Deglacial sea surface temperatures of the western tropical Pacific : a new look at old coral

Author Posting. © American Geophysical Union, 2004. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Paleoceanography 19 (2004): PA4031, doi:10.1029/2004PA001084.Using Secondary Ion Mass Spectrometry (SIMS) ion microprobe techniques, we generated annual Sr/Ca cycles with subweekly resolution from chunks of Porites coral retrieved from a Tahiti barrier reef drill core (149°W, 17°S), representing the period 13,650 to 13,100 years B.P. The centers of pristine skeletal septa were selectively targeted with a 10 μm diameter ion beam spot, avoiding adjacent pore spaces occupied by secondary aragonite needles. Applying a Sr/Ca–sea surface temperature (SST) calibration equation derived from modern Tahiti Porites having the same low growth rate as the fossil specimens, we obtained SSTs ∼0.5°–1.5°C cooler during the Bølling-Allerod relative to the present day, with no significant change in seasonality. On the contrary, we estimate that analysis of bulk samples would yield excessively cool Sr/Ca-based SST estimates due to the occupation by secondary aragonite crystals of up to 50% of the skeletal pore space in the ancient samples. We find that growth rate effects on coral Sr/Ca further depress the apparent mean annual derived SSTs (by >3°C) and amplify the apparent seasonality by selectively enhancing wintertime cooling. Our microscale analysis of pristine skeleton and application of an appropriate growth-dependent calibration yield Sr/Ca-derived SSTs that are in good agreement with those derived from Mg/Ca ratios of calcitic foraminifera which indicate a continuous postglacial warming of the western tropical Pacific, in phase with the warming of the tropical Atlantic.Funds for this study were provided by NSF MG&G award number OCE-0241075

Environmental and diagenetic controls on the morphology and calcification of the Ediacaran metazoan Cloudina

Abstract Cloudina is a globally distributed Ediacaran metazoan, with a tubular, funnel-in-funnel form built of thin laminae (ca. 1–10 μm). To what degree local environmental controlled morphology, and whether early diagenesis controlled the degree of calcification of Cloudina, is debated. Here we test these hypotheses by considering assemblages from four, coeval localities from the Upper Omkyk Member, Nama Group, Namibia, from inner ramp to mid-ramp reef across the Zaris Subbasin. We show that sinuosity of the Cloudina tube is variable between sites, as is the relative thickness of the tube wall, suggesting these features were environmentally controlled. Walls are thickest in high-energy reef settings, and thinnest in the low-energy, inner ramp. While local diagenesis controls preservation, all diagenetic expressions are consistent with the presence of weakly calcified, organic-rich laminae, and lamina thicknesses are broadly constant. Finally, internal ‘cements’ within Cloudina are found in all sites, and pre-date skeletal breakage, transport, as well as syn-sedimentary botryoidal cement precipitation. Best preservation shows these to be formed by fine, pseudomorphed aragonitic acicular crystals. Sr concentrations and Mg/Ca show no statistically significant differences between internal Cloudina cements and botryoidal cements, but we infer all internal cements to have precipitated when Cloudina was still in-situ and added considerable mechanical strength, but may have formed post-mortem or in abandoned parts of the skeleton

Role of adenosine in epilepsy and seizures

© Mary Ann Liebert, Inc.Adenosine is an endogenous anticonvulsant and neuroprotectant of the brain. Seizure activity produces large quantities of adenosine, and it is this seizure-induced adenosine surge that normally stops a seizure. However, within the context of epilepsy, adenosine plays a wide spectrum of different roles. It not only controls seizures (ictogenesis), but also plays a major role in processes that turn a normal brain into an epileptic brain (epileptogenesis). It is involved in the control of abnormal synaptic plasticity and neurodegeneration and plays a major role in the expression of comorbid symptoms and complications of epilepsy, such as sudden unexpected death in epilepsy (SUDEP). Given the important role of adenosine in epilepsy, therapeutic strategies are in development with the goal to utilize adenosine augmentation not only for the suppression of seizures but also for disease modification and epilepsy prevention, as well as strategies to block adenosine A2A receptor overfunction associated with neurodegeneration. This review provides a comprehensive overview of the role of adenosine in epilepsy.The authors acknowledge grant support from the National Institutes of Health to D.B. (NINDS: NS103740, NS065957); support to A.M.S. by LISBOA-01-0145-FEDER-007391, project cofunded by Fundo Europeu Para o Desenvolvimento Regional through POR Lisboa 2020 (Programa Operacional Regional de Lisboa) from PORTUGAL 2020 and Fundação para a Ciência e Tecnologia (FCT), by an FCT project (PTDC/MED-FAR/30933/2017) and by Twinning action (SynaNet) from the EU H2020 programme (project number: 692340); and support to R.A.C. and A.R.T. by Fundacion LaCaixa (LCF/PR/HP17/52190001), Centro 2020 (CENTRO-01-0145-FEDER-000008: BrainHealth 2020 and CENTRO-01-0246-FEDER-000010) and FCT (POCI-01-0145-FEDER-03127).info:eu-repo/semantics/publishedVersio

Preclinical Evaluation of the Safety and Efficacy of Cryopreserved Bone Marrow Mesenchymal Stromal Cells for Corneal Repair

PurposeMesenchymal stromal cells (MSCs) have been shown to enhance tissue repair as a cell-based therapy. In preparation for a phase I clinical study, we evaluated the safety, dosing, and efficacy of bone marrow-derived MSCs after subconjunctival injection in preclinical animal models of mice, rats, and rabbits.MethodsHuman bone marrow-derived MSCs were expanded to passage 4 and cryopreserved. Viability of MSCs after thawing and injection through small-gauge needles was evaluated by vital dye staining. The in vivo safety of human and rabbit MSCs was studied by subconjunctivally injecting MSCs in rabbits with follow-up to 90 days. The potency of MSCs on accelerating wound healing was evaluated in vitro using a scratch assay and in vivo using 2-mm corneal epithelial debridement wounds in mice. Human MSCs were tracked after subconjunctival injection in rat and rabbit eyes.ResultsThe viability of MSCs after thawing and immediate injection through 27- and 30-gauge needles was 93.1% ± 2.1% and 94.9% ± 1.3%, respectively. Rabbit eyes demonstrated mild self-limiting conjunctival inflammation at the site of injection with human but not rabbit MSCs. In scratch assay, the mean wound healing area was 93.5% ± 12.1% in epithelial cells co-cultured with MSCs compared with 40.8% ± 23.1% in controls. At 24 hours after wounding, all MSC-injected murine eyes had 100% corneal wound closure compared with 79.9% ± 5.5% in controls. Human MSCs were detectable in the subconjunctival area and peripheral cornea at 14 days after injection.ConclusionsSubconjunctival administration of MSCs is safe and effective in promoting corneal epithelial wound healing in animal models.Translational relevanceThese results provide preclinical data to support a phase I clinical study

Coral records of central tropical Pacific radiocarbon variability during the last millennium

The relationship between decadal to centennial changes in ocean circulation and climate is difficult to discern using the sparse and discontinuous instrumental record of climate and, as such, represents a large uncertainty in coupled ocean-atmosphere general circulation models. We present new modern and fossil coral radiocarbon (Δ14C) records from Palmyra (6°N, 162°W) and Christmas (2°N, 157°W) islands to constrain central tropical Pacific ocean circulation changes during the last millennium. Seasonally to annually resolved coral Δ14C measurements from the 10th, 12th–17th, and 20th centuries do not contain significant interannual to decadal-scale variations, despite large changes in coral δ 18O on these timescales. A centennial-scale increase in coral radiocarbon from the Medieval Climate Anomaly (∼900–1200 AD) to the Little Ice Age (∼1500–1800) can be largely explained by changes in the atmospheric Δ14C, as determined with a box model of Palmyra mixed layer Δ14C. However, large 12th century depletions in Palmyra coral Δ14C may reflect as much as a 100% increase in upwelling rates and/or a significant decrease in the Δ14C of higher-latitude source waters reaching the equatorial Pacific during this time. SEM photos reveal evidence for minor dissolution and addition of secondary aragonite in the fossil corals, but our results suggest that coral Δ14C is only compromised after moderate to severe diagenesis for these relatively young fossil corals