The relationship of readiness factors to Jan. first grade reading achievement

Thesis (Ed.M.)--Boston Universit

Modularity map of the network of human cell differentiation

Cell differentiation in multicellular organisms is a complex process whose mechanism can be understood by a reductionist approach, in which the individual processes that control the generation of different cell types are identified. Alternatively, a large scale approach in search of different organizational features of the growth stages promises to reveal its modular global structure with the goal of discovering previously unknown relations between cell types. Here we sort and analyze a large set of scattered data to construct the network of human cell differentiation (NHCD) based on cell types (nodes) and differentiation steps (links) from the fertilized egg to a crying baby. We discover a dynamical law of critical branching, which reveals a fractal regularity in the modular organization of the network, and allows us to observe the network at different scales. The emerging picture clearly identifies clusters of cell types following a hierarchical organization, ranging from sub-modules to super-modules of specialized tissues and organs on varying scales. This discovery will allow one to treat the development of a particular cell function in the context of the complex network of human development as a whole. Our results point to an integrated large-scale view of the network of cell types systematically revealing ties between previously unrelated domains in organ functions.Comment: 32 pages, 7 figure

Placental biomarkers of phthalate effects on mRNA transcription: application in epidemiologic research

<p>Abstract</p> <p>Background</p> <p>CYP19 and PPARγ are two genes expressed in the placental trophoblast that are important to placental function and are disrupted by phthalate exposure in other cell types. Measurement of the mRNA of these two genes in human placental tissue by quantitative real-time polymerase chain reaction (qPCR) offers a source of potential biomarkers for use in epidemiologic research. We report on methodologic challenges to be considered in study design.</p> <p>Methods</p> <p>We anonymously collected 10 full-term placentas and, for each, sampled placental villi at 12 sites in the chorionic plate representing the inner (closer to the cord insertion site) and outer regions. Each sample was analyzed for the expression of two candidate genes, aromatase (CYP19) and peroxisome proliferator activated receptor protein gamma (PPARγ) and three potential internal controls: cyclophilin (CYC), 18S rRNA (18S), and total RNA. Between and within placenta variability was estimated using variance component analysis. Associations of expression levels with sampling characteristics were estimated using mixed effects models.</p> <p>Results</p> <p>We identified large within-placenta variability in both transcripts (>90% of total variance) that was minimized to <20% of total variance by using 18S as an internal control and by modelling the means by inner and outer regions. 18S rRNA was the most appropriate internal control based on within and between placenta variability estimates and low correlations of 18S mRNA with target gene mRNA. Gene expression did not differ significantly by delivery method. We observed decreases in the expression of both transcripts over the 25 minute period after delivery (CYP19 p-value for trend = 0.009 and PPARγ (p-value for trend = 0.002). Using histologic methods, we confirmed that our samples were comprised predominantly of villous tissue of the fetal placenta with minimal contamination of maternally derived cell types.</p> <p>Conclusion</p> <p>qPCR-derived biomarkers of placental CYP19 and PPARγ gene expression show high within-placental variability. Sampling scheme, selection of an appropriate internal control and the timing of sample collection relative to delivery can be optimized to minimize within-placenta and other sources of underlying, non-etiologic variability.</p

The Hidden Costs of Land Degradation in US Maize Agriculture

The United States is a world leader in the production of maize and other crops and the agricultural success of the country is directly linked to the intensive use of fertilizers and irrigation. However, even in advanced agricultural systems, soils can become degraded over time due to factors such as soil organic matter (SOM) loss and erosion. Here, we use a series of scenario-based model analyses to show that about one-third of current annual US. N fertilizer use in maize agriculture is used to compensate for the long-term loss of soil fertility through erosion and organic matter loss. This leads to over a half billion dollars per year in extra fertilizer supply costs to US farmers. These results highlight the potential to reduce both the input costs and environmental impacts of agriculture through the restoration of SOM in agricultural soils

NASA in-house Commercially Developed Space Facility (CDSF) study report. Volume 1: Concept configuration definition

The results of a NASA in-house team effort to develop a concept definition for a Commercially Developed Space Facility (CDSF) are presented. Science mission utilization definition scenarios are documented, the conceptual configuration definition system performance parameters qualified, benchmark operational scenarios developed, space shuttle interface descriptions provided, and development schedule activity was assessed with respect to the establishment of a proposed launch date

Low body weight and involuntary weight loss are associated with Raynaud's phenomenon in both men and women

Objectives: Low body weight is an easily assessable cause of Raynaud’s phenomenon (RP), and is frequently overlooked by clinicians. We aim to investigate the association of low body weight (body mass index < 18.5 kg/m2), involuntary weight loss, and nutritional restrictions with the presence of RP. Method: Participants from the Lifelines Cohort completed a validated self-administered connective tissue disease questionnaire. Subjects who reported cold-sensitive fingers and biphasic or triphasic colour changes were considered to suffer from RP. Patient characteristics, anthropometric measurements, and nutritional habits were collected. Statistical analyses was stratified for gender. Results: Altogether, 93 935 participants completed the questionnaire. The prevalence of RP was 4.2% [95% confidence interval (CI) 4.1–4.4%], and was three-fold higher in women than in men (5.7% vs 2.1%, p < 0.001). Subjects with RP had a significantly lower daily caloric intake than those without RP. Multivariate analysis, correcting for creatinine level, daily caloric intake, and other known aetiological factors associated with RP, revealed that low body weight [men: odds ratio (OR) 5.55 (95% CI 2.82–10.93); women: 3.14 (2.40–4.10)] and involuntary weight loss [men: OR 1.32 (1.17–1.48); women: 1.31 (1.20–1.44)] were significantly associated with the presence of RP. Low-fat diet was also associated with RP in women [OR 1.27 (1.15–1.44)]. Conclusion: Low body weight and prior involuntary weight loss are associated with an increased risk of RP in both men and women. This study emphasizes that low body weight and weight loss are easily overlooked risk factors for RP, and should be assessed and monitored in subjects with RP

Computational Methods to Study Kinetics of DNA Replication

New technologies such as DNA combing have led to the availability of large quanti-ties of data that describe the state of DNA while undergoing replication in S phase. In this chapter, we describe methods used to extract various parameters of replica-tion — fork velocity, origin initiation rate, fork density, numbers of potential and utilized origins — from such data. We first present a version of the technique that applies to “ideal ” data. We then show how to deal with a number of real-world complications, such as the asynchrony of starting times of a population of cells, the finite length of fragments used in the analysis, and the finite amount of DNA in a chromosome. Key words: DNA replication, replication fork velocity, origin initiation