Dynamic viscosity of the wall of the lacrimal sac in disorders of the patency of the lacrimal ducts

PURPOSE

To assess the dynamic viscosity of the lacrimal sac wall in patients with various origins of lacrimal duct obstruction.

METHODS

The study was performed in 35 cases: 21 cases with primary nasolacrimal duct obstruction (PANDO) and 14 cases with secondary nasolacrimal duct obstruction after radioiodine therapy (SALDO). The study of biomechanical properties of the lacrimal sac was carried out using a test bench. The principle of the study was to indent the sample at a given speed and record the data obtained from the sensor of the force transmitted to the sample. The area under the curve (AUC) and the peak viscosity were calculated. A qualitative characteristic of the obtained curve was given.

RESULTS

Median AUC in patients with PANDO was 17 × 106 [6 × 106; 19 × 106] N/m2 × s, in patients with SALDO 21 × 106 [13 × 106; 25 × 106] N/m2 × s. Intergroup differences were statistically significant (p = 0,048). The median peak viscosity in PANDO patients was 29 × 106 [25 × 106; 35 × 106] N/m2, in patients with SALDO 32 × 106 [21 × 106; 41 × 106] N/m2. The qualitative characteristics of the obtained curves differed.

CONCLUSION

Biomechanical properties of the lacrimal sac may vary depending on the cause of obliteration of the lacrimal ducts. The integrated dynamic viscosity is significantly higher in SALDO patients due to exposure to radioiodine compared to that in PANDO patients.

Mixed insect pest populations of Diaspididae species under control of oligonucleotide insecticides: 3'-end nucleotide matters

Diaspididae are one of the most serious small herbivorous insects with piercing-sucking mouth parts and are major economic pests as they attack and destroy perennial ornamentals and food crops. Chemical control is the primary management approach for armored scale infestation. However, chemical insecticides do not possess selectivity in action and not always effective enough for the control of armored scale insects. Our previous work showed that green oligonucleotide insecticides (olinscides) are highly effective against armored and soft scale insects. Moreover, olinscides possess affordability, selectivity in action, fast biodegradability, and a low carbon footprint. Insect pest populations undergo microevolution and olinscides should take into account the problem of insecticide resistance. Using sequencing results, it was found that in the mixed populations of insect pests Dynaspidiotus britannicus Newstead and Aonidia lauri Bouche, predominates the population of A. lauri. Individuals of A. lauri comprised for 80% of individuals with the sequence 3'-ATC-GTT-GGC-AT-5' in the 28S rRNA site, and 20% of the population comprised D. britannicus individuals with the sequence 3'-ATC-GTC-GGT-AT-5'. We created olinscides Diasp80-11 (5'-ATG-CCA-ACG-AT-3') and Diasp20-11 (5'-ATA-CCG-ACG-AT-3') with perfect complementarity to each of the sequences. Mortality of insects on the 14th day comprised 98.19 ± 3.12% in Diasp80-11 group, 64.66 ± 0.67% in Diasp20-11 group (p < 0.05), and 3.77 ± 0.94% in the control group. Results indicate that for maximum insecticidal effect it is necessary to use an oligonucleotide insecticide that corresponds to the dominant species. Mortality in Diasp80-11 group was accompanied with significant decrease in target 28S rRNA concentration and was 8.44 ± 0.14 and 1.72 ± 0.36 times lower in comparison with control (p < 0.05) on the 10th and 14th days, respectively. We decided to make single nucleotide substitutions in Diasp20-11 olinscide to understand which nucleotide will play the most important role in insecticidal effect. We created three sequences with single nucleotide transversion substitutions at the 5'-end - Diasp20(5')-11 (A to T), 3'-end - Diasp20(3')-11 (T to A), and in the middle of the sequence - Diasp20(6)-11 (6th nitrogenous base of the sequence; G to C), respectively. As a result, mortality of mixed population of the field experiment decreased and comprised 53.89 ± 7.25% in Diasp20(5')-11 group, 40.68 ± 4.33% in Diasp20(6)-11 group, 35.74 ± 5.51% in Diasp20(3')-11 group, and 3.77 ± 0.94% in the control group on the 14th day. Thus, complementarity of the 3'-end nucleotide to target 28S rRNA was the most important for pronounced insecticidal effect (significance of complementarity of nucleotides for insecticidal effect: 5' nt < 6 nt < 3' nt). As was found in our previous research works, the most important rule to obtain maximum insecticidal effect is complete complementarity to the target rRNA sequence and maximum coverage of target sequence in insect pest populations. However, in this article we also show that the complementarity of 3'-end is a second important factor for insecticidal potential of olinscides. Also in this article we propose 2-step DNA containment mechanism of action of olinscides, recruiting RNase H. The data obtained indicate the selectivity of olinscides and at the same time provide a simple and flexible platform for the creation of effective plant protection products, based on antisense DNA oligonucleotides.

Perfect Complementarity Mechanism for Aphid Control: Oligonucleotide Insecticide Macsan-11 Selectively Causes High Mortality Rate for Macrosiphoniella sanborni Gillette

Macrosiphoniella sanborni is a widespread pest of Chrysanthemum morifolium that causes significant damage to world floriculture. Chemical insecticides and biological methods of control have a number of disadvantages that can be improved by using oligonucleotide insecticides. In this article, we present, for the first time, the results of using oligonucleotide insecticides, for which the target sequence is an internal transcribed spacer (ITS) in a polycistronic rRNA transcript. The mortality of wingless aphid individuals after a Macsan-11 treatment was recorded at a level of 67.15 ± 3.32% 7 days after a single treatment with a solution at a concentration of 100 ng/μL and 97.38 ± 2.49% 7 days after a double treatment with a solution of the same concentration and a daily interval. The contact use of the control oligonucleotide (ACTG)₂ACT-11. as well as the oligonucleotide insecticides Macsan-11(3') and Macsan-11(5') was not accompanied by insect mortality. Given the high variability in the internal transcribed spacer, which has proven to be a promising target for the action of oligonucleotide insecticides, it is possible to create selective preparations. This study showed the prospects of ribosomal insect pest genes as targets for the action of olinscides, and also demonstrated the high specificity of such insecticidal agents.

Icerya purchasi Maskell (Hemiptera: Monophlebidae) Control Using Low Carbon Footprint Oligonucleotide Insecticides

Climate change creates favourable conditions for the growth of insect populations. Today, the world is seeing an increase in the number of insect pest infestations associated with a long-term increase in the average temperature of climatic systems. For example, local invasions of Icerya purchasi Maskell, a citrus pest recognized worldwide, have increased in size and number in recent years. Controlling this pest is complicated because not all chemical insecticides are effective, and their use is undesirable since citrus fruit is used for food and chemical agents cumulatively harm human health. In this article, we demonstrated for the first time the successful use of a short single-stranded fragment of the 28S ribosomal RNA gene called "oligoICER-11" to control cottony cushion scale, and we propose the use of green oligonucleotide insecticides with a low carbon footprint for large-scale implementation in agriculture and forestry. Using the contact oligonucleotide insecticide oligoICER-11 at a concentration of 100 ng/μL on I. purchasi larvae resulted in a mortality of 70.55 ± 0.77% within 10 days. Thus, climate change is driving the need in both agriculture and forestry for oligonucleotide insecticides (DNA insecticides, olinscides): safe, effective, affordable insecticides with a low carbon footprint and long operational life.

Four Most Pathogenic Superfamilies of Insect Pests of Suborder Sternorrhyncha: Invisible Superplunderers of Plant Vitality

Sternorrhyncha representatives are serious pests of agriculture and forestry all over the world, primarily causing damage to woody plants. Sternorrhyncha members are vectors for the transfer of a large number of viral diseases, and subsequently, the host plant weakens. Additionally, many are inherent in the release of honeydew, on which fungal diseases develop. Today, an innovative approach is needed to create new and effective ways to control the number of these insects based on environmentally friendly insecticides. Of particular relevance to such developments is the need to take into account the large number of organisms living together with insect pests in this group, including beneficial insects. Practically without changing their location on their host plant, they adopted to be more invisible and protected due to their small size, symbiosis with ants, the ability to camouflage with a leaf, and moderately deplete plants and others, rarely leading them to death but still causing substantial economic loss in the subtropics and tropics. Due to the lack of presence in the literature, this review fills in this pesky spot by examining (on the example of distinct species from four superfamilies) the characteristic adaptations for this suborder and the chemical methods of combating these insects that allow them to survive in various environmental conditions, suggesting new and highly promising ways of using olinscides for plant protection against Sternorrhyncha members.

Inhibitory Effect of Phosphorothioate Oligonucleotide Complementary to G6PD mRNA on Murine Melanoma

In terms of the incidence among all tumors, skin cancer is on top, with the most deadly among them being melanoma. The search for new therapeutic agents to combat melanoma is very relevant. In our opinion, antisense oligonucleotides (ASO) aimed at suppressing the genes responsible for their viability in cancer cells give hope for treatment, which makes it possible to eliminate cancer cells near the tumor site both before and after surgery. In this article, we describe how Skeen-11 phosphorothioate oligonucleotide significantly decreased the proliferative activity of murine melanoma cells. Injections of Skeen-11 also inhibited tumor growth in mice with inoculated melanoma. A toxicity study showed no side effects with dose adjustments. The results show that the use of ASO Skeen-11 in vivo reduced the tumor size within 7 days, reduced the number of mitoses in the tumor cells, and increased the amount of necrosis compared with the control group.

[Age prediction based on the examination of bone tissue elemental composition using energy dispersive X-Ray spectroscopy]

THE AIM OF THE STUDY

Was to assess the possibility of using chemical analysis of bone mineral content by the means of an energy dispersive X-Ray spectroscopy to determine the age of unidentified corpses for forensic identification. A semi-quantative chemical microanalysis of bone fragments of 85 male and female corpses aged between 21 and 91 was done through the use of energy dispersive X-Ray spectrometer. The association of bone tissue apatite mineral composition with age is confirmed and a formula, connecting age and chemical composition change, is proposed. The possibility of using quantitive evaluation of chemical elements content in the normative mineral to determine the unidentified corpse's age in a standard laboratory, equipped with an energy dispersive X-Ray spectrometer, was proved.

[Express-diagnosis of the diseases of the eye and its appendages by scanning electron microscopy with supravital staining]

This review describes the history of development of a new line of chemical reagents that prompts to significantly reevaluate the application of scanning electron microscopy (SEM) in medical and biological studies, particularly in ophthalmology; considers the establishing of SEM as an analytical method; covers the problems in its application associated with the needs of clinical medicine and the complexities of biological sample preparation for electron microscopy. The article also presents in chronological order the technical solutions associated with creating a unique line of reagents for supravital staining. The multitude of technical solutions allows considering SEM as a method of express diagnostics. The review discusses examples of practical application of these methods for solving certain cases in clinical ophthalmology. The niche of SEM is considered among other methods of clinical diagnostics, as well as its future development involving the use of artificial intelligence.

[Features of accumulation of chemical elements in the volume of the lens in senile cataract]

PURPOSE

This study provides a detailed analysis of the bioinorganic chemical composition of lens substance in patients with senile cataract using classical and spatial statistics methods.

MATERIAL AND METHODS

The study included 30 isolated human lenses. The light scattering ability (LSA) of the lens substance was evaluated using an original method. Additionally, distribution of chemical elements in the lens substance was analyzed using a scanning electron microscope with energy dispersive spectrometer (SEM/EDS). Measurements by all methods were carried out in a single coordinate space, which made it possible to compare the spatial correlation of different parameters.

RESULTS

Small-angle light scattering of the lens substance has been quantitatively characterized for the first time. In contrast to the conventional norm, in senile cataract the accumulation fields of the majority of ion-forming elements (including Na, P, K, Cl) are distributed along the lines repeating the geometry of the lens capsule. At the same time, the light scattering ability of certain areas of the lens is significantly correlated with changes in the concentrations of Na, P, K, Ca in these areas. In particular, one ion-forming element can be distinguished - Na: spatial change of its concentration in senile cataract is strongly associated with a local change in LSA of the lens with opacities clustering of any degree. Thus, a change in the nature of the Na accumulation in the lens volume can be considered the main marker of senile cataract formation.

CONCLUSION

The distribution pattern of ion-forming elements indicates that the loss of barrier properties in the capsule plays a significant role in the development of senile cataract.

[Morphological evaluation of the results of laser activation of scleral hydropermeability in the treatment of glaucoma]

PURPOSE

The study attempted to experimentally substantiate the possibility of using the laser activation of scleral hydropermeability (LASH) technique in glaucoma treatment by morphological evaluation of treatment outcomes.

MATERIAL AND METHODS

The pulsed-periodic radiation from an Er-glass fiber laser (λ=1.56 μm) was used. The model experiment consisted of evaluating ultrafiltration of fluid through the tissues of human sclera autopsy specimen according to the original technique using neodymium chloride-based labeling agent and scanning electron microscopy. The clinical part of the study consisted of optical coherence tomography (OCT) and laser confocal microscopy of the sclera and conjunctiva (CMSC) performed in vivo immediately after laser treatment in the laser application sites in 5 patients (5 eyes) aged 57 to 68 years with uncompensated advanced (IIIb-c) stage of glaucoma who had previously underwent LASH surgery.

RESULTS

Results of morphological evaluation after LASH revealed structural changes indicating increased transscleral ultrafiltration: increased intrastromal hyporeflective areas in the sclera, thinning of collagen fibers, formation of porous structures. Using an original technique involving neodymium chloride-based labeling agent and scanning electron microscopy, we were able to prove the enhancement of transscleral ultrafiltration. The results of the experiment were confirmed by in vivo OCT images of the sclera and CMSC performed in 5 patients with advanced glaucoma after LASH surgery, in which tissue decompaction in the laser-exposed areas was clearly visualized.

CONCLUSION

The revealed structural changes indicate the possibility of reducing intraocular pressure after LASH by the means of forming scleral porous structures and increasing transscleral ultrafiltration. Experimentally selected optimal mode of laser exposure (0.66 W with total exposure time of 6 seconds) during LASH helps avoid gross destructive changes in the eye tissues, making the proposed intervention a sparing approach to the treatment of glaucoma.

[The effect of keratoconus-associated refractive errors on the results of tomographic methods of studying the posterior structures of the eye]

PURPOSE

The study assesses the potential influence of refractive errors in keratoconus (KC) on the results of tomographic methods of studying the structures of the posterior eye segment.

MATERIAL AND METHODS

The study included 30 patients with bilateral stabilized KC of stages I-IV in classification by M. Amsler. Spherical and cylindrical components of refractions were determined using automatic refractometry, keratometry measurements - based on scanning keratotopography with Scheimpflug analyzer. Aberrometry was performed to evaluate corneal wave front according to the following parameters: root mean square for lower order aberrations (RMS LOA), root mean square for higher order aberrations (RMS HOA), vertical trefoil, vertical coma, horizontal coma and spherical aberrations. Optical coherence tomography (OCT) and laser confocal scanning ophthalmoscopy (HRT 3) data was used in morphometric analysis of the optic nerve head and peripapillary retina. The following morphometric parameters were analyzed: optic nerve head (ONH) area, optic disc cup area, optic disc cup volume, ratio of optic disc cup area to ONH area, neuroretinal rim area, neuroretinal rim volume, peripapillary retinal nerve fiber layer (RNFL) thickness. All studies were performed first without correction, and 30 minutes after installing customized scleral hard contact lenses (SHCL).

RESULTS

Compensation of the refractive errors characteristic for KC was achieved as expected with contact correction. OCT revealed a general trend for reduction in the area and volume of the optic disc cupping, ratio of area to volume of the optic disc cupping, as well as an increase in other parameters. As such, with correction the values for area and volume of the neuroretinal rim according to OCT were 2.2 and 13%, HRT 3 - 18 and 51.6%; comparable increase in mean RNFL thickness - 2.8 and 28.5%, respectively (p<0.001). According to HRT 3 data, the area and volume of optic disc cupping statistically significantly decreased (by 21 and 28%, respectively), while OCT showed statistically significant decrease only in cupping area (by 5.7%). The ratio of cupping to ONH area decreased by 6.6 and 23% relative to the initial data obtained with OCT and HRT 3, respectively. Significant decrease in ONH area amid SHCL correction was observed only with HRT 3. The revealed changes in morphometric parameters were analyzed using the fundamental principles of physiological optics. Changes in interference pattern and, consequently, morphometric parameters of structures of the eye fundus in KC are of multifactorial nature, and are mostly associated with refractive and wave artefacts occurring when the rays pass through the irregular corneal surface and cannot be optically compensated by the device. The use of SHCL as means for making the optic system relatively regular can significantly decrease the artefacts in morphometric measurements.

CONCLUSION

The results obtained in this study demonstrate the practicality of tomographic examination in KC with contact correction. The optimal choice is custom-fit SHCL, which along with proper correction of refractive errors also ensures stable position of the lens on the cornea. In standard examination specialists should take into account the «false» decrease in parameters of the peripapillary retinal nerve fiber layer and increase in ONH cupping.

Oligonucleotide Insecticides for Green Agriculture: Regulatory Role of Contact DNA in Plant-Insect Interactions

Insects vastly outnumber us in terms of species and total biomass, and are among the most efficient and voracious consumers of plants on the planet. As a result, to preserve crops, one of the primary tasks in agriculture has always been the need to control and reduce the number of insect pests. The current use of chemical insecticides leads to the accumulation of xenobiotics in ecosystems and a decreased number of species in those ecosystems, including insects. Sustainable development of human society is impossible without useful insects, so the control of insect pests must be effective and selective at the same time. In this article, we show for the first time a natural way to regulate the number of insect pests based on the use of extracellular double-stranded DNA secreted by the plant Pittosporum tobira. Using a principle similar to one found in nature, we show that the topical application of artificially synthesized short antisense oligonucleotide insecticides (olinscides, DNA insecticides) is an effective and selective way to control the insect Coccus hesperidum. Using contact oligonucleotide insecticide Coccus-11 at a concentration of 100 ng/μL on C. hesperidum larvae resulted in a mortality of 95.59 ± 1.63% within 12 days. Green oligonucleotide insecticides, created by nature and later discovered by humans, demonstrate a new method to control insect pests that is beneficial and safe for macromolecular insect pest management.

Age-related changes in cationic compositions of human cranial base bone apatite measured by X-ray energy dispersive spectroscopy (EDS) coupled with scanning electron microscope (SEM)

One of the most common scientific methods to study the chemical composition of bone matter is energy-dispersive X-ray spectroscopy (EDS). However, interpretation of the data obtained can be quite complicated and require a thorough understanding of bone structure. This is especially important when evaluating subtle changes of chemical composition, including the age-related ones. The aim of current study is to create a method of processing the obtained data that can be utilized in clinical medicine and use it to evaluate the age evolution of bone chemical composition. To achieve this goal, an elemental composition of 62 samples of cadaver compact bone, taken from the skull base (age: Me = 57.5; 21/91(min/max); Q1 = 39.5, Q3 = 73.75), was studied with EDS. We used the original method to estimate the amount of Mg²⁺ cations. We detected and confirmed an increase of Mg²⁺ cation formula amount in the bone apatite, which characterizes age-related resorption rate. Analysis of cation estimated ratio in a normative bone hydroxylapatite showed an increase of Mg²⁺ amount (R = 0.43, p = 0.0005). Also, Ca weight fraction was shown to decrease with age (R = - 0.43, p = 0.0005), which in turn confirmed the age-dependent bone decalcification. In addition, electron probe microanalysis (EPMA) and X-ray diffraction analysis (XRD) were performed. EDS data confirmed the EPMA results (R = 0.76, p = 0.001). In conclusion, the proposed method can be used in forensic medicine and provide additional data to the known trends of decalcification and change of density and crystallinity of mineral bone matter.

[Potential risk factors of atrial fibrillation recurrence after cryoballoon ablation]

Aim      To identify risk factors for recurrence of atrial fibrillation (AF) following cryoballoon ablation (CBA).Material and methods  This prospective study included patients with paroxysmal AF who had undergone CBA (141 patients, median age 60 years, 3% men). The evaluation prior to CBA included clinical instrumental parameters (electrocardiography (ECG), 24-h ECG monitoring, echocardiography, contrast-enhanced cardiac multispiral computed tomography). Also, possible intraoperative indexes that could affect the CBA effectivity, were evaluated. The postoperative follow-up duration was 12 months. Effectivity was assessed during in-person visits at 3, 6, and 12 months, when questioning of patients and 24-h ECG monitoring were performed. CBA was considered ineffective if the patient had recurrences of any atrial tachyarrhythmia longer than 30 sec after the end of the 3-month "blind" period.Results During the 12-month follow-up, recurrences of atrial tachyarrhythmia were observed in 46 (32.6 %) patients. Patients with ineffective CBA more frequently had AF during the first 3 months (71.7 % vs. 11.6 %; р&lt;0.001). Such patients had a history of multiple ineffective treatments with antiarrhythmic drugs (AAD), common pulmonary venous (PV) collector (41.3 % vs. 20.0 %; р=0.008), and stroke/recurrent ischemic attacks (15.2 % vs. 5.2 %; р=0.047). Multifactorial regression analysis showed that the factors of AF recurrence included common PV collector (relative risk (RR) 2.35; 95 % confidence interval (CI) 1.29-4.25; р=0.005), multiple ineffective AADs (RR 1.42; 95 % CI 1.08-1.86; р=0.011), and early AF recurrence (RR 7.57; 95 % CI 3.84-14.90; р&lt;0.001).Conclusion      Common PV collector and multiple ineffective AADs are risk factors of ineffective CBA. Early recurrences during the first 3 postoperative months are a significant risk factor of long-term AF recurrences.

Anti-coronavirus vaccines will not accelerate the transition of humanity to a non-pandemic period, but the pandemic will take fewer victims

The vaccination rate worldwide has reached enormous proportions, and it is likely that at least 75% of the world's population will be vaccinated. The controversy is that, while people aged 65 and older suffer a significantly higher mortality rate from COVID-19, plans are being made to vaccinate young people under the age of 20. Equally thorny is the question of vaccinating people who already have antibodies to SARS-CoV-2, as well as B and T memory cells, because they contracted and survived the virus. The possible consequences of large-scale vaccination are difficult to predict, when some people do not have access to the vaccine at all and others have already received 3 doses of the vaccine. SARS-CoV-2 will circulate through the human population forever and continue to mutate, as viruses do. Therefore, in the coming years, the need to develop and use effective vaccines and medicines for the prevention and treatment of COVID-19 will remain urgent in view of the high mortality rate from this disease. To date, three vaccine platforms have been most used: adenoviral vector, inactivated, and mRNA. There is some concern about the side effects that occur after vaccination. Whether modern anti-coronavirus vaccines can raise the safety threshold, only time will answer. It is obvious that the pandemic will end, but the virus will remain in the human population, leaving behind invaluable experience and tens of millions of victims. This article is based on search retrieves in research articles devoted to COVID-19 mainly published in 2020-2021 and examines the possible consequences of the worldwide vaccination against SARS-CoV-2 and suggests that, while anti-coronavirus vaccines will not magically transport humanity to a non-pandemic world, they may greatly reduce the number of victims of the pandemic and help us learn how to live with COVID-19.

Post-genomic platform for development of oligonucleotide vaccines against RNA viruses: diamond cuts diamond

The coronavirus pandemic has starkly demonstrated the need to create highly effective vaccines against various viral diseases. The emerging new platforms for vaccine creation (adenovirus vectors and mRNA vaccines) have shown their worth in the fight against the prevention of coronavirus infection. However, adenovirus vectors and mRNA vaccines have a serious disadvantage: as a rule, only the S protein of the coronavirus is presented as an antigen. This tactic for preventing infection allows the ever-mutating virus to escape quickly from the immunity protection provided by such vaccines. Today, viral genomic databases are well-developed, which makes it possible to create new vaccines on a fundamentally new post-genomic platform. In addition, the technology for the synthesis of nucleic acids is currently experiencing an upsurge in demand in various fields of molecular biology. The accumulated experience suggests that the unique genomic sequences of viruses can act as antigens that trigger powerful humoral and cellular immunity. To achieve this effect, the following conditions must be created: the structure of the nucleic acid must be single-stranded, have a permanent 3D nanostructure, and have a unique sequence absent in the vaccinated organism. Oligonucleotide vaccines are able to resist the rapidly changing genomic sequences of RNA viruses by using conserved regions of their genomes to generate a long-term immune response, acting according to the adage that a diamond cuts a diamond. In addition, oligonucleotide vaccines will not contribute to antibody-dependent enhanced infection, since the nucleic acid of the coronavirus is inside the viral particle. It is obvious that new epidemics and pandemics caused by RNA viruses will continue to arise periodically in the human population. The creation of new, safe, and effective platforms for the production of vaccines that can flexibly change and adapt to new subtypes of viruses is very urgent and at this moment should be considered as a strategically necessary task.

[Prospects for early detection of keratoconus based on systems built for computer-assisted diagnostics of structural changes in the cornea]

The article is devoted to the problem of diagnosing subclinical keratoconus (KK). The need to identify early signs of KK is primarily associated with the potential for the development of iatrogenic keratoectasia in cases of underdiagnosis of the disease when determining the conditions for laser keratorefractive surgery involving a decrease in the thickness of the cornea. Today generally accepted algorithms for early computer-assisted diagnosis of KK are mainly based on the analysis of various morphometric parameters of the cornea, reflecting changes in its shape and thickness induced by structural abnormalities. Direct detection of structural changes in the cornea characteristic of early KK requires the use of high-tech imaging methods that are not always applicable in everyday clinical practice. The promising approach proposed in this study is based on the fact that a digital image of a corneal «slice» obtained using serial analyzers such as the Scheimpflug camera widely used in clinical practice provides indirect information about the structure of the epithelial layer, the local thickening of which takes place in the initial stages KK. It is this criterion that underlies the proposed system of computer-assisted diagnosis of KK. The carried out studies have shown the high sensitivity of this algorithm, and its specificity can be increased by involving the known diagnostic indicators of KK.

[Visualization of normal ocular surface microflora via impression cytology sample using scanning electron microscopy with lanthanide contrasting]

PURPOSE

To determine the possibilities of impression cytology (IC) with subsequent visualization of the sample on a scanning electron microscope in assessment of normal microflora of the ocular surface.

MATERIALS AND METHODS

The article presents a visual characteristic of the microorganisms of the ocular surface (OS) captured during impression cytology (IC) in individuals without signs of inflammatory and degenerative eye diseases. The original method of staining the sample with heavy metal salts made it possible to identify the individual signs of the microorganisms in their subsequent visualization by scanning electron microscopy (SEM).

RESULTS

The paper presents photomicrographs of the microorganisms most common for the OS obtained with the help of SEM, confirming and supplementing the data of non-visual methods of studying the ocular microflora. It was shown that the detection frequency of the microbial component of the OS by the visual method presented in this study is comparable with the detection frequency when using the microbial cultivation method (<80%). Coccoid and rod-shaped microorganisms were detected with relatively equal frequency, with the coccoid organisms mainly represented in association with epithelial cells. The morphological diversity of rod-shaped microorganisms is shown.

CONCLUSION

The results of the study can be used as a visual reference for the normal microbiome of the eye.

[Optical properties of the cornea after different modifications of penetrating keratoplasty]

PURPOSE

Comparative analysis of optical properties of the cornea after different modifications of penetrating keratoplasty.

MATERIAL AND METHODS

The study included 56 patients (56 eyes) divided into three study groups according to the surgery technique. Group I included 17 patients (17 eyes) after one-piece mushroom keratoplasty, group II - 21 patients (21 eyes) after two-piece mushroom keratoplasty and group III - 18 patients (18 eyes) after penetrating keratoplasty. In addition to standard examination methods, before surgery and in the course of the follow-up all patients underwent software-powered corneal densitometry on the anterior segment analyzer (Pentacam HR, "Oculus", Germany), as well as an assessment of the degree and regularity of postoperative astigmatism.

RESULTS

Comparison of the obtained results revealed with a high degree of confidence higher values of the total specific light scattering after two-piece mushroom keratoplasty throughout the entire observation period (p<0.05). At the same time, there was no statistically significant difference in visual acuity between the three study groups (p>0.05). A statistically significant increase in the level of induced astigmatism was revealed after penetrating keratoplasty.

CONCLUSION

The observed increase in light scattering after two-piece mushroom keratoplasty does not lead to a decrease in visual acuity. The interface in the optical zone of the cornea formed by a microkeratome does not affect the degree and regularity of induced astigmatism.

[Effectiveness of anti-VEGF therapy for neovascular age-related macular degeneration in different types of exudative fluid localization]

PURPOSE

To assess the effectiveness of anti-VEGF therapy in different types of fluids localization in neovascular age-related macular degeneration (AMD).

MATERIAL AND METHODS

The study included 16 people (16 eyes) with exudative AMD. The study included patients with fibrovascular detachment of the retinal pigment epithelium (RPE), subretinal and intraretinal fluid. The patients were divided into two groups: in the first group, fibrovascular RPE detachment was combined with subretinal fluid (9 eyes); in the second group, fibrovascular RPE detachment was accompanied by both sub- and intraretinal fluid (7 eyes). All patients underwent standard ophthalmological examination, which included visometry, biomicroscopy, and ophthalmoscopy under conditions of drug-induced mydriasis. Additionally, OCT of the macular region and OCT-angiography were performed.

RESULTS

Over the entire observation period, the first group of patients received an average of 5.11 intravitreal injections (IVI), the second group - 5.14 IVI. Visual acuity was comparable in both groups at the beginning of the study. Subsequently, the treatment resulted in an increase in visual acuity after 3 months in the first (p=0.066) and second (p=0.043) groups, as well as after 12 months in both groups (p=0.043). In the first group of patients, after 12 months, an increase in RPE detachment was observed (p=0.942), which suggests that the disease activity remains underestimated on OCT when RPE detachment and subretinal fluid are combined. In the first group, complete resorption of subretinal fluid occurred in 2 people. In the second group, resorption of subretinal and intraretinal fluid occurred in 6 people.

CONCLUSION

Regardless of the subtype of fluid, anti-VEGF therapy is an effective method for treating exudative AMD. Intravitreal injections are necessary both in the presence of intra- and/or subretinal fluid, and fluid under RPE. The greatest difficulty is assessment of the fluid under the RPE.

[Scanning electron microscopy results of the vitreous body in asteroid hyalosis]

PURPOSE

To evaluate the structure of vitreous body in asteroid hyalosis by low vacuum scanning electron microscopy.

MATERIAL AND METHODS

The material of the study was samples of the vitreous body obtained from 7 patients aged from 62 to 72 years with vitreomacular traction syndrome during vitrectomy. In all cases, clinical manifestations of asteroid hyalosis (the presence of multiple point-like echo-positive inclusions) were identified during the preoperative examination. Samples for scanning electron microscopy and chemical microanalysis were prepared without using fixation elements, total dehydration, staining or centrifugation, and according to the so-called principle of bougienage, which consists in partial separation of fractions of the gel-like tissue with a stream of saline.

RESULTS

The conducted examinations made it possible to identify various types of local accumulations of mineral elements in the vitreous body in asteroid hyalosis - called asteroid bodies - that is, multiple complex rounded formations consisting of needle-shaped crystals of a radial fibrous structure.

CONCLUSION

The developed algorithm, which includes intraoperative sampling of the vitreous body in conditions of its minimal hydration and a special technique for preparing samples for scanning electron microscopy and chemical microanalysis, provides the capability for the in vivo assessment of morphological changes in hyaloid elements of the vitreous body. With that, asteroid bodies can be considered as markers of the vitreous structures that are difficult to visualize.

[Assessment of age-related changes in lens capsule biomechanics using atomic force microscopy]

Studies devoted to the assessment of lens capsule biomechanics can be divided into fundamental and applied. The former are oriented towards analysis of various indicators characterizing elasticity of the capsule as a basal membrane that maintains and changes the shape of the lens, and the latter deal with widespread introduction of modern microinvasive methods of phaco surgery into clinical practice.

PURPOSE

To assess age-related changes in lens capsule biomechanics based on atomic force microscopy (AFM).

MATERIAL AND METHODS

The study included 50 central fragments of the anterior capsule of the human lens obtained intraoperatively during ultrasonic phacoemulsification by continuous circular capsulorhexis. The measurements were carried out in the Fast Force Volume (FFV) mode. The force curves were processed in the Nanoscope Analysis software (Bruker, USA) using the Hertz model that allows calculating the Young's modulus of the capsule sample based on the dependence of the force on the puncture depth.

RESULTS

There was no statistically significant difference in the «stiffness» of the inner and outer surfaces before and after removal of the subcapsular epithelium (p=0.25). In all cases, the inner surface of the capsule turned out to be «harder» than the outer one. In this case, the ratio of Young's modulus of the inner and outer surfaces has a significant dependence on age (p<0.001). With an increase in age from 50 to 90 years, this ratio decreased from ~7 to ~1.5. This was due to a simultaneous change in Young's modulus of the opposite nature: an increase in the stiffness of the outer surface and its decrease in the inner one.

CONCLUSION

It is possible to assess lens capsule biomechanics using AFM if the subcapsular epithelium is present. In this case, the objects of study are the areas of the capsule free of epithelium, and the epithelial cells themselves can be used to identify the inner surface of the capsule. Regardless of age, the stiffness of the inner surface of the anterior lens capsule significantly exceeds that of the outer surface.

Anti-Rheumatic Effect of Antisense Oligonucleotide Cytos-11 Targeting TNF-α Expression

The urgency of the search for inexpensive and effective drugs with localized action for the treatment of rheumatoid arthritis continues unabated. In this study, for the first time we investigated the Cytos-11 antisense oligonucleotide suppression of TNF-α gene expression in a rat model of rheumatoid arthritis induced by complete Freund’s adjuvant. Cytos-11 has been shown to effectively reduce peripheral blood concentrations of TNF-α, reduce joint inflammation, and reduce pannus development. The results achieved following treatment with the antisense oligonucleotide Cytos-11 were similar to those of adalimumab (Humira^®); they also compared favorably with those results, which provides evidence of the promise of drugs based on antisense technologies in the treatment of this disease.

Biomineralization of Trabecular Meshwork in Open-Angle Glaucoma

A new form of open-angle glaucoma has been identified, in which calcification and silicification of the trabecular meshwork is a potentially significant component of outflow obstruction. It is noted that the mineralization of this area is promoted by various disturbances in the acid-base balance in the tissue. The role of melanosomal enzymes in the initiation of the formation of mineral calcium phosphate in trabecular tissue in open-angle glaucoma is considered.

Ultrafast Magneto-Optics in Nickel Magnetoplasmonic Crystals

Here, we report on ultrafast all-optical modulation of the surface-plasmon (SP)-assisted transverse magneto-optical Kerr effect (TMOKE) and the reflectance in a one-dimensional nickel magnetoplasmonic crystal (MPC). A 50 fs nonresonant laser pump pulse with 7 mJ/cm² fluence reduces the magnetization by 65%, which results in the suppression of TMOKE in the SP-resonant probe from 1.15% to 0.4%. The differential reflectance of SP-resonant probe achieves 5.5%. Besides this, it is shown that electron thermalization and relaxation in MPC are several times slower than those in the plane nickel.

Bioinorganic chemistry of open-angle glaucoma: A review

At present, physical methods of chemical analysis are constantly improving providing large amount of data on elemental composition of organs and tissues. However, only few works describe the correlation (or the potential connection) between the general or local bioelemental imbalances and specific biochemical reactions that are involved in pathogenesis of certain diseases. This review describes primary open-angle glaucoma (POAG) - one of the most common ophthalmic diseases - in terms of elemental chemistry. The authors look into the impact that various subgroups of elements have on passive and active processes of homeostasis regulation and hydrodynamic balance in the eye. Alkaline metals and their analogues (K, Na, Li, Rb, Cs) influence hydrostatics and hydrodynamics by means of both K-Na pumps and osmosis. Alkaline-earth elements and their analogues (Ca, Mg, Sr, Ba, Be) are involved in biomineralization and intercellular interaction in the drainage areas. Chalcophile metals and their analogues (Zn, Cu, Hg, Co, Ni, Cd, Pb, Mo, Sb) regulate redox reactions. They are the cofactors of enzymes that support structural homeostasis of the drainage area. Siderophile metals (Fe, Mn, Cr, Rh) regulate oxidation-reduction reactions, including those associated with limited nutrition of tissues in glaucoma. The role of amphoteric metals and nonmetals (Al, Si, Ga, V, TI, Sn, Ge, Zr, W) in POAG has not been described properly, but they were noted to participate in mineralization. Structure-forming non-metals and their analogues (N, S, Se, As) are directly involved in the formation of protein and non-protein aggregates that prevent aqueous humor outflow. The specific role of phosphorus in the pathogenesis of glaucoma has not been described previously. The authors analyze the involvement of phosphorus in energy-dependent processes of cellular activity, which are aimed at the reprocessing of aggregates that cause aqueous humor retention.

[Application of visible longwave radiation for inactivation of microorganisms]

PURPOSE

To perform a comparative assessment of the bactericidal and fungicidal effects of various parts of the radiation spectrum (Ultraviolet A, red, green and blue).

MATERIAL AND METHODS

The study included strains of the most clinically significant microorganisms, which are the most common causes of purulent keratitis - S. aureus, P. aeruginosa and fungi C. albicans. After populating the surface of Petri dishes uniformly with microorganisms of each culture, on four out of the five specimens the central zone of the surface with a diameter of 1 cm was irradiated with light of different spectrum - from ultraviolet to red, with a total radiation energy density of 5.4 J/cm². One specimen remained as the control subject. After irradiation, scanning electron microscopy with lanthanides contrasting (SEMLC) was used to evaluate the total metabolic activity, the activity of the efflux systems and the morphological characteristics of the microorganisms.

RESULTS

The damaging effect of visible spectrum light and UVA radiation on S. aureus, P. aeruginosa and C. albicans cultures was proved by SEMLC. Green spectrum emission with a wavelength of 500 nm had the highest antimicrobial activity. It was manifested by a decrease in the overall level of metabolic activity (from 40-63 c.u. to 26-37 c.u. (S. aureus (p<0.01), P. aeruginosa (p<0.01) and C. albicans (p<0.05)), as well as a 2-fold increase in the proportion of S. aureus cells with active efflux systems.

CONCLUSION

SEMLC allows evaluation of parameters of the microorganisms` state: morphological (form and size) and functional (general metabolic activity, activation of efflux systems). Investigation of S. aureus, P. aeruginosa and C. albicans cultures using SEMLC demonstrated the antimicrobial activity of green spectrum radiation of 500 nm wavelength. This will serve as a basis for further research and development of a method of treating infectious keratitis using green light.

[Histological verification of autofluorescence borders of periorbital skin tumors]

Tumor borders are one of the most significant characteristics of any tumor, including that of the skin.

PURPOSE

To compare histological borders of periorbital skin tumors with their autofluorescence borders built from the analysis of non-induced protoporphyrin IX autofluorescence.

MATERIAL AND METHODS

The study group included 8 patients with skin tumors of the eyelids, periorbital region, eyebrow and zygomatic regions aged 54-88 years. The tumors varied in size from 2 to 8 mm and all displayed signs of basal cell carcinoma (BCC). At admission, all the patients underwent non-induced autofluorescence diagnosis. The images were processed with the «CancerPlot» program. During radio excision, the autofluorescent border of each neoplasm was marked with a surgical incision of about 5 mm long and 2 mm deep.

RESULTS

Upon pathomorphological examination, solid BCC was identified in 7 cases. The remaining case was senile keratosis. All reference incisions were located in healthy tissues not farther than 1 mm from the tumor (or keratosis locus, correspondingly).

CONCLUSION

By the example of facial BCC, an evident correlation was established between histological borders of the tumor and its native (non-induced) protoporphyrin IX autofluorescence.

[Accumulation of sulfur and phosphorus in the eye's drainage system in primary open-angle glaucoma]

PURPOSE

To analyze the chemical composition of the sclera and trabecular meshwork in patients with primary open-angle glaucoma (POAG) and to assess the impact of corneal-compensated intraocular pressure (IOP) on the chemistry of the drainage area.

MATERIAL AND METHODS

Biopsy specimens of the trabecular meshwork (89 specimens) and sclera (41 specimens) obtained from patients with POAG on maximal medical therapy were analyzed to determine the content of certain chemical elements - carbon (C), nitrogen (N), oxygen (O), aluminum (Al), calcium (Ca), chlorine (Cl), potassium (K), magnesium (Mg), sodium (Na), phosphorus (P), silicon (Si) and sulfur (S). The elements were selected based on chemical structure target tissue and sensitivity of the method used for analysis. Visualization was performed using the «EVO LS 10» (Zeiss, Germany) scanning electron microscope (SEM), and the chemical composition was studied with the «Oxford-X-MAX-50» (Oxford, UK) energy-dispersive spectrometer (EDS). Statistical analysis was performed using the Spearman correlation.

RESULTS

The IOP of patients with POAG was found to have positive correlation with the total amount of S, P, and Ca in the trabecular meshwork. The accumulation of sulfur-containing compounds associated with pigment granules in trabecular meshwork's tissue was identified. A correlation was determined between the organic and inorganic (mineral) phosphorus content in the trabeculae, and the IOP values. The organic component of phosphorus was better represented than the mineral component in patients with increased IOP.

CONCLUSION

In patients with POAG, an increase in the IOP level causes the amount of S associated with pigment granules and the proportion of organic P to increase in the trabecular meshwork, which should be taken into account in the further search for drug therapy that would potentially affect pathologically altered tissue.

[Structural features of the vitreous body in asteroid hyalosis]

PURPOSE

To analyze intravital structure of the vitreous body in asteroid hyalosis using digital ultrasound imaging.

MATERIAL AND METHODS

The study included 64 patients (128 eyes) aged 62 to 73 years with opacities in the vitreous body characterized as asteroid hyalosis.

RESULTS

The macrostructure of the vitreous body was evaluated based on the results of digital ultrasound imaging. The analysis covered various types of ultrasound images of the inner projection of the eye and the vitreous cavity. The study demonstrates the possibility of in vivo evaluation of the integrity of vitreous tracts, and the vitreous body as a whole.

CONCLUSION

Ocular ultrasound images of patients with asteroid hyalosis acquired in vivo were used to evaluate the macrostructure of the vitreous body and determine the features of spatial defects.

[Rational strategy for studying microbiome of the ocular surface of people using hard contact lenses by method of 16S rRNA gene metabarcoding]

The study is based on the hypothesis that high taxonomic diversity of bacteria detectable on the eye surface by molecular genetic methods is attributed to the high level of its contamination by skin microflora. Such contamination would make it problematic to identify the fractions of real ocular surface microbiome, which remains behind the one-percent cut-off threshold adopted in the metagenomic analysis. Hard contact lenses for long-wearing act as a physical filter preventing DNA contamination from random microorganisms, and at the same time providing adhesion to the living cells of bacteria and fungi. To confirm this assumption, a detailed analysis of references was carried out, supplemented by original laboratory research.

MATERIAL AND METHODS

The analysis included 16 hard contact lenses obtained from 11 patients with impaired refraction (myopia). Additionally, conjunctival mucosa scrapings were collected from 42 patients. Samples were cross-analyzed by 16S rRNA gene sequencing using 454 GS Junior (Ion Torrent) and Illumina MiSeq platforms.

RESULTS

Results obtained by the Illumina platform (analysis of the V3-V4 variable region of the 16S rRNA gene) showed better convergence with the data of culture tests reported in the literature. The major microorganism groups found were: Acinetobacter (39%), Gluconacetobacter (10.8%), Propionibacterium (9.3%), Corynebacterium (9.3%), Staphylococcus (7.2%), Streptococcus (7%), Pseudomonas (4.1%), Micrococcus (3.3%), Yersinia (3%), Chondromyces (2.4%), Serratia (2.3%), and Bacillus (2.1%). Analysis of the samples obtained directly from the mucosa revealed dominance of typical skin-associated microorganisms.

CONCLUSION

The present study proposes a contamination-reduction algorithm for microbiological testing of the ocular surface using hard contact lenses for prolonged wearing as a carrier for microbial DNA.

[Nitrogen and oxygen levels in placenta - a predictor for retinopathy of prematurity]

PURPOSE

To study the distribution of chemical elements in the placenta of pregnant women at 24-35 and 39-40 weeks of gestation, and to assess the possibility of using data on the levels of principle chemicals for predicting clinical manifestation of retinopathy of prematurity (ROP).

MATERIAL AND METHODS

The study examined 375 placenta tissue fragments of pregnant women for levels of the following chemical elements: carbon (C), nitrogen (N), oxygen (O), calcium (Ca), chlorine (Cl), potassium (K), sodium (Na) and phosphorus (P). Subjects were divided into 3 groups: 1st group consisted of 41 pregnant females (205 fragments of placenta tissue) at weeks 24-35 of gestation, whose children would not develop ROP; 2nd group included 14 mothers (70 fragments of placenta tissue) at weeks 39-40 of gestation; 3rd group - 20 pregnant (100 fragments of placenta tissue) at weeks 24-35 of gestation, whose children would be diagnosed with ROP. Examination of the eye fundi of children from ROP risk group was done by digital retinoscopy and indirect binocular ophthalmoscopy. Chemical composition of placenta was studied using energy-dispersive x-ray microanalysis based on scanning electron microscopy.

RESULTS

Descriptive statistical values of chemical elements were obtained for the three study groups. Statistically significant percentile differences were detected in the levels of C, N and O in the samples (p<2.2·10-16). Differences in the levels of N, O, K, and Na in the placenta of pregnant women of the three study groups were determined.

CONCLUSION

Comparative chemical analysis of the placentas of pregnant women at different gestation periods showed higher levels of N, K, Na, and lower levels of O in the group of mothers whose children would be diagnosed with ROP. Normalized nitrogen content in the placenta of women whose children would develop ROP was 12.9%. Thus, nitrogen content may serve as a pre-clinical marker of retinopathy of prematurity.

[Ultrastructural characteristics of the mechanisms of varicose transformation of veins of different localization]

The contemporary interpretation of the pathogenesis of varicose vein transformation in young patients indicates the genetically determined pattern of this process. According to the diagnostic criteria proposed by T.I. Kadurina, varicose veins of different localization belong to the so-called minor phenomena of undifferentiated connective tissue dysplasia (UCTD) syndrome. However, its impact on the development of varicose vein transformation is taken into account by not all researchers probably due to the fact that its clinical manifestations remain somewhat unclear.

OBJECTIVE

To prove the role of UCTD syndrome in the development of varicose transformation of veins, by examining their wall biopsy specimens at the ultrastructural level.

MATERIAL AND METHODS

Vein wall fragments removed from 25 male patients were examined; their mean age was 19 years. All the patients were divided into 3 groups: 1) cases of left-sided varicocele (VC), 2) those of varicose veins in the lower extremities (VVLE), 3) control cases. Electron microscopy examination (EME) and morphometric and statistical analyses were performed.

RESULTS AND DISCUSSION

EME showed similar changes in the vein wall biopsy specimens obtained from both pediatric and adult patients with VC and VVLE. Analysis of the qualitative parameters of collagen fiber bundles revealed considerable differences in their thickness compared to those in the control group; the phenomenon of structural chaos; variability of their number in the bundles; uneven bundle thickness; abruptness of individual fibers due to their tortuous course; bundle disorganization areas and an expanded part of interfiber spaces. Morphometric analysis demonstrated a pronounced variability of numerical series when measuring their bundle thickness. The above changes indicate primary incompetence of the connective tissue framework of the varicose vein walls. The measurements of smooth muscle cells showed a decrease in their volume compared to that in the control group; there was an excessive proliferation of connective tissue between them. No substantial difference was found in the arithmetic mean of the measurements in different degrees of VC and VVLE and in the age groups for these diseases.

CONCLUSION

The ultrastructural analysis and morphometric results confirm the key role of UCTD syndrome in the pathogenesis of VC and VVLE and make it possible to combine these diseases into one - systemic varicose veins.

[The effect of the tear film on the results of a direct assessment of the sensitivity of the cornea]

Attempts to find clinical application for esthesiometry are associated with studying sensitivity disorders that occur in various diseases (diabetes mellitus, keratitis of various etiologies, corneal erosion, dry eye syndrome), as well as after surgical interventions.

PURPOSE

To evaluate the influence of the tear film on the results of direct assessment of corneal sensitivity.

MATERIAL AND METHODS

The study was conducted in a group of 20 healthy volunteers. Criteria for inclusion in the group: absence of any ocular and general systemic diseases in the anamnesis, normal indicators of tear production and stability of the tear film according to Schirmer and Norn tests. The process of testing involved a specially designed device that was used to exert a dosed force by jets of air on the frontal corneal surface and the pressure was recorded at the moment of tactile sensations and at the breakup time of tear film, as an indicator of its biomechanical stability.

RESULTS

A strong correlation have been found between the pressure of the air stream at the moment of getting tactile sensations and at the breakup of the tear film (R=0.91, p=0.0094). The obtained data indicate that the biomechanical resistance of the lacrimal film is a significant factor preventing the correct assessment of the results of direct corneal esthesiometry in the range of values close to conditionally normal sensitivity.

CONCLUSION

In this regard, in their current technical implementation, modern esthesiometers can only be used for monitoring (not for diagnosis!) of pathological processes by analyzing relative (compared to each other) - rather than absolute - sensitivity measures (optimally in combination with analysis of the structural changes in the corneal nerves based on laser confocal microscopy).

[Atomic force microscopy in the study of anterior eye segment structures]

The application of atomic force microscopy (AFM) in ophthalmology is considered with respect of the classical anatomical division of the eye into anterior and posterior segments. The review presents the findings of published research studies that involved AFM as a method for assessing anatomical and functional condition of the structures of anterior eye segment. One significant line of research is related to the use of AFM technologies for evaluation of morphological and biomechanical characteristics of various parts of the eye lens. That topic draws interest due to the need of furthering the understanding of cataractogenesis, as well as the significance of the anatomical and functional characteristics of the lens capsule in the mechanism of accommodation and modern phaco surgery.

[Analysis of light scattering ability of the cornea before and after endothelial keratoplasty]

PURPOSE

To evaluate light scattering ability of the cornea before and after Descemet's stripping automated endothelial keratoplasty (DSAEK) and Descemet's membrane endothelial keratoplasty (DMEK) endothelial keratoplasty.

MATERIAL AND METHODS

The study included 70 patients (70 eyes) who had undergone DSAEK and DMEK (35 patients, 35 eyes in each group). In addition to standard ophthalmological examinations before and during the one-year follow-up after surgery, the patients had their central corneal thickness, stromal thickness, thickness of the interface area and the graft measured with optical coherence tomography (Optovue, U.S.A.). Intensity of light scattering by corneal structures was evaluated using Pentacam HR (Oculus, Germany) topographer with proprietary software and algorithms for calculation of corneal transparency.

RESULTS

Comparison of the outcomes revealed that indices of general integral and stromal light-scattering were higher in patients after DSAEK. Integral light scattering in the interface and graft areas in the DMEK group was significantly lower than in the DSAEK group during the whole follow-up period.

CONCLUSION

The reason for decrease of visual acuity after endothelial keratoplasty, regardless of the surgery type, may be higher light-scattering ability of patient's corneal stroma due to residual opacifications. Better visual acuity outcomes after DMEK in comparison to DSAEK are associated with higher transparency of the interface and graft areas. The suggested new method of assessing the intensity of light-scattering allows more precise evaluation of the influence of light-scattering ability of the stroma, interface and corneal graft after different modifications of endothelial keratoplasty, considering the respective layer thickness and excluding the influence of light scattering on the air-epithelium interface.

[Inflammatory granuloma after intracanalicular punctal plug migration (a clinical case)]

At present, installation of punctal plugs (tear duct occluders) draws attention of ophthalmologists, but this method of treating dry eye syndrome (DES) is not without complications. Considering the rise of DES occurrence - the tendency anticipated to continue - as well as expansion of indications for installation of tear duct occluders, their usage can be expected to rise. The article describes a relatively rare clinical case that involved intracanalicular migration of silicone punctal plug. A female patient of 36 years old sought medical help in Research Institute of Eye Diseases (Moscow) to treat a lump in the area of lower lacrimal punctum in the left eye that was growing in size; the lump had appeared around 2 months prior to the visit. Patient's medical history read that around 2 years ago she had a silicone occluder installed in the lower lacrimal punctum of the left eye. On examination, in the area of lower lacrimal punctum, a body with a nutrient vascular pedicle deriving from lower lacrimal duct could be found. The occluder was absent in the opening of the lacrimal punctum. A revision of lower tear duct cavity was performed to remove its contents. The body filling tear duct opening was removed with forceps. Substance was then sent for histological examination. Tear duct was scraped out, the silicone occluder removed and sent to laboratory for scanning electron microscopy. The patient had no complaints 6 months after the procedure. CONCLUSION: The study showed that the forming body was granuloma resulting from aseptic inflammation. Surface of the silicone occluder in retention of lacrimal pathways remained unchanged. Described surgical tactic is suitable for treating patients with intracanalicular punctal plug migration.

Bioinorganic Markers of a Loss of the Crystalline Lens Capsule Barrier Properties and Consequent Age-Related Cataract Development

The age-related cataract development consequent upon a loss of the lens capsule barrier properties proved to be associated with accumulation of sodium, calcium, phosphorus and potassium. For the first time the use of spatial cluster and correlation analyses showed that the physical light scattering in the crystalline lens volume depends on changes in the lens matter elemental composition. The fields of elevated concentrations of sodium, calcium, phosphorus, potassium and chlorine conformed to the lens capsule geometry and their clustering was similar to that of opacity fields in the lens body. The accumulation geometry of the elements in the lens body that are commonly seen in the aqueous humor of the anterior chamber, can be considered evidence for excessive transitioning of their compounds through the lens capsule shell, while its spatial connection with transparency changes-proof of participation in cataractogenesis.

[Electrophysiological Cardiac Parameters and Results of Antiarrhythmic Treatment in Patients with Paroxysmal Atrial Fibrillation (Lone and Associated with Arterial Hypertension)]

PURPOSE

to assess cardiac electrophysiological parameters in patients with paroxysmal atrial fibrillation (AF), lone or with concomitant arterial hypertension (AH), and their prognostic significance relative to treatment effectiveness.

MATERIALS AND METHODS

We included in this study 184 patients with paroxysmal AF (84 with concomitant AH and 100 with presumed lone AF). Cardiac electrophysiological study was performed in accordance with standardized protocol that included assessment of sinus node recovery time, sinoatrial, intraatrial and interatrial conduction time, and effective refractory periods (ERP) of right and left atria and atrioventricular node. Patients with inducible supraventricular reentrant arrhythmias that could potentially trigger AF underwent catheter radiofrequency ablation of those arrhythmias. Other patients received either antiarrhythmic drug therapy (AAD; n=79) or catheter cryo-ablation (CBA; n=81). Treatment was considered ineffective in case of any symptomatic or asymptomatic AF episode documented by ECG or Holter ECG within 12 months of follow-up.

RESULTS

Patients with lone AF compared with those with AH had shorter ERP of the right atrium (219±21 ms vs. 253±44 ms, respectively, p&lt;0.05) and more prominent dispersion of ERP of right and left atria (median 40 ms, interquartile range 10-50 ms vs. median 20 ms, interquartile range 10-22.5 ms, respectively, p&lt;0.05). There was no statistically significant difference in other electrophysiology parameters between the groups. Sustained supraventricular reentrant arrhythmias were induced in 9% (9 of 100) patients with presumed lone AF and in 1.2% (1 of 84) patients with AH (p&lt;0.05). All these arrhythmias were successfully ablated, and patients had no AF recurrence during 12-month follow-up. Among other patient treatment (CBA n=81, AAD n=79) was effective in 64% of those with lone AFib and in 34% - with AH (p&lt;0.05). In multivariate multiple regression analysis, none of electrophysiological parameters could be assumed as a factor associated with the efficacy of CBA or AAD.

CONCLUSION

Patients with lone AF had more prominent atrial electrophysiological inhomogeneity compared with patients with concomitant AH. Cardiac electrophysiological parameters had no influence on effectiveness of antiarrhythmic treatment.

DNA insecticide developed from the Lymantria dispar 5.8S ribosomal RNA gene provides a novel biotechnology for plant protection

Having observed how botanicals and other natural compounds are used by nature to control pests in the environment, we began investigating natural polymers, DNA and RNA, as promising tools for insect pest management. Over the last decade, unmodified short antisense DNA oligonucleotides have shown a clear potential for use as insecticides. Our research has concentrated mainly on Lymantria dispar larvae using an antisense oligoRING sequence from its inhibitor-of-apoptosis gene. In this article, we propose a novel biotechnology to protect plants from insect pests using DNA insecticide with improved insecticidal activity based on a new antisense oligoRIBO-11 sequence from the 5.8S ribosomal RNA gene. This investigational oligoRIBO-11 insecticide causes higher mortality among both L. dispar larvae grown in the lab and those collected from the forest; in addition, it is more affordable and faster acting, which makes it a prospective candidate for use in the development of a ready-to-use preparation.

[Biomechanical properties of the anterior lens capsule after manual and femtolaser capsulotomy]

PURPOSE

To comparatively evaluate the mechanical stability of the edge of central fragment of anterior lens capsule after manual and femtolaser capsulotomy.

MATERIAL AND METHODS

The mechanical tests were performed on the central fragments of the anterior lens capsules obtained intraoperatively after manual and femtolaser capsulotomy (15 and 13 samples, respectively). The conditions of the developed method of mechanical testing are as close to in vivo as possible. The method allows evaluation of the mechanical response mainly from the edge of the sample, reception of the averaged response from the four edges of the capsule, and almost eliminates the effect of additional edge notches in samples obtained by manual capsulotomy.

RESULTS

After manual capsulotomy, the maximum force and elongation of the anterior capsule sample at maximum tensile strength were significantly higher than similar characteristics of the samples after femtolaser capsulotomy.

CONCLUSION

The obtained results correspond with the morphological studies of capsule edge structure after manual and femtolaser capsulotomy. The edge of the anterior capsule after femtolaser capsulotomy has form, in rough approximation, close to one of a postage stamp perforation, which is the consequence of micro-irregularities (microfractures) in the areas irradiated by pulsed laser, and wider area of deepithelization compared to the manual technique.

[Modified meibography in malignant eyelid tumors of epithelial origin]

INTRODUCTION

Eyelid tumors can be diagnosed using various diagnostic techniques. However, capability of existing methods for determining the type and margins of the tumor at the preoperative stage remains insufficiently studied.

PURPOSE

To improve the noncontact infrared meibography technique and determine its diagnostic capabilities for studying structural changes in meibomian glands in malignant eyelid tumors of epithelial origin.

MATERIAL AND METHODS

The study included 49 people (66 eyelids), among which 21 (21 eyelids) with malignant eyelid tumors, 11 - with benign eyelid tumors (11 eyelids), and 17 (34 eyelids) comprised the control group. The mean age of patients was 64.8±1.56 years. Meibomian glands of the lower eyelids were photographed in infrared light. Receiver-operating characteristic (ROC) curves were constructed to estimate the sensitivity and specificity of the method.

RESULTS

Modified meibography showed 100% sensitivity and 90% specificity in the differential diagnosis of malignant and benign eyelid tumors in 32 patients. Unlike other methods, the modified meibography technique can clarify the margins of tumor growth, which is considered when planning the resection volume.

CONCLUSION

Modified meibography can indicate the margins of tumor invasion; it can be successfully used in the differential diagnostics of malignant eyelid tumors of epithelial origin and benign eyelid tumors.

Synthesis of Magnetic Nanoparticles Stabilized by Magnetite-Binding Protein for Targeted Delivery to Cancer Cells

A new method for obtaining biomodified magnetite nanoparticles for targeted delivery to cells was developed. The method is based on the use of the C-terminal fragment of the Mms6 protein, which is involved in the magnetite biomineralization during the synthesis of magnetosomes in magnetotactic bacteria Magnetospirillum magneticum AMB-1, and the barnase*barstar high-affinity protein pair. The Mms6 protein fragment is required for stabilizing magnetite, and the barnase*barstar pair mediates the interaction between nanoparticles and the component for modification. The efficiency of this method was confirmed in the synthesis of magnetite nanoparticles recognizing the HER2/neu tumor marker and in the selective labeling of HER2/neu with these nanoparticles on the surface of cancer cells.

[Complex morphological assessment of anterior capsule of the lens in patients with capsular contraction syndrome (a clinical case study)]

The anterior capsular contraction syndrome (ACCS) in pseudophakic patients is known to be accompanied by postoperative opacity of anterior lens capsule (ALC) and partial or full closure of anterior capsulotomy opening.

PURPOSE

To perform complex morphological assessment of ALC in patients with ACCS.

MATERIAL AND METHODS

The study involved complex analysis of ALC that was removed due to ACCS in the pseudophakic eye in the setting of diabetes mellitus and past vitreoretinal surgery. The following examination methods were used: light-optical microscopy of ALC samples in the form of polychrome-colored semifine sections using optical microscope Leica DM-2500 (Germany), scanning microscopy of ALC surface with EVO LS10 (Carl Zeiss, Germany) microscope, analysis of chemical element composition and its variation of the ALC sample with energy-dispersive spectrometer Oxford X-Max50 (Oxford, UK).

RESULTS

Light-optical microscopy showed altered state and plication of ALC induced by proliferation from inner surface of the fibrocellular tissue, which gradually thickens (up to 360 µm) towards center and causes reduction of anterior capsulotomy opening. Scanning electron microscopy revealed presence of tissue with uneven micro-relief and a porous three-dimensional structure uncharacteristic for capsule on the surface of ALC. Thickness of the fibrous deposition significantly exceeded the thickness of ALC. Evaluation of elemental composition of the fibrocellular tissue showed elevated concentration of sulfur and phosphorus, which indicates high activity of the regenerative process. In the observed case, the regenerative process was of substitute nature because an attempt to restore the lens was accompanied by formation of connective tissue structurally different from original.

CONCLUSION

Complex assessment of an isolated ALC sample allowed revelation of the chain of pathological processes accompanying the development of ACCS.

[Influence of chemical compositions of anterior chamber aqueous humour and blood serum on the secretion of intraocular fluid]

PURPOSE

to identify the standard chemical composition of anterior chamber aqueous humour (AH) using energy dispersive spectrometer (EDS) integrated in scanning electron microscope (SEM); to study the influence of concentration gradient of chemical elements between aqueous humor and blood serum (BS) on the secretion of intraocular fluid (IOF) at normal and increased intraocular pressure (IOP).

MATERIAL AND METHODS

The study involved two groups of patients consisting of 33 people (33 eyes) each. The 1^st group included patients with cataract and normal IOP (control), the 2^nd group included patients with POAG and decompensated IOP. The samples (AH and BS) were taken during surgeries and studied using Oxford X-Max50 EDS integrated in EVO LS10 SEM.

RESULTS

The concentration ratios (mmol/l) of AH/BS for Na at normal IOP was 1.472/1.278, for K - 0.106/0.035. In cases with POAG with decompensated IOP, the concentration ratio of Na was 1.424/1.248, K - 0.114/0.036. The concentration ratio of N between AH in cases with decompensated IOP and AH of normotonic eyes was 1.151/0.960, for S - 0.020/0.012.

CONCLUSION

Consistent excess of Na and K concentrations in AH compared to BS indicates active participation of these osmotically active elements in the normal process of intraocular fluid secretion. The absence of significant differences in the ratios of Na and K in AH and BS at normal and decompensated IOP indicates low significance of these elements for pathological hypersecretion of intraocular fluid. Increased concentration of N in AH eyes with decompensated IOP compared with AH at normal IOP indicates possible involvement of nitrogen-containing osmotically active substances in the abnormal hypersecretion of intraocular fluid.

[Bioinorganic chemical composition of the lens and methods of its investigation]

Bioinorganic chemical composition of the lens of human and experimental animals (cows, dogs, rats, rabbits) have been analyzed in various studies. In most cases, the studies employed different methods to determine the gross (total) composition of chemical elements and their concentrations in the examined samples. Less frequently, they included an assessment of the distribution of chemical elements in the lens and correlation of their concentration with its morphological changes. Chemical elements from all groups (series) of the periodic classification system were discovered in the lens substance. Despite similar investigation methods, different authors obtained contradicting results on the chemical composition of the lens. This article presents data suggesting possible correlation between inorganic chemical elements in the lens substance with the development and formation of lenticular opacities. All currently employed methods are known to only analyze limited number of select chemical elements in the tissues and do not consider the whole range of elements that can be analyzed with existing technology; furthermore, the majority of studies are conducted on the animal model lens. Therefore, it is feasible to continue the development of the chemical microanalysis method by increasing the sensitivity of Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM/EDS) with the purpose of assessing the gross chemical composition and distribution of the elements in the lens substance, as well as revealing possible correlation between element concentration and morphological changes in the lens.

[n.s.i.n.i.V. Biomechanical aspects of anterior capsulotomy in cataract surgery]

This paper reviews studies on biomechanical properties of the anterior lens capsule. Early experiments in this field were more fundamental. Later studies were aimed mainly at assessing the mechanical stability of the capsule edge after manual or femtosecond laser capsulorhexis (capsulotomy) - an important step in modern minimally invasive phaco surgery. For biomechanical tests, ex vivo samples of human and animal anterior capsules were used. The results of the studies presented here are quite heterogeneous, which suggests the necessity of gaining further insight into the issue.

[Comparative characteristics of the chemical composition of vitreal contents of cadaver eyes and eyes with terminal refractory glaucoma]

PURPOSE

To compare the chemical elemental composition of vitreous cavity content taken from cadaveric eyes compared to samples taken from the eyes with terminal stage refractory glaucoma with decompensated intraocular pressure (IOP).

MATERIAL AND METHODS

The vitreous contents of the eyes from 2 groups were studied. The 1st group included 15 cadaveric eyes; the 2nd group included 15 eyes with refractory glaucoma in the terminal stage of the disease with decompensated IOP in patients with hypertension pain. The vitreal content samples were taken in the course of antiglaucoma surgery aimed at preserving the eye as an organ and involving employment of drainage in the vitreous cavity. The study of virtual contents was carried out on energy dispersive spectrometer Oxford X-Max 50 integrated into scanning electron microscope Zeiss EVO LS10.

RESULTS

Increased concentrations of Kalium and Phosphorus were detected in the vitreous content of cadaveric eyes compared with the vitreal content from the eyes with terminal glaucoma with decompensated IOP taken in vivo (K - 0.172/0.093; P - 0.045/0.025 mmol/L). In the vitreous cavity in the eyes with end-stage glaucoma with decompensated IOP, the concentration of Nitrogen was higher in comparison with human cadaver eyes (2.030/1.424 mmol/L).

CONCLUSION

The increased concentrations of Kalium and Phosphorus in the vitreous content of cadaveric eyes is associated with postmortem autolytic processes and with the release of intracellular content in the destruction of cell membranes. The increased Nitrogen concentration in the vitreal contents of the eyes with terminal stage glaucoma with decompensated IOP may be associated with the presence of osmotically active nitrogen-containing compounds in the eyes with increased IOP.

[New approaches to the treatment of keratoconjunctivitis sicca]

A new method has been developed for the treatment of severe forms of keratoconjunctivitis sicca (KCS) that involves the use of an original cyclosporine A (CyA) saturated soft contact lens (SCL) together with preservative-free artificial tears therapy.

AIM

to evaluate the effectiveness of the newly developed treatment for KCS based on the use of medical SCL saturated with 0.05% CyA.

MATERIAL AND METHODS

The patients (43 men, 60 eyes) with severe KCS were divided into 2 groups. Group 1 included 21 patients (30 eyes), who received artificial tears and wore 0.05% CyA-saturated silicone-hydrogel SCLs. Group 2 included 22 patients (30 eyes), who wore unsaturated original SCLs and received CyA instillations 2 times daily and, also, artificial tears. Apart from a standard ophthalmic examination, the assessment included Schirmer's test, Norn's test, vital eye stain tests, tear osmometry, laser confocal tomography of the cornea, optical coherence tomography of the anterior segment with meniscometry, impression cytology of the conjunctiva, tear pH measurement, plating of the content of the conjunctival cavity, measurement of the width of the palpebral fissure, and calculation of the ocular surface disease index. Treatment results were followed up at 1, 3, 6, and 12 months.

RESULTS

The use of 0.05% CyA-saturated SCLs allows to halve treatment time for patients with severe KSC (down to 1 week - 1 month) as compared to unsaturated original SCLs in combination with 0.05% CyA instillations and to reduce it 5 times as compared to 0.05% CyA instillations only.

CONCLUSION

The new method of KSC treatment that involves the use of medical SCL of original design (ensures even distribution of 0.05% CyA across the ocular surface) and preservative-free artificial tears has demonstrated high therapeutic effectiveness as compared to existing methods.

[Elemental composition of aqueous humour and blood serum at various levels of intraocular pressure]

AIM

To conduct a comparative study of element concentrations in the aqueous humour of human eye and blood serum at various levels of intraocular pressure (IOP).

MATERIAL AND METHODS

The chemical composition of biological fluids was studied in two equal groups (33 patients/33 eyes each): group 1 - primary open-angle glaucoma (POAG) with decompensated IOP and group 2 - normal IOP (the controls). Sampling of the aqueous humour and blood was done during surgical procedures, namely, penetrating glaucoma surgery (group 1) and cataract phacoemulsification (group 2). Blood was taken from the cubital vein and centrifuged to obtain the supernatant for further analysis. The samples were studied with Zeiss EVO LS10 scanning electron microscope (SEM) equipped with Oxford X-Max50 energy dispersive spectrometer.

RESULTS

In both groups, regardless of the IOP level, Na and K concentrations were found to be constantly higher in the aqueous humour than the blood serum. The ratio of Na concentrations in the aqueous humour and serum (measured in mmol/l) was 1.51/1.30 at normal IOP and 1.49/1.31 at decompensated IOP. The ratio of K concentrations was 0.11/0.03 and 0.12/0.03, respectively. Concentrations of N and S in the aqueous humour were higher in the group with decompensated IOP.

CONCLUSION

Regardless of the IOP level, Na and K concentrations were found to be constantly higher in the aqueous humour than the blood serum. IOP elevation was accompanied by an increase in N and S concentrations in the aqueous humour.