Feasibility of wearable technology for 'real-world' gait analysis in children with Prader-Willi and Angelman syndromes.

BACKGROUND: Prader-Willi syndrome (PWS) and Angelman syndrome (AS) are neurodevelopmental disorders in need of innovative 'real-world' outcome measures to evaluate treatment effects. Instrumented gait analysis (IGA) using wearable technology offers a potentially feasible solution to measure "real-world' neurological and motor dysfunction in these groups. METHODS: Children (50% female; 6-16 years) diagnosed with PWS (n = 9) and AS (n = 5) completed 'real-world' IGA assessments using the Physilog®5 wearable. PWS participants completed a laboratory assessment and a 'real-world' long walk. The AS group completed 'real-world' caregiver-assisted assessments. Mean and variability results for stride time, cadence, stance percentage (%) and stride length were extracted and compared across three different data reduction protocols. RESULTS: The wearables approach was found to be feasible, with all participants able to complete at least one assessment. This study also demonstrated significant agreement, using Lin's concordance correlation coefficient (CCC), between laboratory and 'real-world' assessments in the PWS group for mean stride length, mean stance % and stance % CV (n = 7, CCC: 0.782-0.847, P = 0.011-0.009). CONCLUSION: 'Real-world' gait analysis using the Physilog®5 wearable was feasible to efficiently assess neurological and motor dysfunction in children affected with PWS and AS.

Effects of urban density on carbon dioxide exchanges: Observations of dense urban, suburban and woodland areas of southern England.

Anthropogenic and biogenic controls on the surface-atmosphere exchange of CO2 are explored for three different environments. Similarities are seen between suburban and woodland sites during summer, when photosynthesis and respiration determine the diurnal pattern of the CO2 flux. In winter, emissions from human activities dominate urban and suburban fluxes; building emissions increase during cold weather, while traffic is a major component of CO2 emissions all year round. Observed CO2 fluxes reflect diurnal traffic patterns (busy throughout the day (urban); rush-hour peaks (suburban)) and vary between working days and non-working days, except at the woodland site. Suburban vegetation offsets some anthropogenic emissions, but 24-h CO2 fluxes are usually positive even during summer. Observations are compared to estimated emissions from simple models and inventories. Annual CO2 exchanges are significantly different between sites, demonstrating the impacts of increasing urban density (and decreasing vegetation fraction) on the CO2 flux to the atmosphere.

Establishment of transplantation tolerance via minimal conditioning in aged recipients.

Mixed hematopoietic chimerism is a powerful means of generating donor-specific tolerance, allowing long-term graft acceptance without lifelong dependence on immunosuppressive drugs. To avoid the need for whole body irradiation and associated side effects, we utilized a radiation-free minimal conditioning regime to induce long-term tolerance across major histocompatibility barriers. We found that low-dose busulfan, in combination with host T cell depletion and short-term sirolimus-based immunosuppression, facilitated efficient donor engraftment. Tolerance was achieved when mice were transplanted with whole or T cell-depleted bone marrow, or purified progenitor cells. Tolerance induction was associated with an expansion in regulatory T cells and was not abrogated in the absence of a thymus, suggesting a dominant or compensatory peripheral mode of tolerance. Importantly, we were able to generate durable chimerism and tolerance to donor skin grafts in both young and aged mice, despite age-related thymic atrophy and immune senescence. Clinically, this is especially relevant as the majority of transplant recipients are older patients whose immune recovery might be dangerously slow and would benefit from radiation-free minimal conditioning regimes that allow efficient donor engraftment without fully ablating the recipient immune system.

CfaE tip mutations in enterotoxigenic Escherichia coli CFA/I fimbriae define critical human intestinal binding sites.

Enterotoxigenic Escherichia coli (ETEC) use colonization factors to attach to the human intestinal mucosa, followed by enterotoxin expression that induces net secretion and diarrhoeal illness. ETEC strain H10407 expresses CFA/I fimbriae, which are composed of multiple CfaB structural subunits and a CfaE tip subunit. Currently, the contribution of these individual fimbrial subunits in intestinal binding remains incompletely defined. To identify the role of CfaE in attachment in the native ETEC background, an R181A single-amino-acid substitution was introduced by recombination into the H10407 genome. The substitution of R181A eliminated haemagglutination and binding of intestinal mucosa biopsies in in vitro organ culture assays, without loss of CFA/I fimbriae expression. Wild-type in trans plasmid-expressed cfaE restored the binding phenotype. In contrast, in trans expression of cfaE containing amino acid 181 substitutions with similar amino acids, lysine, methionine and glutamine did not restore the binding phenotype, indicating that the loss of the binding phenotype was due to localized areas of epitope disruption. R181 appears to have an irreplaceable role in the formation of a receptor-binding feature on CFA/I fimbriae. The results specifically indicate that the CfaE tip protein is a required binding factor in CFA/I-mediated ETEC colonization, making it a potentially important vaccine antigen.

Improving water use in crop production.

Globally, agriculture accounts for 80-90% of all freshwater used by humans, and most of that is in crop production. In many areas, this water use is unsustainable; water supplies are also under pressure from other users and are being affected by climate change. Much effort is being made to reduce water use by crops and produce 'more crop per drop'. This paper examines water use by crops, taking particularly a physiological viewpoint, examining the underlying relationships between carbon uptake, growth and water loss. Key examples of recent progress in both assessing and improving crop water productivity are described. It is clear that improvements in both agronomic and physiological understanding have led to recent increases in water productivity in some crops. We believe that there is substantial potential for further improvements owing to the progress in understanding the physiological responses of plants to water supply, and there is considerable promise within the latest molecular genetic approaches, if linked to the appropriate environmental physiology. We conclude that the interactions between plant and environment require a team approach looking across the disciplines from genes to plants to crops in their particular environments to deliver improved water productivity and contribute to sustainability.

Resource-conserving agriculture increases yields in developing countries.

Despite great recent progress, hunger and poverty remain widespread and agriculturally driven environmental damage is widely prevalent. The idea of agricultural sustainability centers on the need to develop technologies and practices that do not have adverse effects on environmental goods and services, and that lead to improvements in food productivity. Here we show the extent to which 286 recent interventions in 57 poor countries covering 37 M ha (3% of the cultivated area in developing countries) have increased productivity on 12.6 M farms while improving the supply of critical environmental services. The average crop yield increase was 79% (geometric mean 64%). All crops showed water use efficiency gains, with the highest improvement in rainfed crops. Potential carbon sequestered amounted to an average of 0.35 t C ha(-1) y(-1). If a quarter of the total area under these farming systems adopted sustainability enhancing practices, we estimate global sequestration could be 0.1 Gt C y(-1). Of projects with pesticide data, 77% resulted in a decline in pesticide use by 71% while yields grew by 42%. Although it is uncertain whether these approaches can meet future food needs, there are grounds for cautious optimism, particularly as poor farm households benefit more from their adoption.

Seasonal changes in the photosynthetic capacity of canopy oak (Quercus robur) leaves: the impact of slow development on annual carbon uptake.

The photosynthetic development of pedunculate oak ( Quercus robur L.) sun leaves in a mature woodland canopy in Oxfordshire, southern England, was investigated in situ during 3 years with contrasting weather conditions. Development of full photosynthetic capacity (indicated by light-saturated net assimilation rates, A(max), typical of the summer period) took between approximately 50 and 70 days after budbreak in different years. This slow development means that these leaves do not utilise a substantial fraction of the seasonal peak of solar irradiance. During the late autumn senscence period the photosynthetic capacity declined over a 2-week period, but as this is a time of low irradiance, the loss of potential photosynthesis was relatively small. The consequences of these developmental changes and differences in bud break dates for daily and seasonal leaf carbon balance were investigated through a simple light-response photosynthetic model. Seasonal changes in photosynthetic capacity would decrease annual carbon uptake per unit leaf area by about 23% compared to that potentially possible if leaves photosynthesised at peak rates throughout the growing season. This difference is likely to be up to 30% larger in years with late budburst and as low as 18% in years with early budburst.

High resolution imaging of photosynthetic activities of tissues, cells and chloroplasts in leaves.

Through imaging of chlorophyll fluorescence, it is possible to produce parameterized fluorescence images that estimate the operating quantum efficiency of photosystem II (PSII) photochemistry and which can be used to reveal heterogeneous patterns of photosynthetic performance within leaves. The operating quantum efficiency of PSII photochemistry is dependent upon the effective absorption cross-section of the light-harvesting system of PSII and the photochemical capacity of PSII. The effective absorption cross-section is decreased by the process of down-regulation, which is widely thought to operate within the pigment matrices of PSII and which results in non-photochemical quenching of chlorophyll fluorescence. The photochemical capacity is non-linearly related to the proportion of PSII centres in the 'open' state and results in photochemical quenching of chlorophyll fluorescence. Examples of heterogeneity of the operating quantum efficiency of PSII photochemistry during the induction of photosynthesis in maize leaves and in the chloroplast populations of stomatal guard cells of a leaf of Tradescantia albifora are presented, together with analyses of the factors determining this heterogeneity. A comparison of the operating quantum efficiency of PSII photochemistry within guard cells and adjacent mesophyll cells of Commelina communis is also made, before and after stomatal closure through a change in ambient humidity.

Very high productivity of the C4 aquatic grass Echinochloa polystachya in the Amazon floodplain confirmed by net ecosystem CO2 flux measurements.

Fluxes of CO2 and H2O vapour from dense stands of the C4 emergent macrophyte grass Echinochloa polystachya were measured by eddy covariance in both the low water (LW) and high water (HW, flooded) phases of the annual Amazon river cycle at Manaus, Brazil. Typical clear-sky midday CO2 uptake rates by the vegetation stand (including detritus, sediment or water surface) were 30 and 35 µmol CO2 (ground) m-2 s-1 in the LW and HW periods, respectively. A rectangular hyperbola model fitted the responses of "instantaneous" (20- or 30-min average) net CO2 exchange rates to incident photosynthetic photon flux densities (PFD) well. Stand evaporation rates were linearly related to PFD. The major difference in CO2 uptake rates between the two periods was the larger respiration flux during LW due to the CO2 efflux from sediment, roots and litter. Integrated 20- or 30-min fluxes were used to derive relationships between daily CO2 and H2O vapour fluxes and incident radiation. The daily CO2 fluxes were almost linearly related to incident radiation, but there was evidence of saturation at the highest daily radiation totals. Annual productivity estimated from the daily model in 1996-1997 agreed closely with that previously estimated for 1985-1986 from a leaf-scale photosynthetic model, but were some 15% less than those derived at that time from biomass harvests. Both CO2 uptake and water use efficiency were comparable with those found in fertilised maize fields in warm temperate conditions.

Regulation of mesophyll photosynthesis in intact wheat leaves by cytoplasmic phosphate concentrations.

The effect of D-(+)-mannose, inorganic phosphate (Pi) and mannose-6-phosphate on net mesophyll CO2 assimilation rate (A) and stomatal conductance (gs) of wheat (Triticum aestivum L.) leaves was studied. The compounds were supplied through the transpiration stream of detached leaves from plants grown in sand in growth cabinets or glasshouses, with different concentrations of Pi (0.25, 1.0 and 4.0 mM) supplied during growth. In all cases, 10 mM D-(+)mannose caused 40-60% reduction of A within 30 min, though the time courses differed for flag leaves and the sixth leaf on the mainstem of glasshouse- and cabinet-grown plants. D-(+)Mannose had a similar effect on A in leaves having a fourfold range in total phosphate content. Effects of D-(+)mannose in reducing gs were always slower than on A. When the CO2 concentration in the leaf chamber was adjusted to maintain intercellular CO2 concentration (Ci) constant as A declined after mannose supply, gs still declined indicating that stomatal closure was not caused by changing Ci. Supplying mannose-6-phosphate at 10 and 1 mM and Pi at 5 and 10 mM concentrations caused rapid reductions in gs and also direct reductions in A. The observed effects of mannose and Pi on assimilation are consistent with the proposed regulatory role of cytoplasmic Pi in determining mesophyll carbon assimilation that has been derived previously using leaf discs, protoplasts and chloroplasts.

Photosynthesis, water use and growth of a C4 grass stand at high CO 2 concentration.

Leaf photosynthesis rate of the C4 species Paspalum plicatulum Michx was virtually CO2-saturated at normal atmospheric CO2 concentration but transpiration decreased as CO2 was increased above normal concentrations thereby increasing transpiration efficiency. To test whether this leaf response led growth to be CO2-sensitive when water supply was restricted, plants were grown in sealed pots of soil as miniature swards. Water was supplied either daily to maintain a constant water table, or at three growth restricting levels on a 5-day drying cycle. Plants were either in a cabinet with normal air (340 µmol (CO2) mol(-1) (air)) or with 250 µmol mol(-1) enrichment. Harvesting was by several cycles of defoliation.With abundant water supply high CO2 concentration did not cause increased growth, but it did not cause an increase in growth over a wide range of growth-limiting water supplies either. Only when water supply was less than 30-50% of the amount used by the stand with a water-table was there evidence that dry weight growth was enhanced by high CO2. In addition, with successive regrowth, the enhancing effect under a regime of minimal water allocations, became attenuated. Examination of leaf gas exchange, growth and water use data showed that in the long term stomatal conductance responses were of little significance in matching plant water use to low water allocation; regulation of leaf area was the mechanism through which consumption matched supply. Since high CO2 effects operate principally via stomatal conductance in C4 species, we postulate that for this species higher CO2 concentrations expected globally in future will not have much effect on long term growth.

Ethylene Contamination of CO(2) Cylinders: Effects on Plant Growth in CO(2) Enrichment Studies.

Ethylene concentrations of CO(2) cylinders from different sources ranged from <0.1 up to 475 microliters per liter. The effect of the higher ethylene concentrations on growth of species in CO(2) enrichment studies was examined. Though maize plants showed no effect on C(2)H(4), growth of tomato, rice, mung bean, and phalaris was substantially reduced by ambient concentrations of ethylene in the range of 0.02 to 0.06 microliters per liter.

Developmental changes in infant pain expression during immunization injections.

Developmental changes in pain expression provoked by routine immunization injections during the first 2 years of life were examined. An interval-sampling, behavioral observation system was developed to code categories of expressive behavior in infants, their mothers and the nurse responsible for the injection. Qualitative changes were observed in the infants' behavior, with those less than 12 months of age responding in a more spontaneous, diffuse manner, whereas the older infants displayed more anticipatory distress, descriptive language and goal-directed movement. Mothers and the nurse actively interacted with each other and the infant with a range of vocal and nonvocal actions. The findings justified the use of unobtrusive, naturalistic observation as a means of assisting practitioners who suffer from an inadequate knowledge-base on pain in children.

Stomatal sensitivity to carbon dioxide and humidity: a comparison of two c(3) and two c(4) grass species.

The sensitivity of stomatal conductance to changes of CO(2) concentration and leaf-air vapor pressure difference (VPD) was compared between two C(3) and two C(4) grass species. There was no evidence that stomata of the C(4) species were more sensitive to CO(2) than stomata of the C(3) species. The sensitivity of stomatal conductance to CO(2) change was linearly proportional to the magnitude of stomatal conductance, as determined by the VPD, the same slope fitting the data for all four species. Similarly, the sensitivity of stomatal conductance to VPD was linearly proportional to the magnitude of stomatal conductance. At small VPD, the ratio of intercellular to ambient CO(2) concentration, C(i)/C(a), was similar in all species (0.8-0.9) but declined with increasing VPD, so that, at large VPD, C(i)/C(a) was 0.7 and 0.5 (approximately) in C(3) and C(4) species, respectively. Transpiration efficiency (net CO(2) assimilation rate/transpiration rate) was larger in the C(4) species than in the C(3) species at current atmospheric CO(2) concentrations, but the relative increase due to high CO(2) was larger in the C(3) than in the C(4) species.

Muscle proteolysis induced by neural colchicine cuffs cast in situ.

The effects of neurotrophic factors on muscle protein degradation in rat leg muscle were studied. In order to inhibit axoplasmic transport and therefore transport of "trophic" factors, the colchicine cuff method of Albuquerque et. al. (1972) was modified so that the cuffs were cast in situ. Protein degradation was estimated by monitoring the release of tyrosine from the muscle. Our observations that colchicine cuffs increased tyrosine release are consistent with the concept of nerve-muscle trophism.