Kinetics of 3-nitrotyrosine modification on exposure to hypochlorous acid.

The markers 3-nitrotyrosine and 3-chlorotyrosine are measured as surrogates for reactive nitrogen species and hypochlorous acid respectively, which are both elevated in inflamed human tissues. Previous studies reported a loss of 3-nitrotyrosine when exposed to hypochlorous acid, suggesting that observations of 3-nitrotyrosine underestimate the presence of reactive nitrogen species in diseased tissue (Whiteman and Halliwell, Biochemical and Biophysical Research Communications, 258, 168-172 (1999)). This report evaluates the significance of 3-nitrotyrosine loss by measuring the kinetics of the reaction between 3-nitrotyrosine and hypochlorous acid. The results demonstrate that 3-nitrotyrosine is chlorinated by hypochlorous acid or chloramines to form 3-chloro-5-nitrotyrosine. As 3-nitrotyrosine from in vivo samples is usually found within proteins rather than as free amino acid, we also examined the reaction of 3-nitrotyrosine modification in the context of peptides. The chlorination of 3-nitrotyrosine in peptides was observed to occur up to 700-fold faster than control reactions using equivalent amino acid mixtures. These results further advance our understanding of tyrosine chlorination and the use of 3-nitrotyrosine formed in vivo as a biomarker of reactive nitrogen species.

Modelling a tethered mammalian sperm cell undergoing hyperactivation.

The beat patterns of mammalian sperm flagella can be categorised into two different types. The first involves symmetric waves propagating down the flagellum with a net linear propulsion of the sperm cell. The second, hyperactive, waveform is classified by vigorous asymmetric waves of higher amplitude, lower wavenumber and frequency propagating down the flagellum resulting in highly curved trajectories. The latter beat pattern is part of the capacitation process whereby sperm prepare for the prospective penetration of the zona pellucida and fusion with the egg. Hyperactivation is often observed to initiate as sperm escape from epithelial and ciliary bindings formed within the isthmic regions of the female oviducts, leading to a conjecture in the literature that this waveform is mechanically important for sperm escape. Hence, we explore the mechanical effects of hyperactivation on a tethered sperm, focussing on a Newtonian fluid. Using a resistive force theory model we demonstrate that hyperactivation can indeed generate forces that pull the sperm away from a tethering point and consequently a hyperactivated sperm cell bound to an epithelial surface need not always be pushed by its flagellum. More generally, directions of the forces generated by tethered flagella are insensitive to reductions in beat frequency and the detailed flagellar responses depend on the nature of the binding at the tethering point. Furthermore, waveform asymmetry and amplitude increases enhance the tendency for a tethered flagellum to start tugging on its binding. The same is generally predicted to be true for reductions in the wavenumber of the flagellum beat, but not universally so, emphasising the dynamical complexity of flagellar force generation. Finally, qualitative observations drawn from experimental data of human sperm bound to excised female reproductive tract are also presented and are found to be consistent with the theoretical predictions.

Structure and implementation of comprehensive state preadmission screening programs for nursing home applicants: 1978-1994.

This paper examines the structure and implementation of comprehensive state preadmission screening (PAS) programs for nursing home applicants from 1978 to 1994 in all 50 states and the District of Columbia. A state was considered to have comprehensive PAS if a majority of nursing home applicants were screened in-person by state or contract agency staff. Twenty-six states had implemented these programs by 1994, with the most growth taking place during the 1980s. The primary changes in program structure were an increased reliance on private providers to screen a subset of applicants and a higher percentage of states screening private pay applicants. All programs but one referred or authorized the use of community-based services, while most programs diverted well over 10 percent of nursing home applicants.

"He calls me his angel of mercy": the experience of caring for elderly parents in the home.

The purpose of this qualitative ethnography was to describe the experience of caregivers who resided with their elder dependent parents and to discover caregiver needs. Five women between the ages of 35 and 73 years who cared for and shared residence with their dependent elder parents participated in the study. As prescribed by Field and Morse's method of data analysis, interviews were transcribed verbatim, and concepts and subconcepts were discovered in the data. The findings reflecting the experience of caregiving and a discovery of caregiver needs assisted in identifying three concepts--needs, motivation, and helpers/hindrances--and six subconcepts--quiescence, emancipation, love for parent, avoiding institutionalization, family, and formal support. These concepts and subconcepts contributed to the development of the model of kin-keeper for caregivers. This model has consideration as a level I theory. It offers to nursing an explanation of the behaviors of caregivers and provides an improved understanding of the process of caregiving as related to holistic nursing practice. Further research and development of the model to a level I theory are recommended, as is the use of a larger and more diverse population.