A toxicological examination of a substance is used to estimate the probable adverse effects of a given dose of the substance. 1 To estimate harm the substance is administered to a number of test animals (e.g. rats or mice). The mortality and clinical signs of the test animals are then recorded. After setting a no-observed adverse effect level and comparing results from the test with historical controls, the substance can be classified as “safe” or “harmful”.
The titer of infectious virus in the blood of patients and donors is measured to identify carriers of virus infection and to determine the extent of their infection. To accomplish this, blood is taken and the virus is first quantitated with standard materials. Then different concentrations of the virus are used to infect tissue culture cells. All total, cells are undamaged and a viable titer (infectious titer) of per culture is provided.
These methods are used to predict the function or expression of a gene. (1) Ligase chain reaction (LCR) allows the DNA sequence of a gene to be determined and, in some cases, amplified for easy detection. The DNA sequence is used to create a synthetic single-stranded DNA probe or complementary RNA probe, which is used for hybridization with the target DNA. Hybridization is then detected by some means. 2) Real-time LCR (TLCR) is the same as LCR except that the separation of the probe from the target DNA is removed. This allows real-time analysis of the process.
CLSI has developed a system in which panelists evaluate and rate bacteria according to their degree of pathogenicity. Samples are incubated in the panelist’s laboratory series, and rated by the panelist. This procedure is specific for the type of sample.
A bacterial suspension is used to rehydrate each of the wells. After incubation, some of the wells will have color changes due to pH differences: others produce end products that must be identified with reagents. A profile number is determined from the sequence of positive and negative test results, then looked up in a codebook to identify the bacterial isolate. d2c66b5586