Ediacaran metazoan reveals lophotrochozoan affinity and deepens root of Cambrian Explosion

Through exceptional preservation, we establish a phylogenetic connection between Ediacaran and Cambrian metazoans. We describe the first three-dimensional, pyritized soft tissue in Namacalathus from the Ediacaran Nama Group, Namibia, which follows the underlying form of a stalked, cup-shaped, calcitic skeleton, with six radially arranged lobes projecting into an apical opening and lateral lumens. A thick body wall and probable J-shaped gut are present within the cup, and the middle layer of the often-spinose skeleton and skeletal pores are selectively pyritized, supporting an organic-rich composition and tripartite construction with possible sensory punctae. These features suggest a total group lophotrochozoan affinity. These morphological data support molecular phylogenies and demonstrates that the origin of modern lophotrochozoan phyla, and their ability to biomineralize, had deep roots in the Ediacaran.

U.K. Community Earth System Modeling for CMIP6

We describe the approach taken to develop the United Kingdom's first community Earth system model, UKESM1. This is a joint effort involving the Met Office and the Natural Environment Research Council (NERC), representing the U.K. academic community. We document our model development procedure and the subsequent U.K. submission to CMIP6, based on a traceable hierarchy of coupled physical and Earth system models. UKESM1 builds on the well-established, world-leading HadGEM models of the physical climate system and incorporates cutting-edge new representations of aerosols, atmospheric chemistry, terrestrial carbon, and nitrogen cycles and an advanced model of ocean biogeochemistry. A high-level metric of overall performance shows that both models, HadGEM3-GC3.1 and UKESM1, perform better than most other CMIP6 models so far submitted for a broad range of variables. We point to much more extensive evaluation performed in other papers in this special issue. The merits of not using any forced climate change simulations within our model development process are discussed. First results from HadGEM3-GC3.1 and UKESM1 include the emergent climate sensitivity (5.5 and 5.4 K, respectively) which is high relative to the current range of CMIP5 models. The role of cloud microphysics and cloud-aerosol interactions in driving the climate sensitivity, and the systematic approach taken to understand this role, is highlighted in other papers in this special issue. We place our findings within the broader modeling landscape indicating how our understanding of key processes driving higher sensitivity in the two U.K. models seems to align with results from a number of other CMIP6 models.

Regional nutrient decrease drove redox stabilisation and metazoan diversification in the late Ediacaran Nama Group, Namibia

The late Ediacaran witnessed an increase in metazoan diversity and ecological complexity, marking the inception of the Cambrian Explosion. To constrain the drivers of this diversification, we combine redox and nutrient data for two shelf transects, with an inventory of biotic diversity and distribution from the Nama Group, Namibia (~550 to ~538 Million years ago; Ma). Unstable marine redox conditions characterised all water depths in inner to outer ramp settings from ~550 to 547 Ma, when the first skeletal metazoans appeared. However, a marked deepening of the redoxcline and a reduced frequency of anoxic incursions onto the inner to mid-ramp is recorded from ~547 Ma onwards, with full ventilation of the outer ramp by ~542 Ma. Phosphorus speciation data show that, whilst anoxic ferruginous conditions were initially conducive to the drawdown of bioavailable phosphorus, they also permitted a limited degree of phosphorus recycling back to the water column. A long-term decrease in nutrient delivery from continental weathering, coupled with a possible decrease in upwelling, led to the gradual ventilation of the Nama Group basins. This, in turn, further decreased anoxic recycling of bioavailable phosphorus to the water column, promoting the development of stable oxic conditions and the radiation of new mobile taxa.

Basin bifurcations, oscillatory instability and rate-induced thresholds for Atlantic meridional overturning circulation in a global oceanic box model

The Atlantic meridional overturning circulation (AMOC) transports substantial amounts of heat into the North Atlantic sector, and hence is of very high importance in regional climate projections. The AMOC has been observed to show multi-stability across a range of models of different complexity. The simplest models find a bifurcation associated with the AMOC 'on' state losing stability that is a saddle node. Here, we study a physically derived global oceanic model of Wood et al. with five boxes, that is calibrated to runs of the FAMOUS coupled atmosphere-ocean general circulation model. We find the loss of stability of the 'on' state is due to a subcritical Hopf for parameters from both pre-industrial and doubled CO₂ atmospheres. This loss of stability via subcritical Hopf bifurcation has important consequences for the behaviour of the basin of attraction close to bifurcation. We consider various time-dependent profiles of freshwater forcing to the system, and find that rate-induced thresholds for tipping can appear, even for perturbations that do not cross the bifurcation. Understanding how such state transitions occur is important in determining allowable safe climate change mitigation pathways to avoid collapse of the AMOC.

Publisher Correction: Critical Southern Ocean climate model biases traced to atmospheric model cloud errors

'In the original HTML version of this Article, ref.12 was incorrectly cited in the first sentence of the first paragraph of the Introduction. The correct citation is ref. 2. This has now been corrected in the HTML version of the Article; the PDF version was correct at the time of publication.'

Critical Southern Ocean climate model biases traced to atmospheric model cloud errors

The Southern Ocean is a pivotal component of the global climate system yet it is poorly represented in climate models, with significant biases in upper-ocean temperatures, clouds and winds. Combining Atmospheric and Coupled Model Inter-comparison Project (AMIP5/CMIP5) simulations, with observations and equilibrium heat budget theory, we show that across the CMIP5 ensemble variations in sea surface temperature biases in the 40-60°S Southern Ocean are primarily caused by AMIP5 atmospheric model net surface flux bias variations, linked to cloud-related short-wave errors. Equilibration of the biases involves local coupled sea surface temperature bias feedbacks onto the surface heat flux components. In combination with wind feedbacks, these biases adversely modify upper-ocean thermal structure. Most AMIP5 atmospheric models that exhibit small net heat flux biases appear to achieve this through compensating errors. We demonstrate that targeted developments to cloud-related parameterisations provide a route to better represent the Southern Ocean in climate models and projections.

The use of omalizumab in allergen immunotherapy

Although omalizumab (anti-IgE) is currently only approved for the treatment of asthma and chronic idiopathic urticaria, it has also been studied as an off-label treatment for numerous allergic conditions, including use as an adjunct to allergen immunotherapy in the treatment of allergic rhinitis, asthma, venom hypersensitivity and food allergy. We conducted a review of publications involving the use of omalizumab with allergen immunotherapy, by searching PubMed with key search terms of "omalizumab" and "immunotherapy." Omalizumab has been used in combination with inhalant allergen immunotherapy for the treatment of seasonal allergic rhinitis and comorbid asthma. While there have been no randomized controlled trials evaluating the addition of omalizumab to venom IT, several case reports and small patient series have been published on the use of omalizumab with venom IT. Omalizumab has been used in conjunction with oral immunotherapy for the treatment of milk, peanut and egg, as well as other foods in multi-allergen protocols. In conclusion, omalizumab used in conjunction with immunotherapy has shown promising results, especially in the reduction of adverse reactions. At this stage, larger, randomized, placebo-controlled trials are needed to better identify those patients who would benefit the most from the addition of omalizumab to immunotherapy, as well as optimal dosing strategies and duration of treatment.

Controls on the evolution of Ediacaran metazoan ecosystems: A redox perspective

A growing number of detailed geochemical studies of Ediacaran (635-541 Ma) marine successions have provided snapshots into the redox environments that played host to the earliest known metazoans. Whilst previous compilations have focused on the global evolution of Ediacaran water column redox chemistry, the inherent heterogeneity evident in palaeogeographically distinct environments demands a more dissected approach to better understand the nature, interactions and evolution of extrinsic controls on the development of early macrobenthic ecosystems. Here, we review available data of local-scale redox conditions within a palaeogeographic and sequence stratigraphic framework, to explore the mechanisms controlling water column redox conditions and their potential impact on the record of metazoans. The openly connected Laurentian margin, North America (632-540 Ma) and Nama basin, Namibia (550-538 Ma), and the variably restricted Yangtze Block, South China (635-520 Ma), show continued redox instability after the first fossil evidence for metazoans. This may support opportunistic benthic colonisation during periods of transient oxygenation amidst episodic upwelling of anoxic waters beneath a very shallow, fluctuating chemocline. The first skeletal metazoans appeared under conditions of continued redox stratification, such as those which characterise the Dengying Formation of the Yangtze Block and the Kuibis Subgroup of the Nama basin. Current data, however, suggests that successful metazoan reef-building demanded more persistent oxia. We propose that cratonic positioning and migration throughout the Ediacaran Period, in combination with gradually increasing dissolved oxygen loading, may have provided a first-order control on redox evolution through regulating circulation mechanisms in the Mirovian Ocean. Some unrestricted lower slope environments from mid-high latitudes benefited from sustained oxygenation via downwelling, whilst transit of isolated cratons towards more equatorial positions stifled pervasive ventilation either through ineffective surface ocean mixing, Ekman-induced upwelling, elevated surface ocean productivity or a combination of these processes.

Intraspecific variation in an Ediacaran skeletal metazoan: Namacalathus from the Nama Group, Namibia

Namacalathus hermanastes is one of the oldest known skeletal metazoans, found in carbonate settings of the terminal Ediacaran (~550-541 million years ago [Ma]). The palaeoecology of this widespread, goblet-shaped, benthic organism is poorly constrained yet critical for understanding the dynamics of the earliest metazoan communities. Analysis of in situ assemblages from the Nama Group, Namibia (~548-541 Ma), shows that Namacalathus exhibited size variation in response to differing water depths, hydrodynamic conditions and substrate types. In low-energy, inner ramp environments, Namacalathus attains the largest average sizes but grew in transient, loosely aggregating, monospecific aggregations attached to microbial mats. In high-energy mid-ramp reefs, Namacalathus spatially segregated into different palaeoecological habitats with distinct size distributions. In outer ramp environments, individuals were small and formed patchy, dense, monospecific aggregations attached to thin microbial mats. Asexual budding is common in all settings. We infer that variations in size distribution in Namacalathus reflect differences in habitat heterogeneity and stability, including the longevity of mechanically stable substrates and oxic conditions. In the Nama Group, long-lived skeletal metazoan communities developed within topographically heterogeneous mid-ramp reefs, which provided diverse mechanically stable microbial substrates in persistently oxic waters, while inner and outer ramp communities were often ephemeral, developing during fleeting episodes of either oxia and/or substrate stability. We conclude that Namacalathus, which forms a component of these communities in the Nama Group, was a generalist that adapted to various palaeoecological habitats within a heterogeneous ecosystem landscape where favourable conditions persisted, and was also able to opportunistically colonise transiently hospitable environments. These early skeletal metazoans colonised previously unoccupied substrates in thrombolitic reefs and other microbial carbonate settings, and while they experienced relatively low levels of interspecific competition, they were nonetheless adapted to the diverse environments and highly dynamic redox conditions present in the terminal Ediacaran.

Dynamic anoxic ferruginous conditions during the end-Permian mass extinction and recovery

The end-Permian mass extinction, ∼252 million years ago, is notable for a complex recovery period of ∼5 Myr. Widespread euxinic (anoxic and sulfidic) oceanic conditions have been proposed as both extinction mechanism and explanation for the protracted recovery period, yet the vertical distribution of anoxia in the water column and its temporal dynamics through this time period are poorly constrained. Here we utilize Fe–S–C systematics integrated with palaeontological observations to reconstruct a complete ocean redox history for the Late Permian to Early Triassic, using multiple sections across a shelf-to-basin transect on the Arabian Margin (Neo-Tethyan Ocean). In contrast to elsewhere, we show that anoxic non-sulfidic (ferruginous), rather than euxinic, conditions were prevalent in the Neo-Tethys. The Arabian Margin record demonstrates the repeated expansion of ferruginous conditions with the distal slope being the focus of anoxia at these times, as well as short-lived episodes of oxia that supported diverse biota.

Oceanic anoxia is invoked for driving the Permo-Triassic Mass Extinction, but the timing, distribution and chemical state are poorly understood. Here, the authors show that fluctuations of anoxic, non-sulfidic (ferruginous) conditions were important for the delayed biotic recovery in the Neo-Tethys.

Ediacaran skeletal metazoan interpreted as a lophophorate

While many skeletal biomineralized genera are described from Ediacaran (635-541 million years ago, Ma) strata, none have been suggested to have an affinity above the Porifera-Cnidaria metazoan grade. Here, we reinterpret the widespread terminal Ediacaran (approx. 550-541 Ma) sessile goblet-shaped Namacalathus as a triploblastic eumetazoan. Namacalathus has a stalked cup with radially symmetrical cross section, multiple lateral lumens and a central opening. We show that the skeleton of Namacalathus is composed of a calcareous foliated ultrastructure displaying regular concordant columnar inflections, with a possible inner organic-rich layer. These features point to an accretionary growth style of the skeleton and an affinity with the Lophotrochozoa, more specifically within the Lophophorata (Brachiopoda and Bryozoa). Additionally, we present evidence for asexual reproduction as expressed by regular budding in a bilateral pattern. The interpretation of Namacalathus as an Ediacaran total group lophophorate is consistent with an early radiation of the Lophophorata, as known early Cambrian representatives were sessile, mostly stalked forms, and in addition, the oldest known calcareous Brachiopoda (early Cambrian Obolellida) and Bryozoa (Ordovician Stenolaemata) possessed foliated ultrastructures.

Regional climate impacts of a possible future grand solar minimum

Any reduction in global mean near-surface temperature due to a future decline in solar activity is likely to be a small fraction of projected anthropogenic warming. However, variability in ultraviolet solar irradiance is linked to modulation of the Arctic and North Atlantic Oscillations, suggesting the potential for larger regional surface climate effects. Here, we explore possible impacts through two experiments designed to bracket uncertainty in ultraviolet irradiance in a scenario in which future solar activity decreases to Maunder Minimum-like conditions by 2050. Both experiments show regional structure in the wintertime response, resembling the North Atlantic Oscillation, with enhanced relative cooling over northern Eurasia and the eastern United States. For a high-end decline in solar ultraviolet irradiance, the impact on winter northern European surface temperatures over the late twenty-first century could be a significant fraction of the difference in climate change between plausible AR5 scenarios of greenhouse gas concentrations.

Ocean acidification and the Permo-Triassic mass extinction

Ocean acidification triggered by Siberian Trap volcanism was a possible kill mechanism for the Permo-Triassic Boundary mass extinction, but direct evidence for an acidification event is lacking. We present a high-resolution seawater pH record across this interval, using boron isotope data combined with a quantitative modeling approach. In the latest Permian, increased ocean alkalinity primed the Earth system with a low level of atmospheric CO2 and a high ocean buffering capacity. The first phase of extinction was coincident with a slow injection of carbon into the atmosphere, and ocean pH remained stable. During the second extinction pulse, however, a rapid and large injection of carbon caused an abrupt acidification event that drove the preferential loss of heavily calcified marine biota.

Circulating TSLP associates with decreased wheezing in non-atopic preschool children: data from the URECA birth cohort

BACKGROUND

Mouse models of atopic march suggest that systemic, skin-derived thymic stromal lymphopoietin (TSLP) mediates progression from eczema to asthma.

OBJECTIVE

We investigated whether circulating TSLP is associated with eczema, allergic sensitization, or recurrent wheezing in young children.

METHODS

A prospective analysis of the relationship between plasma levels of TSLP to allergic sensitization and recurrent wheezing was conducted in the birth cohort from the Urban Environment and Childhood Asthma (URECA) study. Plasma TSLP levels were measured at 1, 2, and 3 years of age and analysed for correlation with clinical parameters in each of the three years. Only those children with consecutive samples for all three years were included in this analysis.

RESULTS

We detected TSLP in 33% of 236 children for whom plasma samples were available for all three years. Overall, a consistently significant association was not found between TSLP and eczema or allergic sensitization. With regard to recurrent wheezing, children with detectable TSLP at one year of age were significantly less likely to experience recurrent wheezing by 3 years compared with those children without detectable TSLP, but this was only seen in children without aeroallergen sensitization at 3 years (P < 0.01).

CONCLUSIONS AND CLINICAL RELEVANCE

Contrary to our expectations, circulating TSLP was not significantly associated with eczema, allergen sensitization, or recurrent wheezing during the first three years of life. Early presence of circulating TSLP was significantly associated with reduced incidence of recurrent wheeze in those children not sensitized to aeroallergen. These findings suggest a possible underlying distinction between pathogenesis of developing atopic vs. non-atopic recurrent wheeze.

Umbilical cord plasma 25-hydroxyvitamin D concentration and immune function at birth: the Urban Environment and Childhood Asthma study

BACKGROUND

Recent studies have reported conflicting data on the association between maternal intake of vitamin D during pregnancy and asthma.

OBJECTIVE

To assess the influence of prenatal vitamin D status on immune function at birth.

METHODS

In an inner-city birth cohort of 568 newborns, 520 of whom had at least one atopic parent, we measured the umbilical cord (UC) plasma concentration of 25-hydroxyvitamin D (25(OH)D) and the cytokine responses of UC blood mononuclear cells (UCMCs) to stimuli including phytohaemagglutinin (PHA), lipopolysaccharide (LPS), and peptidoglycan. In a subset, the UCMC expression of regulatory T cell markers and the suppressive activity of CD4(+) CD25(+) UCMCs were measured. Results The 25th, 50th, and 75th percentiles of UC plasma 25(OH)D level were 15.0, 20.2, and 25.6 ng/mL, respectively. Most cytokine responses of UCMC were not correlated with UC 25(OH)D concentration; however, IFN-γ release after LPS stimulation was weakly positively correlated with UC 25(OH)D concentration (r=0.11, P=0.01). PHA responses were not significantly correlated with 25(OH)D concentration. The UC plasma 25(OH)D concentration was inversely related to the number of CD25(+) (r=-0.20, P=0.06), CD25(Bright) (r=-0.21, P=0.05), and CD25(+) FoxP3 (r=-0.29, P=0.06) cells as a proportion of CD4(+) T cells in UC blood (r=-0.26, P=0.04) but not to the suppressive activity of CD4(+) CD25(+) cells (r=0.17, P=0.22).

CONCLUSION AND CLINICAL RELEVANCE

UC 25(OH)D concentration was not correlated with most UCMC cytokine responses to multiple stimuli. There was a suggestion of a weakly positive correlation with IFN-γ release after LPS stimulation. The proportions of CD25(+) , CD25(Bright) , and CD25(+) FoxP3 cells to total CD4(+) T cells were inversely correlated with UC 25(OH)D concentration. Our findings suggest that higher vitamin D levels at birth may be associated with a lower number of T-regulatory cells. Vitamin D status in utero may influence immune regulation in early life.

Dendritic cell and T cell responses in children with food allergy

BACKGROUND

Food allergy (FA) and eosinophilic oesophagitis (EE) are increasingly common clinical problems. Dendritic cells (DCs) are key regulators of the sensitization and effector phases of allergic immune responses, but their role in these diseases is largely unknown.

OBJECTIVE

To evaluate for alterations in the phenotype and function of DCs in children with IgE-mediated milk allergy or EE compared with their non-affected siblings.

METHODS

Plasmacytoid DCs (pDCs) and myeloid DCs (mDCs) were prepared from peripheral blood of children with milk allergy (FA), EE, and non-affected siblings (CON). Purified pDCs and mDCs were cultured alone or with autologous CD4(+) lymphocytes. Cytokine levels in plasma, or culture supernatants following stimulation, were measured using multiplex array immunoassay. Cell-surface molecule expression was determined by flow cytometry.

RESULTS

DCs from FA subjects produced greater levels of pro-inflammatory cytokines (IL-6, TNF-α), granulocyte macrophage-colony forming factor, and mDC-derived IL-10 compared with controls following allergen exposure. T(H) 2 but not T(H) 1 cytokines were spontaneously produced in DC-CD4(+) T cell co-cultures from children with FA and were not significantly increased after stimulation with milk extract, suggesting an ongoing activation in vivo. This hypothesis was further supported by evidence for elevated IL-5 and IL-13 protein in the plasma of children with both FA and EE. The only significant DC phenotypic differences were: (1) reduced levels of CD80 in EE subjects and (2) FcɛRI expression that correlated with serum IgE levels in both groups of subjects.

CONCLUSION

This study suggests that DCs from children with FA and EE produce more pro-inflammatory cytokines, and that their CD4(+) T cells are spontaneously activated to produce T(H) 2 cytokines in the presence of FcɛRI-bearing DCs.

Lapses in a prefrontal-extrastriate preparatory attention network predict mistakes

Mistakes are common to all forms of behavior but there is disagreement about what causes errors. We recorded electrophysiological and behavioral measures in a letter discrimination task to examine whether deficits in preparatory attention predicted subsequent response errors. Error trials were characterized by decreased frontal-central preparatory attention event-related potentials (ERPs) prior to stimulus presentation and decreased extrastriate sensory ERPs during visual processing. These findings indicate that transient lapses in a prefrontal-extrastriate preparatory attention network can lead to response errors.

Extreme events due to human-induced climate change

A recent assessment by the intergovernmental panel on climate change concluded that the Earth's climate would be 2-6 degrees C warmer than in the pre-industrial era by the end of the twenty-first century, due to human-induced increases in greenhouse gases. In the absence of other changes, this would lead to the warmest period on Earth for at least the last 1000 years, and probably the last 100,000 years. The large-scale warming is expected to be accompanied by increased frequency and/or intensity of extreme events, such as heatwaves, heavy rainfall, storms and coastal flooding. There are also several possibilities that this large change could initiate nonlinear climate responses which lead to even more extreme and rapid (on the time-scale of decades) climate change, including the collapse of the ocean 'conveyor belt' circulation, the collapse of major ice sheets or the release of large amounts of methane in high latitudes leading to further global warming. Although these catastrophic events are much more speculative than the direct warming due to increased greenhouse gases, their potential impacts are great and therefore should be included in any risk assessment of the impacts of anthropogenic climate change.

Memory enhancement in healthy older adults using a brain plasticity-based training program: a randomized, controlled study

Normal aging is associated with progressive functional losses in perception, cognition, and memory. Although the root causes of age-related cognitive decline are incompletely understood, psychophysical and neuropsychological evidence suggests that a significant contribution stems from poorer signal-to-noise conditions and down-regulated neuromodulatory system function in older brains. Because the brain retains a lifelong capacity for plasticity and adaptive reorganization, dimensions of negative reorganization should be at least partially reversible through the use of an appropriately designed training program. We report here results from such a training program targeting age-related cognitive decline. Data from a randomized, controlled trial using standardized measures of neuropsychological function as outcomes are presented. Significant improvements in assessments directly related to the training tasks and significant generalization of improvements to nonrelated standardized neuropsychological measures of memory (effect size of 0.25) were documented in the group using the training program. Memory enhancement appeared to be sustained after a 3-month no-contact follow-up period. Matched active control and no-contact control groups showed no significant change in memory function after training or at the 3-month follow-up. This study demonstrates that intensive, plasticity-engaging training can result in an enhancement of cognitive function in normal mature adults.

Global warming and thermohaline circulation stability

The Atlantic thermohaline circulation (THC) plays an important role in global climate. Theoretical and palaeoclimatic evidence points to the possibility of rapid changes in the strength of the THC, including a possible quasi-permanent shutdown. The climatic impacts of such a shutdown would be severe, including a cooling throughout the Northern Hemisphere, which in some regions is greater in magnitude than the changes expected from global warming in the next 50 years. Other climatic impacts would likely include a severe alteration of rainfall patterns in the tropics, the Indian subcontinent and Europe. Modelling the future behaviour of the THC focuses on two key questions. (i) Is a gradual weakening of the THC likely in response to global warming, and if so by how much? (ii) Are there thresholds beyond which rapid or irreversible changes in the THC are likely? Most projections of the response of the THC to increasing concentrations of greenhouse gases suggest a gradual weakening over the twenty-first century. However, there is a wide variation between different models over the size of the weakening. Rapid or irreversible THC shutdown is considered a low-probability (but high-impact) outcome; however, some climate models of intermediate complexity do show the possibility of such events. The question of the future of the THC is beset with conceptual, modelling and observational uncertainties, but some current and planned projects show promise to make substantial progress in tackling these uncertainties in future.

Food-allergic reactions in schools and preschools

BACKGROUND

Food allergies may affect up to 6% of school-aged children.

OBJECTIVES

To conduct a telephone survey to characterize food-allergic reactions in children (defined as those aged 3-19 years in this study) with known food allergies in schools and preschools and to determine mechanisms that are in place to prevent and treat those reactions.

DESIGN

The parents of food-allergic children were contacted by telephone and asked about their child's history of food-allergic reactions in school. The schools the children attended were contacted, and the person responsible for the treatment of allergic reactions completed a telephone survey.

RESULTS

Of 132 children in the study, 58% reported food-allergic reactions in the past 2 years. Eighteen percent experienced 1 or more reactions in school. The offending food was identified in 34 of 41 reactions, milk being the causative food in 11 (32%); peanut in 10 (29%); egg in 6 (18%); tree nuts in 2 (6%); and soy, wheat, celery, mango, or garlic in 1 (3%) each. In 24 reactions (59%), symptoms were limited to the skin; wheezing occurred in 13 (32%), vomiting and/or diarrhea in 4 (10%), and hypotension in 1 (2%). Also, 15 (36%) of the 41 reactions involved 2 or more organ systems, and 6 (15%) were treated with epinephrine. Fourteen percent of the children did not have a physician's orders for treatment, and 16% did not have any medications available. Of the 80 participating schools, 31 (39%) reported at least 1 food-allergic reaction within the past 2 years and 54 (67%) made at least 1 accommodation for children with a food allergy, such as peanut-free tables, a peanut ban from the classroom, or alternative meals.

CONCLUSIONS

It is common for food-allergic children to experience allergic reactions in schools and preschools, with 18% of children having had at least 1 school reaction within the past 2 years. Thirty-six percent of the reactions involved 2 or more organ systems, and 32% involved wheezing. Every effort should be made to prevent, recognize, and appropriately treat food-allergic reactions in schools.

Cockroach allergen abatement with extermination and sodium hypochlorite cleaning in inner-city homes

BACKGROUND

Although the importance of cockroach allergen in chronic asthma has now been well defined, little progress has been made in the control of cockroach allergen in infested homes.

OBJECTIVE

The objective of this study was to examine the ability of a combination of professional pest extermination and household cleaning using a solution of sodium hypochlorite to reduce cockroach infestation and allergen levels in cockroach infested homes.

METHODS

Seventeen cockroach-infested homes were studied with three homes serving as controls. In the intervention homes, a professional exterminator applied 0.05% abamectin twice at 2-week intervals at study entry and a professional cleaner cleaned the homes before and after the extermination. All washable surfaces were cleaned throughout the study with a solution of 0.5% hypochlorite. Monthly home visits were conducted to inspect the home, interview the homeowner, place passive cockroach traps, and to collect settled dust samples from the kitchen, bedroom, and TV/living room.

RESULTS

The number of cockroaches in the passive traps decreased rapidly after the initial intervention in most homes. Median Blatella germanica allergen 1 levels in the settled dust samples fell by 91% in the kitchen, 78% in the bedroom, and 77% in the living room over the course of the study in the intervention homes but gradually rose in the control homes. The overall reductions were very similar to those seen in a previous study with a similar protocol except for the use of the sodium hypochlorite.

CONCLUSIONS

Successful extermination is possible in most inner-city homes and cockroach allergen levels can be reduced by 80% to 90%. However, 0.5% sodium hypochlorite did not seem to improve allergen reduction, and in many homes, allergen levels remained above the proposed threshold of 8 U/g of dust throughout the study.

Laboratory animal allergens

Allergic sensitivity to laboratory animals can pose a significant occupational hazard to anyone with regular animal contact. Reactions to mice and rats are most common although all furred animals produce allergens that can lead to sensitization and disease. Most of the relevant allergens of laboratory animals have been defined and characterized, which has revealed that these allergens are typically small, acidic glycoproteins and that many of them are members of a superfamily of extracellular proteins called lipocalins. In addition to understanding their molecular characteristics, the identification of these allergens has also made it possible to measure their distribution in laboratory environments and to relate exposure levels to sensitization and symptoms. These studies have shown that the major laboratory animal allergens are carried on small particles that are both capable of remaining airborne for extended periods and penetrating into the lower airways of exposed workers. These advances in the understanding of these important occupational allergens will allow for the development of better methods of diagnosis and avoidance for affected workers and others who may be at risk for future difficulties.

The role and remediation of animal allergens in allergic diseases

Animal allergens are common causes of both acute and chronic allergic disease. The most important animal allergens are derived from mammals, principally cats, dogs, rats, mice, horses, and cows, which secrete or excrete allergens into the environment. Allergic sensitization may occur at home or in the workplace. Cat and dog allergens commonly cause allergies in the home and affect the general population. Laboratory animal handlers often have allergic reactions to rats and mice. Cow dander allergy is usually caused by occupational exposure and occurs in farmers and farm workers. Horse allergy occurs among people who regularly handle horses, either professionally or for recreational purposes. Over the past 20 years, the major animal allergens have been defined and characterized with regard to their molecular structure, immunogenicity, and environmental distribution. One remarkable finding has been the fact that most of the mammalian allergens that have thus far been cloned belong to a single family of proteins called the lipocalins. In addition to these molecular similarities, it has also been shown that most of the animal allergens are quite similar with regard to their aerodynamic properties. Although much is yet to be learned, progress is being made in our knowledge regarding the steps that may be necessary to control exposure to these allergens through environmental modifications in both homes and occupational settings. These measures include source control, air filtration devices, barrier devices, removal of carpeting and other reservoirs, and, in some cases, washing of the animal.

The natural history of peanut allergy

BACKGROUND

It has traditionally been assumed that peanut allergy is rarely outgrown.

OBJECTIVE

The goal of this study was to determine the number of children with peanut allergy who become tolerant of peanut.

METHODS

Patients aged 4 to 20 years with a diagnosis of peanut allergy were evaluated by questionnaire, skin testing, and a quantitative antibody fluorescent-enzyme immunoassay. Patients who had been reaction free in the past year and had a peanut IgE (PN-IgE) level less than 20 kilounits of antibody per liter (kU(A)/L) were offered an open or double-blind, placebo-controlled peanut challenge.

RESULTS

A total of 223 patients were evaluated, and of those, 85 (PN-IgE < 0.35-20.4 kU(A)/L [median 1.42 kU(A)/L]) participated in an oral peanut challenge. Forty-eight (21.5%) patients had negative challenge results and were believed to have outgrown their peanut allergy (aged 4-17.5 years [median 6 years]; PN-IgE < 0.35-20.4 kU(A)/L [median 0.69 kU(A)/L]). Thirty-seven failed the challenge (aged 4-13 years [median 6.5 years]; RAST < 0.35-18.2 kU(A)/L [median 2.06 kU(A)/L]). Forty-one patients with PN-IgE levels less than 20 kU(A)/L declined to undergo challenge, and 97 were not eligible for challenge because their PN-IgE levels were greater than 20 kU(A)/L or they had had a recent reaction. Sixty-seven percent of patients with PN-IgE levels less than 2 kU(A)/L and 61% with levels less than 5 kU(A)/L had negative challenge results. Of those who underwent challenge, PN-IgE levels for those who passed versus those who failed were different at the time of challenge (P = .009), but not at the time of diagnosis (P = .25).

CONCLUSION

This study demonstrates that peanut allergy is outgrown in about 21.5% of patients. Patients with low PN-IgE levels should be offered a peanut challenge in a medical setting to demonstrate whether they can now tolerate peanuts.

Mouse allergen. I. The prevalence of mouse allergen in inner-city homes. The National Cooperative Inner-City Asthma Study

BACKGROUND

Although mouse allergen is a well-defined cause of IgE-mediated hypersensitivity in occupational settings, it has not been well studied in the general population.

OBJECTIVE

We sought to determine the prevalence of mouse allergen in inner-city homes.

METHODS

A subset of 608 homes from the National Cooperative Inner-City Asthma Study population had dust samples adequate for analysis of mouse allergen. In addition, data regarding the demographics and housing of the subjects were related to the mouse allergen levels.

RESULTS

Ninety-five percent of all homes had detectable mouse allergen (Mus m 1) in at least one room, with the highest levels found in kitchens (kitchen: range, 0-618 microg/g; median, 1.60 microg/g; bedroom: range, 0-294 microg/g; median, 0.52 microg/g; television-living room: range, 0-203 microg/g; median, 0. 57 microg/g). By city, 100% of the kitchens in Baltimore had detectable mouse allergen, with the lowest percentage (74%) in Cleveland. Mouse allergen levels correlated among rooms (R = 0.65-0. 75). Forty-nine percent of the homes had reported problems with mice within the last year, and 29% of the homes had evidence of mice in one or more rooms on home inspection and had higher levels of mouse allergen (P =.0001). Higher allergen levels were also associated with evidence of cockroach infestation in any room (P =.006). None of the other subject or housing demographics evaluated were associated with a higher prevalence or level of mouse allergen.

CONCLUSIONS

We conclude that mouse allergen is widely distributed in inner-city homes and that cockroach infestation is associated with high mouse allergen levels.

Mouse allergen. II. The relationship of mouse allergen exposure to mouse sensitization and asthma morbidity in inner-city children with asthma

BACKGROUND

Although mouse allergen is known to cause occupational asthma in laboratory workers, its potential significance in home environments has never been studied.

OBJECTIVE

This study was designed to define the prevalence of mouse sensitivity and its relationship to mouse allergen exposure and disease activity in inner-city children with asthma.

METHODS

A subset of 499 subjects from the National Cooperative Inner-City Asthma Study had dust samples adequate for mouse allergen analysis, as well as valid puncture skin test (PST) results. Data were analyzed to relate mouse allergen exposure and other risk factors to mouse sensitization and asthma morbidity.

RESULTS

Eighty-nine (18%) of the 499 children had a positive mouse skin test response. Children whose homes had mouse allergen levels above the median (1.60 microg/g) in the kitchen had a significantly higher rate of mouse sensitization (23% vs 11%, P =. 007). Atopy was also significantly related to mouse sensitization, with 40% of those with more than 4 positive PST responses having mouse sensitivity compared with 4% of those with no other positive PST responses (P <.0001). When atopy and exposure were considered together, 53% of those with more than 4 positive PST responses and allergen levels above the median had a positive PST response to mouse allergen compared with 22% of those with more than 4 positive PST responses and allergen levels below the median (P <.0001). The relationship among mouse allergen exposure, sensitization, and any measures of asthma morbidity was not statistically significant.

CONCLUSIONS

Mouse allergen may be an important indoor allergen in inner-city children with asthma, with exposure and atopy contributing to mouse sensitization.

Quantitative IgE antibody assays in allergic diseases

During the past several years, immunoassays for specific IgE antibodies have been refined to permit reporting results in mass units. Thus quantitative immunoassays for IgE antibodies may be an adjunct to skin tests. In cases of food allergy among children with atopic dermatitis, cutoff values for IgE antibody concentrations to egg, milk, peanut, and fish have been derived to provide 95% positive and 90% negative predictive values. Food-specific IgE antibody determinations can also be used to predict which food allergies are resolving spontaneously. Elevated egg-specific IgE antibody levels in infancy are associated with significantly increased risk for development of inhalant allergies later in childhood. In cases of inhalant allergy, specific IgE antibody levels correlate closely with results of inhalation challenge studies in cat-sensitive persons. Also, mite-specific IgE antibody levels correlate significantly with the mite allergen contents of reservoir dust in the homes of mite-sensitive persons. Immunoassays for quantitation of specific IgE antibodies may be used to document allergen sensitization over time and to evaluate the risk of reaction on allergen exposure. However, immunoassays and skin tests are not entirely interchangeable, and neither will replace the other in appropriate circumstances.

A randomized, double-blind, placebo-controlled trial of the effect of zafirlukast on upper and lower respiratory responses to cat challenge

BACKGROUND

Zafirlukast, a leukotriene antagonist, has been shown to have protective effects against a variety of asthma triggers.

OBJECTIVE

Our purpose was to evaluate zafirlukast's effects on upper and lower airway responses to cat allergen exposure with use of a well-characterized cat exposure model.

METHODS

In a double-blind, placebo-controlled, cross-over trial 18 subjects with cat-induced asthma were randomly assigned to receive 1 week each of zafirlukast or placebo followed by a 1-hour cat challenge. Upper and lower respiratory symptoms were rated and spirometry and acoustic rhinometry were performed. Challenges were stopped early if the subject was too uncomfortable or had a >50% decrease in FEV(1).

RESULTS

Overall changes in FEV(1) were significantly different with zafirlukast treatment (P = .02). Significant differences in FEV(1) change were detected at 15 and 30 minutes (P = .027 and .05, respectively) but not at 45 and 60 minutes. Changes in acoustic rhinometry were also significantly different at 15 and 30 minutes (P =.05 and .0005, respectively) but not at 45 and 60 minutes. Challenge length was significantly longer with zafirlukast versus placebo after adjustment for differences in allergen exposure (P = .022). Respiratory symptom scores were significantly different (lower respiratory, P < .001; upper respiratory, P = .038) through the first 30 minutes of the challenge after adjustment for allergen exposure.

CONCLUSIONS

Zafirlukast was significantly more effective than placebo in preserving pulmonary function and nasal anatomy and extending challenge length when cat-sensitive asthmatic subjects were exposed to high levels of cat allergen.

Detection of growth suppression in children during treatment with intranasal beclomethasone dipropionate

OBJECTIVE

Intranasal beclomethasone dipropionate (BDP) has generally been considered to have no systemic activity at recommended doses, but the potential for long-term effects on growth has not previously been evaluated. This study was undertaken to assess the effects of 1 year of treatment with intranasal BDP on growth in children.

STUDY DESIGN

In this double-blind, randomized, parallel-group study, 100 prepubertal children 6 to 9 years old with perennial allergic rhinitis were treated with aqueous BDP 168 microg twice daily (n = 51) or placebo (n = 49) for 1 year. Subjects' baseline heights were required to be between the 5th and 95th percentile, and skeletal age as determined by left wrist radiograph was required to be within 2 years of chronological age. Washout periods for medications known to affect growth, including other forms of corticosteroids, were established, and these medications were prohibited during the study. However, short courses of oral prednisolone lasting no more than 7 days, and short courses of dermatologic corticosteroids lasting no more than 10 days, were allowed. Height was measured with a stadiometer after 1, 2, 4, 6, 8, 10, and 12 months of treatment. The hypothalamic-pituitary-adrenocortical axis was assessed by measurements of 8 AM basal cortisol concentrations and response to. 25 mg cosyntropin stimulation. The primary safety parameter was the rate of change in standing height. Statistical analyses were based on all randomized subjects who received at least 1 dose of medication (intent-to-treat principle). The rate of change in standing height was analyzed for all subjects who entered the study and for those completing the full 12 months of treatment (n = 80). The rate of change in standing height over the 1-year study was calculated as the slope of a linear regression line fitted to each subject's height measurements over time. Because there was a statistically significant between-group difference in standing height at baseline, an analysis of covariance was performed for all analyses of standing height data.

RESULTS

Of the 100 subjects enrolled, 90 completed the study. The 2 treatment groups were generally comparable at baseline; however, at baseline, mean age and mean height were significantly greater in the BDP treatment group that the in placebo treatment group. In both analyses, overall growth rate was significantly slower in BDP-treated subjects than placebo-treated subjects. The mean change in standing height after 1 year was 5.0 cm in the BDP-treated subjects compared with 5.9 cm in the placebo-treated subjects. The difference in growth rates was evident as early as the 1-month treatment visit, suggesting that the effect on growth occurred initially. The growth-suppressive effect of BDP remained consistent across all age and gender subgroups, and among subjects with and without a previous history of corticosteroid use. Use of additional exogenous corticosteroids during the study was similar in both groups and did not affect the results. Because there was a baseline imbalance in height, a supplemental analysis of the differences in prestudy growth rates was performed. This analysis found no baseline imbalance in prestudy growth rates. To determine whether the difference in growth rates during the study could be attributed to preexisting growth rates, a z score analysis was performed. The heights of both groups were normalized at baseline and at the end of the study using the US National Center for Health Statistics data for mean and standard deviations of height. This analysis confirmed that the difference in growth rates between the 2 groups was primarily attributable to the treatment rather than to any preexisting difference in growth. Additional analyses confirmed that the results were not influenced by outlier values. No significant between-group difference were found in the hypothalamic-pituitary-adrenocortical axis assessments. No unusual adverse events were observed. (ABSTRACT

Removal of cockroach allergen from inner-city homes

BACKGROUND

Allergen avoidance has been shown to improve the morbidity and physiology of asthma. Although cockroach allergen has been implicated in chronic asthma, little work has been reported on the feasibility of allergen removal from infested homes.

OBJECTIVE

The objective of this study was to examine the effect of professional pest control and home cleaning on cockroach infestation and allergen concentrations in settled dust samples from the kitchens, bedrooms, and television-living rooms of inner-city homes.

METHODS

Thirteen homes in inner-city Baltimore, Maryland, received a professional cleaning, with vacuuming and a thorough cleaning in the kitchen. Pest control technicians applied abamectin 0.05% gel to the kitchen and, to a limited extent, to the rest of the home and the cleaning was repeated. Technicians visited monthly from month 2 to month 8 to inspect, collect dust samples, and place passive cockroach traps. Bla g 1 concentrations in dust extract were measured by means of ELISA.

RESULTS

The number of cockroaches captured in passive traps decreased rapidly in 11 homes, but complete extermination was achieved in only 7 homes. Bla g 1 concentrations were reduced by 93% in kitchens, 77% in television-living rooms, and 74% in bedrooms. The relative reduction in cockroach allergen was not related to successful extermination or to signs of poor house-cleaning.

CONCLUSION

We concluded that cockroach extermination is feasible in inner-city homes but that standard house-cleaning procedures are only partially effective in removing residual allergen over 8 months.