Airway sizes and proportions in children quantified by a video-bronchoscopic technique

Background

Detecting serum antibody against inhaled antigens is an important diagnostic adjunct for hypersensitivity pneumonitis (HP). We sought to validate a quantitative fluorimetric assay testing serum from bird fanciers.

Methods

Antibody activity was assessed in bird fanciers and control subjects using various avian antigens and serological methods, and the titer was compared with symptoms of HP.

Results

IgG antibody against pigeon serum antigens, quantified by fluorimetry, provided a good discriminator of disease. Levels below 10 mg/L were insignificant, and increasing titers were associated with disease. The assay was unaffected by total IgG, autoantibodies and antibody to dietary hen's egg antigens. Antigens from pigeon serum seem sufficient to recognize immune sensitivity to most common pet avian species. Decreasing antibody titers confirmed antigen avoidance.

Conclusion

Increasing antibody titer reflected the likelihood of HP, and decreasing titers confirmed antigen avoidance. Quantifying antibody was rapid and the increased sensitivity will improve the rate of false-negative reporting and obviate the need for invasive diagnostic procedures. Automated fluorimetry provides a method for the international standardization of HP serology thereby improving quality control and improving its suitability as a diagnostic adjunct.     

Radioiodinated clioquinol as a biomarker for beta-amyloid: Zn complexes in Alzheimer's disease

Neocortical beta-amyloid (Abeta) aggregates in Alzheimer's disease (AD) are enriched in transition metals that mediate assembly. Clioquinol (CQ) targets metal interaction with Abeta and inhibits amyloid pathology in transgenic mice. Here, we investigated the binding properties of radioiodinated CQ ([(125)I]CQ) to different in vitro and in vivo Alzheimer models. We observed saturable binding of [(125)I]CQ to synthetic Abeta precipitated by Zn(2+) (K(d)=0.45 and 1.40 nm for Abeta(1-42) and Abeta(1-40), respectively), which was fully displaced by free Zn(2+), Cu(2+), the chelator DTPA (diethylene triamine pentaacetic acid) and partially by Congo red. Sucrose density gradient of post-mortem AD brain indicated that [(125)I]CQ concentrated in a fraction enriched for both Abeta and Zn, which was modulated by exogenous addition of Zn(2+) or DTPA. APP transgenic (Tg2576) mice injected with [(125)I]CQ exhibited higher brain retention of tracer compared to non-Tg mice. Autoradiography of brain sections of these animals confirmed selective [(125)I]CQ enrichment in the neocortex. Histologically, both thioflavine-S (ThS)-positive and negative structures were labeled by [(125)I]CQ. A pilot SPECT study of [(123)I]CQ showed limited uptake of the tracer into the brain, which did however, appear to be more rapid in AD patients compared to age-matched controls. These data support metallated Abeta species as the neuropharmacological target of CQ and indicate that this drug class may have potential as in vivo imaging agents for Alzheimer neuropathology.     

The Prion Protein Preference of Sporadic Creutzfeldt-Jakob Disease Subtypes

Sporadic Creutzfeldt-Jakob disease (CJD) is the most prevalent manifestation of the transmissible spongiform encephalopathies or prion diseases affecting humans. The disease encompasses a spectrum of clinical phenotypes that have been correlated with molecular subtypes that are characterized by the molecular mass of the protease-resistant fragment of the disease-related conformation of the prion protein and a polymorphism at codon 129 of the gene encoding the prion protein. A cell-free assay of prion protein misfolding was used to investigate the ability of these sporadic CJD molecular subtypes to propagate using brain-derived sources of the cellular prion protein (PrP^C). This study confirmed the presence of three distinct sporadic CJD molecular subtypes with PrP^C substrate requirements that reflected their codon 129 associations in vivo. However, the ability of a sporadic CJD molecular subtype to use a specific PrP^C substrate was not determined solely by codon 129 as the efficiency of prion propagation was also influenced by the composition of the brain tissue from which the PrP^C substrate was sourced, thus indicating that nuances in PrP^C or additional factors may determine sporadic CJD subtype. The results of this study will aid in the design of diagnostic assays that can detect prion disease across the diversity of sporadic CJD subtypes.     

sAPPα rescues deficits in amyloid precursor protein knockout mice following focal traumatic brain injury

The amyloid precursor protein (APP) is thought to be neuroprotective following traumatic brain injury (TBI), although definitive evidence at moderate to severe levels of injury is lacking. In the current study, we investigated histological and functional outcomes in APP-/- mice compared with APP+/+ mice following a moderate focal injury, and whether administration of sAPPα restored the outcomes in knockout animals back to the wildtype state. Following moderate controlled cortical impact injury, APP-/- mice demonstrated greater impairment in motor and cognitive outcome as determined by the ledged beam and Barnes Maze tests respectively (p < 0.05). This corresponded with the degree of neuronal damage, with APP-/- mice having significantly greater lesion volume (25.0 ± 1.6 vs. 20.3 ± 1.6%, p < 0.01) and hippocampal damage, with less remaining CA neurons (839 ± 245 vs. 1353 ± 142 and 1401 ± 263). This was also associated with an impaired neuroreparative response, with decreased GAP-43 immunoreactivity within the cortex around the lesion edge compared with APP+/+ mice. The deficits observed in the APP-/- mice related to a lack of sAPPα, as treatment with exogenously added sAPPα post-injury improved APP-/- mice histological and functional outcome to the point that they were no longer significantly different to APP+/+ mice (p < 0.05). This study shows that endogenous APP is potentially protective at moderate levels of TBI, and that this neuroprotective activity is related to the presence of sAPPα. Importantly, it indicates that the mechanism of action of exogenously added sAPPα is independent of the presence of endogenous APP.     

Consistency in the host specificity and host sensitivity of the Bacteroides HF183 marker for sewage pollution tracking

Aims: The host specificity (H‐SPF) and host sensitivity (H‐SNV) values of the sewage‐associated HF183 Bacteroides marker in the current study were compared with the previously published studies in South East Queensland (SEQ), Australia, by testing a large number of wastewater and faecal DNA samples (n = 293) from 11 target and nontarget host groups. This was carried out to obtain information on the consistency in the H‐SPF and H‐SNV values of the HF183 marker for sewage pollution tracking in SEQ. Methods and Results: Polymerase chain reaction (PCR) analysis was used to determine the presence/absence of the HF183 marker in wastewater and faecal DNA samples. Among the human composite wastewater (n = 59) from sewage treatment plants and individual human (n = 20) faecal DNA samples tested, 75 (95%) were PCR positive for the HF183 marker. The overall H‐SNV of this marker in target host group was 0·95 (maximum of 1·00). Among the 214 nontarget animal faecal DNA samples tested, 201 (94%) samples were negative for the HF183 marker. Six chicken, five dog and two bird faecal DNA samples, however, were positive for the marker. The overall H‐SPF of the HF183 marker to differentiate between target and nontarget faecal DNA samples was 0·94 (maximum of 1·00). Conclusions: The H‐SNV (0·95) and H‐SPF (0·94) values obtained in this study was slightly lower than previous studies (H‐SNV value of 1·00 in 2007 and 1·00 in 2009; H‐SPF value of 1·00 in 2007 and 0·99 in 2009). Nonetheless, the overall high H‐SNV (0·98) and H‐SPF (0·97) values of the HF183 marker over the past 4 years (i.e. 2007–2011) suggest that the HF183 marker can be reliably used for the detection of sewage pollution in environmental waters in SEQ. Significance and Impact of the Study: In the current study, the HF183 marker was detected in small number nontarget animal faecal samples. Care should be taken to interpret results obtained from catchments or waterways that might be potentially contaminated with dog faecal matter or poultry litter.     

The effect of ingesting a saltbush and barley ration on the carcass and eating quality of sheepmeat

Forage halophytes such as saltbush (Atriplex spp.) are widely used to revegetate Australian saline land and can provide a medium-quality fodder source. An animal house experiment was conducted to investigate differences in the carcass and eating quality of sheep ingesting saltbush from saline land in combination with a barley supplement. Twenty-six merino hoggets (two groups of 13) were fed either a 60 : 40 dried saltbush (Atriplex nummularia): barley (S + B) ration or a 33 : 25 : 42 lupins : barley : oaten hay ration (C) for 10 weeks prior to commercial slaughter. After 10 weeks, all sheep were commercially slaughtered and a single loin (from 12th rib to chump) collected from each animal for taste-panel analysis. Carcass weight, total tissue depth over the 12th rib 110 mm from the midline (GR fat depth), ultimate pH and colour were determined and X-ray bone densitometry used to estimate the fat content of the carcass. Blood samples were taken to assess the hormonal response to ingesting these diets and fatty acid profiles of the subcutaneous and intramuscular fat were determined. Both groups grew at the same rate (62 g/day) and had similar hot carcass weights (P > 0.01) (17.2 ± 0.3 kg for S + B and 17.9 ± 0.3 kg for C). However, these live weights may not be high enough to be commercially viable such that saltbush and barley may only be suitable as a maintenance feed. The S + B-fed sheep had a significantly (P = 0.055) lower fat and higher lean content (P < 0.05) than the C group. This is a positive finding as fat denudation is a significant cost to processors and farmers can produce sheep that are depositing less fat or more lean per unit of live-weight gain. The decreased fat and increased lean content were attributed to the higher protein : energy ratio available for production and lower circulating insulin and higher growth hormone of the S + B-fed sheep. The lower body-fat content and lower metabolisable energy and digestible organic matter intake did correlate with the sheep fed the S + B diet, having a significantly lower percentage of unsaturated fat and equal levels of saturated fat than the C treatment. Diet had no effect on the ultimate pH or colour of the meat. Treatment had no significant effect on any of the eating-quality attributes (P > 0.1). The drying of the saltbush, the shorter length of the experimental period and the low carcass fat content were believed to have contributed to this result. Further field experiments are needed to clarify the benefits to carcass and eating quality of ingesting saltbush.     

How does global change affect the strength of trophic interactions?

Recent research has generally shown that a small change in the number of species in a food web can have consequences both for community structure and ecosystem processes. However ‘change’ is not limited to just the number of species in a community, but might include an alteration to such properties as precipitation, nutrient cycling and temperature, all of which are correlated with productivity. Here we argue that predicted scenarios of global change will result in increased plant productivity. We model three scenarios of change using simple Lotka–Volterra dynamics, which explore how a global change in productivity might affect the strength of local species interactions and detail the consequences for community and ecosystem level stability. Our results indicate that (i) at local scales the average population size of consumers may decline because of poor quality food resources, (ii) that the strength of species interactions at equilibrium may become weaker because of reduced population size, and (iii) that species populations may become more variable and may take longer to recover from environmental or anthropogenic disturbances. At local scales interaction strengths encompass such properties as feeding rates and assimilation efficiencies, and encapsulate functionally important information with regard to ecosystem processes. Interaction strengths represent the pathways and transfer of energy through an ecosystem. We examine how such local patterns might be affected given various scenarios of ‘global change’ and discuss the consequences for community stability and ecosystem functioning.

Zusammenfassung

Die neuere Forschung hat im Allgemeinen gezeigt, dass eine kleine Veränderung in der Zahl der Arten in einem Nahrungsnetz sowohl Konsequenzen für die Gemeinschaftsstruktur als auch für die Ökosystemprozesse haben kann. „Wandel“ist jedoch nicht nur auf die Anzahl der Arten in einer Gemeinschaft beschränkt, sondern kann auch Veränderungen von Eigenschaften wie Niederschlag, Nährstoffkreisläufe und Temperatur beinhalten, die alle mit der Produktivität korreliert sind. Hier argumentieren wir, dass vorhergesagte Szenarios des globalen Wandels in einer erhöhten Pflanzenproduktivität resultieren werden. Wir modellieren drei Szenarien des Wandels unter der Verwendung einfacher Lotka–Volterra–Dynamiken, die erkunden, wie ein globaler Wandel in der Produktivität die Stärke von lokalen Arteninteraktionen beeinflusst, und wir beschreiben detailliert die Konsequenzen für die Gemeinschaft und die Stabilität des Ökosystemlevels. Unsere Ergebnisse deuten darauf hin, (i) dass auf einer lokalen Skala die durchschnittliche Populationsgröße der Konsumenten aufgrund der geringen Qualität der Nahrungsressourcen abnehmen könnte, (ii) dass die Stärke der Arteninteraktionen im Gleichgewicht aufgrund der reduzierten Populationsgröße schwächer werden könnte und (iii) dass die Populationen der Arten variabler werden und länger brauchen könnten, um sich von umweltbedingten oder anthropogenen Störungen zu erholen. Auf lokalen Skalen umfassen Interaktionsstärken Eigenschaften wie Fraßraten und Assimilationseffizienzen und enthalten wichtige funktionelle Information in Bezug auf Ökosystemprozesse. Interaktionsstärken repräsentieren die Energiewege und den Energietransfer in einem Ökosystem. Wir untersuchen, wie solche lokalen Muster unter der Voraussetzung verschiedener gegebener Szenarios des „globalen Wandels“beeinflusst werden könnten und diskutieren die Konsequenzen für die Gemeinschaftsstabilität und Ökosystemfunktion.     

The C-terminal fragment of the Alzheimer's disease amyloid protein precursor is degraded by a proteasome-dependent mechanism distinct from gamma-secretase.

The beta-amyloid protein (Abeta) is derived by proteolytic processing of the amyloid protein precursor (APP). Cleavage of APP by beta-secretase generates a C-terminal fragment (APP-CTFbeta), which is subsequently cleaved by gamma-secretase to produce Abeta. The aim of this study was to examine the cleavage of APP-CTFbeta by gamma-secretase in primary cortical neurons from transgenic mice engineered to express the human APP-CTFbeta sequence. Neurons were prepared from transgenic mouse cortex and proteins labelled by incubation with [35S]methionine and [35S]cysteine. Labelled APP-CTFbeta and Abeta were then immunoprecipitated with a monoclonal antibody (WO2) specific for the transgene sequences. Approximately 30% of the human APP-CTFbeta (hAPP-CTFbeta) was converted to human Abeta (hAbeta), which was rapidly secreted. The remaining 70% of the hAPP-CTFbeta was degraded by an alternative pathway. The cleavage of hAPP-CTFbeta to produce hAbeta was inhibited by specific gamma-secretase inhibitors. However, treatment with proteasome inhibitors caused an increase in both hAPP-CTFbeta and hAbeta levels, suggesting that the alternative pathway was proteasome-dependent. A preparation of recombinant 20S proteasome was found to cleave a recombinant cytoplasmic domain fragment of APP (APPcyt) directly. The study suggests that in primary cortical neurons, APP-CTFbeta is degraded by two distinct pathways, one involving gamma-secretase, which produces Abeta, and a second major pathway involving direct cleavage of APP-CTFbeta within the cytoplasmic domain by the proteasome. These results raise the possibility that defective proteasome function could lead to an increase in Abeta production in the AD brain.     

Treatment with a copper-zinc chelator markedly and rapidly inhibits beta-amyloid accumulation in Alzheimer's disease transgenic mice.

Inhibition of neocortical beta-amyloid (Abeta) accumulation may be essential in an effective therapeutic intervention for Alzheimer's disease (AD). Cu and Zn are enriched in Abeta deposits in AD, which are solubilized by Cu/Zn-selective chelators in vitro. Here we report a 49% decrease in brain Abeta deposition (-375 microg/g wet weight, p = 0.0001) in a blinded study of APP2576 transgenic mice treated orally for 9 weeks with clioquinol, an antibiotic and bioavailable Cu/Zn chelator. This was accompanied by a modest increase in soluble Abeta (1.45% of total cerebral Abeta); APP, synaptophysin, and GFAP levels were unaffected. General health and body weight parameters were significantly more stable in the treated animals. These results support targeting the interactions of Cu and Zn with Abeta as a novel therapy for the prevention and treatment of AD.