Spike synchrony as a measure of Gestalt structure.

The function of spike synchrony is debatable: some researchers view it as a mechanism for binding perceptual features, others - as a byproduct of brain activity. We argue for an alternative computational role: synchrony can estimate the prior probability of incoming stimuli. In V1, this can be achieved by comparing input with previously acquired visual experience, which is encoded in plastic horizontal intracortical connections. V1 connectivity structure can encode the acquired visual experience in the form of its aggregate statistics. Since the aggregate statistics of natural images tend to follow the Gestalt principles, we can assume that V1 is more often exposed to Gestalt-like stimuli, and this is manifested in its connectivity structure. At the same time, the connectivity structure has an impact on spike synchrony in V1. We used a spiking model with V1-like connectivity to demonstrate that spike synchrony reflects the Gestalt structure of the stimulus. We conducted simulation experiments with three Gestalt laws: proximity, similarity, and continuity, and found substantial differences in firing synchrony for stimuli with varying degrees of Gestalt-likeness. This allows us to conclude that spike synchrony indeed reflects the Gestalt structure of the stimulus, which can be interpreted as a mechanism for prior probability estimation.

How to Treat a Cyclist's Nodule?-Introduction of a Novel, ICG-Assisted Approach.

BACKGROUND: Perineal nodular induration (PNI) is a benign proliferation of the soft tissue in the perineal region that is associated with saddle sports, especially road cycling. The etiology has not been conclusively clarified; however, repeated microtrauma to the collagen and subcutaneous fat tissue by pressure, vibration and shear forces is considered a mechanical pathomechanism. In this context, chronic lymphedema resulting in the development of fibrous tissue has been suggested as an etiological pathway of PNI. The primary aim of this study was to introduce and elucidate a novel operative technique regarding PNI that is assisted by indocyanine green (ICG). In order to provide some context for this approach, we conducted a comprehensive review of the existing literature. This dual objective aimed to contribute to the existing body of knowledge while introducing an innovative surgical approach for managing PNI. METHODS: We reviewed publications relating to PNI published between 1990 and 2023. In addition to the thorough review of the literature, we presented our novel surgical approach. We described how this elaborate approach for extensive cases of PNI involves surgical excision combined with tissue doubling and intraoperative ICG visualization for exact lymphatic vessel obliteration to minimize the risk of recurrence based on the presumed context of lymphatic congestion. RESULTS: The literature research yielded 16 PubMed articles encompassing 23 cases of perineal nodular induration (PNI) or cyclist's nodule. Of these, 9 cases involved females, and 14 involved males. Conservative treatment was documented in 7 cases (30%), while surgical approaches were reported in 16 cases (70%). Notably, a limited number of articles focused on histopathological or radiological characteristics, with a shortage of structured reviews on surgical treatment options. Only two articles provided detailed insights into surgical techniques. Similarly to the two cases of surgical intervention identified in the literature research, the post-operative recovery in our ICG assisted surgical approach was prompt, meaning a return to cycling was possible six weeks after surgery. At the end of the observation period (twelve months after surgery), regular scar formation and no signs of recurrence were seen. CONCLUSION: We hope that this article draws attention to the condition of PNI in times of increasing popularity of cycling as a sport. We aimed to contribute to the existing body of knowledge through our thorough review of the existing literature while introducing an innovative surgical approach for managing PNI. Due to the successful outcome, the combination of tissue doubling, intraoperative ICG visualization and postoperative negative wound therapy should be considered as a therapeutic strategy in cases of large PNI.

How Reliable Is Breast Volume Assessment When the Patient Is Lying Flat?-Volumetric Assessment of Breast Volume Using a Vectra H2 Handheld Device in Different Positions.

(1) Background: Three-dimensional (3D) volumetric assessment is receiving increased recognition in breast surgery. It is commonly used for preoperative planning and postoperative control with the patient standing in an upright position. Recently, intraoperative use was evaluated with patients in the supine position. The aim of this prospective study was to evaluate the volumetric changes in 3D surface imaging depending on the patient's position. (2) Methods: 3D volumetric analysis was performed using a Vectra-H2 device with patients in standing, sitting, and supine positions. A total of 100 complete datasets of female breasts were included in the study. The measured volumes of each evaluated breast (n = 200) were compared between the three positions. (3) Results: The mean difference between the 3D volumetric assessments of the sitting and standing positions per breast was 7.15 cc and, thus, statistically insignificant (p = 0.28). However, the difference between supine and standing positions, at 120.31 cc, was significant (p < 0.01). (4) Conclusions: The 3D volumetric assessment of breasts in the supine position did not statistically correlate with the validated assessment of breast volume in the standing position while breast volume in the sitting position is reliable and correlates with the assessment of a standing patient. We conclude that intraoperative volumetric assessment should be performed with patients in an upright sitting position.

Evaluation of Intraoperative Volumetric Assessment of Breast Volume Using 3D Handheld Stereo Photogrammetric Device.

Methods for assessing three-dimensional (3D) breast volume are becoming increasingly popular in breast surgery. However, the precision of intraoperative volumetric assessment is still unclear. Until now, only non-validated scanning systems have been used for intraoperative volumetric analyses. This study aimed to assess the feasibility, handling, and accuracy of a commercially available, validated, and portable device for intraoperative 3D volumetric evaluation. All patients who underwent breast surgery from 2020 to 2022 were identified from our institutional database. Intraoperative 3D volumetric assessments of 103 patients were included in this study. Standardized 3D volumetric measurements were obtained 3 months postoperatively to compare the intraoperatively generated volumetric assessment. All of the study participants were women with a mean age of 48.3 ± 14.7 years (range: 20-89). The mean time for intraoperative volumetric assessment was 8.7 ± 2.6 min. The postoperative 3D volumetric assessment, with a mean volume of 507.11 ± 206.29 cc, showed no significant difference from the intraoperative volumetric measurements of 504.24 ± 276.61 cc (p = 0.68). The mean absolute volume difference between the intraoperative simulations and postoperative results was 27.1 cc. Intraoperative 3D volumetric assessment using the VECTRA H2 imaging system seems to be a feasible, reliable, and accurate method for measuring breast volume. Based on this finding, we plan to investigate whether volumetric objective evaluations will help to improve breast symmetry in the future.

How Useful Is the SSN-Nipple Distance? An Analytical Questionnaire Survey on Anthropometric Measurements for the Aesthetically Ideal Positioning of the Nipple-Areolar Complex.

Several studies have attempted to identify the optimal anthropometric measurement for the aesthetically ideal positioning of the nipple-areolar complex. However, no standardised solutions and measurements for planning surgical procedures have been reached. The aim of this study is to identify the optimal anthropometric measurement between the suprasternal notch (SSN)-nipple distance and mid-clavicle (MC)-nipple distance for the aesthetic position of the nipple-areola complex (NAC) on the breast. A detailed online survey was sent to 300 board-certified plastic surgeons and residents of plastic surgery departments of hospitals in German, Austrian, and Swiss. A similar survey was also provided to 100 patients who had planned or had already undergone breast surgery. All participants were asked to rank the attractiveness of a series of women's breasts in images with different NAC position measurements. The images showed breasts from two different measurements and distances: all the breasts had equal dimensions and proportions and the same areola size. Complete datasets were obtained from 203 of the 300 board-certified plastic surgeons and residents of plastic surgery departments in German-speaking countries (recall 68%) and from 100 patients. The majority of doctors and patients find a symmetrical breast with a mirrored position of the nipple-areola complex more attractive than a non-symmetrical breast. In cases with minor measurement differences, such as 0.5 cm (SSN vs. MC), there is no relevant difference in the breast symmetry. However, at larger distances, the MC-to-nipple distance is superior for achieving aesthetically appealing symmetry compared with the SSN-to-nipple distance. Using the MC-to-nipple distance seems to be superior for correct nipple positioning than the SSN-to-nipple distance and is a valuable preoperative measurement option for breast symmetry with correct nipple height. Further studies on this topic involving a more general population should be conducted to confirm the improvements in perception with the preoperative measurements using the anatomical landmarks.

Improving symmetry of nipple-areola complex (NAC) position in reduction mammoplasty using laser level projection.

BACKGROUND: Symmetrical height of the nipple-areola complex (NAC) is a key factor in the perception of breast symmetry. For preoperative markings, we mainly rely on conventional anthropometric measurements of distances in correlation to anatomical landmarks. In this study, we evaluated whether the use of a class 2 laser projection water level would lead to better symmetry of nipple height in reduction mammoplasty procedures when used for preoperative planning. METHODS: We analysed 100 patients undergoing reduction mammoplasty with a supero-medial pedicle and wise-pattern skin resection. We compared the bilateral differences in nipple height of the last 50 reduction mammoplasty procedures before using the laser projection water level (group A; no laser) with the first 50 reduction mammoplasties after implementation of this device (group B; laser). The follow-up period was 12 months. RESULTS: A total of 48 patients were included in group A and 44 patients in group B. Patient demographics, mean resection weight and complications did not differ statistically significantly. Nipple height differences were significantly lower in group B (laser), measuring 0.22 ± 0.20 cm (0-0.9; n = 44), than those in group A (no laser; p < 0.001), measuring 0.61 ± 0.28 cm (0.2-1.2; n = 49). CONCLUSION: Using laser level projection helped improve nipple height symmetry in reduction mammoplasty. We consider a difference of more than 1 cm in nipple height to be unacceptable in aesthetic reduction mammoplasty. This simple tool facilitates preoperative markings, and we find it to be safe, quick to install and very helpful in daily practice.

Hypoxic pre-conditioned adipose-derived stem/progenitor cells embedded in fibrin conduits promote peripheral nerve regeneration in a sciatic nerve graft model.

Recent results emphasize the supportive effects of adipose-derived multipotent stem/progenitor cells (ADSPCs) in peripheral nerve recovery. Cultivation under hypoxia is considered to enhance the release of the regenerative potential of ADSPCs. This study aimed to examine whether peripheral nerve regeneration in a rat model of autologous sciatic nerve graft benefits from an additional custom-made fibrin conduit seeded with hypoxic pre-conditioned (2% oxygen for 72 hours) autologous ADSPCs (n = 9). This treatment mode was compared with three others: fibrin conduit seeded with ADSPCs cultivated under normoxic conditions (n = 9); non-cell-carrying conduit (n = 9); and nerve autograft only (n = 9). A 16-week follow-up included functional testing (sciatic functional index and static sciatic index) as well as postmortem muscle mass analyses and morphometric nerve evaluations (histology, g-ratio, axon density, and diameter). At 8 weeks, the hypoxic pre-conditioned group achieved significantly higher sciatic functional index/static sciatic index scores than the other three groups, indicating faster functional regeneration. Furthermore, histologic evaluation showed significantly increased axon outgrowth/branching, axon density, remyelination, and a reduced relative connective tissue area. Hypoxic pre-conditioned ADSPCs seeded in fibrin conduits are a promising adjunct to current nerve autografts. Further studies are needed to understand the underlying cellular mechanism and to investigate a potential application in clinical practice.

A novel chemical inhibitor of polar auxin transport promotes shoot regeneration by local enhancement of HD-ZIP III transcription.

De novo shoot organogenesis is a prerequisite for numerous applications in plant research and breeding but is often a limiting factor, for example, in genome editing approaches. Class III homeodomain-leucine zipper (HD-ZIP III) transcription factors have been characterized as crucial regulators of shoot specification, however up-stream components controlling their activity during shoot regeneration are only partially identified. In a chemical genetic screen, we isolated ZIC2, a novel activator of HD-ZIP III activity. Using molecular, physiological and hormone transport analyses in Arabidopsis and sunflower (Helianthus annuus), we examined the molecular mechanism by which the drug promotes HD-ZIP III expression. ZIC2-dependent upregulation of HD-ZIP III transcription promotes shoot regeneration in Arabidopsis and is accompanied by the induction of shoot specifying factors WUS and RAP2.6L and a subset of cytokinin biosynthesis enzymes. ZIC2's effect on HD-ZIP III expression and regeneration is based on its ability to limit polar auxin transport. We further provide evidence that chemical modulation of auxin efflux can enhance de novo shoot formation in the regeneration recalcitrant species sunflower. Activation of HD-ZIP III transcription during shoot regeneration depends on the local distribution of auxin and chemical modulation of auxin transport can be used to overcome poor shoot organogenesis in tissue culture.

[Liposuction with consequences: what to consider when using prilocaine]. / Folgenreiche Liposuktion ­ was man im Umgang mit Prilocain beachten sollte.

Aetiologically, prilocaine-induced methaemoglobinaemia is a rare form of acquired methaemoglobinaemia, which occurs rarely in the first place. The following report highlights a potentially dangerous complication arising after application of prilocaine during liposuction.A young female visited the Accident and Emergency Department following a pre-syncopal fall. As a consequence of her fall, she experienced debilitating wrist pain and exhibited a laceration on her chin. She had undergone liposuction of the lower extremity as an outpatient approximately 12 hours earlier and received regional anaesthesia in the process. A large volume of an anaesthetic solution containing prilocaine had been injected into the tissue.The patient was normotensive and slightly tachycardic and had oxygen saturations of 90 % on room air. She was cyanotic and her lips were pale. Initial arterial blood gas analysis showed a methaemoglobin fraction, which was increased significantly to 10.9 %. Conventional radiography confirmed the presence of a minimally dislocated distal radius fracture. Following subsequent oxygen therapy over a four-hour period, the patient's methaemoglobin level dropped to 6 %, her lip cyanosis abated and her vital parameters stabilised. The laceration of her chin was sutured and her wrist immobilised in a split plaster brace. After a 12-hour hospital stay, the patient was discharged. At her six-week follow-up appointment, the fracture had healed and both the functional and cosmetic aspects of her chin wound were adequate. We hope that this report draws the attention of emergency care personnel to the possible diagnosis of prilocaine-induced methaemoglobinaemia after liposuction and encourages more general discussions around the use of prilocaine.

Comparison of Outcomes of End-to-End versus End-to-Side Anastomoses in Lower Extremity Free Flap Reconstructions.

BACKGROUND: Whether to perform an end-to-end (ETE) versus end-to-side (ETS) arterial anastomosis is an integral part of preoperative planning and intraoperative decision making in free flap-based reconstructions. This study evaluated the impact of microsurgical anastomotic technique on outcomes of lower extremity reconstructions, with a focus on patients with peripheral arterial disease (PAD). METHODS: Over a 6-year period, 425 patients underwent 437 microvascular lower extremity free flap reconstructions with fasciocutaneous anterolateral thigh- or gracilis muscle flaps at a single surgical center. The cases were divided into an ETE (n = 297 patients) versus ETS (n = 128 patients) group according to the anastomotic technique. A retrospective analysis of patients' demographics, perioperative details, surgical complications, free flap types, recipient sites, flap survival, and the potential impact of PAD on outcomes was performed. Patient groups were comparable regarding comorbidities, American Society of Anesthesiologists scores, types of performed free flaps and recipient sites. RESULTS: We found no significant differences between the ETE versus ETS groups regarding the rate of major or minor complications (p > 0.05). Specifically, in patients suffering from PAD (n = 64) the type of arterial anastomosis had no effect on the outcome. CONCLUSION: Overall, no significant differences in outcomes were observed when comparing the types of performed arterial anastomosis. This observation also held true for the subgroup of patients with PAD. Given that an ETS anastomosis did not increase the risk to encounter complications while preserving distal perfusion, we believe that this technique is the method of choice, especially in patients with impaired vascular status.

Validation of a novel animal model for sciatic nerve repair with an adipose-derived stem cell loaded fibrin conduit.

Despite the regenerative capabilities of peripheral nerves, severe injuries or neuronal trauma of critical size impose immense hurdles for proper restoration of neuro-muscular circuitry. Autologous nerve grafts improve re-establishment of connectivity, but also comprise substantial donor site morbidity. We developed a rat model which allows the testing of different cell applications, i.e., mesenchymal stem cells, to improve nerve regeneration in vivo. To mimic inaccurate alignment of autologous nerve grafts with the injured nerve, a 20 mm portion of the sciatic nerve was excised, and sutured back in place in reversed direction. To validate the feasibility of our novel model, a fibrin gel conduit containing autologous undifferentiated adipose-derived stem cells was applied around the coaptation sites and compared to autologous nerve grafts. After evaluating sciatic nerve function for 16 weeks postoperatively, animals were sacrificed, and gastrocnemius muscle weight was determined along with morphological parameters (g-ratio, axon density & diameter) of regenerating axons. Interestingly, the addition of undifferentiated adipose-derived stem cells resulted in a significantly improved re-myelination, axon ingrowth and functional outcome, when compared to animals without a cell seeded conduit. The presented model thus displays several intriguing features: it imitates a certain mismatch in size, distribution and orientation of axons within the nerve coaptation site. The fibrin conduit itself allows for an easy application of cells and, as a true critical-size defect model, any observed improvement relates directly to the performed intervention. Since fibrin and adipose-derived stem cells have been approved for human applications, the technique can theoretically be performed on humans. Thus, we suggest that the model is a powerful tool to investigate cell mediated assistance of peripheral nerve regeneration.