An Animal Model for Human Melanoma

Abstract— Experimental animal models that are directly relevant to human melanoma are lacking. We propose the Angora goat as a potentially useful field model with experimental potential and to this end have examined the prevalence and site distribution of all skin cancers in 28 Angora goat herds in Queensland, Australia. The prevalence of benign melanocytic lesions (lentigines) and their experimental induction by sunlight were also investigated. Among 1731 goats over 2 years of age, 139 malignant skin tumors were excised from 95 affected animals. The prevalence of squamous cell carcinoma (SCC) was 3.8% and of melanoma, 2.2%. Main site of occurrence of melanoma (83%) was the dorsal surface of the ear; in contrast SCC occurred mostly (84%) on the perineum. Lentigines were darker and more prevalent on the exposed compared with the unexposed surface of the ear in Angoras, analogous to the higher prevalence of nevi on the exposed compared with the less exposed inner surface of the arm in humans. Lentigines, which were also found on the perineum though lighter in color than on the dorsal ear, were absent in young animals under 3 months but were numerous in 1–3 year olds. Furthermore in an experimental substudy eight goats, having one flank repeatedly shorn and the contralateral flank left unshorn, revealed consistently more solar lentigines on the shorn flank ( P < 0.05) when both sides were examined after 9 months. Histopathological examination of paired skin biopsies from five of these goats also showed more abundant pigmentation in skin from the exposed, as compared with the unexposed flank. These findings indicate that sunlight induces tumors and lentigines in goats in a highly site-specific manner. The Angora goat model may suggest paradigms for explaining the site differences observed for human melanoma and may also be useful in the future clarification of molecular changes following carcinogenic levels of sun exposure.     

A rheological investigation of the self-assembly and adsorption behavior of a surfactant salt

The properties of a surfactant salt obtained by neutralizing oleic acid with an ethoxylated stearylamine were determined in blends of water and propylene glycol. The adsorption of this surfactant salt onto the surface of a commercial TiO(2) dispersed in blends of water and propylene glycol was studied using a rheometer. At low propylene glycol content the dispersions exhibited Newtonian behavior, but became shear-thinning fluids with high viscosity at propylene glycol contents above a critical concentration. The observed behavior is consistent with a model involving a surfactant bilayer below the critical point, moving to a monolayer above the critical point. The high viscosity above the critical point is generated by reversible flocculation via hydrophobic forces. The viscosity of the dispersion flocculated by the hydrophobic forces was found to be much higher than that caused by flocculation via van der Waals forces in the absence of surfactant. Changing both the total concentration of the surfactant in the dispersion and the dispersion temperature resulted in a reversible transition between the bilayer and the monolayer. Although the surfactant was always above its critical micelle concentration (CMC) the amount on the particle surface varied appreciably with both propylene glycol and surfactant concentration.     

[(1,4,8,11‐Tetraazacyclotetradeca‐1,4,8,11‐tetrayl)tetraacetamide‐κ6N1,N4,N8,N11,O1,O8]copper(II) sulfate 4.5‐hydrate

The crystal structure of the title copper(II) complex, [Cu(C₁₈H₃₆N₈O₄)]SO₄·4.5H₂O, formed with the tetra­amide cyclam derivative 2‐(4,8,11‐triscarbamoyl­methyl‐1,4,8,11‐tetra­aza­cyclo­tetradec‐1‐yl)­acet­amide (TETAM), is described. The macrocycle lies on an inversion centre occupied by the hexacoordinated Cu atom. The four macrocyclic tertiary amines form the equatorial plane of an axially Jahn–Teller elongated octahedron. Two O atoms belonging to two diagonally opposite amide groups occupy the apical positions, giving rise to a trans‐III stereochemistry, while both the remaining pendant side arms extend outwards from the macrocyclic cavity and are engaged in hydrogen bonds with sulfate anions and co‐crystallized water mol­ecules.     

Preparation and Characterization of a New Ternary Chromium(III)–Molybdenum(VI) Oxide Cr2–2xMoxO3

A new mixed oxide was prepared by coprecipitation of Cr(NO₃)₃and (NH₄)₆Mo₇O₂₄from aqueous solution and subsequent calcination. The ternary oxide with the general stoichiometry Cr_2–2xMo_xO₃was characterized by X-ray diffraction (XRD), thermoanalysis (TA), energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), atomic absorption spectroscopy (AAS), and Raman scattering. The new oxide showed the typical temperature-dependent electric conductivity known for semiconductors. The structure was refined with the Rietveld method from powder diffraction data. It is strongly related to the hexagonal chromiumsesquioxide structure. Preliminary catalytic experiments revealed a low combustion rate for methane but an increasing preference for C–C coupling reactions with higher Mo content.     

Metal ion doped polymers as media for optical memories

Polymer materials are making an impact on optical storage technology to develop high information density and fast access type memories with a high read-out efficiency. The principle and advantages of three-dimensional (3-D) data storage in the form of interference patterns (holograms) have been outlined. Three different information storage materials have been developed by doping metal ions such as Cr(VI) and Fe(III) in water-soluble polymers, namely poly(vinyl alcohol) (PVA) and poly(acrylic acid) (PAA), which need no further thermal or chemical treatment. Volume transmission holograms have been recorded in dichromated poly(vinyl alcohol) (DCPVA), ferric chloride doped poly(vinyl alcohol) (FePVA) and dichromated poly(acrylic acid) (DCPAA), with and without an electron donor (dimethyl formamide), and xanthene dyes (fluorescein, eosin Y and Rose Bengal). Different parameters influencing the holographic performance have been optimized to achieve a high real-time diffraction efficiency (～70%). An electron transfer process from the polymer matrix to Cr(VI)/Fe(III), leading to the photocrosslinking of the polymer in the form of an interference pattern, has been suggested as the mechanism of information storage (hologram recording) in these materials.     

On corrole chemistry. An isomerization study and oxidative cleavage of the corrole macroring to a biliverdin structure

In the present paper, we report the synthesis of free 5- and 10-monophenylcorroles, 4 and 3 respectively as well as the first example of molecular oxygen oxidation of the corrole macrocycle identified as an open chain tetrapyrrole (biliverdin) structure 7 . Reaction of 1 and 2 in acetic acid leads to a mixture of two a,c-biladienes 3b and 4b and therefore to a mixture of two corrole isomers 3 and 4 . Reaction of 1 and 2 in trifluoroacetic acid leads only to the symmetrical corrole isomer 3 in 41% yield.     

Activity and osmotic coefficients oft-butylammonium chloride; Activity coefficients of HCl in mixtures with tris hydrochloride ort-butylammonium chloride at 25°C

In an earlier study, the activity coefficients of aqueous mixtures of HCl with the hydrochlorides of tris(hydroxymethyl)aminomethane (Tris) ort-butylamine (t-B) were determined at ionic strengths of 0.1, 0.5, and 1.0 mol-kg^–1. The work has been extended to ionic strengths of 2.0 and 3.0 through emf measurements with hydrogen and AgCl/Ag electrodes at 25°C. The results are considered in terms of Harned's rule and the Pitzer and Rush-Johnson-Scatchard treatments of activity coefficients in electrolyte mixtures. In order to compare ionic interaction parameters in the two systems, the activity coefficients and osmotic coefficients of t-butylammonium chloride at molalities up to saturation (7.14 mol-kg^–1) were determined by the gravimetric isopiestic method with solutions of NaCl as reference. The behavior for both systems can be accounted for satisfactorily in terms of binary (H⁺–N⁺) and ternary (H⁺–N⁺–Cl^–) interactions, where N⁺ is either Tris·H⁺ or t-B·H⁺.     

Regioselective Alkylation of the Polyfunctional Nucleophile 1-(Methylthio)-3-triethylsilyloxypentadienyllithium

γ-Selective sulfenylation of the triethysilyloxypentadienyllithium 1 gave the versatile alkylthiodene 4 which on successive deprotonation and alkylation furnished with high regioselectivity the γ-products 6 . Fluoride-promoted silylether cleavage 6 → 7 may be followed by intramolecular [4 + 2]-addition 7c → 8 and sulfoxide elimination 8 → 9 . The conversions 7b → 12 and 7a → 17 demonstrate the feasibility of 5 to serve as an equivalent of the hypothetical β-deprotonated divinylketone 13 whose two enone units may be unmasked separately.     

A comparison of the Kjeldahl and Dumas methods for the determination of protein in foods,using data from a proficiency testing scheme

Both the Kjeldahl and the Dumas methods for the determination of protein in foodstuffs are currently in use, but the empirical nitrogen factors used to convert the determined nitrogen content to protein content are based on the Kjeldahl method alone. Non-equivalence between the two methods could therefore result in some laboratories reporting an incorrect protein content. We report here a study using data accumulated over several years in the results of a proficiency testing scheme. On average the Dumas method provided results that were relatively higher by about 1.4% than the Kjeldahl method, but the difference between the methods depended on the type of foodstuff. The methodology of looking for bias between analytical methods is critically discussed.