Proline induced disruption of the structure and dynamics of water.

We use quasi-elastic neutron scattering spectroscopy to study the diffusive motion of water molecules at ambient temperature as a function of the solute molar fraction of the amino acid, proline. We validate molecular dynamics simulations against experimental quasielastic neutron scattering data and then use the simulations to reveal, and understand, a strong dependence of the translational self-diffusion coefficient of water on the distance to the amino acid molecule. An analysis based on the juxtaposition of water molecules in the simulation shows that the rigidity of proline imposes itself on the local water structure, which disrupts the hydrogen-bond network of water leading to an increase in the mean lifetime of hydrogen bonds. The net effect is some distortion of the proline molecule and a slowing down of the water mobility.

Promising strategies for preventing perinatal HIV transmission: model programs from three states.

OBJECTIVES: This paper describes and compares three innovative methods for preventing perinatal HIV transmission. Each of these strategies has been developed based on an in-depth assessment of the strengths and weaknesses of existing prevention approaches, and the needs of the populations they serve. METHODS: Florida expanded an existing outreach program to include women in jails in several high-prevalence counties. Incarcerated women were offered testing for pregnancy and HIV and linked to medical and supportive services. One Connecticut hospital sought to increase prenatal HIV testing rates by requiring HIV test results in the electronic medical records. This program is being expanded to other hospitals throughout the state. Louisiana has implemented a systematic review of perinatal data in order to identify potential programmatic enhancements. This review has led to the perinatal fast track system, designed to quickly identify HIV-infected pregnant women and connect them to care. RESULTS: Each program demonstrated improvements in indicators related to prevention of perinatal HIV transmission, such as increased utilization of prenatal care, increased prenatal testing rates, and decreases in perinatal HIV transmission. CONCLUSIONS: These case studies emphasize two key similarities among these programs: the value of collaboration between agencies providing care and services to HIV-infected and high-risk women of childbearing age, and the importance of maximizing opportunities for HIV testing and treatment. These strategies have demonstrated effectiveness in improving health outcomes and reducing perinatal HIV transmission.