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Biomedical subjects

H Kaplan

Publications and source records attributed to H Kaplan.

At least 235 records · Page 13Linked to original sources
PubMed1973

Protection of privacy and confidentiality.

A multistate, cooperative program seeking to develop better methods for the effective and efficient gathering. storing, analyzing, and utilizing of mental patient records has made a comprehensive effort to protect the confidentiality and privacy of these psychiatric patient records. Administrative, technical, and legal safeguards have been implemented. The discussion of legal safeguards involves two areas: the protection of the system itself, located at Rockland State Hospital; and the specific legal environment of confidentiality and privacy of mental health records and information in the group of cooperating jurisdictions. On the whole, adequate legal and administrative protection can be afforded the confidentiality and privacy of an electronic data system in the mental health field, and access to the records can be restricted for the welfare of the patients. At the same time, access to aggregate data in the system can be allowed, under proper standards, for important research and planning purposes. The methods adopted by MSIS to preserve confidentiality and privacy by limiting access to such records could well prove an important model for the development of protective methods in other electronic data programs-not only those in psychiatry, but those in other fields where the data collected are sensitive and confidential.

Ethics, Medical↗
PubMed1972

A competitive labelling method for determining the ionization constants and reactivity of individual histidine residues in proteins. The histidines of -chymotrypsin.

A competitive labelling method (Kaplan et al., 1971), using tritiated 1-fluoro-2,4-dinitrobenzene as the labelling reagent, is described for determining the ionization constants and reactivities of individual histidine residues in proteins. When this method was applied to the two histidines of alpha-chymotrypsin, histidine-57 was found to have pK(a) 6.8 and a reactivity ten times that of alpha-N-acetyl-l-histidine. Histidine-40 had pK(a) 6.7 and a reactivity approximately six times that of alpha-N-acetyl-l-histidine. Between pH7.5 and 8 the reactivities of both histidines decrease simultaneously to approximately that of alpha-N-acetyl-l-histidine. The high reactivities of the histidines are attributed to hydrogen bonding, which increases the nucleophilicity of the imidazole ring. The sharp decrease in reactivity between pH7.5 and 8 is attributed to a conformational change that disrupts the hydrogen bonding by these residues. The reactivity data support the proposal of a charge-relay mechanism involving histidine-57 (Blow et al., 1969), which makes serine-195 more nucleophilic but indicates that this system is fully operative only in the enzyme-substate complex.

Chemical Phenomena↗
PubMed1971

Competitive labelling, a method for determining the reactivity of individual groups in proteins. The amino groups of porcine elastase.

1. A method is described for determining the ionization constants and reactivities of individual amino groups in proteins. The principle is that in the presence of a trace amount of radioactive label, the various reactive groups in a protein molecule will compete for the label and the amount incorporated into any one group will be determined by its nucleophilicity, pK and micro-environment. The relative amounts of label incorporated into various groups will be proportional to their second-order rate constants and by comparing these rate constants with those expected on the basis of a linear free-energy relationship obtained with a series of standard compounds, the micro-environment can be defined for a particular amino group. 2. The method consists of treating a protein and an internal standard with a limiting amount of radioactive reagent and then with an excess of unlabelled reagent to yield a chemically homogeneous but heterogeneously labelled compound. After appropriate enzymic digestion peptides containing each labelled group are isolated and their rates of reaction, relative to the internal standard, are determined from their specific radioactivities. The entire procedure is repeated at several pH values. 3. When the method was applied to the amino groups of porcine elastase by using tritiated acetic anhydride as the labelling reagent, the N-terminus was found to have pK(a) 9.7 and a much lower than normal reactivity. Lysine-87 and lysine-224 were found to have pK(a) 10.3 and normal reactivities. At pH values greater than 10.5 there are discontinuities in all the titration curves, indicating that the entire molecule is undergoing a structural reorganization.

Amino Acids↗
PubMed1970

Studies on the immune response to a characterized antigenic determinant of the tobacco mosaic virus protein.

THE FOLLOWING PEPTIDES HAVE PREVIOUSLY BEEN SHOWN TO BIND SPECIFICALLY WITH ANTIBODIES TO TMVP: (a) An eicosapeptide representing residues 93-112 of TMVP and having the sequence Ileu-Ileu-Glu-Val-Glu-AspNH(2)-GluNH(2)-Ala-AspNH(2)-Pro-Thr-Thr-Ala-Glu-Thr-Leu-Asp-Ala-Thr-Arg. (b) Its C-terminal decapeptide. (c) Its C-terminal pentapeptide. (d) N-octanoyl-C-terminal-tripeptide. (e) (Lys)(4)-C-terminal-pentapeptide. (f) (Lys)(7) C-terminal-pentapeptide. The present communication deals with the investigation of several parameters of the immunological activity of the peptides. The results show that none of the peptides tested were immunogenic in guinea pigs, nor did they stimulate the incorporation of (14)C-thymidine by spleen cells derived from TMVP-primed animals. Results also showed that all of the peptides tested could elicit specific delayed and immediate skin reactions in TMVP-sensitized guinea pigs, and furthermore, that the peptides could specifically inhibit the migration of peritoneal exudate cells derived from these animals. The elicitation of delayed skin reactions and the ability to inhibit migration of peritoneal exudate cells were independent of carrier specificity.

Animals↗