Dose probes

Dose Probes. Dose probe protocols (see Figure 5.1) are of value when one needs the information supplied by a traditional protocol but has no preliminary data from... 

TABLE 5.1. Dosage Selection for the Two-Step Dose-Probing Protocol Design... 

FIGURE 5.2. Example of dose probe method with delayed deaths. Source Schultz and Fuchs, 1982. 

The detection of trace levels of residual DNA in protein products is a formidable challenge, primarily due to the extremely low detection limits required (e.g., 10-100 pg/dose). Probe hybridization, using a radiolabeled DNA probe derived from host cell DNA, has been in the method most commonly used, due to the extraordinary sensitivity of the assay. However, it is important to remember that this assay will recognize only DNA complementary to the labeled probe (i.e., other forms of DNA will not be recognized in the assay). Several techniques are now available for general detection of DNA at relatively low levels, and these methods are expected to come into more widespread use in the future. One such method is based on the use of DNA binding proteins in a format similar to an ELISA assay. 

The comparison of fish bioassays (6) with the calculated effective doses indicate that the two most potent brevetoxins, PbTx-1 and PbTx-7, also are most effective at displacing tritiated probe from its specific site of action. The considerably lower potency of brevetoxins PbTx-5 and PbTx-6 in the rat system suggest that these two toxins may bind with lesser affinity to site 5. In a general sense, this is indicated in Table II, and is summmarized in Table III. 

High-purity lead oxide is used to make precision glasses needed for lasers, low-dose X-ray machines, fiber optic probes, medical camera systems, and low-light military equipment such as night vision scopes and goggles. 

Dose C, Seitz O (2008) Single nucleotide specific detection of DNA by native chemical ligation of fluorescence labeled PNA-probes. Bioorg Med Chem 16 65-77... 

To study the effect of PGDN on cerebral blood flow, Godin et al. (1995) injected male Sprague-Dawley rats (through a jugular vein cannula) with PGDN at 0.1 to 30 mg/ kg and measured cerebral blood flow with a fiberoptic laser-Doppler flow probe in contact with the brain. Following a small initial drop in cerebral perfusion that lasted 1 min, blood flow rapidly increased and reached a maximum 2 min after injection. The increase in perfusion was correlated with dose, but due to the small number of animals and individual variability, a clear dose-response relationship was not obtained. 

---