Telomeres are essential structures at chromosome termini required for an accurate segregation of eukaryotic chromosomes. The structure and length of telomeres change after each cell cycle and the nature of this change depends on the cell type. In the case of human primary somatic cells, telomeres gradually shorten after each cell cycle until their structure becomes incompatible with the further progression through the cell cycle, i.e., structurally dysfunctional telomeres activate cellular DNA damage response and can lead to genomic instability. In the case of immortalized human cells or cancer cells, telomere size and structure fluctuate as a result of cell proliferation, but telomeres usually do not shorten because telomerase, an enzyme that synthesizes telomeric sequences, is active in these cells. The importance of telomeres from the clinical perspective is illustrated by at least two major observations. First, there is a correlation between telomere length on one side and either the cell senescence in vitro and possibly in vivo or individual mortality rate on the other side. Second, the enzyme telomerase, which is active in most human cancers, provides cells with the means to indefinitely maintain telomeres and as a result make them immortalized, suggesting that the inhibition of this enzyme could be an effective way to stop cancer cell growth. A major prerequisite for making the above two observations useful in the clinical practice is the capacity to measure telomere length with a high degree of accuracy. At present there are three main methods for telomere length measurement: Southern blot analysis, quantitative fluorescence in situ hybridization (Q-FISH), and flow-FISH. The most informative of these three methods is Q-FISH and this article will describe the principles of Q-FISH and discuss the advantages and disadvantages of Q-FISH in comparison with other methods.

Getting Started With Dumbbells

Getting Started With Dumbbells

The use of dumbbells gives you a much more comprehensive strengthening effect because the workout engages your stabilizer muscles, in addition to the muscle you may be pin-pointing. Without all of the belts and artificial stabilizers of a machine, you also engage your core muscles, which are your body's natural stabilizers.

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