Contrast media chemical structures

Numerous positive delayed skin tests in patients with contrast medium-induced non-immediate skin reactions have been reported when the patients were tested with the culprit contrast medium [summarized in 1]. In a large European multicenter study, 37% of patients with non-immediate reactions were positive in delayed IDEs and/or patch tests [13]. The majority of the patients also reacted to the culprit contrast medium and also to other, structurally similar RCM. Notably, in more than 30% of those skin test-positive patients a RCM had been administered for the first time. Thus, there is a lack of a sensitization phase. Again it may be hypothesized that these previously non-exposed patients may have already been sensitized. Different patterns of RCM cross-reactivity indicate that several chemical entities could be involved. No positive skin tests have been obtained with other contrast medium excipients, such as ethylenediaminetetraacetic acid (EDTA), and only rarely patients have been found to react to inorganic iodide. 

Figure 7.4 shows the chemical structure of PHA copolymers composed of 3HB units and Cg-Cj4 numbered R-3-hydroxyalkanoate emits. The latter group of monomers have been classified as the medium-chain length (MCL) R-3-hydroxyalkanoates and the PHA made of these monomers are termed PHA l. In contrast to PHAjcl made of short-chain length hydroxyalkanoates (C4-C5), PHAj l thermoplastic elastomers with melting points... 

Optical rotations [a] d of the two polymers were found to be different, although identical chemical structures (except end groups) were expected according to the literature [34]. In order to clarify the origin of these differences, ORD measurements of polymers and of the monomer (VI) taken as a suitable model compound were undertaken. Rotatory powers and ORD were found to be strongly dependent on the polycondensation medium (Figure 6). In a first step it was found that the polymer prepared in alkaUne condition and the model compound showed very similar ORD in dioxane and both obeyed the one-term DRUDE equation. In contrast, ORD of the polymer prepared in acidic condition was complex and obeyed the Moffitt equation withflio> and Xq constants respectively +492,-755 and 212 quite similar to constants found for helical polypeptides [35, 36]. 

The formulations of the lipiodol W/O/W emulsion developed by us and the conventional emulsions for TAB (Nakamura et al., 1989) are shown in Table 11.6, together with their physical properties. All the materials used are injectable. The anticancer agent used was Farmorubicin (FARM), which is a powder mixture of eptrubicin hydrochloride (BPI) and lactose. The aqueous contrast medium used was Omnipaque 240 , which is an aqueous solution of 517.7mg/ ml iohexol, 0.1 mg/ml ethylenediaminetetraacetic acid disodium calcium, and 1.21 mg/ml tris(hydroxymethyl)aminomethane. The chemical structures of BPI... 

A stress that is describable by a single scalar can be identified with a hydrostatic pressure, and this can perhaps be envisioned as the isotropic effect of the (frozen) medium on the globular-like contour of an entrapped protein. Of course, transduction of the strain at the protein surface via the complex network of chemical bonds of the protein 3-D structure will result in a local strain at the metal site that is not isotropic at all. In terms of the spin Hamiltonian the local strain is just another field (or operator) to be added to our small collection of main players, B, S, and I (section 5.1). We assign it the symbol T, and we note that in three-dimensional space, contrast to B, S, and I, which are each three-component vectors. T is a symmetrical tensor with six independent elements ... 

The oxidation of racemic fenchone by a Corynebacterium sp.[7<>1 (reclassified as Mycobacterium rhodochrous), an organism which grows at the expense of either (+)- or (-)- camphor, has also been reported. This was shown to lead, in a 45% yield, to a 90/10 mixture of 1,2 and 2,3-fencholides, as shown in Fig. 16.5-12. This result contrasts with the chemical oxidation of fenchone with peracetic acid, where 2,3-fencholide is the major product in a 40/60 mixture. Accumulation of these lactones is a priori surprising as compared with the total degradation of the structurally similar camphor substrate. However this may simply be due to the fact that this lactone, unlike that formed from camphor, is chemically stable in the medium. Of course, one has also to assume that, here again, the strain is devoid of any lactone hydrolase. This bioconversion was the first gram-scale preparative report... 

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