Complexation Behavior of the Tri-n-butyl Phosphate Ligand with Pu(IV) and Zr(IV): A Computational Study

Tri-n-butyl phosphate (TBP), used as the extractant in nuclear fuel reprocessing, shows superior extraction abilities for Pu(IV) over a large number of fission products including Zr(IV). We have applied density functional theory (DFT) calculations to explain this selectivity by investigating differences in electronic structures of Pu(NO3)4·2TBP and Zr(NO3)4·2TBP complexes. On the basis of our quantum chemical calculations, we have established the lowest energy electronic states for both complexes; the quintet is the ground state for the former, whereas the latter exists in the singlet spin state. The calculated structural parameters for the optimized geometry of the plutonium complex are in agreement with the experimental results. Atoms in Molecules analysis revealed a considerable amount of ionic character to M-O{TBP} and M-O{NO3} bonds. Additionally, we have also investigated the extraction behavior of TBP for metal nitrates and have estimated the extraction energies to be -73.1 and -57.6 kcal/mol for Pu(IV) and Zr(IV), respectively. The large extraction energy of Pu(IV) system is in agreement with the observed selectivity in the extraction of Pu.

Gender Differences in HIV-Related Neurological Progression in a Cohort of Injecting Drug Users Followed for 3.5 Years

We evaluated potential gender differences in the development of HIV related neurologic impairment, by matching 38 pairs of HIV positive male and female injecting drug users on their baseline age, education, disease stage and CD4 counts, and following them for 3.5 years. Adjusting for age, education, drug use, history of head injury and baseline CD4 count, more women had sensory abnormalities and symptoms than men at baseline, but the odds of having neurological impairment, particularly extrapyramidal signs and sensory abnormalities were increased over time in men but not in women. Men with ARC or AIDS had more neurological impairment than women in similar stages of illness. This study suggests further investigations of gender differences in HIV disease progression.

Age-dependent neuroinflammation and cognitive decline in a novel Ala152Thr-Tau transgenic mouse model of PSP and AD

Introduction

Mutations of Tau are associated with several neurodegenerative disorders. Recently, the Tau mutation A152T was described as a novel risk factor for frontotemporal dementia spectrum disorders and Alzheimer disease. In vitro Tau-A152T shows a decreased binding to microtubules and a reduced tendency to form abnormal fibers.

Results

To study the effects of this mutation we generated a mouse model expressing human full-length Tau with this mutation (hTau40^AT). At young age (2–3 months) immunohistological analysis reveals pathological Tau conformation and Tau-hyperphosphorylation combined with Tau missorting into the somatodendritic compartment of neurons. With increasing age there is Tau aggregation including co-aggregates of endogenous mouse Tau and exogenous human Tau, accompanied by loss of synapses (especially presynaptic failure) and neurons. From ~10 months onwards the mice show a prominent neuroinflammatory response as judged by activation of microglia and astrocytes. This progressive neuroinflammation becomes visible by in vivo bioluminescence imaging after crossbreeding of hTau40^AT mice and Gfap-luciferase reporter mice. In contrast to other Tau-transgenic models and Alzheimer disease patients with reduced protein clearance, hTau40^AT mice show a strong induction of autophagy. Although Tau-hyperphosphorylation and aggregation is also present in spinal cord and motor cortex (due to the Thy1.2 promoter), neuromotor performance is not affected. Deficits in spatial reference memory are manifest at ~16 months and are accompanied by neuronal death.

Conclusions

The hTau40^AT mice mimic pathological hallmarks of tauopathies including a cognitive phenotype combined with pronounced neuroinflammation visible by bioluminescence. Thus the mice are suitable for mechanistic studies of Tau induced toxicity and in vivo validation of neuroprotective compounds.

Electronic supplementary material

The online version of this article (doi:10.1186/s40478-016-0281-z) contains supplementary material, which is available to authorized users.

Ligand sensitized luminescence of uranyl by benzoic acid in acetonitrile medium: a new luminescent uranyl benzoate specie

Benzoic acid (BA) is shown to sensitize and enhance the luminescence of uranyl ion in acetonitrile medium. Luminescence spectra and especially UV-Vis spectroscopy studies reveal the formation of tri benzoate complex of uranyl i.e. [UO2(C6H5COO)3](-) which is highly luminescent. In particular, three sharp bands at 431, 443, 461nm of absorption spectra provides evidence for tri benzoate specie of uranyl in acetonitrile medium. The luminescence lifetime of uranyl in this complex is 68μs which is much more compared to the lifetime of uncomplexed uranyl (20μs) in acetonitrile medium. In contrary to aqueous medium where uranyl benzoate forms 1:1 and 1:2 species, spectroscopic data reveal formation of 1:3 complex in acetonitrile medium. Addition of water to acetonitrile results in decrease of luminescence intensity of this specie and the luminescence features implode at 20% (v/v) of water content. For the first time, to the best of our knowledge, the existence of [UO2(C6H5COO)3](-) specie in acetonitrile is reported. Mechanism of luminescence enhancement is discussed.

From parasites to allergy: a second receptor for IgE

Human allergic responses are triggered when mast cells bind IgE antibodies. IgE production is also a regular feature of helminth infection and parasites can be killed by inflammatory cells such as macrophages, eosinophils and platelets sensitized by reaginic antibody. The IgE receptor they use has been identified only recently. Here André Capron and his colleagues discuss how it differs from the IgE receptor present on mast cells.

Impact of the introduction of weekly radiotherapy quality assurance meetings at one UK cancer centre

OBJECTIVE

The complexity of radiotherapy planning is increasing rapidly. Delivery and planning is subject to detailed quality assurance (QA) checks. The weakest link is often the oncologists' delineation of the clinical target volume (CTV). Weekly departmental meetings for radiotherapy QA (RTQA) were introduced into the Royal Wolverhampton Hospital, Wolverhampton, UK, in October 2011. This article describes the impact of this on patient care.

METHODS

CTVs for megavoltage photon radiotherapy courses for all radical, adjuvant and palliative treatments longer than five fractions (with the exception of two field tangential breast treatments not enrolled into clinical trials) were reviewed in the RTQA meeting. Audits were carried out in January 2012 (baseline) and September 2013, each over a 4-week period. Adherence to departmental contouring protocols was assessed and the number of major and minor alterations following peer review were determined.

RESULTS

There was no statistically significant difference for major alterations between the two study groups; 8 alterations in 80 patients (10%) for the baseline audit vs 3 alterations from 72 patients (4.2%) in the second audit (p = 0.17). A trend towards a reduction in alterations following peer review was observed. There has, however, been a change in practice resulting in a reduction in variation in CTV definition within our centre and greater adherence to protocols. There is increasing confidence in the quality and constancy of care delivered.

CONCLUSION

Introduction of a weekly QA meeting for target volume definition has facilitated consensus and adoption of departmental clinical guidelines within the unit.

ADVANCES IN KNOWLEDGE

The weakest areas in radiotherapy are patient selection and definition of the CTV. Engagement in high-quality RTQA is paramount. This article describes the impact of this in one UK cancer centre.

Artificially-induced organelles are optimal targets for optical trapping experiments in living cells

Optical trapping supplies information on the structural, kinetic or rheological properties of inner constituents of the cell. However, the application of significant forces to intracellular objects is notoriously difficult due to a combination of factors, such as the small difference between the refractive indices of the target structures and the cytoplasm. Here we discuss the possibility of artificially inducing the formation of spherical organelles in the endoplasmic reticulum, which would contain densely packed engineered proteins, to be used as optimized targets for optical trapping experiments. The high index of refraction and large size of our organelles provide a firm grip for optical trapping and thereby allow us to exert large forces easily within safe irradiation limits. This has clear advantages over alternative probes, such as subcellular organelles or internalized synthetic beads.

The liver to abdominal area ratio (LAAR): a novel imaging score for prognostication in cirrhosis

BACKGROUND

Anecdotally, liver size is important in determining prognosis in patients with end-stage liver disease (ESLD).

AIMS

To assess if a ratio of liver area and abdominal area on cross-sectional imaging could accurately predict mortality in ESLD.

METHODS

A retrospective-prospective cohort study was performed on patients with ESLD in a training set. The censor point used was date of patient death or liver transplant (LT). The liver to abdominal area ratio (LAAR) was calculated using the formula {LAAR = [liver area (cm(2))/abdominal area (cm(2))] × 100}. A validation set was collected from a different institution.

RESULTS

Three hundred and sixteen patients were identified. Complete imaging and survival data were available in 158 subjects, 100 male (63%). The LAAR score detected progression to death/LT in our cohort (P < 0.003). Its prognostic accuracy at 90, 360 and 720 days, using the optimal cut-off (32.1), from baseline CT date to death/LT using the log-rank test was P = 0.28, P = 0.06 (OR 1.347, 95% CI 0.94-1.94) and P < 0.0001 (OR 1.89, 95% CI 1.25-2.85) respectively. On multivariate analysis, LAAR (P = 0.008), MELD (P = 0.004) and MELD-Na (P = 0.03) were independently associated with the primary study outcome measurement at 720 days. The validation set of 52 patients confirmed the utility of the LAAR to determine risk of death or need for LT, AUROC 0.89 (0.78-0.97), and P < 0.0001.

CONCLUSIONS

The liver to abdominal area ratio (LAAR) score offers a new paradigm in disease modelling in end-stage liver disease (ESLD) and offers prognostic accuracy at 2 years from computer tomography (CT) imaging.

Ocular complications and loss of vision due to herpes zoster ophthalmicus in patients with HIV infection and a comparison with HIV-negative patients

The aim of the work is to describe the occurrence of ocular complications and loss of vision due to herpes zoster ophthalmicus (HZO) in HIV-positive patients who received early antiviral therapy for HZO. This is a post hoc analysis of prospectively collected data. Twenty-four HIV-positive patients with HZO were included in this report; male to female ratio was 3.8:1; mean age was 33.5 (±14.9) years. The visual outcome was good, with 14/24 patients having 6/6 vision; severe vision loss (≤6/60) occurred in only 2/24. There was no statistical difference in the visual outcome between the HIV-positive and -negative patients ( P = 0.69), although severe vision loss was more likely in HIV-infected patients. The ocular complications of HZO in HIV-infected patients were: reduced corneal sensation (17/24), corneal epithelial lesions (14/24), uveitis (12/24), elevated intraocular pressure (10/24) and extra-ocular muscle palsy (3/24). The severity of rash was similar in the two groups but multidermatomal rash occurred only in HIV-infected patients (4/24). There was no difference in the occurrence of ocular complications of HZO between HIV-positive and HIV-negative patients. HZO associated ocular complications and visual loss is low in HIV-infected patients if treated with HZO antiviral therapy and was comparable with HIV-negative patients. Early institution of HZO antiviral therapy is recommended to reduce ocular complication and vision loss.