Effects of ferroelectric oxides of barium strontium titanate (Ba0.85Sr0.15TiO3) nanoparticles on Ruditapes decussatus assessed through chemical, physiological, and biochemical methods.

Here, the effects of a newly designed ferroelectric oxide synthesized by solid reaction, barium strontium titanate [BST (85/15)] (Ba0.85Sr0.15TiO3), on the carpet shell clam Ruditapes decussatus were investigated. These clams were exposed to four concentrations of BST (85/15) nanoparticles (0.001, 0.01, 0.1, and 1 mg.L-1), and BST (85/15) was absorbed by R. decussatus in an exposure intensity-dependent manner. Measurements of clearance rate and biomarkers confirmed that the nanoparticles significantly affected the health of clams in an organ-dependent manner. Interestingly, BST (85/15) nanoparticles stimulated acetylcholinesterase (AChE) activity in the clams, suggesting their usefulness as antagonists of AChE inhibiting pollutants. These findings demonstrate the suitability of R. decussatus as a test organism to provide a framework for understanding the toxicological effects of these newly designed ferroelectrics. Moreover, concentrations of BST (85/15) < 0.1 mg.L-1 could be good alternatives to lead-based ferroelectric oxides and could be sustainable tools for use in electronic applications.

The influence of age in women in visuo-spatial memory in reaching and navigation tasks with and without landmarks.

Spatial memory and navigation capabilities tend to decline in normal aging, but few studies have assessed the impact of landmarks on route learning in a large-scale environment. The objectives were to examine age-related effects on visuo-spatial working memory capabilities in various environments and to determine the impact of landmarks in navigation skills in normal aging. 42 young women (23.6 ±â€¯4.9 years) and 37 older women (70.7 ±â€¯4.7 years) with no cognitive impairment have performed three visuo-spatial working memory tests: one in reaching space (computerized Corsi-Block-Tapping test) and two in locomotor navigation space (a condition without landmarks: Virtual Walking Corsi Test and a condition with landmarks: Virtual Room Walking Test). A two-way mixed ANOVA test showed that the young subjects performed better in all conditions than older subjects. The performance in visuo-spatial working memory thus decreases with age. Visuo-spatial working memory performances were identical in reaching and navigation spaces for both groups. The integration of landmarks into a navigational task decreases performance in older women, while this performance is not altered in younger women.

Does gravity play an essential role in the asymmetrical visual perception of vertical and horizontal line length?

The eye perceives the length of vertical and horizontal lines with an inherent asymmetry. A vertical line having the same length as a horizontal one is usually perceived to be longer. In this experimental investigation we tested the hypothesis that gravity has a direct role in producing the observed perceptual asymmetry. To this end we performed experiments in weightlessness during long-orbital space flights onboard the MIR station. Subjects performed a psychophysical task in which the length of a visually-presented vertical line was adjusted to match the length of a horizontal reference. On Earth, almost all subjects produce errors in adjusting the length of the vertical line, consistently under-estimating the length of the horizontal reference. The asymmetry of perception of the line lengths persisted in weightlessness. From these results we conclude that the phenomena of asymmetry of perception of the lengths of vertical and horizontal lines is not dependent on gravity, but is instead defined by properties of the system of internal representation. Grant numbers: 99-04-48450.

Internal reference frames for representation and storage of visual information: the role of gravity.

Experimental studies of visual mechanisms suggests that the CNS represents image information with respect to preferred horizontal and vertical axes, as shown by a phenomenon known as the "oblique effect". In the current study we used this effect to evaluate the influence of gravity on the representation and storage of visual orientation information. Subjects performed a psychophysical task in which a visually-presented stimulus line was aligned with the remembered orientation of a reference stimulus line presented moments before. The experiments were made on 5 cosmonauts during orbital space flight and additionally on 13 subjects in conditions of normal gravity with a tilting chair. Data were analyzed with respect to response variability and timing. On earth, these measurements for this task show a distinct preference for horizontally and vertically oriented stimuli when the body and gravitational axes were aligned. This preference was markedly decreased or disappeared when the body axis was tilted with respect to gravity; this effect was not connected with ocular counter-rolling nor could we find a preference of any other intermediate axis between the gravity and body aligned axes. On the other hand, the preference for vertical and horizontal axes was maintained for tests performed in microgravity over the course of a 6 month flight, starting from flight day 6. We concluded that subjects normally process visual orientation information in a multi-modal reference frame that combines both proprioceptive and gravitational cues when both are available, but that a proprioceptive reference frame is sufficient for this task in the absence of gravity after a short period of adaptation. Some of the results from this study have been previously published in a preliminary report. Grant numbers: 99-04-48450.

A 6 D.O.F. opto-inertial tracker for virtual reality experiments in microgravity.

Gravity plays a role in many different levels of human motor behavior. It dictates the laws of motion of our body and limbs, as well as of the objects in the external world with which we wish to interact. The dynamic interaction of our body with the world is molded within gravity's constraints. The role played by gravity in the perception of visual stimuli and the elaboration of human movement is an active research theme in the field of Neurophysiology. Conditions of microgravity, coupled with techniques from the world of virtual reality, provide a unique opportunity to address these questions concerning the function of the human sensorimotor system. The ability to measure movements of the head and to update in real time the visual scene presented to the subject based on these measurements is a key element in producing a realistic virtual environment. A variety of head-tracking hardware exists on the market today, but none seem particularly well suited to the constraints of working with a space station environment. Nor can any of the existing commercial systems meet the more stringent requirements for physiological experimentation (high accuracy, high resolution, low jitter, low lag) in a wireless configuration. To this end, we have developed and tested a hybrid opto-inertial 6 degree-of-freedom tracker based on existing inertial technology. To confirm that the inertial components and algorithms will function properly, this system was tested in the microgravity conditions of parabolic flight. Here we present the design goals of this tracker, the system configuration and the results of 0g and 1g testing.

[Interferon beta-1b retinopathy during a treatment for multiple sclerosis]. / Rétinopathie à l'interféron bêta au cours d'une sclérose en plaques.

Ocular adverse effects of interferon are described during the treatment of malignant diseases and chronic viral hepatitis with interferon alpha. At this time, there is no report of these effects during multiple sclerosis treatment with interferon beta-1b. The authors report a bilateral retinopathy during this treatment. The production of neutralizing antibodies during interferon beta-1b treatment leads to a decrease in diminution of therapeutic efficacy. When treatment failure occurs, neutralizing antibodies are to be tested.

[Birdshot chorioretinopathy associated with tamoxifen retinal toxicity]. / Un cas d'association de choriorétinopathie de type Birdshot et de toxicité rétinienne du tamoxifène.

We report a case of Birdshot retinochoroidopathy associated with ocular toxicity due to tamoxifen. Adverse drug effects were suspected due to the presence of yellow-white dots in the paramacular region and the fovea and by modifications of the retinal epithelial pigments. Ocular toxicity should be suspected as it may be reversible if recognized and stopped early. Other adverse ocular effects are described and the pathogenic mechanism of tamoxifen retinopathy analyzed.

[Central retinal vein occlusion in a patient treated with antiandrogenic drug]. / Occlusion de la veine centrale de la rétine sous anti-androgènes.

Central retinal vein occlusion (CRVO) is usually seen in older adults and is often associated with systemic vascular disease, this is much less evident in young people. A case report of a 28-year-old woman presented a central retinal vein occlusion in her left eye. This young woman was treated with antiandrogenic drug. Investigations revealed an abnormality of the hemostatic system. The central retinal vein occlusion was resolved and the fundus assumed a normal appearance one-month after the primary episode. Retinal vascular occlusions with antiandrogenic drug may be due to three mechanisms: increased platelet cell aggregation, alteration of fibrinolytic system and vascular endothelium hyperplasia.