Normal and lateral forces between lipid covered solids in solution: correlation with layer packing and structure.

We report on the normal and lateral forces between controlled-density mono- and bilayers of phospholipid co-adsorbed onto hydrophobic and hydrophilic solid supports, respectively. Interactions between 1,2-dioleoyl-sn-glycero-3-phosphocholine layers were measured using an atomic force microscope. Notable features of the normal force curves (barrier heights and widths) were found to correlate with the thickness and density of the supported lipid layers. The friction and normal force curves were also found interrelated. Thus, very low friction values were measured as long as the supported layer(s) resisted the normal pressure of the tip. However, as the applied load exceeded the critical value needed for puncturing the layers, the friction jumped to values close to those recorded between bare surfaces. The lipid layers were self-healing between measurements, but a significant hysteresis was observed in the force curves measured on approach and retraction, respectively. The study shows the potential of using atomic force microscopy for lipid layer characterization both with respect to structure and interactions. It further shows the strong lubricating effect of adsorbed lipid layers and how this varies with surface density of lipids. The findings may have important implications for the issue of joint lubrication.

Perceptions of social support and psychological adaptation to sexually acquired HIV among white and African American men.

Although the research literature documents the impact of social support on the mental health of people with human immunodeficiency virus (HIV) and acquired immune deficiency syndrome (AIDS), the assumption that relationships between social support and mental health functioning are comparable across ethnically distinct populations with HIV/AIDS has been challenged. This study reports preliminary data on the relationship between perceptions of social support and mental health in a sample of African American and white men with sexually acquired HIV. Data from 33 respondents revealed considerable differences within the sample. Data from white men revealed strong positive relationships between mental health measures and social support from friends and family, whereas data from African American men revealed negative relationships. Further, measures of social support seem to adequately reflect the support systems of white men but not those of African American men. Implications of these and additional findings for research and practice are considered.

Preparation and in vivo evaluation of an N-(p-[125I]iodophenethyl)maleimide-antibody conjugate.

Protein sulfhydryl reactive N-(4-[125I]iodophenethyl)maleimide (IPEM, 5) was obtained from N-[4-(tri-n-butylstannyl)phenethyl]maleimide in 59-100% radiochemical yield. Conjugation of 5 to NR-ML-05 Fab, a murine anti-melanoma antibody Fab fragment that had been previously reduced with dithiothreitol (DTT), was effected in an average of 85% yield. Results from in vitro chemical challenges and serum stability studies on the IPEM conjugate of NR-ML-05 Fab (6) indicated a stable covalent attachment of the radioiodine. A biodistribution study of the IPEM conjugate in tumor-bearing athymic nude mice showed lack of significant accumulation of radioiodine in the thyroid and stomach which was an indication of in vivo stability. The observed uptake in tumor was consistent with that obtained for Chloramine-T- or p-iodobenzoate-labeled NR-ML-05 Fab conjugates.

Radioiodinated iodobenzoyl conjugates of a monoclonal antibody Fab fragment. In vivo comparisons with chloramine-T-labeled Fab.

A comparative investigation of the biodistributions of radioiodinated p- and m-iodobenzoyl conjugates of a monoclonal antibody Fab fragment, NR-LU-10 Fab, and the same antibody Fab fragment radioiodinated by the chloramine-T (ChT) method has been carried out in mice. Coinjected, dual-isotope studies in athymic mice with tumor xenografts have demonstrated that there are only minor differences in the in vivo distributions of the iodobenzoyl-labeled Fabs, except in the excretory organs, kidneys, and intestines, where major differences were observed. Similarly, coinjection of either the p-iodobenzoyl or m-iodobenzoyl conjugate of NR-LU-10 Fab with the Fab radioiodinated with ChT/radioiodide into BALB/c mice provided additional data that indicated that the two iodobenzoyl conjugates distributed similar in a number of selected tissues. The tissue-distribution differences of the regioisomeric iodobenzoyl conjugates in relation to the ChT-radioiodinated Fab were large for the stomach and neck, consistent with previous studies. The most notable difference between the two iodobenzoyl conjugates was the kidney activity, where the m-iodobenzoyl conjugate was similar to the directly labeled Fab, but the p-iodobenzoyl-conjugated Fab was higher by nearly a factor of 2.

Clinical nurse specialists in transition.

Much attention is given to the development of the clinical nurse specialist role in an institution. This article is written for the seasoned Clinical Nurse Specialist who experiences a change in nursing administration. It describes dilemmas, identifies dynamics, and offers practical suggestions for surviving and thriving during a transition period.

Adolescent sexuality.

The consequences of adolescent sexual behavior are an enormous burden both for the adolescent and society. The problem is not that teens are sexually active but rather that they have little preparation and guidance in developing responsible sexual behavior. Developmentally, adolescents reach physical maturity before they are cognitively able to appreciate the consequences of their behavior. A teenager's primary source of information regarding sexuality is his or her peer group, all of whom are experiencing and reinforcing the same behaviors. The family, the major socializer of other behaviors, is not as powerful a force in shaping responsible sexual behavior because of parental discomfort with sex education and sexual discussions. This is the result of a social milieu in which sex is frequently portrayed but rarely linked with responsible behavior or accurate, nonjudgmental information. The pediatric practitioner is in an ideal position to intervene in these dynamics. In the office, the practitioner can provide accurate sexual information to both parents and adolescents, support parental-child communication on sexual issues, and provide appropriate services or referral. In the community, the practitioner can advocate for school-based sex education as well as act as an information resource. Finally, the practitioner can advocate for the health care needs for adolescents on a national level, supporting legislation that provides adolescents with information and access to services necessary to make responsible sexual decisions.

PIP: Responsible teenage sexual behavior can be promoted by the pediatric practitioner through contact with adolescent patients, parents, and community outreach. In order to achieve this end, a review of the epidemiology of adolescent sexual behavior (sexual activity, contraceptive use, abortion, sexually transmitted diseases (STDs), pregnancy and outcomes for adolescents, parents, and children) and determinants of sexual risk-taking behavior are provided. Such determinants include developmental characteristics, puberty, identity, intimacy, cognitive development, biologic characteristics, and individual characteristics (religiosity, race, socioeconomic status, and media influences). Concrete guidelines for the pediatric practitioner which instruct in the prevention of pregnancy and STDs are included. The practitioner needs to be comfortable with his/her own sexuality; trained in basic adolescent care; knowledgeable about community norms and expectations; and needs to take a sexual history of each patient, including questions about incest, homosexuality, the specific numbers of sexual partners, age at 1st intercourse, and practice of oral or anal sex. Information provided must be nonjudgmental and supportive. A table provides 17 possible questions to prompt history taking. Well-child visits from the beginning should address issues of sexuality. Communication channels prepuberty need to be open between the practitioner and adolescent and parent, so that a confidential discussion between practitioner and adolescent can occur. Parents need to be encouraged to discuss sexual issues. A table provides recommended books. Adolescent needs depend upon the developmental stage, i.e., a teen who has not reached operational thinking does not understand cause and effects of sexual behavior. Sexuality involves feelings and relationships, not just intercourse; it is only 1 aspect of one's personal life. The practitioner can be an important source of accurate information and can promote effective se education and use of clinics. National advocacy can effectively change, for instance, restoring Reagan-style budget cuts for maternal-child health block grants.