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1

Epidemiology of neural tube defects.  

PubMed

Neural tube defects (NTDs)-malformations secondary to abnormal neural tube closure between the third and fourth weeks of gestational age-have a complex and imperfectly understood etiology in which both genetic and environmental factors appear to be involved. A number of specific chromosomal or single-gene disorders, presumably not affected by environmental influences, are associated with the development of NTDs, but such syndromal cases account for a small proportion of NTDs in live-born infants. Analysis of recurrence patterns within families and of twin-concordance data provides evidence of a genetic influence in nonsyndromal cases, but factors such as socioeconomic status and geographic area (independent of race or ethnicity) are also associated with variations in the incidence of NTDs. The prevalence at birth of both anencephaly and spina bifida has decreased, but the advent of antenatal diagnosis and elective termination of affected pregnancies has undermined the reliability of birth prevalence rate as an estimate of incidence. Some occupational and other exposures, including maternal use of antiepileptic drugs (AEDs), are associated with increased risk for NTDs. Among women who have had an NTD-affected pregnancy, recurrence risk is markedly higher than the risk for a first NTD-affected pregnancy in the general population. There is strong evidence, overall, for a protective effect of adequate folate consumption. In some high-risk groups, however, such as women taking AEDs, folate supplementation has not been proven to reduce NTD risk. PMID:12790881

Frey, Lauren; Hauser, W Allen

2003-01-01

2

Neural tube defects and folate: case far from closed  

Microsoft Academic Search

Neural tube closure takes place during early embryogenesis and requires interactions between genetic and environmental factors. Failure of neural tube closure is a common congenital malformation that results in morbidity and mortality. A major clinical achievement has been the use of periconceptional folic acid supplements, which prevents ?50–75% of cases of neural tube defects. However, the mechanism underlying the beneficial

Gary M. Shaw; Martin den Heijer; Richard H. Finnell; Henk J. Blom

2006-01-01

3

Neural tube defects, folic acid and methylation.  

PubMed

Neural tube defects (NTDs) are common complex congenital malformations resulting from failure of the neural tube closure during embryogenesis. It is established that folic acid supplementation decreases the prevalence of NTDs, which has led to national public health policies regarding folic acid. To date, animal studies have not provided sufficient information to establish the metabolic and/or genomic mechanism(s) underlying human folic acid responsiveness in NTDs. However, several lines of evidence suggest that not only folates but also choline, B12 and methylation metabolisms are involved in NTDs. Decreased B12 vitamin and increased total choline or homocysteine in maternal blood have been shown to be associated with increased NTDs risk. Several polymorphisms of genes involved in these pathways have also been implicated in risk of development of NTDs. This raises the question whether supplementation with B12 vitamin, betaine or other methylation donors in addition to folic acid periconceptional supplementation will further reduce NTD risk. The objective of this article is to review the role of methylation metabolism in the onset of neural tube defects. PMID:24048206

Imbard, Apolline; Benoist, Jean-François; Blom, Henk J

2013-09-01

4

Double neural tube defect: a case report and discussions on neural tube development  

Microsoft Academic Search

Objective  Double neural tube defect is a rare congenital problem. A case illustration and current literatures on neural tube closure\\u000a theory are discussed. The available theories are summarised and compared with regard to the case report.\\u000a \\u000a \\u000a \\u000a \\u000a Case report  A preterm baby with a parietal encephalocele and thoracic myelomeningocele is reported and management described. A two-staged\\u000a surgery was performed.\\u000a \\u000a \\u000a \\u000a \\u000a Conclusion  The present case, the

Ravindran Vashu; Ngian San Liew

2010-01-01

5

Genetic, epigenetic, and environmental contributions to neural tube closure.  

PubMed

The formation of the embryonic brain and spinal cord begins as the neural plate bends to form the neural folds, which meet and adhere to close the neural tube. The neural ectoderm and surrounding tissues also coordinate proliferation, differentiation, and patterning. This highly orchestrated process is susceptible to disruption, leading to neural tube defects (NTDs), a common birth defect. Here, we highlight genetic and epigenetic contributions to neural tube closure. We describe an online database we created as a resource for researchers, geneticists, and clinicians. Neural tube closure is sensitive to environmental influences, and we discuss disruptive causes, preventative measures, and possible mechanisms. New technologies will move beyond candidate genes in small cohort studies toward unbiased discoveries in sporadic NTD cases. This will uncover the genetic complexity of NTDs and critical gene-gene interactions. Animal models can reveal the causative nature of genetic variants, the genetic interrelationships, and the mechanisms underlying environmental influences. PMID:25292356

Wilde, Jonathan J; Petersen, Juliette R; Niswander, Lee

2014-11-23

6

Risk Factors of Neural Tube Defects in Northern Iran  

PubMed Central

Background: Neural tube defects (NTDs) including spina bifida and anencephaly are the second most common birth defects with 2.8 per 1000 births in northern Iran. Objectives: This study was conducted to determine the risk factors of neural tube defects in Gorgan, north of Iran. Patients and Methods: This hospital-based, case-control study was carried out on all NTD-affected pregnancies (n = 59) during February 2007 - August 2010, and 160 healthy pregnancies were selected via convenient sampling method in three hospitals in Gorgan, north of Iran. Risk factors including maternal body mass index (BMI), season of birth, gender of the newborn, mother’s age, ethnicity, consanguineous marriage, folic acid consumption, nutrition, habitat, and education, were assessed through interviews with mothers. Univariate and multivariate logistic regression analyses were used to estimate the risks by odds ratios (ORs) and 95% confidence intervals. Results: The multivariate analysis showed that maternal BMI (normal/underweight OR: 0.23, overweight/underweight OR: 0.15, obese/underweight OR: 0.13) and maternal ethnicity (Fars/Sistani OR: 3.49) and maternal nutrition (good/poor OR: 0.46) were significantly correlated with NTDs in the newborns. Conclusions: This study showed that maternal ethnicity, insufficient nutrition, and BMI, were the main risk factors of NTDs in northern Iran. PMID:25068063

Golalipour, Mohammad Jafar; Qorbani, Mostafa; Mirfazeli, Arezo; Mobasheri, Elham

2014-01-01

7

Neural tissue continues its maturation at the site of neural tube closure defects: implications for prenatal intervention in human samples  

Microsoft Academic Search

Objective Our objective was to investigate the relation between the embryological development and neural tissue maturation at the site where the neural plate failed to form a neural tube. Material and methods Samples from 15 aborted human fetuses with neural tube defects (NTD). All of the fetuses were between 20 and 25 gestational weeks old. Indicators of neural tissue maturation,

Mehmet Selçuki; Seda Vatansever; Sevinç Inan; Muzaffer Sanc?; Sevil Sayhan; Celal Ba?dato?lu

2004-01-01

8

Images in Clinical Medicine Congenital Neural Malformations Related to Their Embryological Background  

PubMed Central

Congenital neural malformations are complex anomalies, which stem from an abnormality in the embryological development of the nervous system. The development of the nervous system begins by the formation of the neural tube and its subsequent closure. The failure of closure results in neural tube defects (NTD). Defect in the formation of prosencehalon or rhombencephalon will result in holoprosencephaly or Dandy walker complex respectively. The formation of neuroblasts and their migration to cerebral cortex may be altered by many neuronal migration disorders. Lissencephaly, schizencephaly, and heterotopic gray matter are the most prominent. Conclusion: The objective of the study is relating congenital neural malformations to their corresponding embryological background, and so helping in better understanding the time and the way of the occurrence of such anomalies. PMID:21475482

Bahnassy, Ahmed A.; Aly, Nehal N.

2008-01-01

9

Reconstruction of neural tube-like structures in vitro from primary neural precursor cells.  

PubMed Central

Vertebrate central nervous system develops from a neural tube derived from the embryonic ectoderm. In mouse, the neural tube around embryonic day 10 primarily consists of neural precursor cells (NPCs). During the development of embryonic central nervous system, NPCs proliferate and migrate outward; thus later stages show NPCs toward the lumen of the neural tube and neurofilament-positive differentiated cells toward the periphery. In conventional liquid culture, NPCs isolated from mouse on embryonic day 10 proliferate and differentiate into neurofilament-positive neurons. In the present communication, we show that fragments of neural tubes and aggregates of NPCs, when placed into collagen gel matrix, form three-dimensional structures which resemble the neural tube formed in vivo in the developing embryos. Even dissociated NPCs form the three-dimensional structures in the collagen gel matrix. Our results indicate that individual NPCs or fragments of neural tubes carry morphogenetic information which allows them to reconstruct neural tube-like structures in vitro. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 PMID:8415762

Tomooka, Y; Kitani, H; Jing, N; Matsushima, M; Sakakura, T

1993-01-01

10

Periconceptional Folate Deficiency and Implications in Neural Tube Defects  

PubMed Central

Nutritional deficiencies are preventable etiological and epigenetic factors causing congenital abnormalities, first cause of infant mortality. Folate deficiency has a well-established teratogenic effect, leading to an increasing risk of neural tube defects. This paper highlights the most recent medical literature about folate deficiency, be it maternal or paternal. It then focuses on associated deficiencies as nutritional deficiencies are multiple and interrelated. Observational and interventional studies have all been consistent with a 50–70% protective effect of adequate women consumption of folates on neural tube defects. Since strategies to modify women's dietary habits and vitamin use have achieved little progress, scientific as well as political effort is mandatory in order to implement global preventive public health strategies aimed at improving the alimentation of women in reproductive age, especially folic acid supplementation. Even with the recent breakthrough of fetal surgery for myelomeningocele, the emphasis should still be on prevention as the best practice rather than treatment of neural tube defects. PMID:22900183

Safi, J.; Joyeux, L.; Chalouhi, G. E.

2012-01-01

11

Screening for fetal aneuploidy and neural tube defects  

PubMed Central

Maternal serum screening for neural tube defects and fetal aneuploidy in the second trimester has been incorporated into obstetrical practice over the past two decades. Now, as a result of several multicenter trials, first trimester screening between 11 and 14 weeks has been shown to be an effective and reliable screening test for Down syndrome and trisomy 18. This policy updates the American College of Medical Genetics policy statement entitled Second Trimester Maternal Serum Screening for Fetal Open Neural Tube Defects and Aneuploidy (2004), incorporates First trimester diagnosis and screening for fetal aneuploidy (2008) and complements the sections of American College of Medical Genetic’s Standards and Guidelines for Clinical Genetics Laboratories entitled Prenatal Screening for Down syndrome (2005) and Prenatal Screening for Open Neural Tube Defects (2005). PMID:19915395

Driscoll, Deborah A.; Gross, Susan J.

2009-01-01

12

Genes encoding critical transcriptional activators for murine neural tube development and human spina bifida: a case-control study  

Microsoft Academic Search

BACKGROUND: Spina bifida is a malformation of the neural tube and is the most common of neural tube defects (NTDs). The etiology of spina bifida is largely unknown, although it is thought to be multi-factorial, involving multiple interacting genes and environmental factors. Mutations in transcriptional co-activator genes-Cited2, p300, Cbp, Tfap2?, Carm1 and Cart1 result in NTDs in murine models, thus

Wei Lu; Adrian R Guzman; Wei Yang; Claudia J Chapa; Gary M Shaw; Robert M Greene; M Michele Pisano; Edward J Lammer; Richard H Finnell; Huiping Zhu

2010-01-01

13

Epidemiology of neural tube defects and folic acid  

PubMed Central

This review article combines four disparate observations about Neural Tube Defects (NTDs). They are the worldwide decline in the birth incidence that began prior to prenatal diagnosis; family recurrence risks; the effect of prenatal diagnosis and termination of affected pregnancies; and the effect of folic acid. PMID:15679939

Shurtleff, David B

2004-01-01

14

Prevention of Neural Tube Defects. ARC Q&A #101-45.  

ERIC Educational Resources Information Center

This fact sheet uses a question-and-answer format to summarize issues related to the prevention of neural tube defects. Questions and answers address the following topics: what neural tube defects are and the most common types (spina bifida and anencephaly); occurrence of neural tube defects during the first month of pregnancy; the frequency of…

Arc, Arlington, TX.

15

Neural Tube Defect Genes and Maternal Diabetes during Pregnancy  

PubMed Central

BACKGROUND Maternal diabetes during pregnancy is a well-known teratogen that increases the risk for birth defects, such as neural tube defects (NTDs). We have previously shown that maternal diabetes profoundly affects gene expression in the developing embryo, in particular a suite of known NTD genes. In rodent experimental systems, NTDs present as phenotypes of incomplete penetrance in diabetic pregnancies. This property is difficult to reconcile with observations of consistently altered gene expression in exposed embryos. We here show that maternal diabetes increases the overall variability of gene expression levels in embryos. RESULTS Altered gene expression and increased variability of gene expression together may constitute the molecular correlates for incomplete phenotype penetrance. DISCUSSION Based on this model, we suggest that maternal diabetes reduces the precision of gene regulation in exposed individuals. Loss of precision in embryonic gene regulation may include changes to the epigenome via deregulated expression of chromatin-modifying factors. Unraveling the mechanisms underlying such epigenetic modifications in diabetic pregnancies will help to understand how teratogenic insults compromise embryonic development and possibly provide avenues for therapeutic intervention. PMID:20564432

Salbaum, J. Michael; Kappen, Claudia

2012-01-01

16

Maternal Stress, Social Support, and Risk of Neural Tube Defects Among Mexican Americans  

Microsoft Academic Search

Background: Studies suggest that maternal psychologic stress can increase the risk of congenital malformations, including neural tube defects (NTDs). We examined whether maternal stress and lack of social support contribute to NTD risk in a population living along the Texas-Mexico border. Methods: Case mothers (N 184) were Mexican-American wo- men with NTD-affected pregnancies who delivered during 1995 to 2000 in

Lucina Suarez; Kathryn Cardarelli; Kate Hendricks

2003-01-01

17

Neural tube defects – recent advances, unsolved questions and controversies  

PubMed Central

Neural tube defects (NTDs) are severe congenital malformations affecting around 1 in every 1000 pregnancies. Here we review recent advances and currently unsolved issues in the NTD field. An innovation in clinical management has come from the demonstration that closure of open spina bifida lesions in utero can diminish neurological dysfunction in children. Primary prevention by folic acid has been enhanced through introduction of mandatory food fortification in some countries, although not yet in UK. Genetic predisposition comprises the majority of NTD risk, and genes that regulate folate one-carbon metabolism and planar cell polarity have been strongly implicated. The sequence of human neural tube closure events remains controversial, but study of mouse NTD models shows that anencephaly, open spina bifida and craniorachischisis result from failure of primary neurulation, while skin-covered spinal dysraphism results from defective secondary neurulation. Other ‘NTD’ malformations, such as encephalocele, are likely to be post-neurulation disorders. PMID:23790957

Copp, Andrew J.; Stanier, Philip; Greene, Nicholas D. E.

2014-01-01

18

Cats, frogs, and snakes: early concepts of neural tube defects.  

PubMed

Disturbed neurulation fascinated scientists of all times. In Egypt, anencephalic infants were venerated as animal-headed gods. Roman law required them to be killed. The medieval world held the mother responsible, either because of assumed imagination or "miswatching," or because of suspected intercourse with animals or devils. Modern embryology and teratology began with the use of the microscope by Malpighi in 1672. Details of neural tube closure were described by Koelliker in 1861 and by His in 1874. From 1822, genetic disease and familial recurrence due to insufficient nutrition were discerned and lower social class identified as a risk factor. It took a century to define the malnutrition as insufficient folate intake. The mandatory supplementation of folate in staple foods successfully reduced the incidence of neural tube defects in the United States, Australia, Canada, and Chile, but it was not adopted by most European countries. PMID:21730342

Obladen, Michael

2011-11-01

19

Novel Mutations in VANGL1 in Neural Tube Defects  

PubMed Central

Neural tube defects (NTDs) are severe congenital malformations caused by failure of the neural tube to close during neurulation. Their etiology is complex involving both environmental and genetic factors. We have recently reported three mutations in the planar cell polarity gene VANGL1 associated with NTDs. The aim of the present study was to define the role of VANGL1 genetic variants in the development of NTDs in a large cohort of various ethnic origins. We identified five novel missense variants in VANGL1, p.Ser83Leu, p.Phe153Ser, p.Arg181Gln, p.Leu202Phe and p.Ala404Ser, occurring in sporadic and familial cases of spinal dysraphisms. All five variants affect evolutionary conserved residues and are absent from all controls analyzed. This study provides further evidence supporting the role of VANGL1 as a risk factor in the development of spinal NTDs. PMID:19319979

Kibar, Zoha; Bosoi, Ciprian M.; Kooistra, Megan; Salem, Sandra; Finnell, Richard H.; Marco, Patrizia De; Merello, Elisa; Bassuk, Alexander G.; Capra, Valeria; Gros, Philippe

2010-01-01

20

Reduced folate carrier polymorphisms and neural tube defect risk  

Microsoft Academic Search

The reduced folate carrier (RFCI) is essential for folate transport into cells. Low folate is an important cause of neural tube defects (NTDs), and a single-nucleotide polymorphism (H27R) (80G?A) in the RFCI gene has been reported to be a NTD risk factor. We investigated H27R and a 61bp tandem repeat polymorphism as potential risk factors for NTDs, using a large

Valerie B. O’Leary; Faith Pangilinan; Christopher Cox; Anne Parle-McDermott; Mary Conley; Anne M. Molloy; Peadar N. Kirke; James L. Mills; Lawrence C. Brody; John M. Scott

2006-01-01

21

Analysis of the embryonic phenotype of Bent tail, a mouse model for X-linked neural tube defects.  

PubMed

Neural tube defects, mostly believed to result from closure defects of the neural tube during embryonic development, are frequently observed congenital malformations in humans. Since the etiology of these defects is not well understood yet, many animal models for neural tube defects, either arising from spontaneous mutations or generated by gene targeting, are being studied. The Bent tail mouse is a model for X-linked neural tube defects. This mutant has a characteristic short and kinked tail. Exencephaly occurs in Bent tail embryos with a frequency of 11-16%. Laterality defects also belong to the phenotypic spectrum. In this study, we analyzed the embryonic phenotype in further detail using scanning electron microscopy during the stages of neurulation. We observed a number of defects in both wild type and Bent tail embryos, including a kinked neural tube, tight amnion, delay in axial rotation and even malrotation. The severity or frequency of most defects, the delay in axial rotation excluded, was significantly higher in Bent tail embryos compared to wild type embryos. Other abnormalities were seen in Bent tail embryos only. These defects were related to anterior and posterior neural tube closure and resulted in exencephaly and a closure delay of the posterior neuropore, respectively. The exencephalic phenotype was further analyzed by light microscopy in ED14 embryos, showing disorganization and overgrowth in the mesencephalon and rhombencephalon. In conclusion, the anterior and posterior neural tube closure defects in the Bent tail are strictly linked to the genetic defect in this mouse. Other phenotypic features described in this study also occur in the wild type genetic background of the Bent tail strain. Apparently, the genetic background contains elements conducive to these developmental abnormalities. PMID:14523648

Franke, Barbara; Klootwijk, Riko; Hekking, Johan W M; de Boer, Roelie T; ten Donkelaar, Hans J; Mariman, Edwin C M; van Straaten, Henny W M

2003-10-01

22

Neural Tube Defects: Review of Experimental Evidence on Stem Cell Therapy and Newer Treatment Options  

Microsoft Academic Search

The failure of closure of the neural tube during development leads to malformations called neural tube defects (NTDs). The most common neural malformations in humans include anencephaly, encephalocele, exencephaly, craniorachischisis spina bifida with or without myelomeningocele, lipomyeloschisis, lipomyelomeningocele, meningocele and myelocystocele. Current preventive strategies are mainly based on pharmacologic\\/folic acid supplementation. However, stem cell-based and other combination approaches may emerge

Dhara B. Dhaulakhandi; Seema Rohilla; Kamal Nain Rattan

2010-01-01

23

Folic acid to reduce neonatal mortality from neural tube disorders  

PubMed Central

Background Neural tube defects (NTDs) remain an important, preventable cause of mortality and morbidity. High-income countries have reported large reductions in NTDs associated with folic acid supplementation or fortification. The burden of NTDs in low-income countries and the effectiveness of folic acid fortification/supplementation are unclear. Objective To review the evidence for, and estimate the effect of, folic acid fortification/supplementation on neonatal mortality due to NTDs, especially in low-income countries. Methods We conducted systematic reviews, abstracted data meeting inclusion criteria and evaluated evidence quality using adapted Grading of Recommendations, Assessment, Development and Evaluation (GRADE) methodology. Where appropriate, meta-analyses were performed. Results Meta-analysis of three randomized controlled trials (RCTs) of folic acid supplementation for women with a previous pregnancy with NTD indicates a 70% [95% confidence interval (CI): 35–86] reduction in recurrence (secondary prevention). For NTD primary prevention through folic acid supplementation, combining one RCT with three cohort studies which adjusted for confounding, suggested a reduction of 62% (95% CI: 49–71). A meta-analysis of eight population-based observational studies examining folic acid food fortification gave an estimated reduction in NTD incidence of 46% (95% CI: 37–54). In low-income countries an estimated 29% of neonatal deaths related to visible congenital abnormalities are attributed to NTD. Assuming that fortification reduces the incidence of NTDs, but does not alter severity or case-fatality rates, we estimate that folic acid fortification could prevent 13% of neonatal deaths currently attributed to congenital abnormalities in low-income countries. Discussion Scale-up of periconceptional supplementation programmes is challenging. Our final effect estimate was therefore based on folic acid fortification data. If folic acid food fortification achieved 100% population coverage the number of NTDs in low-income countries could be approximately halved. Conclusion The evidence supports both folic acid supplementation and fortification as effective in reducing neonatal mortality from NTDs. PMID:20348114

Blencowe, Hannah; Cousens, Simon; Modell, Bernadette; Lawn, Joy

2010-01-01

24

Further evidence for an intermittent pattern of neural tube closure in humans.  

PubMed Central

Evidence is presented to support the recent suggestion that human neural tube closure is similar to that observed in mice, and comprises several regionally distinct closure sites rather than being a simple zipping up process. Seven subjects, each with more than one neural tube defect (NTD), are described. Comparative studies of the location of the lesions in relation to the closed parts of the neural tube imply that such NTD could only have come about if there were intermittent closure of the neural tube. Images PMID:7783170

Seller, M J

1995-01-01

25

Contribution of VANGL2 mutations to isolated neural tube defects  

PubMed Central

Vangl2 was identified as the gene defective in the Looptail mouse model for neural tube defects (NTDs). This gene forms part of the planar cell polarity pathway, also called the non-canonical Frizzled/Dishevelled pathway, which mediates the morphogenetic process of convergent extension essential for proper gastrulation and neural tube formation in vertebrates. Genetic defects in PCP signaling have strongly been associated with NTDs in mouse models. To assess the role of VANGL2 in the complex etiology of NTDs in humans, we resequenced this gene in a large multi-ethnic cohort of 673 familial and sporadic NTD patients, including 453 open spina bifida and 202 closed spinal NTD cases. Six novel rare missense mutations were identified in 7 patients, five of which were affected with closed spinal NTDs. This suggests that VANGL2 mutations may predispose to NTDs in approximately 2.5% of closed spinal NTDs (5 in 202), at a frequency that is significantly different from that of 0.4% (2 in 453) detected in open spina bifida patients (P=0.027). Our findings strongly implicate VANGL2 in the genetic causation of spinal NTDs in a subset of patients and provide additional evidence for a pathogenic role of PCP signaling in these malformations. PMID:20738329

Kibar, Zoha; Salem, Sandra; Bosoi, Ciprian M.; Pauwels, Elodie; De Marco, Patrizia; Merello, Elisa; Bassuk, Alexander G; Capra, Valeria; Gros, Philippe

2010-01-01

26

The Relationship of Aluminium and Silver to Neural Tube Defects; a Case Control  

PubMed Central

Objective The purpose of this study was to identify the relationship of neurotoxic inorganic elements in the hair of patients with the diagnosis of Neural Tube Defects. Our initial hypothesis was that neurotoxic inorganic elements were associated with Neural Tube Defects. Methods Twenty-three samples of hair from newborns were obtained from the General Hospital, “Aurelio Valdivieso” in the city of Oaxaca, Mexico. The study group included 8 newborn infants with neural tube pathology. The control group was composed of 15 newborns without this pathology. The presence of inorganic elements in the hair samples was determined by inductively-coupled plasma spectroscopy (spectroscopic emission of the plasma). Findings The population of newborns with Neural Tube Defects showed significantly higher values of the following elements than the control group: Aluminium, Neural Tube Defects 152.77±51.06 µg/g, control group 76.24±27.89 µg/g; Silver, Neural Tube Defects 1.45±0.76, control group 0.25±0.53 µg/g; Potassium, Neural Tube Defects 553.87±77.91 µg/g, control group 341.13±205.90 µg/g. Association was found at 75 percentile between aluminium plus silver, aluminium plus potassium, silver plus potassium, and potassium plus sodium. Conclusion In the hair of newborns with Neural Tube Defects, the following metals were increased: aluminium, silver. Given the neurotoxicity of the same, and association of Neural Tube Defects with aluminum and silver, one may infer that they may be participating as factors in the development of Neural Tube Defects. PMID:23400307

Ramirez-Altamirano, Maria de Jesus; Fenton-Navarro, Patricia; Sivet-Chinas, Elvira; Harp-Iturribarria, Flor de Maria; Martinez-Cruz, Ruth; Cruz, Pedro Hernandez; Cruz, Margarito Martinez; Perez-Campos, Eduardo

2012-01-01

27

The relationship of ceruloplasmin and neural tube defects  

PubMed Central

Objective To compare the levels of ceruloplasmin (cp) in the amniotic fluids and maternal bloods of second trimester fetuses with and without neural tube defects (NTD). Materials and Methods 66 pregnant women were included in the study. Amniocentesis was performed in 32 women in a patient group diagnosed as NTD or anencephaly and 34 pregnants in a control group with positive Down Syndrome screening test. Maternal bloods were also taken. Cp was measured with Erel’s ceruloplasmin measurement method. Results The cp levels of the amniotic fluid of patients and controls were not statistically different (p>0.05). The cp levels of the maternal bloods were not different in two groups (p>0.05). Conclusion As an antioxidant, no relation was found between cp and NTD. PMID:24591905

Yaz?c?oglu, Caglar; Cebesoy, Fatma Bahar; Balat, Ozcan; Dikensoy, Ebru; Celik, Hakim; Erel, Ozcan

2010-01-01

28

Health promotion in a primary health care setting. Neural tube defects and folate.  

PubMed

Primary care practitioners are ideally situated to carry out health promotion activities. Neural tube defects are of a fairly low incidence, but the consequences are tragic. They range from life long physical and often intellectual disabilities, to death at birth. Increased folate intake, either through eating folate rich foods or through supplementation, has been shown to reduce the incidence of neural tube defects in newborns by up to 75%. Encouraging all women of child-bearing age to increase their folate intake could thus prevent a significant number of neural tube defects occurring in the Australian population. PMID:17987155

French, S D

1997-11-01

29

Morphogenetic movements during cranial neural tube closure in the chick embryo and the effect of homocysteine.  

PubMed

In order to unravel morphogenetic mechanisms involved in neural tube closure, critical cell movements that are fundamental to remodelling of the cranial neural tube in the chick embryo were studied in vitro by quantitative time-lapse video microscopy. Two main directions of movements were observed. The earliest was directed medially; these cells invaginated into a median groove and were the main contributors to the initial neural tube closure. Once the median groove was completed, cells changed direction and moved anteriorly to contribute to the anterior neural plate and head fold. This plate developed into the anterior neuropore, which started to close from the 4-somite stage onwards by convergence of its neural folds. Posteriorly, from the initial closure site onwards, the posterior neuropore started to close almost instantaneously by convergence of its neural folds. Homocysteine is adversely involved in human neural tube closure defects. After application of a single dose of homocysteine to chick embryos, a closure delay at the initial closure site and at the neuropores, flattening of the head fold and neural tube, and a halt of cell movements was seen. A possible interference of Hcy with actin microfilaments is discussed. PMID:16133590

Brouns, Madeleine R; Afman, Lydia A; Vanhauten, Bart A M; Hekking, Johan W M; Köhler, Eleonore S; van Straaten, Henny W M

2005-09-01

30

How Many People Are Affected By or Are at Risk for Neural Tube Defects?  

MedlinePLUS

... Information Clinical Trials Resources and Publications How many people are affected by or are at risk for neural tube defects? Skip sharing on social media links Share this: Page Content In the United ...

31

Maternal diet modulates the risk for neural tube defects in a mouse model of diabetic pregnancy  

PubMed Central

Pregnancies complicated by maternal diabetes have long been known to carry a higher risk for congenital malformations, such as neural tube defects. Using the FVB inbred mouse strain and the Streptozotocin-induced diabetes model, we tested whether the incidence of neural tube defects in diabetic pregnancies can be modulated by maternal diet. In a comparison of two commercial mouse diets, which are considered nutritionally replete, we found that maternal consumption of the unfavorable diet was associated with a more than three-fold higher rate of neural tube defects. Our results demonstrate that maternal diet can act as a modifier of the risk for abnormal development in high-risk pregnancies, and provide support for the possibility that neural tube defects in human diabetic pregnancies might be preventable by optimized maternal nutrition. PMID:20868740

Kappen, Claudia; Kruger, Claudia; MacGowan, Jacalyn; Salbaum, J. Michael

2010-01-01

32

21 CFR 101.79 - Health claims: Folate and neural tube defects.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Health claims: Folate and neural tube defects...AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD...FOOD LABELING Specific Requirements for Health Claims § 101.79 Health...

2010-04-01

33

Investigations into arsenate-induced neural tube defects in a mouse model  

E-print Network

arsenate) in a normal inbred mouse strain, LM/Bc/Fnn, that is sensitive to arsenate-induced exencephaly. We investigated arsenate induced gene expression changes using DNA microarrays of embryonic anterior neural tube tissue, as well as monitoring...

Hill, Denise Suzanne

2009-05-15

34

Mouse models of neural tube defects: investigating preventive mechanisms.  

PubMed

Neural tube defects (NTD), including anencephaly and spina bifida, are a group of severe congenital abnormalities in which the future brain and/or spinal cord fail to close. In mice, NTD may result from genetic mutations or knockouts, or from exposure to teratogenic agents, several of which are known risk factors in humans. Among the many mouse NTD models that have been identified to date, a number have been tested for possible primary prevention of NTD by exogenous agents, such as folic acid. In genetic NTD models such as Cart1, splotch, Cited2, and crooked tail, and NTD induced by teratogens including valproic acid and fumonisins, the incidence of defects is reduced by maternal folic acid supplementation. These folate-responsive models provide an opportunity to investigate the possible mechanisms underlying prevention of NTD by folic acid in humans. In another group of mouse models, that includes curly tail, axial defects, and the Ephrin-A5 knockout, NTD are not preventable by folic acid, reflecting the situation in humans in which a subset of NTD appear resistant to folic acid therapy. In this group of mutants alternative preventive agents, including inositol and methionine, have been shown to be effective. Overall, the data from mouse models suggests that a broad-based in utero therapy may offer scope for prevention of a greater proportion of NTD than is currently possible. PMID:15800852

Greene, Nicholas D E; Copp, Andrew J

2005-05-15

35

Dieting behaviors and risk of neural tube defects.  

PubMed

The authors examined whether maternal dieting behaviors were associated with increased neural tube defect (NTD) risk among offspring, using population-based, case-control data. The analysis included 538 cases and 539 nonmalformed controls delivered from 1989 to 1991 in selected California counties, and exposures were assessed by in-person maternal interview. Among four reported dieting behaviors involving restricted food intake, diets to lose weight (odds ratio=2.1, 95% confidence interval: 1.1, 4.1), fasting diets (odds ratio=5.8, 95% confidence interval: 1.7, 20.0), and eating disorders (odds ratio=1.7, 95% confidence interval: 0.8, 3.6) were associated with increased NTD risk during the first trimester of pregnancy. Risk estimates for these behaviors during the 3 months before conception tended to be closer to 1. The fourth behavior, "other special diets," was not associated with increased NTD risk during either period. Women also reported whether they took diet pills, laxatives, or diuretics, engaged in binge eating, induced vomiting, or exercised excessively from the first 3 months before conception through the end of pregnancy. Only the intake of diuretics was associated with substantially increased NTD risk (odds ratio=2.7, 95% confidence interval: 0.7, 10.2). This study suggests that maternal dieting behaviors involving restricted food intake during the first trimester may be associated with increased NTD risk. PMID:14652296

Carmichael, Suzan L; Shaw, Gary M; Schaffer, Donna M; Laurent, Cecile; Selvin, Steve

2003-12-15

36

Neural Tube Defects In Mice Exposed To Tap Water  

PubMed Central

In May of 2006 we suddenly began to observe neural tube defects (NTDs) in embryos of untreated control mice. We hypothesized the mice were being exposed unknowingly to a teratogenic agent and investigated the cause. Our results suggested that NTDs were not resulting from bedding material, feed, strain or source of the mice. Additionally, mice were negative for routine and comprehensive screens of pathogens. To further test whether the NTDs resulted from infectious or genetic cause localized to our facility, we obtained three strains of timed pregnant mice from commercial suppliers located in 4 different states. All strains and sources of mice arrived in our laboratory with NTDs, implying that commercially available mice were possibly exposed to a teratogen prior to purchase. Our investigation eventually concluded that exposure to tap water was causing the NTDs. The incidence of NTDs was greatest in purchased mice provided tap water and lowest in purchased mice provided distilled deionized water (DDI). Providing mice DDI water for two generations (F2-DDI) eliminated the NTDs. When F2-DDI mice were provided tap water from three different urban areas prior to breeding, their offspring again developed NTDs. Increased length of exposure to tap water significantly increased the incidence of NTDs. These results indicate that a contaminant in municipal tap water is likely causing NTDs in mice. The unknown teratogen appears to have a wide geographic distribution but has not yet been identified. Water analysis is currently underway to identify candidate contaminants that might be responsible for the malformations. PMID:20549630

Mallela, Murali K; Werre, Stephen R; Hrubec, Terry C

2010-01-01

37

Slit/Robo1 signaling regulates neural tube development by balancing neuroepithelial cell proliferation and differentiation.  

PubMed

Formation of the neural tube is the morphological hallmark for development of the embryonic central nervous system (CNS). Therefore, neural tube development is a crucial step in the neurulation process. Slit/Robo signaling was initially identified as a chemo-repellent that regulated axon growth cone elongation, but its role in controlling neural tube development is currently unknown. To address this issue, we investigated Slit/Robo1 signaling in the development of chick neCollege of Life Sciences Biocentre, University of Dundee, Dundee DD1 5EH, UKural tube and transgenic mice over-expressing Slit2. We disrupted Slit/Robo1 signaling by injecting R5 monoclonal antibodies into HH10 neural tubes to block the Robo1 receptor. This inhibited the normal development of the ventral body curvature and caused the spinal cord to curl up into a S-shape. Next, Slit/Robo1 signaling on one half-side of the chick embryo neural tube was disturbed by electroporation in ovo. We found that the morphology of the neural tube was dramatically abnormal after we interfered with Slit/Robo1 signaling. Furthermore, we established that silencing Robo1 inhibited cell proliferation while over-expressing Robo1 enhanced cell proliferation. We also investigated the effects of altering Slit/Robo1 expression on Sonic Hedgehog (Shh) and Pax7 expression in the developing neural tube. We demonstrated that over-expressing Robo1 down-regulated Shh expression in the ventral neural tube and resulted in the production of fewer HNK-1(+) migrating neural crest cells (NCCs). In addition, Robo1 over-expression enhanced Pax7 expression in the dorsal neural tube and increased the number of Slug(+) pre-migratory NCCs. Conversely, silencing Robo1 expression resulted in an enhanced Shh expression and more HNK-1(+) migrating NCCs but reduced Pax7 expression and fewer Slug(+) pre-migratory NCCs were observed. In conclusion, we propose that Slit/Robo1 signaling is involved in regulating neural tube development by tightly coordinating cell proliferation and differentiation during neurulation. PMID:23438940

Wang, Guang; Li, Yan; Wang, Xiao-yu; Han, Zhe; Chuai, Manli; Wang, Li-jing; Ho Lee, Kenneth Ka; Geng, Jian-guo; Yang, Xuesong

2013-05-01

38

Moderate alcohol exposure compromises neural tube midline development in prenatal brain  

Microsoft Academic Search

We previously reported that fetal alcohol treatment compromised the development of the midline raphe and the serotonin neurons contained in it. In this study, we report that the timely development of midline neural tissue during neural tube formation is sensitive to alcohol exposure. Pregnant dams were treated from embryonic day 7 (E7, prior to neurulation) or E8.5 (at neurulation) with

Feng C Zhou; Youssef Sari; Teresa Powrozek; Charles R Goodlett; Ting-Kai Li

2003-01-01

39

East Ireland 1980-1994: epidemiology of neural tube defects  

PubMed Central

STUDY OBJECTIVE: The objective of the study was to describe the epidemiology of neural tube defects (NTD) in the eastern region of Ireland using the EUROCAT register of congenital malformations. DESIGN, SETTING AND PATIENTS: EUROCAT registries monitor the prevalence of congenital anomalies in defined populations using multiple sources for case ascertainment. All cases of NTD on the Dublin EUROCAT register born between 1980 and 1994 were extracted and analysed. The crude birth prevalence rate for all NTD, spina bifida, anencephaly and encephalocoele were calculated for each year. Parameters measured were: sex ratio, stillbirth rate, proportion of low birth-weight babies (< 2500 g) and the proportion who were premature (< 37 weeks gestation). MAIN RESULTS: Of 821 NTD cases, 419 (51.0%) had spina bifida, 322 (39.2%) had anencephaly, 69 (8.4%) had encephalocoele and 11 (1.3%) were iniencephalic. The crude birth prevalence of NTD decreased fourfold from 46.9/10,000 births in 1980 to 11.6/10,000 in 1994. The downward trend ceased during the early 1990's. Younger mothers had significantly higher rates of NTD affected births. Twenty two per cent of NTD cases had additional non-central nervous system anomalies. In 40 cases, there was a previous family history of NTD in siblings. Seasonal effects in birth prevalence were observed. Birth notification was the most frequent mechanism of ascertainment. CONCLUSION: There was a marked fall in the birth prevalence of NTD during the 15 year period. This change was real and not accounted for by pre-natal screening and diagnostic practises with termination of pregnancy, which is not legally permissible in Ireland. Dietary factors may have had an influence. Rates of NTD in this region are still higher than many other parts of Europe. Primary prevention strategies through increased folic acid intake are necessary to further reduce NTD affected births.   PMID:10656087

McDonnell, R. J.; Johnson, Z.; Delaney, V.; Dack, P.

1999-01-01

40

Neural tube closure in humans initiates at multiple sites: evidence from human embryos and implications for the pathogenesis of neural tube defects  

Microsoft Academic Search

The closure of the neural tube (NT) in the human embryo has generally been described as a continuous process that begins at the level of the future cervical region and proceeds both rostrally and caudally. On the other hand, multiple initiation sites of NT closure have been demonstrated in mice and other animals. In humans, based on the study of

Tomoko Nakatsu; Chigako Uwabe; Kohei Shiota

2000-01-01

41

Missing Genetic Risk in Neural Tube Defects: Can Exome Sequencing Yield an Insight?  

PubMed Central

Background Neural tube defects (NTD) have a strong genetic component, with up to 70% of variance in human prevalence determined by heritable factors. Although the identification of causal DNA variants by sequencing candidate genes from functionally relevant pathways and model organisms has provided some success, alternative approaches are demanded. Methods Next generation sequencing platforms are facilitating the production of massive amounts of sequencing data, primarily from the protein coding regions of the genome, at a faster rate and cheaper cost than has previously been possible. These platforms are permitting the identification of variants (de novo, rare, and common) that are drivers of NYTD etiology, and the cost of the approach allows for the screening of increased numbers of affected and unaffected individuals from NTD families and in simplex cases. Conclusion The next generation sequencing platforms represent a powerful tool in the armory of the genetics researcher to identify the causal genetic basis of NTDs. PMID:25044326

Krupp, Deidre R.; Soldano, Karen L.; Garrett, Melanie E.; Cope, Heidi; Ashley-Koch, Allison E.; Gregory, Simon G.

2014-01-01

42

Phenotype of the neural tube defect mouse model bent tail is not sensitive to maternal folinic acid,myo-inositol, or zinc supplementation  

Microsoft Academic Search

BACKGROUND: Bent tail is a mouse model for X-linked neural tube defects (NTDs) that is characterized by the presence of exencephaly, a delayed posterior neuropore closure, and a tail phenotype. In addition, Bent tail shows laterality defects and increased prenatal mortality. The congenital malformations of this mouse are caused by a submicroscopic deletion that completely encompasses the gene coding for

Barbara Franke; Riko Klootwijk; Bianca Lemmers; Carolien G. F. De Kovel; Regine P. M. Steegers-Theunissen; Edwin C. M. Mariman

2003-01-01

43

The role of primary cilia in the pathophysiology of neural tube defects.  

PubMed

Neural tube defects (NTDs) are a set of disorders that occur from perturbation of normal neural development. They occur in open or closed forms anywhere along the craniospinal axis and often result from a complex interaction between environmental and genetic factors. One burgeoning area of genetics research is the effect of cilia signaling on the developing neural tube and how the disruption of primary cilia leads to the development of NTDs. Recent progress has implicated the hedgehog (Hh), wingless-type integration site family (Wnt), and planar cell polarity (PCP) pathways in primary cilia as involved in normal neural tube patterning. A set of disorders involving cilia function, known as ciliopathies, offers insight into abnormal neural development. In this article, the authors discuss the common ciliopathies, such as Meckel-Gruber and Joubert syndromes, that are associated with NTDs, and review cilia-related signaling cascades responsible for mammalian neural tube development. Understanding the contribution of cilia in the formation of NTDs may provide greater insight into this common set of pediatric neurological disorders. PMID:23025443

Vogel, Timothy W; Carter, Calvin S; Abode-Iyamah, Kingsley; Zhang, Qihong; Robinson, Shenandoah

2012-10-01

44

Genetic interactions between planar cell polarity genes cause diverse neural tube defects in mice  

PubMed Central

Neural tube defects (NTDs) are among the commonest and most severe forms of developmental defect, characterized by disruption of the early embryonic events of central nervous system formation. NTDs have long been known to exhibit a strong genetic dependence, yet the identity of the genetic determinants remains largely undiscovered. Initiation of neural tube closure is disrupted in mice homozygous for mutations in planar cell polarity (PCP) pathway genes, providing a strong link between NTDs and PCP signaling. Recently, missense gene variants have been identified in PCP genes in humans with NTDs, although the range of phenotypes is greater than in the mouse mutants. In addition, the sequence variants detected in affected humans are heterozygous, and can often be detected in unaffected individuals. It has been suggested that interactions between multiple heterozygous gene mutations cause the NTDs in humans. To determine the phenotypes produced in double heterozygotes, we bred mice with all three pairwise combinations of Vangl2Lp, ScribCrc and Celsr1Crsh mutations, the most intensively studied PCP mutants. The majority of double-mutant embryos had open NTDs, with the range of phenotypes including anencephaly and spina bifida, therefore reflecting the defects observed in humans. Strikingly, even on a uniform genetic background, variability in the penetrance and severity of the mutant phenotypes was observed between the different double-heterozygote combinations. Phenotypically, Celsr1Crsh;Vangl2Lp;ScribCrc triply heterozygous mutants were no more severe than doubly heterozygous or singly homozygous mutants. We propose that some of the variation between double-mutant phenotypes could be attributed to the nature of the protein disruption in each allele: whereas ScribCrc is a null mutant and produces no Scrib protein, Celsr1Crsh and Vangl2Lp homozygotes both express mutant proteins, consistent with dominant effects. The variable outcomes of these genetic interactions are of direct relevance to human patients and emphasize the importance of performing comprehensive genetic screens in humans. PMID:25128525

Murdoch, Jennifer N.; Damrau, Christine; Paudyal, Anju; Bogani, Debora; Wells, Sara; Greene, Nicholas D. E.; Stanier, Philip; Copp, Andrew J.

2014-01-01

45

Maternal Serum B 12 Levels and Risk for Neural Tube Defects in a Texas-Mexico Border Population  

Microsoft Academic Search

PURPOSE: Neural tube defects (NTDs) are common birth defects that can be prevented with folate fortification and supplementation. Studies suggest that other nutrients may also be essential to neural tube closure and have a potential role in risk reduction, with vitamin B12 mentioned most often. We determined the effect of maternal serum B12 levels, measured postpartum, on the risk of

Lucina Suarez; Kate Hendricks; Marilyn Felkner; Elaine Gunter

2003-01-01

46

In toto live imaging of mouse morphogenesis and new insights into neural tube closure  

PubMed Central

In the field of developmental biology, live imaging is a powerful tool for studying, in real time, the dynamic behaviors of tissues and cells during organ formation. Mammals, which develop in utero, have presented a challenge for live imaging. Here, we offer a novel, prolonged and robust live imaging system for visualizing the development of a variety of embryonic tissues in the midgestation mouse embryo. We demonstrate the advantages of this imaging system by following the dynamics of neural tube closure during mouse embryogenesis and reveal extensive movements of the cranial neural tissue that are independent of neural fold zipping. PMID:23175632

Massarwa, R'ada; Niswander, Lee

2013-01-01

47

Prenatal Diagnosis and Elective Termination of Neural Tube Defects in Hawaii, 1986–1997  

Microsoft Academic Search

Objective: To determine the influence of various factors on the prenatal diagnosis and elective termination of neural tube defects (NTDs) in Hawaii in 1986–1997. Methods: Data from a birth defects registry were analyzed and included 245 cases. Results: 74% of the cases were prenatally diagnosed and 48% were terminated. Anencephaly was more likely to be prenatally diagnosed and electively terminated

Mathias B. Forrester; Ruth D. Merz

2000-01-01

48

Improving the health and well-being of women at risk for neural tube defect recurrence  

Microsoft Academic Search

There is growing interest in providing women with internatal care, a package of healthcare and ancillary services that can improve their health during the period after the termination of one pregnancy but before the conception of the next pregnancy. Women who have had a pregnancy affected by a neural tube defect can especially benefit from internatal care because they are

Tasneem Husain

2009-01-01

49

derived growth factor ? -receptor gene predispose to human neural tube defects  

Microsoft Academic Search

Neural tube defects (NTDs), including anencephaly and spina bifida, are multifactorial diseases that occur with an incidence of 1 in 300 births in the United Kingdom 1 . Mouse models have indicated that deregulated expression of the gene encoding the platelet-derived growth factor ? -receptor (Pdgfra) causes congenital NTDs (refs. 2-4), whereas mutant forms of Pax-1 that have been associated

Paul H. L. J. Joosten; Mascha Toepoel; Edwin C. M. Mariman; J. J. Van Zoelen

50

Fate-mapping the mouse neural tube by Cre-loxP transgenesis  

E-print Network

nervous system (CNS) develops from a thin layer of neuroepithelial stem cells that form the early neural Institute for Biomedical Research, University College London A thesis submitted to the University of London tube. Initially neuroepithelial cells generate neurons, the identity of which depends on their position

Richardson, William D.

51

Severe Fetal Hydrocephalus with and without Neural Tube Defect: A Comparative Study  

Microsoft Academic Search

Objective: To describe the main perinatal and 1-year outcomes in babies with a prenatal ultrasonographic diagnosis of severe hydrocephalus according to the presence or absence of a neural tube defect (NTD) in a country where abortion is illegal. Method: The study population consisted of cases referred to and delivered at Hospital de Clínicas de Porto Alegre, diagnosed between January 1993

D. Schlatter; M. T. V. Sanseverino; J. M. R. Schmitt; A. Fritsch; R. G. Kessler; P. M. M. Barrios; R. S. Palma-Dias; J. A. Magalhăes

2008-01-01

52

Morphogenetic movements during axolotl neural tube formation tracked by digital imaging  

Microsoft Academic Search

During neurulation in vertebrate embryos, epithelial cells of the neural plate undergo complex morphogenetic movements that culminate in rolling of the plate into a tube. Resolution of the determinants of this process requires an understanding of the precise movements of cells within the epithelial sheet. A computer algorithm that allows automated tracking of epithelial cells visible in digitized video images

G. Wayne Brodland; Michael J. Scott; Andrew F. MacLean; M. Globus; S. Vethamany-Globus; R. Gordon; Jim H. Veldhuis; R. Maestro

1996-01-01

53

Neural Tube Defects at Siriraj Hospital, Bangkok, Thailand10 Years Review (1990-1999)  

Microsoft Academic Search

Objectives: Neural tube defects (NTDs), (including anencephaly, meningomyelocele and encephalocele), are among the most common birth defects, with high associated mortality and morbidity. NTDs occur in 1-5 per 1,000 births, with marked geographic and ethnic variations. However, there are few data concerning the incidence, associated anomalies, treatment and outcome of NTDs in Thailand. The objective of this study is to

Pornswan Wasant

54

Epidemiologic and Genetic Aspects of Spina Bifida and Other Neural Tube Defects  

ERIC Educational Resources Information Center

The worldwide incidence of neural tube defects (NTDs) ranges from 1.0 to 10.0 per 1,000 births with almost equal frequencies between two major categories: anencephaly and spina bifida (SB). Epidemiological studies have provided valuable insight for (a) researchers to identify nongenetic and genetic factors contributing to etiology, (b) public…

Au, Kit Sing; Ashley-Koch, Allison; Northrup, Hope

2010-01-01

55

Disruption of the MacMARCKS gene prevents cranial neural tube closure and results in anencephaly.  

PubMed Central

MacMARCKS is a member of the MARCKS family of protein kinase C (PKC) substrates. Biochemical evidence demonstrates that these proteins integrate calcium and PKC-dependent signals to regulate actin structure at the membrane. We report here that deletion of the MacMARCKS gene prevents cranial neural tube closure in the developing brain, resulting in anencephaly. This suggests a central role for MacMARCKS and the PKC signal transduction pathway in the folding of the anterior neural plate during the early phases of brain formation, and supports the hypothesis that actin-based motility directs cranial neural tube closure. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 PMID:8692805

Chen, J; Chang, S; Duncan, S A; Okano, H J; Fishell, G; Aderem, A

1996-01-01

56

Neural tube closure in the chick embryo is multiphasic.  

PubMed

Progression of neurulation in the chick embryo has not been well documented. To provide a detailed description, chick embryos were stained in ovo after the least manipulation possible to avoid distortion of the neural plate and folds. This allowed a morphological and morphometric description of the process of neurulation in relatively undisturbed chick embryos. Neurulation comprises several specific phases with distinct closure patterns and closure rates. The first closure event occurs, de novo, in the future mesencephalon at the 4-6 somite stage (sst 4-6). Soon afterwards, at sst 6-7, de novo closure is seen at the rhombocervical level in the form of multisite contacts of the neural folds. These contacts occur in register with the somites, suggesting that the somites may play a role in forcing elevation and apposition of the neural folds. The mesencephalic] and rhombocervical closure events define an intervening rhombencephalic neuropore, which is present for a brief period before it closes. The remaining pear-shaped posterior neuropore (PNP) narrows and displaces caudally, but its length remains constant in embryos with seven to ten somites, indicating that the caudal extension of the rhombocervical closure point and elongation of the caudal neural plate are keeping pace with each other. From sst 10 onward, the tapered cranial portion of the PNP closes fast in a zipper-like manner, and, subsequently, the wide caudal portion of the PNP closes rapidly as a result of the parallel alignment of its folds, with numerous button-like temporary contact points. A role for convergent extension in this closure event is suggested. The final remnant of the PNP closes at sst 18. Thus, as in mammals, chick neurulation involves multisite closure and probably results form several different development mechanisms at varying levels of the body axis. PMID:8922530

Van Straaten, H W; Janssen, H C; Peeters, M C; Copp, A J; Hekking, J W

1996-11-01

57

Heat Transfer Coefficient and Friction Factor Prediction of Corrugated Tubes Combined With Twisted Tape Inserts Using Artificial Neural Network  

Microsoft Academic Search

In the research described here, artificial neural network (ANN) approach has been utilized to characterize the thermohydraulic behavior of corrugated tubes combined with twisted tape inserts in a turbulent flow regime. The experimental data sets were extracted from 57 tubes, 9 and 3 spirally corrugated tubes with varying geometries combined with 5 and 4 twisted tapes with different pitches. The

Mohammad Reza Jafari Nasr; Ali Habibi Khalaj

2010-01-01

58

Cell cycle-related genes p57kip2, Cdk5 and Spin in the pathogenesis of neural tube defects  

PubMed Central

In the field of developmental neurobiology, accurate and ordered regulation of the cell cycle and apoptosis are crucial factors contributing to the normal formation of the neural tube. Preliminary studies identified several genes involved in the development of neural tube defects. In this study, we established a model of developmental neural tube defects by administration of retinoic acid to pregnant rats. Gene chip hybridization analysis showed that genes related to the cell cycle and apoptosis, signal transduction, transcription and translation regulation, energy and metabolism, heat shock, and matrix and cytoskeletal proteins were all involved in the formation of developmental neural tube defects. Among these, cell cycle-related genes were predominant. Retinoic acid ment caused differential expression of three cell cycle-related genes p57kip2, Cdk5 and Spin, the expression levels of which were downregulated by retinoic acid and upregulated during normal neural tube formation. The results of this study indicate that cell cycle-related genes play an important role in the formation of neural tube defects. P57kip2, Cdk5 and Spin may be critical genes in the pathogenesis of neural tube defects.

Li, Xinjun; Yang, Zhong; Zeng, Yi; Xu, Hong; Li, Hongli; Han, Yangyun; Long, Xiaodong; You, Chao

2013-01-01

59

Cell cycle-related genes p57kip2, Cdk5 and Spin in the pathogenesis of neural tube defects.  

PubMed

In the field of developmental neurobiology, accurate and ordered regulation of the cell cycle and apoptosis are crucial factors contributing to the normal formation of the neural tube. Preliminary studies identified several genes involved in the development of neural tube defects. In this study, we established a model of developmental neural tube defects by administration of retinoic acid to pregnant rats. Gene chip hybridization analysis showed that genes related to the cell cycle and apoptosis, signal transduction, transcription and translation regulation, energy and metabolism, heat shock, and matrix and cytoskeletal proteins were all involved in the formation of developmental neural tube defects. Among these, cell cycle-related genes were predominant. Retinoic acid ment caused differential expression of three cell cycle-related genes p57kip2, Cdk5 and Spin, the expression levels of which were downregulated by retinoic acid and upregulated during normal neural tube formation. The results of this study indicate that cell cycle-related genes play an important role in the formation of neural tube defects. P57kip2, Cdk5 and Spin may be critical genes in the pathogenesis of neural tube defects. PMID:25206495

Li, Xinjun; Yang, Zhong; Zeng, Yi; Xu, Hong; Li, Hongli; Han, Yangyun; Long, Xiaodong; You, Chao

2013-07-15

60

Performance predictions of laminar and turbulent heat transfer and fluid flow of heat exchangers having large tube-diameter and large tube-row by artificial neural networks  

Microsoft Academic Search

In this work an artificial neural network (ANN) is used to correlate experimentally determined and numerically computed Nusselt numbers and friction factors of three kinds of fin-and-tube heat exchangers having plain fins, slit fins and fins with longitudinal delta-winglet vortex generators with large tube-diameter and large the number of tube rows. First the experimental data for training the network was

Gongnan Xie; Bengt Sunden; Qiuwang Wang; Linghong Tang

2009-01-01

61

Metabolic effects of C677T and A1298C mutations at the MTHFR gene in Brazilian children with neural tube defects  

Microsoft Academic Search

Background: Methylenetetrahydrofolate reductase (MTHFR) deficiency leads to impairment in folate metabolism and is implicated as a risk factor for neural tube defects (NTDs). Both C677T and A1298C MTHFR mutations are associated with NTDs, in some populations. Methods: The frequencies of the C677T and A1298C MTHFR mutations were determined in 25 children with NTDs, case mothers and 75 healthy individuals from

Andrea L. A Cunha; Mario H Hirata; Chong A Kim; Elvira M Guerra-Shinohara; Kymio Nonoyama; Rosario D. C Hirata

2002-01-01

62

Epidural analgesia for labour in a patient with a neural tube defect.  

PubMed

This report describes the use of epidural analgesia in a patient with a known neural tube defect. The patient had a severe form of spina bifida cystica which had been operated on in childhood. She had a neurogenic bladder but otherwise had preserved neurological function. She had an epidural catheter inserted in early labour; providing effective analgesia for an uneventful birth. This case outlines the severity of the cystica category of neural tube defects, the added anatomical challenges of previous surgery and the difficulties that may arise from the utilization of epidural analgesia. The case demonstrates that epidural analgesia can be utilized despite such a disorder A thorough history and examination are essential, as are the patient's informed consent and knowledge of possible complications. PMID:17183906

Altamimi, Y; Pavy, T J G

2006-12-01

63

Adding folate to the contraceptive pill: a new concept for the prevention of neural tube defects.  

PubMed

Although it is proven for a long time that folic acid supplementation in the periconceptional period can prevent neural tube defects (NTDs) effectively, all measures taken so far including food fortification and awareness campaigns so far had only limited success. Since more than 50% of the pregnant women in Europe get pregnant after they have used oral contraceptives (OCs) before, OCs are an ideal vehicle to increase not only the awareness for periconceptional folate application, but they can also help to bridge the gap between the recognition of a pregnancy and closure of the neural tube which is before day 26. In order to reach a truly protective folate level at the critical time period during pregnancy, now OCs are available which contain metafolin. The availability of this innovative type of OC will significantly reduce the number of NTDs. PMID:22272814

Holzgreve, Wolfgang; Pietrzik, Klaus; Koletzko, Berthold; Eckmann-Scholz, Christel

2012-09-01

64

N-cadherin-mediated cell adhesion restricts cell proliferation in the dorsal neural tube  

PubMed Central

Neural progenitors are organized as a pseudostratified epithelium held together by adherens junctions (AJs), multiprotein complexes composed of cadherins and ?- and ?-catenin. Catenins are known to control neural progenitor division; however, it is not known whether they function in this capacity as cadherin binding partners, as there is little evidence that cadherins themselves regulate neural proliferation. We show here that zebrafish N-cadherin (N-cad) restricts cell proliferation in the dorsal region of the neural tube by regulating cell-cycle length. We further reveal that N-cad couples cell-cycle exit and differentiation, as a fraction of neurons are mitotic in N-cad mutants. Enhanced proliferation in N-cad mutants is mediated by ligand-independent activation of Hedgehog (Hh) signaling, possibly caused by defective ciliogenesis. Furthermore, depletion of Hh signaling results in the loss of junctional markers. We therefore propose that N-cad restricts the response of dorsal neural progenitors to Hh and that Hh signaling limits the range of its own activity by promoting AJ assembly. Taken together, these observations emphasize a key role for N-cad–mediated adhesion in controlling neural progenitor proliferation. In addition, these findings are the first to demonstrate a requirement for cadherins in synchronizing cell-cycle exit and differentiation and a reciprocal interaction between AJs and Hh signaling. PMID:21389116

Chalasani, Kavita; Brewster, Rachel M.

2011-01-01

65

Economic burden of neural tube defects and impact of prevention with folic acid: a literature review  

Microsoft Academic Search

Neural tube defects (NTDs) are the second most common group of serious birth defects. Although folic acid has been shown to\\u000a reduce effectively the risk of NTDs and measures have been taken to increase the awareness, knowledge, and consumption of\\u000a folic acid, the full potential of folic acid to reduce the risk of NTDs has not been realized in most

Yunni Yi; Marion Lindemann; Antje Colligs; Claire Snowball

66

Analysis of the MTHFD1 promoter and risk of neural tube defects  

Microsoft Academic Search

Genetic variants in MTHFD1 (5,10-methylenetetrahydrofolate dehydrogenase\\/5,10-methenyltetrahydrofolate cyclohydrolase\\/ 10-formyltetrahydrofolate\\u000a synthetase), an important folate metabolic enzyme, are associated with a number of common diseases, including neural tube\\u000a defects (NTDs). This study investigates the promoter of the human MTHFD1 gene in a bid to understand how this gene is controlled and regulated. Following a combination of in silico and molecular\\u000a approaches, we report

Nicola Carroll; Faith Pangilinan; Anne M. Molloy; James Troendle; James L. Mills; Peadar N. Kirke; Lawrence C. Brody; John M. Scott; Anne Parle-McDermott

2009-01-01

67

Screening for Down’s Syndrome and Neural Tube Defect in Croatia  

Microsoft Academic Search

Objective: The purpose of this study was to investigate the efficiency of second-trimester maternal serum screening for Down’s syndrome and open neural tube defects using alpha-fetoprotein and free ?-human chorionic gonadotropin as serum markers. Methods: 3,188 women underwent testing between 14th and 22nd week of pregnancy. Of all tested patients, 25.4% were ?35 years old. A cut-off risk of ?1:250

Anatelo Slivar; Miljenko Kapovic; Vesna Košec; Smiljana Ristic; Branko Rajhvajn

1998-01-01

68

‘Dual Positivity’ for Neural Tube Defects and Down Syndrome at Maternal Serum Screening: Gestational Outcome  

Microsoft Academic Search

Objective: To evaluate the gestational outcome of pregnancies screen-positive for both neural tube defects (NTD) and Down syndrome (DS) (‘dual positivity’). Methods: Among 10,667 mid-trimester women screened for DS and NTD with ?-fetoprotein (AFP), unconjugated estriol (uE3), and human chorionic gonadotropin (hCG), delivered up to July 1996, we have selected cases with both an unexplained AFP value ?2.5 multiples of

Roberto Zanini; Michele Tarantini; Valeria Cerri; Carmelo Jacobello; Daniela Bellotti; Sara Lancetti; Sabrina Scalchi; Caterina Groli; Umberto A. Bianchi

1998-01-01

69

Maternal exposure to arsenic, cadmium, lead, and mercury and neural tube defects in offspring  

Microsoft Academic Search

Arsenic, cadmium, lead, and mercury are neurotoxins, and some studies suggest that these elements might also be teratogens. Using a case–control study design, we investigated the relation between exposure to these heavy metals and neural tube defects (NTDs) in offspring of Mexican–American women living in 1 of the 14 Texas counties bordering Mexico. A total of 184 case-women with NTD-affected

Jean D.. Brender; Lucina Suarez; Marilyn Felkner; Zunera Gilani; David Stinchcomb; Karen Moody; Judy Henry; Katherine Hendricks

2006-01-01

70

C5a Receptor Signaling Prevents Folate Deficiency-Induced Neural Tube Defects in Mice  

PubMed Central

The complement system is involved in a range of diverse developmental processes including cell survival, growth, differentiation, and regeneration. However, little is known about the role of complement in embryogenesis. Herein we demonstrate a novel role for the canonical complement 5a receptor (C5aR) in the development of the mammalian neural tube under conditions of maternal dietary folic acid deficiency. Specifically, we found C5aR and C5 to be expressed throughout the period of neurulation in wildtype mice and localized the expression to the cephalic regions of the developing neural tube. C5aR was also found to be expressed in the neuroepithelium of early human embryos. Ablation of the C5ar1 gene or the administration of a specific C5aR peptide antagonist to folic acid-deficient pregnant mice resulted in a high prevalence of severe anterior neural tube defect-associated congenital malformations. These findings provide a new and compelling insight into the role of the complement system during mammalian embryonic development. PMID:23420882

Denny, Kerina J; Coulthard, Liam G; Jeanes, Angela; Lisgo, Steven; Simmons, David G; Callaway, Leonie K; Wlodarczyk, Bogdan; Finnell, Richard H; Woodruff, Trent M; Taylor, Stephen M

2013-01-01

71

Sec24b selectively sorts Vangl2 to regulate planar cell polarity during neural tube closure  

PubMed Central

Craniorachischisis is a rare but severe birth defect that results in a completely open neural tube. Mouse mutants in planar cell polarity (PCP) signaling components have deficits in the morphological movements of convergent extension (CE) that result in craniorachischisis. Using a forward-genetic screen in mice, we have identified Sec24b, a cargo-sorting member of the core complex of the COPII endoplasmic reticulum (ER)-Golgi transport vesicle, as critical for neural tube closure. Sec24bY613 mutants exhibit craniorachischisis, deficiencies in CE, and other PCP-related phenotypes. Vangl2, a key component of the PCP-signaling pathway critical for CE, is selectively sorted into COPII vesicles by Sec24b. Moreover, Sec24bY613 genetically interacts with a loss-of-function Vangl2 allele (Vangl2LP) causing a marked increase in the prevalence of spina bifida. Interestingly, the Vangl2 looptail point mutants D255E and S464N, known to cause defects in CE, fail to sort into COPII vesicles and are trapped in the ER. Thus, during COPII vesicle formation, Sec24b exhibits cargo specificity for a core PCP component, Vangl2, the proper ER to Golgi transport of which is essential for the establishment of PCP, convergent extension, and closure of the neural tube. PMID:19966784

Merte, Janna; Jensen, Devon; Wright, Kevin; Sarsfield, Sarah; Wang, Yanshu; Schekman, Randy; Ginty, David D.

2010-01-01

72

Effect of the notochord on the differentiation of a floor plate area in the neural tube of the chick embryo  

Microsoft Academic Search

The role of a notochord fragment on the origin of an additional floor plate area in the neural tube is investigated by quantitative morphological methods. In 1.5 to 2 day chick embryos a notochordal fragment was implanted in close apposition to the lateral wall of the neural groove in the region between prospective wing and leg bud. At 4 days,

H. W. M. Straaten; J. W. M. Hekking; E. J. L. M. Wiertz-Hoessels; F. Thors; J. Drukker

1988-01-01

73

FKBP8 cell-autonomously controls neural tube patterning through a Gli2- and Kif3a-dependent mechanism  

Microsoft Academic Search

Signaling by Sonic hedgehog (Shh) represents an important process by which many types of neural progenitor cells become properly organized along the dorsal–ventral axis of the vertebrate neural tube in a concentration-dependent manner. However, the mechanism by which Shh signals are transduced with high fidelity and the relationship between the Shh signaling pathway and other patterning systems remain unclear. Here

Ahryon Cho; Hyuk W. Ko; Jonathan T. Eggenschwiler

2008-01-01

74

Applying Bayesian neural networks to separate neutrino events from backgrounds in reactor neutrino experiments  

NASA Astrophysics Data System (ADS)

A toy detector has been designed to simulate central detectors in reactor neutrino experiments in the paper. The samples of neutrino events and three major backgrounds from the Monte-Carlo simulation of the toy detector are generated in the signal region. The Bayesian Neural Networks (BNN) are applied to separate neutrino events from backgrounds in reactor neutrino experiments. As a result, the most neutrino events and uncorrelated background events in the signal region can be identified with BNN, and the part events each of the fast neutron and 8He/9Li backgrounds in the signal region can be identified with BNN. Then, the signal to noise ratio in the signal region is enhanced with BNN. The neutrino discrimination increases with the increase of the neutrino rate in the training sample. However, the background discriminations decrease with the decrease of the background rate in the training sample.

Xu, Y.; Meng, Y. X.; Xu, W. W.

2008-08-01

75

A spatial model to predict the incidence of neural tube defects  

PubMed Central

Background Environmental exposure may play an important role in the incidences of neural tube defects (NTD) of birth defects. Their influence on NTD may likely be non-linear; few studies have considered spatial autocorrelation of residuals in the estimation of NTD risk. We aimed to develop a spatial model based on generalized additive model (GAM) plus cokriging to examine and model the expected incidences of NTD and make the inference of the incidence risk. Methods We developed a spatial model to predict the expected incidences of NTD at village level in Heshun County, Shanxi Province, China, a region with high NTD cases. GAM was used to establish linear and non-linear relationships between local covariates and the expected NTD incidences. We examined the following village-level covariates in the model: projected coordinates, soil types, lithodological classes, distance to watershed, rivers, faults and major roads, annual average fertilizer uses, fruit and vegetable production, gross domestic product, and the number of doctors. The residuals from GAM were assumed to be spatially auto-correlative and cokriged with regional residuals to improve the prediction. Our approach was compared with three other models, universal kriging, generalized linear regression and GAM. Cross validation was conducted for validation. Results Our model predicted the expected incidences of NTD well, with a good CV R2 of 0.80. Important predictive factors included the fertilizer uses, locations of the centroid of each village, the shortest distance to rivers and faults and lithological classes with significant spatial autocorrelation of residuals. Our model out-performed the other three methods by 16% or more in term of R2. Conclusions The variance explained by our model was approximately 80%. This modeling approach is useful for NTD epidemiological studies and intervention planning. PMID:23134640

2012-01-01

76

Trehalose prevents neural tube defects by correcting maternal diabetes-suppressed autophagy and neurogenesis  

PubMed Central

Preexisting maternal diabetes increases the risk of neural tube defects (NTDs). The mechanism underlying maternal diabetes-induced NTDs is not totally defined, and its prevention remains a challenge. Autophagy, an intracellular process to degrade dysfunction protein and damaged cellular organelles, regulates cell proliferation, differentiation, and apoptosis. Because autophagy impairment causes NTDs reminiscent of those observed in diabetic pregnancies, we hypothesize that maternal diabetes-induced autophagy impairment causes NTD formation by disrupting cellular homeostasis, leading to endoplasmic reticulum (ER) stress and apoptosis, and that restoration of autophagy by trehalose, a natural disaccharide, prevents diabetes-induced NTDs. Embryos from nondiabetic and type 1 diabetic mice fed with or without 2 or 5% trehalose water were used to assess markers of autophagy, ER stress, and neurogenesis, numbers of autophagosomes, gene expression that regulates autophagy, NTD rates, indices of mitochondrial dysfunction, and neuroepithelial cell apoptosis. Maternal diabetes suppressed autophagy by significantly reducing LC3-II expression, autophagosome numbers, and GFP-LC3 punctate foci in neuroepithelial cells and by altering autophagy-related gene expression. Maternal diabetes delayed neurogenesis by blocking Sox1 neural progenitor differentiation. Trehalose treatment reversed autophagy impairment and prevented NTDs in diabetic pregnancies. Trehalose resolved homeostatic imbalance by correcting mitochondrial defects, dysfunctional proteins, ER stress, apoptosis, and delayed neurogenesis in the neural tubes exposed to hyperglycemia. Our study demonstrates for the first time that maternal diabetes suppresses autophagy in neuroepithelial cells of the developing neural tube, leading to NTD formation, and provides evidence for the potential efficacy of trehalose as an intervention against hyperglycemia-induced NTDs. PMID:23880312

Xu, Cheng; Li, Xuezheng; Wang, Fang; Weng, Hongbo

2013-01-01

77

Shmt1 and de novo thymidylate biosynthesis underlie folate-responsive neural tube defects in mice1234  

PubMed Central

Background: Folic acid supplementation prevents the occurrence and recurrence of neural tube defects (NTDs), but the causal metabolic pathways underlying folic acid–responsive NTDs have not been established. Serine hydroxymethyltransferase (SHMT1) partitions folate-derived one-carbon units to thymidylate biosynthesis at the expense of cellular methylation, and therefore SHMT1-deficient mice are a model to investigate the metabolic origin of folate-associated pathologies. Objectives: We examined whether genetic disruption of the Shmt1 gene in mice induces NTDs in response to maternal folate and choline deficiency and whether a corresponding disruption in de novo thymidylate biosynthesis underlies NTD pathogenesis. Design: Shmt1 wild-type, +/?, and ?/? mice fed either folate- and choline-sufficient or folate- and choline-deficient diets were bred, and litters were examined for the presence of NTDs. Biomarkers of impaired folate metabolism were measured in the dams. In addition, the effect of Shmt1 disruption on NTD incidence was investigated in Sp mice, an established folate-responsive NTD mouse model. Results: +/? and ?/? embryos exhibited exencephaly in response to maternal folate and choline deficiency. Shmt1 disruption on the Sp background exacerbated NTD frequency and severity. Pax3 disruption impaired de novo thymidylate and purine biosynthesis and altered amounts of SHMT1 and thymidylate synthase protein. Conclusions: SHMT1 is the only folate-metabolizing enzyme that has been shown to affect neural tube closure in mice by directly inhibiting folate metabolism. These results provide evidence that disruption of Shmt1 expression causes NTDs by impairing thymidylate biosynthesis and shows that changes in the expression of genes that encode folate-dependent enzymes may be key determinates of NTD risk. PMID:21346092

Beaudin, Anna E; Abarinov, Elena V; Noden, Drew M; Perry, Cheryll A; Chu, Stephanie; Stabler, Sally P; Allen, Robert H

2011-01-01

78

Hoxb1b controls oriented cell division, cell shape and microtubule dynamics in neural tube morphogenesis  

PubMed Central

Hox genes are classically ascribed to function in patterning the anterior-posterior axis of bilaterian animals; however, their role in directing molecular mechanisms underlying morphogenesis at the cellular level remains largely unstudied. We unveil a non-classical role for the zebrafish hoxb1b gene, which shares ancestral functions with mammalian Hoxa1, in controlling progenitor cell shape and oriented cell division during zebrafish anterior hindbrain neural tube morphogenesis. This is likely distinct from its role in cell fate acquisition and segment boundary formation. We show that, without affecting major components of apico-basal or planar cell polarity, Hoxb1b regulates mitotic spindle rotation during the oriented neural keel symmetric mitoses that are required for normal neural tube lumen formation in the zebrafish. This function correlates with a non-cell-autonomous requirement for Hoxb1b in regulating microtubule plus-end dynamics in progenitor cells in interphase. We propose that Hox genes can influence global tissue morphogenesis by control of microtubule dynamics in individual cells in vivo. PMID:24449840

Zigman, Mihaela; Laumann-Lipp, Nico; Titus, Tom; Postlethwait, John; Moens, Cecilia B.

2014-01-01

79

Signal/background classification in a cosmic ray space experiment by a modular neural system  

NASA Astrophysics Data System (ADS)

In the cosmic ray space experiments, the separation of the signal from background is a hard task. Due to the well-known critical conditions that characterize this class of experiments, some changes of the detector performances can be observed during the data taking. As a consequence, differences between the test and real data are found as systematic errors in the classification phase. In this paper, a modular classification system based on neural networks is proposed for the signal/background discrimination task in cosmic ray space experiments, without a priori knowledge of the discriminating feature distributions. The system is composed by two neural modules. The first one is a self organizing map (SOM) that both clusters the real data space in suitable classes of similarity and builds a prototype for each of them; a skilled inspection of the prototypes defines the signal and background. The second one, a multi layer perceptron (MLP) with a single hidden layer, adapts the classification model based on training/test data to the real experimental conditions. The MLP synaptic weights adaptive formation takes into account the labelled real data set as defined in the first system-phase. The modular neural system has been applied in the context of TRAMP-Si experiment, performed on the NASA Balloon-Borne Magnet Facility, for the positron/proton discrimination.

Bellotti, Roberto; Castellano, Marcello; De Marzo, Carlo N.; Satalino, Giuseppe

1995-04-01

80

Optimal combination of neural temporal envelope and fine structure cues to explain speech identification in background noise.  

PubMed

The dichotomy between acoustic temporal envelope (ENV) and fine structure (TFS) cues has stimulated numerous studies over the past decade to understand the relative role of acoustic ENV and TFS in human speech perception. Such acoustic temporal speech cues produce distinct neural discharge patterns at the level of the auditory nerve, yet little is known about the central neural mechanisms underlying the dichotomy in speech perception between neural ENV and TFS cues. We explored the question of how the peripheral auditory system encodes neural ENV and TFS cues in steady or fluctuating background noise, and how the central auditory system combines these forms of neural information for speech identification. We sought to address this question by (1) measuring sentence identification in background noise for human subjects as a function of the degree of available acoustic TFS information and (2) examining the optimal combination of neural ENV and TFS cues to explain human speech perception performance using computational models of the peripheral auditory system and central neural observers. Speech-identification performance by human subjects decreased as the acoustic TFS information was degraded in the speech signals. The model predictions best matched human performance when a greater emphasis was placed on neural ENV coding rather than neural TFS. However, neural TFS cues were necessary to account for the full effect of background-noise modulations on human speech-identification performance. PMID:25186758

Moon, Il Joon; Won, Jong Ho; Park, Min-Hyun; Ives, D Timothy; Nie, Kaibao; Heinz, Michael G; Lorenzi, Christian; Rubinstein, Jay T

2014-09-01

81

Folate-related gene variants in Irish families affected by neural tube defects  

PubMed Central

Periconceptional folic acid use can often prevent neural tube defects (NTDs). Variants of genes involved in folate metabolism in mothers and children have been associated with occurrence of NTDs. We identified Irish families with individuals affected by neural tube defects. In these families, we observed that neural tube defects and birth defects overall occurred at a higher rate in the maternal lineage compared with the paternal lineage. The goal of this study was to look for evidence for genetic effects that could explain the discrepancy in the occurrence of these birth defects in the maternal vs. paternal lineage. We genotyped blood samples from 322 individuals from NTD-affected Irish families, identified through their membership in spina bifida associations. We looked for differences in distribution in maternal vs. paternal lineages of five genetic polymorphisms: the DHFR 19 bp deletion, MTHFD1 1958G>A, MTHFR 1298A>C, MTHFR 677C>T, and SLC19A1 80A>G. In addition to looking at genotypes individually, we determined the number of genotypes associated with decreased folate metabolism in each relative (“risk genotypes”) and compared the distribution of these genotypes in maternal vs. paternal relatives. Overall, maternal relatives had a higher number of genotypes associated with lower folate metabolism than paternal relatives (p = 0.017). We expected that relatives would share the same risk genotype as the individuals with NTDs and/or their mothers. However, we observed that maternal relatives had an over-abundance of any risk genotype, rather than one specific genotype. The observed genetic effects suggest an epigenetic mechanism in which decreased folate metabolism results in epigenetic alterations related to the increased rate of NTDs and other birth defects seen in the maternal lineage. Future studies on the etiology of NTDs and other birth defects could benefit from including multigenerational extended families, in order to explore potential epigenetic mechanisms. PMID:24223580

Fisk Green, Ridgely; Byrne, Julianne; Crider, Krista S.; Gallagher, Margaret; Koontz, Deborah; Berry, Robert J.

2013-01-01

82

Nitrosatable Drug Exposure During Early Pregnancy and Neural Tube Defects in Offspring  

PubMed Central

Nitrosatable drugs, such as secondary or tertiary amines and amides, form N-nitroso compounds in the presence of nitrite. Various N-nitroso compounds have been associated with neural tube defects in animal models. Using data from the National Birth Defects Prevention Study, the authors examined nitrosatable drug exposure 1 month before and 1 month after conception in 1,223 case mothers with neural tube defect-affected pregnancies and 6,807 control mothers who delivered babies without major congenital anomalies from 1997 to 2005. Nitrite intakes were estimated from mothers’ responses to a food frequency questionnaire. After adjustment for maternal race/ethnicity, educational level, and folic acid supplementation, case women were more likely than were control women to have taken tertiary amines (odds ratio = 1.60, 95% confidence interval (CI): 1.31, 1.95). This association was strongest with anencephalic births (odds ratio = 1.96, 95% CI: 1.40, 2.73); odds ratios associated with tertiary amines from the lowest tertile of nitrite intake to the highest tertile were 1.16 (95% CI: 0.59, 2.29), 2.19 (95% CI: 1.25, 3.86), and 2.51 (95% CI: 1.45, 4.37), respectively. Odds ratios for anencephaly with nitrosatable drug exposure were reduced among women who also took daily vitamin supplements that contained vitamin C. Prenatal exposure to nitrosatable drugs may increase the risk of neural tube defects, especially in conjunction with a mother’s higher dietary intake of nitrites, but vitamin C might modulate this association. PMID:22047825

Brender, Jean D.; Werler, Martha M.; Kelley, Katherine E.; Vuong, Ann M.; Shinde, Mayura U.; Zheng, Qi; Huber, John C.; Sharkey, Joseph R.; Griesenbeck, John S.; Romitti, Paul A.; Langlois, Peter H.; Suarez, Lucina; Canfield, Mark A.

2011-01-01

83

Systems biological approach to investigate the lack of familial link between Down's Syndrome & Neural Tube Disorders  

PubMed Central

Systems Biology involves the study of the interactions of biological systems and ultimately their functions. Down's syndrome (DS) is one of the most common genetic disorders which are caused by complete, or occasionally partial, triplication of chromosome 21, characterized by cognitive and language dysfunction coupled with sensory and neuromotor deficits. Neural Tube Disorders (NTDs) are a group of congenital malformations of the central nervous system and neighboring structures related to defective neural tube closure during the first trimester of pregnancy usually occurring between days 18-29 of gestation. Several studies in the past have provided considerable evidence that abnormal folate and methyl metabolism are associated with onset of DS & NTDs. There is a possible common etiological pathway for both NTDs and Down's syndrome. But, various research studies over the years have indicated very little evidence for familial link between the two disorders. Our research aimed at the gene expression profiling of microarray datasets pertaining to the two disorders to identify genes whose expression levels are significantly altered in these conditions. The genes which were 1.5 fold unregulated and having a p-value <0.05 were filtered out and gene interaction network were constructed for both NTDs and DS. The top ranked dense clique for both the disorders were recognized and over representation analysis was carried out for each of the constituent genes. The comprehensive manual analysis of these genes yields a hypothetical understanding of the lack of familial link between DS and NTDs. There were no genes involved with folic acid present in the dense cliques. Only – CBL, EGFR genes were commonly present, which makes the allelic variants of these genes – good candidates for future studies regarding the familial link between DS and NTDs. Abbreviations NTD - Neural Tube Disorders, DS - Down's Syndrome, MTHFR - Methylenetetrahydrofolate reductase, MTRR– 5 - methyltetrahydrofolate-homocysteine methyltransferase reductase. PMID:23904737

Ragunath, PK; Abhinand, PA

2013-01-01

84

Folic acid and neural tube defect: can't we come to closure?  

PubMed Central

In a series of nonrandomized and randomized intervention trials and case-control and cohort studies, women using multivitamins or folic acid supplements during the first 6 weeks of pregnancy experienced a three- to fourfold reduction in neural tube defects among their offspring. Viewed collectively, these data provide strong evidence that an important subset of US women do not receive sufficient folic acid to minimize their risk of a defective pregnancy. Further, the amounts of folic acid contained in multivitamins (usually 200-400 micrograms per day) appear adequate to greatly reduce, and probably eliminate, the excess risk. PMID:1566943

Willett, W C

1992-01-01

85

Maternal Exposures to Cigarette Smoke, Alcohol, and Street Drugs and Neural Tube Defect Occurrence in Offspring  

Microsoft Academic Search

Objectives  Cigarettes, alcoholic beverages, and street drugs contain substances potentially toxic to the developing embryo. We investigated\\u000a whether maternal cigarette smoking, secondhand smoke exposure, and alcohol or street drug use contributed to neural tube defect\\u000a (NTD) occurrence in offspring.\\u000a \\u000a \\u000a \\u000a Methods  We conducted a population-based case-control study among Mexican American women who were residents of the 14 Texas counties\\u000a bordering Mexico. Case women

Lucina Suarez; Marilyn Felkner; Jean D. Brender; Mark Canfield; Kate Hendricks

2008-01-01

86

Iron Status Indicators in Women with Prior Neural Tube Defect-Affected Pregnancies  

Microsoft Academic Search

\\u000a Objectives: Iron deficiency is the most common nutrient deficiency in pregnant women and has been linked to negative impacts on the\\u000a fetus. We describe the association of various iron-deficiency indices with risk of neural tube defect (NTD) among a high-risk\\u000a Mexican-American population. Methods: The study included 158 case-women (NTD-affected pregnancies) and 189 control-women (normal births) who were residents of\\u000a the

Marilyn M. Felkner; Lucina Suarez; Jean Brender; Barbara Scaife; Kate Hendricks

2005-01-01

87

Maternal Mthfd1 disruption impairs fetal growth but does not cause neural tube defects in mice123  

PubMed Central

Background: MTHFD1 encodes C1-tetrahydrofolate synthase, which is a folate-dependent enzyme that catalyzes the formation and interconversion of folate-activated one-carbon groups for nucleotide biosynthesis and cellular methylation. A polymorphism in MTHFD1 (1958G?A) impairs enzymatic activity and is associated with increased risk of adverse pregnancy outcomes, but the mechanisms are unknown. Objective: The objective of this study was to determine whether disruption of the embryonic or maternal Mthfd1 gene or both interacts with impaired folate and choline status to affect neural tube closure, fetal growth, and fertility in mice and to investigate the underlying metabolic disruptions. Design: Dams with a gene-trapped (gt) allele in Mthfd1 and wild-type dams were fed a control or folate- and choline-deficient AIN93G diet (Dyets Inc). Litters were examined for gross morphologic defects, crown-rump length, and resorptions. Folate status and amounts of folate-related metabolites were determined in pregnant dams. Results: Reduced folate and choline status resulted in severe fetal growth restriction (FGR) and impaired fertility in litters harvested from Mthfd1gt/+ dams, but embryonic Mthfd1gt/+ genotype did not affect fetal growth. Gestational supplementation of Mthfd1gt/+ dams with hypoxanthine increased FGR frequency and caused occasional neural tube defects (NTDs) in Mthfd1gt/+ embryos. Mthfd1gt/+ dams exhibited lower red blood cell folate and plasma methionine concentrations than did wild-type dams. Conclusions: Maternal Mthfd1gt/+ genotype impairs fetal growth but does not cause NTDs when dams are maintained on a folate- and choline-deficient diet. Mthfd1gt/+ mice exhibit a spectrum of adverse reproductive outcomes previously attributed to the human MTHFD1 1958G?A polymorphism. Mthfd1 heterozygosity impairs folate status in pregnant mice but does not significantly affect homocysteine metabolism. PMID:22378735

Beaudin, Anna E; Perry, Cheryll A; Stabler, Sally P; Allen, Robert H; Stover, Patrick J

2012-01-01

88

MicroRNA GENE EXPRESSION SIGNATURES IN THE DEVELOPING NEURAL TUBE  

PubMed Central

BACKGROUND Neurulation requires precise, spatio-temporal expression of numerous genes and coordinated interaction of signal transduction and gene regulatory networks, disruption of which may contribute to the etiology of neural tube (NT) defects. MicroRNAs are key modulators of cell and tissue differentiation. In order to define potential roles of miRNAs in development of the murine NT, miRNA microarray analysis was conducted to establish expression profiles, and identify miRNA target genes and functional gene networks. METHODS miRNA expression profiles in murine embryonic NTs derived from gestational days 8.5, 9.0 and 9.5 were defined and compared utilizing miRXplore™ microarrays from Miltenyi Biotech GmbH. Gene expression changes were verified by TaqMan™ quantitative Real-Time PCR. clValid R package and the UPGMA (hierarchical) clustering method were utilized for cluster analysis of the microarray data. Functional associations among selected miRNAs were examined via Ingenuity Pathway Analysis. RESULTS miRXplore™ chips enabled examination of 609 murine miRNAs. Expression of approximately 12% of these was detected in murine embryonic NTs. Clustering analysis revealed several developmentally regulated expression clusters among these expressed genes. Target analysis of differentially expressed miRNAs enabled identification of numerous target genes associated with cellular processes essential for normal NT development. Utilization of Ingenuity Pathway Analysis revealed interactive biological networks which connected differentially expressed miRNAs with their target genes, and highlighted functional relationships. CONCLUSIONS The present study defined unique gene expression signatures of a range of miRNAs in the developing NT during the critical period of NT morphogenesis. Analysis of miRNA target genes and gene interaction pathways revealed that specific miRNAs may direct expression of numerous genes encoding proteins which have been shown to be indispensable for normal neurulation. This study is the first to identify miRNA expression profiles and their potential regulatory networks in the developing mammalian NT. PMID:21770019

Mukhopadhyay, Partha; Brock, Guy; Appana, Savitri; Webb, Cynthia; Greene, Robert M.; Pisano, M. Michele

2011-01-01

89

Detection of Copy Number Variants Reveals Association of Cilia Genes with Neural Tube Defects  

PubMed Central

Background Neural tube defects (NTDs) are one of the most common birth defects caused by a combination of genetic and environmental factors. Currently, little is known about the genetic basis of NTDs although up to 70% of human NTDs were reported to be attributed to genetic factors. Here we performed genome-wide copy number variants (CNVs) detection in a cohort of Chinese NTD patients in order to exam the potential role of CNVs in the pathogenesis of NTDs. Methods The genomic DNA from eighty-five NTD cases and seventy-five matched normal controls were subjected for whole genome CNVs analysis. Non-DGV (the Database of Genomic Variants) CNVs from each group were further analyzed for their associations with NTDs. Gene content in non-DGV CNVs as well as participating pathways were examined. Results Fifty-five and twenty-six non-DGV CNVs were detected in cases and controls respectively. Among them, forty and nineteen CNVs involve genes (genic CNV). Significantly more non-DGV CNVs and non-DGV genic CNVs were detected in NTD patients than in control (41.2% vs. 25.3%, p<0.05 and 37.6% vs. 20%, p<0.05). Non-DGV genic CNVs are associated with a 2.65-fold increased risk for NTDs (95% CI: 1.24–5.87). Interestingly, there are 41 cilia genes involved in non-DGV CNVs from NTD patients which is significantly enriched in cases compared with that in controls (24.7% vs. 9.3%, p<0.05), corresponding with a 3.19-fold increased risk for NTDs (95% CI: 1.27–8.01). Pathway analyses further suggested that two ciliogenesis pathways, tight junction and protein kinase A signaling, are top canonical pathways implicated in NTD-specific CNVs, and these two novel pathways interact with known NTD pathways. Conclusions Evidence from the genome-wide CNV study suggests that genic CNVs, particularly ciliogenic CNVs are associated with NTDs and two ciliogenesis pathways, tight junction and protein kinase A signaling, are potential pathways involved in NTD pathogenesis. PMID:23349908

Gao, Yonghui; Zhao, Huizhi; Sheng, Xiaoming; Zou, Jizhen; Lip, Va; Xie, Hua; Guo, Jin; Shao, Hong; Bao, Yihua; Shen, Jianliang; Niu, Bo; Gusella, James F.; Wu, Bai-Lin; Zhang, Ting

2013-01-01

90

Neural tube defects and atypical deletion on 22q11.2.  

PubMed

The 22q11.2 deletion syndrome (22q11.2DS) is a common microdeletion disorder. Most of the patients show the common 3?Mb deletion but proximal 1.5?Mb deletion and unusual deletions located outside the common deleted region, have been detected particularly with the advance of comparative cytogenomic microarray technologies. The individuals reported in the literature with unusual deletions involving the 22q11 region, showed milder facial phenotypes, decreased incidence of cardiac anomalies, and intellectual disability. We describe two sibs with an atypical 0.8?Mb microdeletion of chromosome 22q11 who both showed myelomeningocele and mild facial dysmorphisms. The association between neural tube defect and the clinical diagnosis of Di George anomaly/velocardiofacial syndrome is well documented in the literature, but not all cases had molecular studies to determine breakpoint regions. This report helps to narrow a potential critical region for neural tube defects associated with 22q11 deletions. © 2014 Wiley Periodicals, Inc. PMID:25123577

Leoni, Chiara; Stevenson, David A; Geiersbach, Katherine B; Paxton, Christian N; Krock, Bryan L; Mao, Rong; Rope, Alan F

2014-11-01

91

Twist Function Is Required for the Morphogenesis of the Cephalic Neural Tube and the Differentiation of the Cranial Neural Crest Cells in the Mouse Embryo  

Microsoft Academic Search

Loss of Twist function in the cranial mesenchyme of the mouse embryo causes failure of closure of the cephalic neural tube and malformation of the branchial arches. In the Twist?\\/? embryo, the expression of molecular markers that signify dorsal forebrain tissues is either absent or reduced, but those associated with ventral tissues display expanded domains of expression. Dorsoventral organization of

Kenneth Soo; Meredith P. O'Rourke; Poh-Lynn Khoo; Kirsten A. Steiner; Nicole Wong; Richard R. Behringer; Patrick P. L. Tam

2002-01-01

92

Developing Effective Campaign Messages to Prevent Neural Tube Defects: A Qualitative Assessment of Women's Reactions to Advertising Concepts  

Microsoft Academic Search

The incidence of neural tube defects (NTDs), serious birth defects of the brain and spine that affect approximately 3,000 pregnancies in the United States each year, can be reduced by 50–70% with daily periconceptional consumption of the B vitamin folic acid. Two studies were designed to assess college women's reactions to and perceptions of potential campaign advertising concepts derived from

Lisa L. Massi Lindsey; Kami J. Silk; Marlene M. Von Friederichs-Fitzwater; Heather C. Hamner; Christine E. Prue; Franklin J. Boster

2009-01-01

93

Long term effects of periconceptional multivitamin supplements for prevention of neural tube defects: a seven to 10 year follow up  

Microsoft Academic Search

Periconceptional supplementation with Pregnavite Forte F was offered to women who presented consecutively to the Oxford genetic counselling service in the early 1980s who had previously had one or more pregnancies complicated by a neural tube defect. The first 100 children born alive to these women are the subject of this study. Birth weight, gestation, and congenital abnormalities were recorded.

M Holmes-Siedle; J Dennis; R H Lindenbaum; A Galliard

1992-01-01

94

Gene Regulatory Logic for Reading the Sonic Hedgehog Signaling Gradient in the Vertebrate Neural Tube  

PubMed Central

Summary Secreted signals, known as morphogens, provide the positional information that organizes gene expression and cellular differentiation in many developing tissues. In the vertebrate neural tube, Sonic Hedgehog (Shh) acts as a morphogen to control the pattern of neuronal subtype specification. Using an in vivo reporter of Shh signaling, mouse genetics, and systems modeling, we show that a spatially and temporally changing gradient of Shh signaling is interpreted by the regulatory logic of a downstream transcriptional network. The design of the network, which links three transcription factors to Shh signaling, is responsible for differential spatial and temporal gene expression. In addition, the network renders cells insensitive to fluctuations in signaling and confers hysteresis—memory of the signal. Our findings reveal that morphogen interpretation is an emergent property of the architecture of a transcriptional network that provides robustness and reliability to tissue patterning. PMID:22265416

Balaskas, Nikolaos; Ribeiro, Ana; Panovska, Jasmina; Dessaud, Eric; Sasai, Noriaki; Page, Karen M.; Briscoe, James; Ribes, Vanessa

2012-01-01

95

A familial association between twinning and upper-neural tube defects.  

PubMed Central

An increased twinning rate has been observed in the near relatives (sibs, parents, and aunts and uncles) of probands with neural tube defects (NTDs) occurring at the level of the 11th thoracic vertebra and above (upper NTDs). The twin rate was more than double that of the near relatives of probands with lower NTDs and of those of probands with Mendelian disorders (the controls). The excess twinning was same sex and can therefore consist of either MZ or same-sex DZ twins. Furthermore, upper-NTD families with twins had a higher NTD-sibling occurrence rate than did families without twins. These findings, if corroborated, may imply an etiology common to twinning and NTDs and can perhaps be applied in counseling NTD families. PMID:7977342

Garabedian, B. H.; Fraser, F. C.

1994-01-01

96

Multiple neural tube defects in the same patient with no neurological deficit  

PubMed Central

Congenital deformities involving the coverings of the nervous system are called neural tube defects (NTDs). NTD can be classified as neurulation defects, which occur by stage 12, and postneurulation defects. Cervical meningocele and myelomeningocele are rare spinal dysraphic lesions. Unlike lumbosacral dysraphic lesions, there is often no neurologic deficits and thus the subtle features of cervical cord tethering may be overlooked on imaging. The presence of meningomyelocele and/or encephaloceles at multiple (two or more) sites along the vertebral axis is a very rare event occurring in <1% of cases. Less than 10 cases have been described in the published literature. We are reporting a case of multiple NTD in same patient with no neurological deficit. PMID:21042511

Tungaria, Arun; Srivastav, Arun Kumar; Mahapatra, Ashok K.; Kumar, Raj

2010-01-01

97

Are common mutations of cystathionine beta-synthase involved in the aetiology of neural tube defects?  

PubMed

Mildly elevated maternal plasma homocysteine (Hcy) levels (hyperhomocysteinemia) have recently been observed in some neural tube defect (NTD) pregnancies. Plasma levels of Hcy are governed by both genetic and nutritional factors and the aetiology of NTDs is also known to have both genetic and nutritional components. We therefore examined the frequency of relatively common mutations in the enzyme cystathionine beta-synthase (CBS), which is one of the main enzymes that controls Hcy levels, in the NTD population. Neither the severely dysfunctional G307S CBS allele nor the recently reported 68 bp insertion/I278T CBS allele was observed at increased frequency in the cases relative to controls. We therefore conclude that loss of function CBS alleles do not account for a significant proportion of NTDs in Ireland. PMID:9084933

Ramsbottom, D; Scott, J M; Molloy, A; Weir, D G; Kirke, P N; Mills, J L; Gallagher, P M; Whitehead, A S

1997-01-01

98

Genetic Association Analyses of Nitric Oxide Synthase Genes and Neural Tube Defects Vary by Phenotype  

PubMed Central

Neural tube defects (NTDs) are caused by improper neural tube closure during the early stages of embryonic development. NTDs are hypothesized to have a complex genetic origin and numerous candidate genes have been proposed. The nitric oxide synthase 3 (NOS3) G594T polymorphism has been implicated in risk for spina bifida, and interactions between that single nucleotide polymorphism (SNP) and the methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism have also been observed. To evaluate other genetic variation in the NO pathway in the development of NTDs, we examined all three NOS genes: NOS1, NOS2, and NOS3. Using 3109 Caucasian samples in 745 families, we evaluated association in the overall dataset and within specific phenotypic subsets. Haplotype tagging SNPs in the NOS genes were tested for genetic association with NTD subtypes, both for main effects as well as for the presence of interactions with the MTHFR C677T polymorphism. Nominal main effect associations were found with all subtypes, across all three NOS genes, and interactions were observed between SNPs in all three NOS genes and MTHFR C677T. Unlike the previous report, the most significant associations in our dataset were with cranial subtypes and the AG genotype of rs4795067 in NOS2 (p = 0.0014) and the interaction between the rs9658490 G allele in NOS1 and MTHFR 677TT genotype (p = 0.0014). Our data extend the previous findings by implicating a role for all three NOS genes, independently and through interactions with MTHFR, in risk not only for spina bifida, but all NTD subtypes. PMID:24323870

Soldano, Karen L.; Garrett, Melanie E.; Cope, Heidi L.; Rusnak, J. Michael; Ellis, Nathen J.; Dunlap, Kaitlyn L.; Speer, Marcy C.; Gregory, Simon G.; Ashley-Koch, Allison E.

2014-01-01

99

Using artificial neural networks to model extrusion processes for the manufacturing of polymeric micro-tubes  

NASA Astrophysics Data System (ADS)

In this paper a methodology and an application example are presented aiming to show how Artificial Neural Networks (ANNs) can be used to model manufacturing processes when mathematical models are missing or are not applicable e.g. due to the micro- & nano-scaling, due to non-conventional processes, etc. Besides the ANNs methodology, the results of a Software System developed will be presented, which was used to create ANNs models for micro & nano manufacturing processes. More specifically results of a specific application example will be presented, concerning the modeling of extrusion processes for polymeric micro-tubes. ANNs models are capable for modeling manufacturing processes as far as adequate experimental and/or historical data of processes' inputs & outputs are available for their training. The POLYTUBES ANNs models have been trained and tested with experimental data records of process' inputs and outputs concerning a micro-extrusion process of polymeric micro-tubes for several materials such as: COC, PC, PET, PETG, PP and PVDF. The main ANN model of the extrusion application example has 3 inputs and 9 outputs. The inputs are: tube's inner & outer diameters, and the material density. The model outputs are 9 process parameters, which correspond to the specific inputs e.g. process temperature, die inner & outer diameters, extrusion pressure, draw speed etc. The training of the ANN model was completed, when the errors for the model's outputs, which expressed the difference between the training target values and the ANNs outputs, were minimized to acceptable levels. After the training, the micro-extrusion ANN is capable to simulate the process and can be used to calculate model's outputs, which are the process parameters for any new set of inputs. By this way a satisfactory functional approximation of the whole process is achieved. This research work has been supported by the EU FP7 NMP project POLYTUBES.

Mekras, N.; Artemakis, I.

2012-09-01

100

Transcriptome Profiling of Genes Involved in Neural Tube Closure During Human Embryonic Development Using Long Serial Analysis of Gene Expression (Long-SAGE)  

PubMed Central

Background Neural tube defects (NTDs) are common human birth defects with a complex etiology. To develop a comprehensive knowledge of the genes expressed during normal neurulation, we established transcriptomes from human neural tube fragments during and after neurulation using long Serial Analysis of Gene Expression (long-SAGE). Methods Rostral and caudal neural tubes were dissected from normal human embryos aged between 26 and 32 days of gestation. Tissues from the same region and Carnegie stage were pooled (n>=4) and total RNA extracted to construct four long-SAGE libraries. Tags were mapped using the UniGene Homo sapiens 17 bp tag-to-gene best mapping set. Differentially expressed genes were identified by chi-square or Fisher’s exact test and validation was performed for a subset of those transcripts using in situ hybridization. In silico analyses were performed with BinGO and EXPANDER. Results We observed most genes to be similarly regulated in rostral and caudal regions, but expression profiles differed during and after closure. In silico analysis found similar enrichments in both regions for biological process terms, transcription factor binding and miRNA target motifs. Twelve genes potentially expressing alternate isoforms by region or developmental stage, and the miRNAs miR-339-5p, miR-141/200a, miR-23ab, and miR-129/129-5p, are among several potential candidates identified here for future research. Conclusions Time appears to influence gene expression in the developing central nervous system more than location. These data provide a novel complement to traditional strategies of identifying genes associated with human NTDs, and offer unique insight into the genes associated with normal human neurulation. PMID:22806986

Krupp, D. R.; Xu, P-T.; Thomas, S.; Dellinger, A.; Etchevers, H. C.; Vekemans, M.; Gilbert, J. R.; Speer, M.C.; Ashley-Koch, A. E.; Gregory, S. G.

2012-01-01

101

Evidence for multi-site closure of the neural tube in humans.  

PubMed

Four separate initiation sites for neural tube (NT) fusion have been demonstrated recently in mice and other experimental animals. We evaluated the question of whether the multisite model vs. the traditional single-site model of NT closure provided the best explanation for neural tube defects (NTDs) in humans. Evidence for segmental vs. continuous NT closure was obtained by review of our recent clinical cases of NTDs and previous medical literature. With the multi-site NT closure model, we find that the majority of NTDs can be explained by failure of fusion of one of the closures or their contiguous neuropores. We hypothesize that: Anencephaly results from failure of closure 2 for meroacranium and closures 2 and 4 for holoacranium. Spina-bifida cystica results from failure of rostral and/or caudal closure 1 fusion. Craniorachischisis results from failure of closures 2, 4, and 1. Closure 3 non-fusion is rare, presenting as a midfacial cleft extending from the upper lip through the frontal area ("facioschisis"). Frontal and parietal cephaloceles occur at the sites of the junctions of the cranial closures 3-2 and 2-4 (the prosencephalic and mesencephalic neuropores). Occipital cephaloceles result from incomplete membrane fusion of closure 4. In humans, the most caudal NT may have a 5th closure site involving L2 to S2. Closure below S2 is by secondary neurulation. Evidence for multi-site NT closure is apparent in clinical cases of NTDs, as well as in previous epidemiological studies, empiric recurrence risk studies, and pathological studies. Genetic variations of NT closures sites occur in mice and are evident in humans, e.g., familial NTDs with Sikh heritage (closure 4 and rostral 1), Meckel-Gruber syndrome (closure 4), and Walker-Warburg syndrome (2-4 neuropore, closure 4). Environmental and teratogenic exposures frequently affect specific closure sites, e.g., folate deficiency (closures 2, 4, and caudal 1) and valproic acid (closure 5 and canalization). Classification of NTDs by closure site is recommended for all studies of NTDs in humans.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:8267004

Van Allen, M I; Kalousek, D K; Chernoff, G F; Juriloff, D; Harris, M; McGillivray, B C; Yong, S L; Langlois, S; MacLeod, P M; Chitayat, D

1993-10-01

102

Background on the Brain This chapter describes some of the principal cell types and structures of the brain  

E-print Network

. BRAIN DEVELOPMENT Soon after conception, a neural plate folds onto itself to form the neural tube), the mesencephalon (midbrain), and the rhombencephalon (hind- brain). The prosencephalon develops23 !" !# !$ !% !! !& !' &( &) &* &" &# &$ &% &! && &' ( ) * " # $ % ! & 2 Background on the Brain

Allman, John M.

103

Folate Deficiency and Folic Acid Supplementation: The Prevention of Neural-Tube Defects and Congenital Heart Defects  

PubMed Central

Diet, particularly vitamin deficiency, is associated with the risk of birth defects. The aim of this review paper is to show the characteristics of common and severe neural-tube defects together with congenital heart defects (CHD) as vitamin deficiencies play a role in their origin. The findings of the Hungarian intervention (randomized double-blind and cohort controlled) trials indicated that periconceptional folic acid (FA)-containing multivitamin supplementation prevented the major proportion (about 90%) of neural-tube defects (NTD) as well as a certain proportion (about 40%) of congenital heart defects. Finally the benefits and drawbacks of three main practical applications of folic acid/multivitamin treatment such as (i) dietary intake; (ii) periconceptional supplementation; and (iii) flour fortification are discussed. The conclusion arrived at is indeed confirmation of Benjamin Franklin’s statement: “An ounce of prevention is better than a pound of care”. PMID:24284617

Czeizel, Andrew E.; Dudás, Istvan; Vereczkey, Attila; Bánhidy, Ferenc

2013-01-01

104

Classification of Educational Backgrounds of Students Using Musical Intelligence and Perception with the Help of Artificial Neural Networks  

Microsoft Academic Search

In this study we demonstrate that machine learning can be used to classify students who had backgrounds in positive sciences (including engineering, science and math disciplines) vs. social sciences (including arts and humanities disciplines) by the help of musical hearing and perception using artificial neural networks. Our 80 test subjects had an even mixture of both aforementioned disciplines. Each participant

Naciye Hardalaç; Nevhiz Ercan; Firat Hardalaç; Salih Ergüt

2006-01-01

105

Classification of educational backgrounds of students using musical intelligence and perception with the help of genetic neural networks  

Microsoft Academic Search

In this study we demonstrate that machine learning can be used to classify students who had backgrounds in positive sciences (including engineering, science and math disciplines) vs. social sciences (including arts and humanities disciplines) by the help of musical hearing and perception using artificial neural networks. Our 80 test subjects had an even mixture of both aforementioned disciplines. Each participant

Firat Hardalaç

2009-01-01

106

[Indications for an increased risk of neural tube defects in pregnancies following ovulation induction and (or) in-vitro fertilization].  

PubMed

Several authors have reported a possible association between IVF or induction of ovulation on the one hand and the occurrence of neural tube defects on the other hand. Here a review is given of recent literature on this subject, including data available from The Netherlands. Collaborative epidemiologic studies are needed to evaluate the potential risks. In individual pregnancies prenatal examination is advised. In spontaneous abortions fetal pathological evaluation is desirable. PMID:2374625

Cornel, M C; de Jong-van den Berg, L T; Koudstaal, J; Wiegerinck, M A; te Meerman, G J; ten Kate, L P

1990-07-14

107

Polymorphisms within the vitamin B 12 dependent methylmalonyl-coA mutase are not risk factors for neural tube defects  

Microsoft Academic Search

Methionine synthase and methylmalonyl-CoA mutase (mutase) are the only two known vitamin B12 (B12) dependent enzymes in humans. A lower level of B12 has been shown to be an independent maternal risk factor for neural tube defects (NTDs) prompting an investigation of common genetic variants within B12 dependent enzymes. To investigate the role of methylmalonyl-CoA mutase variants we studied 279

Anne Parle-McDermott; Edward J McManus; James L Mills; Valerie B O’Leary; Faith Pangilinan; Christopher Cox; Andrea Weiler; Anne M Molloy; Mary Conley; Deborah Watson; John M Scott; Lawrence C Brody; Peadar N Kirke

2003-01-01

108

Dieting to Lose Weight and Occurrence of Neural Tube Defects in Offspring of Mexican–American Women  

Microsoft Academic Search

Lowered maternal weight gain and reduction in early pregnancy have been associated with risk of neural tube defects (NTDs)\\u000a in offspring. We examined the association of self-reported maternal dieting behaviors on the occurrence of NTDs. We conducted\\u000a a population based case–control study among Mexican–American women who were residents of the 14 Texas counties bordering Mexico.\\u000a Case women had an NTD-affected

Lucina Suarez; Marilyn Felkner; Jean D. Brender; Mark A. Canfield

109

Drinking water treatment is not associated with an observed increase in neural tube defects in mice.  

PubMed

Disinfection by-products (DBPs) arise when natural organic matter in source water reacts with disinfectants used in the water treatment process. Studies have suggested an association between DBPs and birth defects. Neural tube defects (NTDs) in embryos of untreated control mice were first observed in-house in May 2006 and have continued to date. The source of the NTD-inducing agent was previously determined to be a component of drinking water. Tap water samples from a variety of sources were analyzed for trihalomethanes (THMs) to determine if they were causing the malformations. NTDs were observed in CD-1 mice provided with treated and untreated surface water. Occurrence of NTDs varied by water source and treatment regimens. THMs were detected in tap water derived from surface water but not detected in tap water derived from a groundwater source. THMs were absent in untreated river water and laboratory purified waters, yet the percentage of NTDs in untreated river water were similar to the treated water counterpart. These findings indicate that THMs were not the primary cause of NTDs in the mice since the occurrence of NTDs was unrelated to drinking water disinfection. PMID:24497082

Melin, Vanessa E; Johnstone, David W; Etzkorn, Felicia A; Hrubec, Terry C

2014-06-01

110

Folic acid supplementation during pregnancy protects against lipopolysaccharide-induced neural tube defects in mice.  

PubMed

Folic acid is a water-soluble B-complex vitamin. Increasing evidence demonstrates that physiological supply of folic acid during pregnancy prevents folic acid deficiency-related neural tube defects (NTDs). Previous studies showed that maternal lipopolysaccharide (LPS) exposure caused NTDs in rodents. The aim of this study was to investigate the effects of high-dose folic acid supplementation during pregnancy on LPS-induced NTDs. Pregnant mice were intraperitoneally injected with LPS (20 ?g/kg/d) from gestational day (GD) 8 to GD12. As expected, a five-day LPS injection resulted in 19.96% of fetuses with NTDs. Interestingly, supplementation with folic acid (3mg/kg/d) during pregnancy significantly alleviated LPS-induced NTDs. Additionally, folic acid significantly attenuated LPS-induced fetal growth restriction and skeletal malformations. Additional experiment showed that folic acid attenuated LPS-induced glutathione (GSH) depletion in maternal liver and placentas. Moreover, folic acid significantly attenuated LPS-induced expression of placental MyD88. Additionally, folic acid inhibited LPS-induced c-Jun NH2-terminal kinase (JNK) phosphorylation and nuclear factor kappa B (NF-?B) activation in placentas. Correspondingly, folic acid significantly attenuated LPS-induced tumor necrosis factor (TNF)-?, interleukin (IL)-1? and IL-6 in placentas, maternal serum and amniotic fluid. In conclusion, supplementation with high-dose folic acid during pregnancy protects against LPS-induced NTDs through its anti-inflammatory and anti-oxidative effects. PMID:24177262

Zhao, Mei; Chen, Yuan-Hua; Chen, Xue; Dong, Xu-Ting; Zhou, Jun; Wang, Hua; Wu, Shu-Xian; Zhang, Cheng; Xu, De-Xiang

2014-01-13

111

Metabolic signature of pregnant women with neural tube defects in offspring.  

PubMed

Neural tube defects (NTDs) are one of the most common types of birth defects, affecting approximately 1 of every 1000 pregnancies in the United States and an estimated 300?000 newborns worldwide each year. The metabolic signature of pregnant women with NTDs in offspring has not previously been characterized. In this paper, we report a profiling study that characterized the serum metabolome of 101 pregnant women affected with NTDs in offspring in comparison with 143 pregnant women with normal pregnancy outcomes in Lvliang prefecture, the area with the highest birth prevalence of NTDs in China. A serum metabonomic study was also conducted to identify significantly altered metabolites associated with di-n-butyl phthalate (DBP)-induced teratogenesis in mice. The metabolic signature of NTD in pregnant women is characterized by the impaired mitochondrial respiration, neurotransmitter ?-aminobutyric acid, and methionine cycle. Of interest, consistent findings from DBP-induced teratogenesis in mice demonstrated increased succinate and decreased fumarate, suggesting an inhibited succinic dehydrogenase implicated in the defective mitochondria. The characteristic disruption of maternal metabolism offers important insights into metabolic mechanisms underlying human NTDs as well as potential preventive strategies. PMID:21902205

Zheng, Xiaoying; Su, Mingming; Pei, Lijun; Zhang, Ting; Ma, Xu; Qiu, Yunping; Xia, Hongfei; Wang, Fang; Zheng, Xiaojiao; Gu, Xue; Song, Xinming; Li, Xin; Qi, Xin; Chen, Gong; Bao, Yihua; Chen, Tianlu; Chi, Yi; Zhao, Aihua; Jia, Wei

2011-10-01

112

In vivo dual luciferase reporter assay with chick neural tube in ovo electroporation system.  

PubMed

Luciferase reporter systems are widely employed to provide a quantitative readout of gene expression for studies of transcriptional regulation, translation efficiency, and cell signaling. The most common application of luciferase involves transient transfections into cells in vitro or in vivo. In both cases, the normal variability inherent in transfection approaches can introduce significant errors into the data that makes comparison between separate experiments problematic. The dual luciferase reporter assay system (DLR, Promega, WI, USA) is designed to control for this technical issue by using a co-transfection approach with two separate reporter proteins that emit at distinct wavelengths: one from firefly (Photinus pyralis) and the second from Renilla (Renilla reniformis). By normalizing experimental luciferase readings to an internal control transfected under the same conditions, these problems can be largely negated. Here, we describe a method for applying this technique to an in vivo system, the developing chick embryo neural tube. This system provides a physiologically relevant context for functional studies in a spatially and/or temporally controlled manner. PMID:23681631

Wang, Hui; Matise, Michael P

2013-01-01

113

Orally Administered Melatonin Prevents Lipopolysaccharide-Induced Neural Tube Defects in Mice  

PubMed Central

Lipopolysaccharide (LPS) has been associated with adverse pregnant outcomes, including fetal demise, intra-uterine growth restriction (IUGR), neural tube defects (NTDs) and preterm delivery in rodent animals. Previous studies demonstrated that melatonin protected against LPS-induced fetal demise, IUGR and preterm delivery. The aim of the present study was to investigate the effects of melatonin on LPS-induced NTDs. All pregnant mice except controls were intraperitoneally injected with LPS (25 µg/kg) daily from gestational day (GD)8 to GD12. Some pregnant mice were orally administered with melatonin (MT, 50 mg/kg) before each LPS injection. A five-day LPS injection resulted in 27.5% of fetuses with anencephaly, exencephaly or encephalomeningocele. Additional experiment showed that maternal LPS exposure significantly down-regulated placental proton-coupled folate transporter (pcft) and disturbed folate transport from maternal circulation through the placentas into the fetus. Interestingly, melatonin significantly attenuated LPS-induced down-regulation of placental pcft. Moreover, melatonin markedly improved the transport of folate from maternal circulation through the placentas into the fetus. Correspondingly, orally administered melatonin reduced the incidence of LPS-induced anencephaly, exencephaly or encephalomeningocele. Taken together, these results suggest that orally administered melatonin prevents LPS-induced NTDs through alleviating LPS-induced disturbance of folate transport from maternal circulation through the placenta into the fetus. PMID:25420102

Chen, Yuan-Hua; Xia, Mi-Zhen; Wang, Hua; Zhang, Cheng; Tao, Fang-Biao; Xu, De-Xiang

2014-01-01

114

Prediction of active nodes in the transcriptional network of neural tube patterning  

PubMed Central

A transcriptional network governs patterning in the developing spinal cord. As the developmental program runs, the levels of sequence-specific DNA-binding transcription factors (SSTFs) in each progenitor cell type change to ultimately define a set of postmitotic populations with combinatorial codes of expressed SSTFs. A network description of the neural tube (NT) transcriptional patterning process will require definition of nodes (SSTFs and target enhancers) and edges (interactions between nodes). There are 1,600 SSTF nodes in a given mammalian genome. To limit the complexity of a network description, it will be useful to discriminate between active and passive SSTF nodes. We define active SSTF nodes as those that are differentially expressed within the system. Our system, the developing NT, was partitioned into two pools of genetically defined populations by using flow sorting. Microarray comparisons across the partition led to an estimate of 500–700 active SSTF nodes in the transcriptional network of the developing NT. These included most of the 66 known SSTFs assembled from review articles and recent reports on NT patterning. Empirical cutoffs based on the performance of knowns were used to identify 188 further active SSTFs nodes that performed similarly. The general utility and limitations of the population-partitioning paradigm are discussed. PMID:17132738

Kioussi, Chrissa; Shih, Hung-Ping; Loflin, John; Gross, Michael K.

2006-01-01

115

Management of abnormal serum markers in the absence of aneuploidy or neural tube defects  

PubMed Central

Objective Few guidelines address the management of pregnancies complicated by abnormal maternal serum analytes (MSAs) in the absence of aneuploidy or neural tube defects (NTDs). Our objective was to gather preliminary data regarding current opinions and management strategies among perinatologists in the US. Methods This survey of Maternal Fetal Medicine (MFM) physicians and fellows used a secure electronic web-based data capture tool. Results A total of 545 potential participants were contacted, and 136 (25%) responded. The majority were experienced academic physicians with robust practices. Nearly all (97.7%) respondents reported a belief in an association between abnormal MSAs and adverse pregnancy outcomes other than aneuploidy or NTDs. Plasma protein A (PAPP-A) and ?-fetoprotein (AFP) were most often chosen as markers demonstrating a strong association with adverse outcomes. Most (86.9%) respondents acknowledged that abnormal MSAs influenced their counseling approach, and the majority (80.1%) offered additional ultrasound examinations. Nearly half started at 28 weeks and almost one-third at 32 weeks. Respondents acknowledging a relevant protocol in their hospital or practice were more likely to offer additional antenatal testing (p = 0.01). Conclusions Although most perinatologists were in agreement regarding the association of MSAs with adverse pregnancy outcomes, a lack of consensus exists regarding management strategies. PMID:22372385

Schnettler, William T.; Hacker, Michele R.; Barber, Rachel E.; Rana, Sarosh

2013-01-01

116

Role of arsenic as a reproductive toxin with particular attention to neural tube defects  

SciTech Connect

Arsenic has been recognized as a human toxicant for over 2000 years. More recently it has been readily accepted as a human carcinogen. Animal research has demonstrated arsenic`s ability to have profound detrimental effects on the developing embryo in avian and mamalian species. This article comprehensively reviews the human and animal literature on the subject of the reproductive toxicity of arsenic. A variety of endpoints are considered, including spontaneous abortion, cardiovascular defects, and arsenic`s role in the causation of neural tube defects (NTDs). A summary of the literature that has examined the various postulated mechanisms by which arsenic may produce NTDs is also considered. In addition, a discussion of literature relative to the presence of arsenic in the general environment and in the workplace presented. This article reaches the conclusion that while further research is clearly needed, particularly on the potential toxicity of organic arsenical compounds, the current literature suggests it may be prudent and appropriate to treat inorganic arsenic as a probable human reproductive toxin. 132 refs.

Shalat, S.L.; Walker, D.B.; Finnell, R.H. [Texas A& M Univ., College Station, TX (United States)

1996-10-01

117

Field emission characteristics of carbon nano tubes under varying background pressure conditions  

Microsoft Academic Search

In general, for plasma switches, the initiation of the plasma is critical and this is usually achieved by a żtriggerż scheme. The seed electrons needed to initiate a breakdown can be generated by several means such as thermionic, field or optical emission. While the thermionic emission has been used mainly in vacuum tubes and is a mature technology, field emission

Shaomao Li; Hulya Kirkici

2009-01-01

118

Developmental neurotoxicity role of cyclophosphamide on post-neural tube closure of rodents in vitro and in vivo.  

PubMed

To evaluate the possible developmental role of cyclophosphamide on post-neural tube closure of rodents, the 46 pregnant rats of 2.5-3 months old were randomly divided into five groups. On the 13th day of gestation, the rats in control and experimental groups were treated with physiological saline and cyclophosphamide (7.5, 10.5, 12.5 and 15.0 mg/kg bw), respectively. On the 14th day of gestation, three rats each selected randomly from control and experimental (12.5 mg/kg bw) group, respectively, were executed and the embryo brains were checked using both light microscope and transmission electron microscope. Neurocytotoxic effects of cyclophosphamide were determined using tetrazolium dye (MTT) assay, single cell gel electrophoresis, flow cytometry and scanning electron microscope. Compared with control group, the malformation incidence of the experimental groups (except the group 7.5 mg/kg bw) was significantly higher, especially in 12.5 mg/kg bw group (malformation incidence 98%, lethality 0). Neural tube serial section of fetus showed the apoptotic morphological features after 24 h cyclophosphamide administrated. Cyclophosphamide (8 microg/ml) decreased the growth and viability of neurons, damaged nuclear DNA and induced early apoptotic morphological changes. Our study shows that the teratogenesis of cyclophosphamide after neural tube closure are involved in cyclophosphamide-induced neuronal apoptosis and DNA damage. PMID:18022788

Xiao, R; Yu, Huan L; Zhao, Hai F; Liang, J; Feng, Jin F; Wang, W

2007-12-01

119

Folate supplementation, MTHFR gene polymorphism and neural tube defects: a community based case control study in North India.  

PubMed

The present study analyses the potential role of MTHFR gene polymorphism, folate supplementation and dietary pattern among the mothers of NTD neonates and controls in heterogeneous populations of North India, with the special focus on their ethnic labels. Results indicated significant increased risk for neural tube defects with respect to low folic acid supplementation and vegetarian diet in univariate and multivariate analyses. There was no significant difference in the genotypic or allelic distribution of MTHFR C677T polymorphism, however, high frequency of CT genotype, as observed, among controls suggests heterozygous advantage probably due to supplementary folate. Among the two communities, Muslim NTD mothers had higher TT genotype showing increased risk for neural tube defects (adjusted OR: 12.9; 95% CI: 1.21-136.8) and lower folic acid supplementation (adjusted OR: 3.5; 95% CI: 1.18-10.22). Whereas, marginal increased risk for NTDs with vegetarian diet was observed among Hindus. Cultural and ethnic variation in the risk factors for neural tube defects is highlighted in the study. PMID:21792640

Deb, Roumi; Arora, Jyoti; Meitei, Sanjenbam Yaiphaba; Gupta, Sangeeta; Verma, Vanita; Saraswathy, Kallur Nava; Saran, Sunil; Kalla, Aloke Kumar

2011-09-01

120

Case-control study of association of maternal recall of diarrhea or use of antimicrobials in the periconceptional period and neural tube defects  

Microsoft Academic Search

In June 1995 a case-control study was initiated by the Texas Department of Health among Mexican American women residing in the fourteen counties of the Texas-Mexico border. Case-women had carried infants with neural tube defect. Control-women had given birth to infants without neural tube defects. The case-control protocol included a general questionnaire which elicited information regarding illnesses experienced and antibiotics

Marilyn Moss Felkner

2001-01-01

121

Kif11 dependent cell cycle progression in radial glial cells is required for proper neurogenesis in the zebrafish neural tube.  

PubMed

Radial glia serve as the resident neural stem cells in the embryonic vertebrate nervous system, and their proliferation must be tightly regulated to generate the correct number of neuronal and glial cell progeny in the neural tube. During a forward genetic screen, we recently identified a zebrafish mutant in the kif11 loci that displayed a significant increase in radial glial cell bodies at the ventricular zone of the spinal cord. Kif11, also known as Eg5, is a kinesin-related, plus-end directed motor protein responsible for stabilizing and separating the bipolar mitotic spindle. We show here that Gfap+ radial glial cells express kif11 in the ventricular zone and floor plate. Loss of Kif11 by mutation or pharmacological inhibition with S-trityl-L-cysteine (STLC) results in monoastral spindle formation in radial glial cells, which is characteristic of mitotic arrest. We show that M-phase radial glia accumulate over time at the ventricular zone in kif11 mutants and STLC treated embryos. Mathematical modeling of the radial glial accumulation in kif11 mutants not only confirmed an ~226× delay in mitotic exit (likely a mitotic arrest), but also predicted two modes of increased cell death. These modeling predictions were supported by an increase in the apoptosis marker, anti-activated Caspase-3, which was also found to be inversely proportional to a decrease in cell proliferation. In addition, treatment with STLC at different stages of neural development uncovered two critical periods that most significantly require Kif11 function for stem cell progression through mitosis. We also show that loss of Kif11 function causes specific reductions in oligodendroglia and secondary interneurons and motorneurons, suggesting these later born populations require proper radial glia division. Despite these alterations to cell cycle dynamics, survival, and neurogenesis, we document unchanged cell densities within the neural tube in kif11 mutants, suggesting that a mechanism of compensatory regulation may exist to maintain overall proportions in the neural tube. We propose a model in which Kif11 normally functions during mitotic spindle formation to facilitate the progression of radial glia through mitosis, which leads to the maturation of progeny into specific secondary neuronal and glial lineages in the developing neural tube. PMID:24370453

Johnson, Kimberly; Moriarty, Chelsea; Tania, Nessy; Ortman, Alissa; DiPietrantonio, Kristina; Edens, Brittany; Eisenman, Jean; Ok, Deborah; Krikorian, Sarah; Barragan, Jessica; Golé, Christophe; Barresi, Michael J F

2014-03-01

122

Maternal Exposure to Ambient Levels of Benzene and Neural Tube Defects among Offspring: Texas, 1999-2004  

PubMed Central

Background Previous studies have reported positive associations between maternal exposure to air pollutants and several adverse birth outcomes. However, there have been no studies assessing the association between environmental levels of hazardous air pollutants, such as benzene, and neural tube defects (NTDs), a common and serious group of congenital malformations. Objective Our goal was to conduct a case–control study assessing the association between ambient air levels of benzene, toluene, ethylbenzene, and xylene (BTEX) and the prevalence of NTDs among offspring. Methods The Texas Birth Defects Registry provided data on NTD cases (spina bifida and anencephaly) delivered between 1999 and 2004. The control group was a random sample of unaffected live births, frequency matched to cases on year of birth. Census tract–level estimates of annual BTEX levels were obtained from the U.S. Environmental Protection Agency 1999 Assessment System for Population Exposure Nationwide. Restricted cubic splines were used in mixed-effects logistic regression models to determine associations between each pollutant and NTD phenotype. Results Mothers living in census tracts with the highest benzene levels were more likely to have offspring with spina bifida than were women living in census tracts with the lowest levels (odds ratio = 2.30; 95% confidence interval, 1.22–4.33). No significant associations were observed between anencephaly and benzene or between any of the NTD phenotypes and toluene, ethylbenzene, or xylene. Conclusion In the first study to assess the relationship between environmental levels of BTEX and NTDs, we found an association between benzene and spina bifida. Our results contribute to the growing body of evidence regarding air pollutant exposure and adverse birth outcomes. PMID:20923742

Lupo, Philip J.; Symanski, Elaine; Waller, D. Kim; Chan, Wenyaw; Langlois, Peter H.; Canfield, Mark A.; Mitchell, Laura E.

2011-01-01

123

Maternal exposure to arsenic, cadmium, lead, and mercury and neural tube defects in offspring  

SciTech Connect

Arsenic, cadmium, lead, and mercury are neurotoxins, and some studies suggest that these elements might also be teratogens. Using a case-control study design, we investigated the relation between exposure to these heavy metals and neural tube defects (NTDs) in offspring of Mexican-American women living in 1 of the 14 Texas counties bordering Mexico. A total of 184 case-women with NTD-affected pregnancies and 225 control-women with normal live births were interviewed about their environmental and occupational exposures during the periconceptional period. Biologic samples for blood lead and urinary arsenic, cadmium, and mercury were also obtained for a subset of these women. Overall, the median levels of these biomarkers for heavy metal exposure did not differ significantly (P>0.05) between case- and control-women. However, among women in the highest income group, case-women were nine times more likely (95% confidence interval (CI) 1.4-57) than control-women to have a urinary mercury >=5.62{mu}g/L. Case-women were 4.2 times more likely (95% CI 1.1-16) to report burning treated wood during the periconceptional period than control-women. Elevated odds ratios (ORs) were observed for maternal and paternal occupational exposures to arsenic and mercury, but the 95% CIs were consistent with unity. The 95% CIs of the ORs were also consistent with unity for higher levels of arsenic, cadmium, lead, and mercury in drinking water and among women who lived within 2 miles at the time of conception to industrial facilities with reported emissions of any of these heavy metals. Our findings suggest that maternal exposures to arsenic, cadmium, or lead are probably not significant risk factors for NTDs in offspring. However, the elevated urinary mercury levels found in this population and exposures to the combustion of treated wood may warrant further investigation.

Brender, Jean D. [Department of Epidemiology and Biostatistics, Texas A and M School of Rural Public Health, Texas A and M University System Health Science Center, Bryan, TX 77802 (United States)]. E-mail: jdbrender@aol.com; Suarez, Lucina [Division of Prevention and Preparedness, Texas Department of State Health Services, Austin, TX (United States); Felkner, Marilyn [Division of Prevention and Preparedness, Texas Department of State Health Services, Austin, TX (United States); Gilani, Zunera [Division of Prevention and Preparedness, Texas Department of State Health Services, Austin, TX (United States); Stinchcomb, David [Center for Health Statistics, Texas Department of State Health Services, Austin, TX (United States); Moody, Karen [Department of Health Services Research, Texas State University, San Marcos, TX (United States); Henry, Judy [Division of Prevention and Preparedness, Texas Department of State Health Services, Austin, TX (United States); Hendricks, Katherine [Medical Institute, Austin, TX (United States)

2006-05-15

124

Maternal Dietary Patterns are Associated With Risk of Neural Tube and Congenital Heart Defects  

PubMed Central

Studying empirically derived dietary patterns is useful in understanding dietary practice. We classified women by their dietary patterns using latent class analysis of 66 foods and studied the association of these patterns with neural tube defects (NTDs) and congenital heart defects (CHDs) in the US National Birth Defects Prevention Study (1997–2005). Logistic regression models used data from 1,047 with an NTD, 6,641 with a CHD, and 6,123 controls that were adjusted for maternal characteristics and tested the effect modification of multivitamin supplement use. Four latent dietary patterns were identified: prudent, Western, low-calorie Western, and Mexican. Among participants who did not use supplements, those in the Mexican, Western, and low-calorie Western classes were significantly more likely (odds ratios of 1.6, 1.5, and 1.4, respectively) to have offspring born with NTDs than were those in the prudent class after adjustment of for dietary folic acid intake. In contrast, among supplement users, there was no difference in the incidence of NTDs between classes. Associations between dietary class and CHD subgroups were not modified by supplement use except for tetralogy of Fallot; among supplement users, those in the Western class were twice as likely (95% confidence interval: 1.4, 2.8) as the prudent class to have offspring with tetralogy of Fallot. Women who adhered to a Western diet were 1.2 (95% confidence interval: 1.03, 1.35) times more likely to have an infant with septal heart defect than were women who adhered to a prudent diet. A prudent dietary pattern, even with folate fortification, may decrease the risk of NTDs and some heart defects. PMID:23639938

Sotres-Alvarez, Daniela; Siega-Riz, Anna Maria; Herring, Amy H.; Carmichael, Suzan L.; Feldkamp, Marcia L.; Hobbs, Charlotte A.; Olshan, Andrew F.

2013-01-01

125

Maternal dietary patterns are associated with risk of neural tube and congenital heart defects.  

PubMed

Studying empirically derived dietary patterns is useful in understanding dietary practice. We classified women by their dietary patterns using latent class analysis of 66 foods and studied the association of these patterns with neural tube defects (NTDs) and congenital heart defects (CHDs) in the U.S. National Birth Defects Prevention Study (1997-2005). Logistic regression models used data from 1,047 with an NTD, 6,641 with a CHD, and 6,123 controls that were adjusted for maternal characteristics and tested the effect modification of multivitamin supplement use. Four latent dietary patterns were identified: prudent, Western, low-calorie Western, and Mexican. Among participants who did not use supplements, those in the Mexican, Western, and low-calorie Western classes were significantly more likely (odds ratios of 1.6, 1.5, and 1.4, respectively) to have offspring born with NTDs than were those in the prudent class after adjustment of for dietary folic acid intake. In contrast, among supplement users, there was no difference in the incidence of NTDs between classes. Associations between dietary class and CHD subgroups were not modified by supplement use except for tetralogy of Fallot; among supplement users, those in the Western class were twice as likely (95% confidence interval: 1.4, 2.8) as the prudent class to have offspring with tetralogy of Fallot. Women who adhered to a Western diet were 1.2 (95% confidence interval: 1.03, 1.35) times more likely to have an infant with septal heart defect than were women who adhered to a prudent diet. A prudent dietary pattern, even with folate fortification, may decrease the risk of NTDs and some heart defects. PMID:23639938

Sotres-Alvarez, Daniela; Siega-Riz, Anna Maria; Herring, Amy H; Carmichael, Suzan L; Feldkamp, Marcia L; Hobbs, Charlotte A; Olshan, Andrew F

2013-06-01

126

Absence of linkage between familial neural tube defects and PAX3 gene.  

PubMed Central

Neural tube defects (NTD) are among the most common and disabling birth defects. The aetiology of NTD is unknown and their genetics are complex. The majority of NTD cases are sporadic, isolated, nonsyndromic, and generally considered to be multifactorial in origin. Recently, PAX3 (formerly HuP2, the human homologue of mouse Pax-3), on chromosome 2q35-37, was suggested as a candidate gene for NTD because mutations of Pax-3 cause the mouse mutant Splotch (Sp), an animal model for human NTD. Mutations in PAX3 were also identified in patients with Waardenburg syndrome type 1 (WS1). At least eight patients with both WS1 and NTD have been described suggesting pleiotropy or a contiguous gene syndrome. Seventeen US families and 14 Dutch families with more than one affected person with NTD were collected and 194 people (50 affected) from both data sets were genotyped using the PAX3 polymorphic marker. The data were analysed using affecteds only linkage analysis. The lod scores were -7.30 (US), -3.74 (Dutch), and -11.04 (combined) at theta = 0.0, under the assumption of the autosomal dominant model. For the recessive model, the lod scores were -3.30 (US), -1.46 (Dutch), and -4.76 (combined) at theta = 0.0. Linkage between PAX3 and familial NTD was excluded to 9.9 cM on either side of the gene for the dominant model and to 3.63 cM on either side of the gene for the recessive model in the families studied. No evidence of heterogeneity was detected using the HOMOG program. Our data indicate that PAX3 is not a major gene for NTD. PMID:7783169

Chatkupt, S; Hol, F A; Shugart, Y Y; Geurds, M P; Stenroos, E S; Koenigsberger, M R; Hamel, B C; Johnson, W G; Mariman, E C

1995-01-01

127

Epidemiologic and genetic aspects of spina bifida and other neural tube defects  

PubMed Central

The worldwide incidence of neural tube defects (NTDs) ranges from 1.0 to 10.0 per 1,000 births with almost equal frequencies between two major categories: anencephaly and spina bifida (SB). Epidemiological studies have provided valuable insight for (a) researchers to identify nongenetic and genetic factors contributing to etiology, (b) public health officials to design and implement policies to prevent NTD pregnancies, and (c) individuals to take precautions to reduce the chance of having an NTD-affected pregnancy. Despite extensive research, our knowledge of the genetic etiology of human NTDs is limited. Although more than 200 small animal models with NTDs exist, most of these models do not replicate the human disease phenotype. Over a hundred candidate genes have been examined for risk association to human SB. The candidate genes studied include those important in folic acid metabolism, glucose metabolism, retinoid metabolism, and apoptosis. Many genes that regulate transcription in early embryogenesis and maintain planar cell polarity have also been tested as candidates. Additionally, genes identified through mouse models of NTDs have been explored as candidates. We do not know how many genes in the human genome may confer risk for NTDs in human. Less than 20% of the studied candidate genes have been determined to confer even a minor effect on risk association. Many studies have provided conflicting conclusions due to limitations in study design that potentially affect the power of statistical analysis. Future directions such as genomewide association studies (GWAS) and whole exome or even whole genome sequencing are discussed as possible avenues to identify genes that affect risk for human NTDs. PMID:20419766

Au, Kit Sing; Ashley-Koch, Allison; Northrup, Hope

2011-01-01

128

Epigenetic Profiles in Children with a Neural Tube Defect; A Case-Control Study in Two Populations  

PubMed Central

Folate deficiency is implicated in the causation of neural tube defects (NTDs). The preventive effect of periconceptional folic acid supplement use is partially explained by the treatment of a deranged folate-dependent one carbon metabolism, which provides methyl groups for DNA-methylation as an epigenetic mechanism. Here, we hypothesize that variations in DNA-methylation of genes implicated in the development of NTDs and embryonic growth are part of the underlying mechanism. In 48 children with a neural tube defect and 62 controls from a Dutch case-control study and 34 children with a neural tube defect and 78 controls from a Texan case-control study, we measured the DNA-methylation levels of imprinted candidate genes (IGF2-DMR, H19, KCNQ1OT1) and non-imprinted genes (the LEKR/CCNL gene region associated with birth weight, and MTHFR and VANGL1 associated with NTD). We used the MassARRAY EpiTYPER assay from Sequenom for the assessment of DNA-methylation. Linear mixed model analysis was used to estimate associations between DNA-methylation levels of the genes and a neural tube defect. In the Dutch study group, but not in the Texan study group we found a significant association between the risk of having an NTD and DNA methylation levels of MTHFR (absolute decrease in methylation of ?0.33% in cases, P-value?=?0.001), and LEKR/CCNL (absolute increase in methylation: 1.36% in cases, P-value?=?0.048), and a borderline significant association for VANGL (absolute increase in methylation: 0.17% in cases, P-value?=?0.063). Only the association between MTHFR and NTD-risk remained significant after multiple testing correction. The associations in the Dutch study were not replicated in the Texan study. We conclude that the associations between NTDs and the methylation of the MTHFR gene, and maybe VANGL and LEKKR/CNNL, are in line with previous studies showing polymorphisms in the same genes in association with NTDs and embryonic development, respectively. PMID:24223810

Stolk, Lisette; Bouwland-Both, Marieke I.; van Mill, Nina H.; Verbiest, Michael M. P. J.; Eilers, Paul H. C.; Zhu, Huiping; Suarez, Lucina; Uitterlinden, Andre G.; Steegers-Theunissen, Regine P. M.

2013-01-01

129

Maternal and Infant Gene-Folate Interactions and the Risk of Neural Tube Defects  

PubMed Central

Neural tube defects (NTDs) are common, serious malformations with a complex etiology that suggests involvement of both genetic and environmental factors. The authors evaluated maternal or offspring folate-related gene variants and interactions between the gene variants and maternal intake of folates on the risk of NTDs in their offspring. A case-control study was conducted on mothers and/or their fetuses and infants who were born in California from 1999–2003 with an NTD (cases n = 222, including 24 mother-infant pairs) or without a major malformation (controls n = 454, including 186 mother-infant pairs). Maternal intake of folates was assessed by food frequency questionnaire and genotyping was performed on samples from mothers and infants. For mothers in the lowest folate-intake group, risk of NTDs in offspring was significantly decreased for maternal MTHFR SNPs rs1476413, rs1801131 and rs1801133 (odds ratio (OR) = 0.55, 80% confidence interval (CI): 0.20, 1.48; OR = 0.58, 80% CI: 0.24, 1.43; OR = 0.69, 80% CI: 0.41, 1.17, respectively), and TYMS SNPs rs502396 and rs699517 (OR= 0.91, 80% CI: 0.53, 1.56; OR = 0.70, 80% CI: 0.38, 1.29). A gene-only effect was observed for maternal SHMT1 SNP rs669340 (OR = 0.69, 95% CI: 0.49, 0.96). When there was low maternal folate intake, risk of NTDs was significantly increased for infant MTHFD1 SNPs rs2236224, rs2236225 and rs11627387 (OR = 1.58, 80% CI: 0.99, 2.51; OR = 1.53, 80% CI: 0.95, 2.47; OR = 4.25, 80% CI: 2.33, 7.75, respectively) and SHMT1 SNP rs12939757 (OR = 2.01, 80% CI: 1.20, 3.37), but decreased for TYMS SNP rs2847153 (OR = 0.73, 80% CI: 0.37, 1.45). Although power to detect interaction effects was low for this birth defects association study, the gene-folate interactions observed in this study represent preliminary findings that will be useful for informing future studies on the complex etiology of NTDs. PMID:22903727

Etheredge, Analee J.; Finnell, Richard H.; Carmichael, Suzan L.; Lammer, Edward J.; Zhu, Huiping; Mitchell, Laura E.; Shaw, Gary M.

2012-01-01

130

Neural frame classification 1 Walter J Freeman Origin, structure, and role of background EEG activity  

E-print Network

. The rabbit EEG data used in this study are available to scientists associated with The Brain Resource International Database BrainResource.com> and Brain Dynamics Centre #12;Neural frame classification 2 Walter J Freeman Brain-Dynamics.org>. This report is dedicated to the memory of Linda

Freeman, Walter J.

131

Sept6 Is Required for Ciliogenesis in Kupffer's Vesicle, the Pronephros, and the Neural Tube during Early Embryonic Development  

PubMed Central

Septins are conserved filament-forming GTP-binding proteins that act as cellular scaffolds or diffusion barriers in a number of cellular processes. However, the role of septins in vertebrate development remains relatively obscure. Here, we show that zebrafish septin 6 (sept6) is first expressed in the notochord and then in nearly all of the ciliary organs, including Kupffer's vesicle (KV), the pronephros, eye, olfactory bulb, and neural tube. Knockdown of sept6 in zebrafish embryos results in reduced numbers and length of cilia in KV. Consequently, cilium-related functions, such as the left-right patterning of internal organs and nodal/spaw signaling, are compromised. Knockdown of sept6 also results in aberrant cilium formation in the pronephros and neural tube, leading to cilium-related defects in pronephros development and Sonic hedgehog (Shh) signaling. We further demonstrate that SEPT6 associates with acetylated ?-tubulin in vivo and localizes along the axoneme in the cilia of zebrafish pronephric duct cells as well as cultured ZF4 cells. Our study reveals a novel role of sept6 in ciliogenesis during early embryonic development in zebrafish. PMID:24469395

Zhai, Gang; Gu, Qilin; He, Jiangyan; Lou, Qiyong; Chen, Xiaowen; Jin, Xia

2014-01-01

132

Dynamic Assignment and Maintenance of Positional Identity in the Ventral Neural Tube by the Morphogen Sonic Hedgehog  

PubMed Central

Morphogens are secreted signalling molecules that act in a graded manner to control the pattern of cellular differentiation in developing tissues. An example is Sonic hedgehog (Shh), which acts in several developing vertebrate tissues, including the central nervous system, to provide positional information during embryonic patterning. Here we address how Shh signalling assigns the positional identities of distinct neuronal subtype progenitors throughout the ventral neural tube. Assays of intracellular signal transduction and gene expression indicate that the duration as well as level of signalling is critical for morphogen interpretation. Progenitors of the ventral neuronal subtypes are established sequentially, with progressively more ventral identities requiring correspondingly higher levels and longer periods of Shh signalling. Moreover, cells remain sensitive to changes in Shh signalling for an extended time, reverting to antecedent identities if signalling levels fall below a threshold. Thus, the duration of signalling is important not only for the assignment but also for the refinement and maintenance of positional identity. Together the data suggest a dynamic model for ventral neural tube patterning in which positional information corresponds to the time integral of Shh signalling. This suggests an alternative to conventional models of morphogen action that rely solely on the level of signalling. PMID:20532235

Ribes, Vanessa; Balaskas, Nikolaos; Yang, Lin Lin; Pierani, Alessandra; Kicheva, Anna; Novitch, Bennett G.; Briscoe, James

2010-01-01

133

Mutations in the planar cell polarity genes CELSR1 and SCRIB are associated with the severe neural tube defect craniorachischisis.  

PubMed

Craniorachischisis (CRN) is a severe neural tube defect (NTD) resulting from failure to initiate closure, leaving the hindbrain and spinal neural tube entirely open. Clues to the genetic basis of this condition come from several mouse models, which harbor mutations in core members of the planar cell polarity (PCP) signaling pathway. Previous studies of humans with CRN failed to identify mutations in the core PCP genes, VANGL1 and VANGL2. Here, we analyzed other key PCP genes: CELSR1, PRICKLE1, PTK7, and SCRIB, with the finding of eight potentially causative mutations in both CELSR1 and SCRIB. Functional effects of these unique or rare human variants were evaluated using known protein-protein interactions as well as subcellular protein localization. While protein interactions were not affected, variants from five of the 36 patients exhibited a profound alteration in subcellular protein localization, with diminution or abolition of trafficking to the plasma membrane. Comparable effects were seen in the crash and spin cycle mouse Celsr1 mutants, and the line-90 mouse Scrib mutant. We conclude that missense variants in CELSR1 and SCRIB may represent a cause of CRN in humans, as in mice, with defective PCP protein trafficking to the plasma membrane a likely pathogenic mechanism. PMID:22095531

Robinson, Alexis; Escuin, Sarah; Doudney, Kit; Vekemans, Michel; Stevenson, Roger E; Greene, Nicholas D E; Copp, Andrew J; Stanier, Philip

2012-02-01

134

Molecular genetics and pathogenic mechanisms for the severe ciliopathies: insights into neurodevelopment and pathogenesis of neural tube defects.  

PubMed

Meckel-Gruber syndrome (MKS) is a severe autosomal recessively inherited disorder characterized by developmental defects of the central nervous system that comprise neural tube defects that most commonly present as occipital encephalocele. MKS is considered to be the most common syndromic form of neural tube defect. MKS is genetically heterogeneous with six known disease genes: MKS1, MKS2/TMEM216, MKS3/TMEM67, RPGRIP1L, CEP290, and CC2D2A with the encoded proteins all implicated in the correct function of primary cilia. Primary cilia are microtubule-based organelles that project from the apical surface of most epithelial cell types. Recent progress has implicated the involvement of cilia in the Wnt and Shh signaling pathways and has led to an understanding of their role in normal mammalian neurodevelopment. The aim of this review is to provide an overview of the molecular genetics of the human disorder, and to assess recent insights into the etiology and molecular cell biology of severe ciliopathies from mammalian animal models of MKS. PMID:21110233

Logan, Clare V; Abdel-Hamed, Zakia; Johnson, Colin A

2011-02-01

135

Maternal and Neonatal Serum Zinc Level and Its Relationship with Neural Tube Defects  

PubMed Central

Neural tube defect (NTD) is a multi-factorial disorder in which nutritional, genetic and environmental factors are involved. Among the nutritional factors, low level of serum zinc has been reported from different parts of the world. This hospital-based case-control study was conducted with the objective of finding the relationship between serum zinc level in newborns and their mothers and NTDs in a Bangladeshi population. The study was conducted during August 2006–July 2007 at the Bangabandhu Sheikh Mujib Medical University (BSMMU) in Dhaka. In total, 32 mothers and their newborns with NTDs were included as cases and another 32 mothers with their normal babies were included as controls. Concentration of serum zinc was determined by pyro-coated graphite furnace atomic absorption spectrophotometer (GF-AAS). The mean age of the case and control mothers was 25.28 years and 24.34 years respectively. The mean gestational age of the case newborns was 36.59 weeks and that of the control newborns was 37.75 weeks. The mean serum zinc level of the case and control mothers was 610.2 ?g/L and 883.0 ?g/L respectively (p<0.01). The mean serum zinc level of the case and control newborns was 723 ?g/L and 1,046 ?g/L respectively (p<0.01). In both case and control groups, the serum zinc level of the newborns positively correlated with that of the mothers. The serum zinc levels of the mothers and newborns negatively correlated with NTDs. Mothers with serum zinc level lower than normal were 7.66 [95% confidence interval (CI) 2.5-23.28] times more likely to have NTDs compared to the normal zinc level of mothers. After adjusting for the zinc level of the newborns, parity, and age of the mothers, this risk reduced 1.61 times [confidence interval (CI) 95% 0.24-8.77]. On the other hand, the low serum zinc level of the newborns was 7.22 times more associated with NTDs compared to the newborns with the normal serum zinc level, which was statistically significant (p=0.001). After adjusting for other factors, such as maternal age and parity, newborns with the low serum zinc level was found to be 9.186 times more likely to be associated with NTDs compared to newborns with normal serum zinc level. Based on the findings, it may be concluded that the low serum zinc levels of newborns may be associated with NTDs. To confirm these findings, a further study with a larger sample-size is recommended. Moreover, a follow-up study with zinc supplementation to pregnant women and its impact on NTDs is also recommended. PMID:20824977

Shahidullah, Mohammod; Mannan, Mohammad Abdul; Noor, Mohammad Khaled; Saha, Laxmi; Rahman, Shahana A.

2010-01-01

136

Detection of Foreign Matter in Transfusion Solution Based on Gaussian Background Modeling and an Optimized BP Neural Network.  

PubMed

This paper proposes a new method to detect and identify foreign matter mixed in a plastic bottle filled with transfusion solution. A spin-stop mechanism and mixed illumination style are applied to obtain high contrast images between moving foreign matter and a static transfusion background. The Gaussian mixture model is used to model the complex background of the transfusion image and to extract moving objects. A set of features of moving objects are extracted and selected by the ReliefF algorithm, and optimal feature vectors are fed into the back propagation (BP) neural network to distinguish between foreign matter and bubbles. The mind evolutionary algorithm (MEA) is applied to optimize the connection weights and thresholds of the BP neural network to obtain a higher classification accuracy and faster convergence rate. Experimental results show that the proposed method can effectively detect visible foreign matter in 250-mL transfusion bottles. The misdetection rate and false alarm rate are low, and the detection accuracy and detection speed are satisfactory. PMID:25347581

Zhou, Fuqiang; Su, Zhen; Chai, Xinghua; Chen, Lipeng

2014-01-01

137

CBP/p300 and associated transcriptional co-activators exhibit distinct expression patterns during murine craniofacial and neural tube development.  

PubMed

Mutations in each of the transcriptional co-activator genes - CBP, p300, Cited2, Cart1 and Carm1 - result in neural tube defects in mice. The present study thus furnishes a complete and comparative temporal and spatial expression map of CBP/p300 and associated transcriptional co-activators, Cited2, Cart1 and Carm1 during the period of murine neural tube development (embryonic days 8.5 to 10.5). Each co-activator except Cart1 was expressed in the dorsal neural folds on E8.5. Although CBP and p300 are functionally interchangeable in vitro, their respective expression patterns diverge during embryogenesis before neural fold fusion is complete. CBP gene expression was lost from the neural folds by E8.75 and was thereafter weakly expressed in the maxillary region and limb buds, while p300 exhibited strong expression in the first branchial arch, limb bud and telencephalic regions on E9.5. Cart1 exhibited strong expression in the forebrain mesenchyme from E9.0 through E10.5. Although CBP, p300, Carm1 and Cited2 share temporal expression on E8.5, these co-activators have different spatial expression in mesenchyme and/or the neuroepithelium. Nevertheless, co-localization to the dorsal neural folds on E8.5 suggests a functional role in elevation and/or fusion of the neural folds. Target genes, and pathways that promote cranial neural tube fusion that are activated by CBP/p300/Carm1/Cited2/Cart1-containing transcriptional complexes await elucidation. PMID:19598128

Bhattacherjee, Vasker; Horn, Kristin H; Singh, Saurabh; Webb, Cynthia L; Pisano, M Michele; Greene, Robert M

2009-01-01

138

CBP/p300 and associated transcriptional co-activators exhibit distinct expression patterns during murine craniofacial and neural tube development  

PubMed Central

Mutations in each of the transcriptional co-activator genes - CBP, p300, Cited2, Cart1 and Carm1 - result in neural tube defects in mice. The present study thus furnishes a complete and comparative temporal and spatial expression map of CBP/p300 and associated transcriptional co-activators, Cited2, Cart1 and Carm1 during the period of murine neural tube development (embryonic days 8.5 to 10.5). Each co-activator except Cart1 was expressed in the dorsal neural folds on E8.5. Although CBP and p300 are functionally interchangeable in vitro, their respective expression patterns diverge during embryogenesis before neural fold fusion is complete. CBP gene expression was lost from the neural folds by E8.75 and was thereafter weakly expressed in the maxillary region and limb buds, while p300 exhibited strong expression in the first branchial arch, limb bud and telencephalic regions on E9.5. Cart1 exhibited strong expression in the forebrain mesenchyme from E9.0 through E10.5. Although CBP, p300, Carm1 and Cited2 share temporal expression on E8.5, these co-activators have different spatial expression in mesenchyme and/or the neuroepithelium. Nevertheless, co-localization to the dorsal neural folds on E8.5 suggests a functional role in elevation and/or fusion of the neural folds. Target genes, and pathways that promote cranial neural tube fusion that are activated by CBP/p300/Carm1/Cited2/Cart1-containing transcriptional complexes await elucidation. PMID:19598128

BHATTACHERJEE, VASKER; HORN, KRISTIN H.; SINGH, SAURABH; WEBB, CYNTHIA L.; PISANO, M. MICHELE; GREENE, ROBERT M.

2009-01-01

139

21 CFR 101.79 - Health claims: Folate and neural tube defects.  

Code of Federal Regulations, 2013 CFR

...mcg of folic acid, the Food and Drug Administration...a personal or family history of a pregnancy affected...shall not be made on foods that contain more than...amount of folate in the food. This information...those with a personal history of a neural...

2013-04-01

140

21 CFR 101.79 - Health claims: Folate and neural tube defects.  

Code of Federal Regulations, 2012 CFR

...mcg of folic acid, the Food and Drug Administration...a personal or family history of a pregnancy affected...shall not be made on foods that contain more than...amount of folate in the food. This information...those with a personal history of a neural...

2012-04-01

141

21 CFR 101.79 - Health claims: Folate and neural tube defects.  

Code of Federal Regulations, 2011 CFR

...mcg of folic acid, the Food and Drug Administration...a personal or family history of a pregnancy affected...shall not be made on foods that contain more than...amount of folate in the food. This information...those with a personal history of a neural...

2011-04-01

142

Validity of death and stillbirth certifi cates and hospital discharge summaries for the identifi cation of neural tube defects in Quebec City  

Microsoft Academic Search

The objectives of this study were 1) to assess the validity of different databases which identify neural tube defect (NTD) cases in the population, and 2) to examine the tempo- ral trends in NTD rates and the impact of prenatal diagnoses among pregnancies referred to a tertiary care hospital in Quebec City, Canada, from 1993 to 2002. Infant death and

Fassiatou Tairou; Philippe De Wals

2006-01-01

143

Investigation, using rat embryo culture, of the role of methionine supply in folic acid-mediated prevention of neural tube defects  

Microsoft Academic Search

Peri-conceptional folic acid supplementation has become a well established way to prevent neural tube defects (NTDs) and such supplementation reduces the prevalence of these defects by approximately 70%. However, the mechanism of the preventive effect of folic acid is not clear. This overview focuses on the biochemical basis of folic acid-preventable NTDs and on the results obtained with whole embryo

L. A. G. J. M. Vanaerts

1995-01-01

144

Differences in axial curvature correlate with species-specific rate of neural tube closure in embryos of chick, rabbit, mouse, rat and human.  

PubMed

Studies on the mouse strain curly tail, a mutant for neural tube defects, have indicated that axial curvature is an important factor in neural tube closure. Previously reported results from experimental interventions in both mouse and chick embryos indicated that curvature along the craniocaudal axis and closure of the posterior neuropore (PNP) are inversely related, a correlation that is also proposed for the rabbit embryo. It was hypothesized that this relationship is a sign of a more general mechanism. Therefore, in the present report the number of species in which axial curvature is described along the craniocaudal axis was extended to include the rat and human. Next, the closure rate of the neural tube as well as the curvature of the PNP region was determined morphometrically for embryos of the following species: chick, rabbit, mouse, rat and human. Although the relationship between neural tube closure and axial curvature appeared specific for each species in the comparative analysis, a general association of increased rate of closure with a decreased curvature emerged. It is concluded that axial curvature is an important factor in neurulation. PMID:9764973

Peeters, M C; Hekking, J W; Shiota, K; Drukker, J; Van Straaten, H W

1998-09-01

145

Insights into prevention of human neural tube defects by folic acid arising from consideration of mouse mutants.  

PubMed

Almost 30 years after the initial study by Richard W. Smithells and coworkers, it is still unknown how maternal periconceptional folic acid supplementation prevents human neural tube defects (NTDs). In this article, questions about human NTD prevention are considered in relation to three groups of mouse models: NTD mutants that respond to folate, NTD mutants and strains that do not respond to folate, and mutants involving folate-pathway genes. Of the 200 mouse NTD mutants, only a few have been tested with folate; half respond and half do not. Among responsive mutants, folic acid supplementation reduces exencephaly and/or spina bifida aperta frequency in the Sp(2H), Sp, Cd, Cited2, Cart1, and Gcn5 mutants. Prevention ranges from 35 to 85%. The responsive Sp(2H) (Pax3) mutant has abnormal folate metabolism, but the responsive Cited2 mutant does not. Neither folic nor folinic acid reduces NTD frequency in Axd, Grhl3, Fkbp8, Map3k4, or Nog mutants or in the curly tail or SELH/Bc strains. Spina bifida frequency is reduced in Axd by methionine and in curly tail by inositol. Exencephaly frequency is reduced in SELH/Bc by an alternative commercial ration. Mutations in folate-pathway genes do not cause NTDs, except for 30% exencephaly in folate-treated Folr1. Among folate-pathway mutants, neural tube closure is normal in Cbs, Folr2, Mthfd1, Mthfd2, Mthfr, and Shmt1 mutants. Embryos die by midgestation in Folr1, Mtr, Mtrr, and RFC1 mutants. The mouse models point to genetic heterogeneity in the ability to respond to folic acid and also to heterogeneity in genetic cause of NTDs that can be prevented by folic acid. PMID:19117321

Harris, Muriel J

2009-04-01

146

Reduced glucose consumption in the curly tail mouse does not initiate the pathogenesis leading to spinal neural tube defects.  

PubMed

At embryonic stages of neural tube closure, the mouse embryo exhibits a high rate of glycolysis with glucose as the main energy source. In the curly tail mouse, often used as model system for study of human neural tube defects, a delay in closure of the posterior neuropore (PNP) is proposed to be indirectly caused by a proliferation defect in the caudal region. Because glucose is important for proliferation, we tested glucose uptake in curly tail and control embryos, and in a BALB/c-curly tail recombinant strain. The structure and expression of Glut-1, a glucose transporter molecule that is abundantly present during those embryonic stages and that has been mapped in the region of the major curly tail gene, were also studied; however, no strain differences could be demonstrated. Glucose uptake was determined by measuring glucose depletion from the medium in long-term embryo cultures that encompassed the stages of PNP closure and by measuring accumulation of 3H-deoxyglucose in short-term cultures at the stages of early and final PNP closure. Both approaches indicated a reduced glucose uptake by curly tail and recombinant embryos. Surprisingly, the uptake per cell appeared normal, accompanied by a significantly lower DNA content of the mutant embryos. Therefore, it is unlikely that reduced cell proliferation is caused by a reduction in glucose supply during the pathogenesis of the defects in curly tail embryos. The reduced DNA content as well as the reduced glucose uptake per embryo are likely downstream effects of the aberrant proliferation pattern. PMID:9772156

Peeters, M C; Geelen, J L; Hekking, J W; Chavannes, N; Geraedts, J P; van Straaten, H W

1998-10-01

147

Relationship between altered axial curvature and neural tube closure in normal and mutant (curly tail) mouse embryos.  

PubMed

Neural tube defects, including spina bifida, develop in the curly tail mutant mouse as a result of delayed closure of the posterior neuropore at 10.5 days of gestation. Affected embryos are characterized by increased ventral curvature of the caudal region. To determine whether closure of the neuropore could be affected by this angle of curvature, we experimentally enhanced the curvature of non-mutant embryos. The amnion was opened in 9.5 day embryos; after 20 h of culture, a proportion of the embryos exhibited a tightly wrapped amnion with enhanced curvature of the caudal region compared with the control embryos in which the opened amnion remained inflated. Enhanced curvature correlated with a higher frequency of embryos with an open posterior neuropore, irrespective of developmental stage within the range, 27-32 somites. Thus, within this somite range, caudal curvature is a more accurate determinant for normal spinal neurulation than the exact somite stage. Enhanced ventral curvature of the curly tail embryo correlates with an abnormal growth difference between the neuroepithelium and ventral structures (the notochord and hindgut). We experimentally corrected this imbalance by culturing under conditions of mild hyperthermia and subsequently determined whether the angle of curvature would also be corrected. The mean angle of curvature and length of the posterior neuropore were both reduced in embryos cultured at 40.5 degrees C by comparison with control embryos cultured at 38 degrees C. We conclude that the sequence of morphogenetic events leading to spinal neural tube defects in curly tail embryos involves an imbalance of growth rates, which leads to enhanced ventral curvature that, in turn, leads to delayed closure of the posterior neuropore. PMID:8742053

Peeters, M C; Shum, A S; Hekking, J W; Copp, A J; van Straaten, H W

1996-02-01

148

Raltitrexed's effect on the development of neural tube defects in mice is associated with DNA damage, apoptosis, and proliferation.  

PubMed

The causal metabolic pathway and the underlying mechanism between folate deficiency and neural tube defects (NTDs) remain obscure. Thymidylate (dTMP) is catalyzed by thymidylate synthase (TS) using the folate-derived one-carbon unit as the sole methyl donor. This study aims to examine the role of dTMP biosynthesis in the development of neural tube in mice by inhibition of TS via a specific inhibitor, raltitrexed (RTX). Pregnant mice were intraperitoneally injected with various doses of RTX on gestational day 7.5, and embryos were examined for the presence of NTDs on gestational day 11.5. TS activity and changes of dUMP and dTMP levels were measured following RTX treatment at the optimal dose. DNA damage was determined by detection of phosphorylated replication protein A2 (RPA2) and ?-H2AX in embryos with NTDs induced by RTX. Besides, apoptosis and proliferation were also analyzed in RTX-treated embryos with NTDs. We found that NTDs were highly occurred by the treatment of RTX at the optimal dose of 11.5 mg/kg b/w. RTX treatment significantly inhibited TS activity. Meanwhile, dTMP was decreased associated with the accumulation of dUMP in RTX-treated embryos. Phosphorylated RPA2 and ?-H2AX were significantly increased in RTX-treated embryos with NTDs compared to control. More apoptosis and decreased proliferation were also found in embryos with NTDs induced by RTX. These results indicate that impairment of dTMP biosynthesis caused by RTX led to the development of NTDs in mice. DNA damage and imbalance between apoptosis and proliferation may be potential mechanisms. PMID:25245820

Dong, Yanting; Wang, Xiuwei; Zhang, Jianlin; Guan, Zhen; Xu, Lin; Wang, Jianhua; Zhang, Ting; Niu, Bo

2015-01-01

149

MR-Based Morphometry of the Posterior Fossa in Fetuses with Neural Tube Defects of the Spine  

PubMed Central

Objectives In cases of “spina bifida,” a detailed prenatal imaging assessment of the exact morphology of neural tube defects (NTD) is often limited. Due to the diverse clinical prognosis and prenatal treatment options, imaging parameters that support the prenatal differentiation between open and closed neural tube defects (ONTDs and CNTDs) are required. This fetal MR study aims to evaluate the clivus-supraocciput angle (CSA) and the maximum transverse diameter of the posterior fossa (TDPF) as morphometric parameters to aid in the reliable diagnosis of either ONTDs or CNTDs. Methods The TDPF and the CSA of 238 fetuses (20–37 GW, mean: 28.36 GW) with a normal central nervous system, 44 with ONTDS, and 13 with CNTDs (18–37 GW, mean: 24.3 GW) were retrospectively measured using T2-weighted 1.5 Tesla MR -sequences. Results Normal fetuses showed a significant increase in the TDPF (r?=?.956; p<.001) and CSA (r?=?.714; p<.001) with gestational age. In ONTDs the CSA was significantly smaller (p<.001) than in normal controls and CNTDs, whereas in CNTDs the CSA was not significantly smaller than in controls (p?=?.160). In both ONTDs and in CNTDs the TDPF was significantly different from controls (p<.001). Conclusions The skull base morphology in fetuses with ONTDs differs significantly from cases with CNTDs and normal controls. This is the first study to show that the CSA changes during gestation and that it is a reliable imaging biomarker to distinguish between ONTDs and CNTDs, independent of the morphology of the spinal defect. PMID:25393279

Woitek, Ramona; Dvorak, Anton; Weber, Michael; Seidl, Rainer; Bettelheim, Dieter; Schöpf, Veronika; Amann, Gabriele; Brugger, Peter C.; Furtner, Julia; Asenbaum, Ulrika; Prayer, Daniela; Kasprian, Gregor

2014-01-01

150

Foreground-background segmentation of optical character recognition labels by a single-layer recurrent neural network  

NASA Astrophysics Data System (ADS)

Optical character recognition (OCR) algorithms typically start from a binary label image. The need for a binary image is complicated by the fact that most imaging devices usually produce multiply valued data: a gray scale image. The problem then becomes how to extract the meaningful character data from the gray scale image. Image artifacts such as dirt, variations in background intensity, and imaging noise complicate the character extraction. When inspecting packages moving on a conveyor belt, we have control over the optical parameters of the system. Via autofocus and controlled lighting, parameters such as the optical path length, field of view, and illumination intensity may be adjusted. However no control can be placed on labels. The label reading system is totally subject to the package sender's whimsy. We describe the development of a recurrent neural network to segment gray scale label images into binary label images. To determine a pixel label, the neural network takes into account three sources of information: pixel intensities, correlations between neighboring labels, and edge gradients. These three sources of information are succinctly combined via the network's energy function. By changing its label state to minimize the energy function, the network satisfies constraints imposed by the input image and the current label values. The network has no knowledge of shape. Information on what comprises a desirable shape is probably unwarranted at the earliest stage of image processing. Although significant image filtering could be performed by a network that knows what characters should look like, such knowledge is unavoidably font specific. Further there is the problem of teaching the network about shapes. The neural network does not need to be taught. Learning is typically extremely time consuming. To be mappable to analog hardware, it is desirable that the neural equations be deterministic. Two deterministic networks are developed and compared. The first operates at the zero temperature limit, the original Hopfield network. The second employs the mean field annealing algorithm. It is shown that with only a moderate increase in computational requirements, the mean field approach produces far superior results.

Holeva, Lee F.

1996-04-01

151

Detailed expression analysis of regulatory genes in the early developing human neural tube.  

PubMed

Studies in model organisms constitute the basis of our understanding of the principal molecular mechanisms of cell fate determination in the developing central nervous system. Considering the emergent applications in stem cell-based regenerative medicine, it is important to demonstrate conservation of subtype specific gene expression programs in human as compared to model vertebrates. We have examined the expression patterns of key regulatory genes in neural progenitor cells and their neuronal and glial descendants in the developing human spinal cord, hindbrain, and midbrain, and compared these with developing mouse and chicken embryos. As anticipated, gene expression patterns are highly conserved between these vertebrate species, but there are also features that appear unique to human development. In particular, we find that neither tyrosine hydroxylase nor Nurr1 are specific markers for mesencephalic dopamine neurons, as these genes also are expressed in other neuronal subtypes in the human ventral midbrain and in human embryonic stem cell cultures directed to differentiate towards a ventral mesencephalic identity. Moreover, somatic motor neurons in the ventral spinal cord appear to be produced by two molecularly distinct ventral progenitor populations in the human, raising the possibility that the acquisition of unique ventral progenitor identities may have contributed to the emergence of neural subtypes in higher vertebrates. PMID:24007338

Marklund, Ulrika; Alekseenko, Zhanna; Andersson, Elisabet; Falci, Scott; Westgren, Magnus; Perlmann, Thomas; Graham, Anthony; Sundström, Erik; Ericson, Johan

2014-01-01

152

Disturbed apoptosis and cell proliferation in developing neuroepithelium of lumbo-sacral neural tubes in retinoic acid-induced spina bifida aperta in rat.  

PubMed

Spina bifida is a complex congenital malformation resulting from failure of fusion in the spinal neural tube during embryogenesis. However, the cellular mechanism underlying spina bifida is not fully understood. Here, we investigated cell apoptosis in whole embryos and proliferation of neural progenitor cells in the spinal neural tube during neurulation in all-trans retinoic acid (atRA)-induced spina bifida in fetal rats. Cell apoptosis was assessed by TUNEL assay on whole-mount and serially sectioned samples of rat embryos with spina bifida. Cell proliferation of lumbo-sacral neural progenitor cells was assessed by staining for the mitotic marker Ki67 and pH3. We found an excess of apoptosis in the neuroepithelium of embryos with spina bifida, which became more marked as embryos progress from E11 to E13. Conversely, there was a reduction in cell proliferation in spina bifida embryos, with a progressively greater difference from controls with stage from E11 to 13. Thus, atRA-induced spina bifida in rat shows perturbed apoptosis and proliferation of neural progenitors in the lumbo-sacral spinal cord during embryonic development, which might contribute to the pathogenesis of spina bifida. PMID:22504176

Wei, Xiaowei; Li, Hui; Miao, Jianing; Zhou, Fenghua; Liu, Bo; Wu, Di; Li, Shujing; Wang, Lili; Fan, Yang; Wang, Weilin; Yuan, Zhengwei

2012-08-01

153

Prevention of neural tube defects by and toxicity of L-homocysteine in cultured postimplantation rat embryos.  

PubMed

Mild hyperhomocysteinemia is frequently observed in mothers who gave birth to a child with a neural tube defect (NTD). In a previous study we showed L-homocysteine was embryotoxic to gestational day 10 (GD10) rat embryos in culture, however, no NTDs were observed. We therefore investigated the effect of L-homocysteine on the development of neural plate stage (GD9.5) rat embryos. Other objectives of this study were investigation into whether the embryotoxicity of L-homocysteine could be attenuated by compounds related to its metabolism and clarification of the mechanism of L-homocysteine embryotoxicity. In GD9.5 rat embryos L-homocysteine was not toxic at 1- and 2-mM concentrations. Rather at these concentrations it promoted development of the rat embryos in serum that without supplementation caused NTDs in the embryos. L-Methionine had the same preventive effect at even lower concentrations, but folinic acid (1 mM) did not improve embryonic development. N5-Methyltetrahydrofolate (5-CH3-THF) (100 microM), L-serine (6 mM), and L-methionine (6 and 12 mM) attenuated the embryotoxicity of L-homocysteine (6 mM) in GD10 rat embryos. Vitamin B12 (10 microM) completely abolished the embryotoxicity of L-homocysteine, which was shown to be mediated by catalysis of the spontaneous oxidation of L-homocysteine to the less toxic L-homocystine. In GD11 rat embryos, both L- and D-homocysteine were readily taken up when added to the culture (3 mM) and increased embryonic S-adenosylhomocysteine (SAH) levels 14- and 3-fold, respectively. This difference was shown to be caused by the stereospecific preference of SAH hydrolase. We propose the basis for L-homocysteine embryotoxicity is an inhibition of transmethylation reactions by increased embryonic SAH levels. PMID:7716742

Vanaerts, L A; Blom, H J; Deabreu, R A; Trijbels, F J; Eskes, T K; Copius Peereboom-Stegeman, J H; Noordhoek, J

1994-11-01

154

Analysis of the MTHFR 1298A?C and 677C?T polymorphisms as risk factors for neural tube defects  

Microsoft Academic Search

  \\u000a The thermolabile variant (677TT) of methylenetetrahydrofolate reductase (MTHFR) is a known risk factor for neural tube defects\\u000a (NTDs). The relationship between a second MTHFR polymorphism (1298A?C) and NTD risk has been inconsistent between studies.\\u000a We genotyped 276 complete NTD triads (mother, father and child affected with an NTD) and 256 controls for MTHFR 1298A?C. Our\\u000a findings do not support

Anne Parle-McDermott; James L. Mills; Peadar N. Kirke; Valerie B. O'Leary; Deborah A. Swanson; Faith Pangilinan; Mary Conley; Anne M. Molloy; Christopher Cox; John M. Scott; Lawrence C. Brody

2003-01-01

155

Confirmation of the R653Q polymorphism of the trifunctional C1-synthase enzyme as a maternal risk for neural tube defects in the Irish population  

Microsoft Academic Search

The risk of neural tube defects (NTDs) is known to have a significant genetic component that could act through either the NTD patient and\\/or maternal genotype. The success of folic acid supplementation in NTD prevention has focused attention on polymorphisms within folate-related genes. We previously identified the 1958G>A (R653Q) polymorphism of the trifunctional enzyme MTHFD1 (methylenetetrahydrofolate-dehydrogenase, methenyltetrahydrofolate-cyclohydrolase, formyltetrahydrofolate synthetase; often

Anne Parle-McDermott; Peadar N Kirke; James L Mills; Anne M Molloy; Christopher Cox; Valerie B O'Leary; Faith Pangilinan; Mary Conley; Laura Cleary; Lawrence C Brody; John M Scott

2006-01-01

156

Periconceptional folic acid and multivitamin supplementation for the prevention of neural tube defects and other congenital abnormalities.  

PubMed

The pioneering studies of Smithells et al. showed the reduction of recurrent neural-tube defects (NTD) after periconceptional folic acid-containing multivitamin supplementation. The Hungarian Periconceptional Service was established in 1984, and this primary health care system offered a chance to organize a randomized controlled trial to check whether the supplementation of a multivitamin containing 0.8 mg of folic acid during the periconceptional period is appropriate for the reduction of a first occurrence of NTD in the family. This found a reduction of approximately 90% of primary NTD. An unexpected finding was a significant reduction in the rate of congenital abnormalities overall: 20.6 per 1000 in the 'multivitamin' group, and 40.6 per 1000 in the 'trace-element-like' placebo group (RR = 0.53, 95% CI: 0.35-0.70). When the 6 cases of NTD were excluded, this difference in the rates of major congenital abnormalities between the two study-groups remained very highly significant (p < 0.0001). Cardiovascular malformations and urinary tract defects were particularly affected. These findings were confirmed in the Hungarian cohort-controlled trial and by observational studies in other countries. Two questions remain to be answered. Is folic acid better alone or with multivitamins? What is the optimal dose of folic acid? Overall, the Hungarian experiences of periconceptional care have shown not only primary prevention of several severe congenital abnormalities but also a good cost-benefit balance. PMID:19161162

Czeizel, Andrew E

2009-04-01

157

Differences in the Neural Mechanisms of Selective Attention in Children from Different Socioeconomic Backgrounds: An Event-Related Brain Potential Study  

ERIC Educational Resources Information Center

Previous research indicates that children from lower socioeconomic backgrounds show deficits in aspects of attention, including a reduced ability to filter irrelevant information and to suppress prepotent responses. However, less is known about the neural mechanisms of group differences in attention, which could reveal the stages of processing at…

Stevens, Courtney; Lauinger, Brittni; Neville, Helen

2009-01-01

158

Knowledge and periconceptional use of folic acid for the prevention of neural tube defects in ethnic communities in the United Kingdom: Systematic review and meta-analysis  

PubMed Central

BACKGROUND: It is widely accepted that periconceptional supplementation with folic acid can prevent a significant proportion of neural tube defects (NTDs). The present study evaluated how folic acid knowledge and periconceptional use for NTD prevention varies by ethnicity in the United Kingdom (U.K.). METHODS: A literature search was conducted to identify studies that included assessment of folic acid knowledge or use in U.K. women of different ethnicities. Only research and referenced sources published after 1991, the year of the landmark Medical Research Council’s Vitamin Study, were included. A meta-analysis was performed of studies that assessed preconceptional folic acid use in Caucasians and non-Caucasians. RESULTS: Five studies met the inclusion criteria for assessment of knowledge and/or use of folic acid supplements in U.K. women including non-Caucasians. The available evidence indicates that South Asians specifically have less knowledge and lower periconceptional use of folic acid than Caucasians; one study found that West Indian and African women also had lower folic acid uptake. A synthesis of results from three of the studies, in a meta-analysis, shows that Caucasians are almost three times more likely to take folic acid before conception than non-Caucasians. CONCLUSION: From the limited evidence available, U.K. women of non-Caucasian ethnicity appear to have less knowledge and a lower uptake of folic acid supplementation than Caucasians during the periconceptional period. Implementing targeted, innovative education campaigns together with a mandatory fortification policy, including the fortification of ethnic minority foods, will be required for maximum prevention of folic acid–preventable NTDs across different ethnic groups. Birth Defects Research (Part A) 97:444–451, 2013. © 2013 Wiley Periodicals, Inc. PMID:23873812

Peake, Jordana N; Copp, Andrew J; Shawe, Jill

2013-01-01

159

Maternal occupational exposure to organic solvents during early pregnancy and risks of neural tube defects and orofacial clefts  

PubMed Central

Objectives Though toxicological experiments demonstrate the teratogenicity of organic solvents in animal models, epidemiologic studies have reported inconsistent results. Using data from the population-based National Birth Defects Prevention Study, we examined the relation between maternal occupational exposure to aromatic solvents, chlorinated solvents and Stoddard solvent during early pregnancy and neural tube defects (NTDs) and orofacial clefts (OFCs). Methods Cases of NTDs (anencephaly, spina bifida and encephalocele) and OFCs (cleft lip ± cleft palate and cleft palate alone) delivered between 1997 and 2002 were identified by birth defect surveillance registries in 8 states; non-malformed control infants were selected using birth certificates or hospital records. Maternal solvent exposure was estimated by industrial hygienist review of self-reported occupational histories in combination with a literature-derived exposure database. Odds ratios (OR) and 95% confidence intervals (CI) for the association between solvent class and each birth defect group and component phenotype were estimated using multivariable logistic regression, adjusting for maternal age, race/ethnicity, education, pre-pregnancy body mass index, folic acid supplement use and smoking. Results The prevalence of exposure to any solvent among mothers of NTD cases (n=511), OFC cases (n=1163) and controls (n=2977) was 13.1%, 9.6% and 8.2%, respectively. Exposure to chlorinated solvents was associated with increased odds of NTDs (OR=1.96; CI=1.34, 2.87), especially spina bifida (OR=2.26; CI=1.44, 3.53). No solvent class was strongly associated with OFCs in these data. Conclusions Our findings suggest that maternal occupational exposure to chlorinated solvents during early pregnancy is positively associated with the prevalence of NTDs in offspring. PMID:22447643

Desrosiers, Tania A.; Lawson, Christina C.; Meyer, Robert E.; Richardson, David B.; Daniels, Julie L.; Waters, Martha A.; van Wijngaarden, Edwin; Langlois, Peter H.; Romitti, Paul A.; Correa, Adolfo; Olshan, Andrew F.

2013-01-01

160

Dieting to lose weight and occurrence of neural tube defects in offspring of Mexican-American women.  

PubMed

Lowered maternal weight gain and reduction in early pregnancy have been associated with risk of neural tube defects (NTDs) in offspring. We examined the association of self-reported maternal dieting behaviors on the occurrence of NTDs. We conducted a population based case-control study among Mexican-American women who were residents of the 14 Texas counties bordering Mexico. Case women had an NTD-affected pregnancy identified at birth or prenatally and had deliveries during the years 1995-2000. Control women were those who delivered live born infants without an apparent congenital malformation, randomly selected and frequency-matched to cases by year and facility. One hundred eighty-four case women and 225 control women were asked in person about the use of nutritional supplements, dieting to lose weight, and type of weight reduction supplements used during the 3 months before conception. Women who reported being on a diet to lose weight during the 3 months before conception had an NTD odds ratio (OR) of 1.9 (95% confidence interval (CI) = 1.1, 3.3) compared with those not reporting being on a diet. Neither consuming vitamin drinks (OR = 1.2) nor using diet pills (OR = 1.6) during the 3 months before conception had ORs that were different from the null, when compared to women not reporting those behaviors. The risk effect for dieting did not differ markedly among normal or underweight (OR = 2.0, 95% CI = 0.7, 5.6), overweight (OR = 1.9, 95% CI = 0.7, 5.0), or obese women (OR = 1.5, 95% CI = 0.6, 4.0). No effect was seen among dieting women who were consuming at least 1.0 mg/day of folate (OR = 1.1, CI = 0.3, 4.5). Maternal dieting prior to conception may increase the risk of NTDs in offspring. PMID:21512779

Suarez, Lucina; Felkner, Marilyn; Brender, Jean D; Canfield, Mark A

2012-05-01

161

Whole genomewide linkage screen for neural tube defects reveals regions of interest on chromosomes 7 and 10  

PubMed Central

Neural tube defects (NTDs) are the second most common birth defects (1 in 1000 live births) in the world. Periconceptional maternal folate supplementation reduces NTD risk by 50–70%; however, studies of folate related and other developmental genes in humans have failed to definitively identify a major causal gene for NTD. The aetiology of NTDs remains unknown and both genetic and environmental factors are implicated. We present findings from a microsatellite based screen of 44 multiplex pedigrees ascertained through the NTD Collaborative Group. For the linkage analysis, we defined our phenotype narrowly by considering individuals with a lumbosacral level myelomeningocele as affected, then we expanded the phenotype to include all types of NTDs. Two point parametric analyses were performed using VITESSE and HOMOG. Multipoint parametric and nonparametric analyses were performed using ALLEGRO. Initial results identified chromosomes 7 and 10, both with maximum parametric multipoint lod scores (Mlod) >2.0. Chromosome 7 produced the highest score in the 24 cM interval between D7S3056 and D7S3051 (parametric Mlod 2.45; nonparametric Mlod 1.89). Further investigation demonstrated that results on chromosome 7 were being primarily driven by a single large pedigree (parametric Mlod 2.40). When this family was removed from analysis, chromosome 10 was the most interesting region, with a peak Mlod of 2.25 at D10S1731. Based on mouse human synteny, two candidate genes (Meox2, Twist1) were identified on chromosome 7. A review of public databases revealed three biologically plausible candidates (FGFR2, GFRA1, Pax2) on chromosome 10. The results from this screen provide valuable positional data for prioritisation of candidate gene assessment in future studies of NTDs. PMID:15831595

Rampersaud, E; Bassuk, A; Enterline, D; George, T; Siegel, D; Melvin, E; Aben, J; Allen, J; Aylsworth, A; Brei, T; Bodurtha, J; Buran, C; Floyd, L; Hammock, P; Iskandar, B; Ito, J; Kessler, J; Lasarsky, N; Mack, P; Mackey, J; McLone, D; Meeropol, E; Mehltretter, L; Mitchell, L; Oakes, W; Nye, J; Powell, C; Sawin, K; Stevenson, R; Walker, M; West, S; Worley, G; Gilbert, J; Speer, M

2005-01-01

162

Gene-gene interaction in folate-related genes and risk of neural tube defects in a UK population  

PubMed Central

Objective: To investigate the contribution of polymorphic variation in genes involved in the folate-dependent homocysteine pathway in the aetiology of neural tube defects (NTD). Design: Case-control association study. Subjects: A total of 530 individuals from families affected by NTD, 645 maternal controls, and 602 healthy newborn controls from the northern UK. Main outcome measures: Seven polymorphisms in six genes coding for proteins in the folate-dependent homocysteine pathway (MTHFR 677C?T, MTHFR 1298A?C, MTRR 66A?G, SHMT 1420C?T, CßS 844ins68, GCPII 1561C?T, RFC-1 80G?A). The impact of each polymorphism and the effect of gene–gene interactions (epistasis) upon risk of NTD were assessed using logistic regression analysis. Results: The MTHFR 677C?T polymorphism was shown to represent a risk factor in NTD cases (CC v CT+TT odds ratio (OR) 2.03 [95% confidence interval (CI) 1.09, 3.79] p = 0.025) and the MTRR 66A?G polymorphism was shown to exert a protective effect in NTD cases (AA v AG+GG OR 0.31 [95% CI 0.10, 0.94] p = 0.04). When statistical tests for interaction were conducted, three genotype combinations in cases (MTRR/GCPII; MTHFR 677/CßS; MTHFR 677/MTRR) and one combination in case mothers (CßS/RFC-1) were shown to elevate NTD risk. Maternal–fetal interaction was also detected when offspring carried the MTHFR 677C?T variant and mothers carried the MTRR 66A?G variant, resulting in a significantly elevated risk of NTD. Conclusion: Both independent genetic effects and gene–gene interaction were observed in relation to NTD risk. Multi-locus rather than single locus analysis might be preferable to gain an accurate assessment of genetic susceptibility to NTD. PMID:15060097

Relton, C; Wilding, C; Pearce, M; Laffling, A; Jonas, P; Lynch, S; Tawn, E; Burn, J

2004-01-01

163

Diabetes and Obesity-Related Genes and the Risk of Neural Tube Defects in the National Birth Defects Prevention Study  

PubMed Central

Few studies have evaluated genetic susceptibility related to diabetes and obesity as a risk factor for neural tube defects (NTDs). The authors investigated 23 single nucleotide polymorphisms among 9 genes (ADRB3, ENPP1, FTO, LEP, PPARG, PPARGC1A, SLC2A2, TCF7L2, and UCP2) associated with type 2 diabetes or obesity. Samples were obtained from 737 NTD case-parent triads included in the National Birth Defects Prevention Study during 1999–2007. Log-linear models were used to evaluate maternal and offspring genetic effects. After application of the false discovery rate, there were 5 significant maternal genetic effects. The less common alleles at the 4 FTO single nucleotide polymorphisms showed a reduction of NTD risk (for rs1421085, relative risk (RR) = 0.73 (95% confidence interval (CI): 0.62, 0.87); for rs8050136, RR = 0.79 (95% CI: 0.67, 0.93); for rs9939609, RR = 0.79 (95% CI: 0.67, 0.94); and for rs17187449, RR = 0.80 (95% CI: 0.68, 0.95)). Additionally, maternal LEP rs2071045 (RR = 1.31, 95% CI: 1.08, 1.60) and offspring UCP2 rs660339 (RR = 1.32, 95% CI: 1.06, 1.64) were associated with NTD risk. Furthermore, the maternal genotype for TCF7L2 rs3814573 suggested an increased NTD risk among obese women. These findings indicate that maternal genetic variants associated with glucose homeostasis may modify the risk of having an NTD-affected pregnancy. PMID:23132673

Lupo, Philip J.; Canfield, Mark A.; Chapa, Claudia; Lu, Wei; Agopian, A. J.; Mitchell, Laura E.; Shaw, Gary M.; Waller, D. Kim; Olshan, Andrew F.; Finnell, Richard H.; Zhu, Huiping

2012-01-01

164

Association between MTHFD1 G1958A Polymorphism and Neural Tube Defects Susceptibility: A Meta-Analysis  

PubMed Central

Objectives The methylenetetrahydrofolate dehydrogenase (MTHFD1) gene, as one of the key genes involved in the folate pathway, has been reported to play a critical role in the pathogenesis of neural tube defects (NTDs). However, the results of published studies are contradictory and inconclusive. Thus, this meta-analysis aimed to evaluate the effect of the common polymorphism in the MTHFD1 gene, the G1958A (R653Q, dbSNP ID: rs2236225) variant, on the risk of NTDs in all eligible studies. Methods Relevant literature published before January 3, 2014 was retrieved from the MEDLINE, EMBASE, Cochrane Library, and CBM databases. Pooled crude odds ratios (ORs) and their corresponding 95% confidence intervals (CIs) were calculated to evaluate the association between the MTHFD1 G1958A polymorphism and NTDs risk. Results We performed a meta-analysis of nine studies with a total of 4,302 NTDs patients and 4,238 healthy controls. Our results demonstrated a significant correlation between the MTHFD1 G1958A polymorphism and NTDs in an overall meta-analysis. For family-based studies, the study subjects were classified as NTD cases, mothers with NTDs offspring, and fathers with NTDs offspring. We found no association between any of the fathers’ genotypes and NTDs, whereas there was a clear excess of the 1958A allele in the mothers of children with NTDs compared with controls individuals. Conclusions In summary, our meta-analysis strongly suggests that the MTHFD1 G1958A polymorphism might be associated with maternal risk for NTDs in Caucasian populations. However, the evidence of this association should be interpreted with caution due to the selective nature of publication of genetic association studies. PMID:24977710

Jiang, Jianxin; Zhang, Yanfei; Wei, Liang; Sun, Zhiyang; Liu, Zhongmin

2014-01-01

165

Folate deficiency-induced oxidative stress contributes to neuropathy in young and aged zebrafish - Implication in neural tube defects and Alzheimer's diseases.  

PubMed

Folate is a nutrient essential for the development, function and regeneration of nervous systems. Folate deficiency has been linked to many neurological disorders including neural tube defects in fetus and Alzheimer's diseases in the elderly. However, the etiology underlying these folate deficiency-associated diseases is not completely understood. In this study, zebrafish transgenic lines with timing and duration-controllable folate deficiency were developed by ectopically overexpressing a recombinant EGFP-?-glutamyl hydrolase (?GH). Impeded neural crest cell migration was observed in the transgenic embryos when folate deficiency was induced in early stages, leading to defective neural tube closure and hematopoiesis. Adding reduced folate or N-acetylcysteine reversed the phenotypic anomalies, supporting the causal link between the increased oxidative stress and the folate deficiency-induced abnormalities. When folate deficiency was induced in aged fish accumulation of beta-amyloid and phosphorylated Tau protein were found in the fish brain cryo-sections. Increased autophagy and accumulation of acidic autolysosome were apparent in folate deficient neuroblastoma cells, which were reversed by reduced folate or N-acetylcysteine supplementation. Decreased expression of cathepsin B, a lysosomal protease, was also observed in cells and tissue with folate deficiency. We concluded that folate deficiency-induced oxidative stress contributed to the folate deficiency-associated neuropathogenesis in both early and late stages of life. PMID:25131448

Kao, Tseng-Ting; Chu, Chia-Yi; Lee, Gang-Hui; Hsiao, Tsun-Hsien; Cheng, Nai-Wei; Chang, Nan-Shan; Chen, Bing-Hung; Fu, Tzu-Fun

2014-11-01

166

Use of natural neural scaffolds consisting of engineered vascular endothelial growth factor immobilized on ordered collagen fibers filled in a collagen tube for peripheral nerve regeneration in rats.  

PubMed

The search for effective strategies for peripheral nerve regeneration has attracted much attention in recent years. In this study, ordered collagen fibers were used as intraluminal fibers after nerve injury in rats. Vascular endothelial growth factor (VEGF) plays an important role in nerve regeneration, but its very fast initial burst of activity within a short time has largely limited its clinical use. For the stable binding of VEGF to ordered collagen fibers, we fused a collagen-binding domain (CBD) to VEGF through recombinant DNA technology. Then, we filled the ordered collagen fibers-CBD-VEGF targeting delivery system in a collagen tube to construct natural neural scaffolds, which were then used to bridge transected nerve stumps in a rat sciatic nerve transection model. After transplantation, the natural neural scaffolds showed minimal foreign body reactions and good integration into the host tissue. Oriented collagen fibers in the collagen tube could guide regenerating axons in an oriented manner to the distal, degenerating nerve segment, maximizing the chance of target reinnervation. Functional and histological analyses indicated that the recovery of nerve function in the natural neural scaffolds-treated group was superior to the other grafted groups. The guiding of oriented axonal regeneration and effective delivery systems surmounting the otherwise rapid and short-lived diffusion of growth factors in body fluids are two important strategies in promoting peripheral nerve regeneration. The natural neural scaffolds described take advantage of these two aspects and may produce synergistic effects. These properties qualified the artificial nerve conduits as a putative candidate system for the fabrication of peripheral nerve reconstruction devices. PMID:25322152

Ma, Fukai; Xiao, Zhifeng; Meng, Danqing; Hou, Xianglin; Zhu, Jianhong; Dai, Jianwu; Xu, Ruxiang

2014-01-01

167

Use of Natural Neural Scaffolds Consisting of Engineered Vascular Endothelial Growth Factor Immobilized on Ordered Collagen Fibers Filled in a Collagen Tube for Peripheral Nerve Regeneration in Rats  

PubMed Central

The search for effective strategies for peripheral nerve regeneration has attracted much attention in recent years. In this study, ordered collagen fibers were used as intraluminal fibers after nerve injury in rats. Vascular endothelial growth factor (VEGF) plays an important role in nerve regeneration, but its very fast initial burst of activity within a short time has largely limited its clinical use. For the stable binding of VEGF to ordered collagen fibers, we fused a collagen-binding domain (CBD) to VEGF through recombinant DNA technology. Then, we filled the ordered collagen fibers-CBD-VEGF targeting delivery system in a collagen tube to construct natural neural scaffolds, which were then used to bridge transected nerve stumps in a rat sciatic nerve transection model. After transplantation, the natural neural scaffolds showed minimal foreign body reactions and good integration into the host tissue. Oriented collagen fibers in the collagen tube could guide regenerating axons in an oriented manner to the distal, degenerating nerve segment, maximizing the chance of target reinnervation. Functional and histological analyses indicated that the recovery of nerve function in the natural neural scaffolds-treated group was superior to the other grafted groups. The guiding of oriented axonal regeneration and effective delivery systems surmounting the otherwise rapid and short-lived diffusion of growth factors in body fluids are two important strategies in promoting peripheral nerve regeneration. The natural neural scaffolds described take advantage of these two aspects and may produce synergistic effects. These properties qualified the artificial nerve conduits as a putative candidate system for the fabrication of peripheral nerve reconstruction devices. PMID:25322152

Ma, Fukai; Xiao, Zhifeng; Meng, Danqing; Hou, Xianglin; Zhu, Jianhong; Dai, Jianwu; Xu, Ruxiang

2014-01-01

168

Fetal MRI in the evaluation of fetuses referred for sonographically suspected neural tube defects (NTDs): impact on diagnosis and management decision  

Microsoft Academic Search

Introduction  We hypothesized that magnetic resonance imaging (MRI) can assess fetuses with sonographically (ultrasonography (US))-suspected\\u000a neural tube defects (NTD) that might influence their diagnoses and management decision.\\u000a \\u000a \\u000a \\u000a Methods  Institutional review board approval and informed consents were obtained to perform MRI for 19 fetuses referred with US-suspected\\u000a NTD. Prenatal imaging findings were correlated with management decision, postnatal clinical, postnatal imaging, and pathology.\\u000a \\u000a \\u000a \\u000a Results  Prenatal

Sahar N. Saleem; Ahmed-Hesham Said; Maged Abdel-Raouf; Eman A. El-Kattan; Maha Saad Zaki; Noha Madkour; Mostafa Shokry

2009-01-01

169

The impact of prenatal diagnosis on neural tube defect (NTD) pregnancy versus birth incidence in British Columbia.  

PubMed

The birth incidence of neural tube defect (NTD) cases in British Columbia (B.C.), and elsewhere in North America, is reported to be declining. This decline is being attributed to folic acid (FA) supplementation and food fortification, but 2nd trimester prenatal screening of pregnancies for NTDs and other congenital anomalies has increased during this timeframe, as well. This descriptive, population-based study evaluates the impact of prenatal screening of NTD-affected pregnancies on (1) pregnancy outcome and (2) reporting of NTD births to the provincial Health Status Registry (B.C.H.S.R.); and it assesses (3) the use of periconceptional FA supplementation. NTD cases were ascertained from medical records of health centres providing care to families with NTD-affected pregnancies and newborns; and from NTD cases reported to the B.C.H.S.R. In 1997-1999, the B.C.H.S.R. published a NTD incidence of 0.77/1000. In this study, 151 NTD-affected pregnancies were identified, with an incidence of 1.16/1000. Partial Reporting of induced abortions in a NTD incidence 45.5% low than the actual incidence. Medical records were available for review on 144/151 pregnancies. Prenatal screening identified 86.1% (124/144) of NTD-affected pregnancies, with 72.6% (90/124) resulting in pregnancy termination, and 27.4% (34/124) continuing to term. Use of FA supplementation in the periconceptional period was recorded in 36.4% of pregnancies (39/107). Thus in B.C. the decline in the NTD incidence is due predominantly to pregnancy terminations following prenatal diagnosis, which reduces the NTD incidence by 60%, from 1.16/1000 to 0.47/1000. Continued efforts for primary and the option of secondary prevention of NTDs are recommended in order to improve newborn health in B.C. and elsewhere. These interventions need to be monitored, however, for optimal health care planning. PMID:16682757

Van Allen, Margot I; Boyle, Erin; Thiessen, Paul; McFadden, Deborah; Cochrane, Douglas; Chambers, G Keith; Langlois, Sylvie; Stathers, Patricia; Irwin, Beverly; Cairns, Elizabeth; MacLeod, Patrick; Delisle, Marie-France; Uh, Soo-Hong

2006-01-01

170

Blocking hedgehog signaling after ablation of the dorsal neural tube allows regeneration of the cardiac neural crest and rescue of outflow tract septation  

Microsoft Academic Search

Cardiac neural crest cells (CNCC) migrate into the caudal pharynx and arterial pole of the heart to form the outflow septum. Ablation of the CNCC results in arterial pole malalignment and failure of outflow septation, resulting in a common trunk overriding the right ventricle. Unlike preotic cranial crest, the postotic CNCC do not normally regenerate. We applied the hedgehog signaling

Mary Redmond Hutson; Faustina N. Sackey; Katherine Lunney; Margaret L. Kirby

2009-01-01

171

In ovo Electroporation of miRNA-based Plasmids in the Developing Neural Tube and Assessment of Phenotypes by DiI Injection in Open-book Preparations  

PubMed Central

Commissural dI1 neurons have been extensively studied to elucidate the mechanisms underlying axon guidance during development1,2. These neurons are located in the dorsal spinal cord and send their axons along stereotyped trajectories. Commissural axons initially project ventrally towards and then across the floorplate. After crossing the midline, these axons make a sharp rostral turn and project longitudinally towards the brain. Each of these steps is regulated by the coordinated activities of attractive and repulsive guidance cues. The correct interpretation of these cues is crucial to the guidance of axons along their demarcated pathway. Thus, the physiological contribution of a particular molecule to commissural axon guidance is ideally investigated in the context of the living embryo. Accordingly, gene knockdown in vivo must be precisely controlled in order to carefully distinguish axon guidance activities of genes that may play multiple roles during development. Here, we describe a method to knockdown gene expression in the chicken neural tube in a cell type-specific, traceable manner. We use novel plasmid vectors3 harboring cell type-specific promoters/enhancers that drive the expression of a fluorescent protein marker, followed directly by a miR30-RNAi transcript4 (located within the 3'-UTR of the cDNA encoding the fluorescent protein) (Figure 1). When electroporated into the developing neural tube, these vectors elicit efficient downregulation of gene expression and express bright fluorescent marker proteins to enable direct tracing of the cells experiencing knockdown3. Mixing different RNAi vectors prior to electroporation allows the simultaneous knockdown of two or more genes in independent regions of the spinal cord. This permits complex cellular and molecular interactions to be examined during development, in a manner that is fast, simple, precise and inexpensive. In combination with DiI tracing of commissural axon trajectories in open-book preparations5, this method is a useful tool for in vivo studies of the cellular and molecular mechanisms of commissural axon growth and guidance. In principle, any promoter/enhancer could be used, potentially making the technique more widely applicable for in vivo studies of gene function during development6. This video first demonstrates how to handle and window eggs, the injection of DNA plasmids into the neural tube and the electroporation procedure. To investigate commissural axon guidance, the spinal cord is removed from the embryo as an open-book preparation, fixed, and injected with DiI to enable axon pathways to be traced. The spinal cord is mounted between coverslips and visualized using confocal microscopy. PMID:23093090

Wilson, Nicole H.; Stoeckli, Esther T.

2012-01-01

172

In ovo electroporation of miRNA-based plasmids in the developing neural tube and assessment of phenotypes by DiI injection in open-book preparations.  

PubMed

Commissural dI1 neurons have been extensively studied to elucidate the mechanisms underlying axon guidance during development(1,2). These neurons are located in the dorsal spinal cord and send their axons along stereotyped trajectories. Commissural axons initially project ventrally towards and then across the floorplate. After crossing the midline, these axons make a sharp rostral turn and project longitudinally towards the brain. Each of these steps is regulated by the coordinated activities of attractive and repulsive guidance cues. The correct interpretation of these cues is crucial to the guidance of axons along their demarcated pathway. Thus, the physiological contribution of a particular molecule to commissural axon guidance is ideally investigated in the context of the living embryo. Accordingly, gene knockdown in vivo must be precisely controlled in order to carefully distinguish axon guidance activities of genes that may play multiple roles during development. Here, we describe a method to knockdown gene expression in the chicken neural tube in a cell type-specific, traceable manner. We use novel plasmid vectors(3) harboring cell type-specific promoters/enhancers that drive the expression of a fluorescent protein marker, followed directly by a miR30-RNAi transcript(4) (located within the 3'-UTR of the cDNA encoding the fluorescent protein) (Figure 1). When electroporated into the developing neural tube, these vectors elicit efficient downregulation of gene expression and express bright fluorescent marker proteins to enable direct tracing of the cells experiencing knockdown(3). Mixing different RNAi vectors prior to electroporation allows the simultaneous knockdown of two or more genes in independent regions of the spinal cord. This permits complex cellular and molecular interactions to be examined during development, in a manner that is fast, simple, precise and inexpensive. In combination with DiI tracing of commissural axon trajectories in open-book preparations(5), this method is a useful tool for in vivo studies of the cellular and molecular mechanisms of commissural axon growth and guidance. In principle, any promoter/enhancer could be used, potentially making the technique more widely applicable for in vivo studies of gene function during development(6). This video first demonstrates how to handle and window eggs, the injection of DNA plasmids into the neural tube and the electroporation procedure. To investigate commissural axon guidance, the spinal cord is removed from the embryo as an open-book preparation, fixed, and injected with DiI to enable axon pathways to be traced. The spinal cord is mounted between coverslips and visualized using confocal microscopy. PMID:23093090

Wilson, Nicole H; Stoeckli, Esther T

2012-01-01

173

Primary prevention of neural-tube defects and some other congenital abnormalities by folic acid and multivitamins: history, missed opportunity and tasks  

PubMed Central

The history of intervention trials of periconception folic acid with multivitamin and folic acid supplementation in women has shown a recent breakthrough in the primary prevention of structural birth defects, namely neural-tube defects and some other congenital abnormalities. Recently, some studies have demonstrated the efficacy of this new method in reducing congenital abnormalities with specific origin; for example, in the offspring of diabetic and epileptic mothers, and in pregnancy with high fever. The benefits and drawbacks of four possible uses of periconception folate/folic acid and multivitamin supplementation are discussed: we believe there has been a missed opportunity to implement this preventive approach in medical practice. The four methods are as follows: (i) dietary intake of folate and other vitamins, (ii) periconception folic acid/multivitamin supplementation, (iii) food fortification with folic acid, and (iv) the combination of oral contraceptives with 6S-5-methytetrahydrofolate (‘folate’). PMID:25083211

Bártfai, Zoltán; Bánhidy, Ferenc

2011-01-01

174

A New Text Detection Approach Based on BP Neural Network for Vehicle License Plate Detection in Complex Background  

Microsoft Academic Search

With the development of Intelligent Transport Systems (ITS), automatic license plate recognition (LPR) plays an important\\u000a role in numerous applications in reality. In this paper, a coarse to fine algorithm to detect license plates in images and\\u000a video frames with complex background is proposed. First, the method based on Component Connect (CC) is used to detect the\\u000a possible license plate

Yanwen Li; Meng Li; Yinghua Lu; Ming Yang; Chunguang Zhou

2007-01-01

175

Levels of PAH-DNA Adducts in Placental Tissue and the Risk of Fetal Neural Tube Defects in a Chinese Population  

PubMed Central

We examined the relationship between PAH-DNA adduct levels in the placental tissue, measured by a highly sensitive 32P-postlabeling assay, and the risk of fetal neural tube defects (NTDs). We further explored the interaction between PAH-DNA adducts and placental PAHs with respect to NTD risk. Placental tissues from 80 NTD-affected pregnancies and 50 uncomplicated normal pregnancies were included in this case-control study. Levels of PAH-DNA adducts were lower in the NTD group (8.12 per 108 nucleotides) compared to controls (9.92 per 108 nucleotides). PAH-DNA adduct concentrations below the median was associated with a 3-fold increased NTD risk. Women with a low PAH-DNA adduct level in concert with a high placental PAH level resulted in a 10-fold elevated risk of having an NTD-complicated pregnancy. A low level of placental PAH-DNA adducts was associated with an increased risk of NTDs; this risk increased dramatically when a low adduct level was coupled with a high placental PAH concentration. PMID:23416326

Yuan, Yue; Jin, Lei; Wang, Linlin; Li, Zhiwen; Zhang, Le; Zhu, Huiping; Finnell, Richard H; Zhou, Guodong; Ren, Aiguo

2014-01-01

176

Neural tube defects induced by folate deficiency in mutant curly tail (Grhl3) embryos are associated with alteration in folate one-carbon metabolism but are unlikely to result from diminished methylation  

PubMed Central

Background Folate one-carbon metabolism has been implicated as a determinant of susceptibility to neural tube defects (NTDs), owing to the preventive effect of maternal folic acid supplementation and the higher risk associated with markers of diminished folate status. Methods Folate one-carbon metabolism was compared in curly tail (ct/ct) and genetically matched congenic (+ct/+ct) mouse strains using the deoxyuridine suppression test in embryonic fibroblast cells and by quantifying s-adenosylmethionine (SAM) and s-adenosylhomocysteine (SAH) in embryos using liquid chromatography tandem mass spectrometry. A possible genetic interaction between curly tail and a null allele of 5,10-methylenetetrahydrofolate reductase (MTHFR) was investigated by generation of compound mutant embryos. Results There was no deficit in thymidylate biosynthesis in ct/ct cells but incorporation of exogenous thymidine was lower than in +ct/+ct cells. In +ct/+ct embryos the SAM/SAH ratio was diminished by dietary folate deficiency and normalised by folic acid or myor-inositol treatment, in association with prevention of NTDs. In contrast, folate deficiency caused a significant increase in SAM/SAH ratio in ct/ct embryos. Loss of MTHFR function in curly tail embryos significantly reduced the SAM/SAH ratio but did not cause cranial NTDs or alter the frequency of caudal NTDs. Conclusions Curly tail fibroblasts and embryos, in which Grhl3 expression is reduced, display alterations in one-carbon metabolism, particularly in the response to folate deficiency, compared with genetically-matched congenic controls in which Grhl3 is unaffected. However, unlike folate deficiency, diminished methylation potential appears to be insufficient to cause cranial NTDs in the curly tail strain, and neither does it increase the frequency of caudal NTDs. PMID:20589880

De Castro, Sandra CP; Leung, Kit-yi; Savery, Dawn; Burren, Katie; Rozen, Rima; Copp, Andrew J.; Greene, Nicholas D.E.

2013-01-01

177

Investigation, using rat embryo culture, of the role of methionine supply in folic acid-mediated prevention of neural tube defects.  

PubMed

Peri-conceptional folic acid supplementation has become a well established way to prevent neural tube defects (NTDs) and such supplementation reduces the prevalence of these defects by approximately 70%. However, the mechanism of the preventive effect of folic acid is not clear. This overview focuses on the biochemical basis of folic acid-preventable NTDs and on the results obtained with whole embryo culture that may help to shed some light on the mechanisms that underlie the preventive effect of folic acid. Culturing gestational day (GD) 9.5 rat embryos on diet-induced folate-deficient rat serum resulted in many malformations, but no NTDs and this embryotoxicity could only partly be overcome by supplementation with N(5)-methyltetrahydrofolate(5-methylTHF). This indicates that there may be an indirect effect of folate deficiency. Besides an important role in purine and thymidine synthesis, folate drives the methylation cycle in which the methyl group of 5-methylTHF is transferred to numerous biomolecules. In this process homocysteine and methionine are constantly interconverted. It was hypothesized that folate deficiency might lead to a toxic accumulation of homocysteine. However, only homocysteine levels 100-fold higher than physiological levels were embryotoxic to cultured GD10 rat embryos. Moreover, 1 and 2 mm l-homocysteine could prevent NTDs in GD9.5 rat embryos when they were cultured in human serum. Addition of 100 mum methionine had the same preventive effect, but addition of 1 mm folinic acid could not prevent the NTDs. When embryos were cultured in cow or canine serum, methionine had a similar preventive effect. These results suggest folic acid mediated prevention of NTDs may be based on an increase of the methionine supply and possibly its supportive action towards the methylation cycle. PMID:20650144

Vanaerts, L A

1995-10-01

178

Spatio-temporal curvature pattern of the caudal body axis for non-mutant and curly tail mouse embryos during the period of caudal neural tube closure.  

PubMed

During the period of early organogenesis the mouse embryo has a curved body shape, which is thought to interact with ongoing developmental processes. Curly tail is a mouse mutant causing spina bifida, in which aberrant axial curvature is considered to be responsible for a delay in the closure of the posterior neuropore (PNP). Since detailed descriptions of axial curvature have never been made in either the normal or the mutant embryo, the onset and development of the aberrant axial curvature in the curly tail embryo are unknown. In the present study, axial curvature and segmental growth during closure of the PNP are described using circle segments at each somite level in two non-mutant mouse strains. Using the radius and angle of the segments as parameters, CD-1 and Balb/c mouse embryos showed maxima of curvature at the levels of the limb buds. Throughout development, a general axial unbending occurred that was due to a level-specific combination of general outgrowth and other factors. A marked additional decrease in the axial curvature was spatially and temporally related to the final closure of the PNP, indicating that this decrease of curvature facilities the final closure of the PNP. In the curly tail embryo the segment parameter radius was used to relate the axial curvature to an aberrant neural tube closure pattern. These embryos exhibited an enhanced curvature over the entire neuropore region as soon as a delay in the PNP closure could be distinguished. A steep decrease in curvature during final closure of the PNP did also occur, but at a more caudal level. Both the axial level of straightening and the rate of curvature were normalized at advanced developmental stages. The aberrant spatio-temporal curvature pattern in the curly tail mouse embryo indicates that both the rate of curvature and the axial level of unbending are important for a correct PNP closure. PMID:9084824

Peeters, M C; Hekking, W M; Vainas, T; Drukker, J; van Straaten, H W

1997-03-01

179

Initiating Hox gene expression: in the early chick neural tube differential sensitivity to FGF and RA signaling subdivides the HoxB genes in two distinct groups.  

PubMed

Initiation of Hox genes requires interactions between numerous factors and signaling pathways in order to establish their precise domain boundaries in the developing nervous system. There are distinct differences in the expression and regulation of members of Hox genes within a complex suggesting that multiple competing mechanisms are used to initiate their expression domains in early embryogenesis. In this study, by analyzing the response of HoxB genes to both RA and FGF signaling in neural tissue during early chick embryogenesis (HH stages 7-15), we have defined two distinct groups of Hox genes based on their reciprocal sensitivity to RA or FGF during this developmental period. We found that the expression domain of 5' members from the HoxB complex (Hoxb6-Hoxb9) can be expanded anteriorly in the chick neural tube up to the level of the otic vesicle following FGF treatment and that these same genes are refractory to RA treatment at these stages. Furthermore, we showed that the chick caudal-related genes, cdxA and cdxB, are also responsive to FGF signaling in neural tissue and that their anterior expansion is also limited to the level of the otic vesicle. Using a dominant negative form of a Xenopus Cdx gene (XcadEnR) we found that the effect of FGF treatment on 5' HoxB genes is mediated in part through the activation and function of CDX activity. Conversely, the 3' HoxB genes (Hoxb1 and Hoxb3-Hoxb5) are sensitive to RA but not FGF treatments at these stages. We demonstrated by in ovo electroporation of a dominant negative retinoid receptor construct (dnRAR) that retinoid signaling is required to initiate expression. Elevating CDX activity by ectopic expression of an activated form of a Xenopus Cdx gene (XcadVP16) in the hindbrain ectopically activates and anteriorly expands Hoxb4 expression. In a similar manner, when ectopic expression of XcadVP16 is combined with FGF treatment, we found that Hoxb9 expression expands anteriorly into the hindbrain region. Our findings suggest a model whereby, over the window of early development we examined, all HoxB genes are actually competent to interpret an FGF signal via a CDX-dependent pathway. However, mechanisms that axially restrict the Cdx domains of expression, serve to prevent 3' genes from responding to FGF signaling in the hindbrain. FGF may have a dual role in both modulating the accessibility of the HoxB complex along the axis and in activating the expression of Cdx genes. The position of the shift in RA or FGF responsiveness of Hox genes may be time dependent. Hence, the specific Hox genes in each of these complementary groups may vary in later stages of development or other tissues. These results highlight the key role of Cdx genes in integrating the input of multiple signaling pathways, such as FGFs and RA, in controlling initiation of Hox expression during development and the importance of understanding regulatory events/mechanisms that modulate Cdx expression. PMID:12399303

Bel-Vialar, Sophie; Itasaki, Nobue; Krumlauf, Robb

2002-11-01

180

Zebrafish arl6ip1 Is Required for Neural Crest Development during Embryogenesis  

PubMed Central

Background Although the embryonic expression pattern of ADP ribosylation factor-like 6 interacting protein 1 (Arl6ip1) has been reported, its function in neural crest development is unclear. Methods/Principal Findings We found that knockdown of Arl6ip1 caused defective embryonic neural crest derivatives that were particularly severe in craniofacial cartilages. Expressions of the ectodermal patterning factors msxb, dlx3b, and pax3 were normal, but the expressions of the neural crest specifier genes foxd3, snai1b, and sox10 were greatly reduced. These findings suggest that arl6ip1 is essential for specification of neural crest derivatives, but not neural crest induction. Furthermore, we revealed that the streams of crestin- and sox10-expressing neural crest cells, which migrate ventrally from neural tube into trunk, were disrupted in arl6ip1 morphants. This migration defect was not only in the trunk neural crest, but also in the enteric tract where the vagal-derived neural crest cells failed to populate the enteric nervous system. We found that this migration defect was induced by dampened Shh signaling, which may have resulted from defective cilia. These data further suggested that arl6ip1 is required for neural crest migration. Finally, by double-staining of TUNEL and crestin, we confirmed that the loss of neural crest cells could not be attributed to apoptosis. Conclusions/Significance Therefore, we concluded that arl6ip1 is required for neural crest migration and sublineage specification. PMID:22427906

Tu, Chi-Tang; Yang, Tzu-Ching; Huang, Hsing-Yen; Tsai, Huai-Jen

2012-01-01

181

Massive-training artificial neural network (MTANN) for reduction of false positives in computer-aided detection of polyps: Suppression of rectal tubes  

SciTech Connect

One of the limitations of the current computer-aided detection (CAD) of polyps in CT colonography (CTC) is a relatively large number of false-positive (FP) detections. Rectal tubes (RTs) are one of the typical sources of FPs because a portion of a RT, especially a portion of a bulbous tip, often exhibits a cap-like shape that closely mimics the appearance of a small polyp. Radiologists can easily recognize and dismiss RT-induced FPs; thus, they may lose their confidence in CAD as an effective tool if the CAD scheme generates such ''obvious'' FPs due to RTs consistently. In addition, RT-induced FPs may distract radiologists from less common true positives in the rectum. Therefore, removal RT-induced FPs as well as other types of FPs is desirable while maintaining a high sensitivity in the detection of polyps. We developed a three-dimensional (3D) massive-training artificial neural network (MTANN) for distinction between polyps and RTs in 3D CTC volumetric data. The 3D MTANN is a supervised volume-processing technique which is trained with input CTC volumes and the corresponding ''teaching'' volumes. The teaching volume for a polyp contains a 3D Gaussian distribution, and that for a RT contains zeros for enhancement of polyps and suppression of RTs, respectively. For distinction between polyps and nonpolyps including RTs, a 3D scoring method based on a 3D Gaussian weighting function is applied to the output of the trained 3D MTANN. Our database consisted of CTC examinations of 73 patients, scanned in both supine and prone positions (146 CTC data sets in total), with optical colonoscopy as a reference standard for the presence of polyps. Fifteen patients had 28 polyps, 15 of which were 5-9 mm and 13 were 10-25 mm in size. These CTC cases were subjected to our previously reported CAD scheme that included centerline-based segmentation of the colon, shape-based detection of polyps, and reduction of FPs by use of a Bayesian neural network based on geometric and texture features. Application of this CAD scheme yielded 96.4% (27/28) by-polyp sensitivity with 3.1 (224/73) FPs per patient, among which 20 FPs were caused by RTs. To eliminate the FPs due to RTs and possibly other normal structures, we trained a 3D MTANN with ten representative polyps and ten RTs, and applied the trained 3D MTANN to the above CAD true- and false-positive detections. In the output volumes of the 3D MTANN, polyps were represented by distributions of bright voxels, whereas RTs and other normal structures partly similar to RTs appeared as darker voxels, indicating the ability of the 3D MTANN to suppress RTs as well as other normal structures effectively. Application of the 3D MTANN to the CAD detections showed that the 3D MTANN eliminated all RT-induced 20 FPs, as well as 53 FPs due to other causes, without removal of any true positives. Overall, the 3D MTANN was able to reduce the FP rate of the CAD scheme from 3.1 to 2.1 FPs per patient (33% reduction), while the original by-polyp sensitivity of 96.4% was maintained.

Suzuki, Kenji; Yoshida, Hiroyuki; Naeppi, Janne; Dachman, Abraham H. [Department of Radiology, University of Chicago, 5841 South Maryland Avenue, Chicago, Illinois 60637 (United States); Department of Radiology, Massachusetts General Hospital and Harvard Medical School, 75 Blossom Court, Suite 220, Boston, Massachusetts 02114 (United States); Department of Radiology, University of Chicago, 5841 South Maryland Avenue, Chicago, Illinois 60637 (United States)

2006-10-15

182

Twins and neural tube defects  

PubMed Central

The hypothesis that anencephalus stems from fetus-fetus interactions in dizygotic twin pairs is examined by comparing the epidemiological predictions of the hypothesis with available observations. The hypothesis itself was based upon the disease-discordance and sex-concordance characteristics of twin pairs affected with anencephalus, and upon the sex ratio of the disease itself. The testable predictions of the hypothesis are (a) that variations in the incidence of anencephalus should be related to variations in dizygotic twinning rates, and particularly that dizygotic twinning rates will set upper limits to the incidence of anencephalus, and (b) that the F/M ratio in anencephalic infants will be high in circumstances of high incidence, and specifically when the incidence is high in relation to the dizygotic twinning rate. Examples from international comparisons, secular changes, social class gradients, and variations according to maternal age confirm a consistent correspondence between observations and these predictions. In addition, the possibility was tested that some fetus-fetus interactions might be based upon sequential rather than simultaneous pairs of fetuses. This model predicted asymmetries of sex ratio in sibs immediately preceding propositi, with differences according to the sex of the affected child, and the predicted findings were confirmed. The fetus-fetus interaction hypothesis is therefore extended in the terms that about one third of occurrences are determined in a sequential manner. The success of the extended fetus-fetus interaction model in explaining a large number of otherwise unrelatable findings confirms its validity. PMID:4605406

Knox, E. G.

1974-01-01

183

Gastrostomy Tube (G-Tube)  

MedlinePLUS

About G-Tubes Some kids have medical problems that prevent them from being able to take adequate nutrition by mouth. A gastrostomy tube (also called a G-tube ) is a tube inserted through the abdomen ...

184

Wind Tubes  

NSDL National Science Digital Library

In this activity, learners create and experiment with wind tubes. These tubes are a playful and inventive way to explore the effect that moving air has on objects. Construction uses everyday materials such as a fan and embroidery hoops. Itâs fun to make things fly out of or float in the tubes, and to adjust the tubes to change the way the objects fly. The activity requires a significant amount of time and resources to build and may require adult help in construction. Experimentation with the wind tubes is engaging for a wide age range of learners.

Exploratorium

2012-12-14

185

The genesis of avian neural crest cells: a classic embryonic induction.  

PubMed Central

Neural crest cells arise from the ectoderm and are first recognizable as discrete cells in the chicken embryo when they emerge from the neural tube. Despite the classical view that neural crest precursors are a distinct population lying between epidermis and neuroepithelium, our results demonstrate that they are not a segregated population. Cell lineage analyses have demonstrated that individual precursor cells within the neural folds can give rise to epidermal, neural crest, and neural tube derivatives. Interactions between the neural plate and epidermis can generate neural crest cells, since juxtaposition of these tissues at early stages results in the formation of neural crest cells at the interface. Inductive interactions between the epidermis and neural plate can also result in "dorsalization" of the neural plate, as assayed by the expression of the Wnt transcripts characteristic of the dorsal neural tube. The competence of the neural plate changes with time, however, such that interaction of early neural plate with epidermis generates only neural crest cells, whereas interaction of slightly older neural plate with epidermis generates neural crest cells and Wnt-expressing cells. At cranial levels, neuroepithelial cells can regulate to generate neural crest cells when the endogenous neural folds are removed, probably via interaction of the remaining neural tube with the epidermis. Taken together, these experiments demonstrate that: (i) progenitor cells in the neural folds are multipotent, having the ability to form multiple ectodermal derivatives, including epidermal, neural crest, and neural tube cells; (ii) the neural crest is an induced population that arises by interactions between the neural plate and the epidermis; and (iii) the competence of the neural plate to respond to inductive interactions changes as a function of embryonic age. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 PMID:8790333

Selleck, M A; Bronner-Fraser, M

1996-01-01

186

Folate Status of Reproductive Age Women and Neural Tube Defect Risk: The Effect of Long-Term Folic Acid Supplementation at Doses of 140 ug and 400 ug per Day  

PubMed Central

Primary prevention of most folate-responsive neural tube defects (NTDs) may not require 400 ?g folic acid/day but may be achieved by attaining a high maternal folate status. Using RBC folate ?906 nmol/L as a marker for NTD risk reduction, the study aimed to determine the change in blood folate concentrations in reproductive age women in response to long-term folic acid supplementation at 400 µg/day and 140 µg/day (dose designed to mimic the average daily folic acid intake received from New Zealand’s proposed mandatory bread fortification program). Participants were randomly assigned to a daily folic acid supplement of 140 µg (n = 49), 400 µg (n = 48) or placebo (n = 47) for 40 weeks. RBC folate concentrations were measured at baseline, and after 6, 12, 29 and 40 weeks. At 40 weeks, the overall prevalence of having a RBC folate <906 nmol/L decreased to 18% and 35% in the 400 µg and 140 µg groups, respectively, while remaining relatively unchanged at 58% in the placebo group. After 40 weeks, there was no evidence of a difference in RBC folate between the two treatment groups (P = 0.340), nor was there evidence of a difference in the odds of a RBC folate <906 nmol/L (P = 0.078). In conclusion, the average daily intake of folic acid received from the proposed fortification program would increase RBC folate concentrations in reproductive age women to levels associated with a low risk of NTDs. PMID:22254076

Hursthouse, Nicola A.; Gray, Andrew R.; Miller, Jody C.; Rose, Meredith C.; Houghton, Lisa A.

2011-01-01

187

Emergence and migration of trunk neural crest cells in a snake, the California Kingsnake (Lampropeltis getula californiae)  

PubMed Central

Background The neural crest is a group of multipotent cells that emerges after an epithelial-to-mesenchymal transition from the dorsal neural tube early during development. These cells then migrate throughout the embryo, giving rise to a wide variety derivatives including the peripheral nervous system, craniofacial skeleton, pigment cells, and endocrine organs. While much is known about neural crest cells in mammals, birds, amphibians and fish, relatively little is known about their development in non-avian reptiles like snakes and lizards. Results In this study, we show for the first time ever trunk neural crest migration in a snake by labeling it with DiI and immunofluorescence. As in birds and mammals, we find that early migrating trunk neural crest cells use both a ventromedial pathway and an inter-somitic pathway in the snake. However, unlike birds and mammals, we also observed large numbers of late migrating neural crest cells utilizing the inter-somitic pathway in snake. Conclusions We found that while trunk neural crest migration in snakes is very similar to that of other amniotes, the inter-somitic pathway is used more extensively by late-migrating trunk neural crest cells in snake. PMID:20482793

2010-01-01

188

Radiation losses in resonant tubes  

NASA Technical Reports Server (NTRS)

The role of radiation losses in a resonant tube - the transfer of sound energy from the test gas through the confines of the tube to the ambient atmosphere - is investigated both theoretically and experimentally. It is concluded that losses of this sort make no noticeable contribution to the background losses, even at high gas pressures. Nevertheless, if an axial resonant frequency of the test gas closely matches a longitudinal resonant frequency of the tube wall, the internal sound pressure can excite tube displacements of disproportionate magnitude and thus cause excessive losses, not due to radiation but rather to frictional dissipation related to the motion of the tube structure. This mechanism is effective when the mode numbers of the gas and tube have opposite parity, and makes sound absorption measurements at the fundamental gas frequency particularly problematical. An experimental investigation confirms the existence of such additional losses when the parity condition is fulfilled.

Zuckerwar, A. J.; Meredith, R. W.

1981-01-01

189

Dorsal differentiation of neural plate cells induced by BMP-mediated signals from epidermal ectoderm  

Microsoft Academic Search

The cellular interactions that control the differentiation of dorsal cell types from neural progenitors have been examined in neural plate explants. Certain genes that are expressed in the dorsal neural tube are initially expressed uniformly within the neural plate and appear to achieve their dorsal restriction through a Sonic hedgehog (SHH)-mediated repressive signal from the notochord. The acquisition of definitive

Karel F Liem; Gabi Tremml; Henk Roelink; Thomas M Jessell

1995-01-01

190

Neural Networks  

E-print Network

We present an overview of current research on artificial neural networks, emphasizing a statistical perspective. We view neural networks as parameterized graphs that make probabilistic assumptions about data, and view ...

Jordan, Michael I.

1996-03-13

191

Multiple tube premixing device  

DOEpatents

The present application provides a premixer for a combustor. The premixer may include a fuel plenum with a number of fuel tubes and a burner tube with a number of air tubes. The fuel tubes extend about the air tubes.

Uhm, Jong Ho; Naidu, Balachandar; Ziminksy, Willy Steve; Kraemer, Gilbert Otto; Yilmaz, Ertan; Lacy, Benjamin; Stevenson, Christian; Felling, David

2013-08-13

192

Multiple tube premixing device  

DOEpatents

The present application provides a premixer for a combustor. The premixer may include a fuel plenum with a number of fuel tubes and a burner tube with a number of air tubes. The fuel tubes extend about the air tubes.

Uhm, Jong Ho; Varatharajan, Balachandar; Ziminsky, Willy Steve; Kraemer, Gilbert Otto; Yilmaz, Ertan; Lacy, Benjamin; Stevenson, Christian; Felling, David

2012-12-11

193

Neural Crest Cell Migration  

NSDL National Science Digital Library

This simple FlashTM animation depicts migration of neural crest cells throughout the mesoderm of the neurulating germ disc. For context it opens with a cross section of the germ disc showing the neural crests at the dorsal end of the neural tube. It then turns to a lateral view, which allows users to observe neural crest cells separating from the crests and migrating into the mesoderm along the neural tube or epidermis. A back button allows users to jump to previous scenes, a rate button allows them to toggle between fast and slow modes, and a text button allows them to toggle explanatory text on and off. Instructions for opening animation with Windows system. 1. Double click the icon for the SWF. 2. A dialog box may pop up that begins with the statement "Windows cannot open this file:" If this box does not appear proceed to step 4. If it does choose "Select the program from a list," then click OK. 3. Another dialog box will pop up that lists different programs. Make sure " Internet Explorer" is selected, then click OK. 4. A Window for Internet Explorer will pop up. Beneath the toolbars at the top of the window a yellow bar will appear that reads "To help protect your security, Internet Explorer has restricted this webpage from running scripts or Active X controls that could access your computer. Click here for options..." Pass the cursor over this yellow bar and click the right mouse button. 5. A dialog box will pop up. Left click the option "Allow Blocked Content." 6. Another dialog box will appear labeled "Security Warning" asking you to confirm that you want to run the content. Click "Yes." 7. The Flash animation will appear in the Internet Explorer Window. 8. Left click anywhere in the animation to advance the display. 9. Read instructions provided by the animation for additional controls such as navigation buttons.

PhD Jack D Thatcher (West Virginia School of Osteopathic Medicine Structural Biology)

2010-11-29

194

Tube Zither  

NSDL National Science Digital Library

In this activity, learners explore sound by constructing tube zithers, stringed instruments from Southeast Asia and the South Pacific. Use this activity to demonstrate principles of sound including vibration, pitch, tone, frequency, and volume. Note: this activity requires the use of a drill, not included in the cost of materials.

Centers, Oakland D.

2012-01-01

195

Filbronectin tubes as tissue engineering devices for peripheral nerve repair  

Microsoft Academic Search

Fibronectin mats have proved to be successful guidance substrates for the outgrowth of neurites in models of neural damage. The overall aim of this investigation was to develop a tissue engineering conduit for surgical nerve reconstruction. In this study, fibronectin tubes were developed to provide global guidance for neural regrowth across a short gap. A viscous solution of concentrated plasma

J. B. Phillips; S. C. J. Bunting; Z. Ward; S. M. Hall; R. A. Brown

2002-01-01

196

Neutron tubes  

DOEpatents

A neutron tube or generator is based on a RF driven plasma ion source having a quartz or other chamber surrounded by an external RF antenna. A deuterium or mixed deuterium/tritium (or even just a tritium) plasma is generated in the chamber and D or D/T (or T) ions are extracted from the plasma. A neutron generating target is positioned so that the ion beam is incident thereon and loads the target. Incident ions cause D-D or D-T (or T-T) reactions which generate neutrons. Various embodiments differ primarily in size of the chamber and position and shape of the neutron generating target. Some neutron generators are small enough for implantation in the body. The target may be at the end of a catheter-like drift tube. The target may have a tapered or conical surface to increase target surface area.

Leung, Ka-Ngo (Hercules, CA); Lou, Tak Pui (Berkeley, CA); Reijonen, Jani (Oakland, CA)

2008-03-11

197

Neural crest contributions to the lamprey head  

NASA Technical Reports Server (NTRS)

The neural crest is a vertebrate-specific cell population that contributes to the facial skeleton and other derivatives. We have performed focal DiI injection into the cranial neural tube of the developing lamprey in order to follow the migratory pathways of discrete groups of cells from origin to destination and to compare neural crest migratory pathways in a basal vertebrate to those of gnathostomes. The results show that the general pathways of cranial neural crest migration are conserved throughout the vertebrates, with cells migrating in streams analogous to the mandibular and hyoid streams. Caudal branchial neural crest cells migrate ventrally as a sheet of cells from the hindbrain and super-pharyngeal region of the neural tube and form a cylinder surrounding a core of mesoderm in each pharyngeal arch, similar to that seen in zebrafish and axolotl. In addition to these similarities, we also uncovered important differences. Migration into the presumptive caudal branchial arches of the lamprey involves both rostral and caudal movements of neural crest cells that have not been described in gnathostomes, suggesting that barriers that constrain rostrocaudal movement of cranial neural crest cells may have arisen after the agnathan/gnathostome split. Accordingly, neural crest cells from a single axial level contributed to multiple arches and there was extensive mixing between populations. There was no apparent filling of neural crest derivatives in a ventral-to-dorsal order, as has been observed in higher vertebrates, nor did we find evidence of a neural crest contribution to cranial sensory ganglia. These results suggest that migratory constraints and additional neural crest derivatives arose later in gnathostome evolution.

McCauley, David W.; Bronner-Fraser, Marianne

2003-01-01

198

Tube furnace  

DOEpatents

A vermiculite insulated tube furnace is heated by a helically-wound resistance wire positioned within a helical groove on the surface of a ceramic cylinder, that in turn is surroundingly disposed about a doubly slotted stainless steel cylindrical liner. For uniform heating, the pitch of the helix is of shorter length over the two end portions of the ceramic cylinder. The furnace is of large volume, provides uniform temperature, offers an extremely precise programmed heating capability, features very rapid cool-down, and has a modest electrical power requirement.

Foster, Kenneth G. (Livermore, CA); Frohwein, Eugene J. (San Ramon, CA); Taylor, Robert W. (Livermore, CA); Bowen, David W. (Livermore, CA)

1991-01-01

199

Neural networks  

Microsoft Academic Search

We present an overview of current research on artificial neural networks, emphasizing a statistical perspective.We view neural networks as parameterized graphs that make probabilistic assumptions aboutdata, and view learning algorithms as methods for finding parameter values that look probable in the lightof the data. We discuss basic issues in representation and learning, and treat some of the practical issuesthat arise

Michael I. Jordan; Christopher M. Bishop

1996-01-01

200

Neural circuits controlling behavior and autonomic functions in medicinal leeches  

E-print Network

circulatory system is continually pumping blood. A leech's bilateral heart tubes require constant excitatory and Calabrese Lamb and Calabrese Neural Systems & Circuits 2011, 1:13 http circuits underlying behavior and autonomic functions, the stereotyped and accessible nervous system

Calabrese, Ronald

201

The neural crest: A versatile organ system.  

PubMed

The neural crest is the name given to the strip of cells at the junction between neural and epidermal ectoderm in neurula-stage vertebrate embryos, which is later brought to the dorsal neural tube as the neural folds elevate. The neural crest is a heterogeneous and multipotent progenitor cell population whose cells undergo EMT then extensively and accurately migrate throughout the embryo. Neural crest cells contribute to nearly every organ system in the body, with derivatives of neuronal, glial, neuroendocrine, pigment, and also mesodermal lineages. This breadth of developmental capacity has led to the neural crest being termed the fourth germ layer. The neural crest has occupied a prominent place in developmental biology, due to its exaggerated migratory morphogenesis and its remarkably wide developmental potential. As such, neural crest cells have become an attractive model for developmental biologists for studying these processes. Problems in neural crest development cause a number of human syndromes and birth defects known collectively as neurocristopathies; these include Treacher Collins syndrome, Hirschsprung disease, and 22q11.2 deletion syndromes. Tumors in the neural crest lineage are also of clinical importance, including the aggressive melanoma and neuroblastoma types. These clinical aspects have drawn attention to the selection or creation of neural crest progenitor cells, particularly of human origin, for studying pathologies of the neural crest at the cellular level, and also for possible cell therapeutics. The versatility of the neural crest lends itself to interlinked research, spanning basic developmental biology, birth defect research, oncology, and stem/progenitor cell biology and therapy. Birth Defects Research (Part C) 102:275-298, 2014. © 2014 Wiley Periodicals, Inc. PMID:25227568

Zhang, Dongcheng; Ighaniyan, Samiramis; Stathopoulos, Lefteris; Rollo, Benjamin; Landman, Kerry; Hutson, John; Newgreen, Donald

2014-09-01

202

Establishing the plane of symmetry for lumen formation and bilateral brain formation in the zebrafish neural rod.  

PubMed

The lumen of the zebrafish neural tube develops precisely at the midline of the solid neural rod primordium. This process depends on cell polarisation and cell rearrangements, both of which are manifest at the midline of the neural rod. The result of this cell polarisation and cell rearrangement is an epithelial tube that has overt mirror-symmetry, such that cell morphology and apicobasal polarisation are mirrored across the midline of the neural tube. This article discusses how this mirror-symmetry is established and proposes the hypothesis that positioning the cells' centrosomes to the midline of the neural rod is a key event in organising this process. PMID:24721474

Buckley, Clare; Clarke, Jon

2014-07-01

203

Tube-in-tube thermophotovoltaic generator  

DOEpatents

A thermophotovoltaic device includes at least one thermal radiator tube, a cooling tube concentrically disposed within each thermal radiator tube and an array of thermophotovoltaic cells disposed on the exterior surface of the cooling tube. A shell having a first end and a second end surrounds the thermal radiator tube. Inner and outer tubesheets, each having an aperture corresponding to each cooling tube, are located at each end of the shell. The thermal radiator tube extends within the shell between the inner tubesheets. The cooling tube extends within the shell through the corresponding apertures of the two inner tubesheets to the corresponding apertures of the two outer tubesheets. A plurality of the thermal radiator tubes can be arranged in a staggered or an in-line configuration within the shell.

Ashcroft, John (Scotia, NY); Campbell, Brian (Scotia, NY); DePoy, David (Clifton Park, NY)

1998-01-01

204

Tube-in-tube thermophotovoltaic generator  

DOEpatents

A thermophotovoltaic device includes at least one thermal radiator tube, a cooling tube concentrically disposed within each thermal radiator tube and an array of thermophotovoltaic cells disposed on the exterior surface of the cooling tube. A shell having a first end and a second end surrounds the thermal radiator tube. Inner and outer tubesheets, each having an aperture corresponding to each cooling tube, are located at each end of the shell. The thermal radiator tube extends within the shell between the inner tubesheets. The cooling tube extends within the shell through the corresponding apertures of the two inner tubesheets to the corresponding apertures of the two outer tubesheets. A plurality of the thermal radiator tubes can be arranged in a staggered or an in-line configuration within the shell. 8 figs.

Ashcroft, J.; Campbell, B.; DePoy, D.

1998-06-30

205

Evolvable synthetic neural system  

NASA Technical Reports Server (NTRS)

An evolvable synthetic neural system includes an evolvable neural interface operably coupled to at least one neural basis function. Each neural basis function includes an evolvable neural interface operably coupled to a heuristic neural system to perform high-level functions and an autonomic neural system to perform low-level functions. In some embodiments, the evolvable synthetic neural system is operably coupled to one or more evolvable synthetic neural systems in a hierarchy.

Curtis, Steven A. (Inventor)

2009-01-01

206

Neural networks for triggering  

SciTech Connect

Two types of neural network beauty trigger architectures, based on identification of electrons in jets and recognition of secondary vertices, have been simulated in the environment of the Fermilab CDF experiment. The efficiencies for B's and rejection of background obtained are encouraging. If hardware tests are successful, the electron identification architecture will be tested in the 1991 run of CDF. 10 refs., 5 figs., 1 tab.

Denby, B. (Fermi National Accelerator Lab., Batavia, IL (USA)); Campbell, M. (Michigan Univ., Ann Arbor, MI (USA)); Bedeschi, F. (Istituto Nazionale di Fisica Nucleare, Pisa (Italy)); Chriss, N.; Bowers, C. (Chicago Univ., IL (USA)); Nesti, F. (Scuola Normale Superiore, Pisa (Italy))

1990-01-01

207

Neural crest: facing the facts of head development  

Microsoft Academic Search

The cranial neural crest originates at the dorsal margin of the neural tube and produces migratory cells that populate various locations in the head. They are a crucial factor in the development of the vertebrate head because they give rise to numerous differentiated cell types, including the cartilage, bone and connective tissues of the skull. Thus, the coordinated regulation of

David Chambers; Imelda M. McGonnell

2002-01-01

208

[Complications of Woodbridge tubes (spiral wire tubes)].  

PubMed

Flexometallic (armoured) tubes should have advantages in orofacial surgery and difficult positioning. They still have also the possibilities of tube obstruction, as shown in four case reports. PMID:3740379

Wendt, M; Thy, H; Reinhold, P; Lawin, P

1986-05-01

209

Emission Tube Apparatus  

NSDL National Science Digital Library

This is an image of an emission tube apparatus with tube in place. When plugged in and turned on the gas in the tube will become excited and emit a specific color of light depending upon the type of gas.

Ward, Charles

2003-01-16

210

Silicon-Delivery Tube  

NASA Technical Reports Server (NTRS)

Delivery tube transfers molten silicon between high-temperature vessel. Transport tube is sealed to delivery vessel and receiving vessel and slanted so gravity moves molten silicon. Contamination is prevented since molten silicon only contacts quartz delivery tube.

Bates, H. E.; Hill, D. M.; Jewett, D. M.

1983-01-01

211

Magnetic merging in colliding flux tubes  

NASA Technical Reports Server (NTRS)

We develop an analytical theory of reconnection between colliding, twisted magnetic flux tubes. Our analysis is restricted to direct collisions between parallel tubes and is based on the collision dynamics worked out by Bogdan (1984). We show that there is a range of collision velocities for which neutral point reconnection of the Parker-Sweet type can occur, and a smaller range for which reconnection leads to coalescence. Mean velocities within the solar convection zone are probably significantly greater than the upper limit for coalescence. This suggests that the majority of flux tube collisions do not result in merging, unless the frictional coupling of the tubes to the background flow is extremely strong.

Zweibel, Ellen G.; Rhoads, James E.

1995-01-01

212

Magnetic Merging in Colliding Flux Tubes  

E-print Network

We develop an analytical theory of reconnection between colliding, twisted magnetic flux tubes. Our analysis is restricted to direct collisions between parallel tubes and is based on the collision dynamics worked out by Bogdan (1984). We show that there is a range of collision velocities for which neutral point reconnection of the Parker-Sweet type can occur, and a smaller range for which reconnection leads to coalescence. Mean velocities within the solar convection zone are probably significantly greater than the upper limit for coalescence. This suggests that the majority of flux tube collisions do not result in merging, unless the frictional coupling of the tubes to the background flow is extremely strong.

Ellen G. Zweibel; James E. Rhoads

1994-08-14

213

Transporting a tube in a tube.  

PubMed

LbL-assembled tubes were employed for micro/nanoscale cargo transportation through the kinesin-microtubule system. Selectively modified with kinesins onto the inner tube walls through Ni-NTA complexes, these tubes can work as channels for microtubules. A motility assay shows the smooth movement of microtubules along the tube inner wall powered by the inside immobilized kinesins. It could be envisioned that cargoes with different sizes can be transported through these tubular channels with little outside interruption. PMID:25303630

Li, Jieling; Jia, Yi; Dong, Weiguang; Feng, Xiyun; Fei, Jinbo; Li, Junbai

2014-11-12

214

Working with neural networks  

Microsoft Academic Search

As explanation of how neural networks operate is given. Programming of neural networks and regular computers is compared. Matching a neural network to an application is discussed. Designing and training a neural network is examined

D. Hammerstrom

1993-01-01

215

Foundations of Artificial Intelligence Neural Networks  

E-print Network

Foundations of Artificial Intelligence Neural Networks Building Artificial Brains #12;Background of observed examples (training data). #12;Neural Networks Objectives Show how the human brain works Introduction The Human Brain (How a neuron works) Building Artificial Neurons Network Architecture and Learning

Qu, Rong

216

Nuclear phosphatase PPM1G in cellular survival and neural development  

PubMed Central

Background PPM1G is a nuclear localized serine/threonine phosphatase implicated to be a regulator of chromatin remodeling, mRNA splicing and DNA damage. However, its in vivo function is unknown. Results Here we show that ppm1g expression is highly enriched in the central nervous system during mouse and zebrafish development. ppm1g?/? mice were embryonic lethal with incomplete penetrance after E12.5. Rostral defects, including neural tube and craniofacial defects were observed in ppm1g?/? embryos associated with increased cell death in the neural epithelium. In zebrafish, loss of ppm1g also led to neural defects with aberrant neural marker gene expression. Primary fibroblasts from ppm1g?/? embryos failed to grow without immortalization while immortalized ppm1g?/? fibroblasts had increased cell death upon oxidative and genotoxic stress when compared to wild type fibroblasts. Conclusion Our in vivo and in vitro studies revealed a critical role for PPM1G in normal development and cell survival. PMID:23723158

Foster, William H.; Langenbacher, Adam; Gao, Chen; Chen, Jaunian; Wang, Yibin

2014-01-01

217

Fast Pollen Tube Growth in Conospermum Species  

PubMed Central

Background and Aims An unusual form of pollen tube growth was observed for several Conospermum species (family Proteaceae). The rate of pollen tube growth, the number of tubes to emerge and the ultrastructure of these tubes are given here. • Methods Pollen was germinated in vitro in different sucrose concentrations and in the presence of calcium channel blockers, and tube emergence and growth were recorded on a VCR. Measurements were taken of the number of tubes to emerge and rate of tube emergence. Pollen behaviour in vivo was also observed. The ultrastructure of germinated and ungerminated pollen was observed using TEM. • Key Results After 10 s to 3 min in germination medium, up to three pollen tubes emerged and grew at rates of up to 55 µm s–1; the rate then slowed to around 2 µm s–1, 30 s after the initial growth spurt. Tubes were observed to grow in pulses, and the pulsed growth continued in the presence of calcium channel blockers. Optimal sugar concentration for pollen germination was 300 g L–1, in which up to 81 % of pollen grains showed fast germination. Germination and emergence of multiple tubes were observed in sucrose concentrations of 100–800 g L–1. The vegetative and generative nuclei moved into one of the tubes. Multiple tubes from a single grain were observed on the stigma. Under light microscopy, the cytoplasm in the tube showed a clear region at the tip. The ultrastructure of C. amoenum pollen showed a bilayered exine, with the intine being very thick at the pores, and elsewhere having large intrusions into the plasma membrane. The cytoplasm was dense with vesicles packed with inner tube cell wall material. Golgi apparatus producing secretory vesicles, and mitochondria were found throughout the tube. The tube wall was bilayered; both layers being fibrous and loosely packed. • Conclusions It is proposed that, for Conospermum, initial pollen tube wall constituents are manufactured and stored prior to pollen germination, and that tube extension occurs as described in the literature for other species, but at an exceptionally fast rate. PMID:14980970

STONE, L. M.; SEATON, K. A.; KUO, J.; McCOMB, J. A.

2004-01-01

218

Comparison of combitube, easy tube and tracheal tube for general anesthesia  

PubMed Central

Background & Aims: The Combitube® and EasyTube™ enable effective ventilation whether placed in the trachea or esophagus and can be used in prehospital settings, as well as in “Cannot Ventilate Cannot Intubate” situations in the operating room. Whether they can be continued to provide general anesthesia, if required, is not established. Thus the efficacy of Combitube and EasyTube was evaluated and compared with the tracheal tube for general anesthesia using controlled ventilation. Materials and Methods: Combitube, EasyTube and tracheal tubes were used in 30 patients each to secure the airway in a randomized controlled manner. Ventilatory parameters were measured along with hemodynamic variables, and characteristics related to device placement. Results: There was no significant difference in the various ventilatory parameters including minute ventilation requirement to maintain eucapnia amongst the three groups at any time point. There was no hypoxia or hypercarbia in any patient at any time. Placement of EasyTube was more difficult (P = 0.01) as compared with both Combitube and tracheal tube. EasyTube and Combitube resulted in higher incidence of minor trauma than with a tracheal tube (P = 0.00). Conclusion: Combitube and EasyTube may be continued for general anesthesia in patients undergoing elective nonlaparoscopic surgeries of moderate duration, if placed for airway maintenance. Given the secondary observations regarding placement characteristics of the airway devices, it, however cannot be concluded that the devices are a substitute for endotracheal tube for airway maintenance per se, unless specifically indicated

Sethi, Ashok Kumar; Desai, Manisha; Tyagi, Asha; Kumar, Surendra

2014-01-01

219

Brightness enhancement seen through a tube.  

PubMed

We report a fascinating phenomenon that emerges when a surface is viewed through a tube held close to one eye, with the other eye open. The disk-shaped area seen through the tube looks strikingly brighter and, when viewed on a textured background, also of higher spatial contrast than the same surface area viewed without a tube. The effect is reminiscent of a spotlight illuminating the area under consideration. We call this the 'tube effect'. The tube effect is one of the strongest contrast illusions known to us. It requires a matching luminance that is twice as high as the reference luminance seen through the tube. Brightness ratings increase linearly with the log of the background luminance. The effect (i) produces a dark afterimage, (ii) reverses in polarity with low ambient illumination, (iii) assumes the complementary colour of the illuminant, and (iv) persists with fully dilated pupils. Potential explanations include simultaneous contrast (due to the penumbra and dark inner walls of the tube) and veiling of the surround (due to local adaptation and a lower gain factor). PMID:21313947

Spillmann, Lothar; Hardy, Joe; Delahunt, Peter; Pinna, Baingio; Werner, John S

2010-01-01

220

Experiments with Vacuum Tubes  

Microsoft Academic Search

IN my letter published in the last number of NATURE I omitted to say that we have compared vacuum tubes without electrodes with a tube containing water. A tube was filled about nine-tenths full of water and then sealed hermetically. It was then applied to the prime conductor of the electric machine and electrified in the same way as the

J. T. Bottomley

1881-01-01

221

Microhole Tubing Bending Report  

DOE Data Explorer

A downhole tubing bending study was made and is reported herein. IT contains a report and 2 excel spreadsheets to calculate tubing bending and to estimate contact points of the tubing to the drilled hole wall (creating a new support point).

Ken Oglesby

222

Isolated Fallopian Tube Torsion in Adolescents  

PubMed Central

Background. Fallopian tube torsion is a rare cause of acute abdomen, occurring commonly in females of reproductive age. It lacks pathognomonic symptoms, signs, or imaging features, thus causing delay in surgical intervention. Case. We report two cases of isolated fallopian tube torsion in adolescent girls. In the first case a 19-year-old patient presented with acute pain in the left iliac region associated with episodes of vomiting for one day and mild tenderness on examination. Laparoscopy revealed left sided twisted fallopian tube associated with hemorrhagic cyst of ovary. The tube was untwisted and salvaged. In another case an 18-year-old virgin girl presented with similar complaints since one week, associated with mild tenderness in the lower abdomen and tender cystic mass on per rectal examination. On laparoscopy right twisted fallopian tube associated with a paratubal cyst was found. Salpingectomy was done as the tube was gangrenous. Conclusion. Fallopian tube torsion, though rare, should be considered in women of reproductive age with unilateral pelvic pain. Early diagnostic laparoscopy is important for an accurate diagnosis and could salvage the tube. PMID:24251052

Rajaram, S.; Bhaskaran, S.; Mehta, S.

2013-01-01

223

Telescoping tube assembly  

NASA Technical Reports Server (NTRS)

An extensible and retractable telescoping tube positions test devices that inspect large stationary objects. The tube has three dimensional adjustment capabilities and is vertically suspended from a frame. The tube sections are independently supported with each section comprising U-shaped housing secured to a thicker support plate. Guide mechanisms preferably mounted only to the thicker plates guide each tube section parallel to a reference axis with improved accuracy so that the position of the remote end of the telescoping tube is precisely known.

Sturm, Albert J. (Inventor); Marrinan, Thomas E. (Inventor)

1995-01-01

224

Illuminated Emission Tubes and Emission Tube Apparatus  

NSDL National Science Digital Library

This is an image of illuminated emission tubes with the high voltage apparatus that causes the gas to become excited. Elements represented include: hydrogen, nitrogen, chlorine, mercury, and neon. This image is not labeled.

Ward, Charles

2003-01-16

225

OPTIMAL DESIGN AND ASSESSMENT OF HIGH PERFORMANCE MICRO BARE-TUBE HEAT EXCHANGERS  

Microsoft Academic Search

An optimal design methodology is proposed for micro bare-tube heat exchangers. A simulated annealing method is employed with a trained neural network representing the heat transfer and pressure drop characteristics of a specified tube bank. A commercial CFD code, FLUENT5, is used to obtain the heat transfer and pressure drop data sets for in-line tube bundles, which are then used

Nobuhide Kasagi; Yuji Suzuki; Naoki Shikazono; Tomohisa Oku

2003-01-01

226

Differentiation state determines neural effects on microvascular endothelial cells  

SciTech Connect

Growing evidence indicates that nerves and capillaries interact paracrinely in uninjured skin and cutaneous wounds. Although mature neurons are the predominant neural cell in the skin, neural progenitor cells have also been detected in uninjured adult skin. The aim of this study was to characterize differential paracrine effects of neural progenitor cells and mature sensory neurons on dermal microvascular endothelial cells. Our results suggest that neural progenitor cells and mature sensory neurons have unique secretory profiles and distinct effects on dermal microvascular endothelial cell proliferation, migration, and nitric oxide production. Neural progenitor cells and dorsal root ganglion neurons secrete different proteins related to angiogenesis. Specific to neural progenitor cells were dipeptidyl peptidase-4, IGFBP-2, pentraxin-3, serpin f1, TIMP-1, TIMP-4 and VEGF. In contrast, endostatin, FGF-1, MCP-1 and thrombospondin-2 were specific to dorsal root ganglion neurons. Microvascular endothelial cell proliferation was inhibited by dorsal root ganglion neurons but unaffected by neural progenitor cells. In contrast, microvascular endothelial cell migration in a scratch wound assay was inhibited by neural progenitor cells and unaffected by dorsal root ganglion neurons. In addition, nitric oxide production by microvascular endothelial cells was increased by dorsal root ganglion neurons but unaffected by neural progenitor cells. -- Highlights: Black-Right-Pointing-Pointer Dorsal root ganglion neurons, not neural progenitor cells, regulate microvascular endothelial cell proliferation. Black-Right-Pointing-Pointer Neural progenitor cells, not dorsal root ganglion neurons, regulate microvascular endothelial cell migration. Black-Right-Pointing-Pointer Neural progenitor cells and dorsal root ganglion neurons do not effect microvascular endothelial tube formation. Black-Right-Pointing-Pointer Dorsal root ganglion neurons, not neural progenitor cells, regulate microvascular endothelial cell production of nitric oxide. Black-Right-Pointing-Pointer Neural progenitor cells and dorsal root ganglion neurons have different secretory profiles for angiogenic mediators.

Muffley, Lara A., E-mail: muffley@u.washington.edu [University of Washington, Campus Box 359796, 300 9th Avenue, Seattle, WA 98104 (United States); Pan, Shin-Chen, E-mail: pansc@mail.ncku.edu.tw [University of Washington, Campus Box 359796, 300 9th Avenue, Seattle, WA 98104 (United States)] [University of Washington, Campus Box 359796, 300 9th Avenue, Seattle, WA 98104 (United States); Smith, Andria N., E-mail: gnaunderwater@gmail.com [University of Washington, Campus Box 359796, 300 9th Avenue, Seattle, WA 98104 (United States); Ga, Maricar, E-mail: marga16@uw.edu [University of Washington, Campus Box 359796, 300 9th Avenue, Seattle, WA 98104 (United States)] [University of Washington, Campus Box 359796, 300 9th Avenue, Seattle, WA 98104 (United States); Hocking, Anne M., E-mail: ahocking@u.washington.edu [University of Washington, Campus Box 359796, 300 9th Avenue, Seattle, WA 98104 (United States); Gibran, Nicole S., E-mail: nicoleg@u.washington.edu [University of Washington, Campus Box 359796, 300 9th Avenue, Seattle, WA 98104 (United States)

2012-10-01

227

Pediatric cuffed endotracheal tubes  

PubMed Central

Endotracheal intubation in children is usually performed utilizing uncuffed endotracheal tubes for conduct of anesthesia as well as for prolonged ventilation in critical care units. However, uncuffed tubes may require multiple changes to avoid excessive air leak, with subsequent environmental pollution making the technique uneconomical. In addition, monitoring of ventilatory parameters, exhaled volumes, and end-expiratory gases may be unreliable. All these problems can be avoided by use of cuffed endotracheal tubes. Besides, cuffed endotracheal tubes may be of advantage in special situations like laparoscopic surgery and in surgical conditions at risk of aspiration. Magnetic resonance imaging (MRI) scans in children have found the narrowest portion of larynx at rima glottides. Cuffed endotracheal tubes, therefore, will form a complete seal with low cuff pressure of <15 cm H2O without any increase in airway complications. Till recently, the use of cuffed endotracheal tubes was limited by variations in the tube design marketed by different manufacturers. The introduction of a new cuffed endotracheal tube in the market with improved tracheal sealing characteristics may encourage increased safe use of these tubes in clinical practice. A literature search using search words "cuffed endotracheal tube" and "children" from 1980 to January 2012 in PUBMED was conducted. Based on the search, the advantages and potential benefits of cuffed ETT are reviewed in this article. PMID:23492803

Bhardwaj, Neerja

2013-01-01

228

Conduction cooled tube supports  

DOEpatents

In boilers, process tubes are suspended by means of support studs that are in thermal contact with and attached to the metal roof casing of the boiler and the upper bend portions of the process tubes. The support studs are sufficiently short that when the boiler is in use, the support studs are cooled by conduction of heat to the process tubes and the roof casing thereby maintaining the temperature of the stud so that it does not exceed 1400.degree. F.

Worley, Arthur C. (Mt. Tabor, NJ); Becht, IV, Charles (Morristown, NJ)

1984-01-01

229

Wound tube heat exchanger  

DOEpatents

What is disclosed is a wound tube heat exchanger in which a plurality of tubes having flattened areas are held contiguous adjacent flattened areas of tubes by a plurality of windings to give a double walled heat exchanger. The plurality of windings serve as a plurality of effective force vectors holding the conduits contiguous heat conducting walls of another conduit and result in highly efficient heat transfer. The resulting heat exchange bundle is economical and can be coiled into the desired shape. Also disclosed are specific embodiments such as the one in which the tubes are expanded against their windings after being coiled to insure highly efficient heat transfer.

Ecker, Amir L. (Duncanville, TX)

1983-01-01

230

In vitro differentiation of transplantable neural precursors from human embryonic stem cells  

Microsoft Academic Search

The remarkable developmental potential and replicative capacity of human embryonic stem (ES) cells promise an almost unlimited supply of specific cell types for transplantation therapies. Here we describe the in vitro differentiation, enrichment, and transplantation of neural precursor cells from human ES cells. Upon aggregation to embryoid bodies, differentiating ES cells formed large numbers of neural tube–like structures in the

Marius Wernig; Ian D. Duncan; James A. Thomson; Su-Chun Zhang; Oliver Brüstle

2001-01-01

231

iBioSeminar: Role of the Neural Crest in Vertebrate Development and Evolution  

NSDL National Science Digital Library

The neural crest (NC) is a transitory structure of the Vertebrate embryo. It forms when the neural tube closes through the epithelio- mesenchymal transition of the cells in the joining neural folds. Its constitutive cells are endowed of migratory capacities and are highly pluripotent. NC cells migrate in the developing embryo along definite pathways, at precise periods of time during embryogenesis and settle in elected sites in the body where they develop into a large of cell types.

Nicole Le Douarin (CNRS and Collège de France, Paris;)

2008-03-01

232

A gene regulatory network orchestrates neural crest formation.  

PubMed

The neural crest is a multipotent, migratory cell population that is unique to vertebrate embryos and gives rise to many derivatives, ranging from the peripheral nervous system to the craniofacial skeleton and pigment cells. A multimodule gene regulatory network mediates the complex process of neural crest formation, which involves the early induction and maintenance of the precursor pool, emigration of the neural crest progenitors from the neural tube via an epithelial to mesenchymal transition, migration of progenitor cells along distinct pathways and overt differentiation into diverse cell types. Here, we review our current understanding of these processes and discuss the molecular players that are involved in the neural crest gene regulatory network. PMID:18523435

Sauka-Spengler, Tatjana; Bronner-Fraser, Marianne

2008-07-01

233

Steam generator tube failures  

SciTech Connect

A review and summary of the available information on steam generator tubing failures and the impact of these failures on plant safety is presented. The following topics are covered: pressurized water reactor (PWR), Canadian deuterium uranium (CANDU) reactor, and Russian water moderated, water cooled energy reactor (VVER) steam generator degradation, PWR steam generator tube ruptures, the thermal-hydraulic response of a PWR plant with a faulted steam generator, the risk significance of steam generator tube rupture accidents, tubing inspection requirements and fitness-for-service criteria in various countries, and defect detection reliability and sizing accuracy. A significant number of steam generator tubes are defective and are removed from service or repaired each year. This wide spread damage has been caused by many diverse degradation mechanisms, some of which are difficult to detect and predict. In addition, spontaneous tube ruptures have occurred at the rate of about one every 2 years over the last 20 years, and incipient tube ruptures (tube failures usually identified with leak detection monitors just before rupture) have been occurring at the rate of about one per year. These ruptures have caused complex plant transients which have not always been easy for the reactor operators to control. Our analysis shows that if more than 15 tubes rupture during a main steam line break, the system response could lead to core melting. Although spontaneous and induced steam generator tube ruptures are small contributors to the total core damage frequency calculated in probabilistic risk assessments, they are risk significant because the radionuclides are likely to bypass the reactor containment building. The frequency of steam generator tube ruptures can be significantly reduced through appropriate and timely inspections and repairs or removal from service.

MacDonald, P.E.; Shah, V.N.; Ward, L.W.; Ellison, P.G.

1996-04-01

234

Impact of Tympanostomy Tubes on Child Quality of Life  

Microsoft Academic Search

Background: The objective benefits of tympanostomy tubes for otitis media are well established, but the sub- jective impact of surgery on child quality of life (QOL) has not been systematically studied. Objectives: To determine the subjective impact of tym- panostomy tubes on child QOL, and to compare the vari- ability in QOL before surgery with that observed after surgery. Patients:

Richard M. Rosenfeld; Mahesh H. Bhaya; Charles M. Bower; Patrick E. Brookhouser; Margaretha L. Casselbrant; Kenneth H. Chan; Michael J. Cunningham; Craig S. Derkay; Steven D. Gray; Scott C. Manning; Anna H. Messner; Richard J. H. Smith

2000-01-01

235

Welding Tubes In Place  

NASA Technical Reports Server (NTRS)

Special welding equipment joins metal tubes that carry pressurized cyrogenic fluids. Equipment small enough to be used in confined spaces in which such tubes often mounted. Welded joints lighter in weight and more leak-proof than joints made with mechanical fittings.

Meredith, R.

1984-01-01

236

Cosmic Microwave Background Tutorials  

NSDL National Science Digital Library

Probing whether space is curved or flat, cosmologists have been searching for clues in ripples in the universe's microwave background left from the big bang. These tutorials explain the cosmic microwave background for neophytes, as well as more advanced readers.

Hu, Wayne

2003-10-10

237

Enhanced tubes for steam condensers  

Microsoft Academic Search

Electric utility steam condensers typically use plain tubes made of titanium, stainless steel, or copper alloys. Approximately two-thirds of the total thermal resistance is on the water side of the plain tube. This program seeks to conceive and develop a tube geometry that has special enhancement geometries on the tube (water) side and the steam (shell) side. This enhanced'' tube

R. L. Webb; L. Chamra; H. Jaber

1992-01-01

238

Building Background Knowledge  

ERIC Educational Resources Information Center

This article make a case for the importance of background knowledge in children's comprehension. It suggests that differences in background knowledge may account for differences in understanding text for low- and middle-income children. It then describes strategies for building background knowledge in the age of common core standards.

Neuman, Susan B.; Kaefer, Tanya; Pinkham, Ashley

2014-01-01

239

Nonlinear neural controller with neural Smith predictor  

Microsoft Academic Search

This paper proposes a new nonlinear neural controller with a neural Smith predictor for time-delay compensation of nonlinear\\u000a processes. Similar to the conventional linear PID controller, the nonlinear neural network based controller uses the system\\u000a error, the integral of the system error, and the derivative of the system error as its inputs but the mapping from the inputs\\u000a to the

Yonghong Tan; Achiel Van Cauwenberghe

1994-01-01

240

Mathematical modeling supports substantial mouse neural progenitor cell death  

Microsoft Academic Search

BACKGROUND: Existing quantitative models of mouse cerebral cortical development are not fully constrained by experimental data. RESULTS: Here, we use simple difference equations to model neural progenitor cell fate decisions, incorporating intermediate progenitor cells and initially low rates of neural progenitor cell death. Also, we conduct a sensitivity analysis to investigate possible uncertainty in the fraction of cells that divide,

Michael J McConnell; Hugh R MacMillan; Jerold Chun

2009-01-01

241

NEI You Tube Videos: Amblyopia  

MedlinePLUS

Home » NEI YouTube Videos » Amblyopia NEI YouTube Videos: Amblyopia NEI YouTube Home | Age-Related Macular Degeneration | Amblyopia | Animations | Blindness | Cataracts | Convergence Insufficiency | Diabetic Eye Disease | Dilated Eye Exam | Dry Eye | For ...

242

Artificial-neural-network-based failure detection and isolation  

NASA Astrophysics Data System (ADS)

This paper presents the design of a systematic failure detection and isolation system that uses the concept of failure sensitive variables (FSV) and artificial neural networks (ANN). The proposed approach was applied to tube leak detection in a utility boiler system. Results of the experimental testing are presented in the paper.

Sadok, Mokhtar; Gharsalli, Imed; Alouani, Ali T.

1998-03-01

243

Parallel Consensual Neural Networks  

NASA Technical Reports Server (NTRS)

A new neural network architecture is proposed and applied in classification of remote sensing/geographic data from multiple sources. The new architecture is called the parallel consensual neural network and its relation to hierarchical and ensemble neural networks is discussed. The parallel consensual neural network architecture is based on statistical consensus theory. The input data are transformed several times and the different transformed data are applied as if they were independent inputs and are classified using stage neural networks. Finally, the outputs from the stage networks are then weighted and combined to make a decision. Experimental results based on remote sensing data and geographic data are given. The performance of the consensual neural network architecture is compared to that of a two-layer (one hidden layer) conjugate-gradient backpropagation neural network. The results with the proposed neural network architecture compare favorably in terms of classification accuracy to the backpropagation method.

Benediktsson, J. A.; Sveinsson, J. R.; Ersoy, O. K.; Swain, P. H.

1993-01-01

244

Isolated Fallopian Tube Torsion  

PubMed Central

Isolated torsion of the Fallopian tube is a rare gynecological cause of acute lower abdominal pain, and diagnosis is difficult. There are no pathognomonic symptoms; clinical, imaging, or laboratory findings. A preoperative ultrasound showing tubular adnexal masses of heterogeneous echogenicity with cystic component is often present. Diagnosis can rarely be made before operation, and laparoscopy is necessary to establish the diagnosis. Unfortunately, surgery often is performed too late for tube conservation. Isolated Fallopian tube torsion should be suspected in case of acute pelvic pain, and prompt intervention is necessary. PMID:23984132

Kardakis, S.; Barranca, A.; Vitelli, A.; Amore, I.; Trento, F.; Caccia, G.

2013-01-01

245

Optical Neural Interfaces  

PubMed Central

Genetically encoded optical actuators and indicators have changed the landscape of neuroscience, enabling targetable control and readout of specific components of intact neural circuits in behaving animals. Here, we review the development of optical neural interfaces, focusing on hardware designed for optical control of neural activity, integrated optical control and electrical readout, and optical readout of population and single-cell neural activity in freely moving mammals. PMID:25014785

Warden, Melissa R.; Cardin, Jessica A.; Deisseroth, Karl

2014-01-01

246

Amphioxus and lamprey AP-2 genes: implications for neural crest evolution and migration patterns  

NASA Technical Reports Server (NTRS)

The neural crest is a uniquely vertebrate cell type present in the most basal vertebrates, but not in cephalochordates. We have studied differences in regulation of the neural crest marker AP-2 across two evolutionary transitions: invertebrate to vertebrate, and agnathan to gnathostome. Isolation and comparison of amphioxus, lamprey and axolotl AP-2 reveals its extensive expansion in the vertebrate dorsal neural tube and pharyngeal arches, implying co-option of AP-2 genes by neural crest cells early in vertebrate evolution. Expression in non-neural ectoderm is a conserved feature in amphioxus and vertebrates, suggesting an ancient role for AP-2 genes in this tissue. There is also common expression in subsets of ventrolateral neurons in the anterior neural tube, consistent with a primitive role in brain development. Comparison of AP-2 expression in axolotl and lamprey suggests an elaboration of cranial neural crest patterning in gnathostomes. However, migration of AP-2-expressing neural crest cells medial to the pharyngeal arch mesoderm appears to be a primitive feature retained in all vertebrates. Because AP-2 has essential roles in cranial neural crest differentiation and proliferation, the co-option of AP-2 by neural crest cells in the vertebrate lineage was a potentially crucial event in vertebrate evolution.

Meulemans, Daniel; Bronner-Fraser, Marianne

2002-01-01

247

Genetically engineered neural transmission  

Microsoft Academic Search

Neural transmission is a communication between neurons and target cells, resulting in behavioral and physiological changes. Defective or altered neural transmission is thought to occur in neuropsychiatric and neurodegenerative illnesses. To probe the biological consequences of defective or altered neural transmission, various genetically engineered transgenic mouse models have been developed, together with conventional pharmacological manipulation. Via genetic manipulation, we are

J H Son; T H Joh

1997-01-01

248

Computational Verb Neural Networks  

Microsoft Academic Search

When any attribute value in a conventional neural network is verbified, the result is a computational verb neural network(VNN). We can verbify inputs, outputs, biases, weights and many other attributes of conventional neural networks. In this paper, we reported two types of VNNs. The first one consists of computational verb inputs and numerical output. The second one consists of computational

Tao Yang

2007-01-01

249

Nested Neural Networks  

NASA Technical Reports Server (NTRS)

Report presents analysis of nested neural networks, consisting of interconnected subnetworks. Analysis based on simplified mathematical models more appropriate for artificial electronic neural networks, partly applicable to biological neural networks. Nested structure allows for retrieval of individual subpatterns. Requires fewer wires and connection devices than fully connected networks, and allows for local reconstruction of damaged subnetworks without rewiring entire network.

Baram, Yoram

1992-01-01

250

Parallel Consensual Neural Networks  

Microsoft Academic Search

Optimized combination, regularization, and pruning is proposed for the Parallel Consensual Neural Networks (PC- NNs) which is a neural network architecture based on the consensus of a collection of stage neural networks trained on the same input data with dieren t representations. Here, a regularization scheme is presented for the PCNN and in training a regularized cost function is minimized.

J. A. Benediktsson; J. Larsen; J. R. Sveinsson; L. K. Hansen

251

Patterns in neural processing  

NASA Astrophysics Data System (ADS)

In this paper we propose a model for neural processing that addresses both the evolutionary and functional aspects of neural systems that are observed in nature, from the simplest neural collections to dense large scale associations such as human brains. We propose both an architecture and a process in which these components interact to create the emergent behavior that we define as the 'mind'.

Engineer, Sunu

2012-03-01

252

Cognitive neural prosthetics  

E-print Network

Magazine R77 Primer Cognitive neural prosthetics B. Pesaran1, S. Musallam2 and R.A. Andersen2 neural prosthetics seek to help paralyzed patients by recording their thoughts directly from the brain. These prosthetics `read-out' signals by recording neural activity and are different from prosthetics for the deaf

Andersen, Richard

253

Integrated structure vacuum tube  

NASA Technical Reports Server (NTRS)

High efficiency, multi-dimensional thin film vacuum tubes suitable for use in high temperature, high radiation environments are described. The tubes are fabricated by placing thin film electrode members in selected arrays on facing interior wall surfaces of an alumina substrate envelope. Cathode members are formed using thin films of triple carbonate. The photoresist used in photolithography aids in activation of the cathodes by carbonizing and reacting with the reduced carbonates when heated in vacuum during forming. The finely powdered triple carbonate is mixed with the photoresist used to delineate the cathode locations in the conventional solid state photolithographic manner. Anode and grid members are formed using thin films of refractory metal. Electron flow in the tubes is between grid elements from cathode to anode as in a conventional three-dimensional tube.

Dimeff, J.; Kerwin, W. J. (inventors)

1976-01-01

254

Neural tube defects in New South Wales, Australia  

PubMed Central

Cases of spina bifida cystica, encephalocele, and anencephaly occurring over a 9-year period, 1965 to 1973, in New South Wales, Australia, were identified. A low frequency of 1·1 for spina bifida and encephalocele (SB) and 0·9 for anencephaly (A) was found. Secular trends parallel to those observed in the northern hemisphere were noted. Detailed analysis of 1575 cases showed an excess of births in spring, corresponding with conception in the summer months, after correction for shorter gestation in anencephalus, which varies from the peak of spring conceptions observed in British studies. An excess of female cases for each abnormality and a social class effect with a deficit of cases in classes I and II and an excess in classes IV and V and ex-nuptial births were apparent. The first birth rank for younger mothers did not show a significantly increased risk; however, the effect of high birth rank and older maternal age was more significant. Migration studies showed that in migrating from areas of high incidence these parents maintain a higher risk than the Australian population. The highest risk group was that in which both parents were born in the UK, and the next highest that in which an English-born mother was married to an Australian father. Mothers from Malta, and either or both parents from Lebanon, Egypt, and Austria were also at high risk. Part-aboriginal children had a higher risk rate for ASB than white Australian children. The proportion of older sibs affected was 4·12% of sibs of both sexes of an index case of spina bifida, and 3·19% of an index case of anencephaly. The abnormalities alternate or recur in families. An increased perinatal mortality rate in sibs was shown. Twin studies showed a higher concordance rate for monochorionic pairs. A sequential interaction in an excess of opposite sex sib before an index case was apparent. The results of this study support a multifactorial aetiology for ASB resulting from genetic environmental interaction. New South Wales is the eastern coastal state of Australia, with an area of 309 433 square miles and a population of 4 640 800 at the 1971 Census. The continent is geographically isolated with a large migrant population, seasonal reversal, and a hot climate. PMID:739521

Field, Barbara

1978-01-01

255

Cardiac neural crest contributes to cardiomyogenesis in zebrafish.  

PubMed

In birds and mammals, cardiac neural crest is essential for heart development and contributes to conotruncal cushion formation and outflow tract septation. The zebrafish prototypical heart lacks outflow tract septation, raising the question of whether cardiac neural crest exists in zebrafish. Here, results from three distinct lineage-labeling approaches identify zebrafish cardiac neural crest cells and indicate that these cells have the ability to generate MF20-positive muscle cells in the myocardium of the major chambers during development. Fate-mapping demonstrates that cardiac neural crest cells originate both from neural tube regions analogous to those found in birds, as well as from a novel region rostral to the otic vesicle. In contrast to other vertebrates, cardiac neural crest invades the myocardium in all segments of the heart, including outflow tract, atrium, atrioventricular junction, and ventricle in zebrafish. Three distinct groups of premigratory neural crest along the rostrocaudal axis have different propensities to contribute to different segments in the heart and are correspondingly marked by unique combinations of gene expression patterns. Zebrafish will serve as a model for understanding interactions between cardiac neural crest and cardiovascular development. PMID:12710962

Sato, Mariko; Yost, H Joseph

2003-05-01

256

Tubing crimping pliers  

DOEpatents

The disclosure relates to pliers and more particularly to pliers for crimping two or more pieces of copper tubing together prior to their being permanently joined by brazing, soldering or the like. A die containing spring-loaded pins rotates within a cammed ring in the head of the pliers. As the die rotates, the pins force a crimp on tubing held within the pliers.

Lindholm, G.T.

1981-02-27

257

TeacherTube  

NSDL National Science Digital Library

TeacherTube is a professionally vetted site that allows educators to share informative videos with others around the world. The essential interface resembles that of YouTube, and visitors can search for videos by keyword, or they can also look for audio-only resources or helpful documents. Visitors can find a wide variety here including a teacher rapping about perimeters, discussion of the Lenape tribe, and a talk with Benjamin Franklin. This particular resource is compatible with all operating systems.

258

Transcriptional and epigenetic regulation of neural crest induction during neurulation.  

PubMed

Neurulation is one of the many important events in mammalian development. It is the stage of organogenesis in vertebrate embryos during which the neural tube is transformed into the primitive structures that will later develop into the central nervous system. Recent transcriptome analysis during neurulation and early organogenesis in humans and mice has identified the global dynamics of gene expression changes across developmental time. This has revealed a richer understanding of gene regulation and provides hints at the transcriptional regulatory networks that underlie these processes. Similarly, epigenome analysis, which collectively constitutes histone modifications, transcription factor binding, and other structural features associated with gene regulation, has given a renewed appreciation to the subtle mechanisms involving the process of neurulation. More specifically, the histone demethylases KDM4A and KDM6B have recently been shown to be key histone H3K4 and H3K27 modifiers that regulate neural crest specification and neural tube closure. Additionally, miRNAs have recently been shown to influence transcription of genes directly or by altering the levels of epigenetic modifiers and thus regulate gene expression. This mini review briefly summarizes the literature, highlighting the transcriptional and epigenetic regulation of key genes involved in neural crest induction and neural crest specification by transcription factors and miRNAs. Understanding how these mechanisms work individually and in clusters will shed light on pathways in the context of diseases associated with neural crest cell derivatives such as melanoma, cardiovascular defects and neuronal craniofacial defects. PMID:24051984

Mayanil, Chandra S

2013-01-01

259

Background Check Presentation  

E-print Network

·July 1, 2012 ­ The UNM Division of Human Resources engaged in an RFP process to identify a NationalBackground Check Presentation Kim Herron-Singleton, Recruitment & UNMTemps Services Manager #12 check website to include BC and FP processes and resources · New background check request e-mail box

New Mexico, University of

260

Dynamic tube/support interaction in heat exchanger tubes  

SciTech Connect

The supports for heat exchanger tubes are usually plates with drilled holes; other types of supports also have been used. To facilitate manufacture and to allow for thermal expansion of the tubes, small clearances are used between tubes and tube supports. The dynamics of tube/support interaction in heat exchangers is fairly complicated. Understanding tube dynamics and its effects is important for heat exchangers. This paper summarizes the current state of the art on this subject and to identify future research needs. Specifically, the following topics are discussed: dynamics of loosely supported tubes, tube/support gap dynamics, tube response in flow, tube damage and wear, design considerations, and future research needs. 55 refs., 1 fig.

Chen, S.S.

1991-01-01

261

PRESSURE TUBE-CALANDRIA TUBE THERMAL CONTACT CONDUCTANCE  

Microsoft Academic Search

CANDU reactors are of the heavy water moderated, pressure tube type. The core consists of several hundred horizontal fuel channels surrounded by a heavy water moderator. Fuel channels consist of a Zircaloy-2.5%Nb pressure tube enclosed within a Zircaloy-2 calandria tube. There is an annulus gas gap between the pressure tube and the calandria tube. Under extreme accident conditions such as

Adam Cziraky

2009-01-01

262

Microscale shock tube  

NASA Astrophysics Data System (ADS)

This project aims at the simulation, design, fabrication and testing of a microscale shock tube. A step by step procedure has been followed to develop the different components of the microscale shock tube and then combine them together to realize the final device. The document reports on the numerical simulation of flows in a microscale shock tube, the experimental study of gas flow in microchannels, the design, microfabrication, and the test of a microscale shock tube. In the first step, a one-dimensional numerical model for simulation of transport effects at small-scale, appeared in low Reynolds number shock tubes is developed. The conservation equations have been integrated in the lateral directions and three-dimensional effects have been introduced as carefully controlled sources of mass, momentum and energy, into the one-dimensional model. The unsteady flow of gas behind the shock wave is reduced to a quasi-steady laminar flow solution, similar to the Blasius solution. The resulting one-dimensional equations are solved numerically and the simulations are performed for previously reported low Reynolds number shock tube experiments. Good agreement between the shock structure simulation and the attenuation due to the boundary layers has been observed. The simulation for predicting the performance of a microscale shock tube shows the large attenuation of shock wave at low pressure ratios. In the next step the steady flow inside microchannels has been experimentally studied. A set of microchannels with different geometries were fabricated. These microchannels have been used to measure the pressure drop as a function of flow rate in a steady compressible flow. The results of the experiments confirm that the flow inside the microscale shock tube follows the laminar model over the experiment's range of Knudsen number. The microscale shock tube is fabricated by deposition and patterning of different thin layers of selected materials on the silicon substrate. The direct sensing piezoelectric sensors were fabricated and integrated with microchannels patterned on the substrate. The channels were then covered with another substrate. This shock tube is 2000 mum long and it has a 2000 mum wide and 17 mum high rectangular cross section equipped with 5 piezoelectric sensors along the tube. The packaged microscale shock tube was installed in an ordinary shock tube and shock waves with different Mach numbers were directed into the channel. A one-dimensional inviscid calculation as well as viscous simulation using the one-dimensional model have also been performed for the above mentioned geometry. The comparison of results with those of the same geometry for an inviscid flow shows the considerable attenuation of shock strength and deceleration of the shock wave for both incident and reflected shock waves in the channel. The comparison of results with numerically generated results with the one-dimensional model presents good agreement for incident shock waves. Keywords. Shock wave, Shock tube, MEMS, Microfluidic, Piezoelectric sensor, Microchannel, Transport phenomena.

Mirshekari, Gholamreza

263

Background stratospheric aerosol layer  

SciTech Connect

Balloonborne aerosol particle counter measurements are used in studying the stratospheric sulfate layer at Laramie, Wyoming, during 1978 and 1979, a 2-year volcanically quiescent period in which the layer appears to have been in a near equilibrium background state. Subtracting the background aerosol concentration from data obtained during an earlier volcanically active period indicates that the actual decay rate of volcanic aerosol is over 30% faster than one would obtain without this correction. At background, the aerosol size distribution is found to remain remarkably constant between the tropopause and an altitude of approx.25 km, with a sudden transition to a distribution dominated by smaller particles above this altitude. The observations, in some respects, compare favorably with equilibrium one-dimensional stratospheric aerosol models and thus to some extent support the concept of relatively inert tropospheric sulfurous gases, such as carbonyl sulfide and carbon disulfide, as the main background stratospheric aerosol sulfur source. Models which incorporate sulfur chemistry are apparently not able to predict the observed variation of particle size with altitude. The 2-year background period is not long enough in itself to establish long-term trends. The eruption of Mt. St. Helens in May 1980 has considerably disrupted the background stratospheric aerosol which will probably not recover for several years. A comparison of the 1978--79 observations with Junge's original measurements made some 20 years earlier, also during a period void of volcanic perturbations, does not preclude a long-term increase in the background stratospheric aerosol level.

Hofmann, D.J.; Rosen, J.M.

1981-01-01

264

RESEARCH Open Access Acupuncture modulates temporal neural  

E-print Network

RESEARCH Open Access Acupuncture modulates temporal neural responses in wide brain networks Background: Accumulating neuroimaging studies in humans have shown that acupuncture can modulate a widely, a striking feature of acupuncture-induced analgesia is found to be associated with its long-last effect

Tian, Jie

265

Perception of Speech in Noise: Neural Correlates  

Microsoft Academic Search

The presence of irrelevant auditory information (other talkers, environmental noises) presents a major challenge to listening to speech. The fundamental frequency (F0) of the target speaker is thought to provide an important cue for the extraction of the speaker's voice from background noise, but little is known about the relationship between speech-in-noise (SIN) perceptual ability and neural encoding of the

Judy H. Song; Erika Skoe; Karen Banai; Nina Kraus

2011-01-01

266

Diffuse Background Radiation  

E-print Network

A new determination of the upper limit to the cosmic diffuse background radiation, at ~110 nm, of 300 photons s-1 cm-2 sr-1 nm-1, is placed in the context of diffuse background measurements across the entire electromagnetic spectrum, including new optical, infrared, visible, and gamma-ray background measurements. The possibility that observed excess diffuse visible radiation is due to redshifted cosmological Lyman alpha recomination radiation is explored. Also, a new standard of units for the display of spectra is advocated.

Richard C. Henry

1999-03-18

267

Gas fired radiant tube heater  

SciTech Connect

This patent describes a fuel fired radiant tube burner. It comprises a first generally cylindrical heat tube; a second cylindrical heat transfer tube concentrically disposed within the heat tube and defining a longitudinally-extending annular exhaust gas passageway therebetween; a third cylindrical burner tube concentrically disposed within the second tube and defining a longitudinally-extending annular heat distribution passageway therebetween; burner means within the third tube at one axial end of the third tube and sealed with respect thereto for igniting, combusting and burning a source of fuel and air to form heated products of combustion within the third tube casing; plate means closing the first, second and third tube axial end openings which are adjacent one another, the plate means effective to cause the products of combustion to enter the heat distribution passageway; and aperture and opening means associated with the heat distribution passageway for developing a substantially laminar flow of the products of combustion within the heat distribution passageway.

Hemsath, K.H.

1992-01-21

268

The Cosmic Background Radiation  

E-print Network

We summarise the current status of cosmic microwave background spectrum and anisotropy measurements, and their theoretical interpretation. This is the update of the mini-review for the 1997 web-version of the Review of Particle Properties.

George Smoot; Douglas Scott

1997-11-08

269

The GLAST Background Model  

SciTech Connect

In order to estimate the ability of the GLAST/LAT to reject unwanted background of charged particles, optimize the on-board processing, size the required telemetry and optimize the GLAST orbit, we developed a detailed model of the background particles that would affect the LAT. In addition to the well-known components of the cosmic radiation, we included splash and reentrant components of protons, electrons (e+ and e-) from 10 MeV and beyond as well as the albedo gamma rays produced by cosmic ray interactions with the atmosphere. We made estimates of the irreducible background components produced by positrons and hadrons interacting in the multilayered micrometeorite shield and spacecraft surrounding the LAT and note that because the orbital debris has increased, the shielding required and hence the background are larger than were present in EGRET. Improvements to the model are currently being made to include the east-west effect.

Ormes, J. F. [University of Denver (United States); Atwood, W. [University of California at Santa Cruz (United States); Burnett, T. [University of Washington (United States); Grove, E. [Naval Research Laboratory (United States); Longo, F. [Instituto Nazionale di Fisica Nucleare (INFN)-Pisa (Italy); McEnery, J.; Ritz, S. [NASA Goddard Space Flight Center (United States); Mizuno, T. [Hiroshima University (Japan)

2007-07-12

270

The GLAST Background Model  

SciTech Connect

In order to estimate the ability of the GLAST/LAT to reject unwanted background of charged particles, optimize the on-board processing, size the required telemetry and optimize the GLAST orbit, we developed a detailed model of the background particles that would affect the LAT. In addition to the well-known components of the cosmic radiation, we included splash and reentrant components of protons, electrons (e+ and e-) from 10 MeV and beyond as well as the albedo gamma rays produced by cosmic ray interactions with the atmosphere. We made estimates of the irreducible background components produced by positrons and hadrons interacting in the multilayered micrometeorite shield and spacecraft surrounding the LAT and note that because the orbital debris has increased, the shielding required and hence the background are larger than were present in EGRET. Improvements to the model are currently being made to include the east-west effect.

Ormes, J.F.; /Denver U.; Atwood, W.; /UC, Santa Cruz; Burnett, T.; /Washington U., Seattle; Grove, E.; /Naval Research Lab, Wash., D.C.; Longo, F.; /INFN, Pisa; McEnery, J.; /NASA, Goddard; Mizuno, T.; /Hiroshima U.; Ritz, S.; /NASA, Goddard

2007-10-17

271

Introduction 1 Background 1  

E-print Network

squirrel (Sciurus carolinensis). The grey squirrel was introduced to Britain in the late 19 th century populations in Northern Ireland. Background The red squirrel (Sciurus vulgaris) was once ubiquitous

272

Collapse of flux tubes  

SciTech Connect

Flux tubes are one of the most elementary systems of quantum chromodynamics. They are the idealized configurations of heavy quark-antiquark pairs at large separations L such that the region between can be assumed to possess axial-cylindrical symmetry. They play a central role in lattice QCD calculations and in models of QCD, as well as in the phenomenology of QCD processes. Lattice QCD calculations on flux tubes are generally limited to the quenched approximation (no massless quarks) and allow for a separation of the heavy quark-antiquark of only about 1 fm. Static flux tubes are unstable at separations greater than 1 fm, since the energy required to stretch the tube by 1 fm is about 1 GeV and that is about the energy difference between a quarkonium, Q{bar Q}, and a pair of heavy-light mesons, Q{bar q} + {bar Q}q. Lattice calculations without light quarks cannot explore this instability. The author then reviews work on efforts to explore the creation of light quark pairs as a mechanism for flux tube breaking.

Wilets, L.

1993-12-31

273

Background Studies for EXIST  

NASA Technical Reports Server (NTRS)

We present results from a study of the trapped proton and electron background for several orbital inclinations and altitudes. This study includes time dependent effects. In addition we describe a 3 component cosmic background model developed at the University of Southampton, UK. The three components are cosmic diffuse gamma rays, atmospheric albedo gamma rays, and cosmic ray protons. We present examples of how this model was applied to BATSE and discuss its application to EXIST.

Wilson, Colleen A.; Pendleton, G. N.; Fishman, G. J.

2004-01-01

274

Tracheostomy tubes and related appliances.  

PubMed

Tracheostomy tubes are used to administer positive-pressure ventilation, to provide a patent airway, to provide protection from aspiration, and to provide access to the lower respiratory tract for airway clearance. They are available in a variety of sizes and styles, from several manufacturers. The dimensions of tracheostomy tubes are given by their inner diameter, outer diameter, length, and curvature. Differences in length between tubes of the same inner diameter, but from different manufacturers, are not commonly appreciated but may have important clinical implications. Tracheostomy tubes can be angled or curved, a feature that can be used to improve the fit of the tube in the trachea. Extra proximal length tubes facilitate placement in patients with large necks, and extra distal length tubes facilitate placement in patients with tracheal anomalies. Several tube designs have a spiral wire reinforced flexible design and have an adjustable flange design to allow bedside adjustments to meet extra-length tracheostomy tube needs. Tracheostomy tubes can be cuffed or uncuffed. Cuffs on tracheostomy tubes include high-volume low-pressure cuffs, tight-to-shaft cuffs, and foam cuffs. The fenestrated tracheostomy tube has an opening in the posterior portion of the tube, above the cuff, which allows the patient to breathe through the upper airway when the inner cannula is removed. Tracheostomy tubes with an inner cannula are called dual-cannula tracheostomy tubes. Several tracheostomy tubes are designed specifically for use with the percutaneous tracheostomy procedure. Others are designed with a port above the cuff that allows for subglottic aspiration of secretions. The tracheostomy button is used for stoma maintenance. It is important for clinicians caring for patients with a tracheostomy tube to understand the nuances of various tracheostomy tube designs and to select a tube that appropriately fits the patient. PMID:15807912

Hess, Dean R

2005-04-01

275

On Background Independence  

E-print Network

This paper concerns what Background Independence itself is (as opposed to some particular physical theory that is background independent). The notions presented mostly arose from a layer-by-layer analysis of the facets of the Problem of Time in Quantum Gravity. Part of this coincides with two relational postulates which are thus identified as classical precursors of two of the facets of the Problem of Time. These are furthemore tied to the forms of each of the GR Hamiltonian and momentum constraints. Other aspects of Background Independence include the algebraic closure of these constraints, expressing physics in terms of beables, foliation independence as implemented by refoliation invariance, the reconstruction of spacetime from space. The final picture is that Background Independence - a philosophically desirable and physically implementable feature for a theory to have - has the facets of the Problem of Time among its consequences. Thus these arise naturally and are problems to be resolved, as opposed to avoided `by making one's physics background-dependent in order not to have these problems'. This serves as a selection criterion that limits the use of a number of model arenas and physical theories.

Edward Anderson

2013-10-05

276

Mechanistic insights from a quantitative analysis of pollen tube guidance  

PubMed Central

Background Plant biologists have long speculated about the mechanisms that guide pollen tubes to ovules. Although there is now evidence that ovules emit a diffusible attractant, little is known about how this attractant mediates interactions between the pollen tube and the ovules. Results We employ a semi-in vitro assay, in which ovules dissected from Arabidopsis thaliana are arranged around a cut style on artificial medium, to elucidate how ovules release the attractant and how pollen tubes respond to it. Analysis of microscopy images of the semi-in vitro system shows that pollen tubes are more attracted to ovules that are incubated on the medium for longer times before pollen tubes emerge from the cut style. The responses of tubes are consistent with their sensing a gradient of an attractant at 100-150 ?m, farther than previously reported. Our microscopy images also show that pollen tubes slow their growth near the micropyles of functional ovules with a spatial range that depends on ovule incubation time. Conclusions We propose a stochastic model that captures these dynamics. In the model, a pollen tube senses a difference in the fraction of receptors bound to an attractant and changes its direction of growth in response; the attractant is continuously released from ovules and spreads isotropically on the medium. The model suggests that the observed slowing greatly enhances the ability of pollen tubes to successfully target ovules. The relation of the results to guidance in vivo is discussed. PMID:20170550

2010-01-01

277

The development of the neural crest in the human  

PubMed Central

The first systematic account of the neural crest in the human has been prepared after an investigation of 185 serially sectioned staged embryos, aided by graphic reconstructions. As many as fourteen named topographical subdivisions of the crest were identified and eight of them give origin to ganglia (Table 2). Significant findings in the human include the following. (1) An indication of mesencephalic neural crest is discernible already at stage 9, and trigeminal, facial, and postotic components can be detected at stage 10. (2) Crest was not observed at the level of diencephalon 2. Although pre-otic crest from the neural folds is at first continuous (stage 10), crest-free zones are soon observable (stage 11) in Rh.1, 3, and 5. (3) Emigration of cranial neural crest from the neural folds at the neurosomatic junction begins before closure of the rostral neuropore, and later crest cells do not accumulate above the neural tube. (4) The trigeminal, facial, glossopharyngeal and vagal ganglia, which develop from crest that emigrates before the neural folds have fused, continue to receive contributions from the roof plate of the neural tube after fusion of the folds. (5) The nasal crest and the terminalis-vomeronasal complex are the last components of the cranial crest to appear (at stage 13) and they persist longer. (6) The optic, mesencephalic, isthmic, accessory, and hypoglossal crest do not form ganglia. Cervical ganglion 1 is separated early from the neural crest and is not a Froriep ganglion. (7) The cranial ganglia derived from neural crest show a specific relationship to individual neuromeres, and rhombomeres are better landmarks than the otic primordium, which descends during stages 9–14. (8) Epipharyngeal placodes of the pharyngeal arches contribute to cranial ganglia, although that of arch 1 is not typical. (9) The neural crest from rhombomeres 6 and 7 that migrates to pharyngeal arch 3 and from there rostrad to the truncus arteriosus at stage 12 is identified here, for the first time in the human, as the cardiac crest. (10) The hypoglossal crest provides cells that accompany those of myotomes 1–4 and form the hypoglossal cell cord at stages 13 and 14. (11) The occipital crest, which is related to somites 1–4 in the human, differs from the spinal mainly in that it does not develop ganglia. (12) The occipital and spinal portions of the crest migrate dorsoventrad and appear to traverse the sclerotomes before the differentiation into loose and dense zones in the latter. (13) Embryonic examples of synophthalmia and anencephaly are cited to emphasize the role of the neural crest in the development of cranial ganglia and the skull. PMID:17848161

O’Rahilly, Ronan; Müller, Fabiola

2007-01-01

278

Supersymmetric heterotic string backgrounds  

E-print Network

We present the main features of the solution of the gravitino and dilatino Killing spinor equations derived in hep-th/0510176 and hep-th/0703143 which have led to the classification of geometric types of all type I backgrounds. We then apply these results to the supersymmetric backgrounds of the heterotic string. In particular, we solve the gaugino Killing spinor equation together with the other two Killing spinor equations of the theory. We also use our results to classify all supersymmetry conditions of ten-dimensional gauge theory.

Ulf Gran; George Papadopoulos; Diederik Roest

2007-06-29

279

Cosmological Gravitational Wave Backgrounds  

E-print Network

An overview is presented of possible cosmologically distant sources of gravitational wave backgrounds, especially those which might produce detectable backgrounds in the LISA band between 0.1 and 100 mHz. Examples considered here include inflation-amplified vacuum fluctuations in inflaton and graviton fields, bubble collisions in first-order phase transitions, Goldstone modes of classical self-ordering scalars, and cosmic strings and other gauge defects. Characteristic scales and basic mechanisms are reviewed and spectra are estimated for each of these sources. The unique impact of a LISA detection on fundamental physics and cosmology is discussed.

Craig J. Hogan

1998-09-28

280

Computing with neural synchrony.  

PubMed

Neurons communicate primarily with spikes, but most theories of neural computation are based on firing rates. Yet, many experimental observations suggest that the temporal coordination of spikes plays a role in sensory processing. Among potential spike-based codes, synchrony appears as a good candidate because neural firing and plasticity are sensitive to fine input correlations. However, it is unclear what role synchrony may play in neural computation, and what functional advantage it may provide. With a theoretical approach, I show that the computational interest of neural synchrony appears when neurons have heterogeneous properties. In this context, the relationship between stimuli and neural synchrony is captured by the concept of synchrony receptive field, the set of stimuli which induce synchronous responses in a group of neurons. In a heterogeneous neural population, it appears that synchrony patterns represent structure or sensory invariants in stimuli, which can then be detected by postsynaptic neurons. The required neural circuitry can spontaneously emerge with spike-timing-dependent plasticity. Using examples in different sensory modalities, I show that this allows simple neural circuits to extract relevant information from realistic sensory stimuli, for example to identify a fluctuating odor in the presence of distractors. This theory of synchrony-based computation shows that relative spike timing may indeed have computational relevance, and suggests new types of neural network models for sensory processing with appealing computational properties. PMID:22719243

Brette, Romain

2012-01-01

281

Computing with Neural Synchrony  

PubMed Central

Neurons communicate primarily with spikes, but most theories of neural computation are based on firing rates. Yet, many experimental observations suggest that the temporal coordination of spikes plays a role in sensory processing. Among potential spike-based codes, synchrony appears as a good candidate because neural firing and plasticity are sensitive to fine input correlations. However, it is unclear what role synchrony may play in neural computation, and what functional advantage it may provide. With a theoretical approach, I show that the computational interest of neural synchrony appears when neurons have heterogeneous properties. In this context, the relationship between stimuli and neural synchrony is captured by the concept of synchrony receptive field, the set of stimuli which induce synchronous responses in a group of neurons. In a heterogeneous neural population, it appears that synchrony patterns represent structure or sensory invariants in stimuli, which can then be detected by postsynaptic neurons. The required neural circuitry can spontaneously emerge with spike-timing-dependent plasticity. Using examples in different sensory modalities, I show that this allows simple neural circuits to extract relevant information from realistic sensory stimuli, for example to identify a fluctuating odor in the presence of distractors. This theory of synchrony-based computation shows that relative spike timing may indeed have computational relevance, and suggests new types of neural network models for sensory processing with appealing computational properties. PMID:22719243

Brette, Romain

2012-01-01

282

The Blue Tube.  

ERIC Educational Resources Information Center

The "Blue Tube" is a 2-part academic package developed at the U.S. Air Force Academy consisting of an English course in communication and writing skills and a management course in advertising and marketing; the two courses are interrelated through student assignments in television production. The first part of the package includes training of…

Wallisch, Bill; Taylor, Bob

283

An explosive shock tube  

Microsoft Academic Search

Experiments with a model explosive shock tube are described. Flow of a ; dense air plasma with speed 25-l0 km\\/sec is obtained by means of an explosive gas ; compressor. Photographs of flow over models were taken when the flow behind the ; shock wave becomes opaque. The experiments were conducted in a laboratory ; explosion chamber, (auth);

A. E. Voitenko; M. A. Lyubimova; E. P. Matochkin

1973-01-01

284

Tube Feeding Transition Plateaus  

ERIC Educational Resources Information Center

The journey children make from tube feeding to oral feeding is personal for each child and family. There is a sequence of predictable plateaus that children climb as they move toward orally eating. By better understanding this sequence, parents and children can maximize the development, learning, enjoyment and confidence at each plateau. The…

Klein, Marsha Dunn

2007-01-01

285

Multiphase Detonations in Tubes  

Microsoft Academic Search

There are many applications that involve shock interactions with liquid-fuel droplets and transition to detonation. Previous experimental studies have shown that the measured detonation velocity is usually significantly less than the theoretical Chapman-Jouguet (CJ) velocity in most cases and appears to depend on the size of the droplets involved. Numerical simulations have been conducted of a shock tube, where the

Sally Cheatham; K. Kailasanath

2002-01-01

286

Tube welding and brazing  

NASA Technical Reports Server (NTRS)

Brochures outline the tools, equipment, materials, and techniques used for joining tubes by automatic and semiautomatic welding and brazing. A few of the metals being joined are stainless steels of various diameters and thickness. Techniques have been developed for on-site or work-bench repair.

Poorman, R. M.

1969-01-01

287

Joining Tubes With Adhesive  

NASA Technical Reports Server (NTRS)

Cylindrical tubes joined together, end to end, by method employing adhesive, tapered ends, and spacing wires. Tapered joint between tubular structural elements provides pressure between bonding surfaces during adhesive curing. Spacing wires prevent adhesive from being scraped away when one element inserted in other. Method developed for assembling structural elements made of composite materials.

Bateman, W. A.

1984-01-01

288

Investigation of Pitot tubes  

NASA Technical Reports Server (NTRS)

Report describes the principles of operation and characteristics of some of the instruments which have been devised or used to measure both low and high speeds of aeroplanes. Since the pitot tube is the instrument which has been most commonly used in the United States and Great Britain as a speedometer for aeroplanes, it is treated first and somewhat more fully than the others.

Herschel, W H; Buckingham, E

1917-01-01

289

Metal package photomultiplier tube  

Microsoft Academic Search

The Metal Package PMT R5600U series, a size of 15 mm diameter and 10 mm height, has been developed. Its appearance is the same as TO-8 type solid state device and it has as high sensitivity and speed as a conventional PMT. There are two important key components for the development of this tube. They are the metal envelope same

H. Kyushima; Y. Hasegama; A. Atsumi; Y. Yokota; H. Matsuura; Y. Watase; M. Ito; J. Takeuchi; K. Oba

1994-01-01

290

Ear tube insertion  

MedlinePLUS

... trapped fluid can flow out of the middle ear. This prevents hearing loss and reduces the risk of ear infections. ... do not have long-term damage to their hearing or speech, even when ... many months. Ear tube insertion may be done when fluid builds ...

291

Extrusion of a tube  

NSDL National Science Digital Library

For flow through a seamless tube extruder, use simplifying assumptions to reduce the appropriate form of the Navier-Stokes equations as much as possible, sketch the expected flow profile for three rheology types, and discuss microstructure changes during the extrusion process.

Powell, Adam C., IV

2005-05-02

292

Cranial Neural Crest Migration: New Rules for an Old Road  

PubMed Central

The neural crest serve as an excellent model to better understand mechanisms of embryonic cell migration. Cell tracing studies have shown that cranial neural crest cells (CNCCs) emerge from the dorsal neural tube in a rostrocaudal manner and are spatially distributed along stereotypical, long distance migratory routes to precise targets in the head and branchial arches. Although the CNCC migratory pattern is a beautifully choreographed and programmed invasion, the underlying orchestration of molecular events is not well known. For example, it is still unclear how single CNCCs react to signals that direct their choice of direction and how groups of CNCCs coordinate their interactions to arrive at a target in an ordered manner. In this review, we discuss recent cellular and molecular discoveries of the CNCC migratory pattern. We focus on events from the time when CNCCs encounter the tissue adjacent to the neural tube and their travel through different microenvironments and into the branchial arches. We describe the patterning of discrete cell migratory streams that emerge from the hindbrain, rhombomere (r) segments r1–r7, and the signals that coordinate directed migration. We propose a model that attempts to unify many complex events that establish the CNCC migratory pattern, and based on this model we integrate information between cranial and trunk neural crest development. PMID:20399765

Kulesa, Paul M.; Bailey, Caleb M.; Kasemeier-Kulesa, Jennifer C.; McLennan, Rebecca

2010-01-01

293

Cosmic background radiation  

Microsoft Academic Search

We summarise the current status of cosmic microwave background spectrum and\\u000aanisotropy measurements, and their theoretical interpretation. This is the\\u000aupdate of the mini-review for the 1997 web-version of the Review of Particle\\u000aProperties.

George Smoot; Douglas Scott

2000-01-01

294

PANDEMIC INFLUENZA background briefing  

E-print Network

PANDEMIC INFLUENZA background briefing Biomedicine Forum 5 November 2008 compiled by David Evans, Dave Carr, David Lynn and Phil Green Transmission electron micrograph of Influenza A virus (Wellcome influenza!' Page 2 #12;Consequences of an influenza pandemic THE PANDEMIC THREAT DEATH If the next pandemic

Rambaut, Andrew

295

David Smith Academic background  

E-print Network

David Smith Academic background Ph.D. in Mathematics (Algebra), Université de Sherbrooke, Canada project program (I. Assem, F. Bergeron, C. Reutenauer, D. Smith) $132,000 ($44,000 per year for 3 years. Schiffler and D. Smith, Friezes, strings and cluster variables, to appear in Glasgow Mathematcal Journal. 2

296

INDIAN BACKGROUNDS Patuxent Wildlife  

E-print Network

of Sport Fisheries and Wildlife Circular 138 #12;#12;INDIAN BACKGROUNDS of the Patuxent Wildlife Research of the Interior Fish and Wildlife Service Bureau of Sport Fisheries and Wildlife Circular 138 #12; Exhibit the Indian hunted with spear and arrow to supply the necessities of life--food, clothing, and shelter

297

Local microwave background radiation  

E-print Network

An inquiry on a possible local origin for the Microwave Background Radiation is made. Thermal MBR photons are contained in a system called {\\it magnetic bottle} which is due to Earth magnetic field and solar wind particles, mostly electrons. Observational tests are anticipated.

Domingos S. L. Soares

2006-07-11

298

Performance of photomultiplier tubes and sodium iodide scintillation detector systems  

NASA Technical Reports Server (NTRS)

The performance of photomultiplier tubes (PMT's) and scintillation detector systems incorporating 50.8 by 1.27 cm NaI (T l) crystals was investigated to determine the characteristics of the photomultiplier tubes and optimize the detector geometry for the Burst and Transient Source Experiment on the Gamma Ray Observatory. Background information on performance characteristics of PMT's and NaI (T l) detectors is provided, procedures for measurement of relevant parameters are specified, and results of these measurements are presented.

Meegan, C. A.

1981-01-01

299

Tubing For Sampling Hydrazine Vapor  

NASA Technical Reports Server (NTRS)

Report evaluates flexible tubing used for transporting such hypergolic vapors as those of hydrazines for quantitative analysis. Describes experiments in which variety of tubing materials, chosen for their known compatibility with hydrazine, flexibility, and resistance to heat.

Travis, Josh; Taffe, Patricia S.; Rose-Pehrsson, Susan L.; Wyatt, Jeffrey R.

1993-01-01

300

Rubens Flame-Tube Demonstration.  

ERIC Educational Resources Information Center

Investigates and explains the phenomenon associated with Rubens flame-tube demonstration, specifically the persistance of flames at regular intervals along the tube for few minutes after the gas is turned off. (GA)

Ficken, George W.; Stephenson, Francis C.

1979-01-01

301

An early requirement for FGF signalling in the acquisition of neural cell fate in the chick embryo  

Microsoft Academic Search

Background: In Xenopus embryos, fibroblast growth factors (FGFs) and secreted inhibitors of bone morphogenetic protein (BMP)-mediated signalling have been implicated in neural induction. The precise roles, if any, that these factors play in neural induction in amniotes remains to be established.Results: To monitor the initial steps of neural induction in the chick embryo, we developed an in vitro assay of

Sara I Wilson; Enrique Graziano; Richard Harland; Thomas M Jessell; Thomas Edlund

2000-01-01

302

A Low-Noise Low-Power Noise-Adaptive Neural Amplifier in 0.13um CMOS Technology  

Microsoft Academic Search

Chronic recording of neural signals is indispensable in designing efficient brain machine interfaces and in elucidating human neurophysiology. The advent of multichannel micro- electrode arrays has driven the need for electronics to record neural signals from many neurons. The dynamic range of the system is limited by background system noise which varies over time. We propose a neural amplifier in

Vikram Chaturvedi; Bharadwaj Amrutur

2011-01-01

303

Selective migration of neuralized embryonic stem cells to stem cell factor and media conditioned by glioma cell lines  

Microsoft Academic Search

BACKGROUND: Pluripotent mouse embryonic stem (ES) cells can be induced in vitro to become neural progenitors. Upon transplantation, neural progenitors migrate toward areas of damage and inflammation in the CNS. We tested whether undifferentiated and neuralized mouse ES cells migrate toward media conditioned by glioma cell lines (C6, U87 & N1321) or Stem Cell Factor (SCF). RESULTS: Cell migration assays

Peter Serfozo; Maggie S Schlarman; Chris Pierret; Bernard L Maria; Mark D Kirk

2006-01-01

304

The contribution of neural crest cells to the nuchal bone and plastron of the turtle shell.  

PubMed

The origin of the turtle plastron is not well understood, and these nine bones have been homologized to the exoskeletal components of the clavicles, the interclavicular bone, and gastralia. Earlier data from our laboratory showed that the plastral bone-forming cells stained positively for HNK-1 and PDGFR?, two markers of skeletogenic neural crest cells. We have now shown that the HNK-1(+) cells are also positive for p75 and FoxD3, affirming their neural crest identity. These cells originate from the dorsal neural tube of stage-17 turtle embryos, several days after the original wave of neural crest cells have migrated and differentiated. Moreover, we have demonstrated the existence of a staging area, above the neural tube and vertebrae, where these late-emigrating neural crest cells collect. After residing in the carapacial staging area, these cells migrate to form the plastral bones. We also demonstrate that one bone of the carapace, the nuchal bone, also stains with HNK-1 and with antibodies to PDGFR?. The nuchal bone shares several other properties with the plastral bones, suggesting that it, too, is derived from neural crest cells. Alligator gastralia stain for HNK-1, while their ribs do not, thus suggesting that the gastralial precursor may also be derived from neural crest cells. PMID:21672848

Gilbert, Scott F; Bender, Gunes; Betters, Erin; Yin, Melinda; Cebra-Thomas, Judith A

2007-09-01

305

Id expression in amphioxus and lamprey highlights the role of gene cooption during neural crest evolution  

NASA Technical Reports Server (NTRS)

Neural crest cells are unique to vertebrates and generate many of the adult structures that differentiate them from their closest invertebrate relatives, the cephalochordates. Id genes are robust markers of neural crest cells at all stages of development. We compared Id gene expression in amphioxus and lamprey to ask if cephalochordates deploy Id genes at the neural plate border and dorsal neural tube in a manner similar to vertebrates. Furthermore, we examined whether Id expression in these cells is a basal vertebrate trait or a derived feature of gnathostomes. We found that while expression of Id genes in the mesoderm and endoderm is conserved between amphioxus and vertebrates, expression in the lateral neural plate border and dorsal neural tube is a vertebrate novelty. Furthermore, expression of lamprey Id implies that recruitment of Id genes to these cells occurred very early in the vertebrate lineage. Based on expression in amphioxus we postulate that Id cooption conferred sensory cell progenitor-like properties upon the lateral neurectoderm, and pharyngeal mesoderm-like properties upon cranial neural crest. Amphioxus Id expression is also consistent with homology between the anterior neurectoderm of amphioxus and the presumptive placodal ectoderm of vertebrates. These observations support the idea that neural crest evolution was driven in large part by cooption of multipurpose transcriptional regulators from other tissues and cell types.

Meulemans, Daniel; McCauley, David; Bronner-Fraser, Marianne

2003-01-01

306

Neural networks at work  

Microsoft Academic Search

The benefits of neural networks and the types of application for which they are suited are outlined. Four representative applications are described in enough detail to show how they work. They are character recognition, function estimation, financial forecasting, and process control. Factors that have slowed the acceptance of neural networks are discussed. Hardware is briefly considered

D. Hammerstrom

1993-01-01

307

Cellular neural networks: theory  

Microsoft Academic Search

A novel class of information-processing systems called cellular neural networks is proposed. Like neural networks, they are large-scale nonlinear analog circuits that process signals in real time. Like cellular automata, they consist of a massive aggregate of regularly spaced circuit clones, called cells, which communicate with each other directly only through their nearest neighbors. Each cell is made of a

L. O. Chua; L. Yang

1988-01-01

308

Hybrid convolutional neural networks  

Microsoft Academic Search

Convolutional neural networks are known to outperform all other neural network models when classifying a wide variety of 2D-shapes. This type of networks supports a massively parallel extraction of low-level features in the processed images. Especially this characteristic is assumed to impact the performance of convolutional networks in character recognition tasks - and in particular when considering scaled, rotated, translated

I. Mrazova; M. Kukacka

2008-01-01

309

Critical Branching Neural Networks  

ERIC Educational Resources Information Center

It is now well-established that intrinsic variations in human neural and behavioral activity tend to exhibit scaling laws in their fluctuations and distributions. The meaning of these scaling laws is an ongoing matter of debate between isolable causes versus pervasive causes. A spiking neural network model is presented that self-tunes to critical…

Kello, Christopher T.

2013-01-01

310

The feasibility of using neural networks to obtain cross sections from electron swarm data  

SciTech Connect

This paper reports that although still more a curiosity than an accepted technique in computational modeling, the very new field of neural computing is beginning to find applications in physics. Presented in some background on neural computing and a discussion on the use of neural networks to obtain electron-impact cross sections from measured drift velocities, characteristic energies, and other swarm data. This is what is known as an inverse problem, a class of problems for which neural networks may be frequently superior to other numerical algorithms. Momentum transfer cross sections obtained for a model problem and for xenon using a neural network are presented.

Morgan, W.L. (Kinema Research Monument, CO (US))

1991-04-01

311

New insights into the collapsing of cylindrical thin-walled tubes under axial impact load  

E-print Network

and both single-objective and multi-objective optimizations are carried out using the genetic algorithm. Keywords: axial crushing, circular tubes, plastic buckling modes, neural networks, genetic algorithm 1 Corresponding author: Department of Mechanical Engineering, Amirkabir University of Technology, 424 Hafez Avenue

Entekhabi, Dara

312

ENHANCED TUBES FOR STEAM CONDENSERS  

Microsoft Academic Search

This article provides data on enhanced tubes developed especially for application to steam condensers. Data are provided for different types of tube-side (cooling water) and shell-side (steam) enhancements. The first test series involved measuring the condensing coefficient at a 327 K saturation temperature. Average enhancement levels (defined as the ratio of the condensing coefficient of an enhanced tube to that

M. Hassib Jaber; Ralph L. Webb

1993-01-01

313

Boiler tube failure reduction program  

Microsoft Academic Search

Boiler tube failures are generally recognized as the major cause of forced outages of fossil power generating units for US electric utilities. In almost all cases of serious availability losses, the boiler tube failures are repeat in nature and result in multiple forced outages. Primary factors influencing repeat, rather than random, tube failures are usually found to result from not

G. A. Lamping; O. Jonas; R. J. Niebo

1991-01-01

314

YouTube Physics  

NASA Astrophysics Data System (ADS)

To date, this column has presented videos to show in class, Don Mathieson from Tulsa Community College suggested that YouTube could be used in another fashion. In Don's experience, his students are not always prepared for the mathematic rigor of his course. Even at the high school level, math can be a barrier for physics students. Walid Shihabi, a colleague of Don's, decided to compile a list of YouTube videos that his students could watch to relearn basic mathematics. I thought this sounded like a fantastic idea and a great service to the students. Walid graciously agreed to share his list and I have reproduced a large portion of it below.

Riendeau, Diane

2012-09-01

315

Induction plasma tube  

DOEpatents

An induction plasma tube having a segmented, fluid-cooled internal radiation shield is disclosed. The individual segments are thick in cross-section such that the shield occupies a substantial fraction of the internal volume of the plasma enclosure, resulting in improved performance and higher sustainable plasma temperatures. The individual segments of the shield are preferably cooled by means of a counterflow fluid cooling system wherein each segment includes a central bore and a fluid supply tube extending into the bore. The counterflow cooling system results in improved cooling of the individual segments and also permits use of relatively larger shield segments which permit improved electromagnetic coupling between the induction coil and a plasma located inside the shield. Four embodiments of the invention, each having particular advantages, are disclosed.

Hull, Donald E. (Los Alamos, NM)

1984-01-01

316

Induction plasma tube  

DOEpatents

An induction plasma tube having a segmented, fluid-cooled internal radiation shield is disclosed. The individual segments are thick in cross-section such that the shield occupies a substantial fraction of the internal volume of the plasma enclosure, resulting in improved performance and higher sustainable plasma temperatures. The individual segments of the shield are preferably cooled by means of a counterflow fluid cooling system wherein each segment includes a central bore and a fluid supply tube extending into the bore. The counterflow cooling system results in improved cooling of the individual segments and also permits use of relatively larger shield segments which permit improved electromagnetic coupling between the induction coil and a plasma located inside the shield. Four embodiments of the invention, each having particular advantages, are disclosed.

Hull, D.E.

1982-07-02

317

Cardboard Tube Syllabus  

NSDL National Science Digital Library

This site contains an activity demonstrating how one's eyes influence each other and what occurs when two eyes receive conflicting information. The participant looks through a paper tube with only one eye to perform four different activities: Hole In Your Hand, Overlapping Spots, Circles or Ovals? and Lateral Inhibition. Each activity is quick and includes specific instructions, materials needed, assembly, and an explanation of the observed results. This activity is part of Exploratorium's Science Snacks series.

2008-06-19

318

Traveling-Wave Tubes  

NASA Technical Reports Server (NTRS)

The traveling-wave tube (TWT) is a vacuum device invented in the early 1940's used for amplification at microwave frequencies. Amplification is attained by surrendering kinetic energy from an electron beam to a radio frequency (RF) electromagnetic wave. The demand for vacuum devices has been decreased largely by the advent of solid-state devices. However, although solid state devices have replaced vacuum devices in many areas, there are still many applications such as radar, electronic countermeasures and satellite communications, that require operating characteristics such as high power (Watts to Megawatts), high frequency (below 1 GHz to over 100 GHz) and large bandwidth that only vacuum devices can provide. Vacuum devices are also deemed irreplaceable in the music industry where musicians treasure their tube-based amplifiers claiming that the solid-state and digital counterparts could never provide the same "warmth" (3). The term traveling-wave tube includes both fast-wave and slow-wave devices. This article will concentrate on slow-wave devices as the vast majority of TWTs in operation fall into this category.

Kory, Carol L.

1998-01-01

319

Concentric tube support assembly  

DOEpatents

An assembly (45) includes a plurality of separate pie-shaped segments (72) forming a disk (70) around a central region (48) for retaining a plurality of tubes (46) in a concentrically spaced apart configuration. Each segment includes a support member (94) radially extending along an upstream face (96) of the segment and a plurality of annularly curved support arms (98) transversely attached to the support member and radially spaced apart from one another away from the central region for receiving respective upstream end portions of the tubes in arc-shaped spaces (100) between the arms. Each segment also includes a radial passageway (102) formed in the support member for receiving a fluid segment portion (106) and a plurality of annular passageways (104) formed in the support arms for receiving respective arm portions (108) of the fluid segment portion from the radial passageway and for conducting the respective arm portions into corresponding annular spaces (47) formed between the tubes retained by the disk.

Rubio, Mark F.; Glessner, John C.

2012-09-04

320

Anterior/posterior influences on neural crest-derived pigment cell differentiation.  

PubMed

The neural crest of vertebrate embryos has been used to elucidate steps involved in early embryonic cellular processes such as differentiation and migration. Neural crest cells form a ridge along the dorsal midline and subsequently they migrate throughout the embryo and differentiate into a wide variety of cell types. Intrinsic factors and environmental cues distributed along the neural tube, along the migratory pathways, and/or at the location of arrest influence the fate of neural crest cells. Although premigratory cells of the cranial and trunk neural crest exhibit differences in their differentiation potentials, premigratory trunk neural crest cells are generally assumed to have equivalent developmental potentials. Axolotl neural crest cells from different regions of origin, different stages of development, and challenged with different culture media have been analyzed for differentiation preferences pertaining to the pigment cell lineages. We report region-dependent differentiation of chromatophores from trunk neural crest at two developmental stages. Also, dosage with guanosine produces region-specific influences on the production of xanthophores from wild-type embryos. Our results support the hypothesis that spatial and temporal differences among premigratory trunk neural crest cells found along the anteroposterior axis influence developmental potentials and diminish the equivalency of axolotl neural crest cells. PMID:9711533

Thibaudeau, G; Holder, S; Gerard, P

1998-08-01

321

Insights from the amphioxus genome on the origin of vertebrate neural crest.  

PubMed

The emergence of the neural crest has been proposed to play a key role in early vertebrate evolution by remodeling the chordate head into a "new head" that enabled early vertebrates to shift from filter feeding to active predation. Here we show that the genome of the basal chordate, amphioxus, contains homologs of most vertebrate genes implicated in a putative neural crest gene regulatory network (NC-GRN) for neural crest development. Our survey of gene expression shows that early inducing signals, neural plate border patterning genes, and melanocyte differentiation genes appear conserved. Furthermore, exogenous BMP affects expression of amphioxus neural plate border genes as in vertebrates, suggesting that conserved signals specify the neural plate border throughout chordates. In contrast to this core conservation, many neural crest specifier genes are not expressed at the amphioxus neural plate/tube border, raising the intriguing possibility that this level of the network was co-opted during vertebrate evolution. Consistent with this, the regulatory region of AmphiFoxD, homologous to the vertebrate neural crest specifier FoxD3, drives tissue-specific reporter expression in chick mesoderm, but not neural crest. Thus, evolution of a new regulatory element may have allowed co-option of this gene to the NC-GRN. PMID:18562679

Yu, Jr-Kai; Meulemans, Daniel; McKeown, Sonja J; Bronner-Fraser, Marianne

2008-07-01

322

POLYFLOW theoretical background  

NASA Astrophysics Data System (ADS)

In the scope of the 1990-04 lecture series on computational fluid dynamics, a finite element program is described. POLYFLOW was designed for the analysis of industrial processes dominated by nonlinear viscous phenomena and viscoelastic effects. It is based on the general principles of continuum mechanics, together with phenomenological or kinetic theoretical models for describing the rheological behavior of the fluid. The theoretical background, necessary to understand the models, and numerical techniques used in POLYFLOW, are provided. The governing equations, their finite element formulations and the solution procedures are summarized.

Crochet, M. J.

323

The Iron Line Background  

E-print Network

We investigate the presence of iron line emission among faint X-ray sources identified in the 1Ms Chandra Deep Field South and in the 2Ms Chandra Deep Field North. Individual source spectra are stacked in seven redshift bins over the range z=0.5-4. We find that iron line emission is an ubiquitous property of X-ray sources up to z~3. The measured line strengths are in good agreement with those expected by simple pre-Chandra estimates based on X-ray background synthesis models. The average rest frame equivalent width of the iron line does not show significant changes with redshift.

Marcella Brusa; Roberto Gilli; Andrea Comastri

2005-01-25

324

Vagal neural crest provides inhibitory neurotransmission to the chick embryo cloaca  

Microsoft Academic Search

Introduction  The intrinsic innervation of the developing chick cloaca originates in the vagal and sacral regions of the neural tube. Its\\u000a major inhibitory neurotransmitters are nitric oxide (NO) and vasoactive intestinal peptide (VIP). It has previously been shown\\u000a that the majority of neurons in the chick embryo cloaca are derived from vagal neural crest cells. This study aimed to identify\\u000a the

Anne-Marie O’ Donnell; Prem Puri

2008-01-01

325

Step piston pulse tube refrigerator  

NASA Astrophysics Data System (ADS)

In this paper, a numerical simulation is done for a step piston pulse tube refrigerator. The step piston pulse tube refrigerator is a modification of an inertance tube pulse tube refrigerator, which has a step piston compressor. The step piston in a step cylinder forms a compression space which is connected to the after cooler and an expansion space which is connected to the buffer. Numerical simulation shows that it is more effective at higher refrigeration temperature. It also shows there is an optimum swept volume ratio of the expansion space over the compression space, and an optimum diameter and length of the inertance tube for a given refrigerator.

Zhu, Shaowei

2014-11-01

326

Hybrid endotracheal tubes  

NASA Astrophysics Data System (ADS)

Intubation involves the placement of a tube into the tracheal lumen and is prescribed in any setting in which the airway must be stabilized or the patient anesthetized. The purpose of the endotracheal tube in these procedures is to maintain a viable airway, facilitate mechanical ventilation, allow the administration of anesthetics, and prevent the reflux of vomitus into the lungs. In order to satisfy these requirements a nearly airtight seal must be maintained between the tube and the tracheal lining. Most conventional endotracheal tubes provide this seal by employing a cuff that is inflated once the tube is in place. However, the design of this cuff and properties of the material are a source of irritation and injury to the tracheal tissues. In fact, the complication rate for endotracheal intubation is reported to be between 10 and 60%, with manifestations ranging from severe sore throat to erosion through the tracheal wall. These complications are caused by a combination of the materials employed and the forces exerted by the cuff on the tracheal tissues. In particular, the abrasive action of the cuff shears cells from the lining, epithelium adhering to the cuff is removed during extubation, and normal forces exerted on the basement tissues disrupt the blood supply and cause pressure necrosis. The complications associated with tracheal intubation may be reduced or eliminated by employing airway devices constructed from hydrogel materials. Hydrogels are a class of crosslinked polymers which swell in the presence of moisture, and may contain more than 95% water by weight. For the current study, several prototype airway devices were constructed from hydrogel materials including poly(vinyl alcohol), poly(hydroxyethyl methacrylate), and poly(vinyl pyrrolidone). The raw hydrogel materials from this group were subjected to tensile, swelling, and biocompatibility testing, while the finished devices were subjected to extensive mechanical simulation and animal trials. During the course of these experiments it was discovered that reduced water content hydrogel materials generally exhibited superior mechanical properties, but performed more poorly during simulation and biocompatibility studies. Conversely, higher water content materials exhibited lower mechanical performance but superior simulation and biocompatibility results.

Sakezles, Christopher Thomas

327

27 CFR 41.35 - Cigarette tubes.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Cigarette tubes. 41.35 Section 41...IMPORTATION OF TOBACCO PRODUCTS, CIGARETTE PAPERS AND TUBES, AND PROCESSED... Taxes Tax Rates § 41.35 Cigarette tubes. Cigarette tubes...

2010-04-01

328

Beta-Actin Is Required for Proper Mouse Neural Crest Ontogeny  

PubMed Central

The mouse genome consists of six functional actin genes of which the expression patterns are temporally and spatially regulated during development and in the adult organism. Deletion of beta-actin in mouse is lethal during embryonic development, although there is compensatory expression of other actin isoforms. This suggests different isoform specific functions and, more in particular, an important function for beta-actin during early mammalian development. We here report a role for beta-actin during neural crest ontogeny. Although beta-actin null neural crest cells show expression of neural crest markers, less cells delaminate and their migration arrests shortly after. These phenotypes were associated with elevated apoptosis levels in neural crest cells, whereas proliferation levels were unchanged. Specifically the pre-migratory neural crest cells displayed higher levels of apoptosis, suggesting increased apoptosis in the neural tube accounts for the decreased amount of migrating neural crest cells seen in the beta-actin null embryos. These cells additionally displayed a lack of membrane bound N-cadherin and dramatic decrease in cadherin-11 expression which was more pronounced in the pre-migratory neural crest population, potentially indicating linkage between the cadherin-11 expression and apoptosis. By inhibiting ROCK ex vivo, the knockout neural crest cells regained migratory capacity and cadherin-11 expression was upregulated. We conclude that the presence of beta-actin is vital for survival, specifically of pre-migratory neural crest cells, their proper emigration from the neural tube and their subsequent migration. Furthermore, the absence of beta-actin affects cadherin-11 and N-cadherin function, which could partly be alleviated by ROCK inhibition, situating the Rho-ROCK signaling in a feedback loop with cadherin-11. PMID:24409333

Tondeleir, Davina; Noelanders, Rivka; Bakkali, Karima; Ampe, Christophe

2014-01-01

329

78 FR 48416 - Light-Walled Rectangular Pipe and Tube From the People's Republic of China: Final Results of the...  

Federal Register 2010, 2011, 2012, 2013

...Trade Administration [C-570-915] Light-Walled Rectangular Pipe and Tube From...review of the countervailing duty order on light-walled rectangular pipe and tube from...Background The countervailing duty order on light-walled rectangular pipe and tube...

2013-08-08

330

Implicit motor learning promotes neural efficiency during laparoscopy  

Microsoft Academic Search

Background  An understanding of differences in expert and novice neural behavior can inform surgical skills training. Outside the surgical\\u000a domain, electroencephalographic (EEG) coherence analyses have shown that during motor performance, experts display less coactivation\\u000a between the verbal-analytic and motor planning regions than their less skilled counterparts. Reduced involvement of verbal-analytic\\u000a processes suggests greater neural efficiency. The authors tested the utility of

Frank F. Zhu; Jamie M. Poolton; Mark R. Wilson; Yong Hu; Jon P. Maxwell; Rich S. W. Masters

331

Gas lasers and applications. [shock tube technology  

NASA Technical Reports Server (NTRS)

A brief review of laser elements is given. Flowing gas lasers are represented to have the best potential for high average power. The background of shock-tube researchers and the shock tube itself are alleged to be ideally suited for the development of such lasers. Three types - the electric discharge, the gasdynamic, and the chemical laser - are discussed briefly. A legion number of possible gas lasers is enumerated. With the development of their potential for higher power and efficiency, many additional and important uses of lasers are predicted, even beaming power through space for long distances, up to 1 AU. A few details of some current high-power gasdynamic laser devices are given.

Hansen, C. F.

1973-01-01

332

Cosmic Microwave Background Polarization  

E-print Network

Cosmic microwave background (CMB) anisotropy is our richest source of cosmological information; the standard cosmological model was largely established thanks to study of the temperature anisotropies. By the end of the decade, the Planck satellite will close this important chapter and move us deeper into the new frontier of polarization measurements. Numerous ground--based and balloon--borne experiments are already forging into this new territory. Besides providing new and independent information on the primordial density perturbations and cosmological parameters, polarization measurements offer the potential to detect primordial gravity waves, constrain dark energy and measure the neutrino mass scale. A vigorous experimental program is underway worldwide and heading towards a new satellite mission dedicated to CMB polarization.

James G. Bartlett

2006-01-25

333

Neural correlates of consciousness  

PubMed Central

Jon Driver's scientific work was characterized by an innovative combination of new methods for studying mental processes in the human brain in an integrative manner. In our collaborative work, he applied this approach to the study of attention and awareness, and their relationship to neural activity in the human brain. Here I review Jon's scientific work that relates to the neural basis of human consciousness, relating our collaborative work to a broader scientific context. I seek to show how his insights led to a deeper understanding of the causal connections between distant brain structures that are now believed to characterize the neural underpinnings of human consciousness. PMID:23991638

Rees, Geraint

2013-01-01

334

Neural control of muscle  

NASA Technical Reports Server (NTRS)

Cholinergic innervation regulates the physiological and biochemical properties of skeletal muscle. The mechanisms that appear to be involved in this regulation include soluble, neurally-derived polypeptides, transmitter-evoked muscle activity and the neurotransmitter, acetylcholine, itself. Despite extensive research, the interacting neural mechanisms that control such macromolecules as acetylcholinesterase, the acetylcholine receptor and glucose 6-phosphate dehydrogenase remain unclear. It may be that more simplified in vitro model systems coupled with recent dramatic advances in the molecular biology of neurally-regulated proteins will begin to allow researchers to unravel the mechanisms controlling the expression and maintenance of these macromolecules.

Max, S. R.; Markelonis, G. J.

1983-01-01

335

Neural networks for aircraft control  

NASA Technical Reports Server (NTRS)

Current research in Artificial Neural Networks indicates that networks offer some potential advantages in adaptation and fault tolerance. This research is directed at determining the possible applicability of neural networks to aircraft control. The first application will be to aircraft trim. Neural network node characteristics, network topology and operation, neural network learning and example histories using neighboring optimal control with a neural net are discussed.

Linse, Dennis

1990-01-01

336

Tube dislocations in gravity  

E-print Network

We consider static massive thin cylindrical shells (tubes) as the sources in Einstein's equations. They correspond to $\\dl$- and $\\dl'$-function type energy-momentum tensors. The corresponding metric components are found explicitly. They are not continuous functions in general and lead to ambiguous curvature tensor components. Nevertheless all ambiguous terms in Einstein's equations safely cancel. The interplay between elasticity theory, geometric theory of defects, and General Relativity is analyzed. The elasticity theory provides a simple picture for defects creation and a new look on General Relativity.

De Berredo-Peixoto, G

2008-01-01

337

Tube dislocations in gravity  

E-print Network

We consider static massive thin cylindrical shells (tubes) as the sources in Einstein's equations. They correspond to $\\dl$- and $\\dl'$-function type energy-momentum tensors. The corresponding metric components are found explicitly. They are not continuous functions in general and lead to ambiguous curvature tensor components. Nevertheless all ambiguous terms in Einstein's equations safely cancel. The interplay between elasticity theory, geometric theory of defects, and General Relativity is analyzed. The elasticity theory provides a simple picture for defects creation and a new look on General Relativity.

G. de Berredo-Peixoto; M. O. Katanaev

2008-10-01

338

Tube thoracostomy; chest tube implantation and follow up  

PubMed Central

Pneumothorax is an urgent medical situation that requires urgent treatment. We can divide this entity based on the etiology to primary and secondary. Chest tube implantation can be performed either in the upper chest wall or lower. Both thoracic surgeons and pulmonary physicians can place a chest tube with minimal invasive techniques. In our current work, we will demonstrate chest tube implantation to locations, methodology and tools. PMID:25337405

Kuhajda, Ivan; Zarogoulidis, Konstantinos; Kougioumtzi, Ioanna; Huang, Haidong; Li, Qiang; Dryllis, Georgios; Kioumis, Ioannis; Pitsiou, Georgia; Machairiotis, Nikolaos; Katsikogiannis, Nikolaos; Papaiwannou, Antonis; Lampaki, Sofia; Papaiwannou, Antonis; Zaric, Bojan; Branislav, Perin; Porpodis, Konstantinos

2014-01-01

339

An Empirical Study of Boosted Neural Network for Particle Classification in High Energy Collisions  

NASA Astrophysics Data System (ADS)

The possible application of boosted neural network to particle classification in high energy physics is discussed. A two-dimensional toy model, where the boundary between signal and background is irregular but not overlapping, is constructed to show how boosting technique works with neural network. It is found that boosted neural network not only decreases the error rate of classification significantly but also increases the efficiency and signal-background ratio. Besides, boosted neural network can avoid the disadvantage aspects of single neural network design. The boosted neural network is also applied to the classification of quark- and gluon-jet samples from Monte Carlo e+e- collisions, where the two samples show significant overlapping. The performance of boosting technique for the two different boundary cases — with and without overlapping is discussed.

Yu, Meiling; Liu, Lianshou

340

Reading a neural code.  

PubMed

Traditional approaches to neural coding characterize the encoding of known stimuli in average neural responses. Organisms face nearly the opposite task--extracting information about an unknown time-dependent stimulus from short segments of a spike train. Here the neural code was characterized from the point of view of the organism, culminating in algorithms for real-time stimulus estimation based on a single example of the spike train. These methods were applied to an identified movement-sensitive neuron in the fly visual system. Such decoding experiments determined the effective noise level and fault tolerance of neural computation, and the structure of the decoding algorithms suggested a simple model for real-time analog signal processing with spiking neurons. PMID:2063199

Bialek, W; Rieke, F; de Ruyter van Steveninck, R R; Warland, D

1991-06-28

341

Fiber inspired neural probes  

E-print Network

Limitations in the currently available technology for neural probes impede our progress towards a comprehensive brain activity map. The lack of understanding the brain function leads to limited options for the treatment ...

Canales, Andrés

2013-01-01

342

Free compression tube. Applications  

NASA Astrophysics Data System (ADS)

During the flight of vehicles, their propulsion energy must overcome gravity, to ensure the displacement of air masses on vehicle trajectory, to cover both energy losses from the friction between a solid surface and the air and also the kinetic energy of reflected air masses due to the impact with the flying vehicle. The flight optimization by increasing speed and reducing fuel consumption has directed research in the aerodynamics field. The flying vehicles shapes obtained through studies in the wind tunnel provide the optimization of the impact with the air masses and the airflow along the vehicle. By energy balance studies for vehicles in flight, the author Ioan Rusu directed his research in reducing the energy lost at vehicle impact with air masses. In this respect as compared to classical solutions for building flight vehicles aerodynamic surfaces which reduce the impact and friction with air masses, Ioan Rusu has invented a device which he named free compression tube for rockets, registered with the State Office for Inventions and Trademarks of Romania, OSIM, deposit f 2011 0352. Mounted in front of flight vehicles it eliminates significantly the impact and friction of air masses with the vehicle solid. The air masses come into contact with the air inside the free compression tube and the air-solid friction is eliminated and replaced by air to air friction.

Rusu, Ioan

2012-11-01

343

Formation and migration of neural crest cells in the vertebrate embryo.  

PubMed

The neural crest is a stem cell population, unique to vertebrates, that gives rise to a vast array of derivatives, ranging from peripheral ganglia to the facial skeleton. This population is induced in the early embryo at the border of the neural plate, which will form the central nervous system (CNS). After neural tube closure, neural crest cells depart from the dorsal CNS via an epithelial to mesenchymal transition (EMT), forming a migratory mesenchymal cell type that migrates extensive to diverse locations in the embryo. Using in vivo loss-of-function approaches and cis-regulatory analysis coupled with live imaging, we have investigated the gene regulatory network that mediates formation of this fascinating cell type. The results show that a combination of transcriptional inputs and epigenetic modifiers control the timing of onset of neural crest gene expression. This in turn leads to the EMT process that produces this migratory cell population. PMID:22820859

Bronner, Marianne E

2012-08-01

344

Pollen tube growth and guidance: roles of small, secreted proteins  

PubMed Central

Background Pollination is a crucial step in angiosperm (flowering plant) reproduction. Highly orchestrated pollen–pistil interactions and signalling events enable plant species to avoid inbreeding and outcrossing as a species-specific barrier. In compatible pollination, pollen tubes carrying two sperm cells grow through the pistil transmitting tract and are precisely guided to the ovules, discharging the sperm cells to the embryo sac for fertilization. Scope In Lilium longiflorum pollination, growing pollen tubes utilize two critical mechanisms, adhesion and chemotropism, for directional growth to the ovules. Among several molecular factors discovered in the past decade, two small, secreted cysteine-rich proteins have been shown to play major roles in pollen tube adhesion and reorientation bioassays: stigma/style cysteine-rich adhesin (SCA, approx. 9·3 kDa) and chemocyanin (approx. 9·8 kDa). SCA, a lipid transfer protein (LTP) secreted from the stylar transmitting tract epidermis, functions in lily pollen tube tip growth as well as in forming the adhesive pectin matrix at the growing pollen tube wall back from the tip. Lily chemocyanin is a plantacyanin family member and acts as a directional cue for reorienting pollen tubes. Recent consecutive studies revealed that Arabidopsis thaliana homologues for SCA and chemocyanin play pivotal roles in tip polarity and directionality of pollen tube growth, respectively. This review outlines the biological roles of various secreted proteins in angiosperm pollination, focusing on plant LTPs and chemocyanin. PMID:21307038

Chae, Keun; Lord, Elizabeth M.

2011-01-01

345

Gerbert's acoustical and astronomical tubes  

NASA Astrophysics Data System (ADS)

Gerbert of Aurillac dealt with tubes in astronomy and in acoustics. The celestial sphere he described to Constantine of Fleury in 978 has tubes for the accurate pointing of the North pole and for the observation of solstices and equinoxes days. After in 980 he built an organ for the emperor Otto II and wrote a treatise on the tuning of its tubes, De Mensura Fistularum, based on the number 12 of Pithagorean and Apostolic memory.

Sigismondi, Costantino

346

Tubing for augmented heat transfer  

SciTech Connect

The objectives of the program reported were: to determine the heat transfer and friction characteristics on the outside of spiral fluted tubing in single phase flow of water, and to assess the relative cost of a heat exchanger constructed with spiral fluted tubing with one using conventional smooth tubing. An application is examined where an isolation water/water heat exchanger was used to transfer the heat from a gaseous diffusion plant to an external system for energy recovery. (LEW)

Yampolsky, J.S.; Pavlics, P.

1983-08-01

347

Ion plated electronic tube device  

DOEpatents

An electronic tube and associated circuitry which is produced by ion plating techniques. The process is carried out in an automated process whereby both active and passive devices are produced at very low cost. The circuitry is extremely reliable and is capable of functioning in both high radiation and high temperature environments. The size of the electronic tubes produced are more than an order of magnitude smaller than conventional electronic tubes.

Meek, T.T.

1983-10-18

348

Diffusion in a Curved Tube  

E-print Network

The diffusion of particles in confining walls forming a tube is discussed. Such a transport phenomenon is observed in biological cells and porous media. We consider the case in which the tube is winding with curvature and torsion, and the thickness of the tube is sufficiently small compared with its curvature radius. We discuss how geomerical quantities appear in a quasi-one-dimensional diffusion equation.

Naohisa Ogawa

2011-09-03

349

Circular Scan Streak Tube Development  

NASA Technical Reports Server (NTRS)

A streak tube having circular scan was designed, built and tested. Continuous circular scan, easily derived from out of phase sine waves applied to the conventional deflection plates, permits the timing of pulses traveling long baselines. At the tube's output a circular array of 720 elements is scanned to provide 30 to 40 picosecond resolution. Initial difficulties with electron bombarded silicon arrays were circumvented by using microchannel plates within the streak tube to provide the needed electronic amplification and digital sensitivity and coupling the 720 element arrays to the electron beam by means of a phosphor on a fiber optics. Two ceramic body tubes with S-20 photocathodes were tested and delivered.

Nevin, S.

1980-01-01

350

Method for producing a tube  

DOEpatents

A method is described for producing tubular substrates having parallel spaced concentric rings of electrical conductors that can be used as the drift tube of an Ion Mobility Spectrometer (IMS). The invention comprises providing electrodes on the inside of a tube that are electrically connected to the outside of the tube through conductors that extend between adjacent plies of substrate that are combined to form the tube. Tubular substrates are formed from flexible polymeric printed wiring board materials, ceramic materials and material compositions of glass and ceramic, commonly known as Low Temperature Co-Fired Ceramic (LTCC). The adjacent plies are sealed together around the electrode.

Peterson, Kenneth A. (Albuquerque, NM); Rohde, Steven B. (Corrales, NM); Pfeifer, Kent B. (Los Lunas, NM); Turner, Timothy S. (Rio Rancho, NM)

2007-01-02

351

An exclusively mesodermal origin of fin mesenchyme demonstrates that zebrafish trunk neural crest does not generate ectomesenchyme.  

PubMed

The neural crest is a multipotent stem cell population that arises from the dorsal aspect of the neural tube and generates both non-ectomesenchymal (melanocytes, peripheral neurons and glia) and ectomesenchymal (skeletogenic, odontogenic, cartilaginous and connective tissue) derivatives. In amniotes, only cranial neural crest generates both classes, with trunk neural crest restricted to non-ectomesenchyme. By contrast, it has been suggested that anamniotes might generate derivatives of both classes at all axial levels, with trunk neural crest generating fin osteoblasts, scale mineral-forming cells and connective tissue cells; however, this has not been fully tested. The cause and evolutionary significance of this cranial/trunk dichotomy, and its absence in anamniotes, are debated. Recent experiments have disputed the contribution of fish trunk neural crest to fin osteoblasts and scale mineral-forming cells. This prompted us to test the contribution of anamniote trunk neural crest to fin connective tissue cells. Using genetics-based lineage tracing in zebrafish, we find that these fin mesenchyme cells derive entirely from the mesoderm and that neural crest makes no contribution. Furthermore, contrary to previous suggestions, larval fin mesenchyme cells do not generate the skeletogenic cells of the adult fin, but persist to form fibroblasts associated with adult fin rays. Our data demonstrate that zebrafish trunk neural crest does not generate ectomesenchymal derivatives and challenge long-held ideas about trunk neural crest fate. These findings have important implications for the ontogeny and evolution of the neural crest. PMID:23739134

Lee, Raymond Teck Ho; Knapik, Ela W; Thiery, Jean Paul; Carney, Thomas J

2013-07-01

352

An exclusively mesodermal origin of fin mesenchyme demonstrates that zebrafish trunk neural crest does not generate ectomesenchyme  

PubMed Central

The neural crest is a multipotent stem cell population that arises from the dorsal aspect of the neural tube and generates both non-ectomesenchymal (melanocytes, peripheral neurons and glia) and ectomesenchymal (skeletogenic, odontogenic, cartilaginous and connective tissue) derivatives. In amniotes, only cranial neural crest generates both classes, with trunk neural crest restricted to non-ectomesenchyme. By contrast, it has been suggested that anamniotes might generate derivatives of both classes at all axial levels, with trunk neural crest generating fin osteoblasts, scale mineral-forming cells and connective tissue cells; however, this has not been fully tested. The cause and evolutionary significance of this cranial/trunk dichotomy, and its absence in anamniotes, are debated. Recent experiments have disputed the contribution of fish trunk neural crest to fin osteoblasts and scale mineral-forming cells. This prompted us to test the contribution of anamniote trunk neural crest to fin connective tissue cells. Using genetics-based lineage tracing in zebrafish, we find that these fin mesenchyme cells derive entirely from the mesoderm and that neural crest makes no contribution. Furthermore, contrary to previous suggestions, larval fin mesenchyme cells do not generate the skeletogenic cells of the adult fin, but persist to form fibroblasts associated with adult fin rays. Our data demonstrate that zebrafish trunk neural crest does not generate ectomesenchymal derivatives and challenge long-held ideas about trunk neural crest fate. These findings have important implications for the ontogeny and evolution of the neural crest. PMID:23739134

Lee, Raymond Teck Ho; Knapik, Ela W.; Thiery, Jean Paul; Carney, Thomas J.

2013-01-01

353

PE on YouTube – investigating participation in physical education practice  

Microsoft Academic Search

Background: In this article, students’ diverse ways of participating in physical education (PE) practice shown in clips on YouTube were investigated. YouTube is the largest user-generated video-sharing website on the Internet, where different video content is presented. The clips on YouTube, as used in this paper, can be seen as a user-generated archive of ongoing PE practices that can enrich

Mikael Quennerstedt

2012-01-01

354

Learning from YouTube [Video Book  

ERIC Educational Resources Information Center

YouTube is a mess. YouTube is for amateurs. YouTube dissolves the real. YouTube is host to inconceivable combos. YouTube is best for corporate-made community. YouTube is badly baked. These are a few of the things Media Studies professor Alexandra Juhasz (and her class) learned about YouTube when she set out to investigate what actually happens…

Juhasz, Alexandra

2011-01-01

355

Integrable Background Geometries  

NASA Astrophysics Data System (ADS)

This work has its origins in an attempt to describe systematically the integrable geometries and gauge theories in dimensions one to four related to twistor theory. In each such dimension, there is a nondegenerate integrable geometric structure, governed by a nonlinear integrable differential equation, and each solution of this equation determines a background geometry on which, for any Lie group G, an integrable gauge theory is defined. In four dimensions, the geometry is selfdual conformal geometry and the gauge theory is selfdual Yang-Mills theory, while the lower-dimensional structures are nondegenerate (i.e., non-null) reductions of this. Any solution of the gauge theory on a k-dimensional geometry, such that the gauge group H acts transitively on an ?-manifold, determines a (k+?)-dimensional geometry (k+??4) fibering over the k-dimensional geometry with H as a structure group. In the case of an ?-dimensional group H acting on itself by the regular representation, all (k+?)-dimensional geometries with symmetry group H are locally obtained in this way. This framework unifies and extends known results about dimensional reductions of selfdual conformal geometry and the selfdual Yang-Mills equation, and provides a rich supply of constructive methods. In one dimension, generalized Nahm equations provide a uniform description of four pole isomonodromic deformation problems, and may be related to the {SU}(?) Toda and dKP equations via a hodograph transformation. In two dimensions, the {Diff}(S^1) Hitchin equation is shown to be equivalent to the hyperCR Einstein-Weyl equation, while the {SDiff}(?^2) Hitchin equation leads to a Euclidean analogue of Plebanski's heavenly equations. In three and four dimensions, the constructions of this paper help to organize the huge range of examples of Einstein-Weyl and selfdual spaces in the literature, as well as providing some new ! ones. The nondegenerate reductions have a long ancestry. More ! recently , degenerate or null reductions have attracted increased interest. Two of these reductions and their gauge theories (arguably, the two most significant) are also described.

Calderbank, David M. J.

2014-03-01

356

Contextual behavior and neural circuits  

PubMed Central

Animals including humans engage in goal-directed behavior flexibly in response to items and their background, which is called contextual behavior in this review. Although the concept of context has long been studied, there are differences among researchers in defining and experimenting with the concept. The current review aims to provide a categorical framework within which not only the neural mechanisms of contextual information processing but also the contextual behavior can be studied in more concrete ways. For this purpose, we categorize contextual behavior into three subcategories as follows by considering the types of interactions among context, item, and response: contextual response selection, contextual item selection, and contextual item–response selection. Contextual response selection refers to the animal emitting different types of responses to the same item depending on the context in the background. Contextual item selection occurs when there are multiple items that need to be chosen in a contextual manner. Finally, when multiple items and multiple contexts are involved, contextual item–response selection takes place whereby the animal either chooses an item or inhibits such a response depending on item–context paired association. The literature suggests that the rhinal cortical regions and the hippocampal formation play key roles in mnemonically categorizing and recognizing contextual representations and the associated items. In addition, it appears that the fronto-striatal cortical loops in connection with the contextual information-processing areas critically control the flexible deployment of adaptive action sets and motor responses for maximizing goals. We suggest that contextual information processing should be investigated in experimental settings where contextual stimuli and resulting behaviors are clearly defined and measurable, considering the dynamic top-down and bottom-up interactions among the neural systems for contextual behavior. PMID:23675321

Lee, Inah; Lee, Choong-Hee

2013-01-01

357

Neural networks in seismic discrimination  

SciTech Connect

Neural networks are powerful and elegant computational tools that can be used in the analysis of geophysical signals. At Lawrence Livermore National Laboratory, we have developed neural networks to solve problems in seismic discrimination, event classification, and seismic and hydrodynamic yield estimation. Other researchers have used neural networks for seismic phase identification. We are currently developing neural networks to estimate depths of seismic events using regional seismograms. In this paper different types of network architecture and representation techniques are discussed. We address the important problem of designing neural networks with good generalization capabilities. Examples of neural networks for treaty verification applications are also described.

Dowla, F.U.

1995-01-01

358

Piezoelectric Rotary Tube Motor  

NASA Technical Reports Server (NTRS)

A custom rotary SQUIGGLE(Registered TradeMark) motor has been developed that sets new benchmarks for small motor size, high position resolution, and high torque without gear reduction. Its capabilities cannot be achieved with conventional electromagnetic motors. It consists of piezoelectric plates mounted on a square flexible tube. The plates are actuated via voltage waveforms 90 out of phase at the resonant frequency of the device to create rotary motion. The motors were incorporated into a two-axis postioner that was designed for fiber-fed spectroscopy for ground-based and space-based projects. The positioner enables large-scale celestial object surveys to take place in a practical amount of time.

Fisher, Charles D.; Badescu, Mircea; Braun, David F.; Culhane, Robert

2011-01-01

359

Drop tube research  

NASA Technical Reports Server (NTRS)

This report covers the activities performed in the Drop Tube Study which The University of Alabama in Huntsville designed, fabricated and performed various low gravity experiments in materials processing from November 1, 1991 through October 30, 1992. During the performance of this contract the utilization of these ground-based containerless processing facilities has been instrumental in providing the opportunity to determine the feasibility of performing a number of solidification experiments in a simulated space environment, without the expense of a space-based experiment. A number of periodic reports have been given to the TCOR during the course of this contract hence this final report is meant only to summarize the many activities performed and not redundantly cover materials already submitted.

Workman, Gary L.

1992-01-01

360

Drop tube technical tasks  

NASA Technical Reports Server (NTRS)

Criteria, using fundamental thermochemical dynamics, were developed to assist a scientist using the Drop Tube Facility in designing a good experiment. The types of parameters involved in designing the experiments include the type of furnace, the type of atmosphere, and in general which materials are better behaved than others as determined by past experience in the facility. One of the major advantages of the facility lies in its ability to provide large undercoolings in the cooling curve during the drops. A beginning was to consider the effect of oxygen and other gases upon the amount of undercooling observed. The starting point of the thermochemistry was given by Ellingham and later transformed into what is known as the Richardson Chart. The effect of surface oxidations upon the nucleation phenomena can be observed in each specimen.

Workman, G. L.

1986-01-01

361

Distinct short-range ovule signals attract or repel Arabidopsis thaliana pollen tubes in vitro  

Microsoft Academic Search

BACKGROUND: Pollen tubes deliver sperm after navigating through flower tissues in response to attractive and repulsive cues. Genetic analyses in maize and Arabidopsis thaliana and cell ablation studies in Torenia fournieri have shown that the female gametophyte (the 7-celled haploid embryo sac within an ovule) and surrounding diploid tissues are essential for guiding pollen tubes to ovules. The variety and

Ravishankar Palanivelu; Daphne Preuss

2006-01-01

362

Use of Endotracheal Tube Electrodes in Treating Glossopharyngeal Neuralgia: Technical Note  

Microsoft Academic Search

Background\\/Aims: This paper describes the use of endotracheal tube surface electrodes to help delineate the sensory and motor vagal rootlets which may be sacrificed during the surgical treatment of glossopharyngeal neuralgia. Methods: Three patients with glossopharyngeal neuralgia were studied. All patients had their procedure under general anesthesia and a nerve integrity monitor electromyography endotracheal tube (Medtronic Xomed, Jacksonville, Fla., USA)

Anwen M. Harries; Charles C. J. Dong; Christopher R. Honey

2012-01-01

363

Xenopus ADAM 13 is a metalloprotease required for cranial neural crest-cell migration  

Microsoft Academic Search

Background: Cranial neural-crest (CNC) cells originate from the lateral edge of the anterior neuroepithelium and migrate to form parts of the peripheral nervous system, muscles, cartilage, and bones of the face. Neural crest-cell migration involves the loss of adhesion from the surrounding neuroepithelium and a corresponding increase in cell adhesion to the extracellular matrix (ECM) present in migratory pathways. While

Dominique Alfandari; Hélčne Cousin; Alban Gaultier; Katherine Smith; Judith M White; Thierry Darribčre; Douglas W DeSimone

2001-01-01

364

Neural Response to Alcohol Stimuli in Adolescents With Alcohol Use Disorder  

Microsoft Academic Search

Background: Cue reactivity studies in alcohol- dependent adults have shown atypical physiological, cog- nitive, and neural responses to alcohol-related stimuli that differ from the responses of light drinkers. Cue reactiv- ity and its neural substrates are unclear in youth. We hy- pothesized that teens with alcohol use disorder would show greater brain response than nonabusing teens to alcohol images relative

Susan. F. Tapert; Erick H. Cheung; Gregory G. Brown; Lawrence R. Frank; Martin P. Paulus; Alecia D. Schweinsburg; M. J. Meloy; Sandra A. Brown

2003-01-01

365

Research paper Musicians change their tune: How hearing loss alters the neural code  

E-print Network

auditory perceptual skills, including speech-in-noise perception, coupled with heightened subcortical-aged adults with hearing loss. Results indicate that musicians with hearing loss, despite self-perceptions of background noise (e.g., neural timing). Musicians with hearing loss also demonstrate unique neural signatures

Kraus, Nina

366

Reconfigurable Control Design with Neural Network Augmentation for a Modified F-15 Aircraft  

NASA Technical Reports Server (NTRS)

The viewgraphs present background information about reconfiguration control design, design methods used for paper, control failure survivability results, and results and time histories of tests. Topics examined include control reconfiguration, general information about adaptive controllers, model reference adaptive control (MRAC), the utility of neural networks, radial basis functions (RBF) neural network outputs, neurons, and results of investigations of failures.

Burken, John J.

2007-01-01

367

High school music classes enhance the neural processing of speech  

PubMed Central

Should music be a priority in public education? One argument for teaching music in school is that private music instruction relates to enhanced language abilities and neural function. However, the directionality of this relationship is unclear and it is unknown whether school-based music training can produce these enhancements. Here we show that 2 years of group music classes in high school enhance the neural encoding of speech. To tease apart the relationships between music and neural function, we tested high school students participating in either music or fitness-based training. These groups were matched at the onset of training on neural timing, reading ability, and IQ. Auditory brainstem responses were collected to a synthesized speech sound presented in background noise. After 2 years of training, the neural responses of the music training group were earlier than at pre-training, while the neural timing of students in the fitness training group was unchanged. These results represent the strongest evidence to date that in-school music education can cause enhanced speech encoding. The neural benefits of musical training are, therefore, not limited to expensive private instruction early in childhood but can be elicited by cost-effective group instruction during adolescence. PMID:24367339

Tierney, Adam; Krizman, Jennifer; Skoe, Erika; Johnston, Kathleen; Kraus, Nina

2013-01-01

368

Helical tubes in crowded environments.  

PubMed

When placed in a crowded environment, a semiflexible tube is forced to fold so as to make a more compact shape. One compact shape that often arises in nature is the tight helix, especially when the tube thickness is of comparable size to the tube length. In this paper we use an excluded volume effect to model the effects of crowding. This gives us a measure of compactness for configurations of the tube, which we use to look at structures of the semiflexible tube that minimize the excluded volume. We focus most of our attention on the helix and which helical geometries are most compact. We found helices of specific pitch to radius ratio 2.512 to be optimally compact. This is the same geometry that minimizes the global curvature of the curve defining the tube. We further investigate the effects of adding a bending energy or multiple tubes to begin to explore the more complete space of possible geometries a tube could form. PMID:17677029

Snir, Yehuda; Kamien, Randall D

2007-05-01

369

A reflux tube fabric radiator  

Microsoft Academic Search

An alternative heat rejection system is possible that will meet survivability criteria while greatly enhancing space nuclear power systems. This alternative radiator design, the reflux tube fabric radiator, uses light weight high strength fabric materials, relies on an induced artificial gravity, and builds on the long established technologies associated with reflux tubes and thermosyphons, the predecessors of the modern microgravity

Edmund P. Coomes; Joseph M. Kelly

1988-01-01

370

Benefits of coextruded micro tubing.  

PubMed

Coextruded tubing products offer additional functions through multiple material combinations and facilitate secondary assembly processes. This article presents four applications in which coextruded micro tubings have solved problems and reaped significant advantages: infusion therapy, regional anaesthesia, micro dialysis and parenteral feeding. PMID:19626950

Ziembinski, R

2009-01-01

371

The neural decoding toolbox.  

PubMed

Population decoding is a powerful way to analyze neural data, however, currently only a small percentage of systems neuroscience researchers use this method. In order to increase the use of population decoding, we have created the Neural Decoding Toolbox (NDT) which is a Matlab package that makes it easy to apply population decoding analyses to neural activity. The design of the toolbox revolves around four abstract object classes which enables users to interchange particular modules in order to try different analyses while keeping the rest of the processing stream intact. The toolbox is capable of analyzing data from many different types of recording modalities, and we give examples of how it can be used to decode basic visual information from neural spiking activity and how it can be used to examine how invariant the activity of a neural population is to stimulus transformations. Overall this toolbox will make it much easier for neuroscientists to apply population decoding analyses to their data, which should help increase the pace of discovery in neuroscience. PMID:23734125

Meyers, Ethan M

2013-01-01

372

Enhanced tubes for electric utility steam condensers  

Microsoft Academic Search

Electric utility steam condensers typically use plain tubes made of titanium, stainless steel, or copper alloys. Approximately two-thirds of the total thermal resistance is on the water side of the plain tube. This program seeks to conceive and develop a tube geometry that has special enhancement geometries on the tube (water) side and the steam (shell) side. This enhanced'' tube

R. L. Webb; H. Jaber; L. Chamra; Nae-Hyun Kim

1990-01-01

373

Calculation of the Pitot tube correction factor for Newtonian and non-Newtonian fluids.  

PubMed

This paper presents the numerical investigation performed to calculate the correction factor for Pitot tubes. The purely viscous non-Newtonian fluids with the power-law model constitutive equation were considered. It was shown that the power-law index, the Reynolds number, and the distance between the impact and static tubes have a major influence on the Pitot tube correction factor. The problem was solved for a wide range of these parameters. It was shown that employing Bernoulli's equation could lead to large errors, which depend on the magnitude of the kinetic energy and energy friction loss terms. A neural network model was used to correlate the correction factor of a Pitot tube as a function of these three parameters. This correlation is valid for most Newtonian, pseudoplastic, and dilatant fluids at low Reynolds number. PMID:14582876

Etemad, S Gh; Thibault, J; Hashemabadi, S H

2003-10-01

374

MAR Background Report MAR Background Report: Indigenous Protest in Brazil  

E-print Network

MAR Background Report MAR Background Report: Indigenous Protest in Brazil Hundreds of indigenous. According to MAR data, several violent incidents against landowners, miners and others have been observed groups worldwide #12;MAR Background Report About the Minorities at Risk Project The Minorities at Risk

Milchberg, Howard

375

MAR Background Report MAR Background Report: The Revolution in Bahrain  

E-print Network

MAR Background Report MAR Background Report: The Revolution in Bahrain Unrest in Tunisia, Egypt forces. MAR data also reports that social services in Shi'a neighborhoods are inferior to those in Sunni of ethnic groups worldwide #12;MAR Background Report In Bahrain, the freedom of press and expression

Milchberg, Howard

376

Supramolecular architectures for neural prostheses  

E-print Network

Neural prosthetic devices offer a means of restoring function that have been lost due to neural damage. The first part of this thesis investigates the design of a 15-channel, low-power, fully implantable stimulator chip. ...

Theogarajan, Luke Satish Kumar

2007-01-01

377

Deconvolution using a neural network  

SciTech Connect

Viewing one dimensional deconvolution as a matrix inversion problem, we compare a neural network backpropagation matrix inverse with LMS, and pseudo-inverse. This is a largely an exercise in understanding how our neural network code works. 1 ref.

Lehman, S.K.

1990-11-15

378

In Ovo Electroporation as a Useful Tool to Pursue Molecular Mechanisms of Neural Development in Chick Embryos  

NASA Astrophysics Data System (ADS)

In the field of developmental biology, electroporation has become a routine technique for gene transfer because of its simplicity and wide range of application. In chick embryos, the in ovo electroporation technique has enabled molecular analysis of developmental mechanisms in chick embryos and has revived chick embryos as the model animals in developmental biology (Muramatsu et al., 1997; Sakamoto et al., 1998; Funahashi et al., 1999; Nakamura et al., 2000). Especially, many gene analyses were conducted in developing neural tube, because the neural tube is a convenient tissue for application of in ovo electroporation. Here, we show the application of in ovo electroporation to the developmental neural tube in chick embryo. electroporation, only the anode side is transfected and the cathode side could be used as the control (Funahashi et al., 1999; Nakamura et al., 2000; Odani et al., 2008).

Odani, Noritaka; Hou, Xubin; Nakamura, Harukazu

379

The ''neural'' phonetic typewriter  

SciTech Connect

Recently, researchers have placed great hopes on artificial neural networks to perform such ''natural'' tasks as speech recognition. This was indeed one motivation for us to start research in this area many years ago at Helsinki University of Technology. This article describes the result of that research - a complete ''neural'' speech recognition system, which recognizes phonetic units, called phonemes, from a continuous speech signal. Although motivated by neural network principles, the choices in design must be regarded as a compromise of many technical aspects of those principles. As our system is a genuine ''phonetic typewriter'' intended to transcribe orthographically edited text from an unlimited vocabulary, it cannot be directed compared with any more conventional, word-based system that applies classical concepts such as dynamic time warping and hidden Markov models.

Kohonen, T.

1988-03-01

380

Cognitive Neural Prosthetics  

PubMed Central

The cognitive neural prosthetic (CNP) is a very versatile method for assisting paralyzed patients and patients with amputations. The CNP records the cognitive state of the subject, rather than signals strictly related to motor execution or sensation. We review a number of high-level cortical signals and their application for CNPs, including intention, motor imagery, decision making, forward estimation, executive function, attention, learning, and multi-effector movement planning. CNPs are defined by the cognitive function they extract, not the cortical region from which the signals are recorded. However, some cortical areas may be better than others for particular applications. Signals can also be extracted in parallel from multiple cortical areas using multiple implants, which in many circumstances can increase the range of applications of CNPs. The CNP approach relies on scientific understanding of the neural processes involved in cognition, and many of the decoding algorithms it uses also have parallels to underlying neural circuit functions. PMID:19575625

Andersen, Richard A.; Hwang, Eun Jung; Mulliken, Grant H.

2010-01-01

381

Distinct short-range ovule signals attract or repel Arabidopsis thaliana pollen tubes in vitro  

PubMed Central

Background Pollen tubes deliver sperm after navigating through flower tissues in response to attractive and repulsive cues. Genetic analyses in maize and Arabidopsis thaliana and cell ablation studies in Torenia fournieri have shown that the female gametophyte (the 7-celled haploid embryo sac within an ovule) and surrounding diploid tissues are essential for guiding pollen tubes to ovules. The variety and inaccessibility of these cells and tissues has made it challenging to characterize the sources of guidance signals and the dynamic responses they elicit in the pollen tubes. Results Here we developed an in vitro assay to study pollen tube guidance to excised A. thaliana ovules. Using this assay we discerned the temporal and spatial regulation and species-specificity of late stage guidance signals and characterized the dynamics of pollen tube responses. We established that unfertilized A. thaliana ovules emit diffusible, developmentally regulated, species-specific attractants, and demonstrated that ovules penetrated by pollen tubes rapidly release diffusible pollen tube repellents. Conclusion These results demonstrate that in vitro pollen tube guidance to excised A. thaliana ovules efficiently recapitulates much of in vivo pollen tube behaviour during the final stages of pollen tube growth. This assay will aid in confirming the roles of candidate guidance molecules, exploring the phenotypes of A. thaliana pollen tube guidance mutants and characterizing interspecies pollination interactions. PMID:16595022

Palanivelu, Ravishankar; Preuss, Daphne

2006-01-01

382

Background issues for defensive interceptors.  

National Technical Information Service (NTIS)

Mean nuclear backgrounds are large, but are arguably amenable to frame-to-frame subtraction. Striated backgrounds on the sensors for defensive interceptors could, however, cause clutter leak-through, which could make detection and track difficult. Nominal...

G. H. Canavan

1991-01-01

383

Neural nets on the MPP  

NASA Technical Reports Server (NTRS)

The Massively Parallel Processor (MPP) is an ideal machine for computer experiments with simulated neural nets as well as more general cellular automata. Experiments using the MPP with a formal model neural network are described. The results on problem mapping and computational efficiency apply equally well to the neural nets of Hopfield, Hinton et al., and Geman and Geman.

Hastings, Harold M.; Waner, Stefan

1987-01-01

384

Neural networks: an engineering perspective  

Microsoft Academic Search

The development and application of neural networks are presented from an engineering perspective. It is stated that neural computing is a collection of mathematical techniques that have been gaining growing acceptance as plug-compatible replacements for statistical and other data-modeling techniques. Two of these techniques, function approximation and clustering, are discussed. The forces shaping the future of neural networking systems, including

C. C. Klimasauskas

1992-01-01

385

Neural processing of itch  

PubMed Central

While considerable effort has been made to investigate the neural mechanisms of pain, much less effort has been devoted to itch, at least until recently. However, itch is now gaining increasing recognition as a widespread and costly medical and socioeconomic issue. This is accompanied by increasing interest in the underlying neural mechanisms of itch, which has become a vibrant and rapidly-advancing field of research. The goal of the present forefront review is to describe the recent progress that has been made in our understanding of itch mechanisms. PMID:23891755

Akiyama, Tasuku; Carstens, E.

2013-01-01

386

Sieve Tubes in Action  

PubMed Central

Abstract A method was designed for in vivo observation of sieve element/companion complexes by using confocal laser scanning microscopy. A leaf attached to an intact fava bean plant was mounted upside down on the stage of a confocal microscope. Two shallow paradermal cortical cuts were made in the major vein. The basal cortical window allowed us to observe the phloem intact. The apical window at 3 cm from the site of observation was used to apply phloem-mobile fluorochromes, which identified living sieve elements at the observation site. In intact sieve tubes, the sieve plates did not present a barrier to mass flow, because the translocation of fluorochromes appeared to be unhindered. Two major occlusion mechanisms were distinguished. In response to intense laser light, the parietal proteins detached from the plasma membrane and formed a network of minute strands and clustered material that aggregated and pressed against the sieve plate. In response to mechanical damage, the evenly distributed P plastids exploded, giving rise to the formation of a massive plug against the sieve plate. In case of mechanical damage, the parietal proteins transformed into elastic threads (strands) that extended throughout the sieve element lumen. Our observations cover the phenomena encountered in previous microscopic and electron microscopic studies and provide a temporal disentanglement of the events giving rise to the confusing mass of structures observed thus far.

Knoblauch, M.; van Bel, A. J. E.

1998-01-01

387

Tubing drain valve  

SciTech Connect

A method is described for operating a valve means. The valve means comprises a tubular piston movable within a tubular member suitable for use in a borehole pipe string to open and close a port through the wall of the tubular member. The method comprises: biassing the valve means in its closed position; pressurizing the interior of the piston to a predetermined pressure to overcome the biassing closed force and to actuate the valve means to its open position; biassing the valve means to its open position; and actuating the valve means to its closed position by engaging a first arm of a dog pivotally mounted on the piston with an engaging means insertable through the interior of the tubular piston; moving the piston relative to the tubular member; rotating the dog about its pivot to bring a second arm of the dog into contact with a detent in the tubular member; and applying sufficient force to the first arm to continue rotating the dog about the pivot, while engaging the detent with the second arm of the dog, in order to overcome the biassing open force to actuate the valve means to its closed position. A tubing drain valve suitable for use in a borehole pipe string, comprising: a sub suitable for incorporating within a borehole pipe string; and a port between the interior and the exterior of the sub; and valve means for opening and closing the port.

Soderberg, P.B.

1987-02-24

388

Internal and External Radioactive Backgrounds  

E-print Network

Chapter 3 Internal and External Radioactive Backgrounds New physics is often discovered by pushing of the low energies involved. There are many radioactive elements that have decays at lower energies which;Chapter 3: Internal and External Radioactive Backgrounds 104 the rate of background. High-energy neutrino

389

REPORT NO. 5 background material  

E-print Network

REPORT NO. 5 background material for the development of radiation protection standards July 1964 Staff Report of the FEDERAL RADIATION COUNCIL #12;REPORT NO. 5 background material for the development INTRODUCTION This report contains background material used in the development of guidance for Federal agencies

390

Water-storage-tube systems. Final report  

SciTech Connect

Passive solar collection/storage/distribution systems were surveyed, designed, fabricated, and mechanically and thermally tested. The types studied were clear and opaque fiberglass tubes, metal tubes with plastic liners, and thermosyphoning tubes. (MHR)

Hemker, P.

1981-12-24

391

27 CFR 40.352 - Cigarette tubes.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Cigarette tubes. 40.352 Section 40.352... MANUFACTURE OF TOBACCO PRODUCTS, CIGARETTE PAPERS AND TUBES, AND PROCESSED TOBACCO Manufacture of Cigarette Papers and Tubes Taxes §...

2010-04-01

392

Vidicon storage tube electrical input/output  

NASA Technical Reports Server (NTRS)

Electrical data storage tube is assembled from standard vidicon tube using conventional amplification and control circuits. Vidicon storage tube is simple, inexpensive and has an erase and preparation time of less than 5 microseconds.

Lipoma, P.

1972-01-01

393

27 CFR 41.35 - Cigarette tubes.  

Code of Federal Regulations, 2011 CFR

...TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY (CONTINUED) TOBACCO IMPORTATION OF TOBACCO PRODUCTS, CIGARETTE PAPERS AND TUBES, AND PROCESSED TOBACCO Taxes Tax Rates § 41.35 Cigarette tubes. Cigarette tubes...

2011-04-01

394

27 CFR 41.35 - Cigarette tubes.  

Code of Federal Regulations, 2012 CFR

...TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY (CONTINUED) TOBACCO IMPORTATION OF TOBACCO PRODUCTS, CIGARETTE PAPERS AND TUBES, AND PROCESSED TOBACCO Taxes Tax Rates § 41.35 Cigarette tubes. Cigarette tubes...

2012-04-01

395

27 CFR 41.35 - Cigarette tubes.  

...TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY (CONTINUED) TOBACCO IMPORTATION OF TOBACCO PRODUCTS, CIGARETTE PAPERS AND TUBES, AND PROCESSED TOBACCO Taxes Tax Rates § 41.35 Cigarette tubes. Cigarette tubes...

2014-04-01

396

27 CFR 41.35 - Cigarette tubes.  

Code of Federal Regulations, 2013 CFR

...TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY (CONTINUED) TOBACCO IMPORTATION OF TOBACCO PRODUCTS, CIGARETTE PAPERS AND TUBES, AND PROCESSED TOBACCO Taxes Tax Rates § 41.35 Cigarette tubes. Cigarette tubes...

2013-04-01

397

Characterization of domestic and foreign image intensifier tubes  

NASA Astrophysics Data System (ADS)

The market for military-use Generation 2 and Generation 3 image intensifier (I2) tubes has become truly global, with major manufacturers and customers spanning five continents. This worldwide market is becoming increasingly important to U.S. manufacturers, with the majority of U.S. Army intensifier fielding having been completed in 2012. Given this keen global competition, it is not surprising that the advertised tube performance of a given source is often discounted by competitors, and the customers have no objective "honest broker" to determine the relative accuracy of these claims. To help fill this void, the U.S. Army RDECOM CERDEC NVESD recently measured a number of domestic and foreign image intensifier tubes, using consistent test equipment/procedures with which the U.S. industry must correlate for Army tube deliveries. Data and analysis will be presented for the major tube parameters of luminance gain, equivalent background input (EBI), signal-to-noise ratio (SNR), limiting resolution, halo, and modulation transfer function (MTF). The bright-light resolution provided by various auto-gated and non-gated tubes will also be addressed, since this area has been an important factor in the international market. RDECOM CERDEC NVESD measurement data will be compared to the corresponding manufacturer specifications whenever possible.

Bender, Edward J.; Wood, Michael V.; Hosek, Daniel J.; Hart, Steve D.

2013-06-01

398

Early regulative ability of the neuroepithelium to form cardiac neural crest  

PubMed Central

The cardiac neural crest (arising from the level of hindbrain rhombomeres 6–8) contributes to the septation of the cardiac outflow tract and the formation of aortic arches. Removal of this population after neural tube closure results in severe septation defects in the chick, reminiscent of human birth defects. Because neural crest cells from other axial levels have regenerative capacity, we asked whether the cardiac neural crest might also regenerate at early stages in a manner that declines with time. Accordingly, we find that ablation of presumptive cardiac crest at stage 7, as the neural folds elevate, results in reformation of migrating cardiac neural crest by stage 13. Fate mapping reveals that the new population derives largely from the neuroepithelium ventral and rostral to the ablation. The stage of ablation dictates the competence of residual tissue to regulate and regenerate, as this capacity is lost by stage 9, consistent with previous reports. These findings suggest that there is a temporal window during which the presumptive cardiac neural crest has the capacity to regulate and regenerate, but this regenerative ability is lost earlier than in other neural crest populations. PMID:21047505

Ezin, Akouavi M.; Sechrist, John W.; Zah, Angela; Bronner, Marianne; Fraser, Scott E.

2010-01-01

399

Electrospun micro- and nanofiber tubes for functional nervous regeneration in sciatic nerve transections  

PubMed Central

Background Although many nerve prostheses have been proposed in recent years, in the case of consistent loss of nervous tissue peripheral nerve injury is still a traumatic pathology that may impair patient's movements by interrupting his motor-sensory pathways. In the last few decades tissue engineering has opened the door to new approaches;: however most of them make use of rigid channel guides that may cause cell loss due to the lack of physiological local stresses exerted over the nervous tissue during patient's movement. Electrospinning technique makes it possible to spin microfiber and nanofiber flexible tubular scaffolds composed of a number of natural and synthetic components, showing high porosity and remarkable surface/volume ratio. Results In this study we used electrospun tubes made of biodegradable polymers (a blend of PLGA/PCL) to regenerate a 10-mm nerve gap in a rat sciatic nerve in vivo. Experimental groups comprise lesioned animals (control group) and lesioned animals subjected to guide conduits implantated at the severed nerve stumps, where the tubular scaffolds are filled with saline solution. Four months after surgery, sciatic nerves failed to reconnect the two stumps of transected nerves in the control animal group. In most of the treated animals the electrospun tubes induced nervous regeneration and functional reconnection of the two severed sciatic nerve tracts. Myelination and collagen IV deposition have been detected in concurrence with regenerated fibers. No significant inflammatory response has been found. Neural tracers revealed the re-establishment of functional neuronal connections and evoked potential results showed the reinnervation of the target muscles in the majority of the treated animals. Conclusion Corroborating previous works, this study indicates that electrospun tubes, with no additional biological coating or drug loading treatment, are promising scaffolds for functional nervous regeneration. They can be knitted in meshes and various frames depending on the cytoarchitecture of the tissue to be regenerated. The versatility of this technique gives room for further scaffold improvements, like tuning the mechanical properties of the tubular structure or providing biomimetic functionalization. Moreover, these guidance conduits can be loaded with various fillers like collagen, fibrin, or self-assembling peptide gels or loaded with neurotrophic factors and seeded with cells. Electrospun scaffolds can also be synthesized in different micro-architectures to regenerate lesions in other tissues like skin and bone. PMID:18405347

Panseri, Silvia; Cunha, Carla; Lowery, Joseph; Del Carro, Ubaldo; Taraballi, Francesca; Amadio, Stefano; Vescovi, Angelo; Gelain, Fabrizio

2008-01-01

400

Rijke tube with flexible walls  

NASA Astrophysics Data System (ADS)

Sound is excited spontaneously in a Rijke tube because the small temperature perturbations in an acoustic field interact with heat transfer from a heat source in the tube. The air particles near the heat source undergo a thermodynamic cyle converting heat to mechanical energy, which is heard as the sound emanating from the Rijke tube. This principle of energy conversion is used in thermoacoustic engines, and the main objective of this study is to improve their performance. The acoustic oscillations in the Rijke tube regulate the thermodynamic cycle, just as in conventional engines the cycle is controlled by the motion of a piston and the action of inlet and exit valves. The acoustic regulation in the Rijke tube, however, does not allow arbitrary control of the cycle in thermodynamic phase space. In this presentation, we introduce a new way of overcoming this limitation, one by using Rijke tubes with flexible walls. We will discuss how this modification allows for more general thermodynamic cycles to be executed by the air particles in the tube. This possibility, when used in thermoacoustic engines, opens a channel for further improving the engine performance.

Mandre, Shreyas; Nguyen, Bao-Nhat; Li, Marvin

2011-11-01

401

The "prawn-in-the-tube" procedure: what do cuttlefish learn and memorize?  

PubMed

For several decades the "prawn-in-the-tube" procedure has been extensively used in the exploration of behavioral plasticity and its neural correlates in cuttlefish. Although the nature of the task has been characterized, the effect of reinforcement and the extent of different cues cuttlefish can use to solve and memorize the task remain unclear. To determine whether cuttlefish learned to inhibit predatory behavior because of pain incurred when the tentacles hit the glass tube, the shrimp prey (typically attacked with a tentacle strike) was replaced by crabs (normally caught by a jumping strategy, using all eight arms together, which is thought less likely to be painful). We showed that the cuttlefish is still capable of learning inhibition of predatory behavior when it adopts another catching strategy, which suggests that pain from the tentacles hitting the tube has little effect on the learning process. The two latest experiments have shown that cuttlefish do not learn to inhibit predatory behavior towards a specific type of prey, but rather learn and memorize visual (light polarization) and tactile information from the glass tube. The "prawn-in-the-tube" procedure is a powerful and user-friendly tool in the investigation of the processing and retention of multisensory information in invertebrates. Our recent findings now open up new areas of investigation into the neural correlates of learning and memory processes in cuttlefish. PMID:23178535

Cartron, Lelia; Darmaillacq, Anne-Sophie; Dickel, Ludovic

2013-03-01

402

Variation in the schedules of somite and neural development in frogs  

PubMed Central

The timing of notochord, somite, and neural development was analyzed in the embryos of six different frog species, which have been divided into two groups, according to their developmental speed. Rapid developing species investigated were Xenopus laevis (Pipidae), Engystomops coloradorum, and Engystomops randi (Leiuperidae). The slow developers were Epipedobates machalilla and Epipedobates tricolor (Dendrobatidae) and Gastrotheca riobambae (Hemiphractidae). Blastopore closure, notochord formation, somite development, neural tube closure, and the formation of cranial neural crest cell-streams were detected by light and scanning electron microscopy and by immuno-histochemical detection of somite and neural crest marker proteins. The data were analyzed using event pairing to determine common developmental aspects and their relationship to life-history traits. In embryos of rapidly developing frogs, elongation of the notochord occurred earlier relative to the time point of blastopore closure in comparison with slowly developing species. The development of cranial neural crest cell-streams relative to somite formation is accelerated in rapidly developing frogs, and it is delayed in slowly developing frogs. The timing of neural tube closure seemed to be temporally uncoupled with somite formation. We propose that these changes are achieved through differential timing of developmental modules that begin with the elongation of the notochord during gastrulation in the rapidly developing species. The differences might be related to the necessity of developing a free-living tadpole quickly in rapid developers. PMID:23184997

Saenz-Ponce, Natalia; Mitgutsch, Christian; del Pino, Eugenia M.

2012-01-01

403

Variation in the schedules of somite and neural development in frogs.  

PubMed

The timing of notochord, somite, and neural development was analyzed in the embryos of six different frog species, which have been divided into two groups, according to their developmental speed. Rapid developing species investigated were Xenopus laevis (Pipidae), Engystomops coloradorum, and Engystomops randi (Leiuperidae). The slow developers were Epipedobates machalilla and Epipedobates tricolor (Dendrobatidae) and Gastrotheca riobambae (Hemiphractidae). Blastopore closure, notochord formation, somite development, neural tube closure, and the formation of cranial neural crest cell-streams were detected by light and scanning electron microscopy and by immuno-histochemical detection of somite and neural crest marker proteins. The data were analyzed using event pairing to determine common developmental aspects and their relationship to life-history traits. In embryos of rapidly developing frogs, elongation of the notochord occurred earlier relative to the time point of blastopore closure in comparison with slowly developing species. The development of cranial neural crest cell-streams relative to somite formation is accelerated in rapidly developing frogs, and it is delayed in slowly developing frogs. The timing of neural tube closure seemed to be temporally uncoupled with somite formation. We propose that these changes are achieved through differential timing of developmental modules that begin with the elongation of the notochord during gastrulation in the rapidly developing species. The differences might be related to the necessity of developing a free-living tadpole quickly in rapid developers. PMID:23184997

Sáenz-Ponce, Natalia; Mitgutsch, Christian; del Pino, Eugenia M

2012-12-11

404

Microwave vacuum tubes for satellite radio  

Microsoft Academic Search

The present article discusses some of the general principles of microwave tubes and describes the traveling-wave tube (TWT) in detail. Beam-density-controlled tubes, transit-time tubes, drift tubes or klystrons, and the magnetron are also briefly explained. The mode of operation, special satellite requirements, service life, reliability, efficiency, and weight of the traveling-wave tube, as well as data on one TWT already

H. Rothfuss

1975-01-01

405

Cardiac neural crest is necessary for normal addition of the myocardium to the arterial pole from the secondary heart field  

Microsoft Academic Search

In cardiac neural-crest-ablated embryos, the secondary heart field fails to add myocardial cells to the outflow tract and elongation of the tube is deficient (Yelbuz, T.M., Waldo, K.L., Kumiski, D.H., Stadt, H.A., Wolfe, R.R., Leatherbury, L., Kirby, M.L., 2002. Shortened outflow tract leads to altered cardiac looping after neural crest ablation. Circ. Res. 106, 504–510.). Since that study, we have

Karen L. Waldo; Mary R. Hutson; Harriett A. Stadt; Marzena Zdanowicz; Jaroslaw Zdanowicz; Margaret L. Kirby

2005-01-01

406

Validation of adaptive threshold spike detector for neural recording.  

PubMed

We compare the performance of algorithms for automatic spike detection in neural recording applications. Each algorithm sets a threshold based on an estimate of the background noise level. The adaptive spike detection algorithm is suitable for implementation in analog VLSI; results from a proof-of-concept chip using neural data are presented. We also present simulation results of algorithm performance on neural data and compare it to other methods of threshold level adjustment based on the root-mean-square (rms) voltage measured over a finite window. We show that the adaptive spike detection algorithm measures the background noise level accurately despite the presence of large-amplitude action potentials and multi-unit hash. Simulation results enable us to optimize the algorithm parameters, leading to an improved spike detector circuit that is currently being developed. PMID:17271196

Watkins, Paul T; Santhanam, Gopal; Shenoy, Krishna V; Harrison, Reid R

2004-01-01

407

[Antibiotic prophylaxis and endoluminal tubes].  

PubMed

Surgical site infections are one of the most common complications after surgical procedures. The use of perioperative antibiotic prophylaxis can successfully reduce the number of wound infections. The indications, timing and choice of antibiotics are discussed critically. Taken together antibiotic prophylaxis should be evaluated depending on wound contamination, the type of operation and patient-specific risk factors. In the second part of this work the current literature on the effectiveness of endoluminal tubes in abdominal surgery is analyzed. While many surgeons use these tubes regularly in elective abdominal surgery, only few data are available on this topic. The use of nasogastric tubes in elective surgery should be avoided. PMID:22008844

Justinger, C; Schilling, M K

2011-12-01

408

Expansion tube test time predictions  

NASA Technical Reports Server (NTRS)

The interaction of an interface between two gases and strong expansion is investigated and the effect on flow in an expansion tube is examined. Two mechanisms for the unsteady Pitot-pressure fluctuations found in the test section of an expansion tube are proposed. The first mechanism depends on the Rayleigh-Taylor instability of the driver-test gas interface in the presence of a strong expansion. The second mechanism depends on the reflection of the strong expansion from the interface. Predictions compare favorably with experimental results. The theory is expected to be independent of the absolute values of the initial expansion tube filling pressures.

Gourlay, Christopher M.

1988-01-01

409

FatJ acts via the Hippo mediator Yap1 to restrict the size of neural progenitor cell pools  

PubMed Central

The size, composition and functioning of the spinal cord is likely to depend on appropriate numbers of progenitor and differentiated cells of a particular class, but little is known about how cell numbers are controlled in specific cell cohorts along the dorsoventral axis of the neural tube. Here, we show that FatJ cadherin, identified in a large-scale RNA interference (RNAi) screen of cadherin genes expressed in the neural tube, is localised to progenitors in intermediate regions of the neural tube. Loss of function of FatJ promotes an increase in dp4-vp1 progenitors and a concomitant increase in differentiated Lim1+/Lim2+ neurons. Our studies reveal that FatJ mediates its action via the Hippo pathway mediator Yap1: loss of downstream Hippo components can rescue the defect caused by loss of FatJ. Together, our data demonstrate that RNAi screens are feasible in the chick embryonic neural tube, and show that FatJ acts through the Hippo pathway to regulate cell numbers in specific subsets of neural progenitor pools and their differentiated progeny. PMID:21521736

Van Hateren, Nick J.; Das, Raman M.; Hautbergue, Guillaume M.; Borycki, Anne-Gaelle; Placzek, Marysia; Wilson, Stuart A.

2011-01-01

410

Neural Explant Cultures from Xenopus laevis  

PubMed Central

The complex process of axon guidance is largely driven by the growth cone, which is the dynamic motile structure at the tip of the growing axon. During axon outgrowth, the growth cone must integrate multiple sources of guidance cue information to modulate its cytoskeleton in order to propel the growth cone forward and accurately navigate to find its specific targets1. How this integration occurs at the cytoskeletal level is still emerging, and examination of cytoskeletal protein and effector dynamics within the growth cone can allow the elucidation of these mechanisms. Xenopus laevis growth cones are large enough (10-30 microns in diameter) to perform high-resolution live imaging of cytoskeletal dynamics (e.g.2-4 ) and are easy to isolate and manipulate in a lab setting compared to other vertebrates. The frog is a classic model system for developmental neurobiology studies, and important early insights into growth cone microtubule dynamics were initially found using this system5-7 . In this method8, eggs are collected and fertilized in vitro, injected with RNA encoding fluorescently tagged cytoskeletal fusion proteins or other constructs to manipulate gene expression, and then allowed to develop to the neural tube stage. Neural tubes are isolated by dissection and then are cultured, and growth cones on outgrowing neurites are imaged. In this article, we describe how to perform this method, the goal of which is to culture Xenopus laevis growth cones for subsequent high-resolution image analysis. While we provide the example of +TIP fusion protein EB1-GFP, this method can be applied to any number of proteins to elucidate their behaviors within the growth cone. PMID:23295240

Lowery, Laura Anne; Faris, Anna E.R.; Stout, Alina; Van Vactor, David

2012-01-01

411

Neural componentplacement Christopher Cherniak  

E-print Network

with a variety of connection-minimization problems with neuroanatomical applicability, for example, Steiner- tree proved, like the Steiner-tree problem, to be NP-hard, that is, at least as difficult as NP of interconnected neural components is treated like a problem of wire minimization in microchip layout, a hypothesis

Cherniak, Christopher

412

Evolving neural networks  

Microsoft Academic Search

Neural networks are parallel processing structures that provide the capability to perform various pattern recognition tasks. A network is typically trained over a set of exemplars by adjusting the weights of the interconnections using a back propagation algorithm. This gradient search converges to locally optimal solutions which may be far removed from the global optimum. In this paper, evolutionary programming

D. B. Fogel; L. J. Fogel; V. W. Porto

1990-01-01

413

The Guarded Neural Classifier  

Microsoft Academic Search

This paper presents a new approach for classifying multi-dimensional data using an artificial neural network. The proposed network is an extension of a counterpropagation net- work with two special neurons controlling (or 'guarding') the 'de- cisions' of the network - that is why it is called Guarded Neu- ral Classifier (GNC). The design of the GNC network is aimed at

Torsten Felzer; Bernd Freisleben; Martin Hoof

2001-01-01

414

Neural generalized predictive control  

Microsoft Academic Search

An efficient implementation of generalized predictive control using a multilayer feedforward neural network as the plant's nonlinear model is presented. By using Newton-Raphson as the optimization algorithm, the number of iterations needed for convergence is significantly reduced from other techniques. The main cost of the Newton-Raphson algorithm is in the calculation of the Hessian, but even with this overhead the

Donald Soloway; Pamela J. Haley

1996-01-01

415

Background  

E-print Network

This Provisional PDF corresponds to the article as it appeared upon acceptance. Fully formatted PDF and full text (HTML) versions will be made available soon. Embryonic diapause in humans: time to consider?

Grazyna E Ptak; Jacek A Modlinski; Grazyna E Ptak; Jacek A Modlinski; Pasqualino Loi

2013-01-01

416

Background  

E-print Network

Obligate intracellular bacteria commonly have much reduced genome sizes compared to their nearest free-living relatives. One reason for this is reductive evolution: the loss of genes rendered non-essential due to the intracellular habitat. This can occur because of the presence of orthologous genes in the host, combined with the ability of the bacteria to import the protein or metabolite products of the host genes. In this article we take a look at three such bacteria whose genomes have been fully sequenced. Buchnera is an endosymbiont of the pea aphid, Acyrthosiphon pisum, the relationship between these two organisms being so essential that neither can reproduce in the absence of the other. Rickettsia prowazekii is the causative agent of louse-borne typhus in humans and Mycobacterium leprae infection of humans leads to leprosy. Both of these human pathogens have fastidious growth requirements, which has made them very difficult to

Comp Funct Genom; Jo Wixon

417

Background  

E-print Network

OCA is a group of autosomal recessive disorders characterized by hypopigmentation and abnormalities related to ocular development. Mutations in genes regulating melanin-biosynthesis cause four classical types of OCA (OCA 1-4). The clinical spectrum of OCA often depends on the pigmentation threshold of a patient, highlighting the importance of ethnic- specific SNPs. We aimed to understand the molecular bases of OCA in India, where it is one of the four major causes of childhood blindness. Materials and methods Blood samples were collected from OCA patients and family members, mostly from eastern and southern India. Seven pigmentation related genes were screened for variations. Relevant non-synonymous changes in tyrosinase (TYR) were functionally validated. Eighteen SNPs from three OCA genes were genotyped in 552 normal individuals covering various ethnic groups of India. Results Our data suggest that defects in TYR cause albinism in 58 % (36/62) of the cases [1] (and unpublished data; see Figure 1). Functional assays with missense mutations proved that none of mutants are enzymatically active and are retained in the endoplasmic reticulum [1]. Screening of the remaining cases (43%) revealed OCA2 to be the second common locus followed by SLC45A2 [2] (Figure 1). Evaluation of SNPs in TYR, OCA2 and SLC45A2 in normal population suggested definitive bias for some of the SNPs towards specific populations.

Kunal Ray; Mainak Sengupta; Moumita Chaki; Maitreyee Mondal; Swapan Samanta

418

Background  

Cancer.gov

Extensive evidence has demonstrated that 24-hour dietary recalls provide the highest quality, least biased dietary data. Traditional 24-hour recalls, however, are expensive and impractical for large-scale research because they rely on trained interviewers and multiple administrations to estimate usual intakes. As a result, researchers often make use of food frequency questionnaires, which are less expensive but contain substantial error.

419

Background  

Cancer.gov

The discovery that proteins and peptides are "leaked" by tumors into clinically accessible bodily fluids such as blood has led to the possibility of diagnosing cancer at an early stage or monitoring response to treatment by collecting these fluids and testing for the presence of cancer-related biomarkers. Prostate-specific antigen (PSA) and cancer antigen 125 (CA-125) are examples of blood-borne cancer protein biomarkers that are currently being used in the clinic.

420

Tube-wave seismic imaging  

DOEpatents

The detailed analysis of cross well seismic data for a gas reservoir in Texas revealed two newly detected seismic wave effects, recorded approximately 2000 feet above the reservoir. A tube-wave (150) is initiated in a source well (110) by a source (111), travels in the source well (110), is coupled to a geological feature (140), propagates (151) through the geological feature (140), is coupled back to a tube-wave (152) at a receiver well (120), and is and received by receiver(s) (121) in either the same (110) or a different receiving well (120). The tube-wave has been shown to be extremely sensitive to changes in reservoir characteristics. Tube-waves appear to couple most effectively to reservoirs where the well casing is perforated, allowing direct fluid contact from the interior of a well case to the reservoir.

Korneev, Valeri A. (Lafayette, CA); Bakulin, Andrey (Houston, TX)

2009-10-13

421

Thermal stresses in composite tubes  

NASA Technical Reports Server (NTRS)

This paper summarizes work to determine the thermally-induced stresses and deformations in specially-constructed angle-ply composite tubes subjected to a uniform temperature change relative to their stress-free cure state. The tubes are designed for application to space structures and have high axial stiffness. Four angle-ply designs are examined in an effort to determine which design might have the most favorable thermally-induced response. A planar elasticity solution is used, the solution being valid away from the ends of the tube. Of the four designs considered, none has any particular advantage as far as stress levels are concerned. However, despite the fact that the tube wall is a balanced laminate, one design exhibits a significant amount of thermally-induced twist.

Hyer, M. W.

1986-01-01

422

Drop propulsion in tapered tubes  

E-print Network

We present the results of a combined experimental and theoretical investigation of the motion of wetting droplets in tapered capillary tubes. We demonstrate that drops may move spontaneously towards the tapered end owing ...

Renvoise, P.

423

Chest tube insertion - series (image)  

MedlinePLUS

... the lung can collapse, preventing adequate air exchange. Chest tubes are used to treat conditions that can ... as: air leaks from the lung into the chest (pneumothorax) bleeding into the chest (hemothorax) after surgery ...

424

Modeling of Piezoelectric Tube Actuators  

E-print Network

A new dynamic model is presented for piezoelectric tube actuators commonly used in high-precision instruments. The model captures coupling between motions in all three axes such as bending motion due to a supposedly pure ...

El Rifai, Osamah M.

425

Steam generator tube rupture study  

E-print Network

This report describes our investigation of steam generator behavior during a postulated tube rupture accident. Our study was performed using the steam generator, thermal-hydraulic analysis code THERMIT-UTSG. The purpose ...

Free, Scott Thomas

1986-01-01

426

Analysis of neural crest migration and differentiation by cross-species transplantation.  

PubMed

Avian embryos provide a unique platform for studying many vertebrate developmental processes, due to the easy access of the embryos within the egg. Chimeric avian embryos, in which quail donor tissue is transplanted into a chick embryo in ovo, combine the power of indelible genetic labeling of cell populations with the ease of manipulation presented by the avian embryo. Quail-chick chimeras are a classical tool for tracing migratory neural crest cells (NCCs). NCCs are a transient migratory population of cells in the embryo, which originate in the dorsal region of the developing neural tube. They undergo an epithelial to mesenchymal transition and subsequently migrate to other regions of the embryo, where they differentiate into various cell types including cartilage, melanocytes, neurons and glia. NCCs are multipotent, and their ultimate fate is influenced by 1) the region of the neural tube in which they originate along the rostro-caudal axis of the embryo, 2) signals from neighboring cells as they migrate, and 3) the microenvironment of their ultimate destination within the embryo. Tracing these cells from their point of origin at the neural tube, to their final position and fate within the embryo, provides important insight into the developmental processes that regulate patterning and organogenesis. Transplantation of complementary regions of donor neural tube (homotopic grafting) or different regions of donor neural tube (heterotopic grafting) can reveal differences in pre-specification of NCCs along the rostro-caudal axis. This technique can be further adapted to transplant a unilateral compartment of the neural tube, such that one side is derived from donor tissue, and the contralateral side remains unperturbed in the host embryo, yielding an internal control within the same sample. It can also be adapted for transplantation of brain segments in later embryos, after HH10, when the anterior neural tube has closed. Here we report techniques for generating quail-chick chimeras via neural tube transplantation, which allow for tracing of migratory NCCs derived from a discrete segment of the neural tube. Species-specific labeling of the donor-derived cells with the quail-specific QCPN antibody allows the researcher to distinguish donor and host cells at the experimental end point. This technique is straightforward, inexpensive, and has many applications, including fate-mapping, cell lineage tracing, and identifying pre-patterning events along the rostro-caudal axis. Because of the ease of access to the avian embryo, the quail-chick graft technique may be combined with other manipulations, including but not limited to lens ablation, injection of inhibitory molecules, or genetic manipulation via electroporation of expression plasmids, to identify the response of particular migratory streams of NCCs to perturbations in the embryo's developmental program. Furthermore, this grafting technique may also be used to generate other interspecific chimeric embryos such as quail-duck chimeras to study NCC contribution to craniofacial morphogenesis, or mouse-chick chimeras to combine the power of mouse genetics with the ease of manipulation of the avian embryo. PMID:22349214

Griswold, Shannon L; Lwigale, Peter Y

2012-01-01

427

Analysis of Neural Crest Migration and Differentiation by Cross-species Transplantation  

PubMed Central

Avian embryos provide a unique platform for studying many vertebrate developmental processes, due to the easy access of the embryos within the egg. Chimeric avian embryos, in which quail donor tissue is transplanted into a chick embryo in ovo, combine the power of indelible genetic labeling of cell populations with the ease of manipulation presented by the avian embryo. Quail-chick chimeras are a classical tool for tracing migratory neural crest cells (NCCs)1-3. NCCs are a transient migratory population of cells in the embryo, which originate in the dorsal region of the developing neural tube4. They undergo an epithelial to mesenchymal transition and subsequently migrate to other regions of the embryo, where they differentiate into various cell types including cartilage5-13, melanocytes11,14-20, neurons and glia21-32. NCCs are multipotent, and their ultimate fate is influenced by 1) the region of the neural tube in which they originate along the rostro-caudal axis of the embryo11,33-37, 2) signals from neighboring cells as they migrate38-44, and 3) the microenvironment of their ultimate destination within the embryo45,46. Tracing these cells from their point of origin at the neural tube, to their final position and fate within the embryo, provides important insight into the developmental processes that regulate patterning and organogenesis. Transplantation of complementary regions of donor neural tube (homotopic grafting) or different regions of donor neural tube (heterotopic grafting) can reveal differences in pre-specification of NCCs along the rostro-caudal axis2,47. This technique can be further adapted to transplant a unilateral compartment of the neural tube, such that one side is derived from donor tissue, and the contralateral side remains unperturbed in the host embryo, yielding an internal control within the same sample2,47. It can also be adapted for transplantation of brain segments in later embryos, after HH10, when the anterior neural tube has closed47. Here we report techniques for generating quail-chick chimeras via neural tube transplantation, which allow for tracing of migratory NCCs derived from a discrete segment of the neural tube. Species-specific labeling of the donor-derived cells with the quail-specific QCPN antibody48-56 allows the researcher to distinguish donor and host cells at the experimental end point. This technique is straightforward, inexpensive, and has many applications, including fate-mapping, cell lineage tracing, and identifying pre-patterning events along the rostro-caudal axis45. Because of the ease of access to the avian embryo, the quail-chick graft technique may be combined with other manipulations, including but not limited to lens ablation40, injection of inhibitory molecules57,58, or genetic manipulation via electroporation of expression plasmids59-61, to identify the response of particular migratory streams of NCCs to perturbations in the embryo's developmental program. Furthermore, this grafting technique may also be used to generate other interspecific chimeric embryos such as quail-duck chimeras to study NCC contribution to craniofacial morphogenesis, or mouse-chick chimeras to combine the power of mouse genetics with the ease of manipulation of the avian embryo.62 PMID:22349214

Griswold, Shannon L.; Lwigale, Peter Y.

2012-01-01

428

Magnetohydrostatic equilibrium. II. Three-dimensional multiple open magnetic flux tubes in the stratified solar atmosphere  

E-print Network

A system of multiple open magnetic flux tubes spanning the solar photosphere and lower corona is modelled analytically, within a realistic stratified atmosphere subject to solar gravity. This extends results for a single magnetic flux tube in magnetohydrostatic equilibrium, described in Gent et al. (MNRAS, 435, 689, 2013). Self-similar magnetic flux tubes are combined to form magnetic structures, which are consistent with high-resolution observations. The observational evidence supports the existence of strands of open flux tubes and loops persisting in a relatively steady state. Self-similar magnetic flux tubes, for which an analytic solution to the plasma density and pressure distribution is possible, are combined. We calculate the appropriate balancing forces, applying to the equations of momentum and energy conservation to preserve equilibrium. Multiplex flux tube configurations are observed to remain relatively stable for up to a day or more, and it is our aim to apply our model as the background conditi...

Gent, Frederick A; Erd'elyi, Rebertus

2014-01-01

429

Hand alphabet recognition using morphological PCA and neural networks  

Microsoft Academic Search

Proposes a method of feature extraction based upon the principal component analysis (PCA) of the pixel positions for the description of the hand postures from colored glove images. We analyze its performance applying it to a neural network based Japanese and American manual alphabet recognition system, while the background remains natural. Average recognition rates of 89.1% for the Japanese and

M. V. Lamari; M. S. Bhuiyan; A. Iwata

1999-01-01

430

Automatic Scene Text Recognition using a Convolutional Neural Network  

Microsoft Academic Search

This paper presents an automatic recognition method for color text characters extracted from scene images, which is robust to strong distortions, complex background, low res- olution and non uniform lightning. Based on a specific ar- chitecture of convolutional neural networks, the proposed system automatically learns how to recognize characters without making any assumptions, without applying any pre- processing or post-processing

Zohra Saidane; Christophe Garcia

431

The neural crest epithelial-mesenchymal transition in 4D: a 'tail' of multiple non-obligatory cellular mechanisms.  

PubMed

An epithelial-mesenchymal transition (EMT) is the process whereby epithelial cells become mesenchymal cells, and is typified by the generation of neural crest cells from the neuroepithelium of the dorsal neural tube. To investigate the neural crest EMT, we performed live cell confocal time-lapse imaging to determine the sequence of cellular events and the role of cell division in the EMT. It was observed that in most EMTs, the apical cell tail is retracted cleanly from the lumen of the neuroepithelium, followed by movement of the cell body out of the neural tube. However, exceptions to this sequence include the rupture of the neural crest cell tail during retraction (junctional complexes not completely downregulated), or translocation of the cell body away from the apical surface while morphologically rounded up in M phase (no cell tail retraction event). We also noted that cell tail retraction can occur either before or after the redistribution of apical-basolateral epithelial polarity markers. Surprisingly, we discovered that when an EMT was preceded by a mitotic event, the plane of cytokinesis does not predict neural crest cell fate. Moreover, when daughter cells are separated from the adherens junctions by a parallel mitotic cleavage furrow, most re-establish contact with the apical surface. The diversity of cellular mechanisms by which neural crest cells can separate from the neural