Psychological impact of biculturalism: evidence and theory.

A vital step in the development of an equal partnership for minorities in the academic, social, and economic life of the United States involves moving away from assumptions of the linear model of cultural acquisition. In this article we review the literature on the psychological impact of being bicultural. Assimilation, acculturation, alternation, multicultural, and fusion models that have been used to describe the psychological processes, social experiences, and individual challenges and obstacles of being bicultural are reviewed and summarized for their contributions and implications for investigations of the psychological impact of biculturalism. Emphasis is given to the alternation model, which posits that an individual is able to gain competence within 2 cultures without losing his or her cultural identity or having to choose one culture over the other. Finally, a hypothetical model outlining the dimensions of bicultural competence is presented.

MAO-A and -B inhibitors selectively alter Xenopus mucus-induced behaviors of snakes.

Skin mucus of the frog Xenopus laevis, contacted orally by snakes, induces dyskinetic oral movements and climbing behavior that promote escape. The mucus contains peptides and indoleamines known to produce drug-induced movement disorders in other species. We hypothesized that inhibition of monoamine oxidase-A (MAO-A) by N-methyl-N-propargyl-3-(2,4-dichlorophenoxy)-propylamine [clorgyline (CLG)] and MAO-B by R(-)-N, alpha-Dimethyl-N-2-propynyl-benzene-ethanamine [L-deprenyl (LDL)] would selectively modify mucus-induced behaviors by elevating norepinephrine and serotonin (with CLG), phenylethylamine (with LDL), or dopamine (with both drugs). In Experiment 1 (EXP1), adult snakes received mucus and/or 20 micrograms/g (IP) of both drugs. In EXP2, juveniles received mucus and/or 5, 10, and 20 micrograms CLG or LDL. CLG given alone had no effect on tongue flicking, activity, and climbing (EXP1,2). LDL alone decreased tongue flicking in EXP2 and increased climbing (EXP1,2). Given with mucus, both drugs further lowered the tongue flicking rates attenuated by mucus (EXP1,2); only LDL potentiated mucus-induced climbing. Yawning was the only mucus-induced dyskinesia attenuated (20 micrograms CLG, adults; 20 micrograms LDL, juveniles). We suggest that dopamine and/or phenylethylamine, the substrates for MAO-B, may promote mucus-induced climbing and tongue flicking but may have some protective role against mucus-induced yawning in water snakes.

Monoclonal antibody neutralization of unmanipulated Chlamydia trachomatis serovar A infection of human epithelioid cells (A-431).

A human epithelioid cell line (A-431) was tested in parallel with McCoy fibroblast cells for the growth of trachoma-related serovar A Chlamydia trachomatis without centrifugation or cycloheximide addition. A-431 cells were 4-7 times more susceptible to infection with serovar A than McCoy cells in such unmanipulated cultures. Murine monoclonal antibodies (MAbs) developed against serovar A were then evaluated for their ability to inhibit unmanipulated serovar A infectivity of A-431 cells. Two of seven MAbs tested neutralized infectivity by more than 50%. An IgG2a MAb (2C8) that is specific for serovar A, and another IgG2a MAb (4E3) that reacts equally with serovars A and L2 neutralized infectivity of serovar A by 72.2 +/- 3.7% and 56.0 +/- 5.8% (mean +/- SEM of 7 experiments) respectively. Mouse immune serum (MIS) raised against serovar A elementary bodies (EB) neutralized infectivity of serovar A by 76.0 +/- 4.9% (mean +/- SEM of 7 experiments). Immunoblot detection of serovar A EB polypeptides separated by SDS-PAGE indicated that 2C8 reacted with a 16 kD and 4E3 reacted with a 12 kD polypeptide while MIS reacted with several polypeptides including the major outer membrane protein (MOMP). These studies show that the human epithelioid cell line A-431 is a more susceptible host than McCoy cells in unmanipulated cultures, and that 2 MAbs neutralize serovar A infectivity of A-431 cells. Identification of antigenic moieties of importance in unmanipulated chlamydial infections may help in the development of potential vaccines against trachoma.

Immune responses of mice after conjunctival exposure to Chlamydia trachomatis serovar A.

CBA/J mice were inoculated in the lower conjunctival sac with live elementary bodies (EBs) of Chlamydia trachomatis serovar A. Recovery of chlamydia after exposure was done by culture of conjunctival swabs and draining lymph node (D-LN) cells in McCoy cells grown on coverslips in isolation vials. Cellular immune responsiveness was measured by lymphocyte proliferation assay of D-LN cells stimulated with irradiated EBs of serovars A, C, or L2. Humoral immunity was measured by enzyme-linked immunosorbent assay (ELISA) and immunoblot analysis. Chlamydia were consistently isolated from the conjunctiva and from the D-LN at 1 and 7 days after exposure respectively. Intermittent isolations were obtained from the conjunctiva up to day 4 and from the D-LN up to day 14 after a single exposure. Serovar A EB-stimulated lymphocyte proliferation was strong by 1 week after conjunctival exposure, but by 4 and 5 weeks, blastogenic responsiveness was very low. This lack of responsiveness may reflect a state of immunosuppression. Responses to serovars C and L2 EBs were consistently lower than to serovar A EBs. Serum IgG antichlamydia antibodies were not detected by ELISA until 2 weeks after exposure, peaked by 4-5 weeks, and decreased between 5 and 7 weeks after exposure. The IgM response was minimal at all times tested. There was, however, a modest increase in IgM antibodies at 3 and 5-7 weeks after exposure. Immunoblot analysis showed reactivity of mouse serum antibodies with polypeptide bands of 30, 41, and 52 kD at 3 and 4 weeks post exposure and predominantly with the 52 kD moiety at 5 weeks post exposure.(ABSTRACT TRUNCATED AT 250 WORDS)