Coral communities of the remote atoll reefs in the Nansha Islands, southern South China Sea.

During the months of May and June in the year 2007, a survey was conducted regarding coral reef communities in the remote atolls (Zhubi Reef and Meiji Reef) of Nansha Islands, southern South China Sea. The goals of the survey were to: (1) for the first time, compile a scleractinian coral check-list; (2) estimate the total richness, coral cover, and growth forms of the community; and (3) describe preliminary patterns of community structure according to geomorphological units. Findings of this survey revealed a total of 120 species of scleractinia belonging to 40 genera, while the average coral cover was 21 %, ranging from less than 10 % to higher than 50 %. Branching and massive corals were also found to be the most important growth forms of the whole coral community, while Acropora, Montipora, and Porites were the three dominant genera in the overall region, with their contributions to total coral cover measuring 21, 22, and 23 %, respectively. Overall, coral communities of the Nansha Islands were in a relative healthy condition with high species diversity and coral cover. Spatial pattern of coral communities existed among various geomorphological units. Mean coral cover was highest in the patch reef within the lagoon, followed by the fore reef slope, reef flat, and lagoon slope. The greatest contributors to total coral cover were branching Acropora (45 %) in the lagoon slope, branching Montipora (44 %) in the reef flat, and massive Porites (51 %) in the patch reef. Coral cover in the fore reef revealed a greater range of genera than in other habitats. The leeward fore reef slope had higher coral cover (> 50 %) when compared with the windward slope (< 10 %). The coral communities of the inner reef flat were characterized by higher coral cover (27 %) and dominant branching Montipora corals, while lower coral cover (4 %) was dominated by Psammocora with massive growth forms on the outer reef flat. Destructive fishing and coral bleaching were two major threats to coral communities in the study area.

Effectiveness of Family-Centered Oral Health Promotion on Toddler Oral Health in Hong Kong.

Early childhood caries is common in Hong Kong, and parental practices on maintaining good oral health of their young children are far from satisfactory. This article reports on the effectiveness of a randomized controlled trial on family-centered oral health promotion to new parents in establishing proper feeding habits and oral hygiene practices and in reducing caries risk among 3-y-old toddlers. At baseline, pregnant mothers and their husbands were recruited and randomly allocated into 2 groups. The test group received individualized oral health education (OHE) via a behavioral and educational counseling approach while the control group received the OHE pamphlets only. Information related to the feeding habits, oral hygiene practices, and oral health of the toddlers was collected by parent-completed questionnaires and oral examination annually via home visits. A total of 580 families were recruited at baseline, and 436 toddlers were followed up when they reached 3 y old (test, n = 228; control, n = 208; follow-up rate, 75.2%). The proportions of toddlers who held food in the mouth, fell asleep when milk feeding, had prolonged use of the nursing bottle, ate before bed, and consumed a sweet snack daily were significantly lower in the test group than in the control group (all P < 0.05). Significantly higher proportions of toddlers brushed their own teeth twice daily, were brushed by their parents twice daily, and used fluoride toothpaste than in the control group (all P < 0.001). Toddlers in the test group had better oral health status with a lower level of visible plaque, Streptococcus mutans, white spot lesion, and cavitated lesion (all P < 0.05). Family-centered oral health promotion and individualized OHE for parents via a behavioral and educational counseling approach are more effective in establishing good feeding habits and parental toothbrushing practices and in decreasing the caries risk of their toddlers than the distribution of OHE pamphlets alone (ClinicalTrials.gov NCT02937194).

Active immunization of fatty acid translocase specifically decreased visceral fat deposition in male broilers.

Lipid accumulation of avian adipocytes is mainly dependent upon the fatty acid transmembrane uptake process mediated by membrane proteins, such as fatty acid translocase (FAT/CD36), fatty acid transport protein 1, and caveolin-2. To examine the effects of FAT/CD36 on spatial-specific fat deposition, 60 broiler chickens were randomly allocated to 2 groups by sex. Each male or female group contained 2 subgroups (n = 14-15) inoculated by intramuscular injection with chicken FAT/CD36 or BSA (control) immunogens at 34, 49, and 63 d. The subcutaneous and visceral fat deposits were measured, as were levels of plasma triglyceride and free fatty acid. Serum antibody titer was measured by ELISA. The mRNA expression levels of fatty acid transport-related genes in the adipose tissue of the male broilers were investigated to reveal the relationships among various fatty acid transporters. The results showed that active immunization with FAT/CD36 could significantly decrease the visceral fat of the male broilers by up to 40%, but it had no effect on subcutaneous fat stores of male broilers or on either site of fat deposition in female broilers. The concentration of plasma free fatty acids increased in the experimental groups for both male and female broilers. After the FAT/CD36 immunization, very low density lipoprotein receptor mRNA expression was upregulated in both the subcutaneous and visceral fat of male broilers, whereas peroxisome proliferator-activated receptor γ, FAT/CD36, and acyl-CoA binding protein mRNA expression levels were upregulated only in the visceral fat of male broilers. These results indicated a novel role of chicken FAT/CD36 in fat deposition, with sex- and spatial-specific effects.

Testing for genetic association with constrained models using triads.

It has been shown that it is preferable to use a robust model that incorporated constraints on the genotype relative risk rather than rely on a model that assumes the disease operates in a recessive or dominant fashion. Previous methods are applicable to case-control studies, but not to family based studies of case children along with their parents (triads). We show here how to implement analogous constraints while analyzing triad data. The likelihood, conditional on the parents genotype, is maximized over the appropriately constrained parameter space. The asymptotic distribution for the maximized likelihood ratio statistic is found and used to estimate the null distribution of the test statistics. The properties of several methods of testing for association are compared by simulation. The constrained method provides higher power across a wide range of genetic models with little cost when compared to methods that restrict to a dominant, recessive, or multiplicative model, or make no modeling restriction. The methods are applied to two SNPs on the methylenetetrahydrofolate reductase (MTHFR) gene with neural tube defect (NTD) triads.

Evaluation of the effectiveness of a community-based enriched model prenatal intervention project in the District of Columbia.

OBJECTIVE: To evaluate an enriched prenatal intervention program designed to reduce the risk of low birth weight. STUDY SETTING: Freestanding community-based prenatal intervention project located in a poor inner-city community, serving mostly African American women. STUDY DESIGN: All women less than 29 weeks pregnant were eligible to participate. They were compared to women who lived in neighborhoods with similar rates of poverty. DATA COLLECTION: The birth certificate was the source of data on maternal age, education, marital status, timing and frequency of prenatal care attendance, parity, gravidity, prior pregnancy terminations, fetal and child deaths, and birth weight. PRINCIPAL FINDINGS: Thirty-eight percent of the women who delivered live-born infants in the study area participated in the program. There were no differences in low- and very low birthweight rates in the study and comparison groups. In a secondary analysis comparing participants and nonparticipants in the study census tracts, participants were at higher risk for low and very low birth weight, and they adhered more closely to the schedule of prenatal visits than nonparticipants. Low- and very low birthweight rates were lower among participants than among nonparticipants and comparison women. CONCLUSION: The Better Babies Project did not have an effect on the overall low- and very low birthweight rates in the study census tracts. This was probably due to the low participation rates and the high population mobility.

Birth weight, gestational age and perinatal mortality: biological heterogeneity and measurement error.

At low birth weight the variance of last menstrual period based gestational age is wide and the distribution is positively skewed toward higher values. In this study the variance of gestational age decreases rapidly as birth weight increases, skewness decreases and kurtosis increases in approaching the mean of the birth weight distribution. Some of the wider variance and positive skewness of gestational age at low birth weight appears to reflect heterogeneity of intrauterine growth, in which infants with high values of gestational age are growth retarded. We show by partitioning each birth weight group into two groups of infants with different gestational age distributions, that at low birth weight, infants with low gestational ages have higher neonatal mortality rates but lower fetal mortality rates than infants with a higher gestational age for birth weight. The differences in mortality described between small infants at different gestational ages suggest that infants with a high LMP-based gestational age have experienced a slower rate of intrauterine growth. Some authors interpret the distributional characteristics as indications of systematic error in last menstrual period based assessment of gestational age. It appears from this study that the extent of systematic error in the estimation of LMP based gestational age may have been overstated in the past.

On estimating standardized risk differences from odds ratios.

An estimator proposed by Greenland and Holland (1991, Biometrics 47, 319-322) for a standardized risk difference parameter is shown to be a maximum likelihood estimator if the consistent estimator of the common odds ratio is appropriately chosen. The statistical problem under consideration is reparameterized. Likelihood equations are derived.

Segregation of random amplified polymorphic DNA markers and strategies for molecular mapping in tetraploid alfalfa.

An F1 population was used to analyze the inheritance of random amplified polymorphic DNA (RAPD) markers in tetraploid alfalfa. Of the 32 RAPD markers that were used for a segregation analysis in this study, 27 gave ratios that are consistent with random chromosome and random chromatid segregation at meiosis. However, among all of the RAPD markers (121) that were screened in this study, only one example of a double reduction, that is typical of chromatid segregation, was observed. These results indicate that random chromosome segregation is likely the predominant but not the exclusive mode of inheritance for tetraploid alfalfa. χ2 analyses of cosegregation for RAPD marker pairs derived from the female parent revealed nine linkages that fell into four linkage groups. The recombination fractions among linked marker pairs ranged from 1 to 37%. These are the first molecular linkage groups reported in tetraploid alfalfa. In addition, various strategies for molecular mapping in the tetraploid alfalfa genome are proposed that should be of interest to plant breeders who are planning to use molecular markers for alfalfa or other tetraploid species.

Adolescent age at first pregnancy and subsequent obesity.

Adolescent pregnancy has been associated with subsequent obesity. This paper examines the patterns of obesity for second and third pregnancies among women who had their first singleton pregnancy as teenagers. We used maternally-linked data from 1978 to 1990 among 43,160 Missouri resident women. Age, parity, interpregnancy interval and prior body mass index were significantly associated with subsequent obesity among adolescents. Race, marital status and smoking had significant interactions with age. Among older women, being African-American and never having married was associated with an increased probability of obesity, and smoking had a greater effect on obesity at higher maternal age. Race and marital status did not have significant effects on obesity among younger women. The most important predictor of obesity was prior body mass index. Body mass index before the first pregnancy had a greater effect on subsequent obesity if the intervening interpregnancy weight gains were large. Excessive weight gain during pregnancy presents the health care provider with a dilemma. An increase in birthweight associated with high prenatal weight gains may diminish the risk of infant mortality and morbidity in an index pregnancy, but subsequent obesity may increase perinatal mortality rates, the rates of obstetric problems and neural tube defects.

PIP: This study examines the prevalence of obesity among American women who had an adolescent pregnancy in Missouri. Data were obtained from a maternally-linked longitudinal data set for the period 1978-90. The sample includes 103,262 births for first through fifth order singleton pregnancies linked to 43,160 Missouri mothers with a first pregnancy before the age of 20 years. Findings indicate that all women had at least two pregnancies. 31% had three pregnancies, 7% had four pregnancies, and 1% had five pregnancies. 8% were aged under 15 years at the first pregnancy, 35% were aged 16-17 years, and 57% were aged 18-19 years. A significantly higher number of higher birth order women had their first pregnancy when aged under 16 years. African American women were more likely to have their first pregnancy under 15 years of age, while White women were more likely to have their first pregnancy at 19 years. Medical risk factors decreased with age and increased with birth order. Cigarette smoking increased with age and with each pregnancy for all women. White women smoked more at every age and birth order. The rates of women in a subsample on Medicaid and food stamps decreased with age and increased with birth order. Rates of obesity increased with birth order. Rates increased from 3.8% for the first pregnancy to 16% for the fourth pregnancy. Women who were underweight at their first pregnancy had only a 0.5% increase in the rate of obesity from the first to second pregnancy, but overweight women had a 44.9% increase, and obese women had a 21% decrease in the rate of obesity. From the second to the fifth pregnancy, underweight women's rates of obesity are identified. Prior to the second and third pregnancy, the significant predictors of obesity were body mass index before the first pregnancy, interpregnancy weight gain, interpregnancy interval, race, medical risk factors, marital status, and smoking.

A note on testing the Hardy-Weinberg law across strata.

The problem of testing the Hardy-Weinberg law when the data are stratified in K strata is considered. Previous methods lose power when the departure from the law is irregular from stratum to stratum. Two methods based on the squared distance are proposed to overcome this problem. Simulations show that the new methods can have a dramatic improvement over the previous methods. The methods are applied to red cell glyoxalase genotype data from populations in India.

What's the relative risk? A method of correcting the odds ratio in cohort studies of common outcomes.

Logistic regression is used frequently in cohort studies and clinical trials. When the incidence of an outcome of interest is common in the study population (>10%), the adjusted odds ratio derived from the logistic regression can no longer approximate the risk ratio. The more frequent the outcome, the more the odds ratio overestimates the risk ratio when it is more than 1 or underestimates it when it is less than 1. We propose a simple method to approximate a risk ratio from the adjusted odds ratio and derive an estimate of an association or treatment effect that better represents the true relative risk.

Stopping a clinical trial very early because of toxicity: summarizing the evidence.

When a trial is stopped early because of a specific toxicity, it may be important to summarize the statistical evidence for stopping. Such a summary needs to take into account the sequential nature of the stopping rule. We address some practical issues involved in analyzing such toxicity data coming from a trial that was stopped after the fourth patient was evaluated.

Statistical methods of computing reference values for side-to-side differences in nerve conduction studies.

This study uses theoretic derivations, statistical simulations, and empirical estimations to compare two ways of deriving reference values for side-to-side differences in nerve conduction parameters of healthy subjects. The two methods involve using the side-to-side differences (STSD) and the absolute values of the STSD (AVSTSD). The theoretic derivations showed that the population reference value of the AVSTSD is greater than the STSD reference values by 0.18%. Simulation studies showed that the AVSTSD yields greater sampling errors than the STSD method when establishing the reference values for nerve conduction parameters. However, the sampling variability is substantially reduced by using study samples of greater than 50, and the differences between the two methods in sampling errors are trivial as sample size approaches 100. Using H reflex (HR) and extensor digitorum brevis reflex (EDBR) clinical data, the two methods were compared. In contrast to the small theoretic differences in reference values, the AVSTSD method overestimated the reference value by 0.5 ms for the EDBR and 0.1 ms for the H reflex, when using data from a population sample, increasing the type II error (reducing sensitivity) for the EDBR. The STSD method is recommended for establishment of normal values and for clinical comparisons.

Adaptive choice of mean or median in estimating the center of a symmetric distribution.

An adaptive choice of the sample mean x(n) or the sample median m(n) is proposed for estimating the center of a symmetric distribution. This choice becomes correct as n --> infinity, and in simulation results for finite n it is almost as good as the better of x(n) and m(n).

Does changing paternity contribute to the risk of intrauterine growth retardation?

An immune reaction initiated by paternal antigens may be necessary for healthy placental development, pregnancy maintenance and infant growth. An inadequate immune response may result in intrauterine growth retardation (IUGR). We hypothesised that a change in paternity may interfere with the immune response and cause poor placentation with resultant IUGR. In this paper we examine the risk of IUGR associated with changes in paternity. We used the Utah Successive Pregnancies Data Set that contains information on women across their pregnancies. We restricted the analysis to 141,817 women with two or three pregnancies. Women who did not have an IUGR infant in the previous pregnancy were at a 20-30% greater risk of developing IUGR if they had changed partners. Women who had a previous IUGR infant were at no increased risk for IUGR after a change in paternity. These results may point to an immune mechanism or may be as a result of residual confounding of unmeasured risk factors for IUGR. Further studies with data that contain more sociodemographic and biological risk factors for IUGR are necessary to exclude residual confounding.

Maternal vitamin levels during pregnancies producing infants with neural tube defects.

Women at very high risk for having a child with a neural tube defect (NTD) because they had previously delivered affected children significantly reduced their recurrence rate by taking folate supplements before conception. To clarify how these results might apply to a lower-risk general obstetric population, we measured folate, vitamin B12, and retinol levels in maternal serum drawn early in 89 pregnancies resulting in NTD offspring and 178 control pregnancies identified from the Finnish Registry of Congenital Malformations. In 86.5% of the subjects, specimens were collected within 8 weeks after neural tube closure. In the NTD case mothers the mean (+/- SD) levels were not significantly lower than in control mothers: folate, 4.13 +/- 2.36 versus 4.28 +/- 2.52 ng/ml; vitamin B12, 482.8 +/- 161.1 versus 520.3 +/- 191.9 pg/ml; and retinol, 51.2 +/- 17.0 versus 50.5 +/- 16.9 micrograms/dl. After adjustment for age of the specimen, gestational age at which the specimen was drawn, maternal age, and maternal employment status, the odds ratios for being a case mother were 1.00 (95% confidence interval (CI) 0.91 to 1.10) for folate, 1.05 (95% CI 0.92 to 1.19) for vitamin B12, and 0.99 (95% CI 0.88 to 1.10) for retinol. Excluding NTD cases with known or suspected causes unrelated to vitamins, restricting the analyses to interviewed subjects, and excluding subjects whose specimens were collected after 15 gestational weeks confirmed that NTD case and control vitamin levels did not differ significantly. This population-based investigation in a low rate area demonstrated no relationship between maternal serum folate, vitamin B12, or retinol levels during pregnancy and the risk of NTDs.

Breath-to-breath variations in rate and depth of ventilation in sleeping infants.

Ventilatory measurements were made noninvasively over 2- to 3-h periods during sleep in each of nine normal infants at 1 mo of age. To assess the changes that occur in ventilation on a breath-to-breath basis, we 1) examined the variations of each of tidal volume (VT), respiratory cycle time (Ttot), expiratory time (TE), and inspiratory time (TI) and 2) studied their interrelationships. We found that the variations of VT, Ttot, and TE but not of TI were significantly greater in rapid-eye-movement (REM) than in quiet sleep. In addition, on a breath-to-breath basis, VT had a positive linear relationship and strong correlation with TI; however, the correlation between VT and TE was weak in both sleep states. VT/Ttot was found to be moderately and negatively correlated with Ttot in both REM and quiet sleep. VT was weakly correlated with Ttot in REM sleep and was, on the average, more correlated with Ttot in quiet sleep. We suggest that in infants 1) on a breath-to-breath basis, VT/Ttot is likely to drop if respiratory frequency is decreased and 2) VT is nonlinearly related to Ttot during sleep; this lack of linearity depends on the lack of constancy of VT/Ttot, which is in turn closely related to the variability of the "on-switching" of inspiratory activity.