Stigma, Social Comparison and Self-Esteem in Adults with an Intellectual Disability

Background: The paper examines the perception of stigma in 43 adults with an intellectual disability, the relationship this has with their psychological well-being and whether the process of social comparison has a moderating effect on this relationship. Materials and Methods: A questionnaire-based, within-participant design was used. Participants completed three self-report measures of perception of stigma, self-esteem and social comparison. Results: Perception of stigma was found to be significantly related to negative social comparisons, which in turn was significantly related to low self-esteem. No difference was found between social comparisons made with other service users and those made with people in the community. Social comparison was not found to have a moderating effect on the relationship between stigma and self-esteem. Conclusion: This study provides support for the influence of the perception of stigma and social comparison on the self-concept of individuals with an intellectual disability

A pilot of the use of the WAIS III in learning disability services

The present study is a pilot examining how a group of people (n=133) with a learning disability perform on the Wechsler Adult Intelligence Scale – Third Edition (1997). The study found that Full Scale IQ was not always predictive of performance on individual subtests or of performance on the Indices. Implications for clinical practice are discussed

Novel methods in trace metal detoxification

Two putative methods to deal with the problems caused by toxic trace metals were examined. Firstly, Escherichia coli cells into which had been cloned a gene thought to encode a metal-binding protein were examined. It is hoped that by such methods it may be possible to clone metal resistance into bacteria. Secondly, an approach was made to determine the feasibility of using immobilised plant metal binding peptides for the clearance of toxic metals from waste streams. Using this second approach, previously unavailable information on the metal-binding characteristics of (gammaEC)nG has been obtained. These data have implications for the physiology and biochemistry of (gammaEC)nG, in addition to their possible use in bioreclamation

Expression of recombinant metal-binding proteins in E. Coli and in Synechococcus PCC7942: examination of metal binding in vivo and vitro

Metallothioneins (MTs), cysteine-rich proteins and polypeptides, are proposed to detoxify excess intracellular metal ions via sequestration. Three genes, each encoding a protein related to this group of molecules, were expressed in Escherichia coli and in Synechococcus PCC7942 (variant PIM8) in order to examine the metal binding properties of their products. Phenotypic alterations, in terms of metal-tolerance and - accumulation, were assessed in cells expressing these genes. The genes which were expressed were: (1) smtA from Synechococcus PCC7942, which is designated to be the first isolated prokaryotic MT gene; (2) PsMT(_A), a gene from pea (Pisum sativum L) which encodes a protein with similarity to class I MT; and (3) a synthetic gene encoding(Glu-Cys)(_3)Gly, an analogue of the phytochelatin (PC; class III MT) molecule (γGlu-Cys)(_3)Gly. The protein encoded by smtA was shown to have high affinity for metal ions (Hg, Cd, Cu, Zn), supporting the designation of smtA as a prokaryotic MT gene. Comparison with mammalian MT revealed that the affinity of the product of smtA for Zn was higher than that of the mammalian protein, suggesting a role for this protein in Zn homoeostasis and/or detoxification in Synechococcus sp. E. coli cells expressing smtA exhibited increased accumulation of Zn and Cd (3-fold and 1.4-fold respectively relative to control cells), but no increase in tolerance toward Zn, Cd or Cu. Comparison of the metal-affinity of the product of PsMT(_A) with that of mammalian MT revealed that this protein also has high affinities for Cu, Cd and Zn. These data support the hypothesis that PsMTp^ is a higher plant MT gene. Affinity of the product of this gene for Cu was higher than that of mammalian MT, suggesting a role for this protein in Cu homoeostasis and/or detoxification. Expression of PsMT(_A) in E. coli resulted in increased accumulation of Cu, Cd and Zn. Cu accumulation was increased more substantially than either Zn or Cd accumulation in cells expressing PsMT(_A). No increase in tolerance toward any of these metals was observed in E. coli expressing this gene. There is evidence that PCs are involved in Cd detoxification in higher plants. Genes encoding enzymes involved in the synthesis of these molecules have not been isolated, precluding gene transfer experiments for investigation of their function. Expression of a gene encoding (Glu-Cys) gGly in E. coli resulted in increased tolerance toward Cd, but not Cu or Zn. Thus, a predicted function of a secondary metabolite (PC) was observed when a gene product based on the structure of this molecule was expressed in a heterologous system. No significant increase in accumulation of Cd, Cu or Zn was detected in cells expressing this gene.smtA transcripts were shown to increase in abundance in response to elevated concentrations of Cd in Synechococcus PCC7942 (variant PIM8). Sequences derived from the smt locus were fused to a synthetic gene encoding (Glu-Cys)(_3)Gly, and introduced into Synechococcus PCC7942(variant PIM8). Transcripts encoding (Glu-Cys)gGly increased in response to exposure of these cells to Cd. Cells containing this construct exhibited increased tolerance toward Cd. Data concerning expression of(Glu-Cys)(_3)Gly in E. coli and Synechococcal cells support the hypothesis that PCs may have a role in detoxification of excess intracellular Cd. Comparison of the data obtained in these studies has been used to assess the factors affecting metal-accumulation and -tolerance as a result of expression of heterologous metal-ligands in microbial cells