Do We Feel the Same Empathy for Loved and Hated Peers?

Empathy allows us to understand and react to other people''s feelings and sensations; we can more accurately judge another person’s situation when we are aware of his/her emotions. Empathy for pain is a good working model of the behavioral and neural processes involved in empathy in general. Although the influence of perspective-taking processes (notably "Self" vs. "Other") on pain rating has been studied, the impact of the degree of familiarity with the person representing the “Other” perspective has not been previously addressed. In the present study, we asked participants to adopt four different perspectives: "Self", "Other-Most-Loved-Familiar", "Other-Most-Hated-Familiar" and "Other-Stranger". The results showed that higher pain ratings were attributed to the Other-Most-Loved-Familiar perspective than to the Self, Other-Stranger and Other-Most-Hated-Familiar perspectives. Moreover, participants were quicker to rate pain for the Other-Most-Loved-Familiar perspective and the Self-perspective than for the other two perspectives. These results for a perspective-taking task therefore more clearly define the role of familiarity in empathy for pain.     

Nanoscale topography of hepatitis B antigen particles by atomic force microscopy

Hepatitis B virus envelope is mainly composed of three forms of the same protein expressed from different start codons of the same open reading frame. The smaller form named S protein corresponds to the C-terminal common region and represents about 80% of the envelope proteins. It is mainly referred as hepatitis B virus surface antigen (HBsAg). Over expressed in the host cell, this protein can be produced as spherical and tubular self-organized particles. Highly immunogenic, these particles are used in licensed hepatitis B vaccines. In this study we have combined transmission electron microscopy and atomic force microscopy to determine the shape and size of HBsAg particles produced from the yeast Hansenula polymorpha. Tapping mode atomic force microscopy in liquid allows structural details of the surface to be delineated with a resolution in the nanometer range. Particles were decorated by closely packed spike-like structures protruding from particle surface. Protrusions appeared uniformly distributed at the surface and an average number of 75 protrusions per particle were calculated. Importantly, we demonstrated that proteins mainly contribute to the topography of the protrusions.     

Carotenoids modulate the trade-off between egg production and resistance to oxidative stress in zebra finches

The allocation of resources to reproduction and survival is a central question of studies of life history evolution. Usually, increased allocation to current reproduction is paid in terms of reduced future reproduction and/or decreased survival. However, the proximal mechanisms underlying the cost of reproduction are poorly understood. Recently, it has been shown that increased susceptibility to oxidative stress might be one of such proximate links between reproduction and self-maintenance. Organisms possess a range of antioxidant defenses, including endogenously produced molecules (e.g., enzymes) and compounds ingested with food (e.g., carotenoids). If reproductive effort increases the production of reactive oxygen species, the availability of antioxidant defenses may partly or fully counteract the free-radical damages. One could, therefore, expect that the trade-off between reproduction and oxidative stress is modulated by the availability of antioxidant defenses. We tested this hypothesis in zebra finches. We manipulated reproductive effort by either allowing or preventing pairs to breed. Within each breeding or non-breeding group, the availability of antioxidant compounds was manipulated by supplementing or not supplementing the drinking water with carotenoids. We found that although birds in the breeding and non-breeding groups did not differ in their resistance to oxidative stress (the breakdown of red blood cells submitted to a controlled free-radical attack), one aspect of breeding effort (i.e., the number of eggs laid by birds in both breeding and non-breeding groups) was negatively correlated with resistance to oxidative stress only in birds that did not benefit from a carotenoid-supplemented diet. This result therefore suggests that carotenoid availability can modulate the trade-off between reproduction and resistance to oxidative stress.     

Host sex and ectoparasites choice: preference for, and higher survival on female hosts

1. Sex differences in levels of parasite infection are a common rule in a wide range of mammals, with males usually more susceptible than females. Sex-specific exposure to parasites, e.g. mediated through distinct modes of social aggregation between and within genders, as well as negative relationships between androgen levels and immune defences are thought to play a major role in this pattern. 2. Reproductive female bats live in close association within clusters at maternity roosts, whereas nonbreeding females and males generally occupy solitary roosts. Bats represent therefore an ideal model to study the consequences of sex-specific social and spatial aggregation on parasites' infection strategies. 3. We first compared prevalence and parasite intensities in a host-parasite system comprising closely related species of ectoparasitic mites (Spinturnix spp.) and their hosts, five European bat species. We then compared the level of parasitism between juvenile males and females in mixed colonies of greater and lesser mouse-eared bats Myotis myotis and M. blythii. Prevalence was higher in adult females than in adult males stemming from colonial aggregations in all five studied species. Parasite intensity was significantly higher in females in three of the five species studied. No difference in prevalence and mite numbers was found between male and female juveniles in colonial roosts. 4. To assess whether observed sex-biased parasitism results from differences in host exposure only, or, alternatively, from an active, selected choice made by the parasite, we performed lab experiments on short-term preferences and long-term survival of parasites on male and female Myotis daubentoni. When confronted with adult males and females, parasites preferentially selected female hosts, whereas no choice differences were observed between adult females and subadult males. Finally, we found significantly higher parasite survival on adult females compared with adult males. 5. Our study shows that social and spatial aggregation favours sex-biased parasitism that could be a mere consequence of an active and adaptive parasite choice for the more profitable host.     

An experimental test of the dose-dependent effect of carotenoids and immune activation on sexual signals and antioxidant activity

Carotenoid-based sexual traits are thought to be reliable indicators of male quality because they might be scarce and therefore might indicate the ability of males to gather high-quality food and because they are involved in important physiological functions (as immune enhancers and antioxidants). We performed an experiment where male and female zebra finches (Taeniopygia guttata) were provided with increasing carotenoid doses in the drinking water during 4 weeks (bill color of this species is a carotenoid-based sexual signal). Simultaneously, birds were split into two groups: one receiving weekly injections of Escherichia coli lipopolysaccharide in order to activate the immune system, the other being injected with the same volume of phosphate buffered saline. We assessed how carotenoid availability and immune activation affected the amount of circulating plasma carotenoids, the beak color, and the antioxidant defenses (assessed as the resistance of red blood cells to a controlled free radical attack). Carotenoid availability affected the amount of circulating carotenoids and beak color; both variables reached a plateau at the highest carotenoid doses. Immune activation diverted carotenoids from plasma, and this in turn affected the expression of the sexual trait. Finally, we found a positive correlation between the change in circulating carotenoids and antioxidant defenses. These results support the idea that carotenoids have important physiological properties that ensure the honesty of carotenoid-based sexual traits.     

Diffusion Tensor Magnetic Resonance Imaging of Trigeminal Nerves in Relapsing Herpetic Keratouveitis

Background

Corneal hypoesthesia is the landmark of HSV and VZV keratitis and can lead to neurotrophic keratitis. Diffusion tensor imaging (DTI) is a new magnetic resonance imaging (MRI) derived technique, which offers possibilities to study axonal architecture. We aimed at assessing the potential impact of recurrent HSV or VZV-related keratitis on the axonal architecture of trigeminal nerves using DTI.

Design

Prospective non-interventional study.

Participants

Twelve patients and 24 controls.

Methods

DTI using MRI of the trigeminal fibers and corneal esthesiometry using the Cochet-Bonnet esthesiometer were acquired for patients affected by unilateral and recurrent HSV or VZV-related keratitis (3 months after the last corneal inflammatory event), and control subjects with no history of ocular or neuronal disease affecting the trigeminal pathways.

Main Outcome Measures

Fractional anisotropy (FA) and apparent diffusion coefficient (ADC) were compared between the 2 eyes of both patients and controls, and correlated with corneal esthesiometry.

Results

FA was lower in the trigeminal fibers ipsilateral to the affected eye compared to the non-affected side (0.39±0.02 versus 0.46±0.04, P=0.03). This difference was more important than the intra-individual variability observed in controls. Concomitantly, the asymmetry in ADC results was significantly correlated with the loss of corneal sensitivity in the affected eye.

Conclusions

Corneal hypoesthesia related to HSV and VZV keratitis is associated with persistent modifications in the architecture and functionality of the trigeminal fibers. These results add further explanation to the pathogenesis of HSV and VZV-induced neurotrophic keratitis, which may occur despite an apparent quiescence of the disease.     

Reciprocal connections between the red nucleus and the trigeminal nuclei: a retrograde and anterograde tracing study.

An anterograde biocytin and a retrograde WGA-colloidal gold study in the rat can provide information about reciprocal communication pathways between the red nucleus and the trigeminal sensory complex. No terminals were found within the trigeminal motor nucleus, in contrast with the facial motor nucleus. A dense terminal field was observed in the parvicellular reticular formation ventrally to the trigeminal motor nucleus. The parvicellular area may be important for the control of jaw movements by rubrotrigeminal inputs. On the other hand, the contralateral rostral parvicellular part of the red nucleus receives terminals from the same zone in the rostral part of the trigeminal sensory complex, where retrogradely labelled neurones were found after tracer injections into the red nucleus. Such relationships could be part of a control loop for somatosensory information from the orofacial area.     

Differentiation of a clone isolated from the HT29 cell line: polarized distribution of histocompatibility antigens (HLA) and of transferrin receptors

The HT29 cell line, derived from a human colon adenocarcinoma, is able to differentiate if galactose replaces glucose in the culture medium. We have isolated a clone (HT29-18) from this cell line which displays differentiated properties of the parent cell line. HT29-18 cells grown in glucose-containing medium form multiple layers of round cells without specific cell-cell adhesion. In contrast, when grown in galactose-containing medium, they form a monolayer with tight junctions and exhibit a well differentiated brush border at their apical membrane, which faces the culture medium. The polarized properties of HT29-18 cells grown in galactose-containing medium were demonstrated by immunofluorescent techniques with antibodies against 2 plasma membrane proteins. Class I histocompatibility antigens (HLA) and transferrin receptors, 2 well characterized integral membrane proteins, are uniformly distributed on the cell surface of undifferentiated HT29-18 cells, but acquire a polarized distribution during differentiation, localized on the basolateral membranes and absent from the apical surface. Binding of 125I-labeled transferrin was used to determine transferrin receptor distribution on apical and basolateral membranes. Functional tight junctions in the differentiated cultures were demonstrated, as the monolayer was impermeable to a permeation dye (ruthenium red) as well as to antibodies. The sealing of these tight junctions is, as in vivo, Ca++-dependent as they could be opened by a short incubation in Ca++-free medium.