Domain movement in rabbit muscle adenylate kinase might involve proline isomerization

AbstractThe fluorescence probe, 8-anilino-1-naphthalenesulfonic acid (ANS), was used to monitor the induced-fit conformational movement in rabbit muscle adenylate kinase. In 50 mM Tris-HCl buffer (pH 8.1), the time course of ANS binding to rabbit muscle adenylate kinase is a biphasic process. The fast phase completes within the dead-time of the stopped-flow equipment used (about 15 ms), while the slow phase ends in about 10 minutes. In the presence of 2.0 μM peptidyl prolyl cis/trans-isomerase, the rate constant of the slow phase reaction is accelerated about 2.4-fold, suggesting that the domain movement during ANS binding to rabbit muscle adenylate kinase may involve proline isomerization. The activation energy of the slow phase was determined to be 74.6 kJ/mol, which is comparable to the activation energy of proline cis/trans-isomerization (about 80 kJ/mol)

Self-nanomicellizing solid dispersion of edaravone: part I – oral bioavailability improvement

Background: Edaravone (EDR) is known for its free radical scavenging, antiapoptotic, antinecrotic, and anticytokine effects in neurological and non-neurological diseases. It is currently available clinically as Radicava® and Radicut®, intravenous medications, recently approved for the treatment of amyotrophic lateral sclerosis and cerebral infarction. However, the oral use of EDR is still restricted by its poor oral bioavailability (BA) due to poor aqueous solubility, stability, rapid metabolism, and low permeability. The present study reports the development of novel EDR formulation (NEF) using self-nanomicellizing solid dispersion (SNMSD) strategy with the aim to enable its oral use. Materials and methods: The selection of a suitable carrier for the development of NEF was performed based on the miscibility study. The optimization of EDR-to-carrier ratio was conducted via kinetic solubility study after preparing SNMSDs using solvent evaporation technique. The drug–polymer carrier interaction and self-nanomicellizing properties of NEF were investigated with advanced characterization studies. In vitro permeation, metabolism, and dissolution study was carried out to examine the effect of the presence of a carrier on physicochemical properties of EDR. Additionally, the dose-dependent pharmacokinetic study of NEF was conducted and compared with the EDR suspension. Results: Soluplus® (SOL) as a carrier was selected based on the potential for improving aqueous solubility. The NEF containing EDR and SOL (1:5) resulted in the highest enhancement in aqueous solubility (17.53-fold) due to amorphization, hydrogen bonding interaction, and micellization. Moreover, the NEF demonstrated significant improvement in metabolism, permeability, and dissolution profile of EDR. Furthermore, the oral BA of NEF showed 10.2-, 16.1-, and 14.8-fold enhancement compared to EDR suspension at 46, 138, and 414 µmol/kg doses. Conclusion: The results demonstrated that SNMSD strategy could serve as a promising way to enhance EDR oral BA and NEF could be a potential candidate for the treatment of diseases in which oxidative stress plays a key role in their pathogenesis.Ankit Parikh, Krishna Kathawala, Chun Chuan Tan, Sanjay Garg, Xin-Fu Zho

proBDNF inhibits the proliferation and migration of OLN-93 oligodendrocytes

In contrast with mature brain‑derived neurotrophic factor (mBDNF), proBDNF induces cell apoptosis. However, the function of proBDNF in oligodendrocytes remains unclear. In the present study, the OLN‑93 oligodendroglia cell line was utilized as an in vitro model to analyse the functions of proBDNF in oligodendroglia. p75NTR, sortilin and proBDNF were expressed in cultured OLN‑93 cells. It was indicated that proBDNF inhibited OLN‑93 cell proliferation in a dose‑dependent manner as determined using the MTT assay and BrdU staining. Furthermore, proBDNF suppressed the migration of OLN‑93 cells as demonstrated using the scratch assay. proBDNF also decreased cell viability and promoted apoptosis as indicated by activated cysteine‑aspartic acid protease‑3 (caspase‑3) immunocytochemistry. Notably, anti‑proBDNF treatment neutralized the effect of proBDNF and resulted in increased cell proliferation and migration and decreased apoptosis. However, these effects were not observed in the presence of recombinant p75NTR extracellular domain‑human FC fusion protein and p75NTR antibody, indicating that proBDNF imparts its inhibitory effects on oligodendrocytes through the p75NTR signal pathway.Shen Liu, Wei Guo, Hengxing Zhou, Liang Tang, Shiqing Feng, Jin-Hua Zhong, and Xi- Fu Zho

Detection of herb-symptom associations from traditional chinese medicine clinical data

YesTraditional Chinese medicine (TCM) is an individualized medicine by observing the symptoms and signs (symptoms in brief) of patients. We aim to extract the meaningful herb-symptom relationships from large scale TCM clinical data. To investigate the correlations between symptoms and herbs held for patients, we use four clinical data sets collected from TCM outpatient clinical settings and calculate the similarities between patient pairs in terms of the herb constituents of their prescriptions and their manifesting symptoms by cosine measure. To address the large-scale multiple testing problems for the detection of herb-symptom associations and the dependence between herbs involving similar efficacies, we propose a network-based correlation analysis (NetCorrA) method to detect the herb-symptom associations. The results show that there are strong positive correlations between symptom similarity and herb similarity, which indicates that herb-symptom correspondence is a clinical principle adhered to by most TCM physicians. Furthermore, the NetCorrA method obtains meaningful herb-symptom associations and performs better than the chi-square correlation method by filtering the false positive associations. Symptoms play significant roles for the prescriptions of herb treatment. The herb-symptom correspondence principle indicates that clinical phenotypic targets (i.e., symptoms) of herbs exist and would be valuable for further investigations

Spin-filtering and charge- and spin-switching effects in a quantum wire with periodically attached stubs

Spin-dependent electron transport in a periodically stubbed quantum wire in the presence of Rashba spin-orbit interaction (SOI) is studied via the nonequilibrium Green's function method combined with the Landauer-Buttiker formalism. The coexistence of spin filtering, charge and spin switching are found in the considered system. The mechanism of these transport properties is revealed by analyzing the total charge density and spin-polarized density distributions in the stubbed quantum wire. Furthermore, periodic spin-density islands with high polarization are also found inside the stubs, owing to the interaction between the charge density islands and the Rashba SOI-induced effective magnetic field. The proposed nanostructure may be utilized to devise an all-electrical multifunctional spintronic device.Comment: 4 pages, 4 figure

Knockout of p75 neurotrophin receptor attenuates the hyperphosphorylation of Tau in pR5 mouse model

p75 neurotrophin receptor (p75NTR) has been implicated in Alzheimer's disease (AD). However, whether p75NTR is involved in Tau hyperphosphorylation, one of the pathologies observed in AD, remains unclear. In our previous study, the extracellular domain of p75NTR blocked amyloid beta (Aβ) toxicity and attenuated Aβ-induced Tau hyperphosphorylation. Here we show that, in the absence of Aβ, p75NTR regulates Tau phosphorylation in the transgenic mice with the P301L human Tau mutation (pR5). The knockout of p75NTR in pR5 mice attenuated the phosphorylation of human Tau. In addition, the elevated activity of kinases responsible for Tau phosphorylation including glycogen synthase kinase 3 beta; cyclin-dependent-kinase 5; and Rho-associated protein kinase was also inhibited when p75NTR is knocked out in pR5 mice at 9 months of age. The increased caspase-3 activity observed in pR5 mice was also abolished in the absence of p75NTR. Our study also showed that p75NTR is required for Aβ- and pro-brain derived neurotrophin factor (proBDNF)-induced Tau phosphorylation, in vitro. Overall, our data indicate that p75NTR is required for Tau phosphorylation, a key event in the formation of neurofibrillary tangles, another hallmark of AD. Thus, targeting p75NTR could reduce or prevent the pathologic hyperphosphorylation of Tau.Noralyn B. Mañucat-Tan, Lin-Lin Shen, Larisa Bobrovskaya, Mohammed Al-hawwas, Fiona H. Zhou, Yan-Jiang Wang, Xin-Fu Zho

Effects of Exogenous Cellulase Source on In Vitro Fermentation Characteristics and Methane Production of Crop Straws and Grasses

In vitro fermentation experiments were conducted to investigate the effects of 3 sources of exogenous cellulase products (EC) at 4 dose rates (DR) (0, 12, 37 and 62 IU/g of DM) on degradation of forage and methane production by mixed rumen micro-organisms of goats. The maximum gas production (Vf) of grasses was higher (P<0.001) in Neocallimastix patriciarum (NP) group than those in Trichoderma reesei (TR) and Trichoderma longibrachiatum (TL) groups. Quadratic increases in dry matter degradation (DMD) of forage and neutral detergent fiber (NDFD) of straw were observed for all EC, with optimum DR in the low range. Supplementation of EC originated from TR and NP increased (P<0.001) DMD of forage compared to that from TL. Addition of EC originated from TR and NP also decreased pH value, ammonia nitrogen (NH3-N) and methane (CH4) production compared to that from TL. Quadratic decreases in pH value, NH3-N and CH4 of forage were noted for EC of TR and NP, and with optimum DR in the low range. For short chain fatty acid, the EC of NP increased total volatile fatty acid (TVFA) and acetate concentration and the ratio of acetate to propionate of forage compared with EC of TL and TR, and with optimum DR in the low to medium range. It was concluded that the source of EC differed in fiber degradation and methane emission, and with optimum DR of TR in the low range (from 12 to 37 U/g DM) in improving fiber degradation and decreasing methane emission

Fatigue Strength and Life Prediction of a MAR-M247 Nickel-Base Superalloy Gas Turbine Blade with Multiple Carbide Inclusions

Casting of a gas turbine blade from MAR-M247 nickel-base superalloy is followed by multiple carbide precipitates as a result of solidification. The microstructure of carbide was established with scanning electron microscopy and energy spectrum analysis. A finite element model simulating the blade with a random carbide precipitate is constructed using ANSYS software, and stress-strain evaluation is performed. The blade operation conditions are realized in a vibratory-tensile combined test setup with stress measurements using strain gauges arranged on different parts of the blade. The respective von Mises equivalent stresses obtained in simulation and test measurements are found to be comparable and can be used to assess the blade fatigue life based on the available fatigue curves and Palmgren–Miner rule of damage accumulation. Simulation and experimental results are the basis for plotting the relationship between the volumetric ratio of precipitates in the blade and its fatigue life. The results obtained at room temperature can; be extrapolated to the elevated ones to provide more reliable prediction of the superalloy blade fatigue and creep-fatigue life values.Литье лопатки газовой турбины из суперсплава на никелевой основе MAR-M247 сопровождается образованием множественных карбидных выделений в результате затвердевания. Микроструктуру карбида изучали с помощью сканирующей электронной микроскопии и энергетического спектрального анализа. Построена конечноэлементная модель лопатки со случайным карбидным выделением на основе программного обеспечения ANSYS, выполнена оценка напряженно-деформированного состояния. Условия эксплуатации лопатки реализовали на экспериментальной установке для комплексного испытания на вибрацию и растяжение, напряжения измеряли с помощью тензодатчиков, размещаемых на различных участках лопатки. Проведено сравнение эквивалентных напряжений по Мизесу, полученных при моделировании и экспериментально. Установлено, что их можно использовать для оценки усталостной долговечности лопатки на основании полученных кривых усталости и закона накопления повреждений Палмгрена Майлера. Они служат также основой построения зависимости между объемным соотношением включений в лопатке и ее усталостной долговечностью. Данные, полученные при комнатной температуре, могут быть экстраполированы на повышенные, что обеспечивает более достоверный прогноз усталости и усталостной долговечности лопатки из суперсплава при ползучести.Лиття лопатки газової турбіни з суперсплавів на нікелевої основі MAR-M247 супроводжується утворенням множинних карбідних виділень в результаті затвердіння. Мікроструктуру карбіду вивчали за допомогою скануючої електронної мікроскопії та енергетичного спектрального аналізу. Побудована скінченноелементна модель лопатки з випадковим карбідним виділенням на основі програмного забезпечення ANSYS, виконана оцінка напружено-деформованого стану. Умови експлуатації лопатки реалізували на експериментальній установці для комплексного випробування на вібрацію і розтягнення, напруги вимірювали за допомогою тензодатчиків, що розміщуються на різних ділянках лопатки. Проведено порівняння еквівалентних напружень по Мізесу, отриманих при моделюванні і експериментально. Встановлено, що їх можна використовувати для оцінки втомної довговічності лопатки на підставі отриманих кривих втоми і закону накопичення ушкоджень Палмгрена-Майлера. Вони служать також основою побудови залежності між об'ємним співвідношенням включень в лопатці і її втомної довговічністю. Дані, отримані при кімнатній температурі, можуть бути екстрапольовані на підвищені, що забезпечує більш достовірний прогноз втоми і втомної довговічності лопатки з суперсплавів при повзучості

Theory of ac electrokinetic behavior of spheroidal cell suspensions with an intrinsic dispersion

The dielectric dispersion, dielectrophoretic (DEP) and electrorotational (ER) spectra of spheroidal biological cell suspensions with an intrinsic dispersion in the constituent dielectric constants are investigated. By means of the spectral representation method, we express analytically the characteristic frequencies and dispersion strengths both for the effective dielectric constant and the Clausius-Mossotti factor (CMF). We identify four and six characteristic frequencies for the effective dielectric spectra and CMF respectively, all of them being dependent on the depolarization factor (or the cell shape). The analytical results allow us to examine the effects of the cell shape, the dispersion strength and the intrinsic frequency on the dielectric dispersion, DEP and ER spectra. Furthermore, we include the local-field effects due to the mutual interactions between cells in a dense suspension, and study the dependence of co-field or anti-field dispersion peaks on the volume fractions.Comment: accepted by Phys. Rev.

Non-Markovian dynamics in a spin star system: The failure of thermalization

In most cases, a small system weakly interacting with a thermal bath will finally reach the thermal state with the temperature of the bath. We show that this intuitive picture is not always true by a spin star model where non-Markov effect predominates in the whole dynamical process. The spin star system consists a central spin homogeneously interacting with an ensemble of identical noninteracting spins. We find that the correlation time of the bath is infinite, which implies that the bath has a perfect memory, and that the dynamical evolution of the central spin must be non- Markovian. A direct consequence is that the final state of the central spin is not the thermal state equilibrium with the bath, but a steady state which depends on its initial state.Comment: 8 page