Modifiable Risk Factors for Accelerated Decline in Processing Speed: Results from Three Dutch Population Cohorts.

BACKGROUND: Several lifestyle, cardiovascular and psychosocial factors are associated with risk of cognitive decline and dementia. We studied the independent associations of a broad set of modifiable risk factors with decline in processing speed in three large population-based cohorts with up to 23 years of follow-up. METHODS: We used data of 9,666 participants from the Doetinchem Cohort Study, the Longitudinal Aging Study Amsterdam, and the Maastricht Aging Study. Decline in processing speed was measured with the letter digit substitution task or the alphabet coding task and modeled using quadratic latent growth curves. Associations of modifiable risk factors with level and rate of decline in processing speed were investigated by estimating associations with level of processing speed at different centering ages. RESULTS: Latent growth curves showed that decline in processing speed accelerated with age. Smoking, not drinking alcohol and depressive symptoms were associated with a lower level of processing speed in all cohorts. In two of the cohorts, more physical activity, drinking more than two glasses of alcohol per day, higher BMI and diabetes were associated with a lower level of processing speed. Depressive symptoms and diabetes were also associated with faster decline in processing speed. CONCLUSION: Several modifiable risk factors are associated with the level of processing speed in older age, while few are also related to the rate of decline.

Barriers to and facilitators of sports participation for people with physical disabilities: a systematic review.

Most people with physical disabilities do not participate in sports regularly, which could increase the chances of developing secondary health conditions. Therefore, knowledge about barriers to and facilitators of sports participation is needed. Barriers and facilitators for people with physical disabilities other than amputation or spinal cord injuries (SCI) are unknown. The aim of this study was to provide an overview of the literature focusing on barriers to and facilitators of sports participation for all people with various physical disabilities. Four databases were searched using MeSH terms and free texts up to April 2012. The inclusion criteria were articles focusing on people with physical disabilities, sports and barriers and/or facilitators. The exclusion criteria were articles solely focusing on people with cognitive disabilities, sensory impairments or disabilities related to a recent organ transplant or similar condition. Fifty-two articles were included in this review, with 27 focusing on people with SCI. Personal barriers were disability and health; environmental barriers were lack of facilities, transport and difficulties with accessibility. Personal facilitators were fun and health, and the environmental facilitator was social contacts. Experiencing barriers to and facilitators of sports participation depends on age and type of disability and should be considered when advising people about sports. The extent of sports participation for people with physical disabilities also increases with the selection of the most appropriate sport.

Barriers and facilitators of sports in Dutch Paralympic athletes: An explorative study.

The purpose of this study was to gain insight in barriers and facilitators of sports in paralympic athletes. An online questionnaire was distributed through the Netherlands Olympic Committee and National Sports Confederation to determine personal and environmental barriers and facilitators of sports participation. The International Classification of Functioning, Disability and Health model and theory of planned behavior were used to respectively categorize the results in environmental and personal factors, and attitude, subjective norm and perceived behavioral control. Seventy-six Dutch Paralympic athletes completed the questionnaire (51% response rate). Barriers and facilitators experienced by ambulant and wheelchair athletes were compared. Most frequently mentioned personal barrier was dependency of others (22%), while most frequently mentioned environmental barrier was lack of sports facilities (30%). Wheelchair athletes mentioned more barriers (median = 3, interquartile range: 0.5-6), than ambulant athletes (median = 1.0,interquartile range:0.0-3.0, P = 0.023). One-third of the athletes did not experience any barriers. Most frequently mentioned personal facilitators to initiate sports participation were fun (78%), health (61%), and competition (53%). Most frequently mentioned environmental facilitator was social support (40%). This study indicated that barriers of sport were mostly environmental, while facilitators were usually personal factors. Attitude and subjective norm were considered the most important components for intention to participation in sports. The facilitators outweighed the barriers and kept the athletes being active in sports.

Effect of iron on polymorphonuclear granulocyte phagocytic capacity: role of oxidation state and effect of ascorbic acid.

It has been shown that iron (III) impairs the function of polymorphonuclear granulocytes (PMN). We have studied the effect of iron (II), on the membrane function of PMN, by assessing the uptake of radiolabelled Staphylococcus aureus by these cells. Iron (II), significantly impaired PMN phagocytic function. Addition of ascorbic acid reduced uptake further. Ferrous ascorbate, molar ratio 1:20, impaired phagocytic capacity of PMN significantly at iron concentrations as low as 1-10 microM. The toxic effect of iron (II) was not observed when desferrioxamine or transferrin was present in the incubation medium. The oxygen-free radical scavengers thiourea, mannitol and catalase prevented toxicity mediated by ferrous ammoniumsulphate but not by ferrous ascorbate (molar ratio of 1:20). Although high concentrations of ascorbic acid inhibited the generation of .OH and also the formation of the DMPO-.OH adduct by zymosan stimulated PMN, toxicity of iron increased. Iron (II) impaired the uptake of S. aureus by PMN of a patient with chronic granulomatous disease while iron (III) did not. Iron mediated impairment of PMN function is not only a result of the generation of toxic oxygen metabolites but also of direct interaction of iron (II) or an iron (II)-oxygen intermediate with molecules of the cell membrane.

Polynuclear iron complexes impair the function of polymorphonuclear granulocytes.

In a previous study we showed that the phagocytic function of non-stimulated PMN was impaired after incubation with high concentrations (200 microM) of polynuclear Fe(III), probably as a result of continuous generation of small amounts of superoxide and subsequent formation of hydroxyl radicals (Van Asbeck et al, 1984b). Because polynuclear Fe(III) complexes may not be available for biological reactions we have studied the effects of polynuclear and mononuclear iron(III) on the PMN. Fe(III) in its polynuclear form (Fe:citrate 1:1) was deleterious for the phagocytic function of PMN, while the mononuclear form (Fe:citrate 1:20) was not toxic. Binding affinity of polynuclear Fe(III) for PMN was higher than of mononuclear Fe(III), and a considerable amount of bound Fe(III) was found in the cytosolic fraction of non-stimulated PMN. Limit dilution analysis of polynuclear complexes revealed that concentrations as low as 25 microM Fe(III) significantly impaired phagocytic function. The molecular weight of these complexes is similar to that of the non-transferrin plasma iron found in the serum of patients with iron overload. The toxic effects of small polynuclear non-transferrin plasma Fe(III) complexes on PMN function may contribute to the development of infections in patients with iron overload.

Bactericidal, bacteriolytic and opsonic activity of human serum against Escherichia coli.

The effect of human serum on Escherichia coli was studied with serum-sensitive and serum-resistant strains. The bactericidal effect of human serum on serum-sensitive strains of E. coli depended on the activation of the classical complement pathway. The role of activation of the alternative pathway was less important. After incubation in sub-bactericidal concentrations of serum these strains were also easily phagocytosed by polymorphonuclear leukocytes (PMNL). Strains of E. coli of certain O-types required not only an intact classical pathway but also the presence of specific antibodies for effective killing by serum and effective phagocytosis by PMNL, despite rapid activation of complement and rapid deposition of C3 on the bacterial surface in the absence of antibody. Capsulate strains O1K1 and O78K80 resisted the bactericidal effect of serum even in the presence of specific antibodies; phagocytosis by PMNL only occurred after opsonisation with specific antibodies.

Synergy between the iron chelator deferoxamine and the antimicrobial agents gentamicin, chloramphenicol, cefalothin, cefotiam and cefsulodin.

Synergy between the iron chelator deferoxamine in the presence or absence of ascorbic acid and gentamicin, chloramphenicol, cephalothin, cefotiam or cefsulodin, used against Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, Klebsiella pneumoniae, proteus mirabilis and species of Salmonella, Enterobacter, Pseudomonas and Providencia, was determined by measuring the effect of the drugs and combination of drugs on growth of the bacteria in an automated turbidimeter. The combination of drugs was considered to be synergistic when the growth inhibiting effect of the combination was greater than that of the combined action of each of the drugs separately. Deferoxamine plus ascorbic acid together with either gentamicin or cefsulodin showed synergy in 10 out of 10, and 5 out of 6 cultures respectively, whereas deferoxamine plus ascorbic acid with chloramphenicol, cephalothin or cefotiam was synergistic in 6 out of 14, 5 out of 11, and 3 out of 6 cultures. This synergistic effect was much lower when microorganisms were incubated with deferoxamine combined with the various antibiotics but without ascorbic acid. Ascorbic acid alone had no synergistic effect. When deferoxamine was saturated with iron, its antibacterial effect was completely abolished.