A theoretical and empirical review of psychological factors associated with falls-related psychological concerns in community-dwelling older people.

BACKGROUND: Four constructs are encompassed by the term "falls-related psychological concerns" (FrPC); "fear of falling" (FOF), "falls-related self-efficacy" (FSe), "balance confidence" (BC) and "outcome expectancy" (OE). FrPC are associated with negative consequences including physical, psychological, and social. Identifying factors associated with FrPC could inform interventions to reduce these concerns. METHODS: Sixty-two empirical papers relating to psychological factors associated with FrPC in community-dwelling older people (CDOP) were reviewed. Four levels of evidence were used when evaluating the literature: good, moderate, tentative, and none. RESULTS: Evidence that anxiety predicted FOF, BC, and OE was tentative. Moderate evidence was found for anxiety predicting FSe. Good evidence was found for depression predicting FSe. Moderate evidence was found for depression predicting both FOF and BC. No evidence was found for depression predicting OE. Tentative evidence was found for FSe predicting depression. Good and moderate evidence was found for quality of life (QoL) being predicted by FOF and BC respectively. Tentative evidence was found for FSe predicting QoL. Moderate evidence was found for QoL predicting both FSe and BC. No evidence was found for QoL predicting FOF. Good and moderate evidence was found for activity avoidance/restriction (AA/AR) being predicted by FOF and FSe respectively. Tentative evidence was found for BC and OE predicting AA/AR, as well as for AA/AR predicting FOF. Moderate evidence for activity level (AL) predicting FOF was identified, however the evidence of this predicting FSe and BC was tentative. Evidence for FOF, FSe, and BC predicting AL was tentative as was evidence to suggest FOF predicted coping. CONCLUSIONS: Mixed evidence has been found for the association of psychological factors in association with FrPCs. Future research should employ theoretically grounded concepts, use multivariate analysis and longitudinal designs.

Endothelial cells augment T cell interleukin 2 production by a contact-dependent mechanism involving CD2/LFA-3 interaction.

We have demonstrated that endothelial cells (EC) augment IL-2 production by PHA-stimulated PBMC or purified CD4+ T cells and that the increase is apparent both in the amount of soluble IL-2 secreted and in the level of specific mRNA detectable by Northern blot hybridization. The ability of EC to affect levels of IL-2 cannot be reproduced by soluble factors, including the cytokines IL-1, IL-6, IFN-gamma, or TNF, conditioned medium from resting EC or IL-1, IFN-gamma- or TNF-treated EC, or from resting PBMC + EC cultures. Separation of the EC and PBMC by a Transwell membrane demonstrated that cell contact was required for augmentation of IL-2 synthesis and that this effect was unlikely to be mediated by a short-lived soluble signal. The cell-cell interaction required the ligand pair CD2/LFA-3, since augmentation could be inhibited by antibodies to these structures. Antibodies to ICAM-1, LFA-1, CD4, and MHC class II were without effect. A contact-dependent pathway involving CD2/LFA-3 interactions also may be used by EC to augment IL-2 production from T cells stimulated more specifically through the TCR/CD3 complex with antibody OKT3. This pathway provides a proliferative advantage to T cells stimulated with OKT3 in the presence of EC and may also be involved in the proliferative response of resting T cells to allogeneic class II MHC-expressing EC. We propose that EC augmentation of T cell IL-2 synthesis may be critical in the ability of EC to elicit primary T cell antigen responses and may have consequences for the development of localized cell-mediated immune reactions.

IL-4 and IL-13 activate the JAK2 tyrosine kinase and Stat6 in cultured human vascular endothelial cells through a common pathway that does not involve the gamma c chain.

IL-4 and IL-13 each act on human endothelial cells (ECs) to induce expression of vascular cell adhesion molecule-1. On hematopoietic cells. IL-4 responses may be mediated either through a pathway involving gc, the common signaling subunit of the IL-2, IL-4, IL-7, IL-9, and IL-15 receptors, or through a gc-independent pathway that may be alternatively activated by IL-13. We find that human ECs do not express gc, as detected by indirect immunofluorescence and FACS analysis or by a reverse transcription-PCR method. Like IL-4, IL-13 activates a protein tyrosine kinase that phosphorylates the IL-4R binding protein. In addition, we find that IL-4 and IL-13 each induce tyrosine phosphorylation of the JAK2 tyrosine kinase. Furthermore, both IL-4 and IL-13 induce binding of the Stat6 transcription factor to a consensus sequence oligonucleotide. We conclude that the IL-4 response of human ECs involves the IL-13 shared pathway that is independent of gc, and uses JAK2-Stat6 signaling.

Blockade of CD2-LFA-3 interactions protects human skin allografts in immunodeficient mouse/human chimeras.

A human skin allograft injury model in immunodeficient mice, engrafted with human peripheral blood mononuclear cells from a different donor, has been used to test whether reagents that block human T cell CD2 interactions with its principal ligand, LFA-3 (CD58), can inhibit immune reactions in vivo. In this model, human skin grafts show a reproducible pattern of progressive human T-cell infiltration and human graft microvascular injury that resembles human first-set skin graft rejection. Murine Mab to human LFA-3 or human LFA-3-IgG1 fusion protein, but not isotype-matched control antibodies, each markedly protected skin grafts from leukocyte infiltration and injury. These data provide the first evidence that LFA-3 functions in vivo and establish the ability of this new model to test human-specific immune modulators.

Lipid synthesis by rat brain microvessel endothelial cells in tissue culture.

Lipid synthesis and its regulation by serum lipoproteins at the microvascular blood-brain barrier were studied using primary cultures of microvascular endothelial cells from rat brain. These cells are capable of synthesizing all their lipids (neutral lipids, phospholipids, glycolipids) from the water-soluble compounds, glucose, acetate, acetoacetate and beta-hydroxybutyrate. The ketone bodies, especially acetoacetate, are the preferred substrates for lipid synthesis. The incorporation patterns of acetate, acetoacetate and beta-hydroxybutyrate are very similar, indicating that these precursors contribute to lipid synthesis via the same metabolic route. However, the metabolic pathway is different for glucose, which is preferentially incorporated into phospholipids. The existence of an inverse relationship between lipid synthesis and the serum lipoprotein concentration suggests that cultured cerebral endothelial cells are capable of taking up lipids, principally cholesterol, contained in the serum lipoproteins. Cellular lipids would thus be supplied both by intracellular lipid synthesis and by serum lipoproteins. The difference between cholesterol synthesis rates in cultured cerebral endothelial cells and in isolated brain microvessel cells could be partly explained by the fact that the lipoprotein concentration is much lower in the culture medium than in rat serum.

Consistent transient transfection of DNA into non-transformed human and murine T-lymphocytes.

The ability to analyze transcriptional regulation in non-transformed T-cells has been hampered by the inability to reproducibly transiently transfect these cells with DNA constructs. We have previously demonstrated that normal human whole mononuclear and CD4 T-cells can be consistently transiently transfected with plasmid DNA. Human cells were most receptive to plasmid DNA uptake between 19.5 and 20 h after prestimulation with a submitogenic dose of the polyclonal T-cell activator, PHA. Here we report an alteration and optimization of this protocol for non-transformed murine splenic T-cells, using concanavalin A instead of PHA as the preactivation stimulus. When coupled with the high sensitivity of luciferase reporter gene constructs, this protocol facilitates the analysis of a variety of T-cell-specific promoters in non-transformed T-cells. In addition, we directly demonstrate that murine T-cells are specifically transiently transfected among a population of whole mononuclear cells by using an expression vector for green fluorescent protein.

Human CD4+ T cells proliferate to HLA-DR+ allogeneic vascular endothelium. Identification of accessory interactions.

Serially passaged human endothelial cell (EC) cultures will stimulate highly purified peripheral blood CD4+ T cells to proliferate if and only if the EC cultures are pretreated with IFN-gamma to induce de novo expression of MHC class II molecules, principally HLA-DR. HLA-DR-expressing EC alone appear sufficient to stimulate purified CD4+ T cell proliferation without the involvement of other leukocyte populations, as indicated by the following observations: (1) we find no contaminating leukocytes in our EC cultures by FACS analysis or fluorescence microscopy; specifically, there are no detectable CD45 or HLA-DR expressing cells; (2) neither the EC cultures nor the purified CD4+ T cells contain HLA-DR expressing cells detectable by polymerase chain reaction (PCR) of reverse-transcribed mRNA; (3) the stimulatory capacity of the EC cultures is maintained through serial subculture and through low-density replating, indicating that the stimulatory cell type must proliferate in culture as well as EC; and (4) in contrast to MLRs, the response to EC cultures is not inhibited by pretreatment of the stimulator cells and/or responding T cells with the monocyte toxin L-leucine-O-methyl ester. We have used mAb to investigate the role of various EC and T cell surface molecules in the T cell response. mAb to HLA-DR and CD4 inhibit proliferative responses of CD4+ T cells to EC cultures, as would be expected if T cells recognize and proliferate to IFN-gamma-induced allogeneic class II MHC molecules; whereas, also as expected, mAb to class I MHC molecules were without effect. Proliferation is also inhibited by mAbs to T cell CD2 and LFA-1 beta chain (CD18) and by mAbs to LFA-3 (CD58) and CD44, which are expressed by T cells and EC. mAb to ICAM-1 (CD54, a ligand for LFA-1) provides inconsistent inhibition, and mAb to ICAM-2, used with or without anti-ICAM-1, is not inhibitory. Because both of these mAb block adhesion of LFA-1 expressing T cells to EC, our data suggest that additional ligands for LFA-1 must be important for allogeneic proliferation. mAb to VLA-4 alpha or beta chains (CD49d, CD29) enhance proliferation, presumably through direct costimulation of the T cells by these antibodies. However, a mAb to VCAM-1, an EC ligand for VLA-4, is partially inhibitory.(ABSTRACT TRUNCATED AT 400 WORDS)

The potential roles of vascular endothelium in immune reactions.

Cell-mediated immune reactions are initiated and regulated by antigen specific CD4+ helper T cells. However, T cells cannot function independently. In order for a CD4+ T cell to recognize antigen, it must be presented in association with a class II major histocompatibility complex molecule by another cell type and, in order to lead to functional T-cell activation, the antigen presenting cell must also provide costimulatory signals. Once activated, CD4+ T cells function in vivo by secreting cytokines that elicit an inflammatory infiltrate of other cell types that serves to eliminate the source of foreign antigen. In vivo, the development of inflammation requires vascular responses as well as contributions of blood-derived leukocytes. Although several cell types in vitro can present antigen, provide costimulation, and perform actions that contribute to inflammation, vascular endothelial cells may be uniquely important immune accessory cells because they are anatomically uniquely positioned to function in vivo during cell-mediated immune reactions. In this report, we shall review recent data from our laboratories which further characterize the immune accessory functions of endothelial cells.

Uptake of leucine and alanine by cultured cerebral capillary endothelial cells.

Pure cultures of rat cerebral capillary endothelium have been used to study the A- and L-systems of amino acid transport. Leucine is taken up by a non-concentrative mechanism that can be saturated, and competitively inhibited by phenylalanine. Uptake is rapid, with equilibration apparent after 3-5 min (all experiments performed at 37 degrees C). The Km for transport was 83 microM +/- 26 (mean +/- S.E.M., n = 3) which is in good agreement with recent in vivo reports using unanaesthetised rats. Alanine was transported by a saturable, concentrative mechanism. Dependence on Na+-ions was demonstrated by lack of specific uptake in Na+-free buffer and reduced uptake after preincubation in ouabain--a Na+,K+-ATPase inhibitor. The Km for transport was 325 microM +/- 88 (mean +/- S.E.M., n = 3). The finding of an active A-system transporter in vitro suggests that the cells may have lost the polarity they demonstrate in vivo. The relevance of these findings to transport of nutrients and drugs across the blood-brain barrier is discussed.

Brain capillary endothelial cells in vitro lack surface IgG Fc receptors.

A reliable technique to produce consistently pure cultures of endothelial cells prepared from isolated rat brain capillaries has been established. The cells express many of the morphological and antigenic characteristics of endothelium in vivo, including the formation of tight junctions and possession of Factor VIII/von Willebrand Factor antigen (FVIII/vWF) and angiotensin converting enzyme (ACE). Using indirect immunofluorescence, surface IgG Fc receptors (FcR) could not be demonstrated, either when the cells were incubated in aggregated IgG, or in adult rat serum. Rat peritoneal macrophages served as a positive control. However, permeabilization of the endothelial cells with glacial acetic acid/ethanol prior to incubation with IgG allowed the demonstration of internal binding sites. The lack of surface receptors in the normal state does not rule out the possibility of their induction during pathological conditions.

A morphometric study of blood vessel, neuron and glial cell distribution in young and old rat brain.

The distribution of blood vessels, neurons and glial cells through the depth of the cortex in young and old rats has been investigated using semi-automatic quantitative morphometry. Toluidine blue stained semithin sections cut perpendicularly to the surface of the brain and spanning pia to white matter were analysed. There was a strong correlation between the distribution of blood vessels and neurons (P less than 0.001), with peaks in numerical density (Na) occurring at histological layers IV and VI. This correlation was not altered with age. Glial cell distribution was not correlated with either vessel or neuron distribution, but may be related to areas of high synaptic density. In the older animals (90 weeks) blood vessel Na and surface area to volume ratio (Sv) were significantly increased as was glial Na. Neuron Na was unaltered. These changes and the significant decrease in cortical thickness also found are consistent with neuronal loss in ageing and especially, preferential loss at layer IV.

Cultures in conflict: a challenge to faculty of academic health centers.

Academic health centers (AHCs) are experiencing turmoil in all three of their traditional missions of teaching, research, and patient care. The authors examine origins of universities and medical education to place in historical context the stresses affecting AHCs at the end of the 20th century. They describe the cultures of the university to suggest strategies for successful adaptation to these stresses. Clashes of values and norms of the cultures within universities and AHCs can hinder effective adaptation to external change. Administrators, researchers, teachers, and clinicians can have strongly conflicting perspectives. For example, business skill is of increasing importance to the survival of the clinical enterprise, but not typically valued by faculty members. University faculty have often considered accountability as antithetical to academic freedom, and, until recently, accountability was not strongly demanded of AHCs. The authors conclude that AHC faculty must transcend the outdated view that the roles of the scholar, scientist, and healer are in opposition to those of the leader and manager. If AHCs are to survive and prosper through their current cultural transition, their faculty must understand all these roles as part of their intellectual and organizational responsibility.

The family as patient in family medicine. Rhetoric or reality?

Considerable attention has been paid to the role of the family as a system in its own right, rather than the individual patient, as the fundamental unit of health care delivery. Despite the apparent validity of this concept, many important questions remain unanswered. Among these are: (1) Is there sufficient understanding of family pathophysiology, of the sensitivity and specificity of diagnostic techniques and of the safety and efficacy of therapeutic modalities to make true family health care possible? (2) If this type of care is possible, how are the needs of the family and its individual members met, or value judgements made about their relative importance? and (3) What are the consequences for the health care delivery system of this type of care? An extensive literature review is used in an attempt to answer these queries, from which questions for further study are posed.

A need for community education in development: the Mit Abu El Kom case.

A quasi-experimental study was performed in Mit Abu El Kom Village, Egypt, where one-quarter of the 500 village households had been provided with new housing and indoor water and sanitation facilities and where, prior to this provision, water and sanitation facilities were inadequate or nonexistent among all households. No community health education had taken place among relocatees (subjects) or nonrelocatees (controls) in conjunction with the provision of water and sanitation facilities. This study investigated if subjects' access and exposure to facilities had alone been sufficient to significantly alter their relevant knowledge, attitudes and practices as compared to controls. This was accomplished primarily through structured household interview. Given that women are traditionally most affected by facilities and most effective in matters related to household health, one adult female from each sampled household was the respondent, totalling 123 for subjects and 111 for controls. Between-group comparisons of responses revealed overall nonsignificant differences in knowledge and attitudes and that respondent age and sex had no significant overall impact on responses. Age and sex were also discounted as affecting variables in within-group response analyses. Some significant changes in practices had occurred among subjects. However, these mainly resulted out of convenience and their potential benefits were often denigrated by changes which had not occurred or had not continued. The data indicate a need for community health education if health-related benefits of water and sanitation facilities are to be realized, and specifically indicate the need to address the educational needs of all village women.

Obesity and perceptual reactance.

Similarities in anomalous perception of internal gastric states and sensitivity to distraction among the obese to variations in perceptual reactance suggest that the obese tend to augment the intensity of visceral cues associated with hunger. It was hypothesized that the obese would be overrepresented at the augmenter end of the perceptual reactance continuum. Thirteen obese (six male, seven female) and 14 nonobese (eight male, six female) college students participated in a study in which perceptual reactance was assessed by degree of Kinesthetic Figural Aftereffect (KFA). A highly significant relationship in the predicted direction was observed for perceptual reactance category and mean percent weight deviation. Additionally, there was a highly significant interaction of sex by category, with the hypothesized relationship intensified for the female Ss. Results supported interpretation of obesity as a consequence of animalous perception of cues associated with consuming behavior.

A screen for short-range paracrine interactions.

Conventional methods for studying paracrine signaling in vitro may not be sensitive to short-range effects resulting from signal dilution or decay. We employ a microfabricated culture substrate to maintain two cell populations in microscale proximity. Individual populations can be quickly retrieved for cell-specific readouts by standard high-throughput assays. We show that this platform is sensitive to short-range interactions that are not detectable by common methods such as conditioned media transfer or porous cell culture inserts, as revealed by gene expression changes in a tumor-stromal crosstalk model. In addition, we are able to detect population-specific gene expression changes that would have been masked in mixed co-cultures. We thus demonstrate a tool for investigating an important class of intercellular communication that may be overlooked in conventional biological studies.

Virus infection in remnant native bunchgrasses from invaded California grasslands.

This study examined the effects of infection with barley and cereal yellow dwarf viruses (BYDVs) on wild grass species in California, a region in which native perennial bunchgrasses have been largely replaced by exotic annual grasses. We sought to determine whether these widespread viruses compromise the fitness of wild hosts and thus have the potential to influence grassland dynamics. Plant viruses have been long overlooked in ecological studies, and their influence on wild hosts has often been assumed to be minimal. We examined the short-term and long-term consequences of infection on field-grown individuals from 18 different populations of wild California grasses (from seven native and one exotic species). Barley yellow dwarf virus infection was aggressive in most hosts and markedly impaired host fitness by reducing growth, survivorship, and fecundity. Previous work indicates that the presence of exotic grasses can more than double BYDV incidence in natives. Given the ubiquity of BYDVs, our results suggest that apparent competition and other virus-mediated processes may influence interactions among native and exotic grasses and potentially contribute to shifts in grassland community composition.

Transcriptional regulation of the interleukin-2 gene in normal human peripheral blood T cells. Convergence of costimulatory signals and differences from transformed T cells.

To study transcriptional regulation in normal human T cells, we have optimized conditions for transient transfection. Interleukin-2 (IL-2) promoter-reporter gene behavior closely parallels the endogenous gene in response to T cell receptor and costimulatory signals. As assessed with mutagenized promoters, the most important IL-2 cis-regulatory elements in normal T cells are the proximal AP-1 site and the NF- kappaB site. Both primary activation, with phytohemagglutinin or antibodies to CD3, and costimulation, provided by pairs of CD2 antibodies or B7-positive (B cells) or B7-negative (endothelial) accessory cells, are mediated through the same cis-elements. Interestingly, the nuclear factor of activated T cell sites are much less important in normal T cells than in Jurkat T cells. We conclude that IL-2 transcriptional regulation differs in tumor cell lines compared with normal T cells and that different costimulatory signals converge on the same cis-elements in the IL-2 promoter.

Endothelial cell costimulation of T cell activation through CD58-CD2 interactions involves lipid raft aggregation.

Human endothelial cells (EC) costimulate CD4(+) memory T cell activation through CD58-CD2 interactions. In this study we tested the hypothesis that EC activate distinct costimulatory pathways in T cells that target specific transcription factors. AP-1, composed of fos and jun proteins, is a critical effector of TCR signaling and binds several sites in the IL-2 promoter. EC augment c-fos promoter activity in T cells; however, deletion analysis reveals no transcription factor binding sites in the promoter uniquely responsive to EC costimulation. Overexpression of AP-1 proteins in T cells augments the activity of an AP-1-luciferase reporter gene equally in the absence or the presence of EC costimulation. Interestingly, EC stimulate a similar 2- to 3-fold up-regulation of AP-1, NF-AT, NF-kappaB, and NF-IL-2-luciferase reporters. CD2 mAbs completely block EC effects on all of these pathways, as well as costimulation of IL-2 secretion. We conclude that EC costimulation through CD2 does not trigger a single distinct costimulatory pathway in T cells, but rather, it amplifies several pathways downstream of the TCR. Indeed, we find that early EC costimulation acts "upstream" of the TCR by promoting lipid raft aggregation, thus amplifying TCR signaling. Soluble CD2 mAbs block EC-induced raft aggregation, whereas cross-linking CD2 promotes aggregation. These data are consistent with the critical role of CD2 in organizing the T cell-APC contact zone.