Synergistic absorption

We conclude that when the donor and acceptor molecules are closely located relative to molecular dimensions, the analogy between synergistic absorption and emission processes and the interaction breaks down. We now need to think about in terms of local interactions between the donor and... 

More recently, a comparison was made of the oral bioavailability in mice and dogs of a formulation prepared from a kava extract (WS 1490, containing 70% kavalactones), with the extract itself and the pure compound (+)-kavain. In both species, bioavailability increased in the order, pure compound, extract, and extract formulation. The data confirm the above findings on the synergistic absorption and uptake of kavalactones, and indicate that clinical data from one prepauation or formulation cannot simply be transferred to other formulations without appropriate biopharmaceutical characterization (Biber etal., 2000). 

Figure 4. Energy-level diagram for single-beam synergistic absorption. The pairwise...

Figure 8. Typical time-ordered diagrams for the most general case of synergistic absorption with two-beam excitation of a chemically dissimilar pair of molecules (a) relates to the cooperative mechanism and (b) the distributive mechanism.

Figure 10. Resonance energy levels for single-beam synergistic absorption. The levels indicated by dashed lines represent resonances that can be exploited in absorption based on either the cooperative or the distributive mechanism the dotted lines represent a resonance condition that applies to only the distributive case.

For two-frequency synergistic absorption, the vaiious resonance possibilities are also summarized in Table VIII. For cooperative mean-frequency absorption, there are again three distinct possibilities for resimance enhancement of the process, as shown by the lowest three broken lines in Fig. 11. If the centers involved in the process possess energy levels close i o ( q + ftcui) or ( q + 0)2), then although the molecular tensors or S° ((U2) are resonantly... 

In assessing the wider significance of mean-frequency absorption for flash photolytic experiments based on USLS radiation, perhaps the most important factor to consider is the enormously wide range of possibilities for synergistic absorption leading to the simultaneous excitation of more than one excited state. For example, with a s ngle-component sample, it should be possible to observe the process... 

PTH has a dual effect on bone cells, depending on the temporal mode of administration given intermittently, PTH stimulates osteoblast activity and leads to substantial increases in bone density. In contrast, when given (or secreted) continuously, PTH stimulates osteoclast-mediated bone resorption and suppresses osteoblast activity. Further to its direct effects on bone cells, PTH also enhances renal calcium re-absorption and phosphate clearance, as well as renal synthesis of 1,25-dihydroxy vitamin D. Both PTH and 1,25-dihydroxyvitamin D act synergistically on bone to increase serum calcium levels and are closely involved in the regulation of the calcium/phosphate balance. The anabolic effects of PTH on osteoblasts are probably both direct and indirect via growth factors such as IGF-1 and TGF 3. The multiple signal transduction... 

Barnard and colleagues119 reported a powerful absorption band at 1040 cm"1 for sulphoxides, where absorption was proportional to concentration. Oba120 utilized this wavelength for a rapid determination of the synergistic insecticide Sulfox-Cide , 1,2-... 

Prolonged administration of loop diuretics can lead to a second type of diuretic resistance. Enhanced delivery of sodium to the distal tubule can result in hypertrophy of distal convoluted cells.17 Subsequently, increased sodium chloride absorption occurs in the distal tubule which diminishes the effect of the loop diuretic on sodium excretion. Addition of a distal convoluted tubule diuretic, such as metolazone or hydrochlorothiazide, to a loop diuretic can result in a synergistic increase in urine output. There are no data to support the efficacy of one distal convoluted tubule diuretic over another. The common practice of administering the distal convoluted tubule diuretic 30 to 60 minutes prior to the loop diuretic has not been studied, although this practice may first inhibit sodium reabsorption at the distal convoluted tubule before it is inundated with sodium from the loop of Henle. 

Dimalone [bicyclo-(2.2.1)-5-heptene-2,3-dicarboxylic acid dimethyl ester] and Octa-cide 264 [the V-octyl imide of bicyclo-(2.2.1)-5-heptene-2,3-dicarboxylic acid] do produce a red color with an absorption maximum in the same region as that obtained in the analysis of Compound 118. However, because Dimalone is an insect repellent and Octacide 264 is a pyrethrum synergist, neither of these products is likely to be encountered in commercial mixtures of Compound 118. The response to the colorimetric test for Compound 118 of some chemicals commonly used for insect control is listed in Table V. 

Mobile colorless liquid with a pungent odor like mustard detectable at 0.8 ppm. This material is hazardous through inhalation, skin absorption, penetration through broken skin, and ingestion, and produces local skin/eye impacts. Acts synergistically with alcohol in blood. 

Experiments in this study, done exclusively with midge larvae, include 1) 24-hr toxicity data for representative insecticides, with and without synergists 2) in vivo absorptive uptake and metabolic studies of aldrin and dieldrin, with and without piperonyl butoxide (PBO) 3) body depuration rate (loss to water) for dieldrin 4) determination of optimal in vitro... 

The combination of various chemical types of polymer networks in different compositions, resulting frequently in controlled, different morphologies, has produced IPNs with synergistic behavior. Thus, synergistic properties may be obtained by IPNs such as enhanced tensile and impact strength, improved adhesion and, in some cases, greater sound and shock absorption (4-7). 

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