Measurements Of Excited-state Population Ratios Of Atomic Hydrogen Produced By Charge-exchange Neutralization Of Energetic Proton Beams

Excited-state population ratios for atomic hydrogen have been measured for energetic hydrogen ions neutralized by charge exchange with a number of different metallic vapors and permanent gases. Electric field ionization techniques were used to determine excitation ratios. Detection of the energetic ions and neutrals was accomplished using partially depleted surface-barrier detectors. Counting, using phase-detection techniques in which an add-subtract scaler was phased to the signal, provided an improved signal-to-noise ratio. Two methods were used to provide desired targets. Metallic vapor and permanent-gas thin targets of the order of 10-5 mTorr cm were produced as chopped neutral beams, using conventional crossed-beam techniques. Gas cells were used to extend these measurements with permanent gases to targets up to seven orders of magnitude thicker. In the latter case, the ion beam was interrupted electrically. Targets investigated were magnesium, potassium, barium, hydrogen, nitrogen, thallium, Freon, water vapor, ammonia, and perfluorodimethylcyclohexane (C8F16). © 1970 The American Physical Society

D- Production By Charge Transfer Of (0.3 - 3)-keV D+ In Thick Alkaline-earth Vapor Targets: Interaction Energies For CaH+, CaH, And CaH-

Equilibrium charge-state fractions of energetic deuterium ions and atoms emerging from alkaline-earth (magnesium, calcium, strontium, and barium) vapor targets are reported in the range of 0.3- to 3-keV incident D+ energy. Deuterium negative-ion production in thick barium and calcium vapor targets equals similar production in cesium vapor (34%). Moreover, the maximum D- production in strontium vapor exceeds that for all other known gas or vapor targets and reaches 50% at 500 eV. Theory does not quantitatively describe these results, although ab initio molecular-interaction-energy calculations on the neutral and negative-ion CaH systems lead to the prediction of large D- yields at low energies. The theoretical prediction is based on the lack of a strong coupling between the negative ion and neutral molecular states. This implies that there are small D- electron-detachment cross sections at energies less than 1 keV. The present measurements agree with previous measurements done at higher energies. © 1982 The American Physical Society

COVID-19-Related Outcomes in Primary Mitochondrial Diseases: An International Study

OBJECTIVES: To identify factors associated with severe COVID-19, defined by hospitalization status, in patients with primary mitochondrial diseases (PMDs), thereby enabling future risk stratification and informed management decisions. METHODS: We undertook a cross-sectional, international, registry-based study. Data was extracted from the "International Neuromuscular COVID-19 Database" and collected between 1st May 2020 and 31st May 2021. The database included subjects with: 1) PMD diagnosis (any age), clinically/histopathologically suspected and/or genetically confirmed; and (2) COVID-19 diagnosis classified as "confirmed", "probable", or "suspected" based on World Health Organization definitions. The primary outcome was hospitalization due to COVID-19. We collected demographic information, smoking status, coexisting comorbidities, outcome following COVID-19 infection, and PMD genotype-phenotype. Baseline status was assessed using the modified Rankin scale (mRS) and the Newcastle Mitochondrial Disease Adult Scale (NMDAS). RESULTS: Seventy-nine subjects with PMDs from 10 countries were included (mean age 41.5±18 years): 25 (32%) were hospitalized; 48 (61%) recovered fully; 28 (35%) improved with sequelae; and three (4%) died. Statistically significant differences in hospitalization status were observed in: baseline status, including NMDAS score (p=0.003) and mRS (p=0.001); presence of respiratory dysfunction (p<0.001), neurologic involvement (p=0.003); and more than four comorbidities (p=0.002). In multivariable analysis, respiratory dysfunction was independently associated with COVID-19 hospitalization (OR, 7.66; 95%CI, 2 to 28; p=0.002). DISCUSSION: Respiratory dysfunction is an independent risk factor for severe COVID-19 in PMDs, while high disease burden and coexisting comorbidities contribute towards COVID-19 related hospitalization. These findings will enable risk stratification and informed management decisions for this vulnerable population

The GABA Transaminase, ABAT, Is Essential for Mitochondrial Nucleoside Metabolism

SummaryABAT is a key enzyme responsible for catabolism of principal inhibitory neurotransmitter γ-aminobutyric acid (GABA). We report an essential role for ABAT in a seemingly unrelated pathway, mitochondrial nucleoside salvage, and demonstrate that mutations in this enzyme cause an autosomal recessive neurometabolic disorder and mtDNA depletion syndrome (MDS). We describe a family with encephalomyopathic MDS caused by a homozygous missense mutation in ABAT that results in elevated GABA in subjects’ brains as well as decreased mtDNA levels in subjects’ fibroblasts. Nucleoside rescue and co-IP experiments pinpoint that ABAT functions in the mitochondrial nucleoside salvage pathway to facilitate conversion of dNDPs to dNTPs. Pharmacological inhibition of ABAT through the irreversible inhibitor Vigabatrin caused depletion of mtDNA in photoreceptor cells that was prevented through addition of dNTPs in cell culture media. This work reveals ABAT as a connection between GABA metabolism and nucleoside metabolism and defines a neurometabolic disorder that includes MDS

Resonant Electron Transfer And Excitation In Two-, Three-, And Four- Electron Caq +20 And Vq +23 Ions Colliding With Helium

Significant new evidence is reported for resonant transfer and excitation in ion-atom collisions. This process, which is analogous to dielectronic recombination, occurs when a target electron is captured simultaneously with the excitation of the projectile followed by photon emission. Strong resonant behavior with structure, in agreement with theoretical calculations, is observed in the cross section for projectile K x rays coincident with single electron capture for 100-360-MeV Ca16+,17+,18+20 and 180-460-MeV V19+,20+,21+23 ions colliding with helium. © 1984 The American Physical Society

Electron Capture And Loss For 2.5-200-MeV 16S13++He Collisions

Electron capture and loss cross sections have been measured for highly charged (q=13+) sulfur ions with energies 2.5-200 MeV colliding with helium. Electron capture varies by nearly six orders of magnitude over the energy range investigated, while electron loss varies by only about a factor of 2. The capture cross sections are in reasonable agreement with classical and empirical scaling rules, while the loss cross sections agree well with the plane-wave Born approximation. © 1986 The American Physical Society

Enhanced Radiative Auger Emission From Lithiumlike S13+16

The radiative Auger emission (RAE) from 0.946.25-MeV/u 16S13+ (lithiumlike) projectiles excited in collisions with He target atoms has been measured. For these highly stripped ions the intensity of RAE photons relative to K x-ray emission is enhanced by about a factor of five compared with theoretical calculations and an earlier experimental measurement for S ions with few electron vacancies. The enhancement of RAE for S13+ is qualitatively similar to results reported previously for lithiumlike 23V20+; however, some differences between S and V are evident. © 1990 The American Physical Society

Climate change impacts on US agriculture and forestry: benefits of global climate stabilization

Increasing atmospheric carbon dioxide levels, higher temperatures, altered precipitation patterns, and other climate change impacts have already begun to affect US agriculture and forestry, with impacts expected to become more substantial in the future. There have been numerous studies of climate change impacts on agriculture or forestry, but relatively little research examining the long-term net impacts of a stabilization scenario relative to a case with unabated climate change. We provide an analysis of the potential benefits of global climate change mitigation for US agriculture and forestry through 2100, accounting for landowner decisions regarding land use, crop mix, and management practices. The analytic approach involves a combination of climate models, a crop process model (EPIC), a dynamic vegetation model used for forests (MC1), and an economic model of the US forestry and agricultural sector (FASOM-GHG). We find substantial impacts on productivity, commodity markets, and consumer and producer welfare for the stabilization scenario relative to unabated climate change, though the magnitude and direction of impacts vary across regions and commodities. Although there is variability in welfare impacts across climate simulations, we find positive net benefits from stabilization in all cases, with cumulative impacts ranging from $32.7 billion to$54.5 billion over the period 2015–2100. Our estimates contribute to the literature on potential benefits of GHG mitigation and can help inform policy decisions weighing alternative mitigation and adaptation actions.United States. Environmental Protection Agency. Climate Change Division (Contract EP-BPA-12-H-0023, Call Order EP-B13H-00143

Editorial: Translational insights into mechanisms and therapy of organ dysfunction in sepsis and trauma

Multiple organ dysfunction or even failure after sepsis or trauma is due to a dysregulated host response. Currently, besides (surgical) source control (e.g., control of bleeding or drainage of abscesses) and administration of antimicrobial drugs, therapeutic approaches are limited to supportive care. Advances in our understanding of the key pathophysiological pathways involved in the excessive inflammation triggered by trauma, sepsis and/or ischemia-reperfusion have had limited impact. The 28 article in this Research Topic focus on the molecular mechanisms behind (hyper) inflammation after sepsis or trauma, with special emphasis on preclinical and translational studies that target potential organ-protective and/or -resuscitative therapeutic strategies. Most studies report rodent models of trauma and elective surgery (three articles), non-microbial hyper-inflammation induced with endotoxin exposure (LPS; seven articles) and chemical pancreatitis (one article), and cecal ligation and puncture-induced sepsis (six articles). Additional papers summarize investigations of human material (six articles) or fully-resuscitated large animal models (two articles). These article are complimented by four reviews and a commentary

Neuropathologic Characterization of Pontocerebellar Hypoplasia Type 6 Associated With Cardiomyopathy and Hydrops Fetalis and Severe Multisystem Respiratory Chain Deficiency due to Novel RARS2 Mutations

Autosomal recessive mutations in the RARS2 gene encoding the mitochondrial arginyl-transfer RNA synthetase cause infantile-onset myoencephalopathy pontocerebellar hypoplasia type 6 (PCH6). We describe 2 sisters with novel compound heterozygous RARS2 mutations who presented perinatally with neurologic features typical of PCH6 but with additional features including cardiomyopathy, hydrops, and pulmonary hypoplasia and who died at 1 day and 14 days of age. Magnetic resonance imaging findings included marked cerebellar hypoplasia, gyral immaturity, punctate lesions in cerebral white matter, and unfused deep cerebral grey matter. Enzyme histochemistry of postmortem tissues revealed a near-global cytochrome c oxidase-deficiency; assessment of respiratory chain enzyme activities confirmed severe deficiencies involving complexes I, III, and IV. Molecular genetic studies revealed 2 RARS2 gene mutations: a c.1A>G, p.? variant predicted to abolish the initiator methionine, and a deep intronic c.613-3927C>T variant causing skipping of exons 6–8 in the mature RARS2 transcript. Neuropathologic investigation included low brain weights, small brainstem and cerebellum, deep cerebral white matter pathology, pontine nucleus neuron loss (in 1 sibling), and peripheral nerve pathology. Mitochondrial respiratory chain immunohistochemistry in brain tissues confirmed an absence of complexes I and IV immunoreactivity with sparing of mitochondrial numbers. These cases expand the clinical spectrum of RARS2 mutations, including antenatal features and widespread mitochondrial respiratory chain deficiencies in postmortem brain tissues