Search

Background: Retinoblastoma is a rare intraocular malignancy in children. Current treatments have many adverse effects. New therapeutic approaches like intravitreal injections of chemotherapies are currently being developed but their toxicities need to be evaluated on animal models. This study compares the efficacy and toxicity of intravitreal melphalan, topotecan and carboplatin, alone or in combination (sequential administration), in the LHBetaTag retinoblastoma mice. Methods: Mice were divided into nine groups: control, carboplatin 1.5 and 4 μg, melphalan 0.1 and 1 μg, topotecan 0.1 and 1 μg, carboplatin 4 μg/topotecan 0.1 μg and melphalan 1 μg/topotecan 0.1 μg. The follow‐up was performed using fundus imaging and optical coherence tomography combined with histopathological analysis. Absence of tumour and presence of calcified tumours were the criteria for therapeutic response assessment. Ocular complications were assessed after four weekly injections. Retinal toxicity was defined by the decrease of retinal thickness and of the number of retinal layers. Results: Topotecan was inactive on retinal tumours. Melphalan (1 μg) led to a complete tumour control in 91.7% of eyes. Carboplatin strongly decreased the tumour burden (85.7‐93.8% of eyes without retinal tumour). The intravitreal injection itself led to ocular complications (25% of media opacities and 45.7% of retinal detachment). Only melphalan at 1 μg showed a strong retinal toxicity. The two combinations showed a good efficacy in reducing the number of eyes with retinal tumours with a reduced retinal toxicity. Conclusions: This preclinical study suggests that intravitreal injection of carboplatin has a low toxicity and could be evaluated in clinical practice to treat patients suffering from retinoblastoma. [ABSTRACT FROM AUTHOR]

This study reports on an investigation of the predictive validity of the TOEFL iBT® test in an English‐medium institution (EMI) in a non‐target‐language context, namely, Turkey. The relationship between TOEFL iBT scores and academic performance was explored in a cohort of 286 undergraduate students, as was the TOEFL iBT's relationship with an institutional English proficiency exam (Certificate of Proficiency in English [COPE]) used as a benchmark for faculty entry. Performance measures included scores on TOEFL iBT and COPE, grade point averages (GPAs) for content and English for academic purposes (EAP) courses over 2 freshman semesters, and freshman language instructor evaluations of students' freshman EAP performance. Correlations between test scores confirmed a moderate to moderately high predictive validity for content course GPAs and English‐language course GPAs, respectively, and for the TOEFL iBT, particularly in technical fields. Instructor evaluations of student performance supported the findings, with fewer deficiencies in academic English skills for students with higher scores on TOEFL iBT. The study concludes that the TOEFL iBT's predictive validity is on par with the institution's own proficiency test and represents a solid performance measure for use in EMIs in a non‐target‐language context. Report Number: ETS RR–18‐43 [ABSTRACT FROM AUTHOR]

In Arabidopsis thaliana, auxin is a key regulator of tissue patterning in the developing embryo. We have identified a group of proteins that act downstream of auxin accumulation in auxin-mediated root and vascular development in the embryo. Combined mutations in OBERON1 ( OBE1) and OBERON2 ( OBE2) give rise to obe1 obe2 double mutant seedlings that closely phenocopy the monopteros ( mp) mutant phenotype, with an absence of roots and defective development of the vasculature. We show that, in contrast to the situation in mp mutants, obe1 obe2 double mutant embryos show auxin maxima at the root pole and in the provascular region, and that the SCFTIR1 pathway, which translates auxin accumulation into transcriptional activation of auxin-responsive genes, remains intact. Although we focus on the impact of obe mutations on aspects of embryo development, the effect of such mutations on a broad range of auxin-related gene expression and the tissue expression patterns of OBE genes in seedlings suggest that OBE proteins have a wider role to play in growth and development. We suggest that OBE1 and OBE2 most likely control the transcription of genes required for auxin responses through the action of their PHD finger domains. [ABSTRACT FROM AUTHOR]

A 54-year-old woman presented for cardiac evaluation of atypical chest pain. Workup included coronary angiography and a left ventriculogram, during which air was inadvertently injected, resulting in the development of an acute right hemisphere syndrome. Right carotid angiography was immediately performed, yielding only a delayed diffuse venous phase without focal vessel cutoffs. Within 60 minutes, the patient underwent hyperbaric oxygen therapy for the suspected cerebral air emboli. After removal from the chamber for technical reasons, she had a generalized tonic-clonic seizure, and further hyperbaric oxygen therapy was with-held. Initial computed tomography imaging obtained approximately 8 hours after symptom onset showed signs of early right hemispheric edema. Subsequent magnetic resonance imaging studies were markedly abnormal and suggestive of diffuse bilateral but predominantly right-sided parietal lobe edema with mildly positive diffusion-weighted imaging. Follow-up magnetic resonance imaging at 6 months was normal, and the patient's neurological examination returned to normal. [ABSTRACT FROM AUTHOR]

From the characterization of the recessive resistance gene,sbm1, in pea we have identified the eukaryotic translation initiation factor, eIF4E, as a susceptibility factor required for infection with thePotyvirus,Pea seed-borne mosaic virus. A functional analysis of the mode of action of the product of the dominant allele revealed a novel function for eIF4E in its support for virus movement from cell-to-cell, in addition to its probable support for viral RNA translation, and hence replication. Different resistance specificities in two independent pea lines were explained by different mutations ineIF4E. On the modelled structure of eIF4E the coding changes were in both cases lying in and around the structural pocket involved in binding the 5′-m7G cap of eukaryotic mRNAs. Protein expression and cap-binding analysis showed that eIF4E encoded by a resistant plant could not bind to m7G-Sepharose, a result which may point to functional redundancy between eIF4E and the paralogous eIF(iso)4E in resistant peas. These observations, together with related findings for other potyvirus recessive resistances, provide a more complete picture of the potyvirus life cycle. [ABSTRACT FROM AUTHOR]

Summary Using a recombinant potato virus X (PVX) vector, we investigated the relationship between the length of RNA sequence identity with a transgene and the ability to promote post-transcriptional gene silencing (PTGS) and transgene methylation. The lower size limit required for targeting reporter transgene mRNA de novo using PTGS was 23 nucleotides (nt) of complete identity, a size corresponding to that of small RNAs associated with PTGS in plants and RNA interference (RNAi) in animals. The size and sequence specificity were also explored for PTGS-associated transgene methylation and for the targeting of the vector RNA. The PTGS-competent short sequences resulted in similar patterns of methylation. In all cases, including specific sequences of 33 nt with or without symmetrical cytosine residues, the methylation was distributed throughout the transcribed region of the transgene. In contrast, short sequences lacking symmetrical cytosines were less efficient at promoting PTGS of the transgene mRNA. Short gfp sequences in the PVX vector provided as effective a target for the degradation of viral RNA as was found for PVX carrying the complete gfp cDNA. Short sequences were able to initiate PTGS of an endogenous gene, phyotene desaturase, although this occurred in the absence of DNA methylation. This experimental approach provides important insights into the relationship between short RNA sequences and PTGS. [ABSTRACT FROM AUTHOR]

Pea embryonic tissues respond to active replication of pea seed-borne mosaic potyvirus (PSbMV) by the down-regulation of a range of genes and the induction of others. Both of these responses can be seen when tissues are subjected to abiotic stress, particularly heat. We have compared the effects of the two inducers to assess whether the host alterations following virus replication represent generic responses to stress, or more specific effects. Five classes of response were identified: (i) genes induced by both stresses (e.g. heat shock protein 70, hsp70); (ii) genes induced by virus replication but unaffected by heat (e.g. glutathione reductase 2, gor2); (iii) genes induced by heat but unaffected by virus replication (e.g. heat shock factor, hsf); (iv) genes down-regulated by virus replication and unaffected by heat (e.g. vicilin, vic); and (v) genes unaffected by both inducers (e.g. actin, act and β-tubulin, tub). A change in the appearance and organization of the endoplasmic reticulum (ER) was also seen in cells actively replicating PSbMV RNA. Heat treatment of pea embryonic tissues also produced altered ER, although the changes were different from those seen following virus infection. Collectively, these data show that, while there are some common features of the responses to virus infection and heat, there are also substantial differences. Hence, it appears that the host response to virus replication is not a general stress response. [ABSTRACT FROM AUTHOR]

Summary Since some heat-inducible genes [heat shock (hs ) genes] can be induced by virus infection in pea [e.g. Hsp70; Aranda et al . 1996, Proc. Natl Acad. Sci. USA 93, 15289–15293], we have investigated the effect that heat and virus replication may have on the expression of a heat-shock transcription factor gene (Hsf ). We have characterized what appears to be the only member of the Hsf family in pea, PsHsfA . Similar to Hsp70 , PsHsfA is heat-inducible in vegetative and embryonic tissues, which is concordant with the presence of heat shock elements (HSEs) and stress responsive elements (STREs) on its promoter sequence. The expression of PsHsfA during virus replication was studied in pea cotyledons and leaves, and compared to that of Hsp70 . In situ hybridization experiments showed that whereas Hsp70 is induced, there is no detectable increased accumulation of PsHsfA RNA associated with the replication of pea seed-borne mosaic potyvirus (PSbMV). These experiments indicate that there is a selective control of virus-induced hs gene expression, and suggest that different regulatory pathways control hs gene expression during heat shock and virus replication. [ABSTRACT FROM AUTHOR]

The relationship between co-suppression and DNA methylation was explored in transgenic plants showing inducible co-suppression following infection with a cytoplasmically replicating RNA virus. Induction resulted in a loss of transgene mRNA and resistance to further infection, factors typical of post-transcriptional gene silencing. In infected plants, de novo methylation of the transgene appeared to precede the onset of resistance and only occurred in plants where the outcome was co-suppression. The methylation was limited to sequences homologous to the viral RNA and occurred at both symmetric and non-symmetric sites on the DNA. Although methylation is predicted to occur in mitotic cells, the virus was found not to access the meristem. A diffusible sequence-specific signal may account for the epigenetic changes in those tissues. [ABSTRACT FROM AUTHOR]

Temporal variations in a streambed temperature profile between 30 and 300 cm beneath Tijeras Arroyo, New Mexico, were analyzed at 30-min intervals for 1990 to estimate the depth, duration, and rate of percolation during streamflows. The depth of percolation was clearly documented by the rapid response of the streambed temperature profile to streamflows. Results indicate that the streambed possessed small thermal gradients with significant diurnal variations from late November to late May, indicating that ephemeral streamflows created continuous, advection-dominated heat transport to depths below 300 cm during this period. Timing and duration of percolation suggested by temporal variations in the temperature profile were verified by comparison with measured streamflow records for the study reach over 1990. Percolation rates were estimated using a technique based on the travel time of the daily maximum temperature into the streambed. Percolation rates were compared with streambed seepage rates determined from measurements of streamflow loss, stream surface area, and stream evaporative loss for the entire study reach. Travel time estimates of streambed percolation rates ranged from 9 to 40 cm/hr, while streamflow estimates of streambed seepage rates ranged from 6 to 26 cm/hr during the study period. Discrepancies between streambed percolation and seepage rates may be caused by differences in the areal extent of measurements for percolation versus seepages rates. In summary, the depth, timing, and duration of streamflow-induced percolation were well documented by temporal variations in a single streambed temperature profile, while rates of percolation based on the temperature profile were about double the seepage rates based on streamflow records for the entire study reach. [ABSTRACT FROM AUTHOR]

We demonstrate that for losing reaches with significant diurnal variations in stream temperature, the effect of stream temperature on streambed seepage is a major factor contributing to reduced afternoon streamflows. An explanation is based on the effect of stream temperature on the hydraulic conductivity of the streambed, which can be expected to double in the 0° to 25°C temperature range. Results are presented for field experiments in which stream discharge and temperature were continuously measured for several days over losing reaches at St. Kevin Gulch, Colorado, and Tijeras Arroyo, New Mexico. At St. Kevin Gulch in July 1991, the diurnal stream temperature in the 160-m study reach ranged from about 4° to 18°C, discharges ranged from 10 to 18 L/s, and streamflow loss in the study reach ranged from 2.7 to 3.7 L/s. On the basis of measured stream temperature variations, the predicted change in conductivity was about 38%; the measured change in stream loss was about 26%, suggesting that streambed temperature varied less than the stream temperature. At Tijeras Arroyo in May 1992, diurnal stream temperature in the 655-m study reach ranged from about 10° to 25°C and discharge ranged from 25 to 55 L/s. Streamflow loss was converted to infiltration rates by factoring in the changing stream reach surface area and streamflow losses due to evaporation rates as measured in a hemispherical evaporation chamber. Infiltration rates ranged from about 0.7 to 2.0 m/d, depending on time and location. Based on measured stream temperature variations, the predicted change in conductivity was 29%; the measured change in infiltration was also about 27%. This suggests that high infiltration rates cause rapid convection of heat to the streambed. Evapotranspiration losses were estimated for the reach and adjacent flood plain within the arroyo. On the basis of these estimates, only about 5% of flow loss was consumed via stream evaporation and stream-side evapotranspiration, indicating that 95% of the loss within the study reach represented groundwater recharge. [ABSTRACT FROM AUTHOR]

Purpose: Choroidal melanoma is the most frequent malignant intraocular tumor. Radiotherapy using various modalities is the standard conservative treatment for confined lesions. It allows globe preservation in most cases, but 50% to 60% of irradiated eyes develop radiation retinopathy, secondary to multiple retinal vascular occlusions, leading in the most severe cases to neovascular glaucoma and secondary enucleation. The purpose of this experimental study was to create and test a new model of radiation retinopathy in the rat retina, and to explore potential pathways involved in the early pathogenesis of radiation retinopathy. Methods: We used the Small Animal Radiation Research Platform (SARRP, Xstrahl, UK) to build a dose‐response model of retinal irradiation. Long‐Evans rats were irradiated with an X‐ray source, after exorbiting the eye. Only one eye was irradiated for ethical reasons. There were 4 groups of 4 animals according to the radiation dose received. Group 1 received one 15‐Gray fraction of, Group 2 received two 15‐Gray fractions, Group 3 received three 15‐Gray fractions, and Group 4, the control group, received one sham irradiation fraction. Multimodal imaging with OCT, color fundus photograph, and fluoresceine angiography (Micron 4, Phoenix Researchlabs, USA) was performed at baseline and seven days after irradiation. Animals were sacrificed 8 days after irradiation. Eyes were either fixated for inclusion and sections, fixated for flat‐mounts of retina/RPE, or milled for Western Blot analysis. Results: Irradiating of rat retinas using SARRP was successful. At day 7, there were no specific features on angiography, but OCT revealed inconsistent features in the peripheral retina of one animal (Group 3 fractions). In two animals, exorbitation was not possible due to variations of periocular morphology (Groups 2 and 3 fractions). Both animals developed corneal opacifications attributed to lacrymal gland damage. Conclusions: SARRP is a simple and efficient tool to model radiation retinopathy in small animals. Further work is required to improve our understanding of this potentially blinding complication of ocular irradiation References Ramos MS, Echegaray JJ, Kuhn‐Asif S, Wilkinson A, Yuan A, Singh AD, Browne AW.Animal models of radiation retinopathy ‐ From teletherapy to brachytherapy.Exp Eye Res. 2019 Apr;181:240‐251. Rothschild PR, Salah S, Berdugo M, Gélizé E, Delaunay K, Naud MC, Klein C, Moulin A, Savoldelli M, Bergin C, Jeanny JC, Jonet L, Arsenijevic Y, Behar‐Cohen F, Crisanti P. ROCK‐1 mediates diabetes‐induced retinal pigment epithelial and endothelial cell blebbing: Contribution to diabetic retinopathy. Sci Rep. 2017 Aug 18;7(1):8834. Rousseau M, Gaugler M‐H, Rodallec A, Bonnaud S, Paris F, Corre I. RhoA GTPase regulates radiation‐induced alterations in endothelial cell adhesion and migration. Biochem Biophys Res Commun. 2011;414(4):750‐755. [ABSTRACT FROM AUTHOR]

Bovine viral diarrhoea virus (BVDV) is an economically important animal pathogen which is closely related to Hepatitis C virus. Of the structural proteins, the envelope glycoprotein E2 of BVDV is the major antigen which induces neutralizing antibodies; thus, BVDV E2 is considered as an ideal target for use in subunit vaccines. Here, the expression, purification of wild-type and mutant forms of the ectodomain of BVDV E2 and subsequent crystallization and data collection of two crystal forms grown at low and neutral pH are reported. Native and multiple-wavelength anomalous dispersion (MAD) data sets have been collected and structure determination is in progress.