Intrinsically disordered proteins and intrinsically disordered protein regions.

Intrinsically disordered proteins (IDPs) and IDP regions fail to form a stable structure, yet they exhibit biological activities. Their mobile flexibility and structural instability are encoded by their amino acid sequences. They recognize proteins, nucleic acids, and other types of partners; they accelerate interactions and chemical reactions between bound partners; and they help accommodate posttranslational modifications, alternative splicing, protein fusions, and insertions or deletions. Overall, IDP-associated biological activities complement those of structured proteins. Recently, there has been an explosion of studies on IDP regions and their functions, yet the discovery and investigation of these proteins have a long, mostly ignored history. Along with recent discoveries, we present several early examples and the mechanisms by which IDPs contribute to function, which we hope will encourage comprehensive discussion of IDPs and IDP regions in biochemistry textbooks. Finally, we propose future directions for IDP research.

Clinical and Radiological Differences between Patients Diagnosed with Acute Ischemic Stroke and Chameleons at the Emergency Room: Insights from a Single-Center Observational Study.

INTRODUCTION: Scarce data exist about clinical/radiological differences between acute ischemic strokes diagnosed in the emergency room (AISER) and stroke chameleons (SCs). We aimed at describing the differences observed in a comprehensive stroke center in Chile. METHODS: Prospective observational study of patients with ischemic stroke syndromes admitted to the emergency room (ER) of Clínica Alemana between December 2014 and October 2023. RESULTS: 1,197 patients were included; of these 63 (5.2%, 95% CI: 4.1-6.6) were SC; these were younger (p < 0.001), less frequently hypertensive (p = 0.03), and they also had lower systolic (SBP) (p < 0.001), diastolic blood pressures (DBP) (p = 0.011), and NIHSS (p < 0.001). Clinically, they presented less frequently gaze (p = 0.008) and campimetry alterations (p = 0.03), facial (p < 0.001) and limb weakness (left arm [p = 0.004], right arm (p = 0.041), left leg (p = 0.001), right leg p = 0.0029), sensory abnormalities (p < 0.001), and dysarthria (p < 0.001). Neuroradiological evaluations included less frequently large vessel occlusions (p = 0.01) and other stroke locations (p = 0.005); they also differed in their etiologies (p < 0.001). Brainstem strokes (p < 0.001) and extinction/inattention symptoms (p < 0.001) were only seen in AISER. In multivariate analysis, younger age (OR: 0.945; 95% CI: 0.93-0.96), DBP (OR: 0.97; 95% CI, 0.95-0.99), facial weakness (OR: 0.39; 95% CI: 0.19-0.78), sensory abnormities (OR: 0.16.18; 95% CI, 0.05-0.4), infratentorial location (OR: 0.36; 95% CI, 0.15-0.78), posterior circulation involvement (OR: 3.02; 95% CI, 1.45-6.3), cardioembolic (OR: 3.5; 95% CI, 1.56-7.99), and undetermined (OR: 2.42; 95% CI, 1.22-4.7; 95%) etiologies, remained statistically significant. A stepwise analysis including only clinical elements present on the patient's arrival to the ER, demonstrates that age (OR: 0.95; 95% CI: 0.94-0.97), DBP (OR: 0.97; 95% CI, 0.95-0.99), the presence of atrial fibrillation (OR: 2.22; 95% CI, 1.04-4.75, NIHSS (OR: 0.88; 95% CI, 0.71-0.89) and the presence in NIHSS of 1a level of consciousness (OR: 5.66; CI: 95% 1.8-16.9), 1b level of consciousness questions (OR: 3.023; 95% CI, 1.35-6.8), facial weakness (OR: 0.3; CI: 95% 0.17-0.8), and sensory abnormalities (OR: 0.27; 95% CI, 0.1-0.72) remained statistically significant. CONCLUSION: SC had clinical and radiological differences compared to AISER. An additional relevant finding is that neurological symptoms in a patient with atrial fibrillation, even with a negative diffusion-weighted imaging, should be carefully evaluated as a potential stroke until other causes are satisfactorily ruled out.

Lipid bilayer membrane permeability mechanism of the K-Ras(G12D)-inhibitory bicyclic peptide KS-58 elucidated by molecular dynamics simulations.

Peptides are mid-size molecules (700-2000 g/mol) and have attracted particular interest as therapeutic modalities as they are superior in controlling protein-protein interactions, a process that is a typical drug target category, compared with small molecules (<500 g/mol). In 2020, we identified KS-58 (1333 g/mol) as a K-Ras(G12D)-inhibitory bicyclic peptide and suggested its cell membrane permeability. However, the membrane permeability mechanism had not been elucidated. In this study, we aim to clarify the mechanism by molecular dynamics (MD) simulations. Initially, we simulated the molecular conformations of KS-58 in water (a polar solvent) and in chloroform (a non-polar solvent). The identified stable conformations were significantly different in each solvent. KS-58 behaves as a chameleon-like molecule as it alters its polar surface area (PSA) depending on the solvent environment. It was also discovered that orientation of Asp's side chain is a critical energy barrier for KS-58 altering its conformation from hydrophilic to lipophilic. Taking these properties into consideration, we simulated its lipid bilayer membrane permeability. KS-58 shifted toward the inside of the lipid bilayer membrane with altering its conformations to lipophilic. When the simulation condition was set in deionized form of that carboxy group of Asp, KS-58 traveled deeper inside the cell membrane. PSA and the depth of the membrane penetration correlated. In vitro data suggested that cell membrane permeability of KS-58 is improved in weakly acidic conditions leading to partial deionization of the carboxy group. Our data provide an example of the molecular properties of mid-size peptides with membrane accessibility and propose an effective metadynamics approach to elucidate such molecular mechanisms by MD simulations.

A Redactable Blockchain-Based Data Management Scheme for Agricultural Product Traceability.

With the development of agricultural information technology, the Internet of Things and blockchain have become important in the traceability of agricultural products. Sensors collect real-time data in agricultural production and a blockchain provides a secure and transparent storage medium for these data, which improves the transparency and credibility of agricultural product traceability. However, existing agricultural product traceability solutions are limited by the immutability of the blockchain, making it difficult to delete erroneous data and modify the scope of data sharing. This damages the credibility of traceability data and is not conducive to the exchange and sharing of information among enterprises. In this article, we propose an agricultural product traceability data management scheme based on a redactable blockchain. This scheme allows agricultural enterprises to encrypt data to protect privacy. In order to facilitate the maintenance and sharing of data, we introduce a chameleon hash function to provide data modification capabilities. Enterprises can fix erroneous data and update the access permissions of the data. To improve the efficiency of block editing, our scheme adopts a distributed block editing method. This method supports threshold editing operations, avoiding single-point-of-failure issues. We save records of data modifications on the blockchain and establish accountability mechanisms to identify malicious entities. Finally, in this paper we provide a security analysis of our proposed solution and verify its effectiveness through experiments. Compared with the existing scheme, the block generating speed is improved by 42% and the block editing speed is improved by 29.3% at 125 nodes.

Vibration Signal Noise-Reduction Method of Slewing Bearings Based on the Hybrid Reinforcement Chameleon Swarm Algorithm, Variate Mode Decomposition, and Wavelet Threshold (HRCSA-VMD-WT) Integrated Model.

To enhance fault detection in slewing bearing vibration signals, an advanced noise-reduction model, HRCSA-VMD-WT, is designed for effective signal noise elimination. This model innovates by refining the Chameleon Swarm Algorithm (CSA) into a more potent Hybrid Reinforcement CSA (HRCSA), incorporating strategies from Chaotic Reverse Learning (CRL), the Whale Optimization Algorithm's (WOA) bubble-net hunting, and the greedy strategy with the Cauchy mutation to diversify the initial population, accelerate convergence, and prevent local optimum entrapment. Furthermore, by optimizing Variate Mode Decomposition (VMD) input parameters with HRCSA, Intrinsic Mode Function (IMF) components are extracted and categorized into noisy and pure signals using cosine similarity. Subsequently, the Wavelet Threshold (WT) denoising targets the noisy IMFs before reconstructing the vibration signal from purified IMFs, achieving significant noise reduction. Comparative experiments demonstrate HRCSA's superiority over Particle Swarm Optimization (PSO), WOA, and Gray Wolf Optimization (GWO) regarding convergence speed and precision. Notably, HRCSA-VMD-WT increases the Signal-to-Noise Ratio (SNR) by a minimum of 74.9% and reduces the Root Mean Square Error (RMSE) by at least 41.2% when compared to both CSA-VMD-WT and Empirical Mode Decomposition with Wavelet Transform (EMD-WT). This study improves fault detection accuracy and efficiency in vibration signals and offers a dependable and effective diagnostic solution for slewing bearing maintenance.

Going Viral: An Investigation into the Chameleonic Behaviour of Antiviral Compounds.

The ability to adjust conformations in response to the polarity of the environment, i.e. molecular chameleonicity, is considered to be important for conferring both high aqueous solubility and high cell permeability to drugs in chemical space beyond Lipinski's rule of 5. We determined the conformational ensembles populated by the antiviral drugs asunaprevir, simeprevir, atazanavir and daclatasvir in polar (DMSO-d6 ) and non-polar (chloroform) environments with NMR spectroscopy. Daclatasvir was fairly rigid, whereas the first three showed large flexibility in both environments, that translated into major differences in solvent accessible 3D polar surface area within each conformational ensemble. No significant differences in size and polar surface area were observed between the DMSO-d6 and chloroform ensembles of these three drugs. We propose that such flexible compounds are characterized as "partial molecular chameleons" and hypothesize that their ability to adopt conformations with low polar surface area contributes to their membrane permeability and oral absorption.

The Effect of Pulling and Twisting Forces on Chameleon Sequence Peptides.

Chameleon sequences are amino acid sequences found in several distinct configurations in experiment. They challenge our understanding of the link between sequence and structure, and provide insight into structural competition in proteins. Here, we study the energy landscapes for three such sequences, and interrogate how pulling and twisting forces impact the available structural ensembles. Chameleon sequences do not necessarily exhibit multiple structural ensembles on a multifunnel energy landscape when we consider them in isolation. The application of even small forces leads to drastic changes in the energy landscapes. For pulling forces, we observe transitions from helical to extended structures in a very small span of forces. For twisting forces, the picture is much more complex, and highly dependent on the magnitude and handedness of the applied force as well as the reference angle for the twist. Depending on these parameters, more complex and more simplistic energy landscapes are observed alongside more and less diverse structural ensembles. The impact of even small forces is significant, confirming their likely role in folding events. In addition, small forces exerted by the remaining scaffold of a protein may be sufficient to lead to the adoption of a specific structural ensemble by a chameleon sequence.

Chameleon-like microbes promote microecological differentiation of Daqu.

Chameleon-like microbes in the fermentation community are an internal factor that facilitate the transformation of the community to the corresponding homeostasis states under specific environmental conditions. High temperature daqu can form three typical microecologies during the preparation process, making it an ideal system for studying chameleon-like microbes. This study integrated multi-omic methods such as metaproteomics, and determined that Neurospora crassa, Aspergillus nidulans, Bacillus subtilis and Oceanobacillus iheyensis were chameleon-like microbes that regulated the metabolic differences of five-member heterocyclic amino acids in daqu, resulting in microecological differentiation. Synthetic microbial consortia consisting of the four chameleon-like microbes with (T6) and without (T4) the dominant functional bacteria Saccharopolyspora erythraea and Virgibacillus haloimitrificans were fermented under simulated in situ conditions. The community constructed by microorganisms with greater functional diversity (T6) was more robust, and its metabolome was more similar to the in situ system. When exposed to environmental disturbances, the functional diversity helped to maintain the community stability by increasing the dissimilarity of chameleon-like microbes in the community and forming different homeostasis.

Instrumental and visual evaluation of the color adjustment potential of different single-shade resin composites to human teeth of various shades.

OBJECTIVE: The study aims to evaluate the color adjustment potential (CAP-I, CAP-V) of different single-shade resin composites. MATERIALS AND METHODS: The shades of 40 human incisors were determined using a spectrophotometer, with the teeth divided into four groups of the same shade (n = 10). The following single-shade resin composites were tested: Omnichroma, Charisma Diamond One, Vittra Unique, and Essentia Universal. The specimens were prepared as "dual" and "single." Standardized cavity preparations (diameter, 7 mm; depth, 2 mm) were prepared in human incisor teeth and then restored for dual specimens. Composite duplicates of human incisors were prepared with resin composites for single specimens (n = 10). The color match of these specimens to that of unrestored human incisors was compared, and the color difference (ΔE*) was calculated. Independent observers conducted a visual evaluation of the specimens and scored them. CAP-I and CAP-V values were determined. A one-way analysis of variance test was used for statistical analysis (p < 0.05). RESULTS: There was no statistically significant difference between the CAP-V and CAP-I values of the tested single-shade resin composites (p > 0.05). All the materials tested had acceptable color-matching potential. CONCLUSIONS: In terms of color matching, there were no significant differences between the different tooth shades of all the tested resin composites. CLINICAL RELEVANCE: Single-shade resin composites have acceptable CAP. The use of single-shade resin composites can reduce in-chair clinical times by minimizing the time spent on shade selection.

Mechanomyography Signal Pattern Recognition of Knee and Ankle Movements Using Swarm Intelligence Algorithm-Based Feature Selection Methods.

Pattern recognition of lower-limb movements based on mechanomyography (MMG) signals has a certain application value in the study of wearable rehabilitation-training devices. In this paper, MMG feature selection methods based on a chameleon swarm algorithm (CSA) and a grasshopper optimization algorithm (GOA) are proposed for the pattern recognition of knee and ankle movements in the sitting and standing positions. Wireless multichannel MMG acquisition systems were designed and used to collect MMG movements from four sites on the subjects thighs. The relationship between the threshold values and classification accuracy was analyzed, and comparatively high recognition rates were obtained after redundant information was eliminated. When the threshold value rose, the recognition rates from the CSA fluctuated within a small range: up to 88.17% (sitting position) and 90.07% (standing position). However, the recognition rates from the GOA drop dramatically when increasing the threshold value. The comparison results demonstrated that using a GOA consumes less time and selects fewer features, while a CSA gives higher recognition rates of knee and ankle movements.

Comparative development of limb musculature in phylogenetically and ecologically divergent lizards.

BACKGROUND: Squamate reptiles (lizards, snakes, and amphisbaenians) exhibit incredible diversity in their locomotion, behavior, morphology, and ecological breadth. Although they often are used as models of locomotor diversity, surprisingly little attention has been given to muscle development in squamate reptiles. In fact, the most detailed examination was conducted almost 80 years ago and solely focused on the proximal limb regions. Herein, we present forelimb and hindlimb muscle morphogenesis data for three lizard species with different locomotion and feeding strategies: the desert grassland whiptail lizard, the central bearded dragon, and the veiled chameleon. This study fills critical gaps in our understanding of muscle morphogenesis in squamate reptiles and presents a comparative and temporospatial analysis of muscle development. RESULTS: Our results reveal a conserved pattern of early muscle development among lizards with different adult morphologies and ecologies. The variations that exist are concentrated in distal regions, particularly the specialized autopodia of chameleons, where differentiation of muscles associated with the digits is delayed. CONCLUSIONS: The chameleon autopod provides an example of major evolutionary modifications to the skeleton with only minor disruption of the conserved order and pattern of limb muscle development. This robustness of muscle patterning facilitates the evolution of extreme yet functional phenotypes.

Adaptive Density Spatial Clustering Method Fusing Chameleon Swarm Algorithm.

The density-based spatial clustering of application with noise (DBSCAN) algorithm is able to cluster arbitrarily structured datasets. However, the clustering result of this algorithm is exceptionally sensitive to the neighborhood radius (Eps) and noise points, and it is hard to obtain the best result quickly and accurately with it. To solve the above problems, we propose an adaptive DBSCAN method based on the chameleon swarm algorithm (CSA-DBSCAN). First, we take the clustering evaluation index of the DBSCNA algorithm as the objective function and use the chameleon swarm algorithm (CSA) to iteratively optimize the evaluation index value of the DBSCAN algorithm to obtain the best Eps value and clustering result. Then, we introduce the theory of deviation in the data point spatial distance of the nearest neighbor search mechanism to assign the identified noise points, which solves the problem of over-identification of the algorithm noise points. Finally, we construct color image superpixel information to improve the CSA-DBSCAN algorithm's performance regarding image segmentation. The simulation results of synthetic datasets, real-world datasets, and color images show that the CSA-DBSCAN algorithm can quickly find accurate clustering results and segment color images effectively. The CSA-DBSCAN algorithm has certain clustering effectiveness and practicality.

Vision in chameleons-A model for non-mammalian vertebrates.

Chameleons (Chamaeleonidae, Reptilia) are known for their extreme sensory and motor adaptations to arboreal life and insectivoury. They show most distinct sequences of visuo-motor patterns in threat avoidance and in predation with prey capture being performed by tongue strikes that are unparalleled in vertebrates. Optical adaptations result in retinal image enlargement and the unique capacity to determine target distance by accommodation cues. Ocular adaptations result in complex eye movements that are context dependent, not independent, as observed in threat avoidance and predation. In predation, evidence from the chameleons' capacity to track multiple targets support the view that their eyes are under individual controls. Eye movements and body movements are lateralised, with lateralisation being a function of many factors at the population, individual, and specific-situation levels. Chameleons are considered a potentially important model for vision in non-mammalian vertebrates. They provide exceptional behavioural tools for studying eye movements as well as information gathering and analysis. They open the field of lateralisation, decision making, and context dependence. Finally, chameleons allow a deeper examination of the relationships between their unique visuo-motor capacities and the central nervous system of reptiles and ectotherms, in general, as compared with mammals.

Effects of chameleon dispense-to-plunge speed on particle concentration, complex formation, and final resolution: A case study using the Neisseria gonorrhoeae ribonucleotide reductase inactive complex.

Ribonucleotide reductase (RNR) is an essential enzyme that converts ribonucleotides to deoxyribonucleotides and is a promising antibiotic target, but few RNRs have been structurally characterized. We present the use of the chameleon, a commercially-available piezoelectric cryogenic electron microscopy plunger, to address complex denaturation in the Neisseria gonorrhoeae class Ia RNR. Here, we characterize the extent of denaturation of the ring-shaped complex following grid preparation using a traditional plunger and using a chameleon with varying dispense-to-plunge times. We also characterize how dispense-to-plunge time influences the amount of protein sample required for grid preparation and preferred orientation of the sample. We demonstrate that the fastest dispense-to-plunge time of 54 ms is sufficient for generation of a data set that produces a high quality structure, and that a traditional plunging technique or slow chameleon dispense-to-plunge times generate data sets limited in resolution by complex denaturation. The 4.3 Å resolution structure of Neisseria gonorrhoeae class Ia RNR in the inactive α4ß4 oligomeric state solved using the chameleon with a fast dispense-to-plunge time yields molecular information regarding similarities and differences to the well studied Escherichia coli class Ia RNR α4ß4 ring.

Chameleon-Like Reconstruction on Redox Catalysts Adaptive to Alkali Water Electrolysis.

Pre-catalyst reconstruction in electrochemical processes has recently attracted intensive attention with mechanistic potentials to uncover really active species and catalytic mechanisms and advance targeted catalyst designs. Here, nickel-molybdenum oxysulfide is deliberately fabricated as pre-catalyst to present a comprehensive study on reconstruction dynamics for the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in alkali water electrolysis. Operando Raman spectroscopy together with X-ray photoelectron spectroscopy and electron microscopy capture dynamic reconstruction including geometric, component and phase evolutions, revealing a chameleon-like reconstruction self-adaptive to OER and HER demands under oxidative and reductive conditions, respectively. The in situ generated active NiOOH and Ni species with ultrafine and porous textures exhibit superior OER and HER performance, respectively, and an electrolyzer with such two reconstructed electrodes demonstrates steady overall water splitting with an extraordinary 80% electricity-to-hydrogen (ETH) energy conversion efficiency. This work highlights dynamic reconstruction adaptability to electrochemical conditions and develops an automatic avenue toward the targeted design of advanced catalysts.

Do male panther chameleons use different aspects of color change to settle disputes?

In many animals, males engage in agonistic interactions. Color signals are commonly used to mitigate these potentially harmful interactions. Both pigment-based color and structural color, notably ultraviolet coloration, are used in this context to convey information, including an animal's resource holding potential (RHP) or social status. Despite extensive previous work on this topic, the ability to change color in this context has received relatively little attention. Moreover, no studies have considered the visible and the ultraviolet components of this ability. Thus, whether changes in ultraviolet play a role in settling intraspecific disputes remains unknown. Here, we investigate the role of color change during intrasexual agonistic interactions in male panther chameleons (Furcifer pardalis). To do so, we combined behavioral experiments and color analysis. Our results show that the outcome of male intrasexual agonistic interactions depends on particular aspects of color change in the visible spectrum. Dominant males exhibit more brightness changes and Euclidian distance changes within the HSV color space at the level of the bands and interbands, suggesting a prominent role of these patterns in panther chameleon communication. Our results also align with previous studies in another chameleon species, thus supporting the key role of brightness changes in chameleon communication, at least in a competitive context. Interestingly, although our species did exhibit UV coloration, neither this coloration nor its changes seem to be involved in intrasexual agonistic interactions among males, possibly because those signals may be used for other purposes like attracting mates, repelling predators, or deception.

Metaheuristic Approach to Synthesis of Suspension System of Mobile Robot for Mining Infrastructure Inspection.

The article describes the problem of geometric synthesis of the inspection robot suspension system, designed for operation in difficult conditions with the presence of scattered obstacles. The exemplary application of a mine infrastructure inspection robot is developed and supported by the ideas. The brief introduction presents current trends, requirements and known design approaches of platforms enabled to cross the obstacles. The idea of a nature-inspired wheel-legged robot is given, and the general outline of its characteristics is provided. Then the general idea of kinematic system elements selection is discussed. The main subject of geometrical synthesis of the chosen four-bar mechanism is described in detail. The mathematical model of the suspension and connections between the parts of the structure is clarified. The well-known analytical approach of brute force search is analyzed and validated. Then the method inspired by the branch and bound algorithm is developed. Finally, a novel application of the nature-inspired algorithm (the Chameleon Swarm Algorithm) to synthesis is proposed. The obtained results are analyzed, and a brief comparison of methods is given. The successful implementation of the algorithm is presented. The obtained results are effectively tested with simulations and experimental tests. The designed structure developed with the CSA is assembled and attached to the prototype of a 14-DOF wheel-legged robot. Furthermore, the principles of walking and the elements forming the control structure were also discussed. The paper is summarized with the description of the developed wheel-legged robot LegVan 1v2.

Color adjustment potential of resin composites: Optical illusion or physical reality, a comprehensive overview.

OBJECTIVE: The objective was to provide a comprehensive overview of color interactions between resin composite (RC) and its surroundings, analyze the design and results of respective research studies, and provide clinical and research recommendations. OVERVIEW: Resin composite (RC) materials can adjust their color to that of surrounding enamel and dentin to a different extent. This phenomenon has been referred to as the "chameleon effect" in dental jargon, while color blending/adjustment/shifting/assimilation is more scientific terms. Studies that evaluated the color adjustment potential of RCs have employed different methods. This article discusses the (a) terminology used to describe color adjustment potential, (b) color science theories associated with color adjustment, (c) design of respective studies, including methods, specimens, and calculations, and (d) their outcome and reported results. Clinical implications and future directions related to the color adjustment potential of RCs are also provided. CONCLUSIONS: Factors that influence the color adjustment potential of RCs are classified into three categories: (1) material type, (2) cavity design, and (3) the substrate surrounding the restoration. Each factor can be optimized to enhance color matching and the restorative outcome. CLINICAL SIGNIFICANCE: A material that blends well and exhibits pronounced color adjustment potential would likely improve the color match and therefore the esthetic outcome. These materials "work" for dental professionals by compensating for their suboptimal shade matching and/or lack of an excellent match in the used material. This review aims to further the understanding of the inherent properties of RCs and allow clinicians to fully utilize them to place RC restorations and minimize the time spent on modifying or replacing existing ones. Hence, the outcomes would encompass the increased chairside efficiency, enhanced esthetic outcome, and patient satisfaction.

Ocular elongation and retraction in foveated reptiles.

BACKGROUND: Pronounced asymmetric changes in ocular globe size during eye development have been observed in a number of species ranging from humans to lizards. In contrast, largely symmetric changes in globe size have been described for other species like rodents. We propose that asymmetric changes in the three-dimensional structure of the developing eye correlate with the types of retinal remodeling needed to produce areas of high photoreceptor density. To test this idea, we systematically examined three-dimensional aspects of globe size as a function of eye development in the bifoveated brown anole, Anolis sagrei. RESULTS: During embryonic development, the anole eye undergoes dynamic changes in ocular shape. Initially spherical, the eye elongates in the presumptive foveal regions of the retina and then proceeds through a period of retraction that returns the eye to its spherical shape. During this period of retraction, pit formation and photoreceptor cell packing are observed. We found a similar pattern of elongation and retraction associated with the single fovea of the veiled chameleon, Chamaeleo calyptratus. CONCLUSIONS: These results, together with those reported for other foveated species, support the idea that areas of high photoreceptor packing occur in regions where the ocular globe asymmetrically elongates and retracts during development.

Evaluating the role of endometrial colour Doppler dynamic tissue perfusion measurements in in vitro fertilisation success.

The role of uterine receptivity and endometrial perfusion in in vitro fertilisation (IVF) remains unclear. In our prospective pilot study, we used a new dynamic tissue perfusion measurement method to evaluate this relationship in humans. A standard ovulation induction and embryo transfer method were applied to all the volunteers. On the day of embryo transfer, dynamic images of the uterus were recorded using colour Doppler ultrasound, and these images were uploaded onto PixelFlux Chameleon Software (GmbH, Münster, Germany). After determining the region of interest (ROI), the average velocity, intensity, and area values for all coloured pixels in the ROI, the tissue resistance index (RI) and the tissue pulsatility index were calculated. Endometrial thickness, morphology and dynamic endometrial perfusion parameters were compared between the clinically pregnant and non-pregnant groups. Endometrial thickness, morphology values and endometrial dynamic tissue perfusion measurements were similar between the groups. This study compared perfusion parameters between clinically pregnant and non-pregnant patients by accurately calculating endometrial tissue perfusion using standard software to establish its relationship with implantation success in IVF treatment.IMPACT STATEMENTWhat is already known about this subject? The relationship between IVF success, endometrial receptivity and perfusion is known. Clear valuations of endometrial receptivity require an endometrial biopsy which may cause endometrial damage to the actual IVF cycle. This problem has led researchers to conduct non-interventional studies. Studies have revealed the value of endometrial thickness, pattern and Doppler examination of endometrial uterine arteries in predicting the success of IVF treatment.What do the results of this study add? This prospective pilot study is the first one to use this programme in humans to evaluate uterine receptivity in IVF. Successful results can be obtained by using computer programmes in tissues where perfusion parameters cannot be measured using traditional colour Doppler ultrasonography. Revealing the relationship between tissue perfusion and IVF success will be more effective and accurate with the development of software technologies.What are the implications of these findings for clinical practice and/or further research? To increase the success of IVF treatment, current and new technological developments, as well as imaging methods should continue to be tested.