bluuebunny/crossref_metadata_2025 huggingface dataset:
‘Hip-Hop’ Stroke
Authors: Williams Olajide , Noble James M.
Published: July 2008

Background and Purpose—

Public stroke recognition is poor and poses a barrier to acute stroke treatment. We describe a stroke literacy program that teaches elementary school children in high-risk communities to recognize stroke and form an urgent action plan; we then present results of an intervention study using the program.

Methods—

“Hip-Hop” Stroke uses culturally and age-appropriate music and dance to enhance an interactive didactic curriculum including the FAST mnemonic (Facial droop, Arm weakness, Speech disturbance, Time to call 911). The program occurred in central Harlem, New York City, a community with high stroke risk. During the 2006 to 2007 school year, 582 fourth, fifth, and sixth graders (9 to 11 years of age) participated in 1-hour sessions over 3 consecutive days. Stroke knowledge was tested before and after the program with a 94% group participant retention.

Results—

Students learned and retained knowledge well for stroke localization (20% correct before intervention, 93% correct immediately afterward, and 86% correct after 3-month delay;
P
<0.001 both posttests versus baseline), the term “brain attack” (16% pretest, 95% immediate, 86% delayed;
P
<0.001), and to call 911 for stroke (78% pretest, 99.8% immediate, 98% delayed;
P
<0.001). FAST stroke symptoms (facial droop and slurred speech) were better retained than non-FAST symptoms (headache and blurred vision) at 3 months (
P
<0.001). For stroke prevention measures, dietary change and exercise were better learned than concepts of diabetes, hypertension, and cholesterol.

Conclusions—

Elementary school children are educable about stroke, retain their knowledge well, and may be able to appropriately activate emergency services for acute stroke. Incorporating cultural elements such as hip-hop music may improve retention of stroke knowledge among the youth.
Effects of Fiber Arrangement on Mechanical Behavior of Unidirectional Composites
Authors: Yuanchen Huang  , Kyo Kook Jin  , Sung Kyu Ha
Published: July 2008

Micromechanical approaches are employed to investigate the influence of different fiber arrangement on the mechanical behavior of unidirectional composites (UD) under various loading conditions. A micromechanical model with a random fiber array is generated and used in a finite element analysis together with two frequently used representative volume elements (RVE), or unit cell models of square and hexagonal arrays. The algorithm for generating the random fiber array is verified by comparing the comprehensive performance of a unit cell based on our random array and that of a unit cell based on a real fiber distribution in the UD cross-section. Performance of the random and regular fiber arrays is also evaluated through frequency distributions of stress invariants in matrix and tractions at the fiber—matrix interface due to various loading types. The effects of different loading angles on the overall response of regular arrays to various loading conditions are investigated thoroughly. Finally, the Weibull distribution of the maximum normal interfacial traction in random array is compared with the cumulative probability distribution of transverse strength data acquired from experiment, and good agreement is achieved.
How Much Does Country Matter?
Authors: Chen Yi-Min
Published: July 2008

Industrial organization economics and resource-based views of the firm have disagreed over what matters most to profitability for more than 60 years. Until recent variance decomposition studies started trying to determine the relative importance of industry, corporate parent, and business segment on profitability, little research had been done to investigate the extent to which difference in countries could explain the variation in industry performance. This study explores variation in high-tech industry performance, with particular interest in the relative effects of country versus industry for four country classes and eight geographic regions. A variance components model revealed that while country dominated high-tech industry performance in the developed countries and geographic regions North America, South America, All America, Western Europe, and All Europe, industry factors played a role in the development of high-tech industries worldwide. We also found that the effects of industry contributed substantially to the performance of high-tech industry when there was sustainable investment and innovation, especially in newly industrializing economies, large less-developed countries, and Southeast Asia.
Participation of K+ Channels in the Endothelium-Dependent and Endothelium-Independent Components of the Relaxant Effect of Rosuvastatin in Rat Aortic Rings
Authors: López Jorge , Mendoza Roberto , Cleva Villanueva Guadalupe , Martínez Gustavo , Castillo Enrique F. , Castillo Carlos
Published: July 2008

Rosuvastatin was tested on rat aortic rings in the presence and absence of K+ channel blockers, mevalonic acid, and inhibitors of nitric oxide, prostaglandins, or endothelial-derived hyperpolarizing factor synthesis. The direct vascular effects of rosuvastatin were then evaluated by obtaining dose—response curves. Rosuvastatin relaxed aortic rings with and, to a lesser degree, without endothelium. Under both these conditions this effect was partially inhibited by L-NAME, tetraethylammonium, apamin + charybdotoxin (only administered together), or mevalonic acid. The combination of L-NAME with any of the other 3 treatments completely inhibited the effect of rosuvastatin, but indomethacin, clotrimazol, glibenclamide, charybdotoxin, or apamin alone had no effect. Therefore, the relaxation induced by rosuvastatin, even in the absence of endothelium, is partially related to 2 different mechanisms, one that is isoprenoid dependent and NO mediated and the other that is tied to the opening of Ca 2+-dependent K+ channels of the slow subfamily.
Transient left ventricular apical ballooning and exercise induced hypertension during treadmill exercise testing: is there a common hypersympathetic mechanism?
Authors: Dhoble Abhijeet , Abdelmoneim Sahar S , Bernier Mathieu , Oh Jae K , Mulvagh Sharon L
Published: July 2008

Objective

To describe two cases of Takotsubo like myocardial contractile pattern during exercise stress test secondary to hypertensive response.

Background

Treadmill exercise testing is known to cause sympathetic stimulation, leading to increased levels of catecholamine, resulting in alteration in vascular tone. Hypertensive response during exercise testing can cause abnormal consequences, resulting in false positive results.

Cases

We present the cases of two patients experiencing apical and basal akinesis during exercise stress echocardiography, in whom normal wall motion response was observed on subsequent pharmacologic stress testing. The first patient developed transient left ventricular (LV) apical akinesis during exercise stress echocardiography. Due to high suspicion that this abnormality might be secondary to hypertensive response, pharmacologic stress testing was performed after three days, which was completely normal and showed no such wall motion abnormality. Qualitative assessment of myocardial perfusion using contrast was also performed, which showed good myocardial blood flow, indicating low probability for significant obstructive coronary artery disease. The second patient developed LV basal akinesis as a result of hypertensive response during exercise testing. Coronary angiogram was not performed in either patient due to low suspicion for coronary artery disease, and subsequently negative stress studies.

Results

Transient stress induced cardiomyopathy can develop secondary to hypertensive response during exercise stress testing.

Conclusion

These cases provide supporting evidence to the hyper-sympathetic theory of left ventricular ballooning syndrome.
Modulation of gene expression in drug resistant Leishmania is associated with gene amplification, gene deletion and chromosome aneuploidy
Authors: Ubeda Jean-Michel , Légaré Danielle , Raymond Frédéric , Ouameur Amin Ahmed , Boisvert Sébastien , Rigault Philippe , Corbeil Jacques , Tremblay Michel J , Olivier Martin , Papadopoulou Barbara , Ouellette Marc
Published: July 2008

Background

Drug resistance can be complex, and several mutations responsible for it can co-exist in a resistant cell. Transcriptional profiling is ideally suited for studying complex resistance genotypes and has the potential to lead to novel discoveries. We generated full genome 70-mer oligonucleotide microarrays for all protein coding genes of the human protozoan parasites Leishmania major and Leishmania infantum. These arrays were used to monitor gene expression in methotrexate resistant parasites.

Results

Leishmania is a eukaryotic organism with minimal control at the level of transcription initiation and few genes were differentially expressed without concomitant changes in DNA copy number. One exception was found in Leishmania major, where the expression of whole chromosomes was down-regulated. The microarrays highlighted several mechanisms by which the copy number of genes involved in resistance was altered; these include gene deletion, formation of extrachromosomal circular or linear amplicons, and the presence of supernumerary chromosomes. In the case of gene deletion or gene amplification, the rearrangements have occurred at the sites of repeated (direct or inverted) sequences. These repeats appear highly conserved in both species to facilitate the amplification of key genes during environmental changes. When direct or inverted repeats are absent in the vicinity of a gene conferring a selective advantage, Leishmania will resort to supernumerary chromosomes to increase the levels of a gene product.

Conclusion

Aneuploidy has been suggested as an important cause of drug resistance in several organisms and additional studies should reveal the potential importance of this phenomenon in drug resistance in Leishmania.
Osteitis Fibrosa Is Mediated by Platelet-Derived Growth Factor-A Via a Phosphoinositide 3-Kinase-Dependent Signaling Pathway in a Rat Model for Chronic Hyperparathyroidism
Authors: Lowry Malcolm B. , Lotinun Sutada , Leontovich Alexey A. , Zhang Minzhi , Maran Avudaiappan , Shogren Kristen L. , Palama Brett K. , Marley Kevin , Iwaniec Urszula T. , Turner Russell T.
Published: July 2008

Abnormal secretion of PTH by the parathyroid glands contributes to a variety of common skeletal disorders. Prior studies implicate platelet-derived growth factor-A (PDGF-A) as an important mediator of selective PTH actions on bone. The present studies used targeted gene profiling and small-molecule antagonists directed against candidate gene products to elucidate the roles of specific PTH-regulated genes and signaling pathways. A group of 29 genes in rats continuously infused with PTH and cotreated with the PDGF receptor antagonist trapidil were differentially expressed compared with PTH treatment alone. Several of the identified genes were functionally clustered as regulators of fibroblast differentiation and extracellular matrix modeling, including the matrix cross-linking enzyme lysyl oxidase (LOX). Treatment with β-aminopropionitrile, an irreversible inhibitor of LOX activity, dramatically reduced diffuse mineralization but had no effect on PTH-induced fibrosis. In contrast, the receptor tyrosine kinase inhibitor Gleevec and the phosphoinositide 3-kinase inhibitor wortmannin each reduced bone marrow fibrosis. In summary, the present studies support the hypotheses that PTH-induced bone marrow fibrosis is mediated by PDGF-A via a phosphoinositide 3-kinase-dependent signaling pathway and that increased LOX gene expression plays a key role in abnormal mineralization, a hallmark of chronic hyperparathyroidism.
Reverse Transcription with Random Pentadecamer Primers Improves the Detection Limit of a Quantitative PCR Assay for BCR-ABL Transcripts in Chronic Myeloid Leukemia: Implications for Defining Sensitivity in Minimal Residual Disease
Authors: Ross David M , Watkins Dale B , Hughes Timothy P , Branford Susan
Published: July 2008

Background: Real-time quantitative reverse transcription PCR (RQ-PCR) assay for BCR-ABL is used to monitor treatment response in chronic myeloid leukemia (CML). BCR-ABL transcript levels decline over several years of imatinib treatment, and increasing numbers of patients have BCR-ABL transcripts at or below the limit of detection. More sensitive PCR methods are required to assess whether these patients have a long-term continuing decline in residual disease.

Methods: We used random pentadecamer (R15) primers for reverse transcription in RQ-PCR and compared the results with our established method that uses random hexamers. An increase in assay sensitivity would be detected as an increase in the number of BCR-ABL transcripts.

Results: BCR-ABL transcripts increased by 86% with R15 primers. We used R15 primers to retest 19 samples from selected CML patients who had no BCR-ABL transcripts recently detectable with hexamer primers and detected BCR-ABL transcripts in 68% of the samples. Use of R15 primers showed variable increases in the transcripts for control genes BCR (breakpoint cluster region), ABL1 (c-abl oncogene 1, receptor tyrosine kinase), and GUSB (glucuronidase, beta), depending on the gene examined. The reported BCR-ABL/control gene ratio was affected, and the estimated detection limit of the assay, which was based on increased control gene copy number, was different for each control gene.

Conclusions: This simple modification to the reverse transcription methodology improved the detection limit of the RQ-PCR assay for BCR-ABL transcripts. In the field of CML, these results have important implications for defining the detection limit of an assay when the BCR-ABL transcript is undetectable. Random pentadecamer primers may also be useful in other reverse transcription PCR assays for which the abundance of the target RNA is low.
Co-Twin Controls: Facioplasty / Twin Research Reviews: Congenital Anomalies; Personality and Coital Orgasmic Infrequency; Physical Activity Participation / Newsworthy: Twins, Triplets and Quads; School Legislation Update; Premature Twins in Court
Authors: Segal Nancy L.
Published: July 2008

The usefulness of monozygotic (MZ) twins for studying the efficacy of different face lift techniques is described. The data suggest that no particular procedure out of four under consideration is superior to any other. Next, reviews of recent twin studies of congenital anomalies, personality traits and coital orgasmic infrequency, and physical activity participation are presented. Finally, timely topics of public interest are also described. They include a rare birth consequence of artificial reproductive technology, an update on state legislation regarding parents' rights to decide the classroom placement of their young twins, and medical malpractice lawsuits involving premature twins.
Identical Strangers: A Memoir of Twins Separated and ReunitedElyse Schein and Paula Bernstein (2007). New York: Random House, 288 pp., $US25.95. ISBN 978 1 4000 6496 0
Authors: Boomsma Dorret I.
Published: July 2008

Paula Bernstein and Elyse Schein are identical twins who were separated at 6 months of age. After spending the first few months of their lives together with a foster mother they were adopted by different families and finally reunited in 2004, when they were 35 years old. The book, Identical Strangers, written by both twins in alternating paragraphs, describes how they found each other after Elyse contacted their adoption agency with a request about information about her biological mother.
Meningiomas of the ventral foramen magnum
Authors: Arnautovic Kenan I. , Al-Mefty Ossama , Husain Muhamed
Published: July 2008

Meningiomas of the ventral foramen magnum are rare lesions that account for less than 3% of all meningiomas. Their treatment remains one of the most challenging among all meningiomas. The authors comprehensively analyzed multiple features in the series of patients who harbored these lesions.

The authors conducted a retrospective study of 18 patients who harbored lesions in the ventral foramen magnum (mean follow up 40 months) in whom surgery was performed via a transcondylar approach. Sixteen patients underwent surgery for the first time: in 12 patients (75%) gross total, in two (12.5%) near total, and in two (12.5%) subtotal tumor removal was achieved. The remaining two patients were treated for a recurrent tumor. Karnofsky Performance Scale (KPS) scores obtained at follow-up review demonstrated statistically significant improvement compared with those obtained preoperatively. The extent of surgical resection and preoperative KPS score were variables that demonstrated statistically significant favorable influence on outcomes. Ninth and 10th cranial nerve palsies were the most common complication that contributed to the prolonged hospital stay; six patients who experienced nerve palsy preoperatively worsened postoperatively, and four other patients developed nerve palsy after surgery. There were no perioperative deaths. Four patients died during the follow-up period. One patient died of multiple myeloma; another, who underwent surgery for a recurrent tumor, died 3 years after this second surgery from new tumor recurrence at 80 years of age; and the remaining two patients died 1.5 and 5 months postsurgery of pulmonary embolus and endocarditis, respectively.

Meningioma of the ventral foramen magnum can be radically removed in a majority of patients in whom complications will be frequent but transient, resulting from lower cranial nerve palsies. The radical removal of a recurrent tumor provides for the patient a relatively long, stable follow-up period. Patients presenting with a low KPS score have a poor prognosis. Early diagnosis and treatment are recommended.
Environmental Echoes
Authors: Stanford John L. , Stanford Cynthia A. , Grange John M.
Published: July 2008

Allergy, auto immunity and cancer are becoming more prevalent in the developed world. One explanation might be that the immune system required to protect us from such problems is being inadequately trained, perhaps due to our increased separation from the environment which has shaped our mutating genes since we emerged from the primaeval ooze. Those infections which were the essential primers of our immunity are being prevented and action is needed to refocus the immune response without exposing us to the diseases of the past. In this paper we assess our place in relation to the environment and consider ways in which the situation can be redressed. There are considerable similarities between the immune system and human consciousness. Both enter the world in considerable ignorance of the events awaiting them, yet with the genetic ability, endowed by millennia of selection and evolution, to experience the world, to interpret and act on the experiences and to retain memory of the experiences. In both systems, maternal influences and early environmental encounters have profound effects on determining the patterns of subsequent responses. Ideally the ‘learned’ responses will benefit or protect the individual but inappropriate responses may lead to self damage. As the environment has altered irrevocably, attention must be paid to regulating the balance of immunological responsiveness to that expected of the normal immunological learning process. This should be possible by novel vaccination strategies.
Photochemistry of Photochromic Benzopyrans Studied by Time-Resolved Absorption Spectroscopy
Authors: Nakabayashi Takakazu , Nishi Nobuyuki , Sakuragi Hirochika
Published: July 2008

Photochromic reactions of 2H-benzopyrans have been extensively studied to design new materials for commercial applications such as optical memories. Photochromism of 2H-benzopyrans proceeds from a C–O bond cleavage of the colorless closed form to give the colored open forms, which can thermally revert back to the original closed form. From time-resolved absorption spectroscopy, the ring opening of 2H-benzopyrans, 2,4-diphenyl-and 2,2,4-triphenyl-2H-benzopyran, is found to occur via the excited singlet state within 2 ps to produce vibrationally excited open forms in the ground electronic state. In the subnanosecond to submillisecond time domain, several decay components are observed. These components are assigned to respective stereoisomers with respect to two double bonds and one single bond of the open enone forms. As revealed from pump-laser power dependencies of the yields of the open forms, the photocleavage of the benzopyran molecules gives at first only the open forms revertible to the closed form by a single-bond rotation, and the photoexcitation of the first generated open forms gives rise to other open forms that need a double-bond rotation for reversion to the original closed form. Such a two-step two-photon photochromism can be expected to have a wide range of application.
The Design and Applications of Multifunctional Ligands
Authors: Burrows Andrew D.
Published: July 2008

The properties of a metal coordination complex are determined as much by the ligand set – the molecules and ions coordinated to the metal centre – as by the nature of the metal itself. The design and use of new ligands is consequently a major part of chemical research. This review considers the role of multifunctional ligands in three separate and distinct areas of chemistry. In homogeneous catalysis, the role of hybrid and hemilabile ligands is considered, and the introduction of functionalities designed to overcome problems of separation, either by tethering or solubilising, is discussed. In supramolecular chemistry, functionalities enabling the recognition and sensing of cations and anions are examined. In addition, ligands containing two or more faces are discussed for their role in metallodendrimer formation and self-assembly reactions, and the use of bifunctional ligands in crystal engineering is addressed. The application of metal complexes in medicine is examined by consideration of cis-platin and its derivatives as antitumour agents. Imaging agents are also discussed with the uses of gadolinium MRI contrast agents and γ-emitting technetium complexes highlighted.
A New Method for Measuring Intramolecular Charge Transfer
Authors: Schmuttenmaer Charles A.
Published: July 2008

The direct measurement of intramolecular electron transfer through detection of the electromagnetic (EM) waveform that is emitted during this process is reviewed. The waveform is detected in the time-domain via free-space electrooptic sampling and then related to the dynamics of the charge transfer event. Electromagnetic generation from two systems, Betaine-30 in chloroform and DMANS in toluene, are studied to illustrate this technique. A finite-difference time-domain calculation with a time-dependent polarization is used to model the EM generation and propagation through the solution. This method is very general since the movement of charge itself generates the EM waveform, and is sensitive to charge transfer occurring on a 0.1–10ps timescale. The potential for studying the primary steps of charge transfer in photosynthetic bacteria is also discussed.
The Birds from Las Hoyas
Authors: Sanz José Luis , Ortega Francisco
Published: July 2008

Information on the first steps of the avian evolutionary history has dramatically increased during the last few years. The fossil record provides a general view of the morphological changes of the avian flight apparatus from non-volant ancestors (non-avian theropod dinosaurs) to the first derived fliers of the Early Cretaceous. The Las Hoyas bird record includes three genera: Iberomesornis, Concornis and Eoalulavis. This fossil material has yielded information about the early avian evolutionary history. These Early Cretaceous birds (some 120 Myr old) had a wingbeat cycle and breathing devices similar to those of extant birds. The function of the rectricial fan was also similar. In the evolutionary transition from cursorial ancestors to derived fliers it is possible to verify a trend to increase lift. Primitive wing aspect ratio morphotypes were elliptical ones, other derived morphotypes appeared, for example, in the Neornithes (extant birds). Some primitive fliers, like the Las Hoyas genus Eoalulavis, had an alula (feathers attached to the first digit of the hand) similar to that of present day birds, indicating braking and manoeuvring skills similar to those of their extant relatives. Primitive avian life habits are poorly understood. Some evidence from the Las Hoyas bird record indicates that Early Cretaceous birds were present in the trophic chains.
Helicobacter: A Paradigm Shift in Peptic Ulcer Disease and More?
Authors: Basset Christelle , Holton John , Vaira Dino
Published: July 2008

There are many diseases where the cause is unknown and this makes a specific treatment difficult. In many cases all that can be achieved is amelioration of the illness. Peptic ulcer disease was one such condition no more that 20 years ago. The management was drastic – either an operation or life-long medication in order to reduce the acid secreted by the stomach. However, the cause of this condition was discovered in 1983. Although initially sceptical, the medical fraternity now almost universally endorse Helicobacter pylori as the cause of the majority of stomach ulcers. Peptic ulcers can now be cured by antibiotics. This is a major shift in medical practice. Continued investigations on Helicobacter pylori are bringing to light other possible associations with disease as well as delineating plausible biological mechanisms for disease pathogenesis.
Arthrodesis of the tarsometatarsal joints in a cat with a two hole advanced locking plate system
Authors: Koch D. , Bass M. , Inauen R.
Published: July 2008

This report describes the successful use of the novel fixed-angle locking plating system ALPS (advanced locking plate system) in the case of dorsal tarsometatarsal instability in a cat. Partial arthrodesis of the tarsometatarsal joint was performed with a two hole ALPS 5 and two 2.4 mm selftapping locking screws through a small dorsal approach. Five days after the surgery the cat was walking without lameness. Radiographs made after six weeks showed uneventful healing. ALPS offers an alternative to existing plating systems when selecting an implant for the stabilisation of dorsal tarsometatarsal instabilities in cats.
Multifunctional Microporous MOFs Exhibiting Gas/Hydrocarbon Adsorption Selectivity, Separation Capability and Three‐Dimensional Magnetic Ordering
Authors: Li Kunhao , Olson David H. , Lee Jeong Yong , Bi Wenhua , Wu Ke , Yuen Tan , Xu Qiang , Li Jing
Published: July 2008

Microporous materials [M3(HCOO)6] · DMF (M = Mn, Co, Ni) were synthesized solvothermally and structurally characterized by single crystal and powder X‐ray diffraction methods. The metal network exhibits diamondoid connectivity and the overall framework gives rise to zigzag channels along the b axis where guest dimethylformamide molecules reside. The effective pore size of these channels is ∼5–6 Å. The materials feature high thermal stability and permanent porosity with relatively small pore diameters which are attributed to the extensive strong dative bonding between the metal centers and formate molecules. The title compounds exhibit interesting multi‐fold gas adsorption and magnetic properties. The adsorption study of a series of alcohols, aromatics, and linear hydrocarbons revealed strong control of the adsorbent channel structures on their adsorption capacity and selectivity. The study also indicated possibility of using these materials for separation of close boiling chemicals (e.g., ethylbenzene and p‐xylene) via pressure swing adsorption (PSA) process and molecules with different diffusion parameters via kinetic‐based process. Three‐dimensional spontaneous magnetic ordering was found in all three network structures investigated and at ground states they behave somewhat like soft magnets.
Synthesis, Structure, Electronic State, and Luminescent Properties of Novel Blue‐Light‐Emitting Aryl‐Substituted 9,9‐Di(4‐(di‐p‐tolyl)aminophenyl)fluorenes
Authors: Jiao Shibo , Liao Yi , Xu Xinjun , Wang Liping , Yu Gui , Wang Limin , Su Zhongmin , Ye Shanghui , Liu Yunqi
Published: July 2008

Novel blue‐light‐emitting fluorene derivatives 5a–c and 7a–c containing bulky and highly emissive groups, namely pyrene, 10‐phenylanthracene‐9‐yl and 10‐(4′‐diphenylaminophenyl)anthracene‐9‐yl groups, as well as hole‐injecting/transporting triarylamines were synthesized. Single crystals of compounds 5a, 5c, 7a, and 7c were grown and their crystal structures were determined by X‐ray diffraction. The four fluorene derivatives have nonplanar molecular structures, which reduce the intermolecular interaction and the likelihood of molecular aggregation or excimer formation. No unwanted long‐wavelength emission was observed in the photoluminescence (PL) spectra of the 5a–c and 7a–c thin films. Their PL spectra reveal excellent thermal stability after annealing treatment under air and ambient light. All of the six compounds show high fluorescence quantum yields and outstanding thermal stabilities. The 2‐aryl and 2,7‐diaryl substituents at the fluorene molecule have a significant effect on the photophysical properties and the thermal characteristics. The six compounds show almost the same energy levels for the highest occupied molecular orbitals (HOMOs) of about −5.20 eV, which allows effective hole injection. The C2‐ and C7‐aryl substituents play a relatively less‐important role in the HOMO energy levels, which depend mainly on the triphenylamino groups at the C9 position. The molecular orbitals, excitation energy, and emission energy were calculated to explain the real origin of their photophysical characteristics. The HOMOs are mainly localized on the triphenylamino groups at the C9 position, while the lowest unoccupied molecular orbitals (LUMOs) have a significant orbital density at the C2‐ and/or C7‐aryl substituents. Pure‐blue‐light‐emitting diodes based on 2,7‐diaryl‐9,9‐di(triarylamino)fluorenes were fabricated.
Molecular Glass Resists as High‐Resolution Patterning Materials
Authors: De Silva Anuja , Felix Nelson M. , Ober Christopher K.
Published: July 2008

The success of the semiconductor industry is based on the ability to fabricate hundreds of millions of devices on a single chip. In order to fulfill the ever‐shrinking feature sizes, the industry requires new patternable materials in order to operate in the sub‐50 nm regime. Molecular glass (MG) resists are a new type of patterning material that has gained considerable attention over the past few years. This Research News article describes the chemical and structural aspects of MGs as well as important concepts of MG resist design. We also highlight some of the recent advances in high‐resolution patterning capabilities with next‐generation imaging tools.
Agenesis of the corpus callosum in California 1983–2003: A population‐based study
Authors: Glass Hannah C. , Shaw Gary M. , Ma Chen , Sherr Elliott H.
Published: July 2008

The objective of this study was to characterize the prevalence, demographic risk factors, and malformations associated with agenesis and hypoplasia of the corpus callosum diagnosed in infancy. Using a large population‐based registry of birth defects, we ascertained 630 cases of agenesis (ACC) and hypoplasia (HCC) of the corpus callosum diagnosed in the first year of life among 3.4 million live births from 1983 to 2003. Infants with destructive lesions or specific complex central nervous system (CNS) malformations (neural tube defects, lissencephaly, and holoprosencephaly) were excluded. Multivariable Poisson regression analysis was used to examine demographic risk factors. The combined prevalence of ACC and HCC was 1.8 per 10,000 live births. Fifty‐two percent of cases were male. Infants with ACC had an almost fourfold higher prevalence among infants born prematurely when compared with children born ≥37 weeks gestation (RR 3.7, 95% CI 2.5–5.3). After adjusting for paternal age, advanced maternal age ≥40 years was associated with ACC in infants with a chromosomal disorder (ACC RR 5.9; 95% CI 1.8–19.3, HCC RR 3.5; 95% CI 0.9–14.1). Paternal age was not significantly associated with ACC after adjusting for maternal age. Callosal anomalies were often seen in the context of a chromosomal abnormality (17.3%) and with accompanying somatic (musculoskeletal 33.5% and cardiac 27.6%) and CNS malformations (49.5%). Callosal anomalies form a clinically significant and relatively frequent group of malformations of the CNS that are associated with increased risk of premature birth, are more common with advanced maternal age and are frequently part of a complex, multisystem disorder. © 2008 Wiley‐Liss, Inc.
An epidermal nevus syndrome with cerebral involvement caused by a mosaic FGFR3 mutation
Authors: García‐Vargas Alejandro , Hafner Christian , Pérez‐Rodríguez Adriana G. , Rodríguez‐Rojas L. Ximena , González‐Esqueda Pedro , Stoehr Robert , Hernández‐Torres Mercedes , Happle Rudolf
Published: July 2008

A 5‐year‐old Mexican girl had a bilateral, systematized epidermal nevus of a non‐epidermolytic, non‐organoid type covering large parts of her body with the exception of the scalp. Clinically, this nevus was of a soft, velvety type showing affinity to the large body folds. Histopathological examination revealed orthohyperkeratosis and papillomatosis without granular degeneration and without any abnormality of adnexal structures. During infancy she developed seizures, and subsequently a delayed mental development was noted. Computer tomography of the brain revealed cortical and subcortical atrophy, a subdural hygroma in the left frontoparietotemporal region, and hypoplasia of corpus callosum. Molecular analysis of a biopsy specimen obtained from the epidermal nevus revealed a heterozygous R248C hotspot mutation in FGFR3, whereas in normal skin the FGFR3 wild‐type allele was exclusively found. The R248C mutation was also present in DNA extracted from blood leukocytes. Because FGFR3 is involved in the development of the central nervous system, the clinical and genetic findings of this case indicate a widespread mosaicism of the FGFR3 mutation. This unusual mosaic phenotype may represent a distinct entity within the group of epidermal nevus syndromes. © 2008 Wiley‐Liss, Inc.
Gas‐ und Dampfsensoren auf der Basis von Kohlenstoff‐Nanoröhren
Authors: Kauffman Douglas R. , Star Alexander
Published: July 2008

Seit ihrer Entdeckung im Jahr 1991 haben Kohlenstoff‐Nanoröhren ein riesiges Interesse erfahren. Grund ist ihr enormes Anwendungspotenzial, und Forscher unterschiedlicher Fachrichtungen arbeiten heute gemeinsam daran, die elektronische Struktur und das Reaktionsverhalten von Kohlenstoff‐Nanoröhren aufzuklären. Da ihre elektronische Struktur leicht von wechselwirkenden Molekülen beeinflusst wird, reagieren Kohlenstoff‐Nanoröhren extrem empfindlich auf Änderungen in der lokalen chemischen Umgebung. Dies macht sie zu idealen Kandidaten für den Einsatz in chemischen Sensoren, und es wurden bemerkenswerte Fortschritte bezüglich der Empfindlichkeit und chemischen Selektivität gegenüber einer Vielzahl chemischer Spezies erzielt. Trotz der zahlreichen Verbesserungen sind aber noch einige wichtige Probleme zu lösen, bevor Kohlenstoff‐Nanoröhren mit den modernsten Feststoff‐Sensormaterialien konkurrieren können. Die Entwicklung von Sensoren auf der Basis von Kohlenstoff‐Nanoröhren befindet sich zwar noch im Anfangsstadium, aber bei weiteren Fortschritten erscheint ihre Integration in kommerziell tragfähige Sensoren, die sich dann durch eine konkurrenzlose Empfindlichkeit und außerordentlich kleine Abmessungen auszeichnen werden, möglich.
Solvent‐Ligated Copper(II) Complexes for the Homopolymerization of 2‐Methylpropene
Authors: Li Yang , Voon Lih Ting , Yeong Hui Yee , Hijazi Ahmed K. , Radhakrishnan Narayanan , Köhler Klaus , Voit Brigitte , Nuyken Oskar , Kühn Fritz E.
Published: July 2008

Copper(II) complexes with weakly coordinating counter anions can be utilized as highly efficient catalysts for the synthesis of poly(2‐methylpropene) (“polyisobutene”) with a high content of terminal double bonds. These copper(II) compounds are significantly more active than the manganese(II) complexes described previously, can be applied in chlorine‐free solvents such as toluene, are easily accessible, and can be handled at room temperature and in laboratory atmospheres for brief periods, but they are sensitive to excess water, thereby losing their catalytic activity. Replacing the acetonitrile ligands by benzonitrile ligands improves the solubility and catalytic activity in nonpolar and nonchlorinated solvents. However, the benzonitrile copper(II) compounds have lower thermal stability than their acetonitrile congeners.
Mono‐ and Diprotonation of the Superbasic Bisguanidine 1,2‐Bis(N,N,N′,N′‐tetramethylguanidino)benzene (btmgb) and PtII and PtIV Complexes of Chelating Bisguanidines and Guanidinates
Authors: Peters Anastasia , Wild Ute , Hübner Olaf , Kaifer Elisabeth , Himmel Hans‐Jörg
Published: July 2008

New Pt complexes of chelating bisguanidines and guanidinate ligands were synthesized and characterized. 1,2‐Bis(N,N,N′,N′‐tetramethylguanidino)benzene (btmgb) was used as a neutral chelating bisguanidine ligand, and 1,3,4,6,7,8‐hexahydro‐2H‐pyrimido[1,2‐a]pyrimidinate (hpp−) as a guanidinate ligand. The salts [btmgbH]+[HOB(C6F5)3]− and [btmgbH2]Cl2 and the complexes [(btmgb)PtCl2], [(btmgb)PtCl(dmso)]+[PtCl3(dmso)]−, and [(btmgb)PtCl(dmso)]+[Cl−] were synthesized and characterized. In the [btmgbH]+ cation the proton is bound to only one N atom. In the other complexes, both imine N atoms are coordinated to the PtII, thus adopting a η2‐coordinational mode. The hpp− anion, which usually prefers a bridging binding mode in dinuclear complexes, is η2‐coordinated in the PtIV complex [(η2‐hpp)(hppH)PtCl2{N(H)C(O)CH3}], which is formed (in low yield) by reaction between cis‐[(hppH)2PtCl2] and H2O2 in CH3CN.
Experimental Measurement of Carbohydrate–Aromatic Stacking in Water by Using a Dangling‐Ended DNA Model System
Authors: Morales Juan C. , Reina José J. , Díaz Irene , Aviñó Anna , Nieto Pedro M. , Eritja Ramón
Published: July 2008

Protein–carbohydrate recognition is of fundamental importance for a large number of biological processes; carbohydrate–aromatic stacking is a widespread, but poorly understood, structural motif in this recognition. We describe, for the first time, the measurement of carbohydrate–aromatic interactions from their contribution to the stability of a dangling‐ended DNA model system. We observe clear differences in the energetics of the interactions of several monosaccharides with a benzene moiety depending on the number of hydroxy groups, the stereochemistry, and the presence of a methyl group in the pyranose ring. A fucose–benzene pair is the most stabilizing of the studied series (−0.4 Kcal mol−1) and this interaction can be placed in the same range as other more studied interactions with aromatic residues of proteins, such as Phe–Phe, Phe–Met, or Phe–His. The noncovalent forces involved seem to be dispersion forces and nonconventional hydrogen bonds, whereas hydrophobic effects do not seem to drive the interaction.
The Basicity of Unsaturated Hydrocarbons as Probed by Hydrogen‐Bond‐Acceptor Ability: Bifurcated NH+⋅⋅⋅π Hydrogen Bonding
Authors: Stoyanov Evgenii S. , Stoyanova Irina V. , Reed Christopher A.
Published: July 2008

The competitive substitution of the anion (A−) in contact ion pairs of the type [Oct3NH+]B(C6F5)4− by unsaturated hydrocarbons (L) in accordance with the equilibrium Oct3NH+⋅⋅⋅A− + nL ⇄ [Oct3NH+⋅⋅⋅Ln]A− has been studied in CCl4. On the basis of equilibrium constants, K, and shifts of νNH to low frequency, it has been established that complexed Oct3NH+⋅⋅⋅Ln cations with n=1 and 2 are formed and have unidentate and bifurcated NH+⋅⋅⋅π hydrogen bonds, respectively. Bifurcated hydrogen bonds to unsaturated hydrocarbons have not been observed previously. The unsaturated hydrocarbons studied include benzene and methylbenzenes, fused‐ring aromatics, alkenes, conjugated dienes, and alkynes. From the magnitude of the redshifts in the NH stretching frequencies, ΔνNH, a new scale for ranking the π basicity of unsaturated hydrocarbons is proposed: fused‐ring aromatics≤benzene<toluene<xylene<mesitylene<durene<conjugated dienes≈1‐alkynes<pentamethylbenzene<hexamethylbenzene<internal alkynes≈cycloalkenes<1‐methylcycloalkenes. This scale is relevant to the discussion of π complexes for incipient protonation reactions and to understanding NH+⋅⋅⋅π hydrogen bonding in proteins and molecular crystals.
Ruthenium‐Based Olefin Metathesis Catalysts Coordinated with Unsymmetrical N‐Heterocyclic Carbene Ligands: Synthesis, Structure, and Catalytic Activity
Authors: Vougioukalakis Georgios C. , Grubbs Robert H.
Published: July 2008

A series of ruthenium‐based olefin metathesis catalysts coordinated with unsymmetrical N‐heterocyclic carbene (NHC) ligands has been prepared and fully characterized. These complexes are readily accessible in one or two steps from commercially available [(PCy3)2Cl2RuCHPh]. All of the complexes reported herein promote the ring‐closing of diethyldiallyl and diethylallylmethallyl malonate, the ring‐opening metathesis polymerization of 1,5‐cyclooctadiene, and the cross metathesis of allyl benzene with cis‐1,4‐diacetoxy‐2‐butene, in some cases surpassing in efficiency the existing second‐generation catalysts. Especially in the cross metathesis of allyl benzene with cis‐1,4‐diacetoxy‐2‐butene, all new catalysts demonstrate similar or higher activity than the second‐generation ruthenium catalysts and, most importantly, afford improved E/Z ratios of the desired cross‐product at conversion above 60 %. The influence of the unsymmetrical NHC ligands on the initiation rate and the activation parameters for the irreversible reaction of these ruthenium complexes with butyl vinyl ether were also studied. Finally, the synthesis of the related chlorodicarbonyl(carbene) rhodium(I) complexes allowed for the study of the electronic properties of the new unsymmetrical NHC ligands that are discussed in detail.
Synthesis of 4,5‐Dihydroisoxazoles by Condensation of Primary Nitro Compounds with Alkenes by Using a Copper/Base Catalytic System
Authors: Cecchi Luca , De Sarlo Francesco , Machetti Fabrizio
Published: July 2008

A new procedure for the synthesis of 4.5‐dihydroisoxazoles by condensation of primary nitro compounds with olefins by using a copper/base catalytic system is described. The catalytic effect of copper(II) salts is evidenced by comparison of the reaction rates. Thus, activated nitro compounds react faster than with organic catalysis by tertiary amines, whereas nitroalkanes, unable to condense with dipolarophiles in the presence of the base alone, undergo the reaction on addition of a copper(II) catalyst. The observed occurrence of induction periods in most reactions is ascribed to an equilibrium preceding the rate‐determining step, and gives a hint as to the proposed reaction mechanism. The results indicate that this method might be of practical and general utility for synthetic practice.
Prognostic factors for functional outcome and survival after reirradiation for in‐field recurrences of metastatic spinal cord compression
Authors: Rades Dirk , Rudat Volker , Veninga Theo , Stalpers Lukas J. A. , Hoskin Peter J. , Schild Steven E.
Published: July 2008

BACKGROUND.

The purpose of the current study was to retrospectively investigate clinical outcome and potential prognostic factors after reirradiation (Re‐RT) for in‐field recurrence of metastatic spinal cord compression (MSCC).

METHODS.

Re‐RT with 1 × 8 Gy (n = 48), 5 × 3 Gy (n = 29), 5 × 4 Gy (n = 30), 7 × 3 Gy (n = 3), 10‐12 × 2 Gy (n = 11), or 17 × 1.8 Gy (n = 3) was administered to 124 patients. Cumulative biologically effective dose (BED) (first course of RT plus re‐RT) ranged from 77.5 Gy2 to 142.6 Gy2, and was ≤120 Gy2 in 114 (92%) patients. Twelve potential prognostic factors were investigated for associations with motor function and survival.

RESULTS.

Motor function improved in 45 (36%) patients, was stable in another 62 (50%) patients, and deteriorated in 17 (14%) patients. Upon multivariate analyses, the effect of Re‐RT on motor function was significantly associated with the effect of the first course of RT (P = .048), Eastern Cooperative Oncology Group (ECOG) performance status (P = .020), time to development of motor deficits before Re‐RT (P = .002), and visceral metastases (P < .001). Survival was associated with ECOG performance status (P < .001), ambulatory status before Re‐RT (P < .001), time to development of motor deficits (P = .018), and visceral metastases (P <.001). Re‐RT dose schedule or cumulative BED had no significant impact on functional outcome or survival. Acute toxicity was mild, and late toxicity, such as radiation myelopathy, was not observed.

CONCLUSIONS.

Given the limitations of a retrospective study and the relatively short follow up after Re‐RT, spinal reirradiation appeared to be effective and safe when the cumulative BED is ≤120 Gy2. Motor function after Re‐RT was associated with the effect of first irradiation, performance status, time to development of motor deficits, and visceral metastases, whereas the Re‐RT schedule had no significant impact. Cancer 2008. © 2008 American Cancer Society.
Segmentation and analysis of the three‐dimensional redistribution of nuclear components in human mesenchymal stem cells
Authors: Vermolen Bart J. , Garini Yuval , Young Ian T. , Dirks Roeland W. , Raz Vered
Published: July 2008

To better understand the impact of changes in nuclear architecture on nuclear functions, it is essential to quantitatively elucidate the three‐dimensional organization of nuclear components using image processing tools. We have developed a novel image segmentation method, which involves a contrast enhancement and a subsequent thresholding step. In addition, we have developed a new segmentation method of the nuclear volume using the fluorescent background signal of a probe. After segmentation of the nucleus, a first‐order normalization is performed on the signal positions of the component of interest to correct for the shape of the nucleus. This method allowed us to compare various signal positions within a single nucleus, and also on pooled data obtained from multiple nuclei, which may vary in size and shape. The algorithms have been tested by analyzing the spatial localization of nuclear bodies in relation to the nuclear center. Next, we used this new tool to study the change in the spatial distribution of nuclear components in cells before and after caspase‐8 activation, which leads to cell death. Compared to the morphological TopHat method, this method gives similar but significantly faster results. A clear shift in the radial distribution of centromeres has been found, while the radial distribution of telomeres was changed much less. In addition, we have used this new tool to follow changes in the spatial distribution of two nuclear components in the same nucleus during activation of apoptosis. We show that after caspase‐8 activation, when centromeres shift to a peripheral localization, the spatial distribution of PML‐NBs does not change while that of centromeres did. We propose that the use of this new image segmentation method will contribute to a better understanding of the 3D spatial organization of the cell nucleus. © 2008 International Society for Advancement of Cytometry