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A Wichman

Publications and source records attributed to A Wichman.

24 records · Page 2Linked to original sources
PubMed1979

Affinity chromatography of human plasma low- and high-density lipoproteins. Elution by selective cleavage of a bond in the spacer.

Human plasma low- and high-density lipoproteins were found to bind to Sepharose gels containing coupled cholesterol or cholic acid. The lipoproteins were bound very strongly, and it was not possible to elute them under non-denaturing conditions. The detergents Triton X-100 and sodium dodecyl sulphate eluted the lipoproteins in partly denatured form. Adsorbents were used where the steroid was coupled through a spacer containing a thiol ester bond. It was thus possible to elute bound lipoproteins by selective cleavage of the bond with hydroxylamine. A small proportion of albumin was the only contaminant detected, the amounts depending on which ligand was used. Low- and high-density lipoproteins were separated by gel filtration. They behaved as did the native molecules when analysed by gel filtration, immunodiffusion, immunoelectrophoresis and electrophoresis in polyacrylamide gradient gels. The high capacity and the selectivity of the adsorbents make them suitable for the removal of lipoproteins from protein solutions.

Cholesterol↗
PubMed1977

Kinetics of refolding of completely reduced human-serum albumin. Regain of immunochemical reactivity.

The kinetics of refolding of completely reduced human serum albumin has been studied by various methods including immunological techniques. The decrease in thiol content is very rapid in the beginning of the reoxidation process and rather slow in the later stages. Polyacrylamide gel electrophoresis studies show that, in the earlier stages of refolding, the main part of the albumin is present as various oligomers and that a slow conversion to monomer occurs as reoxidation proceeds. Rocket immunoelectrophoresis shows that the completely reduced protein is devoid of native albumin antigenic determinants but that a rapid regain of immunoprecipitability is obtained upon reoxidation. A new 'consumption' rocket immunoelectrophoretic method has been used to estimate the total regain of antigenicity. The data obtained indicate that there is a preferential rapid folding to native structure in certain parts of the molecule but that areas with wrong or incomplete foldings exist a considerable time after the inital refolding period.

Disulfides↗
PubMedDate not supplied

Research involving persons with cognitive impairments: results of a survey of Alzheimer disease research centers in the United States.

Research involving persons with cognitive impairments presents ethical and practical challenges, including how to obtain valid informed consent. We asked the directors of the 29 U.S. research centers funded by the National Institute on Aging as "Alzheimer Disease Centers" to provide us with policies or guidelines used in their centers or associated institutions with regard to research involving cognitively impaired subjects. Twenty-four of the 29 centers (83%) responded. Five institutions (21%) had authored their own institutional policies, seven (29%) used guidelines issued by the Department of Health and Human Service's Office for Protection from Research Risks, and 12 (50%) had no policy or guidelines. The five institutional policies addressed a variety of issues, including obtaining consent from cognitively impaired subjects or their authorized representatives, subjects' assent to research participation, and guidance concerning determination of subjects' intellectual capacity. A well-written policy on the protection of cognitively impaired research subjects is one way a research institution demonstrates that it gives serious attention to the rights and welfare of these vulnerable persons. We recommend that all institutions conducting such research author written policies articulating appropriate safeguards for these vulnerable subjects. To promote the protection of cognitively impaired subjects, federal agencies and other funding groups may want to consider requiring written institutional policies as one condition of receiving funds to conduct such research.

Aged↗