Evolutionary cell biology: Functional insight from “Endless forms most beautiful”

In animal and fungal model organisms, the complexities of cell biology have been analyzed in exquisite detail and much is known about how these organisms function at the cellular level. However, the model organisms cell biologists generally use include only a tiny fraction of the true diversity of eukaryotic cellular forms. The divergent cellular processes observed in these more distant lineages are still largely unknown in the general scientific community. Despite the relative obscurity of these organisms, comparative studies of them across eukaryotic diversity have had profound implications for our understanding of fundamental cell biology in all species and have revealed the evolution and origins of previously observed cellular processes. In this Perspective, we will discuss the complexity of cell biology found across the eukaryotic tree, and three specific examples of where studies of divergent cell biology have altered our understanding of key functional aspects of mitochondria, plastids, and membrane trafficking

Surgical Treatment of Persistent Fetal Vasculature and Visual Rehabilitation: One-Year Followup

We present the management and postoperative course of a persistent fetal vasculature (PFV) case. A four-year-old girl visited the Eye Department of Hippokration, General Hospital of Thessaloniki due to reduced visual acuity of her left eye. She was diagnosed with PFV and underwent surgery (lensectomy, capsulorhexis of the posterior capsule, insertion of an intraocular lens in the posterior chamber, and posterior vitrectomy) in order to dissect the PFV. Along with the postoperative medical care, she underwent intensive treatment for amblyopia. The postoperative course was uncomplicated, and the visual acuity of her left eye improved from hand movement to 20/25 with proper correction. Patients with unilateral PFV and gradually deteriorating visual acuity could be good candidates for a combined surgical procedure, as the one described above, with a good prognosis

Cortical thickness estimation of the proximal femur from multi-view dual-energy X-ray absorptiometry

Hip fracture is the leading cause of acute orthopaedic hospital admission amongst the elderly, with around a third of patients not surviving one-year post-fracture. Current risk assessment tools ignore cortical bone thinning, a focal structural defect characterizing hip fragility. Cortical thickness can be measured using computed tomography, but this is expensive and involves a significant radiation dose. Dual-energy X-ray absorptiometry (DXA) is the preferred imaging modality for assessing fracture risk, and is used routinely in clinical practice. This thesis proposes two novel methods which measure the cortical thickness of the proximal femur from multi-view DXA scans. First, a data-driven algorithm is designed, implemented and evaluated. It relies on a femoral B-spline template which can be deformed to fit an individual’s scans. In a series of experiments on the trochanteric regions of 120 proximal femurs, the algorithm’s performance limits were established using twenty views in the range 0° – 171°: estimation errors were 0.00 ± 0.50 mm. In a clinically viable protocol using four views in the range −20° to 40°, measurement errors were −0.05 ± 0.54 mm. The second algorithm accomplishes the same task by deforming statistical shape and thickness models, both trained using Principal Component Analysis (PCA). Three training cohorts are used to investigate (a) the estimation efficacy as a function of the diversity in the training set and (b) the possibility of improving performance by building tailored models for different populations. In a series of cross-validation experiments involving 120 femurs, minimum estimation errors were 0.00 ± 0.59 mm and −0.01 ± 0.61 mm for the twenty- and four-view experiments respectively, when fitting the tailored models. Statistical significance tests reveal that the template algorithm is more precise than the statistical, and that both are superior to a blind estimator which naively assumes the population mean, but only in regions of thicker cortex. It is concluded that cortical thickness measured from DXA is unlikely to assist fracture prediction in the femoral neck and trochanters, but might have applicability in the sub-trochanteric region.This work was funded by the W. D. Armstrong Trust Fun

Development and Psychometric Evaluation of the Questionnaire of Ethical Leadership (QueL)

In this five-study paper, we developed and validated the Questionnaire of ethical Leadership (QueL). We examined the factor structure of QueL using Exploratory and Confirmatory Factor Analysis, along with measurement invariance techniques, using data from more than 1,200 leaders and subordinates working in Greece. Exploratory analysis indicated two latent highly-correlated factors that were labeled “Telos” and “Ethos.” Confirmatory analysis verified a bifactor solution. The bifactor QueL showed configural, metric, and scalar invariance across independent samples of leaders and subordinates. QueL was found to be a reliable measure across time and occupational groups (leaders and subordinates). We found criterion correlations in the expected direction with other ethical leadership scales, related constructs (i.e., integrity, trust, ethical climate), as well as workplace attitudes and behaviors (i.e., burnout, organizational commitment, organizational citizenship behaviors, deviant behaviors), leadership characteristics (transformational and transactional leadership, abusive supervision, personality), and socio-demographics (i.e., educational level and gender). We conclude that the new measure is a valuable tool for measuring workplace ethical leadership

Ultrahigh-vacuum and ambient-pressure characterisation of nickel model catalysts for enantioselective hydrogenation reactions

The adsorption of (R,R) tartaric acid (TA) on clean and oxidised Ni{100}, (S)- alanine and MAA on Ni{100} and the co-adsorption of (S)-alanine and water on Ni{110} was investigated, under UHV conditions, to obtain fundamental insights into the enantioselective sites of the chirally modified nickel catalyst, which causes the asymmetric hydrogenation of β-ketoesters. The TA/Ni{100} and (S)- alanine/Ni{100} system was also investigated under ambient pressure conditions. The characterisation of these adsorbed complexes was performed using XPS, NEXAFS, TPD, LEED and DFT. The temperature of the crystal, the dosing rate of the TA molecule and its surface coverage influence the chemical state and adsorption geometry of TA on Ni{100} (µ4/TA2- or µ2/µ3/HTA- ) with the latter being favoured, also, at elevated pressures of H2 and H2O. Deposition of TA on oxidised Ni{100}, causes the formation of tartrate species which fully decompose on the nickel surface at T>650 K (200 degrees higher than on clean Ni{100}). (S)-alanine chemisorbs on Ni{100} and Ni{110}, in its anionic and neutral form with coexistence of zwitterionic species which might not be a part of the chemisorbed layer, since these zwitterionic species are dominating the multilayer regime. The presence of PH2= 6.3 mbar destabilises thermally the alanine molecule on Ni{100} and cause the formation of neutral and (perhaps zwitterionic species) of alanine. The presence of multilayer water does not influence the decomposition temperature of alanine on Ni{110} (Tdecomposition≈400-420 K) but causes the formation of zwitterionic species. Finally DFT, XPS and NEXAFS results suggest that MAA adsorbs on Ni{100} in a tilted bidentate enolate geometry. The full decomposition of MAA on Ni{100} occurs at ∼ 350 K. The contribution of these studies into the understanding of the mechanism of the chiral modification of the nickel catalyst is thoroughly discussed in the thesis

A Management Dilemma: Infectious Keratitis Associated with Soft Contact Lens Use and Dubious Treatment Compliance

Purpose. To present a case of infectious keratitis caused by the microorganism Serratia marcescens in a contact lens user and further to confer on the most advantageous management of comparable situations. Case. After altering the routine that she used for contact lens disinfection, a 24-year-old patient presented with pain and conjunctival redness in both eyes. Slit-lamp examination revealed two infiltrates in the inferior part of the cornea in the right eye and five smaller infiltrates in the superior half of the left cornea. Appropriate treatment, after hospitalization, improved the symptoms while culture of the contact lens material revealed Serratia marcescens as the responsible infectious factor. Conclusion. Enhancing the availability of information with respect to contact lens users and customized analysis regarding treatment for a particular complication could be beneficial in order to reduce the frequency of admission to the eye clinic due to infectious keratitis. In addition, rapid laboratory testing of the infected materials should be a priority for selection of the optimal treatment regimen

A nonmitochondrial hydrogen production in Naegleria gruberi

Naegleria gruberi is a free-living heterotrophic aerobic amoeba well known for its ability to transform from an amoeba to a flagellate form. The genome of N. gruberi has been recently published, and in silico predictions demonstrated that Naegleria has the capacity for both aerobic respiration and anaerobic biochemistry to produce molecular hydrogen in its mitochondria. This finding was considered to have fundamental implications on the evolution of mitochondrial metabolism and of the last eukaryotic common ancestor. However, no actual experimental data have been shown to support this hypothesis. For this reason, we have decided to investigate the anaerobic metabolism of the mitochondrion of N. gruberi. Using in vivo biochemical assays, we have demonstrated that N. gruberi has indeed a functional [FeFe]-hydrogenase, an enzyme that is attributed to anaerobic organisms. Surprisingly, in contrast to the published predictions, we have demonstrated that hydrogenase is localized exclusively in the cytosol, while no hydrogenase activity was associated with mitochondria of the organism. In addition, cytosolic localization displayed for HydE, a marker component of hydrogenase maturases. Naegleria gruberi, an obligate aerobic organism and one of the earliest eukaryotes, is producing hydrogen, a function that raises questions on the purpose of this pathway for the lifestyle of the organism and potentially on the evolution of eukaryotes

The option market reaction to bank loan announcements

In this study, we examine the options market reaction to bank loan announcements for the population of US firms with traded options and loan announcements during 1996-2010. We get evidence on a significant options market reaction to bank loan announcements in terms of levels and changes in short-term implied volatility and its term structure, and observe significant decreases in short-term implied volatility, and significant increases in the slope of its term structure as a result of loan announcements. Our findings appear to be more pronounced for firms with more information asymmetry, lower credit ratings and loans with longer maturities and higher spreads. Evidence is consistent with loan announcements providing reassurance for investors in the short-term, however, over longer time horizons, the increase in the TSIV slope indicates that investors become increasingly unsure over the potential risks of loan repayment or uses of the proceeds