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J D Schein

Publications and source records attributed to J D Schein.

17 recordsLinked to original sources
PubMed1992

Hydrofluoric acid-treated tau PHF proteins display the same biochemical properties as normal tau.

Tau (tau) is a major constituent of paired helical filaments (PHF) found in Alzheimer's disease. The current study examines the possibility that the distinct properties of PHF-associated tau proteins (tau PHF) result from post-translational modifications of normal soluble tau (tau s). Following hydrofluoric acid (HF) treatment, tau PHF proteins are heat- and acid-stable, soluble in 2-(N-morpholino)ethanesulfonic acid buffers and display the same molecular weight, pI, and immunochemical properties as normal tau s. Alkaline phosphatase treatment of dissociated PHF results in similar, although less extensive, electrophoretic changes and a reduction in PHF-1 immunoreactivity. Therefore, phosphorylation of normal tau s appears to be responsible for the distinct properties of tau PHF. Although our results suggest that all of the normal tau isoforms are in PHF, the relative abundance of individual tau species differs in HF-treated PHF and tau s samples. Moreover, the loss of PHF following HF treatment suggests that post-translational modifications contribute to the structural stability of PHF.

Adult↗
PubMed1992

Improving the validity of the PSNI in assessing the performance of deaf parents of hearing children.

The content validity of the Parental Strengths and Needs Inventory (PSNI) for evaluating the child-rearing performance of deaf adults was assessed by replicating and extending an earlier cross-sectional descriptive study. Three types of subjects--deaf parents, hearing offspring, and hearing grandparents--provided the research data. The interview responses of 15 parent-child dyads were triangulated with grandparent questionnaire responses to identify parental issues not tapped by the closed-ended PSNI format. The content validity of the PSNI in its present form was found to be inadequate for assessing the strengths and needs of deaf parents. Recommendations for modifying the PSNI for use with deaf parents of hearing children are advanced.

Adolescent↗
PubMedDate not supplied

Limited proteolytic processing of the mature form of cathepsin D in human and mouse brain: postmortem stability of enzyme structure and activity.

The mature form of cathepsin D (Cat D), purified to homogeneity from postmortem human brain or mouse brain, behaved as a 42-kDa protein in its native state but revealed additional proteolytic processing under denaturing conditions. Human brain Cat D was composed of a 30-32 kDa heavy chain and a protein doublet consisting of 14 and 15 kDa light chains. Mouse Cat D, which closely resembled the human enzyme in amino acid composition, existed mainly as the uncleaved 42-kDa protein, but up to 40% existed as a complex of 30-32 kDa and 12-14 kDa chains. The 3:1 ratio of light to heavy (30-32 kDa) chains suggested processing of some 30-kDa chains. Cleavage of the 42-kDa chain could not be induced autolytically. Human brain Cat D had a 2-3-fold higher specific activity than the mouse enzyme but shared other properties, including similar biphasic pH optima (peaks at pH 3.30 and 4.2), Km values for methemoglobin and inhibitor profiles. Human Cat D displayed the same polypeptide chain composition when purified from brains differing in postmortem interval (3-28 h). Fresh SH-SY5Y human neuroblastoma cells analyzed on Western blots with anti-Cat D antibodies also displayed only cleaved forms of mature Cat D. Furthermore, brain Cat D isolated from mice stored after death for 5, 15 or 30 h at 25 degrees C contained the same molar ratios of cleaved and uncleaved enzyme found in fresh mouse brain . Cat D activity was stable in human brains with postmortem intervals up to 27 h and stored frozen for up to 3 years. Similarly, total Cat D activity was essentially unchanged in brains of mice subjected to stimulated postmortem conditions for 0.5-4.2 h, although 20% of the total soluble brain protein became insoluble during this postmortem interval. These results demonstrate a remarkable postmortem stability of Cat D and strongly suggest that limited proteolytic cleavage of mature brain Cat D is an in vivo event, the extent of which varies markedly in different species.

Aged↗