Anesthesia and cognitive performance in children: No evidence for a causal relationship

* Both authors contributed evenly to the manuscript Recent findings of an association between anesthesia administration in the first three years of life and later learning disabilities have created concerns that anesthesia has neurotoxic effects on synaptogenesis, causing later learning problems. An alternative hypothesis is that those children who are likely to undergo surgery early in life have significant medical problems that are associated with a vulnerability to learning disabilities. These two hypotheses were evaluated in a monozygotic concordant–discordant twin design. Data on anesthesia administration and learning abilities and disabilities were available for 1,143 monozygotic twin pairs (56 % female) from the Netherlands Twin Registry. Parents of the twins reported on anesthesia use before age 3 and again between ages 3 and 12 years. Near age 12, educational achievement and cognitive problems were assessed with standardized tests and teacher ratings. Results showed that twins who were exposed to anesthesia before age 3 had significantly lower educational achievement scores and significantly more cognitive problems than twins not exposed to anesthesia. However, there was one important exception: the unexposed co-twin from discordant pairs did not differ from their exposed cotwin. Thus, there is no evidence for a causal relationship between anesthesia administration and later learning-related outcomes in this sample. Rather, there is evidence for early anesthesia being a marker of an individual’s vulnerability for later learning problems, regardless of their exposure to anesthesia

Prenatal Organochlorine and Methylmercury Exposure and Memory and Learning in School-Age Children in Communities Near the New Bedford Harbor Superfund Site, Massachusetts

Background: Polychlorinated biphenyls (PCBs), organochlorine pesticides, and methylmercury (MeHg) are environmentally persistent with adverse effects on neurodevelopment. However, especially among populations with commonly experienced low levels of exposure, research on neurodevelopmental effects of these toxicants has produced conflicting results. Objectives: We assessed the association of low-level prenatal exposure to these contaminants with memory and learning. Methods: We studied 393 children, born between 1993 and 1998 to mothers residing near a PCB-contaminated harbor in New Bedford, Massachusetts. Cord serum PCB, DDE (dichlorodiphenyldichloroethylene), and maternal peripartum hair mercury (Hg) levels were measured to estimate prenatal exposure. Memory and learning were assessed at 8 years of age (range, 7–11 years) using the Wide Range Assessment of Memory and Learning (WRAML), age-standardized to a mean ± SD of 100 ± 15. Associations with each WRAML index—Visual Memory, Verbal Memory, and Learning—were examined with multivariable linear regression, controlling for potential confounders. Results: Although cord serum PCB levels were low (sum of four PCBs: mean, 0.3 ng/g serum; range, 0.01–4.4), hair Hg levels were typical of the U.S. fish-eating population (mean, 0.6 μg/g; range, 0.3–5.1). In multivariable models, each microgram per gram increase in hair Hg was associated with, on average, decrements of –2.8 on Visual Memory (95% CI: –5.0, –0.6, p = 0.01), –2.2 on Learning (95% CI: –4.6, 0.2, p = 0.08), and –1.7 on Verbal Memory (95% CI: –3.9, 0.6, p = 0.14). There were no significant adverse associations of PCBs or DDE with WRAML indices. Conclusions: These results support an adverse relationship between low-level prenatal MeHg exposure and childhood memory and learning, particularly visual memory. Citation: Orenstein ST, Thurston SW, Bellinger DC, Schwartz JD, Amarasiriwardena CJ, Altshul LM, Korrick SA. 2014. Prenatal organochlorine and methylmercury exposure and memory and learning in school-age children in communities near the New Bedford Harbor Superfund Site, Massachusetts. Environ Health Perspect 122:1253–1259; http://dx.doi.org/10.1289/ehp.130780

Spatial and temporal variability of biogenic isoprene emissions from a temperate estuary

[1] Isoprene is important for its atmospheric impacts and the ecophysiological benefits it affords to emitting organisms; however, isoprene emissions from marine systems remain vastly understudied compared to terrestrial systems. This study investigates for the first time drivers of isoprene production in a temperate estuary, and the role this production may play in enabling organisms to tolerate the inherently wide range of environmental conditions. Intertidal sediment cores as well as high and low tide water samples were collected from four sites along the Colne Estuary, UK, every six weeks over a year. Isoprene concentrations in the water were significantly higher at low than high tide, and decreased toward the mouth of the estuary; sediment production showed no spatial variability. Diel isoprene concentration increased with light availability and decreased with tidal height; nighttime production was 79% lower than daytime production. Seasonal isoprene production and water concentrations were highest for the warmest months, with production strongly correlated with light (r2 = 0.800) and temperature (r2 = 0.752). Intertidal microphytobenthic communities were found to be the primary source of isoprene, with tidal action acting as a concentrating factor for isoprene entering the water column. Using these data we estimated an annual production rate for this estuary of 681 μmol m−2 y−1. This value falls at the upper end of other marine estimates and highlights the potentially significant role of estuaries as isoprene sources. The control of estuarine isoprene production by environmental processes identified here further suggests that such emissions may be altered by future environmental change

Analytical investigation of the effects of blade flexibility, unsteady aerodynamics, and variable inflow on helicopter rotor stall characteristics

Analytical investigation of effects of blade flexibility, unsteady aerodynamics, and variable inflow on helicopter rotor stall characteristic

Asteroseismology of red giants & galactic archaeology

Red-giant stars are low- to intermediate-mass ($M \lesssim 10$~M$_{\odot}$) stars that have exhausted hydrogen in the core. These extended, cool and hence red stars are key targets for stellar evolution studies as well as galactic studies for several reasons: a) many stars go through a red-giant phase; b) red giants are intrinsically bright; c) large stellar internal structure changes as well as changes in surface chemical abundances take place over relatively short time; d) red-giant stars exhibit global intrinsic oscillations. Due to their large number and intrinsic brightness it is possible to observe many of these stars up to large distances. Furthermore, the global intrinsic oscillations provide a means to discern red-giant stars in the pre-helium core burning from the ones in the helium core burning phase and provide an estimate of stellar ages, a key ingredient for galactic studies. In this lecture I will first discuss some physical phenomena that play a role in red-giant stars and several phases of red-giant evolution. Then, I will provide some details about asteroseismology -- the study of the internal structure of stars through their intrinsic oscillations -- of red-giant stars. I will conclude by discussing galactic archaeology -- the study of the formation and evolution of the Milky Way by reconstructing its past from its current constituents -- and the role red-giant stars can play in that.Comment: Lecture presented at the IVth Azores International Advanced School in Space Sciences on "Asteroseismology and Exoplanets: Listening to the Stars and Searching for New Worlds" (arXiv:1709.00645), which took place in Horta, Azores Islands, Portugal in July 201

Residual cognitive deficits 50 years after lead poisoning during childhood

The long term neurobehavioural consequences of childhood lead poisoning are not known. In this study adult subjects with a documented history of lead poisoning before age 4 and matched controls were examined with an abbreviated battery of neuropsychological tests including measures of attention, reasoning, memory, motor speed, and current mood. The subjects exposed to lead were inferior to controls on almost all of the cognitive tasks. This pattern of widespread deficits resembles that found in children evaluated at the time of acute exposure to lead rather than the more circumscribed pattern typically seen in adults exposed to lead. Despite having completed as many years of schooling as controls, the subjects exposed to lead were lower in lifetime occupational status. Within the exposed group, performance on the neuropsychological battery and occupational status were related, consistent with the presumed impact of limitations in neuropsychological functioning on everyday life. The results suggest that many subjects exposed to lead suffered acute encephalopathy in childhood which resolved into a chronic subclinical encephalopathy with associated cognitive dysfunction still evident in adulthood. These findings lend support to efforts to limit exposure to lead in childhood

The practices of apartheid as a war crime: a critical analysis

The human suffering caused by the political ideology of apartheid in South Africa during the Apartheid era (1948-1994) prompted worldwide condemnation and a variety of diplomatic and legal responses. Amongst these responses was the attempt to have apartheid recognised both as a crime against humanity in the 1973 Apartheid Convention as well as a war crime in Article 85(4)(c) of Additional Protocol I. This article examines the origins, nature and current status of the practices of apartheid as a war crime and its possible application to the Israeli-Palestinian conflict

Measurement of the Associated γ+μ±\gamma + \mu^\pm Production Cross Section in ppˉp \bar p Collisions at s=1.8\sqrt{s} = 1.8 TeV

We present the first measurement of associated direct photon + muon production in hadronic collisions, from a sample of 1.8 TeV $p \bar p$ collisions recorded with the Collider Detector at Fermilab. Quantum chromodynamics (QCD) predicts that these events are primarily from the Compton scattering process $cg \to c\gamma$, with the final state charm quark producing a muon. Hence this measurement is sensitive to the charm quark content of the proton. The measured cross section of $29\pm 9 pb^{-1}$ is compared to a leading-order QCD parton shower model as well as a next-to-leading-order QCD calculation.Comment: 12 pages, 4 figures Added more detailed description of muon background estimat

Search for the Supersymmetric Partner of the Top-Quark in ppˉp \bar{p} Collisions at s=1.8TeV\sqrt{s} = 1.8 {\rm TeV}

We report on a search for the supersymmetric partner of the top quark (stop) produced in $t \bar{t}$ events using $110 {\rm pb}^{-1}$ of $p \bar{p}$ collisions at $\sqrt{s} = 1.8 {\rm TeV}$ recorded with the Collider Detector at Fermilab. In the case of a light stop squark, the decay of the top quark into stop plus the lightest supersymmetric particle (LSP) could have a significant branching ratio. The observed events are consistent with Standard Model $t \bar{t}$ production and decay. Hence, we set limits on the branching ratio of the top quark decaying into stop plus LSP, excluding branching ratios above 45% for a LSP mass up to 40 {\rm GeV/c}$^{2}$.Comment: 11 pages, 4 figure