bluuebunny/crossref_metadata_2025 huggingface dataset:
Pluripotency Associated Genes Are Reactivated by Chromatin-Modifying Agents in Neurosphere Cells
Authors: Ruau David , Ensenat-Waser Roberto , Dinger Timo C. , Vallabhapurapu Duttu S. , Rolletschek Alexandra , Hacker Christine , Hieronymus Thomas , Wobus Anna M. , Müller Albrecht M. , Zenke Martin
Published: January 2008

Chromatin architecture in stem cells determines the pattern of gene expression and thereby cell identity and fate. The chromatin-modifying agents trichostatin A (TSA) and 5-Aza-2′-deoxycytidine (AzaC) affect histone acetylation and DNA methylation, respectively, and thereby influence chromatin structure and gene expression. In our previous work, we demonstrated that TSA/AzaC treatment of neurosphere cells induces hematopoietic activity in vivo that is long-term, multilineage, and transplantable. Here, we have analyzed the TSA/AzaC-induced changes in gene expression by global gene expression profiling. TSA/AzaC caused both up- and downregulation of genes, without increasing the total number of expressed genes. Chromosome analysis showed no hot spot of TSA/AzaC impact on a particular chromosome or chromosomal region. Hierarchical cluster analysis revealed common gene expression patterns among neurosphere cells treated with TSA/AzaC, embryonic stem (ES) cells, and hematopoietic stem cells. Furthermore, our analysis identified several stem cell genes and pluripotency-associated genes that are induced by TSA/AzaC in neurosphere cells, including Cd34, Cd133, Oct4, Nanog, Klf4, Bex1, and the Dppa family members Dppa2, 3, 4, and 5. Sox2 and c-Myc are constitutively expressed in neurosphere cells. We propose a model in which TSA/AzaC, by removal of epigenetic inhibition, induces the reactivation of several stem cell and pluripotency-associated genes, and their coordinate expression enlarges the differentiation potential of somatic precursor cells.

Disclosure of potential conflicts of interest is found at the end of this article.
A Key Role for Telomerase Reverse Transcriptase Unit in Modulating Human Embryonic Stem Cell Proliferation, Cell Cycle Dynamics, and In Vitro Differentiation
Authors: Yang Chunbo , Przyborski Stefan , Cooke Michael J. , Zhang Xin , Stewart Rebecca , Anyfantis George , Atkinson Stuart P. , Saretzki Gabriele , Armstrong Lyle , Lako Majlinda
Published: January 2008

Embryonic stem cells (ESC) are a unique cell population with the ability to self-renew and differentiate into all three germ layers. Human ESC express the telomerase reverse transcriptase (TERT) gene and the telomerase RNA (TR) and show telomerase activity, but TERT, TR, and telomerase are all downregulated during the differentiation process. To examine the role of telomerase in human ESC self-renewal and differentiation, we modulated the expression of TERT. Upregulation of TERT and increased telomerase activity enhanced the proliferation and colony-forming ability of human ESC, as well as increasing the S phase of the cell cycle at the expense of a reduced G1 phase. Upregulation of TERT expression was associated with increases in CYCLIN D1 and CDC6 expression, as well as hyperphosphorylation of RB. The differentiated progeny of control ESC showed shortening of telomeric DNA as a result of loss of telomerase activity. In contrast, the differentiated cells from TERT-overexpressing ESC maintained high telomerase activity and accumulated lower concentrations of peroxides than wild-type cells, implying greater resistance to oxidative stress. Although the TERT-overexpressing human ESC are able to form teratoma composed of three germ layers in vivo, their in vitro differentiation to all primitive and embryonic lineages was suppressed. In contrast, downregulation of TERT resulted in reduced ESC proliferation, increased G1, and reduced S phase. Most importantly, downregulation of TERT caused loss of pluripotency and human ESC differentiation to extraembryonic and embryonic lineages. Our results indicate for the first time an important role for TERT in the maintenance of human ESC pluripotency, cell cycle regulation, and in vitro differentiation capacity.

Disclosure of potential conflicts of interest is found at the end of this article.
Researching “Black” Educational Experiences and Outcomes: Theoretical and Methodological Considerations
Authors: O’Connor Carla , Lewis Amanda , Mueller Jennifer
Published: January 2008

This article delineates how race has been undertheorized in research on the educational experiences and outcomes of Blacks. The authors identify two dominant traditions by which researchers have invoked race (i.e., as culture and as a variable) and outline their conceptual limitations. They analyze how these traditions mask the heterogeneity of the Black experience, underanalyze institutionalized productions of race and racial discrimination, and confound causes and effects in estimating when and how race is “significant.” The authors acknowledge the contributions of more recent scholarship and discuss how future studies of Black achievement might develop more sophisticated conceptualizations of race to inform more rigorous methodological examinations of how, when, and why Black students perform in school as they do.
Pedagogies for the Poor? Realigning Reading Instruction for Low-Income Students With Scientifically Based Reading Research
Authors: Cummins Jim
Published: January 2008

In this article, the author argues that there is minimal scientific support for the pedagogical approaches promoted for low-income students in the federal Reading First initiative. In combination with high-stakes testing, the interpretation of the construct systematic phonics instruction in Reading First has resulted in highly teacher-centered and inflexible classroom environments. By privileging these approaches, Reading First ignored the National Reading Panel’s finding that systematic phonics instruction was unrelated to reading comprehension for low-achieving and normally achieving students beyond Grade 1. Also ignored was the significant body of research suggesting that reading engagement is an important predictor of achievement. Alternative evidence-based directions for rebalancing reading instruction for low-income students are suggested in the context of the impending reauthorization of the No Child Left Behind legislation.
Preferences for Headlight Swivel Angles at Curves on Rural Two-Lane Highways
Authors: Hagiwara Toru , Morishita Masahiko , Horii Yasuhiko , Miki Katsunori , Ohshima Issei
Published: January 2008

Drivers' preferences for headlight swivel angles were investigated as a function of curve alignment and assessment point before the curve section. In a field experiment using a test vehicle at the test track of the Denso Abashiri Test Center in Hokkaido, Japan, 33 young drivers were surveyed on their headlight swivel-angle preference at three assessment points before each curve. The subjects stopped at each assessment point and selected the preferred low-beam swivel angle from the swivel angles presented. Curve alignment and assessment point were found to have a marked effect on preferred swivel angle. A multiple regression model was developed for estimating optimal swivel angles. It was found that headlight swivel should be predictive toward assisting the driver's judgment of curve sharpness before the curve section. In the near future, headlight swivel systems incorporating a dynamic algorithm should be able to predict the road geometry before arrival at the curve, with the aid of commercial car navigation systems.
Tanks and Pressure Vessels, Layered Vessels
Authors: Jawad Maan , Shah Manesh , Zhu Guohui
Published: January 2008

Pressure vessels in today's chemical plants are employed in a variety of services such as reactors, heat exchangers, storage tanks, waste heat boilers, high pressure fluid reservoirs for heavy mechanical presses, and for storage of rocket propellants. They are also used in traditional and nuclear power plants. Fabrication technologies using thick hot rolled‐welded or bent‐welded steel plate and thick segment forge‐welded steel in a single layer and thin steel plate wrapped welded and fitted in multilayers, and wound steel ribbon or carbon filament are procedures used for major vessels. Reactors for certain processes require anticorrosive layers inside the vessels with the ability for detection of failure in the layer. Special steel is needed for use at high temperatures in the petroleum hydrogenation reactors. This article discusses the fabrication of such vessels and new technologies that have been developed in China and Germany. ASME codes for construction are given as well as details on ASME approved materials. Advantages of ribbon winding and details of fabrication are discussed. Thick steel plate rolled welded and ribbon wound vessel technologies are compared. New developments include, eg, the use of graphite filaments or ribbons in fuel cells for automobiles, and layered vessels for use in long distance transport pipe and storage tanks. Use of the German U‐grooved technology is combined with Chinese technology. Applications for this technology include in vessels for ammonia plants, methanol plants, petrochemical plants, in fluid storage tanks, urea reactors, hydrogen storage tanks, and hot wall hydrogenation reactors. Leak monitoring is important and addressed. Professional organizations important to the pressure vessel technologies are listed.
On the meaning of meaning when being mean: commentary on Berkowitz's “On the Consideration of Automatic as Well as Controlled Psychological Processes in Aggression”
Authors: Dodge Kenneth A.
Published: January 2008

Berkowitz (this issue) makes a cogent case for his cognitive neo‐associationist (CNA) model that some aggressive behaviors occur automatically, emotionally, and through conditioned association with other stimuli. He also proposes that they can occur without “processing,” that is, without meaning. He contrasts his position with that of social information processing (SIP) models, which he casts as positing only controlled processing mechanisms for aggressive behavior. However, both CNA and SIP models posit automatic as well as controlled processes in aggressive behavior. Most aggressive behaviors occur through automatic processes, which are nonetheless rule governed. SIP models differ from the CNA model in asserting the essential role of meaning (often through nonconscious, automatic, and emotional processes) in mediating the link between a stimulus and an angry aggressive behavioral response. Aggr. Behav. 34:133–135, 2008. © 2008 Wiley‐Liss, Inc.
Two‐phase flow in structured packings: Modeling and calculation on a macroscopic scale
Authors: Mahr B. , Mewes D.
Published: January 2008

A model is presented that allows calculating the macroscopic flow field of counter‐current two‐phase flow in strongly anisotropic porous structures. It is applied to corrugated structured packings. All flow field variables and packing properties are averaged over the volume of an elementary cell. The anisotropic gas flow resistance is derived from measurements and from separate CFD calculations on 3D‐X‐ray CT scans. The liquid's flow resistance is calculated using an analytical model of liquid film flow on an inclined plate. Liquid flow along both preferential flow directions is represented by two separate phases, in order to consider horizontal forces despite their symmetry. Gas‐liquid momentum transfer above the loading point is included. The macroscopic flow field is calculated for a 288 mm I.D. column containing four packing elements. Liquid spreading from a point source, for uniform irrigation, increased hold‐up at the packing elements' joints and pressure drop are tested against experimental results. © 2008 American Institute of Chemical Engineers AIChE J, 2008
Ancestral links of Chesapeake Bay region African Americans to specific Bight of Bonny (West Africa) microethnic groups and increased frequency of aggressive breast cancer in both regions
Authors: Jackson Fatimah L. C.
Published: January 2008

The high frequency of aggressive, early onset, and highly fatal breast cancer among Chesapeake Bay region African Americans suggests that there may be a contributing ancestral component. This study identifies the region's founding African, European, and Native American Indian populations using ethnogenetic layering and identifies the microethnic substructure of each founding continental aggregate. The largest component (38%) of the enslaved Africans brought to the Chesapeake Bay originally came from the coastal and hinterlands of the Bight of Bonny, a region with very high rates of aggressive, early onset breast cancer. Ethnogenetic layering is applied a second time to reveal the microethnic groups of the Bight of Bonny hinterlands with historical links to the Chesapeake Bay region. These analyses identify the specific microethnic groups within this region of Africa that may be the sources of relevant polymorphisms contributing to the etiology of aggressive breast cancer in the Chesapeake Bay. This report suggests a historical link between specific African microethnic groups and a US health disparity. Am. J. Hum. Biol., 2008. © 2008 Wiley‐Liss, Inc.
Progressive cerebral vascular degeneration with mitochondrial encephalopathy
Authors: Longo Nicola , Schrijver Iris , Vogel Hannes , Pique Lynn M. , Cowan Tina M. , Pasquali Marzia , Steinberg Gary K. , Hedlund Gary L. , Ernst Sharon L. , Gallagher Renata C. , Enns Gregory M.
Published: January 2008

MELAS (mitochondrial encephalopathy with lactic acidosis and stroke‐like episodes) is a maternally inherited disorder characterized by recurrent cerebral infarctions that do not conform to discreet vascular territories. Here we report on a patient who presented at 7 years of age with loss of consciousness and severe metabolic acidosis following vomiting and dehydration. She developed progressive sensorineural hearing loss, myopathy, ptosis, short stature, and mild developmental delays after normal early development. Biochemical testing identified metabolites characteristic of medium‐chain acyl‐CoA dehydrogenase (MCAD) deficiency (hexanoylglycine and suberylglycine), but also severe lactic acidemia (10–25 mM) and, in urine, excess of lactic acid, intermediates of the citric cycle, and marked ketonuria, suggesting mitochondrial dysfunction. She progressed rapidly to develop temporary cortical blindness. Brain imaging indicated generalized atrophy, more marked on the left side, in addition to white matter alterations consistent with a mitochondrial disorder. Magnetic resonance angiography indicated occlusion of the left cerebral artery with development of collateral circulation (Moyamoya syndrome). This process worsened over time to involve the other side of the brain. A muscle biopsy indicated the presence of numerous ragged red fibers. Molecular testing confirmed compound heterozygosity for the common mutation in the MCAD gene (985A>G) and a second pathogenic mutation (233T>C). MtDNA testing indicated that the muscle was almost homoplasmic for the 3243A>T mutation in tRNALeu, with a lower mutant load (about 50% heteroplasmy) in blood and skin fibroblasts. These results indicate that mitochondrial disorders may be associated with severe vascular disease resulting in Moyamoya syndrome. The contribution of the concomitant MCAD deficiency to the development of the phenotype in this case is unclear. © 2008 Wiley‐Liss, Inc.
Hematological abnormalities during the first week of life among neonates with trisomy 18 and trisomy 13: Data from a multi‐hospital healthcare system
Authors: Wiedmeier S.E. , Henry E. , Christensen R.D.
Published: January 2008

Limited information is available on the expected hematological values of newborn infants with trisomy 18 or trisomy 13 syndromes. About 50% of patients with these conditions survive beyond the first week of life, and some have complete blood counts (CBCs) obtained to assist in medical management. We tabulated all CBC data that had been obtained on patients with either trisomy, during their first week of life, using data from an 18 hospital healthcare system. We posited that describing the CBC findings would assist clinicians in providing care for these patients who survive beyond the first days. During the period of January 1, 2001 through December 31, 2006, 174,480 live births were recorded at the 18 hospitals. Trisomy 18 was recognized in 28 (prevalence estimate, 1 in 6,231) and trisomy 13 in 22 (prevalence estimate, 1 in 7,931). Twenty‐four of these had one or more CBCs obtained before the seventh day. Thrombocytopenia was the most common hematological abnormality detected, occurring in 83% of those with trisomy 18 and 75% of those with trisomy 13. Three patients with trisomy 18, and 1 with trisomy 13, received platelet transfusions. The second most commonly detected abnormality was neutrophilia. Eighty‐three percent of neonates with trisomy 13, and 42% with trisomy 18, had neutrophil concentrations above the upper limit of normal for age. Abnormal erythrocyte values were the third most common hematological abnormalities detected. These were much more common among neonates with trisomy 18. Only 43% of patients with trisomy 18 had normal erythrocyte values; anemia was detected in 40% and polycythemia in 17%. Only one neonate with trisomy 13 had abnormal erythrocyte findings (polycythemia). These data should assist clinicians caring for neonates with trisomy 18 or 13, demonstrating how common hematological abnormalities exist among these patients. © 2008 Wiley‐Liss, Inc.
Characterization of a cryptic 3.3 Mb deletion in a patient with a “balanced t(15;22) translocation” using high density oligo array CGH and gene expression arrays
Authors: Li Marilyn M. , Nimmakayalu Manjunath A. , Mercer Danielle , Andersson Hans C. , Emanuel Beverly S.
Published: January 2008

Patients with an apparently balanced translocation and an abnormal phenotype may carry a cryptic deletion/duplication at their translocation breakpoints that may explain their abnormalities. Using microarray CGH (aCGH) and gene expression arrays we studied a child with t(15;22)(q26.1;q11.2), developmental delay and mild dysmorphic features. A high density aCGH study with 244,000 oligo probes demonstrated a 3.3 Mb deletion immediately adjacent to the 15q breakpoint. Gene expression studies with 44,000 oligos displayed an approximately 50% reduction of the expression of IGF1R gene that was translocated to the der(22). There are 18 known or hypothetical protein coding genes within the deleted region according to UniProt, RefSeq, and GenBank mRNA (UCSC HG17, May 2004). Although two of these genes, RGMA and ST8SIA2, play an important role in neural development, the mild phenotype of our patient indicates that loss of one copy of these genes may not be critical developmentally. The 50% reduction of IGF1R expression could be responsible for the growth deficiency in the patient. Reviewing the few 15q26 microdeletion cases that have been characterized by aCGH, we discovered that deletion of the segment including distal 15q26.2 to the proximal part of 15q26.3 is associated with severe phenotypes. Our experience demonstrates that high‐density oligonucleotide‐based aCGH is a quick and precise way to identify cryptic copy number changes in “balanced translocations.” Expression studies can also add valuable information regarding gene expression changes due to a chromosomal rearrangement. Both approaches can assist in the elucidation of the etiology of unexplained phenotypic differences in cases such as this one. © 2008 Wiley‐Liss, Inc.
A second case of severe mental retardation and absent nails of hallux and pollex (Temple–Baraitser syndrome)
Authors: Gabbett Michael T. , Clark Ronald C. , McGaughran Julie M.
Published: January 2008

We present a case of a male with severe mental retardation, seizure disorder, and absence/hypoplasia of the thumb and great toe nails. This combination of clinical findings has been reported only once previously. We suggest it represents a distinct syndrome. Our case has the additional finding of broad thumbs. © 2008 Wiley‐Liss, Inc.
The Italian National Survey for Prader–Willi syndrome: An epidemiologic study
Authors: Grugni Graziano , Crinò Antonino , Bosio Laura , Corrias Andrea , Cuttini Marina , De Toni Teresa , Di Battista Eliana , Franzese Adriana , Gargantini Luigi , Greggio Nella , Iughetti Lorenzo , Livieri Chiara , Naselli Arturo , Pagano Claudio , Pozzan Giovanni , Ragusa Letizia , Salvatoni Alessandro , Trifirò Giuliana , Beccaria Luciano , Bellizzi Maria , Bellone Jaele , Brunani Amelia , Cappa Marco , Caselli Gabriella , Cerioni Valeria , Delvecchio Maurizio , Giardino Daniela , Iannì Francesco , Memo Luigi , Pilotta Alba , Pomara Cristoforo , Radetti Giorgio , Sacco Michele , Sanzari Annarosa , Sartorio Alessandro , Tonini Giorgio , Vettor Roberto , Zaglia Federico , Chiumello Giuseppe ,   on behalf of the Genetic Obesity Study Group of the Italian Society of Pediatric Endocrinology and Diabetology (ISPED)
Published: January 2008

Twenty‐five medical centers and the Prader–Willi Syndrome (PWS) Association collaborated on a study which attempted to identify all people with genetically confirmed diagnosis of PWS living in Italy. Investigators of the participating centers contacted PWS subjects and/or their family, filled in a specially developed form with the required data and forwarded this information by email. The study identified 425 subjects (209 males and 216 females, between the ages of 0.4–46.7). Two hundred thirty‐eight patients had del15, 104 had UPD15, 4 demonstrated a translocation affecting chromosome 15 and 79 showed a positive methylation test. There were fewer subjects found over the age of 35, probably due to the low rate of identification of older PWS patients as well as the high mortality rate. There were a greater number of male children and adolescents with PWS whilst, amongst adults, there were more females. As expected, the majority of subjects with PWS were obese, especially in adult life. Nevertheless, it is noteworthy that 26% of patients aged between 6 and 17 were normal weight. A total of 212 subjects had received GH treatment, of which 141 were still receiving therapy, while the remaining 71 had stopped. In children and adolescents (233 cases), 89 subjects had never undergone GH therapy. Eighteen PWS patients had died in the past 20 years. Obesity‐related cardiovascular and respiratory diseases were the cause of death, both during childhood and after 18 years of age. Three children died suddenly whilst undergoing GH therapy. Respiratory infection and cardiac illness were the causes of death in two cases. There was no definitive cause of death found in the third case. Overall, there was no increase in number of deaths during GH treatment, suggesting that GH administration in patients with PWS, as a group, does not increase the risk of death. © 2008 Wiley‐Liss, Inc.
Electrocardiography in Noonan syndrome PTPN11 gene mutation—phenotype characterization
Authors: Croonen Ellen A. , van der Burgt Ineke , Kapusta Livia , Draaisma Jos M. Th.
Published: January 2008

Noonan syndrome is a developmental disorder with distinctive facial features, short stature and cardiac abnormalities. In this cross‐sectional study, we evaluated characteristic electrocardiographic (ECG) findings and cardiac abnormalities in 84 patients with Noonan syndrome, 56 (67%) of who were positive for a PTPN11 mutation. As reported previously, pulmonary stenosis was the most common cardiac abnormality, followed by atrial septal defect and hypertrophic cardiomyopathy. The ECG showed at least one characteristic finding in 50% of cases including left axis deviation in 38 (45%), small R waves in the left precordial leads in 20 (24%) and an abnormal Q wave in 5 (6%) patients with Noonan syndrome. A wide QRS complex was not detected in any of these patients. The characteristic ECG findings of Noonan syndrome patients were not associated with a PTPN11 gene mutation, or with a (specific) cardiac anomaly. We conclude that there are characteristic ECG findings in Noonan syndrome, but the ECG pattern is neither a useful tool for the phenotype characterization of a PTPN11 mutation, nor for the presence or type of cardiac abnormality. © 2008 Wiley‐Liss, Inc.
Empirical data about women's attitudes toward a biobank focused on pregnancy outcomes
Authors: Joseph Josh W. , Neidich Alon B. , Ober Carole , Ross Lainie Friedman
Published: January 2008

The Chicago Lying‐in Pregnancy Program (CLIPP) is a biobank designed to collect biological samples from pregnant women to study issues related to pregnancy. Despite the large number of biobanking initiatives in obstetric populations around the world, there is no published research that examines what pregnant women understand about enrollment into such programs and what their attitudes and beliefs are toward the research and its potential outcomes. Postpartum women 18 years or older who delivered at the University of Chicago Hospitals and had live infants on the General Care Nursery service were approached about participating in a survey about the CLIPP biobank and about a hypothetical pediatric biobank. Ninety‐three women who had been recruited to participate in CLIPP agreed to participate in this research. Sixty‐three women (68%) had previously agreed to participate in CLIPP; and 30 (32%) had refused. Both participants and non‐participants understood that CLIPP had the main goal of advancing science, although almost one‐half of the respondents thought that participation in CLIPP would benefit the individual participants. Eighty‐five (92%) correctly believed that the research team would keep the medical information private. There was widespread optimism that the research would yield significant results. Importantly, there was no difference in these beliefs between those who enrolled and those who did not enroll in CLIPP. While education and socioeconomic status correlated with greater understanding about the methods and goals of the program, greater understanding did not correlate with willingness to participate. Our survey found widespread willingness to enroll in a pregnancy‐focused biobank and optimism that the results will yield significant benefits. © 2008 Wiley‐Liss, Inc.
The use by Alabama pediatricians of genetics consultation in the evaluation of developmental delay
Authors: Chen Min‐Jye , Holt Cheryl L. , Lose Edward J. , Robin Nathaniel H.
Published: January 2008

Developmental delay (DD) is among the most common serious problems encountered by the general pediatrician. Published guidelines exist that recommend a genetics evaluation be a routine part of the evaluation of these children [Curry et al. (1997) Am J Med Genet 72:468–477; American Academy of Pediatrics (2001) Peds 108:192–195]. In an effort to determine if this recommendation is widely followed, we surveyed Alabama general pediatrics to learn how they utilize a genetic assessment in their evaluation of unexplained DD, and to identify any barriers to a genetics evaluation. A questionnaire was developed that asked about various factors that might influence how pediatricians use genetic evaluations. It was mailed to all members of the Alabama chapter of the American Academy of Pediatrics. The data were tabulated and analyzed by standard methods. One hundred thirty‐seven of 653 surveys were returned. The respondents were evenly divided among urban (35%), suburban (33%), and rural (32%) practice settings. Most were in a non‐academic group practice (71%) and not fellowship trained (76%). Most felt that a genetic evaluation will help define recurrence risk (96%), determine prognosis (96%), and guide patient management (95%). There was limited concern that a genetics evaluation would increase the cost of evaluation (24%) and that it would not eliminate unnecessary testing (64%). The most common indications for referral were the presence of birth defects (93%), positive family history of DD (88%), unusual facial appearance (88%), and parent request (71%). Poor growth was not as strong an indicator. Lack of meaningful results (20%) and expense (18%) were common reasons not to refer, and 48% also cited “other” reasons. Likelihood to refer did not differ by practice location (rural vs. suburban), but distance from a genetics center was a factor. Alabama general pediatricians appreciated the benefits of a genetic evaluation for DD, but several barriers were identified. These issues that must be addressed in order to make a genetics evaluation available to all children with DD. © 2008 Wiley‐Liss, Inc.
Expanding the phenotype of SPONASTRIME dysplasia to include short dental roots, hypogammaglobulinemia, and cataracts
Authors: Gripp Karen W. , Johnson Caitlyn , Scott Charles I. , Nicholson Linda , Bober Michael , Butler Merlin G. , Shaw Linda , Gorlin Robert J.
Published: January 2008

SPONASTRIME dysplasia (SD) is an autosomal recessive skeletal dysplasia of the spondyloepimetaphyseal dysplasia (SEMD) type. The name was derived from “spondylar and nasal alterations with striated metaphyses” [Fanconi et al. 1983; Helv Paediat Acta 38: 267–280]. We follow two previously reported patients with SD [Patients 3, 4 in Langer et al. 1996; Am J Med Genet 63: 20–27]. Since the original publication, additional findings were identified in these patients. © 2008 Wiley‐Liss, Inc.
A DRD1 haplotype is associated with risk for autism spectrum disorders in male‐only affected sib‐pair families
Authors: Hettinger Joe A. , Liu Xudong , Schwartz Charles E. , Michaelis Ron C. , Holden Jeanette J.A.
Published: January 2008

Individuals with autism spectrum disorders (ASDs) have impairments in executive function and social cognition, with males generally being more severely affected in these areas than females. Because the dopamine D1 receptor (encoded by DRD1) is integral to the neural circuitry mediating these processes, we examined the DRD1 gene for its role in susceptibility to ASDs by performing single marker and haplotype case–control comparisons, family‐based association tests, and genotype–phenotype assessments (quantitative transmission disequilibrium tests: QTDT) using three DRD1 polymorphisms, rs265981C/T, rs4532A/G, and rs686T/C. Our previous findings suggested that the dopaminergic system may be more integrally involved in families with affected males only than in other families. We therefore restricted our study to families with two or more affected males (N = 112). There was over‐transmission of rs265981‐C and rs4532‐A in these families (P = 0.040, P = 0.038), with haplotype TDT analysis showing over‐transmission of the C‐A‐T haplotype (P = 0.022) from mothers to affected sons (P = 0.013). In addition, haplotype case–control comparisons revealed an increase of this putative risk haplotype in affected individuals relative to a comparison group (P = 0.004). QTDT analyses showed associations of the rs265981‐C, rs4532‐A, rs686‐T alleles, and the C‐A‐T haplotype with more severe problems in social interaction, greater difficulties with nonverbal communication and increased stereotypies compared to individuals with other haplotypes. Preferential haplotype transmission of markers at the DRD1 locus and an increased frequency of a specific haplotype support the DRD1 gene as a risk gene for core symptoms of ASD in families having only affected males. © 2008 Wiley‐Liss, Inc.
In‐situ‐Funktionalisierung von Polyolefinen mit Heteroatomen: Reaktionswege und katalytische Kettenübertragung
Authors: Amin Smruti B. , Marks Tobin J.
Published: January 2008

Kettenübertragungen sind effiziente und selektive chemische Prozesse für die d‐ und f‐Metall‐katalysierte In‐situ‐Funktionalisierung von Polyolefinen. Eine Reihe höchst unterschiedlicher elektronenarmer wie auch elektronenreicher Kettenüberträger eignet sich dafür, bei der Single‐Site‐Polymerisation von Olefinen einen selektiven Kettenabbruch mit gleichzeitiger Kohlenstoff‐Heteroelement‐Verknüpfung herbeizuführen. Als Kettenüberträger finden z. B. Silane, Borane, Alane, Phosphine und Amine Verwendung. Mit ihnen sind hohe Polymerisationsaktivitäten, eine Kontrolle von Molekulargewicht und Mikrostruktur der Polyolefine und eine selektive Kettenfunktionalisierung möglich. Für elektronenarme und elektronenreiche Reagentien findet man deutlich unterschiedliche Mechanismen. Als Katalysatoren für diese selektiven Kettenabbruchs‐/Funktionalisierungsprozesse eignen sich vielfältige Metallzentren (frühe Übergangsmetalle, Lanthanoide, späte Übergangsmetalle) und Single‐Site‐Hilfsliganden (Metallocene, Halbmetallocene, Nichtmetallocene).
Versatile Pathways for In Situ Polyolefin Functionalization with Heteroatoms: Catalytic Chain Transfer
Authors: Amin Smruti B. , Marks Tobin J.
Published: January 2008

Chain‐transfer processes represent highly effective chemical means to achieve selective, in situ d‐ and f‐block‐metal catalyzed functionalization of polyolefins. A diverse variety of electron‐poor and electron‐rich chain‐transfer agents, including silanes, boranes, alanes, phosphines, and amines, effect efficient chain termination with concomitant carbon–heteroelement bond formation during single‐site olefin‐polymerization processes. High polymerization activities, control of polyolefin molecular weight and microstructure, and selective chain functionalization are all possible, with distinctly different mechanisms operative for the electron‐poor and electron‐rich reagents. A variety of metal centers (early transition metals, lanthanides, late transition metals) and single‐site ancillary ligand arrays (metallocene, half‐metallocene, non‐metallocene) are able to mediate these selective chain‐termination/functionalization processes.
Structure dependence of photochromism of azobenzene‐functionalized polythiophene derivatives
Authors: Zhao Xiong‐Yan , Wang Ming‐Zhu , Liu Hong‐Jie
Published: January 2008

Two novel azobenzene‐functionalized polythiophene derivatives, poly[4‐((4‐(phenyl)azo)phenoxy)butyl‐3‐thienylacetate] (PATh‐4) and the copolymer of 3‐hexylthiophene and 4‐((4‐(phenyl)azo)phenoxy)butyl‐3‐thienylacetate (COP‐64) were synthesized. The structure and photoelectronic behavior of both polythiophene derivatives were characterized by NMR, FTIR, UV–vis, XRD, GPC, modulated DSC, and photoluminescence spectroscopy. These new polymers combine photoluminescence property and photochemical behavior of both polythiophene‐conjugated backbones and the photoisomerizable moieties in the side chains. The photoluminescence property of polymers so obtained can be modified reversibly through the photochemical isomerization reaction of the photoactive groups in side chains. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci 2008
Functional copolymer of geraniol and acrylonitrile: Synthesis and characterization
Authors: Sharma Saroj , Srivastava A. K.
Published: January 2008

The radical copolymerization of acyclic terpene namely geraniol [GER] with acrylonitrile [AN] in DMF at (70 ± 0.1)°C for 1 h, using benzoylperoxide (BPO) as an initiator has been carried out under inert atmosphere of nitrogen. The kinetic expression for reaction is Rp ∝ [BPO]0.5 [AN]1.0 [GER]1.0. The IR spectrum of the copolymer shows bands at 3432 and at 2244 cm−1 due to OH group of GER and CN group of AN, respectively. The 13C‐NMR spectrum shows peaks at 73–75 δ ppm and 116–120 δ ppm due to OH group of GER and CN group of AN, respectively. The thermogravimetric analysis and differential scanning calorimetry study shows that copolymer is thermally stable up to 407°C and has glass transition temperatures (Tg) 56°C. The reactivity ratios r1 (AN) and r2 (GER) have been calculated as 0.05 and 0.005, respectively. The Alfrey‐Price Q‐e parameter for GER has been calculated as 0.094 and −2.0, respectively. The molecular weights of the copolymers have been evaluated by gel‐permeation chromatography. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Effect of thermal treatments on the miscibility of poly(vinyl cinnamate) binary blends
Authors: Hsu Wen‐Ping
Published: January 2008

Poly(vinyl cinnamate) (PVCN) could undergo thermal or photo crosslinking. PVCN was previously found to be miscible with poly(vinyl phenol) (PVPh) [also named poly(hydroxystyrene)]. In this article, the miscibility between PVCN with or without thermal crosslinking and poly(styrene‐co‐hydrostyrene) (designated as MPS) was investigated. PVCN was determined to be miscible with MPS with 15% of hydroxystyrene (MPS‐15) at two compositions but partially miscible or immiscible at PVCN/MPS‐15(50/50) composition. For MPS with 5% of hydroxystyrene (MPS‐5), two Tg values were detected indicating mostly immiscibility. However, PVCN after thermal crosslinking was determined to be miscible with both MPS‐5 and MPS‐15. Immiscibility was found between thermally crosslinked PVCN and PVPh different from miscibility in the original PVCN/PVPh blends. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
The skin‐core structure of poly(acrylonitrile‐itaconic acid) precursor fibers in wet‐spinning
Authors: Ge Heyi , Liu Huashi , Chen Juan , Wang Chengguo
Published: January 2008

The skin‐core structure of poly(acrylonitrile‐itaconic acid) [P(AN‐IA)] precursor fibers in wet‐spinning has been analyzed by the means of electron probe microanalyser (EPMA), scanning electron microscope (SEM), and transmission electron microscope. The numerical solution of Fick's second law equations for diffusion in the nascent fiber was obtained by using the Method of Lines. It has been found that [P(AN‐IA)] precursor fiber composed of four parts had remarkable skin‐core structure. The sheet‐like skin, which was compact and homogeneous, had high crystallization and highly oriented structure. However, the core with low crystallization and some voids was loose, somewhat disorderly and unsystematic. Moreover, the precursor fiber had a pillar‐like layered structure along the fiber axis. The average thickness of each layer increased gradually from the skin to the endothecium. Meanwhile, a structural model of PAN precursor fiber has been built. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Synthesis and light‐emitting properties of a novel π‐conjugated poly[di(p‐phenyleneethynylene)‐alt‐ (p‐phenylenecyanovinylene)] containing n‐octyloxy side branches
Authors: Chi Jun Ho , Lee Chang‐Lyoul , Kim Jang‐Joo , Jung Jin Chul
Published: January 2008

A novel π‐conjugated poly[di(p‐phenyleneethynylene)‐alt‐(p‐phenylenecyanovinylene)] having n‐octyloxy side chains (PPE‐C8PPE‐PPV) was prepared by polymerization of the monomer DEDB with BCN. Chemical structure of the polymer obtained was confirmed by 1H NMR, FTIR, and EA. PPE‐C8PPE‐PPV had a molecular weight enough to fabricate the electroluminescent (EL) device, and showed a good organosolubility, excellent thermal stability, and film‐forming property. In UV absorption and PL spectra in film it showed a maximum at 430 and 543 nm, respectively, which appeared 5 and 41 nm longer wavelengths than that of the solution, respectively. HOMO, LUMO energy levels and band gap were determined to be −5.70, −3.29, and 2.41 eV, respectively. Two EL devices with low‐work function cathodes were fabricated with the structures of ITO/PEDOT/PPE‐C8PPE‐PPV/cathodes (LiF/Al and Mg:Ag/Ag). The both devices exhibited a bright green light emission at 545 nm and the maximum luminescence of 197 cd/cm2 (LiF/Al) and 158 cd/cm2 (Mg:Ag/Ag). © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Comparative study of the elasticity and permeability of vulcanized films made with skim and cream natural rubber latex
Authors: Winsunthorn Suwaluk , Bonfils Frédéric , Pochat‐Bohatier Céline , Bouyer Denis , Deratani André , Dupuy Claude
Published: January 2008

The purpose of this study was to gain a clearer picture of the structure and properties of vulcanized films made with skim and cream latex from Hevea brasiliensis. The two properties targeted for this study were the elasticity of the films and their permeability to acetone. Surface characterization by atomic force microscopy revealed that vulcanization substantially modified the structure of the films compared to unvulcanized films. Unlike unvulcanized films, particle identity was retained in the vulcanized films made with cream latex, even after 4 weeks of aging. In addition, skim latex gave vulcanized films with greater elasticity than those obtained with cream latex. On the basis of the structural characterization carried out on the latex and films and information from the literature, the greater elasticity of the skim films arose from more entanglements between polyisoprene chains and associations between proteins. Despite differences in the structure, the acetone permeability was very similar for skim and cream vulcanized films. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Swelling properties of chemically modified oil palm empty fruit bunch based polyurethane composites
Authors: Tay G. S. , Rozman H. D.
Published: January 2008

In this study, the diffusion of various types of solvent in oil palm empty fruit bunch/polyurethane composites, produced from chemically modified empty fruit bunches, was investigated. The solubility parameters and polymer–solvent interaction parameters of the produced composites were determined. The void contents of the composites were also determined before swelling tests to eliminate the free solvent present in the system. From the results obtained, we found that the diffusion of the solvents was dependent on the compatible group available and the voids present in the system. The solubility parameters of the empty fruit bunch/polyurethane composites with different degrees of chemical modification were 11.6 and 11.7 (cal/cm−3)1/2. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Morphology, thermal expansion, and electrical conductivity of multiwalled carbon nanotube/epoxy composites
Authors: dos Santos Alexandre S. , Leite Thiago de O. N. , Furtado Clascídia A. , Welter Cezar , Pardini Luiz C. , Silva Glaura G.
Published: January 2008

Multiwalled carbon nanotube/epoxy composites loaded with up to 0.5 wt % multiwalled carbon nanotubes were prepared and characterized. Infrared microscopy, scanning electron microscopy, thermogravimetry, differential scanning calorimetry, thermomechanical analysis, and electrical conductivity measurements of the composites were performed. Infrared microscopy and scanning electron microscopy images showed that the debundled nanotubes were well dispersed. The thermal expansion coefficients, before and after the glass transition, remained approximately constant with the addition of nanotubes, whereas the electrical conductivity at room temperature increased approximately 5 orders of magnitude. This result was attributed to the thermal expansion coefficients of the intertube gap on the carbon nanotube bundles, which were in the same range as that of the epoxy resin. Therefore, nanocomposites capable of electrostatic dissipation can be processed as neat epoxy materials with respect to the volume changes with temperature. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
On the electrospinning of poly(vinyl alcohol) nanofiber mats: A revisit
Authors: Supaphol Pitt , Chuangchote Surawut
Published: January 2008

Electrospinning was used to fabricate mats of poly(vinyl alcohol) (PVA; Mw = 72,000 Da, degree of hydrolysis ≈ 97.5–99.5) nanofibers from PVA solutions in reverse osmotic water. The effects of solution concentration, applied electrical potential, sonication, and collection distance on morphological appearance and diameters of the as‐spun fiber mats as well as those of the individual fibers were carefully investigated mainly by scanning electron microscopy. The effect of the distance from the center of the as‐spun fiber mat on morphological appearance and diameters of the as‐spun fibers was also investigated. The mechanical integrity of some as‐spun PVA fiber mats was also investigated. At all concentrations and applied electrical potentials investigated, the average diameters of the as‐spun PVA fibers ranged between 85 and 647 nm. The use of sonication to prepare a PVA solution caused the viscosity of the solution to decrease; hence, the observed decrease in the average diameters of the as‐spun fibers and the average diameters of the as‐spun fibers were practically the same throughout the as‐spun fiber mat. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
The modified‐single fiber test: A methodology for monitoring ballistic performance
Authors: Kim J. , McDonough W. G. , Blair W. , Holmes G. A.
Published: January 2008

A minimally invasive testing methodology was developed to monitor the in‐service performance of soft body armor. In the spirit of the single fiber test standard, ASTM C 1557‐03, the fiber diameter was measured at five equally spaced locations along a 6‐cm gauge length specimen. In addition, the single fiber test specimen was modified by placing reflecting tape just outside the specimen gauge length to allow the use of a laser extensometer for directly measuring fiber displacement and hence, strain. This modified testing methodology was found to be reproducible and provide data that was normally distributed based on descriptive statistics when variations in the fiber diameters along the length of the specimen were considered. The abnormality in the data, identified using Pierce's outlier criterion, may be associated with processing variations during the fiber manufacture and/or the woven fabrics and not associated with the testing methodology. Furthermore, the failure strain was found to be drastically reduced when the minimum fiber diameter along the length of the test specimen was less than 11 μm. This suggests that a methodology that accurately profiles fiber diameter changes along the gauge length of the fiber may be useful in analyzing single fiber test results. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Crystallization and melting of a polyethylene copolymer: In situ observation by atomic force microscopy
Authors: Mirabella Francis M.
Published: January 2008

The isothermal crystallization and subsequent melting of a narrow composition distribution polyethylene (PE) copolymer (containing a few mole percent of an α‐olefin) was observed by hot‐stage atomic force microscopy (AFM). The observations revealed that a thicker lamellae population formed first, followed by a thinner population. This indicated that the crystallization process occurred in two sequential steps. Initially, a single population of uniform lamellar thickness appeared rapidly and progressively occupied the surface. These skeletal lamellae typically ranged in thickness from about 10–15 nm. Progressively, upon isothermal storage, a second, bridging population of lamellae filled in between this initial skeletal population. This second population was thinner with thicknesses of about 4–6 nm. Upon heating, the second, thinner, bridging population of lamellae melted first, leaving the initial, skeletal population, which melted at higher temperatures. These results indicate that PE copolymers crystallize in a stepwise fashion; this was envisioned to begin with a first step in which the thickest lamellae crystallize from the folding of the longest ethylene sequences, followed by a second step in which shorter sequences, constrained between thicker lamellae, crystallize into a population of thinner crystals. The melting of this presumed bimodal population of crystal thicknesses would produce a broad and bimodal endotherm; the bimodal melting endotherm was observed by differential scanning calorimetry. Furthermore, the lamellar thickness dimensions measured by AFM were in approximately the same range as those calculated from the melting endotherm by means of Gibbs–Thompson theory. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Aromaticity and Diatropicity of Polyacenequinododimethides
Authors: Aihara Jun‐ichi , Makino Masakazu
Published: January 2008

Typical polyacenequinododimethides exist only in a single classical structure. These hydrocarbons are moderately aromatic and diatropic, although they have no aromatic conjugated circuits. This apparent dichotomy was resolved with our graph theory of aromaticity and magnetotropicity. Many nonconjugated circuits were found to contribute collectively to aromaticity and diatropicity. For individual molecules, local aromaticity increases with distance from theexo‐methylene groups. This fact indicates that the conjugated‐circuit model is not always applicable to semibenzenoid hydrocarbons such as polyacenequinododimethides.