Effects of recombinant human growth hormone on HIV-1-specific T-cell responses,thymic output and proviral DNA in patients on HAART: 48-week follow-up

Background  

Efficacious immune-based therapy in treated chronic HIV-1 infection requires the induction of virus-specific CD4⁺ T cells and subsequent maturation and maintenance of specific memory CD8⁺ T cells. Concomitant daily administration of recombinant human growth hormone (rhGH) with highly active antiretroviral therapy (HAART) was used in chronically infected patients with lipodystrophy in an attempt to reconstitute these virus-specific T-cell responses.     

Experimental and kinetic modeling of the reduction of NO by isobutane in a Jsr at 1 atm

A kinetic study of the reduction of nitric oxide (NO) by isobutane in simulated conditions of the reburning zone was carried out in a fused silica jet‐stirred reactor operating at 1 atm, at temperatures ranging from 1100 to 1450 K. In this new series of experiments, the initial mole fraction of NO was 1000 ppm, that of isobutane was 2200 ppm, and the equivalence ratio was varied from 0.75 to 2. It was demonstrated that for a given temperature, the reduction of NO is favored when the temperature is increased and a maximum NO reduction occurs slightly above stoichiometric conditions. The present results generally follow those reported in previous studies of the reduction of NO by C₁ to C₃ hydrocarbons or natural gas as reburn fuel. A detailed chemical kinetic modeling of the present experiments was performed using an updated and improved kinetic scheme (979 reversible reactions and 130 species). An overall reasonable agreement between the present data and the modeling was obtained. Furthermore, the proposed kinetic mechanism can be successfully used to model the reduction of NO by ethylene, ethane, acetylene, a natural gas blend (methane‐ethane 10:1), propene, and HCN. According to this study, the main route to NO reduction by isobutane involves ketenyl radical. The model indicates that the reduction of NO proceeds through the reaction path: iC₄H₁₀ → C₃H₆ → C₂H₄ → C₂H₃ → C₂H₂ → HCCO; HCCO + NO → HCNO + CO and HCN + CO₂; HCNO + H → HCN → NCO → NH; NH + NO → N₂ and NH + H → followed by N + NO → N₂; NH + NO → N₂O followed by N₂O + H → N₂. © 2000 John Wiley & Sons, Inc. Int J Chem Kinet 32: 365–377, 2000     

A Raman spectroscopic study of humite minerals

Raman spectroscopy has been used to study the structure of the humite mineral group ((A₂SiO₄)_n–A(OH, F)₂ where n represents the number of olivine and brucite layers in the structure and is 1, 2, 3 or 4 and A²⁺ is Mg, Mn, Fe or some mix of these cations). The humite group of minerals forms a morphotropic series with the minerals olivine and brucite. The members of the humite group contain layers of the olivine structure that alternate with layers of the brucite‐like sheets. The minerals are characterized by a complex set of bands in the 800–1000 cm⁻¹ region attributed to the stretching vibrations of the olivine (SiO₄)⁴⁻ units. The number of bands in this region is influenced by the number of olivine layers. Characteristic bending modes of the (SiO₄)⁴⁻ units are observed in the 500–650 cm⁻¹ region. The brucite sheets are characterized by the OH stretching vibrations in the 3475–3625 cm⁻¹ wavenumber region. The position of the OH stretching vibrations is determined by the strength of the hydrogen bond formed between the brucite‐like OH units and the olivine silica layer. The number of olivine sheets and not the chemical composition determines the strength of the hydrogen bonds. Copyright © 2006 John Wiley & Sons, Ltd.     

Multi-resolution analysis techniques and nonlinear PCA for hybrid pansharpening applications

Hyperspectral images have a higher spectral resolution (i.e., a larger number of bands covering the electromagnetic spectrum), but a lower spatial resolution with respect to multispectral or panchromatic acquisitions. For increasing the capabilities of the data in terms of utilization and interpretation, hyperspectral images having both high spectral and spatial resolution are desired. This can be achieved by combining the hyperspectral image with a high spatial resolution panchromatic image. These techniques are generally known as pansharpening and can be divided into component substitution (CS) and multi-resolution analysis (MRA) based methods. In general, the CS methods result in fused images having high spatial quality but the fused images suffer from spectral distortions. On the other hand, images obtained using MRA techniques are not as sharp as CS methods but they are spectrally consistent. Both substitution and filtering approaches are considered adequate when applied to multispectral and PAN images, but have many drawbacks when the low-resolution image is a hyperspectral image. Thus, one of the main challenges in hyperspectral pansharpening is to improve the spatial resolution while preserving as much as possible of the original spectral information. An effective solution to these problems has been found in the use of hybrid approaches, combining the better spatial information of CS and the more accurate spectral information of MRA techniques. In general, in a hybrid approach a CS technique is used to project the original data into a low dimensionality space. Thus, the PAN image is fused with one or more features by means of MRA approach. Finally the inverse projection is used to obtain the enhanced image in the original data space. These methods, permit to effectively enhance the spatial resolution of the hyperspectral image without relevant spectral distortions and on the same time to reduce the computational load of the entire process. In particular, in this paper we focus our attention on the use of Nonlinear Principal Component Analysis (NLPCA) for the projection of the image into a low dimensionality feature space. However, if on one hand the NLPCA has been proved to better represent the intrinsic information of hyperspectral images in the feature space, on the other hand an analysis of the impact of different fusion techniques applied to the nonlinear principal components in order to define the optimal framework for the hybrid pansharpening has not been carried out yet. More in particular, in this paper we analyze the overall impact of several widely used MRA pansharpening algorithms applied in the nonlinear feature space. The results obtained on both synthetic and real data demonstrate that an accurate selection of the pansharpening method can lead to an effective improvement of the enhanced hyperspectral image in terms of spectral quality and spatial consistency, as well as a strong reduction in the computational time.     

Liquid chromatography coupled to tandem mass spectrometry methods for the selective and sensitive determination of 24S-hydroxycholesterol,its sulfate,and/or glucuronide conjugates in plasma

24S-hydroxycholesterol (i.e., cerebrosterol, 24S-OH-Chol) is the main form of cholesterol elimination from the brain. Liquid chromatography–tandem mass spectrometry methods were developed for the quantification of the total and unesterified/unbound fractions of 24S-OH-Chol, its monosulfate, monoglucuronide, and diconjugate derivatives (24S-OH-Chol-3sulfate [3S], 24S-OH-Chol-24glucuronide [24G] and 24S-OH-Chol-3S, 24G, respectively) in human plasma. Linearity, precision, accuracy, and extraction recovery were validated within the typical physiological and pathological ranges of concentrations for each compound. The lower limit of quantifications was 2.00, 0.33, 0.26, and 0.74 ng/ml for 24S-OH-Chol, 24S-OH-Chol-24G, 24S-OH-Chol-3S, and 24-OH-Chol-3S, 24G, respectively. Extraction recovery values in total and unbound plasma fractions were also analyzed in murine and monkey plasma and varied from 73% in mouse to 113% in cynomolgus monkey. The methods could rapidly (less than 7 min) quantify individual compounds with high sensitivity, accuracy (bias ≤15%), and reproducibility (coefficient of variation [CV] ≤ 17%). Their clinical applications were validated by measuring levels of the 4 compounds in samples from 20 noncholestatic donors, 5 cholestatic patients suffering from primary biliary cirrhosis, and 10 patients suffering from biliary stenosis. Results highlight the abundance of 24S-OH-Chol in the total fraction and the abundance of 24S-OH-Chol-3S and 24G in the unbound ones. While the latter strongly accumulate in plasma fractions of cholestatic patients, levels of 24S-OH-Chol remained similar to those of healthy donors. Our results indicate that this approach is suitable for monitoring cerebrosterol and its conjugates in large-scale clinical studies.     

Modifications to the NIST reference measurement procedure (RMP) for the determination of serum glucose by isotope dilution gas chromatography/mass spectrometry

The definitive method (DM), now known as the reference measurement procedure (RMP), for the analysis of glucose in serum was originally published in 1982 by the National Institute of Standards and Technology (NIST). Over the years the method has been subject to a number of modifications to adapt to newer technologies and simplify sample preparation. We discuss here an adaptation of the method associated with serum glucose measurements using a modified isotope dilution gas chromatography/mass spectrometry (ID-GC/MS) method. NIST has used this modified method to certify the concentrations of glucose in SRM 965b, Glucose in Frozen Human Serum, and SRM 1950, Metabolites in Human Plasma. Comparison of results from the revised method with certified values for existing Standard Reference Materials (SRMs) demonstrated that these modifications have not affected the quality of the measurements, giving both good precision and accuracy, while reducing the sample preparation time by a day and a half.     

Attraction between like-charged walls: Short-ranged simulations using local molecular field theory

Effective attraction between like-charged walls mediated by counterions is studied using local molecular field (LMF) theory. Monte Carlo simulations of the "mimic system" given by LMF theory, with short-ranged "Coulomb core" interactions in an effective single particle potential incorporating a mean-field average of the long-ranged Coulomb interactions, provide a direct test of the theory, and are in excellent agreement with more complex simulations of the full Coulomb system by Moreira and Netz [Eur. Phys. J. E 8, 33 (2002)]. A simple, generally applicable criterion to determine the consistency parameter sigma(min) needed for accurate use of the LMF theory is presented.