Dosage response

The effect of mechanical treatment on floe behavior is illustrated in Figure 5. In one work (40), identical slurries were treated with varying doses of the same polymer. At each dosage, it can be assumed that the same type of floe formed at the same rate. However, the dosage response was completely different depending on which parameter of the flocculated slurry was measured. Thus the term optimal flocculation caimot be appHed to any flocculant—substrate combination if the soHd—Hquid separation process or process parameter is not specified. 

Zimmerman and Briggs explain their dosage response curves on the basis of three independent pigment systems. However, for several reasons it appears more reasonable to ascribe their complicated patterns to different secondary rather than to distinct primary processes. First, the first and second positive curvatures show essentially the same action spectra (Fig. 3 4 and 5). Second, the Bunsen-Roscoe law holds only for the first 100 s of irradiation. After that time factors other than photochemical ones clearly govern phototropism. Third, the dosage response curves are not real kinetics, i.e. they do not represent continuous traces of bending in time, as the authors assume for their calculations. However, curvature was allowed to develop for 100 min in darkness, measured and plotted as a function of dosage. 

Fig. 2. Phototropic dosage response curves for oat coleoptiles at three intensities of blue light (440 nm) (7) 1.4 10-11, (2)...

FIGURE 5.8. Examples of probit-log dosage response curves illustrating differences in slope curves and the relationship between the slope, LD50, and LD0i. 

It is interesting, as noted by Clark,2 that the dosage-response relationships when intact animals are used appear simpler than when specific tissues, such as the epidermis, are used as test objects. He suggests that this simplicity is apparent rather than real because, in... 

Automatic Control. In some industries, the waste streams can vary in composition over a relatively short lime period When the solids level of a slurry changes, the entire dosage response may change. Automatic systems are available for thickeners that adjust the dosage according to the incoming solids level, overflow turbidity, and streaming current potential. 

This same qualitative difference between adrenaline and noradrenaline obtains for the splenic artery/splenic vein equipressor dosage-response ratios as well, and both observations quite possibly may find their explanation in the recent work of Euler (64-70). He has found that the pressor substance isolated from the heart, blood, liver, and spleen has predominantly the characteristics of noradrenaline. Thus, he has considered Sympathin E to be identical with Z-noradrenaline. 

Craker (40) and Feder and Sullivan (41) have been able to build a dosage response curve for Lemna (Duckweed) which relates the ozone concentration, length of exposure, and percent chlorophyll destruction on a fresh weight basis by using a Spectronic 20. This technique makes it possible to quantify injury caused by ozone and to relate this injury to a particular dose rate for any plant. 

The concentration of choice for mode of action studies is the lowest drug concentration which inhibits growth entirely. This can either be estimated by extrapolation of the probit-transformed log dosage response correlation or by determination of the MIC, ie. minimal inhibitory concentration, by the method of serial twofold dilution of drug-containing medium in test tubes, inoculation of these media and visual observation of growth after incubation overnight. 

The dose of pork insulin for patients with insulin resistance caused by antibodies to beef insulin may be only a fraction of that of beef insulin. Insulin resistance is frequently self-limited after several weeks or months of high dosage, responsiveness may be regained and dosage can be reduced. Insulin resistance is a common feature of insulinoma and can be shown even... 

There is great variability in the frequency and severity of acute pain episodes associated with SCD. Thus the pain should be assessed and analgesic therapy should be tailored for each patient. Pain scales can be useful to quantify the degree of pain. Several pain assessment tools are available. Unfortunately, they have not been validated for sickle ceU pain. The health care provider should choose one tool appropriate for age and use it routinely to assess pain. Other useful information to guide choice of analgesics should include previous effective agents and their dosages, response to therapy and previous clinical course, and duration of pain crisis... 

There are many requirements for adequate assay. The reference material should have the same type of absorption phenomenon as the experimental material. In other words, it is not usually productive of parallel and therefore comparable dosage response curves if an esterified, slowly absorbed preparation is compared with a rapidly absorbed compound. All tests must be applied with intelligence and care. 

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