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Realce por contraste de les？es hepáticas em pacientes com cirrose: estudo cruzado comparativo de dois agentes de contraste para RM realizado em uma única institui？？o. Resultados preliminares
Burke, Lauren M. B.;Vachiranubhap, Busakorn;Tannaphai, Penampai;Semelka, Richard C.;
Radiologia Brasileira , 2011, DOI: 10.1590/S0100-39842011000300005
Abstract: objective: to prospectively compare full dose gadopentetate dimeglumine (gd-dtpa) with full dose gadobenate dimeglumine (gd-bopta) in the detection of focal hepatic lesions in patients with chronic liver disease on mri. materials and methods: eight patients with hepatic cirrhosis and a strong suspicion for small hepatocellular carcinoma based on prior mri underwent contrast-enhanced mr examinations, one with full dose gd-dtpa and one with full dose gd-bopta. the exams were performed from 72-108 hours apart. two blinded and independent radiologists evaluated images for lesion number, characterization, enhancement, and subjective preference. results: there was no statistically significant difference between the two studies for lesion detection or characterization. there was 18% increased lesion enhancement for gd-bopta, compared to gd-dtpa, of the dominant lesion. both blinded readers subjectively preferred the images using gd-bopta over gd-dtpa in the majority of cases, based on greater lesion enhancement and better edge definition. conclusion: at equivalent full doses, gd-bopta compared similarly with gd-dtpa in the detection and characterization of focal hepatic lesions in patients with chronic liver disease. however, gd-bopta was superior for increased lesion enhancement and subjective preference of the reader.
Hemangioma hepático subcapsular com realce perilesional: achados de RM
Kim, Young Hoon;Shin, Sang Soo;Burke, Lauren M. B;Lee, Chang Hee;Ku, Young Mi;Vachiranubhap, Busakorn;Semelka, Richard C;
Radiologia Brasileira , 2010, DOI: 10.1590/S0100-39842010000600010
Abstract: objective: to describe the mr imaging features of hepatic hemangioma with perilesional enhancement. materials and methods: a search was performed of the mri section database to identify all cases of hepatic hemangioma with perilesional enhancement between march 2008 and july 2009. all patients underwent mr examinations including precontrast t1- and t2-weighted images and postgadolinium dynamic images. on mr images, characteristics of the hemangioma and perilesional enhancement were evaluated. results: seven hemangiomas in seven patients (five men, two women; age range, 41-69 years; mean, 57 years) were included in this study. lesion size ranged from 7 to 20 mm (mean, 12.4 mm). on hepatic arterial dominant phase, all seven hemangiomas exhibited wedge-shaped perilesional enhancement which faded on two minutes postgadolinium images. four of these lesions demonstrated adjacent capsular enhancement. conclusion: all hepatic hemangiomas with perilesional enhancement were < 2 cm capsule-based lesions. this location suggests that these hemangiomas may conscript capsular vessels to account for the perilesional enhancement
Evolution of the sugar receptors in insects
Lauren B Kent, Hugh M Robertson
BMC Evolutionary Biology , 2009, DOI: 10.1186/1471-2148-9-41
Abstract: While most Drosophila species retain all eight genes, we find that the three Drosophila subgenus species have lost Gr64d, while D. grimshawi and the D. pseudoobscura/persimilis sibling species have also lost Gr5a function. The entire Gr64 gene complex was also duplicated in the D. grimshawi lineage, but only one potentially functional copy of each gene has been retained. The numbers of SRs range from two in the hymenopterans Apis mellifera and Nasonia vitripennis to 16 in the beetle Tribolium castaneum. An unusual aspect is the evolution of a novel exon from intronic sequence in an expanded set of four SRs in Bombyx mori (BmGr5-8), which appears to be the first example of such exonization in insects. Twelve intron gains and 63 losses are inferred within the SR family.Examination of the SRs in these fly, mosquito, moth, beetle, and hymenopteran genome sequences reveals that they appear to have originated independently from single ancestral genes within the dipteran and coleopteran lineages, and two genes in the lepidopteran and hymenopteran lineages. The origin of the insect SRs will eventually be illuminated by additional basal insect and arthropod genome sequences.Sugars serve as some of the simplest, most easily metabolized forms of energy available to life. For example, despite an anautogenous female mosquito's need for a bloodmeal to nourish her developing eggs, it is the simple nectar of plants that fuels her flight muscles and daily energy needs. As sugar is a valuable resource, it seems fitting that most animals have the ability to taste sugars, and in many it forms a primary stimulatory signal for feeding. The molecular basis for sugar detection in insects has been revealed in Drosophila melanogaster where it involves a series of at least eight genes in the gustatory receptor (Gr) family [1-3]. The first of these is Gr5a on the X chromosome, although identification of this gene as encoding a trehalose receptor was initially confused with the neighboring Tre
Rethinking autonomy: decision making between patient and surgeon in advanced illnesses
Daniel B. Hinshaw,Lauren M. Wancata
- , 2016, DOI: 10.3978/j.issn.2305-5839.2016.01.36
Abstract:
Stochastic Search with an Observable State Variable
Lauren A. Hannah,Warren B. Powell,David M. Blei
Mathematics , 2010,
Abstract: In this paper we study convex stochastic search problems where a noisy objective function value is observed after a decision is made. There are many stochastic search problems whose behavior depends on an exogenous state variable which affects the shape of the objective function. Currently, there is no general purpose algorithm to solve this class of problems. We use nonparametric density estimation to take observations from the joint state-outcome distribution and use them to infer the optimal decision for a given query state. We propose two solution methods that depend on the problem characteristics: function-based and gradient-based optimization. We examine two weighting schemes, kernel-based weights and Dirichlet process-based weights, for use with the solution methods. The weights and solution methods are tested on a synthetic multi-product newsvendor problem and the hour-ahead wind commitment problem. Our results show that in some cases Dirichlet process weights offer substantial benefits over kernel based weights and more generally that nonparametric estimation methods provide good solutions to otherwise intractable problems.
Dirichlet Process Mixtures of Generalized Linear Models
Lauren A. Hannah,David M. Blei,Warren B. Powell
Statistics , 2009,
Abstract: We propose Dirichlet Process mixtures of Generalized Linear Models (DP-GLM), a new method of nonparametric regression that accommodates continuous and categorical inputs, and responses that can be modeled by a generalized linear model. We prove conditions for the asymptotic unbiasedness of the DP-GLM regression mean function estimate. We also give examples for when those conditions hold, including models for compactly supported continuous distributions and a model with continuous covariates and categorical response. We empirically analyze the properties of the DP-GLM and why it provides better results than existing Dirichlet process mixture regression models. We evaluate DP-GLM on several data sets, comparing it to modern methods of nonparametric regression like CART, Bayesian trees and Gaussian processes. Compared to existing techniques, the DP-GLM provides a single model (and corresponding inference algorithms) that performs well in many regression settings.
Inflammatory Proteins Predict Change in Depressive Symptoms in Male and Female Adolescents
Christopher L. Coe,Daniel P. Moriarity,Joshua Klugman,Lauren B. Alloy,Lauren M. Ellman,Lyn Y. Abramson,Naoise Mac Giollabhui
- , 2019, DOI: 10.1177/2167702619826586
Abstract: Inflammation has been implicated in depressive symptoms, but few studies use longitudinal designs with adolescents. Furthermore, the extant literature has yielded inconsistent results. Blood was collected from a community sample of 201 adolescents (109 female, age range = 12.3–20.0 years) and analyzed for inflammatory proteins. Up to five follow-up assessments of depressive symptoms were conducted. Multilevel modeling indicated that high C-reactive protein (CRP) but no other proinflammatory markers predicted depressive symptom increases. Three-way interactions between different inflammatory biomarkers, sex, and months to follow-up predicted change in depressive symptoms. Higher interleukin-6 predicted increased depressive symptoms at 13 to 31 months after baseline assessment of depression and inflammation for females. Higher tumor necrosis factor-α predicted increased depressive symptoms at < 1 month after baseline for males and 13 to 31 months after baseline for females. Higher interleukin-8 in males predicted lower depressive symptoms at 31 months after baseline. Exploratory post hoc analyses were used to examine these predictive associations for specific subsets of depressive symptoms. These findings are the first to support the predictive association of elevated CRP for depressive symptoms in a community adolescent sample and serve as preliminary evidence that the relationship between cytokines and later depressive symptoms differs by sex, time to follow-up, and the specific biomarker
Effects of Fluctuating Daily Temperatures at Critical Thermal Extremes on Aedes aegypti Life-History Traits
Lauren B. Carrington, M. Veronica Armijos, Louis Lambrechts, Christopher M. Barker, Thomas W. Scott
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0058824
Abstract: Background The effect of temperature on insect biology is well understood under constant temperature conditions, but less so under more natural, fluctuating conditions. A fluctuating temperature profile around a mean of 26°C can alter Aedes aegypti vector competence for dengue viruses as well as numerous life-history traits, however, the effect of fluctuations on mosquitoes at critical thermal limits is unknown. Methodology/Principal Findings We investigated the effects of large and small daily temperature fluctuations at low (16°C) and high (35–37°C) mean temperatures, after we identified these temperatures as being thresholds for immature development and/or adult reproduction under constant temperature conditions. We found that temperature effects on larval development time, larval survival and adult reproduction depend on the combination of mean temperature and magnitude of fluctuations. Importantly, observed degree-day estimates for mosquito development under fluctuating temperature profiles depart significantly (around 10–20%) from that predicted by constant temperatures of the same mean. At low mean temperatures, fluctuations reduce the thermal energy required to reach pupation relative to constant temperature, whereas at high mean temperatures additional thermal energy is required to complete development. A stage-structured model based on these empirical data predicts that fluctuations can significantly affect the intrinsic growth rate of mosquito populations. Conclusions/Significance Our results indicate that by using constant temperatures, one could under- or over-estimate values for numerous life-history traits compared to more natural field conditions dependent upon the mean temperature. This complexity may in turn reduce the accuracy of population dynamics modeling and downstream applications for mosquito surveillance and disease prevention.
The structure of allelic diversity in the presence of purifying selection
Michael M. Desai,Lauren E. Nicolaisen,Aleksandra M. Walczak,Joshua B. Plotkin
Quantitative Biology , 2010,
Abstract: In the absence of selection, the structure of allelic diversity is described by the elegant sampling formula of Ewens. This formula has helped shape our expectations of empirical patterns of molecular variation. Along with coalescent theory, it provides statistical techniques for rejecting the null model of neutrality. However, we still do not fully understand the statistics of the allelic diversity we expect to see in the presence of natural selection. Earlier work has described the effects of strongly deleterious mutations linked to many neutral sites, and allelic variation in models where offspring fitness is unrelated to parental fitness, but it has proven difficult to understand allelic diversity in the presence of purifying selection at many linked sites. Here, we study the population genetics of infinitely many perfectly linked sites, some neutral and some deleterious. Our approach is based on studying the lineage structure within each class of individuals of similar fitness in the deleterious mutation-selection balance. Analogous to the Ewens sampling formula, we derive expressions for the likelihoods of any configuration of allelic types in a sample. We find that for moderate and weak selection pressures the patterns of allelic diversity cannot be described by a neutral model for any choice of the effective population size, indicating that there is power to detect selection from patterns of sampled allelic diversity.
The Structure of Genealogies in the Presence of Purifying Selection: A "Fitness-Class Coalescent"
Aleksandra M. Walczak,Lauren E. Nicolaisen,Joshua B. Plotkin,Michael M. Desai
Quantitative Biology , 2010,
Abstract: Compared to a neutral model, purifying selection distorts the structure of genealogies and hence alters the patterns of sampled genetic variation. Although these distortions may be common in nature, our understanding of how we expect purifying selection to affect patterns of molecular variation remains incomplete. Genealogical approaches such as coalescent theory have proven difficult to generalize to situations involving selection at many linked sites, unless selection pressures are extremely strong. Here, we introduce an effective coalescent theory (a "fitness-class coalescent") to describe the structure of genealogies in the presence of purifying selection at many linked sites. We use this effective theory to calculate several simple statistics describing the expected patterns of variation in sequence data, both at the sites under selection and at linked neutral sites. Our analysis combines our earlier description of the allele frequency spectrum in the presence of purifying selection (Desai et al. 2010) with the structured coalescent approach of Nordborg (1997), to trace the ancestry of individuals through the distribution of fitnesses within the population. Alternatively, we can derive our results using an extension of the coalescent approach of Hudson and Kaplan (1994). We find that purifying selection leads to patterns of genetic variation that are related but not identical to a neutrally evolving population in which population size has varied in a specific way in the past.
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