Ultrastructural changes in the chorioretinal complex of the rat after inducing form-deprivation axial myopia only, diabetic retinopathy only and diabetic retinopathy in the presence of myopia

Purpose: To determine the features of the microstructure of choreoretinal complex in rats with diabetes induced by streptozotocin in the presence of axial myopia. Material and Methods: Fifty-five Wistar rats (110 eyes; age, 2 weeks to 14 weeks) were used in experiments. Four groups were formed: group 1 (axial myopia only); group 2 (diabetes only); group 3 (both myopia and diabetes); and group 4 (controls; intact animals). High form-deprivation myopia was produced in two-week animals by surgically fusing the eyelids of both eyes and these animals were maintained under conditions of reduced illumination for two weeks to induce a more intense myopization of the globe. Eyelid sutures were removed on completion of these two weeks. Two weeks thereafter, type 2 diabetes mellitus was induced in rats with induced axial myopia and intact rats. A 50 mg/kg intraperitoneal streptozotocin injection for 5 days was used for this purpose. Elongated axial length and increased anterior chamber depth as measured by in vivo ultrasound were an objective criterion of the development of myopia in experimental animals. A glucose level of ≥ 4.5 mmol/L was a criterion of the development of diabetes. Two months after inducing diabetes, 14-week rats were sacrificed, and their eye tissue samples were processed by a routine method and assessed by electron microscopy. Ultrastructure of the choroid, RPE, and retinal photoreceptor cells were examined. Ultra-thin sections were cut, stained with lead citrate according to the procedure described by Reynolds, and observed with a PEM-100-01 Transmission Electron Microscope. Results: Our ultrastructural study found that myopization of the rat globe with elongation of the axial length somewhat reduced the severity of some ultrastructural changes in the choreoretinal complex in induced type 2 diabetes due to reduced choroidal swelling and dominance of compensatory processes with increased energy producing, protein synthesis and other functions in the endothelial vessels and choriocapillaries as well as RPE cells. Out findings seem to corroborate the concept that myopized eyes have capacity to somewhat buffer the development of severe diabetic retinopathy, likely due to some compensatory-and-restorative processes

Effect of experimental type 2 diabetes complicated by pyelonephritis on ultrastructural changes in the choroid, retina and nephrons

The clinical and morphological picture of diabetic microangiopathy is rather specific. Diabetic retinal ischemia can lead to irreversible damage to retinal neural elements and choroidal capillaries. Diabetic nephropathy can lead to progressive renal dysfunction and chronic renal failure. Choroidal and retinal capillaries are structurally and functionally similar to those of the intestinal mucosa and renal tissue. Purpose: To assess vascular ultrastructural changes in the choroid, retina, and renal glomerular and tubular system in a rat model of pyelonephritis in the presence of type 2 diabetes. Material and Methods: Samples were obtained from 95 Wistar rats divided into three groups: group 1 (or control group) of 30 intact animals; group 2 of 15 animals with type 2 diabetes induced by intraperitoneal streptozotocin 15.0 mg/ kg for 5 consecutive days; and group 3 of 50 animals with acute pyelonephritis in the presence of type 2 diabetes (streptozotocin 35.0 mg/kg on 2 days spaced by a week). Acute pyelonephritis was induced by Escherichia coli administration (107 CFU/kg) rectally. The ultrastructure of rat choroidal, retinal and renal glomerular-and-tubular vessels was examined with electron microscopy (PEM- 100-01 electron microscope). Results: In rats with induced type 2 diabetes, the most significant ocular vascular changes and renal vascular changes were found in endothelial cells. These changes included findings of vacuolar degeneration in some epithelial cells, basal membrane thickening and focal necrosis of individual epithelial cells. Vessel lumens appeared focally narrowed or expanded, with red blood cells forming clumps or sludge in lumens. Some capillaries were obliterated. These changes obviously caused secondary changes in the surrounding structures. Common ocular changes included focal destruction in retinal pigment epithelium cells, destruction of retinal photoreceptor inner segments and choroidal stromal edema. Common renal changes included destruction of the podocytes of the glomerular capillary network and homogenization of the basal membrane. Vascular ultrastructural changes in the renal glomerular system were more marked in rats with experimental type 2 diabetes and pyelonephritis than in those with type 2 diabetes only. Conclusion: Electron microscopy micrographs demonstrated the ultrastructural changes in the retinal and uveal vascular systems which were of a similar type to those in the renal glomerular-and-tubular system in rats with experimental pyelonephritis in the presence of type 2 diabetes

Effect of experimental type 2 diabetes complicated by pyelonephritis on ltrastructural changes in the choroid, retina and nephrons

Background: The clinical and morphological picture of diabetic microangiopathy is rather specific. Diabetic retinal ischemia can lead to irreversible damage to retinal neural elements and choroidal capillaries. Diabetic nephropathy can lead to progressive renal dysfunction and chronic renal failure. Choroidal and retinal capillaries are structurally and functionally similar to those of the intestinal mucosa and renal tissue. Purpose: To assess vascular ultrastructural changes in the choroid, retina, and renal glomerular and tubular system in a rat model of pyelonephritis in the presence of type 2 diabetes. Material and Methods: Samples were obtained from 95 Wistar rats divided into three groups: group 1 (or control group) of 30 intact animals; group 2 of 15 animals with type 2 diabetes induced by intraperitoneal streptozotocin 15.0 mg/kg for 5 consecutive days; and group 3 of 50 animals with acute pyelonephritis in the presence of type 2 diabetes (streptozotocin 35.0 mg/kg on 2 days spaced by a week). Acute pyelonephritis was induced by Escherichia coli administration (107 CFU/kg) rectally. The ultrastructure of rat choroidal, retinal and renal glomerular-and-tubular vessels was examined with electron microscopy (PEM-100-01 electron microscope). Results: In rats with induced type 2 diabetes, the most significant ocular vascular changes and renal vascular changes were found in endothelial cells. These changes included findings of vacuolar degeneration in some epithelial cells, basal membrane thickening and focal necrosis of individual epithelial cells. Vessel lumens appeared focally narrowed or expanded, with red blood cells forming clumps or sludge in lumens. Some capillaries were obliterated. These changes obviously caused secondary changes in the surrounding structures. Common ocular changes included focal destruction in retinal pigment epithelium cells, destruction of retinal photoreceptor inner segments and choroidal stromal edema. Common renal changes included destruction of the podocytes of the glomerular capillary network and homogenization of the basal membrane. Vascular ultrastructural changes in the renal glomerular system were more marked in rats with experimental type 2 diabetes and pyelonephritis than in those with type 2 diabetes only. Conclusion: Electron microscopy micrographs demonstrated the ultrastructural changes in the retinal and uveal vascular systems which were of a similar type to those in the renal glomerular-and-tubular system in rats with experimental pyelonephritis in the presence of type 2 diabetes

Вплив тридцятиденної тампонади перфторорганічними сполуками на ультраструктуру сітківки кролика

Experimental study was performed on 12 (24 eyes) rabbits. All animals underwent back closed subtotal vitrectomy, followed by a 30-day tamponade perfluororganic compound (PFOC) of the right eye, lightweight silicone or saline (left eye). Electron microscopic examination was carried out after 7, 14 and 30 day tamponade. After a 30-day tamponade with the compounds, the structures of the retina respond with similar changes. However these changes were reactive, not damaging, and they are reversible. The compounds can be used for momentary tamponade.Экспериментальное исследование было проведено на 12 кроликах (24 глаза). Всем животным была выполнена задняя закрытая субтотальная витректомия с последующей 30-суточной тампонадой перфторорганическим соединением (ПФОС) – правый глаз; «легким» силиконовым маслом или физраствором (левый глаз). Электронно-микроскопическое исследование было проведено после завершения тампонады через 7, 14 и 30 суток. После 30-суточной тампонадыприменяемых веществ, структуры сетчатки отвечают однотипными изменениями. Однако эти изменения относятся к разряду реактивных, а не повреждающих, и носят обратимый характер. ПФОС могут рассматриваться как кандидаты для проведения кратковременной тампонады.Експериментальне дослідження було проведено на 12 кроликах (24 ока). Всім тваринам була виконана задня закрита субтотальна вітректомія з наступною 30-денною тампонадою перфторорганічною сполукою (ПФОС) – праве око, «легким» силіконом або фізрозчином (ліве око). Електронно-мікроскопічне дослідження було проведено після завершення тампонади 7, 14 і 30 днів. Після 30-денної тампонади використаними сполуками структури сітківки відповідають однаковими змінами. Проте ці зміни реактивні, а не пошкоджувальні і мають оборотний характер. ПФОС можуть розглядатися як кандидати для короткочасної тампонади

Использование линейно-интерполирующего фильтра для точного измерения времени затухания свободных колебаний возбужденных в LC-контуре

The availability of detector with linear interpolating filter for oscillations attenuation time sensitive measurement is considered in article. The necessity of such approach for sesitive measurement is proved. The functional structure of detector with linear interpolating filter and schematic circuit based on it is proposed. Model-based analysis was carried out; expediency of employing such type of detectors is proved.В встатті розглядається можливість застосування детектора з лінійно-інтерполюючим фільтром для точного вимірювання часу загасання вільних коливань в контурі. Обгрунтовується доцільність такого підходу. Запропоновані функціональна та принципова схеми детектора з лінійно-інтерполюючим фільтром Проведено моделювання, яке підтвердило доцільність застосування такого детектора для вимірювань.W artykule rozważa się oraz uzasadnia się możliwość zastosowania liniowo interpolującego filtru dla dokładnego pomiaru zanikania swobodnych drgań generowanych w układzie LC. Zaproponowano schemat detektora z takim filtrem i wykonano teoretyczne modelowanie. (Możliwość zastosowania liniowo interpolującego filtru do dokładnego pomiaru zanikania swobodnych drgań w układzie LC