High-risk drug use and sexual behaviors among out-of-treatment drug users: An aging and life course perspective

High-risk injection drug use and the sexual behaviors that accompany it have large social and financial costs. Tailored treatments have been shown to successfully reduce high-risk behaviors. However, little is known about how age and age at first drug use are related to high-risk injection or sex behaviors. The current study draws on life course theory and hypothesizes that age will have a strong relationship with high-risk behaviors of out-of-treatment drug users. Data from the NIDA Cooperative Agreement was used to analyze the relationship between (1) age, and (2) age at first drug use with seven high-risk injection and sexual behavior variables. Negative binomial regression models revealed that high-risk sexual behavior decreases between 15.8 and 20.9% with each decade of age, while high-risk injection behavior increases between 32 and 67% with each decade of age after the addition of demographic controls. Both high-risk injection and high-risk sex behaviors are significantly reduced with a delayed age at first drug use. Previous research promotes interventions to reduce the high-risk sexual behaviors of older drug users. The current study suggests a refocusing of public health efforts on the high-risk injection habits of older drug users.^

Effects of salinity, temperature and cadmium stress on cadmium -binding protein in the grass shrimp, {\it Palaemonetes pugio}

The combined effects of salinity, temperature and cadmium stress on survival and adaptation through cadmium-binding protein (CdBP) accumulation were studied in the grass shrimp, Palaemonetes pugio. In 96-hour bioassays, shrimp were exposed to zero or one of three levels of cadmium, under one of six different salinity (15, 25, or 35$\perthous$) and temperature (20 or 30$\sp\circ$C) regimes. CdBP concentrations were quantified in survivors from the 24 exposure groups. Salinity and temperature did not affect survivorship unless the shrimp were also exposed to cadmium. Grass shrimp were most sensitive to cadmium at low salinity-high temperature, and least sensitive at high salinity-low temperature. The incidence of cadmium-associated black lesions in gill tissue was influenced by salinity and temperature stress. P. pugio produced a 10,000 dalton metallothionein-like CdBP when exposed to at least 0.1 mg Cd$\sp{2+}$/L for 96 hours. Accumulation of CdBP was increased with increases in the exposure cadmium level, increases in temperature and decreases in salinity, independently and in conjunction with one another. Maximum CdBP concentrations occurred in grass shrimp that survived the salinity-temperature-cadmium conditions creating maximum stress as measured by highest mortality, not necessarily in shrimp exposed to the highest cadmium levels. The potential utility of this method as a monitor of physiological stress in estuarine biota inhabiting metal-polluted environments is discussed. ^