Palms of the past: can morphometric phytolith analysis inform deep time evolution and palaeoecology of Arecaceae?

BACKGROUND AND AIMS: Palm fossils are often used as evidence for warm and wet palaeoenvironments, reflecting the affinities of most modern palms. However, several extant palm lineages tolerate cool and/or arid climates, making a clear understanding of the taxonomic composition of ancient palm communities important for reliable palaeoenvironmental inference. However, taxonomically identifiable palm fossils are rare and often confined to specific facies. Although the resolution of taxonomic information they provide remains unclear, phytoliths (microscopic silica bodies) provide a possible solution because of their high preservation potential under conditions where other plant fossils are scarce. We thus evaluate the taxonomic and palaeoenvironmental utility of palm phytoliths. METHODS: We quantified phytolith morphology of 97 modern palm and other monocot species. Using this dataset, we tested the ability of five common discriminant methods to identify nine major palm clades. We then compiled a dataset of species' climate preferences and tested if they were correlated with phytolith morphology using a phylogenetic comparative approach. Finally, we reconstructed palm communities and palaeoenvironmental conditions at six fossil sites. KEY RESULTS: Best-performing models correctly identified phytoliths to their clade of origin only 59 % of the time. Although palms were generally distinguished from non-palms, few palm clades were highly distinct, and phytolith morphology was weakly correlated with species' environmental preferences. Reconstructions at all fossil sites suggested that palm communities were dominated by Trachycarpeae and Areceae, with warm, equable climates and high, potentially seasonal rainfall. However, fossil site reconstructions had high uncertainty and often conflicted with other climate proxies. CONCLUSIONS: While phytolith morphology provides some distinction among palm clades, caution is warranted. Unlike prior spatially restricted studies, our geographically and phylogenetically broad study indicates phytolith morphology may not reliably differentiate most palm taxa in deep time. Nevertheless, it reveals distinct clades, including some likely to be palaeoenvironmentally informative.

Soil Bacterial Assemblage Across a Production Landscape: Agriculture Increases Diversity While Revegetation Recovers Community Composition.

Aboveground ecological impacts associated with agricultural land use change are evident as natural plant communities are replaced with managed production systems. These impacts have been extensively studied, unlike those belowground, which remain poorly understood. Soil bacteria are good candidates to monitor belowground ecological dynamics due to their prevalence within the soil system and ability to survive under harsh and changing conditions. Here, we use soil physicochemical assessment and 16S rRNA gene sequencing to investigate the soil physical and bacterial assemblage changes across a mixed-use agricultural landscape. We assess soil from remnant vegetation (Eucalyptus mallee), new and old vineyards, old pasture, and recently revegetated areas. Elevated concentrations of nitrogen (NO3-) and plant-available (Colwell) phosphorus were identified in the managed vineyard systems, highlighting the impact of agricultural inputs on soil nutrition. Alpha diversity comparison revealed a significant difference between the remnant mallee vegetation and the vineyard systems, with vineyards supporting highest bacterial diversity. Bacterial community composition of recently revegetated areas was similar to remnant vegetation systems, suggesting that bacterial communities can respond quickly to aboveground changes, and that actions taken to restore native plant communities may also act to recover natural microbial communities, with implications for soil and plant health. Findings here suggest that agriculture may disrupt the correlation between above- and belowground diversities by altering the natural processes that otherwise govern this relationship (e.g. disturbance, plant production, diversity of inputs), leading to the promotion of belowground microbial diversity in agricultural systems.

Forensic validation of a SNP and INDEL panel for individualisation of timber from bigleaf maple (Acer macrophyllum Pursch).

Illegal logging is one of the largest illicit trades in the world, with high profits and generally low risks of detection and prosecution. Timber identification presents problems for law enforcement as traditionally used forensic methods such as wood anatomy and dendrochronology are often unable to confidently match wood evidence to the remains of illegally felled trees. Here we have developed and validated a set of genetic markers for individualisation in bigleaf maple (Acer macrophyllum), a high value timber species often felled illegally in the USA. Using 128 single nucleotide polymorphisms and three insertion/deletion markers developed through massively parallel sequencing, 394 individuals were genotyped on the MassARRAY® iPLEX™ platform (Agena Bio-science™, San Diego, USA) to produce a population reference database for the species. We demonstrate that the resulting DNA assay is reliable, species specific, effective at low DNA concentrations (<1 ng/µL) and suitable for application to timber samples. The PID for the most common profile, calculated using an overall dataset level FST-correction factor, was 1.785 × 10-25 and PID-SIB across all individuals (treated as a single population) was 2.496 × 10-22. The further development of forensic identification assays for timber species has the potential to deliver robust tools for improved detection and prosecution of illegal logging crimes as well as for the verification of legality in reputable supply chains.

Association between the age of solid food introduction and eczema: A systematic review and a meta-analysis.

INTRODUCTION: Eczema is a common childhood ailment responsible for a considerable disease burden. Both timing of introduction to solid food and allergenic food are believed to be related to childhood eczema. Despite the growing body of evidence, the relationship between timing of any solid food introduction (allergenic and/or non-allergenic) and development of eczema has not previously been systematically reviewed. METHODS: PubMed and EMBASE databases were searched using food and eczema terms. Two authors selected papers according to the inclusion criteria and extracted information on study characteristics and measures of association. Meta-analyses were performed after grouping studies according to the age and type of exposure. RESULTS: A total of 17 papers met the inclusion criteria, reporting results from 16 study populations. Of these, 11 were cohort studies, 2 case-controls, 1 cross-sectional study and 2 randomized controlled trials. Limited meta-analyses were performed due to heterogeneity between studies. Timing of solid food introduction was not associated with eczema. One randomized controlled trial provided weak evidence of an association between early allergenic (around 4 months) food introduction and reduced risk of eczema. CONCLUSIONS: The available evidence is currently insufficient to determine whether the timing of introduction of any solid food influences the risk of eczema.

Grandmaternal smoking increases asthma risk in grandchildren: A nationwide Swedish cohort.

BACKGROUND: There is growing interest in exposures prior to conception as possible risk factors for offspring asthma. Although partially supported by evidence from limited human studies, current evidence is inconsistent and based on recall of exposure status. OBJECTIVE: We aimed to investigate grandmaternal smoking during pregnancy and the risk of asthma in grandchildren using prospectively collected population-based data. METHODS: Information on grandmaternal and maternal smoking during pregnancy and grandchild use of asthma medications was collected from national Swedish registries. Associations between grandmaternal smoking during pregnancy (10-12 weeks) and asthma medication use in grandchildren were investigated using generalized estimating equations. Ages at which asthma medications were prescribed classified childhood asthma into never, early transient (0-3 years), late onset (3-6 years) and early persistent (0-3 and 3-6 years) phenotypes. RESULTS: From 1982 to 1986, 44 583 grandmothers gave birth to 46 197 mothers, who gave birth to 66 271 grandchildren (born 1996-2010). Children aged 1-6 years had an increased asthma risk if their grandmothers had smoked during pregnancy, with a higher risk for more exposure (10+ cigs/d; adjusted OR 1.23; 1.17, 1.30). Maternal smoking did not modify this relationship. CONCLUSIONS & CLINICAL RELEVANCE: Children had an increased risk of asthma in the first 6 years of life if their grandmothers smoked during early pregnancy, independent of maternal smoking. Importantly, this exhibited a dose-response relationship and was associated with a persistent childhood asthma phenotype. These findings support possible epigenetic transmission of risk from environmental exposures in previous generations.

Association of breast milk fatty acids with allergic disease outcomes-A systematic review.

INTRODUCTION: Dietary polyunsaturated fatty acids (PUFAs) have immunoregulatory properties. Breast milk is rich in PUFA, and it has been hypothesized that these PUFAs may be important in the aetiology of allergic diseases. Despite a growing body of evidence, the associations between breast milk PUFA and allergic disease have not previously been systematically reviewed. METHODS: The search was performed in PubMed and EMBASE databases using breastfeeding, fatty acid and allergic disease terms. Two authors were involved in selecting papers for review according to the inclusion criteria and extracting information on study characteristics and measures of association. Only studies that reported numeric associations between concentration of breast milk fatty acids and allergic disease outcomes were included. RESULTS: A total of 18 papers met the inclusion criteria, reporting results from 15 study populations. The majority were cohort studies (n=11), with data from only two case-control and two cross-sectional studies. Sample size varied between 30 and 352 participants, and follow-up time of the cohorts varied between 3 months and 14 years. Nine studies reported on eczema, seven reported on sensitization, and only five reported on asthma/wheeze. There was heterogeneity among studies in terms of presenting the association between PUFA and allergy; therefore, estimates could not be pooled. Only a few studies observed associations between n-3 and n-6 PUFAs and allergic disease, and the magnitude of this effect varied greatly. CONCLUSIONS: There is insufficient evidence to suggest that colostrum or breast milk polyunsaturated fatty acids influence the risk of childhood allergic diseases.

Determining Effects of Superfine Sheep wool in INfantile Eczema (DESSINE): a randomized paediatric crossover study.

BACKGROUND: Despite limited evidence, woollen clothing has traditionally been considered to be an irritant that should be avoided by individuals with atopic dermatitis (AD). Wool fibres come in a range of diameters, and have beneficial thermodynamic and moisture transport properties. OBJECTIVES: This study examines the effects of superfine merino wool on symptoms in participants with mild-to-moderate AD. METHODS: The trial was a 12-week, randomized, assessor-blinded, crossover, prospective, cohort study of 39 patients with mild-to-moderate AD, aged between 4 weeks and 3 years, comparing superfine merino wool ensembles with standard cotton clothing chosen by parents. Participants were assigned to wool or cotton clothing and assessed every 3 weeks for 6 weeks, before crossing over to wear the other clothing material for a further 6-week period, with similar 3-weekly reviews. The primary end point was the SCORing Atopic Dermatitis (SCORAD) index after each 6-week period, with Atopic Dermatitis Severity Index (ADSI), Infants' Dermatitis Quality Of Life Index (IDQOL) and topical steroid use as secondary end points to measure AD severity and quality of life. RESULTS: Overall, compared with baseline, superfine wool ensembles were associated with a reduction in mean SCORAD of 2·5 [95% confidence interval (CI) -4·7 to -0·4] at 3 weeks and 7·6 (95% CI -10·4 to -4·8) at 6 weeks when compared with the cotton ensembles. A similar change was observed in ADSI and IDQOL scores for the same period. Body steroid use was also reduced. Conversely, changing ensembles from wool to cotton resulted in an increase in scores. CONCLUSIONS: Superfine merino wool may assist in the management of childhood AD.

Breast milk polyunsaturated fatty acids: associations with adolescent allergic disease and lung function.

BACKGROUND: It has been hypothesized that n-3 PUFA in breast milk may assist immune and lung development. There are very limited data on possible long-term effects on allergic disease and lung function. The aim was to investigate associations of n-3 and n-6 PUFA levels in colostrum and breast milk with allergic disease and lung function at ages 12 and 18 years. METHODS: Polyunsaturated fatty acids were measured in 194 colostrum samples and in 118 three-month expressed breast milk samples from mothers of children enrolled in the Melbourne Atopy Cohort (MACS) Study, a high-risk birth cohort study. Associations with allergic diseases, skin prick tests and lung function assessed at 12 and 18 years were estimated using multivariable regression. RESULTS: Higher levels of n-3 but not n-6 PUFAs in colostrum were associated with a trend towards increased odds of allergic diseases, with strong associations observed for allergic rhinitis at 12 (OR = 5.69[95% CI: 1.83,17.60] per weight%) and 18 years (4.43[1.46,13.39]) and eczema at 18 years (9.89[1.44, 68.49]). Higher levels of colostrum n-3 PUFAs were associated with reduced sensitization (3.37[1.18, 9.6]), mean FEV1 (-166 ml [-332, -1]) and FEV1 /FVC ratio (-4.6%, [-8.1, -1.1]) at 12 years. CONCLUSION: Higher levels of colostrum n-3 PUFAs were associated with increased risks of allergic rhinitis and eczema up to 18 years, and sensitization and reduced lung function at 12 years. As residual confounding may have caused these associations, they should be replicated, but these results could indicate that strategies that increase maternal n-3 PUFA intake may not aid in allergic disease prevention.

The effects of growing up on a farm on adult lung function and allergic phenotypes: an international population-based study.

RATIONALE: Evidence has suggested that exposure to environmental or microbial biodiversity in early life may impact subsequent lung function and allergic disease risk. OBJECTIVES: To investigate the influence of childhood living environment and biodiversity indicators on atopy, asthma and lung function in adulthood. METHODS AND MEASUREMENTS: The European Community Respiratory Health Survey II investigated ∼10 201 participants aged 26-54 years from 14 countries, including participants' place of upbringing (farm, rural environment or inner city) before age 5 years. A 'biodiversity score' was created based on childhood exposure to cats, dogs, day care, bedroom sharing and older siblings. Associations with lung function, bronchial hyper-responsiveness (BHR), allergic sensitisation, asthma and rhinitis were analysed. MAIN RESULTS: As compared with a city upbringing, those with early-life farm exposure had less atopic sensitisation (adjusted OR 0.46, 95% CI 0.37 to 0.58), atopic BHR (0.54 (0.35 to 0.83)), atopic asthma (0.47 (0.28 to 0.81)) and atopic rhinitis (0.43 (0.32 to 0.57)), but not non-atopic outcomes. Less pronounced protective effects were observed for rural environment exposures. Women with a farm upbringing had higher FEV1 (adjusted difference 110 mL (64 to 157)), independent of sensitisation and asthma. In an inner city environment, a higher biodiversity score was related to less allergic sensitisation. CONCLUSIONS: This is the first study to report beneficial effects of growing up on a farm on adult FEV1. Our study confirmed the beneficial effects of early farm life on sensitisation, asthma and rhinitis, and found a similar association for BHR. In persons with an urban upbringing, a higher biodiversity score predicted less allergic sensitisation, but to a lesser magnitude than a childhood farm environment.

Relationships between adult asthma and oxidative stress markers and pH in exhaled breath condensate: a systematic review.

Oxidative stress has a recognized role in the pathophysiology of asthma. Recently, interest has increased in the assessment of pH and airway oxidative stress markers. Collection of exhaled breath condensate (EBC) and quantification of biomarkers in breath samples can potentially indicate lung disease activity and help in the study of airway inflammation, and asthma severity. Levels of oxidative stress markers in the EBC have been systematically evaluated in children with asthma; however, there is no such systematic review conducted for adult asthma. A systematic review of oxidative stress markers measured in EBC of adult asthma was conducted, and studies were identified by searching MEDLINE and SCOPUS databases. Sixteen papers met the inclusion criteria. Concentrations of exhaled hydrogen ions, nitric oxide products, hydrogen peroxide and 8-isoprostanes were generally elevated and related to lower lung function tests in adults with asthma compared to healthy subjects. Assessment of EBC markers may be a noninvasive approach to evaluate airway inflammation, exacerbations, and disease severity of asthma, and to monitor the effectiveness of anti-inflammatory treatment regimens. Longitudinal studies, using standardized analytical techniques for EBC collection, are required to establish reference values for the interpretation of EBC markers in the context of asthma.

The march from early life food sensitization to allergic disease: a systematic review and meta-analyses of birth cohort studies.

BACKGROUND: There is growing evidence for an increase in food allergies. The question of whether early life food sensitization, a primary step in food allergies, leads to other allergic disease is a controversial but important issue. Birth cohorts are an ideal design to answer this question. OBJECTIVES: We aimed to systematically investigate and meta-analyse the evidence for associations between early food sensitization and allergic disease in birth cohorts. METHODS: MEDLINE and SCOPUS databases were searched for birth cohorts that have investigated the association between food sensitization in the first 2 years and subsequent wheeze/asthma, eczema and/or allergic rhinitis. We performed meta-analyses using random-effects models to obtain pooled estimates, stratified by age group. RESULTS: The search yielded fifteen original articles representing thirteen cohorts. Early life food sensitization was associated with an increased risk of infantile eczema, childhood wheeze/asthma, eczema and allergic rhinitis and young adult asthma. Meta-analyses demonstrated that early life food sensitization is related to an increased risk of wheeze/asthma (pooled OR 2.9; 95% CI 2.0-4.0), eczema (pooled OR 2.7; 95% CI 1.7-4.4) and allergic rhinitis (pooled OR 3.1; 95% CI 1.9-4.9) from 4 to 8 years. CONCLUSION: Food sensitization in the first 2 years of life can identify children at high risk of subsequent allergic disease who may benefit from early life preventive strategies. However, due to potential residual confounding in the majority of studies combined with lack of follow-up into adolescence and adulthood, further research is needed.

Timing of routine infant vaccinations and risk of food allergy and eczema at one year of age.

BACKGROUND: Epidemiological evidence suggests that routine vaccinations can have nontargeted effects on susceptibility to infections and allergic disease. Such effects may depend on age at vaccination, and a delay in pertussis vaccination has been linked to reduced risk of allergic disease. We aimed to test the hypothesis that delay in vaccines containing diphtheria-tetanus-acellular pertussis (DTaP) is associated with reduced risk of food allergy and other allergic diseases. METHODS: HealthNuts is a population-based cohort in Melbourne, Australia. Twelve-month-old infants were skin prick-tested to common food allergens, and sensitized infants were offered oral food challenges to determine food allergy status. In this data linkage study, vaccination data for children in the HealthNuts cohort were obtained from the Australian Childhood Immunisation Register. Associations were examined between age at the first dose of DTaP and allergic disease. RESULTS: Of 4433 children, 109 (2.5%) received the first dose of DTaP one month late (delayed DTaP). Overall, delayed DTaP was not associated with primary outcomes of food allergy (adjusted odds ratio (aOR) 0.77; 95% CI: 0.36-1.62, P = 0.49) or atopic sensitization (aOR: 0.66; 95% CI: 0.35-1.24, P = 0.19). Amongst secondary outcomes, delayed DTaP was associated with reduced eczema (aOR: 0.57; 95% CI: 0.34-0.97, P = 0.04) and reduced use of eczema medication (aOR: 0.45; 95% CI: 0.24-0.83, P = 0.01). CONCLUSIONS: There was no overall association between delayed DTaP and food allergy; however, children with delayed DTaP had less eczema and less use of eczema medication. Timing of routine infant immunizations may affect susceptibility to allergic disease.

Breastfeeding and asthma and allergies: a systematic review and meta-analysis.

AIM: To systematically review the association between breastfeeding and childhood allergic disease. METHODS: Predetermined inclusion/exclusion criteria identified 89 articles from PubMed, CINAHL and EMBASE databases. Meta-analyses performed for categories of breastfeeding and allergic outcomes. Meta-regression explored heterogeneity. RESULTS: More vs. less breastfeeding (duration) was associated with reduced risk of asthma for children (5-18 years), particularly in medium-/low-income countries and with reduced risk of allergic rhinitis ≤5 years, but this estimate had high heterogeneity and low quality. Exclusive breastfeeding for 3-4 months was associated with reduced risk of eczema ≤2 years (estimate principally from cross-sectional studies of low methodological quality). No association found between breastfeeding and food allergy (estimate had high heterogeneity and low quality). Meta-regression found differences between study outcomes may be attributable to length of breastfeeding recall, study design, country income and date of study inception. Some of the protective effect of breastfeeding for asthma may be related to recall bias in studies of lesser methodological quality. CONCLUSION: There is some evidence that breastfeeding is protective for asthma (5-18 years). There is weaker evidence for a protective effect for eczema ≤2 years and allergic rhinitis ≤5 years of age, with greater protection for asthma and eczema in low-income countries.

The role of circulating 25 hydroxyvitamin D in asthma: a systematic review.

Asthma is a major public health issue. The co-occurrence of the high prevalence of asthma and vitamin D deficiency documented globally in recent decades has prompted several investigations into a possible association between the two conditions. The objective of this paper was to synthesize the evidence from studies that have measured the association between serum vitamin D and asthma incidence, prevalence, severity and exacerbations. A systematic search of the literature was performed in PubMed, and the available evidence was summarized both qualitatively and by meta-analysis. Only English language, observational studies measuring serum levels of 25(OH)D as the exposure were included, as this is the most robust measure of vitamin D levels. The search identified 23 manuscripts: two case-control, 12 cohort and nine cross-sectional studies. Collectively, the evidence suggests that higher serum levels of 25(OH)D are associated with a reduced risk of asthma exacerbations, but there was little evidence to suggest an association with asthma incidence, prevalence or severity. A significant amount of heterogeneity between study methodology and results restricted the scope for meta-analysis. These results suggest that vitamin D supplementation may be effective for the prevention of asthma exacerbations, but the findings need to be confirmed by clinical trials.

Paracetamol exposure in pregnancy and early childhood and development of childhood asthma: a systematic review and meta-analysis.

BACKGROUND AND OBJECTIVE: While paracetamol exposure in pregnancy and early infancy has been associated with asthma, it remains unclear whether this is confounded by respiratory tract infections, which have been suggested as an alternative explanation. We undertook a systematic review and meta-analysis of longitudinal studies that reported the association between paracetamol exposure during pregnancy or infancy and the subsequent development of childhood asthma (≥5 years). METHODS: Two independent researchers searched the databases EMBASE and PUBMED on 12 August 2013 for relevant articles using predefined inclusion and exclusion criteria. Study quality was assessed and results were pooled using fixed effect models or random effect models when moderate between-study heterogeneity was observed. We explicitly assessed whether the observed associations are due to confounding by respiratory tract infections. RESULTS: Eleven observational cohort studies met the inclusion criteria. Any paracetamol use during the first trimester was related to increased risk of childhood asthma (5 studies, pooled OR=1.39, 95% CI 1.01 to 1.91) but there was marked between-study heterogeneity (I(2)=63%) and only one of these studies adjusted for maternal respiratory tract infections. Increasing frequency of use of paracetamol during infancy was associated with increased odds of childhood asthma (3 studies, pooled OR=1.15, 95% CI 1.00 to 1.31 per doubling of days exposure), but in these same three studies adjusting for respiratory tract infections reduced this association (OR=1.06, 95% CI 0.92 to 1.22). DISCUSSION: The association during early pregnancy exposure was highly variable between studies and exposure during infancy appears to be moderately confounded by respiratory tract infections. There is insufficient evidence to warrant changing guidelines on early life paracetamol exposure at this time.