Conversation for change: engaging older adults as partners in research on gerotechnology.

There is increasing research and public policy investment in the development of technologies to support healthy aging and age-friendly services in Canada. Yet adoption and use of technologies by older adults is limited and rates of abandonment remain high. In response to this, there is growing interest within the field of gerotechnology in fostering greater participation of older adults in research and design. The nature of participation ranges from passive information gathering to more active involvement in research activities, such as those informed by participatory design or participatory action research (PAR). However, participatory approaches are rare with identified barriers including ageism and ableism. This stigma contributes to the limited involvement of older adults in gerotechnology research and design, which in turn reinforces negative stereotypes, such as lack of ability and interest in technology. While the full involvement of older adults in gerotechnology remains rare, the Older Adults' Active Involvement in Ageing & Technology Research and Development (OA-INVOLVE) project aims to develop models of best practice for engaging older adults in these research projects. In this comment paper, we employ an unconventional, conversational-style format between academic researchers and older adult research contributors to provide new perspectives, understandings, and insights into: (i) motivations to engage in participatory research; (ii) understandings of roles and expectations as research contributors; (iii) challenges encountered in contributing to gerotechnology research; (iv) perceived benefits of participation; and (v) advice for academic researchers.

More investments are being made to develop technologies that support healthy aging and age-friendly services in Canada. However, not many older adults use these technologies and those who do tend to stop using them after some time. Gerotechnology is a field of study that combines an interest in gerontology and technology. Within gerotechnology, researchers are learning more about how to encourage older adults to participate in research and the design of new technologies. There are different ways that older adults participate in gerotechnology research, with some approaches being more passive than others. In participatory design and participatory action research projects older adults are encouraged to engage more actively as co-researchers. However, researchers have found that there are some limitations to engaging older adults actively in research, including ageism and ableism, meaning that older adults are perceived to be capable of contributing based on their age and cognitive or physical abilities. These stereotypes have limited how often and how much older adults actually contribute to technology research and design. The Older Adults' Active Involvement in Aging & Technology Research and Development (OA-INVOLVE) project aims to address these gaps. In this comment paper, we present a conversation between academic and older adult researchers who have contributed to OA-INVOLVE. The goal of this conversation is to explore together: (i) motivations to engage in participatory research; (ii) understandings of roles and expectations as research contributors; (iii) challenges encountered in contributing to gerotechnology research; (iv) perceived benefits of participation; and (v) advice for academic researchers.

Growth of calcium-blind mutants of Yersinia pestis at 37 degrees C in permissive Ca2+-deficient environments.

Cells of wild-type Yersinia pestis exhibit a low-calcium response (LCR) defined as bacteriostasis with expression of a pCD-encoded type III secretion system (T3SS) during cultivation at 37 degrees C without added Ca(2+) versus vegetative growth with downregulation of the T3SS with Ca(2+) (>or=2.5 mM). Bacteriostasis is known to reflect cumulative toxicity of Na(+), l-glutamic acid and culture pH; control of these variables enables full-scale growth ('rescue') in the absence of Ca(2+). Several T3SS regulatory proteins modulate the LCR, because their absence promotes a Ca(2+)-blind phenotype in which growth at 37 degrees C ceases and the T3SS is constitutive even with added Ca(2+). This study analysed the connection between the LCR and Ca(2+) by determining the response of selected Ca(2+)-blind mutants grown in Ca(2+)-deficient rescue media containing Na(+) plus l-glutamate (pH 5.5), where the T3SS is not expressed, l-glutamate alone (pH 6.5), where l-aspartate is fully catabolized, and Na(+) alone (pH 9.0), where the electrogenic sodium pump NADH : ubiquinone oxidoreductase becomes activated. All three conditions supported essentially full-scale Ca(2+)-independent growth at 37 degrees C of wild-type Y. pestis as well as lcrG and yopN mutants (possessing a complete but dysregulated T3SS), indicating that bacteriostasis reflects a Na(+)-dependent lesion in bioenergetics. In contrast, mutants lacking the negative regulator YopD or the YopD chaperone (LcrH) failed to grow in any rescue medium and are therefore truly temperature-sensitive. The Ca(2+)-blind yopD phenotype was fully suppressed in a Ca(2+)-independent background lacking the injectisome-associated inner-membrane component YscV but not peripheral YscK, suggesting that the core translocon energizes YopD.

Attenuated enzootic (pestoides) isolates of Yersinia pestis express active aspartase.

It is established that Yersinia pestis, the causative agent of bubonic plague, recently evolved from enteropathogenic Yersinia pseudotuberculosis by undergoing chromosomal degeneration while acquiring two unique plasmids that facilitate tissue invasion (pPCP) and dissemination by fleabite (pMT). Thereafter, plague bacilli spread from central Asia to sylvatic foci throughout the world. These epidemic isolates exhibit a broad host range including man as opposed to enzootic (pestoides) variants that remain in ancient reservoirs where infection is limited to muroid rodents. Cells of Y. pseudotuberculosis are known to express glucose-6-phosphate dehydrogenase (Zwf) and aspartase (AspA); these activities are not detectable in epidemic Y. pestis due to missense mutations (substitution of proline for serine at amino position 155 of Zwf and leucine for valine at position 363 of AspA). In this study, functional Zwf was found in pestoides strains E, F and G but not seven other enzootic isolates; enzymic activity was associated with retention of serine at amino acid position 155. Essentially, full AspA activity occurred in pestoides isolates where valine (pestoides A, B, C and D) or serine (pestoides E, F, G and I) occupied position 363. Reduced activity occurred in strains Angola and A16, which contained phenylalanine at this position. The kcat but not Km of purified AspA from strain Angola was significantly reduced. In this context, aspA of the recently described attenuated enzootic microtus biovar encodes active valine at position 363, further indicating that functional AspA is a biomarker for avirulence of Y. pestis in man.

A missense mutation causes aspartase deficiency in Yersinia pestis.

It is established that cells of Yersinia pestis, the causative agent of bubonic plague, excrete l-aspartic acid at the expense of exogenous l-glutamic acid during expression of the low-calcium response. Results of enzymic analysis provided here suggest that a previously defined deficiency of aspartase (AspA) accounts for this phenomenon rather than an elevated oxaloacetate pool. The only known distinction between most sequenced isolates of aspA from Y. pestis and the active gene in Yersinia pseudotuberculosis (the immediate progenitor of Y. pestis) is a single base transversion (G.C-->T.A) causing replacement of leucine (encoded by UUG) for valine (encoded by GUG) at amino acid position 363. The gene from Y. pestis KIM possesses a unique second transversion (G.C-->T.A) at amino acid 146 causing substitution of aspartic acid (encoded by GAU) with tyrosine (encoded by UAU). We show in this study that Y. pestis expresses aspA as cross-reacting immunological material (CRIM). Functional and inactive aspA of Y. pseudotuberculosis PB1 and Y. pestis KIM, respectively, were then cloned and expressed in AspA-deficient Escherichia coli. After purification to near homogeneity, the products were subjected to biochemical analysis and found to exhibit similar secondary, tertiary and quaternary (tetrameric) structures as well as comparable Michaelis constants for l-aspartic acid. However, the k(cat) of the Y. pestis CRIM of strain KIM is only about 0.1 % of that determined for the active AspA of Y. pseudotuberculosis. Return of valine for leucine at position 363 of the Y. pestis enzyme restored normal turnover (k(cat) 86+/-2 s(-1)) provided that the amino acid substitution at position 146 was also reversed. These observations have important implications for understanding the nature of the stringent low-calcium response of Y. pestis and its role in promoting acute disease.