“Vital effects" in the 13C-18O clumped isotopic composition of marine macro-invertebrates: exploring biologically mediated disequilibrium effects in echinoids and cephalopods

The stable oxygen isotopic composition of marine carbonate has historically been widely used for paleoclimate reconstruction (Emiliani 1955; Zachos 2001). This technique however applies an a priori assumption of δ18O of the seawater. Furthermore, while the stable oxygen isotopic composition of some taxa faithfully reflects both the temperature and the δ18Oseawater other taxa show specific discrepancies known as “vital effects” (Epstein et al. 1951). The carbonate clumped isotope paleothermometer examines thermodynamically dependent “clumping” of 13C and 18O within the carbonate crystal lattice. This allows calculation of carbonate formation temperature independent of the δ18O of seawater (Ghosh et al. 2006; Eiler 2007). Initially inorganic and biogenic calibrations of the clumped isotope thermometer appeared reasonably congruent (Eiler 2011, Ghosh et al. 2006; Tripati et al. 2010a). Further studies however revealed vital effects in the clumped isotopic composition of corals (Thiagarajan et al. 2011; Saenger et al. 2012) with potential vital effects indicated in molluscs (Henkes et al. 2013). In this study we assess how robust the clumped isotope thermometer is to biologically mediated non-equilibrium precipitation (vital effects) by (1) measuring the clumped isotope composition of the previously uninvestigated echinoderm group and (2) verifying and further quantifying offsets in the clumped isotope composition of modern cephalopod molluscs. This aim necessitated further refinements CO2 purification for clumped isotope analysis, also presented within this thesis. The results of this thesis indicate that non-equilibrium signatures in the clumped isotope composition of biogenic materials are more common than initially assumed (Eiler, 2011). Furthermore the manifestation of vital effects does not to occur by a single mechanism, but varies dependent on biomineralization pathway. This has significant implications for the way in which the clumped isotope composition of biogenic carbonate is used in paleoclimate reconstruction. We can no longer unreservedly assume equilibrium precipitation in the 13C-18O composition of biogenic carbonate necessitating the creation of group specific calibrations using modern genera prior to the use of previously unmeasured groups in paloeclimatic reconstruction. Small non-equilibirum offsets in the 13C-18O compositions in echinoids may be corrected. Nautili however display inter-individual variation in 13C-18O such that correction for non-equilbirum effects may be not be possible, precluding the use of the clumped isotopic composition of groups such as the ammonites in paleoclimatic reconstruction.Open Acces

Dosing regimen of meropenem for adults with severe burns : a population pharmacokinetic study with Monte Carlo simulations

Objectives To develop a population model to describe the pharmacokinetics (PK) of intravenous meropenem in adult patients with severe burns and investigate potential relationships between dosage regimens and antimicrobial efficacy.Patients and methods A dose of 1 g every 8 h was administered to adult patients with total body surface area burns of ≥15%. Doses for subsequent courses were determined using results from the initial course and the patient's clinical condition. Five plasma meropenem concentrations were typically measured over the dosage interval on one to four occasions. An open, two-compartment PK model was fitted to the meropenem concentrations using NONMEM and the effect of covariates on meropenem PK was investigated. Monte Carlo simulations investigated dosage regimens to achieve a target T>MIC for ≥40%, ≥60% or ≥80% of the dose interval.Results Data comprised 113 meropenem concentration measurements from 20 dosage intervals in 12 patients. The parameters were CL (L/h) = 0.196 L/h/kg × [1 − 0.023 × (age − 46)] × [1 − 0.049 × (albumin − 15)], V1 = 0.273 L/kg × [1 − 0.049 × (albumin − 15)], Q = 0.199 L/h/kg and V2 = 0.309 L/kg × [1 – 0.049 × (albumin − 15)]. For a target of ≥80% T>MIC, the breakpoint was 8 mg/L for doses of 1 g every 4 h and 2 g every 8 h given over 3 h, but only 4 mg/L if given over 5 min.Conclusions Although 1 g 8 hourly should be effective against Escherichia coli and CoNS, higher doses, ideally with a longer infusion time, would be more appropriate for empirical therapy, mixed infections and bacteria with MIC values ≥4 mg/L

Impact of T2R38 receptor polymorphisms on Pseudomonas aeruginosa infection in cystic fibrosis

The T2R38 (taste receptor 2 member 38) bitter taste receptor on respiratory epithelia detects Pseudomonas aeruginosa N-acyl-l-homoserine lactones (AHLs). In vitro, T2R38 activation by AHLs initiates calcium-mediated increases in nitric oxide production and ciliary beat frequency, dependent on polymorphisms in the TAS2R38 gene (1). In patients with chronic rhinosinusitis, the TAS2R38 genotype is proposed to modify mucosal responses to P. aeruginosa (1). Polymorphisms in the TAS2R38 gene result in two high-frequency haplotypes associated with taste perception of the bitter compound phenylthiocarbamide (2). The “taster” haplotype codes proline-alanine-valine (PAV), and the “nontaster” haplotype codes alanine-valine-isoleucine (AVI) at positions 49, 262, and 296 in the receptor protein. Responses to AHLs in vitro are greatest in PAV/PAV epithelial cells, and this genotype is reported to be protective against P. aeruginosa in the sinonasal airway (1). P. aeruginosa is the most frequently isolated respiratory pathogen in cystic fibrosis (CF), and chronic infection is associated with accelerated rates of disease progression. Determining the impact of TAS2R38 polymorphisms on P. aeruginosa infection in CF could have implications for patient risk stratification and, as naturally occurring and synthetic agonists to T2R38 are already in clinical use (3), could identify promising therapeutic targets. We characterized T2R38 localization in the CF airway and investigated the hypothesis that TAS2R38 polymorphisms would modify the prevalence and impact of P. aeruginosa infection in CF. Some of the results of these studies have previously been reported in the form of abstracts

Nitrous Oxide Dynamics in the Siberian Arctic Ocean and Vulnerability to Climate Change

Nitrous oxide (N2O) is a strong greenhouse gas and stratospheric ozone-depleting substance. Around 20% of global emissions stem from the ocean, but current estimates and future projections are uncertain due to poor spatial coverage over large areas and limited understanding of drivers of N2O dynamics. Here, we focus on the extensive and particularly data-lean Arctic Ocean shelves north of Siberia that experience rapid warming and increasing input of land-derived nitrogen with permafrost thaw. We combine water column N2O measurements from two expeditions with on-board incubation of intact sediment cores to assess N2O dynamics and the impact of land-derived nitrogen. Elevated nitrogen concentrations in water column and sediments were observed near large river mouths. Concentrations of N2O were only weakly correlated with dissolved nitrogen and turbidity, reflecting particulate matter from rivers and coastal erosion, and correlations varied between river plumes. Surface water N2O concentrations were on average close to equilibrium with the atmosphere, but varied widely (N2O saturation 38%–180%), indicating strong local N2O sources and sinks. Water column N2O profiles and low sediment-water N2O fluxes do not support strong sedimentary sources or sinks. We suggest that N2O dynamics in the region are influenced by water column N2O consumption under aerobic conditions or in anoxic microsites of particles, and possibly also by water column N2O production. Changes in biogeochemical and physical conditions will likely alter N2O dynamics in the Siberian Arctic Ocean over the coming decades, in addition to reduced N2O solubility in a warmer ocean.publishedVersio

Assessment of F/HN-Pseudotyped Lentivirus as a Clinically Relevant Vector for Lung Gene Therapy

RATIONALE: Ongoing efforts to improve pulmonary gene transfer thereby enabling gene therapy for the treatment of lung diseases, such as cystic fibrosis (CF), has led to the assessment of a lentiviral vector (simian immunodeficiency virus [SIV]) pseudotyped with the Sendai virus envelope proteins F and HN. OBJECTIVES: To place this vector onto a translational pathway to the clinic by addressing some key milestones that have to be achieved. METHODS: F/HN-SIV transduction efficiency, duration of expression, and toxicity were assessed in mice. In addition, F/HN-SIV was assessed in differentiated human air-liquid interface cultures, primary human nasal epithelial cells, and human and sheep lung slices. MEASUREMENTS AND MAIN RESULTS: A single dose produces lung expression for the lifetime of the mouse (~2 yr). Only brief contact time is needed to achieve transduction. Repeated daily administration leads to a dose-related increase in gene expression. Repeated monthly administration to mouse lower airways is feasible without loss of gene expression. There is no evidence of chronic toxicity during a 2-year study period. F/HN-SIV leads to persistent gene expression in human differentiated airway cultures and human lung slices and transduces freshly obtained primary human airway epithelial cells. CONCLUSIONS: The data support F/HN-pseudotyped SIV as a promising vector for pulmonary gene therapy for several diseases including CF. We are now undertaking the necessary refinements to progress this vector into clinical trials

Effect of Hydrocortisone on Mortality and Organ Support in Patients With Severe COVID-19: The REMAP-CAP COVID-19 Corticosteroid Domain Randomized Clinical Trial.

Importance: Evidence regarding corticosteroid use for severe coronavirus disease 2019 (COVID-19) is limited. Objective: To determine whether hydrocortisone improves outcome for patients with severe COVID-19. Design, Setting, and Participants: An ongoing adaptive platform trial testing multiple interventions within multiple therapeutic domains, for example, antiviral agents, corticosteroids, or immunoglobulin. Between March 9 and June 17, 2020, 614 adult patients with suspected or confirmed COVID-19 were enrolled and randomized within at least 1 domain following admission to an intensive care unit (ICU) for respiratory or cardiovascular organ support at 121 sites in 8 countries. Of these, 403 were randomized to open-label interventions within the corticosteroid domain. The domain was halted after results from another trial were released. Follow-up ended August 12, 2020. Interventions: The corticosteroid domain randomized participants to a fixed 7-day course of intravenous hydrocortisone (50 mg or 100 mg every 6 hours) (n = 143), a shock-dependent course (50 mg every 6 hours when shock was clinically evident) (n = 152), or no hydrocortisone (n = 108). Main Outcomes and Measures: The primary end point was organ support-free days (days alive and free of ICU-based respiratory or cardiovascular support) within 21 days, where patients who died were assigned -1 day. The primary analysis was a bayesian cumulative logistic model that included all patients enrolled with severe COVID-19, adjusting for age, sex, site, region, time, assignment to interventions within other domains, and domain and intervention eligibility. Superiority was defined as the posterior probability of an odds ratio greater than 1 (threshold for trial conclusion of superiority >99%). Results: After excluding 19 participants who withdrew consent, there were 384 patients (mean age, 60 years; 29% female) randomized to the fixed-dose (n = 137), shock-dependent (n = 146), and no (n = 101) hydrocortisone groups; 379 (99%) completed the study and were included in the analysis. The mean age for the 3 groups ranged between 59.5 and 60.4 years; most patients were male (range, 70.6%-71.5%); mean body mass index ranged between 29.7 and 30.9; and patients receiving mechanical ventilation ranged between 50.0% and 63.5%. For the fixed-dose, shock-dependent, and no hydrocortisone groups, respectively, the median organ support-free days were 0 (IQR, -1 to 15), 0 (IQR, -1 to 13), and 0 (-1 to 11) days (composed of 30%, 26%, and 33% mortality rates and 11.5, 9.5, and 6 median organ support-free days among survivors). The median adjusted odds ratio and bayesian probability of superiority were 1.43 (95% credible interval, 0.91-2.27) and 93% for fixed-dose hydrocortisone, respectively, and were 1.22 (95% credible interval, 0.76-1.94) and 80% for shock-dependent hydrocortisone compared with no hydrocortisone. Serious adverse events were reported in 4 (3%), 5 (3%), and 1 (1%) patients in the fixed-dose, shock-dependent, and no hydrocortisone groups, respectively. Conclusions and Relevance: Among patients with severe COVID-19, treatment with a 7-day fixed-dose course of hydrocortisone or shock-dependent dosing of hydrocortisone, compared with no hydrocortisone, resulted in 93% and 80% probabilities of superiority with regard to the odds of improvement in organ support-free days within 21 days. However, the trial was stopped early and no treatment strategy met prespecified criteria for statistical superiority, precluding definitive conclusions. Trial Registration: ClinicalTrials.gov Identifier: NCT02735707

Post-intervention Status in Patients With Refractory Myasthenia Gravis Treated With Eculizumab During REGAIN and Its Open-Label Extension

OBJECTIVE: To evaluate whether eculizumab helps patients with anti-acetylcholine receptor-positive (AChR+) refractory generalized myasthenia gravis (gMG) achieve the Myasthenia Gravis Foundation of America (MGFA) post-intervention status of minimal manifestations (MM), we assessed patients' status throughout REGAIN (Safety and Efficacy of Eculizumab in AChR+ Refractory Generalized Myasthenia Gravis) and its open-label extension. METHODS: Patients who completed the REGAIN randomized controlled trial and continued into the open-label extension were included in this tertiary endpoint analysis. Patients were assessed for the MGFA post-intervention status of improved, unchanged, worse, MM, and pharmacologic remission at defined time points during REGAIN and through week 130 of the open-label study. RESULTS: A total of 117 patients completed REGAIN and continued into the open-label study (eculizumab/eculizumab: 56; placebo/eculizumab: 61). At week 26 of REGAIN, more eculizumab-treated patients than placebo-treated patients achieved a status of improved (60.7% vs 41.7%) or MM (25.0% vs 13.3%; common OR: 2.3; 95% CI: 1.1-4.5). After 130 weeks of eculizumab treatment, 88.0% of patients achieved improved status and 57.3% of patients achieved MM status. The safety profile of eculizumab was consistent with its known profile and no new safety signals were detected. CONCLUSION: Eculizumab led to rapid and sustained achievement of MM in patients with AChR+ refractory gMG. These findings support the use of eculizumab in this previously difficult-to-treat patient population. CLINICALTRIALSGOV IDENTIFIER: REGAIN, NCT01997229; REGAIN open-label extension, NCT02301624. CLASSIFICATION OF EVIDENCE: This study provides Class II evidence that, after 26 weeks of eculizumab treatment, 25.0% of adults with AChR+ refractory gMG achieved MM, compared with 13.3% who received placebo

Minimal Symptom Expression' in Patients With Acetylcholine Receptor Antibody-Positive Refractory Generalized Myasthenia Gravis Treated With Eculizumab

The efficacy and tolerability of eculizumab were assessed in REGAIN, a 26-week, phase 3, randomized, double-blind, placebo-controlled study in anti-acetylcholine receptor antibody-positive (AChR+) refractory generalized myasthenia gravis (gMG), and its open-label extension

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead