Regeneration in the Segmented Annelid Capitella teleta

The segmented worms, or annelids, are a clade within the Lophotrochozoa, one of the three bilaterian superclades. Annelids have long been models for regeneration studies due to their impressive regenerative abilities. Furthermore, the group exhibits variation in adult regeneration abilities with some species able to replace anterior segments, posterior segments, both or neither. Successful regeneration includes regrowth of complex organ systems, including the centralized nervous system, gut, musculature, nephridia and gonads. Here, regenerative capabilities of the annelid Capitella teleta are reviewed. C. teleta exhibits robust posterior regeneration and benefits from having an available sequenced genome and functional genomic tools available to study the molecular and cellular control of the regeneration response. The highly stereotypic developmental program of C. teleta provides opportunities to study adult regeneration and generate robust comparisons between development and regeneration.

The Role of the Temporal Pole in Temporal Lobe Epilepsy: A Diffusion Kurtosis Imaging Study

Objective: This study aims to evaluate the use of diffusion kurtosis imaging (DKI) to detect microstructural abnormalities within the temporal pole (TP) in temporal lobe epilepsy (TLE) patients. Methods: DKI quantitative maps were obtained from fourteen lesional (MRI+) and ten non-lesional (MRI-) TLE patients, along with twenty-one healthy controls. This included mean (MK); radial (RK) and axial kurtosis (AK); mean diffusivity (MD) and axonal water fraction (AWF). Automated fiber quantification (AFQ) was used to quantify DKI measurements along the inferior longitudinal (ILF) and uncinate fasciculus (Unc). ILF and Unc tract profiles were compared between groups and tested for correlation with seizure duration. To characterize temporopolar cortex (TC) microstructure, DKI maps were sampled at varying depths from superficial white matter (WM) towards the pial surface. Each patient group was separated according to side ipsilateral to the epileptogenic temporal lobe and their AFQ results were used as input for statistical analyses. Results: Significant differences were observed between MRI+ and controls (p < 0.005), towards the most anterior of ILF and Unc proximal to the TP of the left (not right) ipsilateral temporal lobe for MK, RK, AWK and MD. Noticeable differences were also observed mostly towards the TP for MK, RK and AWK in the MRI- group. DKI measurements correlated with seizure duration, mostly towards the anterior segments of the WM bundles. Stronger differences in MK, RK and AWF within the TC were observed in the MRI+ and noticeable differences (except for MD) in MRI- groups compared to controls. Significance: The study demonstrates that DKI has potential to detect subtle microstructural alterations within the anterior segments of the ILF and Unc and the connected TC in TLE patients including MRI- subjects. This could aid our understanding of the extrahippocampal areas involved in seizure generation in TLE and might inform surgical planning, leading to better seizure outcomes.

Myofunctional parameters in patients using full removable dentures with progenic and prognathic ratio of the anterior segments of the edentulous jaws

The aim study was to construct artificial dentitions based on the method of mathematical modeling with the progenic and prognatic ratios of toothless frontal segments and to analyze the functional activity of the masticatory muscles in patients using dentures made in this way, compared with standard prosthetic structures. To compare and interpret the data obtained, electromyographic studies were performed in the control group (16 people), whose teeth were made using the traditional method, and the main group (22 people), whose artificial teeth were formed according to individual mathematical calculations, taking into account the size of the sagittal gap of the frontal segments of the progenic and prognatic ratio of toothless jaws. Statistical processing of the results of the electro-myographic study was carried out using the Statistica application software package. The digital data were processed by the method of variational statistics using the Student's t-test. The analysis of the obtained data showed the advantages of using individual mathematical calculations when solving the issue of tactics for constructing dentitions in the frontal segment of toothless jaws, taking into account the degree of the sagittal gap in the progenic and prognatic correlation of the jaws and their possible combinations.

Variants of the design of the dentition of the anterior segments with a progenic and prognathic ratio of edentulous jaws

Objective: To improve the prosthetic and aesthetic treatment of patients with complete absence of teeth, taking into account the development of an algorithm for determining the size of the sagittal gap of the frontal segments against the background of a progenic or prognathic ratio of the jaws and their combinations. Methods: A method of mathematical modeling based on digital data of the distance between the tops of the alveolar ridges of the frontal areas of the edentulous jaws has been developed using a designed measuring device. Results: The results of digital calculations based on the determination of the root-mean-square deviation of the interalveolar lines revealed a different amount of bends and configurations of the interalveolar gaps and median arches common to both parts of the frontal segments. Five main variants of the interalveolar fissure and 26 cases of symmetric or asymmetric arrangement of the tops of the alveolar ridges of the right and left sides were obtained. Accordingly, the divergence angles for each pair in the projection of the missing teeth had their own characteristics, which must be taken into account when deciding on the choice of tooth placement in each specific case. Conclusions: Based on the obtained digital interpolation ratios of the interalveolar lines and the angles of their inclination in relation to the midline, the anterior teeth are placed taking into account the level of the sagittal gap, the parameters of which have different levels of symmetry or asymmetry on the right and left sides.

Anterior Hox Genes and the Process of Cephalization

During evolution, bilateral animals have experienced a progressive process of cephalization with the anterior concentration of nervous tissue, sensory organs and the appearance of dedicated feeding structures surrounding the mouth. Cephalization has been achieved by the specialization of the unsegmented anterior end of the body (the acron) and the sequential recruitment to the head of adjacent anterior segments. Here we review the key developmental contribution of Hox1–5 genes to the formation of cephalic structures in vertebrates and arthropods and discuss how this evolved. The appearance of Hox cephalic genes preceded the evolution of a highly specialized head in both groups, indicating that Hox gene involvement in the control of cephalic structures was acquired independently during the evolution of vertebrates and invertebrates to regulate the genes required for head innovation.

Minimally Invasive Surgery for Intraocular Lens Removal and Intrascleral Intraocular Lens Fixation with Trabeculectomy in a Patient with Dislocated Intraocular Lens and Elevated Intraocular Pressure

A 88-year-old female who was being treated for end-stage pseudoexfoliation syndrome was referred to our hospital for treatment of dislocated intraocular lens (IOL) and the elevated intraocular pressure (IOP) and in the right eye (RE). At the first visit to our hospital, best-corrected visual acuity (BCVA) was 0.2 in the RE and 0.02 in the left eye (LE). IOP was 47 mm Hg in the RE and 21 mm Hg in the LE. Slit-lamp examination showed no abnormalities in anterior segments and dislocated IOL in the RE. Fundus photograph showed optic disc pallor in both eyes. We performed the combined therapy of flanged intrascleral IOL fixation with the double-needle technique and trabeculectomy. Throughout the follow-up period, BCVA slightly improved from 0.2 to 0.4 in the RE. The angle of tilt of the IOL was 6.6, 7.9, and 8.7° as measured by swept-source optical coherence tomography at 1, 4, and 6 months after the surgery, respectively. The IOP remained less than 10 mm Hg without having to administer any other glaucoma medications. Furthermore, any complications associated with the surgery were not confirmed.

The role of a difference between target and actual ablation index values for first-pass point-by-point pulmonary vein isolation: results from a multicenter prospective registry

Funding Acknowledgements Type of funding sources: Other. Main funding source(s): Ministry of Science and Higher Education grant (Russian Federation President Grant) Background/Introduction. Pulmonary vein electrical isolation (PVI) is a cornerstone of atrial fibrillation (AF) ablation. The Ablation Index (AI) aims to improve the efficacy and safety of radiofrequency (RF) PVI. First-pass isolation (FPI) is an indicator of PVI acute success. Target AI is being calculated for every operator as a mean value (usually, differently for anterior and posterior left atrial (LA) segments) following several "ideal" first-pass PVI procedures. However, adherence to target values, as well as its clinical importance, are unknown. Purpose. The aim of the present study was to evaluate the difference between the target and actual AI in the real practice. Methods. This work represents data from the Prospective Multicenter AF Ablation Registry. Data were collected using a web-based system. PVI procedures were performed according to the local practice, and RF ablation settings depended on operators’ preferences. Between January 2019 and December 2020, a total of 446 patients were enrolled from 7 centers, 407 of them underwent first-time AF ablation and were included into the analysis (mean age 61 ± 9 years old; 226 (55%) males; 313 (76%) with paroxysmal AF). FPI was determined as PVI achieved after circular ablation around PVs without additional applications plus persistence of bidirectional block over a 20-minute waiting period. Therefore, patients were divided in two groups: Group 1 (FPI, n = 242) and Group 2 (non-FPI, n = 165). Results. There was a significant difference between target (the mean target AI for the anterior LA segments was 438 ± 58 and 390 ± 27 for the posterior segments) and actually achieved mean AI (406 ± 33 for anterior segments and 389 ± 34 for posterior segments) with a greater difference for anterior segments (Δ 26 (95% CI [19; 32], p = 0,0001) than for posterior (Δ 4 (95% CI [0,2; 8], p = 0,042). The number of patients with a mean actual AI lower than a target value on the anterior and posterior LA walls was 219 (54%) and 171 (42%), respectively. In the FPI group higher mean values of target AI were present (FPI 444 ± 52 for anterior and 393 ± 27 for posterior LA segments vs non-FPI 432 ± 51 (p = 0,04) and 387 ± 23 (p = 0,01), respectively). The FPI group was characterized by higher mean actual AIs on anterior segments (FPI 410 ± 36 vs non-FPI 399 ± 25, p = 0,0001). There was no difference between groups in actual AI on the posterior wall (391 ± 27 vs 386 ± 41, p = 0,1). The non-FPI group was characterized by a higher proportion of subjects with hypertension (87% vs 69%, p = 0,0001) and a lower number of subjects with central obesity (body mass index≥30 in 48% vs 57%, p = 0,04). Conclusion(s). According to our prospective multicenter data, target AI is not achieved in a significant proportion of patients during PVI. This is associated with acute PV electrical reconduction and the necessity in additional ablations. FPI can be achieved more frequently when a higher mean AI value is achieved.

Atypical neural topographies underpin dysfunctional pattern separation in temporal lobe epilepsy

Episodic memory is the ability to accurately remember events from our past. The process of pattern separation is hypothesized to underpin this ability and is defined as the ability to orthogonalize memory traces, to maximize the features that make them unique. Contemporary cognitive neuroscience suggests that pattern separation entails complex interactions between the hippocampus and the neocortex, where specific hippocampal subregions shape neural reinstatement in the neocortex. To test this hypothesis, the current work studied both healthy controls and patients with temporal lobe epilepsy (TLE) who present with hippocampal structural anomalies. In all participants, we measured neural activity using functional magnetic resonance imaging (fMRI) while they retrieved memorized items compared to lure items which share features with the target. Behaviorally, TLE patients were less able to exclude lures than controls, and showed a reduction in pattern separation. To assess the hypothesized relationship between neural patterns in the hippocampus and the neocortex, we identified topographic gradients of intrinsic connectivity along neocortical and hippocampal subfield surfaces and identified the topographic profile of the neural activity accompanying pattern separation. In healthy controls, pattern separation followed a graded pattern of neural activity, both along the hippocampal long axis (and peaked in anterior segments that are more heavily engaged in transmodal processing) and along the neocortical hierarchy running from unimodal to transmodal regions (peaking in transmodal default mode regions). In TLE patients, however, this concordance between task-based functional activations and topographic gradients was markedly reduced. Furthermore, person specific measures of concordance between task-related activity and connectivity gradients in patients and controls related to inter-individual differences in behavioral measures of pattern separation and episodic memory, highlighting the functional relevance of the observed topographic motifs. Our work is consistent with an emerging understanding that successful discrimination between memories with similar features entails a shift in the locus of neural activity away from sensory systems, a pattern that is mirrored along the hippocampal long axis and with respect to neocortical hierarchies. More broadly, our study establishes topographic profiling using intrinsic connectivity gradients captures the functional underpinnings of episodic memory processes in manner that is sensitive to their reorganization in pathology.

Ultrastructure and functional morphology of the appendages in the reef-building sedentary polychaete Sabellaria alveolata (Annelida, Sedentaria, Sabellida)

Background The sedentary polychaete Sabellaria alveolata, the sandcastle or honeycomb worm, possesses four different kinds of appendages besides the parapodia: opercular papillae, tentacular filaments, palps, and branchiae. It exhibits a highly specialized anterior end, the operculum, formed by the prostomium, peristomium, and two anterior segments. The operculum comprises opercular papillae, tentacular filaments, and palps. Paired branchiae are present from the second thoracic chaetiger onwards on the posteriorly following segments except for the last ones. Ultrastructural data on these appendages are either scanty, incomplete, or even lacking in Sabellariidae. In order to analyze their functional morphology, to bridge the data gap, and providing data for future phylogenetic and evolutionary analyses, we investigated the appendages of S. alveolata by applying light microscopy, confocal laser scanning microscopy, scanning, and transmission electron microscopy. Results In S. alveolata the entire body is covered by a thin cuticle characterized by the absence of layers of parallel collagen fibers with no differentiation between the various body regions including the branchiae. The opercular papillae bear numerous tufts of receptor cells and lack motile cilia. The tentacular filaments show a distinctive pattern of motile cilia. Their most conspicuous morphological feature is a cell-free cartilaginous endoskeletal structure enclosed by ECM. Besides musculature the filaments include a single coelomic cavity but blood vessels are absent. The palps are ciliated and possess two coelomic cavities and a single blind-ending internal blood vessel. Besides external ciliation and receptor cells, the coelomate branchiae are highly vascularized and equipped with numerous blood spaces extending deep between the epidermal cells resulting in low diffusion distances. Conclusions All appendages, including the branchiae, bear receptor cells and, as such, are sensory. The opercular papillae resemble typical parapodial cirri. In contrast, the tentacular filaments have a triple function: sensing, collecting and transporting particles. A similarity to branchiae can be excluded. The palps are typical grooved palps. A revised classification of polychaete branchiae is suggested; thereby, the branchiae of S. alveolata belong to the most common type comprising coelom, musculature, and blood vessels. The results indicate that diffusion distances between blood and environment have been underestimated in many cases.