Lamellar Tissue Research Articles

Methylated tirilazad may mitigate oligofructose-induced laminitis in horses.

Laminitis is a serious health condition that can cause severe pain and lameness in horses. Due to lack of understanding of laminitis, treatments often fail to achieve the desired results. In recent years, we have begun to recognize that laminitis may involve a complex interaction between local and systemic inflammation. Dysbiosis of the gut microbiota has been linked in the development of systemic inflammation, and our previous findings suggest that the development of laminitis is closely linked to the production of harmful metabolites of the gut microbiota. In addition, it was found that localized lesions in the hoof, especially lamellar injuries, are the most direct cause of laminitis. Matrix metalloproteinases have been found to be strongly associated with the development of laminitis. Recent discovery has found that methylated tirilazad has a role in repairing laminar tissue in vitro. However, its efficacy in horses never has been studied. Therefore, we aimed to investigate the efficacy of methylated tirilazad (product name: PTP-102) in the prevention/treatment of oligofructose-induced laminitis. The results showed that oligofructose successfully induced laminitis in horses, resulting in detreated clinical signs. Blood indices (including inflammation-related indices and other related indices) were significantly increased. Observations of dissection and staining showed significant bleeding, swelling, and damage to hoof tissue. Analysis of the gut microbiota showed a significant decrease in abundance and diversity, and a significant increase in the relative abundance of specific bacteria. Following methylated tirilazad intervention, there were a significant improvement in clinical signs, blood markers and lamellar tissue damage. Additionally, methylated tirilazad positively influenced the gut microbiota structure by reducing the relative abundance of genera closely associated with the development of equine laminitis. This suggests that some of the therapeutic mechanism of methylated tirilazad may be linked to its effects on the gut microbiota. Notably, methylated tirilazad had better effect in the treatment group than the prophylactic group, indicating the post-diagnosis utility of methylated tirilazad for laminitis management.

Morphofunctional characteristics оs penis of mammals

ABSTRACT The aim of this work was to analyze the issues of the morphofunctional organization of the baculum (os penis) of mammals. In many mammals, to give strength and density to the organ, bone tissue is present in the penis, which forms the bone of the penis (os penis or baculum). This structure is evolutionarily young; it is present only in representatives of the evolutionarily youngest class of vertebrates - the class of mammals. The baculum is present in the penis of both marsupials and representatives of the orders of placental mammals (many rodents, some chiropterans, pinnipeds, cetaceans, some predators, prosimians and some monkeys). Bone tissue is usually located in the anterior region of the penis between the cavernous and spongy bodies. The baculum is an unpaired bone of an elongated shape; it can have the shape of a rod or plate, straight or curved. In cross-section, in representatives of different species, the bone can be round, square, triangular, or flat. Most often, the baculum is a cylindrical rod, expanded at the base and apex; in the proximal and distal parts there are outgrowths of various shapes. The histogenesis of bone tissue during the formation of the os penis in embryogenesis occurs via indirect osteogenesis. At the site of the future os penis, a cartilaginous model is formed from the mesenchyme, in place of which bone tissue then develops. The basis of the baculum is formed by lamellar bone tissue, in which osteons are well expressed. In the superficial zones of the baculum, coarse fibrous (reticulofibrous) bone tissue, as well as fibrous cartilaginous tissue, was identified. The baculum has been found to increase the overall rigidity of the penis when flexing during copulation. It was revealed that larger baculums are present in mammals, which are characterized by a longer duration of copulation.

Estimation of the in-plane ultimate stress of lamellar tissue as a function of bone mineral density and osteocyte lacunae porosity

Background and ObjectiveDetailed finite element models based on medical images (μ-CT) are commonly used to analyze the mechanical behavior of bone at microscale. In order to simulate the tissue failure onset, isotropic failure criteria of lamellar tissue are often used, despite its non-isotropic and heterogeneous nature. The main goal of the present work is to estimate the in-plane ultimate stress of lamellar bone, considering the influence of mineral content and the porosity due to the osteocyte lacunae concentration. MethodsTo this aim, a representative volume cell of lamellar tissue is modeled numerically, including: (1) non-isotropic elastic properties of tissue as a function of the bone mineral density and (2) explicit modeling of the osteocyte lacunae, considering the range of porosity content, size and orientation of ellipsoid-shaped lacunae. Firstly, the element size for the finite element models have been defined from a preliminary convergence analysis. Bounds on the ultimate stress of non-porous lamellar tissue are estimated for two values of bone mineral density, considering the results of tensile and compressive tests of wet osteons from the literature. Subsequently, the ultimate stress of lamellar tissue considering several values of micro-porosity is addressed. ResultsResults obtained in this work show that the strength of lamellar bone decreases exponentially with the increase of lacunae porosity concentration. Ultimate stress of non-porous tissue (p=0%) increases with high mineral content, reaching a value of S¯transc=355.40±39.80 MPa for compression in the transversal direction of the fiber bundles, being BMD=1.246g/cm3. The mean value for the longitudinal to transverse strength ratio evaluated for porosity p=0%,1% and 5% and a mineral content BMD=1.2g/cm3, is 2.47:1 for tension and 1.55:1 for compression. These values are in agreement with literature. ConclusionsOsteocyte lacunae act as stress concentrators, acting as potential stimulus for the bone regeneration process. A novel micromechanical model for the in-plane ultimate stress of lamellar tissue as a function of mineral content and lacunae concentration is presented. Additional considerations about the intralamellar shear stress evolution are also given.

Neutrophil extracellular traps and active myeloperoxidase concentrate in lamellar tissue of equids with naturally occurring laminitis

Laminitis is a pathology of the equine digit ultimately leading to a failure of the dermo-epidermal interface. Neutrophil activation is recognized as a major factor in SIRS-associated laminitis and has recently been described in induced endocrinopathic laminitis evidenced by the presence of myeloperoxidase (MPO). Neutrophil extracellular traps (NET) are released with neutrophil activation. This study aimed to investigate the presence and activity of MPO and NET in the lamellar tissue of equids presented with naturally occurring laminitis. Samples of lamellar tissue of five horses and five donkeys presented with laminitis, as well as eight control horses without laminitis, were collected. Lamellar tissue extracts were submitted to ELISA and specific immuno-extraction followed by enzymatic detection (SIEFED) assays to confirm the presence and activity of both MPO and NET. Lamellar sections were also immunohistopathologically stained for MPO and NET. Analysis of lamellar tissue extracts revealed that laminitis cases had significantly higher levels of total MPO concentration, MPO activity, and NET-bound MPO activity in comparison to control horses. Moreover, a strong correlation was identified between the activity of NET-bound MPO and the total MPO activity, which suggests that MPO activity partly originates from NET-bound MPO. Immunohistochemical staining showed that MPO and NET labelling in laminitis cases was moderate to marked, primarily in the epidermis and in inflammatory infiltrates containing neutrophils, while labelling in control horses was minimal. This article constitutes the first indication of the presence and activity of NET-bound MPO in the lamellar tissue of horses and donkeys with naturally occurring laminitis. Targeting these substances may provide new treatment possibilities for this debilitating disease.

A MODERN VIEW ON REPARATIVE OSTEOGENESIS: MAIN STAGES AND THEIR PATTERNS

Introduction. Reparative osteogenesis is a staged mechanism that ensures the restoration of damaged bone tissue. The study and summarization of current data about bone defect regeneration is the basis for the search and development of methods to improve this process. The aim of the study is to analyze and systematize the current data about reparative osteogenesis, describe the main stages and their patterns. Materials and methods. Searching the relevant sources using online scientific databases and keywords. Selection of publications for review. Further analysis and synthesis of information. The results. Despite different interpretations of the stages of reparative osteogenesis by researchers, they all describe the same coordinated process. The following key stages have been identified: haematoma formation, inflammation, MSC involvement and angiogenesis, cartilage, connective and bone tissue formation, their subsequent reorganisation, ossification and remodelling. Each of these stages involves specific cellular elements, local and general regulatory factors. The development of osteogenic cells and mechanisms of intercellular interaction, as well as the main signalling pathways and molecules (Wnt, RANK/RANKL/OPG, BMPs, HIF, etc.) that regulate osteo- and angiogenesis are described. The role of hypoxia in the process of bone regeneration and angiogenesis is highlighted. The H-type vessels and their participation in the regulation of osteogenesis are considered. Attention is paid to the phenomenon of ‘chondrocyte transdifferentiation’, which is one of the sources of osteoblasts during endochondral ossification. In the context of remodelling, the law of bone biomechanics and piezoelectric adaptive remodelling, as well as bone multicellular units as microsystems that ensure the restructuring of coarse fibrous bone tissue into lamellar bone tissue, are described. Conclusions. Reparative osteogenesis is a complicated and coordinated process at both the cellular and molecular levels. The regeneration process depends on numerous local and systemic factors and the optimization search is carried out at each stage

Применение секретома ММСК для стимуляции репаративного остеогенеза: экспериментальное исследование

The article is devoted to the study of the effect obtained by using a regenerative medicine drug (secretome of multipotent mesenchymal stromal cells) to stimulate reparative regeneration of a long tubular bone after a fracture. The presented materials are a fragment of comprehensive studies on the mechanisms of reparative regeneration of bone tissue under the conditions of the use of cellular products. The work was carried out on outbred white rats, in which the state of the bone regenerate was studied on the 30th and 120th days after injury. After the fracture, the animals were kept under normal conditions, without immobilization or restriction of motor activity. The work used methods of anatomical preparation and light microscopy. Studies have shown that the use of a secretome was accompanied by a more reliable consolidation of fragments behind the ossification of the callus, in the structure of which by the final period of the experiment lamellar bone tissue predominated, against which foci were observed reticulofibrous bone tissue and small fragments of cartilaginous tissue with signs of osteolysis and replacement with bone tissue. In the control group, the reparative process occurred more slowly, foci of cartilaginous tissue remained in the structure of the regenerate for a long time, and the bone tissue was represented mainly by reticulofibrous tissue. A significant amount of connective tissue was revealed between the fragments. All this indicates instability and unreliable consolidation of fragments. Apparently, the secretome of multipotent mesenchymal stromal cells stimulates the repair of bone tissue in fractures by improving the trophic supply in the healing area, against the background of which the formation and remodeling of callus is activated.

Reparative osteogenesis in mandible in cases of filling a bone defect with hydroxyapatite-containing osteotropic material and injecting the surrounding soft tissues with thymalin: experimental and morphological study.

Aim of the study was to identify the morphological features of reparative osteogenesis in the lower jaw bone of rats in cases of filling a bone defect with hydroxyapatite-containing osteotropic material (bone graft "Biomin GT") and injecting the surrounding soft tissues with thymalin. Materials and Methods: An experiment was conducted on 48 mature rats of the WAG population weighing 160-180 grams which were divided into four groups. Group 1 included 12 rats with a simulated holey defect in the lower jaw. Group 2 included 12 rats with a simulated holey defect in the lower jaw followed by its closure with hydroxyapatite-containing osteotropic material (bone graft "Biomin GT"). Group 3 included 12 rats with a simulated holey defect in the lower jaw with injecting the surrounding soft tissues with thymalin. Group 4 included 12 rats with a simulated holey defect in the lower jaw followed by its closure with hydroxyapatite-containing osteotropic material (bone graft "Biomin GT") and injecting the surrounding soft tissues with thymalin. The material for the morphological study was a fragment of the lower jaw from the area of the simulated holey defect. Histological, morphometric and statistical research methods were used. Results: In this study, it was shown by the authors an activation of reparative osteogenesis in the lower jaw under conditions of simultaneous filling the bone defect with hydroxyapatite-containing osteotropic material (bone graft "Biomin GT") and injection the surrounding bone defect soft tissue with thymalin. Stimulation of reparative osteogenesis in the lower jaw of rats occurred due to rapid cleaning of the bone defect cavity from necrotic tissues and hematoma fragments; a decrease in the number of neutrophil leukocytes, an increase in the number and morphofunctional state of monocytes, macrophages, lymphocytes, cells of fibroblastic differon; balanced change (increase or decrease) in the number and morphofunctional state of bone forming osteoblasts and bone resorbing osteoclasts depending on the stage of reparative osteogenesis; activation of hematopoietic processes in lamellar bone tissue from the regenerate; activation of bone tissue mineralization processes. Conclusions: Thymalin injection in the soft tissues surrounding the bone defect in the lower jaw, filled with hydroxyapatite-containing osteotropic material (bone graft "Biomin GT"), significantly stimulates the process of reparative osteogenesis, which makes it possible to recommend this technique in dentistry for treatment the patients with mandible bone tissue defects.

Prolonged hyperinsulinemia increases the production of inflammatory cytokines in equine digital lamellae but not in striated muscle

Hyperinsulinemia is the key feature of equine metabolic syndrome (EMS) which leads to debilitating sequelae. Hyperinsulinemia-associated laminitis (HAL) is one of the major sequelae of EMS, although the pathophysiological mechanisms are not well elucidated. Using an equine model, we hypothesized that expression of inflammatory markers would be increased in digital lamellae and striated muscle following prolonged hyperinsulinemia. Healthy Standardbred horses (5.4 ± 1.9 years) were alternately assigned to a prolonged euglycemic-hyperinsulinemic clamp (pEHC) or control group (n = 4 per group). Following a 48 h pEHC or a 48 h infusion of a balanced electrolyte solution (controls), biopsies were collected from digital lamellar tissue, skeletal muscle and cardiac muscle were obtained. All hyperinsulinemic horses developed laminitis regardless of previous health status at enrollment. Protein expression was quantified via Western blotting. A significant (P < 0.05) upregulation of the protein expression of heat shock protein 90 (HSP90), alpha 2 macroglobulin (A2M) and fibrinogen (α, β isoforms), as well as inflammatory cytokines including interleukin-1β were detected in digital lamellae following prolonged hyperinsulinemia. In contrast, protein expression of cytokines and acute phase proteins in heart and skeletal muscle was unchanged following hyperinsulinemia. Upregulation of inflammatory cytokines and acute phase proteins in digital lamellae during prolonged hyperinsulinemia may reveal potential biomarkers and novel therapeutic targets for equine endocrinopathic laminitis. Further, the lack of increase of inflammatory proteins and acute phase proteins in striated muscle following prolonged hyperinsulinemia may highlight potential anti-inflammatory and cardioprotective mechanisms in these insulin-sensitive tissues.

Microarchitectonics and histomorphometric parameters of bone tissue during remodeling

The article shows and statistically substantiates thepeculiarities of remodeling and structure of cortical andmedullary bone tissue in two age groups (160- and 225days) of laying hens before and during egg-laying. Theaim of the study was to analyze the structural organization of bone tissue in different states of performance.The material for the study was the ulnae of the forearmof laying hens of two experimental groups. Histological studies: fixed in a 10% solution of neutral formalin,decalcified in Wilenson's fluid, dehydrated in alcoholsof increasing concentration, embedded in paraffin, prepared transverse sections from the middle third of thediaphysis, stained by Frankel, Hart, Malory, hematoxylin and eosin. Microscopy and morphometric studies were performed using an Axiolar plus microscope(Carl Zeiss), photographs were taken and measuredusing a Sigeta MDC-200 video camera (eyepiece x10,lenses x25/0.50, x40/0.65, 100/0.25) integrated with anAxiolar plus personal computer (Carl Zeiss). Statisticalprocessing of digital material was performed by Student's t-test. Changes in the structure of cortical bonetissue during the study period are associated with physiological remodeling. This is evidenced by the presenceof cementing lines of individual osteons, semi-osteonsand Haversian canals with an enlarged diameter. Theabsence or insignificant development of the insertionsystem of the forming bone plates indicates a low rateof physiological remodeling of the compact bone substance. The external general system of plates does notchange the structure. The internal general system ofbone plates is unevenly developed. From 160 to 225days of age, the development and accumulation ofmedullary bone tissue occurs, which is confirmed bya significant increase in the area of trabeculae by 2.8times (P3 = 0.999), a complication of their structureand a decrease in the area of intertrabecular spaces by1.7 times (P2 = 0.99). A significantly higher 3.4-fold(P1 = 0.95) volume of osteoblast nuclei at 160 days indicates their active functional activity - the formationof trabeculae of medullary bone tissue. During the period of 160 days, special attention should be paid to thebalance of the diet of laying hens to ensure the formation of a sufficient amount of high-quality medullarybone tissue. Key words: lamellar bone tissue, cortical, medullary, spongy and compact substance, restructuring,histomorphometry, laying hens.

Comparative evaluation of osseointegration of new percutaneous implants made of Ti Grade 4 ultrafine‑grained alloy

Introduction It has been shown that titanium implants with a structured surface provide an increased rate of osseointegration what makes their application quite promising.The purpose of this work was to conduct a comparative evaluation of the efficiency of osseointegration of new percutaneous implants for prosthetics made of ultrafine-grained Ti Grade 4 alloy.Materials and methods The study was carried out on 12 male rabbits of the Soviet Chinchilla breed. Six rabbits of the control group had implants made of Ti6Al4V powder using selective laser sintering technology that were osseointegrated into the tibia, 6 rabbits of the experimental group had implants made of Ti Grade 4 by equal channel angular pressing. The formation of the "bone-implant" block was examined 26 weeks after the implantation.Results Histologically, after 26 weeks of the experiment, porous changes, enlargement of the Haversian canals, and pronounced osteoclastic resorption were not detected in the animals of the experimental group throughout the stump in the compact plate. Around the implant, a bony case repeating the bone shape was formed, represented by lamellar bone tissue. Using X-ray electron probe microanalysis, it was found that in the substrate formed on the surface of the implant in rabbits of the experimental group, there was significantly more calcium in all areas over the implant relative to the animals of the control group. In the control group, relative to the experimental group, an increased level of C-reactive protein in blood serum was retained longer. Complications and significant clinical and laboratory abnormalities were not found in both groups during the entire experiment.Discussion Our data are consistent with the results of other experimental studies, which unambiguously noted that titanium implants with a structured surface show increased osseointegration characteristics in comparative studies relative to implants without modification of the structure of the material of the threaded surface. The absence of complications and undesirable reactions of the animal organism also indicates the acceptable safety of the tested products.Conclusion Osseointegration of a percutaneous implant that has a mixed nanocrystalline and ultrafine-grained structure was more effective than the reference implant. This makes the use of such implant promising for solving clinical problems in prosthetics.

Origins of slow growth on the crocodilian stem lineage

Crocodilians grow slowly and have low metabolic rates similar to other living reptiles, but palaeohistology indicates that they evolved from an ancestor with higher growth rates.1,2,3,4,5 It remains unclear when slow growth appeared in the clade due to the sparse data on key divergences among early Mesozoic members of their stem lineage. We present new osteohistological data from a broad sample of early crocodylomorphs, evaluated in a phylogenetic context alongside other pseudosuchians. We find that the transition to slow-growing bone types during mid-late ontogeny occurred around the origin of Crocodylomorpha during the Late Triassic. Earlier-diverging pseudosuchians had high maximum growth rates, as indicated by the presence of woven bone during middle and (sometimes) late ontogeny.6,7,8,9 Large-bodied pseudosuchians in particular exhibit some of the fastest-growing bone types, giving evidence for prolonged, rapid growth. By contrast, early-branching crocodylomorphs, including a new large-bodied taxon, had slow maximum rates of bone deposition, as evidenced by the presence of predominantly parallel-fibered or lamellar bone tissue during middle-late ontogeny. Late Triassic crocodylomorphs show skeletal anatomy consistent with "active" terrestrial habits,10,11,12 and their slow growth rates reject hypotheses linking this transition with sedentary, semiaquatic lifestyles or sprawling posture. Faster-growing pseudosuchian lineages go extinct in the Triassic, whereas slow-growing crocodylomorphs do not. This contrasts with the Jurassic radiation of fast-growing dinosaurs on the bird-stem lineage,13 suggesting that the End-Triassic mass extinction initiated a divergent distribution of growth strategies that persist in present-day archosaurs.

Bone microstructure of bony-toothed birds (Odontopterygiformes) from the Eocene of Ikove, Ukraine: preliminary paleobiological implications

ABSTRACT Histological structure of long bones from bony-toothed birds (Odontopterygiformes) from Early Lutetian locality Ikove (Ukraine) is examined for the first time. Six limb bones from Pelagornithidae cf. Dasornis sp. and Lutetodontopteryx tethyensis are described. The bones, although usually being fragmented, show good preservation at the microscopic level. Their microstructure (e.g. orientation and diameter of primary osteons) significantly varies, but the basic pattern and, therefore, the way of growth matches that of recent Neognathae (as well as a number of extinct taxa). In young birds, the periosteum quickly deposited well-vascularised primary bone, which at the same time was resorbed from inside, then the animal reached adult size and fast bone growth gave way to much slower deposition of circumferential layers of lamellar or parallel-fibred tissue on the outer and inner bone surfaces. The bones also underwent Haversian remodelling of various extent (from nearly absent to nearly full), generally stronger in larger bones and in the inner compacta. Bone microstructure is consistent with high metabolic rates, expected in Odontopterygiformes, and implies that their growth rates were comparable to those of recent Neognathae.

Histological comparison of the lamellar tissue of Iberian origin breed horses created in semi-feral conditions or in an intensive system.

Although the external conformation of wild horse hooves has been proposed as an ideal model for domesticated modern horses, histological signs of laminitis have been reported among them. With the hypothesis that the lamellar tissue of horses of Iberian origin raised in semi-feral is healthier than those raised in an intensive management system (stall confinement and high-calorie diet intake), the objective was to compare their lamellar tissues. Lamellar tissue samples were taken from the forelimb hoof of eight domesticated Mangalarga Marchador (MM) horses and from six semi-feral Marajoara (MJ) and Puruca (MP) horses. Primary epidermal lamella (PEL) and secondary epidermal lamella (SEL) were measured (length and width) in several regions, and their shapes were morphologically classified into different types. Breed groups were compared using analysis of variance, followed by Tukey or Dunn tests (P<0.05). Early signs of laminitis such as abnormal keratinization of the abaxial primary dermal lamella, tapered tips of the axial PELs, pointed tips of the SEL, nuclei condensation, and abnormal spatial orientation of the secondary epidermal basal cells (SELBC), were seen only in MM horses. MP horses had a greater interface of epidermis/dermis contact than MJ horses and more rounded nuclei in the round SELBC than MM horses. In agreement with the study hypothesis, semi-feral MJ and MP horses' lamellae were classified as healthier than MM horses, which showed early signs of endocrinopathic laminitis.

Paleobiological implications of the bone histology of the extinct Australian marsupial Nimbadon lavarackorum

AbstractDespite the recognition that bone histology provides much information about the life history and biology of extinct animals, osteohistology of extinct marsupials is sorely lacking. We studied the bone histology of the ca. 15-million-year-old Nimbadon lavarackorum from Australia to obtain insight into its biology. The histology of thin sections of five femora and five tibiae of juveniles, subadult, and adult Nimbadon lavarackorum was studied. Growth marks in the bones suggest that N. lavarackorum took at least 7–8 years (and likely longer) to reach skeletal maturity. The predominant bone tissue during early ontogeny is parallel-fibered bone, whereas an even slower rate of bone formation is indicated by the presence of lamellar bone tissue in the periosteal parts of the compacta in older individuals. Deposition of bone was interrupted periodically by lines of arrested growth or annuli. This cyclical growth strategy indicates that growth in N. lavarackorum was affected by the prevailing environmental conditions and available resources, as well as seasonal physiological factors such as decreasing body temperatures and metabolic rates.

Porcine Cornea Storage ExVivo Model as an Alternative to Human Donor Tissues for Investigations of Endothelial Layer Preservation.

Due to the growing shortage of human corneas for research, we developed a porcine cornea storage model with qualitative features comparable to human tissues. We established a decontamination procedure for porcine eye bulbs to ensure corneal storage at 31°C to 35°C for up to 28 days without contamination. We compared human and porcine corneas under hypothermic (2-8°C) or culture (31-35°C) conditions for central corneal thickness (CCT), corneal transparency, endothelial morphology, endothelial cell density (ECD), and a novel method to quantify whole endothelial mortality. We also examined portions of lamellar tissues consisting of Descemet's membrane and endothelial cells under the microscope after Alizarin red staining. Our decontamination procedure reduced corneal contamination from 94% (control corneas without decontamination) to 18% after 28 days of storage at 31°C to 35°C. ECD, CCT, transparency, and morphology were significantly higher in porcine corneas than in human corneas at day 0. Nevertheless, the qualitative parameters of porcine and human corneas showed comparable trends under both investigated storage conditions for up to 14 days. The presented corneal storage model provides a reliable alternative to human tissues for preliminary corneal investigations. The porcine cornea storage model can be used to investigate the efficacy and safety of new media, substances, or storage conditions. Furthermore, the method developed to assess the percentage of endothelial mortality is tissue conservative and can be used in eye banks to monitor endothelial mortality during storage of tissues intended for transplantation.

Technique for the Management of Extensive Ocular Surface Lipodermoid Involving the Cornea of Children.

Ocular surface lipodermoids with corneal involvement may require surgical intervention; if deep, ocular surface reconstruction with lamellar corneal tissue or amniotic membrane may be needed. We describe a staged technique using autologous ipsilateral simple limbal epithelial transplantation. After verifying sparing of Descemet membrane, the conjunctival portion of the lipodermoid was debulked in the first stage. Six weeks later, the corneal portion was excised, followed by autologous ipsilateral simple limbal epithelial transplantation to promote rapid reepithelialization of the residual stromal bed. Temporary tarsorrhaphy was used for patient comfort and to expedite ocular surface healing. Three eyes of 3 children with grade III large ocular surface lipodermoids that encroached the visual axis and hindered proper eyelid closure underwent surgery without complications. In all cases, the visual axis was cleared and eyelid closure was improved. At the last follow-up (mean 35.7 months, median 36.0 months), the bed of the original dermoid showed minimal haze in 1 case, while 2 eyes developed small pseudopterygium; best spectacle-corrected visual acuity improved from 20/200 to 20/70 in the first case, from fix and follow to 20/50 in the second case, and remained fix and follow in the last case, but this child had congenital hydrocephalus with severe developmental delay. This surgical technique is a promising option for children with grade III large ocular surface lipodermoids given its effectiveness in clearing the visual axis and in improving eyelid closure. Moreover, it does not require lamellar corneal transplantation or intervention to the fellow eye.

EXPERIMENTAL AND MORPHOLOGICAL ASSESSMENT OF THE INFLUENCE OF HYDROXYAPATITE-CONTAINING OSTEOTROPIC MATERIAL AND ELECTRICAL STIMULATION ON REPARATIVE OSTEOGENESIS OF THE LOWER JAW.

Aim: The aim of the study was to reveal the peculiarities of reparative osteogenesis in experimental lower jaw defect under the conditions of hydroxyapatite-containing osteotropic material application and electrical stimulation. Materials and Methods: An experiment was conducted on 48 mature male rats of the WAG population. All animals were divided into 4 groups (12 animals in each group). Group 1 included rats that were not subjected to any manipulations. Group 2 included rats that were modeled with a perforated defect of the lower jaw body. Group 3 included rats that were modeled with a perforated defect similar to group 2, the cavity of which was filled with synthetic bone graft "Biomin GT" (RAPID, Ukraine). Group 4 included animals that were modeled with a perforated defect similar to groups 2-3, the cavity of which was filled with synthetic bone graft "Biomin GT". In animals of group 4, a microdevice for electrical action was implanted subcutaneously in the neck area on the side of the simulated bone defect. Morphological and statistical methods were used. Results: The research carried out by the authors proved that the use of the above-mentioned bone replacement material helps to increase the regenerative potential of the bone tissue of the lower jaw, but does not lead to the formation of a full-fledged bone regenerate, as evidenced by the results of the morphometry of the regenerate (the specific volume of lamellar bone tissue accounted for 54.9%); disordered localization of bone beams, which were characterized by reduced signs of mineralization; the presence in connective, osteogenic fibroreticular and lamellar bone tissues the encapsulated bone graft granules with the presence of inflammatory cell infiltration. In cases the combined use of synthetic bone graft "Biomin GT" and electrical stimulation, the authors noted more intensive reparative osteogenesis processes in the bone defect of the lower jaw compared to cases when only one bone graft was used, but they also did not lead to the formation of a full-fledged bone regenerate. Conclusions: The experimental and morphological study conducted by the authors proved that the use of hydroxyapatite-containing osteotropic material ("Biomin GT"), especially in cases of its combined use with electrical stimulation, significantly activates reparative osteogenesis in the bone defect of the lower jaw, which does not lead to the formation of a full-fledged bone regenerate.

Comparative postcranial osteohistology and bone histovariability of aquatic and terrestrial turtles: the case of the South American Phrynops hilarii, Hydromedusa tectifera (Pleurodira, Chelidae), and Chelonoidis chilensis (Cryptodira, Testudinidae).

This article presents a detailed comparative analysis of the bone microstructure of three extant species of South American turtles. The main histological characteristics of postcranial bones are identified, as well as the intraskeletal, ontogenetic and interspecific variation between aquatic and terrestrial species. For this purpose, thin sections of postcranial bones (seventh cervical vertebra, coracoid, scapula, humerus, radius, ulna, ischium, ilium, pubis, femur, tibia, and fibula) of juvenile and adult specimens of aquatic (Phrynops hilarii and Hydromedusa tectifera) and terrestrial (Chelonoidis chilensis) turtles were analyzed. Bone histology revealed an intraskeletal variation of the microanatomical and microstructural organization in these turtles. The cortical bone is composed of poorly vascularized lamellar and parallel-fibered bone tissue interrupted with lines of arrested growth (LAGs), reflecting a cyclical slow growth rate throughout these turtles' life. Although in the adult specimens a growth rate decrease was observed, none of them have reached somatic maturity. The juvenile and the adult of Chelonoidis chilensis, unlike the aquatic species studied, presented a higher vascularization in their bones, which could imply a faster growth rate in this land specie. The number of LAGs was higher in the stylopodial and zeugopodial bones, which would make these elements suitable for approximate age estimations. Pectoral and pelvic girdle bones also exhibited a good record of LAGs. The information here obtained on extant species represents a powerful tool for the interpretation of paleobiological traits present in closely related fossil forms.

Electroporation of embryonic chick skin explant

Since the introduction of electroporation a decade ago, the chick embryo has evolved into a powerful system for studying gene regulation and function during development. Although this is a straightforward method for embryos, skin (especially lamellar tissue) present special challenges. Here we describe a protocol for electroporation of expression vectors into the chick skin explant, with precise spatial and temporal control. We have improved the design of the electroporation chamber, which can achieve precise regulation of the electroporation area by changing the parameters of the laser cutting of the acrylic plate. We give the electroporation parameters of chicken embryo skin, which can effectively improve the electroporation efficiency. This technique can be used for time-lapse imaging and to study gene regulation in chick embryo skin.

ИЗУЧЕНИЕ ВАСКУЛЯРИЗАЦИИ И РЕПАРАТИВНОЙ РЕГЕНЕРАЦИИ ПЛАСТИНЧАТОЙ КОСТНОЙ ТКАНИ В ИСКУССТВЕННО СМОДЕЛИРОВАННЫХ ДЕФЕКТАХ ВЕРХНЕЙ ЧЕЛЮСТИ (экспериментальное исследование)

Subject. Regeneration is one of the most relevant problems of medicine and biology. As it was before and as it is now, the field of investigation, which is connected with regeneration exploring, is a range of heated debates. There is a direct correlation between regeneration of bones and local metabolism, mineralization and early vascularization, which supplies nourishment and oxygenation of cell structure of the regenerate. Owing to these factors, the bone has only its mechanic properties. This prerequisite has made a lot of investigators to pay attention for vascular-regeneration complex in zone of forming bone regenerate and its mineralization. &#x0D; Such adverse circumstances like lack of local circulation, substantial fragment diastasis, excessive instability and etc. do not generate or form delayed intermediate callus. It should be highlighted that there are significant successes in solving reparative regeneration and cortical bone vascularization problems. Nevertheless, a number of problems are not still tackled, they regard to vascularization and reparative regeneration lamellar bone tissue, particularly, middle zone of the facial bone.&#x0D; Objectives. The study on the base of the experimental researches, to explore the dynamics of reparative regeneration lamellar bone tissue with simulated different size defects of naso-frontal area of rabbit maxilla. &#x0D; Methodology. Materials of the experiment are comprised of IV series of experiments on 68 adults (from 6 months to a year), both sexes rabbits, of “Chinchilla” breed, weighing from 2.5–3.0 kg. &#x0D; All animals were kept in the vivarium of the experimental sector of&#x0D; Institute of Medical Radiology of the Academy of Medical Sciences of the USSR. The investigations included microangiographic, histological and metering quantity of vessels by laser densitometry.&#x0D; Results. It is noted that vascularization abruptly decreases in remote periods of the observation (180, 365 days) and a tendency in an amount reduction of the regenerate vessels, which the proved by histological researches results. &#x0D; Conclsion. Healing of naso-frontalis area defects with a height of 5 mm and more flows from mostly fibrocartilaginous compound, under unfavorable conditions are not restored by bone regenerate.