Contexts as moderators of observed interactions: a study of Costa Rican mothers and infants from differing socioeconomic backgrounds.

20 first-born infants from low socioeconomic status (SES) families and 20 first-born infants from middle SES families in Costa Rica were observed for 12 hours when they were 14 weeks old. The goals of this study were the following: 1) to study the impact of length of observation and context on the authors measures of interactional engagement; 2) to compare the interactional experiences of the infants in the two groups in various functional (e.g. feeding, object play) and social (e.g. with mother, with mother and others) contexts. Attuned and disharmonious interactions, as well as the frequency of positive affect, soothing, and vocalization, varied considerably across the functional contexts. In addition, disharmonious interactions increased and interactional engagement decreased when mothers and infants were joined by others. Highly unstable measures of individual differences were obtained when observations were limited to 45-minute blocks, but stability increased considerably as the duration of the observations expanded. The groups did not differ with respect to amounts of time spent in various functional and social contexts, in attuned or disharmonious states, or in high levels of interactional engagement. Within some of the functional contexts, however, significant group differences in levels of attuned interactions, infant vocalization, and maternal response vocalization were found. Overall, functional and social contexts clearly moderated interactional experiences. SES effects on verbal and other interactional measures were limited to some contexts and may thus represent the infants' overall experiences quite poorly. Consequently, comparisons based on a single context may be inadequate for studies of subjects from differing socioeconomic backgrounds.

Adhesion of guinea pig polymorphonuclear leukocytes to autologous aortic strips: influence of chemotactic factors and of pharmacological agents which affect arachidonic acid metabolism.

In superfusion experiments, the complement peptide C5a-desArg and the leukotriene B4 (LTB4) enhanced adhesion of guinea pig polymorphonuclear leukocytes to autologous aortic strips (threshold at about 10(-8) M, maximal effects at 10(-7) M). C5a-desArg acted primarily by stimulation of the leukocytes: pretreatment of them with the peptide abolished their response by deactivation, whereas pretreatment of the endothelium did not affect adhesion. However, the endothelium obviously cooperated in the response: enhanced adhesion was obtained only when the leukocytes were exposed to C5a-desArg while in contact with the endothelium. The cooperation is most probably due to release of arachidonic acid from endothelium and formation of lipoxygenase products (LTB4?) therefrom by the stimulated leukocytes. Incubation of leukocytes with nordihydroguaiaretic acid or with relatively high concentrations of indomethacin--both known to inhibit lipoxygenases-- lowered the effect of C5a-desArg, but not that of LTB4 nor the spontaneous adhesion. On the other hand, the stable prostacyclin analogue ZK 36 374 decreased C5a-desArg-induced adhesion, while pretreatment of the aortic strips with indomethacin increased it. These results suggest that endogenous prostacyclin may also play a role in this system by reducing adhesion.

Influence of the anti-inflammatory serine esterase inhibitor gabexate mesilate (Foy) on aggregation, locomotion and adhesion of polymorphonuclear leukocytes.

The effects of the anti-inflammatory serine esterase inhibitor, gabexate mesilate (Foy) were studied, on locomotion, autoaggregation and adhesion of polymorphonuclear leukocytes stimulated with the complement peptide C5a-desArg. The drug inhibited aggregation as well as spontaneous and directed migration of human leukocytes at concentrations of about 10(-3) M. Adhesion of peritoneal guinea-pig leukocytes to autologous aortic strips was reduced at about 20 times lower drug concentrations. The inhibitory drug effects were highly time- and temperature-dependent. Experiments with the two major drug metabolites, pHB and epsilon GC, indicate that gabexate mesilate is not active by itself but rather by its hydrolytic aromatic metabolite pHB. The results further suggest that the inhibitory effects on leukocyte activities observed are not related to the anti-inflammatory effects of gabexate mesilate.