The acardiac anomaly

Karyotype analysis of a premature human acardiac twin disclosed normal chromosomes. A review of previous cytogenetic, placental and animal studies suggests that chromosomal errors are not the cause of the acardiac anomaly. Rather, they point to the placental vascular anastomoses as the principal pathogenetic event.     

Photoacoustic imaging of the human placental vasculature

Minimally invasive fetal interventions require accurate imaging from inside the uterine cavity. Twin‐to‐twin transfusion syndrome (TTTS), a condition considered in this study, occurs from abnormal vascular anastomoses in the placenta that allow blood to flow unevenly between the fetuses. Currently, TTTS is treated fetoscopically by identifying the anastomosing vessels, and then performing laser photocoagulation. However, white light fetoscopy provides limited visibility of placental vasculature, which can lead to missed anastomoses or incomplete photocoagulation. Photoacoustic (PA) imaging is an alternative imaging method that provides contrast for hemoglobin, and in this study, two PA systems were used to visualize chorionic (fetal) superficial and subsurface vasculature in human placentas. The first system comprised an optical parametric oscillator for PA excitation and a 2D Fabry‐Pérot cavity ultrasound sensor; the second, light emitting diode arrays and a 1D clinical linear‐array ultrasound imaging probe. Volumetric photoacoustic images were acquired from ex vivo normal term and TTTS‐treated placentas. It was shown that superficial and subsurface branching blood vessels could be visualized to depths of approximately 7 mm, and that ablated tissue yielded negative image contrast. This study demonstrated the strong potential of PA imaging to guide minimally invasive fetal therapies.      

Statistical inference in mixed models and analysis of twin and family data

Analysis of data from twin and family studies provides the foundation for studies of disease inheritance. The development of advanced theory and computational software for general linear models has generated considerable interest for using mixed-effect models to analyze twin and family data, as a computationally more convenient and theoretically more sound alternative to the classical structure equation modeling. Despite the long history of twin and family data analysis, some fundamental questions remain unanswered. We addressed two important issues. One is to determine the necessary and sufficient conditions for the identifiability in the mixed-effects models for twin and family data. The other is to derive the asymptotic distribution of the likelihood ratio test, which is novel due to the fact that the standard regularity conditions are not satisfied. We considered a series of specific yet important examples in which we demonstrated how to formulate mixed-effect models to appropriately reflect the data, and our key idea is the use of the Cholesky decomposition. Finally, we applied our method and theory to provide a more precise estimate of the heritability of two data sets than the previously reported estimate.     

Modeling Familial Association of Ages at Onset of Disease in the Presence of Competing Risk

Summary In genetic family studies, ages at onset of diseases are routinely collected. Often one is interested in assessing the familial association of ages at the onset of a certain disease type. However, when a competing risk is present and is related to the disease of interest, the usual measure of association by treating the competing event as an independent censoring event is biased. We propose a bivariate model that incorporates two types of association: one is between the first event time of paired members, and the other is between the failure types given the first event time. We consider flexible measures for both types of association, and estimate the corresponding association parameters by adopting the two‐stage estimation of Shih and Louis (1995, Biometrics 51, 1384–1399) and Nan et al. (2006, Journal of the American Statistical Association 101, 65–77). The proposed method is illustrated using the kinship data from the Washington Ashkenazi Study.     

Baseline neutrophilia,derived neutrophil‐to‐lymphocyte ratio (dNLR), platelet‐to‐lymphocyte ratio (PLR), and outcome in non small cell lung cancer (NSCLC) treated with Nivolumab or Docetaxel

Nivolumab is a novel therapeutic option in NSCLC, associated with a significant survival gain compared with Docetaxel. However, predictive biomarkers are lacking. The presence of systemic inflammation has been correlated with poor outcome in many cancer types. We aimed to evaluate whether there is a correlation between some indicators of inflammation and response to Nivolumab or Docetaxel in pre‐treated NSCLCs. Data of 62 patients receiving Nivolumab or Docetaxel were analyzed. Baseline neutrophilia and thrombocytosis were not associated with response. High dNLR was associated with no response to Nivolumab, but not with Docetaxel, whereas high PLR correlated with low treatment response in both groups. Among refractory patients, a higher incidence of thrombocytosis, neutrophilia, high PLR, and high dNLR levels were observed compared with the overall population. This is one of the first reports in this field and suggests that indicators of inflammation might be included together with other predictive biomarkers in the baseline evaluation of patients candidate for immunotherapy.     

Waist-to-height ratio is an accurate and easier index for evaluating obesity in children and adolescents

Objectives: The present study aims to evaluate the accuracy of the index of waist‐to‐height ratio (WHTR), and proposed the optimal thresholds of WHTR in the definition of childhood overweight and obesity in a bi‐ethnic Chinese school‐aged population. Research Methods and Procedures: Overweight and obese were identified by BMI for age and gender in a random sample including 2055 Han and 2132 Uygur ethnic school‐aged children (8 to 18 years old). WHTR was calculated by waist circumference divided by height on the basis of standard anthropometric measurements. Receiver operating characteristic (ROC) curve analyses were performed to assess the accuracy of WHTR as a diagnostic test for childhood overweight and obesity, compared with waist circumference. The optimal thresholds of WHTR for defining overweight and obesity were recommended respectively by gender. The correlation between WHTR and age was analyzed and compared with BMI. Results: A‐values (area under curve) of WHTR for diagnosing overweight and obesity were both over 0.90 in both genders and better than those of waist circumference. A threshold of 0.445 was identified for overweight in both genders, with the sensitivity and specificity >0.80. The thresholds for defining obesity was 0.485 in boys and 0.475 in girls, both having the sensitivity and specificity >0.90. WHTR showed less association with age than BMI. Conclusions: WHTR is a simple, easy, accurate, and non‐age‐dependent index with high applicability to screening overweight and obesity in children and adolescents. The use of WHTR in the general childhood population has been justified by this study.     

Intrauterine growth restriction in like-sex twins discordant for structural defects

BACKGROUND: An increased risk for intrauterine growth restriction in the affected member of like-sex twin pairs discordant for hypospadias has been reported. The purpose of this study was to document patterns of birth weight disparities in like-sex twins discordant for a variety of structural defects in order to determine if this is a general phenomenon seen in twins who are discordant for any malformation, is seen only in pairs discordant for certain specific malformations, or is unique to hypospadias. METHODS: Data were extracted from the Latin American Collaborative Study of Congenital Malformations (ECLAMC). Between 1967 and 1999, all like-sex twin pairs discordant for hypospadias or any other isolated defect that met the criteria of at least 5 discordant pairs for which birth weight was available on both twins were selected. All nonmalformed like-sex twin pairs in the ECLAMC data base collected over the same study years were selected as controls. RESULTS: A total of 216 discordant malformed like-sex twin pairs in 13 defect categories and 328 nonmalformed like-sex twin pairs met the criteria for inclusion. The proportion of affected infants who were > or =20% smaller than their co-twin was statistically significantly different from controls for hypospadias, heart defects, anencephaly, and esophageal atresia. CONCLUSIONS: Intrauterine growth restriction seen in the affected member of like-sex twin pairs discordant for hypospadias is not unique, but occurs as well in at least 3 additional structural malformations.     

Quantitative variability of 342 plasma proteins in a human twin population

The degree and the origins of quantitative variability of most human plasma proteins are largely unknown. Because the twin study design provides a natural opportunity to estimate the relative contribution of heritability and environment to different traits in human population, we applied here the highly accurate and reproducible SWATH mass spectrometry technique to quantify 1,904 peptides defining 342 unique plasma proteins in 232 plasma samples collected longitudinally from pairs of monozygotic and dizygotic twins at intervals of 2–7 years, and proportioned the observed total quantitative variability to its root causes, genes, and environmental and longitudinal factors. The data indicate that different proteins show vastly different patterns of abundance variability among humans and that genetic control and longitudinal variation affect protein levels and biological processes to different degrees. The data further strongly suggest that the plasma concentrations of clinical biomarkers need to be calibrated against genetic and temporal factors. Moreover, we identified 13 cis‐SNPs significantly influencing the level of specific plasma proteins. These results therefore have immediate implications for the effective design of blood‐based biomarker studies.     

Anthropometric Indices and the Incidence of Hypertension: A Comparative Analysis

Objective: To investigate the association between several anthropometric measurements of obesity with the incidence of hypertension. Research Methods and Procedures: Participants were 592 individuals free of hypertension, selected at random from the community. In the baseline evaluation, they were submitted to completed measures of demographics, anthropometrics, blood pressure, and other risk factors for hypertension. Incident hypertension was defined by blood pressure equal or higher than 140/90 mm Hg or use of blood pressure‐lowering drugs. Results: During a mean follow‐up time of 5.6 ± 1.1 years, 127 developed hypertension. The hazard ratios for the development of hypertension, adjusted for age, baseline blood pressure, gender, and alcohol consumption, were 1.042 (p = 0.091) for BMI, 1.023 (p = 0.028) for waist circumference, 1.042 (p = 0.013) for waist‐to‐height ratio, 1.061 (p = 0.014) for waist‐to‐height² index, 1.079 (p = 0.022) for waist‐to‐height³ index, and 1.033 (p = 0.006) for the waist‐to‐hip ratio. Discussion: The correction of the circumference of waist for stature or hip circumference improves its performance in the prediction of the incidence of hypertension.     

Coexpression of molecular chaperone enhances activity and export of organophosphorus hydrolase in Escherichia coli

Periplasmic secretion has been used in attempts to construct an efficient whole‐cell biocatalyst with greatly reduced diffusion limitations. Previously, we developed recombinant Escherichia coli that express organophosphorus hydrolase (OPH) in the periplasmic space using the twin‐arginine translocation (Tat) pathway to degrade environmental toxic organophosphate compounds. This system has the advantage of secreting protein into the periplasm after folding in the cytoplasm. However, when OPH was expressed with a Tat signal sequence in E. coli, we found that the predominant OPH was an insoluble premature form in the cytoplasm, and thus, the whole‐cell OPH activity was significantly lower than its cell lysate activity. In this work, we, for the first time, used a molecular chaperone coexpression strategy to enhance whole‐cell OPH activity by improving the periplasmic translocation of soluble OPH. We found that the effect of GroEL‐GroES (GroEL/ES) assistance on the periplasmic localization of OPH was secretory pathway dependent. We observed a significant increase in the amount of soluble mature OPH when cytoplasmic GroEL/ES was expressed; this increase in the amount of mature OPH might be due to enhanced OPH folding in the cytoplasm. Importantly, the whole‐cell OPH activity of the chaperone–coexpressing cells was ～5.5‐fold greater at 12 h after induction than that of cells that did not express the chaperone as a result of significant Tat‐based periplasmic translocation of OPH in the chaperone–coexpressing cells. Collectively, these data suggest that molecular chaperones significantly enhance the whole‐cell activity of periplasmic OPH‐secreting cells, yielding an effective whole‐cell biocatalyst system with highly reduced diffusion limitations. © 2012 American Institute of Chemical Engineers Biotechnol. Prog., 28: 925–930, 2012     

Effect of weather conditions on the spring migration of Eurasian Woodcock and consequences for breeding

Migration is a critical period of time with fitness consequences for birds. The development of tracking technologies now allows researchers to examine how different aspects of bird migration affect population dynamics. Weather conditions experienced during migration are expected to influence movements and, subsequently, the timing of arrival and the energetic costs involved. We analysed satellite‐tracking data from 68 Eurasian Woodcock Scolopax rusticola fitted with Argos satellite tags in the British Isles and France (2012–17). First, we evaluated the effect of weather conditions (temperature, humidity, wind speed and direction, atmospheric stability and visibility) on migration movements of individuals. Then we investigated the consequences for breeding success (age ratio) and brood precocity (early‐brood ratio) population‐level indices while accounting for climatic variables on the breeding grounds. Air temperature, wind and relative humidity were the main variables related to migration movements, with high temperatures and northward winds greatly increasing the probability of onward flights, whereas a trend towards greater humidity over 4 days decreased the probability of movement. Breeding success was mostly affected by climatic variables on the breeding grounds. The proportion of juveniles in autumn was negatively correlated with temperature in May, but positively correlated with precipitation in June and July. Brood precocity was poorly explained by the covariates used in this study. Our data for the Eurasian Woodcock indicate that, although weather conditions during spring migration affect migration movements, they do not have a major influence on subsequent breeding success.     

Crystal structure of bacteriophage ϕNIT1 zinc peptidase PghP that hydrolyzes γ-glutamyl linkage of bacterial poly-γ-glutamate

Poly‐γ‐glutamate hydrolase P (PghP) of Bacillus subtilis bacteriophage ΦNIT1 hydrolyzes the γ‐glutamyl peptide linkage of extracellular poly‐γ‐glutamate produced by bacilli, which facilitates infection and propagation of phage progenies. Crystal structure of PghP was determined at a resolution of 1.9 Å. Structure of PghP was elucidated as a globular protein with an open α/β mixed core structure and a seven‐stranded parallel/anti‐parallel β‐sheet. The β‐sheet contained a core four‐stranded parallel β‐sheet. A zinc‐binding motif, His‐Glu‐His, was identified at the C‐terminal end of the β‐sheet. Structure analysis demonstrated that PghP, which had not been previously classified into any peptidase/protease family due to lack of amino acid sequence similarity with known enzymes, had a catalytic center containing a zinc ion and an overall topology resembling mammalian carboxypeptidase A and related enzymes. Structural comparisons indicated important amino acid residues of PghP for catalysis and recognition of the γ‐peptide bond of poly‐γ‐glutamate, which was confirmed by site‐directed mutagenesis of PghP. Proteins 2011. © 2012 Wiley Periodicals, Inc.     

Development and validation of immune inflammation–based index for predicting the clinical outcome in patients with nasopharyngeal carcinoma

Inflammation indicators, such as systemic inflammation response index (SIRI), systemic immune‐inflammation index (SII), neutrophil‐to‐lymphocyte ratio (NLR) and platelet‐lymphocyte ratio (PLR), are associated with poor prognosis in various solid cancers. In this study, we investigated the predictive value of these inflammation indicators in nasopharyngeal carcinoma (NPC). This retrospective study involved 559 patients with NPC and 500 patients with chronic rhinitis, and 255 NPC patients were followed up successfully. Continuous variables and qualitative variables were measured by t test and chi‐square test, respectively. The optimal cut‐off values of various inflammation indicators were determined by receiver operating characteristic (ROC) curve. Moreover, the diagnostic value for NPC was decided by the area under the curves (AUCs). The Kaplan‐Meier methods and the log‐rank test were used to analyse overall survival (OS) and disease‐free survival (DFS). The independent prognostic risk factors for survival and influencing factors of side effects after treatment were analysed by Cox and logistic regression analysis, respectively. Most haematological indexes of NPC and rhinitis were significantly different between the two groups, and PLR was optimal predictive indicators of diagnosis. In the multivariable Cox regression analysis, PLR, WBC, RDW, M stage and age were independent prognostic risk factors. Many inflammation indicators that affected various side effects were evaluated by logistic regression analysis. In conclusion, the combined inflammation indicators were superior to single haematological indicator in the diagnosis and prognosis of NPC. These inflammation indicators can be used to supply the current evaluation system of the TNM staging system to help predict the prognosis in NPC patients.     

Usefulness of Anthropometry and DXA in Predicting Intra‐abdominal Fat in Obese Men and Women

Objective: To investigate the usefulness of anthropometry and DXA in predicting intra‐abdominal fat (IAF) in obese men and women. Research Methods and Procedures: Observational, cross sectional study of 22 women and 18 men with a body mass index of 30 or above. IAF from 20 cm above and 10 cm below the L4 to L5 intervertebral disc was measured by magnetic resonance imaging (MRI) as a reference method. Central abdominal fat was measured from the upper border of L2 to the lower border of L4 by DXA. Waist and hip circumferences were also measured. Results: In obese women DXA, waist circumference and waist‐hip ratio were equally well correlated with IAF (r = 0.74, 0.75, and 0.70, respectively). In obese men DXA was moderately correlated with IAF measured by MRI (r = 0.46), whereas waist circumference and waist‐hip ratio were not significantly correlated with IAF. Discussion: The prediction of IAF in obese subjects was highly dependent on sex more than in non‐obese persons. Anthropometry and DXA were equally useful in obese women, whereas anthropometry had no predictive power and DXA was the only acceptable predictor of IAF in obese men.     

Higher order inference for the consensus mean in inter-laboratory studies

In inter-laboratory studies, a fundamental problem of interest is inference concerning the consensus mean, when the measurements are made by several laboratories which may exhibit different within-laboratory variances, apart from the between laboratory variability. A heteroscedastic one-way random model is very often used to model this scenario. Under such a model, a modified signed log-likelihood ratio procedure is developed for the interval estimation of the common mean. Furthermore, simulation results are presented to show the accuracy of the proposed confidence interval, especially for small samples. The results are illustrated using an example on the determination of selenium in non-fat milk powder by combining the results of four methods. Here, the sample size is small, and the confidence limits for the common mean obtained by different methods produce very different results. The confidence interval based on the modified signed log-likelihood ratio procedure appears to be quite satisfactory.     

An 'unconditional-like' structure for the conditional estimator of odds ratio from 2 x 2 tables

In the estimation of the odds ratio (OR), the conditional maximum-likelihood estimate (cMLE) is preferred to the more readily computed unconditional one (uMLE). However, the exact cMLE does not have a closed form to help divine it from the uMLE or to understand in what circumstances the difference between the two is appreciable. Here, the cMLE is shown to have the same 'ratio of cross-products' structure as its unconditional counterpart, but with two of the cell frequencies augmented, so as to shrink the unconditional estimator towards unity. The augmentation involves a factor, similar to the finite population correction, derived from the minimum of the marginal totals.     

Intragenomic conflict produces sex ratio dynamics that favor maternal sex ratio distorters

Maternal sex ratio distorters (MSDs) are selfish elements that enhance their transmission by biasing their host's sex allocation in favor of females. While previous models have predicted that the female‐biased populations resulting from sex ratio distortion can benefit from enhanced productivity, these models neglect Fisherian selection for nuclear suppressors, an unrealistic assumption in most systems. We used individual‐based computer simulation modeling to explore the intragenomic conflict between sex ratio distorters and their suppressors and explored the impacts of these dynamics on population‐level competition between species characterized by MSDs and those lacking them. The conflict between distorters and suppressors was capable of producing large cyclical fluctuations in the population sex ratio and reproductive rate. Despite fitness costs associated with the distorters and suppressors, MSD populations often exhibited enhanced productivity and outcompeted non‐MSD populations in single and multiple‐population competition simulations. Notably, the conflict itself is beneficial to the success of populations, as sex ratio oscillations limit the competitive deficits associated with prolonged periods of male rarity. Although intragenomic conflict has been historically viewed as deleterious to populations, our results suggest that distorter–suppressor conflict can provide population‐level advantages, potentially helping to explain the persistence of sex ratio distorters in a range of taxa.