Macular Microcysts in Mitochondrial Optic Neuropathies: Prevalence and Retinal Layer Thickness Measurements

Purpose

To investigate the thickness of the retinal layers and to assess the prevalence of macular microcysts (MM) in the inner nuclear layer (INL) of patients with mitochondrial optic neuropathies (MON).

Methods

All patients with molecularly confirmed MON, i.e. Leber’s Hereditary Optic Neuropathy (LHON) and Dominant Optic Atrophy (DOA), referred between 2010 and 2012 were enrolled. Eight patients with MM were compared with two control groups: MON patients without MM matched by age, peripapillary retinal nerve fiber layer (RNFL) thickness, and visual acuity, as well as age-matched controls. Retinal segmentation was performed using specific Optical coherence tomography (OCT) software (Carl Zeiss Meditec). Macular segmentation thickness values of the three groups were compared by one-way analysis of variance with Bonferroni post hoc corrections.

Results

MM were identified in 5/90 (5.6%) patients with LHON and 3/58 (5.2%) with DOA. The INL was thicker in patients with MON compared to controls regardless of the presence of MM [133.1±7μm vs 122.3±9μm in MM patients (p<0.01) and 128.5±8μm vs. 122.3±9μm in no-MM patients (p<0.05)], however the outer nuclear layer (ONL) was thicker in patients with MM (101.4±1mμ) compared to patients without MM [77.5±8mμ (p<0.001)] and controls [78.4±7mμ (p<0.001)]. ONL thickness did not significantly differ between patients without MM and controls.

Conclusion

The prevalence of MM in MON is low (5-6%), but associated with ONL thickening. We speculate that in MON patients with MM, vitreo-retinal traction contributes to the thickening of ONL as well as to the production of cystic spaces.     

Synthesis and characterization of tritylthioethanamine derivatives with potent KSP inhibitory activity

Assembly of a bipolar mitotic spindle requires the action of class 5 kinesins, and inhibition or depletion of this motor results in mitotic arrest and apoptosis. S-Trityl-l-cysteine is an allosteric inhibitor of vertebrate Kinesin Spindle Protein (KSP) that has generated considerable interest due to its anti-cancer properties, however, poor pharmacological properties have limited the use of this compound. We have modified the triphenylmethyl and cysteine groups, guided by biochemical and cell-based assays, to yield new cysteinol and cysteamine derivatives with increased inhibitory activity, greater efficacy in model systems, and significantly enhanced potency against the NCI60 tumor panel. These results reveal a promising new class of conformationally-flexible small molecules as allosteric KSP inhibitors for use as research tools, with activities that provide impetus for further development as anti-tumor agents.     

Fatal outcome of pandemic H1N1 2009 influenza virus infection is associated with immunopathology and impaired lung repair, not enhanced viral burden, in pregnant mice

Pandemic A (H1N1) 2009 influenza virus (pH1N1) infection in pregnant women can be severe. The mechanisms that affect infection outcome in this population are not well understood. To address this, pregnant and nonpregnant BALB/c mice were inoculated with the wild-type pH1N1 strain A/California/04/09. To determine whether innate immune responses are associated with severe infection, we measured the innate cells trafficking into the lungs of pregnant versus nonpregnant animals. Increased infiltration of pulmonary neutrophils and macrophages strongly correlated with an elevated mortality in pregnant mice. In agreement with this, the product of nitric oxide (nitrite) and several cytokines associated with recruitment and/or function of these cells were increased in the lungs of pregnant animals. Surprisingly, increased mortality in pregnant mice was not associated with higher virus load because equivalent virus titers and immunohistochemical staining were observed in the nasal cavities or lungs of all mice. To determine whether exacerbated inflammatory responses and elevated cellularity resulted in lung injury, epithelial regeneration was measured. The lungs of pregnant mice exhibited reduced epithelial regeneration, suggesting impaired lung repair. Despite these immunologic alterations, pregnant animals demonstrated equivalent percentages of pulmonary influenza virus-specific CD8(+) T lymphocytes, although they displayed elevated levels of T-regulator lymphocytes (Tregs) in the lung. Also, pregnant mice mounted equal antibody titers in response to virus or immunization with a monovalent inactivated pH1N1 A/California/07/09 vaccine. Therefore, immunopathology likely caused by elevated cellular recruitment is an implicated mechanism of severe pH1N1 infection in pregnant mice.     

Modelled biophysical impacts of conservation agriculture on local climates

Including the parameterization of land management practices into Earth System Models has been shown to influence the simulation of regional climates, particularly for temperature extremes. However, recent model development has focused on implementing irrigation where other land management practices such as conservation agriculture (CA) has been limited due to the lack of global spatially explicit datasets describing where this form of management is practiced. Here, we implement a representation of CA into the Community Earth System Model and show that the quality of simulated surface energy fluxes improves when including more information on how agricultural land is managed. We also compare the climate response at the subgrid scale where CA is applied. We find that CA generally contributes to local cooling (~1°C) of hot temperature extremes in mid‐latitude regions where it is practiced, while over tropical locations CA contributes to local warming (~1°C) due to changes in evapotranspiration dominating the effects of enhanced surface albedo. In particular, changes in the partitioning of evapotranspiration between soil evaporation and transpiration are critical for the sign of the temperature change: a cooling occurs only when the soil moisture retention and associated enhanced transpiration is sufficient to offset the warming from reduced soil evaporation. Finally, we examine the climate change mitigation potential of CA by comparing a simulation with present‐day CA extent to a simulation where CA is expanded to all suitable crop areas. Here, our results indicate that while the local temperature response to CA is considerable cooling (>2°C), the grid‐scale changes in climate are counteractive due to negative atmospheric feedbacks. Overall, our results underline that CA has a nonnegligible impact on the local climate and that it should therefore be considered in future climate projections.     

A forward genetic screen identifies Dolk as a regulator of startle magnitude through the potassium channel subunit Kv1.1

The acoustic startle response is an evolutionarily conserved avoidance behavior. Disruptions in startle behavior, particularly startle magnitude, are a hallmark of several human neurological disorders. While the neural circuitry underlying startle behavior has been studied extensively, the repertoire of genes and genetic pathways that regulate this locomotor behavior has not been explored using an unbiased genetic approach. To identify such genes, we took advantage of the stereotypic startle behavior in zebrafish larvae and performed a forward genetic screen coupled with whole genome analysis. We uncovered mutations in eight genes critical for startle behavior, including two genes encoding proteins associated with human neurological disorders, Dolichol kinase (Dolk), a broadly expressed regulator of the glycoprotein biosynthesis pathway, and the potassium Shaker-like channel subunit Kv1.1. We demonstrate that Kv1.1 and Dolk play critical roles in the spinal cord to regulate movement magnitude during the startle response and spontaneous swim movements. Moreover, we show that Kv1.1 protein is mislocalized in dolk mutants, suggesting they act in a common genetic pathway. Combined, our results identify a diverse set of eight genes, all associated with human disorders, that regulate zebrafish startle behavior and reveal a previously unappreciated role for Dolk and Kv1.1 in regulating movement magnitude via a common genetic pathway.     

Invertebrates in field margins: taxonomic group diversity and functional group abundance in relation to age

Sown, temporary field margins are a common agri-environment scheme (AES) in the Netherlands. Despite their wide application, though, there has been scarcely any long-term monitoring of the succession of invertebrates. In the field margins of 40 farms, invertebrate diversity and the abundance of three functional groups were assessed in relation to age. The diversity in terms of number of species groups was found to increase with the age of the margins. The abundance of herbivores and detritivores also showed a positive correlation with the age of the margins. However, the abundance of predators decreased with increasing age. Older margins showed a higher total vegetation cover and fewer plant species, also resulting in lower plant species evenness. We suggest several changes to the current AES regulations. For the conservation of invertebrate diversity, longer-lasting field margins are desirable. In addition, old margins are favoured by detritivores, a group that has particular difficulty finding suitable habitats in agricultural landscapes. However, such margins are less favourable from an agricultural perspective, as they appear unsuitable for high abundances of potentially useful predators and the high vegetation cover attracts many potentially harmful herbivores. To circumvent this, the AES might be extended by incorporating hay-making, which would reduce standing biomass and might lead to more predators and fewer herbivores.     

Ultraviolet radiation triggers apoptosis of fibroblasts and skin keratinocytes mainly via the BH3-only protein Noxa

To identify the mechanisms of ultraviolet radiation (UVR)-induced cell death, for which the tumor suppressor p53 is essential, we have analyzed mouse embryonic fibroblasts (MEFs) and keratinocytes in mouse skin that have specific apoptotic pathways blocked genetically. Blocking the death receptor pathway provided no protection to MEFs, whereas UVR-induced apoptosis was potently inhibited by Bcl-2 overexpression, implicating the mitochondrial pathway. Indeed, Bcl-2 overexpression boosted cell survival more than p53 loss, revealing a p53-independent pathway controlled by the Bcl-2 family. Analysis of primary MEFs lacking individual members of its BH3-only subfamily identified major initiating roles for the p53 targets Noxa and Puma. In the transformed derivatives, where Puma, unexpectedly, was not induced by UVR, Noxa had the dominant role and Bim a minor role. Furthermore, loss of Noxa suppressed the formation of apoptotic keratinocytes in the skin of UV-irradiated mice. Collectively, these results demonstrate that UVR activates the Bcl-2-regulated apoptotic pathway predominantly through activation of Noxa and, depending on cellular context, Puma.     

Changes in GAD67 mRNA expression evidenced by in situ hybridization in the brain of R6/2 transgenic mice

Huntington's disease is an autosomal dominant disorder with degeneration of medium size striatal neurones. As the disease evolves, other neuronal populations are also progressively affected. A transgenic mouse model of the disease (R6/2) that expresses exon 1 of the human Huntington gene with approximately 150 CAG repeats has been developed, but GABA concentrations are reported to be normal in the striatum of these animals. In the present study, we analysed the status of GABAergic systems by means of glutamic acid decarboxylase (GAD)67 mRNA in situ hybridization in the brain of R6/2 transgenic mice and wild-type littermates. We show that GAD67 expression is normal in the striatum, cerebellum and septum but decreased in the frontal cortex, parietal cortex, globus pallidus, entopeduncular nucleus and substantia nigra pars reticulata of R6/2 mice. These data, which may, in part, account for the behavioural changes seen in these animals, indicate that at 12.5 weeks of age the pathological features seen in the mice differ from those seen in humans with Huntington's disease.