Search

A review of the taxonomy and distribution of vestimentiferan tubeworms has been performed. The subfamily Vestimentifera comprises three infrafamilies: Lamellibrachiinae, Escarpiinae, and Tevniinae. The complete descriptions and illustrations of 19 vestimentiferan species known to date are given. Comparative tables of the morphological characteristics of all vestimentiferan genera have been compiled. Lamellibrachiinae appear to be the most eurybathic group, representatives of which inhabit depths of 82-3200 m. Most representatives of Tevniinae reside deeper than 1500 m (except A. spiralis, which can be found at a depth of 750 m). Tevniinae live exclusively on the rocky substrate of hydrothermal vents. Lamellibrachiinae and Escarpiinae inhabit both soft and rocky substrates of cold seeps and the periphery of hydrothermal vents. Tevniinae occur only in the hydrothermal vents of the Pacific Ocean. Escarpiinae are found in the Pacific and Atlantic oceans. Lamellibrachiinae is the most widespread group that inhabits the Pacific and Atlantic oceans, including the Mediterranean Sea. The hypothesis on the Pacific origin on vestimentiferan tubeworms has been discussed. The eurybathic Lamellibrachiinae and Escarpiinae penetrated into the Atlantic Ocean through shallow-water basins of the Tethys Ocean and channels in the place of Mesoamerica, while the deep-sea Tevniinae were not able to do that. [ABSTRACT FROM AUTHOR]

A mathematical model for hydraulic fracturing is proposed. The model is based on the presentation of the fractured portion of the stratum adjacent to the well as a heterogeneous fractured porous medium. Assumptions usually used in the theory of elastic flow are applied. Formulas for determining the size of the hydraulic fracturing zone and the degree of fracture opening under conditions of relative equilibrium are derived. [ABSTRACT FROM AUTHOR]

A mathematical model of the axisymmetric distribution of the phases in the zone of invasion of the water-based drilling mud into the productive stratum whose porous space can simultaneously contain three immiscible fluids (oil, gas, and natural water) is constructed; the model takes into account the high rate of heat transfer between the fluids and the rock matrix. It is shown that the resistivity of the invaded zone depends not only on saturation of the latter by the fluids and the concentration of salts in the water phase, but also on the drilling mud filtrate temperature. It is also shown that there is a jump in the function of stratum saturation by oil on the thermal front. [ABSTRACT FROM AUTHOR]

Various conditions of formation of motionless closed hydrocarbon inclusions are considered: viscous instability of fluid displacement and inhomogeneous rock structure. Conditions of dynamic equilibrium of the inclusion in a water flow are given for one-dimensional and two-dimensional motion. Distributions of the oil content in inclusions of different shapes are numerically calculated. It is found that the amount of unrecovered oil depends on the ratio of the pressure gradients in the filtration flow of water pumped into the reservoir and the characteristic capillary pressure on the boundary of immiscible phases. It is demonstrated that the use of chemical reagents can substantially reduce the effect of capillary forces and promotes oil entrainment by the overall flow. [ABSTRACT FROM AUTHOR]

The article analyzes processes running in an oil pool under contour water flooding and resulting in formation of bypassed oil. Based on stability criteria, the authors discuss destabilization of the residual oil pockets by vibration so that the bypassed oil becomes proved & developed. [ABSTRACT FROM AUTHOR]

Penetration of distilled water into a clay soil sample saturated by a sodium chloride solution is experimentally studied. Changes in filtration characteristics of soil due to penetration of fresh water and swelling of clay particles, as well as due to the action of an electrical field on the replacement process are quantified. It is demonstrated that electrokinetic processes play a key role at the final stage of replacement of the solution by fresh water. Reasons for the emergence of clay self-polarization potentials owing to violation of electrical equilibrium conditions are studied. [ABSTRACT FROM AUTHOR]

Neuropsychology entered a new phase of development in the early '70s when it expanded beyond the bounds of local brain pathology in the narrow sense. Even while A.R. Luria was still alive, quite diffuse cerebrovascular disorders, parkinsonism, head injury, inflammatory processes, etc., came to be used as clinical models for study of the cerebral substrates of higher mental functions. The neuropsychological method has by now demonstrated its extraordinary sensitivity in terms of assessment of the distinctive features of mental activity-not just in functional disorders in specific cerebral zones but also in various abnormal changes in the functional state of the brain secondary to extensive brain damage. During that same period, developmental neuropsychology also evolved, on the basis of research on the genesis of cerebral morphofunctional organs of mental activity in childhood. [ABSTRACT FROM AUTHOR]

1. There has been a traditional interest in the processes of mediation ("mediating activity," to use Vygotsky's term [1983]) in Soviet and Russian psychology, especially in the theory of the development of the human mind. The importance of mediating activity for a person's self-regulation of his own mental activeness is underscored in Leont'ev's famous statement (1981) that there are two moments that give a unique character to the evolution of behavior: the mediated nature of human operations that is the consequence of the introduction of auxiliary means into behavior, on the one hand, and the control over one's own behavior that these means allow, on the other. Physiologists also associate mediation with the "mobilization of important adaptive mechanisms" (Gazenko, 1987). [ABSTRACT FROM AUTHOR]

Introduction: Pancreatic tumors (PT) usually occur after age 60 and almost never in children and young patients (pts). Little is known concerning frequency, morphological and immunohistochemical (IHC) characteristics of PTs in children and young pts. Aim(s): To assess the incidence and prevalence of PT in children and young pts. Materials and methods: five-hundred and forty-eight PTs were verified by IHC, including 358 neuroendocrine neoplasms (pNEN), 53 solid-pseudopapillary (SPT), 129 ductal tumors, and eight other types of PT. 98 (17.8%) of these pts were at the age of 2 to 30 yrs. Results: pNEN were identified in 61.2% (60198) young pts: 32 female, 28 male, at mean age of 21.6 (2-30) yrs. pNENs in 10% pts (6/60) were malignant and sporadic with regional or distant metastases. Four of them at age of 11, 16, 16, 28 yrs with two insulinomas, gastrinoma and somatostatinoma died within 2-5 years because of disease progression. Fifty-one pts presented with hypoglycemia, four - Zollinger-Ellison syndromes (SM). The other cases had nonfunctioning pNENs. Sixteen (26.7%) of 60 pts with pNENs had hereditary SM: 13 (21.7%) - MEN-1, two - VHL, one - tuberous sclerosis. Nine (69.2%) of 13 MEN-1 pts had multiple (2 to 8) pNENs. SPT were identified in 35.7% (35198) young pts and mainly occurred in young females (F/M ratio=1:7.8), at mean age of 17.6 (9-30) years. No SPT had signs of malignancy. Conclusion: Predominant types of pancreatic tumors in children and young pts are pNEN and SPT. Young pts with MEN-1 syndrome often have multiple pNENs. [ABSTRACT FROM AUTHOR]

Introduction: Defining localization and potential ACTH-producing extrapituitary neuroendocrine neoplasms (ACTH-epNEN) is important for clinical practice. Aim(s): To assess CK19 expression in ACTH-epNEN of different localization. Materials and methods: CK19 (clone RCK108) and Ki-67 (clone MIB-1) expression were evaluated immunohistochemically (IHC) in 37 ACTH-epNEN specimens: 19 lung (L-NEN) (51.3%); eight thymus (T-NEN) and two mediastinal (M-NEN) (27.2%); six gastrointestinal (GI): three pancreatic (Pn-NEN), one ampulla Vater's (AV-NEN), one appendical (A-NEN), one rectal (R-NEN) (16.2%); two medullary thyroid carcinomas (MTC) (5.4%); in 13 men and 25 women, at mean age 42.1 (16-67 yrs). Results: Clinical presentation of ACTH-ectopic syndrome was diagnosed in 30 (81.1%) patients (pts) at early stage, in three (8.1%) pts at late stage of the disease (Pn-NEN, AV-NEN, R-NEN). Four tumors (10.8%) were asymptomatic (2 L-NEN, Pn-NEN, M-NEN). Twenty of 37 (54.1%) ACTH-epNEN had CK19 expression: in 9/10 T-NEN and M-NEN (90%), 2/2 MTC (100%), 4/6 GI-NEN (66.7%) and 5/19 L-NEN (26.3%). All CK 19-positive ACTH-epNENs of GI and thyroid, mediastinum, thymus and three tumors of the lung were malignant (with metastases or recurrences). We got a strong correlation between CK19 expression in ACTH-epNE and an increased level of Ki-67 (Spearman r=0,75, p<0.001). Conclusion: CK19 expression in ACTH-epNEN is an important criteria for malignancy potential. Especially for L-NEN, this can be used to predict recurrence and metastases. [ABSTRACT FROM AUTHOR]

Nuchal organs are epidermal sensory structures present in most annelids. Based on one of the interpretations, they serve in larval settlement. Siboglinids lack nuchal organs in adult and larval stages, however, larvae of some siboglinids inhabiting seeps and hydrothermal vents are capable of swimming up to 100 km away from their home hydrothermal field to colonize a new one. One question that remains is, what organ are siboglinid larvae using to search and locate suitable substrates? To determine if any nuchal organs are present in siboglinid larvae, we studied the head and sensory apparatus in successive larval stages in a frenulate, Siboglinum fiordicum (Webb, 1963), using transmission electron microscopy and immunocytochemistry. In the early trochophore stage, we found an unpaired dorsal organ lying proximal to the posterior prototroch. This organ consists of trochoblast- and "covering" cells. Trochoblasts exhibited serotonin-like immunoreactivity and likely correspond to ciliated supporting cells, where cilia and microvilli project into the olfactory chamber. The "covering" cells are characterized by the presence of large nuclei with numerous pores and thick processes that project into the olfactory chamber, forming the contacts with the trochoblast projections. We have shown for the first time the presence of a nuchal-like organ in annelids as early as the trochophore stage. The presence of this organ in siboglinid trochophores while they are still in the inside the female tube suggests that this structure might be associated with functions other than settlement, such as communication or initiation of the departure from her tube., (© 2023 Wiley Periodicals LLC.)

Macrofauna can contribute substantially to the organic matter cycling on the seafloor, yet the role of terrestrial and chemosynthetic organic matter in the diets of microphagous (deposit and suspension) feeders is poorly understood. In the present study, we used stable isotopes of carbon and nitrogen to test the hypothesis that the terrestrial organic matter supplied with river runoff and local chemosynthetic production at methane seeps might be important organic matter sources for macrofaunal consumers on the Laptev Sea shelf. We sampled locations from three habitats with the presumed differences in organic matter supply: "Delta" with terrestrial inputs from the Lena River, "Background" on the northern part of the shelf with pelagic production as the main organic matter source, and "Seep" in the areas with detected methane seepage, where chemosynthetic production might be available. Macrobenthic communities inhabiting each of the habitats were characterized by a distinct isotopic niche, mostly in terms of δ 13 C values, directly reflecting differences in the origin of organic matter supply, while δ 15 N values mostly reflected the feeding group (surface deposit/suspension feeders, subsurface deposit feeders, and carnivores). We conclude that both terrestrial and chemosynthetic organic matter sources might be substitutes for pelagic primary production in the benthic food webs on the largely oligotrophic Laptev Sea shelf. Furthermore, species-specific differences in the isotopic niches of species belonging to the same feeding group are discussed, as well as the isotopic niches of the symbiotrophic tubeworm Oligobrachia sp. and the rissoid gastropod Frigidoalvania sp., which are exclusively associated with methane seeps., Competing Interests: The authors declare that they have no competing interests., (© 2023 Kokarev et al.)

Bacterial symbioses allow annelids to colonise extreme ecological niches, such as hydrothermal vents and whale falls. Yet, the genetic principles sustaining these symbioses remain unclear. Here, we show that different genomic adaptations underpin the symbioses of phylogenetically related annelids with distinct nutritional strategies. Genome compaction and extensive gene losses distinguish the heterotrophic symbiosis of the bone-eating worm Osedax frankpressi from the chemoautotrophic symbiosis of deep-sea Vestimentifera. Osedax's endosymbionts complement many of the host's metabolic deficiencies, including the loss of pathways to recycle nitrogen and synthesise some amino acids. Osedax's endosymbionts possess the glyoxylate cycle, which could allow more efficient catabolism of bone-derived nutrients and the production of carbohydrates from fatty acids. Unlike in most Vestimentifera, innate immunity genes are reduced in O. frankpressi, which, however, has an expansion of matrix metalloproteases to digest collagen. Our study supports that distinct nutritional interactions influence host genome evolution differently in highly specialised symbioses., (© 2023. The Author(s).)

In March 2020 the World Health Organization (WHO) declared a pandemic of the novel coronavirus infection (COVID-19) caused by the SARS-CoV-2 respiratory virus. The high spread rate of the virus and the severity of the course of the disease are of great clinical and epidemiological significance, making it relevant for ophthalmologists to study the mechanisms of how SARS-CoV-2 infects ocular structures, as well as possible clinical manifestations of the infection in the organ of vision. This review contains analysis, systematization, and generalization of epidemiological and clinical data on SARS-CoV-2 ocular lesions and was carried out with the data found in scientific abstract databases. The article presents main clinical ophthalmic manifestations of COVID-19, lists the utilized schemes of etiotropic and symptomatic therapy, recommended preventive measures, and considers the possible ophthalmic complications after vaccination against COVID-19.

The Oweniidae are marine annelids with many unusual features of organ system, development, morphology, and ultrastructure. Together with magelonids, oweniids have been placed within the Palaeoannelida, a sister group to all remaining annelids. The study of this group may increase our understanding of the early evolution of annelids (including their radiation and diversification). In the current research, the morphology and ulta-anatomy of the head region of Owenia borealis is studied by scanning electron microscopy (SEM), 3D reconstructions, transmission electron microscopy (TEM), and whole-mount immunostaining with confocal laser scanning microscopy. According to SEM, the tentacle apparatus consists of 8-14 branched arms, which are covered by monociliary cells that form a ciliary groove extending along the oral side of the arm base. Each tentacle contains a coelomic cavity with a network of blood capillaries. Monociliary myoepithelial cells of the tentacle coelomic cavity form both the longitudinal and the transverse muscles. The structure of this myoepithelium is intermediate between a simple and pseudo-stratified myoepithelium. Overall, tentacles lack prominent zonality, i.e., co-localization of ciliary zones, neurite bundles, and muscles. This organization, which indicates a non-specialized tentacle crown in O. borealis and other oweniids with tentacles, may be ancestral for annelids. TEM, light, and confocal laser scanning microscopy revealed that the head region contains the anterior nerve center comprising of outer and inner (=circumoral) nerve rings. Both nerve rings are organized as concentrated nerve plexus, which contains perikarya and neurites extending between basal projections of epithelial cells (radial glia). The outer nerve ring gives rise to several thick neurite bundles, which branch and extend along aboral side of each tentacle. Accordingly to their immunoreactivity, both rings of the anterior nerve center could be homologized with the dorsal roots of circumesophageal connectives of the typical annelids. Accordingly to its ultrastructure, the outer nerve ring of O. borealis and so-called brain of other oweniids can not be regarded as a typical brain, i.e. the most anterior ganglion, because it lacks ganglionic structure., (© 2021. The Author(s).)

Background: Many annelids, including well-studied species such as Platynereis, show similar structured segments along their body axis (homonomous segmentation). However, numerous annelid species diverge from this pattern and exhibit specialised segments or body regions (heteronomous segmentation). Recent phylogenomic studies and paleontological findings suggest that a heteronomous body architecture may represent an ancestral condition in Annelida. To better understand the segmentation within heteronomous species we describe the myogenesis and mesodermal delineation of segments in Siboglinum fiordicum during development., Results: Employing confocal and transmission electron microscopy we show that the somatic longitudinal musculature consists of four separate strands, among which ventrolateral one is the most prominent and is proposed to drive the search movements of the head of the late metatrochophore. The somatic circular musculature lies inside the longitudinal musculature and is predominantly developed at the anterior end of the competent larva to support the burrowing behaviour. Our application of transmission electron microscopy allows us to describe the developmental order of the non-muscular septa. The first septum to form is supported by thick bundles of longitudinal muscles and separates the body into an anterior and a posterior region. The second group of septa to develop further divides the posterior body region (opisthosoma) and is supported by developing circular muscles. At the late larval stage, a septum reinforced by circular muscles divides the anterior body region into a forepart and a trunk segment. The remaining septa and their circular muscles form one by one at the very posterior end of the opisthosoma., Conclusions: The heteronomous Siboglinum lacks the strict anterior to posterior sequence of segment formation as it is found in the most studied annelid species. Instead, the first septum divides the body into two body regions before segments are laid down in first the posterior opisthosoma and then in the anterior body, respectively. Similar patterns of segment formation are described for the heteronomous chaetopterid Chaetopterus variopedatus and serpulid Hydroides elegans and may represent an adaptation of these annelids to the settlement and transition to the sedentarian-tubiculous mode of life., (© 2021. The Author(s).)

We report on the first subpicometer interferometer flown in space. It was part of ESA's Laser Interferometer Space Antenna (LISA) Pathfinder mission and performed the fundamental measurement of the positional and angular motion of two free-falling test masses. The interferometer worked immediately, stably, and reliably from switch on until the end of the mission with exceptionally low residual noise of 32.0&#95;{-1.7}^{+2.4}  fm/sqrt[Hz], significantly better than required. We present an upper limit for the sensor performance at millihertz frequencies and a model for the measured sensitivity above 200 mHz.

The Laser Interferometer Space Antenna Pathfinder (LPF) main observable, labeled Δg, is the differential force per unit mass acting on the two test masses under free fall conditions after the contribution of all non-gravitational forces has been compensated. At low frequencies, the differential force is compensated by an applied electrostatic actuation force, which then must be subtracted from the measured acceleration to obtain Δg. Any inaccuracy in the actuation force contaminates the residual acceleration. This study investigates the accuracy of the electrostatic actuation system and its impact on the LPF main observable. It is shown that the inaccuracy is mainly caused by the rounding errors in the waveform processing and also by the random error caused by the analog to digital converter random noise in the control loop. Both errors are one order of magnitude smaller than the resolution of the commanded voltages. We developed a simulator based on the LPF design to compute the close-to-reality actuation voltages and, consequently, the resulting actuation forces. The simulator is applied during post-processing the LPF data.

Oweniidae is a basal group of recent annelids and nowadays it attracts the attention of researchers of many biological fields. Surprisingly, details of their anatomy, like the adult excretory system, remain obscure. Researchers recently suggested that the paired organs of tubeworms in the family Oweniidae are related to nephridia. In the current study of Owenia borealis adults, we determined that these structures are parapodial glandular organs (PGOs) and are located in the first two segments of adults. The PGOs are complex subepidermal multicellular glands that contain secretory cells, that is, goblet cells, which are differentiated by the type of the producing tube matter. The goblet cells are surrounded by muscles that are used to extrude material stored in the PGO's lumen into the external environment. The anterior pair of PGOs have very well-developed rough endoplasmatic reticulum in the proximal cells, spacious Golgi complexes, numerous nail-shaped microvilli, and apocrine secretory processes in the goblet cells of the distal parts. The posterior pair of PGOs only consists of cells, which probably produce proteinaceous fibrils. We discuss the homology of goblet cells with specific nail-shaped microvilli that produce β-chitin within annelids. We also discuss the possibility that PGOs and nephridia have a common origin. This study provides new information on the ultrastructure of cells that secrete the organic material used to form the tubes inhabited by tube-dwelling annelids., (© 2020 Wiley Periodicals, Inc.)

Primary open-angle glaucoma is a major cause of irreversible blindness in all countries of the world. The pathogenesis of primary open-angle glaucoma has not been resolved. In addition to increased intraocular pressure, pathogenetic factors of this disease such as reduced systemic blood pressure, deterioration of ocular blood flow, as well as vascular dysregulation, reperfusion damage and oxidative stress of ocular tissues are now generally recognized. The role of α1-adrenoreceptors in regulation of, for example, ocular blood flow, blood flow in the retina, permeability of the vascular wall etc has already been described., Purpose: To identify the effects of different subtypes of α1-adrenoreceptors on the level of systemic blood pressure in laboratory mice., Material and Methods: Features of blood pressure of 36 laboratory mice older than 18 months having a genetic defect (lines ADRA-1A, ADRA-1D and ADRA-1D) of one of the subtypes of α1-adrenoreceptors (α1a, α1b, α1d) were studied. The control group included ten healthy laboratory mice of the same age. The blood pressure of mice was measured with modern high-precision and noninvasive method using the Coda TM Standard system (Kent Scientific Corporation, U.S.A.)., Results: The mice of the ADRA-1A line were revealed to have reduced systolic and diastolic blood pressure and maximum level of pulse pressure, as well as the greatest fluctuations of pulse pressure; for the ADRA-1B line - the highest levels of systolic and diastolic blood pressure; for the ADRA-1D line - the smallest systolic and diastolic blood pressure and the minimum values of pulse pressure., Conclusion: The obtained results show the specific contribution of α1a, α1b and α1d subtypes of the adrenoreceptors in the maintenance of normal hemodynamic of an organism, which should be considered when studying pathogenesis of primary open-angle glaucoma.