Distribution of sulfate groups

The distribution of sulfate groups on the surface and into the interior of beads sulfonated under conditions to yield sur-ace modification and surface plus interior modification was investigated by oxygen plasma etching (0PE)(55) of beads that were sulfonated in refluxing sulfuric and in cold sulfuric for the same time interval. The cold sulfonation yielded beads sulfonated so minimally that the sulfate group could not be detected by titration while the capacity of the beads sulfonated hot could be titrated as usual. The beads sulfonated cold are labelled surface while the other are labelled normal. The... 

Summarizing, it may be stated that the combination of size, shape, degree of sulfation, and distribution of sulfate groups endows heparin with a specific, anticoagulant activity of a type which may be different from that shown by synthetic, sulfated polysaccharides," and that inactivation appears to take place with relatively little chemical change in the molecule. The sulfation of heparin may well result in its conversion to the class of synthetic, sulfated mucopolysaccharides. 

Bioactivity of sulfated polysaccharides seems to be due to a complex interaction of structural features including sulfation level, distribution of sulfate groups along the polysaccharide backbone, molecular weight. 

However, this interpretation does not fit with the distribution of sulfate concentrations (Table I) and a more elaborate model must be found. Fig. 4 shows that samples may be divided into four groups ... 

An analysis of alcohol and alcohol ether sulfates should determine the anionic active matter, the unsulfated matter, the inorganic sulfate content, the chloride content, and water. Other more precise analysis must determine the alkyl chain distribution of the alcohol and in the case of alcohol ether sulfates the number of ethoxy groups and its distribution, as well as other more specialized determinations, such as the content of 1,4-dioxane and other impurities. 

Apparently, A-carrageenan is not a simple structure and must have some irregularity in the distribution of its sulfate groups. Also, an occasional side residue may be present. There are still unexplained points about the x-ray spectra of A-carrageenan. 

Further studies are needed to give better dose-response information and to provide a frequency distribution of the population response to oxidants alone and in combination with other pollutants at various concentrations. Such studies should include the effects of mixed pollutants over ranges corresponding to the ambient atmosphere. With combinations of ozone and sulfur dioxide, the mixture should be carefully characterized to be sure of the effects of trace pollutants on sulfate aerosol formation. The design of such studies should consider the need to use the information for cost-benefit analysis and for extrapolation from animals to humans and from small groups of humans to populations. Recent research has indicated the possibility of human a ptation to chronic exposure to oxidants. Further study is desirable. 

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