bluuebunny/crossref_metadata_2025 huggingface dataset:
New method for the in situ determination of AlxGa1–xN composition in MOVPE by real‐time optical reflectance
Authors: Hardtdegen H. , Kaluza N. , Sofer Z. , Cho Y. S. , Steins R. , Bay H. L. , Dikme Y. , Kalisch H. , Jansen R. H , Heuken M. , Strittmatter A. , Reißmann L. , Bimberg D. , Zettler J.‐T.
Published: May 2006

This paper reports on the in situ determination of the Al‐content in Alx Ga1–x N layers deposited by MOVPE on sapphire and silicon substrates by means of optical reflectance. The accuracy of the conventional in situ method which utilizes the dependence of the refractive index and the extinction coefficient on Al‐content is compared to that of the new dispersion approach. The limits and possibilities of the new approach will be discussed. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Progress in MOVPE growth of crack‐free AlGaN based Bragg reflectors on Si(111)
Authors: Charles M. B. , Zhang Y. , Kappers M. J. , Humphreys C. J.
Published: May 2006

Having previously reported growth of uncracked AlN/GaN distributed Bragg reflectors (DBRs), this paper reports use of superlattices as a replacement for AlN layers to produce high quality crack free DBRs. In addition an InGaN LED structure grown above the DBR has been studied and showed improved uniformity in comparison with a standard LED structure. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Development of native, single crystal AlN substrates for device applications
Authors: Schowalter L. J. , Schujman S. B. , Liu W. , Goorsky M. , Wood M. C. , Grandusky J. , Shahedipour‐Sandvik F.
Published: May 2006

Ultra‐low dislocation density aluminum nitride is a very promising substrate for many device structures based on the III–V nitride system. A better lattice and thermal expansion match than foreign substrates such as SiC or sapphire make AlN the substrate of choice for heteroepitaxial growth of AlGaN alloys, especially those with high aluminum concentration. In this paper, we show crystalline and chemical characterization of native aluminum nitride substrates, as well as characterization of AlGaN epilayers with 40 and 50% concentration of aluminum. The observation of atomic steps in atomic force microscope scans of the bare substrates and epilayers, as well as the narrow Full Width at Half Maximum (FWHM) measured on X‐ray diffraction, are an indication of both the good surface preparation of the substrates and quality of the epilayers. An estimation of defect density on epilayers grown by Migration Enhanced Metal Organic Chemical Vapour Deposition (MEMOCVD) resulted in mid 106/cm2. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Structural analysis of (Ga,Mn)N epilayers and self‐organized dots using MeV ion channeling
Authors: Kuroda S. , Marcet S. , Bellet‐Amalric E. , Cibert J. , Mariette H. , Yamamoto S. , Sakai T. , Ohshima T. , Itoh H.
Published: May 2006

Rutherford backscattering (RBS) and particle‐induced X‐ray emission (PIXE) experiments were performed on (Ga,Mn)N epilayers and self‐organized dots grown by plasma‐assisted MBE. The combined channeling RBS and Mn PIXE experiments were performed on Ga0.949Mn0.051N epilayer, which was confirmed to be of pure diluted phase by X‐ray diffraction (XRD) in our previous study, in order to check the presence of Mn atoms in the interstitial site in wurtzite crystal. The axis scan around 〈0001〉 and 〈$ 10 \bar 1 2$〉 axes and the plane scan around ($ 10 \bar 1 0$) plane revealed that almost all the Mn atoms were in the substitutional site of wurtzite GaN crystal. For self‐organized dots of (Ga,Mn)N grown on AlN by MBE, the PIXE spectra were measured and the Mn composition in the dot layer was estimated from the ratio of emission intensity of Mn and Ga Kα lines. At a result, it was found that the Mn composition in the dots was higher by two or three times than that in thick epilayers grown with the addition of the same amount of Mn flux. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Microstructure of thick AlN grown on sapphire by high‐temperature MOVPE
Authors: Imura M. , Nakano K. , Kitano T. , Fujimoto N. , Okada N. , Balakrishnan K. , Iwaya M. , Kamiyama S. , Amano H. , Akasaki I. , Shimono K. , Noro T. , Takagi T. , Bandoh A.
Published: May 2006

Thick AlN layers with atomically flat surfaces were successfully grown directly on sapphire substrates by metal‐organic vapor phase epitaxy at high temperatures between 1300 °C and 1600 °C. Dislocations such as those of the edge, screw and mixed types exhibited different behaviors in the AlN epilayers. The dislocation density of AlN was less than 2 × 109 cm–2. Free and bound excitons of AlN were observed with peak energies of 6.084 eV and 6.063 eV, respectively. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
N‐type doping of HVPE‐grown GaN using dichlorosilane
Authors: Richter E. , Hennig Ch. , Zeimer U. , Wang L. , Weyers M. , Tränkle G.
Published: May 2006

N‐type doping of GaN in hydride vapour phase epitaxy (HVPE) has been studied. While silane was found to be not suitable, doping from solid silicon was found to be feasible but difficult to handle. Dichlorosilane was found to be a convenient Si doping source for HVPE growth of GaN. High electron mobilities as well as good optical and structural properties are obtained in the doping range of 6 × 1017 cm–3 to 8 × 1018 cm–3 using dichlorosilane. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Non‐catalyst growth and characterization of a ‐plane AlGaN nanorods
Authors: Gaevski Mikhail E. , Sun Wenhong , Yang Jinwei , Adivarahan Vinod , Sattu Ajay , Mokina Irina , Shatalov Maxim , Simin Grigory , Asif Khan M.
Published: May 2006

We report on growth of Al0.22Ga0.78N/Al0.06Ga0.94N nanorods over a ‐plane GaN template using low pressure metal‐organic chemical vapor deposition. Nanorods with average diameter of 100 nm were up to 30 µm long. They grew preferentially along the 〈11$ \bar 2 $0〉 crystal direction and possessed excellent optical and mechanical properties. It was shown using monochromatic cathodoluminescence that nanorods emit light both at 320 nm and 350 nm over entire length proving uniform coating of the Al0.06Ga0.94N rod core by an Al0.22Ga0.78N shield. The elastic modulus of nanorod material was found to be 185 GPa. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Strain in a ‐plane GaN layers grown on r ‐plane sapphire substrates
Authors: Roder C. , Einfeldt S. , Figge S. , Hommel D. , Paskova T. , Monemar B. , Haskell B. A. , Fini P. T. , Speck J. S. , Nakamura S.
Published: May 2006

The strain in a ‐plane GaN layers of different thickness grown on r ‐plane sapphire substrates by hydride vapor phase epitaxy was studied by X‐ray diffraction. The layers are found to be under compression in the growth plane and under tension in the growth direction. Therefore, the symmetry of the GaN unit cell is no longer hexagonal but orthorhombic. With increasing layer thickness the strain relaxes and the curvature of the wafer increases. Wafer bending is proposed to be the major strain relaxation mechanism. The anisotropic in‐plane strain relaxation is attributed to the elastic and thermal anisotropy of GaN and sapphire. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Investigation of reaction mechanisms by electrospray ionization mass spectrometry: characterization of intermediates in the degradation of phenol by a novel iron/magnetite/hydrogen peroxide heterogeneous oxidation system
Authors: Moura Flávia C. C. , Araujo Maria H. , Dalmázio Ilza , Alves Tânia M. A. , Santos Leonardo S. , Eberlin Marcos N. , Augusti Rodinei , Lago Rochel M.
Published: May 2006

Electrospray ionization (ESI) mass spectrometry (MS) and tandem mass spectrometry (MS/MS) were used to monitor the oxidation of phenol by a novel heterogeneous Fenton system based on a Fe0/Fe3O4 composite and H2O2. On‐line ESI‐MS(/MS) shows that this heterogeneous system promotes prompt oxidation of phenol to hydroquinone, which is subsequently oxidized to quinone, other cyclic poly‐hydroxylated intermediates and an acyclic carboxylic acid. A peroxide‐type intermediate, probably formed via an electrophilic attack of HOO. on the phenol ring, was also intercepted and characterized. ESI‐MS(/MS) monitoring of the oxidation of two other model aromatic compounds, benzene and chlorobenzene, indicates the participation of analogous intermediates. These results suggest that oxidation by the heterogeneous system is promoted by highly reactive HO. and HOO. radicals generated from H2O2 on the surface of the Fe0/Fe3O4 composite via a classical Fenton‐like mechanism. Copyright © 2006 John Wiley & Sons, Ltd.
Simultaneous determination of low levels of methotrexate and cyclophosphamide in human urine by micro liquid chromatography/electrospray ionization tandem mass spectrometry
Authors: Barbieri Anna , Sabatini Laura , Indiveri Paolo , Bonfiglioli Roberta , Lodi Vittorio , Violante Francesco S.
Published: May 2006

The aim of this study was to develop and validate a novel solid‐phase extraction (SPE) liquid chromatography/tandem mass spectrometry (LC/MS/MS) method for the simultaneous determination of two antineoplastic drugs, cyclophosphamide (CP) and methotrexate (MTX), in human urine using trophosphamide as internal standard. The method showed good precision and accuracy (mean RSD 2.8% and 0.9%; bias 2.7% and 2.4% for MTX and CP, respectively). The lower limits of detection obtained, 0.2 µg/Lurine for MTX and 0.04 µg/Lurine for CP, were lower than the best previously reported values. The use of a 96‐well SPE plate for matrix purification ensures a high throughput (50 samples/day), allowing the routine biological monitoring of CP and MTX as measures of occupational exposure at very low levels. Copyright © 2006 John Wiley & Sons, Ltd.
Determination of phenylalanine in human serum by isotope dilution liquid chromatography/tandem mass spectrometry
Authors: Lee Hwashim , Park Sangryoul , Lee Gaeho
Published: May 2006

Isotope dilution liquid chromatography/tandem mass spectrometry (ID‐LC/MS/MS) has been developed as a candidate reference method to determine the level of phenylalanine in human serum. The advantages of this method include a simple sample preparation without derivatization, selective detection of analytes, and the use of an isotopic analogue as an internal standard. Phenylalanine and its isotopic analogue, phenylalanine‐ring‐13C6, were monitored at the transitions m/z 166.2/120.2 and 172.2/126.2 in the multiple‐reaction monitoring (MRM) mode, respectively. The expanded uncertainty of the measurement result of phenylalanine in the serum was approximately 1.2% within a 95% confidence level. A standard reference material, with a certified value of phenylalanine, was analyzed in order to verify this method. The result obtained by the ID‐LC/MS/MS method differed somewhat from the certified value, but agreed well with the gravimetric value. The measurement result of phenylalanine in serum by ID‐LC/MS/MS was compared with the results from the commercial HPLC method, which was carried out in clinics. The results from the commercial HPLC method showed inconsistent results with each other. The busted results from the commercial HPLC method suggest that it should be possible to trace the results of the commercial fields to well‐characterized reference materials or methods. Copyright © 2006 John Wiley & Sons, Ltd.
High‐throughput quantification of perindopril in human plasma by liquid chromatography/tandem mass spectrometry: application to a bioequivalence study
Authors: Nirogi Ramakrishna V. S. , Kandikere Vishwottam N. , Shukla Manoj , Mudigonda Koteshwara , Maurya Santosh , Komarneni Prashanth
Published: May 2006

A simple, sensitive and rapid high‐performance liquid chromatography/positive ion electrospray tandem mass spectrometry method was developed and validated for the quantification of perindopril in human plasma. Following liquid‐liquid extraction, the analytes were separated using an isocratic mobile phase on a reversed‐phase column and analyzed by mass spectrometry in the multiple reaction monitoring mode using the respective [M+H]+ ions, m/z 369/172 for perindopril and m/z 417/234 for the internal standard. The method exhibited a linear dynamic range of 0.1–100 ng/mL for perindopril in human plasma. The lower limit of quantification was 0.1 ng/mL with a relative standard deviation of less than 6.1%. Acceptable precision and accuracy were obtained for concentrations over the standard curve range. A run time of 2.0 min for each sample made it possible to analyze more than 450 human plasma samples per day. The validated method has been successfully used to analyze human plasma samples for application in pharmacokinetic, bioavailability and bioequivalence studies. Copyright © 2006 John Wiley & Sons, Ltd.
Hybrid density functional theory study of fragment ions generated during mass spectrometry of 1,3‐dioxane derivatives
Authors: Albu Titus V.
Published: May 2006

It was recently reported that the cis,cis and trans,trans diastereoisomers of four 2(r)‐R‐2,4(R),6(S)‐trimethyl‐1,3‐dioxane derivatives show distinct electron ionization mass spectra. As a possible explanation for this finding, the authors suggested that the ions generated during the mass spectrometry of these compounds could follow different fragmentation patterns that initiate from different ion conformations. In this report, hybrid density functional theory methods have been used to investigate the conformational preference of three ions involved in the mass spectrometry of some 1,3‐dioxane derivatives. We found that there is indeed more than one stable ion conformation for each of the investigated ions. Energy profiles along the torsional coordinates connecting the conformers are presented, and factors influencing the relative stability of ion conformations are discussed. Copyright © 2006 John Wiley & Sons, Ltd.
Precursor ion scanning for the non‐targeted detection of individual arsenosugars in extracts of marine organisms
Authors: Kanaki Katerina , Pergantis Spiros A.
Published: May 2006

Arsenosugars are a group of arsenic compounds reported to be present in a wide variety of marine organisms. Numerous such compounds have been identified and characterized in marine organisms; however, unknown arsenosugar species may also be present. This indicates the need for an analytical technique suitable for their non‐targeted detection. One such technique is tandem mass spectrometry operated in the precursor ion scanning mode. This technique is based on scanning for precursor ions that give specific product ions, characteristic of the compounds under investigation. In the present study two subgroups of arsenosugar species were examined, the oxo‐ and the thioarsenosugars, the CID behavior of which is well known from previous studies. In the case of the oxoarsenosugars characteristic product ions were observed at m/z 237 and 97, and for the thioarsenosugars at m/z 253 and 97. Validation of this approach was carried out by analyzing extracts of two commercial kelp powders with known contents of arsenosugar species. All arsenosugars reported to exist in these materials were detected successfully using the precursor ion scanning approach. The limits of detection for the oxo‐ and the thioarsenosugar species, and the selectivity and sensitivity of the method, strongly indicate the suitability of this approach for the non‐targeted detection of arsenosugars in extracts of marine origin. Copyright © 2006 John Wiley & Sons, Ltd.
Analysis of isotope ratios in vitamin K1 (phylloquinone) from human plasma by gas chromatography/mass spectrometry
Authors: Jones Kerry S. , Bluck Leslie J. C. , Coward W. Andy
Published: May 2006

Vitamin K1 is a fat‐soluble vitamin required for the γ‐carboxylation of vitamin K‐dependent proteins. Recent work has suggested an important role for vitamin K1 in bone health beyond its more established function in the control and regulation of blood coagulation. However, current UK recommended intakes do not reflect this recent evidence. The use of stable isotopes provides a powerful tool to investigate vitamin K kinetics, turnover and absorption in man, although published methods have reported difficulties in the extraction and analysis of isotope ratios of vitamin K in human plasma. In this paper, we report a new methodology for the extraction and measurement of isotope ratios in vitamin K1. Sample clean‐up is achieved with liquid‐liquid extraction, enzyme hydrolysis with lipase and cholesterol esterase, and solid‐phase extraction. Isotopic analysis of the pentafluoropropionyl derivative of vitamin K1 is performed by gas chromatography/mass spectrometry (GC/MS). The limit of quantitation is equivalent to at least 0.3 nmol/L and the method is demonstrated to be linear over a range of enrichments. This method provides a robust alternative to previous work requiring the use of semi‐preparative high‐performance liquid chromatography (HPLC). Copyright © 2006 John Wiley & Sons, Ltd.
Human papillomavirus vaccines
Authors: Stanley Margaret A.
Published: May 2006

A wealth of epidemiological and molecular evidence has led to the conclusion that virtually all cases of cervical cancer and its precursor intra‐epithelial lesions are a result of infection with one or other of a subset of genital human papillomaviruses (HPVs) suggesting that prevention of infection by prophylactic vaccination would be an effective anti‐cancer strategy. The papillomaviruses cannot be grown in large amounts in culture in vitro, but the ability to generate HPV virus like particles (VLPs) by the synthesis and self‐assembly in vitro of the major virus capsid protein L1 provides for a potentially effective sub unit vaccine. HPV L1 VLP vaccines are immunogenic and have a good safety profile. Published data from proof of principle trials and preliminary reports from large Phase III efficacy trials suggest strongly that they will protect against persistent HPV infection and cervical intra epithelial neoplasia. However, the duration of protection provided by these vaccines is not known, the antibody responses induced are probably HPV type specific and immunisation should occur pre‐exposure to the virus. Second generation vaccines could include an early antigen for protection post‐exposure and alternative delivery systems may be needed for the developing world. Copyright © 2006 John Wiley & Sons, Ltd.
Vaccinia virus proteolysis—a review
Authors: Byrd Chelsea M. , Hruby Dennis E.
Published: May 2006

It is well known that viruses, as obligate intracellular parasites, must use their hosts' metabolic machinery in order to replicate their genomes and form infectious progeny virions. What is less well known are the details of how viruses make sure that once all the necessary proteins are made, that they assume the correct configuration at the proper time in order to catalyse the efficient assembly of infectious virions. One of the methods employed by viruses to regulate this process is the proteolytic cleavage of viral proteins. Over the past several decades, studies in numerous laboratories have demonstrated that morphogenic proteolysis plays a major and essential role during the assembly and maturation of infectious poxvirus virions. In this review we describe the history of vaccinia virus proteolysis as a prototypic viral system. Copyright © 2006 John Wiley & Sons, Ltd.
Morphine withdrawal syndrome and its prevention with baclofen: Autoradiographic study of μ‐opioid receptors in prepubertal male and female mice
Authors: Diaz Silvina L. , Barros Virginia G. , Antonelli Marta C. , Rubio Modesto C. , Balerio Graciela N.
Published: May 2006

Although the expression of the morphine (MOR) withdrawal syndrome is more marked in male mice than in females, we have demonstrated that the GABABagonist baclofen (BAC) is able to attenuate MOR withdrawal signs in either sex. In order to extend these previous observations, the aim of the present study was to evaluate the μ‐opioid receptor labeling in various brain areas in mice of either sex, during MOR withdrawal and its prevention with BAC. Prepubertal Swiss‐Webster mice were rendered dependent by intraperitonial (i.p.) injection of MOR (2 mg/kg) twice daily for 9 days. On the 10th day, dependent animals received naloxone (NAL; 6 mg/kg, i.p.) 60 min after MOR, and another pool of dependent mice received BAC (2 mg/kg, i.p.) previous to NAL. Thirty minutes after NAL, mice were sacrificed and autoradiography with [3H]‐[D‐Ala2,N‐Me‐Phe4, ‐glycol5] enkephalin (DAMGO) was carried out on mice brains at five different anatomical levels. Autoradiographic mapping showed a significant increase of μ‐opioid receptor labeling during MOR withdrawal in nucleus accumbens core (NAcC), caudate putamen (CPu), mediodorsal thalamic nucleus (MDTh), basolateral and basomedial amygdala, and ventral tegmental area vs. respective control groups in male mice. In contrast, opiate receptor labeling was not significantly modified in any of the brain areas studied in withdrawn females. BAC reestablished μ‐opioid receptor binding sites during MOR withdrawal only in NAcC of males, and a similar tendency was observed in CPu and MDTh, even when it was not statistically significant. The sexual dimorphism observed in the present study confirms previous reports indicating a greater sensitivity of males in response to MOR pharmacological properties. The present results suggest that the effect of BAC in preventing the expression of MOR withdrawal signs could be related with the ability of BAC to reestablish the μ‐opioid receptor labeling in certain brain areas. Synapse 60:132–140, 2006. © 2006 Wiley‐Liss, Inc.
[123I]TPCNE—A novel SPET tracer for the sigma‐1 receptor: First human studies and in vivo haloperidol challenge
Authors: Stone James M. , Årstad Erik , Erlandsson Kjell , Waterhouse Rikki N. , Ell Peter J. , Pilowsky Lyn S.
Published: May 2006

[123I]TPCNE (1(trans‐[123I]iodopropen‐2‐yl)‐4‐[(4‐cyanophenoxy)methyl] piperidine; Ki = 0.67 nM; log P = 3.36) is a novel sigma‐1 receptor SPET ligand. In this study, we developed an optimized labeling method for [123I]TPCNE and investigated the kinetics, binding characteristics, and whole‐body distribution of this tracer for the first time in humans. We also performed a challenge with the sigma‐1 receptor antagonist haloperidol against [123I]TPCNE.

Seven healthy volunteers were recruited. Dynamic brain SPET scans were performed following i.v. administration of 185 MBq [123I]TPCNE in all seven subjects. Three of the subjects were given oral haloperidol (2.5 mg) ∼1 h before the scan. The dynamic data were analyzed with both reversible and irreversible compartmental models.

[123I]TPCNE showed high uptake in brain and liver. All non‐haloperidol‐treated subjects showed a high whole‐brain uptake (average: 8.7% of injected activity). No significant clearance of the tracer was seen up to 30 h post injection. In the haloperidol‐treated subjects, the time–activity curves clearly demonstrated clearance of the tracer from the brain. Regional radioactivity concentrations were reduced by haloperidol from 42% in the cerebellum to 73% in the thalamus.

[123I]TPCNE demonstrated high brain uptake, with highest binding found in the posterior cingulate. A region in which binding was unaffected by haloperidol pretreatment could not be identified, and the time–activity data were best described by an irreversible model. Synapse 60:109–117, 2006. © 2006 Wiley‐Liss, Inc.
Is psychological stress in man associated with increased striatal dopamine levels?: A [11C]raclopride PET study
Authors: Montgomery Andrew J. , Mehta Mitul A. , Grasby Paul M.
Published: May 2006

In rodents, stress causes rapid increases in extracellular dopamine (DA) concentration in cortical and subcortical brain regions, and positron emission tomography (PET) studies in healthy humans have suggested psychological and pharmacological stressors are associated with increased DA concentration in the striatum. In this experiment, we measured the effect of stress, induced by difficult mental arithmetic, on [11C]raclopride binding in order to index striatal DA release. To refine measurements and facilitate interpretation of results a combination of head movement correction, a carefully designed control condition and bolus infusion administration of [11C]raclopride were employed. Fourteen healthy volunteers were scanned using [11C]raclopride PET. Physiological and psychological responses to the task were consistent with a stress response with changes in cardiovascular, hormonal, and subjective state indices. No change of ventral or dorsal striatal [11C]raclopride binding was found in the stress condition compared to nonstress. This negative result suggests that significant DA release does not occur in the striatum in healthy humans after mild, psychological stress. Synapse 60:124–131, 2006. © 2006 Wiley‐Liss, Inc.
Reduced basal and ethanol stimulation of striatal extracellular dopamine concentrations in dopamine D2 receptor knockout mice
Authors: Job Martin O. , Ramachandra Vorani , Anders Sheneil , Low Malcolm J. , Gonzales Rueben A.
Published: May 2006

The present study was undertaken to examine the role of the dopamine (DA) D2 receptor in the ethanol‐evoked DA response in the ventral striatum. We performed microdialysis experiments using the D2 null mutant and wild‐type controls and measured the effect of an intraperitoneal (i.p.) injection of either saline or ethanol (2 g/kg) on dialysate DA concentrations in the ventral striatum. Dialysate ethanol concentrations were also determined in the samples from the ventral striatum. In addition, the effects of quinpirole, a D2/D3 agonist, were examined in both the ventral and dorsal striatum. Basal dialysate concentrations of DA were significantly reduced in both the ventral and dorsal striatum of the D2 knockouts compared with wild‐type controls. Ethanol administration significantly enhanced ventral striatal DA in both groups, but the increase in dialysate DA concentration was 3.5‐fold higher in the wild‐type controls. The time course of dialysate ethanol concentrations was similar in the two groups. Saline injection did not alter DA concentrations in either the ventral or dorsal striatum. However, quinpirole (0.3 mg/kg) administration significantly depressed striatal dialysate DA concentrations in the wild‐type mice, but not in the D2 knockouts. The results suggest that the D2 receptor is necessary for normal development and regulation of striatal extracellular DA concentrations, but the mechanism for this alteration is unclear. In addition, the blunted ethanol‐evoked DA response in the D2 knockouts may contribute, in part, to some of the behavioral deficits previously observed in response to ethanol. Synapse 60:158–164, 2006. © 2006 Wiley‐Liss, Inc.
High resolution spatial mapping of nicotine action using pharmacologic magnetic resonance imaging
Authors: Choi Ji‐kyung , Mandeville Joseph B. , Chen Y. Iris , Kim Young R. , Jenkins Bruce G.
Published: May 2006

Nicotine is one of the most addictive substances known. To better understand the mechanisms of action, we mapped the regional brain response to nicotine administration using pharmacologic magnetic resonance imaging (phMRI) in rats. We measured the regional response of relative cerebral blood volume (rCBV) in rats to a challenge of 0.07 mg/kg (0.43 μmol/kg) of nicotine. The areas of the brain with significant and reproducible changes in the rCBV response were (in descending order of magnitude) infralimbic cortex, hippocampus (subiculum), agranular insular/pyriform cortex, visual cortex, interpeduncular area, nucleus accumbens, cingulate cortex, thalamus, and septum. This pattern of response is consistent with stimulation of both cholinergic and dopaminergic neuronal pathways and is consistent with the known behavioral properties of nicotine. The peak CBV response to nicotine occurred between 9 and 13 min depending upon brain region, and the average full width half‐maximum of the rCBV response was 27 min. The high spatial and temporal resolution of the phMRI technique lends itself well to further, more detailed, studies of nicotine dynamics. Synapse 60:152–157, 2006. © 2006 Wiley‐Liss, Inc.
Inhibition of the glycine transporter GlyT‐1 potentiates the effect of risperidone, but not clozapine, on glutamatergic transmission in the rat medial prefrontal cortex
Authors: Konradsson Åsa , Marcus Monica M. , Hertel Peter , Svensson Torgny H. , Jardemark Kent E.
Published: May 2006

Clinical studies suggest that the efficacy of the atypical antipsychotic drug (APD) risperidone (but not clozapine) can be augmented by adjunctive treatment with agonists at the glycine site of theN‐methyl‐D‐aspartate (NMDA) receptor. By using intracellular recording, we have investigated the effect of the glycine transporter‐1 (GlyT‐1) inhibitorN[3‐(4′‐fluorophenyl)‐3‐(4′phenylphenylphenoxy) propyl] sarcosine (NFPS) on NMDA‐induced currents in pyramidal cells of the medial prefrontal cortex (mPFC), both when given alone and in combination with either risperidone or clozapine. Both risperidone and clozapine enhanced the NMDA‐induced currents. The concentration–response curves were biphasic, and the maximal effect of clozapine on the NMDA‐induced currents was significantly larger than the maximal effect of risperidone. NFPS also significantly potentiated the NMDA‐induced currents, when given alone. Moreover, NFPS (1 μM) augmented the effect of both the maximal (20 nM), and a submaximal (10 nM), concentration of risperidone. In contrast, NFPS did not potentiate either the effect of the maximal (100 nM) or a submaximal (80 nM) concentration of clozapine on the NMDA‐induced currents. These data may explain the beneficial clinical results of using glycine reuptake antagonists as adjuvant treatment to risperidone. Our findings also suggest that risperidone and clozapine may affect NMDA receptor‐mediated neurotransmission differently in the mPFC. Synapse 60:102–108, 2006. © 2006 Wiley‐Liss, Inc.
Homologous down‐regulation of histamine H3receptors in rat striatal slices
Authors: Garduño‐Torres Belén , Arias‐Montaño José‐Antonio
Published: May 2006

Preincubation of striatal slices with the selective histamine H3‐receptor agonist immepip (100 nM) decreased the specific binding ofN‐α‐[methyl‐3H]‐histamine ([3H]‐NMHA) to membranes obtained from the treated slices. The binding decrease was significant after 5 min, remained at similar reduced levels between 5‐ and 30‐min incubations with agonist, and only a partial recovery was observed after 90‐min washout (34, 41, and 44% at 90, 120, and 150 min, respectively). Saturation analysis showed a significant decrease in both receptor density (−44% ± 9%) and affinity (dissociation constant,Kd1.15 ± 0.23 nM from 0.59 ± 0.17 nM). The effect of immepip was mimicked by histamine and the H3agonists imetit andR‐α‐methylhistamine, and was blocked by the H3antagonist thioperamide. The reduction in [3H]‐NMHA binding was fully and partially prevented by incubation at 4°C and in hypertonic medium, respectively, but not by the endocytosis inhibitor phenylarsine oxide (10 μM). None of the following protein kinase inhibitors, Ro‐318220 and Gö‐6976 (PKC), H‐89 (PKA) and staurosporine (general inhibitor) prevented the effect of immepip. In [3H]‐adenine‐labeled slices the preincubation with immepip (100 nM, 15 min) prevented the inhibitory effect of H3receptor activation on forskolin‐induced [3H]‐cAMP accumulation (99% ± 9% vs. 76% ± 4% of control values). Taken together our results indicate that agonist binding promotes the down‐regulation of striatal H3receptors resulting in a significant loss of function. Synapse 60:165–171, 2006. © 2006 Wiley‐Liss, Inc.
In vivo characterization of the pharmacokinetics and pharmacological properties of [11C]‐(+)‐PHNO in rats using an intracerebral beta‐sensitive system
Authors: Galineau Laurent , Wilson Alan A. , Garcia Armando , Houle Sylvain , Kapur Shitij , Ginovart Nathalie
Published: May 2006

This study reports on the binding kinetics and pharmacological characterization of [11C]‐(+)‐PHNO ((+)‐4‐propyl‐3,4,4a,5,6,10b‐hexahydro‐2H‐naphtho[1,2‐b][1,4]oxazin‐9‐ol), a promising agonist radiotracer for in vivo evaluation of the D2‐receptor. Its in vivo kinetics were monitored in rat striatum and cerebellum using a β‐sensitive Microprobe system. Control studies showed that [11C]‐(+)‐PHNO binding was reversible and reached a peak time equilibrium of specific binding in striatum 30 min after radiotracer injection. The binding potential (BP) calculated by the simplified reference tissue model was 3‐fold higher than that measured with [11C]‐(−)‐NPA (2.14 ± 0.50 vs. 0.66 ± 0.01, respectively). In contrast, the methyl analog of (+)‐PHNO, [11C]‐(+)‐MHNO, which displayed promising D2‐agonist properties in vitro, showed no specific binding in the striatum in vivo. [11C]‐(+)‐PHNO binding was totally blocked by raclopride (1 mg/kg; i.v.) and 97% displaced by NPA (2 mg/kg; i.v.) suggesting that [11C]‐(+)‐PHNO was specific for the high affinity states of D2/D3‐receptors. However, (+)‐PHNO (1 mg/kg; i.v.) totally blocked and displaced [11C]‐raclopride binding in striatum. Thus, (+)‐PHNO at high concentrations might be able to bind to the low affinity states of D2/D3‐receptors. After an amphetamine pretreatment (2 mg/kg; i.v.), a 69% decrease in BP value (P< 0.05) was observed for [11C]‐(+)‐PHNO indicating that its binding was highly sensitive to variations of endogenous DA. These results substantiate the use of [11C]‐(+)‐PHNO as an agonist radiotracer for D2‐imaging. The sensitivity of its binding to competition with endogenous DA suggests an association with the subset of high affinity state D2‐receptors. Synapse 60:172–183, 2006. © 2006 Wiley‐Liss, Inc.
A longitudinal study of conceptual change: Preservice elementary teachers' conceptions of moon phases
Authors: Trundle Kathy Cabe , Atwood Ronald K. , Christopher John E.
Published: May 2006

This research consists of a longitudinal study of 12 female elementary preservice teachers' conceptual understanding over the course of several months. The context in which the participants received instruction was in an inquiry‐based physics course, and the targeted science content was the cause of moon phases. Qualitative research methods, including observations and interviews, were used to investigate and describe participants' conceptual understanding over time. Participants were interviewed on their understanding of the cause of moon phases before instruction, 3 weeks after instruction, and again in delayed post‐interviews several months after instruction. Patterns and themes in the participants' conceptual understanding were identified through constant‐comparative data analysis. Consistent with results reported earlier, participants who had instruction that included recording and analyzing moon observations over time and psychomotor modeling of changes in moon phases were very likely to hold a scientific conceptual understanding shortly after instruction. The present study indicates a majority of participants continued to hold a scientific understanding six months or more after instruction. However, some participants reverted to alternative conceptions they had shown during the pre‐interview. These results are interpreted utilizing contemporary conceptual change theory. © 2006 Wiley Periodicals, Inc. J Res Sci Teach 44: 303–326, 2007
Ultrasonographic characteristics and cystoscopic correlates of bladder wall invasion by endophytic cervical cancer
Authors: Huang W.‐C. , Yang J.‐M. , Yang Y.‐C. , Yang S.‐H.
Published: May 2006

Objectives

To present the ultrasonographic findings and explore cystoscopic correlates of endophytic cervical cancer invading the bladder wall.

Methods

We retrospectively reviewed the imaging files in 19 cases of cervical cancer, comprising six cases of endophytic lesions invading the bladder wall (study group) and 13 cases of endo‐ or exophytic, clinical stage IB1 lesions without bladder wall invasion (controls). Bladder wall infiltration or invasion was confirmed by cystoscopic biopsy or surgical findings or both. All 19 patients had undergone transvaginal ultrasound examination to evaluate the cervix and lower urinary tract. The main measures included tumor volume of the primary cervical neoplasm, tumor protuberance, mobility of the cervix over the lower bladder wall, continuity of the endopelvic fascia and echogenicity and morphological texture of the bladder wall and its thickness.

Results

A tumor protuberance emerging from the cervicocorporeal junction and invading the bladder in the supratrigonal area was seen in the study group but not in the controls. Disruption of the endopelvic fascia, a thickened bladder wall, changes in the bladder mucosa and interruption of the entire bladder wall were ultrasonographic characteristics demonstrating the sequential stages of bladder wall invasion. The morphological changes in the bladder wall on ultrasound examination were categorized into four stages. Based on the morphological classification, two of the six patients in the study group belonged to stage I, one to stage II, one to stage III and two to stage IV of bladder wall invasion.

Conclusions

In cervical cancer, transvaginal ultrasonography helps to explore sequential changes seen in bladder wall invasion, information that is not as readily available from cystoscopic examination. Copyright © 2006 ISUOG. Published by John Wiley & Sons, Ltd.
Two‐ and three‐dimensional ultrasonographic findings in urethral stenosis with bladder wall trabeculation: case report
Authors: Huang W.‐C. , Yang S.‐H. , Yang J.‐M.
Published: May 2006

Female bladder outlet obstruction is uncommon. We report a case of bladder outlet obstruction secondary to urethral stenosis leading to bladder wall trabeculation. The patient presented at our clinic because of lower urinary tract symptoms including nocturia, urgency, bed wetting, hesitancy, straining to void, and incomplete emptying. Urodynamic study revealed a low maximum free uroflow rate, high residual urine volume, and low compliance on filling phase cystometry. Introital ultrasonography with two‐ and three‐dimensional (2D and 3D) scanning displayed a constriction in the echolucent part of the lower‐mid urethra with hyperechogenicity and a lattice‐like appearance of the bladder wall. Cystourethroscopy confirmed urethral stenosis and bladder wall trabeculation. The voiding symptoms subsided after the urethral stenosis was relieved by urethral dilatation, but, despite some improvement, the irritative symptoms persisted. Introital ultrasonography with 2D and 3D scanning may help to clarify the cause of female bladder outlet obstruction. Copyright © 2006 ISUOG. Published by John Wiley & Sons, Ltd.
Is measurement of nuchal translucency thickness a useful screening tool for heart defects? A study of 16 383 fetuses
Authors: Westin M. , Saltvedt S. , Bergman G. , Almström H. , Grunewald C. , Valentin L.
Published: May 2006

Objective

To determine the performance of nuchal translucency thickness (NT) measurement as a screening method for congenital heart defects (CHD) among fetuses with normal karyotype.

Methods

An NT measurement was made in 16 383 consecutive euploid fetuses derived from an unselected pregnant population. The cut‐offs for increased risk of heart defects, chosen a priori and tested prospectively, were: NT ≥ 95th centile for crown–rump length, NT ≥ 3 mm, and NT ≥ 3.5 mm. The sensitivity and false‐positive rate (FPR; 1 minus specificity) of the risk cut‐offs and their positive and negative likelihood ratios (+LR and −LR) with regard to CHD were calculated.

Results

Among the 16 383 fetuses with an NT measurement there were 127 cases with a diagnosis of heart defect confirmed by cardiac investigations after birth or at autopsy. Of these, 55 defects were defined as major, of which 52 were isolated (no other defects or chromosomal aberrations), corresponding to a prevalence of major heart defects in chromosomally normal fetuses/newborns of 3.3/1000. The sensitivity, FPR, +LR and −LR for NT ≥ 95th centile with regard to an isolated major heart defect were: 13.5%, 2.6%, 5.2 and 0.9, respectively. For NT ≥ 3.0 mm these values were: 9.6%, 0.8%, 12.0 and 0.9, and for NT ≥ 3.5 mm they were: 5.8%, 0.3%, 19.3 and 0.9.

Conclusions

NT measurement is a poor screening method for isolated major CHD. A method with a much higher detection rate and with a reasonably low FPR is needed. However, increased NT indicates increased risk of fetal heart defect, and women carrying fetuses with increased NT should be offered fetal echocardiography in the second trimester. Copyright © 2006 ISUOG. Published by John Wiley & Sons, Ltd.
Three‐dimensional ultrasound volume calculations of human embryos and young fetuses: a study on the volumetry of compound structures and its reproducibility
Authors: Blaas H.‐G. K. , Taipale P. , Torp H. , Eik‐Nes S. H.
Published: May 2006

Objective

To evaluate volumetry with three‐dimensional (3D) ultrasonography in the assessment of the size of human embryos and fetuses.

Methods

Forty‐four healthy embryos/fetuses with crown–rump length (CRL) ranging from 9 mm to 58 mm were studied using a 7.5‐MHz annular array transvaginal 3D probe. EchoPAC 3D software was used to calculate the volumes of the head, body and limbs in the same data set by two observers working independently of each other. Regression analysis was used to assess the relationship between estimated volumes and CRL.

Results

The embryonic and fetal volume estimates of both observers ranged from a mean of 93 mm3 at 10 mm CRL to a mean of 11 169 mm3 at 55 mm CRL. The volume of the limbs as a proportion of the mean whole‐body volume increased from 4.7% at a CRL of 15 mm to 9.3% at a CRL of 55 mm. Limits of agreement between the observers were calculated to be −0.12 ± 9.2%.

Conclusion

It is possible to reconstruct complex small anatomic structures and calculate the volumes of human embryos and fetuses in vivo by using dedicated 3D ultrasound equipment. The reproducibility of whole‐body volume estimates seems to be high. The limbs represent a significant proportion of the size of the embryonic/fetal body. Copyright © 2006 ISUOG. Published by John Wiley & Sons, Ltd.
Transcriptional response to nitrosative stress in Saccharomyces cerevisiae
Authors: Horan Susannah , Bourges Ingrid , Meunier Brigitte
Published: May 2006

Nitric oxide and NO‐derived species (RNS) are defence molecules with broad antimicrobial activity. Microorganisms have developed strategies to sense RNS and counteract their damaging effects. We used Saccharomyces cerevisiae, harbouring a deletion of YHB1 that encodes the main NO scavenger enzyme, to study consequences of RNS exposure on whole‐genome transcriptional response. The expression of > 700 genes was altered on RNS treatment. No major role for ROS‐scavenging enzymes was found, and the respiratory chain, the main site of ROS production, had only minor involvement in the RNS‐induced stress. The changes were generally transient and also found after treatment with the respiratory inhibitor myxothiazol. However, 117 genes showed a persistent response that was not observed after myxothiazol treatment. Of these, genes of the glutathione and DNA repair systems, iron homeostasis and transport were found to be upregulated. Severe repression of genes of respiratory chain enzymes was observed. Many of these genes are known to be regulated by the transcription factor Hap1p, suggesting that RNS might interfere with Hap1p activity. We showed also that Msn2/4p and Yap1p, key regulators of the response to general stress and oxidative stress, respectively, played a role in mediating the RNS‐induced response. Copyright © 2006 John Wiley & Sons, Ltd.
Inorganic Polyphosphates and Exopolyphosphatases in Cell Compartments of the Yeast Saccharomyces cerevisiae Under Inactivation of PPX1 and PPN1 Genes
Authors: Lichko Lidiya , Kulakovskaya Tatyana , Pestov Nikolai , Kulaev Igor
Published: May 2006

Purified fractions of cytosol, vacuoles, nuclei, and mitochondria of Saccharomyces cerevisiae possessed inorganic polyphosphates with chain lengths characteristic of each individual compartment. The most part (80–90%) of the total polyphosphate level was found in the cytosol fractions. Inactivation of a PPX1 gene encoding ∼40-kDa exopolyphosphatase substantially decreased exopolyphosphatase activities only in the cytosol and soluble mitochondrial fraction, the compartments where PPX1 activity was localized. This inactivation slightly increased the levels of polyphosphates in the cytosol and vacuoles and had no effect on polyphosphate chain lengths in all compartments. Exopolyphosphatase activities in all yeast compartments under study critically depended on the PPN1 gene encoding an endopolyphosphatase. In the single PPN1 mutant, a considerable decrease of exopolyphosphatase activity was observed in all the compartments under study. Inactivation of PPN1 decreased the polyphosphate level in the cytosol 1.4-fold and increased it 2- and 2.5-fold in mitochondria and vacuoles, respectively. This inactivation was accompanied by polyphosphate chain elongation. In nuclei, this mutation had no effect on polyphosphate level and chain length as compared with the parent strain CRY. In the double mutant of PPX1 and PPN1, no exopolyphosphatase activity was detected in the cytosol, nuclei, and mitochondria and further elongation of polyphosphates was observed in all compartments.
Physical Limits on Self-Replication Processes
Authors: Alicki Robert
Published: May 2006

Using few very general axioms which should be satisfied by any reasonable theory consistent with the Second Law of Thermodynamics we argue that: a) "no-cloning theorem" is meaningful for a very general theoretical scheme including both quantum and classical models, b) in order to describe self-replication, Wigner's "cloning" process should be replaced by a more general "broadcasting", c) "separation of species" is possible only in a non-homogeneous environment, d) "parent" and "offspring" must be strongly correlated. Motivated by the existing results on broadcasting which show that only classical information can self-replicate perfectly we discuss briefly a classical toy model with "quantum features" — overlapping pure states and "entangled states" for composite systems.
Energy Levels of "Hydrogen Atom" in Discrete Time Dynamics
Authors: Khrennikov Andrei , Volovich Yaroslav
Published: May 2006

We analyze dynamical consequences of a conjecture that there exists a fundamental (indivisible) quant of time. In particular we study the problem of discrete energy levels of hydrogen atom. We are able to reconstruct potential which in discrete time formalism leads to energy levels of unperturbed hydrogen atom. We also consider linear energy levels of quantum harmonic oscillator and show how they are produced in the discrete time formalism. More generally, we show that in discrete time formalism finite motion in central potential leads to discrete energy spectrum, the property which is common for quantum mechanical theory. Thus deterministic (but discrete time!) dynamics is compatible with discrete energy levels.
A Concise Guide to Complex Hadamard Matrices
Authors: Tadej Wojciech , Życzkowski Karol
Published: May 2006

Complex Hadamard matrices, consisting of unimodular entries with arbitrary phases, play an important role in the theory of quantum information. We review basic properties of complex Hadamard matrices and present a catalogue of inequivalent cases known for the dimensions N = 2,…,16. In particular, we explicitly write down some families of complex Hadamard matrices for N = 12, 14 and 16, which we could not find in the existing literature.