3,072 research outputs found
Early onset preeclampsia is characterized by altered placental lipid metabolism and a premature increase in circulating FABP4
Preeclampsia is a pregnancy-associated disorder that manifests as a sudden increase in maternal blood pressure accompanied by proteinuria. Because the placenta is a key organ in preeclampsia, we used proteomic and lipidomic analyses to compare placentae from preeclamptic and gestational age matched control pregnancies. Fatty acid binding protein 4 (FABP4), enoyl-CoA dehydrogenase and delta-3,5-delta-2,4-dienoyl-CoA isomerase had altered abundance in preeclamptic placentae compared to controls. FABP4 placental protein and RNA and plasma levels were all increased in early-onset preeclampsia (prior to 28 weeks gestation) compared to controls (6-fold, 3.3-fold and 3.5-fold respectively). After 28 weeks, FABP4 protein in control placenta and plasma increased to the same concentrations as in preeclampsia. Total tetracosapentaenoic acid in preeclamptic placentae was decreased to 0.6 of control levels before 28 weeks. The data indicate a disruption of fatty acid transport and metabolism in the placenta in early onset preeclampsia that is reflected in the maternal plasma
Classification of Classical Spin Liquids: Topological Quantum Chemistry and Crystalline Symmetry
Frustrated magnetic systems can host highly interesting phases known as
classical spin liquids (CSLs), which feature {extensive} ground state
degeneracy and lack long-range magnetic order. Recently, Yan and Benton et al.
proposed a classification scheme of CSLs in the large- (soft spin)
limit [arXiv.2305.00155], [arXiv:2305.19189]. This scheme classifies CSLs into
two categories: the algebraic CSLs and the fragile topological CSLs, each with
their own correlation properties, low energy effective description, and finer
classification frameworks. In this work, we further develop the classification
scheme by considering the role of crystalline symmetry. We present a
mathematical framework for computing the band representation of the flat bands
in the spectrum of these CSLs, which extends beyond the conventional
representation analysis. It allows one to determine whether the algebraic CSLs,
which features gapless points on their bottom flat bands, are protected by
symmetry or not. It also provides more information on the finer classifications
of algebraic and fragile topological CSLs. We demonstrate this framework via
concrete examples and showcase its power by constructing a pinch-line algebraic
CSL protected by symmetry.Comment: 12 pages, 4 pages. Third paper in the series of [arXiv.2305.00155],
[arXiv:2305.19189
Size-Specific Tree Mortality Varies with Neighbourhood Crowding and Disturbance in a Montane Nothofagus Forest
Tree mortality is a fundamental process governing forest dynamics, but understanding tree mortality patterns is challenging because large, long-term datasets are required. Describing size-specific mortality patterns can be especially difficult, due to few trees in larger size classes. We used permanent plot data from Nothofagus solandri var. cliffortioides (mountain beech) forest on the eastern slopes of the Southern Alps, New Zealand, where the fates of trees on 250 plots of 0.04 ha were followed, to examine: (1) patterns of size-specific mortality over three consecutive periods spanning 30 years, each characterised by different disturbance, and (2) the strength and direction of neighbourhood crowding effects on size-specific mortality rates. We found that the size-specific mortality function was U-shaped over the 30-year period as well as within two shorter periods characterised by small-scale pinhole beetle and windthrow disturbance. During a third period, characterised by earthquake disturbance, tree mortality was less size dependent. Small trees (<20 cm in diameter) were more likely to die, in all three periods, if surrounded by a high basal area of larger neighbours, suggesting that size-asymmetric competition for light was a major cause of mortality. In contrast, large trees (≥20 cm in diameter) were more likely to die in the first period if they had few neighbours, indicating that positive crowding effects were sometimes important for survival of large trees. Overall our results suggest that temporal variability in size-specific mortality patterns, and positive interactions between large trees, may sometimes need to be incorporated into models of forest dynamics
Neural Indices of Vowel Discrimination in Monolingual and Bilingual Infants and Children
Objectives: To examine maturation of neural discriminative responses to an English vowel contrast from infancy to 4 years of age and to determine how biological factors (age and sex) and an experiential factor (amount of Spanish versus English input) modulate neural discrimination of speech.
Design: Event-related potential (ERP) mismatch responses (MMRs) were used as indices of discrimination of the American English vowels [ε] versus [I] in infants and children between 3 months and 47 months of age. A total of 168 longitudinal and cross-sectional data sets were collected from 98 children (Bilingual Spanish–English: 47 male and 31 female sessions; Monolingual English: 48 male and 42 female sessions). Language exposure and other language measures were collected. ERP responses were examined in an early time window (160 to 360 msec, early MMR [eMMR]) and late time window (400 to 600 msec, late MMR).
Results: The eMMR became more negative with increasing age. Language experience and sex also influenced the amplitude of the eMMR. Specifically, bilingual children, especially bilingual females, showed more negative eMMR compared with monolingual children and with males. However, the subset of bilingual children with more exposure to English than Spanish compared with those with more exposure to Spanish than English (as reported by caretakers) showed similar amplitude of the eMMR to their monolingual peers. Age was the only factor that influenced the amplitude of the late MMR. More negative late MMR was observed in older children with no difference found between bilingual and monolingual groups.
Conclusions: Consistent with previous studies, our findings revealed that biological factors (age and sex) and language experience modulated the amplitude of the eMMR in young children. The early negative MMR is likely to be the mismatch negativity found in older children and adults. In contrast, the late MMR amplitude was influenced only by age and may be equivalent to the Nc in infants and to the late negativity observed in some auditory passive oddball designs
Two-stage analyses of sequence variants in association with quantitative traits
We propose a two-stage design for the analysis of sequence variants in which a proportion of genes that show some evidence of association are identified initially and then followed up in an independent data set. We compare two different approaches. In both approaches the same summary measure (total number of minor alleles) is used for each gene in the initial analysis. In the first (simple) approach the same summary measure is used in the analysis of the independent data set. In the second (alternative) approach a more specific hypothesis is formed for the second stage; the summary measure used is the count of minor alleles in only those variants that in the initial data showed the same direction of association as was seen overall. We applied the methods to the simulated quantitative traits of Genetic Analysis Workshop 17, blind to the simulation model, and then evaluated their performance once the underlying model was known. Performance was similar for most genes, but the simple strategy considerably out-performed the alternative strategy for one gene, where most of the effect was due to very rare variants; this suggests that the alternative approach would not be advisable when the effect is seen in very rare variants. Further simulations are needed to investigate the potential superior power of the alternative method when some variants within a gene have opposing effects. Overall, the power to detect associations was low; this was also true when using a more powerful joint analysis that combined the two stages of the study
Surgeon choice in the use of postdischarge antibiotics for prophylaxis following mastectomy with and without breast reconstruction
Multiple guidelines recommend discontinuation of prophylactic antibiotics \u3c24 hours after surgery. In a multicenter, retrospective cohort of 2,954 mastectomy patients ± immediate breast reconstruction, we found that utilization of prophylactic postdischarge antibiotics varied dramatically at the surgeon level among general surgeons and was virtually universal among plastic surgeons
Postdischarge antibiotic use for prophylaxis following spinal fusion
OBJECTIVE: Despite recommendations to discontinue prophylactic antibiotics after incision closure or \u3c24 hours after surgery, prophylactic antibiotics are continued after discharge by some clinicians. The objective of this study was to determine the prevalence and factors associated with postdischarge prophylactic antibiotic use after spinal fusion.
DESIGN: Multicenter retrospective cohort study.
PATIENTS: This study included patients aged ≥18 years undergoing spinal fusion or refusion between July 2011 and June 2015 at 3 sites. Patients with an infection during the surgical admission were excluded.
METHODS: Prophylactic antibiotics were identified at discharge. Factors associated with postdischarge prophylactic antibiotic use were identified using hierarchical generalized linear models.
RESULTS: In total, 8,652 spinal fusion admissions were included. Antibiotics were prescribed at discharge in 289 admissions (3.3%). The most commonly prescribed antibiotics were trimethoprim/sulfamethoxazole (22.1%), cephalexin (18.8%), and ciprofloxacin (17.1%). Adjusted for study site, significant factors associated with prophylactic discharge antibiotics included American Society of Anesthesiologists (ASA) class ≥3 (odds ratio [OR], 1.31; 95% CI, 1.00-1.70), lymphoma (OR, 2.57; 95% CI, 1.11-5.98), solid tumor (OR, 3.63; 95% CI, 1.62-8.14), morbid obesity (OR, 1.64; 95% CI, 1.09-2.47), paralysis (OR, 2.38; 95% CI, 1.30-4.37), hematoma/seroma (OR, 2.93; 95% CI, 1.17-7.33), thoracic surgery (OR, 1.39; 95% CI, 1.01-1.93), longer length of stay, and intraoperative antibiotics.
CONCLUSIONS: Postdischarge prophylactic antibiotics were uncommon after spinal fusion. Patient and perioperative factors were associated with continuation of prophylactic antibiotics after hospital discharge
Ampullary cancers harbor ELF3 tumor suppressor gene mutations and exhibit frequent WNT dysregulation
The ampulla of Vater is a complex cellular environment from which adenocarcinomas arise to form a group of histopathologically heterogenous tumors. To evaluate the molecular features of these tumors, 98 ampullary adenocarcinomas were evaluated and compared to 44 distal bile duct and 18 duodenal adenocarcinomas. Genomic analyses revealed mutations in the WNT signaling pathway among half of the patients and in all three adenocarcinomas irrespective of their origin and histological morphology. These tumors were characterized by a high frequency of inactivating mutations of ELF3, a high rate of microsatellite instability, and common focal deletions and amplifications, suggesting common attributes in the molecular pathogenesis are at play in these tumors. The high frequency of WNT pathway activating mutation, coupled with small-molecule inhibitors of β-catenin in clinical trials, suggests future treatment decisions for these patients may be guided by genomic analysis
Are Iraq and Afghanistan Veterans Using Mental Health Services? New Data From a National Random-Sample Survey
This study analyzed data from a national survey of Iraq and Afghanistan veterans to improve understanding of mental health services use and perceived barriers
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