Rapid determination and comparative pharmacokinetics of tetrahydropalmatine in spontaneously hypertensive rats and normotensive rats

A rapid high‐performance liquid chromatographic method was developed and validated for determination of tetrahydropalmatine (THP), an active component of Rhizoma Corydalis, in rat plasma. The samples were prepared using protein precipitation and separated on an Agilent XDB‐C₁₈ column (150 × 4.6 mm, 5 µm) with the mobile phase consisting of methanol–0.1% phosphate acid solution, adjusted with triethylamine to pH 5.5 (65:35). Good linearity was found within 0.10–10.00 µg/mL of THP in rat plasma sample. The intra‐ and inter‐day precision values were less than 10%. The developed method was successfully applied to assess the pharmacokinetics of THP in spontaneously hypertensive rats (SHR) and normotensive rats. After oral administration of a single dose of THP (60 mg/kg), the maximum plasma concentrations were 6.15 ± 2.1 and 7.54 ± 2.9 µg/mL for normotensive rats and SHR, respectively. The mean values of AUC_0–∞ of THP in SHR were 81.44 ± 45.0 µg h/mL, significantly higher (p < 0.05) than in normotensive rats (44.06 ± 19.6 µg h/mL). The t_1/2 and MRT in SHR were much longer than that in healthy Sprague–Dawley rats, indicating slow elimination of THP in SHR. The results indicated that there are some differences in pharmacokinetics of THP in SHR and Sprague–Dawley rats and it is very important to investigate the pharmacokinetic properties of drugs in pathological conditions. Copyright © 2011 John Wiley & Sons, Ltd.     

Parametric investigation on the effect of channel topologies on electrophoretic separations

This paper presents a systematic study that illustrates the importance of the topologies of microchannels on electrokinetically based separation. Using theoretical and numerical analyses, we designed and showed that topologies that significantly increased the surface-to-volume ratio of the channel can provide dramatic improvement in the ability of the channel both to dissipate the heat generated by Joule heating and to reduce the axial dispersion associated with the siphoning effect. The incremental benefit and tradeoff of geometric complexity was also evaluated. The improvement offered by topographically patterned channels, such as finned structures, is especially pertinent in the development of preparative or semi-preparative scale electrokinetically driven separations, such as capillary electrophoresis and capillary electrochromatography, in which large cross sections of channels are required to achieve the needed volumetric throughput.     

A comparative investigation of the electrophoretic spectra of the gliadins of some varieties of wheat grown in the Republic of Uzbekistan

The gliadin fractions of six varieties of soft wheat grown in the Republic of Uzbekistan have been investigated by electrophoresis in PAAG. The varieties Sanzar-8 and Enbosh proved to be monogenetic with respect to the index studied, and the others were divided into 4–9 forms in relation to the electrophoretic spectra of their gliadins. Institute of Plant Genetics and Experimental Biology, Tashkent, fax (371) 64 22 30. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 818–820, November–December, 1988.     

In-vitro investigation on antiurolithiatic activity and phytochemical examination of Aerva lanata and Bryophyllum pinnatum: A comparative study

Using the titrimetry method, the researchers hope to discover the kidney stone dissolving properties of the ethyl acetate extracts of Bryophyllum pinnatum and Aerva lanata. The ethyl acetate extract of B. pinnatum has the ability to dissolve calcium oxalate crystals and exhibited strong antiurolithiatic properties, according to the findings. Both extracts outperformed the conventional medication Neeri in terms of antiurolithiatic activity. The phytochemicals included in both plant extracts were studied using HPLC analysis. As a result, ethyl acetate extract of B. pinnatum can be used as an alternative for the treatment of kidney stones in this investigation.     

Metabolomics study of the effect of Danggui Buxue Tang on rats with chronic fatigue syndrome

Danggui Buxue Tang (DBT), a traditional Chinese medicine (TCM) formula for ‘invigorating qi and enriching blood’, has been reported to produce a good effect on chronic fatigue syndrome (CFS). However, the related mechanism remains largely undetermined. This study devised a metabolomics approach with GC–MS combined with pattern recognition to estimate the extent to which DBT alleviated CFS induced by food restriction and force swimming in rats. After 4 weeks of treatment, the endurance capability of rats was significantly better, and the motionless time was significantly shorter in the DBT group than in the CFS model group. Moreover, the activities of superoxide dismutase and glutathione peroxidase increased, whereas the levels of malondialdehyde, interleukin 6, and tumor necrosis factor alpha decreased in the DBT treatment group. Fifteen significantly changed metabolites were observed in the serum of rats with CFS, which was reversed markedly by DBT treatment. Metabolic pathway analysis showed that DBT could possibly alleviate CFS in rats by regulating the biosynthesis of phenylalanine, tyrosine, and tryptophan and the metabolism of glycine, serine, threonine, glycerolipid, glyoxylate, dicarboxylate, and tyrosine. It was observed that the metabolism of glycine, serine, and threonine was most closely related to the improvement in CFS by DBT treatment. This study showed that DBT could improve CFS effectively, and metabolomics was a powerful means to gain insights into the TCM formulas against CFS.     

A fluorescence toolbox: A review of investigation of electrophoretic separations,process, and interfaces

This review focuses on fluorescence spectroscopy techniques for the investigation of electrophoretic separations. Fluorescence has been used as a sensitive detector for capillary, gel, and microchip electrophoresis for decades. However, advanced fluorescence methods can be used to study transport, interfacial phenomena, intermolecular and affinity interactions, and other processes that occur during separation. This so‐called spectroscopic toolkit can be implemented to understand fundamental behavior in electrophoresis and electrokinetic chromatography. Techniques such as fluorescence recovery after photobleaching, fluorescence correlation spectroscopy, and fluorescence anisotropy are discussed in relation to electrophoretic separations. Newer methods such as super‐resolution microscope are also introduced.     

A comparative semi-empirical study of the effect of ring ortho-substitution on the conformation of diphenylamine

An extensive theoretical study of the structural and energy properties of diphenylamine (DPA) and derivatives was carried out. The effect of ring substitution on geometrical parameters, inversion barriers and ionisation potentials was investigated for rings containing methyl, methoxy and chloro groups. The dihedral angles between phenyl rings and pyramidality of the nitrogen atom were also studied. Results were compared to the optimised geometry of the unsubstituted DPA. Calculations were carried out using the AM1 semi-empirical method.     

Insight into carbon nanotube effect on polymer molecular orientation: an infrared dichroism study

The effect of carbon nanotubes on polymer macromolecular orientation structure during stretching of syndiotactic polystyrene/carbon nanotube nanocomposite film was quantitatively studied for the first time by an infrared dichroism technique.     

The effect of titanium dioxide on the biochemical constituents of the brain of Zebrafish (Danio rerio): an FT-IR study

During recent years, the use of nanoparticles (NPs) in commercial products and industrial applications has increased greatly. One of the most widely used nanoparticles is titanium dioxide (nTiO(2)). It is a very versatile compound that has many uses, depending on its particle size. In the present paper an attempt is made to study the effect of TiO(2) nanoparticles and its bulk material on the biochemical constituents of the brain of Zebrafish (Danio rerio) by using FT-IR technique. FT-IR spectra reveals significant differences in absorbance intensities between the control and TiO(2) exposed brain tissues, reflecting alterations on the major biochemical constituents such as proteins, lipids and nucleic acids in the brain tissues of D. rerio due to TiO(2) exposure. The results further reveal that TiO(2) nanoparticles are more toxic than their bulk counterparts. The higher ratio of integrated area of carbonyl-to-CH(2) peaks (1743 cm(-1):1458 cm(-1)) observed in the present study in the nTiO(2) exposed brain tissues suggests that lipids are being oxidized. Since oxidation can cause an increase in carbonyls and a degradation of lipids, both of these changes could be contributed to the elevated ratio. Further, the observed decreasing ratio of integrated areas of both 1458 cm(-1):1542 cm(-1) and 1743 cm(-1):1542 cm(-1) in the TiO(2) exposed tissues suggests that lipid degradation predominates over carbonyl formation. The observed changes in the biochemical constituents in the brain tissues of D. rerio could be due to the overproduction of ROS.     

A preliminary study of isopropyl alcohol matrix effect and correction in ICP-MS

Isopropyl alcohol matrix effect was found to be element specific by using the defined matrix effect factor in ICP-MS,which could not be corrected by using the conventional internal reference method.Unlike the conventional internal reference method,the presented method allows for the analyte to behave differently from the internal reference under the influence of the matrix.     

Polyaniline and polypyrrole: A comparative study of the preparation

Aniline and pyrrole have been oxidized with ammonium peroxydisulfate in aqueous solutions, in the presence of equimolar quantities of hydrochloric acid. The oxidation of pyrrole was faster; the induction period typical of aniline oxidation was absent in the case of pyrrole. As the proportion of oxidant-to-monomer molar concentration increased up to 1.5, the yield increased in both cases. Similarities between the two oxidations are illustrated and discussed. The oxidant-to-monomer molar ratio 1.25 is proposed to be the optimum stoichiometry, in the accordance with the data published in the literature. The conductivities of the polymers prepared were only slightly dependent on the oxidant-to-monomer ratio in the range 0.3-1.5, and were of the order of 10⁰ S cm⁻¹ for polyaniline and ∼10⁻²-10⁻¹ S cm⁻¹ for polypyrrole. Outside this interval, the conductivity of both polymers was reduced. Polyaniline having conductivity ∼10 S cm⁻¹ was produced in solutions of phosphoric acid of various concentrations. On the contrary, the conductivity of polypyrrole was reduced as the concentration of phosphoric acid became higher. The type of protonation is discussed with the help of FTIR spectra by analyzing the ammonium salts obtained after deprotonation. Sulfate or hydrogen sulfate anions produced from peroxydisulfate always constitute a part of the counter-ions.     

A comparative study on the effect of carbon fillers on electrical and thermal conductivity of a cyanate ester resin

Carbon fillers including multi-walled carbon nanotubes (MWCNTs), carbon black (CB) and graphite were introduced in a cyanate ester (CE) resin, respectively. The effects of the fillers on the electrical and thermal conductivity of the resin were measured and analyzed based on the microscopic observations. MWCNTs, CB and graphite exhibited percolation threshold at 0.1 wt%, 0.5 wt% and 10 wt%, respectively. The maximal electrical conductivity of the composites was 1.08 S/cm, 9.94 × 10⁻³ S/cm and 1.70 × 10⁻⁵ S/cm. MWCNTs showed the best enhancement on the electrical conductivity. The thermal behavior of the composites was analyzed by calorimetry method. Incorporation of MWCNTs, CB and graphite increased the thermal conductivity of CE resin by 90%, 15% and 92%, respectively. Theoretical models were introduced to correlate the thermal conductivity of the CE/MWCNTs composite. The interfacial thermal resistance between CE resin and MWCNTs was 8 × 10⁻⁸ m²K/W and the straightness ratio was 0.2. The MWCNTs were seriously entangled and agglomerated. Simulation results revealed that thermal conductivity of the CE/MWCNTs composites can be substantially elevated by increasing the straightness ratio and/or filler content of MWCNTs.     

Insight into the topology effect on the diffusion of ethene and propene in zeolites: A molecular dynamics simulation study

Selectivity control is a difficult scientific and industrial challenge in methanol-to-olefins(MTO)conversion.It has been experimentally established that the topology of zeolite catalysts influenced the distribution of products.Besides the topology effect on reaction kinetics,the topology influences the diffusion of reactants and products in catalysts as well.In this work,by using COMPASS force-field molecular dynamics method,we investigated the intracrystalline diffusion of ethene and propene in four different zeolites,CHA,MFI,BEA and FAU,at different temperatures.The self-diffusion coefficients and diffusion activation barriers were calculated.A strong restriction on the diffusion of propene in CHA was observed because the self-diffusion coefficient ratio of ethene to propene is larger than 18 and the diffusion activation barrier of propene is more than 20 kJ/mol in CHA.This ratio decreases with the increase of temperature in the four investigated zeolites.The shape selectivity on products from diffusion perspective can provide some implications on the understanding of the selectivity difference between HSAPO-34 and HZSM-5 catalysts for the MTO conversion.     

A study of the effect of attenuation curvature on molecular correlation energies by introducing an explicit cutoff radius into two-electron integrals

We present a new attenuator function that can be applied to the Coulomb operator. Similar to the popular erf(omegar) attenuator, the function [erf(omega(r + r0)) + erf(omega(r - r0))]/2 divides the Coulomb potential into a singular short-range piece and a non-singular long-range piece. In our attenuator, omega controls the sharpness of the short-range/long-range division at r0. With r0 = 0, this reduces to erf(omegar), but the additional parameter allows more flexible adjustment of the potential, for physical and/or computational reasons. We present some illustrative results for a truncated MP2 method, where mean field effects are handled exactly and correlation is treated locally. This study indicates, somewhat expectedly, that the slope and curvature of the attenuated potential are more important than its value (a trivial constant may always be added to a potential). However, there are some surprising features of the data that suggest what bounds need to be put on the curvature of the attenuated potential in order to achieve reasonable physics. Conveniently, we find that our attenuator form has the ability to preserve the curvature of the Coulomb potential almost exactly at short range, allowing for the truncation of long-range interactions while preserving the local physics very well. The molecular integrals for the resultant operator can be done analytically over Gaussian basis functions, and the extensive algebraic manipulations necessary to evaluate them stably are shown.     

Theoretical investigation on electron transport through an organic molecule: effect of the contact structure

Knowing how the contact geometry influences the conductance of a molecular wire junction requires both a precise determination of the molecule/metallic-electrode interface structure and an evaluation of the conductance for different contact geometries with a fair accuracy. With a greatly improved method to solve the Lippmann-Schwinger equation, we are able to include at least one atomic layer of each electrode into the extended molecule. The artificial effect of the jellium model used for the electrodes is therefore significantly reduced. Our first-principles calculations on the transport properties of a single benzene dithiolate molecule sandwiched between Au(111) surfaces show that the transmission of the bridge site contact, which is the most stable adsorption configuration in equilibrium, displays different features from those of other configurations, and that the inclusion of the surface layers of Au electrodes into the extended molecule shifts and broadens the transmission peaks due to a stronger and more realistic S-Au bonding. We discuss the geometry dependence of the transport properties by analyzing the density of states of the molecular orbitals.     

A comparative study on the antioxidant properties of tetrahydrocurcuminoids and curcuminoids

Several curcuminoids and tetrahydrocurcuminoids (THCs), bearing various hydroxyl and/or methoxy groups on their benzene rings, have been synthesized to study their antioxidant and hydrogen donating capacities using the DPPH method at 25 °C in methanol. The results show that the tetrahydrocurcuminoids are in general much more efficient than their curcuminoid analogs if they include a phenol group in meta- or para-position of the linking chain and a neighboring phenol or methoxy group. This efficiency gain of THCs by comparison to curcuminoids was attributed to the presence of benzylic hydrogens involved in the oxidation process of these compounds and not to the beta-diketone moiety in the chain.     

A study of the mixing of a liquid into an elastomer

A low-melting alloy was mixed with SBR and carboxy-NBR on a rubber mill above its melting point, and changes in its state of dispersion were examined through an optical microscope. Solution of the resulting mix showed that many of the particles of alloy were of colloid size, and did not settle out. Repeated washing of the sediment with solvent could not separate all the rubber phase from the sediment, and a form of bound rubber is postulated.     

Encapsulation of porphyrins and chlorins in biodegradable nanoparticles: the effect of dye lipophilicity on the extravasation and the photothrombic activity. A comparative study

In the present work, we performed a preclinical inter-comparison study using several photosensitizers with the goal of optimizing photodynamic therapy (PDT) for the treatment of choroidal neovascularization (CNV) associated with age-related macular degeneration. The tested molecules were the porphyrins meso-tetraphenylporphyrin (TPP) and meso-tetra-(4-carboxyphenyl)-porphyrin (TCPP), and the chlorins pheophorbide-a (Pheo-a) and chlorin e(6) (Ce(6)). Each of these molecules was entrapped in biodegradable nanoparticles (NP) based on poly(d,l-lactic acid). The influence of the degree of lipophilicity on the incorporation efficiency of the drug in the NPs, and on the dye leakage from blood vessels as well as on the photothrombic efficiency was investigated using the chick chorioallantoic membrane (CAM) as in vivo model. NP characterization showed that the dye was more effectively entrapped in the polymeric matrix when its degree of lipophilicity increased. While less lipophilic compounds (TCPP, Ce(6)) extravasate rather easily, the more lipophilic dyes (TPP, Pheo-a) tend to remain inside the blood vessels. After injection of a drug dose of 1 mg/kg body weight and a drug-light application interval of 1 min, irradiation with light doses ranging from 5 to 20 J/cm(2) led to the highest photothrombic efficiency when using the NPs loaded with the most lipophilic molecule (TPP). The latter induced vascular damage, which was significantly higher than that observed with the other molecules tested. Thus, in addition to minimal leakage from blood vessels, the TPP in NP formulation exhibited photothrombic efficiency similar to Visudyne which was also tested in the CAM model.