Analysis of adhesive domains from the A4VAR Plasmodium falciparum erythrocyte membrane protein-1 identifies a CD36 binding domain.

The A4VAR is a variant antigen expressed by a clonal line that binds CD36 and intercellular adhesion molecule-1, ICAM-1. We have cloned and sequenced the extracellular domain coded by the A4var gene. To probe the relationship between A4var expression and parasite adhesion to ICAM-1, var mRNA and protein expression were analyzed in an enriched population of A4 parasites that displayed higher ICAM-1 binding. By Northern analyses, A4var was the predominant var message and antisera raised against a recombinant A4VAR protein reacted with the majority of infected erythrocytes, reinforcing previous conclusions that A4VAR binds ICAM-1. A4VAR contains five Duffy-binding like (DBL) domains, and two cysteine-rich interdomain regions (CIDR) domains. DBL and CIDR domains from A4VAR were expressed in mammalian cells to determine which regions mediate binding to CD36 and ICAM-1. Using several different binding assays, the A4VAR CIDR1 was the only domain found to bind CD36. In contrast, the same assays were unable to identify the ICAM-1 binding domain in A4VAR. This is the first time that each of the DBL and CIDR domains from a Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) have been systematically expressed and tested for binding. These results confirm that CIDR1 is sufficient to bind CD36 without any apparent contribution from other domains

Racial/Ethnic and Nativity Patterns of U.S. Adolescent and Young Adult Smoking

We document racial/ethnic and nativity differences in U.S. smoking patterns among adolescents and young adults using the 2006 Tobacco Use Supplement to the Current Population Survey (n=44,202). Stratifying the sample by nativity status within five racial/ethnic groups (Asian American, Mexican American, other Hispanic, non-Hispanic black, and non-Hispanic white), and further by sex and age, we compare self-reports of lifetime smoking across groups. U.S.-born non-Hispanic whites, particularly men, report smoking more than individuals in other racial/ethnic/nativity groups. Some groups of young women (e.g., foreign-born and U.S.-born Asian Americans, foreign-born and U.S.-born Mexican Americans, and foreign-born blacks) report extremely low levels of smoking. Foreign-born females in all of the 25–34 year old racial/ethnic groups exhibit greater proportions of never smoking than their U.S.-born counterparts. Heavy/moderate and light/intermittent smoking is generally higher in the older age group among U.S.-born males and females whereas smoking among the foreign-born of both sexes is low at younger ages and remains low at older ages. Taken together, these findings highlight the importance of considering both race/ethnicity and nativity in assessments of smoking patterns and in strategies to reduce overall U.S. smoking prevalence and smoking-attributable health disparities