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Biomedical subjects

I V Tsapenko

Publications and source records attributed to I V Tsapenko.

At least 19 recordsLinked to original sources
PubMed2003

[Electroretinography in the diagnosis and study of pathogenesis of X-linkage retinoschizis].

Due to an extensive variability of manifestations of X-linkage retinoschizis, there is a need in a differential diagnosis of it and of other hereditary retinal diseases. The method of electroretinography is often of primary importance in specifying a diagnosis in ophthalmology; it both enables the detection of new and more sensitive criteria of early and differential diagnosis and ensures a more profound understanding of changes occurring in the retina. A topical analysis of changes of the bioelectric activity taking place in different retinal layers and sections as well as a differential evaluation of the functional condition of neurons and glia Muller's cells in patients with X-linkage retinoschizis were accomplished within the framework of this study. The nature of the peak latency and of the b-wave amplitude in the electroretinogram (ERG) and in the mechano-electroretinogram (MERG) as well as of a low-frequency ERG is indicative of that Muller's cells are damaged; the damage severity is related with an intensity of the pathological process and can be objectively determined by the ERG examinations of patients. An analysis of sub-components of a low-frequency rheoelectroretinogram (RERG) shows weakened inhibitory inter-neuron connections in the retina, which is a sign of disease aggravation. The regularities of changes of retinal biopotential to blue light flashes under all registration conditions (ganz-feld, macular and rhythmical stimulation) differ from the ERG dynamics to other light stimuli, which is indicative of a significant role of the pathology of S-cone paths in the development of X-linkage retinoschizis.

Adolescent↗
PubMed1990

[The rhythmic ERG in the diagnosis of diabetic retinopathy in cataract patients].

The paper describes a new method for diagnosing initial stages of diabetic retinopathy in the presence of cataract--analysis of amplitude parameters of averaged ERG. The usage of different frequency stimuli allows to separately judge about the state of peripheral (10 Hz) and central (40 Hz) segments of the retina. The stage of diabetic retinopathy can be judged by degree of depression of rhythmical ERG. Ophthalmoscopic and fluorescein angiographic verification of the method conducted in 70 patients (94 eyes) after cataract extraction confirmed its high informativeness.

Aged↗
PubMedDate not supplied

[Time course of bioelectrical activity of retina in patients with pigmented abiotrophy treated by deoxinate].

Bioelectrical retinal activity was assessed before and after a course of deoxinate therapy and in a blind placebo test in order to assess the efficacy of this new drug in the treatment of patients with pigmented retinal abiotrophy. Time course of electroretinograms during deoxinate therapy indicated a significant positive effect of the drug on retinal function as regards a variety of electrophysiological parameters in 80-94% patients. Improvement of electroretinography data was paralleled by improvement of visual acuity, extension of visual fields, and decrease of scotomas. Good effect was attained in patients with early and far advanced stages of pigmented retinal abiotrophy. Analysis of bioelectrical activity of the retina after a course of therapy with deoxinate and enkad showed a higher efficacy of the former drug in patients with pigmented retinal abiotrophy.

Adjuvants, Immunologic↗
PubMedDate not supplied

Electroretinographic characteristics of proliferative vitreoretinopathy in rhegmatogenous detachment of retina.

Thirty-five patients with types A, B, C2, C3, and D1 proliferative vitreoretinopathy (PVR) were followed up for 8-14 months after surgical treatment of rhegmatogenic amotio retinae. Hanz-Feld electroretinogram (ERG), rhythmic ERG to low and high-frequency stimulation, and macular ERG were recorded. Before surgery all patients presented with specific signs of changes in the retinal electrogenesis, characteristic of rhegmatogenic amotio retinae with PVR of different types. Comparative analysis of ERG and rhythmic ERG alteration showed a more expressed reaction of Mueller's glial cells in patients with types A-C2 PVR and of second order neurons in the internal nuclear layer of the retina in those with types C3 and D1 PVR. Characteristic changes in the retinal functional activity were detected, possessing a prognostic significance. According to electrophysiological studies, the decisive factor for predicting the course of recovery after surgical treatment of retinal detachment is the preoperative function of retinal neurons. A drastic depression of low-frequency rhythmic ERG is the most unfavorable sign in prognosis of the postoperative time course of visual functions. The least favorable course of recovery after the operation is typical of amotio retinae with type C3 PVR. Recovery of amplitudes of different biopotentials and functional horizontal bonds at different levels of the retinal structure is different.

Electroretinography↗
PubMedDate not supplied

[Early changes in the bioelectrical activity of retina after eyeball contusion].

Characteristic signs of changes in the bioelectrical activity of the retina soon after contusion of the eyeball supplement the functional criteria used for accurate diagnosis of the severity of contusion (classification of the injury). The most sensitive indicator of electroretinography is the amplitude of the electroretinogram (ERG) a-wave, which is sharply suppressed during the first three days in injury of any severity. Recovery of the bioelectrical activity of photoreceptors is delayed in comparison with the time course of the function of the second-order neurons (more rapid recovery of the b-wave in comparison with the a-wave). The reactivity of Müller cells increases in severe contusion, which is shown by a more pronounced decrease in the ERG b-wave amplitude and less expressed changes in low-frequency ERG. Analysis of the time course of biopotentials during repeated examinations of the patients helps control the efficacy of treatment. The results indicate that electroretinographic examinations are the most desirable 5-7 days after the contusion, because at this period the differences in the bioelectrical activity of the retina are the most expressed. The most informative parameters of electroretinography are the time course of total ERG a- and b-waves and the low-frequency rhythmic ERG.

Action Potentials↗
PubMedDate not supplied

[Effects of ozone therapy on the functional activity of the retina in patients with involutional central chorioretinal dystrophy].

The retinal electrogenesis was studied in central chorioretinal dystrophy (CCRD) of different stages. The general peculiarities of the ozone-therapy influence on the functional retinal activity typical of any CCRD stage were detected; they comprise: an increasing activity of neurons in the muscular region and a specificity related with the dynamic functional activity of the retinal peripheral segments peculiar of each disease stage. A sharp growth of glial index Cg (b/R12) detected in all patients is indicative of an activated metabolism of Mueller glial cells and of impaired glial-neuron relations in the retina as observed in CCRD. A decreasing Cg, observed after ozone-therapy, is an indirect confirmation of anti-hypoxic effect produced by ozone, which can be regarded as a patho-physiological mechanism of its positive influence on the dynamics of the functional retinal activity. Ozone-therapy is recommended to be implemented with the electroretinography monitoring.

Choroid Diseases↗
PubMedDate not supplied

[Experimental intraocular introduction of blood serum of patients with endophthalmitis].

Effects of blood serum from patients with endophthalmitis, who systematically received gentamicin at therapeutic dose, exerted on the retina of healthy rabbits were experimentally studied. A moderate toxic effect produced by gentamicin on the retina, when it was administered in the vitreous body of rabbits, was detected yet on day 1 of the experiment. Changes of retinal electrogenesis were aggravating and, beginning from day 7, there were noted profound changes of the functional activity in all retinal layers. According to the results, the blood serum from patients with endophthalmitis, who were systematically receiving gantamicin at therapeutic dose, does not virtually have any negative effect on the functional condition of the retina and can be used for intracavitary administration.

Animals↗
PubMedDate not supplied

[Functional diagnosis of retinal ischemia. Communication 1. Reaction of Muller cells at early stages of diabetic retinopathy].

Electroretinographic examinations were made in 191 patients with non-proliferative and pre-proliferative diabetic retinopathy. On the basis of the ratio of b-wave in ??? and ???? at 12 Hz, the glial index (Cg) was estimated for evaluating the functional changes in Muller cells. As the retinal ischemia aggravated, C@f was increasing, which was indicative of an activated metabolism of Muller cells. C@g was shown to be a sensitive criterion of retinal ischemia ensuring the detection of initial stages of retinal ischemia prior to the detection of changes recognizable in ophthalmoscopy and fluorescence angiography. The established regularities of changing functions in Muller glia and in glia-neuron ratios denote the possibility of using the electroretinographic criteria in the diagnosis of lesions in the retina and of early signs of retinal dystrophy in diabetic retinopathy.

Adult↗
PubMedDate not supplied

[Transplantation of neural stem cells in experimental retinopathy].

A stable and easily reproducible model of experimental retinopathy was constructed in rabbits. The influence of transplanted neural stem cells (NSC) on the functional activity of the retina was studied. Retinopathy was provoked by 0.04 mg of kainic acid introduced intravitreously. The cultivated NSCs were transplanted into the vitreous bodies of the right (experimental) eyes, physiological solution was administered into the left (control) eyes. Clinical examinations of the eyeball in the experimental group showed less pronounced proliferative changes and a lack of gliosis, whereas, in the control group, the retina looked like tissue with fibrous changes and glial bars. An evaluation of the functional activity of the retina denoted a reliably better function of rod bipolars and Muller glias in the eyes with transplanted NSCs during the whole follow-up.

Animals↗
PubMedDate not supplied

[Functional diagnostics of retinal ischemia: Muller cells and neovascularization of the retina in diabetic retinopathy].

Electrography was made for 58 patients (110 eyes) with proliferative diabetic retinopathy distinguished by neovascularization. Fluorescence angiography and electroretinography were dynamically made for 1-1.5 years in 18 patients with preproliferative diabetic retinopathy. The hyperfunction of Muller cells with an increasing glial index, which was detected earlier by us in progressing retinal ischemia, was also observed in retinal neovascularization. The regular monitoring of the dynamics of electroretinogram (ERG, made several times) makes it possible to evaluate in each separate case a degree of neovascularization risk. When the value of the glial index abruptly drops in a patient, who had earlier regular increases in the index value, there is a high probability of a fast development of retinal neovascularization. Regular ERG examinations are advisable for the evaluation of a neovascularization risk.

Diabetic Retinopathy↗
PubMedDate not supplied

[Antibodies to retinal S antigen in the tear and serum as an indicator of the nature of a course of endogenous uveitis in children].

Antibodies (IgM and IgG) to retinal S antigen were studied by enzyme immunoassay in the tear (n = 135) and blood serum (n = 221) samples taken from 45 children with chronic endogenous uveitis during a follow-up (for 6 months to 5 years). The studies have confirmed the early evidence that detection of serum autoantibodies may be used for the diagnosis of autoimmune and infectious-and-autoimmune uveitis, the verification and prediction of renal alterations, risks for lesions in the second eye in unilateral uveitis and prerecurrence in bilateral uveitis. Criteria for detecting antibodies to lacrimal S antigen were developed. Its has been ascertained that it is expedient to use this procedure as a method for controlling the efficiency of treatment in uveitis involving the posterior parts of the eye, confirming, and predicting the risk for involvement of the retina into an inflammatory process, detecting trends for development of chronic forms of both bilateral and unilateral uveitis. Simultaneous accumulation of IgM and/or IgG antibodies in the lacrimal fluid and serum, as well as imbalance, i.e. a prolonged enhancement of only local or only systemic response to S antigen (of both classes), are prognostically unfavorable.

Adolescent↗
PubMedDate not supplied

[Use of perindopril in the treatment of patients with diabetic retinopathy].

There have been recent data on an important role of the rennin-angiotensin system (RAS) and its major effector--angiotensin-converting enzyme (ACE) in the pathogenesis of diabetes mellitus and its complications. The treatment for diabetes mellitus with ACE inhibitors (ACEI) has received wide recognition. By lowering blood pressure, ACEI improves endothelial function, positively affect carbohydrate metabolism, and exerts a nephroprotective effect. However, the role of ACEI in the treatment of diabetic retinopathy (DR) remains to be studied. This paper presents the results of a comprehensive clinicofunctional study of 36 patients with preproliferative DR before and after treatment with the ACEI perindopril. The agent has been found to have a positive effect on visual functions, retinal electrogenesis, and the state of the blood-retinal barrier.

Adult↗
PubMedDate not supplied

[Topography and functional changes of the rabbit retina with a single injection of triamcinolone].

Intravitreal injections of 6 and 8 mg of triamcinolone (kenalog) were studied for impact on the time course of electroretinographic changes and the retinal structure of healthy rabbits. Histopathological study failed to reveal the signs of toxic damage to the retina. The electroretinographic findings suggest that kenalog primarily affect the function of photoreceptors and Muller's glia. The fact that the alteration of retinal functional activity may be linked with the early cytotoxic effects of the agent cannot be ruled out. However, the changes found in retinal electrogenesis are most likely to reflect the mechanisms of kenalog's beneficial therapeutic action that is primarily mediated through its effect on the function of photoreceptors and Muller's cells.

Animals↗
PubMedDate not supplied

[Effect of enkad on the development of experimental chloroquine retinopathy].

The effect of enkad on the development of chloroquine retinopathy in rabbits was studied by electron microscopy and electrophysiological methods. It is shown that subconjunctival enkade injection inhibits the development of a dystrophic process in the retina induced by intravitreous chloroquine administration.

Animals↗
PubMedDate not supplied

[Prediction of functional results of extraction in complicated cataract in patients with tapetoretinal abiotrophy].

Relative informative value of various functional methods of investigation was studied in 87 patients with tapetoretinal abiotrophy and complicated cataracts in order to find adequate methods for the assessment of the retinal status before surgery and to define the criteria of visual function prediction. The efficacy of the diagnosis was verified after cataract extraction in these patients. The methods of investigation employed were instrumental electroretinogram (ERG) recording, Hanz-Feld stimulated microERG, high-frequency (40 Hz) rhythmic ERG, electrocoagulograms, determination of electric sensitivity thresholds for the retina and of the optic nerve axial bundle lability (ESL), perimetry, and vision acuity measurements. Rhythmic ERG and ESL were found the most informative; rhythmic ERG amplitude proved to be the most sensitive to macular area involvement, this prompting employment of this method for the prediction of visual functions. Rhythmic ERG helped single out three groups of patients with relatively favorable, doubtful, and unfavorable outcomes.

Cataract↗
PubMedDate not supplied

[Pathological changes in the eyeball in tapetoretinal abiotrophy].

The authors sum up the results of comprehensive examination of all the principal structures of the eyeball in patients with tapetoretinal abiotrophy. Present-day methods of investigation were employed, that helped reveal a generalized pattern of the pathologic process in this condition. The detected shifts should be borne in mind when choosing a method for cataract extraction in such patients.

Adult↗
PubMedDate not supplied

[The electroretinographic assessment of the efficacy of retinal electrostimulation by the method of biocontrolled chronophysiotherapy in Stargardt's disease].

The biocontrolled chronoelectrotherapy for Stardgardt's disease has some advantage over the traditional electrostimulation techniques. There is an increase in the efficacy with a lower number of sessions, adverse reactions are not observed, and the risk for overdosage decreases. The technique proposed normalizes the rhythms of blood flow and it may be useful for the chronoelectrostimulation of the paired eye in abnormalities of or injury to the other eye. Its therapeutical efficiency is controlled by the changes occurring in the ERG b-wave.

Adult↗