Skin Exposure to Ultraviolet B Rapidly Activates Systemic Neuroendocrine and Immunosuppressive Responses

The back skin of C57BL/6 mice was exposed to a single 400 mJ cm^?2 dose of ultraviolet B (UVB), and parameters of hypothalamic–pituitary–adrenal (HPA) axis in relation to immune activity were tested after 30–90 min following irradiation. Levels of brain and/or plasma corticotropin‐releasing hormone (CRH), β‐endorphin, ACTH and corticosterone (CORT) were enhanced by UVB. Hypophysectomy had no effect on UVB‐induced increases of CORT. Mitogen‐induced IFNγ production by splenocytes from UVB‐treated mice was inhibited at 30, 90 min and after 24 h. UVB also led to inhibition of IL‐10 production indicating an immunosuppressive effect on both Th1 and Th2 cytokines. Conditioned media from splenocytes isolated from UVB‐treated animals had no effect on IFNγ production in cultured normal splenocytes; however, IFNγ increased with conditioned media from sham‐irradiated animals. Sera from UVB‐treated mice suppressed T‐cell mitogen‐induced IFNγ production as compared to sera from sham‐treated mice. IFNγ production was inhibited in splenocytes isolated from UVB‐treated animals with intact pituitary, while stimulated in splenocytes from UVB‐treated hypophysectomized mice. Thus, cutaneous exposure to UVB rapidly stimulates systemic CRH, ACTH, β‐endorphin and CORT production accompanied by rapid immunosuppressive effects in splenocytes that appear to be independent of the HPA axis.     

Simple physics-based analytical formulas for the potentials of mean force for the interaction of amino acid side chains in water. 3. Calculation and parameterization of the potentials of mean force of pairs of identical hydrophobic side chains

The potentials of mean force of homodimers of the molecules modeling hydrophobic amino acid side chains (ethane (for alanine), propane (for proline), isobutane (for valine), isopentane (for leucine and isoleucine), ethylbenzene (for phenylalanine), and methyl propyl sulfide (for methionine)) were determined by umbrella-sampling molecular dynamics simulations in explicit water as functions of distance and orientation. Analytical expressions consisting of the Gay-Berne term to represent effective van der Waals interactions and the cavity term derived in paper 1 of this series were fitted to the potentials of mean force. The positions and depths of the contact minima and the positions and heights of the desolvation maxima, including their dependence on the orientation of the molecules, were well represented by the analytical expressions for all systems, which justifies use of such potentials in coarse-grain protein-folding simulations.     

Improving the Accuracy of the Fast Inverse Square Root by Modifying Newton–Raphson Corrections

Direct computation of functions using low-complexity algorithms can be applied both for hardware constraints and in systems where storage capacity is a challenge for processing a large volume of data. We present improved algorithms for fast calculation of the inverse square root function for single-precision and double-precision floating-point numbers. Higher precision is also discussed. Our approach consists in minimizing maximal errors by finding optimal magic constants and modifying the Newton–Raphson coefficients. The obtained algorithms are much more accurate than the original fast inverse square root algorithm and have similar very low computational costs.     

Acknowledgement to referees

Acknowledgements

Acknowledgement to referees     

Studies on the catalysis of the reaction of organotin phenoxides with bis(2,2,2‐trichloroethyl) azodicarboxylate by lithium perchlorate

Organotin phenoxides, which are distinctly more active than the corresponding phenols, react at room temperature with bis(2,2,2‐trichloroethyl) azodicarboxylate to produce para‐substituted phenolic hydrazides in high yields. Copyright © 2004 John Wiley & Sons, Ltd.     

The effect of β-CD polymers structure on the efficiency of copper(II) ion flotation

β-Cyclodextrin (β-CD) polymers were prepared by cross-linking of β-CD with phtalic and 3-nitrophtalic anhydride in anhydrous N,N-dimethylformamide (DMF) in the presence of NaH. The weight-average molecular weight (M _W) and the chemical structure of the polymers were determined using high performance size exclusion chromatography (HPSEC) with refractive index (RI) detector, and ¹H NMR spectroscopy. The molecular weight of the polymer increased with molar ratio of substrates and reaction temperature. ¹H NMR spectra revealed that the β-CD polymers contained both mono- and diesters of phtalic and 3-nitrophtalic acids. In the case of phtalic moieties about four or five diester moieties groups and for 3-nitrophtalic moieties about to or three diester moieties are linkages for β-CD molecule, respectively. Results of copper(II) flotation obtained with the use of nonylphenol polyoxyethyl glycol ether as an non-anionic surfactant and β-CD polymers as complexation collector agent, show␣that the removal of Cu²⁺ decreases with increase of molecular mass of β-CD polymers linked by phtalic or␣3-nitrophtalic anhydrides. For both derivatives with pH increase the copper(II) removal increase. The highest flotation removal, i.e. 93%, was found for β-CD polymers synthesized at 100 °C with molar ratio CD:NaH:3-nitrophtalic anhydride equal to 1:7:7.     

On the interaction between gold and copper in mercury

On the base of cyclic voltammetry, chronoamperometry and potentiometry experiments with the use of the hanging mercury drop electrodes, there was found that a solid AuCu compound is formed in the complex Au-Cu amalgam. The stability of AuCu is controlled by its solubility product, which is equal (7.1±1.5)·10^–6 M ² at 298 K. The temperature dependence of the solubility product allowed to determine H _AuCu of formation in mercury. This value is compared with H _AuCu of the reaction in the binary system. On the basis of theBorn-Haber cycle one may conclude that the AuCu formed in mercury phase should have the same structure as in the binary alloy. Some thermodynamic aspects of reactions in the Au-Cu-Ga amalgam are discussed. The solubility of copper in mercury was experimentally confirmed and is equal (1.1±0.1) · 10^–2at.%.

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Über die Wechselwirkung zwischen Gold und Kupfer in Quecksilber

Zusammenfassung Mit Hilfe von voltammetrischen, chronoamperometrischen und potentiometrischen Experimenten mit der hängenden Quecksilbertropfelektrode wurde eine feste AuCu-Verbindung in Au-Cu-Amalgam gefunden. Die Beständigkeit der Verbindung AuCu wird durch das Löslichkeitsprodukt bestimmt, das gleich (7,1 ± 1,5) · 10^–6 M ² bei 298 K ist. Die Temperaturabhängigkeit des Löslichkeitsproduktes erlaubt die Bestimmung der Bildungswärme H _AuCu der Verbindung in Quecksilber. Dieser Wert wird mit der Bildungswärme H _AuCu im binären System verglichen. Auf der Basis desBorn-Haber-Kreisprozesses kann man schließen, daß das in Quecksilber gebildete AuCu dieselbe Struktur wie im binären System hat. Verschiedene thermodynamische Aspekte der Reaktionen in Au-Cu-Ga-Amalgam werden diskutiert. Die Löslichkeit von Kupfer in Quecksilber wurde experimentell bestätigt und beträgt (1,1 ± 0,1) · 10^–2 at.%.

     

Protein structure prediction with the UNRES force-field using Replica-Exchange Monte Carlo-with-Minimization; Comparison with MCM, CSA, and CFMC

Two current methods of global optimization are coupled to produce the Replica-Exchange method together with Monte Carlo-with-Minimization (REMCM). Its performance is compared with each separate component and with other global optimization techniques. REMCM was applied to search the conformational space of coarse grain protein systems described by the UNRES force field. The method consists of several noninteracting copies of Monte Carlo simulation, and minimization was used after every perturbation to enhance the sampling of low-energy conformations. REMCM was applied to five proteins of different topology, and the results were compared to those from other optimization methods, namely Monte Carlo-with-Minimization (MCM), Conformational Space Annealing (CSA), and Conformational Family Monte Carlo (CFMC). REMCM located global minima for four proteins faster and more consistently than either MCM or CFMC, and it converged faster than CSA for three of the five proteins tested. A performance comparison was also carried out between REMCM and the traditional Replica Exchange method (REM) for one protein, with REMCM showing a significant improvement. Moreover, because of its simplicity, REMCM was easy to implement, thereby offering an alternative to other global optimization methods used in protein structure prediction.