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We report the expression of the human muscle (CK-MM) and brain (CK-BB) creatine kinases in Escherichia coli. The proteins have been purified to apparent homogeneity and several of their physical and kinetic properties investigated. In the process, we have conclusively verified the correct DNA sequence of the genes encoding the respective isozymes, and determined the correct primary structure and mass of the gene products. Alignment of the primary sequences of these two enzymes shows 81% sequence identity with each other, and no obvious gross structural differences. However, Western blot analyses demonstrated the general lack of antigenic cross-reactivity between these isozymes. Preliminary kinetic analyses show the K(m) and k(cat) values for the creatine and MgATP substrates are similar to values reported for other isozymes from various tissues and organisms. The human muscle and brain CKs do not, however, exhibit the synergism of substrate binding that is observed, for example, in rabbit muscle creatine kinase.

The examination of sexual activity in old age has typically meant a consideration of sexual intercourse. Masturbation has not received a rigorous investigation with respect to the elderly, despite benefits that may be associated with this form of sexual expression. The present study reports on the relationship of masturbation with locus of control, sexual status, and sexual knowledge as part of a more general but intensive study of an elderly sample. Results indicated that the best predictor of frequency of masturbation was locus of control, while sexual status and sexual knowledge contributed somewhat less to the variance explained in frequency of masturbation. Specifically, the data support the conclusion that internals masturbate more than externals, particularly internals with high sexual knowledge and persons without sexual partners may have a slight tendency to masturbate more often than those with partners.

Although the idea that sexuality is a lifelong need is gaining greater research support and greater acceptability to the general public, few consider the institutionalized aged as having sexual needs or being able to benefit from sexual intimacy. The research presented here indicates that sexual activity in the institutionalized aged is related to their attitudes and behavior toward sexuality and to their sexual interest level and prior frequency of sexual activity. Institutionalized aged persons evidence sexual needs and do engage in sexual behavior.

Current research on sexuality in the aged suffers from a lack of measuring instruments designed to assess the particular aspects of sexual knowledge and attitudes as they relate to the aged. The present scale is the result of several studies of sexual functioning in the aged, including intervention research, utilizing the Aging Sexuality Knowledge and Attitudes Scale (ASKAS) with aged persons, families of aged persons, and people who work with the aged. All findings support the validity and reliability of the scale in assessing sexual attitudes and sexual knowledge with specific reference to the aged. Significant changes in scale scores following intervention and significant relationships of sexual behavior to scale scores follow predicted directions. A factor analysis supported the two dimensions of attitudes and knowledge in the instrument.