bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis of carbon‐14 labeled 4‐[4‐[2‐[2‐[bis(4‐chlorophenyl) methoxy]ethyl sulfonyl][1‐14C]ethoxy]phenyl]‐1,1,1‐trifluoro‐2‐butanone
Authors: Dischino Douglas D. , Banville Jacques , Remillard Roger
Published: February 2003

Carbon‐14 labeled 4‐[4‐[2‐[2‐[bis(4‐chlorophenyl)methoxyethylsulfonyl] [1‐14C]ethoxy]phenyl]‐1,1,1‐trifluoro‐2‐butanone was prepared in a six step radioactive synthesis from 2‐bromo[1‐14C]acetic acid. The overall radiochemical yield was 2.2%. The specific activity of the final product was found to be 42μCi/mg with a radiochemical purity of >98%. Copyright © 2002 John Wiley & Sons, Ltd.
Synthesis and properties of radiolabeled CPTA–oligonucleotides
Authors: Wagner S. , Eritja R. , Zuhayra M. , Oberdorfer F. , Mohammed A. , Mier W. , Haberkorn U. , Eisenhut M.
Published: February 2003

A solid phase technique for the preparation of antisense oligodeoxynucleotides (ODNs) is described featuring 5′‐end conjugated 4‐[(1,4,8,11‐tetraazacyclotet‐radec‐1‐yl)‐methyl]benzoic acid (CPTA). Using Fmoc‐protected CPTA–C6 amidite, CPTA was conjugated to ODNs at the end of an automated DNA synthesis. To illustrate successful conjugations, the CPTA–ODNs were labeled with 99mTc using the stannous‐chloride reduction method. The resulting 99mTc complexes showed differences of stability between CPTA‐conjugated and CPTA‐unconjugated as well as 3′‐protected and 3′‐unprotected ODNs. Propane‐1,3‐diol 3′‐modification enhanced efficiently the stability of 99mTc labeled ODN against exonuclease degradation. Fmoc3CPTA‐C6 amidite turned out to be a versatile ligand for radiometal complexation at the 5′‐end. Copyright © 2002 John Wiley & Sons, Ltd.
Synthesis of tritium labelled arachidonic acid amide and ester derivatives with dopamine, serotonin, vanillylamine, and ethyleneglycol moieties
Authors: Shevchenko V.P. , Nagaev I.Yu. , Myasoedov N.F. , Yudushkin I.A. , Gretskaya N.M. , Bobrov M.Yu. , Bezuglov V.V.
Published: February 2003

Tritium labelled arachidonic acid amides with dopamine, serotonin, vanillyl‐amine and the ethyleneglycol ester moieties with high specific activity (120 Ci/mmol) and yield (70–90%) were prepared from tritiated arachidonic acid by condensation with the corresponding amines and alcohol via mixed anhydrides or acyl fluorides. The labelled compounds were used for studying their uptake by mouse spleen lymphocytes. From the data obtained it was suggested that arachidonic acid amides permeate the membrane by means of passive diffusion, while transmembrane transport of arachidonoylethyleneglycol seems to be driven by the concentration gradient, maintained by hydrolytic enzymes. The compounds synthesized by the reported methods can also be used in receptor binding studies and in the oxidative metabolism of fatty acids amides and esters. Copyright © 2002 John Wiley & Sons, Ltd.
FDTD analysis of higher‐order‐mode coupling effects in the crossed junctions of a planar slot array
Authors: Long Li , Yu Zhang , Huiqing Zhai , Changhong Liang
Published: February 2003

Higher‐order‐mode coupling effects between radiating slots and coupling slots in centered‐inclined and longitudinal‐transverse types of crossed rectangular waveguide junctions are effectively analyzed in this paper by using a modified locally conformal finite‐difference time‐domain (MLC‐FDTD) algorithm. The errors arising from this higher‐order‐mode coupling are given in terms of the equivalent network S parameter. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 36: 422–425, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10781
A superdirective 3‐element array for adaptive beamforming
Authors: Chaloupka H. J. , Wang X. , Coetzee J. C.
Published: February 2003

A small array composed of three monopole elements with very small element spacing on the order of λ/6 to λ/20 is considered for application in adaptive beamforming. The properties of this 3‐port array are governed by strong mutual coupling. It is shown that for signal‐to‐noise maximization, it is not sufficient to adjust the weights to compensate for the effects of mutual coupling. The necessity for an RF‐decoupling network (RF‐DN) and its simple realization are shown. The array with closely spaced elements together with the RF‐DN represent a superdirective antenna with a directivity of more than 10 dBi. It is shown that the required fractional frequency bandwidth and the available unloaded Q of the antenna and RF‐DN structure determine the lower limit for the element spacing. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 36: 425–430, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10782
The 2.5D FDTD and Fourier PSTD methods and applications
Authors: Tang Zibin , Liu Qing Huo
Published: February 2003

In this work, 2.5‐dimensional finite‐difference time‐domain (FDTD) and pseudospectral time‐domain (PSTD) algorithms are developed for electromagnetic waves in media that are invariant in one spatial dimension. Both algorithms use Berenger's perfect matched layer (PML) as an absorbing boundary condition. The FDTD method is an extension of Yee's 3D algorithm to 2.5D. The PSTD algorithm uses the fast Fourier transform to approximate spatial derivatives, and gives a much higher accuracy than the FDTD method. Numerical results have been validated by comparing them with analytical solutions. The methods have been applied to ground‐penetrating‐radar and dielectric‐waveguide problems. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 36: 430–436, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10783
Efficient analysis of microwave structures using a matrix interpolation method
Authors: Yeo Junho , Mittra Raj
Published: February 2003

This paper presents a new impedance matrix interpolation algorithm, in the context of method of moments (MoM), for planar microstrip structures. Three different interpolating functions are implemented, depending upon the distance between the locations of the basis and the testing functions. The accuracy and computation times for the direct MoM and the impedance matrix interpolation methods are compared for several planar microstrip structures. It is demonstrated that the use of the proposed impedance matrix interpolation scheme can result in significant savings in the computation time with little or no compromise in the accuracy of the solution. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 36: 439–447, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10785
Far‐field patterns of metal and dielectric‐wall conical horn antennas
Authors: Dube P. K. , Singh S. P.
Published: February 2003

The far‐field patterns and gain of dielectric‐wall conical horn antennas, each with axial length 149.5 cm, flare angle 20.2°, dielectric constant of horn dielectric 2.56, and varying thicknesses (0.33 cm and 0.65 cm), have been experimentally studied and compared with a metal horn antenna of identical flare angle and axial length at 9.4 GHz in X‐band. The use and applicability of dielectric‐wall conical horn antennas are discussed. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 36: 447–449, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10786
Broadband square annular planar monopoles
Authors: Chen Zhi Ning , Ammann M. J. , Chia M. Y. W.
Published: February 2003

This paper describes a vertical square planar monopole with a square concentric slot and a shifted feed location for broadband applications. The impedance and radiation characteristics of the proposed monopoles are experimentally studied, as a function of antenna dimensions and feed location. The proposed monopoles are shown to yield impedance bandwidth ratios of >1:1 for VSWR = 2:1, which fulfill most of the demands of EMC applications. Within the broad bandwidths, acceptable monopole‐like radiation patterns are also observed. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 36: 449–454, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10787
Multipole theory analysis of cylindrical strip and microstrip lines
Authors: Zheng Qinhong , Zeng Hua , Jiang Shaoquan , Li Manyi , Song Ming
Published: February 2003

A new approach, the multipole theory (MT) method, is presented for the computation of the quasi‐TEM parameters of cylindrical strip and microstrip lines. The inhomogeneous field domain of cylindrical strip and microstrip lines is treated as a combination of several simple homogeneous regions, and the solution of the boundary‐value problem is represented by the generalized MT formula. Representative computational examples, including single cylindrical stripline, coupled cylindrical stripline, and microstrip line, are presented to validate the theory and demonstrate the accuracy and flexibility of the MT method. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 36: 454–456, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10788
Effect of the chassis length on the bandwidth, SAR, and efficiency of internal mobile phone antennas
Authors: Kivekäs Outi , Ollikainen Jani , Lehtiniemi Tuukka , Vainikainen Pertti
Published: February 2003

The effect of the chassis length on the characteristics of the combination of an internal mobile phone antenna and a phone chassis were studied with simulations at 900 MHz and 1800 MHz. The results show that a local increase of SARs and a local decrease of radiation efficiency occur when the bandwidth reaches its maximum. This happens when the resonant frequency of the chassis equals that of the antenna. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 36: 457–462, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10789
Effects of CMOS process fill patterns on spiral inductors
Authors: Chen Chang‐Lee
Published: February 2003

Spiral inductors with various metal fill‐patterns under the spiral is fabricated with SOI CMOS technology and characterized up to 49 GHz. The impact of the fill on the inductor characteristics is found to be very small and changes can be attributed to the increase of parasitic capacitance. A simple model is proposed that can accurately estimate the increase of capacitance. A simple model is proposed that can accurately estimate the increase of capacitance by the fill. Design guidelines for optimizing fill patterns are recommended. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 36: 462–465, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10790
Electromagnetic interconnection between microstrip lines through a thick ground plate
Authors: Lee Byungje , Park Myun‐Joo
Published: February 2003

Understanding of electromagnetic coupling is an important area of research in the design and development of multi‐layered antenna arrays. In this paper, the spectral domain moment method (SDMM) is developed to investigate the coupling between two microstrip lines through a circular waveguide in a thick common‐ground plate. Measured data, along with the results obtained from the finite‐difference time‐domain (FDTD) method, are used to verify the solution. A parametric study illustrates the coupling behavior of the structure under investigation. It is observed that the frequency tuning and wide frequency bandwidth can be achieved by choosing the appropriate geometry, and this type of transition can be significantly affected by structural parameters. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 36: 467–471, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10792
A simplified hybrid calculation method for the surface fields and near fields of surface‐current patches
Authors: Zhang X. J. , Alphones Arokiaswami , Liu A. Q. , Leong Yoke Choy , Chio Tan Huat , Liang C. H.
Published: February 2003

This paper presents a simplified hybrid calculation method, which enables calculation of a field very close to the surface of a perfect conducting object as well as the surface field itself. This method is based on the series electric dipole modeling (SEDM) technique, used to quickly and efficiently calculate near fields of wire antennas or objects, and the Kemptner method, used to find the surface fields of patches. The present method combines advantages of both the SEDM and Kemptner method techniques, without their weak points. Several examples in this paper show the validity of the SEDM and the simplified hybrid calculation method. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 36: 471–474, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10793
Performance analysis of homowavelength crosstalk in optical packet networks
Authors: Zhang Min , Ye Peida , Zhang Fan , Zhao Yongpeng
Published: February 2003

In this paper, homowavelength crosstalk in optical packet networks is evaluated with the following aspects taken into consideration: device crosstalk coefficient, signal extinction ratio, traffic load, node size, and cascadability. Our results are very useful for the design of optical packet networks. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 36: 474–479, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10794
An alternative layout for CPW‐fed printed antennas with low back radiation
Authors: Montisci Giorgio , Mazzarella Giuseppe
Published: February 2003

In this paper, we analyze a patch fed by a hybrid system microstrip‐coplanar waveguide. The proposed feeding structure allows us to design an antenna with a significant reduction of the back‐radiation especially in the broadside direction. The analysis is made using the MPIE formulation of the method of moments (MoM). © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 36: 481–483, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10796
Nondestructive measurement of complex permittivity of sheet material
Authors: Verma A. K. , Nasimuddin
Published: February 2003

In this paper, we present a new model to determine the dielectric constant and the loss tangent of dielectric material in the sheet/slab form, with both low and high relative permittivity. A non‐destructive testing method is used, based on the microstrip patch and line resonators. This method provides consistently accurate results, as compared to the nominal value of data given by the manufactures. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 36: 483–486, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10797
A low‐cost surface‐mount monopole antenna for 2.4/5.2/5.8‐GHz band operation
Authors: Su Saou‐Wen , Fang Shyh‐Tirng , Wong Kin‐Lu
Published: February 2003

A low‐cost surface‐mount monopole antenna obtained by folding a metallic strip onto a low‐profile square‐disk foam base is presented. With a compact size of 10 × 10 × 2 mm3, the antenna can generate two separate wide resonant modes, with the lower mode covering the 2.4‐GHz WLAN band (2400–2484 MHz), and the upper mode covering both of the 5.2‐GHz HIPERLAN band (5150–5350 MHz) and the 5.8‐GHz ISM band (5725–5875 MHz). Good measured antenna gain for operating frequencies across the 2.4/5.2/5.8‐GHz bands is also obtained. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 36: 487–489, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10798
Design of the optical label eraser for DWDM network systems
Authors: Zhang Yejin , Zhu Lin , Gao Zhiguo , Chen Minghua , Xie Shizhong
Published: February 2003

In this paper, an all‐fiber birefringent filter was designed by using the Sagnac interferometer. The frequency spacing of the filter transfer function's two adjacent notches alternates between two different periods, which differs from the normal fiber loop mirror (FLM) and Lyot–Sagnac filters. A filter with over 40‐dB notch depth can be used as an optical label eraser in N × 20 Gb/s WDM all‐optical label swapping (AOLS) networks with 50‐GHz channel spacing. The results show that the filter is a high‐performance optical label eraser, and this work presents an approach for optical label erasing in high‐speed WDM AOS networks with narrow channel spacing. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 36: 489–491, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10799
Effects of finite‐sized groundplane on radiation pattern deformation, impedance bandwidth, and radiation efficiency of U‐PIFA
Authors: Salonen Pekka
Published: February 2003

Planar‐inverted F antennas (PIFAs) are widely used in portable devices, which are definitely size‐limited. Therefore, it is useful to study the effects of a finite‐sized ground plane on the antenna's various radiation and circuit parameters. In this paper, impedance bandwidth with criterion VSWR < 2 and radiation efficiency as a function of antenna position on a finite‐sized ground plane are studied for a dual‐band U‐shaped‐slot PIFA (U‐PIFA). Impedance bandwidth and radiation efficiency dependence along the ground plane are the main concerns. The results show that radiation efficiency and impedance bandwidth are strongly dependent on the antenna position on the groundplane. In addition, it is shown that the desired bandwidth can be controlled by proper location of the antenna. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 36: 491–496, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10800
BER performance comparison between an active Mach‐Zehnder modulator and passive Mach‐Zehnder interferometer for conversion of microwave subcarriers of BPSK signals
Authors: Le Guennec Y. , Maury G. , Cabon B.
Published: February 2003

The BER performances of a classical external optical Mach–Zehnder modulator and a passive all‐optical integrated device, an unbalanced Mach–Zehnder interferometer, are measured and analyzed theoretically. This analysis show better results for the passive all‐optical device than for the external modulator in the case of the laser diode's high enhancement factor. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 36: 496–498, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10801
Bandwidth enhancement of U‐slot patch antenna on high permittivity ceramic substrate for Bluetooth application
Authors: Tzou Wen‐Cheng , Chen Hua‐Ming , Chen Ying‐Chung , Yang Cheng‐Fu
Published: February 2003

A patch antenna on a very high‐permittivity ceramic substrate with a pair of U‐shaped slots is investigated experimentally at 2.45 GHz. The dielectric constant of the ceramic substrate is 43. By embedding a pair of U‐shaped slots close to the nonradiating edges of the patch, two adjacent resonant modes are very close to each other and are both covered. Thus, an enhanced impedance bandwidth of 5.3% can be achieved. The proposed antenna operates with 2:1 VSWR throughout the entire Bluetooth band (2400–2484 MHz). Details of the antenna design and experimental results are presented. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 36: 499–501, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10802
Reflection L‐band erbium‐doped fiber‐amplifier‐based on a fiber‐loop mirror
Authors: Meng Hongyun , Liu Yange , Gao Weiqing , Zhang Hao , Yuan Shuzhong , Dong Xiaoyi
Published: February 2003

A novel reflection L‐band erbium‐doped fiber amplifier, based on a fiber loop mirror, is constructed. This amplifier reflects the backward ASE to the EDF as a secondary pumping source. A gain of 30 dB (an increase of 6 dB) is obtained, compared to the forward‐end‐pumped EDFA in the range of 1570–1603 nm. The saturated output power was 7.63 dBm and 7.6 dBm for 1580 nm and 1600 nm signals, with increases of 2.98 dB and 3 dB, respectively, compared to the forward end‐pumped EDFA. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 36: 501–503, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10803
Germ cell transplantation in goats
Authors: Honaramooz Ali , Behboodi Esmail , Blash Stephen , Megee Susan O. , Dobrinski Ina
Published: February 2003

Transplantation of spermatogonial stem cells provides a unique approach for the study of spermatogenesis and manipulation of the male germ line. This technique may also offer an alternative to the currently inefficient methods of producing transgenic domestic animals. We have recently established the technique of spermatogonial transplantation, originally developed in laboratory rodents, in pigs, and this study was aimed to extend the technique to the goat. Isolated donor testis cells were infused into the seminiferous tubules of anesthetized recipient goats through an ultrasonographically‐guided catheter inserted into the rete testis. Donor cells were obtained by enzymatic digestion of freshly collected testes from immature goats (either from the recipients' contralateral testis or from unrelated donors). Prior to transplantation, testis cells were labeled with a fluorescent marker to allow identification after transplantation. Recipient testes were examined for the presence and localization of labeled donor cells at 3‐week intervals up to 12 weeks after transplantation. Labeled donor cells were found in the seminiferous tubules of all testes, comprising 10–35% of the examined tubules. Histological examination of the recipient testes did not reveal evident tissue damage, except for limited fibrotic changes at the site of needle insertion. Likewise there were no detectable local or systemic signs of immunologic reactions to the transplantations. These results indicate that germ cell transplantation is technically feasible in immature male goats and that donor‐derived cells are retained in the recipient testis for at least three months and through puberty. This study represents the first report of germ cell transplantation in goats. Mol. Reprod. Dev. 64: 422–428, 2003. © 2003 Wiley‐Liss, Inc.
Over‐expression and secretion of angiogenin in intrauterine growth retardation placenta
Authors: Rajashekhar G. , Loganath A. , Roy A.C. , Wong Y.C.
Published: February 2003

Human angiogenin is a potent inducer of neovascularization. There is a strong evidence to suggest that it might be involved in morphological and angiogenic changes in the placenta, that are necessary for a successful fetal outcome during pregnancy. However, its precise role in the pathogenesis of abnormal pregnancies is yet unknown. Intrauterine growth retardation (IUGR), an abnormal pregnancy is not a specific disease entity per se, but rather a manifestation of many possible fetal and maternal disorders. In this study, we demonstrated, for the first time, that placental explants in vitro secrete significantly elevated levels of angiogenin in placental tissues from patients with IUGR. We also observed enhanced mRNA expression in placenta from these patients. In addition, using the immunohistochemical methods, we observed identical staining of angiogenin to villous syncytiotrophobalst and fetal endothelial cells in both IUGR and normal placenta. Functionally active placental explants were used to detect immunoreactive angiogenin in conditioned media of all the samples from IUGR placenta and normal term group. The mean levels of angiogenin secreted by IUGR placenta were 1.4‐, 1.6‐, and 1.3‐fold higher (P < 0.01) than normal term samples at 24, 48, and 72 hr of culture, respectively. Expression profiles of angiogenin from term and IUGR cases are in agreement with its mRNA levels and immunoblot analysis. In conclusion, the significant elevated levels of angiogenin in IUGR placenta may provide a molecular mechanism for the abnormal placental development. Mol. Reprod. Dev. 64: 397–404, 2003. © 2003 Wiley‐Liss, Inc.
Meiosis in male PL/J mice: A genetic model for gametic aneuploidy
Authors: Pyle April , Handel Mary Ann
Published: February 2003

Sperm from mice of the PL/J strain have a high frequency of sperm‐head morphology abnormalities. Fluorescence in situ hybridization (FISH) methods revealed that PL/J sperm are also characterized by a high frequency of aneuploidy. The traits of abnormal sperm head morphology and aneuploidy are associated with numerous meiotic abnormalities. Spermatocytes of PL/J mice exhibit chromosome asynapsis during meiotic prophase as well as reduced crossing over, revealed by analysis of both MLH1 foci in pachytene spermatocytes and chiasmata seen at the first meiotic metaphase. During the first meiotic division, roughly one‐third of the PL/J spermatocytes exhibit aberrant spindle morphology, with abnormalities including monopolar spindles, split spindle poles, and incomplete spindle formation and centrosomal abnormalities. F1 progeny of a cross between PL/J and C57BL/6J did not exhibit a high frequency of either sperm aneuploidy or sperm head morphology aberrations, as would be expected if the PL/J traits were dominant. Among progeny of a backcross of F1 mice to PL/J, none of 16 males assessed exhibited elevated frequencies of sperm head morphology abnormalities. Four of the individuals exhibited elevated sperm aneuploidy, but not at the levels of the PL/J parents. Thus, it is likely that the aberrant PL/J traits are due to several genes and/or modifiers affecting the generation of both sperm aneuploidy and abnormal sperm head morphology. Mol. Reprod. Dev. 64: 471–481, 2003. © 2003 Wiley‐Liss, Inc.
Chromatin configuration and transcriptional control in human and mouse oocytes
Authors: Miyara Faïçal , Migne Carole , Dumont‐Hassan Martine , Meur Alain Le , Cohen‐Bacrie Paul , Aubriot François‐Xavier , Glissant Amélie , Nathan Catherine , Douard Stéphane , Stanovici Alexandre , Debey Pascale
Published: February 2003

In vitro maturation of human oocytes at the germinal vesicle (GV) stage could offer an alternative in several cases of female infertility. It however rests on a better knowledge of the quality of human oocyte. Using fluorescence imaging of DNA and of the transcription sites, combined with electron microscopy, we show that human oocytes follow size‐dependent changes in chromatin configuration, transcription sites distribution and nuclear ultrastructure that follow those observed in mouse GV oocytes. We thus analyzed in mouse GV oocytes the phosphorylation dependence of the transcriptional activity. We show by Western blot that, while active GV oocytes have approximately the same proportion of hypo‐ and hyperphosphorylated forms of the RNA polymerase II (RNAP II), the hyperphosphorylated form is almost absent from inactive oocytes. We also show that (1) RNAP II‐dependent transcription is much less sensitive to various kinase inhibitors in mouse oocytes than in somatic cells or mouse one‐cell embryos, although the phosphorylation equilibrium of RNAP II was largely shifted towards the hypo‐phosphorylated form upon treatment with these inhibitors (2) RNAP I is completely insensitive to kinase inhibitors in GV oocytes. Mol. Reprod. Dev. 64: 458–470, 2003. © 2003 Wiley‐Liss, Inc.
ADAM7 (a disintegrin and metalloprotease 7) mRNA is suppressed in mouse epididymis by neonatal exposure to Diethylstilbestrol
Authors: Adachi Tetsuya , Matsuno Yoshiharu , Sugimura Atsushi , Takano Kaiya , Koh Kyu‐Bom , Sakurai Kenichi , Shibayama Takako , Iguchi Taisen , Mori Chisato , Komiyama Masatoshi
Published: February 2003

We investigated whether neonatal exposure to diethylstilbestrol (DES) induces the alteration of mRNA expression in adult mouse epididymis, which plays an important role in sperm maturation. Using a cDNA subtraction method, we isolated 15 changed gene clones in neonatally DES‐treated mouse epididymides, and we found a clone homologous with a disintegrin and metalloprotease (ADAM) 7 in the epididymis, as a suppressed gene, by means of neonatal DES treatment in 8‐week‐old mice. Indeed, it was confirmed by Northern blot analysis that the ADAM7 mRNA expression in the epididymis was at a lower level in neonatally DES‐treated mice than in non‐treated mice. Moreover, in situ hybridization analysis and real‐time reverse transcription and polymerase chain reaction (real‐time RT‐PCR) revealed that ADAM7 expression was markedly reduced in the corpus region of the epididymis of DES‐treated mice as compared with non‐treated mice. Our results suggest that neonatal exposure to DES leads to the suppression of ADAM7 expression in the epididymis in the long term. ADAM7 gene expression might be a biological marker of fetal or neonatal exposure to estrogenic compounds, including endocrine disruptors. Mol. Reprod. Dev. 64: 414–421, 2003. © 2003 Wiley‐Liss, Inc.
Increased recombination frequency showing evidence of loss of interference is associated with abnormal testicular histopathology
Authors: Varmuza Susannah , Ling Ling
Published: February 2003

Nondisjunction leading to aneuploid gametes has been linked genetically to both increases and decreases in recombination frequency on the aneuploid chromosome. In the present study, we present physical evidence of increased frequency of recombination nodules as measured by Mut‐S‐like homologue‐1 (MLH1) foci on pachytene chromosomes from sterile male mice homozygous for a mutation in the protein phosphatase 1cγ (PP1cγ) gene. The pattern of elevated recombination frequency in PP1cγ mutant spermatocytes is consistent with a loss of interference. Previous studies demonstrated: (1) spermiogenesis is impaired starting at step 8 with a severe reduction in elongating and condensed spermatids; (2) spermatids and sperm exhibit elevated rates of DNA fragmentation; and (3) haploid gametes exhibit elevated levels of aneuploidy. Morphometric analysis of developing testes revealed that the first wave of meiosis proceeds at a normal rate in mutant testes, a surprising result given that the PP1 inhibitor okadaic acid has been shown to accelerate progression of spermatocytes from pachytene to the first meiotic division (MI). Evidence of abnormal testicular histopathology is apparent at 3 weeks, before the appearance of haploid gametes, eliminating the possibility that the mutant phenotype is caused by the presence of abnormal spermatids, but coincident with the appearance of the first set of mid to late pachytene spermatocytes. These observations lead us to conclude that the PP1cγ mutation causes a complex phenotype, including subtle adverse effects on meiosis, possibly mediated by defective signaling between germ cells and Sertoli cells. Mol. Reprod. Dev. 64: 499–506, 2003. © 2003 Wiley‐Liss, Inc.
Glutathione and adenosine triphosphate content of in vivo and in vitro matured porcine oocytes
Authors: Brad A.M. , Bormann C.L. , Swain J.E. , Durkin R.E. , Johnson A.E. , Clifford A.L. , Krisher R.L.
Published: February 2003

Glutathione (GSH) content in mature porcine oocytes is correlated with subsequent fertilization and developmental success. Adenosine triphosphate (ATP) is an important energy source for maintaining cellular activities and protein synthesis. The objective of this study was to compare GSH and ATP concentrations of in vivo and in vitro matured porcine oocytes. Ovulated, in vivo matured oocytes were frozen at −80°C in groups of 10–20 (GSH) or 5–10 (ATP). In vitro oocytes were matured in either tissue culture medium‐199 (TCM199) supplemented with polyvinyl alcohol (PVA) or hyaluronic acid (MAP5), or North Carolina State University‐23 (NCSU23) supplemented with porcine follicular fluid (pFF) and frozen as described, or fertilized and cultured. GSH content was determined by the dithionitrobenzoic acid–glutathione disulfide (DTNB–GSSG) reductase recycling assay. ATP content was determined by using the Bioluminescent Somatic Cell Assay Kit. Oocytes matured in vitro in defined TCM199 with PVA or hyaluronic acid, or NCSU23 with pFF had significantly lower concentrations (P < 0.05) of GSH (n = 207, 9.82 ± 0.71 pmol/oocyte; n = 104, 9.73 ±  0.81 pmol/oocyte; n = 108, 7.89 ± 0.66 pmol/oocyte, respectively) compared to in vivo matured oocytes (n = 217, 36.26 ± 11.00 pmol/oocyte). Concentrations of ATP were not different between treatments (in vivo, n = 70, 0.97 ± 0.07 pmol/oocyte; TCM–PVA, n = 117, 0.81 ± 0.13 pmol/oocyte; TCM–MAP, n = 107, 1.02 ± 0.18 pmol/oocyte; NCSU–pFF, n = 134, 0.71 ± 0.08 pmol/oocyte). Intracellular ATP content does not appear to be related to developmental potential in porcine oocytes. Low intracellular GSH may be responsible, in part, for lower developmental competence observed in in vitro matured porcine oocytes. Mol. Reprod. Dev. 64: 492–498, 2003. © 2003 Wiley‐Liss, Inc.
Stage‐specific regulatory element of mouse Sry gene
Authors: Yokouchi Kou , Ito Masanori , Nishino Koichiro , Yamanouchi Keitaro , Naito Kunihiko , Suzawa Miyuki , Kato Shigeaki , Hakamata Yoji , Endo Hitoshi , Tojo Hideaki
Published: February 2003

Sry expression is essential for initiating male sex differentiation, and the expression occurs only during a restricted period in the developing gonad. It is thought that Sry is part of a pathway of genes that regulate sex determination. Although the interactions of several genes with Sry expression have been suggested, the exact cascade of gene expression regulating Sry transcription is entirely obscure because there is no available cell line expressing Sry and reflecting an in vivo condition. The present study was carried out to investigate the cis‐acting element of the mouse Sry that responds stage specifically to its expression, in part, using transgenic mice expressing GFP on the Y chromosome. Ten DNA fragments were generated by digesting the 5′ upstream region (positions 5491–8039; 2,549 bp) of mouse Sry with appropriate restriction enzymes. In an electrophoretic mobility assay with these fragments, the region from position 5491 to position 5799 (309 bp) was identified as forming specific protein–DNA complexes with nuclear extracts from 11.5 days post coitus (dpc) gonads, but not from 12.5 and 13.5‐dpc gonads. This region also formed specific protein–DNA complexes with the nuclear extracts from adult testicular germ cells that generate only a circular form from Sry. This stage‐specific responsive region was narrowed down to positions 5559–5616 by DNase I footprinting analysis. The assay of DNase I hypersensitive (HS) using the nuclear lysates from the 11.5‐dpc urogenital ridges demonstrated that the novel HS site was located in the proximity of position 5600. This region DNase I HS was also detected at the same position when the lysates from adult testicular germ cells were applied. The results indicate that the present HS site may be involved in the transcriptional regulation of the linear and/or circular molecule transcripts from mouse Sry gene. Mol. Reprod. Dev. 64: 389–396, 2003. © 2003 Wiley‐Liss, Inc.
Proliferation of donor mitochondrial DNA in nuclear transfer calves (Bos taurus) derived from cumulus cells
Authors: Takeda Kumiko , Akagi Satoshi , Kaneyama Kanako , Kojima Toshiyuki , Takahashi Seiya , Imai Hiroshi , Yamanaka Mariko , Onishi Akira , Hanada Hirofumi
Published: February 2003

In embryos derived by nuclear‐transfer (NT), fusion of donor cell and recipient oocyte caused mitochondrial heteroplasmy. Previous studies from other laboratories have reported either elimination or maintenance of donor‐derived mitochondrial DNA (mtDNA) from somatic cells in cloned animals. Here we examined the distribution of donor mtDNA in NT embryos and calves derived from somatic cells. Donor mitochondria were clearly observed by fluorescence labeling in the cytoplasm of NT embryos immediately after fusion; however, fluorescence diminished to undetectable levels at 24 hr after nuclear transfer. By PCR‐mediated single‐strand conformation polymorphism (PCR–SSCP) analysis, donor mtDNAs were not detected in the NT embryos immediately after fusion (less than 3–4%). In contrast, three of nine NT calves exhibited heteroplasmy with donor cell mtDNA populations ranging from 6 to 40%. These results provide the first evidence of a significant replicative advantage of donor mtDNAs to recipient mtDNAs during the course of embryogenesis in NT calves from somatic cells. Mol. Reprod. Dev. 64: 429–437, 2003. © 2003 Wiley‐Liss, Inc.
Maternal gamma (γ)‐tubulin is involved in microtubule reorganization during bovine fertilization and parthenogenesis
Authors: Shin Mi‐Ra , Kim Nam‐Hyung
Published: February 2003

In this study, γ‐tubulin distribution was determined chronologically in conjunction with microtubule dynamics during bovine fertilization and parthenogenesis. In unfertilized bovine oocytes, γ‐tubulin was identified in the cytoplasm, mainly in the cortex and concentrated in the meiotic spindle. Following sperm penetration, γ‐tubulin in the cytoplasm was recruited by a sperm component. During pronuclear apposition, γ‐tubulin was localized as spots at the spindle poles. γ‐tubulin spots were observed in blastomeres of embryos cleaved in vitro. Following electrical stimulation, γ‐tubulin and microtubule matrix were noted in oocyte cortex. In the late pronuclear stage, considerably less γ‐tubulin and microtubules were detected in the cytoplasm. At the mitotic metaphase of parthenotes, γ‐tubulin was recruited to the condensed chromatin and concentrated in the spindle. The γ‐tubulin spots were not detected until the 8‐cell stage of parthenotes. This suggests that maternal γ‐tubulin is recruited by a sperm component to reconstitute the zygotic centrosome. In the absence of sperm components, the cell cycle‐related assembly of γ‐tubulin organizes microtubule nucleation for positioning the pronucleus and spindle protein of mitotic metaphase during the first cell cycle of bovine parthenotes. Mol. Reprod. Dev. 64: 438–445, 2003. © 2003 Wiley‐Liss, Inc.
Partial pressure dependency of 17O/16O and 18O/16O of molecular oxygen in the mass spectrometer
Authors: Abe Osamu , Yoshida Naohiro
Published: February 2003

A method to determine both 17O/16O and 18O/16O ratios for molecular oxygen with high precision by direct introduction into the mass spectrometer without gas separation is presented. Because both 17O/16O and 18O/16O in mixed gases have good linear correlations with their mixing ratios, these isotopic compositions can be determined without a gas‐separation procedure by calibration using prepared standard gases with variable mixed ratios and by monitoring the amounts of fragment ions. Analytical precision for δ17O and δ18O of 45 and 7 per meg, respectively, were obtained. The observed partial pressure dependency of isotopic composition may be caused by isotope fractionation during admission from the ionization chamber into the flight tube of the mass spectrometer. Copyright © 2003 John Wiley & Sons, Ltd.
High affinity capture surface for matrix‐assisted laser desorption/ionisation compatible protein microarrays
Authors: Koopmann Jens‐Oliver , Blackburn Jonathan
Published: February 2003

A surface for the capture of biotin‐tagged proteins on matrix‐assisted laser desorption/ionisation (MALDI) targets has been investigated. Binding of a poly‐L‐lysine poly(ethylene glycol)‐biotin polymer to glass and gold surfaces has been demonstrated using dual wavelength interferometry. Biotinylated proteins were captured onto this surface using tetrameric neutravidin as a multivalent bridging molecule. Biotin tagging of proteins was achieved by chemical biotinylation or by expressing a protein with a biotinylation consensus sequence in E. coli. The specificity of the surface for biotin‐tagged proteins allowed the purification of biotin‐tagged glutathione‐S‐transferase from a bacterial lysate directly onto a MALDI target. Subsequently, the protein was digested on the MALDI target and a protein fingerprint analysis confirmed its presence directly, but no E. coli proteins were detected. Therefore, we conclude that this surface is highly specific for the capture of biotin‐labelled proteins and has low non‐specific binding properties for non‐biotinylated proteins. Furthermore, protein–protein interactions using biotinylated lectins were investigated, and the selective capture of the glycoprotein fetuin with wheat germ agglutinin was demonstrated. Also, immobilised Arachis hypogea agglutinin recognised a minor asialo component of this glycoprotein on the array. The high affinity immobilisation of proteins onto this surface allowed effective desalting procedures to be used which improved the desorption of high molecular weight proteins. Another aspect of this surface is that a highly ordered coupling of the analyte can be achieved which eliminates the search for the sweet spot and allows the creation of densely packed protein microarrays for use in mass spectrometry. Copyright © 2003 John Wiley & Sons, Ltd.
Mass spectrometric investigation of N‐sulfonylated purine nucleic bases and nucleosides
Authors: Srzić Dunja , Rožman Marko , Krizmanić Irena , Žinić Biserka
Published: February 2003

The gas/phase behaviour of N‐sulfonylated purine nucleic bases and nucleosides towards electron impact (EI) and matrix‐assisted laser desorption/ionization (MALDI) occurring in a ion trap of a Fourier transform ion cyclotron resonance mass spectrometer is investigated. The influence of the storage time on the protonated molecule ([M+H]+) abundance under EI conditions confirms that the formation of these ions proceeds through ion/molecule reactions. Using stored‐waveform inverse Fourier transform (SWIFT) selective isolation of M+. or H3O+, self‐chemical ionization, M+./M, and chemical ionization, H3O+/M, are detected. Investigation of specific EI expulsion of SO2, SO2H and/or SO2H2 from M+. and/or [M+H]+ shows that oxygen protonation in SO2 proceeds faster than nitrogen protonation. Expulsion of SO2 from molecular ions is not observed in MALDI mass spectra of nucleosides. Copyright © 2003 John Wiley & Sons, Ltd.
Use of S‐pentafluorophenyl tris(2,4,6‐trimethoxyphenyl)phosphonium acetate bromide and (4‐hydrazino‐4‐oxobutyl) [tris(2,4,6‐trimethoxyphenyl)phosphonium bromide for the derivatization of alcohols, aldehydes and ketones for detection by liquid chromatography/electrospray mass spectrometry
Authors: Barry Samantha J. , Carr Richard M. , Lane Stephen J. , Leavens William J. , Manning Calvin O. , Monté Soraya , Waterhouse Ian
Published: February 2003

The synthesis of S‐pentafluorophenyl tris(2,4,6‐trimethoxyphenyl)phosphonium acetate bromide (TMPP‐AcPFP) and the novel compound (4‐hydrazino‐4‐oxobutyl) [tris(2,4,6‐trimethoxyphenyl)phosphonium bromide (TMPP‐PrG) is described and the use of these compounds as derivatizing reagents for alcohols, aldehydes and ketones evaluated. Methods have been developed for the pre‐column derivatization of alcohols using TMPP‐AcPFP and for aldehydes and ketones using TMPP‐PrG. The reactions were investigated by the use of a variety of individual test compounds containing the target functional groups. The TMPP acetyl ester and TMPP propyl hydrazone derivatives formed with their respective target analytes produced an enhanced response in electrospray ionization mass spectrometry (ESI‐MS), and reproducible chromatography. The use of these two reagents to derivatize and facilitate detection of alcohols (including sugars and steroids), aldehydes and ketones (including steroids) by LC/ESI‐MS was investigated. Copyright © 2003 John Wiley & Sons, Ltd.
Individual variability in Tityus serrulatus (Scorpiones, Buthidae) venom elicited by matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry
Authors: Pimenta Adriano M. C. , Almeida Flavia De Marco , de Lima Maria Elena , Martin‐Eauclaire Marie France , Bougis Pierre E.
Published: February 2003

Venom variability in specimens of Tityus serrulatus scorpion was assessed by matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOFMS) analyses. An expanded time lag venom extraction protocol was carried out using ten scorpions to study individual variations that might occur due to different rates in protein expression and/or processing. The first extraction of venom was made from the animals after 20 days of starvation, which allowed the venom gland to be filled up. The second extraction event was carried out 24 hours after the first one. The third was 8 days after the first extraction. By means of MALDI‐TOF analyses, important variations were observed in venoms of a single specimen extracted at different times, especially in latter extraction events. These variations are most probably related to dynamics in cell gland production. Since T. serrulatus is a parthenogenetic species, sexual variations are naturally excluded and we did not expect intra‐specific variations, which was confirmed. Knowledge of individual venom variability is extremely important to avoid misunderstandings in the use of venom proteomic analysis as a taxonomic tool. Copyright © 2003 John Wiley & Sons, Ltd.
A novel nanoflow interface for atmospheric pressure ionization mass spectrometry
Authors: Hirabayashi Atsumu
Published: February 2003

A novel spray‐ionization technique for nanoflow liquid chromatography/mass spectrometry (nLC/MS) has been developed by modifying the sonic spray ionization (SSI) technique. A solution from a tapered fused‐silica capillary is sprayed by a gas flow coaxial to the capillary, and ions produced are analyzed with an ion‐trap mass spectrometer. The ion intensity is shown to have a steep threshold at a low gas velocity and to be much less dependent on the gas velocity than that of conventional SSI, in which the ion intensity is strongly dependent on the gas velocity and reaches its maximum at sonic velocity. Thus, we conclude that the concentration of charge in the solution at the tapered capillary tip with an inner diameter of 15 μm is almost at saturation so that charged droplets are produced from the solution by electrical force, rather than by sheer stress due to the gas flow. The ions are readily produced from these charged droplets. Preliminary results are compared with results obtained with a miniaturized electrospray unit. Copyright © 2003 John Wiley & Sons, Ltd.
Determination of perfluorooctane sulfonate in river water by liquid chromatography/atmospheric pressure photoionization mass spectrometry by automated on‐line extraction using turbulent flow chromatography
Authors: Takino Masahiko , Daishima Shigeki , Nakahara Taketoshi
Published: February 2003

A simple, fast and sensitive liquid chromatography/atmospheric pressure photoionization mass spectrometry (LC/APPI‐MS) method, with automated on‐line extraction using turbulent flow chromatography (TFC), was developed for the determination of perfluorooctane sulfonate (PFOS) in river water. In this method, following an on‐line extraction by injection onto a column under TFC conditions, PFOS is back‐flushed onto a reversed‐phase column via on‐line column switching, and resolved chromatographically at a laminar flow rate of 1 mL min−1. Using this tandem LC‐LC/APPI‐MS system the extraction, separation and selective detection of PFOS in river water could be achieved with satisfactory selectivity and sensitivity. The limit of detection (LOD) (S/N = 3) and the limit of quantitation (LOQ) (S/N = 10)were 5.35 and 17.86 pg mL−1. The described procedure was very simple since no off‐line sample preparation was required, total analysis time being 18.75 min. Copyright © 2003 John Wiley & Sons, Ltd.
A simple method for fabrication of silver‐coated sheathless electrospray emitters
Authors: Chen Yet‐Ran , Her Guor‐Rong
Published: February 2003

A simple and time‐saving procedure is proposed for preparing a silver‐coated fused‐silica capillary tip. The tapered capillary tip was coated with silver using an acrylic‐based silver conductive pen. The fabrication of a silver‐coated fused‐silica capillary tip takes less than 5 minutes. The silver‐coated fused‐silica capillary tip is rugged and durable for sheathless capillary electrophoresis/electrospray mass spectrometry and also for microspray applications. Copyright © 2003 John Wiley & Sons, Ltd.