Evaluating a polymicrobial biofilm model for structural components by co-culturing Komagataeibacter hansenii produced bacterial cellulose with Pseudomonas aeruginosa PAO1

A polymicrobial biofilm model of Komagataeibacter hansenii and Pseudomonas aeruginosa was developed to understand whether a pre-existing matrix affects the ability of another species to build a biofilm. P. aeruginosa was inoculated onto the preformed K. hansenii biofilm consisting of a cellulose matrix. P. aeruginosa PAO1 colonized and infiltrated the K. hansenii bacterial cellulose biofilm (BC), as indicated by the presence of cells at 19 μm depth in the translucent hydrogel matrix. Bacterial cell density increased along the imaged depth of the biofilm (17-19 μm). On day 5, the average bacterial count across sections was 67 ± 4 % P. aeruginosa PAO1 and 33 ± 6 % K. hansenii. Biophysical characterization of the biofilm indicated that colonization by P. aeruginosa modified the biophysical properties of the BC matrix, which inlcuded increased density, heterogeneity, degradation temperature and thermal stability, and reduced crystallinity, swelling ability and moisture content. This further indicates colonization of the biofilm by P. aeruginosa. While eDNA fibres - a key viscoelastic component of P. aeruginosa biofilm - were present on the surface of the co-cultured biofilm on day 1, their abundance decreased over time, and by day 5, no eDNA was observed, either on the surface or within the matrix. P. aeruginosa-colonized biofilm devoid of eDNA retained its mechanical properties. The observations demonstrate that a pre-existing biofilm scaffold of K. hansenii inhibits P. aeruginosa PAO1 eDNA production and suggest that eDNA production is a response by P. aeruginosa to the viscoelastic properties of its environment.

Structure-function characterization of the transition zone in the intervertebral disc

Understanding the structure-function relationship in the intervertebral disk (IVD) is crucial for the development of novel tissue engineering strategies to regenerate IVD and the establishment of accurate computational models for low back pain research. A large number of studies have improved our knowledge of the mechanical and structural properties of the nucleus pulposus (NP) and annulus fibrosus (AF), two of the main regions in the IVD. However, few studies have focused on the AF-NP interface (transition zone; TZ). Therefore, the current study aims to, for the first time, characterize the cyclic and failure mechanical properties of the TZ region under physiological loading (1, 3, and 5%s^-1 strain rates) and investigate the structural integration mechanisms between the NP, TZ, and AF regions. The results of the current study reveal significant effects of region (NP, TZ, and AF) and strain rates (1, 3, and 5%s^-1) on stiffness (p < 0.001). In addition, energy absorption is significantly higher for the AF compared to the TZ and NP (p <0.001) as well as between the TZ and NP (p <0.001). The current research finds adaptation, direct penetration, and entanglement between TZ and AF fibers as three common mechanisms for structural integration between the TZ and AF regions. STATEMENT OF SIGNIFICANCE: Despite a large number of studies that have mechanically, structurally, and biologically characterized the nucleus pulposus (NP) and annulus fibrosus (AF) regions, few studies have focused on the NP-AF interface region (known as Transition Zone; TZ) in the IVD; hence, our understanding of the TZ structure-function relationship is still incomplete. Of particular importance, the cyclic mechanical properties of the TZ, compared to the adjacent regions (NP and AF), are yet to be explored and the precise nature of the structural integration between the NP and AF via the TZ region is not yet known. The current study explores both the mechanical and structural properties of the TZ region to ultimately identify the mechanism of integration between the NP and AF.

Assessment of personality functioning in psychosomatic medicine

Background

Personality functioning, also referred to as structural integration, describes basic emotion-related perception and regulation capacities directed towards the self and others. Patients with impairments of personality functioning experience difficulties in self-regulation and interpersonal relations. Although personality functioning has become increasingly important in psychotherapeutic and psychiatric diagnoses and treatment planning, there is little systematic evidence on the role of personality functioning in patients with chronic and somatic diseases. This article reviews empirical studies using standardized assessments of personality functioning in patients with chronic and somatic diseases and discusses the role of personality structure in psychosomatic medicine.

Results

Currently, there are only a limited number of studies using standardized assessments of personality functioning in patients with chronic or somatic diseases. The available evidence points to correlations of personality functioning with pain perception and the development of chronic pain. In addition, patients with lower levels of personality functioning may have difficulties in managing chronic conditions that require enduring changes in health behavior, such as in diabetes or posttransplantation therapy.

Conclusion

The review suggests a systematic link between personality functioning and health behavior in patients with chronic diseases that relate to self-regulation and coping strategies. These findings underline the importance of assessing personality functioning for diagnostics and treatment planning in psychosomatic medicine. Finally, an assessment of personality functioning could be helpful in choosing specific psychotherapeutic treatment strategies; however, more empirical studies are needed to comprehensively prove these assumptions.

Personality functioning as a mediator of adult mental health following child maltreatment

BACKGROUND

The broad range of adverse health outcomes following child maltreatment (child maltreatment) underscores the need to investigate shared trajectories that contribute to associated physical and mental health problems. Previous research focused on different mechanisms, such as emotion regulation or attachment. In the present study, we propose personality functioning, comprising self- and interpersonal regulation and perception, to mediate between child maltreatment and mental and physical health.

METHODS

In a German representative sample (N = 2,508), we assessed remembered child maltreatment, levels of personality functioning, and different health outcomes in adulthood, namely somatic symptoms, general mental distress, and body dysmorphic concern. We conducted path analyses to investigate mediation effects in the total sample as well as in female and male subsamples.

RESULTS

Child maltreatment significantly predicted the assessed health outcomes and showed significant associations with lower levels of personality functioning. Personality functioning partially mediated all health outcomes assessed by significant indirect effects and lowered direct effects of child maltreatment on health outcomes. An exploratory analysis of different facets of personality functioning revealed a pronounced impact of identity perception and self-reflective capacities in mediating between child maltreatment and physical and mental health. Comparable results were found in female and male participants.

LIMITATIONS

Major limitations of the study are the reliance on cross-sectional data and the use of a screening measure to assess experienced child maltreatment.

CONCLUSION

Personality functioning may represent a transdiagnostic link to different somatic and psychological symptoms in the aftermath of child maltreatment.