Purpose: to provide clinical and morphological evaluation of the corneal epithelium phenotype in total vascular leukomas of varied etiologies and determine the optimal surgical treatment using ...impression cytology (IC).
Materials and methods. 44 patients (44 eyes) with corneal vascular leukomas of various etiologies underwent optic keratoplasty preceded by IС. The patients were divided into 2 groups according to IC findings. Group 1 included 30 patients who were shown by IC to have corneal epithelium. These patients received penetrating keratoplasty (PK). Group 2 consisted of 14 patients whose epithelium was determined to be of conjunctival phenotype. Eight of group 2 patients had their corneal epithelium phenotype restored by limbal transplantation followed by PK. The remaining patients of group 2 were not operated for various reasons.
Results. In the remote postoperative period (9–12 months after the operation) corrected visual acuity of group 1 patients ranged from 0.3 to 0.6 (ave. 0.450 ± 0.073). A relapse of corneal leukoma was observed in three patients of group 1 (10%). In group 2, a transparent vascular-free engraftment of keratotransplants was observed in 5 patients after limbal transplantation (the first stage of surgical treatment) and PK, their corrected visual acuity ranged from 0.1 to 0.5 (ave 0.37 ± 0.12), 1 (20%) patient had a relapse of the leukoma. C
onclusions. Impression cytology is an acceptable and low invasive diagnostic technique that allows clinical and morphological evaluation of the epithelium phenotype that covers the vascular leukoma and helps determine validated indications for the choice of a surgical treatment technique for such patients.
Relevance
. In a number of pathological conditions accompanied by defects of the basal membrane, such as chemical or thermal burn, mechanical trauma, Schegren’s syndrome, herpetic keratitis processes ...of corneal epithelization are slowed down, and sometimes epithelization does not occur at all. Slow epithelization or its complete absence creates conditions for infection, thinning, and sometimes perforation of the cornea. That is why the problem of chronic corneal erosions is very relevant. The most perspective method of treatment is the use of autologous platelet-riched plasma (PRP). Presence of platelet growth factors, adhesive molecules and cytokines in PRP allows to use it for acceleration of regeneration of corneal defects, and the presence of live platelets allows to refer this procedure to autologous cell transplantations.
Objective
: To evaluate the clinical and morphological features of corneal epithelium regeneration in response to the application of PRP in conditions of experimental chronic corneal erosion (ECCE).
Materials and methods
. Researches were carried out on 12 rabbits of Chinchilla breed (24 eyes). At first stage the model of ECCE was reproduced for all animals: local ultraviolet (UV) irradiation with the exposure time of 45 min. on the preliminary de-epithelized corneal surface. At the second stage all animals under study were divided into three groups (4 rabbits in each group). I-st main group (MG) was instillated with PRP at a rate of 1 drop / 1 min within 10 minutes (total of 10 drops) once, in the II MG treatment was carried out according to the above method, every day for 5 days. In the control group (CG) PRP treatment was not applied.
Results
. 45-min. UV irradiation causes persistent ECCE up to 30 days of the experiment and reverts only after surface vessels are ingrowed in the affected area. Single use of PRP has insufficient therapeutic effect. Instillation within 5 days accelerates the cornea reparative regeneration in ECCE conditions. The absence of epithelial defect, newly formed vessels and corneal clouding was registered on the 9th day. Histologically, on the 30th day a normal multilayer non-squamous epithelium was found, while the stroma had an organized structure with no signs of inflammation.
Conclusions
. Therapeutic effect of PRP in ECCE conditions is based on reforming of the normal «adhesion complex» between epithelium, olfactory membrane and multifactor stimulation of reparative regeneration due to growth factors located in it, adhesive molecules and cytokines, as a result of which the typical corneal epithelium is restored.
The review is focused on the modern view of the etiology and pathogenesis of limbal stem cells deficiency. The history of development of tissue and ex-vivo transplantation of limbal epithelial stem ...cells is presented. Certain promising directions of the treatment of patients with limbal stem cells deficiency are presented.
The possibility of biodegradation of thermopolymerizable collagen gel (without cultured stem cells) in various concentrations is considered. In an experiment, an unpolymerized collagen gel was ...injected into the conjunctival cavity during preliminary blepharography. A polymerized collagen gel was obtained by incubating a thermopolymerizing collagen gel at37°C for 30 min until complete polymerization, then the gel was placed on the ocular surface and fixed by blepharography. Collagen gel biodegradation was evaluated at the 1st and 4th hours after surgery. Evaluation criteria: visually by the change in the volume of the plugged conjunctival cavity, leakage of fluid through the intershoot spaces, and also 12 hours after the operation according to the volume of collagen gel remaining in the conjunctival cavity (after removal of blepharoraphic sutures). It was revealed that biodegradation of thermally polarizable collagen gel is carried out by the mechanism of its dehydration regardless of the state of the implanted gel (unpolymerized/polymerized). The volume of the dehydrated collagen framework is directly proportional to its concentration. To increase the biodegradation time of a thermopolarizable collagen gel, it is advisable to develop a method for retaining fluid inside the collagen frame.
Introduction
. In a number of pathological conditions accompanied by the basement membrane defects, such as chemical or thermal burns, mechanical trauma, Sjögren’s syndrome, neurotrophic keratopathy ...or some corneal dystrophies, in which conditions are created independent epithelialization is weakened or becomes impossible. This condition was named recurrent corneal erosion (RCE). For the experimental study of the regenerative processes and evaluation of the effectiveness of new treatments, a standardized and reproducible RCE model is needed. Several RCE models are known: chemical, bacterial. The disadvantages of such models are the labour intensity of their implementation and a relatively high cost. The proposed method makes it possible to create the necessary conditions for local inflammation and destruction of adhesive molecules using the energy of ultraviolet (UV) irradiation. In this study, an experimental RCE model in rabbits has been proposed.
Purpose
. To create a reproducible standardized experimental model of recurrent corneal erosion.
Materials and methods
. The studies were conducted in 8 chinchilla rabbits (16 eyes). After local instillation (0.5 % alkaine solution) and retrobulbar anesthesia (2 % lidocaine solution), superficial deepithelialization of the cornea was performed by mechanical removal of its epithelium with a blunt scraper; and the quality of deepithelialization was assessed by staining the surface with 2 % fluorescein solution. In the optical zone with a diameter of 4 mm, local UV irradiation of the cornea was performed with exposures of 30 and 45 minutes.
Results
. In case of 30-minute exposures, the epithelialization of the cornea subjected only to mechanical deepithelialization was observed since Day 3 in the form of concentric epithelial growth. On Day 14, a complete epithelialization of the cornea was observed, along with the formation of superficial newly formed vessels along the limbus. On Day 24, the vascular injection significantly decreased; and no erosion was observed. After 45-minute exposure without treatment, the regeneration occurred much slower; and a complete epithelialization had been achieved by Day 34 of the experiment, by the time the newly formed vessels grew to the epithelial defect zone. It was noted that since Day 86, the turbidity in the irradiation area persisted, as well as the inflammatory infiltrate.
Conclusions
. The proposed method makes it possible to reproduce RCE, in which there is an alternation of epithelialization and deepithelialization of the irradiated corneal area through 30 days of the experiment and is arrested only after the ingrowth of surface vessels into the affected area. At that, the non-irradiated cornea is epithelialized by Day 7 of the experiment.
The «gold standard» among biological and synthetic scaffolds for cultivation is the amniotic membrane. Its preparation for the needs of tissue engineering is associated with the difficulties of ...transporting and preserving the native amniotic membrane. The amniotic membrane was taken after elective caesarean section. The separated amniotic membrane was fixed according to our method 5. Scaffolds were divided into 3 groups of 5 membranes each: storage under hypothermia, cryopreservation at –20 °C and –80 °C. Stem cells of the corneal epithelium of rabbits were used as a test system, and cells cultured under standard conditions were used as a control. Viability was determined using phase contrast microscopy and microtiter test. It has been suggested that the inhibition of the state of cells cultured on the amniotic membrane by the 14th day is associated with the viability of the own cells of the amniotic membrane. To verify this assumption, a microtiter test was carried out for all scaffold groups. The described method of immobilization of the amniotic membrane provides transportation, preservation and the possibility of culturing stem cells on the amniotic membrane. For the cultivation of stem cells during the first day, all three types of preservation of the amniotic membrane are suitable. In order to create bioengineered structures for restoration of the corneal epithelium, further research is needed to find the optimal way to de-epithelialize the amniotic membrane.
Impression cytology (from the Latin impressio — impact, indentation) is a minimally invasive method of cytological examination of the surface epithelium of the cornea, limbus and conjunctiva using ...various sorbing applicators for the collection of cellular material. The spectrum of diseases, in the diagnosis of which impression cytology is traditionally used, is mainly associated with pathological processes occurring in the conjunctiva. Such diseases as: Sjogren’s syndrome, dry eye syndrome, mucopolysaccharidosis, vitamin A deficiency, trachoma, squamous cell neoplasia of the ocular surface, etc. With the advent of the concept of limbal epithelial stem cell, new diagnostic possibilities of impression cytology in ophthalmology occurred.
The results of the long-term recording of thermal neutron flux near the Earth’s surface with the use of an unshielded scintillation thermal-neutron detector are presented. The data obtained indicate ...the presence of periodic variations in the thermal neutron flux with the lunar diurnal and the lunar monthly periods. A hypothesis about the existence in the Earth’s crust of radon-neutron tidal variations in the concentration of thermal neutrons, correlated with the Moon’s phases and which have the gravitational origin, is formulated and confirmed experimentally. A simple mathematical model is proposed, which satisfactorily describes the observed variations. The case of the anomalous behavior of thermal neutrons is presented, which correlates with the high local seismic activity.
The manifestations of dysbiotic syndrome were monitored in the setting of chronically inflammatory diseases among women and men of different ages. Significant imbalances were found in the direction ...of reducing the titers of symbionts lactobacilli to 105 -0 CFU, bifidobacteria 108 -107 , enterococci 105 , typical Escherichia 106 -103 and increasing the number of representatives of opportunistic enterobacteria to 108 -105 CFU, staphylococci 106 -104 and fungi of the genus Candida 106 -103 . A more significant manifestation of intestinal inflammation of the intestine in terms of fecal calprotectin in men compared with women was shown. In males of patients with nonspecific ulcerative colitis, the level of imbalance of intestinal microbiocenosis was more pronounced in contrast to females. The number of cases when there was a decrease in the number of the main representatives of normal flora exceeded in the male group than in the female group by an average of 12.5%. Also, the identification of opportunistic pathogenic microflora and fungi of the genus Candida in the titer of higher reference indicators was observed more often in men by an average of 7.8%. However, in Crohns disease, the frequency of registration of deviations in the titers of individual microbiota varied among women and men. The high incidence of chronic inflammatory bowel disease with the corresponding dysbiotic disorders was recorded in the group of people aged 20 to 44 years. All patients, regardless of their age, showed a significant decrease in lactobacillus titers. The number of cases when a decrease in the number of bifidobacteria was recorded, enterococci relative to the norm, exceeded among young people and was 41.4% and 27.6%, respectively. At the same time, the quantitative indices of colonization of opportunistic microorganisms of the digestive tract were higher in the elderly. The frequency of detection of yeast-like fungi of the genus Candida was at a high level in all the examined age groups and was 42.8% 44.9%. It can be concluded that intestinal lesions caused by pathologies of nonspecific ulcerative colitis and Crohns disease play a leading role in the development of dysbacteriosis. The data obtained are the basis for studying the relationship between the depth of the pathogenesis of these diseases and the duration of dysbiotic disorders.
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