A comparison of the influence of conflictual and supportive social interactions on psychological distress.

Following a quantitative review examining the relative influence of positive and negative social exchanges on emotional health, a second-order factor model of negative social exchange was tested and supported in a sample of 906 college students. Structural equation analysis exploring the unique effects of negative social exchange and perceived support satisfaction on depression revealed both variables to predict this outcome, over and above the contribution of personality and coping variables. In addition to the direct effects of the Big Five personality dimensions on depression, indirect effects of the Big Five via negative social exchange, support satisfaction, and avoidant coping also were observed. Although the prevailing belief among support researchers is that the negative effects of conflictual social interactions outweigh the positive effects of social support, the results of the quantitative review suggest boundary conditions that qualify this conclusion. In addition to corroborating a hierarchical measurement model of negative social exchange, the results of the present investigation suggest that how social support and social negativity are measured substantially influences conclusions concerning their relative impact on psychological distress.

The self-esteem motive in social influence: agreement with valued majorities and disagreement with derogated minorities.

This research provides evidence for the role of self-esteem in social influence; it demonstrates that the positions taken by self-relevant social groups can threaten people's self-esteem. Participants who wished to align themselves with a majority group and who learned that the group held a counterattitudinal position suffered a reduction in self-esteem. Similarly, participants who wished to differentiate themselves from a derogated minority group and who learned that the group held attitudes similar to theirs experienced reduced self-esteem. Group attitudes, however, did not affect the self-esteem of participants who were indifferent to the group. In addition, this study demonstrates that self-relevant motivations direct the way people process influence appeals. Participants adopted interpretations of the issues that allowed them to align themselves with valued majorities and differentiate themselves from derogated minorities.

Self-definition, defensive processing, and influence: the normative impact of majority and minority groups.

Past research has found that recipients agree with majority group positions and resist minority group positions on direct measures of influence. The authors suggest that these attitude shifts reflect normative pressures to align with valued majorities and to differentiate from derogated minorities. In support of this idea, participants who considered a majority group relevant to their own self-definitions (but not those who judged it irrelevant), on learning that the group held a counterattitudinal position, shifted their attitudes to agree with the source. In a second study, recipients who judged a minority group (negatively) self-relevant, on learning that the group held a similar attitude to their own, shifted their attitudes to diverge from the source. These shifts in attitudes were based on participants' interpretations of the attitude issues.

Detection of enterotoxigenic Escherichia coli in stool samples by using nonradioactively labeled oligonucleotide DNA probes and PCR.

The detection of heat-labile enterotoxin LT-A and heat-stable enterotoxin ST Ia and ST Ib genes from enterotoxigenic Escherichia coli (ETEC) by using oligonucleotide DNA probes and the PCR was evaluated in reconstruction experiments and by testing stool specimens from 29 healthy subjects and from 50 patients with diarrhea who had returned from the (sub)tropics. ETEC strains were detected in concentrations ranging from 10(6) to 10(8) CFU/g of feces when oligonucleotide probes were applied to colony blots from five randomly picked E. coli-like colonies from CLED (cystine lactose electrolyte deficient) agar plates inoculated with the feces. When these probes were applied to blots from whole stool cultures collected from the agar plates (sweep blot), the detection limit was 10(6) CFU/g of feces. PCR of the sweep material could detect toxin genes when the concentration of ETEC strains was 10(2) CFU/g of feces. Results obtained with stool specimens from 29 healthy control subjects were negative. Testing stool specimens from 50 patients confirmed the observation that the number of samples containing ETEC enterotoxin genes was higher when PCR of sweeps was used than when oligonucleotide DNA probe hybridization of either sweep blots or colony blots was used. Furthermore, PCR of sweeps is an easy and rapid method which does not require DNA extraction and purification from fecal specimens.