compounds other than melanin may be involved in mitigating the damaging effects of sunlight in the skin.     

Protective effect of sanguinarine on ultraviolet B-mediated damages in SKH-1 hairless mouse skin: implications for prevention of skin cancer

Excessive exposure of solar ultraviolet (UV) radiation, particularly its UVB component (280-320 nm), to human skin is the major cause of skin cancers. UV exposure also leads to the development of precancerous conditions such as actinic keratosis and elicits a variety of other adverse effects such as sunburn, inflammation, hyperplasia, immunosuppression and skin aging. Therefore, there is a need to intensify our efforts towards the development of novel mechanism-based approaches/agents for the protection of UVB-mediated damages. Chemoprevention is being investigated as a potential approach for the management of UV damages including skin cancer. We have earlier shown that sanguinarine, a benzophenanthridine alkaloid, inhibits UVB exposure-mediated damages in HaCaT keratinocytes. In this study, to determine the relevance of our in vitro findings to in vivo situations, we assessed the effects of sanguinarine on UVB-mediated damages in SKH-1 hairless mice. Our data demonstrated that a topical application of sanguinarine (5 micromol 0.3 mL(-1) ethanol per mouse), either as a pretreatment (30 min prior to UVB) or posttreatment (5 min after UVB), resulted in a significant decrease in UVB-mediated increases in skin edema, skin hyperplasia and infiltration of leukocytes. Further, sanguinarine treatments (pre and post) also resulted in a significant decrease in UVB mediated (1) generation of H2O2 and (2) increases in the protein levels of markers of tumor promotion/proliferation viz. ornithine decarboxylase (ODC), proliferating cell nuclear antigen (PCNA) and Kiel antigen-67. Based on this data, we suggest that sanguinarine could be developed as an agent for the management of conditions elicited by UV exposure including skin cancer. However, further detailed studies are needed to support this suggestion.     

Comparison of the action spectra and quantum requirements for photosynthesis and photo-reduction of Scenedesmus

Abstract -The action spectrum and the quantum requirement of photoreduction (P.R) by hydrogen-adapted Scenedesmus have been determined under conditions where photosystem II is inoperative. The action spectrum of P.R., when compared to that of photosynthesis, shows approximately a 20 nm shift in the long wavelength maxima and an apparent decreased utilization of light in the wavelength region 600–650 nm. The quantum requirement for P.R. is high at wavelengths below 650 nm and decreases to a minimum between 705–720 nm; the best value obtained was 10. These observations indicate that this process is exclusively a photosystem I reaction and furthermore offer additional evidence for a lack of appreciable transfer of excitation energy between the pigments of photosystems I and II. The relatively high requirement photophosphorylation or to the inadequacy of H₂-hydrogenase system as the electron donor mechanism for photosystem I.     

Computation of ultraviolet and visible spectra for cobalt acetylacetonate

A computation is made for the Co(acac)₃ molecule by the semiempirical method of Mulliken, Helmholz, and Wolfsberg. The results indicate a high degree of covalence in the metal—ligand bond. Analysis of the obtained system of energy levels and oscillator forces for the possible transitions makes it possible to interpret the 1100 nm and 800 nm bands as transitions from the -orbitals of the carbon atoms in the ortho position to the metal to the d orbitals of the metal; the bands in the 400- to 610-nm region are interpreted as d()-d transitions, which cannot be regarded as pure d-d transitions. The bands in the region below 400 nm are attributed to - transitions. The calculation also shows that in complexes with covalent metal-ligand bonds the levels, to which the main contribution is made by the atomic orbitals of the metal and the directly coordinated atoms, are mixed.     

Similarity in dose responses, action spectra and red light responses between phototropism and photoinhibition of growth.

Abstract— First positive phototropism and photoinhibition of growth of oat colcoptiles share similar dose response curves and action spectra. Both responses increase with increasing dosage of blue light (440 nm) up to 10¹³ photons cm^-2, then both decrease with increasing dosage. Action spectra for both responses have peaks at 360, 440, and 470 nm. When red light (660 nm) was given beforehand, the sensitivity of each response to blue light was lessened. These data indicate a close correlation between phototropism and photoinhibition of growth. Both phenomena can be explained as a result of photoinhibition of basipetal transport of auxin.     

Vacuum ultraviolet mcd and absorption spectra of P4 isolated in an ar matrix using synchrotron radiation

The VUV MCD and absorption spectra of P₄ isolated in an argon matrix were obtained using synchrotron radiation. Four well resolved ¹A₁ → ¹T₂^J transitions are observed (J = A, B, C, D from low to high energy). A Jahn-Teller effect is clearly evident in the ¹T₂^C excited state. The ¹T₂^D excited state contains substantial 3d character.     

Molecular response to ultraviolet radiation exposure in fish embryos: implications for survival and morphological development

UVR exposure is known to cause developmental defects in a variety of organisms including aquatic species but little is known about the underlying molecular mechanisms. In this work we used zebrafish (Danio rerio) embryos as a model system to characterize the UVR effects on fish species. Larval viability was measured for embryos exposed to several UVR spectral treatments by using a solar simulator lamp and an array of UV cutoff filters under controlled conditions in the laboratory. Survival rate and occurrence of development abnormalities, mainly caudal (posterior) notochord bending/torsion, were seriously affected in UV-exposed larvae reaching values of 53% and 72%, respectively, compared with non-UV-exposed larvae after 6 days postfertilization (dpf). In order to elucidate the molecular mechanisms involved, a matricellular glycoprotein named osteonectin and the expression of a DNA-repair related gene, p53, were studied in relation to UVR exposure. The results indicate that osteonectin and p53 expression were increased under UVR exposure due to wavelengths shorter than 335 nm (i.e. mainly UVB) and 350 nm (i.e. short UVA and UVB), respectively. Furthermore, parallel experiments with microinjections of osteonectin-capped RNA showed that malformations induced by osteonectin overexpression were similar to those observed after a UVR exposure. Consequently this study shows a potential role of osteonectin in morphological deformities induced by solar UV radiation in zebrafish embryos.     

Alterations of hairless mouse skin exposed to chronic UV irradiation and its prevention by hydrocortisone

Ultraviolet-induced alterations of skin were investigated in a murine animal model. Groups of hairless mice were exposed to UV (black light, lambda max 352 nm; UV distribution: 300-310 nm, 0.9%; 310-320 nm, 2.0%; 320-420 nm, 97.1%) for 20 weeks at a dose of 16.3 J/cm2 five times weekly on weekdays. At the end of 20 weeks irradiation, the dorsal skins were biochemically and histologically examined. Ultraviolet caused remarkable increases in amounts of hyaluronan, chondroitin sulfates and dermatan sulfates in skin (microgram/cm2). Interestingly, a significant change in a collagen content (hydroxyproline, microgram/g of dry powder) caused by UV irradiation was not observed, whereas the amount of collagen (hydroxyproline, microgram/cm2) increased remarkably. Histologically, no distinguishable thickening was observed in both upper dermis and lower dermis, but thickening of the epidermis was observed. Furthermore, the histological study indicated that UV irradiation caused a disappearance of crowds of adipocytes, alternative appearance of numerous fibroblasts and accumulation of collagen bundles and hyaluronan in lower dermis. Hydrocortisone, an anti-inflammatory agent, prevented both the fibrosis of lower dermis and the accumulation of the extracellular matrix components. Based on these results, it seems reasonable that UV penetrates into the lower dermis and causes fibrosis there, resulting from the inflammatory responses.     

Emission spectra of an argon inductively coupled plasma in the vacuum ultraviolet: background spectra from 85 to 200 nm

The background spectra emitted from an argon ICP discharge have been recorded over the spectral range 85 to 200 nm. These vacuum ultraviolet spectra were acquired by coupling the ICP to a 0.5-m Seya-Namioka vacuum monochromator, through a helium purged side-arm. Background features observed include emission from the resonance lines of ArI, and emission from gas impurities such as oxygen, nitrogen, carbon and hydrogen.     

Induction of primary cutaneous melanomas in C3H mice by combined treatment with ultraviolet radiation, ethanol and aloe emodin

The role of ultraviolet (UV) radiation in the induction of nonmelanoma skin cancer is widely accepted, although its precise contribution to the development of primary cutaneous melanoma skin cancer requires further definition. We found that painting aloe emodin, a trihydroxyanthraquinone from Aloe barbadensis, in ethyl alcohol vehicle on the skin of mice in conjunction with exposure to UVB (280-320 nm) radiation results in the development of melanin-containing skin tumors. C3H/HeN mice were treated thrice weekly with aloe emodin in a 25% ethanol in water vehicle and exposed to 15 kJ/m2 UV radiation. Neither ethanol vehicle nor aloe emodin alone induced skin tumors in the absence of UV radiation. In two separate experiments, 20-30% of the mice treated with a combination of UV radiation and ethanol vehicle and 50-67% of the UV-irradiated animals given aloe emodin in ethanol vehicle developed primary cutaneous melanin-containing tumors. The diagnosis of melanoma was established using Fontana silver stain for melanin; these tumors were negative for vimentin and keratin. Melanin-containing melanosomes were observed by transmission electron microscopy in tumors diagnosed as melanomas. Although the mechanism of carcinogenesis in these mice is currently unknown, our findings have led to the development of the first facile murine model for the induction of primary melanoma. This model has the potential to clarify the role of UV radiation in the etiology of malignant melanoma.     

Estimating attenuation of ultraviolet radiation in streams: field and laboratory methods

We adapted and tested a laboratory quantitative filter pad method and field-based microcosm method for estimating diffuse attenuation coefficients (K(d)) of ultraviolet radiation (UVR) for a wide range of stream optical environments (K(d320) = 3-44 m(-1)). Logistical difficulties of direct measurements of UVR attenuation have inhibited widespread monitoring of this important parameter in streams. Suspended sediment concentrations were manipulated in a microcosm, which was used to obtain direct measurements of diffuse attenuation. Dissolved and particulate absorption measurements of samples from the microcosm experiments were used to calibrate the laboratory method. Conditions sampled cover a range of suspended sediment (0-50 mg L(-1)) and dissolved organic carbon concentrations (1-4 mg L(-1)). We evaluated four models for precision and reproducibility in calculating particulate absorption and the optimal model was used in an empirical approach to estimate diffuse attenuation coefficients from total absorption coefficients. We field-tested the laboratory method by comparing laboratory-estimated and field-measured diffuse attenuation coefficients for seven sites on the main stem and 10 tributaries of the Lehigh River, eastern Pennsylvania, USA. The laboratory-based method described here affords widespread application, which will further our understanding of how stream optical environments vary spatially and temporally and consequently influence ecological processes in streams.     

Plant responses to current solar ultraviolet-B radiation and to supplemented solar ultraviolet-B radiation simulating ozone depletion: an experimental comparison

Field experiments assessing UV-B effects on plants have been conducted using two contrasting techniques: supplementation of solar UV-B with radiation from fluorescent UV lamps and the exclusion of solar UV-B with filters. We compared these two approaches by growing lettuce and oat simultaneously under three conditions: UV-B exclusion, near-ambient UV-B (control) and UV-B supplementation (simulating a 30% ozone depletion). This permitted computation of "solar UV-B" and "supplemental UV-B" effects. Microclimate and photosynthetically active radiation were the same under the two treatments and the control. Excluding UV-B changed total UV-B radiation more than did supplementing UV-B, but the UV-B supplementation contained more "biologically effective" shortwave radiation. For oat, solar UV-B had a greater effect than supplemental UV-B on main shoot leaf area and main shoot mass, but supplemental UV-B had a greater effect on leaf and tiller number and UV-B-absorbing compounds. For lettuce, growth and stomatal density generally responded similarly to both solar UV-B and supplemented UV-B radiation, but UV-absorbing compounds responded more to supplemental UV-B, as in oat. Because of the marked spectral differences between the techniques, experiments using UV-B exclusion are most suited to assessing effects of present-day UV-B radiation, whereas UV-B supplementation experiments are most appropriate for addressing the ozone depletion issue.     

Synergetic effect of the action of atomic oxygen and vacuum ultraviolet radiation on polymers in the Earth’S ionosphere

A procedure for the bench-test simulation of the physicochemical interactions of polymers with flows of atomic oxygen and vacuum ultraviolet radiation in the ionosphere of the Earth has been developed. The threshold values of the ratios of the vacuum ultraviolet flux density to the flux of atomic oxygen, which characterize the synergistic effect on the ablation of polymers (the polyimides Kapton-H and PM-1E, polyethylene, and Teflon 100A) have been obtained.     

Photoreactivation of killing in Streptomyces: action spectra and kinetic studies

Abstract— An action spectrum was obtained for photoreactivation of killing (PR) of Streptomyces griseus conidia. This spectrum shows a major peak around 436 nm, originally observed by A. Kelner, and a secondary peak at 313 nm not previously reported. The rate of PR shows a strong dependence upon temperature and dose rate of the PR light at 436 nm, but this decreases to only a slight dependence upon these parameters at 313 nm. These findings suggested that PR at 436 nm in this organism is of the usual photoenzymatic type, but that PR at 313 nm might be of a different kind. A mutant (PHR-1) of S. griseus was found that shows only a narrow range of PR (roughly 310–400 nm) with a single peak at 313 nm. The PR efficiency was lower than for wild type and the PR sector not greater than one-half that of wild type. This PR shows no temperature dependence. Essentially similar behavior was observed with wild-type Streptomyces coelicolor. These findings show that at least some of the PR at 313 nm is a separable phenomenon. It is therefore unlikely to involve a mechanism identical to that at 436 nm. The nature of PR at 313 nm in Streptomyces is not known. If it is enzymatic, it is remarkable in having little or no dependence upon temperature and dose rate. Absence of photoprotection and liquid-holding recovery indicate that it is not indirect PR. Some of it (that part exhibited by S. griseus PHR-1 and S. coelicolor) might result from a direct photochemical action on DNA.