This study looks at young people's accounts of life in communities in rural northern Scotland, and considers in what ways affective and social aspects of community are bound up with well-being, over and above young people's concerns for the future, rural youth transitions, and out-migration. Interviews were held with 15-18 year-olds in four study areas (16 groups, N = 60+) and a parallel survey of 11-16 year-olds was conducted in eight study areas (N = 2400+). Themes to emerge from the interviews included: opportunities locally, the future and staying on, as well as local amenities and services; but older teenagers also spoke at length about their social lives, family and social networks, and their community, both as close-knit and caring and as intrusive and controlling. Rural communities were seen as good places in childhood, but not necessarily for young people. In parallel with that, the survey data paints a picture where feelings of support, control, autonomy, and attachment were all associated with emotional well-being. Importantly, links between emotional well-being and practical, material concerns were outweighed by positive identifications of community as close-knit and caring; and equally, by negative identifications as intrusive and constraining, where the latter was felt more strongly by young women. Certainly, beliefs about future employment and educational opportunities were also linked to well-being, but that was over and above, and independently of, affective and social aspects of community life. Additionally, migration intentions were also bound up with sense of self and well-being, and with feelings about community life; and links between thoughts about leaving and community life as controlling and constraining were, yet again, felt more strongly by young women. Thus, gender was a key dimension affecting young people's feelings about their communities with significant implications for well-being, and out-migration. The study illustrates the importance of understanding the experiences young people have of growing up in rural areas, and how they evaluate those experiences: particularly, how life in rural communities matters for young people's well-being; and especially, for young women.

The human complement system is an important early host defense against infection. Entamoeba histolytica activates the complement system but is resistant to killing by complement C5b-9 complexes deposited on the membrane surface. Our aim was to identify components of the amebic plasma membrane that mediate resistance to human complement C5b-9 by screening for neutralizing monoclonal antibodies. A monoclonal antibody was identified that abrogated amebic resistance to C5b-9, and the mAb was shown to recognize the parasite's galactosespecific adhesin. The purified adhesin bound to C8 and C9 and conferred C5b-9 resistance to sensitive ameba upon reconstitution; these activities of the adhesin were inhibited by the antiadhesin mAb. The E. histolytica adhesin shared sequence similarities and antigenic cross-reactivity with CD59, a membrane inhibitor of C5b-9 in human blood cells, suggesting both molecular mimicry and shared complement-inhibitory functions. (J. Clin. Invest. 1992. 90:1131-1137

Entamoeba histolytica trophozoites initiate pathogenic colonization by adherence to host glycoconjugates via an amebic surface lectin which binds to galactose (Gal) and N-acetylgalactosamine (GalNAc) residues. Monovalent and multivalent carbohydrate ligands were screened for inhibition of E. histolytica lectin-mediated human red cell hemagglutination, revealing that: (i) the synthetic multivalent neoglycoprotein GalNAc39BSA (having an average of 39 GalNAc residues linked to bovine serum albumin) was 140,000-fold more potent an inhibitor than monovalent GalNAc and 500,000-fold more potent than monovalent Gal; and (ii) small synthetic multivalent ligands which bind with high affinity to the mammalian hepatic Gal/GalNAc lectin do not bind with high affinity to the E. histolytica lectin. Radioligand binding studies revealed saturable binding of 125I-GalNAc39BSA to E. histolytica membranes (KD = 10 +/- 3 nM, Bmax = 0.9 +/- 0.08 pmol/mg membrane protein). Maximal binding required the presence of calcium chloride (300 microM) or sodium chloride (50 mM), and had a broad pH maximum (pH 6-9). GalNAc39BSA was 200,000-fold more potent than monovalent GalNAc in blocking radio-ligand binding. Among synthetic saccharide-derivatized linear polymers, the GalNAc beta and GalNAc alpha 3Gal beta derivatives were the most potent, with GalNAc alpha and GalNAc alpha 3(Fuc alpha 2)Gal beta derivatives much weaker. The data support a model in which a unique pattern of spaced multiple GalNAc residues are the highest affinity targets for the E. histolytica lectin.

Monoclonal antibodies (MAbs) directed against pathogen-specific epitopes of the galactose adhesin of Entamoeba histolytica were used in an ELISA to detect antigen from pathogenic E. histolytica. Single stool specimens from 74 patients in Bangladesh were used. The ELISA for pathogenic E. histolytica was positive in all 12 stool specimens with pathogenic amebae subsequently cultured, in no stool specimens with nonpathogenic E. histolytica and in 2 of 40 stools with other or no intestinal parasites detected. Specificity and sensitivity of the assay for pathogenic E. histolytica were 97% and 100%, respectively. These preliminary data offer promise for an ELISA using MAbs to the galactose adhesin as a rapid and sensitive means to detect the presence of pathogenic E. histolytica infection in stool specimens.

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