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Prediction of physical activity and physical work capacity (PWC150) in young adulthood from childhood and adolescence with consideration of parental measures.

The 12-year prediction of physical activity level and submaximal aerobic fitness observed during young adulthood was quantified from childhood and parental measures. The sample consisted of 153 children and adolescents of the Quebec Family Study who were evaluated at baseline and reassessed 12 years later, as young adults. Physical work capacity at a heart rate of 150 beats x min(-1) (PWC150) was measured using cycle ergometry. A 3-day activity record was used to estimate daily energy expenditure (DEE), inactive time (IA), and time spent in moderate-to-vigorous activity (MVPA). Spearman partial inter-age correlations, controlling for length of follow-up and age at baseline, indicated better tracking for PWC150 (0.24 and 0.46, males and females, respectively) than for indicators of physical activity (0.07 < or = r < or = 0.25, males; 0.06 < or = r < or = 0.22, females). Multiple regression analyses indicated that parental measurements of activity and PWC150 did not add any predictive value, with the exception of paternal DEE, which accounted for 8% of the variance in males. There is moderately high stability of submaximal work capacity and lower tracking of physical activity from childhood and adolescence into young adulthood.

Adolescent↗

Preprocessing of rotamers for protein design calculations.

We have developed a process that significantly reduces the number of rotamers in computational protein design calculations. This process, which we call Vegas, results in dramatic computational performance increases when used with algorithms based on the dead-end elimination (DEE) theorem. Vegas estimates the energy of each rotamer at each position by fixing each rotamer in turn and utilizing various search algorithms to optimize the remaining positions. Algorithms used for this context specific optimization can include Monte Carlo, self-consistent mean field, and the evaluation of an expression that generates a lower bound energy for the fixed rotamer. Rotamers with energies above a user-defined cutoff value are eliminated. We found that using Vegas to preprocess rotamers significantly reduced the calculation time of subsequent DEE-based algorithms while retaining the global minimum energy conformation. For a full boundary design of a 51 amino acid fragment of engrailed homeodomain, the total calculation time was reduced by 12-fold.

Algorithms↗

Fast and accurate side-chain topology and energy refinement (FASTER) as a new method for protein structure optimization.

We have developed an original method for global optimization of protein side-chain conformations, called the Fast and Accurate Side-Chain Topology and Energy Refinement (FASTER) method. The method operates by systematically overcoming local minima of increasing order. Comparison of the FASTER results with those of the dead-end elimination (DEE) algorithm showed that both methods produce nearly identical results, but the FASTER algorithm is 100-1000 times faster than the DEE method and scales in a stable and favorable way as a function of protein size. We also show that low-order local minima may be almost as accurate as the global minimum when evaluated against experimentally determined structures. In addition, the new algorithm provides significant information about the conformational flexibility of individual side-chains. We observed that strictly rigid side-chains are concentrated mainly in the core of the protein, whereas highly flexible side-chains are found almost exclusively among solvent-oriented residues.

Algorithms↗

A protein/peptide assay using peptide-resin adduct: application to the calmodulin/RS20 complex.

To obtain equilibrium and kinetic constants of a protein/peptide complex, we have developed a rapid procedure which uses peptides specifically linked to a resin. With this peptide-resin adduct, bound and free 125I-labeled protein could be easily separated by simple centrifugation. The feasibility of the method was demonstrated with the calmodulin/RS20 complex, where RS20 is the putative calmodulin binding peptide of the smooth muscle myosin light chain kinase (smMLCK). In addition to the wild-type calmodulin (SYNCAM) expressed in Escherichia coli, we also examined calmodulin mutants with charge reversals called SYNCAM12A (DEE 118-120-->KKK) and SYNCAM18A (EEE 82-84-->KKK and DEE 118-120-->KKK). The kinetic analysis of the interaction between SYNCAM and RS20 associated with titration experiments allowed us to measure dissociation constants (KD) in the range of 10(-9) M, in good agreement with previously published data. Moreover, the binding assays showed that SYN-CAM18A did not interact with RS20, whereas SYN-CAM12A did with a KD around 10(-8) M. The lack of binding of SYNCAM18A to RS20 provides an explanation for the lack of smMLCK activation by SYNCAM18A. Altogether, these results demonstrate that peptide-resin can be used as a tool for separating bound from free protein, thus enabling a rapid and reliable quantification of the protein/peptide interaction.

Amino Acid Sequence↗

Generalized dead-end elimination algorithms make large-scale protein side-chain structure prediction tractable: implications for protein design and structural genomics.

The dead-end elimination (DEE) theorems are powerful tools for the combinatorial optimization of protein side-chain placement in protein design and homology modeling. In order to reach their full potential, the theorems must be extended to handle very hard problems. We present a suite of new algorithms within the DEE paradigm that significantly extend its range of convergence and reduce run time. As a demonstration, we show that a total protein design problem of 10(115) combinations, a hydrophobic core design problem of 10(244) combinations, and a side-chain placement problem of 10(1044) combinations are solved in less than two weeks, a day and a half, and an hour of CPU time, respectively. This extends the range of the method by approximately 53, 144 and 851 log-units, respectively, using modest computational resources. Small to average-sized protein domains can now be designed automatically, and side-chain placement calculations can be solved for nearly all sizes of proteins and protein complexes in the growing field of structural genomics.

Algorithms↗

Wheel-running activity and energy metabolism in relation to ambient temperature in mice selected for high wheel-running activity.

Interrelationships between ambient temperature, activity, and energy metabolism were explored in mice that had been selectively bred for high spontaneous wheel-running activity and their random-bred controls. Animals were exposed to three different ambient temperatures (10, 20 and 30 degrees C) and wheel-running activity and metabolic rate were measured simultaneously. Wheel-running activity was decreased at low ambient temperatures in all animals and was increased in selected animals compared to controls at 20 and 30 degrees C. Resting metabolic rate (RMR) and daily energy expenditure (DEE) decreased with increasing ambient temperature. RMR did not differ between control and selected mice, but mass-specific DEE was increased in selected mice. The cost of activity (measured as the slope of the relationship between metabolic rate and running speed) was similar at all ambient temperatures and in control and selected mice. Heat generated by running apparently did not substitute for heat necessary for thermoregulation. The overall estimate of running costs was 1.2 kJ/km for control mice and selected mice.

Animals↗

Changing patterns of acute myocardial infarction: decline in period prevalence and delay in onset.

The rural Pee Dee area of South Carolina has had the highest mortality rate in the nation for coronary heart disease. Community surveillance shows a 22.7% (p = 0.0008) decline in fatal and nonfatal acute myocardial infarction (AMI) rates during the period 1978 to 1985 in the Pee Dee area. Rates for white men decreased 32% (p = 0.001), whereas in other race-sex groups changes were not significant, although there was a downward trend (p = 0.18) among black men. Among white men decreases in the AMI rates occurred in each of the decades of age 35 to 64 years. In all race-sex groups there was a sharp increase in rates between 1978 and 1985 for those 65 to 74 years of age, suggesting that the incidence of AMI was delayed to a later age. Out-of-hospital AMI death rates declined markedly in all race-sex groups: 63% for white men, 62% for white women, 49% for black men, and 39% for black women. Overall case fatality rates declined from 14% (27 of 193) to 10% (23 of 232), but the decrease was not statistically significant.

Adult↗

alpha,beta-Dehydro-3,4-dihydroxyphenylalanine derivatives: rate and mechanism of formation.

The amino acid L-3,4-dihydroxyphenylalanine (DOPA), when present in the primary sequence of proteins, does not form melanin upon oxidation to the quinone, since its amine moiety participates in a peptide bond and cannot undergo internal cyclization. Instead, peptidyl DOPA quinone is available for other reactions. We have investigated the oxidation chemistry of a low molecular weight peptidyl DOPA analog, N-acetylDOPA ethyl ester (NAcDEE), and have shown that a major product of oxidation is an unsaturated DOPA derivative, N-acetyl-alpha,beta-dehydroDOPA ethyl ester (NAc delta DEE) (see companion paper, Rzepecki et al., Arch. Biochem. Biophys. (1991) 285, 17-26). In the present study, we have explored kinetic and mechanistic features of the conversion of NAcDEE to NAc delta DEE and found that the reaction requires: (i) oxidation of NAcDEE to the quinone, (ii) the presence of a Lewis base as a catalyst (phosphate anion was the best of those tried in the pH range 6.0-8.0), and (iii) prevention of competing reactions such as Michael additions. Conversion efficiencies in the presence of Lewis bases ranged between 12 and 19% at pH 8.0 and 35 and 90% at pH 6.0. At least two separate reaction mechanisms appeared necessary to explain the kinetic data: (i) a pseudo-first-order mechanism at pH 6.0 and above, and (ii) an additional second-order mechanism at higher pH which involved both NAcDEE catechol and quinone. The apparent pseudo-first-order rate constants increased with pH from 2.36 X 10(-4) s-1 at pH 6.0 to about 30 X 10(-4) s-1 at pH 8.0 in 0.1 M sodium phosphate. Tautomerization of DOPA quinone to dehydroDOPA may thus be a factor in the sclerotization of natural structures incorporating DOPA containing proteins.

Buffers↗

Mercury in flounder (Platichthys flesus L.) from estuaries and coastal waters of the north-east Irish Sea.

This paper reports concentrations of mercury in muscle tissue of flounder (Platichthys flesus L.) from various estuaries and coastal waters of north Wales and north-west England that encompass the north-east Irish Sea. Mercury concentrations were highest within and offshore the Ribble Estuary (0.476 +/- 0.037 mg kg(-1)) but were also high within the Mersey (0.389+/-0.042 mg kg(-1)) and Dee Estuaries (0.295+/-0.065) and at coastal sites in the vicinity. Values for all three estuaries and their near coastal sites were significantly higher than for sites in the north and central sectors of the study area. Regressions of mercury concentration against fish length showed significant relationships and age accumulation for the majority of sites, particularly within or in close proximity to the Mersey, Dee and Ribble Estuaries.

Journal Article↗

Differential energy costs of winter acclimatized common spiny mice Acomys cahirinus from two adjacent habitats.

The common spiny mouse Acomys cahirinus, of Ethiopian origin, has a widespread distribution across arid, semi-arid and Mediterranean parts of the Arabian sub-region. We compared the daily energy expenditure (DEE), water turnover (WTO) and sustained metabolic scope (SusMS=DEE/resting metabolic rate) of two adjacent populations during the winter. Mice were captured from North- and South- facing slopes (NFS and SFS) of the same valley, comprising mesic and xeric habitats, respectively. Both DEE and SusMS winter values were greater in NFS than SFS mice and were significantly greater than values previously measured in the summer for these two populations in the same environments. However, WTO values were consistent with previously established values and were not significantly different from allometric predictions for desert eutherians. We suggest that physiological plasticity in energy expenditure, which exists both temporally and spatially, combined with stable WTO, perhaps reflecting a xeric ancestry, has enabled A. cahirinus to invade a wide range of habitats.

Acclimatization↗

Energetic cost of physical activity in cystic fibrosis children during Pseudomonas aeruginosa pulmonary exacerbation.

Chronic pulmonary infection by Pseudomonas aeruginosa is observed in 50% of patients with cystic fibrosis and requires the use of recurrent intravenous therapy. A decrease of resting energy expenditure (REE) and an increase of physical activity (PA) after intravenous anti-P. aeruginosa therapy (IVAT) is observed while total energy expenditure (TEE) does not change. A decrease in the energetic cost of physical activity (ECPA) could be hypothesized but has never been studied. Our aim was to assess the evolution of ECPA after home IVAT in both standardized condition at hospital and in free-living condition twice before and after IVAT. Sixteen CF patients (nine boys, seven girls) chronically colonized by P. aeruginosa with a mean age of 12.1+/-2.3 years (range 7.1-14.6) were studied before and after IVAT. Each patient passed throughout a visit in hospital: weight, height and fat-free mass were measured. Then, energy expenditure (EE) measured by indirect calorimetry and heart rate (HR) were simultaneously recorded at different levels of PA: REE, and at different intensity of physical activities on a cycloergometer using an incremental increase of the power brake force. Physical activity energy expenditure (PAEE) was computed in laboratory condition using PAEE=EE-BEE (basal energy expenditure). Linear regression between PAEE and power brake force was fitted for each patient before and after IVAT. ECPA in standardized conditions was compared at different range of power brake force using area under the curve (AUC). After coming back at home, 24 h TEE using the heart rate monitoring technique and PA by triaxial accelerometry were simultaneously measured in free-living condition for 24 h during a school day. ECPA in free-living conditions was compared by the ratio PAEE:PA where PAEE=DEE-REE (DEE=daily energy expenditure). After IVAT, median AUC between 60 and 90 W in standardized condition decreased significantly by -15.4% (median 14.9, range 8.8-30.3 vs. median 12.6, range 8.5-17.6; P<0.05, Wilcoxon rank test) while the decrease for lower range of power work load did not reach significance. Spearman correlation was significant between variations of forced expiratory volume in 1 s and variation of AUC at 30-60 W before and after IVAT in standardized condition. In free-living conditions, ratio PAEE/PA did not vary significantly (median 3.4, range 1.6-6.4 vs. median 2.8, range 1.4-4.8; NS). Our data demonstrate a decrease of ECPA after IVAT in standardized conditions for moderate level of PA (60-90 W), but not in free-living conditions. The decrease of ECPA was probably due to a decrease in the energetic cost of breathing after IVAT, that is particularly relevant to promote PA in CF patients.

Adolescent↗

A biomarker approach to endocrine disruption in flounder--estrogen receptors, hepatocyte proliferation, and sperm motility.

Three different physiological parameters were assessed to determine their potential for serving as biomarkers to predict abnormally elevated vitellogenin (VTG) production in male and immature flounder. Whereas abnormally elevated mean VTG plasma concentrations clearly distinguished the Mersey and Dee flounder studied, the results showed no significant differences in estrogen receptor binding capacity or binding affinity between the two groups. Hepatocyte proliferation was not found to be a "biomarker of effect" that could specifically be used to assess an increase in VTG-related proliferation. Nevertheless, immunohistochemical staining for proliferating cell nuclear antigen did show a significantly higher proliferative activity in the livers of Mersey flounder than that in Dee flounder. Sperm motility also was not found to be a biomarker of effect linked to an abnormal elevation of VTG plasma concentration. The results (higher sperm quality in terms of motility in Mersey flounder) were unexpected but interesting.

Animals↗

Predicting Gran alkalinity and calcium concentrations in river waters over a national scale using a novel modification to the G-BASH model.

Monthly stream water calcium and Gran alkalinity concentration data from 11 sub-catchments of the Nether Beck in the English Lake District have been used to appraise the transferability of the Scottish, River Dee-based G-BASH model. Readily available riparian zone geochemistry and flow paths were used initially to predict minimum and mean stream water concentrations at the Nether Beck, based on calibration equations from the River Dee catchment data. Predicted values significantly exceeded observed values. Differences in runoff between the two areas, leading to a dilution effect in the Nether Beck, explained most of the difference between observed and predicted values. Greater acid deposition in the Lake District also reduced stream water Gran alkalinity concentrations in that area. If regional differences in precipitation, evapotranspiration and pollutant deposition are incorporated into the model, it may then be used reliably to predict catchment susceptibility to acidification over a wide regional (national) scale.

Acid Rain↗

Biallelic FOXRED1 mutations cause infantile mitochondrial encephalopathy with complex I disassembly and basal ganglia degeneration.

Developmental and epileptic encephalopathy (DEE) is a severe neurological disorder. Biallelic mutations in the nuclear-encoded mitochondrial chaperone gene FOXRED1, a specific assembly factor for complex I, cause mitochondrial dysfunction; however, their role in DEE pathogenesis remains unexplored. Clinical data and peripheral blood mononuclear cells (PBMCs) were obtained from two patients with compound heterozygous FOXRED1 mutations (c.850T>C (p.C284R)/c.1054C>T (p.R352W) and c.1054C>T (p.R352W)/c.3dup (p.I2Dfs*35) and age-matched controls. Mitochondrial phenotyping, included complex I activity, mitochondrial respiration stress test, membrane potential, intracellular ROS, and NAD+/NADH ratio, were performed. Both patients exhibited early-onset refractory seizures, basal ganglia lesions, hyperlacticemia, and developmental regression. FOXRED1 mutations resulted in 50% reduction in complex I activity, dissasembly of complex I, mitochondrial depolarization, oxidative stress, and NAD+/NADH imbalance. Niacin restored the NAD+/NADH ratio in vitro, while clinical supplementation reduced blood lactate levels, suggesting it may be a potential therapeutic option.

Humans↗

Seasonal energetics of the Hottentot golden mole at 1500 m altitude.

Winter is an energetically stressful period for small mammals as increasing demands for thermoregulation are often coupled with shortages of food supply. In sub-tropical savannah, Hottentot golden moles (Ambysomus hottentottus longiceps) forage throughout the year and for long periods of each day. This may enable them to acquire sufficient resources from an insectivorous prey base that is both widely dispersed and energetically costly to obtain. However, they also inhabit much cooler regions; how their energy budgets are managed in these areas is unknown. We measured the daily energy expenditure (DEE), resting metabolic rate (RMR) and water turnover (WTO) of free-living golden moles during both winter and summer at high altitude (1500 m). We used measurements of deuterium dilution to estimate body fat during these two periods. DEE, WTO and body mass did not differ significantly between seasons. However, RMR values were higher during the winter than the summer and, in the latter case were also lower than allometric predictions. Body fat was also higher during the winter. Calculations show that during the winter they may restrict activity to shorter, more intense periods. This, together with an increase in thermal insulation, might enable them to survive the cold.

Algorithms↗

A model for predicting chloride concentrations in river water in a relatively unpolluted catchment in north-east Scotland.

The River Dee is an oligotrophic soft water system, in the NE of Scotland, with a catchment area of approximately 2100 km2. The river rises in the Cairngorm Mountains and enters the North Sea at Aberdeen, approximately 140 km from its source. Water chemical quality data was collected every 2 weeks over 12 months for 59 sites distributed throughout the catchment. River water chloride concentrations increased significantly from west to east. In depth investigation of the relationship with distance from the coast revealed the significant difference in spatial distribution of river water chloride concentrations between upland and lowland/agricultural areas, suggesting the possible importance of agricultural practices to streamwater chloride concentrations. Thirty of the sample sites are independent and have been used to develop a simple model for prediction of streamwater Cl- concentration throughout the catchment. The model has been validated using data from the remaining sub-catchments. The model shows that mean Cl- concentration may be reliably predicted from distance from the coast and the percentage of improved grassland and arable land cover in each sub-catchment (r2 = 0.98). It is postulated that the land use effects may be partly due to the evolved link between landuse and catchment altitude characteristics, rather than just the direct effect of applied potassium chloride fertiliser on agricultural land. It was noted that there was insufficient forestry within the River Dee Catchment to reliably include % forest cover in the model.

Agriculture↗

The extent of oestrogenic contamination in the UK estuarine and marine environments--further surveys of flounder.

In 1996, The Centre for Environment, Fisheries and Aquaculture Science (CEFAS) initiated a project to establish whether oestrogenic materials are present in UK estuarine and marine waters at biologically significant concentrations, and to investigate some of the possible effects which these may have in flounder (Platichthys flesus). Early results are published elsewhere; this paper describes the results of a second wider survey of vitellogenin and reproductive abnormalities in UK flounder. Vitellogenin levels in male blood plasma in the period from spring to winter 1997 were found to be significantly elevated (in comparison with a clean reference site on the Alde estuary) in at least one sample from most of the 11 estuaries investigated. The exceptions were the Tamar and the Dee where all fish appeared entirely normal. In broad terms, the degree of oestrogenic contamination as measured by male vitellogenesis in the various estuaries was ranked in the following descending order: Tees > Mersey > Tyne > Wear = Humber = Clyde = Southampton Water = Thames > Dee = Tamar. VTG concentrations in Tees, Mersey and Tyne male fish were extremely high (> 100,000 ng/ml), and often exceeded those normally found in sexually mature females. At most locations, ovotestis conditions in male flounder were entirely absent but 9% of male Mersey fish and 7% of male Tyne fish contained ovotestis. In a few cases, eggs were fully developed with yolk granules. Most testes did not show gross morphological abnormalities related to oestrogenic exposure, although one testis from a Mersey fish appeared to be almost entirely composed of eggs. Abnormal sex ratios were not seen in any estuary. The paper concludes by outlining a new research programme which will be addressing the biological significance of these observations.

Animals↗

Pathology of the liver, kidney and gonad of flounder (Platichthys flesus) from a UK estuary impacted by endocrine disrupting chemicals.

The Mersey estuary is highly contaminated with xenobiotics compared to the nearby Dee estuary. Male flounder, a migratory flatfish caught in the Mersey frequently contains high blood concentrations of the oestrogen controlled, female protein vitellogenin, suggesting that Mersey flounder have been exposed to endocrine disrupting contaminants. Males caught from the Dee contain lower blood vitellogenin levels. Preliminary histopathological examination of 410 flounder from both estuaries, focuses on the liver, kidney and gonads. Hepatic tubular vacuolation, foci of cellular alteration, and hepatocellular tumours were seen. Renal and gonadal pathology included the presence of two Mersey fish with enlarged and abnormal glomeruli, three phenotypic male Mersey flounder with unilateral intersex gonads and one male with bilateral, abnormal ovarian follicular components in the testis. These initial results provide pathological evidence of xenobiotic exposure in flounder sampled from both estuaries. Preliminary findings from flounder sampled from Millport, an offshore site in Southwest Scotland, showed no histopathological evidence of xenobiotic exposure.

Animals↗