4 research outputs found
Mild depolarization of the inner mitochondrial membrane is a crucial component of an anti-aging program.
The mitochondria of various tissues from mice, naked mole rats (NMRs), and bats possess two mechanistically similar systems to prevent the generation of mitochondrial reactive oxygen species (mROS): hexokinases I and II and creatine kinase bound to mitochondrial membranes. Both systems operate in a manner such that one of the kinase substrates (mitochondrial ATP) is electrophoretically transported by the ATP/ADP antiporter to the catalytic site of bound hexokinase or bound creatine kinase without ATP dilution in the cytosol. One of the kinase reaction products, ADP, is transported back to the mitochondrial matrix via the antiporter, again through an electrophoretic process without cytosol dilution. The system in question continuously supports H <sup>+</sup> -ATP synthase with ADP until glucose or creatine is available. Under these conditions, the membrane potential, ∆ψ, is maintained at a lower than maximal level (i.e., mild depolarization of mitochondria). This ∆ψ decrease is sufficient to completely inhibit mROS generation. In 2.5-y-old mice, mild depolarization disappears in the skeletal muscles, diaphragm, heart, spleen, and brain and partially in the lung and kidney. This age-dependent decrease in the levels of bound kinases is not observed in NMRs and bats for many years. As a result, ROS-mediated protein damage, which is substantial during the aging of short-lived mice, is stabilized at low levels during the aging of long-lived NMRs and bats. It is suggested that this mitochondrial mild depolarization is a crucial component of the mitochondrial anti-aging system
ОЦЕНКА КОНСТРУКТИВНОГО СТЕНОЗА МЕХАНИЧЕСКИХ КЛАПАНОВ СЕРДЦА У ВЗРОСЛЫХ В АОРТАЛЬНОЙ ПОЗИЦИИ: ПРЕИМУЩЕСТВО ПОЛНОПРОТОЧНОГО ПРОТЕЗА КЛАПАНА СЕРДЦА
The analysis of transprosthetic hemodynamics in adults after aortic valve replacement in the Bakoulev Center for Cardiovascular Surgery in 2007–2010 demonstrated the hemodynamic advantage of the concept of new full-flow mechanical aortic valve prosthesis «CorBeat». Having the same size of internal orifice and tissue annulus diameters, the values of transprosthetic parameters (peak and mean gradients, blood flow velocities) through «CorBeat» were close to physiological values of transvalvular native aortic parameters and had a tendency to be not dependent on the size of prosthesis (p =0,63). In the article for the first time a morphometric database of geometric values of internal orifice area of normal native aortic valves in adults was used taking into account both the gender and the body surface area’s of a patient. There was also used the standardized prosthesis size Z-score which represents the number of SDs by which the internal prosthesis area differs from the mean normal native aortic valve area for the patient’s body surface area. The article emphasizes the need of the personal selection of the size and the type of prosthesis for any patient as well as the need for new design development of prosthetic heart valves. Количественный анализ транспротезной гемодинамики протезов клапанов сердца у взрослых пациентов, перенесших протезирование аортального клапана в НЦССХ им. А.Н. Бакулева РАМН в 2007–2010 гг., продемонстрировал функциональное преимущество первой конструктивной версии полнопроточного протеза «КорБит». При одинаковых по сравнению с другими типами механических протезов посадочных размерах и геометрических площадях отверстия значения транспротезных градиентов и скоростей на протезах «КорБит» показали тенденцию к независимости от посадочного размера (p =0,63). При анализе эффективности новых протезов были впервые использованы нормативная база геометрических значений проходной площади аортальных нормальных клапанов у взрослых, учитывающая пол пациента и площадь поверхности тела, и стандартизированный параметр протеза Z-score, указывающий, на какое число среднеквадратичных отклонений отличается площадь проходного отверстия протеза от площади нативного (нормального) аортального клапана. В работе подчеркивается актуальность задачи персонального подбора размеров и типа протеза для каждого больного и подтверждается необходимость поиска новых конструктивных решений протезов клапанов сердца.