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In recent years dynamic nuclear polarization (DNP) has greatly expanded the range of materials systems that can be studied by solid state NMR spectroscopy. To date, the majority of systems studied by DNP were insulating materials including organic and inorganic solids. However, many technologically-relevant materials used in energy conversion and storage systems are electrically conductive to some extent or are employed as composites containing conductive additives. Such materials introduce challenges in their study by DNP-NMR which include microwave absorption and sample heating that were not thoroughly investigated so far. Here we examine several commercial carbon allotropes, commonly employed as electrodes or conductive additives, and consider their effect on the extent of solvent polarization achieved in DNP from nitroxide biradicals. We then address the effect of sample conductivity systematically by studying a series of carbons with increasing electrical conductivity prepared via glucose carbonization. THz spectroscopy measurements are used to determine the extent of μw absorption. Our results show that while the DNP performance significantly drops in samples containing the highly conductive carbons, sufficient signal enhancement can still be achieved with some compromise on conductivity. Furthermore, we show that the deleterious effect of conductive additives on DNP enhancements can be partially overcome through pulse-DNP experiments.

A new and efficient method for orientation echo spectroscopy is presented and realized experimentally. The excitation scheme utilizes concerted rotational excitations by both ultrashort terahertz and near-IR pulses and its all-optical detection is enabled by the molecular orientation-induced second harmonic method [J. Phys. Chem. A 126, 3732 (2022)10.1021/acs.jpca.2c03237]. This method provides practical means for orientation echo spectroscopy of gas phase molecules and highlights the intriguing underlying physics of coherent rotational dynamics induced by judiciously-orchestrated interactions with both resonant (terahertz) and nonresonant (NIR) fields.

This essay examines the policy response of the federal and regional governments in federations to the COVID-19 crisis. We theorize that the COVID-19 policy response in federations is an outcome of strategic interaction among the federal and regional incumbents in the shadow of their varying accountability for health and the repercussions from the disruptive consequences of public health measures. Using the data from the COVID-19 Public Health Protective Policy Index Project, we study how the variables suggested by our theory correlate with the overall stringency of public health measures in federations as well as the contribution of the federal government to the making of these policies. Our results suggest that the public health measures taken in federations are at least as stringent as those in non-federations, and there is a cluster of federations on which a bulk of crisis policy making is carried by subnational governments. We find that the contribution of the federal government is, on average, higher in parliamentary systems; it appears to decline with the proximity of the next election in presidential republics, and to increase with the fragmentation of the legislative party system in parliamentary systems. Our analysis also suggests that when the federal government carries a significant share of responsibility for healthcare provision, it also tends to play a higher role in taking non-medical steps in response to the pandemic.

Selection of resistant clones following intensive chemotherapy is a common obstacle for cure in many cancers, particularly in acute myeloid leukemia (AML). In AML, clone-specific sensitivity to chemotherapy varies even within the same patient. Multiple mutations and genetic aberrations are associated with clones surviving chemotherapy. The current study explored the role of activated signaling pathways in chemoresistance as a function of cell maturation, reflected by CD34 expression. In-vitro, Kasumi-1 leukemic cell line, sorted by CD34 expression, showed increased apoptosis only in the CD34− subpopulation after exposure to cytosine arabinoside (Ara-C) or daunorubicin. The resistant CD34+ subset demonstrated higher expression of ERK1/2 and BCL-2 proteins than CD34− cells. MEK1/2 inhibition elevated Ara-C ability to induce apoptosis in CD34+ cells, suggesting that MEK1/2-ERK1/2 is surviving signaling, which correlates to cell maturation levels and plays a role in chemoresistance. Deep sequencing of sorted CD34+/− populations, both derived from the same patient samples, demonstrated various subclonal distribution of NPM1, DNMT3A and FLT3-ITD mutations. Interestingly, in these samples, p-ERK levels and apoptosis rates following chemotherapy exposure significantly differed between CD34+/− populations. Hence, clones may be selected due to their ability to escape apoptosis rather than a direct effect of chemotherapy on a specific mutated clone.

Despite numerous studies on whether democracy reduces the infant mortality rate (IMR), the empirical results remain mixed at best. In this article, I perform several theoretical and empirical exercises that help explain why and under what conditions we should expect politics to matter most for a decrease in IMR. First, I capitalize on the epidemiological view that IMR – the most commonly used indicator of health in social sciences – is better suited to reflect public health micromanagement than overall social development. Second, I theorize that autocrats have incentives to invest in health up to a certain point, which could lead to a reduction in IMR. Third, I introduce an omitted variable – good governance – that trumps the importance of a political regime for IMR: (1) it directly affects public health micromanagement, and (2) many autocrats made inroads in achieving good governance. Finally, for the first time in such research, I use a disaggregated IMR approach to corroborate my hypotheses.

This paper investigates the effect of political regimes on healthcare outcomes with a novel approach. Instead of focusing on cross-country comparisons, like most studies do, we utilize the within-country variation of political regimes across individual regions. We use the case of the Russian Federation, where large sub-national differences exist in both health outcomes and political regimes in different provinces. General differences in sub-national politics in Russia have been subject of investigation of a large literature our paper adds to. The paper shows that the effect of political regimes on health is heterogeneous and depends on the type of health problems more salient for the region. More pluralist and competitive regimes are able to produce better results than the less competitive ones in rich regions, while in poor regions political pluralism and competition have an adverse impact on health.

Although there is a broad consensus among political scientists that polarization is detrimental to democracy, very few empirically investigate the links between political polarization and democratic erosion. Most studies use diversity measures that fail to capture contemporary polarization, where the society is divided into two large hostile camps. In this article, we address the gap. Theoretically, we argue that polarization increases animosity between “enemy camps,” making voters more willing to accept anti-democratic measures against the rival group. This tacit approval becomes even more pronounced during election periods, where political controversy reigns and the stakes are higher. Focusing on a specific type of electoral manipulation, we hypothesize that ceteris paribus, political polarization is strongly associated with higher levels of government intimidation of the opposition. We expect this relationship to be stronger in democracies than in autocracies. Empirically, we create our own measure of political polarization based on Esteban and Ray’s widely accepted measure, and test our hypotheses on panel data. In addition to the regression analysis, we offer anecdotal evidence from Turkey, Hungary, and the United States.

Conventional wisdom holds that natural resource abundance negatively affects economic development, especially in countries with weak quality of governance. In this paper we raise a related, yet separate, question that was largely overlooked in the literature - the effect of natural resource rents on technological innovations, a very specific type of economic activity. We argue that the abundance of natural resources negatively affects technological innovations, but only under authoritarian settings. Technological innovations are risky, costly, long-term and partially public goods (an idea cannot be taken back), which makes them disproportionately disadvantaged in resource-rich authoritarian countries. First, alternative economic activity is too attractive to miss out on: steady, high and short-term profits from natural resources. Second, authoritarian leaders are infamous for not encouraging or even blocking technological innovations because they redistribute political power away from the leaders (old elites) to newcomers (innovators). We corroborate our hypothesis on the extensive cross-section time-series data.

We propose and experimentally validate the use of rotational echo responses for obtaining the degree of molecular alignment induced in a gas. The method is independent of various parameters that are hardly accessible in most experimental configurations such as the effective length of interaction and the gas density as it relies on the intrinsic, self-contained dynamics of the rotational echo response., Comment: 11 pages

The rotational echo response of molecules is found to strongly depend on the delay between the two ultrashort laser pulses, as opposed to two-level systems. We study this dependence experimentally and theoretically and show that by judicious control of the 2nd pulse intensity, 'rotational echo spectroscopy' in a multi-level molecular system becomes possible., 12 pages (including supplementary information)

Rephasing the rotational centrifugal effect by laser-induced alignment echoes[1] Dina Rosenberg1,2, Ran Damari1,2, Shimshon Kallush3,4 and Sharly Fleischer1,2 1 Raymond and Beverly Sackler Faculty of Exact Sciences, School of Chemistry, Tel Aviv University, Tel Aviv 6997801, Israel 2 Tel-Aviv University Center for Light-Matter Interaction, Tel Aviv 6997801, Israel 3 Department of Physics and Optical Engineering, ORT Braude College, P.O. Box 78, Karmiel 21982, Israel 4 The Fritz Haber Research Center and The Institute of Chemistry, The Hebrew University, Jerusalem 91904, Israel Echo spectroscopy is a central technique in magnetic resonance, electronic and vibrational spectroscopy, enabling researchers to distinguish dynamical dephasing from decoherence phenomena. The interest in echo responses for gas phase rotational spectroscopy is gradually increasing in recent years, with theoretical and experimental results utilizing resonant terahertz fields and non-resonant optical fields to induce a variety of echo responses in multi-level rotational systems. In the talk I will focus on the rephasing property of rotational echoes induced by two ultrashort optical pulses in a gas phase ensemble of molecules. Different from two-level systems associated with a single transition frequency, multilevel rotational systems manifest quantum rotational revivals due to the unique harmonic rotational level spacing. Thus, following their excitation by an ultrashort optical pulse, the molecules demonstrate periodic rotational dynamics with a long series of alignment events persisting under field-free conditions. However, due to the finite rigidity of the molecules (centrifugal distortion) the molecules experience significant dephasing and distortion of the alignment signal with time and the alignment events become gradually longer in duration and with increasing number of oscillations. When applying the second optical pulse after a delay of a few rotational revivals, the accumulated dephasing in the signal is significant and therefore also visible in the echo signal. The first echo signal appears with the same dephasing, only in the reversed phase-time direction. Since the echo manifests the same periodicity as the fundamental revivals, the rephasing its signal occurs gradually in every appearance. When reaching the zero echo signal, at twice the delay between the pulses, the rephasing is complete. Afterwards, the echo signal continues to diphase jointly with the already non-rephasing fundamental revivals. In my talk I will also discuss the dependence of the echo signal on the intensities of the driving pulses and present a quantum-mechanical version of Hahn's famous track-runners analogy to spin echoes [2]. References: [1] D. Rosenberg, R. Damari, S. Kallush, and S. Fleischer, J. Phys. Chem. Lett. 8 ,5128 (2017). [2] E. L. Hahn, “Spin Echoes,” Phys. Rev. 80, 580 (1950).

Intense terahertz (THz) pulses with MV/cm peak-field amplitudes have become experimentally feasible with the advents in table-top THz generation methodologies. Such fields provide a new control-handle over the rotations of polar molecules in the gas phase, as they primarily interact with molecular rotors via their permanent dipole moments, differing yet complementing ultrashort optical pulses that interact with molecules via their polarizability tensor. When applied to linear molecules, optical pulses induce molecular ALIGNMENT while THz pulses induce ORIENTATION. In linear molecules both the dipole vector and the most polarizable axis coincide at the inter-atomic axis of the molecule, thus serving to rotate the molecules about the same axis. However, for asymmetric tops like SO2, the dipole and the most polarizable axes lie along different molecular frame axes, turning optical and THz fields as two distinct rotational handles. Well-orchestrated application of these pulses can provide complete three-dimensional control over the molecular angular distribution of such molecules - a long standing goal in molecular physics and chemistry. In the first part of the talk I will present our recent experimental and theoretical results of optical induced alignment and THz induced orientation in gas phase SO2 molecules that highlight the different rotational dynamics induced by these two distinct rotational handles. On the theoretical front, simulating the rotational dynamics of asymmetric molecules like SO2 at room temperature remains a highly demanding computational task that is effectively impossible by exact methods for dynamics. We overcame this issue by employing the Random Phase Wave Functions method [1,2] that was also verified by experimental results [3]. In the second part I will present a decay phenomenon that was recently unveiled in by a series of time-resolved measurements of the rotational dynamics induced by an optical pulse and a THz-field. We have found that despite their exact same pressure and temperature, transiently oriented molecules decay at a faster rate than aligned molecules [4]. This is attributed a coherent radiative decay mechanism that we believe is general to all resonantly induced dynamics, however has been discarded previously. I will present our recent experimental results and suggest a theoretical model that incorporates a coherent radiative term into the typical Hamiltonian of the problem. References [1] D. Gelman and R. Kosloff, Chem. Phys. Lett., 381, 129 (2003). [2] S. Kallush, and S. Fleischer, Phys. Rev. A, 91, 063420 (2015). [3] R. Damari, S. Kallush, and S. Fleischer, Phys. Rev. Lett. 117, 103001 (2016). [4] R. Damari, D. Rosenberg, and S. Fleischer, Phys. Rev. Lett. 119, 033002 (2017).

D-Serine is a physiological co-agonist that activates N-methyl D-aspartate receptors (NMDARs) and is essential for neurotransmission, synaptic plasticity, and behavior. D-Serine may also trigger NMDAR-mediated neurotoxicity, and its dysregulation may play a role in neurodegeneration. D-Serine is synthesized by the enzyme serine racemase (SR), which directly converts L-serine to D-serine. However, many aspects concerning the regulation of D-serine production under physiological and pathological conditions remain to be elucidated. Here, we investigate possible mechanisms regulating the synthesis of D-serine by SR in paradigms relevant to neurotoxicity. We report that SR undergoes nucleocytoplasmic shuttling and that this process is dysregulated by several insults leading to neuronal death, typically by apoptotic stimuli. Cell death induction promotes nuclear accumulation of SR, in parallel with the nuclear translocation of GAPDH and Siah proteins at an early stage of the cell death process. Mutations in putative SR nuclear export signals (NESs) elicit SR nuclear accumulation and its depletion from the cytosol. Following apoptotic insult, SR associates with nuclear GAPDH along with other nuclear components, and this is accompanied by complete inactivation of the enzyme. As a result, extracellular D-serine concentration is reduced, even though extracellular glutamate concentration increases severalfold. Our observations imply that nuclear translocation of SR provides a fail-safe mechanism to prevent or limit secondary NMDAR-mediated toxicity in nearby synapses.

We study and demonstrate the rephasing property of the echo response in a multilevel rotational system of iodomethane via long time-resolved optical birefringence measurements. The strong centrifugal distortion of iodomethane is utilized as a dephasing mechanism imprinted on the echo signal and is shown to rephase throughout its evolution. The dependence of the echo signal amplitude on the driving pulses’ intensities is theoretically and experimentally explored. The analogy to Hahn’s spin echoes is discussed, and a quantum-mechanical version of Hahn’s track runners is provided for the case of multilevel rotational system.

The decay of field-free rotational dynamics is experimentally studied by two complementary methods: laser-induced molecular alignment and terahertz-field-induced molecular orientation. A comparison between the decay rates of different molecular species at various gas pressures reveals that oriented molecular ensembles decay faster than aligned ensembles. The discrepancy in decay rates is attributed to the coherent radiation emitted by the transiently oriented ensembles and is absent from aligned molecules. The experimental results reveal the dramatic contribution of coherent radiative emission to the observed decay of rotational dynamics and underline a general phenomenon expected whenever field-free coherent dipole oscillations are induced.

Introduction: Mutations of the NPM1 gene (NPM1mut) are considered a favorable prognostic marker in acute myeloid leukemia (AML). Data from a prospective randomized trial have shown that in young AML patients with NPM1mut upfront allogeneic stem cell transplantation (allo-SCT) performed in first complete remission (CR1) may lead to a significantly improved overall survival (OS) (Dohner K, Blood 2005). However, due to considerable allo-SCT-associated morbidity and mortality and a relatively favorable outcome of these patients outside the transplant setting, many physicians are reluctant to refer NPM1mut AML patients to allo-SCT in CR1. Recently, quantitative NPM1 testing has been adopted in patient selection for allo-SCT; yet, evidence to support such practice is scant. The current single-center retrospective study compared the outcome of fit NPM1mut AML patients before and after the introduction of quantitative PCR monitoring to the routine practice at the Rambam Leukemia Unit. Methods: This retrospective cohort analysis included NPM1mut AML patients who were considered fit for intensive chemotherapy. FLT3 positivity was not an exclusion criterion. The cohort incorporated patients treated between 2011-2014 whose minimal residual disease (MRD) status was not evaluated (n=31) and patients treated between 2015-2019 who underwent MRD assessment as part of their routine follow-up (n= 38). All patients (n=69) received intensive chemotherapy (the "3+7" regimen). In the former period, our practice was to recommend allo-SCT for any NPM1mut fit patient with an available donor. Starting from 2015, bone marrow samples of all patients have been monitored for MRD both post-induction and after each consolidation cycle, using quantitative PCR. Presently, only patients failing to achieve a 3-log reduction in the NPM1mut relative expression level (NPM1/ABL) after the first consolidation are recommended to proceed to allo-SCT during CR1. In case of molecular relapse identified in former MRDneg patients, the aim is to immediately perform allo-SCT in an attempt to avoid morphological relapse. Patient demographics, comorbidities, cytogentic and molecular risk factors were compared. Survival curves were calculated with and without censoring at time of SCT. Results: Comparison of the pre-MRD monitoring cohort with the MRD-evaluated cohort revealed no difference in age (53.5 years and 56.2 years, respectively), comorbidities (ischemic heart disease, insulin-dependent diabetes mellitus, chronic kidney disease grade >2, chronic obstructive pulmonary disease and cirrhosis), high risk features such as FLT3 positive status, complex karyotype or P53 positive (38.8% and 39.5%, respectively) and extramedullary involvement (3.2% and 15.8%, respectively; P=0.12). More women were treated in the earlier period (64.5% and 39.5%, respectively; P=0.053). The use of intensified induction (daunorubicin 90mg/m2 or re-induction) was significantly more prevalent in the second cohort (50%, n=19) than in the first one (12.9%, n=4). Patients were generally prescribed the daunorubicin dose of ≥60mg/m2 or similar, apart from one patient in each group who received high-dose Ara-C as induction therapy. The use of MRD quantitative monitoring allowed reducing the portion of patients transplanted in CR1 from 61% (n=19/31) to 47.3% (n=18/38). Four patients who had not been transplanted in first molecular remission were successfully transplanted at time of molecular relapse without requiring salvage chemotherapy and prior to morphological relapse. To date, these four patients are alive and in remission at a follow-up of 1,8, 17 and 26 months from relapse. The 1- and 2-year OS was identical in the two cohorts (1 year: 77.3% vs. 86.7%; 2 years: 66.3% vs 74.4%, respectively) (Fig 1a). There was no significant change without censoring at time of SCT (Fig 1b). Conclusions: The present analysis demonstrates that in clinical practice quantitative NPM1 monitoring may be safely used for precise selection of NPM1mut fit AML patients for allo-SCT. This approach may allow avoiding transplantation in patients who may have a prolonged remission outside the transplant setting, while reserving allo-SCT for the time when such patients experience molecular relapse. The use of MRD monitoring as decision making tool in the hematologist armamentarium should be evaluated in lager patient cohorts.

d-Serine is an endogenous ligand for NMDARs generated from l-serine by the enzyme serine racemase (Srr). Both neuronal and glial localizations have been reported for d-serine and Srr. 3-Phosphoglycerate dehydrogenase is an exclusively astrocytic enzyme that catalyzes the first committed step of l-serine biosynthesis. Using transgenic mice expressing enhanced green fluorescent protein under the Srr promoter and mice with targeted deletion of Srr or 3-Phosphoglycerate dehydrogenase, we demonstrate predominantly neuronal sources of d-serine dependent on astrocytic supply of l-serine. These findings clarify the cellular basis for the regulation of NMDAR neurotransmission by d-serine.

d-Serine is a co-agonist of NMDA receptors (NMDARs) whose activity is potentially regulated by Asc-1 (SLC7A10), a transporter that displays high affinity for d-serine and glycine. Asc-1 operates as a facilitative transporter and as an antiporter, though the preferred direction of d-serine transport is uncertain. We developed a selective Asc-1 blocker, Lu AE00527, that blocks d-serine release mediated by all the transport modes of Asc-1 in primary cultures and neocortical slices. Furthermore, d-serine release is reduced in slices from Asc-1 knockout (KO) mice, indicating that d-serine efflux is the preferred direction of Asc-1. The selectivity of Lu AE00527 is assured by the lack of effect on slices from Asc-1-KO mice, and the lack of interaction with the co-agonist site of NMDARs. Moreover, in vivo injection of Lu AE00527 in P-glycoprotein-deficient mice recapitulates a hyperekplexia-like phenotype similar to that in Asc-1-KO mice. In slices, Lu AE00527 decreases the long-term potentiation at the Schaffer collateral-CA1 synapses, but does not affect the long-term depression. Lu AE00527 blocks NMDAR synaptic potentials when typical Asc-1 extracellular substrates are present, but it does not affect AMPAR transmission. Our data demonstrate that Asc-1 mediates tonic co-agonist release, which is required for optimal NMDAR activation and synaptic plasticity.

Food enrichment with nutraceuticals is an important goal, but its effectiveness in preventing diseases depends on preserving the functionality and bioavailability of the bioactive nutraceuticals. Omega-3 polyunsaturated fatty acids, such as docosahexaenoic acid (DHA), are important nutraceutical lipids, providing protection against cardiovascular and other diseases. Caseins are the major milk proteins whose biological function is to transport calcium, protein and phosphate from mother to the neonate. Our goal was to harness the natural self-assembly properties of caseins for protecting and delivering this important, but sensitive nutraceutical, DHA. Using spectrofluorescence we have shown, apparently for the first time, that casein can bind DHA with a relatively high affinity ( K b = (8.38 ± 3.12) × 10 6 M −1 ), and the binding ratio was 3–4 DHA molecules per protein molecule on average. Moreover, DLS particle characterization experiments have shown the formation of nanoparticles upon addition of DHA (predissolved in ethanol) to a casein solution. When calcium and phosphate were added (at 4 °C), DHA-loaded re-formed casein micelles (r-CM) with a size of 50–60 nm were obtained and there was no significant effect of the thermal treatment (74 °C, 20 s) on particle size. When casein nanoparticles (CNP) were prepared (at room temperature and without adding calcium and phosphate), DHA-loaded CNP with a diameter of 288.9 ± 9.6 nm were formed. Both the DHA-loaded r-CM and the DHA-loaded CNP systems showed a remarkable protective effect against DHA oxidation, demonstrating good colloidal stability and bioactive conservation throughout shelf life at 4 °C. These nanotechnologies may enable the enrichment of foods and beverages for promoting health of wide populations.

In this paper we argue that autocracies’ healthcare policy is a part of their economic policy and targets developing the labor force as a production factor. With the disaggregated data on mortality from specific diseases, we show that, other things equal, autocracies manage to deal relatively well with the diseases that “damage” the workforce, at the expense of other areas of health improvement. Democracies, in contrast, do not have such bias, and their policy priorities are less clear and depend on the preferences of their winning coalitions on the dimension of health.

d-Serine is a physiological co-agonist that activates N-methyl d-aspartate receptors (NMDARs) and is essential for neurotransmission, synaptic plasticity, and behavior. d-Serine may also trigger NMDAR-mediated neurotoxicity, and its dysregulation may play a role in neurodegeneration. d-Serine is synthesized by the enzyme serine racemase (SR), which directly converts l-serine to d-serine. However, many aspects concerning the regulation of d-serine production under physiological and pathological conditions remain to be elucidated. Here, we investigate possible mechanisms regulating the synthesis of d-serine by SR in paradigms relevant to neurotoxicity. We report that SR undergoes nucleocytoplasmic shuttling and that this process is dysregulated by several insults leading to neuronal death, typically by apoptotic stimuli. Cell death induction promotes nuclear accumulation of SR, in parallel with the nuclear translocation of GAPDH and Siah proteins at an early stage of the cell death process. Mutations in putative SR nuclear export signals (NESs) elicit SR nuclear accumulation and its depletion from the cytosol. Following apoptotic insult, SR associates with nuclear GAPDH along with other nuclear components, and this is accompanied by complete inactivation of the enzyme. As a result, extracellular d-serine concentration is reduced, even though extracellular glutamate concentration increases severalfold. Our observations imply that nuclear translocation of SR provides a fail-safe mechanism to prevent or limit secondary NMDAR-mediated toxicity in nearby synapses.

Asc-1 (SLC7A10) is an amino acid transporter whose deletion causes neurological abnormalities and early postnatal death in mice. Using metabolomics and behavioral and electrophysiological methods, we demonstrate that Asc-1 knockout mice display a marked decrease in glycine levels in the brain and spinal cord along with impairment of glycinergic inhibitory transmission, and a hyperekplexia-like phenotype that is rescued by replenishing brain glycine. Asc-1 works as a glycine and L-serine transporter, and its transport activity is required for the subsequent conversion of L-serine into glycine in vivo. Asc-1 is a novel regulator of glycine metabolism and a candidate for hyperekplexia disorders.

In this paper we draw upon the unique natural experiment of post-communist transitions to show how the interaction between democratization and economic liberalization impacts health. We argue that, if occurring simultaneously, these transformations reduce overall uncertainty and thus improve health. Two concrete mechanisms are at work: first, people suffer less from stress-related diseases, and second, they start investing more in their own health. To capture the proposed theoretical mechanisms, we use stress-caused mortality and private expenditures on health as our dependent variables. Empirically, we employ mediation analysis with country and time fixed effects. We find that, ceteris paribus, democratization and economic liberalization exert a cumulatively positive impact upon health. Our findings should be relevant to other countries that undergo politico-economic transitions.

d-Serine and glycine are coagonists of NMDA receptors (NMDARs), but their relative contributions for several NMDAR-dependent processes are unclear. We now report that the alanine–serine–cysteine transporter-1 (Asc-1) mediates release of bothd-serine and glycine from neurons, and, in turn, this modulates NMDAR synaptic activity. Asc-1 antiporter activity is enhanced byd-isoleucine (d-Ile), which releasesd-serine and glycine from Asc-1-transfected cells, primary neuronal cultures, and hippocampal slices.d-Ile has no effect on astrocytes, which do not express Asc-1. We show thatd-Ile enhances the long-term potentiation (LTP) in rat and mouse hippocampal CA1 by stimulating Asc-1-mediated endogenousd-serine release.d-Ile effects on synaptic plasticity are abolished by enzymatically depletingd-serine or by using serine racemase knock-out (SR-KO) mice, confirming its specificity and supporting the notion that LTP depends mostly ond-serine release. Conversely, our data also disclose a role of glycine in activating synaptic NMDARs. Although acute enzymatic depletion ofd-serine also drastically decreases the isolated NMDAR synaptic potentials, these responses are still enhanced byd-Ile. Furthermore, NMDAR synaptic potentials are preserved in SR-KO mice and are also enhanced byd-Ile, indicating that glycine overlaps withd-serine binding at synaptic NMDARs. Altogether, our results disclose a novel role of Asc-1 in regulating NMDAR-dependent synaptic activity by mediating concurrent non-vesicular release ofd-serine and glycine. Our data also highlight an important role of neuron-derivedd-serine and glycine, indicating that astrocyticd-serine is not solely responsible for activating synaptic NMDARs.

Introduction: Leukemic sub-clones which survive chemotherapy during induction period may remain dormant and subsequently lead to relapse in patients with acute myeloid leukemia (AML). No mechanism linking clonal selection to a specific leukemia-associated genetic aberration is known. Clonal selection is a common phenomenon; therefore, any suggested mechanism should be applicable to all kinds of leukemia-specific genetic aberrations. We hypothesized that clonal selection might result from differences in differentiation capacity among sub-clones and that chemo-resistance is not necessarily directly affected by specific mutations. Patients and Methods: We tested this hypothesis in vitro using the kasumi-1 leukemia cell line, which undergoes limited differentiation while growing and is composed of both CD34+ and CD34- sub-populations. Kasumi-1 cells were sorted by fluorescence-activated cell sorting (FACS-Aria IIIu, BD Biosciences) to CD34+CD117+ and CD34-CD117+ sub-populations. Each sub-population was separately exposed to escalating doses of daunorubicin (DNR) and cytarabine (ARA-C) for 66 hours. Cell viability was determined by alamarBlue assay (Bio-Rad, USA); apoptosis was assessed by Annexin-V and propidium iodide (PI) staining. In vivo experiments included BM samples derived from three AML patients, with both NPM1 and FLT3 gene mutations, who received intensive induction and subsequently relapsed. Blast cells were sorted to CD34+CD117+ and CD34-CD117+ sub-populations. Targeted gene sequencing was conducted using Ion Torrent™ Personal Genome Machine® (PGM) System (Life Technologies, USA). Allelic frequency of NPM1 and DNMT3A mutations in CD34+ and CD34-sub-populations was measured. FLT3-ITD was sequenced using theGeneScan method and theallelic ratio (AR) was calculated. Results: Following sorting,cultured kasumi-1 CD34+ cells partly differentiated into CD34- cells and several weeks later, the phenotype became similar to the original kasumi-1 phenotype (a mixture of 34+/- cells). In contrast, the CD34- sub-population maintained its phenotype. Immediately after sorting by CD34 expression, both sub-populations were exposed to increasing doses of DNR or ARA-C. Only the CD34+ sub-population was found to be resistant to ARA-C (at all tested concentrations), as determined by the cell viability assay (fig 1a). The CD34- sub-population exhibited a 4-fold higher apoptosis rate than CD34+ cells after exposure to 0.16 µM ARA-C. DNR (0.01 µM) resulted in 2.5-fold higher apoptosis in the CD34- compared to CD34+ sub-population (fig 1b). The sub-clonal composition of BM blasts obtained from three AML patients at diagnosis and relapse was compared. NPM1 mutation was identified in all patients at diagnosis. FLT3-ITD mutation was identified in one patient at diagnosis and in the other two at relapse. To explore the differentiation capacity of each sub-clone, blasts were sorted to well-defined CD34+ and CD34- subgroups. At diagnosis, most of the leukemic blasts presented with the CD34- phenotype, while at relapse, the CD34+ population grew in all patients. The FLT3-ITD allelic ratio was higher in CD34+ cells. In the first patient, FLT3-ITD was not detected at diagnosis, while at relapse, the wild-type allele of FLT3 was lost and FLT3-ITD was solely present in the CD34+ sub-population. In CD34- cells, the AR was low (0.55) at relapse. In the second patient, the dominant clone at diagnosis was NPM1mutFLT3wtDNMT3Awt and >95% cells were CD34-. At relapse, the FLT3-ITD DNMT3Awt clone became dominant and was mostly located within the rising CD34+ population. Another sub-clone, exhibiting both FLT3-ITD and DNMT3A R882C mutation, was identified and was found to reside only within the CD34+ population. Similar findings were also observed in the third patient. We screened additional eight patients presenting with FLT3-ITD and in 4 of them, while both CD34+/- blasts were observed, the FLT3-ITD carrying clones resided only in one sub-population. Conclusions: Chemo-resistance and survival of a specific AML sub-clone correlate with its phenotype and differentiation level. Even genetic aberrations which have no direct interaction with chemotherapy biological effect, may give rise to clonal selection. Sub-clonal differentiation capacity may affect its sensitivity to chemotherapy. Disclosures No relevant conflicts of interest to declare.

d-Serine is thought to be a glia-derived transmitter that activates N-methyl d-aspartate receptors (NMDARs) in the brain. Here, we investigate the pathways for d-serine release using primary cultures, brain slices, and in vivo microdialysis. In contrast with the notion that d-serine is exclusively released from astrocytes, we found that d-serine is released by neuronal depolarization both in vitro and in vivo. Veratridine (50 μM) or depolarization by 40 mM KCl elicits a significant release of endogenous d-serine from primary neuronal cultures. Controls with astrocyte cultures indicate that glial cells are insensitive to veratridine, but release d-serine mainly by the opening of volume-regulated anion channels. In cortical slices perfused with veratridine, endogenous d-serine release is 10-fold higher than glutamate receptor-evoked release. Release of d-serine from slices does not require internal or external Ca2+, suggesting a nonvesicular release mechanism. To confirm the neuronal origin of d-serine, we selectively loaded neurons in cortical slices with d-[3H]serine or applied d-alanine, which specifically releases d-serine from neurons. Depolarization with veratridine promotes d-serine release in vivo monitored by high temporal resolution microdialysis of the striatum. Our data indicate that the neuronal pool of d-serine plays a major role in d-serine dynamics, with implications for the regulation of NMDAR transmission. Rosenberg, D., Kartvelishvily, E., Shleper, M., Klinker, C. M. C., Bowser, M. T., Wolosker, H. Neuronal release of d-serine: a physiological pathway controlling extracellular d-serine concentration.