As a result of anthropogenic pCO2 increases, future oceans are growing warmer and lower in pH and oxygen, conditions that are likely to impact planktic communities. Past intervals of elevated and ...changing pCO2 and temperatures can offer a glimpse into the response of marine calcifying plankton to changes in surface oceans under conditions similar to those projected for the future. Here we present new records of planktic foraminiferal and coccolith calcification (weight and size) from Deep Sea Drilling Project Site 607 (mid-North Atlantic) and Ocean Drilling Program Site 999 (Caribbean Sea) from the Pliocene, the last time that pCO2 was similar to today, and extending through a global cooling event into the intensification of Northern Hemisphere glaciation (3.3 to 2.6 million years ago). Test weights of both surface-dwelling Foraminifera Globigerina bulloides and thermocline-dwelling Foraminifera Globorotalia puncticulata vary with a potential link to regional temperature variation in the North Atlantic, whereas in the tropics Globigerinoides ruber test weight remains stable. In contrast, reticulofenestrid coccoliths show a narrowing size range and a decline in the largest lith diameters over this interval. Our results suggest no major changes in plankton calcite production during the high pCO2 Pliocene or during the transition into an icehouse world.
The objective of this review was to identify causes of stroke/death after carotid endarterectomy (CEA) and to develop transferable strategies for preventing stroke/death after CEA, via an overview of ...a 21-year series of themed research and audit projects. Three preventive strategies were identified: (i) intra-operative transcranial Doppler (TCD) ultrasound and completion angioscopy which virtually abolished intra-operative stroke, primarily through the removal of residual luminal thrombus prior to restoration of flow; (ii) dual antiplatelet therapy with a single 75-mg dose of clopidogrel the night before surgery in addition to regular 75 mg aspirin which virtually abolished post-operative thromboembolic stroke and may also have contributed towards a decline in stroke/death following major cardiac events; and (iii) the provision of written guidance for managing post-CEA hypertension which was associated with virtual abolition of intracranial haemorrhage and stroke as a result of hyperperfusion syndrome. The pathophysiology of peri-operative stroke is multifactorial and no single monitoring or therapeutic strategy will reduce its prevalence. Two of the preventive strategies developed during this 21-year project (peri-operative dual antiplatelet therapy, published guidance for managing post-CEA hypertension) are easily transferable to practices elsewhere.
Late Paleocene and early Eocene hyperthermals are transient warming events associated with massive perturbations of the global carbon cycle, and are considered partial analogues for current ...anthropogenic climate change. Because the magnitude of carbon release varied between the events, they are natural experiments ideal for exploring the relationship between carbon cycle perturbations, climate change and biotic response. Here we quantify marine biotic variability through three million years of the early Eocene that include five hyperthermals, utilizing a method that allows us to integrate the records of different plankton groups through scenarios ranging from background to major extinction events. Our long time-series calcareous nannoplankton record indicates a scaling of biotic disruption to climate change associated with the amount of carbon released during the various hyperthermals. Critically, only the three largest hyperthermals, the Paleocene-Eocene Thermal Maximum (PETM), Eocene Thermal Maximum 2 (ETM2) and the I1 event, show above-background variance, suggesting that the magnitude of carbon input and associated climate change needs to surpass a threshold value to cause significant biotic disruption.
Despite advances in surgery, anaesthesia, and critical care, mortality from ruptured abdominal aortic aneurysms (AAAs) has not decreased over the last 20 years. Endovascular aneurysm repair (EVAR) of ...ruptured AAAs is an alternative to open repair, which may improve outcome. However, a computed tomography (CT) scan is usually required to assess the anatomic suitability of the aneurysm for EVAR. This may result in delay in transferring patients to the operating room. We evaluated all patients admitted to hospital with a ruptured AAA who died without undergoing surgery, to determine time to death after AAA rupture and thus the potential time available for obtaining a CT scan.
A retrospective case note review was conducted of 56 patients admitted to a single center with ruptured AAAs who did not undergo surgery because of advanced age or associated comorbidity over 8 years from 1995 to 2003. Statistical analysis was performed with the Fisher exact test.
The 56 patients (33 men, 59%; 23 women, 41%) had a median age of 85 years (range, 71-98 years). Reasons for no operation being performed were shock (9%), cardiac arrest (11%), quality of life (29%), malignancy (7%), cardiac disease (15%), respiratory disease (16%) and age (14%). Median systolic blood pressure at admission was 110 mm Hg, heart rate was 88 beats per minute, and hemoglobin concentration was 10.5 g/dL. Patients were not aggressively resuscitated once a decision was made to not perform surgery. Death within 2 hours of hospital admission occurred in 7 (12.5%) patients, and 49 (87.5%) patients died more than 2 hours after admission. Median interval between onset of symptoms and admission to hospital was 2 hours 30 minutes (range, 44 minutes–36 hours), and the median interval between admission and death was 10 hours 45 minutes (range, 1 hour 1 minute–143 hours 55 minutes). The median total time to death from onset of symptoms was 16 hours 38 minutes (range, 2 hours 6 minutes–146 hours 50 minutes).
Most (87.5%) patients admitted to hospital with a ruptured AAA died after more than 2 hours. These data show that most patients with a ruptured AAA who reach the hospital alive are sufficiently stable to undergo CT and consideration of EVAR.
Calcareous nannoplankton diversity, evolutionary rates and species longevity show markedly different characters above and below the Cretaceous/Tertiary boundary. Excluding mass extinction events, and ...the initial origination and radiation, Mesozoic nannoplankton diversity is characterized by relatively continuous increase with low background evolutionary rates and high species longevity. Cenozoic diversity is more variable and features significant Eocene and Neogene diversity declines, with little or no recovery. Cenozoic evolutionary rates are also consistently higher than those of the Mesozoic, and species longevity is low. The response of nannoplankton to climate cooling in the two eras is particularly revealing: cold intervals in the Cretaceous saw greater paleobiogeographical differentiation and high-latitude nannoplankton provinces that supported diversifying communities, whereas, cooling in the Eocene and Neogene coincided with diversity declines, the selective extinction of warm-water taxa, and high-latitude provinces with reduced diversity. It appears likely that the presence of widespread stable, subtropical and tropical oligotrophic water masses promoted the diversification of the broadly K-strategist calcareous nannoplankton (and dinoflagellates) for much of the Mesozoic and into the early Paleogene. The switch to an icehouse climate, however, transformed the oceans, favouring the r-strategist diatoms at the expense of the other phytoplankton groups. The profound Eocene cooling established new, cold-water habitats that limited calcareous nannoplankton habitation and diversification, but promoted diatom expansion and diversification at high latitudes. Diatoms became the most competitive of the phytoplankton groups, flourishing in all environments but particularly those with high and pulsed nutrient inputs, although their expansion may also have been aided by tectonic and biological factors that increased the flux of biolimiting silica to the oceans.
Inhibition of serotonergic raphe neurons is mediated by somatodendritic 5-HT1A autoreceptors, which may be increased in depressed patients. We report an association of the C(-1019)G 5-HT1A promoter ...polymorphism with major depression and suicide in separate cohorts. In depressed patients, the homozygous G(-1019) allele was enriched twofold versus controls (p = 0.0017 and 0.0006 for G/G genotype and G allele distribution, respectively), and in completed suicide cases the G(-1019) allele was enriched fourfold (p = 0.002 and 0.00008 for G/G genotype and G allele distribution, respectively). The C(-1019) allele was part of a 26 bp imperfect palindrome that bound transcription factors nuclear NUDR nuclear deformed epidermal autoregulatory factor (DEAF-1)/suppressin and Hairy/Enhancer-of-split-5 (Drosophila) (Hes5) to repress 5-HT1A or heterologous promoters, whereas the G(-1019) allele abolished repression by NUDR, but only partially impaired Hes5-mediated repression. Recombinant NUDR bound specifically to the 26 bp palindrome, and endogenous NUDR was present in the major protein-DNA complex from raphe nuclear extracts. Stable expression of NUDR in raphe cells reduced levels of endogenous 5-HT1A protein and binding. NUDR protein was colocalized with 5-HT1A receptors in serotonergic raphe cells, hippocampal and cortical neurons, and adult brain regions including raphe nuclei, indicating a role in regulating 5-HT1A autoreceptor expression. Our data indicate that NUDR is a repressor of the 5-HT1A receptor in raphe cells the function of which is abrogated by a promoter polymorphism. We suggest a novel transcriptional model in which the G(-1019) allele derepresses 5-HT1A autoreceptor expression to reduce serotonergic neurotransmission, predisposing to depression and suicide.
Oceanic Anoxic Events (OAEs) are important geological events that may be analogues to future climate-driven deoxygenation of our oceans. Much of the global ocean experienced anoxic conditions during ...the Cenomanian–Turonian OAE (OAE2; ∼94 Ma), whereas the Western Interior Seaway (WIS) experienced oxygenation at this time. Here, organic geochemical and palynological data generated from Cenomanian–Turonian age sediments from five sites in the WIS are used to investigate changing redox and ecological conditions across differing palaeoenvironments and palaeolatitudes. Heterogeneity across the sites is apparent, but important relationships and trends among oceanographic variables are recognised: 1) Increasing total organic carbon (TOC) and CaCO3 percentages indicate the onset of a sea-level maximum towards the end of OAE2; 2) C28 sterane is shown to be a useful marker for prasinophyte abundance, and concurrent increases in this marker and overall sterane abundance indicate prasinophyte-driven increase in algal productivity in a stratified water column; and 3) sterane ratios can be a more reliable geochemical proxy than redox proxies for assessing the Benthic Oxic Zone. Our redox data do not always follow established trends for the WIS overall, particularly for proximal settings. We therefore surmise that local effects, such as nutrient-driven expansion of the oxygen minimum zone and/or sedimentation-driven anoxia just below the sediment-water interface, have overprinted regional trends.
•Five sites across the Western Interior Seaway show highly variable trends.•Local processes can overprint regional trends.•C28 sterane is a useful marker for low-oxygen, stressed biotic environments.•An oceanographic mixing front is proposed near the Billings Landfill site.
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