A genetic adaptive pattern＊low hemoglobin concentration in the himalayan highlanders

Mean hemoglobin （Hb） concentration of about 3 500 subjects derived from 17 studies of Himalayan highlanders （Tibetans, Sherpas, and Ladakhis） was compared with lowlanders （Chinese Han, Indian Tamils） lived in the Himalayas, and European climbers during Everest expeditions as well as Andean natives. The results found that Hb concentration in Himalayan highlanders was systemically lower than those reported for Andean natives and lowland immigrants. These comparative data demonstrated that a healthy native population may successfully reside at high altitude without a significant elevation in Hb, and the lower Hb levels of Himalayan highlanders than those of migrated lowlanders and Andean natives are an example of favourable adaptation over the generations. In addition, excessive polycythemia has frequently been used as a marker of chronic mountain sickness （CMS）. Altitude populations who have a higher Hb concentration also have a higher incidence of CMS. The low Hb in Himalayans suggested as showing adaptation over many generations in Tibetan stock. Recent work in Tibet, suggested that Tibetans there may have adapted to high altitude as a result of evolutionary pressure selecting for genes which give an advantage at altitude. All of the population genomic and statistical analysis indicated that EPAS1 and EGLN1 are mostly likely responsible for high altitude adaptation and closely related to low Hb concentration in Tibetans. These data supported the hypothesis that Himalayan highlanders have evolved a genetically different erythropoietic response to chronic hypoxia by virtue of their much longer exposure to high altitude.     

Monoamine-dependent Production of Reactive Oxygen Species Catalyzed by Pseudoperoxidase Activity of Human Hemoglobin

Hemoglobin (Hb) solution-based blood substitutes are being developed as oxygen-carrying agents for the prevention of ischemic tissue damage and low blood volume-shock. However, the cell-free Hb molecule has intrinsic toxicity to the tissue since harmful reactive oxygen species (ROS) are readily produced during autoxidation of Hb from the ferrous state to the ferric state, and the cell-free Hb also causes distortion in the oxidant/antioxidant balance in the tissues. There may be further hindering dangers in the use of free Hb as a blood substitute. It has been reported that Hb has peroxidase-like activity oxidizing peroxidase substrates such as aromatic amines. Here we observed the Hb-catalyzed ROS production coupled to oxidation of a neurotransmitter precursor, β-phenylethylamine (PEA). Addition of PEA to Hb solution resulted in generation of superoxide anion (O₂^??). We also observed that PEA increases the Hb-catalyzed monovalent oxidation of ascorbate to ascorbate free radicals (Asc^?). The O₂^?? generation and Asc^? formation were detected by O₂^??-specific chemiluminescence of the Cypridina lucigenin analog and electron spin resonance spectroscopy, respectively. PEA-dependent O₂^?? production and monovalent oxidation of ascorbate in the Hb solution occurred without addition of H₂O₂, but a trace of H₂O₂ added to the system greatly increased the production of both O₂^?? and Asc^?. Addition of GSH completely inhibited the PEA-dependent production of O₂^?? and Asc^? in Hb solution. We propose that the O₂^?? generation and Asc^? formation in the Hb solution are due to the pseudoperoxidase activity-dependent oxidation of PEA and resultant ROS may damage tissues rich in monoamines, if the Hb-based blood substitutes were circulated without addition of ROS scavengers such as thiols.     

Evolution of alternative insect life histories in stochastic seasonal environments

Deterministic seasonality can explain the evolution of alternative life history phenotypes (i.e., life history polyphenism) expressed in different generations emerging within the same year. However, the influence of stochastic variation on the expression of such life history polyphenisms in seasonal environments is insufficiently understood. Here, we use insects as a model and explore (1) the effects of stochastic variation in seasonality and (2) the life cycle on the degree of life history differentiation among the alternative developmental pathways of direct development and diapause (overwintering), and (3) the evolution of phenology. With numerical simulation, we determine the values of development (growth) time, growth rate, body size, reproductive effort, adult life span, and fecundity in both the overwintering and directly developing generations that maximize geometric mean fitness. The results suggest that natural selection favors the expression of alternative life histories in the alternative developmental pathways even when there is stochastic variation in seasonality, but that trait differentiation is affected by the developmental stage that overwinters. Increasing environmental unpredictability induced a switch to a bet‐hedging type of life history strategy, which is consistent with general life history theory. Bet‐hedging appeared in our study system as reduced expression of the direct development phenotype, with associated changes in life history phenotypes, because the fitness value of direct development is highly variable in uncertain environments. Our main result is that seasonality itself is a key factor promoting the evolution of seasonally polyphenic life histories but that environmental stochasticity may modulate the expression of life history phenotypes.     

3-Substituted-4-hydroxycoumarin as a new scaffold with potent CDK inhibition and promising anticancer effect: Synthesis,molecular modeling and QSAR studies

A new series of 3-substituted-4-hydroxycoumarin derivatives was designed, synthesized, and evaluated for CDK inhibiting and anticancer activities. All the synthesized target compounds showed remarkably high affinity and selectivity towards CDK1B, compared to flavopiridol, with Ki values in the low nanomolar range (Ki = 0.35–0.88 nM). Most of them elicited considerable inhibiting effect against CDK9T1 (Ki = 3.26–23.45 nM). Moreover, all the target compounds were tested in vitro against eighteen types of human tumor cell lines. The hydrazone 3a, N-phenylpyrazoline derivative 6b and 2-aminopyridyl-3-carbonitrile derivative 8c were the most potent anticancer agents against MCF-7 breast cancer cell line (IC₅₀ = 0.21, 0.21 and 0.23 nM, respectively). The target compounds 3a, 6b and 8c were further evaluated in MCF-7 breast cancer mouse xenograft model and showed in vivo efficacy at 10 mg/kg dose. The docking study confirmed a unique binding mode in the active site of CDK1B with better score than flavopiridol. Quantitative structure activity relationship study was done and revealed a highly predictive power R² of 0.81.     

A hidden aggregation‐prone structure in the heart of hypoxia inducible factor prolyl hydroxylase

Prolyl hydroxylase domain‐containing protein 2 (PHD2), as one of the most important regulators of angiogenesis and metastasis of cancer cells, is a promising target for cancer therapy drug design. Progressive studies imply that abnormality in PHD2 function may be due to misfolding. Therefore, study of the PHD2 unfolding pathway paves the way for a better understanding of the influence of PHD2 mutations and cancer cell metabolites on the protein folding pathway. We study the unfolding of the PHD2 catalytic domain using differential scanning calorimetry (DSC), fluorescence spectroscopy, and discrete molecular dynamics simulations (DMD). Using computational and experimental techniques, we find that PHD2 undergoes four transitions along the thermal unfolding pathway. To illustrate PHD2 unfolding events in atomic detail, we utilize DMD simulations. Analysis of computational results indicates an intermediate species in the PHD2 unfolding pathway that may enhance aggregation propensity, explaining mutation‐independent PHD2 malfunction. Proteins 2016; 84:611–623. © 2016 Wiley Periodicals, Inc.     

Solvation structure of sodium chloride (Na+–Cl-) ion pair in acetonitrile (AN)–dimethyl formamide (DMF) mixtures

Solvation structures of Na⁺–Cl^? ion pair are investigated in acetonitrile (AN)–dimethylformamide (DMF) isodielectric mixtures. The potentials of mean force of Na⁺–Cl^? in the five compositions of mixtures show minima corresponding to a contact ion pair (CIP) and a solvent-shared ion pair (SShIP). The solvent-separated ion pair minima are present in lower mole fractions of AN (x_AN ≤ 0.50). CIPs are found to be more stable than the SShIPs. From a thermodynamic decomposition of the potentials of mean force, we find that the formation of the ion pair is entropically driven in these compositions. The most stable CIP is in pure AN. The local solvation structures around the ion pair are analysed through the running coordination numbers, excess coordination numbers, solvent orientational distributions and density profiles. We find that both Na⁺ and Cl^? are preferentially solvated by DMF.     

Heme Orientation of Cavity Mutant Hemoglobins (His F8 → Gly) in Either α or β Subunits: Circular Dichroism, 1H NMR,and Resonance Raman Studies

Native human adult hemoglobin (Hb A) has mostly normal orientation of heme, whereas recombinant Hb A (rHb A) expressed in E. coli contains both normal and reversed orientations of heme. Hb A with the normal heme exhibits positive circular dichroism (CD) bands at both the Soret and 260‐nm regions, while rHb A with the reversed heme shows a negative Soret and decreased 260‐nm CD bands. In order to examine involvement of the proximal histidine (His F8) of either α or β subunits in determining the heme orientation, we prepared two cavity mutant Hbs, rHb(αH87G) and rHb(βH92G), with substitution of glycine for His F8 in the presence of imidazole. CD spectra of both cavity mutant Hbs did not show a negative Soret band, but instead exhibited positive bands with strong intensity at the both Soret and 260‐nm regions, suggesting that the reversed heme scarcely exists in the cavity mutant Hbs. We confirmed by ¹H NMR and resonance Raman (RR) spectroscopies that the cavity mutant Hbs have mainly the normal heme orientation in both the mutated and native subunits. These results indicate that the heme Fe‐His F8 linkage in both α and β subunits influences the heme orientation, and that the heme orientation of one type of subunit is related to the heme orientation of the complementary subunits to be the same. The present study showed that CD and RR spectroscopies also provided powerful tools for the examination of the heme rotational disorder of Hb A, in addition to the usual ¹H NMR technique. Chirality 28:585–592, 2016. © 2016 Wiley Periodicals, Inc.     

Molecular dynamics simulation of six β-blocker drugs passing across POPC bilayer

Six selected β-blocker drugs (alprenolol, atenolol, metoprolol, nadolol, pindolol and propranolol) passing across 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine bilayer were studied using all-atom molecular dynamics simulation. The free energy profiles can be divided into two groups, according to their shapes: the free energy curve of group one (atenolol, nadolol and pindolol) has an obvious minimum while that of the other group (propranolol, metoprolol and alprenolol) is flat inside membrane. Energy analysis shows that electrostatic interaction plays an important role for the first group drugs. The hydrogen bond analysis results also certify that the first group drugs form more hydrogen bonds than the other β-blockers. The calculated permeability sequence agrees with the experimental ones. Our calculation suggests that the permeability model using potential of mean force (PMF) method can be also applied to chemically similar compounds besides chemically diverse compounds.     

Comparison of three formal methods used to estimate the functional axis of rotation: an extensive in-vivo analysis performed on the knee joint

Estimating the main axis of rotation (AoR) of a human joint represents an important issue in biomechanics. This study compared three formal methods used to estimate functional AoR, namely a cylindrical fitting method, a mean helical axis transformation, and a symmetrical axis approach. These methods were tested on 106 subjects undergoing navigated total knee arthroplasty. AoR orientation in 3D and in the frontal and coronal planes provided by each method was compared to the transepicondylar axis direction. Although all the methods resulted effective, significant differences were identified among them, relatively to the orientation in 3D and in the frontal plane projection. This was probably due to the presence of secondary rotations during the first degrees of knee flexion.