Fluorescence eXclusion Measurement of volume in live cells.

Volume is a basic physical property of cells; however, it has been poorly investigated in cell biology so far, mostly because it is difficult to measure it precisely. Recently, large efforts were made to experimentally measure mammalian cell size and used mass, density, or volume as proxies for cell size. Here, we describe a method enabling cell volume measurements for single living cells. The method is based on the principle of fluorescent dye exclusion and can be easily implemented in cell biology laboratories. As this method is very versatile, it can be used for cells of different sizes, adherent or growing in suspension, over several cell cycles and is independent of cell shape changes. The method is also compatible with traditional cell biology tools such as epifluorescence imaging or drug treatments.

[Modern opportunities and prospects for studying pathogenesis, diagnosing and treating hereditary optic neuropathies].

OBJECTIVE: To evaluate modern opportunities and prospects for studying pathogenesis and improving diagnostics and treatment of hereditary optic neuropathies (HON). MATERIAL AND METHODS: The article presents summarized data on the pathogenesis, diagnostics, and treatment of HON based on modern methods of assessment. RESULTS: The results of long-term worldwide studies and those performed in the Research Institute of Eye Diseases in collaboration with several other institutions are presented. Genetic testing for mitochondrial and nucleus DNA mutations that have a known association with Leber's hereditary optic neuropathy (LHON) and autosomal dominant optic neuropathy (ADON) allow verification only in half of the cases. Particular features of hereditary diseases, such as incomplete penentrance, variable expression, clinical polymorphism, difficulties in detection of hereditary sings, and genetic heterogeneity, are shown to complicate the diagnosis of HON. Spectral retinal tomography revealed characteristic morphometric changes in the macular region and peripapillary nerve fiber layer in the acute stage of LHON. Hereditary optic neuropathies result from a genetically determined decrease in mitochondrial respiratory chain complexes activity, which is associated with a decrease in ATP production. From that standpoint, studying of mitochondrial oxidative phosphorylation biochemical defects in LHON and ADON is an option for detection of mitochondrial dysfunction. Results of a newly proposed method of mitochondrial membrane potential assessment in skin fibroblasts, which can be used for differential diagnosis of mitochondrial optic nerve diseases, are presented. Possible therapeutic measures for HON are discussed. CONCLUSION: In the prevailing number of cases the described clinical, molecular genetic, and cytological methods ensure proper diagnosis of hereditary optic neuropathies. Prospects of HON treatment, rather ambiguous, are associated with further studying of pathogenesis, development of drugs and gene therapy.