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1

Apicobasal polarity and neural tube closure.  

PubMed

During development, a flat neural plate rolls up and closes to form a neural tube. This process, called neural tube closure, is complex and requires morphogenetic events to occur along multiple axes of the neural plate. Recent studies suggest that cell and tissue polarity play a major role in neural tube morphogenesis. While the planar cell polarity pathway is known to be involved in this process, a role for the apicobasal polarity pathway has only recently begun to be elucidated. These studies show that bone morphogenetic proteins can regulate the apicobasal polarity pathway in the neural plate in a cell cycle dependent manner. This dynamically modulates apical junctions in the neural plate, resulting in cell and tissue shape changes that help bend, shape and close the neural tube. PMID:23277919

Eom, Dae Seok; Amarnath, Smita; Agarwala, Seema

2013-01-01

2

MIM regulates vertebrate neural tube closure  

PubMed Central

Neural tube closure is a critical morphogenetic event that is regulated by dynamic changes in cell shape and behavior. Although previous studies have uncovered a central role for the non-canonical Wnt signaling pathway in neural tube closure, the underlying mechanism remains poorly resolved. Here, we show that the missing in metastasis (MIM; Mtss1) protein, previously identified as a Hedgehog response gene and actin and membrane remodeling protein, specifically binds to Daam1 and couples non-canonical Wnt signaling to neural tube closure. MIM binds to a conserved domain within Daam1, and this interaction is positively regulated by Wnt stimulation. Spatial expression of MIM is enriched in the anterior neural plate and neural folds, and depletion of MIM specifically inhibits anterior neural fold closure without affecting convergent extension movements or mesoderm cell fate specification. Particularly, we find that MIM is required for neural fold elevation and apical constriction along with cell polarization and elongation in both the superficial and deep layers of the anterior neural plate. The function of MIM during neural tube closure requires both its membrane-remodeling domain and its actin-binding domain. Finally, we show that the effect of MIM on neural tube closure is not due to modulation of Hedgehog signaling in the Xenopus embryo. Together, our studies define a morphogenetic pathway involving Daam1 and MIM that transduces non-canonical Wnt signaling for the cytoskeletal changes and membrane dynamics required for vertebrate neural tube closure. PMID:21471152

Liu, Wei; Komiya, Yuko; Mezzacappa, Courtney; Khadka, Deepak K.; Runnels, Loren; Habas, Raymond

2011-01-01

3

Folic Acid Helps Prevent Neural Tube Defects  

MedlinePLUS

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4

Incidence of neural tube defects in Ontario, 1986-1999  

Microsoft Academic Search

Background: Prenatal screening and the promotion of folic acid intake could affect the incidence of neural tube defects (NTDs). We examined trends in the total NTD incidence, as detected in live births, stillbirths and therapeutic abortions, from 1986 to 1999 in Ontario. Methods: To capture cases of NTDs we used data from the Canadian Congenital Anomalies Surveillance System and hospital

Enza Gucciardi; Mary-Anne Pietrusiak; Donna L. Reynolds; Jocelyn Rouleau

5

Immunohistochemistry of medulloepithelioma and neural tube.  

PubMed

Immunohistochemistry profiles of medulloepithelioma (from two 2 1/2-year-old girls who had cerebral medulloepitheliomas and a 35-week postconceptional female infant with congenital posterior fossa tumor) and neural tube are compared. Microscopically, the tumors contained a medulloepitheliomatous component, manifested as tubular epithelial structures lined by pseudostratified columnar epithelium delineated by well-defined basement membranes. In all cases, glial and neuronal differentiation were noted to differing extents. The medulloepitheliomatous components did not exhibit glial fibrillary acidic protein, neuron-specific enolase, or S-100 protein reactivity. Neurofilament, cytokeratin, and epithelial membrane antigen were focally present in one case. Extensive nestin immunopositivity was confined to the basal cell layer of the epithelium, leaving the luminal surface unreactive or slightly reactive. These cells also displayed a reactivity to vimentin and to microtubule-associated protein type 5 similar to that of cells of the primitive neural tube. The similarity between the immunohistochemical profile of medulloepithelioma and that of neural tube epithelium suggests a possible reexpression of that component of the genome responsible for neural tube growth and differentiation in medulloepithelioma. PMID:9353831

Khoddami, M; Becker, L E

1997-01-01

6

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

7

Neural Tube Defects, Folic Acid and Methylation  

PubMed Central

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.

2013-01-01

8

Shroom Induces Apical Constriction and Is Required for Hingepoint Formation during Neural Tube Closure  

Microsoft Academic Search

Background: The morphogenetic events of early vertebrate development generally involve the combined actions of several populations of cells, each engaged in a distinct behavior. Neural tube closure, for instance, involves apicobasal cell heightening, apical constriction at hingepoints, convergent extension of the midline, and pushing by the epidermis. Although a large number of genes are known to be required for neural

John B. Wallingford; Jeffrey D. Hildebrand; Richard M. Harland

2003-01-01

9

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

10

Morphogenesis: Shroom in to Close the Neural Tube  

Microsoft Academic Search

A novel actin-binding protein, Shroom, localises to precisely those cells that will constrict during cranial neural tube closure and appears pivotal in regulating the apical constrictions that drive epithelial foldings in vertebrate embryos.

Paul Martin

2004-01-01

11

How Do Health Care Providers Diagnose Neural Tube Defects?  

MedlinePLUS

... Information Clinical Trials Resources and Publications How do health care providers diagnose neural tube defects? Skip sharing on ... AFP, as well as high levels of acetylcholinesterase; health care providers might conduct this test to confirm high ...

12

Homocysteine metabolism in pregnancies complicated by neural-tube defects  

Microsoft Academic Search

Folic acid taken around the time of conception can prevent many neural-tube defects. Women with low-normal vitamin B12 values may also be at increased risk. We considered whether homocysteine metabolism via the enzyme methionine synthase, which requires both folate and B12, could be the critical defect in folate-related neural tube defects. Blood was obtained during pregnancies that produced 81 infants

J. L. Mills; Y. J. Lee; M. R. Conley; P. N. Kirke; J. M. McPartlin; D. G. Weir; J. M. Scott

1995-01-01

13

Aneuploidy among prenatally detected neural tube defects  

SciTech Connect

We have reported previously a 10% aneuploidy detection rate among 39 cases of fetal neural tube defects (NTD). Subsequently we amassed an additional experience of over 17,000 prenatal diagnosis cases over a 5-year period. During this period 106 cases of NTDs were identified; 44 with anencephaly, 62 with open spina bifida. The average maternal age of this population with NTDs was 29 years (15-40); 6 patients declined amniocentesis. Six of 100 cytogenetic studies were aneuploid; on anencephalic fetus had inherited a maternal marker chromosome, and 5 NTD cases had trisomy 18. The average maternal age of the aneuploid cases was 21 (19-40); 3 were 35 years or older. Four of 5 trisomy 18 cases had multiple congenital anomalies (MCA). The overall aneuploidy detection rate in our cohort was 5-6, while aneuploidy occurred in 2% of the isolated NTD cases, and 24% of the MCA cases. Combining the earlier experience, 4/39 aneuploidy (2 trisomy 18, 4p+, del 13q) yields an aneuploidy detection frequency of 10/145 (7%), of which most (7/10) had trisomy 18. These data support fetal karyotyping for accurate diagnosis, prognosis, and recurrence-risk counseling. 5 refs., 2 tabs.

Hume, R.F. Jr.; Lampinen, J.; Martin, L.S.; Johnson, M.P.; Evans, M.I. [Wayne State Univ., Detroit, MI (United States)] [and others] [Wayne State Univ., Detroit, MI (United States); and others

1996-01-11

14

Apical Accumulation of Rho in the Neural Plate Is Important for Neural Plate Cell Shape Change and Neural Tube Formation  

PubMed Central

Although Rho-GTPases are well-known regulators of cytoskeletal reorganization, their in vivo distribution and physiological functions have remained elusive. In this study, we found marked apical accumulation of Rho in developing chick embryos undergoing folding of the neural plate during neural tube formation, with similar accumulation of activated myosin II. The timing of accumulation and biochemical activation of both Rho and myosin II was coincident with the dynamics of neural tube formation. Inhibition of Rho disrupted its apical accumulation and led to defects in neural tube formation, with abnormal morphology of the neural plate. Continuous activation of Rho also altered neural tube formation. These results indicate that correct spatiotemporal regulation of Rho is essential for neural tube morphogenesis. Furthermore, we found that a key morphogenetic signaling pathway, the Wnt/PCP pathway, was implicated in the apical accumulation of Rho and regulation of cell shape in the neural plate, suggesting that this signal may be the spatiotemporal regulator of Rho in neural tube formation. PMID:18337466

Kinoshita, Nagatoki; Sasai, Noriaki; Misaki, Kazuyo

2008-01-01

15

Neural tube defects--prenatal diagnosis and management.  

PubMed Central

Neural tube defects rank second to congenital heart disease as a major cause of congenital malformation. Recent developments in ultrasound have improved prenatal diagnosis. Due to anomaly scans at 18 weeks gestation and the availability of a genetic clinic, prenatal diagnosis of neural tube defects at the Royal Maternity Hospital was 91.2% during 1987-1989. However, only 50% of parents accept termination of pregnancy and it is questionable if prenatal diagnosis is of benefit to those who wish to continue with the pregnancy. Parents may accept the situation better at birth, having had time to come to terms with it, helped with support from the obstetrician, clinical geneticist, paediatrician, genetic nurse and social worker. For some affected fetuses who have better muscle function and leg movement at term it appears from the literature that the outcome may be improved by caesarean section delivery. In Ireland fetuses with neural tube defects will continue to be delivered, as termination is unacceptable to many, but despite this there may be a positive benefit from prenatal diagnosis of neural tube defects. Prospective randomised controlled trials are needed to confirm benefit from delivery by caesarean section for fetuses with a good prognosis. As a result of prenatal diagnosis of a neural tube lesion the fetus should enjoy benefit in terms of physical morbidity, and the parents should benefit in terms of psychological morbidity. PMID:1481301

Hamilton, R. A.; Dornan, J. C.

1992-01-01

16

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

17

Spinal dysraphism: genetic relation to neural tube malformations.  

PubMed Central

The families of 207 index patients treated for spinal dysraphism at The Hospital for Sick Children were studied to discover whether the condition was aetiologically related to the classical neural tube malformation--spina bifida cystica and anencephaly. The index patients had all had a tethered conus medullaris and one or more of a variety of anomalies of the spinal cord, vertebrae, or skin overlying the vertebral column. Of 364 sibs of index patients, 9 had an encephaly and 6 spina bifida cystica, a pro-proportion of 4.12%. This approximates to the proportion of sibs affected by neural tube malformations in the London region when the index patients themselves have spina bifida or anencephaly. It is, therefore, appropriate that the mothers of children with spinal dysraphism should be offered prenatal screening for neural tube malformations. PMID:794474

Carter, C O; Evans, K A; Till, K

1976-01-01

18

Prevention of neural tube defects in an urban health district.  

PubMed Central

An evaluation of voluntary prenatal screening for neural tube defects with serum alphafetoprotein (s-AFP) is presented. During a three year period, there were 52 fetuses with neural lesions. Of 46 mothers who bore a fetus with an open neural lesion, 25 were detected, of whom 23 agreed to the termination of their pregnancies. An unscreened group of 2331 mothers (17% of all deliveries) produced 14 fetuses with neural tube defects, an incidence of 6.0 per 1000, 1.8 times the incidence (3.3 per 1000) in the screened group. Pitfalls occurring in the assessment of hyper-alphafetoproteinemia included inaccurate gestational dating and allowance for excessive body weight. The results of a robust AFP-NTD screening programme supported in selected cases by ultrasonar visualisation of the spine argue for its continuance in this district. PMID:6194239

Watson, D; Pow, M; Ellam, A; Costeloe, K

1983-01-01

19

Apical Accumulation of Rho in the Neural Plate Is Important for Neural Plate Cell Shape Change and Neural Tube Formation  

Microsoft Academic Search

Although Rho-GTPases are well-known regulators of cytoskeletal reorganization, their in vivo distribution and physio- logical functions have remained elusive. In this study, we found marked apical accumulation of Rho in developing chick embryos undergoing folding of the neural plate during neural tube formation, with similar accumulation of activated myosin II. The timing of accumulation and biochemical activation of both Rho

Nagatoki Kinoshita; Noriaki Sasai; Kazuyo Misaki; Shigenobu Yonemura

2008-01-01

20

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

21

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

22

Socioeconomic status, neighborhood social conditions, and neural tube defects.  

PubMed Central

OBJECTIVES: This study evaluated the contributions of lower socioeconomic status (SES) and neighborhood socioeconomic characteristics to neural tube defect etiology. The influence of additional factors, including periconceptional multivitamin use and race/ethnicity, was also explored. METHODS: Data derived from a case-control study of California pregnancies from 1989 to 1991. Mothers of 538 (87.8% of eligible) case infants/fetuses with neural tube defects and mothers of 539 (88.2%) nonmalformed infants were interviewed about their SES. Reported addresses were linked to 1990 US census information to characterize neighborhoods. RESULTS: Twofold elevated risks were observed for several SES indicators. Risks were somewhat confounded by vitamin use, race/ethnicity, age, body mass index, and fever but remained elevated after adjustment. A risk gradient was seen with increasing number of lower SES indicators. Women with 1 to 3 and 4 to 6 lower SES indicators had adjusted odds ratios of 1.6 (1.1-2.2) and 3.2 (1.9-5.4), respectively, compared with women with no lower SES indicators. CONCLUSIONS: Both lower SES and residence in a SES-lower neighborhood increased the risk of an neural tube defect-affected pregnancy, with risks increasing across a gradient of SES indicators. PMID:9807535

Wasserman, C R; Shaw, G M; Selvin, S; Gould, J B; Syme, S L

1998-01-01

23

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

24

Grainyhead-like 2 regulates neural tube closure and adhesion molecule expression during neural fold fusion  

PubMed Central

Summary Defects in closure of embryonic tissues such as the neural tube, body wall, face and eye lead to severe birth defects. Cell adhesion is hypothesized to contribute to closure of the neural tube and body wall, however potential molecular regulators of this process have not been identified. Here we identify an ENU-induced mutation in mice that reveals a molecular pathway of embryonic closure. Line2F homozygous mutant embryos fail to close the neural tube, body wall, face, and optic fissure, and they also display defects in lung and heart development. Using a new technology of genomic sequence capture and high-throughput sequencing of a 2.5 Mb region of the mouse genome, we discovered a mutation in the grainyhead-like 2 gene (Grhl2). Microarray analysis revealed Grhl2 affects the expression of a battery of genes involved in cell adhesion and E-cadherin protein is drastically reduced in tissues that require Grhl2 function. The tissue closure defects in Grhl2 mutants are similar to that of AP-2? null mutants and AP-2? has been shown to bind to the promoter of E-cadherin. Therefore, we tested for a possible interaction between these genes. However, we find that Grhl2 and AP-2? do not regulate each other’s expression, E-cadherin expression is normal in AP-2? mutants during neural tube closure, and Grhl2;AP-2? trans-heterozygous embryos are morphologically normal. Taken together, our studies point to a complex regulation of neural tube fusion and highlight the importance of comparisons between these two models to understand more fully the molecular pathways of embryonic tissue closure. PMID:21377456

Pyrgaki, Christina; Liu, Aimin; Niswander, Lee

2011-01-01

25

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

SciTech Connect

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{sup +} migrating neural crest cells (NCCs). In addition, Robo1 over-expression enhanced Pax7 expression in the dorsal neural tube and increased the number of Slug{sup +} pre-migratory NCCs. Conversely, silencing Robo1 expression resulted in an enhanced Shh expression and more HNK-1{sup +} migrating NCCs but reduced Pax7 expression and fewer Slug{sup +} 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. - Highlights: ? The role of Slit/Robo1 signaling was investigated with chick and mouse models. ? Disturbance of Slit/Robo1 signaling resulted in neural tube defects. ? Slit/Robo1 signaling regulated the proliferation of neural tube cells. ? Slit/Robo1 signaling modulated the differentiation of neural tube cells. ? Slit/Robo1 signaling balanced the proliferation and differentiation of neural tube.

Wang, Guang; Li, Yan; Wang, Xiao-yu [Key Laboratory for Regenerative Medicine of The Ministry of Education, Department of Histology and Embryology, School of Medicine, Jinan University, Guangzhou 510632 (China); Han, Zhe [Institute of Vascular Biological Sciences, Guangdong Pharmaceutical University, Guangzhou 510224 (China); Chuai, Manli [College of Life Sciences Biocentre, University of Dundee, Dundee DD1 5EH (United Kingdom); Wang, Li-jing [Institute of Vascular Biological Sciences, Guangdong Pharmaceutical University, Guangzhou 510224 (China); Ho Lee, Kenneth Ka [Stem Cell and Regeneration Thematic Research Programme, School of Biomedical Sciences, Chinese University of Hong Kong, Shatin (Hong Kong); Geng, Jian-guo, E-mail: jgeng@umich.edu [Institute of Vascular Biological Sciences, Guangdong Pharmaceutical University, Guangzhou 510224 (China); Department of Biologic and Materials Sciences, University of Michigan School of Dentistry, Ann Arbor, MI 48109 (United States); Yang, Xuesong, E-mail: yang_xuesong@126.com [Key Laboratory for Regenerative Medicine of The Ministry of Education, Department of Histology and Embryology, School of Medicine, Jinan University, Guangzhou 510632 (China)

2013-05-01

26

Folic Acid for the Prevention of Infant Neural Tube Defects: U.S. Preventive Services Task Force Recommendation  

MedlinePLUS

Folic Acid for the Prevention of Infant Neural Tube Defects: U.S. Preventive Services Task Force Recommendation Summaries for Patients ... modern medicine. The full reports are titled “Folic Acid for the Prevention of Neural Tube Defects: U.S. ...

27

Measuring the benefits of screening for open neural tube defects.  

PubMed Central

Evaluation of the costs and benefits of public sector programmes is necessary to plan the optimum uses for society's resources. Here the benefits of screening for open neural tube defects are examined, and the most appropriate methodological approach to their valuation is discussed in the context of the possible provision by the National Health Service of a routine prenatal screening programme. It is argued that, in measuring the benefits of screening, previous evaluations have adopted an approach that is rather unsatisfactory from the standpoint of economic methodology. An attempt is therefore made here to show the effect that adopting a more appropriate approach would have on the estimated value of the benefit of routine screening. The effect is found to be a substantial increase in its estimated value. PMID:6815296

Henderson, J B

1982-01-01

28

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

29

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

30

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

Code of Federal Regulations, 2011 CFR

...2011-04-01 2011-04-01 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...

2011-04-01

31

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

Code of Federal Regulations, 2012 CFR

...2012-04-01 2012-04-01 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...

2012-04-01

32

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

...2014-04-01 2014-04-01 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...

2014-04-01

33

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

Code of Federal Regulations, 2013 CFR

...2013-04-01 2013-04-01 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...

2013-04-01

34

Morphogens, modeling and patterning the neural tube: an interview with James Briscoe.  

PubMed

James Briscoe has a BSc in Microbiology and Virology (from the University of Warwick, UK) and a PhD in Molecular and Cellular Biology (from the Imperial Cancer Research Fund, London, now Cancer Research UK). He started working on the development of the neural tube in the lab of Tom Jessel as a postdoctoral fellow, establishing that there was graded sonic hedgehog signaling in the ventral neural tube. He is currently a group leader and Head of Division in Developmental Biology at the MRC National Institute for Medical Research (which will become part of the Francis Crick Institute in April 2015). He is working to understand the molecular and cellular mechanisms of graded signaling in the vertebrate neural tube.We interviewed him about the development of ideas on morphogenetic gradients and his own work on modeling the development of the neural tube for our series on modeling in biology. PMID:25600934

Briscoe, James

2015-01-01

35

Oxidant regulation of gene expression and neural tube development: Insights gained from diabetic pregnancy on molecular causes of neural tube defects  

Microsoft Academic Search

  \\u000a \\u000a Aims\\/hypothesis. Maternal diabetes increases oxidative stress in embryos. Maternal diabetes also inhibits expression of embryonic genes, most\\u000a notably, Pax-3, which is required for neural tube closure. Here we tested the hypothesis that oxidative stress inhibits expression of Pax-3, thereby providing a molecular basis for neural tube defects induced by diabetic pregnancy.\\u000a \\u000a \\u000a \\u000a \\u000a Methods. Maternal diabetes-induced oxidative stress was blocked with

T. I. Chang; M. Horal; S. K. Jain; F. Wang; R. Patel; M. R. Loeken

2003-01-01

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

Bone morphogenetic proteins regulate neural tube closure by interacting with the apicobasal polarity pathway  

PubMed Central

During neural tube closure, specialized regions called hinge points (HPs) display dynamic and polarized cell behaviors necessary for converting the neural plate into a neural tube. The molecular bases of such cell behaviors (e.g. apical constriction, basal nuclear migration) are poorly understood. We have identified a two-dimensional canonical BMP activity gradient in the chick neural plate that results in low and temporally pulsed BMP activity at the ventral midline/median hinge point (MHP). Using in vivo manipulations, high-resolution imaging and biochemical analyses, we show that BMP attenuation is necessary and sufficient for MHP formation. Conversely, BMP overexpression abolishes MHP formation and prevents neural tube closure. We provide evidence that BMP modulation directs neural tube closure via the regulation of apicobasal polarity. First, BMP blockade produces partially polarized neural cells, which retain contact with the apical and basal surfaces but where basolateral proteins (LGL) become apically localized and apical junctional proteins (PAR3, ZO1) become targeted to endosomes. Second, direct LGL misexpression induces ectopic HPs identical to those produced by noggin or dominant-negative BMPR1A. Third, BMP-dependent biochemical interactions occur between the PAR3-PAR6-aPKC polarity complex and phosphorylated SMAD5 at apical junctions. Finally, partially polarized cells normally occur at the MHP, their frequencies inversely correlated with the BMP activity gradient in the neural plate. We propose that spatiotemporal modulation of the two-dimensional BMP gradient transiently alters cell polarity in targeted neuronal cells. This ensures that the neural plate is flexible enough to be focally bent and shaped into a neural tube, while retaining overall epithelial integrity. PMID:21750029

Eom, Dae Seok; Amarnath, Smita; Fogel, Jennifer L.; Agarwala, Seema

2011-01-01

38

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

39

Modeling Anterior Development in Mice: Diet as Modulator of Risk for Neural Tube Defects  

PubMed Central

Head morphogenesis is a complex process that is controlled by multiple signaling centers. The most common defects of cranial development are craniofacial defects, such as cleft lip and cleft palate, and neural tube defects, such as anencephaly and encephalocoele in humans. More than 400 genes that contribute to proper neural tube closure have been identified in experimental animals, but only very few causative gene mutations have been identified in humans, supporting the notion that environmental influences are critical. The intrauterine environment is influenced by maternal nutrition, and hence, maternal diet can modulate the risk for cranial and neural tube defects. This article reviews recent progress toward a better understanding of nutrients during pregnancy, with particular focus on mouse models for defective neural tube closure. At least four major patterns of nutrient responses are apparent, suggesting that multiple pathways are involved in the response, and likely in the underlying pathogenesis of the defects. Folic acid has been the most widely studied nutrient, and the diverse responses of the mouse models to folic acid supplementation indicate that folic acid is not universally beneficial, but that the effect is dependent on genetic configuration. If this is the case for other nutrients as well, efforts to prevent neural tube defects with nutritional supplementation may need to become more specifically targeted than previously appreciated. Mouse models are indispensable for a better understanding of nutrient–gene interactions in normal pregnancies, as well as in those affected by metabolic diseases, such as diabetes and obesity. PMID:24124024

Kappen, Claudia

2014-01-01

40

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

41

Replication and exploratory analysis of 24 candidate risk polymorphisms for neural tube defects.  

PubMed

BackgroundNeural tube defects (NTDs), which are among the most common congenital malformations, are influenced by environmental and genetic factors. Low maternal folate is the strongest known contributing factor, making variants in genes in the folate metabolic pathway attractive candidates for NTD risk. Multiple studies have identified nominally significant allelic associations with NTDs. We tested whether associations detected in a large Irish cohort could be replicated in an independent population.MethodsReplication tests of 24 nominally significant NTD associations were performed in racially/ethnically matched populations. Family-based tests of fifteen nominally significant single nucleotide polymorphisms (SNPs) were repeated in a cohort of NTD trios (530 cases and their parents) from the United Kingdom, and case¿control tests of nine nominally significant SNPs were repeated in a cohort (190 cases, 941 controls) from New York State (NYS). Secondary hypotheses involved evaluating the latter set of nine SNPs for NTD association using alternate case¿control models and NTD groupings in white, African American and Hispanic cohorts from NYS.ResultsOf the 24 SNPs tested for replication, ADA rs452159 and MTR rs10925260 were significantly associated with isolated NTDs. Of the secondary tests performed, ARID1A rs11247593 was associated with NTDs in whites, and ALDH1A2 rs7169289 was associated with isolated NTDs in African Americans.ConclusionsWe report a number of associations between SNP genotypes and neural tube defects. These associations were nominally significant before correction for multiple hypothesis testing. These corrections are highly conservative for association studies of untested hypotheses, and may be too conservative for replication studies. We therefore believe the true effect of these four nominally significant SNPs on NTD risk will be more definitively determined by further study in other populations, and eventual meta-analysis. PMID:25293959

Pangilinan, Faith; Molloy, Anne M; Mills, James L; Troendle, James F; Parle-McDermott, Anne; Kay, Denise M; Browne, Marilyn L; McGrath, Emily C; Abaan, Hatice; Sutton, Marie; Kirke, Peadar N; Caggana, Michele; Shane, Barry; Scott, John M; Brody, Lawrence C

2014-10-01

42

Spontaneous neural tube defects in splotch mice supplemented with selected micronutrients  

SciTech Connect

Splotch (Sp/Sp) mice homozygous for a mutation in the Pax3 gene inevitably present with neural tube defects (NTDs), along with other associated congenital anomalies. The affected mutant embryos usually die by gestation days (E) 12-13. In the present study, the effect of modifier genes from a new genetic background (CXL-Sp) and periconceptional supplementation with selected micronutrients (folic acid, 5-formyltetrahydrofolate, 5-methyltetrahydrofolate, methionine, myoinositol, thiamine, thymidine, and {alpha}-tocopherol) was determined with respect to the incidence of NTDs. In order to explore how different exposure parameters (time, dose, and route of compound administration) modulate the beneficial effects of micronutrient supplementation, female mice received either short- or long-term nutrient supplements via enteral or parenteral routes. Embryos were collected on E12.5 and examined for the presence of anterior or posterior NTDs. Additionally, whole mount in situ hybridization studies were conducted in order to reveal/confirm normal expression patterns of the Pax3 gene during neurulation in the wild-type and Sp/Sp homozygous mutant mouse embryos utilized in this study. A strong Pax3 signal was demonstrated in CXL-Sp embryos during neural tube closure (E9.5 to E10.5). The intensity and spatial pattern of expression were similar to other Splotch mutant mice. Of all the micronutrients tested, only supplementation with folic acid or 5-methyltetrahydrofolate rescued the normal phenotype in Sp/Sp embryos. When the folate supplementation dose was increased to 200 mg/kg in the diet, the incidence of rescued splotch homozygotes reached 30%; however, this was accompanied by six-fold increased resorption rate.

Wlodarczyk, Bogdan J. [Center for Environmental and Genetic Medicine, Institute of Biosciences and Technology, Texas A and M University System Health Science Center, Houston, TX 77030 (United States)]. E-mail: bwlodarczyk@ibt.tamhsc.edu; Tang, Louisa S. [Center for Environmental and Genetic Medicine, Institute of Biosciences and Technology, Texas A and M University System Health Science Center, Houston, TX 77030 (United States); Triplett, Aleata [Center for Human Molecular Genetics, Department of Pediatrics, University of Nebraska Medical Center, Omaha, NE 68198-5455 (United States); Aleman, Frank [Center for Human Molecular Genetics, Department of Pediatrics, University of Nebraska Medical Center, Omaha, NE 68198-5455 (United States); Finnell, Richard H. [Center for Environmental and Genetic Medicine, Institute of Biosciences and Technology, Texas A and M University System Health Science Center, Houston, TX 77030 (United States); Center for Human Molecular Genetics, Department of Pediatrics, University of Nebraska Medical Center, Omaha, NE 68198-5455 (United States)

2006-05-15

43

Syndecan 4 interacts genetically with Vangl2 to regulate neural tube closure and planar cell polarity  

PubMed Central

Syndecan 4 (Sdc4) is a cell-surface heparan sulfate proteoglycan (HSPG) that regulates gastrulation, neural tube closure and directed neural crest migration in Xenopus development. To determine whether Sdc4 participates in Wnt/PCP signaling during mouse development, we evaluated a possible interaction between a null mutation of Sdc4 and the loop-tail allele of Vangl2. Sdc4 is expressed in multiple tissues, but particularly in the non-neural ectoderm, hindgut and otic vesicles. Sdc4;Vangl2Lp compound mutant mice have defective spinal neural tube closure, disrupted orientation of the stereocilia bundles in the cochlea and delayed wound healing, demonstrating a strong genetic interaction. In Xenopus, co-injection of suboptimal amounts of Sdc4 and Vangl2 morpholinos resulted in a significantly greater proportion of embryos with defective neural tube closure than each individual morpholino alone. To probe the mechanism of this interaction, we overexpressed or knocked down Vangl2 function in HEK293 cells. The Sdc4 and Vangl2 proteins colocalize, and Vangl2, particularly the Vangl2Lp mutant form, diminishes Sdc4 protein levels. Conversely, Vangl2 knockdown enhances Sdc4 protein levels. Overall HSPG steady-state levels were regulated by Vangl2, suggesting a molecular mechanism for the genetic interaction in which Vangl2Lp/+ enhances the Sdc4-null phenotype. This could be mediated via heparan sulfate residues, as Vangl2Lp/+ embryos fail to initiate neural tube closure and develop craniorachischisis (usually seen only in Vangl2Lp/Lp) when cultured in the presence of chlorate, a sulfation inhibitor. These results demonstrate that Sdc4 can participate in the Wnt/PCP pathway, unveiling its importance during neural tube closure in mammalian embryos. PMID:23760952

Escobedo, Noelia; Contreras, Osvaldo; Muñoz, Rosana; Farías, Marjorie; Carrasco, Héctor; Hill, Charlotte; Tran, Uyen; Pryor, Sophie E.; Wessely, Oliver; Copp, Andrew J.; Larraín, Juan

2013-01-01

44

?-catenin regulates Pax3 and Cdx2 for caudal neural tube closure and elongation  

PubMed Central

Non-canonical Wnt/planar cell polarity (PCP) signaling plays a primary role in the convergent extension that drives neural tube closure and body axis elongation. PCP signaling gene mutations cause severe neural tube defects (NTDs). However, the role of canonical Wnt/?-catenin signaling in neural tube closure and NTDs remains poorly understood. This study shows that conditional gene targeting of ?-catenin in the dorsal neural folds of mouse embryos represses the expression of the homeobox-containing genes Pax3 and Cdx2 at the dorsal posterior neuropore (PNP), and subsequently diminishes the expression of the Wnt/?-catenin signaling target genes T, Tbx6 and Fgf8 at the tail bud, leading to spina bifida aperta, caudal axis bending and tail truncation. We demonstrate that Pax3 and Cdx2 are novel downstream targets of Wnt/?-catenin signaling. Transgenic activation of Pax3 cDNA can rescue the closure defect in the ?-catenin mutants, suggesting that Pax3 is a key downstream effector of ?-catenin signaling in the PNP closure process. Cdx2 is known to be crucial in posterior axis elongation and in neural tube closure. We found that Cdx2 expression is also repressed in the dorsal PNPs of Pax3-null embryos. However, the ectopically activated Pax3 in the ?-catenin mutants cannot restore Cdx2 mRNA in the dorsal PNP, suggesting that the presence of both ?-catenin and Pax3 is required for regional Cdx2 expression. Thus, ?-catenin signaling is required for caudal neural tube closure and elongation, acting through the transcriptional regulation of key target genes in the PNP. PMID:24284205

Zhao, Tianyu; Gan, Qini; Stokes, Arjun; Lassiter, Rhonda N. T.; Wang, Yongping; Chan, Jason; Han, Jane X.; Pleasure, David E.; Epstein, Jonathan A.; Zhou, Chengji J.

2014-01-01

45

Fetotoxicity and neural tube defects in CD1 mice exposed to the mycotoxin Fumonisin B1  

Technology Transfer Automated Retrieval System (TEKTRAN)

Fumonisins are mycotoxins that are produced by Fusarium verticillioides and that occur in corn and corn-based foods. Their effects on human health are unclear, however, epidemiological and experimental evidence suggests that they increase the risk of neural tube defects (NTDs) in populations routine...

46

Neural tube patterning by Krox20 and emergence of a respiratory control  

Microsoft Academic Search

Recent data begin to bridge the gap between developmental events controlling hindbrain neural tube regional patterning and the emergence of breathing behaviour in the fetus and its vital adaptive function after birth. In vertebrates, Hox paralogs and Hox-regulating genes orchestrate, in a conserved manner, the transient formation of developmental compartments in the hindbrain, the rhombomeres, in which rhythmic neuronal networks

C. Borday; F. Chatonnet; M. Thoby-Brisson; J. Champagnat; G. Fortin

2005-01-01

47

Maternal fumonisin exposure as a risk factor for neural tube defects  

Technology Transfer Automated Retrieval System (TEKTRAN)

Fumonisins are mycotoxins produced by the fungus F. verticillioides, a common contaminant of maize (corn) worldwide. Maternal consumption of fumonisin B1-contaminated maize during early pregnancy has recently been associated with increased risk for neural tube defects (NTDs) in human populations th...

48

Lipid mediators link cells progression with placental and neural tube defects after maternal fumonisin exposure  

Technology Transfer Automated Retrieval System (TEKTRAN)

Fumonisin B1 (FB1) is a mycotoxin produced by a common fungal contaminant of maize. Increased risk for neural tube defects (NTDs) is observed in populations that rely on maize as a dietary staple. FB1 inhibits ceramide synthase, resulting in altered pools of biologically active sphingolipids. FB1...

49

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

50

dNTP deficiency induced by HU via inhibiting ribonucleotide reductase affects neural tube development.  

PubMed

Exposure to environmental toxic chemicals in utero during the neural tube development period can cause developmental disorders. To evaluate the disruption of neural tube development programming, the murine neural tube defects (NTDs) model was induced by interrupting folate metabolism using methotrexate in our previous study. The present study aimed to examine the effects of dNTP deficiency induced by hydroxyurea (HU), a specific ribonucleotide reductase (RNR) inhibitor, during murine neural tube development. Pregnant C57BL/6J mice were intraperitoneally injected with various doses of HU on gestation day (GD) 7.5, and the embryos were checked on GD 11.5. RNR activity and deoxynucleoside triphosphate (dNTP) levels were measured in the optimal dose. Additionally, DNA damage was examined by comet analysis and terminal deoxynucleotidyl transferase mediated dUTP nick end-labeling (TUNEL) assay. Cellular behaviors in NTDs embryos were evaluated with phosphorylation of histone H3 (PH-3) and caspase-3 using immunohistochemistry and western blot analysis. The results showed that NTDs were observed mostly with HU treatment at an optimal dose of 225mg/kg b/w. RNR activity was inhibited and dNTP levels were decreased in HU-treated embryos with NTDs. Additionally, increased DNA damage, decreased proliferation, and increased caspase-3 were significant in NTDs embryos compared to the controls. Results indicated that HU induced murine NTDs model by disturbing dNTP metabolism and further led to the abnormal cell balance between proliferation and apoptosis. PMID:25527867

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

2015-02-01

51

Costs and Effects of Prenatal Screening Methods for Down Syndrome and Neural Tube Defects  

Microsoft Academic Search

Objectives: To evaluate prenatal screening methods for Down syndrome and neural tube defects (NTD) with regard to costs per detected case and the number of screening-related miscarriages. Methods: The screening methods compared were risk assessment tests, i.e. serum tests and nuchal translucency measurement (NT), and invasive testing through chorionic villus sampling (CVS) or amniocentesis. Costs, the number of cases detected

Mirjam Hoogendoorn; Silvia M. A. A. Evers; Peter C. J. I. Schielen; Marianne L. L. van Genugten; G. Ardine de Wit; André J. H. A. Ament

2008-01-01

52

Zebrafish Neural Tube Morphogenesis Requires Scribble-Dependent Oriented Cell Divisions  

PubMed Central

SUMMARY How control of subcellular events in single cells determines morphogenesis on the scale of the tissue is largely unresolved. The stereotyped cross-midline mitoses of progenitors in the zebrafish neural keel [1–4] provide a unique experimental paradigm for defining the role and control of single cell orientation for tissue-level morphogenesis in vivo. We show that the coordinated orientation of individual progenitor cell division in the neural keel is the cellular determinant required for morphogenesis into a neural tube epithelium with a single straight lumen. We find that Scribble is required for oriented cell division and that its function in this process is independent of canonical apico-basal and planar polarity pathways. We identify a role for Scribble in controlling clustering of ?-Catenin foci in dividing progenitors. Loss of either Scrib or of N-cadherin results in abnormally oriented mitoses, reduced cross-midline cell divisions and similar neural tube defects. We propose that Scribble-dependent nascent cell-cell adhesion clusters between neuroepithelial progenitors contribute to define orientation of their cell division. Finally, our data demonstrate that while oriented mitoses of individual cells determine neural tube architecture, the tissue can in turn feed back on its constituent cells to define their polarization and cell division orientation to ensure robust tissue morphogenesis. PMID:21185191

Žigman, Mihaela; Trinh, Le A.; Fraser, Scott E.; Moens, Cecilia B.

2014-01-01

53

Can we afford screening for neural tube defects? The South Wales experience.  

PubMed Central

Clinical and financial gains and losses accruing from five different options for screening for open neural tube defects were estimated, based principally on the results of detailed monitoring of inputs and outcomes and of process costs in the South Wales Anencephaly and Spina Bifida Study. As well as estimating the overall clinical costs of a screening service it was shown that if the prevalence, including terminations, of open neural tube defects is between 1.25 and five per 1000 births the financial cost of avoiding the birth of a seriously handicapped child who would survive for more than 24 hours is in the range 9000 pounds- 54000 pounds depending on the option adopted and the prevalence of the condition in the target population. Prevalence is the biggest determinant of cost. The data should provide a basis for assessment and discussion of resource priorities in the National Health Service. PMID:3917791

Hibbard, B M; Roberts, C J; Elder, G H; Evans, K T; Laurence, K M

1985-01-01

54

The cause of neural tube defects: some experiments and a hypothesis.  

PubMed Central

The mouse mutant curly-tail is an animal model for human neural tube defects (NTD). Around 60% spontaneously have NTD. It has been found that maternal administration of hydroxyurea, mitomycin C, or 5-fluorouracil on day 9 of pregnancy, that is, when the fetal neural tube is in the final stages of closure, leads to a significant reduction in the proportion of NTD (to 15 to 20%) in the offspring, while total litter size is unaffected. All these substances are inhibitors of DNA synthesis, yet are apparently beneficial to subjects predisposed to NTD. As a consequence, it is suggested that the underlying mechanism causing NTD in the mice, and also in man, is a basic metabolic defect in DNA synthesis which affects cell replication and results in abnormal morphogenesis of the neuraxis. PMID:6876107

Seller, M J

1983-01-01

55

C5a receptor signaling prevents folate deficiency-induced neural tube defects in mice.  

PubMed

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. In this study, 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 wild-type 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

2013-04-01

56

The mouse Ovol2 gene is required for cranial neural tube development  

PubMed Central

The Ovo gene family encodes a group of evolutionarily conserved transcription factors and includes members that reside downstream of key developmental signaling pathways such as Wg/Wnt and BMP/TGF-?. In the current study, we explore the function of Ovol2, one of three Ovo paralogues in mice. We report that Ovol2 is expressed during early–mid embryogenesis, particularly in the inner cell mass at E3.5, in epiblast at E6.5, and at later stages in ectodermally derived tissues such as the rostral surface (epidermal) ectoderm. Embryos in which Ovol2 is ablated exhibit lethality by E10.5, prior to which they display severe defects including an open cranial neural tube. The neural defects are associated with improper Shh expression in the underlying rostral axial mesoderm and localized changes of neural marker expression along the dorsoventral axis, as well as with expanded cranial neural tissue and reduced cranial surface ectoderm culminating in a lateral shift of the neuroectoderm/surface ectoderm border. We propose that these defects reflect the involvement of Ovol2 in independent processes such as regionalized gene expression and neural/non-neural ectodermal patterning. Additionally, we present evidence that Ovol2 is required for efficient migration and survival of neural crest cells that arise at the neuroectoderm/surface ectoderm border, but not for their initial formation. Collectively, our studies indicate that Ovol2 is a key regulator of neural development and reveal a previously unexplored role for Ovo genes in mammalian embryogenesis. PMID:16423343

Mackay, Douglas R.; Hu, Ming; Li, Baoan; Rhéaume, Catherine; Dai, Xing

2010-01-01

57

Shroom, a PDZ Domain–Containing Actin-Binding Protein, Is Required for Neural Tube Morphogenesis in Mice  

Microsoft Academic Search

Using gene trap mutagenesis, we have identified a mutation in mice that causes exencephaly, acrania, facial clefting, and spina bifida, all of which can be attributed to failed neural tube closure. This mutation is designated shroom (shrm) because the neural folds “mushroom” outward and do not converge at the dorsal midline. shrm encodes a PDZ domain protein that is involved

Jeffrey D. Hildebrand; Philippe Soriano

1999-01-01

58

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

59

Sonic hedgehog induces the differentiation of ventral forebrain neurons: A common signal for ventral patterning within the neural tube  

Microsoft Academic Search

The vertebrate hedgehog-related gene Sonic hedge-hog (Shh) is expressed in ventral domains along the entire rostrocaudal length of the neural tube, including the forebrain. We show here that SHH induces the differentiation of ventral neuronal cell types in explants derived from prospective forebrain regions of the neural plate. Neurons induced in explants derived from both diencephalic and telencephalic levels of

J Ericson; J Muhr; M Placzek; T Lints; T. M Jessel; T Edlund

1995-01-01

60

Estimating the burden of neural tube defects in low– and middle–income countries  

PubMed Central

Background To provide an estimate for the burden of neural tube defects (NTD) in low– and middle–income countries (LMIC) and explore potential public health policies that may be implemented. Although effective interventions are available to prevent NTD, there is still considerable childhood morbidity and mortality present in LMIC. Methods A search of Medline, EMBASE, Global Health Library and PubMed identified 37 relevant studies that provided estimates of the burden of NTD in LMIC. Information on burden of total NTD and specific NTD types was separated according to the denominator into two groups: (i) estimates based on the number of live births only; and (ii) live births, stillbirths and terminations. The data was then extracted and analysed. Results The search retrieved NTD burden from 18 countries in 6 WHO regions. The overall burden calculated using the median from studies based on livebirths was 1.67/1000 (IQR?=?0.98–3.49) for total NTD burden, 1.13/1000 (IQR?=?0.75–1.73) for spina bifida, 0.25/1000 (IQR?=?0.08–1.07) for anencephaly and 0.15/1000 (IQR?=?0.08–0.23) for encephalocele. Corresponding estimates based on all pregnancies resulting in live births, still births and terminations were 2.55/1000 (IQR?=?1.56–3.91) for total NTD burden, 1.04/1000 (IQR?=?0.67–2.48) for spina bifida, 1.03/1000 (IQR?=?0.67–1.60) for anencephaly and 0.21 (IQR?=?0.16–0.28) for encephalocele. This translates into about 190?000neonates who are born each year with NTD in LMIC. Conclusion Limited available data on NTD in LMIC indicates the need for additional research that would improve the estimated burden of NTD and recommend suitable aid policies through maternal education on folic acid supplementation or food fortification. PMID:24976961

Lo, Annie; Polšek, Dora; Sidhu, Simrita

2014-01-01

61

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

62

Natural history of hydrocephalus in children with spinal open neural tube defect  

PubMed Central

Background: The long-term prognosis of patients with Spinal Open Neural Tube Defect (SONTD)-associated hydrocephalus is not well known. This study was conducted to ascertain the incidence and natural history of hydrocephalus in patients with SONTD. Methods: All 82 patients with SONTD referred to Neurosurgery/Spina Bifida Clinics at King Khalid University Hospital, Riyadh, Saudi Arabia (January 1995 - July 2010) were studied and followed for a period of 1-16 years. Patients were divided into three groups: Group “A” with active hydrocephalus treated with ventriculoperitoneal shunt (VPS), or endoscopic third ventriculostomy (ETV); Group “B” with compensated hydrocephalus; and Group “C” with no hydrocephalus. Timing of shunt insertion, complications of treatment and status of hydrocephalus were analyzed. Results: The mean age of the 82 patients was 7.4 years (range 1-16 years). Group “A” included 59 (72%) patients, Group “B” 7 (8.5%) patients, and Group “C” 16 (19.5%) patients. Chiari malformation type II was found in 71 (86.6%) patients, 57 of whom (80%) were in Group “A” with active hydrocephalus. They were treated by VPS (51 patients) and ETV (8 patients). The shunts were revised or replaced in 10 (19.6%) patients due to obstruction or infection. Primary ETV failed in 3/8 patients, and treated by VPS. None of those in Groups “B” or “C” required treatment for hydrocephalus during the follow up. Conclusion: Hydrocephalus affects the majority of patients with SONTD who have Myelomeningocele (MMC) and CM II and requires close surveillance and prompt management. Children with SONTD should routinely undergo MRI examination of brain and craniocervical junction to clarify ventricular size, and the presence of CM II. PMID:23087828

Elgamal, Essam A.

2012-01-01

63

Uncoupling Protein 2 Polymorphisms as Risk Factors for Neural Tube Defects  

PubMed Central

BACKGROUND: Both environmental and genetic factors are involved in the etiology of neural tube defects (NTDs). Inadequate folate intake and obesity are important environmental risk factors. Several folate-related genetic variants have been identified as risk factors; however, little is known about how genetic variants relate to the increased risk seen in obese women. Uncoupling Protein 2 (UCP2) is an attractive candidate to screen for NTD risk because of its possible role in obesity as well as energy metabolism, type-2 diabetes, and the regulation of reactive oxygen species. Interestingly, a previous study found that a common UCP2 compound homozygous genotype was associated with a threefold increase in NTD risk. METHODS: We evaluated three polymorphisms, ?866G>A, A55V, and the 3?UTR 45bp insertion/deletion, as risk factors for NTDs in Irish NTD cases (N=169), their mothers (N=163), their fathers (N=167) and normal control subjects (N=332). RESULTS: Allele and genotype frequencies were not significantly different when comparing NTD mothers, NTD fathers, or affected children to controls. Additionally, the previously reported risk genotype (combined homozygosity of 55VV and 3?UTR 45bp deletion/deletion) was not present at a higher frequency in any NTD group when compared to controls. CONCLUSIONS: In our Irish study population, UCP2 polymorphisms do not influence NTD risk. Moreover, the prevalence of this allele in other populations was similar to the Irish prevalence but far lower than reported in the previous NTD study, suggesting that this previous finding of an association with NTDs might have been due to an unrepresentative study sample. PMID:19137581

Mitchell, Adam; Pangilinan, Faith; VanderMeer, Julie; Molloy, Anne M.; Troendle, James; Conley, Mary; Kirke, Peadar N.; Scott, John M.; Brody, Lawrence C.; Mills, James L.

2008-01-01

64

Junctional neurulation: a unique developmental program shaping a discrete region of the spinal cord highly susceptible to neural tube defects.  

PubMed

In higher vertebrates, the primordium of the nervous system, the neural tube, is shaped along the rostrocaudal axis through two consecutive, radically different processes referred to as primary and secondary neurulation. Failures in neurulation lead to severe anomalies of the nervous system, called neural tube defects (NTDs), which are among the most common congenital malformations in humans. Mechanisms causing NTDs in humans remain ill-defined. Of particular interest, the thoracolumbar region, which encompasses many NTD cases in the spine, corresponds to the junction between primary and secondary neurulations. Elucidating which developmental processes operate during neurulation in this region is therefore pivotal to unraveling the etiology of NTDs. Here, using the chick embryo as a model, we show that, at the junction, the neural tube is elaborated by a unique developmental program involving concerted movements of elevation and folding combined with local cell ingression and accretion. This process ensures the topological continuity between the primary and secondary neural tubes while supplying all neural progenitors of both the junctional and secondary neural tubes. Because it is distinct from the other neurulation events, we term this phenomenon junctional neurulation. Moreover, the planar-cell-polarity member, Prickle-1, is recruited specifically during junctional neurulation and its misexpression within a limited time period suffices to cause anomalies that phenocopy lower spine NTDs in human. Our study thus provides a molecular and cellular basis for understanding the causality of NTD prevalence in humans and ascribes to Prickle-1 a critical role in lower spinal cord formation. PMID:25253865

Dady, Alwyn; Havis, Emmanuelle; Escriou, Virginie; Catala, Martin; Duband, Jean-Loup

2014-09-24

65

Prevalence of neural tube defects in South Australia, 1966-91: effectiveness and impact of prenatal diagnosis.  

PubMed Central

OBJECTIVE--To determine trends in total prevalence of neural tube defects in South Australia during 1966-91, the impact of prenatal diagnosis on birth prevalence, and the effectiveness of prenatal screening for neural tube defects in 1986-91. DESIGN--All births and terminations of pregnancy affected by neural tube defects and information on prenatal screening were ascertained from multiple sources including the South Australian perinatal and abortion statistics collections, birth defects register, and state maternal serum alpha fetoprotein screening programme. SETTING--Southern Australia. SUBJECTS--All 1058 births and terminations of pregnancy affected by neural tube defects in 1966-91. MAIN OUTCOME MEASURES--Total prevalence and birth prevalence of individual and all neural tube defects. The proportion of screened cases detected prenatally. RESULTS--Total prevalence of neural tube defects during 1966-91 was 2.01/1000 births with no upward or downward trend. However, birth prevalence fell significantly (by 5.1% a year), with an 84% reduction from 2.29/1000 births in 1966 to 0.35/1000 in 1991 (relative risk = 0.16, 95% confidence interval 0.07 to 0.34). The fall was 96% for anencephaly and 82% for spina bifida. 85% of defects, both open and closed, were detected before 28 weeks' gestation in women screened by serum alpha fetoprotein or mid-trimester ultrasonography, or both, in 1986-91 (99.0% for anencephaly and 75.7% for spina bifida). CONCLUSIONS--While the total prevalence of neural tube defects in South Australia remained stable, prenatal diagnosis and termination of pregnancy resulted in an 84% fall in birth prevalence during 1966-91. Screening detected over four fifths of cases in 1986-91. PMID:8401091

Chan, A; Robertson, E F; Haan, E A; Keane, R J; Ranieri, E; Carney, A

1993-01-01

66

Lulu Regulates Shroom-Induced Apical Constriction during Neural Tube Closure  

PubMed Central

Apical constriction is an essential cell behavior during neural tube closure, but its underlying mechanisms are not fully understood. Lulu, or EPB4.1l5, is a FERM domain protein that has been implicated in apical constriction and actomyosin contractility in mouse embryos and cultured cells. Interference with the function of Lulu in Xenopus embryos by a specific antisense morpholino oligonucleotide or a carboxy-terminal fragment of Lulu impaired apical constriction during neural plate hinge formation. This effect was likely due to lack of actomyosin contractility in superficial neuroectodermal cells. By contrast, overexpression of Lulu RNA in embryonic ectoderm cells triggered ectopic apico-basal elongation and apical constriction, accompanied by the apical recruitment of F-actin. Depletion of endogenous Lulu disrupted the localization and activity of Shroom3, a PDZ-containing actin-binding protein that has also been implicated in apical constriction. Furthermore, Lulu and Shroom3 RNAs cooperated in triggering ectopic apical constriction in embryonic ectoderm. Our findings reveal that Lulu is essential for Shroom3-dependent apical constriction during vertebrate neural tube closure. PMID:24282618

Chu, Chih-Wen; Gerstenzang, Emma; Ossipova, Olga; Sokol, Sergei Y.

2013-01-01

67

Regulation of Patched by Sonic Hedgehog in the Developing Neural Tube  

NASA Astrophysics Data System (ADS)

Ventral cell fates in the central nervous system are induced by Sonic hedgehog, a homolog of hedgehog, a secreted Drosophila protein. In the central nervous system, Sonic hedgehog has been identified as the signal inducing floor plate, motor neurons, and dopaminergic neurons. Sonic hedgehog is also involved in the induction of ventral cell type in the developing somites. ptc is a key gene in the Drosophila hedgehog signaling pathway where it is involved in transducing the hedgehog signal and is also a transcriptional target of the signal. PTC, a vertebrate homolog of this Drosophila gene, is genetically downstream of Sonic hedgehog (Shh) in the limb bud. We analyze PTC expression during chicken neural and somite development and find it expressed in all regions of these tissues known to be responsive to Sonic hedgehog signal. As in the limb bud, ectopic expression of Sonic hedgehog leads to ectopic induction of PTC in the neural tube and paraxial mesoderm. This conservation of regulation allows us to use PTC as a marker for Sonic hedgehog response. The pattern of PTC expression suggests that Sonic hedgehog may play an inductive role in more dorsal regions of the neural tube than have been previously demonstrated. Examination of the pattern of PTC expression also suggests that PTC may act in a negative feedback loop to attenuate hedgehog signaling.

Marigo, Valeria; Tabin, Clifford J.

1996-09-01

68

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

69

Neural tube defects in New South Wales: management and preventive policies, 1965-1980.  

PubMed

This paper reviews the results of the programme of antenatal testing and selective termination of fetuses with anencephaly and spina bifida in New South Wales over the last eight years. It discusses the problems associated with pregnancy screening, with reference to those involved in selection for treatment of newborn infants with spina bifida. The incidence of neural tube defects has been declining, and this, although possibly the result of early termination of affected fetuses, may have its basis in a worldwide trend. Preventive action based on a more precise understanding of aetiological factors will further decrease the incidence, thereby reducing the load of long-term handicapped survivors. PMID:6174849

Field, B R; Kerr, C B

70

Evaluation of common genetic variants in 82 candidate genes as risk factors for neural tube defects  

PubMed Central

Background Neural tube defects (NTDs) are common birth defects (~1 in 1000 pregnancies in the US and Europe) that have complex origins, including environmental and genetic factors. A low level of maternal folate is one well-established risk factor, with maternal periconceptional folic acid supplementation reducing the occurrence of NTD pregnancies by 50-70%. Gene variants in the folate metabolic pathway (e.g., MTHFR rs1801133 (677?C?>?T) and MTHFD1 rs2236225 (R653Q)) have been found to increase NTD risk. We hypothesized that variants in additional folate/B12 pathway genes contribute to NTD risk. Methods A tagSNP approach was used to screen common variation in 82 candidate genes selected from the folate/B12 pathway and NTD mouse models. We initially genotyped polymorphisms in 320 Irish triads (NTD cases and their parents), including 301 cases and 341 Irish controls to perform case–control and family based association tests. Significantly associated polymorphisms were genotyped in a secondary set of 250 families that included 229 cases and 658 controls. The combined results for 1441 SNPs were used in a joint analysis to test for case and maternal effects. Results Nearly 70 SNPs in 30 genes were found to be associated with NTDs at the p?

2012-01-01

71

Integration of Signals along Orthogonal Axes of the Vertebrate Neural Tube Controls Progenitor Competence and Increases Cell Diversity  

PubMed Central

A relatively small number of signals are responsible for the variety and pattern of cell types generated in developing embryos. In part this is achieved by exploiting differences in the concentration or duration of signaling to increase cellular diversity. In addition, however, changes in cellular competence—temporal shifts in the response of cells to a signal—contribute to the array of cell types generated. Here we investigate how these two mechanisms are combined in the vertebrate neural tube to increase the range of cell types and deliver spatial control over their location. We provide evidence that FGF signaling emanating from the posterior of the embryo controls a change in competence of neural progenitors to Shh and BMP, the two morphogens that are responsible for patterning the ventral and dorsal regions of the neural tube, respectively. Newly generated neural progenitors are exposed to FGF signaling, and this maintains the expression of the Nk1-class transcription factor Nkx1.2. Ventrally, this acts in combination with the Shh-induced transcription factor FoxA2 to specify floor plate cells and dorsally in combination with BMP signaling to induce neural crest cells. As development progresses, the intersection of FGF with BMP and Shh signals is interrupted by axis elongation, resulting in the loss of Nkx1.2 expression and allowing the induction of ventral and dorsal interneuron progenitors by Shh and BMP signaling to supervene. Hence a similar mechanism increases cell type diversity at both dorsal and ventral poles of the neural tube. Together these data reveal that tissue morphogenesis produces changes in the coincidence of signals acting along orthogonal axes of the neural tube and this is used to define spatial and temporal transitions in the competence of cells to interpret morphogen signaling. PMID:25026549

Sasai, Noriaki; Kutejova, Eva; Briscoe, James

2014-01-01

72

Major derivatives of the ectoderm germ layer Primary neurulation: neural tube formation in the chick embryo (Part 1)  

E-print Network

in the chick embryo (Part 1) #12;Primary neurulation: neural tube formation in the chick embryo (Part 2) #12;Neurulation in an amphibian embryo, showing early, middle, and late neurulae in each case (Part 1) #12;Neurulation in an amphibian embryo, showing early, middle, and late neurulae in each case (Part 2) #12

73

Increased sphingoid base-1-phosphates and failure of neural tube closure after exposure to fumonisin or FTY720  

Technology Transfer Automated Retrieval System (TEKTRAN)

Fumonisin B1 (FB1) is a mycotoxin produced by a common fungal contaminant of corn. Ingestion of FB1-contaminated food is associated with increased risk for neural tube defects (NTDs). FB1 induces NTDs in inbred LM/Bc mice. FB1 inhibits ceramide synthase in de novo sphingolipid biosynthesis, resultin...

74

Maternal Serum ?-Fetoprotein Screening for the Detection of Neural Tube Defects—Report of a Pilot Program  

PubMed Central

We tested 10,715 low-risk pregnancies in a voluntary maternal serum ?-fetoprotein screening program for the detection of neural tube defects in California. In all, 5.3 percent of women had one elevated serum level, 3.3 percent were referred for sonography and 1.5 percent for amniocentesis. There were 12 cases of open neural tube defects (1.1 per 1,000); all of the mothers had one elevated serum ?fetoprotein level: nine (75 percent) completed the protocol and the neural tube defects were correctly identified. No normal pregnancies were terminated. The risk of an open neural tube defect occurring was about 1 in 50 after the first abnormal serum level and 1 in 15 at amniocentesis. We found significantly increased risk for fetal death and low birth weight after one elevated serum ?-fetoprotein level, though the likelihood of a normal pregnancy outcome was about 80 percent. Maternal serum screening was also useful in identifying twin pregnancies and correcting underestimated gestational dates. PMID:6191442

Crandall, Barbara F.; Robertson, Robert D.; Lebherz, Thomas B.; King, William; Schroth, Phillip C.

1983-01-01

75

Use of Family History Information for Neural Tube Defect Prevention: Integration into State-Based Recurrence Prevention Programs  

ERIC Educational Resources Information Center

A family history of neural tube defects (NTDs) can increase the risk of a pregnancy affected by an NTD. Periconceptional folic acid use decreases this risk. Purpose: Our objective was to determine whether second-degree relatives of NTD-affected children showed differences in folic acid use compared with the general population and to provide them…

Green, Ridgely Fisk; Ehrhardt, Joan; Ruttenber, Margaret F.; Olney, Richard S.

2011-01-01

76

Neural tube defects, maternal cohorts, and age: a pointer to aetiology.  

PubMed Central

The effects of maternal year of birth and age on the declining prevalence of neural tube defects after 1972-3 were examined using 403 cases ascertained in a prospective study in the Fylde of Lancashire during 1957-89. Matched case-control data were analysed using conditional logistic regression analysis. The risk of an anencephalic baby was significantly greater for older mothers, but changes in the maternal age distribution in the population did not appear to be relevant to the recent decline in prevalence. Antenatal diagnosis and termination of pregnancy was the major cause. Mothers born before 1950 were at significantly greater risk of producing a baby with spina bifida or cranium bifidum. We suggest that abandonment of mercury as a therapeutic agent for infants in the early 1950s is a possible factor in the current decline of these malformations. PMID:1953007

Bound, J P; Francis, B J; Harvey, P W

1991-01-01

77

Perturbations in choline metabolism cause neural tube defects in mouse embryos in vitro.  

PubMed

A role for choline during early stages of mammalian embryogenesis has not been established, although recent studies show that inhibitors of choline uptake and metabolism, 2-dimethylaminoethanol (DMAE), and 1-O-octadecyl-2-O-methyl-rac-glycero-3-phosphocholine (ET-18-OCH3), produce neural tube defects in mouse embryos grown in vitro. To determine potential mechanisms responsible for these abnormalities, choline metabolism in the presence or absence of these inhibitors was evaluated in cultured, neurulating mouse embryos by using chromatographic techniques. Results showed that 90%-95% of 14C-choline was incorporated into phosphocholine and phosphatidylcholine (PtdCho), which was metabolized to sphingomyelin. Choline was oxidized to betaine, and betaine homocysteine methyltransferase was expressed. Acetylcholine was synthesized in yolk sacs, but 70 kDa choline acetyltransferase was undetectable by immunoblot. DMAE reduced embryonic choline uptake and inhibited phosphocholine, PtdCho, phosphatidylethanolamine (PtdEtn), and sphingomyelin synthesis. ET-18-OCH3 also inhibited PtdCho synthesis. In embryos and yolk sacs incubated with 3H-ethanolamine, 95% of recovered label was PtdEtn, but PtdEtn was not converted to PtdCho, which suggested that phosphatidylethanolamine methyltransferase (PeMT) activity was absent. In ET-18-OCH3 treated yolk sacs, PtdEtn was increased, but PtdCho was still not generated through PeMT. Results suggest that endogenous PtdCho synthesis is important during neurulation and that perturbed choline metabolism contributes to neural tube defects produced by DMAE and ET-18-OCH3. PMID:11919173

Fisher, Melanie C; Zeisel, Steven H; Mar, Mei-Heng; Sadler, Thomas W

2002-04-01

78

Methanol-induced neural tube defects in mice: Characterization of lesions, target and teratogen  

SciTech Connect

The present studies investigated the hypothesis that methanol induces neural tube defects (e.g., exenephaly) through the cytotoxic action of its metabolite, formate, upon embryonic neuroepithelium during neurulation. Methanol was tested because of concerns raised by the proposed heavier use of this alcohol in automobile fuels, which could result in increased exposure of the general public. Neurulation (gestational days [GD] 7-9 in mice) was shown to be the period of greatest vulnerability. Pregnant mice inhaled methanol (5,000 to 15,000 ppm) for 6 hr/day either during GD 7-9 or during a encephaly was observed only if exposure to [>=] 10,000 ppm encompassed GD 7 and/or GD 8. Aberrant neural tube closure was confirmed as the pathogensis by demonstrating persistent patency of the anterior neuropore in embryos. Peak concentrations of 431 mmol methanol/kg and 14 mmol formate/kg were measured in embryos following maternal methanol inhalation at a teratogenic level (15,000 ppm for 6 hr on GD 8). Autoradiography of pregnant mice after intravenous injection with 0.06 or 6 mmol [sup 14]C-formate/kg on GD 8 revealed selective localization of radioactivity to the neuroepithelium within 10 minutes after administration, with at least a two fold greater level in each tissue of formate-exposed embryos. Exposure in vitro to either 187 mM methanol or [>=]12 mM formate for 12 hr delayed closure of the anterior neuropore in neurulating mouse embryos. In addition, in vitro exposure to formate resulted in lower reduction of 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bormide (MTT) and decreased levels of ATP in cephalic tissues of embryos. Formate also reduced MTT staining in neuroepithelium and mesoderm, suggesting these embryonic tissues as potential targets.

Bolon, B.N.

1993-01-01

79

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

80

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

81

Effects of methionine on the cytoplasmic distribution of actin and tubulin during neural tube closure in rat?embryos  

PubMed Central

Research has previously shown that, without methionine supplements, neural tube proteins of rat embryos cultured on bovine sera were hypomethylated and neural tubes failed to close. In the present study, to identify the proteins that became methylated during neurulation, rat embryos were first cultured on methionine-deficient bovine serum for 40 hr, then incubated with puromycin for 1 hr, and, finally, incubated with [methyl-14C]methionine and puromycin for 5 hr. On the basis of molecular weights, isoelectric points, and Western immunoblots, the methyl-14C-labeled proteins were identified as actin, ??-tubulin, and neurofilament L. Indirect immunofluorescence studies indicated that without the addition of methionine to the culture, localization of actin and ??-tubulin in the basal cytoplasm did not occur and these neuroepithelial cells lost their columnar morphology. PMID:9012820

Moephuli, Shadrack?R.; Klein, Norman?W.; Baldwin, Michael?T.; Krider, Hallie?M.

1997-01-01

82

Identification and characterization of novel rare mutations in the planar cell polarity gene PRICKLE1 in human neural tube defects  

PubMed Central

The planar cell polarity (PCP) pathway controls the process of convergent extension (CE) during gastrulation and neural tube closure and has been implicated in the pathogenesis of neural tube defects (NTDs) in animal models and human cohorts. In this study, we analyzed the role of one core PCP gene PRICKLE1 in these malformations. We screened this gene in 810 unrelated NTD patients and identified 7 rare missense heterozygous mutations that were absent in all controls analyzed and predicted to be functionally deleterious using bioinformatics. Functional validation of 5 PRICKLE1 variants in a zebrafish model demonstrated that one variant, p.Arg682Cys, antagonized the CE phenotype induced by the wild-type zebrafish prickle1a in a dominant fashion. Our study demonstrates that PRICKLE1 could act as a predisposing factor to human NTDs and further expands our knowledge of the role of PCP genes in the pathogenesis of these malformations. PMID:21901791

Bosoi, Ciprian M.; Capra, Valeria; Allache, Redouane; Trinh, Vincent Quoc-Huy; De Marco, Patrizia; Merello, Elisa; Drapeau, Pierre; Bassuk, Alexander G.; Kibar, Zoha

2011-01-01

83

The role of folic acid fortification in neural tube defects: a review.  

PubMed

The worldwide prevalence of neural tube defects (NTDs) has fallen noticeably during the past 30 years, but the specific etiology and causative mechanism of NTDs remain unknown. Since introduction of mandatory fortification of grains with folic acid, a further decrease in NTD prevalence has been reported in North America and other countries with large variations among ethnic subgroups. However, a significant portion of NTDs still persists. Population data suggest that women of childbearing age may not yet be adequately targeted, while the general population may be overfortified with folic acid. While an excessive folate intake may be associated with adverse effects, there remains uncertainty about the minimum effective folate intake and status required for NTD prevention, and the safe upper folate level. Besides folate, several other lifestyle and environmental factors as well as genetic variations may influence NTD development, possibly by affecting one-carbon metabolism and thus epigenetic events. In conclusion, mandatory folic acid fortification plays a significant part in the reduction of NTD prevalence, but possibly at a cost and with a portion of NTDs remaining. More effective preventive strategies require better understanding of the etiology of this group of birth defects. PMID:24007422

Osterhues, Anja; Ali, Nyima S; Michels, Karin B

2013-01-01

84

Spirulina (arthrospira) protects against valproic acid-induced neural tube defects in mice.  

PubMed

Valproic acid (VPA) is a potent inducer of neural tube defects in human and mouse, its teratogenicity is associated with its potential to generation of free radicals and increase oxidative stress. Furthermore, spirulina (SP) has shown pharmacological properties against teratogenicity, which are attributed to its antioxidant potential. Accordingly, the present study was performed to investigate the influence of SP on the teratogenicity of VPA in imprinting control region mice and the possible mechanisms of action. VPA (sodium valproate) was administered intraperitoneally to mice on gestation day (GD) 8 at a dose of 600 mg/kg. SP was given orally at 125, 250, and 500 mg/kg daily from GD0 through GD18. The most common finding in fetuses with VPA exposure was exencephaly. SP decreased the incidence of this and other malformations and increased levels of superoxide dismutase, catalase, and glutathione peroxidase. In conclusion, these results illustrate the protective action of SP through its antioxidant activity against VPA-induced teratogenicity. PMID:23134463

Escalona-Cardoso, Gerardo N; Paniagua-Castro, Norma; Pérez-Pastén, Ricardo; Chamorro-Cevallos, Germán

2012-12-01

85

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

86

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

87

[Folic acid use by pregnant women in Israel for preventing neural tube defects].  

PubMed

Spina bifida and anencephaly are the most common, serious malformations in neural tube defects (NTD). Randomized trials in the last 2 decades have demonstrated that folic acid, 0.4 mg/d, reduces the incidence of NTD by more than 50%. We investigated the use of folic acid and multivitamins containing folic acid in childbearing women. Of 221 women interviewed, 67 (30%) regularly took pills containing 0.4 mg folic acid. Women with higher educational levels were more likely to take multivitamins with folic acid than were the less educated (p = 0.05). Of the women who took folic acid, only 5 (7.5%) used separate folic acid tablets, before and during their pregnancy. The rest used multivitamins containing folic acid. The 5 women who took folic acid separately were college-educated and nonreligious, and they took multivitamins in addition (p > 0.05). Of the women interviewed, 58 (26.2%) were Bedouin of the Negev. 24 (41.4%) of them took pills containing folic acid on a regular basis. This percentage is higher than that in the Jewish women in the study who took folic acid for prevention of NTD (17%; p = 0.038). Most of the women took folic acid after the first trimester. Only a minority took daily periconceptional folic acid. Multivitamins containing 0.4 mg of folic acid were more popular than folic acid tablets alone. This study emphasizes the need for continuing efforts to increase consumption of folic acid and awareness of its benefits among women of childbearing age. PMID:11341184

Gil, Z; Aran, A; Friedman, O; Beni-Adani, L; Constantini, S

2000-12-01

88

Association of selected persistent organic pollutants in the placenta with the risk of neural tube defects  

PubMed Central

Persistent organic pollutants (POPs) have been associated with a wide range of adverse health effects. Our case–control study was performed to explore the association between placental levels of selected POPs and risks for neural tube defects (NTDs) in a Chinese population with a high prevalence of NTDs. Cases included 80 fetuses or newborns with NTDs, whereas the controls were 50 healthy, nonmalformed newborn infants. Placental concentrations of polycyclic aromatic hydrocarbons (PAHs), organochlorine pesticides, polychlorinated biphenyls, and polybrominated diphenyl ethers were analyzed by gas chromatography–mass spectrometry. The medians of PAHs, o,p?-isomers of dichlorodiphenyltrichloroethane (DDT) and metabolites, ?- and ?-hexachlorocyclohexane (HCH), and ?-endosulfan were significantly higher in case placentas than in controls. PAH concentrations above the median were associated with a 4.52-fold [95% confidence interval (CI), 2.10–9.74) increased risk for any NTDs, and 5.84- (95% CI, 2.28–14.96) and 3.71-fold (95% CI, 1.57–8.79) increased risks for anencephaly and spina bifida, respectively. A dose–response relationship was observed between PAH levels and the risk of NTDs, with odds ratios for the second, third, and fourth quartiles, compared with the first, of 1.77- (95% CI, 0.66–4.76), 3.83- (95% CI, 1.37–10.75), and 11.67-fold (95% CI, 3.28–41.49), respectively. A dose–response relationship was observed for anencephaly and spina bifida subtypes. Similar results were observed for o,p?-DDT and metabolites, ?-HCH, ?-HCH, and ?-endosulfan, whereas no dose–response relationship was observed for the last two pollutants. Elevated placental concentrations of PAHs, o,p?-DDT and metabolites, and ?-HCH were associated with increased risks of NTDs in this population. PMID:21768370

Ren, Aiguo; Qiu, Xinghua; Jin, Lei; Ma, Jin; Li, Zhiwen; Zhang, Le; Zhu, Huiping; Finnell, Richard H.; Zhu, Tong

2011-01-01

89

Neural tube defects: an analysis of neighbourhood- and individual-level socio-economic characteristics  

PubMed Central

Summary Several studies have reported that neural tube defects (NTD) occur more frequently among children born to women of lower socio-economic status (SES). This study investigated the relationship between individual- and neighbourhood-level SES and the risk of an NTD-affected pregnancy. Data were drawn from a population-based case-control study of fetuses and infants among a cohort of California births between July 1999 and June 2003. Information on individual SES was obtained via telephone interviews with mothers of 337 (76% of eligible) cases and 626 (79% of eligible) non-malformed liveborn controls. Respondents’ addresses were linked to the 2000 US Census to characterise six measures of neighbourhood SES (education, poverty, unemployment, occupation, crowding and rental occupancy). The analyses indicated that relative to women with a high school education, those with less than a high school education had a 1.7-fold increased risk of delivering infants with NTDs [95% CI 1.2, 2.6]. Twofold elevated risks for NTDs were observed for women with less than a high school education who lived in neighbourhoods where a majority of residents had not graduated from high school [95% CI 1.3, 3.1]. No consistent risk gradients were observed between NTD-affected pregnancies and indicators of lower neighbourhood SES. Results for phenotype subgroups were similar to those for all cases. Low maternal education was associated with an elevated risk of NTD in offspring. This risk varied by the education profile of the neighbourhood: women who did not graduate from high school and lived in less educated neighbourhoods exhibited a higher risk. PMID:19159398

Grewal, Jagteshwar; Carmichael, Suzan L.; Song, Jun; Shaw, Gary M.

2010-01-01

90

Placental concentrations of manganese and the risk of fetal neural tube defects.  

PubMed

Manganese (Mn) is an essential trace element required for normal growth, development, and cellular homeostasis, but excess Mn is toxic to the central nervous system. The present pilot study examined whether the level of Mn in the placenta was associated with the risk of fetal neural tube defects (NTDs). A case-control study was conducted. Cases were 80 fetuses or newborns with NTDs, and controls were 50 healthy, nonmalformed newborns. Placental Mn, zinc, copper, iron, and selenium were determined with inductively coupled plasma-mass spectrometry. The median Mn concentration was significantly higher in case placentas than in controls: cases, 131.60 ng/g (95% confidence interval [CI], 99.25-166.76); controls, 101.54 ng/g (95% CI, 80.14-119.79). Mn concentrations above the median were associated with a 4-fold (95% CI, 1.23-14.79) increased risk for any NTDs and a 7-fold (95% CI, 1.52-39.64) increased risk for spina bifida after other confounding factors were controlled. Elevated Mn levels were associated with an increased risk of anencephaly, although the adjusted odds ratio did not reach statistical significance. The association between higher Mn concentrations and risk of NTDs showed a clear dose-response relationship. Risk of NTDs increased to 1.51 (95% CI, 0.65-3.52) and 5.03 (95% CI, 1.89-13.33) for those whose placental Mn level was in the second and third tertiles, respectively, compared with the lowest tertile. Elevated placental concentrations of Mn may be associated with increased risks of NTDs in this population. PMID:23664920

Liu, Jufen; Jin, Lei; Zhang, Le; Li, Zhiwen; Wang, Linlin; Ye, Rongwei; Zhang, Yali; Ren, Aiguo

2013-10-01

91

Eddy Current Signature Classification of Steam Generator Tube Defects Using A Learning Vector Quantization Neural Network  

SciTech Connect

A major cause of failure in nuclear steam generators is degradation of their tubes. Although seven primary defect categories exist, one of the principal causes of tube failure is intergranular attack/stress corrosion cracking (IGA/SCC). This type of defect usually begins on the secondary side surface of the tubes and propagates both inwards and laterally. In many cases this defect is found at or near the tube support plates.

Gabe V. Garcia

2005-01-03

92

Statistical properties of cosmic-ray showers at ground level determined from photomultiplier-tube background registrations  

NASA Astrophysics Data System (ADS)

The fluctuations of cosmic-ray particles resulting from extensive air showers at ground level are well described by the two-parameter Poisson-driven Yule-Furry and negative-binomial counting probability distributions. The background signal from a single photomultiplier tube has been used to experimentally verify these results with remarkable precision, in spite of the simplicity of the underlying pure-birth stochastic process. Counting distributions from three different photomultiplier-tube detectors operated in the dark are presented, together with the theoretical predictions. Probability distributions of interevent times have also been obtained and these are found to be consistent with the observed clustering properties at the detector output. Our approach is expected to be of importance in quantum optics where cosmic-ray-shower particles can pose a significant limitation on the detection of squeezed light.

Teich, Malvin C.; Campos, Richard A.; Saleh, Bahaa E. A.

1987-11-01

93

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

PubMed

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 we focus on the role of FK506-binding protein 8 (FKBP8) in controlling neural cell identity through its antagonism of the Shh pathway. Our data indicate that disruption of FKBP8 function activates the Shh signaling pathway cell-autonomously at a step that is independent of the transmembrane protein Smoothened but dependent on the Gli2 transcription factor. This activation is also dependent on the kinesin-2 subunit Kif3a, a component of the intraflagellar transport (IFT) machinery used to generate cilia. Our data also indicate that non-cell-autonomous effects of the Fkbp8 mutation further contribute to the neural patterning phenotype and suggest that FKBP8 plays an indirect role in promoting Bone morphogenetic protein (BMP) signaling through antagonism of the Shh pathway. PMID:18590716

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

2008-09-01

94

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, André G.; Steegers-Theunissen, Régine P. M.

2013-01-01

95

Neural network analysis of fin-tube refrigerating heat exchanger with limited experimental data  

Microsoft Academic Search

We consider the problem of accuracy in heat rate estimations from artificial neural network (ANN) models of heat exchangers used for refrigeration applications. Limited experimental measurements from a manufacturer are used to show the capability of the neural network technique in modeling the heat transfer phenomena in these systems. A well-trained network correlates the data with errors of the same

Arturo Pacheco-Vega; Mihir Sen; K. T. Yang; Rodney L. McClain

2001-01-01

96

Deciphering axonal pathways of genetically defined groups of neurons in the chick neural tube utilizing in ovo electroporation.  

PubMed

Employment of enhancer elements to drive expression of reporter genes in neurons is a widely used paradigm for tracking axonal projection. For tracking axonal projection of spinal interneurons in vertebrates, germ line-targeted reporter genes yield bilaterally symmetric labeling. Therefore, it is hard to distinguish between the ipsi- and contra-laterally projecting axons. Unilateral electroporation into the chick neural tube provides a useful means to restrict expression of a reporter gene to one side of the central nervous system, and to follow axonal projection on both sides. This video demonstrates first how to handle the eggs prior to injection. At HH stage 18-20, DNA is injected into the sacral level of the neural tube, then tungsten electrodes are placed parallel to the embryo and short electrical pulses are administered with a pulse generator. The egg is sealed with tape and placed back into an incubator for further development. Three days later (E6) the spinal cord is removed as an open book preparation from embryo, fixed, and processed for whole mount antibody staining. The stained spinal cord is mounted on slide and visualized using confocal microscopy. PMID:20440258

Avraham, Oshri; Zisman, Sophie; Hadas, Yoav; Vald, Lilach; Klar, Avihu

2010-01-01

97

Neural networks and separation of Cosmic Microwave Background and astrophysical signals in sky maps  

E-print Network

The Independent Component Analysis (ICA) algorithm is implemented as a neural network for separating signals of different origin in astrophysical sky maps. Due to its self-organizing capability, it works without prior assumptions on the signals, neither on their frequency scaling, nor on the signal maps themselves; instead, it learns directly from the input data how to separate the physical components, making use of their statistical independence. To test the capabilities of this approach, we apply the ICA algorithm on sky patches, taken from simulations and observations, at the microwave frequencies, that are going to be deeply explored in a few years on the whole sky, by the Microwave Anisotropy Probe (MAP) and by the {\\sc Planck} Surveyor Satellite. The maps are at the frequencies of the Low Frequency Instrument (LFI) aboard the {\\sc Planck} satellite (30, 44, 70 and 100 GHz), and contain simulated astrophysical radio sources, Cosmic Microwave Background (CMB) radiation, and Galactic diffuse emissions from thermal dust and synchrotron. We show that the ICA algorithm is able to recover each signal, with precision going from 10% for the Galactic components to percent for CMB; radio sources are almost completely recovered down to a flux limit corresponding to $0.7\\sigma_{CMB}$, where $\\sigma_{CMB}$ is the rms level of CMB fluctuations. The signal recovering possesses equal quality on all the scales larger then the pixel size. In addition, we show that the frequency scalings of the input signals can be partially inferred from the ICA outputs, at the percent precision for the dominant components, radio sources and CMB.

C. Baccigalupi; L. Bedini; C. Burigana; G. De Zotti; A. Farusi; D. Maino; M. Maris; F. Perrotta; E. Salerno; L. Toffolatti; A. Tonazzini

2000-06-21

98

Modifying a sealed tube zinc reduction method for preparation of AMS graphite targets: Reducing background and attaining high precision  

NASA Astrophysics Data System (ADS)

The sealed tube zinc reduction method for converting CO 2 to graphite for AMS 14C measurements was originally developed for rapid production of graphite in biomedical tracer experiments. The method was usually thought to have low precision and a high background. We have modified the zinc reduction method originally outlined in Vogel [J.S. Vogel, Radiocarbon 34 (3) (1992) 344] by carefully controlling the amounts of reagents (zinc, titanium hydride and Co or Fe catalyst) and now routinely obtain a precision of 2-3‰ and a relatively low background of ˜50,000 14C years when analyzing for 14C at the Keck Carbon Cycle AMS facility at UC Irvine. Fractionation of carbon isotopes does occur during graphitization and depends on the graphitization yield, which can be affected by the amounts of reagents used and other conditions. The ?13C of our zinc-reduced graphite is usually lighter by 2-3‰ than the CO 2 from which it is made, but this is corrected for in our system by simultaneous measurement of 13C/ 12C along with 14C/ 12C by the spectrometer. This method is suitable for 14C enriched samples, as well as natural abundance 14C samples, especially those with modern 14C contents. With improved precision and background, we believe that many disciplines can benefit from this technique because of its low cost and rapid production of graphite.

Xu, Xiaomei; Trumbore, Susan E.; Zheng, Shuhui; Southon, John R.; McDuffee, Kelsey E.; Luttgen, Madelyn; Liu, Julia C.

2007-06-01

99

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

100

Apical accumulation of MARCKS in neural plate cells during neurulation in the chick embryo  

Microsoft Academic Search

BACKGROUND: The neural tube is formed by morphogenetic movements largely dependent on cytoskeletal dynamics. Actin and many of its associated proteins have been proposed as important mediators of neurulation. For instance, mice deficient in MARCKS, an actin cross-linking membrane-associated protein that is regulated by PKC and other kinases, present severe developmental defects, including failure of cranial neural tube closure. RESULTS:

Flavio R Zolessi; Cristina Arruti

2001-01-01

101

Folic acid and pantothenic acid protection against valproic acid-induced neural tube defects in CD-1 mice  

SciTech Connect

In utero exposure to valproic acid (VPA) during pregnancy is associated with an increased risk of neural tube defects (NTDs). Although the mechanism by which VPA mediates these effects is unknown, VPA-initiated changes in embryonic protein levels have been implicated. The objectives of this study were to investigate the effect of in utero VPA exposure on embryonic protein levels of p53, NF-{kappa}B, Pim-1, c-Myb, Bax, and Bcl-2 in the CD-1 mouse. We also evaluated the protective effects of folic acid and pantothenic acid on VPA-induced NTDs and VPA-induced embryonic protein changes in this model. Pregnant CD-1 mice were administered a teratogenic dose of VPA prior to neural tube closure and embryonic protein levels were analyzed. In our study, VPA (400 mg/kg)-induced NTDs (24%) and VPA-exposed embryos with an NTD showed a 2-fold increase in p53, and 4-fold decreases in NF-{kappa}B, Pim-1, and c-Myb protein levels compared to their phenotypically normal littermates (P < 0.05). Additionally, VPA increased the ratio of embryonic Bax/Bcl-2 protein levels (P < 0.05). Pretreatment of pregnant dams with either folic acid or pantothenic acid prior to VPA significantly protected against VPA-induced NTDs (P < 0.05). Folic acid also reduced VPA-induced alterations in p53, NF-{kappa}B, Pim-1, c-Myb, and Bax/Bcl-2 protein levels, while pantothenic acid prevented VPA-induced alterations in NF-{kappa}B, Pim-1, and c-Myb. We hypothesize that folic acid and pantothenic acid protect CD-1 embryos from VPA-induced NTDs by independent, but not mutually exclusive mechanisms, both of which may be mediated by the prevention of VPA-induced alterations in proteins involved in neurulation.

Dawson, Jennifer E. [Department of Pharmacology and Toxicology and School of Environmental Studies, Queen's University, Kingston, Ontario, K7L 3N6 (Canada); Raymond, Angela M. [Department of Pharmacology and Toxicology and School of Environmental Studies, Queen's University, Kingston, Ontario, K7L 3N6 (Canada); Winn, Louise M. [Department of Pharmacology and Toxicology and School of Environmental Studies, Queen's University, Kingston, Ontario, K7L 3N6 (Canada)]. E-mail: winnl@biology.queensu.ca

2006-03-01

102

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

103

Updated estimates of neural tube defects prevented by mandatory folic Acid fortification - United States, 1995-2011.  

PubMed

In 1992, the U.S. Public Health Service recommended that all women capable of becoming pregnant consume 400 µg of folic acid daily to prevent neural tube defects (NTDs). NTDs are major birth defects of the brain and spine that occur early in pregnancy as a result of improper closure of the embryonic neural tube, which can lead to death or varying degrees of disability. The two most common NTDs are anencephaly and spina bifida. Beginning in 1998, the United States mandated fortification of enriched cereal grain products with 140 µg of folic acid per 100 g. Immediately after mandatory fortification, the birth prevalence of NTD cases declined. Fortification was estimated to avert approximately 1,000 NTD-affected pregnancies annually. To provide updated estimates of the birth prevalence of NTDs in the period after introduction of mandatory folic acid fortification (i.e., the post-fortification period), data from 19 population-based birth defects surveillance programs in the United States, covering the years 1999-2011, were examined. After the initial decrease, NTD birth prevalence during the post-fortification period has remained relatively stable. The number of births occurring annually without NTDs that would otherwise have been affected is approximately 1,326 (95% confidence interval = 1,122-1,531). Mandatory folic acid fortification remains an effective public health intervention. There remain opportunities for prevention among women with lower folic acid intakes, especially among Hispanic women, to further reduce the prevalence of NTDs in the United States. PMID:25590678

Williams, Jennifer; Mai, Cara T; Mulinare, Joe; Isenburg, Jennifer; Flood, Timothy J; Ethen, Mary; Frohnert, Barbara; Kirby, Russell S

2015-01-16

104

The novel mouse mutant, chuzhoi, has disruption of Ptk7 protein and exhibits defects in neural tube, heart and lung development and abnormal planar cell polarity in the ear  

PubMed Central

Background The planar cell polarity (PCP) signalling pathway is fundamental to a number of key developmental events, including initiation of neural tube closure. Disruption of the PCP pathway causes the severe neural tube defect of craniorachischisis, in which almost the entire brain and spinal cord fails to close. Identification of mouse mutants with craniorachischisis has proven a powerful way of identifying molecules that are components or regulators of the PCP pathway. In addition, identification of an allelic series of mutants, including hypomorphs and neomorphs in addition to complete nulls, can provide novel genetic tools to help elucidate the function of the PCP proteins. Results We report the identification of a new N-ethyl-N-nitrosourea (ENU)-induced mutant with craniorachischisis, which we have named chuzhoi (chz). We demonstrate that chuzhoi mutant embryos fail to undergo initiation of neural tube closure, and have characteristics consistent with defective convergent extension. These characteristics include a broadened midline and reduced rate of increase of their length-to-width ratio. In addition, we demonstrate disruption in the orientation of outer hair cells in the inner ear, and defects in heart and lung development in chuzhoi mutants. We demonstrate a genetic interaction between chuzhoi mutants and both Vangl2Lp and Celsr1Crsh mutants, strengthening the hypothesis that chuzhoi is involved in regulating the PCP pathway. We demonstrate that chuzhoi maps to Chromosome 17 and carries a splice site mutation in Ptk7. This mutation results in the insertion of three amino acids into the Ptk7 protein and causes disruption of Ptk7 protein expression in chuzhoi mutants. Conclusions The chuzhoi mutant provides an additional genetic resource to help investigate the developmental basis of several congenital abnormalities including neural tube, heart and lung defects and their relationship to disruption of PCP. The chuzhoi mutation differentially affects the expression levels of the two Ptk7 protein isoforms and, while some Ptk7 protein can still be detected at the membrane, chuzhoi mutants demonstrate a significant reduction in membrane localization of Ptk7 protein. This mutant provides a useful tool to allow future studies aimed at understanding the molecular function of Ptk7. PMID:20704721

2010-01-01

105

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

PubMed Central

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

106

Occurrence of neural tube defects in pregnancy: an excess of cases in a 2773-km2 area in Central Italy.  

PubMed

Neural tube defects (NTDs) have a complex and imperfectly understood etiology, in which both genetic and environmental factors might be involved. The aim of the study was to describe an excess of cases of NTDs in a small area in central Italy. Over a 2-wk period in autumn 2002, three diagnoses of anencephaly were made in a 2773-km(2) area. As a consequence of these events, information on known risk factors as well as data on environmental changes, or epidemics of infectious diseases, in 2002-2004, were collected. The NTD rate was estimated for 10,000 births (live and stillborn) in this area. The 95% confidence intervals of rates were estimated assuming Poisson distribution of cases. Six cases of NTD were observed, with an NTD prevalence rate of 18.5 per 10,000 births (95% CI 17.0, 20.12). No evidence of known risk factors was reported. During summer 2002, the local service for environmental surveillance observed that the threshold level of drinking-water bacterial contamination had been exceeded, which probably resulted in an adjustment in the amount of chlorine added. The major difficulty in making hypotheses regarding the causes of birth defects is linking environmental risk factors exposure to fetal outcome. The prompt gathering of data may be essential. Thus, we emphasize the need for the activation of a population-based congenital malformation registry in order to achieve a deeper understanding of these events etiology. PMID:18569606

Prospero, Emilia; Barbadoro, Pamela; Filippetti, Fabio; Appignanesi, Remo; Ciavattini, Andrea; Carle, Flavia

2008-01-01

107

[The alpha-fetoprotein level analysis in open neural tube defects and chromosomal aberrations in the fetus].  

PubMed

During the last 12 years 4258 amniocenteses were performed between the 12th and 20th week of gestation (including 323 early amniocenteses carried out before 15th week). In every case, cytogenetical examination was performed and concentration of AFP was determined. In cases with elevated AFP level electrophoresis of AchE izoenzymes was performed. The results of the tests enabled us to calculate laboratory standard values of AFP in the amniotic fluid for 12th to 20th weeks of gestation. In 22 of 44 pregnancies with Down's syndrome the value of AFP concentration was below the 25th percentile of the laboratory normal value. In 5 of 10 pregnancies with Edward's syndrome AFP level exceeded significantly the 75th percentile of the laboratory norm. In two cases it was due to coexisting spina bifida and in one case due to omphalocele. In 28 amniotic fluid samples AFP concentration exceeded normal level and electrophoresis of AchE revealed additional band. In 26 cases increased values of AFP were due to open neural tube defect in the fetus: 13 cases of anencephaly and 13 cases of spina bifida; in the remaining two other cases omphalocele was found. PMID:8657351

Ilnicka, A; Paw?owska, B; Czyzewska, J; G?ogowska, I; Korlak, J; Rodo, M; Bieganowska, K; Szirkowiec, W; Zdzienicka, E; Zaremba, J

1996-01-01

108

Segmental costovertebral malformations: association with neural tube defects. Report of 3 cases and review of the literature.  

PubMed

Patients with spondylocostal dysostosis (SCD) have vertebral abnormalities and numerical or structural rib anomalies that produce thoracic asymmetry. Rib anomalies and dysmorphism are the typical features that differentiate this syndrome from spondylothoracic dysostosis (STD). Jarcho-Levin syndrome is a severe form with involvement of the whole vertebral column. Other associated findings such as congenital heart defects, abdominal wall malformations, genitourinary malformations and upper limb anomalies may be found; in addition, neural tube defects (NTDs) have been associated with this malformation. SCD is transmitted both in a recessive form and as a dominant defect. We report on 3 children with SCD; 2 also had NTDs. All of them were studied with X-rays and spinal magnetic resonance (MR), and over the same period they underwent multidisciplinary clinical functional evaluation. One of our cases with NTD also presented polythelia, which has not previously been described in patients with SCD. The common association of segmental costovertebral malformations with NTDs could be related to an early gastrulation genomic defect, or one after gastrulation, when there are two independent somitic columns. The latter sometimes progresses and then involves primary and secondary neurulation. Also, the association of SCD with NTDs could be related to the interaction of different genes, resulting in this complex phenotype. Therefore, additional genetical and embryological studies are necessary to provide evidence of an etiological link between SCD and NTD. PMID:10461076

Duru, S; Ceylan, S; Güvenç, B H

1999-05-01

109

Metabonomic study on women of reproductive age treated with nutritional intervention: screening potential biomarkers related to neural tube defects occurrence.  

PubMed

Nutritional intervention is effective in reducing the risk of neural tube defects (NTDs). To determine the effects of nutritional supplementation on human metabolism, a metabonomic study was carried out on 96 women of reproductive age. Subjects with nutritional intervention were given fortified wheat flour (containing folic acid, vitamin B?, vitamin B?, ferric sodium edetate and zinc oxide) for 8 months. Serum metabolic fingerprinting was detected via ultraperformance liquid chromatography in tandem with time-of-flight mass spectrometry (UPLC-TOF MS), and data acquired was processed by multivariate statistical analysis. The result revealed a significant difference between the control and intervention group. Twenty potential biomarkers, including fructose 6-phosphate, sphingosine 1-phosphate, docosahexaenoic acid and hexadecanoic acid, were located and identified by the accurate mass measurement of TOF MS. These compounds are believed to be functionally related to anti-oxidative competence in vivo. In conclusion, metabonomics study is a valuable approach in exploring the effect mechanism of nutritional intervention on NTD prevention. PMID:20812204

Jiang, Zhiting; Liang, Qionglin; Wang, Yong; Zheng, Xiaoying; Pei, Lijun; Zhang, Ting; Wang, Yiming; Luo, Guoan

2011-07-01

110

Reduced folate carrier A80G polymorphism and susceptibility to neural tube defects: a meta-analysis.  

PubMed

The reduced folate carrier (RFC1) plays a crucial role in mediating folate delivery into a variety of cells. RFC1 polymorphism (A80G) has been reported to be associated with increased risk of neural tube defects (NTDs). However, results derived from individually underpowered studies are conflicting. We performed a systematic search of MEDLINE and EMBASE databases and carried out a meta-analysis on the association between RFC1 polymorphism (A80G) and NTDs risk. Overall, a significant correlation between RFC1 A80G polymorphism and NTDs risk was found neither in infants nor in maternal (allele contrast in infants: OR(RE)=1.15, 95% CI: 0.92-1.45; allele contrast in mothers: OR(RE)=1.24, 95% CI: 0.98-1.56). The present meta-analysis failed to support a positive association between RFC1 A80G polymorphism and susceptibility to NTDs. It is important to realize, however, that socio-economic factors, and gene-environment and gene-gene interactions, could have influenced the outcome of our meta-analysis. For this reason, a relationship between the A80G polymorphism and NTD risk cannot be entirely discounted. PMID:22975209

Wang, Hai-Gang; Wang, Jia-Li; Zhang, Jian; Zhao, Li-Xia; Zhai, Guang-Xi; Xiang, Yu-Zhu; Chang, Ping

2012-12-01

111

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

112

Nausea and vomiting in early pregnancy and the risk of neural tube defects: a case-control study.  

PubMed

There has been considerable professional debate on the association between nausea and vomiting in early pregnancy (NVP) and neural tube defects (NTDs) risk. This study explored the association between NVP and NTDs risk, and the effect of folic acid supplements on the association. A 1:1 matched case-control study was conducted and conditional logistic regression model was used to analyze the associations. The result showed the odds ratio (OR) of severe NVP for NTDs was 2.403 (95%CI 1.437,4.017; P<0.001) and that of moderate NVP was 1.469 (95%CI 1.063,2.031; P = 0.020) compared with light NVP when adjusted by the potential confounders. Stratified by intake of folic acid supplements, the ORs for severe and moderate NVP turned to 2.147 (95%CI 1.140, 4.043; P = 0.018) and 2.055 (95%CI 1.320, 3.199; P = 0.001) in the stratum of non-intake of folic acid supplements while ORs reduced to 1.851 (95%CI 0.729, 4.699; P = 0.195) and 1.003 (95%CI 0.594, 1.694; P = 0.992) in the stratum of intake of folic acid supplements, respectively. We conclude that severe/moderate NVP has an association with the risk of NTDs, which was not found in the group with intake of folic acid supplements. Folic acid supplements should be recommended to use for the prevention of NTDs. PMID:25567703

Lu, Qing-Bin; Wang, Zhi-Ping; Gao, Li-Jie; Gong, Rui; Sun, Xi-Hong; Wang, Meng; Zhao, Zhong-Tang

2015-01-01

113

"Polymorphisms in folate metabolism genes as maternal risk factor for neural tube defects: an updated meta-analysis".  

PubMed

Epidemiological studies have evaluated the association between maternal methylenetetrahydrofolate reductase (MTHFR) C677T, A1298C and methionine synthase reductase (MTRR) A66G polymorphisms and risk of neural tube defects (NTDs) in offspring. However, the results from the published studies on the association between these three polymorphisms and NTD risk are conflicting. To derive a clearer picture of association between these three maternal polymorphisms and risk of NTD, we performed meta-analysis. A comprehensive search was conducted to identify all case-control studies of maternal MTHFR and MTRR polymorphisms and NTD risk. We used odds ratios (ORs) with 95 % confidence intervals (CIs) to assess the strength of the association. Overall, we found that maternal MTHFR C677T polymorphism (ORTvsC =1.20; 95 % CI?=?1.13-1.28) and MTRR A66G polymorphism (ORGvsA?=?1.21; 95 % CI?=?0.98-1.49) were risk factors for producing offspring with NTD but maternal MTHFR A1298C polymorphism (ORCvsA?=?0.91; 95 % CI?=?0.78-1.07) was not associated with NTD risk. However, in stratified analysis by geographical regions, we found that the maternal C677T polymorphism was significantly associated with the risk of NTD in Asian (ORTvsC?=?1.43; 95 % CI: 1.05-1.94), European (ORTvsC?=?1.13; 95 % CI: 1.04-1.24) and American (ORTvsC?=?1.26; 95 % CI: 1.13-1.41) populations. In conclusion, present meta-analysis supports that the maternal MTHFR C677T and MTRR A66G are polymorphisms contributory to risk for NTD. PMID:25005003

Yadav, Upendra; Kumar, Pradeep; Yadav, Sushil Kumar; Mishra, Om Prakash; Rai, Vandana

2015-02-01

114

Nausea and Vomiting in Early Pregnancy and the Risk of Neural Tube Defects: a Case-Control Study  

PubMed Central

There has been considerable professional debate on the association between nausea and vomiting in early pregnancy (NVP) and neural tube defects (NTDs) risk. This study explored the association between NVP and NTDs risk, and the effect of folic acid supplements on the association. A 1:1 matched case-control study was conducted and conditional logistic regression model was used to analyze the associations. The result showed the odds ratio (OR) of severe NVP for NTDs was 2.403 (95%CI 1.437,4.017; P<0.001) and that of moderate NVP was 1.469 (95%CI 1.063,2.031; P = 0.020) compared with light NVP when adjusted by the potential confounders. Stratified by intake of folic acid supplements, the ORs for severe and moderate NVP turned to 2.147 (95%CI 1.140, 4.043; P = 0.018) and 2.055 (95%CI 1.320, 3.199; P = 0.001) in the stratum of non-intake of folic acid supplements while ORs reduced to 1.851 (95%CI 0.729, 4.699; P = 0.195) and 1.003 (95%CI 0.594, 1.694; P = 0.992) in the stratum of intake of folic acid supplements, respectively. We conclude that severe/moderate NVP has an association with the risk of NTDs, which was not found in the group with intake of folic acid supplements. Folic acid supplements should be recommended to use for the prevention of NTDs. PMID:25567703

Lu, Qing-Bin; Wang, Zhi-Ping; Gao, Li-Jie; Gong, Rui; Sun, Xi-Hong; Wang, Meng; Zhao, Zhong-Tang

2015-01-01

115

A second common mutation in the methylenetetrahydrofolate reductase gene: an additional risk factor for neural-tube defects?  

PubMed Central

Recently, we showed that homozygosity for the common 677(C-->T) mutation in the methylenetetrahydrofolate reductase (MTHFR) gene, causing thermolability of the enzyme, is a risk factor for neural-tube defects (NTDs). We now report on another mutation in the same gene, the 1298(A-->C) mutation, which changes a glutamate into an alanine residue. This mutation destroys an MboII recognition site and has an allele frequency of .33. This 1298(A-->C) mutation results in decreased MTHFR activity (one-way analysis of variance [ANOVA] P < .0001), which is more pronounced in the homozygous than heterozygous state. Neither the homozygous nor the heterozygous state is associated with higher plasma homocysteine (Hcy) or a lower plasma folate concentration-phenomena that are evident with homozygosity for the 677(C-->T) mutation. However, there appears to be an interaction between these two common mutations. When compared with heterozygosity for either the 677(C-->T) or 1298(A-->C) mutations, the combined heterozygosity for the 1298(A-->C) and 677(C-->T) mutations was associated with reduced MTHFR specific activity (ANOVA P < .0001), higher Hcy, and decreased plasma folate levels (ANOVA P <.03). Thus, combined heterozygosity for both MTHFR mutations results in similar features as observed in homozygotes for the 677(C-->T) mutation. This combined heterozygosity was observed in 28% (n =86) of the NTD patients compared with 20% (n =403) among controls, resulting in an odds ratio of 2.04 (95% confidence interval: .9-4.7). These data suggest that the combined heterozygosity for the two MTHFR common mutations accounts for a proportion of folate-related NTDs, which is not explained by homozygosity for the 677(C-->T) mutation, and can be an additional genetic risk factor for NTDs. PMID:9545395

van der Put, N M; Gabreëls, F; Stevens, E M; Smeitink, J A; Trijbels, F J; Eskes, T K; van den Heuvel, L P; Blom, H J

1998-01-01

116

Neural networks and separation of background and foregrounds in astrophysical sky maps  

E-print Network

The Independent Component Analysis (ICA) algorithm is implemented as a neuralnetwork for separating signals of different origin in astrophysical sky maps.Due to its self-organizing capability, it works without prior assumptions onthe signals, neither on their frequency scaling, nor on the signal mapsthemselves; instead, it learns directly from the input data how to separate thephysical components, making use of their statistical independence. To test thecapabilities of this approach, we apply the ICA algorithm on sky patches, takenfrom simulations and observations, at the microwave frequencies, that are goingto be deeply explored in a few years on the whole sky, by the MicrowaveAnisotropy Probe (MAP) and by the {\\sc Planck} Surveyor Satellite. The maps areat the frequencies of the Low Frequency Instrument (LFI) aboard the {\\scPlanck} satellite (30, 44, 70 and 100 GHz), and contain simulated astrophysicalradio sources, Cosmic Microwave Background (CMB) radiation, and Galacticdiffuse emissions from thermal dust...

Baccigalupi, C; Burigana, C; De Zotti, G; Farusi, A; Maino, D; Maris, M; Perrotta, F; Salerno, E; Toffolatti, L; Tonazzini, A

2000-01-01

117

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

118

Genome-Wide Association Mapping in Dogs Enables Identification of the Homeobox Gene, NKX2-8, as a Genetic Component of Neural Tube Defects in Humans  

PubMed Central

Neural tube defects (NTDs) is a general term for central nervous system malformations secondary to a failure of closure or development of the neural tube. The resulting pathologies may involve the brain, spinal cord and/or vertebral column, in addition to associated structures such as soft tissue or skin. The condition is reported among the more common birth defects in humans, leading to significant infant morbidity and mortality. The etiology remains poorly understood but genetic, nutritional, environmental factors, or a combination of these, are known to play a role in the development of NTDs. The variable conditions associated with NTDs occur naturally in dogs, and have been previously reported in the Weimaraner breed. Taking advantage of the strong linkage-disequilibrium within dog breeds we performed genome-wide association analysis and mapped a genomic region for spinal dysraphism, a presumed NTD, using 4 affected and 96 unaffected Weimaraners. The associated region on canine chromosome 8 (pgenome?=?3.0×10?5), after 100,000 permutations, encodes 18 genes, including NKX2-8, a homeobox gene which is expressed in the developing neural tube. Sequencing NKX2-8 in affected Weimaraners revealed a G to AA frameshift mutation within exon 2 of the gene, resulting in a premature stop codon that is predicted to produce a truncated protein. The exons of NKX2-8 were sequenced in human patients with spina bifida and rare variants (rs61755040 and rs10135525) were found to be significantly over-represented (p?=?0.036). This is the first documentation of a potential role for NKX2-8 in the etiology of NTDs, made possible by investigating the molecular basis of naturally occurring mutations in dogs. PMID:23874236

Safra, Noa; Bassuk, Alexander G.; Ferguson, Polly J.; Aguilar, Miriam; Coulson, Rochelle L.; Thomas, Nicholas; Hitchens, Peta L.; Dickinson, Peter J.; Vernau, Karen M.; Wolf, Zena T.; Bannasch, Danika L.

2013-01-01

119

Prevalence of neural tube defects in 20 regions of Europe and the impact of prenatal diagnosis, 1980-1986. EUROCAT Working Group.  

PubMed Central

STUDY OBJECTIVE--The aims were (1) to determine whether in Europe, 1980-86, geographical differences in total prevalence of neural tube defects persist; (2) to examine the stability of total prevalence rates over time; (3) to evaluate the impact of prenatal diagnosis in terms of frequency and timing of termination of pregnancy. DESIGN--Prevalence rates of neural tube defects were determined from case registration data in 20 EUROCAT regional registers of congenital anomalies, 1980-86. The chi 2 test for homogeneity in proportions was used to test whether differences in total prevalence rates were significant between regions or over time. SETTING--Geographically defined populations were used in the Republic of Ireland, United Kingdom, Belgium, The Netherlands, Luxemburg, Denmark, France, Italy, Yugoslavia, and Malta. PATIENTS--The patients were 3113 cases of anencephaly, spina bifida, encephalocele, and iniencephaly. Total cases (livebirths, stillbirths and induced abortions following prenatal diagnosis) were registered in 14 regions. Induced abortions were excluded from registration in six regions. MEASUREMENTS AND MAIN RESULTS--Total prevalence rates (including livebirths, stillbirths and induced abortions) were 24 to 38 per 10,000 in six areas of Ireland and United Kingdom. Average total prevalence rate in eight continental European areas was 11.5 per 10,000. There was a secular decline in total prevalence in Dublin (Republic of Ireland) and Northern Ireland (United Kingdom) and a fluctuation in Glasgow, Liverpool, and South Glamorgan (United Kingdom). Total prevalence in continental Europe was stable over time. There was no significant geographical or secular variation in the spina bifida to anencephaly ratio (1.3). The ratio of encephalocele to other neural tube defects was lower in the British Isles (0.09) than in continental Europe (0.18). The impact of prenatal diagnosis and termination of pregnancy is increasing over time. Terminations were performed 1984-86 in at least 80% of total cases of anencephaly in 6/11 centres registering induced abortions, and in at least 40% of total cases of spina bifida in four centres. Serum alpha fetoprotein screening in British centres was associated with earlier prenatal diagnosis of spina bifida than ultrasound screening in other centres. CONCLUSIONS--Geographical and secular variation in total prevalence of neural tube defects persists in Europe 1980-86, independent of the practice of prenatal diagnosis. There is considerable regional variation in the impact of prenatal diagnosis in terms of frequency and timing of diagnosis and pregnancy termination linked to different policies and practices of prenatal screening. PMID:2045746

1991-01-01

120

Neural Tube Defects  

MedlinePLUS

... baby's risk for NTDS. Folic acid is a B vitamin that every cell in your body needs for ... help prevent NTDs in your baby? Taking the B-vitamin folic acid can help prevent NTDs. It’s important ...

121

Female predisposition to cranial neural tube defects is not because of a difference between the sexes in the rate of embryonic growth or development during neurulation.  

PubMed Central

The susceptibility of females to anencephaly is well established and has been suggested to result from a slower rate of growth and development of female embryos during cranial neurulation. We have tested this hypothesis by measuring the rates of growth and development, both in utero and in vitro, of male and female embryos of the curly tail (ct) mutant mouse strain, in which cranial neural tube defects occur primarily in females. Embryonic growth was assessed by increase in protein content, while development progression was judged from increase in somite number and morphological score. Embryos were sexed by use of the polymerase chain reaction to amplify a DNA sequence specific to the Y chromosome, and by sex chromatin analysis. We find that, during neurulation (between 8.5 and 10.5 days of gestation), males are advanced in growth and development relative to their female litter mates, but that the rates of growth and development do not differ between the sexes during this period. We conclude that rate of embryonic growth and development is unlikely to determine susceptibility to cranial neural tube defects. It seems more likely that male and female embryos differ in some specific aspect(s) of the neurulation process that increases the susceptibility of females to development of anencephaly. Images PMID:8064816

Brook, F A; Estibeiro, J P; Copp, A J

1994-01-01

122

Single-Tube Multiplexed Molecular Detection of Endemic Porcine Viruses in Combination with Background Screening for Transboundary Diseases  

PubMed Central

Detection of several pathogens with multiplexed real-time quantitative PCR (qPCR) assays in a one-step setup allows the simultaneous detection of two endemic porcine and four different selected transboundary viruses. Reverse transcription (RT)-qPCR systems for the detection of porcine reproductive and respiratory syndrome virus (PRRSV) and porcine circovirus type 2 (PCV2), two of the most economically important pathogens of swine worldwide, were combined with a screening system for diseases notifiable to the World Organization of Animal Health, namely, classical and African swine fever, foot-and-mouth disease, and Aujeszky's disease. Background screening was implemented using the identical fluorophore for all four different RT-qPCR assays. The novel multiplex RT-qPCR system was validated with a large panel of different body fluids and tissues from pigs and other animal species. Both reference samples and clinical specimens were used for a complete evaluation. It could be demonstrated that a highly sensitive and specific parallel detection of the different viruses was possible. The assays for the notifiable diseases were even not affected by the simultaneous amplification of very high loads of PRRSV- and PCV2-specific sequences. The novel broad-spectrum multiplex assay allows in a unique form the routine investigation for endemic porcine pathogens with exclusion diagnostics of the most important transboundary diseases in samples from pigs with unspecific clinical signs, such as fever or hemorrhages. The new system could significantly improve early detection of the most important notifiable diseases of swine and could lead to a new approach in syndromic surveillance. PMID:23303496

Wernike, Kerstin; Hoffmann, Bernd

2013-01-01

123

Differences in the neural mechanisms of selective attention in children from different socioeconomic backgrounds: An event-related brain potential study  

PubMed Central

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 which attention deficits arise. The present study examined this question using an event-related brain potential (ERP) measure of selective auditory attention. Thirty-two children aged 3- to 8-years participated in the study. Children were cued to attend selectively to one of two simultaneously presented narrative stories. The stories differed in location (left/right speaker), narration voice (male/female), and content. ERPs were recorded to linguistic and non-linguistic probe stimuli embedded in the attended and unattended stories. Children whose mothers had lower levels of educational attainment (no college experience) showed reduced effects of selective attention on neural processing relative to children whose mothers had higher levels of educational attainment (at least some college). These differences occurred by 100 msec after probe onset. Furthermore, the differences were related specifically to a reduced ability to filter irrelevant information (i.e., to suppress the response to sounds in the unattended channel) among children whose mothers had lower levels of education. These data provide direct evidence for differences in the earliest stages of processing within neural systems mediating selective attention in children from different socioeconomic backgrounds. Results are discussed in the context of intervention programs aimed at improving attention and self-regulation abilities in children at-risk for school failure. PMID:19635089

Stevens, Courtney; Lauinger, Brittni; Neville, Helen

2009-01-01

124

IRDL Cloning: A One-Tube, Zero-Background, Easy-to-Use, Directional Cloning Method Improves Throughput in Recombinant DNA Preparation  

PubMed Central

Rapid and efficient construction of expression vectors and subsequent transformation are basic recombinant methods for the investigation of gene functionality. Although novel cloning methods have recently been developed, many laboratories worldwide continue to use traditional restriction digestion-ligation methods to construct expression vectors owing to financial constraints and the unavailability of appropriate vectors. We describe an improved restriction digestion-ligation (IRDL) cloning method that combines the advantage of directional cloning from double digestion-ligation with that of a low background observed by using a positive selection marker gene ccdB to facilitate digestion and ligation in a single tube. The IRDL cloning overcomes the time-consuming and laborious limits of traditional methods, thereby providing an easy-to-use, low-cost, and one-step strategy for directional cloning of target DNA fragments into an expression vector. As a proof-of-concept example, we developed two yeast vectors to demonstrate the feasibility and the flexibility of the IRDL cloning method. This method would provide an effective and easy-to-use system for gene cloning and functional genomics studies. PMID:25243603

Wang, Jiancai; Xu, Ronghua; Liu, Aizhong

2014-01-01

125

[Quantitative acetylcholinesterase (AChE)--determination in amniotic fluid--potential for differential diagnosis in consistently high AFP levels during general AFP screening for prenatal diagnosis of open neural tube defects].  

PubMed

Measurement of maternal serum alpha-fetoprotein concentration for prenatal detection of open neural tube defects had been introduced into the obstetrical care of pregnant women in the district of Schwerin since 1983. In cases of high risk for presence of an open neural tube defect, noticed by elevated levels of maternal serum alpha-fetoprotein concentration step by step further diagnostic steps are necessary. In addition to special examination by ultrasound and measurement of alpha-fetoprotein concentration in amniotic fluid quantitative analysis of acetylcholinesterase activity in amniotic fluid seems to be valuable. Reliability of detecting open neural tube defects in prenatal care had been proved by quantitative analysis of acetylcholinesterase activity in amniotic fluid. The existing results up to now were very reliable, especially biological transit stages from normal to pathological findings were taken into consideration, too. In these cases further controls are necessary. Levels of acethylcholinesterase activity below the 90th percentile can be considered as normal findings, levels above the 99th percentile must be interpreted as pathological findings. These are our experiences up to date. PMID:2480036

Zwahr, C; Grosch, A; Horn, A; Schulze, M

1989-01-01

126

Effects of Korean red ginseng extracts on neural tube defects and impairment of social interaction induced by prenatal exposure to valproic acid.  

PubMed

Ginseng is one of the most widely used medicinal plants, which belongs to the genus Panax. Compared to uncured white ginseng, red ginseng has been generally regarded to produce superior pharmacological effects with lesser side/adverse effects, which made it popular in a variety of formulation from tea to oriental medicine. Using the prenatal valproic acid (VPA)-injection model of autism spectrum disorder (ASD) in rats, which produces social impairrment and altered seizure susceptibility as in human ASD patients as well as mild neural tube defects like crooked tail phenotype, we examined whether chronic administration of red ginseng extract may rescue the social impairment and crooked tail phenotype in prenatally VPA-exposed rat offspring. VPA-induced impairment in social interactions tested using sociability and social preference paradigms as well as crooked tail phenotypes were significantly improved by administration of Korean red ginseng (KRG) in a dose dependent manner. Rat offspring prenatally exposed to VPA showed higher sensitivity to electric shock seizure and increased locomotor activity in open-field test. KRG treatment reversed abnormal locomotor activity and sensitivity to electric shock to control level. These results suggest that KRG may modulate neurobehavioral and structural organization of nervous system adversely affected by prenatal exposure to VPA. PMID:23104247

Kim, Pitna; Park, Jin Hee; Kwon, Kyoung Ja; Kim, Ki Chan; Kim, Hee Jin; Lee, Jong Min; Kim, Hahn Young; Han, Seol-Heui; Shin, Chan Young

2013-01-01

127

Defective neural tube closure and anteroposterior patterning in mice lacking the LIM protein LMO4 or its interacting partner Deaf-1.  

PubMed

LMO4 belongs to a family of transcriptional regulators that comprises two zinc-binding LIM domains. LIM-only (LMO) proteins appear to function as docking sites for other factors, leading to the assembly of multiprotein complexes. The transcription factor Deaf-1/NUDR has been identified as one partner protein of LMO4. We have disrupted the Lmo4 and Deaf-1 genes in mice to define their biological function in vivo. All Lmo4 mutants died shortly after birth and showed defects within the presphenoid bone, with 50% of mice also exhibiting exencephaly. Homeotic transformations were observed in Lmo4-null embryos and newborn mice, but with incomplete penetrance. These included skeletal defects in cervical vertebrae and the rib cage. Furthermore, fusions of cranial nerves IX and X and defects in cranial nerve V were apparent in some Lmo4(-/-) and Lmo4(+/-) mice. Remarkably, Deaf-1 mutants displayed phenotypic abnormalities similar to those observed in Lmo4 mutants. These included exencephaly, transformation of cervical segments, and rib cage abnormalities. In contrast to Lmo4 nullizygous mice, nonexencephalic Deaf-1 mutants remained healthy. No defects in the sphenoid bone or cranial nerves were apparent. Thus, Lmo4 and Deaf-1 mutant mice exhibit overlapping as well as distinct phenotypes. Our data indicate an important role for these two transcriptional regulators in pathways affecting neural tube closure and skeletal patterning, most likely reflecting their presence in a functional complex in vivo. PMID:14966286

Hahm, Kyungmin; Sum, Eleanor Y M; Fujiwara, Yuko; Lindeman, Geoffrey J; Visvader, Jane E; Orkin, Stuart H

2004-03-01

128

Defective Neural Tube Closure and Anteroposterior Patterning in Mice Lacking the LIM Protein LMO4 or Its Interacting Partner Deaf-1  

PubMed Central

LMO4 belongs to a family of transcriptional regulators that comprises two zinc-binding LIM domains. LIM-only (LMO) proteins appear to function as docking sites for other factors, leading to the assembly of multiprotein complexes. The transcription factor Deaf-1/NUDR has been identified as one partner protein of LMO4. We have disrupted the Lmo4 and Deaf-1 genes in mice to define their biological function in vivo. All Lmo4 mutants died shortly after birth and showed defects within the presphenoid bone, with 50% of mice also exhibiting exencephaly. Homeotic transformations were observed in Lmo4-null embryos and newborn mice, but with incomplete penetrance. These included skeletal defects in cervical vertebrae and the rib cage. Furthermore, fusions of cranial nerves IX and X and defects in cranial nerve V were apparent in some Lmo4?/? and Lmo4+/? mice. Remarkably, Deaf-1 mutants displayed phenotypic abnormalities similar to those observed in Lmo4 mutants. These included exencephaly, transformation of cervical segments, and rib cage abnormalities. In contrast to Lmo4 nullizygous mice, nonexencephalic Deaf-1 mutants remained healthy. No defects in the sphenoid bone or cranial nerves were apparent. Thus, Lmo4 and Deaf-1 mutant mice exhibit overlapping as well as distinct phenotypes. Our data indicate an important role for these two transcriptional regulators in pathways affecting neural tube closure and skeletal patterning, most likely reflecting their presence in a functional complex in vivo. PMID:14966286

Hahm, Kyungmin; Sum, Eleanor Y. M.; Fujiwara, Yuko; Lindeman, Geoffrey J.; Visvader, Jane E.; Orkin, Stuart H.

2004-01-01

129

Epigenetic alterations in folate transport genes in placental tissue from fetuses with neural tube defects and in leukocytes from subjects with hyperhomocysteinemia.  

PubMed

The objectives of this study were to identify tissue-specific differentially methylated regions (T-DMR's) in the folate transport genes in placental tissue compared with leukocytes, and from placental tissues obtained from normal infants or with neural tube defects (NTDs). Using pyrosequencing, we developed methylation assays for the CpG islands (CGIs) and the CGI shore regions of the folate receptor ? (FOLR1), proton-coupled folate transporter (PCFT) and reduced folate carrier 1 (RFC1) genes. The T-DMRs differed in location for each gene and the difference in methylation ranged between 2 and 54%. A higher T-DMR methylated fraction was associated with a lower mRNA level of the FOLR1 and RFC1 genes. Methylation fractions differed according to RFC1 80G > A genotype in the NTD cases and in leukocytes from subjects with high total plasma homocysteine (tHcy). There were no differences in methylated fraction of folate transporter genes between NTD cases and controls. We suggest that T-DMRs participate in the regulation of expression of the FOLR1 and RFC1 genes, that the RFC1 80G > A polymorphism exerts a gene-nutrition interaction on DNA methylation in the RFC1 gene, and that this interaction appears to be most prominent in NTD-affected births and in subjects with high tHcy concentrations. PMID:23417011

Farkas, Sanja A; Böttiger, Anna K; Isaksson, Helena S; Finnell, Richard H; Ren, Aiguo; Nilsson, Torbjörn K

2013-03-01

130

Sirtuin inhibitor Ex-527 causes neural tube defects, ventral edema formations, and gastrointestinal malformations in Xenopus laevis embryos.  

PubMed

Chemical reagent Ex-527 is widely used as a major inhibitor of Sirtuin enzymes, which are a family of highly conserved protein deacetylases and have been linked with caloric restriction and aging by modulating energy metabolism, genomic stability, and stress resistance. However, the extent to which Ex-527 controls early developmental events of vertebrate embryos remains to be understood. Here, we report an examination of Ex-527 effects during Xenopus early development, followed by a confirmation of expressions of xSirt1 and xSirt2 in embryonic stages and enhancement of acetylation by Ex-527. First, we found that reductions in size of neural plate at neurula stages were induced by Ex-527 treatment. Second, tadpoles with short body length and large edematous swellings in the ventral side were frequently observed. Moreover, Ex-527-treated embryos showed severe gastrointestinal malformations in late tadpole stages. Taken together with these results, we conclude that the Sirtuin family start functioning at early embryonic stages and is required for various developmental events. PMID:25131500

Ohata, Yoshihisa; Matsukawa, Shinya; Moriyama, Yuki; Michiue, Tatsuo; Morimoto, Kenta; Sato, Yuka; Kuroda, Hiroki

2014-08-01

131

Genetic background impacts developmental potential of enteric neural crest-derived progenitors in the Sox10Dom model of Hirschsprung disease  

PubMed Central

Abnormalities in the development of enteric neural crest-derived progenitors (ENPs) that generate the enteric nervous system (ENS) can lead to aganglionosis in a variable portion of the distal gastrointestinal tract. Cumulative evidence suggests that variation of aganglionosis is due to gene interactions that modulate the ability of ENPs to populate the intestine; however, the developmental processes underlying this effect are unknown. We hypothesized that differences in enteric ganglion deficits could be attributable to the effects of genetic background on early developmental processes, including migration, proliferation, or lineage divergence. Developmental processes were investigated in congenic Sox10Dom mice, an established Hirschsprung disease (HSCR) model, on distinct inbred backgrounds, C57BL/6J (B6) and C3HeB/FeJ (C3Fe). Immuno-staining on whole-mount fetal gut tissue and dissociated cell suspensions was used to assess migration and proliferation. Flow cytometry utilizing the cell surface markers p75 and HNK-1 was used to isolate live ENPs for analysis of developmental potential. Frequency of ENPs was reduced in Sox10Dom embryos relative to wild-type embryos, but was unaffected by genetic background. Both migration and developmental potential of ENPs in Sox10Dom embryos were altered by inbred strain background with the most highly significant differences seen for developmental potential between strains and genotypes. In vivo imaging of fetal ENPs and postnatal ganglia demonstrates that altered lineage divergence impacts ganglia in the proximal intestine. Our analysis demonstrates that genetic background alters early ENS development and suggests that abnormalities in lineage diversification can shift the proportions of ENP populations and thus may contribute to ENS deficiencies in vivo. PMID:20739296

Walters, Lauren C.; Cantrell, V. Ashley; Weller, Kevin P.; Mosher, Jack T.; Southard-Smith, E. Michelle

2010-01-01

132

Supplement use and other characteristics among pregnant women with a previous pregnancy affected by a neural tube defect - United States, 1997-2009.  

PubMed

Neural tube defects (NTDs) include anomalies of the brain (anencephaly and encephalocele) and spine (spina bifida). Even with ongoing mandatory folic acid fortification of enriched cereal grain products, the U.S. Preventive Services Task Force recommends that women of childbearing potential consume a daily supplement containing 400 µg-800 µg of folic acid. Women with a prior NTD-affected pregnancy have an increased risk for having another NTD-affected pregnancy, and if they are planning another pregnancy, the recommendation is that they consume high-dosage folic acid supplements (4.0 mg/day) beginning ?4 weeks before conception and continuing through the first 12 weeks of pregnancy. To learn whether folic acid supplementation (from multivitamins or single- ingredient supplements) was commonly used during pregnancy by women with a previous NTD-affected pregnancy, supplement use was assessed among a convenience sample of women with a previous NTD-affected pregnancy who participated in the National Birth Defects Prevention Study (NBDPS), a case-control study of major birth defects in the United States. Characteristics of women who previously had an NTD-affected pregnancy and whose index pregnancy (pregnancy included in NBDPS) was either affected by an NTD (N = 17) (i.e., recurrence-cases) or resulted in a live-born infant without a major birth defect (N = 10) (i.e., recurrence-controls) were assessed. Taking a supplement that included folic acid was more common among recurrence-control mothers (80%) than recurrence-case mothers (35%). The recommendation that women should take folic acid supplements just before and during early pregnancy is not being followed by many women and offers an opportunity for NTD prevention, especially among women who are at a higher risk because they have had a previous pregnancy affected by an NTD. PMID:25590679

Arth, Annelise; Tinker, Sarah; Moore, Cynthia; Canfield, Mark; Agopian, Aj; Reefhuis, Jennita

2015-01-16

133

Tube support  

DOEpatents

A tube support for supporting horizontal tubes from an inclined vertical support tube passing between the horizontal tubes. A support button is welded to the vertical support tube. Two clamping bars or plates, the lower edges of one bearing on the support button, are removably bolted to the inclined vertical tube. The clamping bars provide upper and lower surface support for the horizontal tubes.

Mullinax, Jerry L. (Green Township, Summit County, OH)

1988-01-01

134

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

135

Neural induction and factors that stabilize a neural fate  

PubMed Central

The neural ectoderm of vertebrates forms when the BMP signaling pathway is suppressed. Herein we review the molecules that directly antagonize extracellular BMP and the signaling pathways that further contribute to reduce BMP activity in the neural ectoderm. Downstream of neural induction, a large number of “neural fate stabilizing” (NFS) transcription factors are expressed in the presumptive neural ectoderm, developing neural tube, and ultimately in neural stem cells. Herein we review what is known about their activities during normal development to maintain a neural fate and regulate neural differentiation. Further elucidation of how the NFS genes interact to regulate neural specification and differentiation should ultimately prove useful for regulating the expansion and differentiation of neural stem and progenitor cells. PMID:19750523

Rogers, Crystal; Moody, Sally A.; Casey, Elena

2009-01-01

136

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 ...

137

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

138

Tracheostomy tubes.  

PubMed

Tracheostomy tubes are used to administer positive-pressure ventilation, to provide a patent airway, 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 dimensions between tubes with the same inner diameter from different manufacturers are not commonly appreciated but may have important clinical implications. Tracheostomy tubes can be cuffed or uncuffed and may be fenestrated. Some tracheostomy tubes are designed with an inner cannula. It is important for clinicians caring for patients with a tracheostomy tube to appreciate the nuances of various tracheostomy tube designs and to select a tube that appropriately fits the patient. The optimal frequency of changing a chronic tracheostomy tube is controversial. Specialized teams may be useful in managing patients with a tracheostomy. Speech can be facilitated with a speaking valve in patients with a tracheostomy tube who are breathing spontaneously. In mechanically ventilated patients with a tracheostomy, a talking tracheostomy tube, a deflated cuff technique with a speaking valve, or a deflated cuff technique without a speaking valve can be used to facilitate speech. PMID:24891201

Hess, Dean R; Altobelli, Neila P

2014-06-01

139

ORIGINAL ARTICLE Yield prediction for seamless tubing processes  

E-print Network

Abstract Seamless tubing is the most commonly used process for high quality pipe products due to itsORIGINAL ARTICLE Yield prediction for seamless tubing processes: a computational intelligence in a seamless tubing factory, using neural networks to model relationships between controlled and uncontrolled

Huang, Samuel H.

140

Null Mutation of the Lmo4 Gene or a Combined Null Mutation of the Lmo1/Lmo3 Genes Causes Perinatal Lethality, and Lmo4 Controls Neural Tube Development in Mice  

PubMed Central

The LIM-only family of proteins comprises four members; two of these (LMO1 and LMO2) are involved in human T-cell leukemia via chromosomal translocations, and LMO2 is a master regulator of hematopoiesis. We have carried out gene targeting of the other members of the LIM-only family, viz., genes Lmo1, Lmo3 and Lmo4, to investigate their role in mouse development. None of these genes has an obligatory role in lymphopoiesis. In addition, while null mutations of Lmo1 or Lmo3 have no discernible phenotype, null mutation of Lmo4 alone causes perinatal lethality due to a severe neural tube defect which occurs in the form of anencephaly or exencephaly. Since the Lmo1 and Lmo3 gene sequences are highly related and have partly overlapping expression domains, we assessed the effect of compound Lmo1/Lmo3 null mutations. Although no anatomical defects were apparent in compound null pups, these animals also die within 24 h of birth, suggesting that a compensation between the related Lmo1 and 3 proteins can occur during embryogenesis to negate the individual loss of these genes. Our results complete the gene targeting of the LIM-only family in mice and suggest that all four members of this family are important in regulators of distinct developmental pathways. PMID:14966285

Tse, E.; Smith, A. J. H.; Hunt, S.; Lavenir, I.; Forster, A.; Warren, A. J.; Grutz, G.; Foroni, L.; Carlton, M. B. L.; Colledge, W. H.; Boehm, T.; Rabbitts, T. H.

2004-01-01

141

Developmental time rather than local environment regulates the schedule of epithelial polarization in the zebrafish neural rod  

PubMed Central

Background Morphogenesis requires developmental processes to occur both at the right time and in the right place. During neural tube formation in the zebrafish embryo, the generation of the apical specializations of the lumen must occur in the center of the neural rod after the neural cells have undergone convergence, invagination and interdigitation across the midline. How this coordination is achieved is uncertain. One possibility is that environmental signaling at the midline of the neural rod controls the schedule of apical polarization. Alternatively, polarization could be regulated by a timing mechanism and then independent morphogenetic processes ensure the cells are in the correct spatial location. Results Ectopic transplantation demonstrates the local environment of the neural midline is not required for neural cell polarization. Neural cells can self-organize into epithelial cysts in ectopic locations in the embryo and also in three-dimensional gel cultures. Heterochronic transplants demonstrate that the schedule of polarization and the specialized cell divisions characteristic of the neural rod are more strongly regulated by time than local environmental signals. The cells’ schedule for polarization is set prior to gastrulation, is stable through several rounds of cell division and appears independent of the morphogenetic movements of gastrulation and neurulation. Conclusions Time rather than local environment regulates the schedule of epithelial polarization in zebrafish neural rod. PMID:23521850

2013-01-01

142

Nasogastric feeding tube  

MedlinePLUS

Feeding - nasogastric tube; NG tube; Bolus feeding; Continuous pump feeding; Gavage tube ... A nasogastric tube, or NG tube, is a special tube that carries food and medicine to the stomach through the nose. It can be used for ...

143

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

144

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

145

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

146

Comparison of Complication Rates, Types, and Average Tube Patency Between Jejunostomy Tubes and Percutaneous Gastrostomy Tubes in a Regional Home Enteral Nutrition Support Program.  

PubMed

Background: Percutaneous endoscopic gastrostomy (PEG) tubes are common enteral access devices for long-term enteral nutrition. Jejunostomy tubes (J-tubes) are able to provide postpyloric enteral access in patients who are not PEG tube candidates. There is a scarcity of literature comparing complication rates of J-tubes to PEG tubes. Objective: To compare and characterize J-tube and PEG tube complications requiring tube replacement. Methods: A retrospective chart review was performed on 560 patients discharged from the Northern Alberta Home Enteral Nutrition Support Program (NAHENSP) from January 2010 to December 2011. Patients were followed for 3 years from initial tube insertion or until discharge from the NAHENSP, whichever was earliest. Comparisons were made in terms of complications requiring tube replacement, tube patency to first replacement, and indications for tube replacement. Results: A total of 64 J-tube patients were identified and compared with 65 PEG tube patients. Tube replacement rates for the J-tube group included 3.2 cases per 1000 patient days compared with 0.86 cases per 1000 patient days in the PEG group (P < .001). The mean ± SEM duration to first tube replacement for J-tube and PEG tube patients was 160 ± 26.3 days and 331 ± 53.6 days, respectively (P = .010). The most common causes for tube replacement in J-tube patients were dislodgement (35.6%) and obstruction (22.2%) compared with routine replacement (54.5%) and dislodgement (27.2%) in the PEG tube group. Conclusion: J-tubes are associated with higher complication rates requiring tube replacement compared with PEG tubes. The main causes of J-tube replacement are dislodgement and obstruction. PMID:25378355

Ao, Peter; Sebastianski, Meghan; Selvarajah, Vijeyakumar; Gramlich, Leah

2014-11-01

147

Diffusion tube  

NASA Technical Reports Server (NTRS)

The diffusion tube was designed to operate below about 0.25 percent of water supersaturation. It is simply a long tube lined on the inside with a damp chamois cloth, and heated isothermally to a few degrees centigrade above the incoming air. The diffusion coefficient for water vapor is slightly larger than that for heat, making it possible to supersaturate the airflow. This is the same principle by which transient supersaturations may occur in parallel plate cloud chambers. Only the diffusion of vapor and heat from the walls into the moving air are considered.

Leaitch, R.; Megaw, W. J.

1981-01-01

148

Tube Feedings.  

ERIC Educational Resources Information Center

This module on tube feedings is intended for use in inservice or continuing education programs for persons who work in long-term care. Instructor information, including teaching suggestions and a listing of recommended audiovisual materials and their sources appear first. The module goal and objectives are then provided. A brief discussion follows…

Plummer, Nancy

149

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

150

Vitamin dificiencies and neural tube defects  

Microsoft Academic Search

Serum folate, red cell folate, white blood cell vitamin C, riboflavin saturation index, and serum vitamin A were determined during the first trimester of pregnancy in over 900 cases. For each of these there was a social classes I + II showed the highest levels which differed significantly from other classes, except for serum folate. In 6 mothers who gave

R. W. Smithells; S Sheppard; C J Schorah

1976-01-01

151

Fetal surgery for neural tube defects  

PubMed Central

Open spina bifida remains a major source of disability despite an overall decrease in incidence. It is frequently diagnosed prenatally and can thus -- potentially -- be treated by fetal surgery. Animal studies and preliminary human studies strongly suggest that at least a portion of the neurological abnormalities seen in these patients are secondary, and occur in mid-gestation. It is estimated that approximately 400 fetal operations have now been performed for myelomeningocele world wide. Despite this large experience, the technique remains of unproven benefit. Preliminary results suggest that fetal surgery results in reversal of hindbrain herniation (the Chiari II malformation), a decrease in shunt-dependent hydrocephalus, and possibly improvement in leg function, but these findings might be explained by selection bias and changing management indications. A randomized prospective trial (the MOMS trial) is currently being conducted by three centers in the United States, and is estimated to be completed in 2009. PMID:17714997

Sutton, Leslie N.

2008-01-01

152

Electron tube  

DOEpatents

An electron tube of the present invention includes: a vacuum vessel including a face plate portion made of synthetic silica and having a surface on which a photoelectric surface is provided, a stem portion arranged facing the photoelectric surface and made of synthetic silica, and a side tube portion having one end connected to the face plate portion and the other end connected to the stem portion and made of synthetic silica; a projection portion arranged in the vacuum vessel, extending from the stem portion toward the photoelectric surface, and made of synthetic silica; and an electron detector arranged on the projection portion, for detecting electrons from the photoelectric surface, and made of silicon.

Suyama, Motohiro (Hamamatsu, JP); Fukasawa, Atsuhito (Hamamatsu, JP); Arisaka, Katsushi (Los Angeles, CA); Wang, Hanguo (North Hills, CA)

2011-12-20

153

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

154

Epigenetic regulation in neural crest development.  

PubMed

The neural crest is a migratory and multipotent cell population that plays a crucial role in many aspects of embryonic development. In all vertebrate embryos, these cells emerge from the dorsal neural tube then migrate long distances to different regions of the body, where they contribute to formation of many cell types and structures. These include much of the peripheral nervous system, craniofacial skeleton, smooth muscle, and pigmentation of the skin. The best-studied regulatory events guiding neural crest development are mediated by transcription factors and signaling molecules. In recent years, however, growing evidence supports an important role for epigenetic regulation as an additional mechanism for controlling the timing and level of gene expression at different stages of neural crest development. Here, we summarize the process of neural crest formation, with focus on the role of epigenetic regulation in neural crest specification, migration, and differentiation as well as in neural crest related birth defects and diseases. PMID:25446277

Hu, Na; Strobl-Mazzulla, Pablo H; Bronner, Marianne E

2014-12-15

155

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

156

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

157

Tapered pulse tube for pulse tube refrigerators  

DOEpatents

Thermal insulation of the pulse tube in a pulse-tube refrigerator is maintained by optimally varying the radius of the pulse tube to suppress convective heat loss from mass flux streaming in the pulse tube. A simple cone with an optimum taper angle will often provide sufficient improvement. Alternatively, the pulse tube radius r as a function of axial position x can be shaped with r(x) such that streaming is optimally suppressed at each x.

Swift, Gregory W. (Sante Fe, NM); Olson, Jeffrey R. (San Mateo, CA)

1999-01-01

158

Trunk neural crest has skeletogenic potential.  

PubMed

During early vertebrate development, neural crest cells emerge from the dorsal neural tube, migrate into the periphery, and form a wide range of derivatives. There is, however, a significant difference between the cranial and trunk neural crest with respect to the diversity of cell types that each normally produces. Thus, while crest cells from all axial levels form neurons, glia, and melanocytes, the cranial crest additionally generates skeletal derivatives such as bone and cartilage; trunk crest cells are generally thought to lack skeletogenic potential. Here, we show, however, that if avian trunk neural crest cells are cultured in appropriate media, they form both bone and cartilage cells, and if placed into the developing head, they contribute to cranial skeletal components. Thus, the neural crest from all axial levels can generate the full repertoire of crest derivatives. The skeletogenic potential of the trunk neural crest is significant, as it was likely realized in early vertebrates, which had extensive postcranial exoskeletal coverings. PMID:12007423

McGonnell, Imelda M; Graham, Anthony

2002-04-30

159

Gastrostomy feeding tube - bolus  

MedlinePLUS

Feeding - gastrostomy tube - bolus; G-tube - bolus; Gastrostomy button - bolus; Bard Button - bolus; MIC-KEY - bolus ... Your child’s gastrostomy tube or “G-tube” is a special tube in your child’s stomach that will help deliver food and medicines until your child can chew and ...

160

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

161

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

162

Feeding tube - infants  

MedlinePLUS

Gavage tube - infants; OG - infants; NG - infants ... small, soft, plastic tube placed through the nose (NG) or mouth (OG) into the stomach. These tubes are used to provide feedings and medications into ...

163

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

164

Background Notes  

NSDL National Science Digital Library

Country Background Notes, distributed on the DOSBACK list, are updated periodically and include information on US bilateral relations with foreign countries and on their governments, political conditions, and foreign relations. You can expect the DOSBACK list to generate about 3-4 email messages per month. Via DOSBACK you will receive the full-text version of newly released Background Notes. Archives of these two lists are also available at the Department of State Foreign Affairs Network (DOSFAN) gopher at the University of Illinois-Chicago.

165

Background & Publications  

E-print Network

Home Background & Projects Calendar Publications Staff Directory Station Videos Links Search Northern Michigan FruitNet 2008 Weekly Update NW Michigan Horticultural Research Station Nikki Rothwell maggot from growers. European red mites and two-spotted spider mites have reached threshold levels

166

Ultrasound Can Accurately Guide Gastrostomy Tube Replacement and Confirm Proper Tube Placement at the Bedside  

Microsoft Academic Search

Background: Malfunctioning or dislodged gastrostomy tubes (G-tubes) often require urgent replacement and reinsertion in the Emergency Department (ED). Few data exist regarding the best technique for bedside catheter replacement and verification, and individual operator preferences vary. Although a few reports have described the use of ultrasound guidance during the initial percutaneous insertion, no data are available concerning its role during

Teresa S. Wu; Stephen J. Leech; Marcy Rosenberg; Charles Huggins; Linda Papa

2009-01-01

167

Properties of a Fetal Multipotent Neural Stem Cell (NEP Cell)  

Microsoft Academic Search

Multipotent neural stem cells (NSCs) present in the developing neural tube (E10.5, neuroepithelial cells; NEP) were examined for the expression of candidate stem cell markers, and the expression of these markers was compared with later appearing precursor cells (E14.5) that can be distinguished by the expression of embryonic neural cell adhesion molecule (E-NCAM) and A2B5. NEP cells possess gap junctions,

Jingli Cai; Yuanyuan Wu; Takumi Mirua; Jeanne L. Pierce; Mary T. Lucero; Kurt H. Albertine; Gerald J. Spangrude; Mahendra S. Rao

2002-01-01

168

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

169

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

170

1999 tubing guide  

SciTech Connect

Petroleum Engineer International`s 1999 Tubing Guide contains performance and metallurgical data, as well as connection dimensions, on tubing from several companies. Parameters listed in each section were selected with the input of buyers and manufacturers of connections and tubing. Connections listings include: nominal tube OD, weight, tensile efficiency, sealing system, standard connection OD, special clearance OD, minimum ID and make-up loss. The grades section lists the tubing OD range, yield strength, tensile strength, hardness and whether the tubing is seamless or welded. An applications index specifies the downhole environments each grade can survive.

NONE

1999-06-01

171

Endoscopic nasogastric-jejunal feeding tube placement in critically ill patients  

Microsoft Academic Search

Background: Historically, placement of small bowel nasoenteric feeding tubes in the critically ill patient has been difficult because of lack of bedside fluoroscopy, inadequately designed endoscopic tubes, or failure of the tube to spontaneously pass into the duodenum following placement. Methods: We followed-up 54 consecutive critically ill patients who had a combined nasogastric-jejunal feeding tube placed at the bedside using

Paula G. Patrick; Shivaprasad Marulendra; Donald F. Kirby; Mark H. DeLegge

1997-01-01

172

Neural Networks  

SciTech Connect

Physicists use large detectors to measure particles created in high-energy collisions at particle accelerators. These detectors typically produce signals indicating either where ionization occurs along the path of the particle, or where energy is deposited by the particle. The data produced by these signals is fed into pattern recognition programs to try to identify what particles were produced, and to measure the energy and direction of these particles. Ideally, there are many techniques used in this pattern recognition software. One technique, neural networks, is particularly suitable for identifying what type of particle caused by a set of energy deposits. Neural networks can derive meaning from complicated or imprecise data, extract patterns, and detect trends that are too complex to be noticed by either humans or other computer related processes. To assist in the advancement of this technology, Physicists use a tool kit to experiment with several neural network techniques. The goal of this research is interface a neural network tool kit into Java Analysis Studio (JAS3), an application that allows data to be analyzed from any experiment. As the final result, a physicist will have the ability to train, test, and implement a neural network with the desired output while using JAS3 to analyze the results or output. Before an implementation of a neural network can take place, a firm understanding of what a neural network is and how it works is beneficial. A neural network is an artificial representation of the human brain that tries to simulate the learning process [5]. It is also important to think of the word artificial in that definition as computer programs that use calculations during the learning process. In short, a neural network learns by representative examples. Perhaps the easiest way to describe the way neural networks learn is to explain how the human brain functions. The human brain contains billions of neural cells that are responsible for processing information [2]. Each one of these cells acts as a simple processor. When individual cells interact with one another, the complex abilities of the brain are made possible. In neural networks, the input or data are processed by a propagation function that adds up the values of all the incoming data. The ending value is then compared with a threshold or specific value. The resulting value must exceed the activation function value in order to become output. The activation function is a mathematical function that a neuron uses to produce an output referring to its input value. [8] Figure 1 depicts this process. Neural networks usually have three components an input, a hidden, and an output. These layers create the end result of the neural network. A real world example is a child associating the word dog with a picture. The child says dog and simultaneously looks a picture of a dog. The input is the spoken word ''dog'', the hidden is the brain processing, and the output will be the category of the word dog based on the picture. This illustration describes how a neural network functions.

Smith, Patrick I.

2003-09-23

173

1998 tubing guide  

SciTech Connect

Petroleum Engineer International`s 1998 Tubing Guide contains performance and metallurgical data, as well as connection dimensions, on tubing from more than 20 companies. Parameters listed in each section were selected with the input of buyers and manufacturers of connections and tubing. Connections listings include: nominal tube OD, weight, tensile efficiency, sealing system, standard connection OD, special clearance OD, minimum ID and make-up loss. The grades section lists the tubing OD range, yield strength, tensile strength, hardness and whether the tubing is seamless or welded. An applications index specifies the downhole environments each grade can survive. Information in these tables was provided by the individual companies listed. PEI`s 1998 Tubing Guide should be used as a reference when planning tubing programs. However, you should consult with company representatives for confirmation of data before making final decisions. A contact key of the participating companies is listed.

NONE

1998-06-01

174

Microscale shock tube  

Microsoft Academic Search

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

Gholamreza Mirshekari

2008-01-01

175

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).

Oglesby, Ken

176

Chest Tube Thoracostomy  

MedlinePLUS

... tube is inserted, except when it in placed in the operating room during an open chest procedure. Sometimes a person, ... you may have after the chest tube is in place ? Have your nurse show you how the chest tube site is ...

177

Microhole Tubing Bending Report  

SciTech Connect

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).

Oglesby, Ken

2012-01-01

178

Fallopian Tube Cancer  

MedlinePLUS

eNEWS SIGNUP f t y g H Types of Cancer Navigating Cancer Care Coping and Emotions Research and Advocacy Survivorship Blog About Us s You are here Home > Types of Cancer > Fallopian Tube Cancer Fallopian Tube Cancer This is Cancer.Net’s Guide to Fallopian Tube Cancer. Use the menu below to choose the Overview ...

179

Nasogastric tube versus gastrostomy tube for gastric decompression in abdominal surgery: a prospective, randomized trial comparing patients' tube-related inconvenience  

Microsoft Academic Search

Background: Perioperative decompression of the stomach is still a common procedure and can be achieved using either nasogastric tubes (NTs) or gastrostomy tubes (GTs). While both procedures appear to be equally effective, some authors believe that NTs are less convenient for patients than GTs. However, to date, no reliable prospective data are available on this issue. Methods: We conducted a

S. Hoffmann; M. Koller; U. Plaul; B. Stinner; B. Gerdes; W. Lorenz; M. Rothmund

2001-01-01

180

Arrested neural and advanced mesenchymal differentiation of glioblastoma cells-comparative study with neural progenitors  

Microsoft Academic Search

BACKGROUND: Although features of variable differentiation in glioblastoma cell cultures have been reported, a comparative analysis of differentiation properties of normal neural GFAP positive progenitors, and those shown by glioblastoma cells, has not been performed. METHODS: Following methods were used to compare glioblastoma cells and GFAP+NNP (NHA): exposure to neural differentiation medium, exposure to adipogenic and osteogenic medium, western blot

Piotr Rieske; Ewa Golanska; Magdalena Zakrzewska; Sylwester Piaskowski; Krystyna Hulas-Bigoszewska; Magdalena Wola?czyk; Malgorzata Szybka; Monika Witusik-Perkowska; Dariusz J Jaskolski; Krzysztof Zakrzewski; Wojciech Biernat; Barbara Krynska; Pawel P Liberski

2009-01-01

181

Tube Thoracostomy: Complications and Its Management  

PubMed Central

Background. Tube thoracostomy is widely used throughout the medical, surgical, and critical care specialities. It is generally used to drain pleural collections either as elective or emergency. Complications resulting from tube thoracostomy can occasionally be life threatening. Aim. To present an update on the complications and management of complications of tube thoracostomy. Methods. A review of the publications obtained from Medline search, medical libraries, and Google on tube thoracostomy and its complications was done. Results. Tube thoracostomy is a common surgical procedure which can be performed by either the blunt dissection technique or the trocar technique. Complication rates are increased by the trocar technique. These complications have been broadly classified as either technical or infective. Technical causes include tube malposition, blocked drain, chest drain dislodgement, reexpansion pulmonary edema, subcutaneous emphysema, nerve injuries, cardiac and vascular injuries, oesophageal injuries, residual/postextubation pneumothorax, fistulae, tumor recurrence at insertion site, herniation through the site of thoracostomy, chylothorax, and cardiac dysrhythmias. Infective complications include empyema and surgical site infection. Conclusion. Tube thoracostomy, though commonly performed is not without risk. Blunt dissection technique has lower risk of complications and is hence recommended. PMID:22028963

Kesieme, Emeka B.; Dongo, Andrew; Ezemba, Ndubueze; Irekpita, Eshiobo; Jebbin, Nze; Kesieme, Chinenye

2012-01-01

182

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

183

Retrograde Gastrojejunostomy Tube Migration  

PubMed Central

Percutaneous enteral feeding tubes are placed about 250,000 times each year in the United States. Although they are relatively safe, their placement may be complicated by perforation, infection, bleeding, vomiting, dislodgment, and obstruction. There have been numerous reports of antegrade migration of gastrojejunostomy (G-J) tubes. We report a case of G-J tube regurgitation following protracted vomiting and discuss the management of this very rare entity.

Adesina, Adeleke; Rammohan, Guhan

2014-01-01

184

Ruggedized electronographic tube development  

NASA Technical Reports Server (NTRS)

Because of their glass components and lack of far ultraviolet sensitivity, currently available Spectracons are not suited for rocket launch. Technology developed for second generation image tubes and for magnetically focused image tubes can be applied to improve the optical and mechanical properties of these magnetically focused electronographic tubes whose 40 kilovolt signal electrons exit a 4-micrometer thick mica window and penetrate a photographic recording emulsion.

Nevin, S.

1981-01-01

185

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

186

Composite Pulse Tube  

NASA Technical Reports Server (NTRS)

A modification of the design of the pulse tube in a pulse-tube cryocooler reduces axial thermal conductance while preserving radial thermal conductance. It is desirable to minimize axial thermal conductance in the pulse-tube wall to minimize leakage of heat between the warm and cold ends of the pulse tube. At the same time, it is desirable to maximize radial thermal conductance at the cold end of the pulse tube to ensure adequate thermal contact between (1) a heat exchanger in the form of a stack of copper screens inside the pulse tube at the cold end and (2) the remainder of the cold tip, which is the object to which the heat load is applied and from which heat must be removed. The modified design yields a low-heat-leak pulse tube that can be easily integrated with a cold tip. A typical pulse tube of prior design is either a thin-walled metal tube or a metal tube with a nonmetallic lining. It is desirable that the outer surface of a pulse tube be cylindrical (in contradistinction to tapered) to simplify the design of a regenerator that is also part of the cryocooler. Under some conditions, it is desirable to taper the inner surface of the pulse tube to reduce acoustic streaming. The combination of a cylindrical outer surface and a tapered inner surface can lead to unacceptably large axial conduction if the pulse tube is made entirely of metal. Making the pulse-tube wall of a nonmetallic, lowthermal- conductivity material would not solve the problem because the wall would not afford the needed thermal contact for the stack of screens in the cold end. The modified design calls for fabricating the pulse tube in two parts: a longer, nonmetallic part that is tapered on the inside and cylindrical on the outside and a shorter, metallic part that is cylindrical on both the inside and the outside. The nonmetallic part can be made from G-10 fiberglass-reinforced epoxy or other low-thermal-conductivity, cryogenically compatible material. The metallic part must have high thermal conductivity in the cryogenic temperature range and would typically be made of pure copper to satisfy this requirement. The metallic part is bonded to the nonmetallic part with epoxy. Copper screens are inserted in the metallic part to form the cold-end heat exchanger, then the assembled pulse tube is inserted in the cold tip.

Martin, Jerry L.; Cloyd, Jason H.

2007-01-01

187

Sapphire tube pressure vessel  

SciTech Connect

A pressure vessel is provided for observing corrosive fluids at high temperatures and pressures. A transparent Teflon bag contains the corrosive fluid and provides an inert barrier. The Teflon bag is placed within a sapphire tube, which forms a pressure boundary. The tube is received within a pipe including a viewing window. The combination of the Teflon bag, sapphire tube and pipe provides a strong and inert pressure vessel. In an alternative embodiment, tie rods connect together compression fittings at opposite ends of the sapphire tube.

Outwater, J.O.

2000-05-23

188

Nasogastric and Enteral Feeding Tubes GI/GU Nasogastric Tubes  

E-print Network

Nasogastric and Enteral Feeding Tubes GI/GU Nasogastric Tubes: Kendall Argyle Salem tube can should be high enough to evacuate the tube. 10 kg = 35-50 mmHg Nasogastric enteral. and 10 FR. Nasogastric and Enteral Feeding Tubes Lucile Packard Children's Hospital Heart Center

Kay, Mark A.

189

Looking Southeast Along Kilauea TEB Tube System  

USGS Multimedia Gallery

View looking southeast along the fuming trace of the TEB tube system. The growing rootless shield field is in the background just above and to the left of center frame. The low, rounded shape of the shields--especially the shield in shadow to the left--are evident in this photo....

2010-07-19

190

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

191

Neural Communication  

NSDL National Science Digital Library

First you will explore the neuron. Then how neurons communicate with each other by exploring action potentials and neural transmission. Let's start with the neuron. Explore the neuron and fill out the worksheet by labeling each part of the neuron and giving a brief description of what it does. Structure of the Neuron (Upon entering the site go through each link at the top of the page from intro to terminal buttons) Now take a look ...

Mrs. Johnson

2010-06-22

192

Gastrostomy feeding tube - pump  

MedlinePLUS

Feeding - gastrostomy tube - pump; G-tube - pump; Gastrostomy button - pump; Bard Button - pump; MIC-KEY - pump ... Gather supplies: Feeding pump (electronic or battery powered) Feeding set that matches the feeding pump (includes a feeding bag, drip chamber, roller clamp, ...

193

Hologram recording tubes  

NASA Technical Reports Server (NTRS)

Optical memories allow extremely large numbers of bits to be stored and recalled in a matter of microseconds. Two recording tubes, similar to conventional image-converting tubes, but having a soft-glass surface on which hologram is recorded, do not degrade under repeated hologram read/write cycles.

Rajchman, J. H.

1973-01-01

194

THE UV-TUBE AS AN APPROPRIATE WATER DISINFECTION TECHNOLOGY  

E-print Network

......................................................................................................... 7 IV. BACKGROUND: SCIENCE AND TECHNOLOGY OF UV DISINFECTION.................................. 12 Vi THE UV-TUBE AS AN APPROPRIATE WATER DISINFECTION TECHNOLOGY: An Assessment of Technical Performance and Potential for Dissemination Alicia Cohn Master's Project for The Energy and Resources Group

Kammen, Daniel M.

195

1.0 BACKGROUND VIBRATIONS INDUCED BY THE FLOW  

E-print Network

on the beam tube (A3' H), it can be observed that the total rms acceleration response increased by a factor. oos G- :::. \\v - - - - - - - · 0 1 o( l HZ LIN Fig. 2. Beam Tube (A 3 ) Acc _.Jater Off) Background #12;1 0 0 V SQR 1. 0 puu 3 , LL

Kemner, Ken

196

Fallopian Tube Catheterization  

PubMed Central

Fallopian tube catheterization is used for treatment of infertility caused by proximal tubal occlusion, and has replaced surgical treatment for this condition. More recently, fallopian tube catheterization has been used for tubal sterilization. Interventional radiologists tested numerous methods for tubal occlusion using the rabbit as an animal model. As a result, a tubal device has recently been Food and Drug Administration approved for permanent sterilization using hysteroscopic guidance; it can also be placed fluoroscopically by fallopian tube catheterization as an “off-label” procedure. This is a 5-year continuation and update on a procedure that has been done by interventional radiologists for 25 years; history of the development of fallopian tube catheterization in women has been published in detail in this journal. Highlighted in this article will be description of the basic components needed for fallopian tube catheterization. PMID:24436565

Thurmond, Amy Suzanne

2013-01-01

197

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

198

A spatiotemporal coding mechanism for background-invariant odor recognition.  

PubMed

Sensory stimuli evoke neural activity that evolves over time. What features of these spatiotemporal responses allow the robust encoding of stimulus identity in a multistimulus environment? Here we examined this issue in the locust (Schistocerca americana) olfactory system. We found that sensory responses evoked by an odorant (foreground) varied when presented atop or after an ongoing stimulus (background). These inconsistent sensory inputs triggered dynamic reorganization of ensemble activity in the downstream antennal lobe. As a result, partial pattern matches between neural representations encoding the same foreground stimulus across conditions were achieved. The degree and segments of response overlaps varied; however, any overlap observed was sufficient to drive background-independent responses in the downstream neural population. Notably, recognition performance of locusts in behavioral assays correlated well with our physiological findings. Hence, our results reveal how background-independent recognition of odors can be achieved using spatiotemporal patterns of neural activity. PMID:24185426

Saha, Debajit; Leong, Kevin; Li, Chao; Peterson, Steven; Siegel, Gregory; Raman, Baranidharan

2013-12-01

199

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

200

[Enteral tube feeding].  

PubMed

Tube feeding is an integral part of medical therapies, and can be easily managed also in the outpatient setting. Tube feeding by the stomach or small intestine with nasogastral or nasojejunal tubes is common in clinical practice. Long-term nutrition is usually provided through a permanent tube, i. e. a percutaneous endoscopic gastrostomy (PEG). Modern portable nutrition pumps are used to cover the patient's nutritional needs. Enteral nutrition is always indicated if patients can not or should not eat or if nutritional requirements cannot be covered within 3 days after an intervention, e. g. after abdominal surgery. Industrially produced tube feedings with defined substrate concentrations are being used; different compositions of nutrients, such as glutamine fish oil etc., are used dependent on the the condition of the patient. Enteral nutrition may be associated with complications of the tube, e. g. dislocation, malposition or obstruction, as well as the feeding itself, e. g.hyperglycaemia, electrolyte disturbances, refeeding syndrome diarrhea or aspiration). However, the benefit of tube feeding usually exceeds the potential harm substantially. PMID:24568855

Haller, Alois

2014-03-01

201

PE on YouTube--Investigating Participation in Physical Education Practice  

ERIC Educational Resources Information Center

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…

Quennerstedt, Mikael

2013-01-01

202

FGF8 signaling is chemotactic for cardiac neural crest cells.  

PubMed

Cardiac neural crest cells migrate into the pharyngeal arches where they support development of the pharyngeal arch arteries. The pharyngeal endoderm and ectoderm both express high levels of FGF8. We hypothesized that FGF8 is chemotactic for cardiac crest cells. To begin testing this hypothesis, cardiac crest was explanted for migration assays under various conditions. Cardiac neural crest cells migrated more in response to FGF8. Single cell tracing indicated that this was not due to proliferation and subsequent transwell assays showed that the cells migrate toward an FGF8 source. The migratory response was mediated by FGF receptors (FGFR) 1 and 3 and MAPK/ERK intracellular signaling. To test whether FGF8 is chemokinetic and/or chemotactic in vivo, dominant negative FGFR1 was electroporated into the premigratory cardiac neural crest. Cells expressing the dominant negative receptor migrated slower than normal cardiac neural crest cells and were prone to remain in the vicinity of the neural tube and die. Treating with the FGFR1 inhibitor, SU5402 or an FGFR3 function-blocking antibody also slowed neural crest migration. FGF8 over-signaling enhanced neural crest migration. Neural crest cells migrated to an FGF8-soaked bead placed dorsal to the pharynx. Finally, an FGF8 producing plasmid was electroporated into an ectopic site in the ventral pharyngeal endoderm. The FGF8 producing cells attracted a thick layer of mesenchymal cells. DiI labeling of the neural crest as well as quail-to-chick neural crest chimeras showed that neural crest cells migrated to and around the ectopic site of FGF8 expression. These results showing that FGF8 is chemotactic and chemokinetic for cardiac neural crest adds another dimension to understanding the relationship of FGF8 and cardiac neural crest in cardiovascular defects. PMID:21419761

Sato, Asako; Scholl, Ann Marie; Kuhn, E N; Kuhn, E B; Stadt, Harriett A; Decker, Jennifer R; Pegram, Kelly; Hutson, Mary R; Kirby, Margaret L

2011-06-01

203

Trends in silicone tubing.  

PubMed

Silicone is the material of choice for many new applications. Those examined here include drug delivery and peristaltic pumps, pacemaker leads and tubing used in minimally invasive surgery and to deliver high pressure gases and liquids. PMID:19133622

Jahn, Donald

2008-01-01

204

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

205

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

206

Dynamics of tubes in fluid with tube-baffle interaction  

SciTech Connect

Three series of tests are performed to evaluate the effects of tube to tube-support-plate (TSP) clearance on tube dynamic characteristics and instability phenomena for tube arrays in crossflow. Test results show that, for relatively large clearances, tubes may possess TSP-inactive modes in which the tubes rattle inside some of the tube-support-plate holes, and that the natural frequencies of TSP-inactive modes are lower than those of TSP-active modes, in which the support plates provide knife-edge type support. Tube response characteristics associated with TSP-inactive modes are sensitive to tube-to-TSP clearance, TSP thickness, excitation amplitude, tube alignment, and the fluid inside the clearance. In addition, tube response is intrinsically nonlinear, with the dominance of TSP-inactive or TSP-active modes depending on the magnitudes of different system parameters. In general, such a system is difficult to model; only a full-scale test can provide all the necessary characteristics. A tube array supported by TSPs with relatively large clearances may be subjected to dynamic instability in some of the TSP-inactive modes; tube response characteristics and impact forces on TSPs for a tube row are studied in detail in this report. Tube displacements associated with the instability of a TSP-inactive mode are small; however, impacts of the tube against TSPs may result in significant damage in a relatively short time. 52 figures.

Chen, S.S.; Jendrzejczyk, J.A.; Wambsganss, M.W.

1983-09-01

207

Aeronautical tubes and pipes  

NASA Astrophysics Data System (ADS)

The main and subcomponent French suppliers of aircraft tubes and pipes are discussed, and the state of the industry is analyzed. Quality control is essential for tubes with regard to their i.d. and metallurgical compositions. French regulations do not allow welded seam tubes in hydraulic circuits unless no other form is available, and then rustproofed steel must be installed. The actual low level of orders for any run of tubes dictates that the product is only one of several among the manufacturers' line. Automation, both in NDT and quality control, assures that the tubes meet specifications. A total of 10 French companies participate in the industry, serving both civil and military needs, with some companies specializing only in titanium, steel, or aluminum materials. Concerns wishing to enter the market must upgrade their equipment to meet the higher aeronautical specifications and be prepared to furnish tubes and pipes that serve both functional and structural purposes simultaneously. Additionally, pipe-bending machines must also perform to tight specifications. Pipes can range from 0.2 mm exterior diameter to 40 mm, with wall thicknesses from 0.02 mm to 3 mm. A chart containing a list of manufacturers and their respective specifications and characteristics is presented, and a downtrend in production with reduction of personnel is noted.

Beauclair, N.

1984-12-01

208

Weakly Supervised Learning of Foreground-Background Segmentation using  

E-print Network

Weakly Supervised Learning of Foreground-Background Segmentation using Masked RBMs Nicolas Heess1 representation into the DL framework. In this model, the Masked RBM (MRBM), an image is composed of several re Conference on Artificial Neural Networks (2011)" #12;2 Masked-RBMs for Foreground-Background Segmentation

Boyer, Edmond

209

Terminal Attractors In Neural Networks  

NASA Technical Reports Server (NTRS)

Neural networks made to "learn" faster. Report presents theoretical study of terminal attractors in neural networks. Includes systematic analysis of applications to activation dynamics of neural networks.

Zak, Michail A.

1991-01-01

210

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

211

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

212

Extended multipotency of neural crest cells and neural crest-derived cells.  

PubMed

Neural crest cells (NCC) are migratory multipotent cells that give rise to diverse derivatives. They generate various cell types during embryonic development, including neurons and glial cells of the peripheral sensory and autonomic ganglia, Schwann cells, melanocytes, endocrine cells, smooth muscle, and skeletal and connective tissue cells of the craniofacial complex. The multipotency of NCC is thought to be transient at the early stage of NCC generation; once NCC emerge from the neural tube, they change into lineage-restricted precursors. Although many studies have described the clear segregation of NCC lineages right after their delamination from the neural tube, recent reports suggest that multipotent neural crest stem cells (NCSC) are present not only in migrating NCC in the embryo, but also in their target tissues in the fetus and adult. Furthermore, fully differentiated NCC-derived cells such as glial cells and melanocytes have been shown to dedifferentiate or transdifferentiate into other NCC derivatives. The multipotency of migratory and postmigratory NCC-derived cells was found to be similar to that of NCSC. Collectively, these findings support the multipotency or plasticity of NCC and NCC-derived cells. PMID:25662258

Motohashi, Tsutomu; Kunisada, Takahiro

2015-01-01

213

Anonymitet och YouTube; Anonymity and YouTube.  

E-print Network

?? Denna studie undersöker hur minskad anonymitet kan förändra sättet människor skriver kommentarer på YouTube-videor. YouTube begärde nyligen att användarna skulle ange sina fullständiga namn.… (more)

Karlsson, Katarina

2012-01-01

214

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

215

Marshmallow Puff Tube  

NSDL National Science Digital Library

In this demonstration/activity, learners observe as a regular size marshmallow is blown through a tube made from a manila file folder. The result is spectacular, and the process provides a great illustration of Newton's 2nd Law, F=ma.

Rathjen, Don

2007-01-01

216

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

217

Downhole pulse tube refrigerators  

SciTech Connect

This report summarizes a preliminary design study to explore the plausibility of using pulse tube refrigeration to cool instruments in a hot down-hole environment. The original motivation was to maintain Dave Reagor`s high-temperature superconducting electronics at 75 K, but the study has evolved to include three target design criteria: cooling at 30 C in a 300 C environment, cooling at 75 K in a 50 C environment, cooling at both 75 K and 30 C in a 250 C environment. These specific temperatures were chosen arbitrarily, as representative of what is possible. The primary goals are low cost, reliability, and small package diameter. Pulse-tube refrigeration is a rapidly growing sub-field of cryogenic refrigeration. The pulse tube refrigerator has recently become the simplest, cheapest, most rugged and reliable low-power cryocooler. The authors expect this technology will be applicable downhole because of the ratio of hot to cold temperatures (in absolute units, such as Kelvin) of interest in deep drilling is comparable to the ratios routinely achieved with cryogenic pulse-tube refrigerators.

Swift, G.; Gardner, D. [Los Alamos National Lab., NM (United States). Condensed Matter and Thermal Physics Group

1997-12-01

218

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

219

Morphological neural networks  

SciTech Connect

The theory of artificial neural networks has been successfully applied to a wide variety of pattern recognition problems. In this theory, the first step in computing the next state of a neuron or in performing the next layer neural network computation involves the linear operation of multiplying neural values by their synaptic strengths and adding the results. Thresholding usually follows the linear operation in order to provide for nonlinearity of the network. In this paper we introduce a novel class of neural networks, called morphological neural networks, in which the operations of multiplication and addition are replaced by addition and maximum (or minimum), respectively. By taking the maximum (or minimum) of sums instead of the sum of products, morphological network computation is nonlinear before thresholding. As a consequence, the properties of morphological neural networks are drastically different than those of traditional neural network models. In this paper we consider some of these differences and provide some particular examples of morphological neural network.

Ritter, G.X.; Sussner, P. [Univ. of Florida, Gainesville, FL (United States)

1996-12-31

220

Novel insight into the function and regulation of ?N-catenin by Snail2 during chick neural crest cell migration  

Microsoft Academic Search

The neural crest is a transient population of migratory cells that differentiates to form a variety of cell types in the vertebrate embryo, including melanocytes, the craniofacial skeleton, and portions of the peripheral nervous system. These cells initially exist as adherent epithelial cells in the dorsal aspect of the neural tube and only later become migratory after an epithelial-to-mesenchymal transition

S. Jhingory; C.-Y. Wu; L. A. Taneyhill

2010-01-01

221

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

222

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

223

Enhanced expression of FNDC5 in human embryonic stem cell-derived neural cells along with relevant embryonic neural tissues.  

PubMed

Availability of human embryonic stem cells (hESCs) has enhanced the capability of basic and clinical research in the context of human neural differentiation. Derivation of neural progenitor (NP) cells from hESCs facilitates the process of human embryonic development through the generation of neuronal subtypes. We have recently indicated that fibronectin type III domain containing 5 protein (FNDC5) expression is required for appropriate neural differentiation of mouse embryonic stem cells (mESCs). Bioinformatics analyses have shown the presence of three isoforms for human FNDC5 mRNA. To differentiate which isoform of FNDC5 is involved in the process of human neural differentiation, we have used hESCs as an in vitro model for neural differentiation by retinoic acid (RA) induction. The hESC line, Royan H5, was differentiated into a neural lineage in defined adherent culture treated by RA and basic fibroblast growth factor (bFGF). We collected all cell types that included hESCs, rosette structures, and neural cells in an attempt to assess the expression of FNDC5 isoforms. There was a contiguous increase in all three FNDC5 isoforms during the neural differentiation process. Furthermore, the highest level of expression of the isoforms was significantly observed in neural cells compared to hESCs and the rosette structures known as neural precursor cells (NPCs). High expression levels of FNDC5 in human fetal brain and spinal cord tissues have suggested the involvement of this gene in neural tube development. Additional research is necessary to determine the major function of FDNC5 in this process. PMID:25497839

Ahmadi Ghahrizjani, Fatemeh; Ghaedi, Kamran; Salamian, Ahmad; Tanhaei, Somayeh; Shoaraye Nejati, Alireza; Salehi, Hossein; Nabiuni, Mohammad; Baharvand, Hossein; Nasr-Esfahani, Mohammad Hossein

2015-02-25

224

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

225

Interaktivität auf YouTube.  

E-print Network

??Die vorliegende Arbeit beschäftigt sich mit den interaktiven Möglichkeiten auf der Videoplattform YouTube. Zu Beginn wird eine kurze Einleitung zu YouTube gegeben und grundlegende Begrifflichkeiten… (more)

Wilke, Christoph

2013-01-01

226

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

227

Environmental test report for the WX-32335 SEC camera tube. [for International Ultraviolet Explorer  

NASA Technical Reports Server (NTRS)

The environmental testing activity on the WX-32335 was carried out to determine if this tube type could withstand the environmental requirements established for the International Ultraviolet Explorer (IUE) camera tube (WX-32224). The results of the tests led to the following conclusions: (1) The WX-32335 as processed with a CsTe photocathode surface can withstand the temperature extremes established for the IUE camera tube without damage to the photocathode surface or without introducing background signal in the tube after one hour of dark integration. (2) The WX-32335 built with a WX-32224 type target support structure can withstand the sinusoidal vibration requirements established for the IUE camera tube. (3) Although the vibration test of the WX-32335 type tubes built with the flat target ring structure could not be completed, there was no indication that these tubes could not withstand the sinusoidal vibration requirements established for the IUE camera tube.

Malanoski, R. J.

1973-01-01

228

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

229

Sip1 mediates an E-cadherin-to-N-cadherin switch during cranial neural crest EMT  

PubMed Central

The neural crest, an embryonic stem cell population, initially resides within the dorsal neural tube but subsequently undergoes an epithelial-to-mesenchymal transition (EMT) to commence migration. Although neural crest and cancer EMTs are morphologically similar, little is known regarding conservation of their underlying molecular mechanisms. We report that Sip1, which is involved in cancer EMT, plays a critical role in promoting the neural crest cell transition to a mesenchymal state. Sip1 transcripts are expressed in premigratory/migrating crest cells. After Sip1 loss, the neural crest specifier gene FoxD3 was abnormally retained in the dorsal neuroepithelium, whereas Sox10, which is normally required for emigration, was diminished. Subsequently, clumps of adherent neural crest cells remained adjacent to the neural tube and aberrantly expressed E-cadherin while lacking N-cadherin. These findings demonstrate two distinct phases of neural crest EMT, detachment and mesenchymalization, with the latter involving a novel requirement for Sip1 in regulation of cadherin expression during completion of neural crest EMT. PMID:24297751

Rogers, Crystal D.; Saxena, Ankur

2013-01-01

230

Enteral Tube Feeding and Pneumonia  

ERIC Educational Resources Information Center

To determine the effects of enteral tube feeding on the incidence of pneumonia, we performed a retrospective review of all clients at our institution who had gastrostomy or jejunostomy tubes placed over a 10-year period. Ninety-three subjects had a history of pneumonia before feeding tube insertion. Eighty had gastrostomy and 13, jejunostomy…

Gray, David Sheridan; Kimmel, David

2006-01-01

231

NEI You Tube Videos: Amblyopia  

MedlinePLUS

... NEI Education Programs Training and Jobs NEI YouTube Videos YouTube Videos Home Age-Related Macular Degeneration Amblyopia ... of Prematurity Science Spanish Videos Webinars NEI YouTube Videos: Amblyopia Your browser does not support iframes please ...

232

Manufacturing SP100 rhenium tubes  

Microsoft Academic Search

A process for producing high quality, thin walled, wrought, rhenium tubing was successfully developed and qualified in the SP-100 fuel fabrication program. Rhenium was selected for the fuel-cladding barrier versus tungsten because of the cold workability and nuclear characteristics of rhenium. Several tube fabricating processes including swaging, drawing, and extruding sintered tube shells and chemical vapor deposition were evaluated before

Edwin D. Sayre; Thomas J. Ruffo

1992-01-01

233

Comparison of Image Quality and Radiation Dose between Fixed Tube Current and Combined Automatic Tube Current Modulation in Craniocervical CT Angiography  

Microsoft Academic Search

BACKGROUND AND PURPOSE: The combined automatic tube current modulation (ATCM) technique adapts and modulates the x-ray tube current in the x-y-z axis according to the patient's individual anatomy. We compared image quality and radiation dose of the combined ATCM technique with those of a fixed tube current (FTC) technique in craniocervical CT angiography performed with a 64-section multidetector row CT

E. J. Lee; S. K. Lee; R. Agid; P. Howard; J. M. Bae; K. terBrugge

2009-01-01

234

LARGE SCALE DEEP NEURAL NETWORK ACOUSTIC MODELING WITH SEMI-SUPERVISED TRAINING DATA FOR YOUTUBE VIDEO TRANSCRIPTION  

E-print Network

LARGE SCALE DEEP NEURAL NETWORK ACOUSTIC MODELING WITH SEMI-SUPERVISED TRAINING DATA FOR YOUTUBE, andrewsenior}@google.com ABSTRACT YouTube is a highly visited video sharing website where over one billion recognition. However, YouTube videos are extremely chal- lenging for automatic speech recognition systems

Tomkins, Andrew

235

Up-regulation of neural stem cell markers suggests the occurrence of dedifferentiation in regenerating spinal cord  

Microsoft Academic Search

Following tail amputation in urodele amphibians, an ependymal tube, that resembles a developing neural tube, forms from ependymal cells that migrate from the cord stump and elongates by cell proliferation. Expression of the keratin pair 8 and 18 has been observed in the developing urodele nervous system and is maintained in the ependymal cells of the mature cord. We show

Sally Walder; Fang Zhang; Patrizia Ferretti

2003-01-01

236

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

237

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

238

Chitin in pogonophore tubes  

Microsoft Academic Search

The chitin from pogonophore tubes is shown to be essentially the same as that from the pen of the squid Loligo and is classified as \\/I-chitin (as are the known chitins in annelids). However, certain important differences in detail are seen when comparing X-ray diffraction photographs and infra-red absorption spectra of the chitin from the two sources. These matters are

J. Blackwell; K. D. Parker; K. M. Rudall

1965-01-01

239

Joined concentric tubes  

DOEpatents

Tubular objects having two or more concentric layers that have different properties are joined to one another during their manufacture primarily by compressive and friction forces generated by shrinkage during sintering and possibly mechanical interlocking. It is not necessary for the concentric tubes to display adhesive-, chemical- or sinter-bonding to each other in order to achieve a strong bond. This facilitates joining of dissimilar materials, such as ceramics and metals.

DeJonghe, Lutgard; Jacobson, Craig; Tucker, Michael; Visco, Steven

2013-01-01

240

Cardboard Tube Syllabus  

NSDL National Science Digital Library

This site contains an activity demonstrating how oneâs 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.

2006-07-17

241

Fit and seal characteristics of a new paediatric tracheal tube with high volume-low pressure polyurethane cuff  

Microsoft Academic Search

Background: To evaluate a new paediatric tracheal tube (Microcuff, Weinheim, Germany) with an ultrathin high volume—low pressure polyurethane cuff. Methods: With approval of the Hospital Ethics Committee tracheas of children undergoing general anaesthesia were intub- ated using a Microcuff tube. Tube sizes were selected accord- ing to: internal diameter (mm) ¼ age\\/4 þ 3.5 in children aged ? 2 years.

A. Dullenkopf; A. C. Gerber; M. Weiss

2005-01-01

242

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

243

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

244

Background Subtraction Techniques  

Microsoft Academic Search

Background subtraction is a commonly used class of techniques for segmenting out objects of interest in a scene for applications such as surveillance. This paper surveys a repre- sentative sample of the published techiques for background subtraction, and analyses them with respect to three important attributes: foreground detection; background maintenance; and postprocessing.

Alan M. McIvor

245

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

246

Genetic background has a major effect on the penetrance and severity of craniofacial defects in mice heterozygous for the gene encoding the nucleolar protein Treacle.  

PubMed

Treacher Collins syndrome (TCS) is a craniofacial disorder that results from mutations in TCOF1, which encodes the nucleolar protein Treacle. The severity of the clinical features exhibits wide variation and includes hypoplasia of the mandible and maxilla, abnormalities of the external ears and middle ear ossicles, and cleft palate. To determine the in vivo function of Treacle, we previously generated Tcof1 heterozygous mice on a mixed C57BL/6 and 129 background. These mice exhibited a lethal phenotype, which included abnormal development of the maxilla, absence of the eyes and nasal passages, and neural tube defects. Here, we show that placing the mutation onto different genetic backgrounds has a major effect on the penetrance and severity of the craniofacial and other defects. The offspring exhibit markedly variable strain-dependent phenotypes that range from extremely severe and lethal in a mixed CBA/Ca and 129 background, to apparently normal and viable in a mixed BALB/c and 129 background. In the former case, in addition to a profoundly severe craniofacial phenotype, CBA-derived heterozygous mice also exhibited delayed ossification of the long bones, rib fusions, and digit anomalies. The results of our studies indicate that factors in the different genetic backgrounds contribute extensively to the Tcof1 phenotype. PMID:15042714

Dixon, Jill; Dixon, Michael James

2004-04-01

247

Elastocapillary flows in flexible tubes  

NASA Astrophysics Data System (ADS)

Interactions between capillary and elastic effects are relevant to a variety of applications from micro- and nano-scale manufacturing to biological systems. In this work, we investigate capillary flows in flexible, millimeter-scale cylindrical elastic tubes. We demonstrate that surface tension can cause sufficiently flexible tubes to collapse and coalesce spontaneously through non-axisymmetric buckling, and develop criteria for the initial deformation and complete collapse of a circular tube. Experimental results for capillary rise and evaporation of a liquid in a flexible tube are presented, and several regimes are seen for the equilibrium state of a flexible tube deforming under capillary pressure. Deformations of the tube walls are measured in different regimes and compared with a shell theory model. Analysis and experimental results show that despite the complex and non-axisymmetric deformed shapes of cylindrical structures, the elastocapillary length used in previous literature for flat plates and sheets can be used to predict the behavior of flexible tubes.

Hoberg, Theresa B.; Verneuil, Emilie; Hosoi, A. E.

2014-12-01

248

BMP receptor IA is required in mammalian neural crest cells for development of the cardiac outflow tract and ventricular myocardium  

PubMed Central

Summary The neural crest is a multipotent, migratory cell population arising from the border of the neural and surface ectoderm. In mouse, the initial migratory neural crest cells occur at the five-somite stage. Bone morphogenetic proteins (BMPs), particularly BMP2 and BMP4, have been implicated as regulators of neural crest cell induction, maintenance, migration, differentiation and survival. Mouse has three known BMP2/4 type I receptors, of which Bmpr1a is expressed in the neural tube sufficiently early to be involved in neural crest development from the outset; however, earlier roles in other domains obscure its requirement in the neural crest. We have ablated Bmpr1a specifically in the neural crest, beginning at the five-somite stage. We find that most aspects of neural crest development occur normally; suggesting that BMPRIA is unnecessary for many aspects of early neural crest biology. However, mutant embryos display a shortened cardiac outflow tract with defective septation, a process known to require neural crest cells and to be essential for perinatal viability. Surprisingly, these embryos die in mid-gestation from acute heart failure, with reduced proliferation of ventricular myocardium. The myocardial defect may involve reduced BMP signaling in a novel, minor population of neural crest derivatives in the epicardium, a known source of ventricular myocardial proliferation signals. These results demonstrate that BMP2/4 signaling in mammalian neural crest derivatives is essential for outflow tract development and may regulate a crucial proliferation signal for the ventricular myocardium. PMID:15073157

Stottmann, Rolf W.; Choi, Murim; Mishina, Yuji; Meyers, Erik N.; Klingensmith, John

2010-01-01

249

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

250

Stochastic perturbations in vortex-tube dynamics.  

PubMed

A dual lattice vortex formulation of homogeneous turbulence is developed, within the Martin-Siggia-Rose field theoretical approach. It consists of a generalization of the usual dipole version of the Navier-Stokes equations, known to hold in the limit of vanishing external forcing. We investigate, as a straightforward application of our formalism, the dynamics of closed vortex tubes, randomly stirred at large length scales by Gaussian stochastic forces. We find that besides the usual self-induced propagation, the vortex tube evolution may be effectively modeled through the introduction of an additional white-noise correlated velocity field background. The resulting phenomenological picture is closely related to observations previously reported from a wavelet decomposition analysis of turbulent flow configurations. PMID:15600755

Moriconi, L; Nobre, F A S

2004-11-01

251

Boundary cap neural crest stem cells homotopically implanted to the injured dorsal root transitional zone give rise to different types of neurons and glia in adult rodents  

PubMed Central

Background The boundary cap is a transient group of neural crest-derived cells located at the presumptive dorsal root transitional zone (DRTZ) when sensory axons enter the spinal cord during development. Later, these cells migrate to dorsal root ganglia and differentiate into subtypes of sensory neurons and glia. After birth when the DRTZ is established, sensory axons are no longer able to enter the spinal cord. Here we explored the fate of mouse boundary cap neural crest stem cells (bNCSCs) implanted to the injured DRTZ after dorsal root avulsion for their potential to assist sensory axon regeneration. Results Grafted cells showed extensive survival and differentiation after transplantation to the avulsed DRTZ. Transplanted cells located outside the spinal cord organized elongated tubes of Sox2/GFAP expressing cells closely associated with regenerating sensory axons or appeared as small clusters on the surface of the spinal cord. Other cells, migrating into the host spinal cord as single cells, differentiated to spinal cord neurons with different neurotransmitter characteristics, extensive fiber organization, and in some cases surrounded by glutamatergic terminal-like profiles. Conclusions These findings demonstrate that bNCSCs implanted at the site of dorsal root avulsion injury display remarkable differentiation plasticity inside the spinal cord and in the peripheral compartment where they organize tubes associated with regenerating sensory fibers. These properties offer a basis for exploring the ability of bNCSCs to assist regeneration of sensory axons into the spinal cord and replace lost neurons in the injured spinal cord. PMID:24884373

2014-01-01

252

Jejunostomy tube feeding in patients undergoing esophagectomy  

PubMed Central

Background Surgical jejunostomy tubes are a routine part of elective esophagectomies in patients with carcinomas and provide a route for nutritional support in those who experience complications. We wished to determine how frequently oral intake is delayed and the amount of nutrition delivered via the jejunostomy tube. Methods We reviewed the charts of all adults undergoing esophagectomy for carcinoma between January 2000 and June 2008. We determined the proportion of patients unable to resume oral nutrition after 8 days and the amount of nutrition delivered in each of the 8 days. Results In all, 111 patients underwent elective esophagectomy for carcinoma, and 103 had a jejunostomy tube placed. The mean age was 67 ± 10.8 years. The median time to oral intake was 7 (interquartile range 7–11) days. Seventy-four (67%) patients resumed oral intake within 8 days. The mean nutrition delivered by jejunostomy within the first 8 days as a percentage of the target was 45.6% (95% confidence interval 41.2%–49.9%). Six (5.4%) patients experienced complications attributable solely to the jejunostomy tube; 3 (2.9%) required surgery. Forty (38.8%) patients had abdominal issues serious enough to warrant delaying the progression of feeding. Conclusion Two-thirds of patients undergoing elective esophagectomy were tolerating oral intake by the end of the eighth postoperative day, and less than half of the target nutrition was delivered over the first 8 days. We now selectively place surgical jejunostomy tubes in patients undergoing elective esophagectomies. PMID:24284149

Srinathan, Sadeesh K.; Hamin, Tamara; Walter, Stephen; Tan, A. Lawrence; Unruh, Helmut W.; Guyatt, Gordon

2013-01-01

253

Signal dispersion within a hippocampal neural network  

NASA Technical Reports Server (NTRS)

A model network is described, representing two neural populations coupled so that one population is inhibited by activity it excites in the other. Parameters and operations within the model represent EPSPs, IPSPs, neural thresholds, conduction delays, background activity and spatial and temporal dispersion of signals passing from one population to the other. Simulations of single-shock and pulse-train driving of the network are presented for various parameter values. Neuronal events from 100 to 300 msec following stimulation are given special consideration in model calculations.

Horowitz, J. M.; Mates, J. W. B.

1975-01-01

254

Evolvable Neural Software System  

NASA Technical Reports Server (NTRS)

The Evolvable Neural Software System (ENSS) is composed of sets of Neural Basis Functions (NBFs), which can be totally autonomously created and removed according to the changing needs and requirements of the software system. The resulting structure is both hierarchical and self-similar in that a given set of NBFs may have a ruler NBF, which in turn communicates with other sets of NBFs. These sets of NBFs may function as nodes to a ruler node, which are also NBF constructs. In this manner, the synthetic neural system can exhibit the complexity, three-dimensional connectivity, and adaptability of biological neural systems. An added advantage of ENSS over a natural neural system is its ability to modify its core genetic code in response to environmental changes as reflected in needs and requirements. The neural system is fully adaptive and evolvable and is trainable before release. It continues to rewire itself while on the job. The NBF is a unique, bilevel intelligence neural system composed of a higher-level heuristic neural system (HNS) and a lower-level, autonomic neural system (ANS). Taken together, the HNS and the ANS give each NBF the complete capabilities of a biological neural system to match sensory inputs to actions. Another feature of the NBF is the Evolvable Neural Interface (ENI), which links the HNS and ANS. The ENI solves the interface problem between these two systems by actively adapting and evolving from a primitive initial state (a Neural Thread) to a complicated, operational ENI and successfully adapting to a training sequence of sensory input. This simulates the adaptation of a biological neural system in a developmental phase. Within the greater multi-NBF and multi-node ENSS, self-similar ENI s provide the basis for inter-NBF and inter-node connectivity.

Curtis, Steven A.

2009-01-01

255

Resolving time and space constraints during neural crest formation and delamination.  

PubMed

A striking feature of neural crest development in vertebrates is that all the specification, delamination, migration, and differentiation steps occur consecutively in distinct areas of the embryo and at different timings of development. The significance and consequences of this partition into clearly separated events are not fully understood yet, but it ought to be related to the necessity of controlling precisely and independently each step, given the wide array of cell types and tissues derived from the neural crest and the long duration of their development spanning almost the entire embryonic life. In this chapter, using the examples of early neural crest induction and delamination, we discuss how time and space constraints influence their development and describe the molecular and cellular responses that are employed by cells to adapt. In the first example, we analyze how cell sorting and cell movements cooperate to allow nascent neural crest cells, which are initially mingled with other neurectodermal progenitors after induction, to segregate from the neural tube and ectoderm populations and settle at the apex of the neural tube prior to migration. In the second example, we examine how cadherins drive the entire process of neural crest segregation from the rest of the neurectoderm by their dual role in mediating first cell sorting and cohesion during specification and later in promoting their delamination. In the third example, we describe how the expression and activity of the transcription factors known to drive epithelium-to-mesenchyme transition (EMT) are regulated timely and spatially by the cellular machinery so that they can alternatively and successively regulate neural crest specification and delamination. In the last example, we briefly tackle the problem of how factors triggering EMT may elicit different cell responses in neural tube and neural crest progenitors. PMID:25662257

Duband, Jean-Loup; Dady, Alwyn; Fleury, Vincent

2015-01-01

256

RBMK pressure tube rupture assessment  

SciTech Connect

The Russian RBMK reactor core design consists of multiple parallel pressure tube channels that contain Zr clad, UO{sub 2} fuel pin bundles. These parallel channels are contained within graphite moderator blocks which are, in turn, contained within a sealed core cavity. Current safety evaluation efforts of the RBMK reactors have been concentrating in the area of tube ruptures within the core cavity and, in particular, multiple tube ruptures that could threaten the reactor core integrity. Tube rupture events result in a pressurization of the reactor core cavity. The original design overpressure for the cavity region was based on a single tube rupture, resulting in considerable margin to the top plate lift pressure. The top plate lift pressure is 3.1 bar, and a single tube rupture would result in approximately 1.4 bar. RBMK plant specific cavity pressure relief designs provide for between three and in simultaneous tube ruptures before exceeding the top plate lift pressure. Thus, current safety evaluations have begun to examine the potential for multiple tube ruptures that could exceed the current cavity pressure relief designs. One such scenario being examined is a partial rupture in a group distribution header that results in stagnated (low) flow to up to 40 pressure tubes. The subsequent fuel heatup in these reduced flow tubes could result in multiple tube ruptures beyond the design relief capacity of the core cavity. This paper examines several key issues in evaluating this transient, including: (1) the effects of low flow, (2) the effects of axial peaking, and (3) the effects of radial peaking, all relative to the time to tube rupture. These issues each play a significant role in attempting to evaluate the likelihood and severity of multiple tube ruptures for a partial group distribution header break.

Schmitt, B.E.; Tsiklauri, G.V.

1994-08-01

257

Tube thoracostomy; chest tube implantation and follow up.  

PubMed

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; Zarogoulidis, Paul

2014-10-01

258

DNA methyltransferase 3B regulates duration of neural crest production via repression of Sox10.  

PubMed

Neural crest stem cells arise within the central nervous system but then undergo an epithelial-to-mesenchymal transition to migrate away and contribute to the peripheral nervous system and craniofacial skeleton. Here we show that DNA methyltransferase 3B (DNMT3B) is responsible for the loss of competence of dorsal neural tube cells to generate emigrating neural crest cells. DNMT3B knockdown results in up-regulation of neural crest markers, prolonged neural crest emigration, and subsequent precocious neuronal differentiation of the trigeminal ganglion. We find that DNMT3B binds to the promoter of Sox10, known to be important for neural crest emigration and lineage acquisition. Bisulfite sequencing further reveals methylation of the Sox10 promoter region upon cessation of emigration in normal embryos, whereas this mark is reduced after DNMT3B loss. Taken together, these results reveal the importance of DNA methylation in regulating the ability of neural tube cells to produce neural crest cells and the timing of peripheral neuron differentiation. PMID:25453070

Hu, Na; Strobl-Mazzulla, Pablo H; Simoes-Costa, Marcos; Sánchez-Vásquez, Estefania; Bronner, Marianne E

2014-12-16

259

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

260

The Cosmic Background Explorer.  

ERIC Educational Resources Information Center

Outlines the Cosmic Background Explorer (COBE) mission to measure celestial radiation. Describes the instruments used and experiments involving differential microwave radiometers, and a far infrared absolute spectrophotometer. (YP)

Gulkis, Samuel; And Others

1990-01-01

261

Fuzzy and neural control  

NASA Technical Reports Server (NTRS)

Fuzzy logic and neural networks provide new methods for designing control systems. Fuzzy logic controllers do not require a complete analytical model of a dynamic system and can provide knowledge-based heuristic controllers for ill-defined and complex systems. Neural networks can be used for learning control. In this chapter, we discuss hybrid methods using fuzzy logic and neural networks which can start with an approximate control knowledge base and refine it through reinforcement learning.

Berenji, Hamid R.

1992-01-01

262

Massively parallel neural computation  

E-print Network

and communication resources is developed and then used to implement a neural computation system on the multi- FPGA platform. Finding suitable benchmark neural networks for a massively parallel neural com- putation system proves to be a challenge. A synthetic... .2.4 Accumulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113 7.2.5 Memory spike source . . . . . . . . . . . . . . . . . . . . . . . 116 7.2.6 Spike injector . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117 7.2.7 Spike auditor...

Fox, Paul James

2013-03-12

263

Effect of Blood Collection Tubes on Total Triiodothyronine and Other Laboratory Assays  

Microsoft Academic Search

Background: Increased total triiodothyronine (TT3) as- say results in apparently euthyroid patients triggered an investigation of the effect of blood collection tubes on serum TT3 and other laboratory assays. Methods: We examined potential assay interference for three types of tubes: plastic Greiner Bio-OneTM VacuetteTM; glass Becton Dickinson (BD) VacutainerTM; and plastic BD Vacutainer SSTTM tubes. Serum samples from apparently healthy

Raffick A. R. Bowen; Yung Chan; Joshua Cohen; Nadja N. Rehak; Glen L. Hortin; Gyorgy Csako; Alan T. Remaley

264

Quality improvement of oral medication administration in patients with enteral feeding tubes  

Microsoft Academic Search

Background: The correct administration of oral drugs to patients on enteral tube feeding presents a special\\u000achallenge. As patients are usually unable to swallow oral drugs and many drugs should not be crushed,\\u000aways have to be found to administer them through the feeding tube. Measures to improve the quality of\\u000aoral drug administration in patients with enteral feeding tubes

P. M. L. A. van den Bemt; M. B. I. Cusell; P. W. Overbeeke; M. T. G. Trommelen; D. van Dooren; W. R. Ophorst; A. C. G. Egberts

2006-01-01

265

Valved pulse tube refrigerator development  

NASA Astrophysics Data System (ADS)

The pulse tube refrigerator is inherently reliable since it contains no moving parts at low temperature. However, the performance of a simple pulse tube is typically lower than that of other cryocoolers both in terms of COP and temperature differential per stage. Recent work indicates that the valved pulse tube, otherwise known as the orifice pulse tube, is able to reach much lower temperatures than the simple design, 31 K having been achieved in a two stage device. The addition of the valve and buffer volume subtly alters the heat pumping mechanism in the pulse tube. The valved pulse tube is described and the nature of the heat pumping machine explained. The current status of the device is reviewed.

Richardson, R. N.

266

Angiogenesis in the developing spinal cord: blood vessel exclusion from neural progenitor region is mediated by VEGF and its antagonists.  

PubMed

Blood vessels in the central nervous system supply a considerable amount of oxygen via intricate vascular networks. We studied how the initial vasculature of the spinal cord is formed in avian (chicken and quail) embryos. Vascular formation in the spinal cord starts by the ingression of intra-neural vascular plexus (INVP) from the peri-neural vascular plexus (PNVP) that envelops the neural tube. At the ventral region of the PNVP, the INVP grows dorsally in the neural tube, and we observed that these vessels followed the defined path at the interface between the medially positioned and undifferentiated neural progenitor zone and the laterally positioned differentiated zone. When the interface between these two zones was experimentally displaced, INVP faithfully followed a newly formed interface, suggesting that the growth path of the INVP is determined by surrounding neural cells. The progenitor zone expressed mRNA of vascular endothelial growth factor-A whereas its receptor VEGFR2 and FLT-1 (VEGFR1), a decoy for VEGF, were expressed in INVP. By manipulating the neural tube with either VEGF or the soluble form of FLT-1, we found that INVP grew in a VEGF-dependent manner, where VEGF signals appear to be fine-tuned by counteractions with anti-angiogenic activities including FLT-1 and possibly semaphorins. These results suggest that the stereotypic patterning of early INVP is achieved by interactions between these vessels and their surrounding neural cells, where VEGF and its antagonists play important roles. PMID:25585380

Takahashi, Teruaki; Takase, Yuta; Yoshino, Takashi; Saito, Daisuke; Tadokoro, Ryosuke; Takahashi, Yoshiko

2015-01-01

267

Angiogenesis in the Developing Spinal Cord: Blood Vessel Exclusion from Neural Progenitor Region Is Mediated by VEGF and Its Antagonists  

PubMed Central

Blood vessels in the central nervous system supply a considerable amount of oxygen via intricate vascular networks. We studied how the initial vasculature of the spinal cord is formed in avian (chicken and quail) embryos. Vascular formation in the spinal cord starts by the ingression of intra-neural vascular plexus (INVP) from the peri-neural vascular plexus (PNVP) that envelops the neural tube. At the ventral region of the PNVP, the INVP grows dorsally in the neural tube, and we observed that these vessels followed the defined path at the interface between the medially positioned and undifferentiated neural progenitor zone and the laterally positioned differentiated zone. When the interface between these two zones was experimentally displaced, INVP faithfully followed a newly formed interface, suggesting that the growth path of the INVP is determined by surrounding neural cells. The progenitor zone expressed mRNA of vascular endothelial growth factor-A whereas its receptor VEGFR2 and FLT-1 (VEGFR1), a decoy for VEGF, were expressed in INVP. By manipulating the neural tube with either VEGF or the soluble form of FLT-1, we found that INVP grew in a VEGF-dependent manner, where VEGF signals appear to be fine-tuned by counteractions with anti-angiogenic activities including FLT-1 and possibly semaphorins. These results suggest that the stereotypic patterning of early INVP is achieved by interactions between these vessels and their surrounding neural cells, where VEGF and its antagonists play important roles. PMID:25585380

Takahashi, Teruaki; Takase, Yuta; Yoshino, Takashi; Saito, Daisuke; Tadokoro, Ryosuke; Takahashi, Yoshiko

2015-01-01

268

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

269

Improved Mechanical Seals For Tubes  

NASA Technical Reports Server (NTRS)

Improved tube-to-fitting seals made by application of soft metal pieces to either ends of tubes or to interior of fittings. Metal silver, gold, platinum, tin, or other easily malleable metal selected to be inert with fluid of use. Metal plated, evaporated, or sputter-deposited. Coat of soft metal thin, so no changes required in design or tolerances of standard fittings. Technique suitable for hydraulic or other fluid systems in which leakage from mechanically joined sections of tubes occur.

Babel, Henry W.; Anderson, Raymond H.; Fuson, Phillip L.; Chickles, Colin D.; Jones, Cherie A.

1996-01-01

270

YouTube Sharathon Crackerbarrel  

NASA Astrophysics Data System (ADS)

This year at the AAPT Summer Meeting in Philadelphia, there was a session called "YouTube Sharathon Crackerbarrel." The session allowed many teachers to share their YouTube videos and explain how they use YouTube in their classroom. Unfortunately, I had a conflicting meeting and had to miss this session. Dean Baird was the originator of the session and also served as host. In addition, he forwarded a few of the best videos to me.

2012-10-01

271

YouTube Sharathon Crackerbarrel  

NASA Astrophysics Data System (ADS)

This year at the AAPT Summer Meeting in Philadelphia, there was a session called ``YouTube Sharathon Crackerbarrel.'' The session allowed many teachers to share their YouTube videos and explain how they use YouTube in their classroom. Unfortunately, I had a conflicting meeting and had to miss this session. Dean Baird was the originator of the session and also served as host. In addition, he forwarded a few of the best videos to me.

Riendeau, Diane

2012-10-01

272

A neural plate fate map at stage HH4 in the chick: methodology and preliminary data  

Microsoft Academic Search

This paper centers on the design of a perfected methodology for establishing a fate map of the chick neural plate at stages 3d\\/4, projected upon the closing neural tube (stages 9–11). The principal aim was to saturate the area of interest with overlapping small isochronic and homotopic grafts (100–300 cells), in order to later derive firmer conclusions from the detailed

P Fernández-Garre; L Rodr??guez-Gallardo; I. Santiago Alvarez; Luis Puelles

2002-01-01

273

Background music reactive games  

Microsoft Academic Search

In this paper, we discuss the concept of games that react to their background music. Instead of limiting the player to a fixed set of songs, the background music can be any song chosen from the player's own music collection. Due to the relative simplicity of such existing game titles, we wanted to explore the potential of the concept more

Juha Arrasvuori; Jukka Holm

2010-01-01

274

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

275

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

276

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

277

Correlators in nontrivial backgrounds  

SciTech Connect

Operators in N=4 super Yang-Mills theory with an R-charge of O(N{sup 2}) are dual to backgrounds which are asymtotically AdS{sub 5}xS{sup 5}. In this article we develop efficient techniques that allow the computation of correlation functions in these backgrounds. We find that (i) contractions between fields in the string words and fields in the operator creating the background are the field theory accounting of the new geometry, (ii) correlation functions of probes in these backgrounds are given by the free field theory contractions but with rescaled propagators and (iii) in these backgrounds there are no open string excitations with their special end point interactions; we have only closed string excitations.

Mello Koch, Robert de [National Institute for Theoretical Physics, Department of Physics and Centre for Theoretical Physics, University of the Witwatersrand, Wits, 2050 (South Africa); Stellenbosch Institute for Advanced Studies, Stellenbosch (South Africa); Ives, Norman; Stephanou, Michael [National Institute for Theoretical Physics, Department of Physics and Centre for Theoretical Physics, University of the Witwatersrand, Wits, 2050 (South Africa)

2009-01-15

278

A novel role for MuSK and non-canonical Wnt signaling during segmental neural crest cell migration  

PubMed Central

Trunk neural crest cells delaminate from the dorsal neural tube as an uninterrupted sheet; however, they convert into segmentally organized streams before migrating through the somitic territory. These neural crest cell streams join the segmental trajectories of pathfinding spinal motor axons, suggesting that interactions between these two cell types might be important for neural crest cell migration. Here, we show that in the zebrafish embryo migration of both neural crest cells and motor axons is temporally synchronized and spatially restricted to the center of the somite, but that motor axons are dispensable for segmental neural crest cell migration. Instead, we find that muscle-specific receptor kinase (MuSK) and its putative ligand Wnt11r are crucial for restricting neural crest cell migration to the center of each somite. Moreover, we find that blocking planar cell polarity (PCP) signaling in somitic muscle cells also results in non-segmental neural crest cell migration. Using an F-actin biosensor we show that in the absence of MuSK neural crest cells fail to retract non-productive leading edges, resulting in non-segmental migration. Finally, we show that MuSK knockout mice display similar neural crest cell migration defects, suggesting a novel, evolutionarily conserved role for MuSK in neural crest migration. We propose that a Wnt11r-MuSK dependent, PCP-like pathway restricts neural crest cells to their segmental path. PMID:21750038

Banerjee, Santanu; Gordon, Laura; Donn, Thomas M.; Berti, Caterina; Moens, Cecilia B.; Burden, Steven J.; Granato, Michael

2011-01-01

279

Neural Crest and Olfactory System: New Prospective  

PubMed Central

Sensory neurons in vertebrates are derived from two embryonic transient cell sources: neural crest (NC) and ectodermal placodes. The placodes are thickenings of ectodermal tissue that are responsible for the formation of cranial ganglia as well as complex sensory organs that include the lens, inner ear, and olfactory epithelium. The NC cells have been indicated to arise at the edges of the neural plate/dorsal neural tube, from both the neural plate and the epidermis in response to reciprocal interactions Moury and Jacobson (Dev Biol 141:243–253, 1990). NC cells migrate throughout the organism and give rise to a multitude of cell types that include melanocytes, cartilage and connective tissue of the head, components of the cranial nerves, the dorsal root ganglia, and Schwann cells. The embryonic definition of these two transient populations and their relative contribution to the formation of sensory organs has been investigated and debated for several decades (Basch and Bronner-Fraser, Adv Exp Med Biol 589:24–31, 2006; Basch et al., Nature 441:218–222, 2006) review (Baker and Bronner-Fraser, Dev Biol 232:1–61, 2001). Historically, all placodes have been described as exclusively derived from non-neural ectodermal progenitors. Recent genetic fate-mapping studies suggested a NC contribution to the olfactory placodes (OP) as well as the otic (auditory) placodes in rodents (Murdoch and Roskams, J NeurosciOff J Soc Neurosci 28:4271–4282, 2008; Murdoch et al., J Neurosci 30:9523–9532, 2010; Forni et al., J Neurosci Off J Soc Neurosci 31:6915–6927, 2011b; Freyer et al., Development 138:5403–5414, 2011; Katoh et al., Mol Brain 4:34, 2011). This review analyzes and discusses some recent developmental studies on the OP, placodal derivatives, and olfactory system. PMID:22773137

Forni, Paolo E.

2013-01-01

280

Effect of tube size on electromagnetic tube bulging  

Microsoft Academic Search

The commercial finite code ANSYS was employed for the simulation of the electromagnetic tube bulging process. The finite element model and boundary conditions were thoroughly discussed. ANSYS\\/EMAG was used to model the time varying electromagnetic field in order to obtain the radial and axial magnetic pressure acting on the tube. The magnetic pressure was then used as boundary conditions to

Zhong LI; Chun-feng LI; Hai-ping YU; Zhi-heng ZHAO

2007-01-01

281

Primary Fallopian Tube Carcinoma Arising in the Setting of Chronic Pelvic Inflammatory Disease  

PubMed Central

Primary fallopian tube cancer (PFTC) is a rare gynaecological malignancy, clinically often mistaken for pelvic inflammatory disease or ovarian cancer. Three primary fallopian tube carcinomas, arising in a background of chronic pelvic inflammatory disease (PID), are presented. The possible association between chronic PID and PFTC is discussed and a hypothesies linking these cancers with chronic inflammation is proposed. PMID:24527040

Zardawi, Ibrahim M.

2014-01-01

282

COPI Vesicle Transport Is a Common Requirement for Tube Expansion in Drosophila  

Microsoft Academic Search

BackgroundTube expansion defects like stenoses and atresias cause devastating human diseases. Luminal expansion during organogenesis begins to be elucidated in several systems but we still lack a mechanistic view of the process in many organs. The Drosophila tracheal respiratory system provides an amenable model to study tube size regulation. In the trachea, COPII anterograde transport of luminal proteins is required

Satish Arcot Jayaram; Kirsten-André Senti; Katarína Tiklová; Vasilios Tsarouhas; Johanna Hemphälä; Christos Samakovlis; Francois Schweisguth

2008-01-01

283

Beta-actin is required for proper mouse neural crest ontogeny.  

PubMed

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

284

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

285

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

286

The cosmic neutrino background  

NASA Technical Reports Server (NTRS)

The cosmic neutrino background is expected to consist of relic neutrinos from the big bang, of neutrinos produced during nuclear burning in stars, of neutrinos released by gravitational stellar collapse, and of neutrinos produced by cosmic ray interactions with matter and radiation in the interstellar and intergalactic medium. Formation of baryonic dark matter in the early universe, matter-antimatter annihilation in a baryonic symmetric universe, and dark matter annihilation could have also contributed significantly to the cosmic neutrino background. The purpose of this paper is to review the properties of these cosmic neutrino backgrounds, the indirect evidence for their existence, and the prospects for their detection.

Dar, Arnon

1991-01-01

287

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

288

Supplementary Methods Neural recordings  

E-print Network

Supplementary Methods Neural recordings Neural recordings were made using Pt/Ir electrodes for a minimum of 100 trials per search task were included in the database regardless of task response. Another database of recordings was obtained during the centre-out task using the same procedure. Recordings during

Andersen, Richard

289

Forming tool improves quality of tubing flares  

NASA Technical Reports Server (NTRS)

Punch and die set improves the quality of tubing flares for use with standard flared-tube fittings in high-pressure systems. It forges a dimensionally accurate flare in the tubing and forces more tubing material into the high-stress areas to improve the strength and tightness of the tubing connection.

1966-01-01

290

ATLAS Muon Drift Tube Electronics  

Microsoft Academic Search

This paper describes the electronics used for the ATLAS monitored drift tube (MDT) chambers. These chambers are the main component of the precision tracking system in the ATLAS muon spectrometer. The MDT detector system consists of 1,150 chambers containing a total of 354,000 drift tubes. It is capable of measuring the sagitta of muon tracks to an accuracy of 60

Y. Arai; B. Ball; M. Beretta; H. Boterenbrood; G. W. Brandenburg; F. Ceradini; J. W. Chapman; T. Dai; C. Ferretti; T. Fries; J. Gregory; J. Guimarães da Costa; S. Harder; E. Hazen; J. Huth; P. P. M. Jansweijer; L. E. Kirsch; A. C. König; A. Lanza; G. Mikenberg; J. Oliver; C. Posch; R. Richter; W. Riegler; E. Spiriti; F. E. Taylor; J. C. Vermeulen; B. Wadsworth; T. A. M. Wijnen

2008-01-01

291

Alameda Tubes seismic retrofit studies  

Microsoft Academic Search

As a part of the Posey and Webster Street Tubes seismic retrofit project, finite element analysis was used to study the soil–structure interaction behavior due to earthquake ground motions. This paper summarizes the nonlinear analysis activities for the Alameda Tubes. The overall objective of these studies was to estimate the responses of the as-built and retrofit configurations of the Posey

Alexander Kozak; Hassan Sedarat; Alex Krimotat

1999-01-01

292

Aluminum foil lined composite tubing  

NASA Astrophysics Data System (ADS)

This paper describes the development of lightweight aluminum foil lined polymer matrix composite tubing for applications ranging from heat pipe construction to fluid transport tubing and tankage structure for future spacecraft. The metal lining is completely hermetic and endows the tubing with metal like characteristics without compromising its lightweight or strength advantages. It consists of one wrap of 0.076 mm thick aluminum foil that is rolled in a cylindrical shape and seam welded. Each end of the foil tube transitions to a short section of heavy wall aluminum tubing that is welded to the foil tube creating a leak tight lining. Composite fibers are braided over the lining and then resin transfer molded. The epoxy resin bonds to the fibers and to the lining, forming an integral tube. The demonstration tubing that was constructed was 25.4 mm in diameter, 4.57 m long and had an average mass per unit length of 0.131 kg/m. Extension of this technology to other metal lining materials for containment of various fluids is feasible.

Gernert, Nelson J.; Sarraf, David B.; Armstrong, Douglas L.; Blood, Scott A.

1996-03-01

293

Hot window, metal vapor tube  

Microsoft Academic Search

A new quartz laser tube, which can operate at 1000°C for metal vapors, has been built. The tube was operated in a three-zone oven, with the Brewster windows at a slightly higher temperature than the main laser body. Thus, a buffer gas was not necessary to prevent condensation of the metal on the windows. A technique for fusing the quartz

D. E. Altman; G. J. Barstow; M. Geller; G. Mooradian; C. Ingram; G. T. Andry

1975-01-01

294

Helical Tubes in Crowded Environments  

E-print Network

When placed in a crowded environment, a semi-flexible 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 semi-flexible tube that minimize the excluded volume. We focus most of our attention on the helix and which helical geometries are most compact. We found that 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.

Yehuda Snir; Randall D. Kamien

2006-12-11

295

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

296

Tubes at Glen Canyon Dam  

USGS Multimedia Gallery

The river outlet tubes at Glen Canyon Dam on the Colorado River in Arizona. At noon Monday, Nov. 19, U.S. Interior Secretary Ken Salazar will open the dam's river outlet tubes, releasing controlled flows larger than the usual 8,000-25,000 cubic feet per second that flows through the turbines of...

297

Does Tube Feeding Prevent Pneumonia?  

Microsoft Academic Search

The use of artificial nutrition and hydration in elderly patients with severe dementia is common under hospice care. This topic will become increasingly important as the prevalence of dementia rises and population ages. Interrupting the cycle of feeding, aspiration and subsequent pneumonia is one of the most commonly cited reasons for using the feeding tube. Use of feeding tubes to

K Kejriwal

298

Differentiation between non-neural and neural contributors to ankle joint stiffness in cerebral palsy  

PubMed Central

Background Spastic paresis in cerebral palsy (CP) is characterized by increased joint stiffness that may be of neural origin, i.e. improper muscle activation caused by e.g. hyperreflexia or non-neural origin, i.e. altered tissue viscoelastic properties (clinically: “spasticity” vs. “contracture”). Differentiation between these components is hard to achieve by common manual tests. We applied an assessment instrument to obtain quantitative measures of neural and non-neural contributions to ankle joint stiffness in CP. Methods Twenty-three adolescents with CP and eleven healthy subjects were seated with their foot fixated to an electrically powered single axis footplate. Passive ramp-and-hold rotations were applied over full ankle range of motion (RoM) at low and high velocities. Subject specific tissue stiffness, viscosity and reflexive torque were estimated from ankle angle, torque and triceps surae EMG activity using a neuromuscular model. Results In CP, triceps surae reflexive torque was on average 5.7 times larger (p?=?.002) and tissue stiffness 2.1 times larger (p?=?.018) compared to controls. High tissue stiffness was associated with reduced RoM (p?neural and non-neural contributors varied substantially within adolescents with CP. Significant associations of SPAT (spasticity test) score with both tissue stiffness and reflexive torque show agreement with clinical phenotype. Conclusions Using an instrumented and model based approach, increased joint stiffness in CP could be mainly attributed to higher reflexive torque compared to control subjects. Ratios between contributors varied substantially within adolescents with CP. Quantitative differentiation of neural and non-neural stiffness contributors in CP allows for assessment of individual patient characteristics and tailoring of therapy. PMID:23880287

2013-01-01

299

The GLAST Background Model  

NASA Astrophysics Data System (ADS)

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.; Atwood, W.; Burnett, T.; Grove, E.; Longo, F.; McEnery, J.; Mizuno, T.; Ritz, S.

2007-07-01

300

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

301

IR-background database  

Microsoft Academic Search

The Swedish Defence Research Agency (FOI) has recently performed systematic measurements in order to establish an IR-background database. It will be used for a wide range of applications and provide a basis for the modeling of IR-background properties of Swedish terrain. Experimental data like this is also necessary for the validation of methods and programs for synthetic IR-scene simulation. The

Claes Nelsson; Paer Nilsson; Roland Lindell; Emma Bernhardsson

2001-01-01

302

Neural constraints on learning.  

PubMed

Learning, whether motor, sensory or cognitive, requires networks of neurons to generate new activity patterns. As some behaviours are easier to learn than others, we asked if some neural activity patterns are easier to generate than others. Here we investigate whether an existing network constrains the patterns that a subset of its neurons is capable of exhibiting, and if so, what principles define this constraint. We employed a closed-loop intracortical brain-computer interface learning paradigm in which Rhesus macaques (Macaca mulatta) controlled a computer cursor by modulating neural activity patterns in the primary motor cortex. Using the brain-computer interface paradigm, we could specify and alter how neural activity mapped to cursor velocity. At the start of each session, we observed the characteristic activity patterns of the recorded neural population. The activity of a neural population can be represented in a high-dimensional space (termed the neural space), wherein each dimension corresponds to the activity of one neuron. These characteristic activity patterns comprise a low-dimensional subspace (termed the intrinsic manifold) within the neural space. The intrinsic manifold presumably reflects constraints imposed by the underlying neural circuitry. Here we show that the animals could readily learn to proficiently control the cursor using neural activity patterns that were within the intrinsic manifold. However, animals were less able to learn to proficiently control the cursor using activity patterns that were outside of the intrinsic manifold. These results suggest that the existing structure of a network can shape learning. On a timescale of hours, it seems to be difficult to learn to generate neural activity patterns that are not consistent with the existing network structure. These findings offer a network-level explanation for the observation that we are more readily able to learn new skills when they are related to the skills that we already possess. PMID:25164754

Sadtler, Patrick T; Quick, Kristin M; Golub, Matthew D; Chase, Steven M; Ryu, Stephen I; Tyler-Kabara, Elizabeth C; Yu, Byron M; Batista, Aaron P

2014-08-28

303

New genes in the evolution of the neural crest differentiation program  

PubMed Central

Background Development of the vertebrate head depends on the multipotency and migratory behavior of neural crest derivatives. This cell population is considered a vertebrate innovation and, accordingly, chordate ancestors lacked neural crest counterparts. The identification of neural crest specification genes expressed in the neural plate of basal chordates, in addition to the discovery of pigmented migratory cells in ascidians, has challenged this hypothesis. These new findings revive the debate on what is new and what is ancient in the genetic program that controls neural crest formation. Results To determine the origin of neural crest genes, we analyzed Phenotype Ontology annotations to select genes that control the development of this tissue. Using a sequential blast pipeline, we phylogenetically classified these genes, as well as those associated with other tissues, in order to define tissue-specific profiles of gene emergence. Of neural crest genes, 9% are vertebrate innovations. Our comparative analyses show that, among different tissues, the neural crest exhibits a particularly high rate of gene emergence during vertebrate evolution. A remarkable proportion of the new neural crest genes encode soluble ligands that control neural crest precursor specification into each cell lineage, including pigmented, neural, glial, and skeletal derivatives. Conclusion We propose that the evolution of the neural crest is linked not only to the recruitment of ancestral regulatory genes but also to the emergence of signaling peptides that control the increasingly complex lineage diversification of this plastic cell population. PMID:17352807

2007-01-01

304

Epigenetic regulation of neural stem cell fate during corticogenesis.  

PubMed

The cerebral cortex comprises over three quarters of the brain, and serves as structural basis for the sophisticated perceptual and cognitive functions. It develops from common multipotent neural stem cells (NSCs) that line the neural tube. Development of the NSCs encompasses sequential phases of progenitor expansion, neurogenesis, and gliogenesis along with the progression of developmental stages. Interestingly, NSCs steadfastly march through all of these phases and give rise to specific neural cell types in a temporally defined and highly predictable manner. Herein, we delineate the intrinsic and extrinsic factors that dictate the progression and tempo of NSC differentiation during cerebral cortex development, and how epigenetic modifications contribute to the dynamic properties of NSCs. PMID:23466416

MuhChyi, Chai; Juliandi, Berry; Matsuda, Taito; Nakashima, Kinichi

2013-10-01

305

Neural-mesodermal progenitor interactions in pattern formation: an introduction to the collection  

PubMed Central

Mesodermal and spinal cord progenitors originate from common founder cells from which they segregate during development. Moreover, neural and mesodermal tissues closely interact during embryogenesis to ensure timely patterning and differentiation of both head and trunk structures. For instance, the fate and morphogenesis of neural progenitors is dependent on signals produced by mesodermal cells and vice-versa. While some of the cellular and molecular signals that mediate these interactions have been described, much more remains to be uncovered. The scope of this collection will cover these interactions between neural (CNS or PNS) and mesodermal progenitors in patterning body plans and specific body systems in vertebrate embryos. This includes, but is not limited to, interactions influencing the formation of body axes, neural tube formation, neural crest migration, gut development, muscle patterning and myogenesis. PMID:25580236

Kalcheim, Chaya; Storey, Kate G.

2014-01-01

306

Higgs Search at LHC by Neural Networks  

Microsoft Academic Search

We present an attempt to identify two Higgs boson processes (pp-->HX-->W+W-X-->l+nul-nuX and pp-->HX-->tt¯X-->4muX) from backgrounds, by using the discriminant analysis and neural networks methods. Events were produced at LHC energies, using the PYTHIA 6.1 Monte Carlo generator, in the Higgs mass range 115

Mostafa Mjahed

2005-01-01

307

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

308

Neural progenitor cells treated with EPO induce angiogenesis through the production of VEGF  

PubMed Central

Recombinant human erythropoietin (rhEPO) induces neurogenesis and angiogenesis. Using a coculture system of mouse brain endothelial cells (MBECs) and neural progenitor cells derived from the subventricular zone of adult mouse, we investigated the hypothesis that neural progenitor cells treated with rhEPO promote angiogenesis. Treatment of neural progenitor cells with rhEPO significantly increased their expression and secretion of vascular endothelial growth factor (VEGF) and activated phosphatidylinositol 3-kinase/Akt (PI3K/Akt) and extracellular signal-regulated kinase (ERK1/2). Selective inhibition of the Akt and ERK1/2 signaling pathways significantly attenuated the rhEPO-induced VEGF expression in neural progenitor cells. The supernatant harvested from neural progenitor cells treated with rhEPO significantly increased the capillary-like tube formation of MBECs. SU1498, a specific VEGF type-2 receptor (VEGFR2) antagonist, abolished the supernatant-enhanced angiogenesis. In addition, coculture of MBECs with neural progenitor cells treated with rhEPO substantially increased VEGFR2 mRNA and protein levels in MBECs. These in vitro results suggest that EPO enhances VEGF secretion in neural progenitor cells through activation of the PI3K/Akt and ERK1/2 signaling pathways and that neural progenitor cells treated with rhEPO upregulate VEGFR2 expression in cerebral endothelial cells, which along with VEGF secreted by neural progenitor cells promotes angiogenesis. PMID:18414495

Wang, Lei; Chopp, Michael; Gregg, Sara R; Zhang, Rui Lan; Teng, Hua; Jiang, Angela; Feng, Yifan; Zhang, Zheng Gang

2014-01-01

309

CD133 (Prominin) Negative Human Neural Stem Cells Are Clonogenic and Tripotent  

Microsoft Academic Search

BackgroundCD133 (Prominin) is widely used as a marker for the identification and isolation of neural precursor cells from normal brain or tumor tissue. However, the assumption that CD133 is expressed constitutively in neural precursor cells has not been examined.Methodology\\/Principal FindingsIn this study, we demonstrate that CD133 and a second marker CD15 are expressed heterogeneously in uniformly undifferentiated human neural stem

Yirui Sun; Weiqing Kong; Anna Falk; Jin Hu; Liangfu Zhou; Steve Pollard; Austin Smith; Alain Chédotal

2009-01-01

310

Dynamics of neural cryptography  

SciTech Connect

Synchronization of neural networks has been used for public channel protocols in cryptography. In the case of tree parity machines the dynamics of both bidirectional synchronization and unidirectional learning is driven by attractive and repulsive stochastic forces. Thus it can be described well by a random walk model for the overlap between participating neural networks. For that purpose transition probabilities and scaling laws for the step sizes are derived analytically. Both these calculations as well as numerical simulations show that bidirectional interaction leads to full synchronization on average. In contrast, successful learning is only possible by means of fluctuations. Consequently, synchronization is much faster than learning, which is essential for the security of the neural key-exchange protocol. However, this qualitative difference between bidirectional and unidirectional interaction vanishes if tree parity machines with more than three hidden units are used, so that those neural networks are not suitable for neural cryptography. In addition, the effective number of keys which can be generated by the neural key-exchange protocol is calculated using the entropy of the weight distribution. As this quantity increases exponentially with the system size, brute-force attacks on neural cryptography can easily be made unfeasible.

Ruttor, Andreas; Kinzel, Wolfgang; Kanter, Ido [Institut fuer Theoretische Physik, Universitaet Wuerzburg, Am Hubland, 97074 Wuerzburg (Germany); Minerva Center and Department of Physics, Bar Ilan University, Ramat Gan 52900 (Israel)

2007-05-15

311

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

312

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

313

Failure in internally pressurized bent tubes  

Microsoft Academic Search

The analysis and modeling of tube-hydroformed components is more complicated than that employed for sheet-metal panels, due\\u000a to the lengthier process sequence and variable strain path—from flat-rolled sheet to tube; from straight tube to bent tube;\\u000a and from bent tube to hydroformed component. These additional process steps make it difficult to determine whether post mortem analyses of tube failure during

Robin Stevenson; Boon-Chai Ng; Peter Polidoro

2004-01-01

314

Method of making straight fuel cell tubes  

DOEpatents

A method and an apparatus for making straight fuel cell tubes are disclosed. Extruded tubes comprising powders of fuel cell material and a solvent are dried by rotating the extruded tubes. The rotation process provides uniform circumferential drying which results in uniform linear shrinkage of the tubes. The resultant dried tubes are very straight, thereby eliminating subsequent straightening steps required with conventional processes. The method is particularly useful for forming inner air electrode tubes of solid oxide fuel cells.

Borglum, Brian P. (Edgewood, PA)

2001-01-01

315

Cosmic Microwave Background  

NSDL National Science Digital Library

In this lesson, students explore the cosmic microwave background to understand why it permeates the universe and why it peaks as microwave radiation. Students should be able to explain that the origin of the background radiation is the uniform thermal radiation of the big bang and that the radiation produced was evenly distributed around the small early universe, causing it to permeate today's universe. This activity is part of the Cosmic Times teachers guide and is intended to be used in conjunction with the 1965 Cosmic Times Poster.

316

The Cosmic Background Explorer  

NASA Technical Reports Server (NTRS)

The Cosmic Background Explorer (CBE), NASA's cosmological satellite which will observe a radiative relic of the big bang, is discussed. The major questions connected to the big bang theory which may be clarified using the CBE are reviewed. The satellite instruments and experiments are described, including the Differential Microwave Radiometer, which measures the difference between microwave radiation emitted from two points on the sky, the Far-Infrared Absolute Spectrophotometer, which compares the spectrum of radiation from the sky at wavelengths from 100 microns to one cm with that from an internal blackbody, and the Diffuse Infrared Background Experiment, which searches for the radiation from the earliest generation of stars.

Gulkis, Samuel; Lubin, Philip M.; Meyer, Stephan S.; Silverberg, Robert F.

1990-01-01

317

The cosmic microwave background  

NASA Technical Reports Server (NTRS)

Recent limits on spectral distortions and angular anisotropies in the cosmic microwave background are reviewed. The various backgrounds are described, and the theoretical implications are assessed. Constraints on inflationary cosmology dominated by cold dark matter (CDM) and on open cosmological models dominated by baryonic dark matter (BDM), with, respectively, primordial random phase scale-invariant curvature fluctuations or non-gaussian isocurvature fluctuations are described. More exotic theories are addressed, and I conclude with the 'bottom line': what theorists expect experimentalists to be measuring within the next two to three years without having to abandon their most cherished theories.

Silk, Joseph

1991-01-01

318

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

319

AUV fuzzy neural BDI  

NASA Astrophysics Data System (ADS)

The typical BDI (belief desire intention) model of agent is not efficiently computable and the strict logic expression is not easily applicable to the AUV (autonomous underwater vehicle) domain with uncertainties. In this paper, an AUV fuzzy neural BDI model is proposed. The model is a fuzzy neural network composed of five layers: input (beliefs and desires), fuzzification, commitment, fuzzy intention, and defuzzification layer. In the model, the fuzzy commitment rules and neural network are combined to form intentions from beliefs and desires. The model is demonstrated by solving PEG (pursuit-evasion game), and the simulation result is satisfactory.

Liu, Hai-Bo; Gu, Guo-Chang; Shen, Jing; Fu, Yan

2005-09-01

320

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

321

Nonsteady Flow in Capillary Tubes  

NASA Astrophysics Data System (ADS)

Surface phenomena in the field of electron devices and the problem of how long. It takes plants to absorb water during their growth in hydroponic cultivation is attraching the attention of riseachers. However, the related study of non-steady flow in capillary tubes has a number of issues that require investigation. In response to this situation, we made attempted to assess nonsteady fiow in capillary tubes, the liquid rise time and other issues, using a motion equation that takes factors including the friction force of the tube and the surface tension into consideration.

Hara, Ayako

2000-03-01

322

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

323

Vortex tubes in velocity fields of laboratory isotropic turbulence: dependence on the Reynolds number.  

PubMed

The streamwise and transverse velocities are measured simultaneously in isotropic grid turbulence at relatively high Reynolds numbers Re(lambda) approximately 110-330. Using a conditional averaging technique, we extract typical intermittency patterns that are consistent with velocity profiles of a model for a vortex tube, i.e., Burgers vortex. The radii of the vortex tubes are several of the Kolmogorov length, regardless of the Reynolds number. Using the distribution of an interval between successive enhancements of a small-scale velocity increment, we study the spatial distribution of vortex tubes. The vortex tubes tend to cluster together. This tendency is increasingly significant with the Reynolds number. Using statistics of velocity increments, we also study the energetical importance of vortex tubes as a function of the scale. The vortex tubes are important over the background flow at small scales especially below the Taylor microscale. At a fixed scale, the importance is increasingly significant with the Reynolds number. PMID:12636600

Mouri, Hideaki; Hori, Akihiro; Kawashima, Yoshihide

2003-01-01

324

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

325

Radioactive Decay 1. Background  

E-print Network

Radioactive Decay 1. Background It is well known that many nuclei are unstable and are transformed into other nuclear species by means of either alpha decay or beta decay. The rate at which those radioactive on the number N of radioactive nuclei in the sample and also on the probability for each nucleus to decay

Elster, Charlotte

326

Country background Forest history  

E-print Network

33 Country background Forest history During the Gallo-Roman period (1st­4th century AD), forests this proportion decreased dramatically to only 15­17 % of the land area. This residual forest was then severely Colbert's Forest Ordinance was instituted in 1669 a gradual restoration took place. High forests produced

Paris-Sud XI, Université de

327

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

328

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

329

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 Soares

2014-11-13

330

Condensation of tubular D2-branes in a magnetic field background  

NASA Astrophysics Data System (ADS)

It is known that in the Minkowski vacuum a bunch of IIA superstrings with D0-branes can be blown-up to a supersymmetric tubular D2-brane, which is supported against collapse by the angular momentum generated by crossed electric and magnetic Born-Infeld fields. In this paper we show how the multiple, smaller tubes with relative angular momentum could condense to a single, larger tube to stabilize the system. Such a phenomena could also be shown in the systems under the Melvin magnetic-tube or uniform magnetic field background. However, depending on the magnitude of field strength, a tube in the uniform magnetic field background may split into multiple, smaller tubes with relative angular momentum to stabilize the system.

Huang, Wung-Hong

2004-11-01

331

Charm production in flux tubes  

SciTech Connect

We argue that the nonperturbative Schwinger mechanism may play an important role in the hadronic production of charm. We present a flux tube model which assumes that the colliding hadrons become color charged because of gluon exchange, and that a single nonelementary flux tube is built up as they recede. The strong chromoelectric field inside this tube creates quark pairs (including charmed ones) and the ensuing color screening breaks the tube into excited hadronic clusters. In their turn these clusters, or {open_quote}{open_quote}fireballs,{close_quote}{close_quote} decay statistically into the final hadrons. The model is able to account for the soft production of charmed, strange, and lighter hadrons within a unified framework. {copyright} {ital 1996 The American Physical Society.}

Aguiar, C.E.; Kodama, T.; Nazareth, R.A.; Pech, G. [Instituto de Fisica, Universidade Federal do Rio de Janeiro, C.P. 68528, 21945-970, Rio de Janeiro (Brazil)] [Instituto de Fisica, Universidade Federal do Rio de Janeiro, C.P. 68528, 21945-970, Rio de Janeiro (Brazil); [European Centre for Theoretical Studies in Nuclear Physics and Related Areas, Villa Tambosi, I-38050, Trento (Italy); [Instituto de Fisica, Universidade do Estado do Rio de Janeiro, 20550-013, Rio de Janeiro (Brazil)

1996-01-01

332

YouTube und Kinder.  

E-print Network

??Das Phänomen YouTube, als Inbegriff eines Videoportals, das alle Eigenschaften einer Web 2.0-Anwendung erfüllt, betrifft nicht nur erwachsene Mediennutzer, sondern ganz besonders auch Kinder. Der… (more)

Blaimschein, Sarah

2013-01-01

333

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

334

The neural decoding toolbox  

E-print Network

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 ...

Meyers, Ethan M.

335

Geometric neural computing.  

PubMed

This paper shows the analysis and design of feedforward neural networks using the coordinate-free system of Clifford or geometric algebra. It is shown that real-, complex-, and quaternion-valued neural networks are simply particular cases of the geometric algebra multidimensional neural networks and that some of them can also be generated using support multivector machines (SMVMs). Particularly, the generation of radial basis function for neurocomputing in geometric algebra is easier using the SMVM, which allows one to find automatically the optimal parameters. The use of support vector machines in the geometric algebra framework expands its sphere of applicability for multidimensional learning. Interesting examples of nonlinear problems show the effect of the use of an adequate Clifford geometric algebra which alleviate the training of neural networks and that of SMVMs. PMID:18249926

Bayro-Corrochano, E J

2001-01-01

336

The Neural Code  

NSDL National Science Digital Library

Cognitive information is encoded in patterns of nervous activity and decoded by molecular listening devices at the synapse. Professor Seth Grant explains how different patterns of neural firing are critical to cognition.

2009-04-14

337

Weakly connected neural nets  

NASA Technical Reports Server (NTRS)

A new neural network architecture is proposed based upon effects of non-Lipschitzian dynamics. The network is fully connected, but these connections are active only during vanishingly short time periods. The advantages of this architecture are discussed.

Zak, Michail

1990-01-01

338

Using Neural Networks  

E-print Network

unmeasurable parameters in a first-principles mathematical model of the engine. The network is trained using data derived from measured data taken on an auxiliary power unit (APU) engine (from an aircraft application). A discussion of the neural network...

Gabel, S.

339

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

340

Dermatology on YouTube.  

PubMed

YouTube, reaches upwards of six billion users on a monthly basis and is a unique source of information distribution and communication. Although the influence of YouTube on personal health decision-making is well established, this study assessed the type of content and viewership on a broad scope of dermatology related content on YouTube. Select terms (i.e. dermatology, sun protection, skin cancer, skin cancer awareness, and skin conditions) were searched on YouTube. Overall, the results included 100 videos with over 47 million viewers. Advocacy was the most prevalent content type at 24% of the total search results. These 100 videos were "shared" a total of 101,173 times and have driven 6,325 subscriptions to distinct YouTube user pages. Of the total videos, 35% were uploaded by or featured an MD/DO/PhD in dermatology or other specialty/field, 2% FNP/PA, 1% RN, and 62% other. As one of the most trafficked global sites on the Internet, YouTube is a valuable resource for dermatologists, physicians in other specialties, and the general public to share their dermatology-related content and gain subscribers. However, challenges of accessing and determining evidence-based data remain an issue. PMID:24945641

Boyers, Lindsay N; Quest, Tyler; Karimkhani, Chante; Connett, Jessica; Dellavalle, Robert P

2014-06-01

341

Tube wall thickness measurement apparatus  

DOEpatents

An apparatus for measuring the thickness of a tube's wall for the tube's entire length and circumference by determining the deviation of the tube wall thickness from the known thickness of a selected standard item. The apparatus comprises a base and a first support member having first and second ends. The first end is connected to the base and the second end is connected to a spherical element. A second support member is connected to the base and spaced apart from the first support member. A positioning element is connected to and movable relative to the second support member. An indicator is connected to the positioning element and is movable to a location proximate the spherical element. The indicator includes a contact ball for first contacting the selected standard item and holding it against the spherical element. The contact ball then contacts the tube when the tube is disposed about the spherical element. The indicator includes a dial having a rotatable needle for indicating the deviation of the tube wall thickness from the thickness of the selected standard item.

Lagasse, Paul R. (Santa Fe, NM)

1987-01-01

342

Ubiquitous Solar Eruptions Driven by Magnetized Vortex Tubes  

E-print Network

The solar surface is covered by high-speed jets transporting mass and energy into the solar corona and feeding the solar wind. The most prominent of these jets have been known as spicules. However, the mechanism initiating these eruptions events is still unknown. Using realistic numerical simulations we find that small-scale eruptions are produced by ubiquitous magnetized vortex tubes generated by the Sun's turbulent convection in subsurface layers. The swirling vortex tubes (resembling tornadoes) penetrate into the solar atmosphere, capture and stretch background magnetic field, and push surrounding material up, generating quasiperiodic shocks. Our simulations reveal a complicated high-speed flow patterns, and thermodynamic and magnetic structure in the erupting vortex tubes. We found that the eruptions are initiated in the subsurface layers and are driven by the high-pressure gradients in the subphotosphere and photosphere, and by the Lorentz force in the higher atmosphere layers.

Kitiashvili, I N; Lele, S K; Mansour, N N; Wray, A A

2013-01-01

343

High school music classes enhance the neural processing of speech.  

PubMed

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

344

Cosmic Microwave Background Theory  

Microsoft Academic Search

A long-standing goal of theorists has been to constrain cosmological parameters that define the structure formation theory from cosmic microwave background (CMB) anisotropy experiments and large-scale structure (LSS) observations. The status and future promise of this enterprise is described. Current band-powers in ell -space are consistent with a Delta T flat in frequency and broadly follow inflation-based expectations. That the

J. Richard Bond

1998-01-01

345

The cosmic microwave background  

NASA Technical Reports Server (NTRS)

Recent observational and theoretical investigations of the cosmic microwave background radiation (CMBR) are reviewed. Particular attention is given to spectral distortions and CMBR temperature anisotropies at large, intermediate, and small angular scales. The implications of the observations for inflationary cosmological models with curvature fluctuation are explored, and it is shown that the limits determined for intermediate-scale CMBR anisotropy almost rule out a baryon-dominated cosmology.

Silk, Joseph

1989-01-01

346

Mathematical modeling supports substantial mouse neural progenitor cell death  

PubMed Central

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, differentiate, and die at each cell cycle. Conclusion We demonstrate that uniformly low-level neural progenitor cell death, as concluded in previous models, is incompatible with normal mouse cortical development. Levels of neural progenitor cell death up to and exceeding 50% are compatible with normal cortical development and may operate to prevent forebrain overgrowth as observed following cell death attenuation, as occurs in caspase 3-null mutant mice. PMID:19602274

McConnell, Michael J; MacMillan, Hugh R; Chun, Jerold

2009-01-01

347

Dialyzers and D-Tube Electroelution Kit  

E-print Network

-TubeTM Dialyzers are easy-to-handle dialyzers in a capped centrifuge tube format with dialysis membrane windows recovery. The disposable, single-use tubes require no syringes, centrifuge, or laborious steps rack that can hold up to four devices in an exchange buffer. D-TubeTM Dialyzers: maximizing convenience

Lebendiker, Mario

348

Rounding And Aligning Tubes For Butt Welding  

NASA Technical Reports Server (NTRS)

Easy-to-use tool helps to ensure solid, reliable joint. Tool similar to automobile-tailpipe expander corrects out-of-roundness in tubes before butt-welded and holds tubes in position during welding. Two tubes rounded and aligned with each other by expansion shoes. After use, shoes retracted so tool withdrawn, even through tube narrower than its mate.

Burley, Richard H.; Burow, Glenn H.

1990-01-01

349

Stereospecificity and PAX6 function direct Hoxd4 neural enhancer activity along the antero-posterior axis  

Microsoft Academic Search

The antero-posterior (AP) and dorso-ventral (DV) patterning of the neural tube is controlled in part by HOX and PAX transcription factors, respectively. We have reported on a neural enhancer of Hoxd4 that directs expression in the CNS with the correct anterior border in the hindbrain. Comparison to the orthologous enhancer of zebrafish revealed seven conserved footprints including an obligatory retinoic

Christof Nolte; Mojgan Rastegar; Angel Amores; Maxime Bouchard; David Grote; Richard Maas; Erzsebet Nagy Kovacs; John Postlethwait; Isabel Rambaldi; Sheldon Rowan; Yi-Lin Yan; Feng Zhang; Mark Featherstone

2006-01-01

350

Nasal Bridles for Securing Nasoenteric Tubes: A Meta-Analysis  

PubMed Central

Background Nasoenteric feeding tubes may easily become dislodged due to patient mental status, transfers, or positional changes. Nasal bridles were introduced to provide a better, more reliable system to secure these tubes. This meta-analysis was performed to evaluate the effectiveness of nasal bridles compared with the traditional method of adhesive tape alone in securing enteral feeding tubes. Materials and Methods Multiple databases were searched (October 2013). All studies that evaluated the use of nasal bridles in adult patients were included in the analysis. Meta-analysis for the outcomes from use of a nasal bridle vs the more traditional method of adhesive tape alone for securing nasoenteric tubes was analyzed by calculating pooled estimates of dislodgement, skin complications, and sinusitis. Statistical analysis was performed using RevMan 5.1. Results Six studies (n = 594) met the inclusion criteria. Use of a nasal bridle for securing enteral tubes resulted in a statistically significant reduction in tube dislodgement compared with traditional adhesive tape alone (odds ratio [OR], 0.16; 95% confidence interval [CI], 0.10–0.27; P < .01). The use of nasal bridles was associated with a higher rate of skin complications compared with traditional adhesive tape (OR, 4.27; 95% CI, 1.79–10.23; P < .01). Incidence of sinusitis was no different between the 2 groups (OR, 0.26; 95% CI, 0.03–2.28; P = .22). Conclusion Nasal bridles appear to be more effective at securing nasoenteric tubes and preventing dislodgement than traditional use of tape alone. PMID:25606648

Bechtold, Matthew L.; Nguyen, Douglas L.; Palmer, Lena B.; Kiraly, Laszlo N.; Martindale, Robert G.; McClave, Stephen A.

2015-01-01

351

Volume Threshold for Chest Tube Removal: A Randomized Controlled Trial  

PubMed Central

Abstract: Background: Despite importance of chest tube insertion in chest trauma, there is no general agreement on the level of daily volume drainage from chest tube. This study was conducted to compare the effectiveness and safety of chest tube removal at the levels of 150 ml/day and 200 ml/day. Methods: Eligible patients (138) who needed replacement of chest tube (because of trauma or malignancy) were randomized into two groups; control (removal of chest tube when drainage reached to 150 ml/day) and trial (removal of chest tube at the level of 200 ml/day). All patients received standard care during hospital admission and a follow-up visit after 7days of discharge from hospital. Patients were then compared in terms of major clinical outcomes using chisquared and t-test. Results: From the total of 138 patients, 70 and 68 patients were randomized to control (G150) and trial (G200) group, respectively. Baseline characteristics were comparable between the two groups. Although the trial group had a shorter mean for length of hospital stay (LOS) (4.1 compared to 4.8, p=0.04), their differences in drainage time did not reach to the level of statistical significance (p=0.1). Analysis of data showed no statistically significant differences between the rate of radiological reaccumulation, thoracentesis and decrease in pulmonary sounds (auscultatory), one week after discharge from hospital. Conclusions: Compared to a daily volume drainage of 150 ml, removal of chest tube when there is 200 ml/day is safe and will even result in a shorter hospital stay. This in turn leads to a lower cost. PMID:21483189

Ali Hessami, Mohammad; Najafi, Farid; Hatami, Sajad

2009-01-01

352

Neural crest cells provide species-specific patterning information in the developing branchial skeleton.  

PubMed

The skeletal elements of the branchial region are made by neural crest cells, following tissue interactions with the pharyngeal endoderm. Previous transplantation experiments have claimed that the cranial neural crest is morphogenetically prespecified in respect of its branchial skeletal derivatives, that is, that information for the number, size, shape, and position of its individual elements is already determined in these cells when they are still in the neural folds. This positional information would somehow be preserved during delamination from the neural tube and migration into the branchial arches, before being read out as a spatial pattern of chondrogenesis and osteogenesis. However, it now appears that signals from the endoderm are able to specify not only the histogenic differentiation state of neural crest cells but also the identity and orientation of the branchial skeletal elements. It is therefore important to ask whether fine details of branchial skeletal pattern such as those that exist between different species are also governed by extrinsic factors, such as the endoderm, or by the neural crest itself. We have grafted neural crest between duck and quail embryos and show that the shape and size of the resulting skeletal elements is donor derived. The ability to form species-specific patterns of craniofacial skeletal tissue thus appears to be an inherent property of the neural crest, expressed as species-specific responses to endodermal signals. PMID:15108816

Tucker, Abigail S; Lumsden, Andrew

2004-01-01

353

Fallopian Tube Prolapse after Hysterectomy: A Systematic Review  

PubMed Central

Background Prolapse of the fallopian tube into the vaginal vault is a rarely reported complication that may occur after hysterectomy. Clinicians can miss the diagnosis of this disregarded complication when dealing with post-hysterectomy vaginal bleeding. Objectives We performed a systematic review in order to describe the clinical presentation, therapeutic management and outcome of fallopian tube prolapse occurring after hysterectomy. Search Strategy A systematic search of MEDLINE and EMBASE references from January 1980 to December 2010 was performed. We included articles that reported cases of fallopian tube prolapse after hysterectomy. Data from eligible studies were independently extracted onto standardized forms by two reviewers. Results Twenty-eight articles including 51 cases of fallopian tube prolapse after hysterectomy were included in this systematic review. Clinical presentations included abdominal pain, dyspareunia, post- coital bleeding, and/or vaginal discharge. Two cases were asymptomatic and diagnosed at routine checkup. The surgical management reported comprised partial or total salpingectomy, with vaginal repair in some cases combined with oophorectomy using different approaches (vaginal approach, combined vaginal-laparoscopic approach, laparoscopic approach, or laparotomy). Six patients were initially treated by silver nitrate application without success. Conclusions This systematic review provided a precise summary of the clinical characteristics and treatment of patients presenting with fallopian tube prolapse following hysterectomy published in the past 30 years. We anticipate that these results will help inform current investigations and treatment. PMID:24116117

Ouldamer, Lobna; Caille, Agnès; Body, Gilles

2013-01-01

354

UBIQUITOUS SOLAR ERUPTIONS DRIVEN BY MAGNETIZED VORTEX TUBES  

SciTech Connect

The solar surface is covered by high-speed jets transporting mass and energy into the solar corona and feeding the solar wind. The most prominent of these jets have been known as spicules. However, the mechanism initiating these eruption events is still unknown. Using realistic numerical simulations we find that small-scale eruptions are produced by ubiquitous magnetized vortex tubes generated by the Sun's turbulent convection in subsurface layers. The swirling vortex tubes (resembling tornadoes) penetrate into the solar atmosphere, capture and stretch background magnetic field, and push the surrounding material up, generating shocks. Our simulations reveal complicated high-speed flow patterns and thermodynamic and magnetic structure in the erupting vortex tubes. The main new results are: (1) the eruptions are initiated in the subsurface layers and are driven by high-pressure gradients in the subphotosphere and photosphere and by the Lorentz force in the higher atmosphere layers; (2) the fluctuations in the vortex tubes penetrating into the chromosphere are quasi-periodic with a characteristic period of 2-5 minutes; and (3) the eruptions are highly non-uniform: the flows are predominantly downward in the vortex tube cores and upward in their surroundings; the plasma density and temperature vary significantly across the eruptions.

Kitiashvili, I. N.; Kosovichev, A. G. [Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA 94305 (United States); Lele, S. K.; Mansour, N. N.; Wray, A. A., E-mail: irinasun@stanford.edu [Center for Turbulence Research, Stanford University, Stanford, CA 94305 (United States)

2013-06-10

355

Targets, backgrounds, and discrimination  

NASA Astrophysics Data System (ADS)

The present volume discusses a model-based aircraft identification technique, target intensity and angle scintillations, spatiotemporal nonstationary scene generation, an overview of the Strategic Scene Generation Model (SSGM), nuclear backgrounds for SSGM, and an atmospheric and transmittance code for 50-300 km altitudes. Also discussed are a data base for airborne target signatures, the auroral module of the Strategic High Altitude Radiance Code, and the 3D characteristics of underexpanded and overexpanded rectangular jets. (No individual items are abstracted in this volume)

Accetta, J. S.; Kelley, G. H.

356

The Limitations of GastroJejunal (G-J) Feeding Tubes in Children: A 9Year Pediatric Hospital Database Analysis  

Microsoft Academic Search

BACKGROUND:A gastro-jejunal (G-J) feeding tube is a safe and useful temporizing method of providing enteral access in children. Although G-J tubes are often used to obviate the need for a surgical jejunostomy, their long-term use is often associated with mechanical failure.AIM:To review the clinically effective durability of G-J feeding tubes in providing enteral access in children.METHODS:We performed a retrospective review

John E. Fortunato; Anil Darbari; Sally E. Mitchell; Richard E. Thompson; Carmen Cuffari

2005-01-01

357

Primary placement technique of jejunostomy using the entristar™ skin-level gastrostomy tube in patients with esophageal cancer  

Microsoft Academic Search

BACKGROUND: We developed a skin-level jejunostomy tube (SLJT) procedure for patients undergoing esophagectomy using a skin-level gastrostomy tube (G-tube) (Entristar™; Tyco Healthcare, Mansfield, Mass), in order to improve their nutrition status and quality of life (QOL). We describe the procedure and the adverse effects of SLJT in patients with esophageal cancer (EC). METHODS: Over a 24-month period (March 2008 to

Yasushi Rino; Norio Yukawa; Hitoshi Murakami; Tsutomu Sato; Ken Takata; Tsutomu Hayashi; Takashi Oshima; Nobuyuki Wada; Munetaka Masuda; Toshio Imada

2011-01-01

358

Backgrounds Data Center  

NASA Astrophysics Data System (ADS)

The Backgrounds Data Center (BDC) is the designated archive for backgrounds data collected by Ballistic Missile Defense Organization (BMDO) programs, some of which include ultraviolet sensors. Currently, the BDC holds ultraviolet data from the IBSS, UVPI, UVLIM, and FUVCAM sensors. The BDC will also be the prime archive for Midcourse Space Experiment (MSX) data and is prepared to negotiate with program managers to handle other datasets. The purpose of the BDC is to make data accessible to users and to assist them in analyzing it. The BDC maintains the Science Catalog Information Exchange System (SCIES) allowing remote users to log in, read or post notices about current programs, search the catalogs for datasets of interest, and submit orders for data. On-site facilities are also available for the analysis of data, and consist of VMS and UNIX workstations with access to software analysis packages such as IDL, IRAF, and Khoros. Either on-site or remotely, users can employ the BDC-developed graphical user interface called the Visual Interface for Space and Terrestrial Analysis (VISTA) to generate catalog queries and to display and analyze data. SCIES and VISTA permit nearly complete access to BDC services and capabilities without the need to be physically present at the data center.

Snyder, William A.; Gursky, Herbert; Heckathorn, Harry M.; Lucke, Bob L.; Dorland, Bryan N.; Kessel, R. A.; Berg, S. L.; Dombrowski, E. G.

1994-09-01

359

Mathematics of the Neural Response  

E-print Network

We propose a natural image representation, the neural response, motivated by the neuroscience of the visual cortex. The inner product defined by the neural response leads to a similarity measure between functions which we ...

Caponnetto, Andrea

2008-11-26

360

Mathematics of the Neural Response  

E-print Network

We propose a natural image representation, the neural response, motivated by the neuroscience of the visual cortex. The inner product defined by the neural response leads to a similarity measure between functions which we ...

Bouvrie, Jacob Vincent

361

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

362

Neural Mechanisms of Perceptual Learning  

E-print Network

Cholinergic enhancement modulates neural correlates ofneural selectivity by ACh may Chapter 3. Cholinergic enhancementenhancement, this would provide further support to the idea that learning occurs through a change in the neural

Rokem, Ariel Shalom

2010-01-01

363

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

364

Parallel consensual neural networks.  

PubMed

A new type of a neural-network architecture, the parallel consensual neural network (PCNN), is introduced and applied in classification/data fusion of multisource remote sensing and geographic data. The PCNN architecture is based on statistical consensus theory and involves using stage neural networks with transformed input data. The input data are transformed several times and the different transformed data are used as if they were independent inputs. The independent inputs are first classified using the stage neural networks. The output responses from the stage networks are then weighted and combined to make a consensual decision. In this paper, optimization methods are used in order to weight the outputs from the stage networks. Two approaches are proposed to compute the data transforms for the PCNN, one for binary data and another for analog data. The analog approach uses wavelet packets. The experimental results obtained with the proposed approach show that the PCNN outperforms both a conjugate-gradient backpropagation neural network and conventional statistical methods in terms of overall classification accuracy of test data. PMID:18255610

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

1997-01-01

365

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

366

Fuzzy logic and neural network technologies  

NASA Technical Reports Server (NTRS)

Applications of fuzzy logic technologies in NASA projects are reviewed to examine their advantages in the development of neural networks for aerospace and commercial expert systems and control. Examples of fuzzy-logic applications include a 6-DOF spacecraft controller, collision-avoidance systems, and reinforcement-learning techniques. The commercial applications examined include a fuzzy autofocusing system, an air conditioning system, and an automobile transmission application. The practical use of fuzzy logic is set in the theoretical context of artificial neural systems (ANSs) to give the background for an overview of ANS research programs at NASA. The research and application programs include the Network Execution and Training Simulator and faster training algorithms such as the Difference Optimized Training Scheme. The networks are well suited for pattern-recognition applications such as predicting sunspots, controlling posture maintenance, and conducting adaptive diagnoses.

Villarreal, James A.; Lea, Robert N.; Savely, Robert T.

1992-01-01

367

3D nano/microfabrication techniques and nanobiomaterials for neural tissue regeneration.  

PubMed

Injuries of the nervous system occur commonly among people of many different ages and backgrounds. Currently, there are no effective strategies to improve neural regeneration; however, tissue engineering provides a promising avenue for regeneration of many tissue types, including the neural context. Functional nerve conduits derived from tissue engineering techniques present bioengineered 3D artificial substitutes for implantation and rehabilitation of injured nerves. In particular, nanotechnology as a versatile vehicle to create biomimetic nanostructured tissue-engineered neural scaffolds provides great potential for the development of innovative and successful nerve grafts. Nanostructured conduits derived from traditional and novel tissue engineering techniques have been shown to be superior for successful neural function construction due to a high degree of biomimetic character. In this paper, we will focus on current progress in developing 3D nano/microstructured neural scaffolds via electrospinning, emerging 3D printing and self-assembly techniques, nanobiomaterials and bioactive cues for enhanced neural tissue regeneration. PMID:24981651

Zhu, Wei; O'Brien, Christopher; O'Brien, Joseph R; Zhang, Lijie Grace

2014-05-01

368

Measuring Cherenkov Backgrounds from Proportional Counters in SNO  

NASA Astrophysics Data System (ADS)

In the current phase of operation of the Sudbury Neutrino Observatory, He-3 proportional counters have been deployed in the center of the detector to measure neutron production from neutral-current interactions between neutrinos and deuterons in the heavy water. Radioactive decays of Bi-214 and Tl-208 in the counters produce gammas of sufficient energy to photodisintegrate deuterons, which become a background to the neutral current measurement. We have measured the background rate in-situ using Cherenkov light detected with SNO's 9456 inward-looking photomultiplier tubes. A maximum likelihood method is used to separate backgrounds in the heavy water from backgrounds in the proportional counters based upon the spatial distribution of low energy Cherenkov event vertices. Uncertainties on the backgrounds have been estimated using calibration data taken with both a distributed Na-24 source, and a contained Th source deployed at various points in the detector.

Seibert, Stanley

2006-04-01

369

Hobetron current regulating switch tube  

SciTech Connect

This paper describes a novel high power electron tube that can hold off voltages up to hundreds of kilovolts, and switch hundreds of amps of current. They call the divide the Hobertron since it utilizes a hollow electron beam. Unlike magnetron injection gun (MIG) switch tubes, it does not require a magnet. Further, it uses nonintercepting control laments, and a dispenser cathode for long life and reliability. Finally, it features a double walled Faraday cage collector for high power dissipation capability. Current is very tightly controlled against changes in voltage across the switch (it is an almost perfect pentode), thus this tube is ideally suited for direct series switching applications. In the paper, various Hobertron designs, and the computer codes and methods used to create them, will be described.

True, R.B.; Hansen, R.J.; Deb, D.N.; Good, G.R.; Reass, W.A.

1999-07-01

370

Failure analysis of brass tubes  

SciTech Connect

The 1996 Jacquet Lucas Award for Excellence in Metallography was won by Samuel J. Lawrence and Richard L. Bodnar for their analysis of cracks in Admiralty brass cooling tubes, which are part of a heat exchanger in a turbogenerator that provides electricity to a manufacturing plant. A mixture of non-recirculating city and spring pit water flows through bundles of tubes to cool the oil in which they are immersed. However, a problem developed when several of the brass tubes cracked transversely, allowing cooling water to mix with the oil. This award-winning entry in the ASM/IMS competition shows how the metallographers analyzed the cracks, and what the results were.

Lawrence, S.J.; Bodnar, R.L. [Bethlehem Steel Corp., PA (United States)

1997-02-01

371

Coiled tubing; Operations and services  

SciTech Connect

Oil and gas wells that flow on initial completion eventually reach a condition of liquid loading that kills the wells. This results form declining reservoir pressure, decreased gas volume (velocity), increased water production and other factors that cause liquids to accumulate at the bottom of the well and exert back pressure on the formation. This restricts or in some cases prevents fluid entry into the wellbore form the formation. Flowing production can be restored or increased by reducing surface backpressure, well bore stimulation, pressure maintenance or by installing a string of smaller diameter tubing. This paper reports on installation (hanging off) of a concentric string of coiled tubing inside existing production tubing which is an economically viable, safe, convenient and effective alterative for returning some of these liquid loaded )logged-up) wells to flowing status.

Brown, P.T.; Wimberly, R.D.

1992-10-01

372

End Calorimeter Warm Tube Heater  

SciTech Connect

The Tevatron accelerator beam tube must pass through the End Calorimeter cryostats of the D-Zero Collider Detector. Furthermore, the End Calorimeter cryostats must be allowed to roll back forty inches without interruption of the vacuum system; hence, the Tev tube must slide through the End Calorimeter cryostat as it is rolled back. The Tev pass through the End Calorimeter can actually be thought of as a cluster of concentric tubes: Tev tube, warm (vacuum vessel) tube, IS layers of superinsulation, cold tube (argon vessel), and Inner Hadronic center support tube. M. Foley generated an ANSYS model to study the heat load. to the cryostat. during collider physics studies; that is, without operation of the heater. A sketch of the model is included in the appendix. The vacuum space and superinsulation was modeled as a thermal solid, with conductivity derived from tests performed at Fermilab. An additional estimate was done. by this author, using data supplied by NR-2. a superinsulation manufacturer. The ANSYS result and hand calculation are in close agreement. The ANSYS model was modified. by this author. to incorporate the effect of the heater. Whereas the earlier model studied steady state operation only. the revised model considers the heater-off steady state mode as the initial condition. then performs a transient analysis with a final load step for time tending towards infinity. Results show the thermal gradient as a function of time and applied voltage. It should be noted that M. Foley's model was generated for one half the warm tube. implying the tube to be symmetric. In reality. the downstream connection (relative to the collision point) attachment to the vacuum shell is via several convolutions of a 0.020-inch wall bellows; hence. a nearly adiabatic boundary condition. Accordingly. the results reported in the table reflect extrapolation of the curves to the downstream end of the tube. Using results from the ANSYS analysis, that is, tube temperature and corresponding heat flux, temperature of the nichrome wire can be estimated. The possibility of frost is of genuine concern, as evidenced by the 250 K minimum temperature for the warm tube while heaters are not operating. Noting that steady state operation at 1 Amp (40 volts) allows the nichrome wire to stay below the critical temperature for Kapton, a conservative plan is to allow several days of heater operation, at 1 Amp (40 volts), before roll-back. Warm-up can be accelerated by operating the heaters in excess of 1 Amp, as evidenced by the test where a maximum of 3.2 Amp was supplied. Operating the heaters in excess of 1 Amp must be done with care since a rapid rise in temperature will likely occur once any ice present has been melted.

Primdahl, K.; /Fermilab

1991-08-06

373

Molecular Analysis of Microbial Communities in Endotracheal Tube Biofilms  

Microsoft Academic Search

BackgroundVentilator-associated pneumonia is the most prevalent acquired infection of patients on intensive care units and is associated with considerable morbidity and mortality. Evidence suggests that an improved understanding of the composition of the biofilm communities that form on endotracheal tubes may result in the development of improved preventative strategies for ventilator-associated pneumonia.Methodology\\/Principal FindingsThe aim of this study was to characterise

Scott Cairns; John Gilbert Thomas; Samuel James Hooper; Matthew Peter Wise; Paul John Frost; Melanie Julia Wilson; Michael Alexander Oxenham Lewis; David Wynne Williams; Niyaz Ahmed

2011-01-01

374

Neural network learning without backpropagation.  

PubMed

The method introduced in this paper allows for training arbitrarily connected neural networks, therefore, more powerful neural network architectures with connections across layers can be efficiently trained. The proposed method also simplifies neural network training, by using the forward-only computation instead of the traditionally used forward and backward computation. PMID:20858577

Wilamowski, Bogdan M; Yu, Hao

2010-11-01

375

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

376

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

377

Hyperbolic Hopfield neural networks.  

PubMed

In recent years, several neural networks using Clifford algebra have been studied. Clifford algebra is also called geometric algebra. Complex-valued Hopfield neural networks (CHNNs) are the most popular neural networks using Clifford algebra. The aim of this brief is to construct hyperbolic HNNs (HHNNs) as an analog of CHNNs. Hyperbolic algebra is a Clifford algebra based on Lorentzian geometry. In this brief, a hyperbolic neuron is defined in a manner analogous to a phasor neuron, which is a typical complex-valued neuron model. HHNNs share common concepts with CHNNs, such as the angle and energy. However, HHNNs and CHNNs are different in several aspects. The states of hyperbolic neurons do not form a circle, and, therefore, the start and end states are not identical. In the quantized version, unlike complex-valued neurons, hyperbolic neurons have an infinite number of states. PMID:24808287

Kobayashi, M

2013-02-01

378

Holography for Schrodinger backgrounds  

E-print Network

We discuss holography for Schrodinger solutions of both topologically massive gravity in three dimensions and massive vector theories in (d+1) dimensions. In both cases the dual field theory can be viewed as a d-dimensional conformal field theory (two dimensional in the case of TMG) deformed by certain operators that respect the Schrodinger symmetry. These operators are irrelevant from the viewpoint of the relativistic conformal group but they are exactly marginal with respect to the non-relativistic conformal group. The spectrum of linear fluctuations around the background solutions corresponds to operators that are labeled by their scaling dimension and the lightcone momentum k_v. We set up the holographic dictionary and compute 2-point functions of these operators both holographically and in field theory using conformal perturbation theory and find agreement. The counterterms needed for holographic renormalization are non-local in the v lightcone direction.

Monica Guica; Kostas Skenderis; Marika Taylor; Balt van Rees

2010-08-11

379

The diffuse UV background  

NASA Technical Reports Server (NTRS)

The diffuse radiation field in the UV (900-3,000 A) affects the structure of galactic molecular clouds and conveys important information concerning the physical characteristics and spatial distribution of gas and dust in the universe. Continuum emission in this range is probably dominated by interstellar dust scattering in our galaxy. For view directions and angular resolutions allowing observations in the rifts between galactic dust clouds, the background due to the integrated light of spiral galaxies may be detected, providing important information on their structure and evolution. The redshifted emission from an intergalactic medium may be observable in the regions between nearby bright galaxies. Present observations provide weak constraints on the radiation field required to ionize the intergalactic medium at the level required by the Gunn-Peterson test.

Paresce, F.; Jakobsen, P.

1980-01-01

380

Free-Fall Bottles & Tubes  

NSDL National Science Digital Library

In this physics activity, learners conduct two experiments to explore free-falling. In the first experiment, water-filled plastic bottles with holes in them spurt water under normal conditions, but don't leak while in free-fall. In the second experiment, a ping-pong ball in a water-filled plastic tube floats upward under normal conditions, but remains motionless when the tube is dropped or thrown. Educators can use pre-assembled materials for group demonstration purposes. Note: this activity will get the floor wet, so consider doing this outside.

Don Rathjen

2011-08-20

381

The tube-to-tube through transmission eddy current technique  

Microsoft Academic Search

Heat exchangers are used in the process and power industries to transfer heat between two thermodynamic fluids. A new technique for inspection of heat exchanger tubing is introduced. The method is applicable to any inspection job that involves sets of parallel pipes. The technique is not adversely affected by support plate interference and can therefore be used to obtain information

A. Shatat; D. L. Atherton

1998-01-01

382

Enhancing the top signal at Tevatron using Neural Nets  

E-print Network

We show that Neural Nets can be useful for top analysis at Tevatron. The main features of $t\\bar t$ and background events on a mixed sample are projected in a single output, which controls the efficiency and purity of the $t\\bar t$ signal.

Ll. Ametller; Ll. Garrido; P. Talavera

1994-05-24

383

PAIN MEDICINE Neural Correlates of Chronic Low Back Pain Measured  

E-print Network

PAIN MEDICINE Neural Correlates of Chronic Low Back Pain Measured by Arterial Spin Labeling Ajay D of the CP exacerba- tions for each back pain subject. Results: The clinically significant worsening.D., Randy L. Gollub, M.D., Ph.D.# ABSTRACT Background: The varying nature of chronic pain (CP) is difficult

Napadow, Vitaly

384

Background light in potential sites for the ANTARES undersea neutrino telescope  

Microsoft Academic Search

The ANTARES collaboration has performed a series of in-situ measurements to study the background light for a planned undersea neutrino telescope. Such background can be caused by 40K decays or by biological activity. We report on measurements at two sites in the Mediterranean Sea at depths of 2400 m and 2700 m, respectively. Three photomultiplier tubes were used to measure

P. Amram; S. Anvar; E. Aslanides; J.-J. Aubert; R. Azoulay; S. Basa; Y. Benhammou; F. Bernard; V. Bertin; M. Billault; P-E Blanc; F. Blondeau; R. W Bland; N. Bottu; J. Boulesteix; B. Brooks; J. Brunner; A. Calzas; C. Carloganu; E. Carmona; J. Carr; P-H Carton; S. Cartwright; R. Cases; F. Cassol; C. Compere; S. Cooper; G. Coustillier; N de Botton; P. Deck; F. E Desages; J.-J. Destelle; G. Dispau; J. F Drogou; F. Drouhin; P-Y Duval; F. Feinstein; D. Festy; J. Fopma; J-L Fuda; P. Goret; L. Gosset; J-F Gournay; J. J. Hernández; G. Herrouin; F. Hubaut; J. R Hubbard; D. Huss; M. Jaquet; N. Jelley; E. Kajfasz; M. Karolak; A. Kouchner; V. Kudryavtsev; D. Lachartre; H. Lafoux; P. Lamare; J-C Languillat; D. Laugier; J-P Laugier; Y Le Guen; H Le Provost; A Le Van Suu; L. Lemoine; P. L Liotard; S. Loucatos; P. Magnier; M. Macelin; L. Martin; A. Massol; B. Mazeau; A. Mazure; F. Mazéas; J. McMillan; C. Millot; P. Mols; F. Montanet; J. P Morel; L. Moscoso; S. Navas; C. Olivetto; N. Palanque-Delabrouille; A. Pallares; P. Payre; P. Perrin; A. Pohl; J. Poinsignon; R. Potheau; Y. Queinec; C. Racca; M. Raymond; J. F Rolin; Y. Sacquin; J-P Schuller; W. Schuster; N. Spooner; T. Stolarczyk; A. Tabary; M. Talby; C. Tao; Y. Tayalati; L. F Thompson; R. Triay; T. Tzvetanov; P. Valdy; P. Vernin; E. Vigeolas; D. Vignaud; D. Vilanova; D. Wark; A. Zghiche; J. Zúñiga

2000-01-01

385

Pax3 is essential for normal cardiac neural crest morphogenesis but is not required during migration nor outflow tract septation  

PubMed Central

Systemic loss-of-function studies have demonstrated that Pax3 transcription factor expression is essential for dorsal neural tube, early neural crest and muscle cell lineage morphogenesis. Cardiac neural crest cells participate in both remodeling of the pharyngeal arch arteries and outflow tract septation during heart development, but the lineage specific role of Pax3 in neural crest function has not yet been determined. To gain insight into the requirement of Pax3 within the neural crest, we conditionally deleted Pax3 in both the premigratory and migratory neural crest populations via Wnt1-Cre and Ap2?-Cre and via P0-Cre in only the migratory neural crest, and compared these phenotypes to the pulmonary atresia phenotype observed following the systemic loss of Pax3. Surprisingly, using Wnt1-Cre deletion there are no resultant heart defects despite the loss of Pax3 from the premigratory and migratory neural crest. In contrast, earlier premigratory and migratory Ap2?-Cre mediated deletion resulted in double outlet right ventricle alignment heart defects. In order to assess the tissue-specific contribution of neural crest to heart development, genetic ablation of neural crest lineage using a Wnt1-Cre-activated diphtheria toxin fragment-A cell-killing system was employed. Significantly, ablation of Wnt1-Cre-expressing neural crest cells resulted in fully penetrant persistent truncus arteriosus malformations. Combined, the data show that Pax3 is essential for early neural crest progenitor formation, but is not required for subsequent cardiac neural crest progeny morphogenesis involving their migration to the heart or septation of the outflow tract. PMID:21600894

Olaopa, Michael; Zhou, Hong-ming; Snider, Paige; Wang, Jian; Schwartz, Robert J.; Moon, Anne M.; Conway, Simon J.

2011-01-01

386

Dynamical evolution of twisted magnetic flux tubes. I - Equilibrium and linear stability  

NASA Technical Reports Server (NTRS)

The three-dimensional dynamical evolution of twisted magnetic flux tubes is studied using a time-dependent magnetohydrodynamic (MHD) model. The flux tubes are intended to model solar coronal loops, and include the stabilizing effect of photospheric line tying. The model permits the complete evolution of flux tubes to be followed self-consistently, including the formation, equilibrium, linear instability, and nonlinear behavior. Starting from an initial uniform background magnetic field, a twisted flux tube is created by the application of slow, localized photospheric vortex flows. The flux tube evolves quasi-statically through sequences of equilibria with increasing twist, until it becomes linearly unstable to an ideal MHD kink mode. In this paper, the equilibrium properties and the linear stability behavior are discussed. The application of the method to the uniform-twist, Gold-Hoyle field confirms the previous stability threshold for kink instability and provides estimates of the resulting growth rate.

Mikic, Zoran; Schnack, Dalton D.; Van Hoven, Gerard

1990-01-01

387

Background sources in optical communications  

NASA Technical Reports Server (NTRS)

The characterization and measurement of background radiation relevant to optical communications system performance is addressed. The necessary optical receiver parameters are described, and radiometric concepts required for the calculation of collected background power are developed. The most important components of optical background power are discussed, and their contribution to the total collected background power in various communications scenarios is examined.

Vilnrotter, V. A.

1983-01-01

388

Cosmic Microwave Background  

NASA Astrophysics Data System (ADS)

The cosmic microwave background (CMB) radiation, the relic of the early phases of the expanding universe, is bright, full of information, and difficult to measure. Along with the recession of galaxies and the primordial nucleosynthesis, it is one of the strongest signs that the Hot Big Bang Model of the universe is correct. It is brightest around 2 mm wavelength, has a temperature of T_{cmb} = 2.72548 ± 0.00057 K, and has a blackbody spectrum within 50 parts per million. Its spatial fluctuations (around 0.01% on 1{}^{circ } scales) are possibly the relics of quantum mechanical processes in the early universe, modified by processes up to the decoupling at a redshift of about 1,000 (when the primordial plasma became mostly transparent). In the cold dark matter (DM) model with cosmic acceleration (? CDM), the fluctuation statistics are consistent with the model of inflation and can be used to determine other parameters within a few percent, including the Hubble constant, the ? constant, the densities of baryonic and dark matter, and the primordial fluctuation amplitude and power spectrum slope. In addition, the polarization of the fluctuations reveals the epoch of reionization at a redshift approximately twice that determined from the Gunn-Peterson trough due to optically thick Lyman ? absorption in QSO spectra. It is of historic importance, and a testament to the unity of theory and experiment, that we now have a standard model of cosmology that is consistent with all of the observations.Current observational challenges include (1) improvement of the spectrum distortion measurements, especially at long wavelengths, where the measured background is unexpectedly bright; (2) the search for the B-mode polarization (the divergence-free part of the polarization map), arising from propagating gravitational waves; and (3) the extension of fluctuation measurements to smaller angular scales. Much more precise spectrum observations near 2 mm are likely and would test some very interesting theories. Current theoretical challenges include explanation of the dark matter and dark energy; understanding, estimating, and removing the interference of foreground sources that limit the measurements of the CMB; detailed understanding of the influence of nonequilibrium processes on the decoupling and reionization phases; and searches for signs of the second order or exotic processes (e.g., isocurvature fluctuations, cosmic strings, non-Gaussian fluctuations). At this writing, we await the cosmological results of the Planck mission.

Mather, John; Hinshaw, Gary; Page, Lyman

389

Electron Diffraction Tube with mounting  

E-print Network

the electron beam, providing, with the anode, an electron optic lens system. The accelerated particles land of a fluorescent screen and #12;2 only one simple to operate, test instrument is required. compact "" The electron system (H, K, G! to G4) connect with the correspondlngly marked sockets on the mounting. The tube

Bayindir, Mehmet

390

Orifice fittings and meter tubes  

SciTech Connect

Various methods and designs of orifice fittings and meter tubes exist. The incorporation of these designs depend on process conditions, piping configurations, economics, and other considerations. Within the incorporation of these designs are the specifications of the orifice meter standards set forth by the AGA and the API. This will ensure reliable and accurate fluid measurement.

Ragsdale, J. [Daniel Industries, Inc., Tulsa, OK (United States)

1995-12-01

391

Phase detonated shock tube (PFST)  

Microsoft Academic Search

The simple, cylindrically imploding and axially driven fast shock tube (FST) has been a basic component in the high velocity penetrator (HVP) program. It is a powerful device capable of delivering a directed and very high pressure output that has been successfully employed to drive hypervelocity projectiles. The FST is configured from a hollow, high-explosive (HE) cylinder, a low-density Styrofoam

W. D. Zerwekh; S. P. Marsh; Tai-Ho Tan

1993-01-01

392

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

393

Neural Mechanisms of Cardioprotection  

PubMed Central

This review highlights the importance of neural mechanisms capable of protecting the heart against lethal ischemia/reperfusion injury. Increased parasympathetic (vagal) activity limits myocardial infarction, and recent data suggest that activation of autonomic reflex pathways contributes to powerful innate mechanisms of cardioprotection underlying the remote ischemic conditioning phenomena. PMID:24583769

Gourine, Alexander V.

2014-01-01

394

Neural ECM mimetics.  

PubMed

The consequence of numerous neurological disorders is the significant loss of neural cells, which further results in multilevel dysfunction or severe functional deficits. The extracellular matrix (ECM) is of tremendous importance for neural regeneration mediating ambivalent functions: ECM serves as a growth-promoting substrate for neurons but, on the other hand, is a major constituent of the inhibitory scar, which results from traumatic injuries of the central nervous system. Therefore, cell and tissue replacement strategies on the basis of ECM mimetics are very promising therapeutic interventions. Numerous synthetic and natural materials have proven effective both in vitro and in vivo. The closer a material's physicochemical and molecular properties are to the original extracellular matrix, the more promising its effectiveness may be. Relevant factors that need to be taken into account when designing such materials for neural repair relate to receptor-mediated cell-matrix interactions, which are dependent on chemical and mechanical sensing. This chapter outlines important characteristics of natural and synthetic ECM materials (scaffolds) and provides an overview of recent advances in design and application of ECM materials for neural regeneration, both in therapeutic applications and in basic biological research. PMID:25410366

Estrada, Veronica; Tekinay, Ayse; Müller, Hans Werner

2014-01-01

395

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

396

Neural Mechanisms of Emotion.  

ERIC Educational Resources Information Center

Views neural mechanisms of emotion from an evolutionary perspective, seeing them distributed across the brainstem, limbic, paralimbic, and neocortical regions. Discusses descending and ascending connections among these levels in relation to three types of emotional processes: peripheral effects on patterned bodily responses, central effects on…

Derryberry, Douglas; Tucker, Don M.

1992-01-01

397

Neural plasticity in tinnitus  

Microsoft Academic Search

Two distinctly different kinds of tinnitus occur: objective and subjective tinnitus. Objective tinnitus is caused by sounds generated in the body while subjective tinnitus is caused by abnormal neural activity that is not evoked by sound. This chapter discusses subjective tinnitus. Subjective tinnitus has many forms. In most forms of tinnitus the anatomical location of the physiological abnormality is in

Aage R. Møller

2006-01-01

398

Vangl-dependent planar cell polarity signalling is not required for neural crest migration in mammals  

PubMed Central

The role of planar cell polarity (PCP) signalling in neural crest (NC) development is unclear. The PCP dependence of NC cell migration has been reported in Xenopus and zebrafish, but NC migration has not been studied in mammalian PCP mutants. Vangl2Lp/Lp mouse embryos lack PCP signalling and undergo almost complete failure of neural tube closure. Here we show, however, that NC specification, migration and derivative formation occur normally in Vangl2Lp/Lp embryos. The gene family member Vangl1 was not expressed in NC nor ectopically expressed in Vangl2Lp/Lp embryos, and doubly homozygous Vangl1/Vangl2 mutants exhibited normal NC migration. Acute downregulation of Vangl2 in the NC lineage did not prevent NC migration. In vitro, Vangl2Lp/Lp neural tube explants generated emigrating NC cells, as in wild type. Hence, PCP signalling is not essential for NC migration in mammals, in contrast to its essential role in neural tube closure. PCP mutations are thus unlikely to mediate NC-related birth defects in humans. PMID:25038043

Pryor, Sophie E.; Massa, Valentina; Savery, Dawn; Andre, Philipp; Yang, Yingzi; Greene, Nicholas D. E.; Copp, Andrew J.

2014-01-01

399

Characterization of the Trunk Neural Crest in the bamboo shark, Chiloscyllium punctatum  

PubMed Central

The neural crest is a population of mesenchymal cells that after migrating from the neural tube give rise to a structures and cell-types: jaw, part of the peripheral ganglia and melanocytes. Although much is known about neural crest development in jawed vertebrates, a clear picture of trunk neural crest development for elasmobranchs is yet to be developed. Here we present a detailed study of trunk neural crest development in the bamboo shark, Chiloscyllium punctatum. Vital labeling with DiI and in situ hybridization using cloned Sox8 and Sox9 probes demonstrated that trunk neural crest cells follow a pattern similar to the migratory paths already described in zebrafish and amphibians. We found shark trunk neural crest along the rostral side of the somites, the ventromedial pathway, branchial arches, gut, sensory ganglia and nerves. Interestingly, Chiloscyllium punctatum Sox8 and Sox9 sequences aligned with vertebrate SoxE genes, but appeared to be more ancient than the corresponding vertebrate paralogs. The expression of these two SoxE genes in trunk neural crest cells, especially Sox9, matched the Sox10 migratory patterns observed in teleosts. Interestingly, we observed DiI cells and Sox9 labeling along the lateral line, suggesting that in C. punctatum, glial cells in the lateral line are likely of neural crest origin. Though this has been observed in other vertebrates, we are the first to show that the pattern is present in cartilaginous fishes. These findings demonstrate that trunk neural crest cell development in Chiloscyllium punctatum follows the same highly conserved migratory pattern observed in jawed vertebrates PMID:23640803

Juarez, Marilyn; Reyes, Michelle; Coleman, Tiffany; Rotenstein, Lisa; Sao, Sothy; Martinez, Darwin; Jones, Matthew; Mackelprang, Rachel; de Bellard, Maria Elena

2013-01-01

400

Defining a neural network controller structure for a rubbertuator robot.  

PubMed

Rubbertuator (Rubber-Actuator) robot arm is a pneumatic robot, unique with its lightweight, high power, compliant and spark free nature. Compressibility of air in the actuator tubes and the elastic nature of the rubber, however, are the two major sources of increased non-linearity and complexity in motion control. Soft computing, exploiting the tolerance of uncertainty and vagueness in cognitive reasoning has been offering easy to handle, robust, and low-priced solutions to several non-linear industrial applications. Nonetheless, the black-box approach in these systems results in application specific architectures with some important design parameters left for fine tuning (i.e. number of nodes in a neural network). In this study we propose a more systematic method in defining the structure of a soft computing technique, namely the backpropagation neural network, when used as a controller for rubbertuator robot systems. The structure of the neural network is based on the physical model of the robot, while the neural network itself is trained to learn the trajectory independent parameters of the model that are essential for defining the robot dynamics. The proposed system performance was compared with a well-tuned PID controller and shown to be more accurate in trajectory control for rubbertuator robots. PMID:10946398

Ozkan, M; Inoue, K; Negishi, K; Yamanaka, T

2000-01-01

401

The tight junction protein claudin-1 influences cranial neural crest cell emigration  

PubMed Central

The neural crest is a population of migratory cells that follows specific pathways during development, eventually differentiating to form parts of the face, heart, and peripheral nervous system, the latter of which includes contributions from placodal cells derived from the ectoderm. Stationary, premigratory neural crest cells acquire the capacity to migrate by undergoing an epithelial-to-mesenchymal transition that facilitates their emigration from the dorsal neural tube. This emigration involves, in part, the dismantling of cell-cell junctions, including apically localized tight junctions in the neuroepithelium. In this study, we have characterized the role of the transmembrane tight junction protein claudin-1 during neural crest and placode ontogeny. Our data indicate that claudin-1 is highly expressed in the developing neuroepithelium but is down-regulated in migratory neural crest cells, although expression persists in the ectoderm from which the placode cells arise. Depletion or overexpression of claudin-1 augments or reduces neural crest cell emigration, respectively, but does not impact the development of several cranial placodes. Taken together, our results reveal a novel function for a tight junction protein in the formation of migratory cranial neural crest cells in the developing vertebrate embryo. PMID:22771518

Fishwick, Katherine J.; Neiderer, Theresa; Jhingory, Sharon; Bronner, Marianne; Taneyhill, Lisa A.

2012-01-01

402

Hox genes: choreographers in neural development, architects of circuit organization.  

PubMed

The neural circuits governing vital behaviors, such as respiration and locomotion, are comprised of discrete neuronal populations residing within the brainstem and spinal cord. Work over the past decade has provided a fairly comprehensive understanding of the developmental pathways that determine the identity of major neuronal classes within the neural tube. However, the steps through which neurons acquire the subtype diversities necessary for their incorporation into a particular circuit are still poorly defined. Studies on the specification of motor neurons indicate that the large family of Hox transcription factors has a key role in generating the subtypes required for selective muscle innervation. There is also emerging evidence that Hox genes function in multiple neuronal classes to shape synaptic specificity during development, suggesting a broader role in circuit assembly. This Review highlights the functions and mechanisms of Hox gene networks and their multifaceted roles during neuronal specification and connectivity. PMID:24094100

Philippidou, Polyxeni; Dasen, Jeremy S

2013-10-01

403

Hox Genes: Choreographers in Neural Development, Architects of Circuit Organization  

PubMed Central

Summary The neural circuits governing vital behaviors, such as respiration and locomotion, are comprised of discrete neuronal populations residing within the brainstem and spinal cord. Work over the past decade has provided a fairly comprehensive understanding of the developmental pathways that determine the identity of major neuronal classes within the neural tube. However, the steps through which neurons acquire the subtype diversities necessary for their incorporation into a particular circuit are still poorly defined. Studies on the specification of motor neurons indicate that the large family of Hox transcription factors has a key role in generating the subtypes required for selective muscle innervation. There is also emerging evidence that Hox genes function in multiple neuronal classes to shape synaptic specificity during development, suggesting a broader role in circuit assembly. This review highlights the functions and mechanisms of Hox gene networks, and their multifaceted roles during neuronal specification and connectivity. PMID:24094100

Philippidou, Polyxeni; Dasen, Jeremy S.

2013-01-01

404

Caring for Your Percutaneous Nephrostomy Tube  

MedlinePLUS

... called an ultrasound, will be made to guide placement of the nephrostomy tube. To see your kidney ... For the first 2 weeks after nephrostomy tube placement, the sterile gauze dressing should be changed once ...

405

Performance of drift tubes under high radiation  

E-print Network

In this thesis, the aging and the rejuvenation of an ATLAS proportional drift tube are described. Firstly, the Diethorn model of gain is tested using pressure and sense-wire voltage measurements. The drift tube was then ...

Shi, Yue, S.B. Massachusetts Institute of Technology

2005-01-01

406

Fracture compliance estimation using borehole tube waves  

E-print Network

We tested two models, one for tube-wave generation and the other for tube-wave attenuation at a fracture intersecting a borehole that can be used to estimate fracture compliance, fracture aperture, and lateral extent. In ...

Bakku, Sudhish Kumar

407

Reduce - and Report - Enteral Feeding Tube Misconnections  

MedlinePLUS

... patient requiring mechanical ventilation also had a nasogastric (NG) tube in place. After being transported to another department ... high-flow oxygen was accidentally connected to the NG tube. The patient subsequently underwent emergency surgery to repair ...

408

I tube, you tube, everybody tubes: analyzing the world's largest user generated content video system  

Microsoft Academic Search

User Generated Content (UGC) is re-shaping the way people watch video and TV, with millions of video producers and consumers. In particular, UGC sites are creating new view- ing patterns and social interactions, empowering users to be more creative, and developing new business opportunities. To better understand the impact of UGC systems, we have analyzed YouTube, the world's largest UGC

Meeyoung Cha; Haewoon Kwak; Pablo Rodriguez; Yong-yeol Ahn; Sue Moon

2007-01-01

409

Stability of tube rows in crossflow. [LMFBR  

SciTech Connect

A mathematical model for the instability of tube rows subjected to crossflow is examined. The theoretical model, based on the fluid-force data for a pitch-to-diameter ratio of 1.33, provides additional insight into the instability phenomenon. Tests are also conducted for three sets of tube rows. The effects of mass ratio, tube pitch, damping, detuning and finned tubes are investigated. Theoretical results and experimental data are in good agreement.

Chen, S.S.; Jendrzejczyk, J.A.

1982-10-01

410

Hybrid digital signal processing and neural networks for automated diagnostics using NDE methods  

SciTech Connect

The primary purpose of the current research was to develop an integrated approach by combining information compression methods and artificial neural networks for the monitoring of plant components using nondestructive examination data. Specifically, data from eddy current inspection of heat exchanger tubing were utilized to evaluate this technology. The focus of the research was to develop and test various data compression methods (for eddy current data) and the performance of different neural network paradigms for defect classification and defect parameter estimation. Feedforward, fully-connected neural networks, that use the back-propagation algorithm for network training, were implemented for defect classification and defect parameter estimation using a modular network architecture. A large eddy current tube inspection database was acquired from the Metals and Ceramics Division of ORNL. These data were used to study the performance of artificial neural networks for defect type classification and for estimating defect parameters. A PC-based data preprocessing and display program was also developed as part of an expert system for data management and decision making. The results of the analysis showed that for effective (low-error) defect classification and estimation of parameters, it is necessary to identify proper feature vectors using different data representation methods. The integration of data compression and artificial neural networks for information processing was established as an effective technique for automation of diagnostics using nondestructive examination methods.

Upadhyaya, B.R.; Yan, W. [Tennessee Univ., Knoxville, TN (United States). Dept. of Nuclear Engineering

1993-11-01

411

Magnetohydrostatic Equilibrium. II. Three-dimensional Multiple Open Magnetic Flux Tubes in the Stratified Solar Atmosphere  

NASA Astrophysics Data System (ADS)

A system of multiple open magnetic flux tubes spanning the solar photosphere and lower corona is modeled 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. 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 condition for numerical studies of energy transport mechanisms from the solar surface to the corona. We apply magnetic field strength, plasma density, pressure, and temperature distributions consistent with observational and theoretical estimates for the lower solar atmosphere. Although each flux tube is identical in construction apart from the location of the radial axis, combinations can be applied to generate a non-axisymmetric magnetic field with multiple non-uniform flux tubes. This is a considerable step forward in modeling the realistic magnetized three-dimensional equilibria of the solar atmosphere.

Gent, F. A.; Fedun, V.; Erdélyi, R.

2014-07-01

412

Kundt's Tube: An Acoustic Gas Analyzer  

ERIC Educational Resources Information Center

A Kundt tube is normally used to measure the speed of sound in gases. Therefore, from known speeds of sound, a Kundt tube can be used to identify gases and their fractions in mixtures. In these experiments, the speed of sound is determined by measuring the frequency of a standing sound wave at a fixed tube length, temperature, and pressure. This…

Aristov, Natasha; Habekost, Gehsa; Habekost, Achim

2011-01-01

413

Inspecting The Full Circumferences Of Tubes  

NASA Technical Reports Server (NTRS)

Proposed tool for inspection of external welds on tube gives view of full circumferential strip of outer surface. Similar to borescopes used to inspect interiors of tubes. Instead of fitting inside tube, new tool encircles it. Inspection more reliable and less time consuming.

Geddes, John P.

1990-01-01

414

Simulating Rotary Draw Bending and Tube Hydroforming  

Microsoft Academic Search

Tube hydroforming is currently an active area of development in the automotive industry on account of the advantages it offers in comparison to other manufacturing processes presently under use to produce similar components. The majority of hydroformed tubes must be pre-bent using some bending process. Rotary draw bending is one of the most commonly used tube bending processes, incorporating the

Dilip K Mahanty; Narendran M. Balan

415

Centrifugal tube mill for finest grinding  

Microsoft Academic Search

The design and the motion behaviour of the filling of a new centrifugal tube mill are introduced. In contrast to the usual range of application for centrifugal tube mills, once developed to substitute ball mills, it is shown that centrifugal tube mills are particularly suited for pulverizing if the grinding media filling is reduced to max. 35%. This measure also

K.-E. Kurrer; E. Gock; V. Vogt; R. Florescu

2004-01-01

416

Spring/dimple instrument tube restraint  

DOEpatents

A nuclear fuel assembly for a pressurized water nuclear reactor has a spring and dimple structure formed in a non-radioactive insert tube placed in the top of a sensor receiving instrumentation tube thimble disposed in the fuel assembly and attached at a top nozzle, a bottom nozzle, and intermediate grids. The instrumentation tube thimble is open at the top, where the sensor or its connection extends through the cooling water for coupling to a sensor signal processor. The spring and dimple insert tube is mounted within the instrumentation tube thimble and extends downwardly adjacent the top. The springs and dimples restrain the sensor and its connections against lateral displacement causing impact with the instrumentation tube thimble due to the strong axial flow of cooling water. The instrumentation tube has a stainless steel outer sleeve and a zirconium alloy inner sleeve below the insert tube adjacent the top. The insert tube is relatively non-radioactivated inconel alloy. The opposed springs and dimples are formed on diametrically opposite inner walls of the insert tube, the springs being formed as spaced axial cuts in the insert tube, with a web of the insert tube between the cuts bowed radially inwardly for forming the spring, and the dimples being formed as radially inward protrusions opposed to the springs. 7 figures.

DeMario, E.E.; Lawson, C.N.

1993-11-23

417

Strong, corrosion-resistant aluminum tubing  

NASA Technical Reports Server (NTRS)

When aluminum tubing having good corrosion resistance and postweld strength is needed, type 5083 alloy should be considered. Chemical composition is carefully controlled and can be drawn into thin-wall tubing with excellent mechanical properties. Uses of tubing are in aircraft, boats, docks, and process equipment.

Reed, M. W.; Adams, F. F.

1980-01-01

418

Spring/dimple instrument tube restraint  

DOEpatents

A nuclear fuel assembly for a pressurized water nuclear reactor has a spring and dimple structure formed in a non-radioactive insert tube placed in the top of a sensor receiving instrumentation tube thimble disposed in the fuel assembly and attached at a top nozzle, a bottom nozzle, and intermediate grids. The instrumentation tube thimble is open at the top, where the sensor or its connection extends through the cooling water for coupling to a sensor signal processor. The spring and dimple insert tube is mounted within the instrumentation tube thimble and extends downwardly adjacent the top. The springs and dimples restrain the sensor and its connections against lateral displacement causing impact with the instrumentation tube thimble due to the strong axial flow of cooling water. The instrumentation tube has a stainless steel outer sleeve and a zirconium alloy inner sleeve below the insert tube adjacent the top. The insert tube is relatively non-radioactivated inconel alloy. The opposed springs and dimples are formed on diametrically opposite inner walls of the insert tube, the springs being formed as spaced axial cuts in the insert tube, with a web of the insert tube between the cuts bowed radially inwardly for forming the spring, and the dimples being formed as radially inward protrusions opposed to the springs.

DeMario, Edmund E. (Columbia, SC); Lawson, Charles N. (Columbia, SC)

1993-01-01

419

Manual tube-to-tubesheet welding torch  

DOEpatents

A welding torch made of a high temperature plastic which fits over a tube intermediate the ends thereof for welding the juncture between the tube and the back side of a tube plate and has a ballooned end in which an electrode, filler wire guide, fiber optic bundle, and blanketing gas duct are disposed.

Kiefer, Joseph H. (Tampa, FL); Smith, Danny J. (Tampa, FL)

1982-01-01

420

Inspection tool for butt-welded tubing  

NASA Technical Reports Server (NTRS)

Inspection tool for tubing consists of metal casing housing elastic collar. Collar is clamped around weld site under test. Leakage through weld is contained within chamber and is bled to detector via tubing attached to fitting. Tool, originally designed to detect fluid leakage in tubing, can be used to detect gas leaks.

Horman, D. P.

1977-01-01

421

Studies of Degraded Smelt Spout Opening Tubes  

SciTech Connect

Co-extruded type 304L stainless steel/SA210 carbon steel tubes have been used on the floors and lower walls of many black liquor recovery boilers to address the wall thinning problem that had been an issue for boiler owners and operators. Use of these tubes greatly reduced the corrosion issue, but corrosion was still sometimes observed and cracking was discovered in some tubes, particularly those that are bent to form the openings for smelt spouts. Because cracks in the opening tubes were sometimes observed to extend a significant distance into the tube wall and because these cracks were found fairly frequently, tubes made from a number of alternate cladding materials were tried in place of the 304L clad opening tubes. This paper describes the results of examinations of spout opening tubes of the standard 304L/carbon steel and of several of the alternate materials that have been tried. In addition to the corrosion and cracking seen in the spout opening tubes, another issue associated with these tubes has been observed. Preferential corrosion of the cap welds is sometimes seen on butt welds attaching the spout opening tubes made with alternate cladding materials to the standard 304L/carbon steel co-extruded wall tubes. Some information on the observations of this corrosion is also included in this paper.

Keiser, James R [ORNL; Kish, Joseph R. [Paprican; Willoughby, Adam W [ORNL; Longmire, Hu Foster [ORNL; Singbeil, Douglas [Paprican

2007-01-01

422

Acoustic target detection and classification using neural networks  

NASA Technical Reports Server (NTRS)

A neural network approach to the classification of acoustic emissions of ground vehicles and helicopters is demonstrated. Data collected during the Joint Acoustic Propagation Experiment conducted in July of l991 at White Sands Missile Range, New Mexico was used to train a classifier to distinguish between the spectrums of a UH-1, M60, M1 and M114. An output node was also included that would recognize background (i.e. no target) data. Analysis revealed specific hidden nodes responding to the features input into the classifier. Initial results using the neural network were encouraging with high correct identification rates accompanied by high levels of confidence.

Robertson, James A.; Conlon, Mark

1993-01-01

423

Peculiar arcuate scotoma in pathologic myopia—optical coherence tomography to detect peripapillary neural tissue loss over the disc crescent  

Microsoft Academic Search

Background: Optical co- herence tomography (OCT) was used to detect peripapillary neural tissue loss (PPNTL) over the disc crescent in pathologic myopia. The retinal neural tissue loss located inside the disc crescent in pathologic myopia is a newly recognized fundus lesion. Methods: Review of ten eyes of ten patients with peripapillary yellowish- white retinal lesions who underwent OCT for evaluation

Tzyy-Chang Ho; Yung-Feng Shih; Szu-Yung Lin; Luke L.-K. Lin; Muh-Shy Chen

2005-01-01

424

Latex Tubing and Hybrid Vehicles  

NSDL National Science Digital Library

The learning of linear functions is pervasive in most algebra classrooms. Linear functions are vital in laying the foundation for understanding the concept of modeling. This unit gives students the opportunity to make use of linear models in order to make predictions based on real-world data, and see how engineers address incredible and important design challenges through the use of linear modeling. Student groups act as engineering teams by conducting experiments to collect data and model the relationship between the wall thickness of the latex tubes and their corresponding strength under pressure (to the point of explosion). Students learn to graph variables with linear relationships and use collected data from their designed experiment to make important decisions regarding the feasibility of hydraulic systems in hybrid vehicles and the necessary tube size to make it viable.

2014-09-18

425

ATLS: Catheter and tube placement  

NASA Technical Reports Server (NTRS)

The specific objectives of this experiment are: to evaluate the rack mounted equipment and medical supplies necessary for medical procedures; to evaluate the attachments, mounting points, and inner drawer assemblies for the medical supplies; and to evaluate the procedures for performing medical scenarios. The resources available in the HMF miniracks to accomplish medical scenarios and/or procedures include: medical equipment mounted in the racks; a patch panel with places to attach tubing and catheters; self contained drawers full of critical care medical supplies; and an ALS 'backpack' for deploying supplies. The attachment lines, tubing and associated medical supplies will be deployed and used with the equipment and a patient mannequin. Data collection is provided by direct observations by the inflight experimenters, and analysis of still and video photography.

Gosbee, John; Krupa, Debra T.; Pepper, L.; Orsak, Debra

1991-01-01

426

Ketamine improves nasogastric tube insertion  

Microsoft Academic Search

ObjectivesNasogastric (NG) intubation is one of the most common procedures performed in the emergency department (ED) and other hospital settings. The aim of this study was to compare the level of pain during NG tube insertion in groups receiving local ketamine plus water-soluble lubricating gel and water-soluble lubricating gel alone (the latter is the common practice in our hospital). It

Amir Nejati; Keihan Golshani; Maziar Moradi Lakeh; Patricia Khashayar; Reza Shariat Moharari

2010-01-01

427

Hydatid cyst of fallopian tube.  

PubMed

Echinococcosis is a common disease in the Middle East region and is in the differential diagnosis of cystic lesions in patients of this area. Liver and lung are commonly involved. Infection of unusual sites can cause difficulties in diagnosis. Here, we present a patient with echinococcal cyst of the fallopian tube. She had abdominal pain and a cystic lesion in adnexa was found by imaging. She underwent surgery and diagnosis of echinococcosis was established. PMID:25364612

Jafarian, A; Fakhar, N; Parsaei, R

2014-09-01

428

Cold cathode vacuum discharge tube  

DOEpatents

A cold cathode vacuum discharge tube, and method for making same, with an interior surface of the trigger probe coated with carbon deposited by carbon vapor deposition (CVD) or diamond-like carbon (DLC) deposition. Preferably a solid graphite insert is employed in the probe-cathode structure in place of an aluminum bushing employed in the prior art. The CVD or DLC probe face is laser scribed to allow resistance trimming to match available trigger voltage signals and to reduce electrical aging.

Boettcher, Gordon E. (Albuquerque, NM)

1998-01-01

429

Beam induced backgrounds: CDF experience  

SciTech Connect

We summarize the experiences of the Collider Detector at Fermilab (CDF) experiment in the presence of backgrounds originating from the counter circulating beams in the Fermilab Tevatron. These backgrounds are measured and their sources identified. Finally, we outline the strategies employed to reduce the effects of these backgrounds on the experiment.

Tesarek, R.J.; /Fermilab

2008-05-01

430

21 CFR 870.4390 - Cardiopulmonary bypass pump tubing.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 false Cardiopulmonary bypass pump tubing. 870.4390 Section 870.4390... § 870.4390 Cardiopulmonary bypass pump tubing. (a) Identification. A cardiopulmonary bypass pump tubing is polymeric tubing which is...

2010-04-01

431

21 CFR 888.4230 - Cement ventilation tube.  

Code of Federal Regulations, 2012 CFR

...2012-04-01 2012-04-01 false Cement ventilation tube. 888.4230 Section 888.4230...Surgical Devices § 888.4230 Cement ventilation tube. (a) Identification. A cement ventilation tube is a tube-like device...

2012-04-01

432

21 CFR 888.4230 - Cement ventilation tube.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 2013-04-01 false Cement ventilation tube. 888.4230 Section 888.4230...Surgical Devices § 888.4230 Cement ventilation tube. (a) Identification. A cement ventilation tube is a tube-like device...

2013-04-01

433

21 CFR 888.4230 - Cement ventilation tube.  

...2014-04-01 2014-04-01 false Cement ventilation tube. 888.4230 Section 888.4230...Surgical Devices § 888.4230 Cement ventilation tube. (a) Identification. A cement ventilation tube is a tube-like device...

2014-04-01

434

21 CFR 888.4230 - Cement ventilation tube.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Cement ventilation tube. 888.4230 Section 888.4230...Surgical Devices § 888.4230 Cement ventilation tube. (a) Identification. A cement ventilation tube is a tube-like device...

2010-04-01

435

21 CFR 888.4230 - Cement ventilation tube.  

Code of Federal Regulations, 2011 CFR

...2011-04-01 2011-04-01 false Cement ventilation tube. 888.4230 Section 888.4230...Surgical Devices § 888.4230 Cement ventilation tube. (a) Identification. A cement ventilation tube is a tube-like device...

2011-04-01

436

Tech Trek: TeacherTube for Science  

NSDL National Science Digital Library

Following in the footsteps of YouTube, TeacherTube is a website where teachers can access a trove of videos that can be used in the classroom to improve instruction. The inclusion of YouTube as a venue in the presidential debates of 2008 has brought a level of legitimacy and recognition to this kind of electronic meeting place, and TeacherTube is similarly being acknowledged as a rich web resource of particular interest to science teachers. This article describes how to you can utilize TeacherTube in your science classroom, and explains how you can contribute to the collection with a video of your own.

Lucking, Robert A.; Wighting, Mervyn A.; Christmann, Edwin P.

2009-04-01

437

Numerical evaluation of alternate tube configurations for particle deposition rate reduction in heat exchanger tube bundles  

Microsoft Academic Search

The potential of two passive techniques, namely elliptic-shaped tubes and asymmetric tube bundle arrangement, for deposition rate reduction in lignite-fired utility boiler heat exchangers is numerically studied through comparison with an in-line tube arrangement with circular tubes. The simulation is based on a two-dimensional calculation of the turbulent two-phase flow in heat exchanger tube bundles using a subgrid-scale model for

D. Bouris; G. Papadakis; G. Bergeles

2001-01-01

438

Neural network technologies  

NASA Technical Reports Server (NTRS)

A whole new arena of computer technologies is now beginning to form. Still in its infancy, neural network technology is a biologically inspired methodology which draws on nature's own cognitive processes. The Software Technology Branch has provided a software tool, Neural Execution and Training System (NETS), to industry, government, and academia to facilitate and expedite the use of this technology. NETS is written in the C programming language and can be executed on a variety of machines. Once a network has been debugged, NETS can produce a C source code which implements the network. This code can then be incorporated into other software systems. Described here are various software projects currently under development with NETS and the anticipated future enhancements to NETS and the technology.

Villarreal, James A.

1991-01-01

439

Arrested neural and advanced mesenchymal differentiation of glioblastoma cells-comparative study with neural progenitors  

PubMed Central

Background Although features of variable differentiation in glioblastoma cell cultures have been reported, a comparative analysis of differentiation properties of normal neural GFAP positive progenitors, and those shown by glioblastoma cells, has not been performed. Methods Following methods were used to compare glioblastoma cells and GFAP+NNP (NHA): exposure to neural differentiation medium, exposure to adipogenic and osteogenic medium, western blot analysis, immunocytochemistry, single cell assay, BrdU incorporation assay. To characterize glioblastoma cells EGFR amplification analysis, LOH/MSI analysis, and P53 nucleotide sequence analysis were performed. Results In vitro differentiation of cancer cells derived from eight glioblastomas was compared with GFAP-positive normal neural progenitors (GFAP+NNP). Prior to exposure to differentiation medium, both types of cells showed similar multilineage phenotype (CD44+/MAP2+/GFAP+/Vimentin+/Beta III-tubulin+/Fibronectin+) and were positive for SOX-2 and Nestin. In contrast to GFAP+NNP, an efficient differentiation arrest was observed in all cell lines isolated from glioblastomas. Nevertheless, a subpopulation of cells isolated from four glioblastomas differentiated after serum-starvation with varying efficiency into derivatives indistinguishable from the neural derivatives of GFAP+NNP. Moreover, the cells derived from a majority of glioblastomas (7 out of 8), as well as GFAP+NNP, showed features of mesenchymal differentiation when exposed to medium with serum. Conclusion Our results showed that stable co-expression of multilineage markers by glioblastoma cells resulted from differentiation arrest. According to our data up to 95% of glioblastoma cells can present in vitro multilineage phenotype. The mesenchymal differentiation of glioblastoma cells is advanced and similar to mesenchymal differentiation of normal neural progenitors GFAP+NNP. PMID:19216795

2009-01-01

440

Neural Correlates of Sympathy  

E-print Network

CORRELATES OF SYMPATHY iii ABSTRACT Neural Correlates of Sympathy. (April 2009) Laura Christine Gravens Department of Psychology Texas A&M University Research Advisor: Dr. Eddie Harmon-Jones Department of Psychology Sympathy has not been.... 20 CONTACT INFORMATION Name: Laura Christine Gravens Professional Address: c/o Dr. Eddie Harmon Jones Department of Psychology Texas A&M University College Station, TX 77843-4235 Email Address: lauragravens@gmail.com Education: B...

Gravens, Laura

2011-01-11

441

Quantum Neural Nets  

NASA Technical Reports Server (NTRS)

The capacity of classical neurocomputers is limited by the number of classical degrees of freedom which is roughly proportional to the size of the computer. By Contrast, a Hypothetical quantum neurocomputer can implement an exponentially large number of the degrees of freedom within the same size. In this paper an attempt is made to reconcile linear reversible structure of quantum evolution with nonlinear irreversible dynamics for neural nets.

Zak, Michail; Williams, Colin P.

1997-01-01

442

Modeling Orifice Pulse Tube Coolers  

NASA Technical Reports Server (NTRS)

We have developed a calculational model that treats all the components of an orifice pulse tube cooler. We base our analysis on 1-dimensional thermodynamic equations for the regenerator and we assume that all mass flows, pressure oscillations and temperature oscillations are small and sinusoidal. Non-linear pressure drop effects are included in the regenerator to account for finite pressure amplitude effects. The resulting mass flows and pressures are matched at the boundaries with the other components of the cooler: compressor, aftercooler, cold heat exchanger, pulse tube, hot heat exchanger, orifice and reservoir. The results of the calculation are oscillating pressures, mass flows and enthalpy flows in the main components of the cooler. By comparing with the calculations of other available models, we show that our model is very similar to REGEN 3 from NIST and DeltaE from Los Alamos National Lab. Our model is much easier to use than other available models because of its simple graphical interface and the fact that no guesses are required for the operating pressures or mass flows. In addition, the model only requires a few minutes of running time allowing many parameters to be optimized in a reasonable time. A version of the model is available for use over the World Wide Web at http://irtek.arc.nasa.gov. Future enhancements include adding a bypass orifice and including second order terms in steady mass streaming and steady heat transfer. A two-dimensional anelastic approximation of the fluid equations will be used as the basis for the latter analysis. Preliminary results are given in dimensionless numbers appropriate for oscillating compressible flows. The model shows how transverse heat transfer reduces enthalpy flow, particularly for small pulse tubes. The model also clearly shows mass recirculation in the open tube on the order of the tube length. They result from the higher order Reynolds stresses. An interesting result of the linearized approach is that the steady mass streaming does not affect the enthalpy flow at second order. The major effect of recirculating mass streaming is to increase transverse temperature gradients, which leads to higher entropy production and reduced efficiency.

Roach, Kittel P.; Roach, P. R.; Lee, J. M.; Kashani, A.; McCreight, Craig R. (Technical Monitor)

1996-01-01

443

The Experiences of Patients With Advanced Head and Neck Cancer With a Percutaneous Endoscopic Gastrostomy Tube: A Qualitative Descriptive Study.  

PubMed

Background: While the percutaneous endoscopic gastrostomy (PEG) tube has become an established part of the management regimen for patients with head and neck cancer (HNCA) with impaired nutrition and functional status, limited research has explored the impact and experiences of living with a PEG tube from the patient's perspective. This qualitative study serves as a follow-up investigation undertaken to describe the experiences of patients with advanced HNCA living with a PEG tube. Materials and Methods: Eligible patients from convenience sampling were invited to participate until data saturation was reached. In-depth interviews were conducted with consenting participants. Qualitative descriptive design guided the content analysis of the interview transcripts. Results: Of the 49 patients invited, a total of 15 participants' interviews were transcribed and analyzed. Each interview was 15-90 minutes in length. Four of 22 content codes were chosen to describe the overarching ideas of the progressive experience of a patient's journey from the initial decision-making process around tube insertion through to its removal. Difficulty swallowing and weight loss emerged as primary factors for PEG tube insertion, and all participants became accustomed to living with the tube. Resuming a complete oral diet was a gradual transition. All participants recognized the value of the tube, and most acknowledged its necessity for their survival. Conclusions: Results describe the overall PEG tube experience as a dichotomy. While there were issues with the PEG tube, all participants found the tube to be beneficial. This study provides invaluable insight from a practice perspective. PMID:24871492

Kwong, Janna P Y; Stokes, Edith J; Posluns, Elaine C; Fitch, Margaret I; McAndrew, Alison; Vandenbussche, Katherine A

2014-05-28

444

Background issues for defensive interceptors  

SciTech Connect

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 motions and backgrounds give signal to clutter ratios too low to be useful. Clutter leakage due to line-of-sight drift can be reduced by stabilizing the line of sight around the background clutter itself. Current interceptors have detector arrays large enough for operation independent of nuclear backgrounds in their fields of view. 6 refs., 2 figs.

Canavan, G.H.

1991-03-01

445

Gastroenteric tube feeding: Techniques, problems and solutions  

PubMed Central

Gastroenteric tube feeding plays a major role in the management of patients with poor voluntary intake, chronic neurological or mechanical dysphagia or gut dysfunction, and patients who are critically ill. However, despite the benefits and widespread use of enteral tube feeding, some patients experience complications. This review aims to discuss and compare current knowledge regarding the clinical application of enteral tube feeding, together with associated complications and special aspects. We conducted an extensive literature search on PubMed, Embase and Medline using index terms relating to enteral access, enteral feeding/nutrition, tube feeding, percutaneous endoscopic gastrostomy/jejunostomy, endoscopic nasoenteric tube, nasogastric tube, and refeeding syndrome. The literature showed common routes of enteral access to include nasoenteral tube, gastrostomy and jejunostomy, while complications fall into four major categories: mechanical, e.g., tube blockage or removal; gastrointestinal, e.g., diarrhea; infectious e.g., aspiration pneumonia, tube site infection; and metabolic, e.g., refeeding syndrome, hyperglycemia. Although the type and frequency of complications arising from tube feeding vary considerably according to the chosen access route, gastrointestinal complications are without doubt the most common. Complications associated with enteral tube feeding can be reduced by careful observance of guidelines, including those related to food composition, administration rate, portion size, food temperature and patient supervision. PMID:25024606

Blumenstein, Irina; Shastri, Yogesh M; Stein, Jürgen

2014-01-01

446

Gastroenteric tube feeding: techniques, problems and solutions.  

PubMed

Gastroenteric tube feeding plays a major role in the management of patients with poor voluntary intake, chronic neurological or mechanical dysphagia or gut dysfunction, and patients who are critically ill. However, despite the benefits and widespread use of enteral tube feeding, some patients experience complications. This review aims to discuss and compare current knowledge regarding the clinical application of enteral tube feeding, together with associated complications and special aspects. We conducted an extensive literature search on PubMed, Embase and Medline using index terms relating to enteral access, enteral feeding/nutrition, tube feeding, percutaneous endoscopic gastrostomy/jejunostomy, endoscopic nasoenteric tube, nasogastric tube, and refeeding syndrome. The literature showed common routes of enteral access to include nasoenteral tube, gastrostomy and jejunostomy, while complications fall into four major categories: mechanical, e.g., tube blockage or removal; gastrointestinal, e.g., diarrhea; infectious e.g., aspiration pneumonia, tube site infection; and metabolic, e.g., refeeding syndrome, hyperglycemia. Although the type and frequency of complications arising from tube feeding vary considerably according to the chosen access route, gastrointestinal complications are without doubt the most common. Complications associated with enteral tube feeding can be reduced by careful observance of guidelines, including those related to food composition, administration rate, portion size, food temperature and patient supervision. PMID:25024606

Blumenstein, Irina; Shastri, Yogesh M; Stein, Jürgen

2014-07-14

447

Evaluation of GTA tube welding techniques  

SciTech Connect

In this study, various tube weld joint designs are evaluated for use with manual welding techniques and automatic tube welding heads. Manual welds were made with three joint types: square butt with no filler metal addition, square butt with manual filler wire addition, and square butt with tube weld fittings designed for use with automatic tube welding heads. Automatic welding was conducted using procedures for three joint types: square butt with no filler wire addition, square butt with type ''C'' tube weld fittings, and square butt with type ''P'' tube weld fittings. While tube welds of good quality can be made without using automatic welding equipment, the welder must be highly skilled and practiced. Automatic tube welding equipment drastically reduces the level of skill required of the welding operator. Further skill reductions can be made when tube weld fittings designed for use with automatic equipment are used. The fittings provide a means for accurate positioning of the tube ends. In the case of the type ''P'' fitting, mechanized welding heads are automatically positioned by a special locating rib on the fitting. Fittings also simplify manual welding procedures with the tube end alignment feature. This is particulary advantageous in limited access situations where visibility is restricted.

Marburger, S.J.

1986-10-01

448

Shannon Wavelet Chaotic Neural Networks  

Microsoft Academic Search

Chaotic neural networks have been proved to be strong tools to solve the optimization problems. In order to escape the local\\u000a minima, a new chaotic neural network model called Shannon wavelet chaotic neural network was presented. The activation function\\u000a of the new model is non-monotonous, which is composed of sigmoid and Shannon wavelet. First, the figures of the reversed bifurcation

Yao-qun Xu; Ming Sun; Ji-hong Shen

2006-01-01

449

Cable damping effects on thin tubes  

SciTech Connect

There are many thin tubes in nuclear power plants. Thin tubes, which are vertically supported at the top, tend to have low natural frequency and low damping ability. They may respond strongly to severe earthquakes. If a cable is connected to the bottom end of the tube, it is expected that the cable will affect the tube's response characteristics, possibly and probably decreasing the response. Therefore, in order to clarify the problems, the authors established a typical thin-tube model and studied, experimentally and analytically, the suspended cable effect on tube response. The natural frequency of the model is approx. 1 Hz. The cable is connected to the bottom end of the tube and the other end is fixed on the upper support. The cable itself has very low natural frequency and extensive damping capability. Its vibration characteristics can be changed by changing cable conditions.

Naruse, K.; Watanabe, Y.; Ozaki, O.

1987-01-01

450

Minimum wear tube support hole design  

DOEpatents

A minimum-wear through-bore (16) is defined within a heat exchanger tube support plate (14) so as to have an hourglass configuration as determined by means of a constant radiused surface curvature (18) as defined by means of an external radius (R3), wherein the surface (18) extends between the upper surface (20) and lower surface (22) of the tube support plate (14). When a heat exchange tube (12) is disposed within the tube support plate (14) so as to pass through the through-bore (16), the heat exchange tube (12) is always in contact with a smoothly curved or radiused portion of the through-bore surface (16) whereby unacceptably excessive wear upon the heat exchange tube (12), as normally developed by means of sharp edges, lands, ridges, or the like conventionally part of the tube support plates, is eliminated or substantially reduced.

Glatthorn, Raymond H. (St. Petersburg, FL)

1986-01-01

451

Foundations of fuzzy neural networks  

NASA Astrophysics Data System (ADS)

Over the last decade or so, significant advances have been made in two distinct areas: fuzzy logic and computational neural networks. The theory of fuzzy logic provides mathematical strength to compare the uncertainties associated with human cognitive processes, such as thinking and reasoning. Also, it provides a mathematical morphology to emulate certain perceptual and linguistic attributes associated with human cognition. On the other hand, the computational neural network paradigm has evolved in the process of understanding the incredible learning and adaptability of biological neural mechanisms. Neural networks replicate, on a small scale, some of the computational operations observed in biological learning and adaptation. The integration of these two fields, fuzzy logic and neural networks, has given birth to an emerging paradigm--the fuzzy neural networks. The fuzzy neural networks have the potential to capture the benefits of the two fascinating fields, fuzzy logic and neural networks, into a single capsule. The intent of this paper is to provide an introductory look at this emerging research field of fuzzy neural networks.

Gupta, Madan M.; Rao, Dandina H.

1993-12-01

452

Perception of speech in noise: neural correlates.  

PubMed

The presence of irrelevant auditory information (other talkers, environmental noises) presents a major challenge to listening to speech. The fundamental frequency (F(0)) 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 F(0). Motivated by recent findings that music and language experience enhance brainstem representation of sound, we examined the hypothesis that brainstem encoding of the F(0) is diminished to a greater degree by background noise in people with poorer perceptual abilities in noise. To this end, we measured speech-evoked auditory brainstem responses to /da/ in quiet and two multitalker babble conditions (two-talker and six-talker) in native English-speaking young adults who ranged in their ability to perceive and recall SIN. Listeners who were poorer performers on a standardized SIN measure demonstrated greater susceptibility to the degradative effects of noise on the neural encoding of the F(0). Particularly diminished was their phase-locked activity to the fundamental frequency in the portion of the syllable known to be most vulnerable to perceptual disruption (i.e., the formant transition period). Our findings suggest that the subcortical representation of the F(0) in noise contributes to the perception of speech in noisy conditions. PMID:20681749

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

2011-09-01

453

Developmental Outcomes after Early or Delayed Insertion of Tympanostomy Tubes  

PubMed Central

BACKGROUND To prevent later developmental impairments, myringotomy with the insertion of tympanostomy tubes has often been undertaken in young children who have persistent otitis media with effusion. We previously reported that prompt as compared with delayed insertion of tympanostomy tubes in children with persistent effusion who were younger than three years of age did not result in improved developmental outcomes at three or four years of age. However, the effect on the outcomes of school-age children is unknown. METHODS We enrolled 6350 healthy infants younger than 62 days of age and evaluated them regularly for middle-ear effusion. Before three years