bluuebunny/crossref_metadata_2025 huggingface dataset:
An N-terminally acetylated Arf-like GTPase is localised to lysosomes and affects their motility
Authors: Hofmann Irmgard , Munro Sean
Published: March 2006

Small GTPases of the Arf and Rab families play key roles in the function of subcellular organelles. Each GTPase is usually found on only one compartment and, hence, they confer organelle specificity to many intracellular processes. However, there has so far been little evidence for specific GTPases present on lysosomes. Here, we report that two closely related human Arf-like GTPases, Arl8a and Arl8b (also known as Arl10b/c and Gie1/2), localise to lysosomes in mammalian cells, with the single homologue in Drosophila cells having a similar location. Conventionally, membrane binding of Arf and Arl proteins is mediated by both an N-terminal myristoyl group and an N-terminal amphipathic helix that is inserted into the lipid bilayer upon activation of the GTPase. Arl8a and Arl8b do not have N-terminal myristoylation sites, and we find that Arl8b is instead N-terminally acetylated, and an acetylated methionine is necessary for its lysosomal localization. Overexpression of Arl8a or Arl8b results in a microtubule-dependent redistribution of lysosomes towards the cell periphery. Live cell imaging shows that lysosomes move more frequently both toward and away from the cell periphery, suggesting a role for Arl8a and Arl8b as positive regulators of lysosomal transport.
Surface Plasmon Resonance Imaging Studies for Proteolytic Hydrolysis of Proteins
Authors: Huang Haowen , Chen Yi
Published: March 2006

Hydrolysis of various proteins was simultaneously studied using a surface plasmon resonance imaging technique. Poly-l-lysine has been found to be completely resistant to hydrolysis, while bovine serum albumin, casein, and lactate dehydrogenase are hydrolyzed at different rates under the attack of pepsin.
End-capping of Pseudo[2]rotaxane Composed of Alkyl(ferrocenylmethyl)ammonium and Dibenzo[24]crown-8 via Cross Metathesis Reactions
Authors: Suzaki Yuji , Osakada Kohtaro
Published: March 2006

Pseudo[2]rotaxane, having dialkylammonium with a ferrocenyl stopper and a vinyl group as the axis component, underwent cross-metathesis reaction with acrylate esters to form ferrocene-containing [2]rotaxanes.
Synthesis and Characterization of Hollow Porous MgO Microspheres
Authors: Qin Li-rong , Zhao Jian-wei , Zhang Li-de , Zou Xian-wu
Published: March 2006

The hollow porous MgO microspheres have been synthesized through a simple in situ chemical vapor deposition method, and the investigations reveal that Zn in raw source is key and possibly acts as an interim template in the formation of MgO hollow-sphere morphology.
A Convenient Method to Prepare Alkali- and Chloride-free Ammonium Metavanadate (NH4VO3)
Authors: Kótai László , Sajó István E , May Zoltán , Gács István , Fodor Judit
Published: March 2006

A convenient method for the preparation of alkali- and chloride-free ammonium metavanadate has been developed. This new process is utilizing a hydrothermal reaction of vanadium pentoxide with ammonium hydroxide or ammonium carbonate for 2 h at 120 °C in a teflon-lined stainless steel autoclave. The yields are 78 and 82%, respectively.
Synthesis and Application of Rigid Calix[4]arenes Partially Modified by Ester Functionality
Authors: Okada Yukihiro , Miao Zhihui , Mizutani Manabu , Nishimura Jun
Published: March 2006

Ionophores 2 having ethyl acetate unit were found to extract efficiently alkali metal ions. Their ion selectivity was apparently changed by the number of ethyl acetate moieties introduced. Dendritic calixarenes were also obtained in excellent yields.
Life goals, approaches to study and performance in an undergraduate cohort
Authors: Wilding John. , Andrews Bernice.
Published: March 2006

Background. Two main approaches to studying have been distinguished by several researchers, the deep approach and the surface approach. In addition, an achieving or strategic approach employs either deep or surface strategies, depending on the demands of the task.

Aims. The present study investigated factors contributing to the choice of preferred study approach at university and relations between these factors and academic performance.

Method. A questionnaire was mailed to a complete cohort of entrants in a college of London University in the UK. A further questionnaire was sent part way through the second year of the course.

Results. Consistent relations were found between general life goals and approaches to study, with the deep approach being associated with altruistic life goals and the surface approach being associated with wealth and status life goals. The achieving approach was related to both types of life goal, but more strongly to wealth and status life goals. Older students, those with superior results in Advanced Level examinations, those reporting more use of the achieving approach, and those with less interest in wealth and status life goals, produced better academic results. Study approaches became more surface‐oriented and less deep and achieving‐oriented over the first year of study, but these changes were unrelated to academic performance.

Conclusions. Approaches to study form part of a wider approach to life in general. Students adopting the achieving approach to study performed better. Though the achieving approach tended to weaken as the course proceeded, this change was unrelated to performance.
Parental interest in children's education, children's self‐esteem and locus of control, and later educational attainment: Twenty‐six year follow‐up of the 1970 British Birth Cohort
Authors: Flouri Eirini.
Published: March 2006

Background.Few studies have investigated if mother's interest and father's interest in child's education are linked to educational attainment via their impact on child's self‐esteem and locus of control.

Aims.(1) To investigate (after controlling for known confounding factors) the long‐term effect of mother's and father's interest in child's education at age 10 and child's locus of control and self‐esteem at age 10 in educational attainment at age 26; and (2) to explore if mother's interest and father's interest in child's education are linked to child's educational attainment via their effect in increasing child's self‐esteem and internal locus of control.

Sample.The study used longitudinal data from sweeps of the 1970 British Cohort Study (BCS70). The initial sample was those 1,737 men and 2,033 women with valid data on age 10 self‐esteem, locus of control, father's interest, mother's interest, and age 26 educational attainment. Of these, 1,326 men and 1,578 women were included in the final analysis.

Method.The birth to age 10 factors that were controlled for were birth weight, parental social class, socio‐economic disadvantage, emotional/behavioural problems, cognitive ability, and mother's educational attainment.

Results.At the multivariate level, internal locus of control and mother's interest (but not self‐esteem) were significantly related to educational attainment in both men and women. Father's interest was a significant predictor of educational attainment only in women. Parent's interest was not linked to educational attainment via its impact on child's self‐esteem or locus of control. Self‐esteem predicted educational attainment in both genders by increasing internal locus of control, and fathers' interest predicted educational attainment in men by increasing mother's involvement.

Conclusion.Although mothers' and fathers' interest in their children's education were not linked to educational attainment via their impact on children's self‐esteem or locus of control, they were significant predictors of educational attainment especially in daughters.
The state of educational intervention research as viewed through the lens of literacy intervention
Authors: Pressley Michael. , Graham Steve. , Harris Karen.
Published: March 2006

The characteristics of educational intervention research are reviewed: Educational intervention research is inspired by diverse theories, targeted at a variety of simple to very complex interventions, and includes a variety of methods and measurements. Some interventions have been studied much more than others, with the more studied ones often summarized in meta‐analyses and other integrative reviews. The study of some of the more complex interventions pose new ethical challenges. Although some intervention research impacts educational practice and policy, much more could and probably should.
An intra‐individual test of the demands‐control model: A weekly diary study of psychological strain in portfolio workers
Authors: Totterdell Peter , Wood Stephen , Wall Toby
Published: March 2006

Twenty‐five years of research on Karasek's job strain model has produced evidence that jobs involving high demands, low control and low social support may produce psychological strain. The present study takes this research in a new direction by using a time‐sampling methodology with a group of portfolio workers (self‐employed individuals who work for multiple clients) to examine whether working weeks that involve more of these characteristics are associated with greater psychological strain. The study also examines whether workers' optimism moderates the intra‐individual relationship between job characteristics and strain. Every week for 26 weeks, 65 portfolio workers completed a diary containing measures of work demands, job control, social support and strain. Multi‐level analyses supported the additive but not the interactive form of the job strain model. However, differences in portfolio workers' optimism moderated an interactive effect of weekly demands and control on anxiety and depression, such that the highest levels of strain were experienced by pessimists under conditions of low control and high demands. The results suggest that psychological strain can vary with temporal variations in job characteristics and that a person‐situation approach is appropriate for understanding these dynamics.
Vogelgrippe aktuell: Auslöser einer neuen Pandemie? Avian influenza updated: will it trigger the next pandemic?
Authors: Allwinn Regina , Varwig Domenica , Wilhelm Doerr Hans
Published: March 2006

Bis einschließlich 10. Januar 2006 infizierten sich in Asien rund 150 Menschen mit dem Erreger der Vogelgrippe H5N1. In sechs Ländern (Kambodscha, China, Indonesien, Thailand, Vietnam und Türkei) verstarben an der “Hühnergrippe” rund 80 Patienten. Eine Übertragung von Mensch zu Mensch scheint in Einzelfällen möglich. Eine Pandemie hat der Erreger bisher nicht ausgelöst: Er wurde nicht (effektiv) von Mensch zu Mensch übertragen.

Aktuell erscheint aber eine Ausweitung der Hühnergrippe auch in Europa denkbar. Meldungen aus Rumänien im Oktober 2005 lassen eine Ausbreitung des H5N1-Erregers bei Wasservögeln vermuten. Jetzt (Stand Januar 2006) wurden auch aus der Türkei mehrere Infektionen des Menschen, davon drei Todesfälle, bekannt.

Sorge bereitet Experten die Möglichkeit eines genetischen “Reassortment” durch eine gleichzeitige Doppel-Infektion eines Wirtes (Mensch, Schwein) mit humanen und aviären Influenza-A-Viren-Erregern. Der neue Subtyp könnte bei passender Adaption an die menschlichen Zellen zu einer neuen Pandemie führen.
Analytik modifizierter Steroidhormone mittels Flüssigkeitschromatographie/Tandem-Massenspektrometrie Analysis of modified steroid hormones using liquid chromatography/tandem mass spectrometry
Authors: Thevis Mario , Schänzer Wilhelm
Published: March 2006

Anabole Wirkstoffe wie Steroidhormone gehören zu den am häufigsten detektierten Dopingsubstanzen in Urinproben von Leistungssportlern. Klassische Nachweisverfahren basieren auf der Zielanalytik verbotener Substanzen bzw. deren Metaboliten mittels Gas-Chromatographie/Massenspektrometrie. Diese Nachweisverfahren werden heutzutage durch modernere flüssigkeitschromatographisch-massenspektrometrische Verfahren ergänzt, die sich im Besonderen für den Nachweis thermisch instabiler Steroide eignen. Tandem-Massenspektrometrie erlaubt zudem die Bestimmung strukturverwandter modifizierter Steroide, deren genaue Komposition den Dopingkontrollinstituten möglicherweise unbekannt ist, wie z.B. im Falle der sogenannten Designersteroide. Umfangreiche Studien zum Fragmentierungsverhalten bestimmter Steroidnuklei sowie sensitive und selektive Massenspektrometer haben deutlich zur Verbesserung der Nachweise verbotener Wirkstoffe in Urinproben beigetragen, indem sogenannte Precursor-Ion sowie Product-Ion Scans zur Detektion und Charakterisierung eingesetzt werden.
Effects of Steel and Tungsten Carbide Ball Indenters on Rockwell Hardness Measurements
Authors: Ma L , Low SR , Fink J
Published: March 2006

The Rockwell hardness (HR) test is a valuable and widely used indentation hardness test for evaluating mechanical properties of metallic materials. For the Rockwell scales that use a ball indenter, either a steel or tungsten carbide (WC) ball indenter is permitted to be used in the current standards of ASTM International and the International Organization for Standardization. However, significant differences occur in Rockwell hardness tests depending on whether the ball indenter that is used is made of steel or WC. In this paper, finite element analysis is used to simulate the HR indentation process using steel and WC ball indenters on the same test materials under the same testing conditions. The effects of four different sizes of steel and WC ball indenters on different Rockwell hardness scales are studied and compared with the experimental tests. This study provides important approximations of differences between the performance of steel and WC Rockwell hardness indenters.
Lateralization of the Human Mirror Neuron System
Authors: Aziz-Zadeh Lisa , Koski Lisa , Zaidel Eran , Mazziotta John , Iacoboni Marco
Published: March 2006

A cortical network consisting of the inferior frontal, rostral inferior parietal, and posterior superior temporal cortices has been implicated in representing actions in the primate brain and is critical to imitation in humans. This neural circuitry may be an evolutionary precursor of neural systems associated with language. However, language is predominantly lateralized to the left hemisphere, whereas the degree of lateralization of the imitation circuitry in humans is unclear. We conducted a functional magnetic resonance imaging study of imitation of finger movements with lateralized stimuli and responses. During imitation, activity in the inferior frontal and rostral inferior parietal cortex, although fairly bilateral, was stronger in the hemisphere ipsilateral to the visual stimulus and response hand. This ipsilateral pattern is at variance with the typical contralateral activity of primary visual and motor areas. Reliably increased signal in the right superior temporal sulcus (STS) was observed for both left-sided and right-sided imitation tasks, although subthreshold activity was also observed in the left STS. Overall, the data indicate that visual and motor components of the human mirror system are not left-lateralized. The left hemisphere superiority for language, then, must be have been favored by other types of language precursors, perhaps auditory or multimodal action representations.
Preoptic Area Neurons and the Homeostatic Regulation of Rapid Eye Movement Sleep
Authors: Gvilia Irma , Turner Amanda , McGinty Dennis , Szymusiak Ronald
Published: March 2006

The median preoptic nucleus (MnPN) and the ventral lateral preoptic area (vlPOA) of the hypothalamus express sleep-related Fos immunoreactivity, and a subset of Fos-immunoreactive neurons (IRNs) in these nuclei contain glutamic acid decarboxylase (GAD), a marker of GABAergic cells. We recently showed that the numbers of Fos-positive (Fos+) and Fos+ GAD-IRNs in both the MnPN and the vlPOA are positively correlated with the total amount of preceding sleep. The present study was designed to clarify whether or not activation of sleep-related neurons in the rat MnPN and vlPOA is associated with rapid eye movement (REM) sleep regulation. Expression of c-fosin MnPN and vlPOA neurons was examined under conditions of spontaneous sleep, REM sleep restriction, and REM sleep recovery after REM sleep restriction. Across all conditions, the number of Fos-IRNs was highest in REM-sleep-restricted rats displaying the highest levels of REM sleep homeostatic pressure/drive, i.e., those rats exhibiting the most frequent attempts to enter REM sleep. This finding provides the first evidence that activation of subsets of MnPN and vlPOA neurons is more strongly related to REM sleep pressure than to REM sleep amount.
A Model of Biological Motion Perception from Configural Form Cues
Authors: Lange Joachim , Lappe Markus
Published: March 2006

Biological motion perception is the compelling ability of the visual system to perceive complex human movements effortlessly and within a fraction of a second. Recent neuroimaging and neurophysiological studies have revealed that the visual perception of biological motion activates a widespread network of brain areas. The superior temporal sulcus has a crucial role within this network. The roles of other areas are less clear. We present a computational model based on neurally plausible assumptions to elucidate the contributions of motion and form signals to biological motion perception and the computations in the underlying brain network. The model simulates receptive fields for images of the static human body, as found by neuroimaging studies, and temporally integrates their responses by leaky integrator neurons. The model reveals a high correlation to data obtained by neurophysiological, neuroimaging, and psychophysical studies.
Impaired Feedforward Inhibition of the Thalamocortical Projection in Epileptic Ca2+Channel Mutant Mice,tottering
Authors: Sasaki Sachie , Huda Kadrul , Inoue Tsuyoshi , Miyata Mariko , Imoto Keiji
Published: March 2006

Thetottering(tg) mice have a mutation in the CaV2.1 (P/Q-type) voltage-dependent Ca2+channel α12.1 subunit gene.tgmice show not only cerebellar ataxia but also absence epilepsy, which begins at ∼3 weeks of age and persists throughout life. Similarities in EEG and sensitivity to antiepileptic drugs suggest thattgmice are a good model for human absence epilepsy. Although imbalance between excitatory and inhibitory activity in the thalamocortical network is thought to contribute to the pathogenesis of absence epilepsy, the effect of the mutation on thalamocortical synaptic responses remains unknown. Here we showed imbalanced impairment of inhibitory synaptic responses intgmice using brain slice preparations. Somatosensory thalamocortical projection makes not only monosynaptic glutamatergic connections but also disynaptic GABAergic connections, which mediate feedforward inhibition, onto layer IV neurons. Intgmice, IPSC amplitudes recorded from layer IV pyramidal cells of the somatosensory cortex in response to thalamic stimulation became disproportionately reduced compared with EPSC amplitudes at later developmental stages (postnatal days 21–30). Similar results were obtained by local stimulation of layer IV pyramidal neurons. However, IPSC reduction was not seen in layer V pyramidal neurons of epileptictgmice or in layer IV pyramidal neurons of youngertgmice before the onset of epilepsy (postnatal days 14–16). These results showed that the feedforward inhibition from the thalamus to layer IV neurons of the somatosensory cortex was severely impaired intgmice and that the impairment of the inhibitory synaptic transmission was correlated to the onset of absence epilepsy.
Regulation of Dendritic Branching and Spine Maturation by Semaphorin3A-Fyn Signaling
Authors: Morita Asa , Yamashita Naoya , Sasaki Yukio , Uchida Yutaka , Nakajima Oumi , Nakamura Fumio , Yagi Takeshi , Taniguchi Masahiko , Usui Hiroshi , Katoh-Semba Ritsuko , Takei Kohtaro , Goshima Yoshio
Published: March 2006

A member of semaphorin family, semaphorin3A (Sema3A), acts as a chemorepellent or chemoattractant on a wide variety of axons and dendrites in the development of the nervous systems. We here show that Sema3A induces clustering of both postsynaptic density-95 (PSD-95) and presynaptic synapsin I in cultured cortical neurons without changing the density of spines or filopodia. Neuropilin-1 (NRP-1), a receptor for Sema3A, is present on both axons and dendrites. When the cultured neurons are exposed to Sema3A, the cluster size of PSD-95 is markedly enhanced, and an extensive colocalization of PSD-95 and NRP-1 or actin-rich protrusion is seen. The effects of Sema3A on spine morphology are blocked by PP2, an Src type tyrosine kinase inhibitor, but not by the PP3, the inactive-related compound. In the cultured cortical neurons fromfyn−/−mice, dendrites bear few spines, and Sema3A does not induce PSD-95 cluster formation on the dendrites. Sema3A and its receptor genes are highly expressed during the synaptogenic period of postnatal days 10 and 15. The cortical neurons in layer V, but not layer III, show a lowered density of synaptic bouton-like structure on dendrites insema3A- andfyn-deficient mice. The neurons of the double-heterozygous mice show the lowered spine density, whereas those of single heterozygous mice show similar levels of the spine density as the wild type. These findings suggest that the Sema3A signaling pathway plays an important role in the regulation of dendritic spine maturation in the cerebral cortex neurons.
Among-Subject Concordance in Keyword Generation and its Effect on Recall: A Preliminary Study
Authors: Campos Alfredo , Amor Angeles
Published: March 2006

A major unresolved question in keyword mnemonics is whether the technique is more effective when the keyword is supplied by the researcher, or when it is generated by the participants. We have recently described a hybrid approach: keywords are selected by the researcher from among those generated by persons of similar sociodemographic characteristics to those of the persons with which the technique is to be used. In the present study we investigated whether recall is affected by the degree of among-persons concordance at the keyword generation stage. The 109 participants (12- to 15-year-olds) received a list of 10 Latin words, each with keyword (previously generated by persons of similar sociodemographic characteristics), translation to Spanish. For five of the 10 Latin words, there had been high among-subject concordance at the keyword generation stage, whereas for the remaining five concordance had been low. Our results indicate that both immediate and one-week recall were significantly better for words for which there had been high concordance in keyword selection. These results indicate ways in which the keyword method can be used more effectively to aid word learning.
Inside Front Cover: Towards See‐Through Displays: Fully Transparent Thin‐Film Transistors Driving Transparent Organic Light‐Emitting Diodes (Adv. Mater. 6/2006)
Authors: Görrn P. , Sander M. , Meyer J. , Kröger M. , Becker E. , Johannes H.‐H. , Kowalsky W. , Riedl T.
Published: March 2006

The first fully transparent organic light‐emitting diode (OLED) pixels, fabricated by integrating transparent OLEDs on top of transparent thin‐film transistors (TTFTs), are demonstrated on p. 738 by Riedl and co‐workers, and shown schematically on the inside cover. With an average transmittance of more than 70 % in the visible part of the spectrum (400–750 nm), the presented active pixels pave the way to the realization of fully transparent active matrix displays.
Social patterns of food sharing in monogamous owl monkeys
Authors: Wolovich C.K. , Feged A. , Evans S. , Green S.M.
Published: March 2006

Captive owl monkeys (Aotus nancymaae, A. azarai) share food frequently within both families and pairs. In this study food sharing was observed in seven mated pairs and four families (i.e., four mated pairs and their offspring). Patterns of food sharing were examined with respect to age class, sex, and the presence or absence of dependent offspring. Within families, most food transfers were from adult males to developing offspring. Adult males and females transferred food to their mates in caged pairs as well as in family units. Food interactions between adults are as likely to result in food transfers as those between adults and offspring. This pattern of food sharing between mates in a monogamous species may serve both nutritional and social functions that differ from those in polygamous species. Am. J. Primatol. 68:1–12, 2006. © 2005 Wiley‐Liss, Inc.
Genetic characterization of rhesus macaques (Macaca mulatta) in Nepal
Authors: Kyes Randall C. , Jones‐Engel Lisa , Chalise Mukesh K. , Engel Gregory , Heidrich John , Grant Richard , Bajimaya Shyam S. , McDonough John , Smith David Glenn , Ferguson Betsy
Published: March 2006

Indian‐origin rhesus macaques (Macaca mulatta) have long served as an animal model for the study of human disease and behavior. Given the current shortage of Indian‐origin rhesus, many researchers have turned to rhesus macaques from China as a substitute. However, a number of studies have identified marked genetic differences between the Chinese and Indian animals. We investigated the genetic characteristics of a third rhesus population, the rhesus macaques of Nepal. Twenty‐one rhesus macaques at the Swoyambhu Temple in Kathmandu, Nepal, were compared with more than 300 Indian‐ and Chinese‐origin rhesus macaques. The sequence analyses of two mitochondrial DNA (mtDNA) loci, from the HVS I and 12 S rRNA regions, showed that the Nepali animals were more similar to Indian‐origin than to Chinese‐origin animals. The distribution of alleles at 24 short tandem repeat (STR) loci distributed across 17 chromosomes also showed greater similarity between the Nepali and Indian‐origin animals. Finally, an analysis of seven major histocompatibility complex (MHC) alleles showed that the Nepali animals expressed Class I alleles that are common to Indian‐origin animals, including Mamu‐A*01. All of these analyses also revealed a low level of genetic diversity within this Nepali rhesus sample. We conclude that the rhesus macaques of Nepal more closely resemble rhesus macaques of Indian origin than those of Chinese origin. As such, the Nepali rhesus may offer an additional resource option for researchers who wish to maintain research protocols with animals that possess key genetic features characteristic of Indian‐origin rhesus macaques. Am. J. Primatol. 68:1–11, 2006. © 2005 Wiley‐Liss, Inc.
Population size and density of Colobus vellerosus at the Boabeng‐Fiema Monkey Sanctuary and surrounding forest fragments in Ghana
Authors: Wong Sarah N.P. , Sicotte Pascale
Published: March 2006

The Boabeng‐Fiema Monkey Sanctuary (BFMS) is inhabited by a growing population of Ursine colobus (Colobus vellerosus), a species that is listed as vulnerable. Smaller, degraded forest fragments that surround the BFMS also contain C. vellerosus and may provide an important habitat for the monkeys. Our objectives were to 1) determine the current population size and density of C. vellerosus at BFMS and in five surrounding fragments, 2) examine the differences in demographics between the fragments and BFMS, and 3) determine whether a relationship exists between population density and fragment size and isolation distance from BFMS. The census was a complete count and was conducted for 1 month (July 2003) by S.W. and trained research assistants. Seven census routes were walked simultaneously on 13 days. The 2003 population estimate of C. vellerosus at BFMS was 217–241 individuals (15 groups), a slight increase from the 2000 census. Numbers in the fragments (58–62, six groups) have remained stable since 1997, when the only other census of these fragments was conducted. Mean group size did not differ between the fragments and BFMS. Larger fragments had larger numbers of colobus, but there was no relationship between fragment size and colobus density. Isolation distance had no effect on population density. Our data suggest that colobus probably travel between fragments. Conservation efforts should focus on treating the small forests and their connecting areas as a single conservation unit. Am. J. Primatol. 68:1–12, 2006. © 2005 Wiley‐Liss, Inc.
Nanoscale investigation on adhesion of E. coli to surface modified silicone using atomic force microscopy
Authors: Cao Ting , Tang Haiying , Liang Xuemei , Wang Anfeng , Auner Gregory W. , Salley Steven O. , Ng K.Y. Simon
Published: March 2006

Bacterial adhesion on biomaterial surfaces is the initial step in establishing infections and leads to the formation of biofilms. In this study, silicone was modified with different biopolymers and silanes, including: heparin, hyaluronan, and self‐assembled octadecyltrichlorosilane (OTS), and fluoroalkylsilane (FAS). The aim was to provide a stable and bacteria‐resistant surface by varying the degree of hydrophobicity and the surface structure. The adhesion of Escherichia coli (JM 109) on different modified silicone surfaces was investigated by atomic force microscopy (AFM) and scanning electron microscopy (SEM). Mica, an ideal hydrophilic and smooth surface, was employed as a control specimen to study the effect of hydrophobicity and surfaces roughness on bacterial adhesion. AFM probes were coated with E. coli and the force measurements between the bacteria‐immobilized tip and various materials surfaces were obtained while approaching to and retracting from the surfaces. A short‐range repulsive force was observed between the FAS coated silicone and bacteria. The pull‐off force of bacteria to FAS was the smallest among coated surfaces. On the other hand, heparin exhibited a long‐range attractive force during approach and required a higher pull‐off force in retraction. Both AFM and SEM results indicated that FAS reduced bacterial adhesion whereas heparin enhanced the adhesion compared to pure silicone. The work demonstrates that hydrophobicity cannot be used as a criterion to predict bacterial adhesion. Rather, both the native properties of the individual strain of bacteria and the specific functional structure of the surfaces determine the strength of force interaction, and thus the extent of adhesion. © 2006 Wiley Periodicals, Inc.
Nonenzymatic Ligation of Short‐Chained 2′–5′‐ or 3′–5′‐Linked Oligoribonucleotides on 2′–5′‐ or 3′–5′‐Linked Complementary Templates
Authors: Sawai Hiroaki , Wada Makoto , Kouda Tsukasa , Nakamura Ozaki Akiko
Published: March 2006

5′‐pACUG tetraribonucleotides containing 2′–5′ or 3′–5′ linkages self‐condensed on 2′–5′‐ or 3′–5′‐linked complementary decaribonucleotide (5′‐CAGUCAGUCA) templates. CD and UV melting studies showed that helix formation took place in all four possible combinations of linkage isomers of the substrate tetramer and the template decamer under the ligation conditions. The hybridization ability followed the order: [3′–5′ tetramer with 3′–5′ decamer]>[2′–5′ tetramer with 3′–5′ decamer]>[2′–5′ tetramer with 2′–5′ decamer]≥[3′–5′ tetramer with 2′–5′ decamer]. Each tetramer condensed on the complementary decaribonucletide template to form the corresponding octamer, but the ligation efficiency varied considerably, depending on the types of linkage in the tetramer substrate and the template decamer. The yields of the octamers obtained by the template‐directed ligation followed the order: [2′–5′ substrate: 2′–5′ template]>[3′–5′:3′–5′]>[2′–5′:3′–5′]>[3′–5′:2′–5′]. The results demonstrate that a homo‐linkage system is preferable for the template‐directed synthesis of RNA. The resulting linkage of the octamer formed from the 2′–5′‐linked substrate and the 2′–5′‐linked template is mainly 2′–5′.
Down‐regulation of locus‐specific human lymphocyte antigen class I expression in Epstein–Barr virus‐associated gastric cancer
Authors: Dutta Nirmal , Gupta Arnab , Mazumder Debendra Nath Guha , Banerjee Subrata
Published: March 2006

BACKGROUND

To understand whether the association between Epstein–Barr Virus (EBV) and gastric cancer (GC) has any role in loss of surface expression of human lymphocyte antigen (HLA) class I, the authors analyzed locus‐specific transcriptional expression of HLA‐A, HLA‐B, HLA‐C, and HLA‐E along with other HLA‐associated molecules (β2‐microglobulin [β2M], cellular latent membrane protein [LMP], and transporter associated with antigen presentation [TAP]) in EBV‐associated, primary GC (EBVaGC) and EBV‐negative GC (EBVnGC) tissues.

METHODS

Approximately 20 EBVaGC tissues and 40 EBVnGC tissues and their corresponding normal tissues were used in the study. The presence of EBV in GC was established by EBV‐encoded small RNA in situ hybridization analysis and BamHI W polymerase chain reaction (PCR) analysis. Transcriptional expression of viral LMP2A and several HLA class I genes were analyzed by reverse transcriptase (RT)‐PCR. Surface expression levels of HLA class I proteins in cancer samples along with their normal counterparts also were quantified by flow cytometry.

RESULTS

The RT‐PCR data suggested selective down‐regulation of the HLA‐A/HLA‐B locus along with over‐expression of HLA‐E transcripts in EBVaGC (P < .05). This was confirmed further by the flow‐cytometric studies using antibodies to HLA‐ABC and HLA‐E. Among the accessory molecules, LMP7 transcript was down‐regulated in a number of EBVaGC tissues compared with EBVnGC.

CONCLUSIONS

The current results suggested that the establishment of EBV latent infection in gastric tissues allows malignant cells to avoid the immune surveillance of both cytotoxic T‐lymphocytes and natural killer cells by regulating the differential expression of HLA class I molecules. Cancer 2006. © 2006 American Cancer Society.
Branching of calyceal afferents during postnatal development in the rat auditory brainstem
Authors: Rodríguez‐Contreras Adrián , de Lange Robert P.J. , Lucassen Paul J. , Borst J. Gerard G.
Published: March 2006

Cells in the anteroventral cochlear nucleus (aVCN) send out calyceal axons that form large excitatory somatic terminals, the calyces of Held, onto principal cells of the contralateral medial nucleus of the trapezoid body (MNTB). It is unclear which fraction of these axons might form more than one calyx and whether this fraction changes during development. We combined in vitro anterograde tracing, stereological cell counts, analysis of apoptosis, and immunohistochemistry to study the development of calyceal afferents in rats of different postnatal ages. We found that some principal cells were contacted by multiple large axosomatic inputs, but these invariably originated from the same axon. Conversely, at least 18% of traced afferents branched to form multiple calyces, independently of age. Calyces from the same axon generally innervated nearby principal cells, and most of these branch points were <50 μm away from the synaptic terminals. Our results show that the projection from the aVCN to the MNTB is divergent, both when calyces have just been formed and in the adult. Cell counts did not provide evidence for principal cell loss during development, although analysis of apoptosis showed a large increase in nonneuronal cell death around the onset of hearing. Our data suggest that, once a calyceal synapse forms in the MNTB, it stays. J. Comp. Neurol. 496:214–228, 2006. © 2006 Wiley‐Liss, Inc.
Contribution of bone marrow hematopoietic stem cells to adult mouse inner ear: Mesenchymal cells and fibrocytes
Authors: Lang Hainan , Ebihara Yasuhiro , Schmiedt Richard A. , Minamiguchi Hitoshi , Zhou Daohong , Smythe Nancy , Liu Liya , Ogawa Makio , Schulte Bradley A.
Published: March 2006

Bone marrow (BM)‐derived stem cells have shown plasticity with a capacity to differentiate into a variety of specialized cells. To test the hypothesis that some cells in the inner ear are derived from BM, we transplanted either isolated whole BM cells or clonally expanded hematopoietic stem cells (HSCs) prepared from transgenic mice expressing enhanced green fluorescent protein (EGFP) into irradiated adult mice. Isolated GFP+ BM cells were also transplanted into conditioned newborn mice derived from pregnant mice injected with busulfan (which ablates HSCs in the newborns). Quantification of GFP+ cells was performed 3–20 months after transplant. GFP+ cells were found in the inner ear with all transplant conditions. They were most abundant within the spiral ligament but were also found in other locations normally occupied by fibrocytes and mesenchymal cells. No GFP+ neurons or hair cells were observed in inner ears of transplanted mice. Dual immunofluorescence assays demonstrated that most of the GFP+ cells were negative for CD45, a macrophage and hematopoietic cell marker. A portion of the GFP+ cells in the spiral ligament expressed immunoreactive Na, K‐ATPase, or the Na‐K‐Cl transporter (NKCC), proteins used as markers for specialized ion transport fibrocytes. Phenotypic studies indicated that the GFP+ cells did not arise from fusion of donor cells with endogenous cells. This study provides the first evidence for the origin of inner ear cells from BM and more specifically from HSCs. The results suggest that mesenchymal cells, including fibrocytes in the adult inner ear, may be derived continuously from HSCs. J. Comp. Neurol. 496:187–201, 2006. © 2006 Wiley‐Liss, Inc.
Expression of Prox1 during mouse cochlear development
Authors: Bermingham‐McDonogh Olivia , Oesterle Elizabeth C. , Stone Jennifer S. , Hume Clifford R. , Huynh Huy M. , Hayashi Toshinori
Published: March 2006

We carried out an analysis of the expression of Prox1, a homeodomain transcription factor, during mouse inner ear development with particular emphasis on the auditory system. Prox1 is expressed in the otocyst beginning at embryonic day (E)11, in the developing vestibular sensory patches. Expression is downregulated in maturing (myosin VIIA immunoreactive) vestibular hair cells and subsequently in the underlying support cell layer by E16.5. In the auditory sensory epithelium, Prox1 is initially expressed at embryonic day 14.5 in a narrow stripe of cells at the base of the cochlea. This stripe encompasses the full thickness of the sensory epithelium, including developing hair cells and support cells. Over the next several days the stripe of expression extends to the apex, and as the sensory epithelium differentiates Prox1 becomes restricted to a subset of support cells. Double labeling for Prox1 and cell‐type‐specific markers revealed that the outer hair cells transiently express Prox1. After E18, Prox1 protein is no longer detectable in hair cells, but it continues to be expressed in support cells for the rest of embryogenesis and into the second postnatal week. During this time, Prox1 is not expressed in all support cell types in the organ of Corti, but is restricted to developing Deiters' and pillar cells. The expression is maintained in these cells into the second week of postnatal life, at which time Prox1 is dynamically downregulated. These studies form a baseline from which we can analyze the role of Prox1 in vertebrate sensory development. J. Comp. Neurol. 496:172–186, 2006. © 2006 Wiley‐Liss, Inc.
GABABreceptors in the centromedian/parafascicular thalamic nuclear complex: An ultrastructural analysis of GABABR1 and GABABR2 in the monkey thalamus
Authors: Villalba Rosa M. , Raju Dinesh V. , Hall Randy A. , Smith Yoland
Published: March 2006

Strong γ‐aminobutyric acid type B (GABAB) receptor binding has been shown throughout the thalamus, but the distribution of the two GABABreceptor subunits, GABABreceptor subunit 1 (GABABR1) and GABABreceptor subunit 2 (GABABR2), remains poorly characterized. In primates, the caudal intralaminar nuclei, centromedian and parafascicular (CM/PF), are an integral part of basal ganglia circuits and a main source of inputs to the striatum. In this study, we analyzed the subcellular and subsynaptic distribution of GABABreceptor subunits by using light and electron microscopic immunocytochemical techniques. Quantitative immunoperoxidase and immunogold analysis showed that both subunits display a similar pattern of distribution in CM/PF, being expressed largely at extrasynaptic and perisynaptic sites in neuronal cell bodies, dendrites, and axon‐like processes and less abundantly in axon terminals. Postsynaptic GABABR1 labeling was found mostly on the plasma membrane (70–80%), whereas GABABR2 was more evenly distributed between the plasma membrane and intracellular compartments of CM/PF neurons. A few axon terminals forming symmetric and asymmetric synapses were also labeled for GABABR1 and GABABR2, but the bulk of presynaptic labeling was expressed in small axon‐like processes. About 20% of presynaptic vesicle‐containing dendrites of local circuit neurons displayed GABABR1/R2 immunoreactivity. Vesicular glutamate transporters (vGluT1)‐containing terminals forming asymmetric synapses expressed GABABR1 and/or displayed postsynaptic GABABR1 at the edges of their asymmetric specialization. Overall, these findings provide evidence for multiple sites where GABABreceptors could modulate GABAergic and glutamatergic transmission in the primate CM/PF complex. J. Comp. Neurol. 496:269–287, 2006. © 2006 Wiley‐Liss, Inc.
Two Novel 5f–3d Bimetallic Cyano‐Bridged Complexes
Authors: Zhang Lin‐Ping , Tanner Peter A. , Mak Thomas C. W.
Published: March 2006

Bimetallic cyano‐bridged uranyl Co and uranyl Fe compounds crystallize in the same space group but are not isomorphous and each comprises two different types of uranyl ion. The spectroscopic consequences with regard to band intensities and positions for the transitions at these different uranyl ion sites are novel and are rationalized. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
A comparison of quantum chemical models for calculating NMR shielding parameters in peptides: Mixed basis set and ONIOM methods combined with a complete basis set extrapolation
Authors: Moon Seongho , Case David A.
Published: March 2006

This article compares several quantum mechanical approaches to the computation of chemical shielding tensors in peptide fragments. First, we describe the effects of basis set quality up to the complete basis set (CBS) limit and level of theory (HF, MP2, and DFT) for four different atoms in trans N‐methylacetamide. For both isotropic shielding and shielding anisotropy, the MP2 results in the CBS limit show the best agreement with experiment. The HF values show quite a different tendency to MP2, and even in the CBS limit they are far from experiment for not only the isotropic shielding of carbonyl carbon but also most shielding anisotropies. In most cases, the DFT values differ systematically from MP2, and small basis‐set (double‐ or triple‐zeta) results are often fortuitously in better agreement with the experiment than the CBS ones. Second, we compare the mixed basis set and ONIOM methods, combined with CBS extrapolation, for chemical shielding calculations at a DFT level using various model peptides. From the results, it is shown that the mixed basis set method provides better results than ONIOM, compared to CBS calculations using the nonpartitioned full systems. The information studied here will be useful in guiding the selection of proper quantum chemical models, which are in a tradeoff between accuracy and cost, for shielding studies of peptides and proteins. © 2006 Wiley Periodicals, Inc. J Comput Chem 27: 825–836, 2006
Quantitative determination of melphalan DNA adducts using HPLC—inductively coupled mass spectrometry
Authors: Edler Michael , Jakubowski Norbert , Linscheid Michael
Published: March 2006

For the quantification of Melphalan DNA adducts, an analytical approach based on the detection of phosphorus using liquid chromatography combined with inductively‐coupled‐plasma mass spectrometry (ICP‐MS) was developed. In reaction mixtures of native 2′‐deoxynucleotides‐5′‐monophosphates and Melphalan, which were separated using reversed phase chromatography, phosphate adducts were found as the most abundant modifications. Besides the phosphate adducts, several base alkylated adducts were observed. In calf thymus DNA incubated with Melphalan and enzymatically digested using Nuclease P1, the phosphate adducts as well as monoalkylated dinucleotides were found. The most abundant single Melphalan adduct observed in DNA was a ring‐opened adenosine monophosphate. Some dinucleotide adducts and the adenosine adduct were identified using electrospray ionization mass spectrometry (ESI‐MS). Copyright © 2006 John Wiley & Sons, Ltd.
An automated and fully validated LC‐MS/MS procedure for the simultaneous determination of 11 opioids used in palliative care, with 5 of their metabolites
Authors: Musshoff F. , Trafkowski J. , Kuepper U. , Madea B.
Published: March 2006

A fully validated liquid chromatographic procedure coupled with electrospray ionization–tandem mass spectrometry (LC‐ESI‐MS/MS) is presented for quantitative determination of the opioids buprenorphine, codeine, fentanyl, hydromorphone, methadone, morphine, oxycodone, oxymorphone, piritramide, tilidine, and tramadol together with their metabolites bisnortilidine, morphine‐glucuronides, norfentanyl, and nortilidine in blood plasma after an automatically performed solid‐phase extraction (SPE). Separation was achieved in 35 min on a Phenomenex C12 MAX‐RP column (4 µm, 150 × 2 mm) using a gradient of ammonium formiate buffer (pH 3.5) and acetonitrile. The validation data were within the required limits. The assay was successfully applied to authentic plasma samples, allowing confirmation of the diagnosis of overdose situations as well as monitoring of patients' compliance, especially in patients under palliative care. Copyright © 2006 John Wiley & Sons, Ltd.
Synthesis and properties of poly(carbonate‐co‐ester)s obtained by cationic ring‐opening copolymerization of spiroorthocarbonate and ε‐caprolactone
Authors: Nagai Daisuke , Nishida Masaki , Ochiai Bungo , Endo Takeshi
Published: March 2006

Cationic ring‐opening copolymerization behavior of 1,5,7,11‐tetraoxaspiro[5.5]undecane (SOC1) and ε‐caprolactone (CL), and the thermal behavior of the obtained copolymers are described. When SOC1 and CL were cationically copolymerized under various feed ratios using BF3OEt2 as the initiator in CH2Cl2 at 25 °C, the corresponding copolymers were obtained in 77–99% yields. The 1H NMR spectroscopic analysis of the copolymers revealed that the copolymer compositions were almost identical to the feed ratios, and the diad ratios of SOC1–SOC1/SOC1–CL and CL–SOC1/CL–CL are 48.0/52.0 and 54.3/45.7. These observations proved the random structures of the copolymers without containing the long blocks of the homopolymer sequences. Differential scanning calorimetric (DSC) analysis revealed that the melting points and melting entharpies decreased with the increase of the SOC1 unit compositions, suggesting that the copolymers gain flexibility as the SOC1 unit increases. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2937–2942, 2006
Single electron transfer–degenerative chain transfer living radical polymerization of N‐butyl acrylate catalyzed by Na2S2O4 in water media
Authors: Coelho Jorge F. J. , Silva Ana M. F. P. , Popov Anatoliy V. , Percec Virgil , Abreu Mariana V. , Gonçalves Pedro M. O. F , Gil M. H.
Published: March 2006

Living radical polymerization of n‐butyl acrylate was achieved by single electron transfer/degenerative‐chain transfer mediated living radical polymerization in water catalyzed by sodium dithionate. The plots of number–average molecular weight versus conversion and ln[M]0/[M] versus time are linear, indicating a controlled polymerization. This methodology leads to the preparation of α,ω‐di(iodo) poly (butyl acrylate) (α,ω‐di(iodo)PBA) macroinitiators. The influence of polymerization degree ([monomer]/[initiator]), amount of catalyst, concentration of suspending agents and temperature were studied. The molecular weight distributions were determined using a combination of three detectors (TriSEC): right‐angle light scattering (RALLS), a differential viscometer (DV), and refractive index (RI). The methodology studied in this work represents a possible route to prepare well‐tailored macromolecules made of butyl acrylate in an environmental friendly reaction medium. Moreover, such materials can be subsequently functionalized leading to the formation of different block copolymers of composition ABA. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2809–2825, 2006