Ion and water transport in cells and tissues, chiefly of plants

CONTENTS Dainty, J.and Krnjević, K. (1955). The Rate of Exchange of ²⁴Na in Cat Nerves. J. Physiol. 128, 489. || MacRobbie, E.A.C. and Dainty, J. (1958). Sodium and Potassium Distribution and Transport in the seaweed Rhodymenia palmata (L.) Grey. Physiologia Plantarum 11, 782. || MacRobbie, E.A.C. and Dainty, J. (1958). Ion Transport in Nitellopsis obtusa. J. Gen. Physiol. Ag, 335. || Dainty, J. and Hope, A.B. (1959) . The Water Permeability of Cells of Chara Australis. Aust. J. Biol. Sci. (in press). || Dainty, J. and Hope, A.B. (1959). Ionic Relations of Cells of Chara australis. I. Ion Exchange in the Cell Wall. Aust. J. Biol. Sci. (in press). || Dainty, J. (1959). Notes on Water Permeability. (unpublished). || Dainty, J. (1959). Notes on Free Space (chiefly Donnan Free Space) in Plant Tissues. (unpublished). || Verma, R.D., Dainty, J. and Simpson, K. (1959). Studies on the Uptake of Phosphorus from 32P- labelled Superphosphate by Crops. I. Oats. J. Sci. Food and Agriculture 10, 100. || Verna, R.U., Dainty, J. and Simpson, K. (1959). Studies on the Uptake of Phosphorus from 32p- labelled Superphosphate by Crops. II. Potatoes. J. Sci. Food and Agriculture 10, 108. || Simpson, K., Verma, R.D. and Dainty, J. (1959). The Effect of Rate of Application of Superphosphate on the Growth and Yield of Potatoes. J. Sci. Food and Agriculture 20 (in press)

Ion channels in vacuoles from halophytes and glycophytes

AbstractThe electrical properties of the vacuolar membrane (tonoplast) of a halophyte, sugar beet, and a glycophyte, tomato, have been investigated using the patch-clamp technique [(1981) Pflügers Arch. 391, 85–100]. Voltage-dependent ion channels were analyzed using isolated membrane patches. Both species displayed channel activities which were nonselective between sodium and potassium. Beet tonoplast channels displayed inward rectification (65 pS and 10 pS for negative and positive potentials, respectively), while tomato tonoplast channels showed a constant conductance (25 pS) in the range −80 to +80 mV potentials. The observed low channel conductance at positive potentials in halophytes would prevent a significant loss of the Na+ accumulated in the vacuole through the operation of the Na+/H+ antiport [(1987) Physiol. Plant. 69, 731–734], while channel rectification in glycophytes would have no physiological significance

Trajectory of social isolation following hip fracture: an analysis of the English Longitudinal Study of Ageing (ELSA) cohort

Background: social isolation is defined as a lack of meaningful and sustained communication or interactions with social networks. There is limited understanding on the prevalence of social isolation and loneliness in people following hip fracture and no previous understanding of how this changes over time. Objective: to determine the prevalence and trajectory of social isolation and loneliness before a hip fracture, during the recovery phase and a minimum of 2 years post-hip fracture in an English population. Methods: data were from the English Longitudinal Study of Ageing (ELSA) cohort (2004/5–2014/15). The sample comprised of 215 participants who had sustained a hip fracture. Measures of social isolation and loneliness were analysed through multilevel modelling to determine their trajectories during three-time intervals (pre-fracture; interval at hip fracture and recovery; minimum 2 years post-fracture). The prevalence of social isolation and loneliness were determined pre- and post-fracture. Results: prevalence of social isolation was 19% post-hip fracture and loneliness 13% post-hip fracture. There was no statistically significant change in social isolation pre-fracture compared to a minimum of 2 years post-fracture (P = 0.78). Similarly, there was no statistically significant change in loneliness pre-fracture compared to a minimum of 2 years post-fracture (P = 0.12). Conclusion: this analysis has determined that whilst social isolation and loneliness do not change over time following hip fracture, these remain a significant problem for this population. Interventions are required to address these physical and psychological health needs. This is important as they may have short and longer term health benefits for people post-hip fracture

Changes in social isolation and loneliness following total hip and knee arthroplasty: longitudinal analysis of the English Longitudinal Study of Ageing (ELSA) cohort

Objective: To determine the prevalence and change in social isolation and loneliness in people before and after THA and TKA in England. Design: The English Longitudinal Study of Ageing dataset, a prospective study of community-dwelling older adults, was used to identify people who had undergone primary THA or TKA because of osteoarthritis. Social isolation was assessed using the ELSA Social Isolation Index. Loneliness was evaluated using the Revised University of California, Los Angeles (UCLA) Loneliness Scale. The prevalence of social isolation and loneliness were calculated and multilevel modelling was performed to assess the potential change of these measures before arthroplasty, within a two-year operative-recovery phase and a following two-year follow-up. Results: The sample consisted of 393 people following THA and TKA. The prevalence of social isolation and loneliness changed from 16.9% and 18.8% pre-operative to 21.8% and 18.9% at the final post-operative follow-up respectively. This was not a statistically significant change for either measure (p=0.15; p=0.74). There was a significant difference in social isolation at the recovery phase compared to the pre-operative phase (p=0.01), where people following arthroplasty reported an increase in social isolation (16.9% to 21.4%). There was no significant difference between the assessment phases in respect to UCLA Loneliness Scale score (p≥0.74). Conclusions: Given the negative physical and psychological consequences which social isolation and loneliness can have on individuals following THA or TKA, clinicians should be mindful of this health challenge for this population. The reported prevalence of social isolation and loneliness suggests this is an important issue

Trajectory of physical activity following total hip and knee arthroplasty: data from the English Longitudinal Study of Ageing (ELSA) cohort

Purpose: To determine the prevalence and trajectory of physical activity levels in people before and after total hip (THA) and total knee arthroplasty (TKA).  Materials and Methods: An analysis of the English Longitudinal Study of Ageing (ELSA) (2004/5 to 2014/15) cohort study, a prospective study of community-dwelling older adults. 201 people who received a THA or TKA for the management of osteoarthritis were identified. Physical activity was assessed through the frequency of engagement in sedentary, mild, moderate and high physical activity levels pre-operatively, during the recovery phase and a minimum of two years’ post-operatively.  Results: There was a statistically significant decrease in physical activity from the pre-arthroplasty phase to the operative-recovery phase (p<0.01), and a significant increase in physical activity from the operative-recovery phase to final follow-up (p=0.05). However, overall there was no significant change in physical activity from pre-operatively to final follow-up where prevalence altered from 8% (95% Confidence Intervals (CI): 5% to 12%) to 13% (95% CI: 9% to 18%)(p=0.15). Increasing age, male gender and greater depressive symptoms were explanatory variables associated with physical inactivity (p<0.02).  Conclusion: Physical activity does not increase following THA or TKA. A proportion of the arthroplasty population remain physically inactive

Trajectory of physical activity after hip fracture: An analysis of community-dwelling individuals from the English Longitudinal Study of Ageing

Introduction: To analyse physical activity participation in a community-dwelling people in England with hip fracture the interval prior to fracture, in the fracture recovery period, and a minimum of two years post-fracture. Materials and methods: 215 individuals were identified from the English Longitudinal Study of Ageing cohort (2002–2014) who sustained a hip fracture following a fall and for whom data were available on physical activity participation relating to the period pre-fracture, within-fracture recovery phase and post-fracture (minimum of two years). Physical activity was assessed using the validated ELSA physical activity questionnaire. Prevalence of ‘low’ physical activity participation was calculated and multi-level modelling analyses were performed to explore physical activity trajectories over the follow-up phase, and whether age, depression, gender and frailty were associated with physical activity participation. Results: Prevalence of low physical activity participation within two years prior to hip fracture was 16.7% (95% Confidence Intervals (CI): 11.6% to 21.8%). This increased at the final follow-up phase to 21.3% (95% CI: 15.1% to 27.6%). This was not a statistically significant change (P = 0.100). Age (P = 0.005) and frailty (P < 0.001) were statistically significant explanatory variables (P = 0.005) where older age and greater frailty equated to lower physical activity participation. Neither gender (P = 0.288) nor depression (P = 0.121) were significant explanatory variables. Conclusion: Physical activity levels do not significantly change between pre-fracture to a minimum of two years post-hip fracture for community-dwelling individuals. This contrasts with previous reports of reduced mobility post-hip fracture, suggesting that ‘physical activity’ and ‘mobility’ should be considered as separate outcomes in this population

Association between musculoskeletal pain with social isolation and loneliness: analysis of the English Longitudinal Study of Ageing

Introduction: Musculoskeletal pain is a prevalent health challenge for all age groups worldwide, but most notably in older adults. Social isolation is the consequence of a decrease in social network size with a reduction in the number of social contacts. Loneliness is the psychological embodiment of social isolation and represents an individual’s perception of dissatisfaction in the quality or quantity of their social contacts. This study aims to determine whether a relationship exists between musculoskeletal pain and social isolation and loneliness. Methods: A cross-sectional analysis of the English Longitudinal Study of Ageing (ELSA) cohort was undertaken. ELSA is a nationally representative sample of the non-institutionalised population of individuals aged 50 years and over based in England. Data were gathered on social isolation through the ELSA Social Isolation Index, loneliness through the University of California, Los Angeles (UCLA) Loneliness Scale and musculoskeletal pain. Data for covariates included physical activity, depression score, socioeconomic status, access to transport and demographic characteristics. Logistic regression analyses were undertaken to determine the relationship between social isolation and loneliness with pain and the additional covariates. Results: A total of 9299 participants were included in the analysis. This included 4125 (44.4%) males, with a mean age of 65.8 years. There was a significant association where social isolation was lower for those in pain (odd ratio (OR): 0.87; 95% confidence intervals (CI): 0.75 to 0.99), whereas the converse occurred for loneliness where this was higher for those in pain (OR: 1.15; 95% CI: 1.01 to 1.31). Age, occupation, physical activity and depression were all associated with increased social isolation and loneliness. Conclusion: People who experience chronic musculoskeletal pain are at greater risk of being lonely, but at less risk of being socially isolated. Health professionals should consider the wider implications of musculoskeletal pain on individuals, to reduce the risk of negative health implications associated with loneliness from impacting on individual’s health and well-being

Modeling tool for calculating dietary iron bioavailability in iron-sufficient adults

Background: Values for dietary iron bioavailability are required for setting dietary reference values. These are estimated from predictive algorithms, nonheme iron absorption from meals, and models of iron intake, serum ferritin concentration, and iron requirements. Objective: We developed a new interactive tool to predict dietary iron bioavailability. Design: Iron intake and serum ferritin, a quantitative marker of body iron stores, from 2 nationally representative studies of adults in the United Kingdom and Ireland and a trial in elderly people in Norfolk, United Kingdom, were used to develop a model to predict dietary iron absorption at different serum ferritin concentrations. Individuals who had raised inflammatory markers or were taking iron-containing supplements were excluded. Results: Mean iron intakes were 13.6, 10.3, and 10.9 mg/d and mean serum ferritin concentrations were 140.7, 49.4, and 96.7 mg/L in men, premenopausal women, and postmenopausal women, respectively. The model predicted that at serum ferritin concentrations of 15, 30, and 60 mg/L, mean dietary iron absorption would be 22.3%, 16.3%, and 11.6%, respectively, in men; 27.2%, 17.2%, and 10.6%, respectively, in premenopausal women; and 18.4%, 12.7%, and 10.5%, respectively, in postmenopausal women. Conclusions: An interactive program for calculating dietary iron absorption at any concentration of serum ferritin is presented. Differences in iron status are partly explained by age but also by diet, with meat being a key determinant. The effect of the diet is more marked at lower serum ferritin concentrations. The model can be applied to any adult population in whom representative, good-quality data on iron intake and iron status have been collected. Values for dietary iron bioavailability can be derived for any target concentration of serum ferritin, thereby giving risk managers and public health professionals a flexible and transparent basis on which to base their dietary recommendations. This trial was registered at clinicaltrials.gov as NCT01754012