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A new closure approximation is presented here, and it is based on two thermodynamic relations, namely, a particular case of a local expression together with a global thermodynamic condition. The results obtained from this local approximation are compared with thermodynamic and structural properties determined by using well-established closure approximations as well as numerical simulations for different kinds of interaction potentials. In terms of numerical simulations, the new closure delivers results similar to and sometimes better than the well-known closure relations that are specialized in certain types of interactions.

The extensive use of diesel as fuel has contributed to the current problem of soil contamination, and the aged diesel is a highly toxic pollutant for the soil microbial flora. The objective of the ...

In this work, Curcuma longa L. extract has been used in the synthesis and direct coating of magnetite (Fe3O4) nanoparticles ~12 nm, providing a surface layer of polyphenol groups (–OH and –COOH). This contributes to the development of nanocarriers and triggers different bio-applications. Curcuma longa L. is part of the ginger family (Zingiberaceae); the extracts of this plant contain a polyphenol structure compound, and it has an affinity to be linked to Fe ions. The nanoparticles’ magnetization obtained corresponded to close hysteresis loop Ms = 8.81 emu/g, coercive field Hc = 26.67 Oe, and low remanence energy as iron oxide superparamagnetic nanoparticles (SPIONs). Furthermore, the synthesized nanoparticles (G-M@T) showed tunable single magnetic domain interactions with uniaxial anisotropy as addressable cores at 90–180°. Surface analysis revealed characteristic peaks of Fe 2p, O 1s, and C 1s. From the last one, it was possible to obtain the C–O, C=O, –OH bonds, achieving an acceptable connection with the HepG2 cell line. The G-M@T nanoparticles do not induce cell toxicity in human peripheral blood mononuclear cells or HepG2 cells in vitro, but they can increase the mitochondrial and lysosomal activity in HepG2 cells, probably related to an apoptotic cell death induction or to a stress response due to the high concentration of iron within the cell.

Frames formed by orbits of vectors through the iteration of a bounded operator have recently attracted considerable attention, in particular due to its applications to dynamical sampling. In this article, we consider two commuting bounded operators acting on some separable Hilbert space $\mathcal H$. We completely characterize operators $T$ and $L$ with $TL=LT$ and sets $\Phi\subset \mathcal H$ such that the collection $\{T^k L^j \phi: k\in \mathbb Z, j\in J, \phi \in \Phi \}$ forms a frame of $\mathcal H$. This is done in terms of model subspaces of the space of square integrable functions defined on the torus and having values in some Hardy space with multiplicity. The operators acting on these models are the bilateral shift and the compression of the unilateral shift (acting pointwisely). This context includes the case when the Hilbert space $\mathcal H$ is a subspace of $L^2(\mathbb R)$, invariant under translations along the integers, where the operator $T$ is the translation by one and $L$ is a shift-preserving operator., Comment: 18 pages. To appear in Applied and Computational Harmonic Analysis

We present a model of circular dichroism for proteins, which is mainly based on both the classical theory of optical activity and a series of effective atomic polarizabilities. Such polarizabilities are extracted from the analysis of a set of synchrotron radiation circular dichroism spectra and their corresponding three-dimensional structures from the Protein Data Bank. Each modeled spectrum is obtained from the protein atomic coordinates and the identification of its secondary structure elements. The resulting spectra are in good agreement with additional experimental data and also with the predictions of some other models. Among them, only our approach is able to describe the effect of d-amino acids. Moreover, our model is also utilized to evaluate protein reconstructions as well as structural changes.

We present a model of circular dichroism for proteins that is based on the classical electromagnetic theory for optical activity. The two additional constituents of the model are as follows: an appropriate characterization of the secondary structure of the protein residues and the assignment of an effective polarizability to each type of classified residue. The set of effective polarizabilities is obtained by means of a Monte Carlo statistical method, which is used to analyze a series of synchrotron radiation circular dichroism spectra together with their corresponding crystallographic structures. As a result, the predicted spectra from our model are in good accord with experimental data, as well as with the results of some other theoretical approaches.

We present a model based on effective pair interactions to describe the arrangement of sodium polystyrene sulfonate chains in suspension. The potential functions are obtained from the analysis of a...

We present a method that takes advantage of the Brownian motion of a colloidal particle to experimentally determine the area stretch modulus of giant liposomes in solution, in regard to the continuum mechanics theory of elasticity. The characteristic parameters of the corresponding model are measured by using the three-dimensional version of digital video microscopy. Such an approach makes use of the diffraction pattern generated by fluorescent spheres found below the focal plane of the microscope objective, allowing the spatial location of the sphere and, thus, the reconstruction of its trajectory. When this particle probe is localized in the neighborhood of a bilayer membrane, its motion causes an elastic distortion of the membrane that is quantifiable. More importantly, such deformation is related to the mentioned modulus, whose measured values are consistent with experimental data obtained through well-known techniques.

In this note, we solve the dynamical sampling problem for a class of shift-preserving operators $L:V\to V$ acting on a finitely generated shift-invariant space $V$. We find conditions on $L$ and a finite set of functions of $V$ so that the iterations of the operator $L$ on the functions produce a frame generator set of $V$. This means that the integer translations of the generators form a frame of $V$., 18 pages. To appear in Appl. Comput. Harmon. Anal

We performed molecular dynamics simulations of a lipid bilayer consisting of POPC and cholesterol at temperatures from 283 to 308 K and cholesterol concentrations from 0 to 50% mol/mol. The purpose of this study was to look for the existence of structural differences in the region delimited by these parameters and, in particular, in a region where coexistence of liquid disordered and liquid ordered phases has been proposed. Our interest in this range of concentration and temperature responds to the fact that polyene ionophore activity varies considerably along it. Two force fields, CHARMM36 and Slipids, were compared in order to determine the most suitable. Both force fields predict non-monotonic behaviors consistent with the existence of phase transitions. We found the presence of lateral structural heterogeneity, statistical in nature, in some of the bilayers occurring in this range of temperatures and sterol concentrations. This heterogeneity was produced by correlated ordering of the POPC tails and not due to cholesterol enrichment, and lasts for tens of nanoseconds. We relate these observations to the action of polyenes in these membranes.

This study examines the inflation rates of 215 countries in 2013. Researchers took the data from World Bank database, and fractal analysis was used to determine the hidden dimensions why countries have diverse inflation rates beyond the four identified factors. These factors are money supply, commodity prices, employment rate, and production capacity. The characteristic of inflation is the rate at which the general level of prices of goods and services increase. The result showed that there were countries that had extremely high or low inflation rates. Most of these countries that suffered extremely low inflation are in Africa, one in Europe and one in South America. World Bank established an ideal inflation rate of 2%. The majority of the countries in Europe, America and Asia, had stable inflation figures. Fractal analysis showed politics as the hidden dimension of the changes in inflation rates.

We present a revised version of a coarse-grained model for RNA dynamics. In such approach, the description of nucleotides is reduced to single points that interact between them through a series of effective pair potentials that were obtained from an improved analysis of RNA structures from the Protein Data Bank. These interaction potentials are the main constituents of a Brownian dynamics simulation algorithm that allows to perform a variety of tasks by taking advantage of the reduced number of variables. Such tasks include the prediction of the three-dimensional configuration of a series of test molecules. Moreover, the model permits the inclusion of effective magnesium ions and the ends of the RNA chains can be pulled with an external force to study the process of unfolding. In spite of the simplicity of the model, we obtain a good agreement with the experimental results.

We present a method to describe the formation of small lipid vesicles in terms of three bending elastic constants that can be experimentally measured. Our method combines a general expression of the elastic free energy of the bilayer and the thermodynamic description of molecular aggregation. The resulting model requires the size distribution of liposomes, which is determined from the X-ray scattered intensity spectra of vesicular dispersions. By using two different preparation methods, we studied a series of vesicular solutions made of distinct lipids and we obtained their corresponding bending elastic constants that are consistent with known bending rigidities.

International audience; The production of botrytised wines involves grapes with high sugar concentration and complex aromas caused by the presence of noble rot. The aim of this paper was to characterise botrytised grapes on a physico-chemical basis and therefore identify markers of its evolution. Colour analysis, compression and puncture tests and phenolic profiles were performed in order to identify the potential markers and discriminating tools for the presence of the fungus. Chenin blanc grapes from two parcels in Loire Valley (France) were sampled during a 4-week period. Significant changes of phenolic composition like the total polyphenol which decreases up to 40 % were observed as B. cinerea was more advanced on the berries. Myricetin a compound that has not been reported before in white grapes was found only in highly affected berries. At the same time as the level of infection increases, the presence of the fungus seems to induce, from one side, an increase of catechin, epicatechin and epicatechin gallate, and from the other side, the decrease in caftaric acid, coutaric acid, quercetin-3 glucoside and kaempferol-3 glucoside. Puncture tests appeared to be the more reliable mechanical tool to differentiate between infection levels by itself; however, the combination of puncture and compression tests with colour showed a more significant and clear differentiation. This combination appeared to be the most adequate for stablish markers of noble rot evolution in the conditions studied. A decrease in mechanical resistance of berries' skin (measured by the maximum puncture force required for skin rupture) was observed during infection. These results on botrytised Chenin grapes are new and provide a novel approach for an objective measurement of noble rot in Chenin grapes.

Background and objective: Benign prostatic hyperplasia (BPH) is a non-malignant enlargement of the prostate that results in obstructive lower urinary tract symptoms. Saw palmetto (Serenoa repens), the dwarf American palm (Arecaceae family), is commonly used to treat BPH. The Cuban royal palm (Roystonea regia) also belongs to the Arecaceae family, and 200–400mg of D-004, a lipid extract from its fruits, administered orally for 14 days has been shown to prevent testosterone- but not dihydrotestosterone-induced prostatic hyperplasia in rats. D-004 (125–250 μ/mL) added to preparations of rat vas deferens caused a marked, dose-dependent and significant inhibition of noradrenaline-induced smooth muscle contraction, a response mediated through α1-adrenoceptors, and was more effective in these respects than Saw palmetto. However, the in vivo effects of D-004 and Saw palmetto on the hypertensive response induced by noradrenaline were modest (albeit significant), and neither treatment affected resting blood pressure or heart rate in rats. The differential effects of D-004 in in vitro and in vivo models could be related to a differential affinity for adrenoceptor subtypes or to different bioavailabilities in vascular and urogenital targets. Phenylephrine injected into rodents induces prostatic hyperplasia with all the characteristic morphological changes of the condition but does not result in enlargement of the prostate. Therefore, this phenylephrine-induced change in rat prostate tissue is called atypical prostatic hyperplasia. It serves as an in vivo model of prostatic hyperplasia induced by stimulation of α1-adrenoceptors. The objective of this study was to determine whether D-004 can inhibit induction of atypical prostatic hyperplasia by phenylephrine in rats. Methods: Rats were randomly distributed into five groups (ten rats/group). One group was a negative control and received oral vehicle only. The other four groups were injected subcutaneously with phenylephrine (2 mg/kg): of these groups, one was a positive control receiving the vehicle, and the other three groups were treated with D-004 or Saw palmetto (both 400 mg/kg) or tamsulosin 0.4 mg/kg. All active treatments were given orally for 28 days. After completion of treatment, rats were placed unrestrained in metabolic cages and micturition studies were performed. The rats were later killed and their prostates removed and weighed. Prostate samples were processed for histological study, with histological changes being assessed according to a scoring system. Bodyweight was measured at baseline and at weekly intervals. Results: Histological examination of positive control rats revealed features of atypical prostatic hyperplasia, with piling-up, papillary and cribiform patterns and budding-out of epithelial cells. Micturition assessment revealed that phenylephrine significantly lowered both the total volume of urine in 1 hour and the volume per micturition; the latter was considered the main efficacy variable. D-004 and Saw palmetto extracts significantly prevented this reduction in volume per micturition by 70.5% and 68.6%, respectively, while tamsulosin totally abolished the reduction in micturition induced by phenylephrine (100% inhibition). Tamsulosin, D-004 and Saw palmetto significantly reduced the histological changes of atypical prostatic hyperplasia induced by phenylephrine by 73.1%, 61.2% and 50.0%, respectively. Conclusions: Administration of D-004 resulted in marked and significant prevention of phenylephrine-induced impairment of micturition and histological changes in rat prostate. These findings indicate that, in vivo, D-004 effectively opposes these responses to phenylephrine, which are mediated through urogenital α1-adrenoceptors. In this respect, D-004 was moderately more effective than Saw palmetto, a phytotherapeutic standard used to treat BPH, but less effective than tamsulosin, a selective α1A-adrenoceptor antagonist.

Benign prostatic hyperplasia (BPH) is the non-malignant, uncontrolled growth of glandular and stromal elements of the prostate gland. Lipid extracts from Saw palmetto (Arecaceae) fruits are widely used to treat BPH. The Cuban royal palm (Roystonea regia) is a member of the same family. Previous studies have found that D-004, a lipid extract from the R. regia fruit, administered orally at 200-800 mg/day for 14 days, prevented testosterone- but not dihydrotestosterone-induced prostate hyperplasia in rats.To determine whether D-004 can inhibit noradrenaline (NA) [norepinephrine]- and acetylcholine (ACh)-induced smooth muscle contraction in rat vas deferens and to investigate the in vivo effects of D-004 on NA pressure-elevating effects in rats, an effect mediated by vascular alpha1-adrenoceptors.In vitro effects were investigated by adding D-004 (125-500 microg/mL) to preparations of rat vas deferens suspended in an organ bath containing Tyrode's solution, in which in vitro contractions were induced by NA or ACh. Negative and positive controls containing Tyrode's solution alone or with Saw palmetto extracts (125-500 microg/mL), respectively, were included. To assess the in vivo effects of D-004 on arterial blood pressure, rats were randomly distributed to one of five groups (ten rats/group): these consisted of a negative control group receiving the vehicle, two groups treated with D-004 (400 and 800 mg/kg) and two other groups treated with Saw palmetto (400 and 800 mg/kg). All treatments were orally administered. Rats were anaesthetised with sodium thiopental. Heart rate and blood pressure were registered in baseline conditions. Immediately afterwards, rats were injected intravenously over 5 seconds with successive doses of NA (1, 2 and 4 microg/kg) [0.1mL/100g], with 5 minutes' interval between doses.D-004 and Saw palmetto (125-500 microg/mL) significantly (p0.05) and dose dependently inhibited contractions induced by NA in rat vas deferens versus control. D-004 was more effective in inhibiting NA-induced contractions than Saw palmetto. The contractions induced by NA in preparations with D-004 (500 microg/mL) were weaker (p0.05) than in preparations containing Saw palmetto (500 microg/mL). At 125 microg/mL, D-004 inhibited the contractions induced by NA 1 and 32 x 10(-6) mol/L by 70.8% and 28.5%, respectively, and Saw palmetto by 56.2% and 10.7%, respectively. At 500 microg/mL, D-004 inhibited these contractions by 100.0% and 71.3%, and Saw palmetto by 80.0% and 42.7%, respectively. The inhibitory concentrations of 50% (IC50) for NA contractions were 148.34 (D-004) and 188.38 (Saw palmetto) microg/mL. D-004 and Saw palmetto significantly (p0.05) and to a similar extent inhibited ACh-induced contractions, but less effectively than contractions induced by NA, since at 125 microg/mL they were ineffective. At a dose of 800 mg/kg, but not at 400 mg/kg, D-004 and Saw palmetto inhibited the pressure-elevating effects induced with low (1 microg/kg) but not with high doses (2 and 4 microg/kg) of NA.D-004 and Saw palmetto extracts inhibited in vitro the contractile responses to NA and ACh in rat vas deferens, and were more effective in inhibiting NA than ACh contractions. The in vivo effects of D-004 and Saw palmetto on the hypertensive response induced by NA were significant but modest. These results are preliminary as the relevance of the effects of D-004 on alpha1-adrenoceptors deserves further investigation, including comparative studies versus specific defined alpha1-adrenoceptor antagonists.

A series of hydrophobic sodium poly(styrene-co-styrene sulfonate)'s of various charge fractions was studied by means of two combined techniques, static light scattering and small-angle X-rays scattering. The existence of structural changes as a function of the charge content was evidenced in the full scattering spectrum. By fitting the experimental data with some known models, we were able to show that these hydrophobic polyelectrolytes have a Gaussian shape at large scales. Moreover, the correlation between characteristic lengths of different scales suggests that the small angle upturn of the most hydrophobic polyelectrolytes could be related to the conformation of the chains.

We apply the Ornstein–Zernike equations together with the extended Zerah–Hansen approach, described in a previous paper [J. Chem. Phys. 109, 11074 (1998)], to determine the microstructure of a colloidal suspension at finite concentrations. Using these results as an input, the effective pair potential between two colloidal particles is also calculated following the general approach described in that paper. It is found that, for sufficiently large concentrations, this effective potential develops an attractive well with a minimum located at a distance of almost four macroparticle diameters. It is also shown that this attraction is generated by the inversion of the sign of the effective charged distribution surrounding each macroparticle involved in the electrostatic component of the effective pair potential.

We present a revised version of a Monte Carlo simulation model for RNA molecules that was introduced in a previous communication [O. Taxilaga-Zetina, P. Pliego-Pastrana, and M. D. Carbajal-Tinoco, Phys. Rev. E 81, 041914 (2010)]. The basic model consists of a series of knowledge-based pair potentials that were obtained from the statistical analysis of large RNAs belonging to the Protein Data Bank. These effective interactions are then used to dress a polymeric chain that reproduces relatively simple secondary structures (e.g., small hairpins). In order to describe more complicated three-dimensional structures such as pseudo-knots, here we include orientational information for the interaction between nucleotides forming hydrogen bonds, as in the case of the Watson-Crick base pairs. As a result, the simulated molecules obtained through the modified model are now consistent with their corresponding experimental configurations.

A series of hydrophobic sodium poly(styrene-co-styrene sulfonate) of different charge fractions has been studied by static light scattering in the thermodynamic limit. In the examined concentration range ( ≤ 0.1 M/l, in monomers), the solutions show an ideal gas behaviour. A quantitative comparison with previous osmotic pressure measurements reveals the existence of a strong variation of the polarizability, which is related to a change of local chain conformation. This result can be interpreted in terms of the globular instability model for hydrophobic polyelectrolytes (pearl necklace model).

A general formalism for ionic fluids is presented. We report general and exact expressions for the distribution functions which directly satisfy the Stillinger–Lovett moment conditions. General and exact expressions are also provided for the effective pair potentials among charged colloidal particles. These general expressions are a direct consequence of the multicomponent Ornstein–Zernike (OZ) equations and the asymptotic behavior of the direct correlation functions in charged systems. The effective pair potentials show two distinct parts: short-ranged and electrostatic. For the primitive model (PM) with pointlike small ions the electrostatic component is reduced, for sufficiently large distances, to a screened Coulomb potential with renormalized charges. The general expression of the effective electrostatic interaction gives a clear insight of the specific conditions of validity of the Derjaguin–Landau–Verwey–Overbeek (DLVO) model and of the possible directions in which this model may be improved. We also present results for the PM with pointlike small ions obtained from an implementation of the Zerah–Hansen (ZH) approximation complemented with a new minimization criterion. These results are compared with experimental data to test the accuracy of the predictions of the ZH scheme against those obtained from the DLVO model.

We report the direct measurement by video microscopy of the Van Hove function of quasi-two-dimensional colloidal suspensions. Under these conditions of confinement, the effective interparticlepotential exhibits an intermediate range attractive component. This is obtained by deconvolutingthe measured pair correlation function using an inverse Monte Carlo method. The experimentaldynamic behavior is well represented by a Brownian dynamics simulation, performed using theexperimental pair potential and an effective quasi-two-dimensional short-time diffusion coefficient.[S0031-9007(98)06595-8]

Cholesterol (Chol) plays an essential function in the regulation of the physical properties of the cell membrane by controlling the lipid organization and phase behavior and, thus, managing the membrane fluidity. However, at sufficiently high concentrations of Chol, the so-called liquid-ordered state is formed over a wide range of temperatures and it is characterized by high conformational order and high translational mobility. We performed a set of all-atom molecular dynamics simulations of lipid bilayers of POPC with different Chol/POPC molar ratios ranging from 0 to 50% and three different temperatures. We analyzed the behavior of the deuterium order parameter profiles of the POPC as well as its lateral diffusion. Our results show that the lipid tails become more ordered with the increase of the Chol concentration, as found in experimental results. Moreover, the predicted values of lateral diffusion are in the range of the fluid phase (D ≈ 10∧−8 - 10∧−7 cm∧2/s) in agreement with experimental ones. The observed dependences with cholesterol content and temperature are not monotonically, reflecting the phase diagram for this mixture and suggest domain formation between 15 to 40 mol %m especially for the highest temperature. It is important that the simulation is able to predict these subtle changes and opens the possibility of using them as tools for understanding the molecular effects of sterols.

"By using three-dimensional digital video microscopy (DVM-3D), we study the displacement of a Brownian particle immersed in a polymeric solution located near a rigid wall. The technique takes advantage of the diffraction pattern generated by a fluorescent particle that is found below the focal plane of an optical microscope. The particle is then tracked from the analysis of a sequence of digitized images to reconstruct its trajectory, which provides relevant information about the properties of the system. In a first stage, we obtain the mean square displacement (MSD) of a spherical probe dissolved in a viscoelastic solution. This MSD is then used to determine the elastic and viscous moduli of the suspension. Such measurements are consistent with bulk measurements performed by means of two techniques, namely, diffusing wave spectroscopy and mechanical rheology. Near the rigid wall, the motion of the probe particle can be split in two directions, i.e., parallel and perpendicular to the surface. For short times (but still in the Brownian regime), such motion can be characterized by means of two distance dependent friction coefficients. We observe deviations of the measured friction coefficients in comparison with the Newtonian behavior."

Digital video microscopy is used to study the Brownian motion in quasibidimensional colloidal systems, consisting of spherical polystyrene particles suspended in water and confined between two glass plates. This technique allows the direct measurement of the lateral (two-dimensional) probability distribution function, $P(\ensuremath{\Delta}\mathbf{r},t),$ of the random variable \ensuremath{\Delta}r (the particle displacement) at time $t,$ and the mean squared displacement $W(t).$ We studied the effect of confinement in highly diluted samples, where $W(t)$ is found to be a linear function of time. The hydrodynamic interactions between the colloidal particles and the glass walls are found to be more important than predicted by approximate hydrodynamic theories. Keeping fixed the separation between the plates, we studied the effect of direct and hydrodynamic interactions between the particles by increasing the particle concentration. In this case, the short time dynamics is characterized by means of a theoretical approach that describes self-diffusion in terms of the static structure of the suspension. In all the samples studied, we found negligible deviations of $P(\ensuremath{\Delta}\mathbf{r},t)$ from Gaussian behavior.

The effect of policosanol, a mixture of high-molecular-weight aliphatic alcohols isolated from sugar-cane wax, on casein-induced hypercholesterolaemia in rabbits was studied. When policosanol was administered by the oral route once daily for 30 d (50mg/kg) the increases in plasma total cholesterol and LDL-cholesterol (LDC-C) were significantly reduced when compared with the control group. The incorporation of3H2O into sterols in the liver was significantly depressed, suggesting inhibition of hepatic cholesterol biosynthesis. The oral administration of policosanol raised the rate of removal of125l-labelled LDL from serum. Kinetic parameters calculated following injection of [125I]LDL showed than in casein-fed rabbits, the terminal half-life (t½) was significantly decreased after policosanol treatment. The hepatic LDL-binding activity was increased after policosanol administration which suggested that the enhanced clearance was due, at least in part, to increased receptor-mediated uptake of LDL by the liver. Considered together, these results suggest that policosanol can significantly reduce the increase of plasma LDL-C in rabbits fed on a wheat starch-casein diet by reducing cholesterol biosynthesis in the liver. Such an effect could account for the enhancement of LDL catabolism through the receptor-mediated pathway.

The ternary system Ni2+(AOT)2 (nickel 2-bis[2-ethylhexyl] sulfosuccinate)/water/isooctane presents w/o and o/w microemulsions with a Winsor progression ( 2 ¯ Φ − 3 Φ − 2 Φ ), without the addition of salt; the “fish diagram” was obtained for α = 0.5 and γ = 0.02 – 0.22 . Using static and dynamic light scattering the micellar size, the ratio of water to surfactant, and the density of micelles for this system were estimated. In addition, the mean interfacial curvature as a function of temperature was obtained.

By using digital video microscopy, we study the three-dimensional displacement of fluorescent colloidal particles that are located close to a water-air interface. Our technique takes advantage of the diffraction pattern generated by fluorescent spheres that are found below the focal plane of the microscope objective. By means of image analysis software, we are able to determine the spatial location of a few beads in a sequence of digital images, which allows us to reconstruct their trajectories. From their corresponding mean square displacements, we get the diffusion coefficients in the directions parallel and perpendicular to the interface. We find a qualitatively different kind of diffusion between the two directions, in agreement with theoretical predictions that are obtained from established models as well as our own proposals. Quite interesting, we observe the enhanced Brownian motion in the parallel direction.

Quantum Mechanics is the favourite theory to predict the structure of any group of atoms, including biological molecules. Due to numerous difficulties, however, it is necessary to introduce a series of approximations to overcome such impediments. We present a coarse-grained model of circular dichroism (CD) that is based on the theory of optical activity, developed by DeVoe, in order to predict CD spectra. In first stage, we determine the polarisability of individual monomers (residues, in the case of peptides) from experiments of molar absorptivity. The complex polarisabilities are used together with peptide structures obtained by density functional theory and other methods to determine their corresponding CD spectra, which are in reasonable agreement with their experimental counterparts.

By means of digital video microscopy, we study the three-dimensional (3D) motion of fluorescent colloidal particles that are located close to a water-air interface. In order to track the spatial motion of such particles, we take advantage of their diffraction pattern which is characterized by using image analysis software. In accordance with theoretical predictions, we find an asymmetric motion of the particles in the directions parallel and perpendicular to the interface.

The static structure and the time‐dependent self‐diffusion motion of interacting Brownian particles in a model two‐dimensional suspension are discussed. For the static structure we report Brownian dynamics results assuming a hard disk plus Yukawa pair potential. The self‐diffusion properties of this model system are calculated from two independent theoretical approaches. In order to assess the accuracy of the predictions of these two theories, we also performed Brownian dynamics calculations of the time‐dependent self‐diffusion coefficient for a wide range of values of both the particle concentration and the pair potential coupling constant. We find that both theories reproduce very well the main features exhibited by the Brownian dynamics data. Quantitatively, there are some discrepancies between both theoretical predictions and the Brownian dynamics results, which are negligible at moderate couplings, but become larger for strongly coupled systems and long times.

D-004, a lipid extract of Roystonea regia fruits that contains oleic, lauric and myristic acids as major components inhibits alpha1-adrenoreceptors-mediated contractile responses in isolated rat vas deferens and prostate trips; no study has demonstrated a similar effect for oleic, lauric or myristic acids individually. Therefore, the effects of D-004 (250 microg/mL), oleic (100 microg/mL), lauric (50 microg/mL) or myristic (25 microg/mL) acids and their combined effects on phenylephrine (PHE: 10(-7)-10(-4) mol/L) induced contractions has been studied. No treatment changed the basal tone of the preparations, but all inhibited PHE-induced contractions. D-004 produced the highest inhibition, followed by lauric acid, which was more effective than myristic and oleic acids against PHE-induced contractions of control group. D-004 and the mixture of the three acids produced similar inhibitions.

A theoretical approach to the study of self‐diffusion properties of interacting colloidal particles in suspensions is developed. It is based on the assumption of a model for the memory function Ms(q,t), whose parameters are calculated by using exact short‐time conditions for the self‐diffusion propagator. Expressions, in terms of microscopic quantities of the system, for the time‐dependent self‐diffusion coefficient D(t) are derived from three different functional forms for Ms(q,t): a single‐exponential function (already introduced in previous communications [J. L. Arauz‐Lara and M. Medina‐Noyola, J. Phys. A 19, L117 (1986); G. Nagele, M. Medina‐Noyola, R. Klein, and J. L. Arauz‐Lara, Physica A 149, 123 (1988)], an algebraic function, and a combination of the two. The latter one involves an adjustable parameter (the relative weight of the two modes) which can be determined by fitting the calculated values of D(t) to experimental data at long times. Explicit calculations of D(t) were carried out for system...

We derive a set of effective potentials describing the interaction between pairs of nucleotides that belong to an RNA molecule. Such interaction potentials are then used as the main constituents of a simplified simulation model, which is tested in the description of small secondary structure motifs. Our simulated RNA hairpins are consistent with the experimental structures obtained by NMR.

We present a new closure relation that is an extension of the thermodynamically consistent approximation of Rogers and Young [Phys. Rev. A 30, 999 (1984)]. In the proposed closure, we introduce a nonlinear term along with an additional thermodynamic consistency equation. We compare some thermodynamic and structural properties obtained within our scheme with the corresponding results emerging from other approaches that include numerical simulations and other closure approximations. For the systems considered here, the results derived from our scheme are in better agreement with the reference values of the simulations.

After a brief overview that is focused on the importance of biological molecules like RNA and proteins, we present a model that can be used to predict the three‐dimensional structure of RNA sequences. An appropriate version of our model was first used in the description of polypeptide folding. These coarse‐graining models are based on a set of effective pair potentials that were extracted from experimental data. Such interaction potentials are then used as the main input of Monte Carlo simulations which are characterized by requiring a reasonable computer time, in comparison with other approaches. The resulting structures obtained from our method are clearly similar to the experimental ones.

The three-dimensional motion of single colloidal particles close to a plane wall is measured by optical microscopy. In accordance with classical theoretical predictions, we find an asymmetric motion of the particles in the directions parallel and perpendicular to the wall. We also find that, close to the wall, the distribution functions of perpendicular steps are asymmetric, being shorter toward the wall and longer away from it.

Benign prostatic hyperplasia (BPH) is the nonmalignant, uncontrolled growth of prostate gland cells and stroma leading to difficulty in urinating. Lipid extracts from Saw palmetto (Arecaceae) fruits are used to treat BPH. The Cuban royal palm (Roystonea regia) is a member of this family and D-004, a lipid extract from its fruits, prevents prostate hyperplasia (PH) induced with testosterone, as opposed to dihydrotestosterone, in rodents. This study investigated whether D-004 could prevent the histological features of testosterone-induced PH in rats. Rats were distributed into six groups (10 rats per group): A negative control group receiving subcutaneous injections of soy oil and treated with vehicle, and five groups injected subcutaneously with testosterone and treated with the vehicle (positive control), D-004 (100, 200 and 400 mg/kg) or Saw palmetto (400 mg/kg). Treatments were given orally for 14 days. At sacrifice, prostates were removed and processed for light microscopy. The histopathological findings of PH were assessed according to a score-chart protocol. D-004 200 and 400 mg/kg, but not 100 mg/kg, significantly and moderately in a dose-dependent manner prevented prostate enlargement and the testosterone-induced histological changes. Compared with positive controls, D-004 200 and 400 mg/kg inhibited prostate size increases and the histological score up to 56.1% and 60.7%, respectively, while Saw palmetto 400 mg/kg reduced such variables by 45.8% and 49.0%, respectively. The effects of D-004 400 mg/kg on the histological changes, not on prostate size, were greater (p0.05) than those of Saw palmetto. D-004 and Saw palmetto did not affect body weight values. In conclusion, D-004 200 and 400 mg/kg administered orally for 14 days prevented the increase of prostate size and the testosterone-induced histological changes in rats, its effects being comparable or mildly better than those of Saw palmetto. These results extend previous data showing preventive effects of D-004 on testosterone-induced prostate enlargement with in rodents, and further studies are required to explore the mechanisms underlying such effects.

Benign prostatic hyperplasia (BPH) is a nonmalignant growth of prostate leading to difficulty in urinating. Drug therapy, phytotherapy included, is frequently used to treat BPH. D-004 is a lipid extract from Roystonea regia fruits, and previous studies have shown that oral treatment with D-004 for 14 days prevented prostate hyperplasia (PH) induced by testosterone in rats. No information is available, however; about the effects of D-004 in reverting already established PH. This study investigated whether D-004 could improve PH after oral dosing with testosterone in rats. Rats were distributed in five groups (10 rats/group). One group was injected with soy oil (negative control) and four groups were injected with testosterone: one was orally treated with the vehicle (positive control), two with D-004 (200 and 400 mg/kg) and the other with Saw palmetto (400 mg/kg). At study completion, the rats were sacrificed and the prostates were removed and weighed. D-004 (200 and 400 mg/kg) significantly and dose-dependently decreased prostate enlargement by 85% and 98%, respectively, versus the positive control. Likewise, Saw palmetto (400 mg/kg) significantly reduced prostate weight by 73% versus the positive control. D-004 (400 mg/kg) was more effective (p0.05) than Saw palmetto (400 mg/kg) in lowering prostate enlargement. D-004 and Saw palmetto also decreased the prostate weight to body weight ratio, but did not affect body weight. In conclusion, D-004 (200 and 400 mg/kg) orally administered was effective for reducing PH after testosterone dosing. D-004 (400 mg/kg) was more effective than Saw palmetto (400 mg/kg). Further studies, however, are needed to corroborate the present results.

We present a model of protein folding which is based on a potential function that describes the effective interaction between two amino acids (alanines, in this case). Our model is consistent with the formation of two important secondary structures, namely, an alpha-helix and a beta-ladder. In each case, we estimate the density of states using a random walk in energy space. This function allows the direct calculation of certain thermodynamic properties. By means of the configurational temperature, we also verify that the obtained polypeptides are in their native state.

D-003 is a mixture of high molecular weight aliphatic primary acids purified from sugar cane wax with antiplatelet and cholesterol-lowering effects. Previous studies showed that D-003 (10-20 mg/day) administered for a short time inhibits platelet aggregation, 14 days being the longest duration investigated. This study was conducted to investigate the effects of D-003 (5 and 10 mg/day) for 30 days on platelet aggregation in normocholesterolemic subjects. This report shows the effects of D-003 on platelet aggregation to arachidonic acid (AA) (1.5 mM), collagen (2 microg/ml) and adenosine 5'-diphosphate ADP (2 microM) assessed at baseline and at treatment completion. Fifty-four subjects were randomized to placebo or D-003 (5 or 10 mg/day) for 30 days. Platelet aggregation to AA, collagen and ADP were assessed. D-003 at the lowest dose (5 mg/day) significantly but modestly inhibited (p0.01) platelet aggregation to AA (5.0%) and (p0.01) to collagen (7.5%). D-003 at 10 mg/day inhibited (p0.001) platelet aggregation to AA and collagen (p0.01) by 20.3% and 14.7%, respectively. ADP-induced aggregation, however, was unchanged. D-003 at 10 mg/day, but not at 5 mg/day, lowered (p0.01) plasma fibrinogen. D-003 (5 and 10 mg/day) reduced low-density lipoprotein cholesterol (LDL-C) by 17.7% and 26.4%, respectively, and total cholesterol (TC) by 14.5% and 18.5%, while at 10 mg/day, but not at 5 mg/day, it increased high-density lipoprotein cholesterol (HDL-C) by 9.6%. Triglycerides, however, were unchanged with D-003. No disturbances in safety indicators were induced with D-003. One subject (D-003 5 mg/day) discontinued the study and four patients (three taking D-003 and one taking placebo) reported adverse effects (AE) (headache in two patients taking D-003 and one patient taking placebo, and polyphagia in one patient taking D-003). In conclusion, D-003 (5-10 mg/day) for 30 days inhibited platelet aggregation to AA and collagen but not to ADP Therefore, the antiplatelet effect was present with the longer treatment, even at a dose of 5 mg/day. The cholesterol-lowering effects of D-003 were consistent with those expected for such a short treatment. In addition, D-003 at 10 mg/day significantly lowered plasma fibrinogen. The treatment was well tolerated.

Non-steroidal anti-inflammatory drugs (NSAIDs) are indicated for treatment of rheumatoid arthritis and osteoarthritis, but often induce gastric adverse experiences (AE), including gastric ulcers and complications. Inhibitors of proton pump and H(2) antagonists are very effective for duodenal ulcer; meanwhile, cytoprotective drugs are more effective for gastric ulcer. D-002 is a mixture of higher aliphatic alcohols obtained from beeswax, wherein triacontanol is the most abundant. D-002 induces anti-ulcer effects through a cytoprotective mechanism, being more effective in protecting against ethanol- and NSAID-induced ulcers. The present double-blind, placebo-controlled clinical study was undertaken to investigate the effects of D-002 on gastric symptoms associated to piroxicam use on patients suffering osteoarthritis. Fifty-nine patients, all taking piroxicam, 20 mg/day, were randomized to placebo or D-002 (40 or 100 mg/day) for 14 days. The primary efficacy variable was the reduction on the frequency of patients with gastric AE compared with placebo. Pain evolution was investigated to discard any influence on D-002 on the analgesic effect of piroxicam. The frequency of patients treated with D-002, 40 and 100 mg/day, reporting acidity [0 of 18 (0%) and 1 of 21 (4.8%), respectively] was lower (P.05) than in placebo [6 of 20 (30%)]. Also, the frequency of patients treated with 100 mg/day reporting some gastric AE [5 of 21 (23.8%)] was lower (P.05) than in placebo [13 of 20 (65.0%)]. The analgesic effect of piroxicam was unaffected with D-002. Treatment was well tolerated. Two patients discontinued from the study because of gastrointestinal AE: one in the placebo group and the other treated with D-002, 40 mg/day. Other three patients discontinued because of other AE: mildly uncontrolled hypertension (one in the placebo group, one treated with D-002, 40 mg/day) and headache (one treated with D-200, 100 mg/day). It is concluded that D-002 could be useful for controlling gastric AE of patients treated with NSAIDs, although further studies with a larger sample size and longer follow-up are needed for definitive conclusions.

Benign prostatic hyperplasia (BPH) is the noncancerous, uncontrolled growth of prostate gland cells and stroma that can cause difficulty urinating. Fruit lipid extracts from saw palmetto, a palm from the Arecaceae family, are used for BPH management. The Cuban royal palm, Roystonea regia, is also a member of the Arecaceae family and therefore it was appropriate to investigate the protective effects of Roystonea regia fruit lipid extracts on prostatic hyperplasia. The aim of this study was to investigate whether D-004, a lipid extract from Roystonea regia fruits, prevented testosterone-induced PH in castrated and intact rodents. Two series of experiments were performed. The first one was conducted in castrated and intact rats, distributed into five groups of 10 rats per group. The negative control group was injected with soy oil and treated orally with vehicle, while the four testosterone-injected groups were treated with vehicle (positive control), D-004 100, 200 and 400 mg/kg, respectively. The other experiment was conducted in castrated and intact mice. These were distributed into four groups of 10 mice per group: a negative control group and three testosterone-injected groups, of which one was a positive control, while two received D-004 200 and 400 mg/kg, respectively. At study completion, the rodents were sacrificed and prostates removed and weighed. D-004 at doses of 100, 200 and 400 mg/kg significantly and dose-dependently prevented prostate enlargement in intact and castrated rats and mice. The percentage inhibitions obtained in mice were greater: 77% and 84% for intact and castrated mice, respectively. D-004 therapy did not affect body weight. It is concluded that D-004 administered orally significantly prevented testosterone-induced prostate enlargement in both intact and castrated rodents, indicating that an endogenous supply of testosterone is not necessary to observe such an effect The results of the present investigation support further studies of D-004 on experimental models of prostatic hyperplasia.

D-003 is a mixture of very high molecular weight aliphatic acids purified from sugar cane wax showing cholesterol-lowering and antiplatelet effects proven in experimental and clinical studies. Experimental evidence indicates that inhibition of platelet aggregation induced by D-003 is associated with a reduction of thromboxane B2 (TxB2) and an increase of prostacyclin (Pgl2) serum levels. This double-blinded, randomized, placebo-controlled study was undertaken to investigate whether D-003 (20 mg/day) modifies serum levels of TxB2 and Pgl2 and inhibits platelet aggregation in human healthy volunteers. Thirty-one subjects were randomized to placebo or D-003 at 20 mg/day for 14 days. Serum levels of TxB2 and Pgl2 and platelet aggregation to arachidonic acid (AA) (1.75 mM) and collagen (1 microg/ml) were assessed. D-003 (20 mg/day) significantly reduced (p0.001) TxB2by 36.4% and increased Pgl2 serum levels by 31% compared with baseline, and these changes were different from placebo. As expected, D-003 significantly inhibited (p0.001) platelet aggregation to AA (81.9-65.6%) and to collagen (75.3-62.3%). No subject withdrew from the study. No drug-related disturbances were observed. We conclude that D-003 at 20 mg/day for 14 days significantly inhibited platelet aggregation to AA and collagen and reduced TxB2 and increased Pgl2 serum levels. These results are consistent with those observed in experimental models, indicating that the antiplatelet effect of D-003 is associated with the observed changes on the levels of AA metabolites. Further studies, however, should explore the mechanism involved in this action in greater depth.

In a previous paper [Phys. Rev. E 68, 011903 (2003)], we extracted an effective potential between pairs of alanines from an experimental correlation function, through the Ornstein‐Zernike equation and the hypernetted chain approximation. A modified version of this effective pair potential is then used in a Monte Carlo simulation. As a result, we obtain two important secondary structures, i.e., an α‐helix and a β‐ladder.