Location of the axon initial segment assembly can be predicted from neuronal shape.

The axon initial segment (AIS) is located at the proximal axon demarcating the boundary between axonal and somatodendritic compartments. The AIS facilitates the generation of action potentials and maintenance of neuronal polarity. In this study, we show that the location of AIS assembly, as marked by Ankyrin G, corresponds to the nodal plane of the lowest-order harmonic of the Laplace-Beltrami operator solved over the neuronal shape. This correlation establishes a coupling between location of AIS assembly and neuronal cell morphology. We validate this correlation for neurons with atypical morphology and neurons containing multiple AnkG clusters on distinct neurites, where the nodal plane selects the appropriate axon showing enriched Tau. Based on our findings, we propose that Turing patterning systems are candidates for dynamically governing AIS location. Overall, this study highlights the importance of neuronal cell morphology in determining the precise localization of the AIS within the proximal axon.

Motility of an autonomous protein-based artificial motor that operates via a burnt-bridge principle.

Inspired by biology, great progress has been made in creating artificial molecular motors. However, the dream of harnessing proteins - the building blocks selected by nature - to design autonomous motors has so far remained elusive. Here we report the synthesis and characterization of the Lawnmower, an autonomous, protein-based artificial molecular motor comprised of a spherical hub decorated with proteases. Its "burnt-bridge" motion is directed by cleavage of a peptide lawn, promoting motion towards unvisited substrate. We find that Lawnmowers exhibit directional motion with average speeds of up to 80 nm/s, comparable to biological motors. By selectively patterning the peptide lawn on microfabricated tracks, we furthermore show that the Lawnmower is capable of track-guided motion. Our work opens an avenue towards nanotechnology applications of artificial protein motors.

Free labial mucocutaneous graft for eyelid reconstruction in four dogs.

PURPOSE: To describe a technique for eyelid margin reconstruction following large mass resection utilizing a free labial mucocutaneous graft. METHODS: Four dogs (4 eyes) underwent en bloc eyelid mass excision under general anesthesia. Measurements were made of the mass followed by free labial mucocutaneous graft retrieval, resection of the mass, and then transplantation of retrieved region of labial mucocutaneous tissue into the resulting defect. RESULTS: Three patients underwent eyelid margin reconstruction with a free labial mucocutaneous graft. One patient received a pedicle advancement graft combined with a free labial mucocutaneous graft. In all cases, a length of 120%-150% of the eyelid defect was retrieved from the oral labia. Postoperative follow-up ranged from 6 weeks to 4 months. All cases had superficial graft necrosis and depigmentation of the donor tissue with total healing time taking up to 8 weeks. All cases had an esthetic and functional reconstruction. CONCLUSIONS: This technique allows reconstruction of the majority of the eyelid margin, greater than that which can be closed primarily. Due to tissue sloughing, the healing time can be extended but cosmetic outcomes are good. Eyelid reconstruction utilizing a free labial graft restored a mucocutaneous margin and recreated a functional eyelid, thus avoiding trichiasis or secondary keratitis.

Molecular dissection of the soluble photosynthetic antenna from the cryptophyte alga Hemiselmis andersenii.

Cryptophyte algae have a unique phycobiliprotein light-harvesting antenna that fills a spectral gap in chlorophyll absorption from photosystems. However, it is unclear how the antenna transfers energy efficiently to these photosystems. We show that the cryptophyte Hemiselmis andersenii expresses an energetically complex antenna comprising three distinct spectrotypes of phycobiliprotein, each composed of two αß protomers but with different quaternary structures arising from a diverse α subunit family. We report crystal structures of the major phycobiliprotein from each spectrotype. Two-thirds of the antenna consists of open quaternary form phycobiliproteins acting as primary photon acceptors. These are supplemented by a newly discovered open-braced form (~15%), where an insertion in the α subunit produces ~10 nm absorbance red-shift. The final components (~15%) are closed forms with a long wavelength spectral feature due to substitution of a single chromophore. This chromophore is present on only one ß subunit where asymmetry is dictated by the corresponding α subunit. This chromophore creates spectral overlap with chlorophyll, thus bridging the energetic gap between the phycobiliprotein antenna and the photosystems. We propose that the macromolecular organization of the cryptophyte antenna consists of bulk open and open-braced forms that transfer excitations to photosystems via this bridging closed form phycobiliprotein.

Molecular structures reveal the origin of spectral variation in cryptophyte light harvesting antenna proteins.

In addition to their membrane-bound chlorophyll a/c light-harvesting antenna, the cryptophyte algae have evolved a unique phycobiliprotein antenna system located in the thylakoid lumen. The basic unit of this antenna consists of two copies of an αß protomer where the α and ß subunits scaffold different combinations of a limited number of linear tetrapyrrole chromophores. While the ß subunit is highly conserved, encoded by a single plastid gene, the nuclear-encoded α subunits have evolved diversified multigene families. It is still unclear how this sequence diversity results in the spectral diversity of the mature proteins. By careful examination of three newly determined crystal structures in comparison with three previously obtained, we show how the α subunit amino acid sequences control chromophore conformations and hence spectral properties even when the chromophores are identical. Previously we have shown that α subunits control the quaternary structure of the mature αß.αß complex (either open or closed), however, each species appeared to only harbor a single quaternary form. Here we show that species of the Hemiselmis genus contain expressed α subunit genes that encode both distinct quaternary structures. Finally, we have discovered a common single-copy gene (expressed into protein) consisting of tandem copies of a small α subunit that could potentially scaffold pairs of light harvesting units. Together, our results show how the diversity of the multigene α subunit family produces a range of mature cryptophyte antenna proteins with differing spectral properties, and the potential for minor forms that could contribute to acclimation to varying light regimes.

An investigation into the development of qualitative tear film disorders in dogs following cryoepilation for distichiasis.

OBJECTIVE: The aim of this prospective study was to compare tear film quality between dogs who have previously undergone cryoepilation for distichiasis to a reference population. ANIMALS STUDIED: Nine dogs (17 eyes) were recruited after surgery and were compared to a reference population of 21 dogs (42 eyes). PROCEDURES: Canine patients who had previously undergone cryoepilation for distichiasis for a minimum of 1 month prior to examination were recruited. A complete ophthalmic examination was performed by an ABVO resident (BDR), with additional tear tests, including tear film interferometry, infra-red meibography, and a tear film break-up time (TFBUT) performed. The tear test results were compared to a reference population obtained from client-owned dogs with no history of ophthalmic complaints, a normal ophthalmic examination performed by an ABVO resident (BDR) and a Schirmer Tear Test-1 > 15 mm/min. Statistical analysis was performed of the results obtained. RESULTS: The treated group was significantly more affected with meibomian gland dropout (MG-dropout) in 11/17 (64.7%) cases, compared to the reference population of 2/21 (9.5%) (p < .01). The treated group had an odds ratio of 23.8 to develop MG-dropout compared to the reference population (p < .01). Tear film breakup time (TFBUT) was significantly shorter in the treatment group (5.8 ± 2.6 s) compared to the reference population (10.1 ± 1.1 s) (p < .001). In the treatment group, 12/17 (70.5%) of treated eyes had a TFBUT < 5 s compared to 2/21 (9.5%) of the reference population. CONCLUSION: Cryoepilation for distichaiasis appears to be a risk factor for developing MG-dropout and qualitative tear film disorders post-operatively in canines.

Scaffolding proteins guide the evolution of algal light harvesting antennas.

Photosynthetic organisms have developed diverse antennas composed of chromophorylated proteins to increase photon capture. Cryptophyte algae acquired their photosynthetic organelles (plastids) from a red alga by secondary endosymbiosis. Cryptophytes lost the primary red algal antenna, the red algal phycobilisome, replacing it with a unique antenna composed of αß protomers, where the ß subunit originates from the red algal phycobilisome. The origin of the cryptophyte antenna, particularly the unique α subunit, is unknown. Here we show that the cryptophyte antenna evolved from a complex between a red algal scaffolding protein and phycoerythrin ß. Published cryo-EM maps for two red algal phycobilisomes contain clusters of unmodelled density homologous to the cryptophyte-αß protomer. We modelled these densities, identifying a new family of scaffolding proteins related to red algal phycobilisome linker proteins that possess multiple copies of a cryptophyte-α-like domain. These domains bind to, and stabilise, a conserved hydrophobic surface on phycoerythrin ß, which is the same binding site for its primary partner in the red algal phycobilisome, phycoerythrin α. We propose that after endosymbiosis these scaffolding proteins outcompeted the primary binding partner of phycoerythrin ß, resulting in the demise of the red algal phycobilisome and emergence of the cryptophyte antenna.

Virtual Reality Therapy in Mental Health.

Initially designed for the treatment of phobias, the use of virtual reality in phobic disorders has expanded to other mental health disorders such as posttraumatic stress disorder, substance-related disorders, eating disorders, psychosis, and autism spectrum disorder. The goal of this review is to provide an accessible understanding of why this approach is important for future practice, given its potential to provide clinically relevant information associated with the assessment and treatment of people suffering from mental illness. Most of the evidence is available for the use of virtual reality exposure therapy in anxiety disorders and posttraumatic stress disorder. There is hardly any evidence that virtual reality therapy is effective in generalized anxiety disorder and obsessive-compulsive disorder. There is increasing evidence that cue exposure therapy is effective in addiction and eating disorders. Studies into the use of virtual reality therapy in psychosis, autism spectrum disorder, and attention deficit hyperactivity disorder (ADHD) are promising.

One year follow-up and mediation in cognitive behavioral therapy and acceptance and commitment therapy for adult depression.

BACKGROUND: Existing therapies for depression are effective, but many patients fail to recover or relapse. To improve care for patients, more research into the effectiveness and working mechanisms of treatments is needed. We examined the long-term efficacy of Cognitive Behavioral Therapy (CBT) and Acceptance and Commitment Therapy (ACT) for Major Depressive Disorder (MDD), testing the hypothesis that CBT outperforms ACT and that both therapies work through their designated mechanisms of change. METHODS: We conducted a randomized controlled trial with 82 patients suffering from MDD. Data were collected before, during and after treatment, and at 12-month follow-up, assessing symptoms of depression, quality of life, dysfunctional attitudes, decentering, and experiential avoidance. RESULTS: Patients in both conditions reported significant and large reductions of depressive symptoms (d = - 1.26 to - 1.60) and improvement in quality of life (d = 0.91 to - 1.28) 12 months following treatment. Our findings indicated no significant differences between the two interventions. Dysfunctional attitudes and decentering mediated treatment effects of depressive symptoms in both CBT and ACT, whereas experiential avoidance mediated treatment effects in ACT only. CONCLUSIONS: Our results indicate that CBT is not more effective in treating depression than ACT. Both treatments seem to work through changes in dysfunctional attitudes and decentering, even though the treatments differ substantially. Change in experiential avoidance as an underlying mechanism seems to be an ACT-specific process. Further research is needed to investigate whether ACT and CBT may work differently for different groups of patients with depression. TRIAL REGISTRATION: clinicaltrials.gov; NCT01517503 . Registered 25 January 2012 - Retrospectively registered.

An Oscillating MinD Protein Determines the Cellular Positioning of the Motility Machinery in Archaea.

MinD proteins are well studied in rod-shaped bacteria such as E. coli, where they display self-organized pole-to-pole oscillations that are important for correct positioning of the Z-ring at mid-cell for cell division. Archaea also encode proteins belonging to the MinD family, but their functions are unknown. MinD homologous proteins were found to be widespread in Euryarchaeota and form a sister group to the bacterial MinD family, distinct from the ParA and other related ATPase families. We aimed to identify the function of four archaeal MinD proteins in the model archaeon Haloferax volcanii. Deletion of the minD genes did not cause cell division or size defects, and the Z-ring was still correctly positioned. Instead, one of the deletions (ΔminD4) reduced swimming motility and hampered the correct formation of motility machinery at the cell poles. In ΔminD4 cells, there is reduced formation of the motility structure and chemosensory arrays, which are essential for signal transduction. In bacteria, several members of the ParA family can position the motility structure and chemosensory arrays via binding to a landmark protein, and consequently these proteins do not oscillate along the cell axis. However, GFP-MinD4 displayed pole-to-pole oscillation and formed polar patches or foci in H. volcanii. The MinD4 membrane-targeting sequence (MTS), homologous to the bacterial MinD MTS, was essential for the oscillation. Surprisingly, mutant MinD4 proteins failed to form polar patches. Thus, MinD4 from H. volcanii combines traits of different bacterial ParA/MinD proteins.

Synthetic biology approaches to dissecting linear motor protein function: towards the design and synthesis of artificial autonomous protein walkers.

Molecular motors and machines are essential for all cellular processes that together enable life. Built from proteins with a wide range of properties, functionalities and performance characteristics, biological motors perform complex tasks and can transduce chemical energy into mechanical work more efficiently than human-made combustion engines. Sophisticated studies of biological protein motors have provided many structural and biophysical insights and enabled the development of models for motor function. However, from the study of highly evolved, biological motors, it remains difficult to discern detailed mechanisms, for example, about the relative role of different force generation mechanisms, or how information is communicated across a protein to achieve the necessary coordination. A promising, complementary approach to answering these questions is to build synthetic protein motors from the bottom up. Indeed, much effort has been invested in functional protein design, but so far, the "holy grail" of designing and building a functional synthetic protein motor has not been realized. Here, we review the progress made to date, and we put forward a roadmap for achieving the aim of constructing the first artificial, autonomously running protein motor. Specifically, we propose to break down the task into (i) enzymatic control of track binding, (ii) the engineering of asymmetry and (iii) the engineering of allosteric control for internal communication. We also propose specific approaches for solving each of these challenges.

Virtual Reality Therapy in Social Anxiety Disorder.

PURPOSE OF REVIEW: This review provides an overview of current methods and important aspects to consider when applying virtual worlds in the treatment of social anxiety disorder (SAD). RECENT FINDINGS: Different aspects such as dialogs between avatars and patients have been investigated as well as virtual audiences, emotional facial expression, and verbal interaction with avatars. Results of these studies are promising. Few randomized controlled trials (RCTs) have investigated the efficacy of virtual reality exposure therapy (VRET) in SAD. Unfortunately, most RCTs into the efficacy of VRET in comparison with exposure in vivo in SAD have been conducted with a combination of cognitive interventions and VRET. No differences between these conditions were found, but the pure effect of VRET as a stand-alone treatment has only been investigated in one RCT, wherein VRET was not superior to exposure in vivo. Current research into different facets of SAD and VRET has produced promising results with respect to technological aspects. No differences in efficacy between cognitive behavior therapy and VRET were found, but there is a clear need for studies investigating the efficacy of VRET as a stand-alone treatment and the therapeutic processes involved before this therapy can be disseminated in routine clinical practice.

Explicit and implicit attachment and the outcomes of acceptance and commitment therapy and cognitive behavioral therapy for depression.

BACKGROUND: Attachment theory predicts that patients who are not securely attached may benefit less from psychological treatment. However, evidence on the predictive role of attachment in the effectiveness of treatment for depression is limited. METHODS: Explicit attachment styles, levels of attachment anxiety and attachment avoidance, as well as implicit relational self-esteem and implicit relational anxiety were assessed in 67 patients with major depressive disorder (MDD) receiving Acceptance and Commitment Therapy (ACT) or Cognitive Behavioral Therapy (CBT). ANOVA and hierarchical regression analyses were performed to investigate the predictive power of explicit and implicit attachment measures on treatment outcome. RESULTS: Explicit attachment avoidance at pre-treatment significantly predicted reduction of depressive symptoms following treatment. Reductions in attachment anxiety and avoidance from pre- to post-treatment predicted better treatment outcomes. Neither one of the implicit measures, nor change in these measures from pre- tot post-treatment significantly predicted treatment outcome. CONCLUSIONS: Our findings show that attachment avoidance as well as reductions in avoidant and anxious attachment predict symptom reduction after psychological treatment for depression. Future research should use larger sample sizes to further examine the role of attachment orientation as moderator and mediator of treatment outcome. TRIAL REGISTRATION: clinicaltrials.gov; NCT01517503.

Home-based parent training for school-aged children with attention-deficit/hyperactivity disorder and behavior problems with remaining impairing disruptive behaviors after routine treatment: a randomized controlled trial.

The objective is to investigate the effectiveness of home-based behavioral parent training for school-aged children with attention-deficit/hyperactivity disorder (ADHD) and behavior problems with remaining impairing disruptive behaviors after routinely offered treatments in clinical practice. In a randomized controlled study including 73 referred children with ADHD and impairing disruptive symptoms after routine clinical pharmacotherapy and/or clinic-based parent training had been tried or, at least, offered, home-based behavioral parent training (n = 26) was compared to a waiting list (n = 23) and a care-as-usual home-based treatment (n = 24). It was unknown to families which of the home-based treatments that they received. Using mixed models for repeated measures, we examined the effectiveness on the primary outcome measure of children's severity of disruptive behaviors and on a number of secondary outcome measures [the degree to which parents experienced the disruptive behaviors as troublesome, ADHD symptoms, oppositional-defiant disorder (ODD) symptoms, and internalizing problems]. Compared to the waiting list, children receiving home-based parent training improved significantly more regarding severity of disruptive behaviors (ES = 0.75), ADHD symptoms (ES = 0.89), ODD symptoms (ES = 0.65), and internalizing problems (ES = 0.60). Compared to care-as-usual, home-based parent training was more effective in reducing disruptive behaviors (ES = 0.57), ADHD symptoms (ES = 0.89), and ODD symptoms (ES = 0.88). Significantly more reduction of children's internalizing problems was not found. In conclusion, children with ADHD and residual behavioral problems after routine treatment may benefit from home-based behavioral parent training.