Joint associations of accelero-meter measured physical activity and sedentary time with all-cause mortality: a harmonised meta-analysis in more than 44 000 middle-aged and older individuals

OBJECTIVES

To examine the joint associations of accelerometer-measured physical activity and sedentary time with all-cause mortality.

METHODS

We conducted a harmonised meta-analysis including nine prospective cohort studies from four countries. 44 370 men and women were followed for 4.0 to 14.5 years during which 3451 participants died (7.8% mortality rate). Associations between different combinations of moderate-to-vigorous intensity physical activity (MVPA) and sedentary time were analysed at study level using Cox proportional hazards regression analysis and summarised using random effects meta-analysis.

RESULTS

Across cohorts, the average time spent sedentary ranged from 8.5 hours/day to 10.5 hours/day and 8 min/day to 35 min/day for MVPA. Compared with the referent group (highest physical activity/lowest sedentary time), the risk of death increased with lower levels of MVPA and greater amounts of sedentary time. Among those in the highest third of MVPA, the risk of death was not statistically different from the referent for those in the middle (16%; 95% CI 0.87% to 1.54%) and highest (40%; 95% CI 0.87% to 2.26%) thirds of sedentary time. Those in the lowest third of MVPA had a greater risk of death in all combinations with sedentary time; 65% (95% CI 1.25% to 2.19%), 65% (95% CI 1.24% to 2.21%) and 263% (95% CI 1.93% to 3.57%), respectively.

CONCLUSION

Higher sedentary time is associated with higher mortality in less active individuals when measured by accelerometry. About 30-40 min of MVPA per day attenuate the association between sedentary time and risk of death, which is lower than previous estimates from self-reported data.

CD40 signaling replaces CD4+ lymphocytes and its blocking prevents chronic rejection of heart transplants

Chronic rejection remains the major obstacle to long term survival in heart transplant recipients. The cellular and molecular mechanisms that underlie chronic rejection are not known, and their discovery can form the basis of clinical intervention. Several investigators have suggested that the development of chronic rejection in solid organ transplants is dependent on help mediated by CD4(+) lymphocytes. Importantly, the mechanism through which help is provided has not been fully delineated in transplant rejection. Using a murine heterotopic heart transplant model without immunosuppression, this study defines the functional role of CD4(+) lymphocytes in chronic rejection. In an MHC class II-mismatched model, we demonstrate that chronic rejection was absolutely contingent on the presence of CD4(+) lymphocytes. Importantly, here we report that signaling through CD40 can replace the requirement of CD4(+) lymphocytes, demonstrated by the development of chronic rejection in CD4 knockout recipients treated with a CD40-activating mAb (FGK45). The return of rejection appears to be a CD8(+) lymphocyte-dependent process, noted by the absence of rejection in FGK45-treated recombinase-activated gene knockout (CD4(+) and CD8(+) lymphocyte-deficient) recipients. The CD40 signaling pathway works independently of B7-CD28 costimulation, as indicated by the development of severe chronic rejection in CD28 knockout recipients. Importantly, this study provides evidence that CD40 ligand-targeted therapies may prevent chronic rejection only in strain combinations where CD4(+) lymphocyte help is absolutely required.

Genetic analysis of deciduous tooth size in Australian twins

Investigations of permanent dental crown size in twins and family groups indicate a high degree of transmissible control, but little is known about the relative contributions of genetic and environmental factors to variation in size of the deciduous (primary) teeth. Here, maximum mesiodistal and buccolingual crown dimensions of maxillary and mandibular primary teeth were measured from dental models of 602 individuals, including 99 monozygous (MZ) twin pairs, 81 dizygous (DZ) same-sex pairs, 41 DZ opposite-sex pairs, and 160 singletons. Data were subjected to univariate genetic analysis with the structural-equation-modelling package, Mx using the normal assumptions of the twin model. A model incorporating additive genetic (A) and unique environmental (E) variation was found to be the most parsimonious for all tooth-size variables. Estimates of heritability for deciduous crown size ranged from 0.62 to 0.91. This study shows that variation in deciduous crown size has a strong genetic component, similar to that observed in the permanent dentition. Further studies are required to determine whether the underlying genetic mechanisms are the same for both deciduous and permanent teeth.

Human granulocyte-macrophage colony-stimulating factor (hGM-CSF): identification of a binding site for a neutralizing antibody

One approach to the localization of functionally active regions of human granulocyte-macrophage colony-stimulating factor (hGM-CSF) is to map the epitopes recognized by neutralizing anti-hGM-CSF monoclonal antibodies. We have defined the epitope recognized by one neutralizing antibody (LMM102) using proteolytic fragments obtained by enzymic digestion of bacterially synthesized hGM-CSF. RP-HPLC fractionation of a tryptic digest resulted in the identification of an immunoreactive "tryptic core" peptide containing 66 amino acids (52% of the protein). Further digestion of this "tryptic core" with S. aureus V8 protease produced a unique immunoreactive hGM-CSF product comprising two peptides, residues 86-93 and 112-127, linked by a disulfide bond between residues 88 and 121. The individual peptides, generated by reduction with dithiothreitol, were not recognized by the antibody. An analog of this peptide has been synthesized chemically and shown to have similar immunoreactivity to the epitope obtained by enzymic digestion. A series of modified peptides has also been synthesized to identify further the region required for antibody recognition.

Effect of TGF-beta on differentiated organoids of the colon carcinoma cell line LIM 1863

The LIM 1863 colon carcinoma cell line grows in suspension as morphologically and functionally organized organoids in serum-containing medium. Addition of TGF-beta caused the organoids to adhere and inhibited DNA synthesis. A 20 min incubation with TGF-beta was sufficient to induce adherence and this could be inhibited by cycloheximide. The adhesion and DNA synthesis inhibition were demonstrated to be separate events. We were not able to detect any changes in matrix or cell membrane antigens. Similarly there were no changes in synthesized proteins (by two-dimensional gel electrophoresis), and no upregulation of proteoglycan. When adhered organoids were lysed from the tissue culture plastic surface, untreated organoids adhered to this surface. This 'conditioned' surface was destroyed by trypsin but not collagenase or medium from normal LIM 1863 cultures. However, the adherent phenotype was prevented when organoids were treated with transforming growth factor-beta (TGF-beta) in the presence of medium conditioned by normal LIM 1863 cultures rather than in fresh medium. The adhesion process was inhibited by an antibody (QE2E5) against beta 1 integrin although no quantitative changes in integrins were observed (by immunoprecipitation or RNA analysis). A second anti-beta 1 integrin antibody (61.2C4) inhibited LIM 1863 adhesion to collagen but not TGF-beta induced adhesion, implying that TGF-beta induced a specific conformational change or interaction of a beta 1 integrin. In this morphologically structured system TGF-beta induced a number of subtle effects including formation of new extracellular matrix and conformational change of a beta 1 integrin, rather than the major quantitative changes in cell/matrix molecules reported previously.

Psychophysical study of six hand movements

This study represents a continuation of a series of psychophysical studies on repetitive motions of the wrist and hand conducted at the Liberty Mutual Research Center for Safety and Health. The purpose of the study was to quantify maximum acceptable forces of six motions performed on separate days but within the context of the same experiment. The six motions were wrist flexion with a power grip, wrist extension with a power grip, wrist flexion with a pinch grip, wrist extension with a pinch grip, ulnar deviation with a power grip, and a handgrip task (with a power grip). A psychophysical methodology was used in which the subject adjusted the resistance on the handle and the experimenter manipulated or controlled all other variables. Thirty-one subjects performed the six tasks at repetition rates of 15, 20 and 25 motions/min. Subjects performed the tasks for 7 h per day, 5 days per week, for 4 weeks. The subjects were instructed to work as if they were on an incentive basis, getting paid for the amount of work performed. Symptoms were recorded by the subjects during the last 5 min of each hour. The results revealed that maximum acceptable torques ranged from 11 to 19% of maximum isometric torque depending on frequency and motion. Maximum acceptable torques for the tasks that could be compared with previous studies showed the same patterns of response. However, the selected forces were substantially lower using the mixed protocol. A table of maximum acceptable torques and forces is presented for application in the field.

Joint associations between objectively measured physical activity volume and intensity with body fatness: the Fenland study

BACKGROUND/OBJECTIVES

Physical activity energy expenditure (PAEE) represents the total volume of all physical activity. This can be accumulated as different underlying intensity profiles. Although volume and intensity have been studied in isolation, less is known about their joint association with health. We examined this association with body fatness in a population-based sample of middle-aged British adults.

METHODS

In total, 6148 women and 5320 men from the Fenland study with objectively measured physical activity from individually calibrated combined heart rate and movement sensing and DXA-derived body fat percentage (BF%) were included in the analyses. We used linear and compositional isocaloric substitution analysis to examine associations of PAEE and its intensity composition with body fatness. Sex-stratified models were adjusted for socio-economic and dietary covariates.

RESULTS

PAEE was inversely associated with body fatness in women (beta = -0.16 (95% CI: -0.17; -0.15) BF% per kJ day-1 kg-1) and men (beta = -0.09 (95% CI: -0.10; -0.08) BF% per kJ day-1 kg-1). Intensity composition was significantly associated with body fatness, beyond that of PAEE; the reallocation of energy to vigorous physical activity (>6 METs) from other intensities was associated with less body fatness, whereas light activity (1.5-3 METs) was positively associated. However, light activity was the main driver of overall PAEE volume, and the relative importance of intensity was marginal compared to that of volume; the difference between PAEE in tertile 1 and 2 in women was associated with 3 percentage-point lower BF%. Higher vigorous physical activity in the same group to the maximum observed value was associated with 1 percentage-point lower BF%.

CONCLUSIONS

In this large, population-based cohort study with objective measures, PAEE was inversely associated with body fatness. Beyond the PAEE association, greater levels of intense activity were also associated with lower body fatness. This contribution was marginal relative to PAEE. These findings support current guidelines for physical activity which emphasise that any movement is beneficial, rather than specific activity intensity or duration targets.

Rise and Recharge: Effects on Activity Outcomes of an e-Health Smartphone Intervention to Reduce Office Workers' Sitting Time

This feasibility study evaluated the effects of an individual-level intervention to target office workers total and prolonged sedentary behaviour during working hours, using an e-health smartphone application. A three-arm (Prompt-30 or 60 min Intervention arm and a No-Prompt Comparison arm), quasi-randomised intervention was conducted over 12 weeks. Behavioural outcomes (worktime sitting, standing, stepping, prolonged sitting, and physical activity) were monitored using accelerometers and anthropometrics measured at baseline, 6 weeks and 12 weeks. Cardiometabolic measures were taken at baseline and 12 weeks. Fifty-six office workers (64% female) completed baseline assessments. The Prompt-60 arm was associated with a reduction in occupational sitting time at 6 (-46.8 min/8 h workday [95% confidence interval = -86.4, -6.6], p < 0.05) and 12 weeks (-69.6 min/8 h workday [-111.0, -28.2], p < 0.05) relative to the No-Prompt Comparison arm. Sitting was primarily replaced with standing in both arms (p > 0.05). Both Intervention arms reduced time in prolonged sitting bouts at 12 weeks (Prompt-30: -27.0 [-99.0, 45.0]; Prompt-60: -25.8 [-98.4, 47.4] min/8 h workday; both p > 0.05). There were no changes in steps or cardiometabolic risk. Findings highlight the potential of a smartphone e-health application, suggesting 60 min prompts may present an optimal frequency to reduce total occupational sedentary behaviour.

Beliefs, values, and practices of Navajo childbearing women

The purpose of this exploratory-descriptive study is to describe the beliefs, values, and practices regarding the childbearing experience as perceived by a sample of Navajo childbearing women. The methodology is a replication of that used in previous studies by the researchers and colleagues who investigated the childbearing experience as perceived by childbearing women of five other cultures. A Navajo nurse interviewed 20 pregnant Navajo women between 16 and 38 years of age who reside on the Navajo reservation. The 35 items with which at least 12 subjects agreed are reported. The great diversity in beliefs, values, and practices reported by this sample of Navajo childbearing women is consistent with findings of the five previous studies. The results reemphasize the need for individualized culture-specific assessment of each Navajo childbearing client to provide health care that is truly sensitive to her cultural needs.

The development of a risk-based approach to managing the ecological impact of pollutants in highway runoff

In the UK, the Highways Agency is responsible for the strategic road network. It is recognised that current design guidance to control pollutants in highway runoff is out of date. A research programme is in progress to develop a better understanding of pollutants in highway runoff and their ecological impact. The paper summarises the outcome of a study to: (1) monitor pollutants in highway runoff under different climate and traffic conditions at 24 sites; (2) develop standards to assess potential ecological risks; and (3) develop a model to predict pollutant concentrations in highway runoff. Data collection and analysis of the resulting data have identified a link between pollutant concentrations and traffic density. A number of pollutants routinely present in highway runoff have been identified as posing the greatest ecological risk. Ecologically based standards for acute impacts have been derived for the soluble form of these pollutants. These standards will be used in conjunction with the model to indicate where runoff treatment may be required to mitigate ecological risk. The model and standards will be used to develop improved design guidance to protect receiving waters from pollutants in highway runoff by identifying where runoff treatment is required, and to what degree.

Prompts to increase physical activity at points-of-choice between stairs and escalators: what about escalator climbers?

Since 1980, many studies have evaluated whether stair-use prompts increased physical activity by quantifying changes in stair use. To more completely evaluate changes in physical activity, this study addressed the often-overlooked assessment of climbing up escalators by evaluating the degree to which stair-use sign prompts increased active ascent-defined as stair use or escalator climbing. Over 5 months, at an airport stairs/escalator point of choice, we video-recorded passersby (N = 13,544) who ascended either stairs or escalators, on 10 days with signs and 10 days without signs. Ascenders using the stairs, standing on the escalator, and climbing the escalator were compared on days with versus without signs using multivariable logistic regression. The percentage of ascenders on days with versus without signs were as follows: stair use, 6.9 versus 3.6 percent; escalator standing, 75.2 versus 76.0 percent; and escalator climbing, 18.5 versus 20.4 percent. Signs more than doubled the odds of stair use (vs. escalator use; OR = 2.25; 95% CI = 1.90-2.68; p < .001). Signs decreased the odds of escalator climbing (vs. escalator standing or stair use); OR = 0.90; 95% CI = 0.82-0.99; p = .028). Signs increased the odds of active ascent versus escalator standing by 15 percent (OR = 1.15; 95% CI = 1.05-1.25; p = .002). Although stair-use prompts increased stair use more than twofold (125%), they increased active ascent by only 15 percent, partly because escalator climbing-a behavior not targeted by the intervention-decreased. Although our results corroborated the established consensus that point-of-choice prompts increase stair use, future studies should test interventions designed to increase active ascent.

The development of an ecological approach to manage the pollution risk from highway runoff

In the UK, the Highways Agency is responsible for operating, maintaining and improving the strategic road network in England. One focus of the Highways Agency's ongoing research into the nature and impact of highway runoff is aimed at ensuring that the Highways Agency will meet the requirements of the EU Water Framework Directive. A research programme, undertaken in partnership with the Environment Agency, is in progress to develop a better understanding of pollutants in highway runoff and their ecological impact. The paper presents the outcome of a study to: (1) monitor pollutants in highway runoff under different climate and traffic conditions; (2) develop standards to assess potential ecological risks from soluble pollutants in highway runoff; and (3) develop a model to predict pollutant concentrations in highway runoff. The model has been embedded in a design tool incorporating risk assessment procedures and receiving water standards for soluble and insoluble pollutants--the latter has been developed elsewhere in another project within the research programme. The design tool will be used to support improved guidance on where, and to what level, treatment of runoff is required for highway designers to manage the risk of ecological impact from highway runoff.

Pharmacokinetics of human granulocyte-macrophage colony-stimulating factor using a sensitive immunoassay

A sensitive and reliable sandwich enzyme-linked immunosorbent assay (ELISA) has been developed for recombinant human granulocyte-macrophage colony-stimulating factor (hGM-CSF). The assay is quantitative between 100 pg/mL and 2.5 ng/mL for bacterially synthesized hGM-CSF in human serum and is more sensitive and specific than the semisolid agar bioassay. As part of a phase I study, the pharmacokinetics of intravenous (IV) bolus injection and subcutaneous (SC) administration of hGM-CSF were studied. Following a single IV dose, an initial high blood level of hGM-CSF occurred, followed by a rapid decrease occurring in two apparent phases with a half-life (t1/2)alpha of less than five minutes and a t1/2 beta of 150 minutes. After an SC injection, detectable serum levels occurred within 15 to 30 minutes, and serum levels were sustained for a variable time depending on the dose. At the highest SC dose (10 micrograms/kg), a serum level of greater than 1 ng/mL (65 pmol/L) was maintained for greater than 12 hours after a single injection. This corresponds to the concentration of hGM-CSF supporting near-maximum proliferation in vitro.