Acceptance of digital health services among older adults: Findings on perceived usefulness, self-efficacy, privacy concerns, ICT knowledge, and support seeking.

Background: Over the last decade, the rapid advancements in information and communication technologies (ICTs) have also driven the development of digital health services and applications. Older adults could particularly benefit from these technologies, but they still have less access to the Internet and less competence in using it. Based on the empirical literature on technology acceptance among older adults, this study examines the relations of perceived usefulness, self-efficacy, privacy concerns, ICT knowledge, and support seeking (family, informal, formal/institutional) with older adults' intention to adopt new digital health services. Methods: The study included 478 older adults who participated in an online or paper/pencil questionnaire (M = 70.1 years, SD = 7.8; 38% male). Sociodemographic characteristics, subjective health status, and variables related to technology acceptance were assessed. Results: Latent structural equation modeling revealed that higher perceived usefulness, higher self-efficacy regarding digital health technologies, and lower privacy concerns contributed to a higher intention to use digital health services among older adults. Contrary to our expectations, general ICT knowledge was not a significant predictor. Older adults who reported seeking more support regarding technology problems from family members and formal/institutional settings also reported higher usage intentions, whereas informal support was not as relevant. Furthermore, higher age was associated with higher perceived usefulness and lower self-efficacy. Discussion: Future studies should further explore mediating factors for intention and actual use of digital health services and develop educational programs including follow-up assessments.

Contrasting Internet Adoption in Early and Advanced Old Age: Does Internet Self-Efficacy Matter?

OBJECTIVES: Understanding why older adults (including those in very old age) use or do not use the Internet can build on the technology acceptance model (TAM). In this cross-sectional study, we translate the TAM to the Internet and assume that perceived usefulness of the Internet (PUI) and perceived ease of use of the Internet (PEUI) will be revealed as major predictors of behavioral intention to use the Internet (BII). Additionally, we consider the role of Internet self-efficacy (ISE) as another major factor for older adults' Internet use. We also argue that life phase, particularly early as opposed to advanced old age, may moderate how PUI, PEUI, and ISE relate to BII. METHODS: A sample of 1,200 older adults aged 60 years and older (60-74 years, n = 658; 75-99 years, n = 542) was randomly drawn from the city of Stuttgart, Germany. Sociodemographic variables and major indicators of TAM and ISE were assessed based on a computer-assisted telephone interviewing procedure. RESULTS: Latent structural equation modeling revealed that PUI is the more important predictor of BII in older adults. Furthermore, ISE revealed statistically meaningful positive links with PUI, PEUI, and BII. Multigroup comparison revealed that PUI had a stronger linkage with BII in early old age, whereas ISE was more important for BII in advanced old age. DISCUSSION: The results suggest that ISE may enrich the network of TAM constructs among older adults in general but specifically in advanced old age.

Hsc70 and Hsp70 interact with phosphatidylserine on the surface of PC12 cells resulting in a decrease of viability.

Heat shock proteins (hsps) are involved in multiple cellular processes during normal and stress conditions, particularly in the folding of polypeptides. A newly recognized property of the members of the Hsp70 family is their ability to interact with lipids, opening ion conductance pathways in artificial membranes, and integrating into natural membranes. The formation of Hsp70 channels in biological membranes and their function is still elusive. In this study, we showed that Hsp70 and Hsc70 display a highly selective interaction with phosphatidylserine moieties on membranes, followed by rapid incorporation into the lipid bilayer. Addition of Hsp70 or Hsc70 into the extracellular medium resulted in a viability decrease of cells beading PS on the exterior surface, such as PC12 cells. This toxic effect is modulated by the presence of ATP or ADP and can be blocked by screening PS moieties with annexin 5. These observations suggest that the presence of Hsp70 in the extracellular medium may be an accelerator of apoptosis since the presence of PS on the surface is an early indicator of this process. These findings may also explain the toxicity observed in cells overexpressing Hsp70s and provide a rational for the tight regulation of Hsp70 expression.

Aggregation of liposomes induced by the toxic peptides Alzheimer's Abetas, human amylin and prion (106-126): facilitation by membrane-bound GM1 ganglioside.

To compare both the peptide molecular self-aggregation and the interaction with membrane lipids of the Alzheimer's amyloid beta (Abeta)40, Abeta42 peptides, and the cytotoxic peptides human amylin and prion (106-126) peptides, we applied a liposome aggregation technology. The kinetics of the changes in the optical density (DeltaOD) of liposome suspensions generated by the aggregation of liposomes induced by these peptides, allowed us to comparatively analyze their phospholipid affinity and self-aggregation. The kinetic curves showed an initial nonlinear region where d(DeltaOD)/dt followed first order kinetics corresponding to the binding of the peptides to the membrane of the liposome, a linear region where d(DeltaOD)/dt was constant, corresponding to the interaction between two membrane-bound peptide molecules, and a final slower increasing nonlinear region that corresponds to nucleation or seeding of aggregation. The analysis of the aggregation curves demonstrated that amylin and prion peptides also showed affinity for the acidic phospholipid phosphatidylserine (PS), as it has previously been shown for the Alzheimer's Abeta40, Abeta42 peptides. Abeta42 showed the highest, and amylin the lowest, affinity for the liposome membrane. When bound to the membrane of the liposomes, all the peptides preserved the self-aggregation characteristics observed in solution. Aging the Abeta40 and Abeta42 peptide solutions that permit molecular self-aggregation reduced their capacity to induce liposome aggregation. The self-aggregation of membrane-bound prion molecules was several orders of magnitude higher than that observed for the other toxic peptides. Incorporation of the ganglioside GM1 into the membrane of liposomes enhanced the peptide-induced liposome aggregation. Kinetic analysis revealed that this enhancement was due to facilitation of the formation of bridges between membrane-bound peptide molecules, demonstrating that the peptide-membrane interaction and the peptide amyloidogenesis are independent functions performed at separate molecular regions.

Plasma membrane cholesterol controls the cytotoxicity of Alzheimer's disease AbetaP (1-40) and (1-42) peptides.

Cell degeneration in Alzheimer's disease is mediated by a toxic mechanism that involves interaction of the AbetaP peptide with the plasma membrane of the target cell. We report here that PC12 cells become resistant to the cytotoxic action of AbetaP when incubated in a medium that enriches cholesterol levels of the surface membrane. On the other hand, making cholesterol-deficient membranes by either cholesterol extraction with cyclodextrin or by inhibiting de novo synthesis of cholesterol makes PC12 cells more vulnerable to the action of AbetaP. Increasing cholesterol content of PS liposomes also suppresses AbetaP-dependent liposome aggregation. We suggest that by modifying the fluidity of the neuronal membranes, cholesterol modulates the incorporation and pore formation of AbetaP into cell membranes. This idea is supported by our finding that the enhanced cytotoxicity generated by lowering the membrane cholesterol content can be reversed by AbetaP calcium channel blockers Zn2+ and tromethamine.

Lipid interaction differentiates the constitutive and stress-induced heat shock proteins Hsc70 and Hsp70.

Heat shock proteins play a major role in the process of protein folding, and they have been termed molecular chaperones. Two members of the Hsp70 family, Hsc70 and Hsp70, have a high degree of sequence homology. But they differ in their expression pattern. Hsc70 is constitutively expressed, whereas Hsp70 is stress inducible. These 2 proteins are localized in the cytosol and the nucleus. In addition, they have also been observed in close proximity to cellular membranes. We have recently reported that Hsc70 is capable of interacting with a lipid bilayer forming ion-conductance channels. In the present study, we found that both Hsc70 and Hsp70 interact with lipids and can be differentiated by their characteristic induction of liposome aggregation. These proteins promote the aggregation of phosphatidylserine liposomes in a time- and protein concentration-dependent manner. Although both proteins are active in this process, the level and kinetics of aggregation are different between them. Calcium ions enhance Hsc70 and Hsp70 liposome aggregation, but the effect is more dramatic for Hsc70 than for Hsp70. Addition of adenosine triphosphate blocks liposome aggregation induced by both proteins. Adenosine diphosphate (ADP) also blocks Hsp70-mediated liposome aggregation. Micromolar concentrations of ADP enhance Hsc70-induced liposome aggregation, whereas at millimolar concentrations the nucleotide has an inhibitory effect. These results confirm those of previous studies indicating that the Hsp70 family can interact with lipids directly. It is possible that the interaction of Hsp70s with lipids may play a role in the folding of membrane proteins and the translocation of polypeptides across membranes.