SUPPRESSION OF CONTACT HYPERSENSITIVITY BY UV RADIATION AND ITS RELATIONSHIP TO UV-INDUCED SUPPRESSION OF TUMOR IMMUNITY

Abstract— In this study, we examine some of the photobiologic and immunologic characteristics of the suppression of contact hypersensitivity (CHS) by UV radiation. BALB/c mice were irradiated on the shaved dorsal skin with FS40 sunlamps and sensitized 5 days later by applying a contact sensitizer lo the shaved abdomen. The suppression of CHS resulting from exposure to a given total dose of UV radiation was unaffected by changes in dose fractionation over a 5-day period and by changes in dose-rate over a 10-fold range. Elimination of wavelengths below 315 nm with a mylar filter abrogated the suppressive effect of the sunlamps, even when the same total energy was administered. Irradiation of unshaved mice required 14 times more energy to produce 50% suppression than was required for shaved mice, suggesting that the exposed skin is the primary target of this effect. Contact sensitization of UV-irradiated, but not unirradiated, mice induced the appearance of antigen-specific suppressor T lymphocytes in their spleen. The photobiologic and immunologic similarities between the suppression of CHS by UV radiation and the UV-mediated suppression of tumor rejection that we described previously suggest that these two immunosuppressive effects of UV exposure share certain steps in their pathways.     

Deuterodehalogenation—a mild method for synthesising deuterated heterocycles

We report a mild and efficient method for introducing deuterium into a range of heterocycles by reacting readily available halide analogues in a deuterodehalogenation reaction using D₈-IPA or Et₃SiD under palladium-catalysed conditions.     

Tuning Thiophene with Phosphorus: Synthesis and Electronic Properties of Benzobisthiaphospholes

1,4‐Dimercapto‐2,5‐diphosphinobenzene and 3,6‐bis(hexyloxy)‐1,4‐dimercapto‐2,5‐diphosphinobenzene were synthesized and combined with various acid chlorides to obtain a series of benzobisthiaphospholes. Electrochemical and photophysical properties of the substituted benzobisthiaphospholes have been evaluated, and the observed reductions are more facile than the related benzothiaphospholes and 2,6‐diphenylbenzobisthiazole. A benzobisthiaphosphole with C₆H₄‐p‐CN substituents was reduced at E_1/2=?1.08 V (vs. saturated calomel electrode (SCE)). X‐ray diffraction data for several of these phosphorus heterocycles has been obtained, and DFT calculations at the B3LYP level have been performed.     

Synthesis of [18F]F-γ-T-3, a Redox-Silent γ-Tocotrienol (γ-T-3) Vitamin E Analogue for Image-Based In Vivo Studies of Vitamin E Biodistribution and Dynamics

Vitamin E, a natural antioxidant, is of interest to scientists, health care pundits and faddists; its nutritional and biomedical attributes may be validated, anecdotal or fantasy. Vitamin E is a mixture of tocopherols (TPs) and tocotrienols (T-3s), each class having four substitutional isomers (α-, β-, γ-, δ-). Vitamin E analogues attain only low concentrations in most tissues, necessitating exacting invasive techniques for analytical research. Quantitative positron emission tomography (PET) with an F-18-labeled molecular probe would expedite access to Vitamin E’s biodistributions and pharmacokinetics via non-invasive temporal imaging. (R)-6-(3-[¹⁸F]Fluoropropoxy)-2,7,8-trimethyl-2-(4,8,12-trimethyltrideca-3,7,11-trien-1-yl)-chromane ([¹⁸F]F-γ-T-3) was prepared for this purpose. [¹⁸F]F-γ-T-3 was synthesized from γ-T-3 in two steps: (i) 1,3-di-O-tosylpropane was introduced at C6-O to form TsO-γ-T-3, and (ii) reaction of this tosylate with [¹⁸F]fluoride in DMF/K₂₂₂. Non-radioactive F-γ-T-3 was synthesized by reaction of γ-T-3 with 3-fluoropropyl methanesulfonate. [¹⁸F]F-γ-T-3 biodistribution in a murine tumor model was imaged using a small-animal PET scanner. F-γ-T-3 was prepared in 61% chemical yield. [¹⁸F]F-γ-T-3 was synthesized in acceptable radiochemical yield (RCY 12%) with high radiochemical purity (>99% RCP) in 45 min. Preliminary F-18 PET images in mice showed upper abdominal accumulation with evidence of renal clearance, only low concentrations in the thorax (lung/heart) and head, and rapid clearance from blood. [¹⁸F]F-γ-T-3 shows promise as an F-18 PET tracer for detailed in vivo studies of Vitamin E. The labeling procedure provides acceptable RCY, high RCP and pertinence to all eight Vitamin E analogues.     

Melt rheology of ion-containing polymers. I. Effect of ionic content in a model polyesterionomer

The effects of copolymerizing small amounts of an ionic moiety (0–7 mol %) into the backbone of a polycondensation polymer have been investigated by a combination of linear viscoelastic, steady-shear, and extensional testing. At a constant viscosity in dilute solution, both the zero-shear-rate viscosity and the maximum relaxation time in the melt increase monotonically with an increase in the ionic character. These effects are present after the data are normalized to remove the increase in the glass transition temperature T_g with increased ionic content. Large-strain, steady-shear flow experiments showed that the viscoelastic memory of the melt is affected by ionic content. An increase in ion content causes a decrease in the effect of strain on the memory function. This effect is not apparent in extensional flow experiments, which indicate that the ionic content does not affect the response if the tests are conducted at a constant temperature above T_g.     

Highly efficient blue-light generation from a compact, diode-pumped femtosecond laser by use of a periodically poled KTP waveguide crystal

We present a simplified, potentially portable, and highly efficient blue-light source from a periodically poled KTP waveguide crystal with a compact femtosecond Cr:LiSAF laser. This light source generates 5.6 mW of blue average output power at 424 nm with 27 mW of incident fundamental in a single-pass extracavity arrangement at room temperature. The overall system efficiency of electrical power to blue light is 0.5%, and the internal second-harmonic generation conversion efficiency is as high as 37%. The slope efficiency of 5.5% pJ(-1) at low pulse energies is, to our knowledge, the highest slope efficiency yet reported for frequency conversion into the blue spectral region.     

Gas chromatographic determination of gallopamil and norgallopamil in human plasma

A highly sensitive gas chromatographic assay is described for the simultaneous determination of gallopamil, a calcium channel blocking agent, and its major metabolite, norgallopamil. A multi-step extraction procedure is employed followed by on-column capillary gas chromatographic analysis using nitrogen-selective detection. Acetylation of norgallopamil is performed to enable accurate quantification of the metabolite. Linearity was achieved over the range 1-50 ng/ml for both analytes. Assay specificity, precision and accuracy were investigated.