At Least One-Third of Zeros of Riemann's Zeta-Function are on sigma = (1/2)

Starting from the derivative of the functional equation of the zeta-function, it is shown that at least one-third of the zeros of the zeta-function are on the line σ = ½.     

Asymptotic Formula for the Coordinates of the Zeros of Sections of the Zeta Function, zeta(N)(s), Near s = 1

The sum, Σ1^Nn^-8 = ζN(s), s = σ + it, is called a section of the Riemann zeta function, ζ(s). Here an asymptotic formula, for large N, giving the location of the zeros of ζN(s) near s = 1 will be demonstrated. In particular these zeros will lie in σ < 1. Relationships between the location of the zeros of ζN(s) and the zeros of ζ(s) were discovered by Turán. The location in σ < 1 will also be demonstrated directly, without the asymptotic formula, together with results valid also when s - 1 is not small.     

Expression, purification, and characterization of human hemoglobins Gower-1 (zeta(2)epsilon(2)), Gower-2 (alpha(2)epsilon(2)), and Portland-2 (zeta(2)beta(2)) assembled in complex transgenic-knockout mice

Embryonic zeta- and epsilon-globin subunits assemble with each other and with adult alpha- and beta-globin subunits into hemoglobin heterotetramers in both primitive and definitive erythrocytes. The properties of these hemoglobins-Hbs Gower-1 (zeta(2)epsilon(2)), Gower-2 (alpha(2)epsilon(2)), and Portland-2 (zeta(2)beta(2))-have been incompletely described as they are difficult to obtain in quantity from either primary human tissue or conventional expression systems. The generation of complex transgenic-knockout mice that express these hemoglobins at levels between 24% and 70% is described, as are efficient methods for their purification from mouse hemolysates. Key physiological characteristics-including P(50), Hill coefficient, Bohr effect, and affinity for 2,3-BPG-were established for each of the 3 human hemoglobins. The stability of each hemoglobin in the face of mechanical, thermal, and chemical stresses was also determined. Analyses indicate that the zeta-for-alpha exchange distinguishing Hb Portland-2 and Hb A alters hemoglobin O(2)-transport capacity by increasing its P(50) and decreasing its Bohr effect. By comparison, the epsilon-for-beta exchange distinguishing Hb Gower-2 and Hb A has little impact on these same functional parameters. Hb Gower-1, assembled entirely from embryonic subunits, displays an elevated P(50) level, a reduced Bohr effect, and increased 2,3-BPG binding compared to Hb A. The data support the hypothesis that Hb Gower-2, assembled from reactivated epsilon globin in individuals with defined hemoglobinopathies and thalassemias, would serve as a physiologically acceptable substitute for deficient or dysfunctional Hb A. In addition, the unexpected properties of Hb Gower-1 call into question a common hypothesis for its primary role in embryonic development.     

Acid-sensing ion channel (ASIC) 1a/2a heteromers have a flexible 2:1/1:2 stoichiometry

Acid-sensing ion channels (ASICs) are widely expressed proton-gated Na⁺ channels playing a role in tissue acidosis and pain. A trimeric composition of ASICs has been suggested by crystallization. Upon coexpression of ASIC1a and ASIC2a in Xenopus oocytes, we observed the formation of heteromers and their coexistence with homomers by electrophysiology, but could not determine whether heteromeric complexes have a fixed subunit stoichiometry or whether certain stoichiometries are preferred over others. We therefore imaged ASICs labeled with green and red fluorescent proteins on a single-molecule level, counted bleaching steps from GFP and colocalized them with red tandem tetrameric mCherry for many individual complexes. Combinatorial analysis suggests a model of random mixing of ASIC1a and ASIC2a subunits to yield both 2:1 and 1:2 ASIC1a:ASIC2a heteromers together with ASIC1a and ASIC2a homomers.Acid-sensing ion channels (ASICs) are proton-gated Na⁺ channels, which are probably ubiquitously expressed in neurons, yet surprisingly little is known about their physiological function in the brain (1). It is believed that ASICs localize to the postsynapse and carry an excitatory postsynaptic current (2). ASICs in central neurons are mainly composed of homomeric ASIC1a and heteromeric ASIC1a/2a (3–6) and ASIC1a/2b (7). Genetic ablation of ASIC1a has indeed led to the conclusion that ASICs contribute to long-term potentiation and memory formation (2), but a more recent study challenged these findings (8). In contrast to our incomplete understanding of the physiological functions of ASICs, there is a comparatively large body of evidence that activation of ASIC1a-containing channels in pathophysiological states that are associated with sustained acidosis contributes to neuronal or axonal degeneration (9, 10). In addition, blockade of the ASIC1a/2a heteromer causes central analgesia (11). Together, these findings render ASIC1a-containing channels attractive drug target candidates.The crystal structure of chicken ASIC1 revealed an acidic pocket at subunit interfaces, which has been proposed to be the ligand-binding site of ASICs (12). In agreement, it has recently been shown that a gating modifier toxin of ASIC1, psalmotoxin 1, which behaves like an agonist (13), binds at the acidic pocket at subunit interfaces (14–16). Therefore, knowing the subunit composition of the ASIC1a/2a heteromer is of major interest, in particular for pharmacologically targeting this subtype.Fluorescence resonance energy transfer analysis suggested that the ASIC1a/2a heteromer contains at least two ASIC1a and two ASIC2a subunits (17). In agreement, several studies reported that the related epithelial Na⁺ channel (ENaC) is composed of four (18–21) or nine subunits (22–24). In strong contrast, however, the crystal structure of chicken ASIC1 revealed a number of three subunits (12, 25), suggesting that all ASICs and their relatives like ENaC are trimers. The trimeric structure of ASIC1a has in the meanwhile been confirmed by atomic force microscopy imaging (26). The stoichiometry of heteromeric ASICs, however, remains completely unknown.In this study, we first used electrophysiology to characterize mixtures of ASIC1a and ASIC2a at different expression ratios in Xenopus laevis oocytes to demonstrate that at least one heteromeric channel forms. Because we were unable to decide on the existence of a second heteromeric species by electrophysiology, we used a single-molecule photobleaching approach that resolves stoichiometries of membrane proteins with high accuracy. We tagged ASIC1a and ASIC2a with green and red fluorescent reporter proteins, which did not change the electrophysiological characteristics of homo- and heteromeric ASICs, suggesting that fusion of a fluorescent reporter has no impact on the molecular composition of ASICs. Colocalization of red and green reporter tags on a single-molecule level and counting of green bleaching steps confirms the trimeric nature of functional ASICs and shows that ASIC1a and ASIC2a randomly assemble into a complex with a flexible stoichiometry of either 1:2 or 2:1.     

Embryonic pig hemoglobins Gower I (zeta 2 epsilon 2), Gower II (alpha 2 epsilon 2), Heide I (zeta 2 theta 2) and Heide II (alpha 2 theta 2): oxygen-binding functions related to structure and embryonic oxygen supply

The common pig lacks a fetal hemoglobin but has four embryonic hemoglobins: Gower I (zeta 2 epsilon 2), Gower II (alpha 2 epsilon 2), Heide I (zeta 2 theta 2) and Heide II (alpha 2 theta 2) as well as adult Hb A (alpha 2 beta 2) and the amino acid sequence for each of the five constituent polypeptide chains has been established. The oxygenation characteristics of the five components, measured in relation to pH, temperature and the erythrocytic ligand 2,3-diphosphoglycerate (DPG), together with the changes in their relative concentrations during early embryonic life, are given. The findings indicate a progressive decrease in maternal-fetal oxygen affinity difference and thus in oxygen transfer efficacy at a given diffusion gradient that correlates with the development of the gas exchange structures. The functional properties of the individual hemoglobins are additionally discussed in relation to molecular structure.     

Neonatal Alloimmune Thrombocytopenia due to Anti-HPA-1b (PLA2) (Zwb)

Background : Neonatal alloimmune thrombocytopenia is a rare condition due to passively acquired maternal antibodies directed against paternal platelet antigens inherited by the infant. Only 5 cases have been reported due to antibodies against HPA-lb (PL^A2) (Zw^b). Case Report : We report a case of neonatal alloimmune thrombocytopenia due to anti-HPA-lb in the second pregnancy of a 26-year-old Caucasian female. The male infant was treated with a 5-day course of intravenous immunoglobulin without complications. We report the HLA phenotype of the infant's mother and summarize the previous case reports due to anti-HPA-lb. Conclusion : Based on this case and a review of the literature, intravenous immunoglobulin as well as random donor exchange transfusion and random donor platelet transfusions are effective in the treatment of neonatal alloimmune thrombocytopenia due to anti-HPA-lb. Obvious associations between HLA alleles and sensitization to HPA-lb have not been elucidated.     

Cytoplasmic FMRP interacting protein 1/2 (CYFIP1/2) expression analysis in autism

Metabolic Brain Disease - Cytoplasmic FMRP interacting proteins 1 and 2 (CYFIP1/2) have been previously shown to be associated with central nervous system (CNS) disorders such as autism spectrum...     

Aspirin resistance in coronary artery disease is correlated to elevated markers for oxidative stress but not to the expression of cyclooxygenase (COX) 1/2, a novel COX-1 polymorphism or the PlA(1/2) polymorphism

Aspirin resistance (AR) is estimated to be present in 5-75% of patients and is related to increased cardiovascular mortality. However, the underlying mechanisms are mostly unknown. In the present study, AR was detected in 14 out of 55 patients (25%) with coronary artery disease. The presence of concomitant anti-inflammatory drugs did not affect AR. Plasma levels of thromboxane B(2) as well as the markers for oxidative stress and known platelet activators 8-isoprostane and lipid peroxidation products were significantly higher in aspirin-resistant individuals (349.3 pg/ml, 53.9 pg/ml, and 538 micromol/l) compared to controls (113.7 pg/ml, 10.3 pg/ml, and 32.2 micromol/l; P < 0.05, respectively). Platelet cyclooxygenase-1 (COX-1) and COX-2 mRNA and protein expression were without significant differences between the two groups. DNA sequencing detected a novel platelet COX-1 single nucleotide polymorphism (SNP) resulting in amino acid exchange at position 8 (Arg8/Trp8). The wild-type as well as the heterozygous and homozygous SNP were present in both patient groups without significant differences. The aspirin binding (Arg120) and acetylation site (Ser529) were unaffected in the samples tested. Neither was AR related to the platelet integrin PlA(1)/A(2) polymorphism. In conclusion, AR appears to be unrelated to differences in platelet COX-1 and COX-2 expression or to a novel platelet COX-1 SNP and the PlA(1)/A(2) SNP. However, a correlation exists to elevated eicosanoids generated by oxidative stress indicating COX-1-independent pathways for the generation of platelet activating molecules represent a potential cause for AR.     

Identification of GIT1/Cat-1 as a substrate molecule of protein tyrosine phosphatase zeta /beta by the yeast substrate-trapping system

We used a genetic method, the yeast substrate-trapping system, to identify substrates for protein tyrosine phosphatases zeta (PTPzeta/RPTPbeta). This method is based on the yeast two-hybrid system, with two essential modifications: conditional expression of protein tyrosine kinase v-src (active src) to tyrosine-phosphorylate the prey proteins and screening by using a substrate-trap mutant of PTPzeta (PTPzeta-D1902A) as bait. By using this system, several substrate candidates for PTPzeta were isolated. Among them, GIT1/Cat-1 (G protein-coupled receptor kinase-interactor 1/Cool-associated, tyrosine-phosphorylated 1) was examined further. GIT1/Cat-1 bound to PTPzeta-D1902A dependent on the substrate tyrosine phosphorylation. Tyrosine-phosphorylated GIT1/Cat-1 was dephosphorylated by PTPzeta in vitro. Immunoprecipitation experiments indicated that PTPzeta-D1902A and GIT1/Cat-1 form a stable complex also in mammalian cells. Immunohistochemical analyses revealed that PTPzeta and GIT1/Cat-1 were colocalized in the processes of pyramidal cells in the hippocampus and neocortex in rat brain. Subcellular colocalization was further verified in the growth cones of mossy fibers from pontine explants and in the ruffling membranes and processes of B103 neuroblastoma cells. Moreover, pleiotrophin, a ligand for PTPzeta, increased tyrosine phosphorylation of GIT1/Cat-1 in B103 cells. All these results indicate that GIT1/Cat-1 is a substrate molecule of PTPzeta.     

Both ERK1 and ERK2 Are Required for Enterovirus 71 (EV71) Efficient Replication

It has been demonstrated that MEK1, one of the two MEK isoforms in Raf-MEK-ERK1/2 pathway, is essential for successful EV71 propagation. However, the distinct function of ERK1 and ERK2 isoforms, the downstream kinases of MEKs, remains unclear in EV71 replication. In this study, specific ERK siRNAs and selective inhibitor U0126 were applied. Silencing specific ERK did not significantly impact on the EV71-caused biphasic activation of the other ERK isoform, suggesting the EV71-induced activations of ERK1 and ERK2 were non-discriminative and independent to one another. Knockdown of either ERK1 or ERK2 markedly impaired progeny EV71 propagation (both by more than 90%), progeny viral RNA amplification (either by about 30% to 40%) and protein synthesis (both by around 70%), indicating both ERK1 and ERK2 were critical and not interchangeable to EV71 propagation. Moreover, suppression of EV71 replication by inhibiting both early and late phases of ERK1/2 activation showed no significant difference from that of only blocking the late phase, supporting the late phase activation was more importantly responsible for EV71 life cycle. Taken together, this study for the first time identified both ERK1 and ERK2 were required for EV71 efficient replication and further verified the important role of MEK1-ERK1/2 in EV71 replication.     

Low-Thermal-Conductivity (MS)1+x(TiS2)2 (M = Pb,Bi, Sn) Misfit Layer Compounds for Bulk Thermoelectric Materials

A series of (MS)_1+x(TiS₂)₂ (M = Pb, Bi, Sn) misfit layer compounds are proposed as bulk thermoelectric materials. They are composed of alternating rock-salt-type MS layers and paired trigonal anti-prismatic TiS₂ layers with a van der Waals gap. This naturally modulated structure shows low lattice thermal conductivity close to or even lower than the predicted minimum thermal conductivity. Measurement of sound velocities shows that the ultra-low thermal conductivity partially originates from the softening of the transverse modes of lattice wave due to weak interlayer bonding. Combined with a high power factor, the misfit layer compounds show a relatively high ZT value of 0.28~0.37 at 700 K.     

Construction of a human platelet alloantigen-1a epitope(s) within murine glycoprotein IIIa: identification of residues critical to the conformation of the antibody binding site(s)

The human platelet alloantigen 1 system (HPA-1) is determined by a polymorphism at position 33 in the N-terminus of human glycoprotein IIIa (GPIIIa). This naturally occurring substitution creates a conformation in the HPA-1a allelic form that can be antigenic when presented to an individual expressing the HPA-1b form. Anti-HPA-1a antibodies generated by this immune response can lead to the destruction of platelets, as seen in the clinical disorders, neonatal alloimmune thrombocytopenia (NAIT) and posttransfusion purpura (PTP). To understand better the structural requirements for recognition by these pathogenic antibodies, we investigated the N-terminal 66 amino acids from the HPA-1a form of human GPIIIa and the analogous amino acids from the nonimmunogenic murine homolog. Our objectives were to define further the boundaries of the HPA-1a epitope(s) in the N-terminus of human GPIIIa, to isolate the murine 5' nucleotide sequence and compare the deduced murine N-terminal sequence to that of human, and to mutate the murine sequence systematically to include an HPA-1a epitope(s). Murine amino acids that differed from human were changed by site-directed mutagenesis to the analogous residues in the HPA-1a form of human GPIIIa, starting and radiating from murine position 33 (site of human polymorphism). This systematic approach allowed us to pinpoint amino acids critical to a conformation recognized by anti-HPA-1a antibodies. Our results show that an HPA-1a epitope can be created within the N-terminus of murine GPIIIa and raise the possibility that murine models of HPA-1a sensitization can be developed.