Investigation of Salivary Cortisol Response to Awakening in Underweight and Weight-Restored Patients with Anorexia Nervosa

Introduction

Anorexia nervosa (AN) is characterized by dysregulated eating that leads to chronic malnutrition, which may be responsible for several physical complications, including endocrine alterations, such as hyperactivity of the hypothalamus-pituitary-adrenal (HPA) axis.

Objectives

Several studies have shown a dysregulation of the cortisol awakening response (CAR) in symptomatic AN patients. However, it has not been established if the deranged CAR of underweight AN patients is a primary phenomenon or an alteration secondary to malnutrition.

Aims

The aim of this study was to explore the salivary CAR in both underweight and weight-restored patients with AN.

Methods

We recruited 59 women: 18 undernourished AN patients, 15 weight-restored AN women and 26 normal-weight healthy controls. Saliva samples were collected in the morning, immediately after awakening and after 15, 30 and 60 minutes, in order to measure saliva levels of cortisol. Participants filled in the state-trait anxiety inventory (STAI) to test their anxiety levels in the morning of the test.

Results

Compared to healthy controls, underweight AN patients showed an enhanced CAR whereas the weight recovered patients had a normal CAR. These results were not correlated with levels of anxiety.

Conclusions

For the first time, our results demonstrate that the deranged CAR found in acute AN patients is not present in weight-restored ones, suggesting that altered activity of the HPA axis of symptomatic AN patients is a state-dependent phenomenon.

Disclosure of interest

The authors have not supplied their declaration of competing interest.

Alexithymia and cortisol awakening response in people with eating disorders

Introduction

Alexithymia, that is the inability to recognize and describe one’s own emotions, is a transdiagnostic feature across eating disorders (EDs) and it has been associated to a prolonged stress exposure.

Objectives

Therefore, we evaluated whether alexithymia affects the hypothalamus-pituitary-adrenal (HPA) axis functioning in patients with anorexia nervosa (AN) or bulimia nervosa (BN).

Methods

Twenty-six women with AN and 26 with BN participated in the study. Alexithymia was evaluated by the Toronto Alexithymia Scale–20 and eating-related psychopathology was measured by the Eating Disorder Inventory-2. The activity of the HPA axis was assessed by the salivary cortisol awakening response (CAR). Group differences in saliva CAR were tested by repeated measures 3-way ANOVA with diagnosis and alexithymia as between-subject factors.

Results

The prevalence of alexithymia did not differ significantly between the two diagnostic groups (c²=1.24, p=0.26). Alexithymia was associated with more severe eating-related psychopathology in AN women but not in BN women. A significant reduction in the magnitude of CAR occurred in alexithymic patients with BN compared to non-alexithymic patients with BN (t = 3.39, p = 0.008), but not in alexithymic women with AN (t = 0.67, p = 0.54).

Conclusions

These results confirm the presence of a more severe eating-related psychopathology in alexithymic individuals with AN and show, for the first time, an association between alexithymia and a dampened basal activity of the HPA axis in BN.

Disclosure

No significant relationships.

A Light Scattering Investigation of Enzymatic Gelation in Self-Assembling Peptides

Self-assembling peptides (SAPs) have been increasingly studied as hydrogel-former gelators because they can create biocompatible environments. A common strategy to trigger gelation, is to use a pH variation, but most methods result in a change in pH that is too rapid, leading to gels with hardly reproducible properties. Here, we use the urea-urease reaction to tune gel properties, by a slow and uniform pH increase. We were able to produce very homogeneous and transparent gels at several SAP concentrations, ranging from c=1g/L to c=10g/L. In addition, by exploiting such a pH control strategy, and combining photon correlation imaging with dynamic light scattering measurements, we managed to unravel the mechanism by which gelation occurs in solutions of (LDLK)3-based SAPs. We found that, in diluted and concentrated solutions, gelation follows different pathways. This leads to gels with different microscopic dynamics and capability of trapping nanoparticles. At high concentrations, a strong gel is formed, made of relatively thick and rigid branches that firmly entrap nanoparticles. By contrast, the gel formed in dilute conditions is weaker, characterized by entanglements and crosslinks of very thin and flexible filaments. The gel is still able to entrap nanoparticles, but their motion is not completely arrested. These different gel morphologies can potentially be exploited for controlled multiple drug release.

Vulnerability to acute psychosocial stress in subjects with eating disorders and history of childhood trauma: experimental evidence of a “Maltreated Ecophenotype”

Introduction

Subjects with eating disorders (ED) show a high prevalence of childhood trauma.

Objectives

Aim of the study is to evaluate the emotional, biological and behavioral responses to an experimental acute psychosocial stress in subjects with ED with or without childhood maltreatment. Secondary aim is to evaluate the effects of different traumatic experiences (physical and emotional).

Methods

48 women with ED completed the Childhood Trauma Questionnaire (CTQ). 29 participants (14 with Anorexia Nervosa [AN] and 15 with Bulimia Nervosa [BN]) reported an history of childhood maltreatment, while 19 (11 with AN and 8 with BN) did not. Cortisol levels, anxiety and hunger perceptions have been assessed in all participants throughout the Trier Social Stress Test (TSST) as well as body dissatisfaction after stress exposure.

Results

Subjects with childhood trauma showed higher emotional reactivity and body dissatisfaction and lower hunger throughout the TSST than those without childhood trauma. Higher cortisol levels were observed in patients with AN, regardless of the presence of childhood trauma, and in those with BN and history of emotional trauma. Emotional trauma was the childhood trauma explaining most of the observed differences.

Conclusions

Childhood trauma, especially emotional one, can lead to vulnerability to interpersonal stress in individuals with ED. The present study is the first that supports the “maltreated ecophenotype” hypothesis in subjects with ED through an experimental task and the evaluation of multiple levels of response. These data may provide new prospectives on the pathogenetic mechanisms of ED and novel therapeutic implications.

Disclosure

No significant relationships.

Optothermal crystallization of hard spheres in an effective bidimensional geometry

Using colloids effectively confined in two dimensions by a cell with a thickness comparable to the particle size, we investigate the nucleation and growth of crystallites induced by locally heating the solvent with a near-infrared laser beam. The particles, which are "thermophilic," move towards the laser spot solely because of thermophoresis with no convection effects, forming dense clusters whose structure is monitored using two order parameters that gauge the local density and the orientational ordering. We find that ordering takes place when the cluster reaches an average surface density that is still below the upper equilibrium limit for the fluid phase of hard disks, meaning that we do not detect any sign of a proper "two-stage" nucleation from a glass or a polymorphic crystal structure. The crystal obtained at late growth stage displays a remarkable uniformity with a negligible amount of defects, arguably because the incoming particles diffuse, bounce, and displace other particles before settling at the crystal interface. This "fluidization" of the outer crystal edge may resemble the surface enhanced mobility giving rise to ultra-stable glasses by physical vapor deposition.

Microrheology of a thermosensitive gelling polymer for cell culture

We investigate the rheo-mechanical properties of Mebiol Gel®, a thermosensitive Gel-Forming Polymer extensively used as a medium for cellular culture, using passive microrheology made either by standard Dynamic Light Scattering(DLS) or by Photon Correlation Imaging (PCI). In the dilute limit, Mebiol displays a Newtonian behaviour with an effective viscosity that decreases with temperature, consistent with a peculiar aggregation mechanism characterized by anincrease of the molecular weight with a simultaneous reduction of the aggregate size. By increasing concentration and approaching gelation, both the storage and loss moduli shows a nonmonotonic dependence with temperature, with a pronounced maximum around Tm ≃28 −30{degree sign}C, the value above which, in the dilute limit, the individual Mebiol chains are fully compacted. Such a distinctive trend of the elastic and viscous properties persists within the gel, which therefore becomes "softer" above Tm. Although when temperature changes are performed adiabatically the transition from the fluid to the gel phase takes place without any apparent discontinuity, a rapid T -jump leads to the formation of a hard gel at a concentration where a low heating rate conversely yields a fluid phase. This is a visible manifestation of the nonequilibrium nature of these physical gels.

Cortisol, anxiety and cognitive responses to trier social stress test: The first multiple levels assessment of the rdoc “system for social process” in eating disorders

Introduction

Social dysfunction is a putative risk and maintaining factor for Eating Disorders (EDs).

Objectives

We aimed to assess biological, emotional, and cognitive responses to a psychosocial stressor, in order to provide a multilevel investigation of the RDoC social process system in EDs.

Methods

Cortisol response to Trier Social Stress Test (TSST) was measured in 105 subjects: 35 women with anorexia nervosa (AN), 32 with bulimia nervosa (BN) and 38 healthy women. In a subgroup of them (23 AN, 21 BN, and 25 control women) anxiety, hunger, and desire to eat throughout the TSST were also rated.

Results

Compared to healthy women, AN and BN women showed reduced cortisol reactivity that disappeared after controlling for trait anxiety and ineffectiveness. They also displayed increased anxiety response, while only people with AN reported greater decrease in hunger and desire to eat. Baseline ineffectiveness predicted post-stress body dissatisfaction through the mediation of post-stress anxiety while no significant correlations were found between cortisol and anxiety, hunger, or desire to eat responses

Conclusions

People with EDs are characterized by blunted cortisol reactivity and greater anxiety, hunger, and desire to eat responses to a psychosocial stressor. We show a relationship between socio-emotional distress and ED-related attitudes without an association between biological and emotional or cognitive changes. This study provides the first empirical and multilevel support to a deranged functioning of the RDoC “system for social process” in EDs.

Disclosure

No significant relationships.

Unraveling gelation kinetics, arrested dynamics and relaxation phenomena in filamentous colloids by photon correlation imaging

The fundamental understanding of the gelation kinetics, stress relaxation and temporal evolution in colloidal filamentous gels is central to many aspects of soft and biological matter, yet a complete description of the inherent complex dynamics of these systems is still missing. By means of photon correlation imaging (PCI), we studied the gelation of amyloid fibril solutions, chosen as a model filamentous colloid with immediate significance to biology and nanotechnology, upon passage of ions through a semi-permeable membrane. We observed a linear-in-time evolution of the gelation front and rich rearrangement dynamics of the gels, the magnitude and the spatial propagation of which depend on how effectively electrostatic interactions are screened by different ionic strengths. Our analysis confirms the pivotal role of salt concentration in tuning the properties of amyloid gels, and suggests potential routes for explaining the physical mechanisms behind the linear advance of the salt ions.

Thermal Lens Measurements of Thermal Expansivity in Thermosensitive Polymer Solutions

The weak absorption of a laser beam generates in a fluid an inhomogeneous refractive index profile acting as a negative lens. This self-effect on beam propagation, known as Thermal Lensing (TL), is extensively exploited in sensitive spectroscopic techniques, and in several all-optical methods for the assessment of thermo-optical properties of simple and complex fluids. Using the Lorentz-Lorenz equation, we show that the TL signal is directly proportional to the sample thermal expansivity α, a feature allowing minute density changes to be detected with high sensitivity in a tiny sample volume, using a simple optical scheme. We took advantage of this key result to investigate the compaction of PniPAM microgels occurring around their volume phase transition temperature, and the temperature-driven formation of poloxamer micelles. For both these different kinds of structural transitions, we observed a significant peak in the solute contribution to α, indicating a decrease in the overall solution density-rather counterintuitive evidence that can nevertheless be attributed to the dehydration of the polymer chains. Finally, we compare the novel method we propose with other techniques currently used to obtain specific volume changes.