[Angioarchitecture of small retinoblastomas: the role of optical coherence tomography angiography]. / Angioarkhitektonika malykh retinoblastom: rol' opticheskoi kogerentnoi tomografii-angiografii.

Optical coherence tomography angiography (OCTA) is a non-invasive diagnostic method used in children and adults. Features of angioarchitecture of small retinoblastoma are not sufficiently covered. PURPOSE: The study investigated the angioarchitecture of small retinoblastomas using OCTA. MATERIAL AND METHODS: The study included 10 children with binocular retinoblastoma aged 2.7±0.5 months with small tumors of central localization (10 foci). The tumors were divided into 3 groups: group 1 (n=4) - tumor thickness 0.8±0.2 mm; group 2 (n=3) - 1.6±0.5 mm; group 3 (n=3) - 2.4±0.8 mm. OCTA was performed on Spectralis HRA+OCT (2460 scans in total). Vessels were identified in the superficial, deep and outer layers of the tumor on En Face images. Their average number was estimated by visualization of yellow pixels in the superficial layers on 10 sagittal sections. Statistical analysis was done using Microsoft Excel, Statistica 8.0. The Kruskal-Wallis H test was used for comparative analysis of independent variables with more than two samples. RESULTS: Retinal vessels with feeding anastomoses connecting them to multiple small tortuous tumor vessels in the superficial layers were identified in group 1. Number of yellow pixels - 16.5±0.5. In the deep layers - single chaotic vascular arcades. In flat small retinoblastomas the vascular component was not evaluated. In group 2 in the superficial layers of the tumor we found multiple geniculate vessels of large and small caliber anastomosing between themselves and the retinal vessels. Number of yellow pixels was 21±0.8. A few vessels were identified in the deep and outer layers. In group 3 we identified single convoluted vessels in the superficial layers with glow and quantity increasing in the deep layers. In the deep layers - emergence of a small number of vessels. The maximum number of multiple own tumor vessels was determined in the outer layers. Number of yellow pixels - 10±0.8. CONCLUSION: The obtained results confirm the possibility to preclinically identify the angioarchitecture of small retinoblastomas in order to determine the activity of tumor growth and serve as a marker of neoplasm regression in the future, after organ-preserving treatment.

Enalaprilat as a new means of preventing the development of retinopathy of prematurity.

In a rat model of experimental retinopathy of prematurity (ROP), the safety of enalaprilat and its effect on the level of angiotensin-converting enzyme (ACE) and angiotensin-II (AT-II) in the vitreous body and retina were investigated. The study was performed on 136 newborn Wistar rat pups divided into 2 groups: group A - experimental (animals with ROP, n=64) and group B - control (n=72). Each group was further divided into 2 subgroups: A0 and B0 (n=32 and n=36, respectively) - animals that did not receive injections of enalaprilat, and A1 and B1 (n=32 and n=36, respectively) - animals treated with daily intraperitoneal (i.p.) injections of enalaprilat (0.6 mg/kg of body weight). This treatment started on day 2 and lasted either to day 7 or to day 14 in accordance with the therapeutic scheme. Animals were taken out of the experiment on day 7 and day 14. In samples of the vitreous body and retina, the content of ACE and AT-II was determined by enzyme immunoassay. On day 7 in subgroups A1 and B1 the levels of ACE and AT-II in the vitreous did not differ, while on day 14 were lower than in subgroups A0 and B0, respectively. Changes in the parameters studied in the retina were somewhat different from those found in the vitreous body. On the seventh day, the level of ACE in the retina of animals of subgroup B1 did not differ significantly from subgroup B0, and in subgroup A1 it was increased compared to subgroup A0. On day 14, its significant decrease was noted in subgroups A1 and B1 as compared with subgroups A0 and B0. At the same time, the level of AT-II in the retina of rat pups of subgroup B1 was lower than in subgroup B0, both on day 7 and day 14. On day 7, the concentration of AT-II, as well as the concentration of ACE, increased in subgroup A1 as compared to subgroup A0. On day 14, this parameter in subgroup A1 was significantly lower as compared to subgroup A0, but significantly higher than in subgroup B1. It should be noted that i.p. injections of enalaprilat, increased a death rate of animals of both groups. The use of enalaprilat, starting from the preclinical period of the ROP development, led to a decrease in the activity of the renin-angiotensin system (RAS) in ROP animals at the onset of retinopathy in the experimental model used. This opens up prospects for considering enalaprilat as a means of preventing the development of this pathology; however, the recognized high toxicity of the drug requires further studies and correction of the timing of its administration and dosage in order to achieve a balance of efficacy and safety of use in order to prevent the development of ROP in children.

[Pathogenetically oriented approach to prevention of retinopathy of prematurity (experimental study)]. / Patogeneticheski orientirovannaya profilaktika retinopatii nedonoshennykh (eksperimental'noe issledovanie).

Intraperitoneal injections of exogenous melatonin during the development of the retinal vascular system in experimental rats has been shown in a number of experimental studies on the model of EROP to prevent the appearance of histological signs of the development of experimental retinopathy of prematurity (EROP), stabilize the blood-retinal barrier and have a pronounced antioxidant effect, but pathogenetic basis for these phenomena hasn't been studied. PURPOSE: To study the influence mechanism of melatonin and its analogues on the development of EROP at the preclinical stage of the pathological process to substantiate new approaches to prevention of ROP. MATERIAL AND METHODS: The study included 42 Wistar rat pups (84 eyes) divided into 6 groups: control group, experimental group (rat pups with EROP), experimental groups who underwent injections of melatonin and its analogues K-148, AL-3, K-096. The pups were euthanized on day 7 (4-5 pups from each group at each study period), binocular enucleation was performed, and the content of hypoxia-induced factor1α (HIF-1α) and VEGF-A was determined in retinal samples. RESULTS: The intraperitoneal injections of melatonin and its analogs led to a significant decrease in the level of HIF-1α and VEGF-A in the retina of the rat pups of the experimental group until the beginning of pathological vasoproliferation. CONCLUSION: Melatonin and its analogues are able to prevent the development of EROP by reducing the level of angiogenic factors in the retina of rat pups at the stage of existing avascular zones, which allows for them to be considered as a new promising approach to preventing the development of ROP.