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.