Roles of Lys191 and Lys179 in regulating thermodynamic binding forces of ligands to determine their binding affinity for human histamine H1 receptors.

Docking simulations based on the crystal structure of human histamine H1 receptors have predicted crucial roles of Lys1915.39 and Lys179ECL2, which exist at the entrance of the ligand-binding pocket, in increasing the H1-receptor selectivity for carboxylated second-generation antihistamines via electrostatic interaction. In this study, we evaluated the roles of Lys1915.39 and Lys179ECL2 in regulating the thermodynamic binding forces of non-carboxylated and carboxylated antihistamines that determine their binding affinity for human H1 receptors. The binding enthalpy and entropy of the 3 sets of non-carboxylated and corresponding carboxylated antihistamines (doxepin and olopatadine, desloratadine and loratadine, and terfenadine and fexofenadine, respectively) were estimated using the van't Hoff equation with the dissociation constants obtained from the displacement curves of the non-carboxylated and carboxylated antihistamines against the binding of [3H]mepyramine to the membrane preparations of Chinese hamster ovary cells expressing human H1 receptors at various temperatures, ranging from 4 °C to 37 °C. We found that the affinity for carboxylated antihistamines was lower than that for the corresponding non-carboxylated compounds due to lower enthalpy-dependent electrostatic binding forces and/or entropy-dependent hydrophobic binding forces. Mutations of Lys1915.39 and/or Lys179ECL2 to alanine mostly increased the binding affinity for antihistamines due to a variety of changes in both enthalpy- and entropy-dependent binding forces. These results suggest that Lys1915.39 and Lys179ECL2 may not contribute to selectively increasing the binding affinity for carboxylated antihistamines via electrostatic interaction, but that they can negatively modulate the binding affinity for non-carboxylated and carboxylated antihistamines non-selectively by affecting their electrostatic as well as hydrophobic binding forces.

Organic dicarboxylate negative electrode materials with remarkably small strain for high-voltage bipolar batteries.

As advanced negative electrodes for powerful and useful high-voltage bipolar batteries, an intercalated metal-organic framework (iMOF), 2,6-naphthalene dicarboxylate dilithium, is described which has an organic-inorganic layered structure of π-stacked naphthalene and tetrahedral LiO4 units. The material shows a reversible two-electron-transfer Li intercalation at a flat potential of 0.8 V with a small polarization. Detailed crystal structure analysis during Li intercalation shows the layered framework to be maintained and its volume change is only 0.33%. The material possesses two-dimensional pathways for efficient electron and Li(+) transport formed by Li-doped naphthalene packing and tetrahedral LiO3C network. A cell with a high potential operating LiNi(0.5)Mn(1.5)O4 spinel positive and the proposed negative electrodes exhibited favorable cycle performance (96% capacity retention after 100 cycles), high specific energy (300 Wh kg(-1)), and high specific power (5 kW kg(-1)). An 8 V bipolar cell was also constructed by connecting only two cells in series.

Reformation of organic dicarboxylate electrode materials for rechargeable batteries by molecular self-assembly.

We have found that the specific capacity of a Li-intercalated metal-organic framework (iMOF) electrode material, 2,6-naphthalene dicarboxylate dilithium, can be increased by narrowing the distance between naphthalene layers via ordering. The increase in specific capacity can be attributed to formation of more efficient electron and ion pathways in the framework.

Comparison of the characteristics of small commercial NDIR CO2 sensor models and development of a portable CO2 measurement device.

Many sensors have to be used simultaneously for multipoint carbon dioxide (CO(2)) observation. All the sensors should be calibrated in advance, but this is a time-consuming process. To seek a simplified calibration method, we used four commercial CO(2) sensor models and characterized their output tendencies against ambient temperature and length of use, in addition to offset characteristics. We used four samples of standard gas with different CO(2) concentrations (0, 407, 1,110, and 1,810 ppm). The outputs of K30 and AN100 models showed linear relationships with temperature and length of use. Calibration coefficients for sensor models were determined using the data from three individual sensors of the same model to minimize the relative RMS error. When the correction was applied to the sensors, the accuracy of measurements improved significantly in the case of the K30 and AN100 units. In particular, in the case of K30 the relative RMS error decreased from 24% to 4%. Hence, we have chosen K30 for developing a portable CO(2) measurement device (10 × 10 × 15 cm, 900 g). Data of CO(2) concentration, measurement time and location, temperature, humidity, and atmospheric pressure can be recorded onto a Secure Digital (SD) memory card. The CO(2) concentration in a high-school lecture room was monitored with this device. The CO(2) data, when corrected for simultaneously measured temperature, water vapor partial pressure, and atmospheric pressure, showed a good agreement with the data measured by a highly accurate CO(2) analyzer, LI-6262. This indicates that acceptable accuracy can be realized using the calibration method developed in this study.

Expression of an RSV-gag virus-like particle in insect cell lines and silkworm larvae.

Rous sarcoma virus group antigen protein-based virus-like particles (VLPs) are well known for their structural integrity and ease of handling. VLPs play an important role in drug delivery systems because they can be manipulated with ease. In this study, a new method was established for expressing Rous sarcoma virus group antigen protein based VLPs in silkworm larvae and establishing stably expressing insect cell lines. These VLPs have been isolated by ultracentrifugation using a sucrose step gradient of 10-60% (v/v), and their spherical structure has been confirmed using transmission electron microscopy (TEM). The spherical morphology is similar in both the silkworm larvae and in stably expressing cell lines. Silkworm larvae are better suited for producing Rous sarcoma virus group antigen protein-based VLPs on a large scale; yields from silkworm larvae were approximately 8.2-fold higher than yields from stable cell lines. These VLPs provide a new method for large-scale application in vaccine development and drug delivery systems.

Identification of hydroxyl radicals after UV irradiation of aqueous extracts of cigarette smoke and evaluation of urinary 8-OHdG in smokers.

The role of oxidative stress in tobacco smoke damage was examined using a combination of in vitro and in vivo approaches. Aqueous extracts of cigarette smoke were irradiated with UV and hydroxyl radical generation was evaluated by electron spin resonance (ESR). The spectra obtained revealed spin adducts of the hydroxyl radical (*OH) to increase with the volume of the aqueous extract of cigarette smoke, cigarette smoke collection flow, and UV irradiation time. Hydroxyl radical generation persisted for long hours, showing no change over time. Ascorbic acid protected against radical generation in a marked concentration-dependent fashion. In specimens of urine from volunteers, 8-OHdG levels and the 8-OHdG-production rate per hour were found to be higher in smokers than non-smokers. Our results suggest that more marked oxidative stress occurs with the smoking habit.