Marital coitus across the life course

It remains unclear whether the frequency of marital coitus does in fact decline universally across the life course, what shape that decay normally takes, and what best accounts for it: increasing marriage duration, women's age or age of their partners. Using cross-sectional Demographic and Health Survey (DHS) data of 91,744 non-abstaining women in their first marriage, a generalized linear model is used to determine if there is a consistent pattern in the life course pattern of degradation in the frequency of marital coitus. Datasets were drawn from nineteen countries in Asia, Africa and the Americas. Use of very large samples allows proper disentangling of the effects of women's age, husband's age and marital duration, and use of samples from multiple countries allows consideration of the influence of varied prevailing fertility regimes and fertility-related practices on life course trajectories. It is found that declining coital frequency over time seems a shared demographic feature of human populations, but whether marriage duration, wife's age or husband's age is most responsible for that decline varies by country. In many cases, coital frequency actually increases with women's age into their thirties, once husband's age and marriage duration are taken into account, but in most cases coital frequency declines with husband's age and marital duration.     

Charting the course of reed‐warblers across the Pacific islands

Aim Deciphering the complex colonization history of island archipelagos is greatly facilitated by comprehensive phylogenies. In this study we investigate the phylogeny and biogeography of the insular reed‐warblers (genus Acrocephalus) of the tropical Pacific Ocean, from Australia to eastern Polynesia. Location Oceania. Methods We used sequences of mitochondrial DNA (cytochrome b, ND2 and ATP8 genes) to infer the colonization patterns of reed‐warblers endemic to Pacific islands and Australia. We sampled all known taxa of Acrocephalus in the Pacific except A. luscinius nijoi, for which no sample was available. Most taxa were represented by toe‐pad samples from museum specimens collected in the 19th and 20th centuries. With a few exceptions, several specimens per taxon were sequenced independently in two institutions (Smithsonian Institution and Natural History Museum of Geneva). Results Our data indicate that Pacific reed‐warblers do not form a monophyletic group, because A. luscinius luscinius from Guam falls outside the main Pacific radiation. The remaining Pacific taxa are divided into two clades: one clade includes all the reed‐warblers from Micronesia (except Guam) and Australia, and two Polynesian taxa from the Line Islands and the southern Marquesas; the other clade includes all remaining Polynesian taxa. The taxa endemic to three archipelagos (Mariana, Marquesas and Society islands) are polyphyletic, suggesting several independent colonizations. Main conclusions Our results provide evidence for a complex pattern of colonization of the Pacific by reed‐warblers. Calibration analyses suggest that reed‐warbler lineages are much younger than the ages of the islands they occupy. Several remote archipelagos were colonized independently more than once. Consequently, we infer that the colonization of reed‐warblers in the Pacific did not follow a regular, stepping‐stone‐like pattern. The phylogeny also suggests a previously undetected case of reverse colonization (from island to continent) for the Australian lineage and indicates that A. luscinius, as currently defined, is not monophyletic. We discuss the supertramp strategy of reed‐warblers in the Pacific and show that, although Pacific reed‐warblers meet some of the supertramp criteria in their aptitude for colonizing remote archipelagos, their life history characteristics do not fit the model.     

Measuring health-related quality of life of HIV-positive adolescents in resource-constrained settings

Background and Objectives

Access to antiretroviral treatment among adolescents living with HIV (ALH) is increasing. Health-related quality of life (HRQOL) is relevant for monitoring the impact of the disease on both well-being and treatment outcomes. However, adequate screening tools to assess HRQOL in low-resource settings are scarce. This study aims to fill this research gap, by 1) assessing the psychometric properties and reliability of an Eastern African English version of a European HRQOL scale for adolescents (KIDSCREEN) and 2) determining which version of the KIDSCREEN (52-, 27- and 10-item version) is most suitable for low-resource settings.

Methods

The KIDSCREEN was translated into Eastern African English, Luganda (Uganda) and Dholuo (Kenya) according to standard procedures. The reconciled version was administered in 2011 to ALH aged 13–17 in Kenya (n = 283) and Uganda (n = 299). All three KIDSCREEN versions were fitted to the data with confirmatory factor analysis (CFA). After comparison, the most suitable version was adapted based on the CFA outcomes utilizing the results of previous formative research. In order to develop a general HRQOL factor, a second-order measurement model was fitted to the data.

Results

The CFA results showed that without adjustments, the KIDSCREEN cannot be used for measuring the HRQOL of HIV-positive adolescents. After comparison, the most suitable version for low-resource settings - the 27-item version - was adapted further. The introduction of a negative wording factor was required for the Dholuo model. The Dholuo (CFI: 0.93; RMSEA: 0.039) and the Luganda model (CFI: 0.90; RMSEA: 0.052) showed a good fit. All cronbach’s alphas of the factors were 0.70 or above. The alpha value of the Dholuo and Lugandan HRQOL second-order factor was respectively 0.84 and 0.87.

Conclusions

The study showed that the adapted KIDSCREEN-27 is an adequate tool for measuring HRQOL in low-resource settings with high HIV prevalence.     

Sex differences in body composition early in life

Background: Early development of the percentage of fat and muscle is rarely considered, but is important because excessive fat is related to the development of diabetes and other morbidities later in life. In pediatric medicine, there are few to no data comparing sex differences in body composition in the first months of life despite the fact that males are typically longer and weigh more than girls at birth.Objective: The purpose of this study was to determine whether observed sex differences in body composition at birth persist through the first 6 months of life.Methods: Participants were healthy, full-term, male and female newborns. Children throughout the Oklahoma City, Oklahoma, metropolitan area were enrolled. The inclusion criteria were: mothers aged 18 to 45 years at the time of delivery; a term pregnancy lasting ≥37 weeks of gestation (determined by mother's physician); weight adequate for gestational age; and a hospital stay for the infant of <3 days following delivery. The exclusion criteria were: maternal tobacco use or alcohol consumption (>1 drink per week) during pregnancy; gestational diabetes; preeclampsia; and infants with presumed or known congenital birth defects. Baseline assessment at birth included length and weight. Newborns had their body composition (percent fat [%fat], total fat, and fat-free mass) determined at ~1 month of age using whole body plethysmography. Mothers were invited to have their children take part in a 5-month extension that conducted additional body composition measurements at 3 and 6 months of age.Results: Sixty-four girls (mean [SD] age at time of testing, 20.9 [7.9] days; birth weight, 3500 [388] g; birth length, 49.9 [2.4] cm; white race, 73.4%) and 53 boys (mean age at time of testing, 20.2 [7.3] days; birth weight, 3353 [413] g; birth length, 51.0 [2.4] cm; white race, 69.8%) were assessed and included in the study. At birth, girls were significantly shorter and weighed more than boys (both, P < 0.05). At ~1 month of age, body composition revealed that girls had significantly greater %fat (15.1% vs 12.7%; P < 0.05) and less fat-free mass (3182 [303] vs 3454 [361] g; P < 0.001) than did boys. At 3 months of age, girls continued to have significantly less fat-free mass (4379 [347] vs 4787 [310] g; P < 0.01) than did boys; however, by 6 months of age, no significant sex difference was observed in any body composition variable studied.Conclusion: In this small sample of healthy, full-term newborns, at ~1 month of age, statistically significant differences in %fat and fat-free mass existed between girls and boys; however, by 6 months of age, these differences no longer existed.     

Atypical squamous cells and low‐grade squamous intraepithelial lesion in cervical cytology: cytohistological correlation and implication for management in a low‐resource setting

N. Gupta, R. Srinivasan, R. Nijhawan, A. Rajwanshi, P. Dey, V. Suri and L. Dhaliwal Atypical squamous cells and low‐grade squamous intraepithelial lesion in cervical cytology: cytohistological correlation and implication for management in a low‐resource setting Objectives: To perform an audit of all cervical smears reported as atypical squamous cells (ASC) and low‐grade squamous intraepithelial lesion (LSIL) as in the Bethesda system (TBS) 2001, and determine their histological follow‐up and outcome when available, in order to define the threshold for colposcopic referral. Material and methods: A total of 25 203 cervical smears were screened over a period of 3 years (January 2006 – December 2008) and all ASC and LSIL smears were reviewed with the corresponding histological follow‐up. All cervical intraepithelial neoplasia (CIN) grade 2 lesions and above (CIN2+) were considered as clinically significant lesions for analysis. Results: Out of 25 203 cervical smears, 424 (1.7%) were reported as ASC and 113 (0.4%) as LSIL. Additionally, three were reported as atypical cells, not otherwise specified. The ASC : SIL ratio was 2.18 : 1. Follow‐up histology was available in 153 (36.8%) of the ASC cases and revealed CIN2+ lesions in 22 (14.4%). Follow‐up histology was available in 50 (44.2%) of LSIL cases and revealed clinically significant abnormalities in five (10%), all of which were CIN2. CIN3 and invasive squamous carcinomas were seen in 5.9% and 1.4%, respectively, of cases of ASC, and not seen in LSIL. Reclassification of ASC smears into ASC‐US (ASC‐undetermined significance) and ASC‐H (ASC‐ high grade SIL not excluded) revealed ASC‐H in 2.6% of all ASC smears, with a clinically significant outcome in 45.4%. Conclusion: In a low‐resource setting where human papillomavirus testing is unaffordable, the threshold for colposcopic referral and follow‐up histology should be ASC rather than SIL.     

Contrasting heterozygosity‐fitness correlations across life in a long‐lived seabird

Selection is a central force underlying evolutionary change and can vary in strength and direction, for example across time and space. The fitness consequences of individual genetic diversity have often been investigated by testing for multilocus heterozygosity‐fitness correlations (HFCs), but few studies have been able to assess HFCs across life stages and in both sexes. Here, we test for HFCs using a 26‐year longitudinal individual‐based data set from a large population of a long‐lived seabird (the common tern, Sterna hirundo), where 7,974 chicks and breeders of known age were genotyped at 15 microsatellite loci and sampled for life‐history traits over the complete life cycle. Heterozygosity was not correlated with fledging or post‐fledging prospecting probabilities, but was positively correlated with recruitment probability. For breeders, annual survival was not correlated with heterozygosity, but annual fledgling production was negatively correlated with heterozygosity in males and highest in intermediately heterozygous females. The contrasting HFCs among life stages and sexes indicate differential selective processes and emphasize the importance of assessing fitness consequences of traits over complete life histories.     

Potentials for prolonging shelf‐life of platelets by near infrared low‐level light

Platelets are uniquely stored at room temperature, during which they gradually loss their quality owing to deteriorating functions of mitochondria over time. Given the well‐documented beneficial effect of near infrared low‐level light (LLL) on mitochondrial functions, we explored a potential for LLL to protect mitochondrial function and extend the shelf‐life of platelets beyond the current 5 days. We found that exposure of a platelet‐containing storage bag to 830 nm light‐emitting diode (LED) light at 0.5 J/cm² prior to storage could significantly retain a pH value and viability of the platelets stored for 8 days with improved quality compared to those stored similarly for 5 days in controls. The LLL inhibited reactive oxygen species (ROS) and lactate production, while sustaining ATP synthesis and mitochondrial membrane potential and morphology in the stored platelets. It also sustained aggregation capacity and in vivo survival of stored platelets, concomitant with no significant activation, as suggested by similar CD62p expression and enhanced agonist‐induced aggregation and recovery following infusion in the presence compared to absence of LLL treatment. This simple, additive‐free, cost‐effective, noninvasive approach can be readily incorporated into the current platelet storage system to potentially improve quality of stored platelets.      

Bird community composition across an Andean tree‐line ecotone

Few studies have found strong evidence to suggest that ecotones promote species richness and diversity. In this study we examine the responses of a high‐Andean bird community to changes in vegetation and topographical characteristics across an Andean tree‐line ecotone and adjacent cloud forest and puna grassland vegetation in southern Peru. Over a 6‐month period, birds and vegetation were surveyed using a 100 m fixed‐width Distance Sampling point count method. Vegetation analyses revealed that the tree‐line ecotone represented a distinctive high‐Andean vegetation community that was easily differentiated from the adjacent cloud forest and puna grassland based on changes in tree‐size characteristics and vegetation cover. Bird community composition was strongly seasonal and influenced by a pool of bird species from a wider elevational gradient. There were also clear differences in bird community measures between tree‐line vegetation, cloud forest and puna grassland with species turnover (β‐diversity) most pronounced at the tree‐line. Canonical Correspondence Analysis revealed that the majority of the 81 bird species were associated with tree‐line vegetation. Categorizing patterns of relative abundance of the 42 most common species revealed that the tree‐line ecotone was composed primarily of cloud forest specialists and habitat generalists, with very few species from the puna grassland. Only two species, Thlypopsis ruficeps and Anairetes parulus, both widespread Andean species more typical of montane woodland vegetation edges, were categorized as ecotone specialists. However, our findings were influenced by significant differences in species detectability between all three vegetation communities. Our study highlights the importance of examining ecotones at an appropriate spatial and temporal scale. Selecting a suitable distance between sampling points based on the detection probabilities of the target bird species is essential to obtain an unbiased picture of how ecotones influence avian richness and diversity.     

Microbial life associated with low‐temperature alteration of ultramafic rocks in the Leka ophiolite complex

Water–rock interactions in ultramafic lithosphere generate reduced chemical species such as hydrogen that can fuel subsurface microbial communities. Sampling of this environment is expensive and technically demanding. However, highly accessible, uplifted oceanic lithospheres emplaced onto continental margins (ophiolites) are potential model systems for studies of the subsurface biosphere in ultramafic rocks. Here, we describe a microbiological investigation of partially serpentinized dunite from the Leka ophiolite (Norway). We analysed samples of mineral coatings on subsurface fracture surfaces from different depths (10–160 cm) and groundwater from a 50‐m‐deep borehole that penetrates several major fracture zones in the rock. The samples are suggested to represent subsurface habitats ranging from highly anaerobic to aerobic conditions. Water from a surface pond was analysed for comparison. To explore the microbial diversity and to make assessments about potential metabolisms, the samples were analysed by microscopy, construction of small subunit ribosomal RNA gene clone libraries, culturing and quantitative‐PCR. Different microbial communities were observed in the groundwater, the fracture‐coating material and the surface water, indicating that distinct microbial ecosystems exist in the rock. Close relatives of hydrogen‐oxidizing Hydrogenophaga dominated (30% of the bacterial clones) in the oxic groundwater, indicating that microbial communities in ultramafic rocks at Leka could partially be driven by H₂ produced by low‐temperature water–rock reactions. Heterotrophic organisms, including close relatives of hydrocarbon degraders possibly feeding on products from Fischer–Tropsch‐type reactions, dominated in the fracture‐coating material. Putative hydrogen‐, ammonia‐, manganese‐ and iron‐oxidizers were also detected in fracture coatings and the groundwater. The microbial communities reflect the existence of different subsurface redox conditions generated by differences in fracture size and distribution, and mixing of fluids. The particularly dense microbial communities in the shallow fracture coatings seem to be fuelled by both photosynthesis and oxidation of reduced chemical species produced by water–rock reactions.     

Life‐history trade‐offs vary with resource availability across the geographic range of a widespread plant

• Trade‐offs between reproduction, growth and survival arise from limited resource availability in plants. Environmental stress is expected to exacerbate these negative correlations, but no studies have evaluated variation in life‐history trade‐offs throughout species geographic ranges. Here we analyse the costs of growth and reproduction across the latitudinal range of the widespread herb Plantago coronopus in Europe.
• We monitored the performance of thousands of individuals in 11 populations of P. coronopus, and tested whether the effects of growth and reproduction on a set of vital rates (growth, probability of survival, probability of reproduction and fecundity) varied with local precipitation and soil fertility. To account for variation in internal resources among individuals, we analysed trade‐offs correcting for differences in size.
• Growth was negatively affected by previous growth and reproduction. We also found costs of growth and reproduction on survival, reproduction probability and fecundity, but only in populations with low soil fertility. Costs also increased with precipitation, possibly due to flooding‐related stress. In contrast, growth was positively correlated with subsequent survival, and there was a positive covariation in reproduction between consecutive years under certain environments, a potential strategy to exploit temporary benign conditions.
• Overall, we found both negative and positive correlations among vital rates across P. coronopus geographic range. Trade‐offs predominated under stressful conditions, and positive correlations arose particularly between related traits like reproduction investment across years. By analysing multiple and diverse fitness components along stress gradients, we can better understand life‐history evolution across species’ ranges, and their responses to environmental change.

     

Host genetic variation impacts microbiome composition across human body sites

BackgroundThe composition of bacteria in and on the human body varies widely across human individuals, and has been associated with multiple health conditions. While microbial communities are influenced by environmental factors, some degree of genetic influence of the host on the microbiome is also expected. This study is part of an expanding effort to comprehensively profile the interactions between human genetic variation and the composition of this microbial ecosystem on a genome- and microbiome-wide scale.ResultsHere, we jointly analyze the composition of the human microbiome and host genetic variation. By mining the shotgun metagenomic data from the Human Microbiome Project for host DNA reads, we gathered information on host genetic variation for 93 individuals for whom bacterial abundance data are also available. Using this dataset, we identify significant associations between host genetic variation and microbiome composition in 10 of the 15 body sites tested. These associations are driven by host genetic variation in immunity-related pathways, and are especially enriched in host genes that have been previously associated with microbiome-related complex diseases, such as inflammatory bowel disease and obesity-related disorders. Lastly, we show that host genomic regions associated with the microbiome have high levels of genetic differentiation among human populations, possibly indicating host genomic adaptation to environment-specific microbiomes.ConclusionsOur results highlight the role of host genetic variation in shaping the composition of the human microbiome, and provide a starting point toward understanding the complex interaction between human genetics and the microbiome in the context of human evolution and disease.

Electronic supplementary material

The online version of this article (doi:10.1186/s13059-015-0759-1) contains supplementary material, which is available to authorized users.     

Translation of a behavioral weight loss intervention for mid‐life,low‐income women in local health departments

Objective: To translate a behavioral weight loss intervention for mid‐life, low‐income women in real world settings. Design and Methods: In this pragmatic clinical trial, we randomly selected six North Carolina county health departments and trained their current staff to deliver a 16‐session evidence‐based behavioral weight loss intervention (special intervention, SI). SI weight loss outcomes were compared to a delayed intervention (DI) control group. Results: Of 432 women expressing interest, 189 completed baseline measures and were randomized within health departments to SI (N = 126) or DI (N = 63). At baseline, average age was 51 years, 53% were African American, mean weight was 100 kg, and BMI averaged 37 kg/m². A total of 96 (76%) SI and 55 (87%) DI participants returned for 5‐month follow‐up measures. The crude weight change was ?3.1 kg in the SI and ?0.4 kg in the DI group, for a difference of 2.8 kg (95% CI 1.4 to 4.1, p = 0.0001). Diet quality and physical activity improved significantly more in the SI group, and estimated intervention costs were $327 per participant. Conclusion: This pragmatic short‐term weight loss intervention targeted to low‐income mid‐life women yielded meaningful weight loss when translated to the county health department setting.     

Tracking and fixed ranking of leukocyte telomere length across the adult life course

Short leukocyte telomere length (LTL) is associated with atherosclerosis in adults and diminished survival in the elderly. LTL dynamics are defined by LTL at birth, which is highly variable, and its age‐dependent attrition thereafter, which is rapid during the first 20 years of life. We examined whether age‐dependent LTL attrition during adulthood can substantially affect individuals' LTL ranking (e.g., longer or shorter LTL) in relation to their peers. We measured LTL in samples donated 12 years apart on average by 1156 participants in four longitudinal studies. We observed correlations of 0.91–0.96 between baseline and follow‐up LTLs. Ranking individuals by deciles revealed that 94.1% (95% confidence interval of 92.6–95.4%) showed no rank change or a 1 decile change over time. We conclude that in adults, LTL is virtually anchored to a given rank with the passage of time. Accordingly, the links of LTL with atherosclerosis and longevity appear to be established early in life. It is unlikely that lifestyle and its modification during adulthood exert a major impact on LTL ranking.