Metabolic balance of coastal Antarctic waters revealed by autonomous pCO2 and ΔO2/Ar measurements

Author Posting. © American Geophysical Union, 2014. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geophysical Research Letters 41 (2014): 6803–6810, doi:10.1002/2014GL061266.We use autonomous gas measurements to examine the metabolic balance (photosynthesis minus respiration) of coastal Antarctic waters during the spring/summer growth season. Our observations capture the development of a massive phytoplankton bloom and reveal striking variability in pCO2 and biological oxygen saturation (ΔO2/Ar) resulting from large shifts in community metabolism on time scales ranging from hours to weeks. Diel oscillations in surface gases are used to derive a high-resolution time series of net community production (NCP) that is consistent with 14C-based primary productivity estimates and with the observed seasonal evolution of phytoplankton biomass. A combination of physical mixing, grazing, and light availability appears to drive variability in coastal Antarctic NCP, leading to strong shifts between net autotrophy and heterotrophy on various time scales. Our approach provides insight into the metabolic responses of polar ocean ecosystems to environmental forcing and could be employed to autonomously detect climate-dependent changes in marine primary productivity.This study was supported by funds from the U.S. National Science Foundation (OPP awards ANT-0823101, ANT-1043559, ANT-1043593, and ANT-1043532) as well as support for PDT and ECA from the National Science and Engineering Research Council of Canada.2015-04-0

Surgery for pituitary tumor apoplexy is associated with rapid headache and cranial nerve improvement

Pituitary tumor apoplexy (PTA) classically comprises sudden-onset headache, loss of vision, ophthalmoparesis, and decreased consciousness. It typically results from hemorrhage and/or infarction within a pituitary adenoma. Presentation is heterologous, and optimal management is debated. The time course of recovery of cranial nerve deficits (CNDs) and headaches is not well established. In this study, a retrospective series of consecutive patients with PTA managed at a single academic institution over a 22-year period is presented. Headaches at the time of surgery were more severe in the early and subacute surgical cohort and improved significantly within 72 h postoperatively

Genetically-Directed, Cell Type-Specific Sparse Labeling for the Analysis of Neuronal Morphology

Background: In mammals, genetically-directed cell labeling technologies have not yet been applied to the morphologic analysis of neurons with very large and complex arbors, an application that requires extremely sparse labeling and that is only rendered practical by limiting the labeled population to one or a few predetermined neuronal subtypes. Methods and Findings: In the present study we have addressed this application by using CreER technology to noninvasively label very small numbers of neurons so that their morphologies can be fully visualized. Four lines of IRES-CreER knock-in mice were constructed to permit labeling selectively in cholinergic or catecholaminergic neurons [choline acetyltransferase (ChAT)-IRES-CreER or tyrosine hydroxylase (TH)-IRES-CreER], predominantly in projection neurons [neurofilament light chain (NFL)-IRES-CreER], or broadly in neurons and some glia [vesicle-associated membrane protein2 (VAMP2)-IRES-CreER]. When crossed to the Z/AP reporter and exposed to 4-hydroxytamoxifen in the early postnatal period, the number of neurons expressing the human placental alkaline phosphatase reporter can be reproducibly lowered to fewer than 50 per brain. Sparse Cre-mediated recombination in ChAT-IRES-CreER;Z/AP mice shows the full axonal and dendritic arbors of individual forebrain cholinergic neurons, the first time that the complete morphologies of these very large neurons have been revealed in any species. Conclusions: Sparse genetically-directed, cell type-specific neuronal labeling with IRES-creER lines should prove useful fo

New Mouse Lines for the Analysis of Neuronal Morphology Using CreER(T)/loxP-Directed Sparse Labeling

BACKGROUND: Pharmacologic control of Cre-mediated recombination using tamoxifen-dependent activation of a Cre-estrogen receptor ligand binding domain fusion protein [CreER(T)] is widely used to modify and/or visualize cells in the mouse. METHODS AND FINDINGS: We describe here two new mouse lines, constructed by gene targeting to the Rosa26 locus to facilitate Cre-mediated cell modification. These lines should prove particularly useful in the context of sparse labeling experiments. The R26rtTACreER line provides ubiquitous expression of CreER under transcriptional control by the tetracycline reverse transactivator (rtTA); dual control by doxycycline and tamoxifen provides an extended dynamic range of Cre-mediated recombination activity. The R26IAP line provides high efficiency Cre-mediated activation of human placental alkaline phosphatase (hPLAP), complementing the widely used, but low efficiency, Z/AP line. By crossing with mouse lines that direct cell-type specific CreER expression, the R26IAP line has been used to produce atlases of labeled cholinergic and catecholaminergic neurons in the mouse brain. The R26IAP line has also been used to visualize the full morphologies of retinal dopaminergic amacrine cells, among the largest neurons in the mammalian retina. CONCLUSIONS: The two new mouse lines described here expand the repertoire of genetically engineered mice available for controlled in vivo recombination and cell labeling using the Cre-lox system

Metabolic balance of coastal Antarctic waters revealed by autonomous pCO₂ and ΔO₂/Ar measurements

We use autonomous gas measurements to examine the metabolic balance (photosynthesis minus respiration) of coastal Antarctic waters during the spring/summer growth season. Our observations capture the development of a massive phytoplankton bloom and reveal striking variability in pCO₂ and biological oxygen saturation (ΔO₂/Ar) resulting from large shifts in community metabolism on time scales ranging from hours to weeks. Diel oscillations in surface gases are used to derive a high-resolution time series of net community production (NCP) that is consistent with ¹⁴C-based primary productivity estimates and with the observed seasonal evolution of phytoplankton biomass. A combination of physical mixing, grazing, and light availability appears to drive variability in coastal Antarctic NCP, leading to strong shifts between net autotrophy and heterotrophy on various time scales. Our approach provides insight into the metabolic responses of polar ocean ecosystems to environmental forcing and could be employed to autonomously detect climate-dependent changes in marine primary productivity

Origins of direction selectivity in the primate retina

From mouse to primate, there is a striking discontinuity in our current understanding of the neural coding of motion direction. In non-primate mammals, directionally selective cell types and circuits are a signature feature of the retina, situated at the earliest stage of the visual process. In primates, by contrast, direction selectivity is a hallmark of motion processing areas in visual cortex, but has not been found in the retina, despite significant effort. Here we combined functional recordings of light-evoked responses and connectomic reconstruction to identify diverse direction-selective cell types in the macaque monkey retina with distinctive physiological properties and synaptic motifs. This circuitry includes an ON-OFF ganglion cell type, a spiking, ON-OFF polyaxonal amacrine cell and the starburst amacrine cell, all of which show direction selectivity. Moreover, we discovered that macaque starburst cells possess a strong, non-GABAergic, antagonistic surround mediated by input from excitatory bipolar cells that is critical for the generation of radial motion sensitivity in these cells. Our findings open a door to investigation of a precortical circuitry that computes motion direction in the primate visual system.This work was largely supported by grants from the National Eye Institute (NIH NEI) to D.M.D. (EY032045), R.G.S. (EY022070), P.D.G. (EY018369) and by National Institutes of Health (NIH) Grant RR-00166 to the Tissue Distribution Program of the Washington National Primate Research Center (WaNPRC), grant P51 OD010425 from the NIH Office of Research Infrastructure Program to the WaNPRC. and EY01730 to the Vision Research Core at the University of Washington. Additional support from MICINN Programa de Movilidad Salvador de Madariaga (PRX16/00188) to F.V. and NIH (NIBIB) R21EB028069 to J.B.T, and a Christina Enroth-Cugell and David Cugell Fellowship to J.W.Peer reviewe

Preoperative Aspirin Use and Its Effect on Adverse Events in Patients Undergoing Cardiac Operations

BackgroundPreoperative aspirin use within 5 days of cardiac operations is controversial. Aspirin could reduce cardiovascular complications and yet might increase risk of bleeding. Recent reports showed conflicting results, and whether aspirin has variable effects for different cardiac surgical procedures is unclear.MethodsA single-center retrospective cohort analysis was performed. After propensity score matching (PSM) for identified confounders, the relationship between preoperative aspirin use and 30-day all-cause mortality, postoperative renal failure, major adverse cardiocerebral events (MACE), blood transfusion, reoperation for bleeding, and postoperative infection were estimated with separate logistic regression models.ResultsPreoperative aspirin therapy was associated with a 49% (p = 0.04) increased risk of reoperation for bleeding among 868 matched pairs of patients undergoing valve operations. Among 725 matched patients undergoing coronary artery bypass grafting (CABG), preoperative aspirin therapy was not associated with a statistically significant higher risk of reoperation for bleeding. However, preoperative aspirin use, compared with nonuse, was not associated with risks of MACE, 30-day mortality, postoperative renal failure, blood transfusion, or postoperative infection in the entire cohort, in patients undergoing valve operations only, and in patients undergoing CABG only after PSM.ConclusionsPreoperative aspirin use in all patients undergoing cardiac operations was not associated with risks of major cardiac, cerebral, or renal complications and infections and death; however, the risk of reoperation for bleeding was elevated among preoperative aspirin users compared with nonusers in a subpopulation of patients undergoing valve operations only

Effects of antiplatelet therapy on stroke risk by brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases: subgroup analyses of the RESTART randomised, open-label trial

Background Findings from the RESTART trial suggest that starting antiplatelet therapy might reduce the risk of recurrent symptomatic intracerebral haemorrhage compared with avoiding antiplatelet therapy. Brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases (such as cerebral microbleeds) are associated with greater risks of recurrent intracerebral haemorrhage. We did subgroup analyses of the RESTART trial to explore whether these brain imaging features modify the effects of antiplatelet therapy