Differential roles of T-cell subsets in regulation of ultraviolet radiation induced cutaneous photocarcinogenesis

Ultraviolet (UV) radiation, in particular the midwavelength range (UVB; 290-320 nm), is one of the most significant risk factors for the development of nonmelanoma skin cancer. UVB radiation-induced immunosuppression, which occurs in both humans and laboratory animals, contributes to their pathogenesis. However, there are conflicting reports on the relative role of CD4(+) and CD8(+) T cells in UVB induced skin cancer. The purpose of this study was to delineate the contribution of these two cell subpopulations to UVB induced immunosuppression and tumor development using C3H/HeN (WT), CD4 knockout (CD4(-/-) ) and CD8 knockout (CD8(-/-) ) mice. We observed that UVB induced skin carcinogenesis was retarded in terms of number of tumors per group, tumor volume and percentage of mice with tumors, in mice deficient in CD4(+) T cells compared with wild-type mice, whereas significantly greater (P < 0.05) numbers of tumors occurred in CD8(-/-) mice. These results indicate that, CD4(+) T cells promote tumor development while CD8(+) T cells have the opposite effect. Further, we found that CD4(+) T cells from tumor-bearing mice produced interleukin (IL)-4, IL-10, and IL-17 whereas CD8(+) T cells produced interferon-γ. Manipulation of T-cell subpopulations that are induced by UVB radiation could be a means of preventing skin cancers caused by this agent.     

Effect of plasticizer on structural and electrical properties of nanocomposite solid polymer electrolytes

The solid polymer electrolyte films based on polyethylene oxide, NaClO₄ with dodecyl amine modified montmorillonite as filler, and polyethylene glycol as plasticizer were prepared by a tape casting method. The effect of plasticization on structural, microstructural, and electrical properties of the materials has been investigated. A systematic change in the structural and microstructural properties of plasticized polymer nanocomposite electrolytes (PPNCEs) on addition of plasticizer was observed in our X-ray diffraction pattern and scanning electron microscopy micrographs. Complex impedance analysis technique was used to calculate the electrical properties of the nanocomposites. Addition of plasticizer has resulted in the lowering of the glass transition temperature, effective dissociation of the salt, and enhancement in the electrical conductivity. The maximum value of conductivity obtained was ∼4.4 × 10⁻⁶ S cm⁻¹ (on addition of ∼20% plasticizer), which is an order of magnitude higher than that of pure polymer nanocomposite electrolyte films (2.82 × 10⁻⁷ S cm⁻¹). The enhancement in conductivity on plasticization was well correlated with the change in other physical properties.     

Raman spectroscopy of BaTiO3/(Ba,Sr)TiO3 superlattices

A series of BaTiO₃/Ba_{1 ? x} Sr _x TiO₃ (BT/BST) superlattices were prepared by pulsed laser deposition on MgO substrates with a constant period of 80 Å (40 Å BT and 40 Å BST) and varying compositions of the BST layer so that the Ba/Sr concentration ratios were 0/100, 30/70, 40/60, 50/50, 60/40, 70/30, 100/0. The soft mode E(1TO) of the polarized Raman spectra transformed depending on the Ba/Sr ratio in the BST layer. As the Sr concentration in the BST layers increased from 0 to 100%, the E(1TO) soft mode half-width varied from 171 to 103 cm^?1 and its frequency increased from 31 to 109 cm^?1 due to the interaction between the epitaxial layers forming the superlattices.     

Structural studies and Raman spectroscopy of forbidden zone boundary phonons in Ni‐doped ZnO ceramics

We present X‐ray diffraction and Raman spectroscopy studies of Ni‐doped ZnO (Zn_1−xNi_xO, x = 0.0, 0.03, 0.06, and 0.10) ceramics prepared by solid‐state reaction technique. The presence of the secondary phase along with the wurtzite phase is observed in Ni‐doped ZnO samples. The E₂(low) optical phonon mode is seen to be shifted to a lower wavenumber with Ni incorporation in ZnO and is explained on the basis of force‐constant variation of ZnO bond with Ni incorporation. A zone boundary phonon is observed in Ni‐doped samples at ∼130 cm⁻¹ which is normally forbidden in the first‐order Raman scattering of ZnO. Antiferromagnetic ordering between Ni atoms via spin‐orbit mechanism at low temperatures (100 K) is held responsible for the observed zone boundary phonon. Copyright © 2008 John Wiley & Sons, Ltd.     

Spectrophotometric titration of bismuth with EDTA

A new spectrophotometnc method for the estimation of bismuth with EDTA, using iron-salicylate complex as the indicator, has been developed. The determinations were carried out by measuring the absorbance at 520 mmu. of solutions containing bismuth, iron(III), salicylic acid and various quantities of EDTA, at pH 0.5. It has been shown from the stability constants of the complexes present that before the end-point iron(III) will not react appreciably with the Bi-EDTA complex. The interference from iron(III) in the estimation of bismuth, which is a serious drawback in many other methods, is eliminated in the present method, as iron(III) acts as the indicator.     

Development of HPTLC detection of synthetic pesticide carbosulfan in biological material

JPC – Journal of Planar Chromatography – Modern TLC - The field of agriculture is the key role in Indian society in which insecticides play a vital role in increasing the crop...     

Crosstalk Among UV‐Induced Inflammatory Mediators,DNA Damage and Epigenetic Regulators Facilitates Suppression of the Immune System

The suppression of the immune system by overexposure to ultraviolet (UV) radiation has been implicated in the initiation and progression of photocarcinogenesis. Numerous changes occur in the skin on UVB exposure, including the generation of inflammatory mediators, DNA damage, epigenetic modifications, and migration and functional alterations in the antigen‐presenting dendritic cells. Although each of these alterations can elicit a cascade of events that have the potential to modulate immune sensitivity alone, there is emerging evidence that there is considerable crosstalk between these cascades. The development of an understanding of UV‐induced changes in the skin that culminate in UV‐induced immunosuppression, which has been implicated in the risk of nonmelanoma skin cancer, as a network of events has implications for the development of more effective chemopreventive strategies. In the current review article, we discuss the evidence of interactions between the various molecular targets and signaling mechanisms associated with UV‐induced immunosuppression.     

New bioactive hydrogenated linderazulene-derivatives from the gorgonian Echinogorgia complexa

Chemical analysis of the secondary metabolite pattern of the gorgonian Echinogorgia complexa, collected along South Indian coasts, showed the presence of two new tricyclic guaiane furanosesquiterpenes, iso-echinofuran (3) and 8,9-dihydro-linderazulene (4), co-occurring with the known echinofuran (5) and structurally related to the pigment linderazulene (1). The unprecedented molecules 3 and 4 were characterized by spectral methods, mainly by NMR techniques. Compounds 3-5 displayed moderate activity in the mitochondrial respiratory chain inhibition assay.     

Untersuchungen über die Molekel-Assoziation unter Beteiligung von Wasserstoff-Bindungen. 2. Mitt.

Ohne Zusammenfassung     

Analysis of electro-optical and dielectric parameters of TiO2 nanoparticles dispersed nematic liquid crystal

The present investigation is focused on to find out the role of TiO₂ nanoparticles (NPs) on altering the dielectric and electro-optical parameters of nematic liquid crystal (NLC). In addition to this, we also optimized the concentration of dopant (0.25 wt%) for a saturation value of permittivity and dielectric anisotropy in the doped system. Dielectric spectroscopy has been performed with the variation of frequency and temperature to investigate the various dielectric parameters, which demonstrate that the investigated NLC is of positive dielectric anisotropy; the observed result shows a decrement in the value of relative permittivity and dielectric anisotropy; however, the permittivity value increases for higher concentration of dopant but remains less than that of pure NLC. Electro-optical measurements have also been performed to compute the optical response of pure and dispersed NLC. It is found that optical response decreases for the NP-doped systems. This optimized concentration of NPs in NLC matrix can have various credential applications in the field of active matrix display and holography.