bluuebunny/crossref_metadata_2025_split huggingface dataset:
Recruitment of FoxP2‐expressing neurons to area X varies during song development
Authors: Rochefort Christelle , He Xiaolu , Scotto‐Lomassese Sophie , Scharff Constance 
Published: February 2007

AbstractIn adult songbirds, neural progenitors proliferate along the lateral ventricles. After migration, many of the subsequently formed neuroblasts integrate into the song nuclei HVC and Area X that participate in auditory‐guided vocal motor learning and singing. Recruitment of postembryonically generated neurons into HVC, rodent hippocampus, and olfactory bulb has been linked to learning and memory. The cellular identity and the role of postembryonically generated neurons in Area X are unknown. Here we describe that the majority of new neurons in postembryonic Area X of male zebra finches expressed DARPP32 but not choline acetyltransferase or parvalbumin. This suggests that they are spiny neurons. Retrogradely labeled neurons projecting to thalamic nucleus DLM were not renewed. The spiny neurons in Area X were recently shown to express FoxP2, a transcription factor critical for normal speech and language development in humans. Since increased FoxP2 mRNA expression was previously observed during periods of vocal plasticity we investigated whether this increase might be associated with neuronal recruitment. Consistent with their spiny phenotype, new neurons in Area X did express FoxP2 and recruitment increased transiently during the juvenile song learning period. Moreover we found that FoxP2 was expressed in the ventricular zone of adult songbirds but was absent from the germinal zones in adult mouse brains, the hippocampus, and the subventricular zone. Together these results raise the possibility that neuronal recruitment and FoxP2 expression in Area X are associated with vocal learning. © 2007 Wiley Periodicals, Inc. Develop Neurobiol, 2007.
Hormonal and environmental control of song control region growth and new neuron addition in adult male house finches, Carpodacus mexicanus
Authors: Strand Christine R. , Deviche Pierre 
Published: February 2007

AbstractIn songbirds, testosterone (T) mediates seasonal changes in the sizes and neuroanatomical characteristics of brain regions that control singing (song control regions; SCRs). One model explaining the mechanisms of the growth of one SCR, the HVC, postulates that in the spring increasing photoperiod and circulating T concentrations enhance new neuron survival, thus increasing total neuron number. However, most research investigating the effects of T on new neuron survival has been done in autumn. The present study investigated the effects of photoperiod and T treatment on SCR growth and new neuron survival in the HVC in photosensitive adult male House Finches, Carpodacus mexicanus, under simulated spring‐like conditions. Birds were castrated, given T‐filled or empty Silastic capsules and maintained on short days (SD; 8L:16D) or long days (LD; 16L:8D). To mark new cells, birds received bromodeoxyuridine injections 11 days after experimental manipulations began and were sacrificed 28 days later. Testosterone treatment increased the sizes of two SCRs, the HVC and Robust nucleus of the arcopallium (RA). Exposure to LD did not affect HVC volume, but did increase RA volume. Testosterone treatment increased the total number of HVC neurons, but did not affect the number of new HVC neurons. Thus, T initiates SCR growth and increases neuron survival, but effects of T on new neuron incorporation may be limited in photosensitive birds under spring‐like conditions. These results provide new insight into the effects of photoperiod and T treatment on vernal SCR growth and new neuron incorporation and support current models explaining this growth. © 2007 Wiley Periodicals, Inc. Develop Neurobiol, 2007.
Impacts of distributed Raman amplification transmission technologies on terrestrial large‐capacity WDM systems
Authors: Masuda Hiroji , Tomizawa Masahito , Miyamoto Yutaka , Hagimoto Kazuo 
Published: February 2007

AbstractThe impact of distributed Raman amplification (DRA) technologies on long‐distance large‐capacity transmission systems is discussed from the viewpoint of improving the signal‐to‐noise ratio (SNR). First, we show the characteristics of this technology, which has brought significant improvement to the SNR, and its trends, the basic configuration for our proposed DRA system (a DRA/EDFA hybrid configuration), and safety aspects for high‐power pumped light. In addition, we show the merits of the DRA system, including the amount of improvement in the optical SNR, transmission fiber (DSF and SMF) dependence, and superiority of DSF over SMF (about 2 to 3 dB). Furthermore, in a long‐distance large‐capacity wavelength division multiplexing transmission field trial using DRA in the L band on DSF, we confirm good transmission characteristics. In other words, the impact of DRA technologies lies in the significant improvement of the SNR in terrestrial long‐distance large‐capacity optically amplified transmission systems with field‐installed fibers, and in the improvement of performance in systems utilizing these technologies. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 90(6): 20–28, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.20340
Design and implementation of a fully distributed ultrasonic positioning system
Authors: Minami Masateru , Morikawa Hiroyuki , Aoyama Tomonori 
Published: February 2007

AbstractIn the ubiquitous computing environment, the physical locations of persons and goods are extremely important information. In this paper, the design of a fully distributed localization system based on ultrasound, mainly for the indoor environment, is described. This system performs localization with as few positioning references as possible by an iterative technique. When such a localization method is used, deterioration of localization accuracy due to no‐line‐of‐sight signals and to accumulated errors is a problem. In this paper, the resolution of these problems is discussed and system evaluation by implementation experiments is carried out. With 24 devices, localization with an accuracy of about 20 cm is demonstrated. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 90(6): 17– 26, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.20249
A design of ΔΣ A‐D converter
Authors: Hayahara Etsuro , Aoki Ken'Ichi , Hirano Satoshi 
Published: February 2007

AbstractThe ΔΣ modulation A‐D converter is widely used in practice as a high‐resolution A‐D converter suitable for LSI implementation. However, in general, if the order of the loop filter in the ΔΣ modulation A‐D converter exceeds three, stability of the circuit is no longer guaranteed. In this paper, the relationship of the loop filter coefficients in the A‐D converter is studied. Based on the results, a design method is proposed for a higher‐order ΔΣ modulation A‐D converter such that stability is assured while maximizing the signal‐to‐noise (SN) ratio. Further, the results of a PSPICE simulation and experimental results obtained using individual components confirm that the present design method is sufficiently practical. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 90(6): 10– 16, 2007; Published online in Wiley InterScience (www.interscience. wiley.com). DOI 10.1002/ecjc.20269
CE‐ and HPLC‐TOF‐MS for the characterization of phenolic compounds in olive oil
Authors: Carrasco‐Pancorbo Alegría , Neusüß Christian , Pelzing Matthias , Segura‐Carretero Antonio , Fernández‐Gutiérrez Alberto 
Published: February 2007

AbstractWe present an easy and rapid method for the analysis of phenolic compounds in extra‐virgin olive oil by CZE coupled with ESI‐TOF‐MS. Optimum electrophoretic separation was obtained using a basic carbonate electrolyte. We thus achieved the determination of several important families (phenyl alcohols, phenyl acids, lignans, flavonoids, and secoiridoids) of the polar fraction of the olive oil. Furthermore, other “unknown” compounds were also identified. In addition to the CZE method, HPLC analyses were made, separating compounds belonging to the main families present in this polyphenolic fraction, as well as other new compounds. We compared the results obtained with both techniques and found it was possible to determine more than 45 compounds with both methods. The sensitivity, together with mass accuracy and true isotopic pattern of the TOF‐MS, allowed the identification of a broad series of known and so far not described phenolic compounds present in extra‐virgin olive oil.
Control of EOF in CE by different ways of application of radial electric field
Authors: Sázelová Petra , Kašička Václav , Koval Dušan , Prusík Zdeněk , Fanali Salvatore , Aturki Zeineb 
Published: February 2007

AbstractVarious ways of application of radial electric field for the control of electrokinetic potential and EOF in a home‐made device for CE are presented. The device comprises three high‐voltage power supplies, which are used to form a radial electric field across the fused‐silica capillary wall. One power supply provides the internal electric field – a driving force for electrophoretic migration of charged analytes and for the EOF. Two power supplies are connected to the ends of the outer low‐conductivity polymeric coating, which is formed by the dispersion of insoluble conductive copolymer of aniline and p‐phenylendiamine in polystyrene matrix (dissolved in N‐methylpyrrolidone) attached to the original outer polyimide coating of the capillary. They are able to constitute the external longitudinal electric field with variable values of electric potential at both ends of the outer coating. The potential gradient between the external and internal electric field is perpendicular to the capillary wall and forms a radial electric field across the capillary wall, which affects the electrokinetic potential at the solid–liquid interface and EOF inside the capillary. The developed device and methodology has been applied for the analysis of both chiral and achiral molecules such as terbutaline enantiomers and oligopeptides (diglycine and triglycine). The effect of magnitude, orientation, and different ways of application of the radial electric field on the flow rate of the EOF and on the speed, efficiency, and resolution of CZE separations of the above analytes in the internally noncoated fused‐silica capillaries have been evaluated.
Modulation of induced reversion frequency by nucleotide pool imbalance as a tool for mutant characterization
Authors: Randazzo Rosalba , di Leonardo A. , Bonatti Stefania , Abbondandolo A. 
Published: February 2007

AbstractAddition of thymidine (TdR) or deoxycytine (CdR) to the culture medium during posttreatment incubation affected the frequency of mutagen‐induced reversion in three hypoxanthine‐guanine phosphoribosyl transferase‐deficient mutants of V79 Chinese hamster cells. With two of the mutants (E20 and 13), reversions induced by N‐ethylnitrosourea, ethyl methanesulfonate, and methyl methanesulfonate were enhanced by TdR and were either decreased (E20) or not affected (13) by CdR. With the third mutant (E21), alkylating agent‐induced reversions were enhanced by CdR and decreased by TdR. Finally, 6‐amino‐2‐hydroxypurine induced reversions were enhanced by TdR in mutant I3 and were decreased by TdR or deoxyadenosine (AdR) and enhanced by CdR in mutant E21. An attempt was made to reconcile these results with simple mutation mechanisms, based on either G:C to A:T or A:T to G:C transitions. It is suggested that the present approach may add useful information to studies of specific revertibility of mammalian cell mutants with known mutagens.
Variation in the human lymphocyte sister chromatid exchange frequency as a function of time: Results of daily and twice‐weekly sampling
Authors: Tucker James D. , Christensen Mari L. , Strout Cheryl L. , McGee Keith A. , Carrano Anthony V. 
Published: February 2007

AbstractThe variation in lymphocyte sister chromatid exchange (SCE) frequency was investigated in healthy nonsmokers who were not taking any medication. Two separate studies were undertaken. In the first, blood was drawn from four women twice a week for 8 weeks. These donors recorded the onset and termination of menstruation and times of illness. In the second study, blood was obtained from two women and two men for 5 consecutive days on two separate occasions initiated 14 days apart. One donor participated in both studies. Analysis of the mean SCE frequencies in each study indicated that significant temporal variation occurred in each donor, and that more variation occurred in the longer study. Some of the variation was found to be associated with the menstrual cycle. Peaks in the SCE frequency were observed at times that corresponded approximately to ovulation and to the beginning and end of menstruation. In the daily study, most of the variation appeared to be random, but occasional day‐to‐day changes occurred that were greater than those expected by chance. To determine how well a single SCE sample estimated the pooled mean for each donor in each study, we calculated the number of samples that encompassed that donor's pooled mean within 1 or more standard errors. For both studies, about 75% of the samples encompassed the pooled mean within 2 standard errors. An analysis of high‐frequency cells (HFCs) was also undertaken. The results for each study indicate that the proportion of HFCs, compared with the use of Fisher's Exact test, is significantly more constant than the means, which were compared by using the t‐test. These results coupled with our previous work suggest that HFC analysis may be the method of choice when analyzing data from human population studies.
Binding of ethylene oxide in spermiogenic germ cell stages of the mouse after low‐level inhalation exposure
Authors: Sega G. A. , Owens J. G. 
Published: February 2007

AbstractMice received inhalation exposures of 3H‐labeled ethylene oxide (EtO) gas at levels from 0.65 to 3.2 parts per million‐hours (ppm‐hr), which are below the exposure limits currently allowed for humans. Subsequently, spermatozoa were recovered from the reproductive tracts of the animals over a two‐week period and assayed for the amount of bound EtO. A strong increase in the level of EtO binding occurred in late spermatid stages; these stages are also genetically sensitive to the action of EtO. The maximum binding of EtO in late spermatids amounted to 6 × 103 alkylations/sperm head/ppm‐hr of exposure. Alkylation of the DNA within the sperm accounted for a very small fraction of the total sperm head alkylation, averaging about 20 DNA alkylations per sperm per ppm‐hr of exposure over the two‐week period. However, alkylation of protamine, a protein unique to sperm cells, was found to be correlated with total sperm head alkylation and accounted for nearly all of the EtO binding. Protamine alkylation appears to be a significant cause of EtO‐induced genetic damage in spermiogenic cells of the mammal.
Differential sensitivity of mouse oocytes to colchicine‐induced aneuploidy
Authors: Mailhes John B. , Yuan Zhi Ping 
Published: February 2007

AbstractUnpublished results from our laboratory showed that colchicine increased the incidence of hyperploid mouse metaphase II (MII) oocytes when injected at the same time as human chorionic gonadotrophin (HCG). The objective of the present study was to determine whether the time of administering colchicine influenced the incidence of aneuploidy in MII oocytes. CD‐1 mice were given pregnant mare's serum (PMS) and, 48 hr later, HCG. An intraperitoneal injection of 0.2 mg/kg colchicine was given at +4, +2, 0, −2, or −4 hr relative to HCG. Oocytes were collected 17 hr post‐HCG and processed, and chromosomes were subsequently C‐banded. The percentage of hyperploid oocytes was 0.77, 2.56, 5.71, 7.79, 3.54, and 2.70 for control, +4, +2, 0, −2, or −4 hr pre/post‐HCG, respectively. Chi‐square analyses of these data demonstrated that colchicine significantly increases the proportion of aneuploid oocytes, and that the relative sensitivity of colchicine‐induced aneuploidy depends upon the time that this drug is administered relative to HCG.
Induction and transmission of chemically induced chromosome aberrations in female germ cells
Authors: Albanese R. 
Published: February 2007

AbstractFemale mice were dosed with a number of chemical clastogens. The dosed females were then mated 28.5, 6.5, and 0.5 days after dosing, corresponding to various developmental stages of oogenesis (ie, early pre‐antral to late antral stages). One‐cell embryos derived from these matings were then isolated and analysed for structural and/or numerical chromosome aberrations. Chromosome damage, either structural or numerical, was induced only in oocytes at the late antral stages of oogenesis (i.e. when females were dosed 0.5 days prior to mating). There were few chromosome aberrations in embryos obtained from females dosed 6.5 or 28.5 days prior to mating. The results show that the analysis of one‐cell embryos derived from the germ cells of dosed females is a potentially useful test system for the identification of chemically induced structural and numerical chromosome aberrations. However, the technically demanding methods involved in the preparation of these one‐cell embryos prevent their use for routine screening purposes.
Low oxygen tension, as found in tissues in vivo, alters the mutagenic activity of aristolochic acid I and II in primary fibroblast‐like rat cells in vitro
Authors: Maier Peter , Schawalder Hanspeter , Weibel Beatrice 
Published: February 2007

AbstractThe mutagenic activities of aristolochic acid I (AAI) and II (AAII), the two main components of aristolochic acid (AA), were tested for mutagenicity in vivo in a subcutaneous granulation tissue in rats and in vitro in the corresponding freshly isolated and cultured target cells. In vivo at equimolar dose, AAI induced 16 times more 6‐thioguanine resistant cells than AAII. Oxygen tension in vitro was adjusted to that found in vivo: in the subcutaneous connective tissue, the pO2 was determined to be 40 ± 9 mm Hg, which corresponds in vitro to an O2 concentration of 5% in the incubator atmosphere. In vitro, AAI was 19 times more mutagenic than AAII at this low oxygen tension but exhibited only 4 times greater activity than AAII under standard culture conditions. These results indicate that the genotoxic activity of AA in mammals is mainly caused by AAI and that the exposure of cells to AAI and AAII in vitro at low pO2 corresponds more closely to the metabolic situation in vivo. Therefore, the mutagenic potency of the two chemicals can only be estimated correctly at tissue oxygen tension. The influence of pO2 on the mutation frequencies seems to arise from a modulation of the activation/detoxification pathways.
Mutagenicity testing of ethylene oxide in Escherichia coli strains with different repair capacities
Authors: Kolman Ada , Näslund Maria 
Published: February 2007

AbstractMutagenicity of ethylene oxide in Escherichia coli B strains with different repair capacities was studied. Deficiencies in excision repair (uvrA, polA) led to a considerable increase in mutation frequency compared with that in the wild‐type strain and in strains deficient in error‐prone repair (recA, lexA).
Stability and inactivation of mutagenic drugs and their metabolites in the urine of patients administered antineoplastic therapy
Authors: Monteith D. K. , Connor T. H. , Benvenuto J. A. , Fairchild E. J. , Theiss J. C. 
Published: February 2007

AbstractUrine samples from patients administered mutagenic antineoplastic drugs are mutagenic in the Ames assay, and hence may pose a genotoxic hazard to hospital personnel or family members caring for the patient. The urine samples in the present study were tested for mutagenicity in several strains of Salmonella typhimurium that were uvr negative (TA98, TA100) or positive (TA102, UTH8413, UTH8414), and were analyzed for the presence of drugs and their metabolites using high‐pressure liquid chromatography (HPLC). Urine samples from cancer patients were kept at room temperature and their mutagenicity as well as the chemical stability of the drugs was tested for a period of 14 days. It was observed that, in general, the urine remained mutagenic for the 14‐day period while the parent compound degraded within the first seven days. An exception was cisplatin, which was chemically stable as platinum, but the urine decreased in mutagenicity with time. This decrease was probably the result of ligand exchange with the platinum. Inactivation methods were developed to reduce the genotoxic hazard posed by the mutagenic compounds in the urine. Cisplatin was inactivated by complexing with sodium diethyldithiocarbamate (DDTC). Oxidation of urine containing mitomycin C and doxorubicin (sodium thiosulfate must be added to urine containing doxorubicin) with 5.25% sodium hypochlorite solution (bleach) results in mutagenic inactivation. Urine containing cyclophosphamide and its metabolites was oxidized with alkaline potassium permaganate and the active degradation products trapped with sodium thiosulfate. Both chemical and mutagenic assays are necessary to determine the reduction of risk. Methods of inactivation of mutagenic urine developed in this study are both effective and practical for the reduction of exposure to genotoxic hazards.
A modified mouse peripheral blood lymphocyte culture system for cytogenetic analysis
Authors: Erexson Gregory L. , Kligerman Andrew D. 
Published: February 2007

AbstractA detailed methodology is presented for culturing mouse peripheral blood lymphocytes isolated on density gradients and stimulated to divide using either phytohem‐agglutinin, concanavalin A, or lipopolysaccharide. The techniques described yield more than sufficient numbers of mitotic cells for analyzing sister chromatid exchange, chromosome aberrations, and micronuclei following in vitro or in vivo exposure to chemicals or radiation.
Aneuploidy induction in Saccharomyces cerevisiae by two solvent compounds, 1‐methyl‐2‐pyrrolidinone and 2‐pyrrolidinone
Authors: Mayer Vernon W. , Goin Carol J. , Taylor‐Mayer Rhoda E. 
Published: February 2007

AbstractA number of solvent compounds that were tested in Saccharomyces cerevisiae were potent inducers of aneuploidy, although they did not induce any other genetic effects. As an extention of these earlier findings, 1‐methyl‐2‐pyrrolidinone was tested and was found to induce aneuploidy. Several structurally related compounds were also tested; 2‐pyrrolidinone induced aneuploidy, but succinimide, pyrrolidine, 1‐methylpyrrolidine, 1‐methyl‐3‐pyrrolidinol, and 2‐pyrrolidineethanol did not. Maleimide and its N‐hydroxy, N‐methyl, and N‐ethyl derivatives were also negative for aneuploidy induction.
In vitro BALB/3T3 cell transformation assay of nonoxynol‐9 and 1,4‐dioxane
Authors: Sheu Chingju W. , Moreland Frances M. , Lee Jung Keun , Dunkel Virginia C. 
Published: February 2007

AbstractThe spermicidal surfactant nonoxynol‐9 (Igepal CO‐630, GAF Corp.) and a potential impurity, 1,4‐dioxane, were tested in the in vitro cell transformation assay using BALB/3T3 cells. Two treatment periods, 48 hr and 13 days, were used. Nonoxynol‐9, tested at levels up to 10 μg/ml, did not induce transformation, whereas dioxane was very active in the induction of type III foci in the cultured BALB/3T3 cells.