Pathways of urea transport in the mammalian kidney

Urea is the chief end product of nitrogen metabolism in mammals. Most of the urea produced is excreted by the kidneys. Excretion of a large fraction of the urea filtered by the glomerulus is required to keep pace with the rate of hepatic urea production. Consequently, the maintenance of nitrogen balance depends on a sustained high rate of renal urea excretion. One factor that might challenge the ability of the kidney to maintain a high rate of urea excretion is the need to limit water excretion. Theoretically, an increase in water absorption along the nephron would be expected to increase luminal urea concentration and consequently increase the driving force for passive urea reabsorption. Indeed, as demonstrated originally by Shannon [1] and confirmed in many subsequent studies, the rate of urea excretion decreases when water excretion decreases. However, the decline in urea excretion is relatively modest, even when the rate of water excretion is very low. In Shannon's studies in dogs [1], when water diuresis was established (water excretion 5–10 percent of filtered load), urea excretion was about 60 percent of the filtered load. During antidiuresis, when water excretion was reduced by 95% or more (to less than 0.5 percent of the glomerular filtration rate), urea excretion fell only by 25 to 30% (to 40 to 45 percent of the filtered load)

Regional and total body bioelectrical impedance analysis compared with DXA in Icelandic elderly.

To access publisher full text version of this article. Please click on the hyperlink in Additional Links field.BACKGROUND/OBJECTIVES: The aims were (1) to compare fat free mass (FFM) estimates from regional hand-held bioelectrical impedance analysis (HHBIA) with conventional BIA (CBIA) and dual energy X-ray absorptiometry (DXA) and (2) to develop a population specific equation for FFM prediction in Icelandic elderly. SUBJECTS/METHODS: DXA, CBIA and HHBIA data were available for 98 free-living Icelandic elderly (age=73.0 ± 5.6 years, body mass index=28.8 ± 5.2 kg/m(2)). Participants were randomized into a development block (n=50) and validation block (n=48). A population specific equation for FFM prediction was calculated using CBIA-derived resistance and anthropometric data from the development block and then compared with other BIA equations (Deurenberg, Segal, company-specific equations) and DXA estimates using the validation block. RESULTS: The correlations between BIA methods and DXA were very high, that is, >0.9; however, mean differences compared with DXA were quite variable, ranging from -5.0 (Deurenberg) to +2.5 (Segal, HHBIA) and +3.3 kg (CBIA). Mean difference of the population-specific equation was below 0.1 kg. The standard deviations of the differences ranged from 2.6 to 3.3 kg. The limits of agreement of the BIA methods were similar and between 9.9 and 12.9 kg. CONCLUSIONS: In Icelandic elderly, HHBIA and CBIA produce similar FFM estimates when using company-specific prediction equations. CBIA provides the additional possibility to use a population-specific prediction equation, which yields best results. However, limits of agreement were wide and similar of all employed BIA methods, which indicates principal limitations of BIA analysis in the determination of FFM.Icelandic Technology Development Fund 071323008 The University of Iceland Helga Jonsdottir and Sigurlidi Kristjansson Geriatric Research Fun

Effects of weight loss and seafood consumption on inflammation parameters in young, overweight and obese European men and women during 8 weeks of energy restriction

To access publisher full text version of this article. Please click on the hyperlink in Additional Links fieldBackground/Objectives:In vitro studies have shown that long-chain n-3 polyunsaturated fatty acids (LC n-3 PUFAs) can affect inflammation; however, results from intervention studies in overweight or obese individuals are contradicting. The aim of this study was to investigate the effects of weight loss and seafood consumption on inflammation parameters during energy restriction.Subjects/Methods:In this 8-week intervention trial, 324 subjects (aged 20-40 years, body mass index 27.5-32.5 kg/m(2) from Iceland, Spain and Ireland) were randomized to one of four energy-restricted diets (-30% relative to estimated requirements): salmon (3 x 150 g/week, 2.1 g LC n-3 PUFA per day); cod (3 x 150 g/week, 0.3 g LC n-3 PUFA per day); fish oil capsules (1.3 g LC n-3 PUFA per day); and control (sunflower oil capsules, no seafood). Body weight, high-sensitivity C-reactive protein (CRP), interleukin-6 (IL-6), glutathione reductase and prostaglandin F2 alpha (PGEF2alpha) were measured at baseline and end point.Results:Subjects experienced weight loss (-5.2+/-3.2 kg, P<0.001). Taken together for all subjects, there were significant decreases in all inflammation parameters. On a group level, salmon consumption was most effective, three of the four inflammation parameters decreased in the salmon group (high-sensitivity CRP=-32.0%; IL-6=-18.4%; PGEF2alpha=-18.5%; all P<0.05). Cod consumption decreased high-sensitivity CRP and IL-6 (-21.5 and -10.8%, respectively, both P<0.05). Changes in the other two groups were not significant, which can be partly explained by the large s.d.Conclusions:The mean concentrations of inflammation parameters decreased during a period of weight loss and dietary intervention. In our study, salmon consumption was most effective, three of the four measured inflammation parameters decreased significantly in the salmon group

Visualising apoptosis in live zebrafish using fluorescence lifetime imaging with optical projection tomography to map FRET biosensor activity in space and time

Fluorescence lifetime imaging (FLIM) combined with optical projection tomography (OPT) has the potential to map Förster resonant energy transfer (FRET) readouts in space and time in intact transparent or near transparent live organisms such as zebrafish larvae, thereby providing a means to visualise cell signalling processes in their physiological context. Here the first application of FLIM OPT to read out biological function in live transgenic zebrafish larvae using a genetically expressed FRET biosensor is reported. Apoptosis, or programmed cell death, is mapped in 3-D by imaging the activity of a FRET biosensor that is cleaved by Caspase 3, which is a key effector of apoptosis. Although apoptosis is a naturally occurring process during development, it can also be triggered in a variety of ways, including through gamma irradiation. FLIM OPT is shown here to enable apoptosis to be monitored over time, in live zebrafish larvae via changes in Caspase 3 activation following gamma irradiation at 24 hours post fertilisation. Significant apoptosis was observed at 3.5 hours post irradiation, predominantly in the head region

Attention and Emotion Influence the Relationship Between Extraversion and Neural Response

Extraversion has been shown to positively correlate with activation within the ventral striatum, amygdala and other dopaminergically innervated, reward-sensitive regions. These regions are implicated in emotional responding, in a manner sensitive to attentional focus. However, no study has investigated the interaction among extraversion, emotion and attention. We used fMRI and dynamic, evocative film clips to elicit amusement and sadness in a sample of 28 women. Participants were instructed either to respond naturally (n = 14) or to attend to and continuously rate their emotions (n = 14) while watching the films. Contrary to expectations, striatal response was negatively associated with extraversion during amusement, regardless of attention. A negative association was also observed during sad films, but only when attending to emotion. These findings suggest that attentional focus does not influence the relationship between extraversion and neural response to positive (amusing) stimuli but does impact the response to negative (sad) stimuli

The sarcopenia and physical frailty in older people : multi-component treatment strategies (SPRINTT) project: description and feasibility of a nutrition intervention in community-dwelling older Europeans

Background The "Sarcopenia and Physical Frailty in Older People: Multicomponent Treatment Strategies" (SPRINTT) project sponsored a multi-center randomized controlled trial (RCT) with the objective to determine the effect of physical activity and nutrition intervention for prevention of mobility disability in community-dwelling frail older Europeans. We describe here the design and feasibility of the SPRINTT nutrition intervention, including techniques used by nutrition interventionists to identify those at risk of malnutrition and to carry out the nutrition intervention. Methods SPRINTT RCT recruited older adults (>= 70 years) from 11 European countries. Eligible participants (n = 1517) had functional limitations measured with Short Physical Performance Battery (SPPB score 3-9) and low muscle mass as determined by DXA scans, but were able to walk 400 m without assistance within 15 min. Participants were followed up for up to 3 years. The nutrition intervention was carried out mainly by individual nutrition counseling. Nutrition goals included achieving a daily protein intake of 1.0-1.2 g/kg body weight, energy intake of 25-30 kcal/kg of body weight/day, and serum vitamin D concentration >= 75 mmol/L. Survey on the method strategies and feasibility of the nutrition intervention was sent to all nutrition interventionists of the 16 SPRINTT study sites. Results Nutrition interventionists from all study sites responded to the survey. All responders found that the SPRINTT nutrition intervention was feasible for the target population, and it was well received by the majority. The identification of participants at nutritional risk was accomplished by combining information from interviews, questionnaires, clinical and laboratory data. Although the nutrition intervention was mainly carried out using individual nutritional counselling, other assisting methods were used as appropriate. Conclusion The SPRINTT nutrition intervention was feasible and able to adapt flexibly to varying needs of this heterogeneous population. The procedures adopted to identify older adults at risk of malnutrition and to design the appropriate intervention may serve as a model to deliver nutrition intervention for community-dwelling older people with mobility limitations. Aim To describe the methods and feasibility of the nutritional intervention carried out within the SPRINTT Randomized cotrolled trial. We also illustrate how nutrition interventionists identified participants at risk of malnutrition and the lessons learnt from the nutrition intervention. Findings SPRINTT nutrition intervention was well-received by the majority of the participants. It was mainly carried out using tailored nutrition counselling, but also other means of delivering the intervention were successfully used. Compared with a standard nutrition prescription, an individualized protocol to diagnose malnutrition and follow-up by tailored nutrition counselling helped achieve nutritional targets more effectively in spite of diversity of population in nutritional habits and in some cases reluctance to accept changes. Message The SPRINTT nutrition intervention was feasible and allowed flexibility to the varying needs and cultural differences of this heterogeneous population of frail, older Europeans. It may serve as a model to educate and improve nutrition among community-dwelling older people at risk of mobility limitations.Peer reviewe

Topology Learning and Place Recognition using Bayesian Programming for Mobile Robot Navigation

This paper proposes an approach allowing topology learning and recognition in indoor environments by using a probabilistic approach called Bayesian Programming. The main goal of this approach is to cope with the uncertainty, imprecision and incompleteness of handled information. The Bayesian Program for topology recognition and door detection is presented. The method has been successfully tested in indoor environments with the BIBA robot, a fully autonomous robot. The experiments address both the topology learning and topology recognition capabilities of the approach

ASSOCIATION BETWEEN GRIP STRENGTH AND COGNITIVE FUNCTION AMONG COMMUNITY-DWELLING OLDER ADULTS.

GSA 2019 Annual Scientific MeetingPeer reviewe

Voice Enabled Interface for Interactive Tour Guide Robots

This paper considers design methodologies in order to develop voice-enabled interfaces for tour-guide robots to be deployed at the Robotics Exposition of the Swiss National Exhibition (Expo.02). Human-robot voice communication presents new challenges for design of fully autonomous mobile robots, in that interactivity must be robot-initiated in conversation and within a dynamic adverse environment. We approached these general problems for a voice enabled interface, tailored to limited computational resources of one on-board processor, when integrating smart speech signal acquisition, automatic speech recognition and synthesis, as well as dialogue system into the multi-modal, multi-sensor interface for the expo tour-guide robot. We also focus on particular issues that need to be addressed in voice-based interaction when planning specific tasks and research experiments for Expo.02 where tour-guide robots will interact with hundred of thousands of visitors during six months, seven days a week, ten hours per day

Relationship Between Physical Activity and Function With Quality of Life in Community-Living Older Adults

Background: Quality of life (QOL) is a multidimensional concept which is often used as an evaluation of a person‘s health and psychological status. Increasing longevity can be associated with better QOL as long as older adults are independent in daily life. The aim of the study was to examine the associations of QOL with muscle strength and physical function among community-dwelling older adults. Methods: The current cross-sectional study had 225 participants (73.7±5.7yrs, 58.2% female) living in Reykjavik, Iceland. QOL measured using the 36-item short-form survey (SF-36). Covariates were anthropometrics, muscle strength, physical function including timed up and go test (TUG), and 6-minute walking distance (6MWD), physical activity per week (PA). Linear regression analysis was used to examine the association of QOL with physical function. Results: The mean QOL score for the study population was 54.9±6.13. The analysis was adjusted for age and gender, body mass index, height, and PA. We found that QOL was associated with better grip strength (B=1.4, PPeer reviewe