Socioecological effects of swidden management in traditional Maya agroforests in the Selva Lacandona of Chiapas, Mexico.

For millennia, Maya farmers (i.e., milperos) throughout Mesoamerica have managed milpa: sequential agroforests initiated by slashing and burning patches of secondary forest and then cultivating a diverse polyculture of trees and annual crops. To reduce greenhouse gas emissions associated with deforestation, the Mexican government and non-governmental organizations have urged milperos to cease burning. We collaborated with Maya milperos in several communities in the Montes Azules Biosphere Reserve region in Chiapas, Mexico to determine carbon retained as char in traditional milpas, carbon loss associated with burning, and effects of burning on soil quality. We found the carbon retention of char in Maya milpas (24 ± 6.5% of C in vegetation) is 4-1400% higher than other slash-and-burn agroecosystems reported in the literature. Burning resulted in significant carbon loss of 12.6 (±3.6) t C ha-1 yr-1, but this was partially mitigated by char production (3.0 [±0.6] t C ha-1 yr-1) and incomplete combustion of woody biomass. The effects of burning on soil were minimal, with the only significant changes observed being increases in pH, potassium availability, and cation exchange capacity (2, 100, and 7%, respectively). The mean residence times of charred materials were at least double that of uncharred biomass. While there is a risk that shortening fallow periods would undermine the sustainability of Maya swidden agroecology, proper management and secure land tenure can help maintain intensive production without enduring environmental degradation. The char produced in these swiddens and successional management could allow this agroforestry system to be a long-term carbon sink.

Smoking in pregnancy is a key factor for sudden infant death among Maori.

AIM: To examine the sudden unexpected death in infancy (SUDI) disparity between Maori and non-Maori in New Zealand. METHODS: A nationwide prospective case-control study ran from March 2012 to February 2015. Exposure to established SUDI risk factors was analysed to investigate the disparity experienced by Maori. Infant ethnicity was based on mother's ethnicity. Maori ethnicity was prioritised. Non-Maori includes Pacific, Asian, NZ European and Other. RESULTS: There were 137 cases and 649 controls. The Maori SUDI rate was 1.41/1000 live births compared to 0.53/1000 for non-Maori. Parents/caregivers of 132 cases (96%) and 258 controls (40%) were interviewed. Smoking in pregnancy was associated with an equally increased SUDI risk for Maori (adjusted OR = 8.11, 95% CI = 2.64, 24.93) and non-Maori (aOR = 5.09, 95% CI = 1.79, 14.47), as was bed-sharing (aOR = 3.66, 95% CI = 1.49, 9.00 vs aOR = 11.20, 95% CI = 3.46, 36.29). Bed-sharing prevalence was similar; however, more Maori controls smoked during pregnancy (46.7%) than non-Maori (22.8%). The main contributor relating to increased SUDI risk for Maori/non-Maori infants is the combination of smoking in pregnancy and bed sharing. CONCLUSION: The association between known SUDI risk factors, including bed sharing and/or smoking in pregnancy and SUDI risk, is the same regardless of ethnicity. Maori infants are exposed more frequently to both behaviours because of the higher Maori smoking rate.

Effect of monthly high-dose vitamin D on bone density in community-dwelling older adults substudy of a randomized controlled trial.

BACKGROUND: Severe vitamin D deficiency causes osteomalacia, yet trials of vitamin D supplementation in the community have not on average demonstrated benefit to bone mineral density (BMD) or fracture risk in adults. OBJECTIVE: To determine whether monthly high-dose vitamin D supplementation influences BMD in the general population and in those with low 25-hydroxyvitamin D levels. METHODS: Two-year substudy of a trial in older community-resident adults. A total of 452 participants were randomized to receive monthly doses of vitamin D3 100 000 IU, or placebo. The primary end-point was change in lumbar spine BMD. Exploratory analyses to identify thresholds of baseline 25-hydroxyvitamin D for vitamin D effects on BMD were prespecified. RESULTS: Intention-to-treat analyses showed no significant treatment effect in the lumbar spine (between-groups difference 0.0071 g cm-2 , 95%CI: -0.0012, 0.0154) or total body but BMD loss at both hip sites was significantly attenuated by ~1/2% over 2 years. There was a significant interaction between baseline 25-hydroxyvitamin D and treatment effect (P = 0.04). With baseline 25-hydroxyvitamin D ≤ 30 nmol L-1 (n = 46), there were between-groups BMD changes at the spine and femoral sites of ~2%, significant in the spine and femoral neck, but there was no effect on total body BMD. When baseline 25-hydroxyvitamin D was >30 nmol L-1 , differences were ~1/2% and significant only at the total hip. CONCLUSIONS: This substudy finds no clinically important benefit to BMD from untargeted vitamin D supplementation of older, community-dwelling adults. Exploratory analyses suggest meaningful benefit in those with baseline 25-hydroxyvitamin D ≤ 30 nmol L-1 . This represents a significant step towards a trial-based definition of vitamin D deficiency for bone health in older adults.

Antibiotic treatment during infancy and increased body mass index in boys: an international cross-sectional study.

OBJECTIVE: To investigate whether antibiotic exposure during the first year of life is associated with increased childhood body mass index (BMI). DESIGN: Secondary analysis from a multi-centre, multi-country, cross-sectional study (The International Study of Asthma and Allergies in Childhood Phase Three). SUBJECTS: A total of 74 946 children from 31 centres in 18 countries contributed data on antibiotic use in the first 12 months of life and current BMI. METHODS: Parents/guardians of children aged 5-8 years completed questionnaires that included questions about their children's current height and weight, and whether in the child's first 12 months of life, they had received any antibiotics, paracetamol, were breastfed or the mother/female guardian smoked cigarettes, and whether the child had wheezed in the past 12 months. A general linear mixed model was used to determine the association of antibiotic exposure with BMI, adjusting for age, sex, centre, BMI measurement type (self-reported or measured), maternal smoking, breastfeeding, paracetamol use, gross national income and current wheeze. RESULTS: There was a significant interaction between sex and early-life antibiotic exposure. Early-life antibiotic exposure was associated with increased childhood BMI in boys (+0.107 kg m(-2), P<0.0001), but not in girls (-0.008 kg m(-2), P=0.75) after controlling for age, centre and BMI measurement type. The association remained in boys (+0.104 kg m(-2), P<0.0007), after adjustment for maternal smoking, breastfeeding, paracetamol use and current wheeze. There was no interaction between age, maternal smoking, breastfeeding, paracetamol use, gross national income and current wheeze in the association between early antibiotic exposure and BMI. CONCLUSIONS: Exposure to antibiotics during the first 12 months of life is associated with a small increase in BMI in boys aged 5-8 years in this large international cross-sectional survey. By inference this provides additional support for the importance of gut microbiota in modulating the risk of obesity, with a sex-specific effect.

Body mass index in relation to semen quality and reproductive hormones in New Zealand men: a cross-sectional study in fertility clinics.

STUDY QUESTION: Is there an association between body mass index (BMI) and routine semen analysis parameters in adult men? SUMMARY ANSWER: No significant correlation was found between BMI and semen parameters measured with the exception of normal sperm morphology. WHAT IS KNOWN ALREADY: Multiple cross-sectional studies have found inconsistent results, with two meta-analyses finding no correlation between BMI and semen parameters. A relationship between BMI and male reproductive hormones, particularly total testosterone, has been established in several studies and a systematic review. STUDY DESIGN, SIZE, DURATION: Cross-sectional study of 511 men recruited at the time of semen analysis over 4 years (2008-2012). PARTICIPANTS/MATERIALS, SETTING, METHODS: Men presenting for semen analysis for any reason at participating fertility clinics in Auckland, New Zealand were recruited, with BMI measured or self-reported at this time. Exclusion criteria included azoospermia and pathological conditions of male genital tract. Conventional BMI categories were used (underweight <18.5 kg/m(2), normal 18.5-24.99 kg/m(2), overweight 25.00-29.99 kg/m(2), obese ≥30 kg/m(2)). The routine semen analysis results for sperm concentration, total sperm count, sperm motility (total motility), sperm morphology, semen volume and total motile sperm (primary outcome) from one semen sample were recorded. Consent from 175 men was obtained to measure LH, FSH, estradiol, total testosterone, free testosterone and sex hormone-binding globulin (SHBG) in a blood sample (secondary outcome). Associations between BMI and these outcomes were assessed using Spearman correlation and analysis of variance, and a multiple linear regression analysis was performed. In addition, the relative risks for men having abnormal semen analysis results according to reference ranges of the World Health Organization, such as oligozoospermia, were calculated. This study has sufficient power to detect a doubling in abnormally low sperm concentration and total sperm count in overweight or obese men compared with men with normal BMI. Participation rate was not recorded. MAIN RESULTS AND THE ROLE OF CHANCE: The body mass indices from measured and self-reported samples had an equivalent range of values which did not differ statistically. Median BMI was 27.1 kg/m(2) [10th-90th percentile: 22.8-32.9]. Overall, 72.8% of the study population were overweight or obese (BMI >25 kg/m(2)), while 19 men (3.72%) had a BMI of 35-40 kg/m(2) and 7 men (1%) had a BMI of >40 kg/m(2). No significant correlation was found between BMI and the semen parameters measured with the exception of normal sperm morphology (r = 0.12, P = 0.024), although this finding is derived from only 330 samples. Overweight and obese men showed no significantly increased relative risk of abnormal semen parameters. Of the reproductive hormones, significant negative relationships with BMI were found for total testosterone (r = -0.35, P = <0.0001), free testosterone (r = -0.25, P = <0.0012) and SHBG (r = -0.44, P = <0.0001). Multiple linear regression analysis also showed that BMI had a marginally significant effect on normal sperm morphology (effect estimate =0.47, P = 0.038). In addition, <2 days of abstinence was negatively associated with semen volume (effect estimate =-0.80, P = 0.0074) and summer season was negatively associated with sperm concentration (effect estimate =-14.9, P = 0.020). LIMITATIONS, REASONS FOR CAUTION: The power of this study is limited by the relatively small overall sample size, although it does have one of the largest proportions of obese men (23.3%) in published cross-sectional studies. The study involved samples from men attending a fertility clinic, who are likely to have a lower semen quality and higher rate of pathology compared with the general population, therefore limiting the possible generalization of this study to all adult men. WIDER IMPLICATIONS OF THE FINDINGS: Our findings are consistent with those of other cross-sectional studies as well as two meta-analyses but do disagree in part with the most recent meta-analysis (which found significant odds ratios for oligozoospermia and azoospermia with increased BMI) and with studies measuring DNA fragmentation index. Therefore a definitive conclusion on the effect of BMI on semen quality remains uncertain while our data reinforce previous findings that BMI is negatively associated with male reproductive hormones. STUDY FUNDING/COMPETING INTEREST(S): All funding for this study was from New Zealand academic and charitable sources including: Faculty of Medical and Health Sciences, University of Auckland (New Zealand), the Mercia Barnes Trust of the Royal Australian and New Zealand College of Obstetricians and Gynaecologists and the Nurture Foundation for Reproductive Research. The authors have no conflicts of interest to declare.

Foraging Wild Edibles: Dietary Diversity in Expanded Food Systems.

Human food foraging in community forests offers extensive and expandable sources of food and high-quality nutrition that support chronic disease prevention and management and are underrepresented in US diets. Despite severe gaps in non-commercial "wild food" data, research in Syracuse, NY, identified substantial amounts of five key antioxidant phytochemicals in locally available, forageable foods with the potential to augment local dietary diversity and quality. Findings endorse the need for micro- and macro-nutrient research on an expanded range of forageable foods, community nutrition education on those foods, an expanded study on antioxidant phytochemical function, and the inclusion of forageables in the food system definition.

Maternal and pathological pregnancy characteristics in customised birthweight centiles and identification of at-risk small-for-gestational-age infants: a retrospective cohort study.

OBJECTIVE: To regenerate coefficients for the New Zealand customised birthweight centile calculator using an updated birth cohort, and compare the identification of at-risk small-for-gestational-age (SGA) infants between full customisation (including maternal characteristics) and an ultrasound-based fetal weight and infant gender partial customisation. DESIGN: Retrospective cohort study of prospectively collected maternity data. SETTING: National Women's Health Auckland, New Zealand. POPULATION: Singleton pregnancies in the period 2006-2009; n = 24,176. METHODS: Multiple linear regression analysis was performed for full customisation (adjusted for gestation, infant gender, maternal characteristics and pathological variables) and ultrasound-and-gender customisation (adjusted for gestation and infant gender). MAIN OUTCOME MEASURES: Risks of SGA-related perinatal death were compared between models. RESULTS: Changes occurred in some ethnicity coefficients, including Chinese (-135 g), Tongan (-101 g) and Samoan (-89 g), and ten ethnicities were added. Overall, full customisation identified SGA infants with higher odds of perinatal death (OR 5.6, 95% CI 3.6-8.7) than infants classed as SGA by ultrasound-and-gender customisation (OR 2.1, 95% CI 1.4-3.3) (P = 0.02). In subgroup analyses, infants classed as SGA by full but not ultrasound-and-gender customisation (n = 888, 3.4%) had an increased risk of perinatal death (RR 4.7, 95% CI 2.7-7.9); however, those identified as SGA by ultrasound-and-gender customisation alone were not at an increased risk (n = 676, 2.6%, RR 1.1, 95% CI 0.4-3.6). The population attributable risk (PAR) of SGA-related perinatal death was higher for full (49.8%) than for ultrasound-and-gender (43.0%) customisation. CONCLUSIONS: Updating the New Zealand customised birthweight centile calculator resulted in revised coefficients that better reflect a contemporary birth cohort. Inclusion of maternal characteristics in a birthweight customisation model increases the detection of SGA infants at risk of perinatal death.

The impact of maternal body mass index on the phenotype of pre-eclampsia: a prospective cohort study.

OBJECTIVE: We hypothesised that among nulliparous women with pre-eclampsia, overweight or obese women would have a different phenotype of pre-eclampsia compared with normal weight women with pre-eclampsia. Specifically, they are more likely to develop term pre-eclampsia and less likely to have indicators of impaired placental perfusion, e.g. abnormal uterine artery Doppler or a small-for-gestational-age (SGA) infant. DESIGN: Prospective, multicentre, cohort SCOPE study (n = 3170). SETTING: New Zealand and Australia. POPULATION: Nulliparous women who developed pre-eclampsia. METHODS: Participants were interviewed at 14-16 weeks of gestation, uterine artery Doppler studies were performed at 19-21 weeks and pregnancy outcome was tracked prospectively. MAIN OUTCOME MEASURES: Rates of abnormal uterine artery Doppler indices, term/preterm birth and SGA infants were compared between normal, overweight and obese women with pre-eclampsia. Multivariable analysis was performed to examine the association between body mass index (BMI) and term pre-eclampsia. RESULTS: Of 178 women with pre-eclampsia, one underweight woman was excluded and 66 (37%) were normal weight, 52 (29%) were overweight and 59 (34%) were obese. Pre-eclampsia developed preterm in 26% of women and at term in 74% of women. There were no differences in the rates of term/preterm pre-eclampsia, abnormal uterine artery Doppler indices or SGA infants between BMI groups (P > 0.10). No independent association between BMI and term pre-eclampsia was found (P = 0.56). CONCLUSIONS: Among women with pre-eclampsia, those who are overweight or obese in early pregnancy are not more likely to have term pre-eclampsia compared with women with a normal BMI. Overweight and obese women require vigilant surveillance for the development of preterm as well as term pre-eclampsia.

Changes over time in the relationship between symptoms of asthma, rhinoconjunctivitis and eczema: a global perspective from the International Study of Asthma and Allergies in Childhood (ISAAC).

BACKGROUND: The International Study of Asthma and Allergies in Childhood (ISAAC) identified trends in the prevalence of symptoms of asthma, rhinoconjunctivitis and eczema over a seven-year period. We hypothesised that environmental influences on the three diseases are different and therefore investigated the correlation over time between trends in the prevalence of these diseases and their combinations at centre and individual level. METHODS: Centre level analyses were correlations between time trends in the prevalence of symptoms. At an individual level, odds ratios were calculated for associations between symptoms between Phases One and Three. We also investigated potential effect modification in the younger versus older age group; male versus female; and by average Gross National Income per capita (GNI). RESULTS: Both phases were completed in 66 centres in 37 countries for the 6-7 year age group and in 106 centres in 56 countries for the 13-14 year age group. We found that the correlations in time trends were stronger for the older age group than the younger one. Between symptoms of diseases, correlations of time trends were the strongest for rhinoconjunctivitis with eczema and weakest for eczema with asthma. The relationship between the three diseases was generally consistent over the seven-year period, and there was little association found with average GNI. CONCLUSIONS: Despite some increase in the proportion of children with symptoms of asthma, rhinoconjunctivitis and eczema, the pattern between the three diseases has not changed much, suggesting that similar factors may be affecting them at a global level.

PCOSMIC: a multi-centre randomized trial in women with PolyCystic Ovary Syndrome evaluating Metformin for Infertility with Clomiphene.

BACKGROUND: Ovulation induction treatment with metformin, either alone or in combination with clomiphene citrate (CC), remains controversial even though previous randomized trials have examined this. METHODS: A double blinded multi-centre randomized trial was undertaken including 171 women with anovulatory or oligo-ovulatory polycystic ovary syndrome. Women with high body mass index (BMI) > 32 kg/m(2) received placebo ('standard care') or metformin; women with BMI < or = 32 kg/m(2) received CC ('standard care'), metformin or both. Treatment continued for 6 months or until pregnancy was confirmed. Primary outcomes were clinical pregnancy and live birth. RESULTS: For women with BMI > 32 kg/m(2), clinical pregnancy and live birth rates were 22% (7/32) and 16% (5/32) with metformin, 15% (5/33) and 6% (2/33) with placebo. For women with BMI < or = 32 kg/m(2), clinical pregnancy and live birth rates were 40% (14/35) and 29% (10/35) with metformin, 39% (14/36) and 36% (13/36) with CC, 54% (19/35) and 43% (15/35) with combination metformin plus CC. CONCLUSIONS: There is no evidence that adding metformin to 'standard care' is beneficial. Pregnancy and live birth rates are low in women with BMI > 32 kg/m(2) whatever treatment is used, with no evidence of benefit of metformin over placebo. For women with BMI < or = 32 kg/m(2) there is no evidence of significant differences in outcomes whether treated with metformin, CC or both. ClinicalTrials.gov number NCT00795808; trial protocol accepted for publication November 2005: Johnson, Aust N Z Journal Obstet Gynaecol 2006;46:141-145.

Ethnic differences in time trends in asthma prevalence in New Zealand: ISAAC Phases I and III.

SETTING: The International Study of Asthma and Allergies in Childhood (ISAAC) Phase III survey, New Zealand. OBJECTIVE: To assess the prevalence of asthma symptoms and time trends by ethnicity between ISAAC Phase I (1992-1993) and Phase III (2001-2003). DESIGN: Information on asthma symptoms and environmental exposures was collected in children aged 6-7 years (n = 10,873) and adolescents aged 13-14 years (n = 13,317). RESULTS: In children, the prevalence of current wheeze was 28.5% in Maori (prevalence odds ratio [POR] = 1.49, 95%CI 1.32-1.68), and 25.2% in Pacific Islanders (POR 1.28, 95%CI 1.07-1.54) compared with 20.7% in Europeans/Pakeha. In adolescents, 29.9% of Maori (POR = 1.13, 95%CI 1.03-1.23) and 20.8% of Pacific Islanders (POR 0.74, 95%CI 0.62-0.87) experienced current wheeze compared to 28.6% of Europeans/Pakeha. Between Phases I and III, the prevalence of current wheeze increased significantly by 0.49%/year in Pacific Islanders, increased non-significantly by 0.12%/year in Maori, and decreased significantly by 0.25%/year in Europeans/Pakeha children. In adolescents, the prevalence of current wheeze increased by 0.05%/year in Pacific Islanders and decreased by 0.33%/year in Europeans/Pakeha and by 0.07%/year in Maori. CONCLUSION: Ethnic differences in asthma symptom prevalence in New Zealand have increased. The reasons for this are unclear, but may reflect inequalities in access to health services.

Lacandon Maya ecosystem management: sustainable design for subsistence and environmental restoration.

Indigenous groups have designed and managed their ecosystems for generations, resulting in biodiversity protection while producing for their family's needs. Here we describe the agroecosystem of the Lacandon Maya, an indigenous group who live in Chiapas, Mexico. The Lacandon practice a form of swidden agriculture that conserves the surrounding rain forest ecosystem while cycling the majority of their land through five successional stages. These stages include an herbaceous stage, two shrub stages, and two forest stages. A portion of their land is kept in primary forest. This study presents the Lacandon traditional ecological knowledge (TEK) for agroforestry and quantitatively describes the plant community and the associated soil ecology of each successional stage. Also documented is the knowledge of the Lacandon regarding the immediate use of plant species and plant species useful for soil fertility enhancement. Woody plant diversity increases during the successional stages of the Lacandon system, and by the beginning of the first forest stage, the diversity is similar to that of the primary forest. In all stages, Lacandon use 60% of the available plant species for food, medicine, and raw materials. Approximately 45% of the woody plant species present in each fallow stage were thought by the Lacandon to enhance soil fertility. Total soil nitrogen and soil organic matter increased with successional stage and with time from intentional burn. Nutrient and soil nematode dynamics in shrub stages related to the presence of introduced and managed plants, indicating engineered soil enhancement by the Lacandon. The effects on biodiversity and soil ecology coupled with productivity for agricultural subsistence indicate that Lacandon TEK may offer tools for environmental conservation that would provide for a family's basic needs while maintaining a biodiverse rain forest ecosystem. Tools such as these may offer options for regional restoration and conservation efforts such as the Mesoamerican Biological Corridor in Mexico and Central America, where attainment of environmental goals must include methods to provide resources to local inhabitants.

Effect of a Mycobacterium vaccae derivative on paediatric atopic dermatitis: a randomized, controlled trial.

BACKGROUND: The prevalence of atopic diseases in the Western world is rising while infectious diseases decline. The 'hygiene hypothesis' suggests that reduced exposure to microbes such as mycobacteria in early life is associated with increased atopic disease. Recent research showed that Mycobacterium vaccae reduced the severity of atopic dermatitis (AD) in children. OBJECTIVE: To evaluate the efficacy of a derivative of heat-killed M. vaccae in children with AD. METHODS: In total, 129 children, aged 5-16 years old with moderate to severe AD participated in this randomized, double-blind, placebo-controlled trial. Participants received an intradermal injection of either M. vaccae or placebo three times at 2-weekly intervals. The two groups were compared for changes in severity and extent of AD from baseline to 3 and 6 months after treatment. RESULTS: There was no significant difference between the two groups for change in severity of AD at 3 and 6 months (P = 0.77 and P = 0.70, respectively) or in extent of disease at 3 months (P = 1.0). Local injection-site reactions occurred in 47% of participants, of whom 75% received M. vaccae. CONCLUSION: In this study, M. vaccae did not improve AD significantly in children with moderate to severe disease.

Obesity, underweight and BMI distribution characteristics of children by gross national income and income inequality: results from an international survey.

BACKGROUND: Economic wealth and income inequality may impact on childhood BMI distribution by affecting overconsumption of food and sedentary forms of transportation and entertainment across the whole or some of the population. OBJECTIVES: To determine whether BMI distribution of children differs by gross national income (GNI) per capita and Gini index derived from World Bank data. METHODS: Secondary analysis of largely self-reported height and weight data from a multi-country, cross-sectional study (ISAAC), of 77,963 children aged 6-7 (from 19 countries) and 205,388 adolescents aged 13-14 (from 36 countries), were used to examine underweight vs obesity prevalence and BMI distribution skewness, median and dispersion. RESULTS: Children and adolescents from 'lower' GNI countries had higher prevalence of underweight than those from 'higher' GNI countries (6% vs 3%, p = 0.03; 2% vs 1%, p = 0.05 respectively), but the prevalence of obesity was not different (2% vs 5%, p = 0.29; 2% vs 2%, p = 0.66). BMI distribution of participants from 'higher' GNI countries had higher median, without significant difference in skewness or dispersion compared to 'lower' GNI countries (higher medians +1.1 kg/m2 for 6-7 year olds, and + 0.7 kg/m2, +1.2 kg/m2 for 13-14 year old girls and boys respectively). Gini index was not associated with underweight or obesity prevalence in either children or adolescents, nor with any BMI distribution characteristics with one exception. Adolescent girls from higher income inequality countries had a greater median BMI (+0.7 kg/m2) and a less skewed BMI distribution. CONCLUSIONS: It appears that the obesogenic impact of economic prosperity affects all children similarly. Income inequality may have a gender specific effect affecting BMI distribution in adolescent girls.

Design effects associated with dietary nutrient intakes from a clustered design of 1 to 14-year-old children.

OBJECTIVE: To calculate intra-cluster and intra-household design effects and intra-class correlation coefficients for dietary nutrients obtained from a 24 h record-assisted recall. DESIGN: Children were recruited using clustered probability sampling. Randomly selected starting-point addresses were obtained with probability proportional to mesh block size. SETTING: Children aged 1-14 years in New Zealand. SUBJECTS: There were 125 children in 50 clusters, giving an average of 2.498 children per cluster. In 15 homes, there were two children for the calculation of intra-household statistics. RESULTS: Intra-cluster design effects ranged from 1.0 for cholesterol, beta-carotene, vitamin A, vitamin D, vitamin E, selenium, fructose and both carbohydrate and protein expressed as their contribution to total energy intakes to 1.552 for saturated fat, with a median design effect of 1.148. Their corresponding intra-cluster correlations ranged from 0 to 0.37, respectively. Intra-household design effects ranged from 1.0 for height to 1.839 for vitamin B(6), corresponding to intra-household correlations of 0 and 0.839. The median intra-household design effect was 1.550. Using a sampling design of two to three households per cluster for estimating dietary nutrient intakes would need, on average, a 15% increase in sample size compared with simple random sampling with a maximum increase of 55% to cover all nutrients. CONCLUSIONS: These data enable sample sizes for dietary nutrients to be estimated for both cluster and non-cluster sampling for children aged 1-14 years. The larger design effects found within households suggest that little extra information may be obtained by sampling more than one child per household.

Birth weight and subsequent body mass index in children: an international cross-sectional study.

BACKGROUND: The reported association between birth weight and subsequent body mass index (BMI) is conflicting. OBJECTIVES: To examine the relationship between birth weight and BMI in children aged 6-7 years. METHODS: Secondary analysis of data from a multi-centre, multi-country, cross-sectional study (International Study of Asthma and Allergies in Childhood (ISAAC) Phase Three). Parents/guardians of children aged 6-7 years completed questionnaires about their children's birth weight, current height and weight and whether their mother smoked in the first year of the child's life. A general linear mixed model was used to determine the association between BMI and birth weight. RESULTS: A total of 72 111 children (17 countries) were included in the analysis. There was a positive association of birth weight with BMI (for each kg increase in birth weight the BMI at 6-7 increased by 0.47 (SE 0.02) kg/m2 ; p < 0.0001) with a clear gradient by birth weight category. There was no statistically significant interaction between birth weight and Gross National Income (GNI). CONCLUSIONS: There is a positive linear relationship between birth weight and BMI in 6-7 year old children, which is present in both high and low income countries.

Mosquito larvae density and pollutant removal in tropical wetland treatment systems in Honduras.

Constructed wetlands offer a low-cost wastewater treatment option for tropical developing countries. The vast majority of published treatment wetland research has been conducted in temperate regions. Because the function of treatment wetlands is related to the environmental conditions, more research specific to the tropics should be completed. A six-cell free water surface (FWS) wetland mesocosm was constructed in Santa Rosa de Copán, Honduras that received input from an open-sewer/wastewater-impacted stream. Three cells were planted with Typha domingensis Pers., and three cells were left unplanted. Both planted and unplanted wetlands were constructed with three different surface areas to concurrently study different hydraulic retention times (HRTs) and hydraulic loading rates (HLRs). Results from 6 months of operation showed improved water quality and mosquito larvae populations affected by their specific environment. Five-day biochemical oxygen demand (BOD) removal appeared to be proportional to HRT and HLR, and BOD concentration in the effluent was higher in unplanted cells than in planted cells (P<0.05). BOD removal approached 60% for greater than 3.5 days HRT. Total phosphorus (P) removal and coliform bacteria removal were found to be correlated with pollutant load, and P removal was found to be correlated with HRT but not HLR. A second municipal wastewater FWS treatment wetland in Copán Ruinas, Honduras that had been established for 15 years, was also evaluated. BOD removal in the Copán Ruinas system was determined to be 93% with 2.6 day HRT. These pollutant removal rates are higher than would be expected in temperate regions. Mosquito larvae density was correlated with depth of the wetland. Mosquito larvae densities were higher in cells that were operating below design depth of 0.2 m (P<0.005). Results indicate that it is possible to design FWS wetlands in the tropics for effective BOD removal and reduced mosquito larvae development.

Long-term survival and valve-related complications in young women with cardiac valve replacements.

BACKGROUND: The type of cardiac valve replacement associated with the lowest health risks for young women who may undergo pregnancies is unknown. We investigated which valve type was associated with greatest patient and valve survival and the effect of pregnancy on valve loss. METHODS AND RESULTS: In this retrospective study, all women 12 to 35 years old who underwent valve replacements between 1972 and 1992 at Greenlane Hospital were identified, and follow-up was available in 93%. The 232 women were followed up for 1499 patient-years. Ten-year survival of women with mechanical (n=178), bioprosthetic (n=73), and homograft (n=72) valves was 70% (95% CI, 59% to 83%), 84% (95% CI, 72% to 99%), and 96% (95% CI, 91% to 100%), P=0.002. After adjustment for confounding variables, the relative risk (RR) of death with mechanical compared with bioprosthetic valves was 2.17 (95% CI, 0.78 to 5.88). Thromboembolic events occurred in 45% of women with mechanical valves within 5 years, compared with 13% with bioprosthetic valves, P=0.0001. Valve loss at 10 years was higher in bioprosthetic valves [82% (95% CI, 62% to 92%)] than in mechanical [29% (95% CI, 17% to 39%)] or homograft [28% (95% CI, 12% to 41%)] valves, P=0.0001. Pregnancy was not associated with increased bioprosthetic (RR, 0.96; 95% CI, 0.68 to 1. 35), homograft (RR, 0.65; 95% CI, 0.37 to 1.13), or mechanical (RR, 0.54; 95% CI, 0.27 to 1.08) valve loss. CONCLUSIONS: Although 10-year valve survival was greater with mechanical than bioprosthetic valves, mechanical valves may be associated with reduced patient survival in young women. Thromboembolic complications, often with long-term sequelae, were common with mechanical valves. Pregnancy did not increase structural deterioration or reduce survival of bioprosthetic valves.

The association between diabetic retinopathy and skeletal muscle capillary basal lamina thickening corrected for the influence of age and duration of diabetes.

The association between an objective measure of diabetic retinopathy and skeletal muscle capillary basal lamina thickness was examined in a group of 30 male insulin-treated diabetic subjects, mean age (+/- SD) 44.6 +/- 13.2 yr, duration of diabetes 21.2 +/- 11.2 yr, % ideal body weight (% IBW) 106 +/- 11%. In addition, muscle capillary basal lamina width was measured in a group of 18 nondiabeitc men, mean age 40.7 +/- 16.3 yr and % IBW 118 +/- 23%. The muscle capillary width of the diabetic subjects was significantly greater than that of the nondiabetic group (P less than 0.01), but the values of the two overlapped considerably. In the diabetic group, there was a significant association of basal lamina width with age (P less than 0.01) but not with duration of diabetes. The association between extent of retinopathy and muscle capillary basal lamina width was not strong. The findings of the study do not therefore support the use of an estimate of muscle capillary basal lamina thickness as a single representative measure of diabetic microangiopathy.

The international study of asthma and allergies in childhood (ISAAC): phase three rationale and methods.

The International Study of Asthma and Allergies in Childhood (ISAAC) programme commenced in 1991 to study the aetiology of asthma, allergic rhinoconjunctivitis and atopic eczema in children in different populations using standardised methodology and facilitating international collaboration. ISAAC Phase One (1992-1996) found marked differences in the prevalence of symptoms of asthma and allergic disease throughout the world which have not been explained by the current understanding of these diseases. ISAAC Phase Two (1998-2004) uses intensive investigations to further examine the potential role of risk and protective factors that may contribute to the international difference observed in Phase One. Phase Three (2000-2003) essentially represents a repeat of Phase One, in which more detailed standardised data are obtained to enable the time trends of symptom prevalence to be determined as well as the development of a more comprehensive 'world map'. The ISAAC Phase Three rationale and methods are described in this paper. With over 280 centres in 106 countries, we anticipate that ISAAC Phase Three will comprehensively determine the prevalence of symptoms of asthma and allergic disease worldwide, explore recent time trends in the prevalence of these symptoms and cast new light on the aetiology of asthma and allergic disease.