Adaptation of Postural Sway in a Standing Position during Tilted Video Viewing Using Virtual Reality: A Comparison between Younger and Older Adults.

This study aimed to investigate the effects of wearing virtual reality (VR) with a head-mounted display (HMD) on body sway in younger and older adults. A standing posture with eyes open without an HMD constituted the control condition. Wearing an HMD and viewing a 30°-tilt image and a 60°-tilt image in a resting standing position were the experimental conditions. Measurements were made using a force plate. All conditions were performed three times each and included the X-axis trajectory length (mm), Y-axis trajectory length (mm), total trajectory length (mm), trajectory length per unit time (mm/s), outer peripheral area (mm2), and rectangular area (mm2). The results showed a significant interaction between generation and condition in Y-axis trajectory length (mm) and total trajectory length (mm), with an increased body center-of-gravity sway during the viewing of tilted VR images in older adults than in younger adults in both sexes. The results of this study show that body sway can be induced by visual stimulation alone with VR without movement, suggesting the possibility of providing safe and simple balance training to older adults.

The Relationship between Modified Short Physical Performance Battery and Falls: A Cross-Sectional Study of Older Outpatients.

The Short Physical Performance Battery (SPPB) is a physical fall-risk screening tool and predictor of adverse health effects for the older. Its limited use in Japan is due to the relative ease for high-functioning older adults to achieve perfect scores. Japanese researchers thus created a community-based SPPB (SPPB-com). This study investigated whether the SPPB-com score can distinguish between older patients classified as "fallers" and "non-fallers." Participants comprised 185 older outpatients aged 65 and above who self-reported their history of accidental falls and relevant physical activity. Fall risk was assessed using SPPB and SPPB-com. Handgrip strength, maximum isometric knee extensor strength, and maximum walking speed were measured as physical functions. Multivariate logistic regression and receiver-operating characteristic analyses determined criteria indicating faller status. Fallers were older and had lower physical function, physical activity, SPPB, and SPPB-com scores than non-fallers. Multivariate logistic regression analysis showed SPPB (OR 0.76, 95% CI 0.59-0.99, p = 0.045) and SPPB-com (OR 0.63, 95% CI 0.45-0.87, p = 0.005) scores were both independently associated with prior falls. The SPPB-com score may function as a fall-risk assessment tool for older outpatients, and its combined use with SPPB can increase the accuracy and precision of distinction between fallers and non-fallers.

DANCE/fibulin-5 promotes elastic fiber formation in a tropoelastin isoform-dependent manner.

OBJECTIVE: To investigate a function of fibulin-5 in the elastic fiber formation, we studied the molecular interactions among elastin, fibrillin-1, and fibulin-5 in the extracellular space and the maturation of tropoelastin using retinal pigment epithelial cells (ARPE-19). DESIGN AND METHODS: Bacterial recombinant tropoelastin (rTE) was added to ARPE-19 cells overexpressing V5-tagged fibulin-5 (ARPE-Fibulin-5). These elastic fibers were evaluated by immunofluorescence staining, the quantitative analysis of cross-linked amino acids, and semi-quantitative analysis of matrix-associated tropoelastin. RESULTS: Immunoprecipitation assays revealed that fibulin-5 is able to separately interact with tropoelastin or fibrillin-1 in the culture medium. Moreover, immunofluorescent staining showed that elastin, fibrillin-1, and fibulin-5 co-localize in the extracellular matrix. Desmosine levels were significantly increased in ARPE-Fibulin-5 relative to untransfected cells in spite of equal deposition of tropoelastin by enzyme-linked immunosorbent assay. The addition of a tropoelastin isoform, which lacked the peptide encoded by exon 26A (Delta26A) and could bind to fibulin-5 strongly, led to a larger increase in cross-linking amino acids compared to tropoelastin containing the exon 26A peptide sequence. CONCLUSION: These data provide new insights into the initial steps of elastic fiber assembly and identify fibulin-5 and tropoelastin isoforms as potential targets for the regeneration of elastic fibers in vivo.

Characterization of the molecular interaction between tropoelastin and DANCE/fibulin-5.

Fibulin-5 is believed to play an important role in the elastic fiber formation. The present experiments were carried out to characterize the molecular interaction between fibulin-5 and tropoelastin. Our data showed that the divalent cations of Ca(2+), Ba(2+) and Mg(2+) significantly enhanced the binding of fibulin-5 to tropoelastin. In addition, N-linked glycosylation of fibulin-5 does not require for the binding to tropoelastin. To address the fibulin-5 binding site on tropoelastin constructs containing, exons 2-15 and exons 16-36, of tropoelastin were used. Fibulin-5 binding was significantly reduced to either fragment and also to a mixture of the two fragments. These results suggested that the whole molecule of tropoelastin was required for the interaction with fibulin-5. In co-immunoprecipitation experiments, tropoelastin binding to fibulin-5 was enhanced by an increase of temperature and sodium chloride concentration, conditions that enhance the coacervation of tropoelastin. The binding of tropoelastin fragments to fibulin-5 was directly proportional to their propensity to coacervate. Furthermore, the addition of fibulin-5 to tropoelastin facilitated coacervation. Taken together, the present study shows that fibulin-5 enhances elastic fiber formation in part by improving the self-association properties of tropoelastin.

Distinct steps of cross-linking, self-association, and maturation of tropoelastin are necessary for elastic fiber formation.

Elastic fibers play an important role in the characteristic resilience of many tissues. The assembly of tropoelastin into a fibrillar matrix is a complex stepwise process and the deposition and cross-linking of tropoelastin are believed to be key steps of elastic fiber formation. However, the detailed mechanisms of elastic fiber assembly have not been defined yet. Here, we demonstrate the relationship between deposition and the cross-linking/maturation of tropoelastin. Our data show that a C-terminal half-fragment of tropoelastin encoded by exons 16-36 (BH) is deposited onto microfibrils, yet we detect very limited amounts of the cross-linking amino acid, desmosine, an indicator of maturation, whereas the N-terminal half-fragment encoded by exons 2-15 (FH) was deficient for both deposition and cross-linking, suggesting that elastic fiber formation requires full-length tropoelastin molecules. A series of experiments using mutant BH fragments, lacking either exon 16 or 30, or a deletion of both exons showed that self-association of tropoelastin polypeptides was an early step in elastic fiber assembly. Immunofluorescence and Western blot assay showed that the treatment of cell culture medium or conditioned medium with beta-aminopropionitrile to inhibit cross-linking, prevented both the deposition and polymerization of tropoelastin. In conclusion, our present results support the view that self-association and oxidation by lysyl oxidase precedes tropoelastin deposition onto microfibrils and the entire molecule of tropoelastin is required for this following maturation process.

Induction of matrix metalloproteinase-9 secretion from human keratinocytes in culture by ultraviolet B irradiation.

BACKGROUND: Matrix metalloproteinases (MMPs) are known as important enzymes involved in tissue metabolism. Among them, MMP-2 and MMP-9 are termed gelatinases, but their specific roles in vivo are still unknown, including their expression patterns following ultraviolet (UV) irradiation. OBJECTIVE: To elucidate the effects of UV irradiation on the skin, we analyzed the expression of MMP-2 and MMP-9 by primary human keratinocytes in culture. METHODS: We evaluated the enzymatic functions of MMP-2 and MMP-9 by gelatin-zymography, and of MMP-9 expression by immunofluorescence, using cultured keratinocytes after UV irradiation. RESULTS: The secretion of MMP-2 (72 kDa) remained at low levels under all conditions examined. Although MMP-9 (92 kDa) secretion was not induced by UVA, it was stimulated by UVB irradiation in a dose-dependent manner. In addition, an enzyme-linked immunosorbent assay showed the tendency to increase for the involucrin expression following UVB exposure. Cell viability was decreased by UVB irradiation in contrast to the induction of MMP-9 and involucrin. CONCLUSION: These results suggest that the induction of MMP-9 secretion is related to the inflammation including apoptosis of keratinocytes resulting from UVB irradiation.