Both the invasion of red blood cells (RBCs) by Plasmodium falciparum parasites and the sequestration of parasite-infected RBCs in the microvasculature are mediated in part by complement receptor one ...(CR1). RBC surface CR1 level can vary between individuals by more than 20-fold and may be associated with the risk of severe malaria. The factors that influence RBC CR1 level variation are poorly understood, particularly in African populations. We studied 3535 child residents of a malaria-endemic region of coastal Kenya and report, for the first time, that the CR1 Knops blood group alleles Sl2 and McC(b), and homozygous HbSS are positively associated with RBC CR1 level. Sickle cell trait and ABO blood group did not influence RBC CR1 level. We also confirm the previous observation that α(+)thalassaemia is associated with reduced RBC CR1 level, possibly due to small RBC volume, and that age-related changes in RBC CR1 expression occur throughout childhood. RBC CR1 level in malaria-endemic African populations is a complex phenotype influenced by multiple factors that should be taken into account in the design and interpretation of future studies on CR1 and malaria susceptibility.
The objective of the current study is to prepare a biomimetic collagen–apatite scaffold for improved bone repair and regeneration. A novel bottom–up approach has been developed, which combines a ...biomimetic self-assembly method with a controllable freeze-casting technology. In this study, the mineralized collagen fibers were generated using a simple one-step co-precipitation method which involved collagen self-assembly and in situ apatite precipitation in a collagen-containing modified simulated body fluid (m-SBF). The precipitates were then subjected to controllable freeze casting, forming scaffolds with either an isotropic equiaxed structure or a unidirectional lamellar structure. These scaffolds were comprised of collagen fibers and poorly crystalline bone-like carbonated apatite nanoparticles. The mineral content in the scaffold could be tailored in the range 0–54wt.% by simply adjusting the collagen content in the m-SBF. Further, the mechanisms of the formation of both the equiaxed and the lamellar scaffolds were investigated, and freezing regimes for equiaxed and lamellar solidification were established. Finally, the bone-forming capability of such prepared scaffolds was evaluated in vivo in a mouse calvarial defect model. It was confirmed that the scaffolds well support new bone formation.
Although high-functioning individuals with autistic disorder (i.e. autism and Asperger syndrome) are of normal intelligence, they have life-long abnormalities in social communication and emotional ...behaviour. However, the biological basis of social difficulties in autism is poorly understood. Facial expressions help shape behaviour, and we investigated if high-functioning people with autistic disorder show neurobiological differences from controls when processing emotional facial expressions. We used functional MRI to investigate brain activity in nine adults with autistic disorder (mean age +/- standard deviation 37 +/- 7 years; IQ 102 +/- 15) and nine controls (27 +/- 7 years; IQ 116 +/- 10) when explicitly (consciously) and implicitly (unconsciously) processing emotional facial expressions. Subjects with autistic disorder differed significantly from controls in the activity of cerebellar, mesolimbic and temporal lobe cortical regions of the brain when processing facial expressions. Notably, they did not activate a cortical 'face area' when explicitly appraising expressions, or the left amygdala region and left cerebellum when implicitly processing emotional facial expressions. High-functioning people with autistic disorder have biological differences from controls when consciously and unconsciously processing facial emotions, and these differences are most likely to be neurodevelopmental in origin. This may account for some of the abnormalities in social behaviour associated with autism.
Here we document at century to millennial scale the regional changes of precipitation–evaporation from the late Pleistocene to present with multiproxy methods on a north–south transect of lake sites ...across the eastern cordillera of the central Andes. The transect of study sites covers the area from ∼14°S to 20°S and includes core studies from seven lakes and modern calibration water samples from twenty-three watersheds analyzed to constrain the down-core interpretations of stable isotopes and diatoms. We selected lakes in different hydrologic settings spanning a range of sensitivity to changes in the moisture balance. These include: (1) lakes directly receiving glacial meltwater, (2) overflowing lakes in glaciated watersheds, (3) overflowing lakes in watersheds without active glaciers, and (4) lakes that become closed basins during the dry season. The results of our current work on multiple lakes in the Bolivian Andes show that while the overall pattern of Holocene environmental change is consistent within the region, conditions were not always stable over centennial to over millennial timescales and considerable decadal- to century-scale climate variability is evident Abbott et al., Quat. Res. 47 (1997) 70–80, Quat. Res. 47 (1997) 169–180, Quat. Sci. Rev. 19 (2000) 1801–1820; Polissar, Master's thesis, University of Massachusetts (1999). Comparison of the paleoclimate record from one well-studied site, Lago Taypi Chaka Kkota (LTCK), with others within the region illustrates a consistent overall pattern of aridity from the late glacial through the middle Holocene. Previous work noted a difference between the timing of water-level rise in Lake Titicaca ∼5.0–3.5 ka B.P. Abbott et al., Quat. Res. 47 (1997) 169–180; Cross et al., Holocene 10 (2000) 21–32; Rowe et al., Clim. Change 52 (2002) 175–199 and the onset of wetter conditions at 2.3 ka B.P. in LTCK, a lake that drains into the southern end of Lake Titicaca Abbott et al., Quat. Res. 47 (1997) 70–80. Sedimentary and oxygen isotope evidence from Paco Cocha (13°54′S) located in the northern reaches of the expansive 57 000 km
2 Titicaca watershed, which spans ∼14°S to 17°S, indicates that glaciers returned to the watershed around 4.8 ka B.P. In addition, sedimentary and geochemical data from Llacho Kkota (15°07′S), located between LTCK (16°12′S) and Paco Cocha, indicate wetter conditions around 3.4 ka B.P. This suggests wetter conditions occurred first in the northern reaches of the Titicaca watershed and resulted in rising water levels in Lake Titicaca while the LTCK watershed remained unglaciated and seasonally desiccated. Comparison of the paleoclimate records from Paco Cocha, LTCK, and Potosi with other paleoclimate records from the region including Lake Titicaca and Nevado Sajama illustrates a consistent overall pattern of aridity from the late Pleistocene through the middle Holocene, but wetter conditions occurred in the northern areas first, and the aridity in the north was of shorter duration and less severe. The progressive increase in wet season (summer) insolation across the region during the Holocene likely resulted in an increasingly southward position and intensification of the zone of intense summer convection – known as the Intertropical Convergence Zone over the tropical Atlantic and Pacific. We suggest this is the cause of the overall pattern of increasingly later dates for the onset of wetter conditions moving north to south that we observe across the seven lakes discussed here that span four degrees of latitude. However, this does not explain the decadal- to century-scale variability that demonstrably exists at these same sites. Overall the last 2.3 ka has been the wettest period during the Holocene, but even during this relatively wet phase there are century-scale lowstands in lakes, including Titicaca, Llacho Kkota, Juntutuyo (17°33′S), and Potosi (19°38′S), and significant changes in the extent of glacial activity in the glaciated watersheds of Paco Cocha, LTCK, and Viscachani (16°11′S), indicating the continued sensitivity of the region to shifts in the moisture balance.
Fire activity has varied globally and continuously since the last glacial maximum (LGM) in response to long-term changes in global climate and shorter-term regional changes in climate, vegetation, ...and human land use. We have synthesized sedimentary charcoal records of biomass burning since the LGM and present global maps showing changes in fire activity for time slices during the past 21,000 years (as differences in charcoal accumulation values compared to pre-industrial). There is strong broad-scale coherence in fire activity after the LGM, but spatial heterogeneity in the signals increases thereafter. In North America, Europe and southern South America, charcoal records indicate less-than-present fire activity during the deglacial period, from 21,000 to ~11,000 cal yr BP. In contrast, the tropical latitudes of South America and Africa show greater-than-present fire activity from ~19,000 to ~17,000 cal yr BP and most sites from Indochina and Australia show greater-than-present fire activity from 16,000 to ~13,000 cal yr BP. Many sites indicate greater-than-present or near-present activity during the Holocene with the exception of eastern North America and eastern Asia from 8,000 to ~3,000 cal yr BP, Indonesia and Australia from 11,000 to 4,000 cal yr BP, and southern South America from 6,000 to 3,000 cal yr BP where fire activity was less than present. Regional coherence in the patterns of change in fire activity was evident throughout the post-glacial period. These complex patterns can largely be explained in terms of large-scale climate controls modulated by local changes in vegetation and fuel load.
It is well known that a boundary layer of air is entrained around a rotating grinding wheel. The effects of the boundary layer have been under some scrutiny in recent years with most research being ...based on trying to overcome the boundary layer. The current investigation aims to show through experiment and modelling, the effects of the boundary layer on cutting fluid application and how it can be used to aid delivery by increasing flow rate beneath the wheel. Results from three experiments with different quantities of cutting fluid passing through the grinding zone are presented.
Clustering of Complement Receptor 1 (CR1) in the erythrocyte membrane is important for immune-complex transfer and clearance. CR1 contains the Knops blood group antigens, including the antithetical ...pairs Swain-Langley 1 and 2 (Sl1 and Sl2) and McCoy a and b (McC
and McC
), whose functional effects are unknown. We tested the hypothesis that the Sl and McC polymorphisms might influence CR1 clustering on erythrocyte membranes. Blood samples from 125 healthy Kenyan children were analysed by immunofluorescence and confocal microscopy to determine CR1 cluster number and volume. In agreement with previous reports, CR1 cluster number and volume were positively associated with CR1 copy number (mean number of CR1 molecules per erythrocyte). Individuals with the McC
/McC
genotype had more clusters per cell than McC
/McC
individuals. However, this association was lost when the strong effect of CR1 copy number was included in the model. No association was observed between Sl genotype, sickle cell genotype, α+thalassaemia genotype, gender or age and CR1 cluster number or volume. Therefore, after correction for CR1 copy number, the Sl and McCoy polymorphisms did not influence erythrocyte CR1 clustering, and the effects of the Knops polymorphisms on CR1 function remains unknown.
Primary lateral sclerosis (PLS) is an idiopathic upper motor neuron degenerative disorder. The aim of this study was to compare brain volumes in patients with PLS and controls and determine whether ...differences were due to loss of gray matter (GM), white matter (WM), or both.
T1-weighted images were acquired in patients with PLS and controls. Freesurfer was used for volumetric segmentation of whole brain, cortical GM, precentral and postcentral cortex, WM, corpus callosum, basal ganglia, thalamus, cerebellum, and CSF. Relationships were sought between disease severity, disease duration, age and brain volumes.
Eleven patients with PLS and 10 age-matched healthy controls were included in this study. Compared to control subjects, patients with PLS had significantly smaller whole brain (p = 0.043), frontal lobe (p = 0.036), precentral cortex (p = 0.016), and corpus callosum (p = 0.036) volumes. There was a trend toward a smaller thalamus (p = 0.051). Disease severity correlated with ventricular CSF volume (rho = -0.604, p = 0.025) and precentral cortex volume loss (rho = 0.599, p = 0.026). Disease duration tended to correlate with a loss of WM (rho = -0.636, p = 0.063).
Our results suggest that there is focal atrophy in patients with primary lateral sclerosis compared with controls especially in the precentral cortex and the corpus callosum, specifically where there is transfer of motor fibers.
We measured the dose–response effects of drink sodium content (treatments: 0mmol/l, 18mmol/l, 30mmol/l, 40mmol/l, and 60mmol/l) on sensory perception and palatability in athletes at four time points: ...in a sedentary laboratory setting (non-exercise context), pre-exercise, and after 60min and 120min of aerobic-circuit exercise. Fifty-five triathletes and runners (30 males, 39.7 (8.0 S.D.) years; 25 females, 37.2 (9.2 S.D.) years) sip-tested chilled 6% carbohydrate drinks varying in sodium content during sedentary and pre-exercise conditions and had ad lib access to drinks during exercise conditions. There was a significant intensity discrimination among all sodium levels (p≤0.001) except 0mmol/l vs. 18mmol/l, and 30mmol/l vs. 40mmol/l. There were no significant differences among time points for perceived salt intensity. However, overall drink acceptability and liking of saltiness of the 60mmol/l drink was greater pre-exercise, after 60min and after 120min of exercise than during the sedentary condition. The environmental cues of the exercise context may be associated with an increase in palatability of the drink containing 60mmol/l of sodium over the sedentary condition. Sensory measures provided better differentiation (were more sensitive to treatment effects) among salt concentrations than was fluid intake. Neither thirst nor sweat loss were related to drink palatability or liking of saltiness. Liking of saltiness but not thirst was related to fluid intake. There was a significant negative correlation between sodium ingested (mg/kg) and percent body mass loss.
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