Structural alterations

Dealloyed areas are structurally altered. Corroded areas are weak and porous, causing fracture and weeping leaks. 

Derbyshire, F. J., Vitrinitc structure alterations with rank and processing. Fuel, 1991,70, 276 284. 

The reduced symmetry of the chromophore, which still contains 187t-electrons and is therefore an aromatic system, influences the electronic spectrum which shows a bathochromic shift and a higher molar extinction coefficient of the long-wavelength absorption bands compared to the porphyrin, so that the photophysical properties of the chlorins resulting from this structural alteration render them naturally suitable as pigments for photosynthesis and also make them of interest in medical applications, e.g. photodynamic tumor therapy (PDT).2... 

Hypervitaminosis A is characterized by hepatomegaly, cerebral edema and bone structure alterations. (3-Carotene... 

Freshour G., R. P. Clay, M. S. Fuller, P. Albersheim, A. Darvill and M. G. Hahn. (1995). Developmental and tissue-specific structural alterations of the cell wall poysaccharides of Arabidopsis thaliana roots. Plant Physiology 110 1413-1429. 

The distribution of open channel times is mainly determined by the rate constants S and K (2 is assumed to be very small). Mutations which change the C to O transition (e.g., the burst size of channel opening) have not been characterized yet. However, structural alterations which affect k and thereby the level of steady state inactivation have been described for Sh channels [29,60]. Different splice variants of Sh channels... 

Arylpiperazines have immensely important effects on various and diverse biological targets, in particular on CNS receptors. In the case of serotonin (5-HT) receptors, compounds containing this arylpiperazine moiety represent the largest systematically studied class of 5-HTia receptor ligands [63]. Structural alterations within long-chain arylpiperazines (LCAPs) occur mainly at the two opposite ends of a molecule and have been described by many authors [64-71]. 

Human chronic inflammatory diseases are characterized by populations of cells with altered regulation and function. A large body of evidence suggests that many of these cellular abnormalities may be linked to an increase in the production of free radicals and/or deficiencies of antioxidant defence systems. Oxygen free radicals attack cell structures, altering their function, and are cytotoxic. They have therefore been implicated in the pathogenesis of rheumatoid arthritis as well as many other human diseases (HaUiwell, 1991). 

Inhibitors of AR have been demonstrated to prevent a wide variety of biochemical, functional and structural alterations in animal models of diabetes. Early studies demonstrated arrest of both early cataract development and nerve conduction velocity. At least 30 clinical trials of AR inhibitors have been published involving nearly 1000 patients in total. However, there is little impressive data of their efficacy up to now but, rather than undermine the hypothesis linking excess polyol pathway activity to diabetic complications, it may reflect methodological difficulties and trial design errors. 

Because of continued interest in the in situ degradation products of both DDT and parathion, preliminary spectrophotometric evidences, which are also indicative of structural alterations and/or changes in composition, have been secured with extracts of navel oranges previously treated with standard formulations of these compounds. 

As we stated above, there is a risk involved in the use of the Cheng-Prusoff relationships for SAR studies, as it is possible that structural alterations of the lead analogues could change the inhibition modality. This can be check from time to time for compounds that represent the greatest structural excursions from the lead molecule. Additionally compounds that are destined for progression into cellular and animal models should have their inhibition modality and affinity confirmed by running the more comprehensive studies discussed in Section 5.3. 

Most enzymes are very specific in their activity, and each chemical reaction in a living organism requires a specific enzyme. Their specificity arises from what is known as an active site, a location in the enzyme s molecule that has a shape matching that of a part of the molecule with which it reacts. The activity of the enzymes is affected by such factors as temperature and pH, each enzyme functioning best within a specific range of temperatures and pH. Outside this range the enzymes are structurally altered and their activity is either impaired or terminated. 

DNA and RNA quantification, SNP typing, hybridization, and structural alteration have been widely carried out by modified oligonucleotides possessing pyrene derivatives [104-113]. As is known, pyrene-1-carboxaldehyde fluorescence is considerably dependent on solvent polarity [114], being strong in methanol but insignificant in nonpolar solvents [115]. Owing to this property, Tanaka and collaborators developed a pyrenecarboxamide-tethered modified DNA base, PyU 46, and applied it to SNP discrimination in DNA [116-120],... 

Bonadio, J. and Byers, P.H. (1985) Subtle structural alterations in the chains of type-I procollagen produce osteogenesis imperfecta type-II. Nature 316, 363-366. 

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