bluuebunny/crossref_metadata_2025 huggingface dataset:
Follistatin overexpression in rodent liver tumors: A possible mechanism to overcome activin growth control
Authors: Rossmanith Walter , Chabicovsky Monika , Grasl‐Kraupp Bettina , Peter Barbara , Schausberger Elisabeth , Schulte‐Hermann Rolf
Published: September 2002

The activin‐follistatin system is a potent growth regulatory system of liver tissue homeostasis. Activin A inhibits hepatocellular DNA synthesis and induces cell death. Follistatin binds activin and sequesters it from the signaling pathway. Consistently, follistatin has been reported to act as an inducer of DNA synthesis in the liver. Using RNase protection analysis, we studied the expression of follistatin in rat and mouse liver tumors as a possible mechanism to overcome activin growth control. Approximately 40% of the tumors (nine of 24 each), most of them hepatocellular carcinomas, displayed increased levels of follistatin mRNA when compared to tumor‐surrounding liver tissue. The degree of overexpression was highly variable but independent of the carcinogen treatment that animals had received. It was also independent from the histological stage of malignancy and further found in rat liver adenomas. Follistatin expression was also observed in cell lines derived from human hepatocellular carcinomas. Overexpression of follistatin may represent a unique strategy of hepatic tumors to overcome the inhibitory action of a growth factor, activin, by decreasing its local bioavailability. © 2002 Wiley‐Liss, Inc.
CCND1‐ and ERBB2‐gene deregulation and PTEN mutation analyses in invasive lobular carcinoma of the breast
Authors: Mercapide Javier , Zhang Shi Yu , Fan Xing , Furió‐Bacete Vicente , Schneider José , Osa Íñigo López de la , Patchefsky Arthur S. , Klein‐Szanto Andrés J. P. , Castresana Javier S.
Published: September 2002

Because of the relatively low incidence of lobular breast carcinoma, there are very few studies on the molecular characteristics of this breast cancer. In an attempt to improve its characterization, we investigated in a large collection of invasive lobular carcinomas (ILCs) the status of markers known to be involved in the better‐studied invasive ductal carcinomas (IDC). In the current study we disposed of 80 well‐characterized ILC cases. Gene amplification of cyclin D1 (CCND1) and c‐erbB2‐encoding gene (ERBB2) and expression of their gene products were studied by differential polymerase chain reaction (PCR) and immunohistochemistry, respectively. A comprehensive point mutation study of the phosphatase and tensin homolog tumor suppressor gene (PTEN) was pursued by single strand conformation polymorphism (SSCP)/sequencing analysis. The CCND1 gene was rarely amplified in ILC in spite of showing overexpression of the protein in 41% of tumors. Hence, unlike IDC, increase in gene dosage did not account for the protein excess. PTEN mutations were detected in ILC (truncating mutations) in around 2% of the tumors. Unlike IDC, ILC did not display ERBB2 overexpression and expression of the transcription factor E2F1 correlated inversely with tumor grade. The observed discrepancy in the pattern of the human oncogenes CCND1 and ERBB2, which are involved in the process of carcinogenesis of ductal tumors, appears to suggest a different molecular basis for development and progression of ILC. © 2002 Wiley‐Liss, Inc.
Evidence of increased Id‐1 expression and its role in cell proliferation in nasopharyngeal carcinoma cells
Authors: Wang Xianghong , Xu Kexin , Ling Ming Tat , Wong Y. C. , Feng Hui Chen , Nicholls John , Tsao S. W.
Published: September 2002

Inhibitor of differentiation or DNA binding (Id‐1), a helix‐loop‐helix transcription factor, has recently been shown to inactivate the retinoblastoma (RB)/p16INK4a pathway through down‐regulation of p16INK4a and increasing phosphorylation of RB in certain cell types. Nasopharyngeal carcinoma (NPC) is a common cancer in Hong Kong, and inactivation of the tumor suppressor RB at transcription level is a rare event in NPC. The objective of this study was to investigate the role of Id‐1 in NPC cell proliferation and its expression in NPC samples. An NPC cell line, CNE1, was transfected with a retroviral vector containing a full‐length Id‐1 cDNA, and six stable transfectant clones were isolated with differential Id‐1 expression levels. The effect of ectopic Id‐1 expression on serum‐independent cell growth, cell‐cycle distribution, and expression of proteins associated with RB pathway was studied. The Id‐1 expression in five NPC samples was also investigated using immunohistochemistry. Ectopic Id‐1 expression in CNE1 cells resulted in an increase in serum‐independent cell growth, percentage of cells in S phase, and phosphorylation of RB and cyclin‐dependent kinase 2 proteins. In addition, immunohistochemical studies on NPC samples showed that expression of Id‐1 was present in NPC cells but absent in normal tissues. This study demonstrates that Id‐1 plays an important role in cell proliferation in NPC cells, and our results provide evidence for the first time of the significance of Id‐1 expression in NPC cells and suggest a possible role of Id‐1 expression in the inactivation of RB and development of NPC. © 2002 Wiley‐Liss, Inc.
Time‐to‐market, window of opportunity, and salvageability of a new product development
Authors: Messica A. , Mehrez A.
Published: September 2002

The time‐to‐market in the presence of a window of opportunity is analyzed using ;a probabilistic model, i.e. a model where the completion time of new product development is a random variable characterized by a gamma distribution. Two cases are considered: the first, a case where the discounted return‐on‐investment exceeds the return expected from a conservative investment—e.g. investment in bonds—termed ‘the profitable case’; and the second, a case where the discounted return‐on‐investment just balances the cost of new product development, termed ‘the salvageable case’. The model constructed is focused on the financial aspects of new product development. It allows a decision‐maker to monitor, as well as terminate, a project based on its expected value (at any time prior to completion) by computing the mean time‐to‐market that provides profit, investment salvage, or loss. The mean time‐to‐market computed by the model may be compared with that estimated by the technology development team for decision‐making purposes. Finally, in the presence of a window of opportunity and for the specific cases analyzed, we recommend to always keep the expenditure rate lower than the expected return rate. This will provide the decision‐maker a salvageable exit opportunity if project termination is decided. Copyright © 2002 John Wiley & Sons, Ltd.
Vorticity–velocity–pressure formulation for the Stokes problem
Authors: Dubois François
Published: September 2002

We present a new variational formulation of Stokes problem of fluid mechanics that allows to take into account very general boundary conditions for velocity, tangential vorticity or pressure. This formulation conducts a well posed mathematical problem in a family of particular cases. Copyright © 2002 John Wiley & Sons, Ltd.
Some existence results for conservation laws with source‐term
Authors: Dias João‐Paulo , LeFloch Philippe G.
Published: September 2002

We prove some new results concerning the existence and asymptotic behaviour of entropy solutions of hyperbolic conservation laws containing non‐smooth source‐terms. Copyright © 2002 John Wiley & Sons, Ltd.
Negative index of refraction and distributed Bragg reflectors
Authors: Gerardin Jaline , Lakhtakia Akhlesh
Published: September 2002

The Bragg regime shifts when conventional materials in a multilayer distributed Bragg reflector (DBR) are replaced by artificial materials with the so‐called negative index of refraction. This provides an avenue for characterizing the latter class of materials. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 34: 409–411, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10478
Convergence studies of plane‐wave spectral expansion technique for analyzing truncated frequency‐selective surfaces
Authors: Prakash V. V. S. , Mittra Raj
Published: September 2002

In this Letter, the problem of scattering from truncated frequency‐selective surfaces (FSSs) has been analyzed by using the plane‐wave spectral (PWS) expansion technique. The scattered electric and magnetic fields from the structure are computed for each spectral component, and are then superimposed to obtain the total fields. The convergence of various electrical characteristics has been studied as a function of the number of terms used in the expansion. Numerical results are presented to illustrate the accuracy of the technique by comparing them with those derived by using the rigorous moment‐method analysis. In addition, the computational advantages of the PWS method, in terms of CPU time and memory requirements, are pointed out. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 34: 417–421, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10481
GaAs MESFET rf I‐V curve through unique determination of small‐signal circuit parameters from measured S parameters
Authors: Meng C. C. , Huang G. H.
Published: September 2002

A method to uniquely determine each small signal circuit element from measured S parameters is used to obtain the rf I‐V curve for uniform‐doped MESFETs. No dc measurement is needed in this method. The resulting rf I‐V curve differs from the static dc I‐V curve and is useful to predict rf performance. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 34: 426–427, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10483
FDTD modeling and validation of EM survey tools
Authors: Johnson David , Furse Cynthia , Tripp Alan C.
Published: September 2002

Accurate finite‐difference–time‐domain (FDTD) modeling of loop‐type sources using a modified source term is described and validated by comparison with an analytical solution in a resistive whole space. This demonstrates that the FDTD method provides good accuracy a few cells beyond the source but is slightly inaccurate very near the source. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 34: 427–429, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10484
Dual‐feeding active integrated antenna for dual‐resonant structure
Authors: Lee Byoung Moo , Kim Hyungrak , Kwon Sewoong , Yoon Youngjoong
Published: September 2002

The proposed dual‐feeding active integrated antenna suppresses the third harmonics and isolates the Tx signal at the Rx ports to a high degree. The characteristics of the measured results are provided and the transmitted output power of the 2 × 2 array for the spatial power combining effect is calculated. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 34: 435–437, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10487
Simulation of multiple composite coatings based on conducting plate and investigation of microwave reflectivity
Authors: Cao Maosheng , Zhu Jing , Yuan Jie , Peng Zhihui , Xiao Gang
Published: September 2002

A simulation of radar absorbing materials (RAM) with multiple composite coatings is given, including theory, methodology, and techniques. To illustrate the theory and method of multiple composite coatings, the basic tracking calculation method and pure‐shape optimum are also introduced. In addition, the simulation process and examples with multiple coatings are described. Experimental results show that the simulation is effective, and the multiple coatings provide considerable microwave absorption. The multiple coatings used are types of broadband coatings. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 34: 442–445, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10489
A novel electromagnetic band‐gap (EBG) structure with one cell with the use of properties of a microstrip open‐loop resonator
Authors: Görür Adnan
Published: September 2002

A novel EBG structure is proposed for a tunable and wide stop band (band gap). Although the proposed EBG, which consists of two microstrip open‐loop resonators located back to back, has only one unit cell inserted into the microstrip; it produces the characteristics of the general EBG structure, that is, slow wave and wide band gap. Simulations and measurements have shown that the stop‐band center frequency and the bandwidth of stop band depend on the widths of strips of the proposed EBG. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 34: 454–459, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10493
Dual‐port dual‐polarized microstrip antenna
Authors: Kundukulam Sona O. , Paulson Manju , Aanandan C. K. , Mohanan P.
Published: September 2002

Experimental and simulated results for a dual‐port dual‐polarized microstrip antenna are presented. The antenna excites two orthogonally polarized resonant frequencies providing an isolation of ∼30 dB between the ports. The patch geometry consists of two circular arcs of different radii with their centers displaced by a distance. This new design offers an area reduction of ∼70% compared to a standard rectangular microstrip antenna with a reduction in gain of 1.7 dB. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 34: 459–460, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10494
Tunnel‐based artificial neural network technique to calculate the resonant frequency of a thick‐substrate microstrip antenna
Authors: Pattnaik Shyam S. , Panda Dhruba C. , Devi S.
Published: September 2002

The mathematical formulation of empirically developed formulas for the calculation of the resonant frequency of a thick‐substrate (h ≥ 0.08151λ0) microstrip antenna has been analyzed. With the use of tunnel‐based artificial neural networks (ANNs), the resonant frequency of antennas with h satisfying the thick‐substrate condition are calculated and compared with the existing experimental results and also with the simulation results obtained with the use of an IE3D software package. The artificial neural network results are in very good agreement with the experimental results. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 34: 460–462, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10495
Autotuning technique to reach resonance for determining the properties of Ni‐Zn and Mn‐Zn ferrite used in RF inductors for EMI suppression
Authors: Zhang Daming , Li Erping , Foo CF
Published: September 2002

A resonant method with autotuning technique to measure the losses is presented. The properties of Ni‐Zn and Mn‐Zn ferrite used in RF inductors can be determined. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 34: 466–469, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10497
Design and fabrication of a planar inverted‐F antenna for the wireless LAN in the 5‐GHz band
Authors: Kim Yongjin , Lee Sangseol
Published: September 2002

A compact, lightweight, and low‐cost planar inverted‐F antenna (PIFA) for wireless LAN communication in the 5‐GHz band is designed. The antenna is designed with the use of the IE3D, a simulation tool by Zeland, Inc. The rectangular planar element of the standard type PIFA is modified as a L‐shape element to increase the spatial efficiency. The characteristics of the implemented antenna are measured and analyzed. The antenna is resonated at 5.25 GHz, and its bandwidth is about 580 MHz under the condition of VSWR ≤ 1.5. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 34: 469–475, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10498
Application of a novel CFIE for electromagnetic scattering by dielectric objects
Authors: Ylä‐Oijala Pasi
Published: September 2002

In this Letter a new type of combined field integral equation (CFIE) is proposed and applied for electromagnetic scattering by three‐dimensional dielectric objects of arbitrary shape. In this formulation, traditional CFIE is applied outside the object, and inside the object the electric and magnetic field integral equations are combined by changing their roles. This formulation gives a more stable solution than the traditional CFIE when the method of moments with Galerkin's type testing and RWG functions is applied. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 35: 3–5, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10500
An efficient technique for analyzing multiple frequency‐selective‐surface screens with dissimilar periods
Authors: Prakash V. V. S. , Mittra Raj
Published: September 2002

This Letter presents an efficient technique for analyzing multiple frequency‐selective surfaces (FSSs) with noncommensurate periodicities based on the discrete plane‐wave spectrum (DPWS) expansion method. In this method, the tangential electric fields at the interfaces of the screens are first expanded in a set of transverse electric and transverse magnetic waves, and the responses of the individual FSS screens are derived for each of these waves. The transmission and reflection characteristics of the composite structure are then computed in an iterative manner, circumventing the need for matrix inversions, which can be extremely expensive in terms of CPU time and memory for noncommensurate FSSs. Representative numerical examples are presented to illustrate the computational advantage gained by using the proposed approach as opposed to the conventional generalized scattering matrix technique. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 35: 23–27, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10506
Numerical method for dispersion calculation and effect of index imperfection on dispersion in single‐mode fibers
Authors: Meher H. , Hosain S. I.
Published: September 2002

A simple numerical method has been proposed to compute dispersion for single‐mode graded‐index fibers with power law profile. The results so obtained are in excellent agreement with those obtained by more complicated methods proposed earlier. It has been shown that there two core radii exist at which dispersion becomes zero. With this method the effect of on‐axis dip on these two zero‐dispersion core radii have been investigated. A recently proposed single‐parameter variational approximation for the LP01 mode has also been utilized to study these effects. The results obtained by the variational method are in excellent agreement with those obtained from the proposed numerical method. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 35: 27–33, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10507
A study of laser SNR in an erbium‐doped fiber laser subject to external injection
Authors: Teyo T. C. , Mohd Shah N. S. , Ahmad H.
Published: September 2002

Variation of laser signal‐to‐noise ratio (SNR) in an erbium‐doped fiber‐ring laser system subject to external injection is presented. Laser SNR is found to be dependent not only on the injected power, but also on the amplification characteristic over the entire amplified spontaneous emission (ASE) bandwidth. Both laser SNR and injected power as a function of the signal detuning show an inverse relation with the ASE spectral profile. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 35: 40–42, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10509
Microwave characteristics of long TWPDs for high‐power operation
Authors: Kong Soon‐Cheol , Yoon Sang‐Jun , Choi Young‐Wan
Published: September 2002

Microwave characteristics of traveling‐wave photodetectors (TWPD) calculated with the use of the finite‐difference–time‐domain (FDTD) method are presented. When a TWPD is long for high‐power operation, microwave loss affects the bandwidth. This article presents a design guide for microwave characteristics for long TWPDs. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 35: 51–54, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10513
High‐performance micromachined tapered spiral inductors with resonant frequency of 17 GHz
Authors: Lin Yo‐Sheng , Hsu Heng‐Ming
Published: September 2002

A 4.5‐turn spiral inductor with tapered Cu metal width (ΔW = 3 μm) fabricated on normal silicon substrate (∼750 μm) exhibited a high quality factor of 9.68 at 2.0 GHz, which is 18.8% higher than that (8.15) of a 4.5‐turn spiral inductor with comparable outer dimension and equal Cu metal width fabricated on the same substrate. This phenomenon results from an effectively smaller series resistance of the tapered spiral inductor structure due to smaller eddy current effect. In addition, if the silicon substrate of the 4.5‐turn tapered spiral inductor (ΔW = 3 μm) is thinned down to about 22 μm by micro‐machined method, the quality factor and resonant frequency can be greatly improved to 15.6 and 17 GHz, respectively. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 35: 56–60, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10515
The influence of the time step on the numerical dispersion error of an unconditionally stable 3‐D ADI‐FDTD method: A simple and unified approach to determine the maximum allowable time step required by a desired numerical dispersion accuracy
Authors: Zhao Anping
Published: September 2002

In this paper, by analyzing the numerical dispersion property of an unconditionally stable three‐dimensional alternating direction implicit finite‐difference time‐domain (ADI‐FDTD) method, the influence of the time steps on the numerical dispersion error of the method is investigated. It is demonstrated that, to keep the numerical dispersion error of the method within a certain level of accuracy, an upper limit for the time step allowed to be used in the method exists and it can be theoretically determined. Particularly, in order to systematically determine the upper limit for the computational domain meshed with arbitrary uniform and non‐uniform grids, a special strategy used to divide Yee's cells into different categories is developed. Subsequently, a simple and unified approach for determining the maximum allowable time steps (i.e., the upper limits) from a desired numerical dispersion accuracy is proposed. Most importantly, with the help of the proposed approach, the maximum allowable time steps can be simply and easily determined once the meshing of structures (meshed with either uniform or non‐uniform grids) is known, i.e., without carrying out any real ADI‐FDTD simulations for the structures. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 35: 60–65, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10516
A fast analysis of microwave devices by the combined unifrontal/multifrontal solver for unsymmetric sparse matrices
Authors: Chen R. S. , Wang D. X. , Yung Edward K. N. , Jin J. M.
Published: September 2002

The multifrontal method is applied for solving a large, sparse, and unsymmetric system of linear equations resulting from the use of the edge‐based finite‐element method (FEM). The finite‐element method combined with perfectly matched layers (PML) is given for simulation of microwave devices, and the combined algorithm of the multifrontal method is described. The electrical characteristics of typical waveguide devices such as the ferrite phase shifter and circulator are analyzed, and the calculated results are compared with those obtained from the literature. In order to demonstrate the efficiency of the multifrontal method, the computational time is compared with that of both successive overrelaxation (SOR) preconditioned conjugate‐gradient (PCG) and conjugate‐gradient methods (CG) for the phase shifter. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 35: 76–81, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10521
Nonrepetition of differential phase shift of latching ferrite phase shifter
Authors: Che Wenquan , Yung Edward K. N.
Published: September 2002

A phenomenon called nonrepetition of differential phase shift in several latching ferrite phase shifters has been investigated. The relationship between the remanent magnetic strength (4πMr) and the bias magnetic field (H0) has been studied. It has been revealed that the slope of the initial section of the curve (4πMr ∼ H0) severely affects the repetition of the differential phase shift. In addition, a physical explanation is given and measurements used to solve the problem have been presented. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 35: 81–85, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10522
Erratum to “The hybrid FEM‐MoL approach for the analysis of scattering problems”
Authors: Xiao Ying , Lu Yilong
Published: September 2002

The addresss for Ying Xiao in the above article was incomplete. The entire address appears below. We apologize for the omission.

Institute of High Performance Computing, 1 Science Park Road, #01‐01 The Capricorn, Singapore Science Park 2, Singapore 117528
Interventions for anemia in pediatric cancer patients
Authors: Ruggiero Antonio , Riccardi Riccardo
Published: September 2002

Background

Children with cancer frequently develop anemia both from the disease and from chemo‐ and radiotherapy. Considered a manageable complication, anemia is often not treated until it becomes severe, i.e., hemoglobin (Hb) level ≤ 7 g/dL. The most frequent treatment employed for anemia in children with cancer is blood transfusion.

Procedure and Results

A retrospective survey of 74 children demonstrated that the use of blood transfusions increased as the intensity of therapy increased. At least one blood transfusion was administered to 12.5% of children who received standard chemotherapy, and to 59.5% of children who received intensive chemotherapy. These data also show that a substantial percentage of children did not receive treatment for intensive or high‐dose chemotherapy, whereas anemia occurred in almost all patients. Recombinant human erythropoietin (rHuEPO, epoetin alfa) has been shown to be effective in adults in increasing Hb levels and in improving outcomes, including quality of life and survival. The use of epoetin alfa in children has not been extensively studied, and only a few clinical trials have been conducted.

Conclusions

The good results seen in adults, data thus far in pediatrics, and the need for alternatives to transfusions in children make epoetin alfa an attractive treatment option for anemia in pediatric cancer patients. Clinical studies are underway to evaluate the efficacy and safety of epoetin alfa in increasing Hb values and improving outcomes in children with cancer. Med Pediatr Oncol 2002;39:451–454. © 2002 Wiley‐Liss, Inc.
Fine structure of leydig and sertoli cells in the testis of immature and mature spotted ray Torpedo marmorata
Authors: Marina Prisco , Annamaria Liguoro , Barbara D'onghia , Loredana Ricchiari , Piero Andreuccetti , Francesco Angelini
Published: September 2002

An ultrastructural investigation revealed the presence of true Leydig cells in the testis of sexually mature specimens of Torpedo marmorata. They showed the typical organization of steroid‐hormone‐producing cells, which, however, changed as spermatocysts approached maturity. In fact, they appeared as active cells among spermatocysts engaged in spermatogenesis, while in regions where spermiation occurred, they progressively regressed resuming the fibroblastic organization typically present in the testis of immature specimens. Such observations strongly suggest that these cells might be engaged in steroidogenesis and actively control spermatogenesis. Sertoli cells, too, appeared to play a role in spermatogenesis control, since, like Leydig cells, they showed the typical aspect of steroidogenic cells. In addition, the presence of gap junctions between Sertoli cells suggests that their activity might be coordinated. After sperm release, most Sertoli cells were modified and, finally, degenerated, but few of them changed into round cells (cytoplasts) or round cell remnants, which continued their steroidogenic activity within the spermatocyst and the genital duct lumen. From the present observations, it can be reasonably concluded that, in T. marmorata, spermatogenesis depends on both Leydig and Sertoli cells, and, as postulated by Callard (1991), in cartilaginous fish, the function of the Leydig cells as producers of steroids might be more recent and subsequent to that of Sertoli cells. In this regard, it is noteworthy that, in immature males, when Leydig cells showed a fibroblastic organization, Sertoli cells already displayed the typical organization of a steroidogenic cell Mol. Reprod. Dev. 63: 192–201, 2002. © 2002 Wiley‐Liss, Inc.
Effects of β‐endorphin and Naloxone on in vitro maturation of bovine oocytes
Authors: Dell'Aquila M.E. , Casavola V. , Reshkin S.J. , Albrizio M. , Guerra L. , Maritato F. , Minoia P.
Published: September 2002

Bovine cumulus‐oocyte complexes (COCs) and mural granulosa cells express the mRNA coding for the μ‐opioid receptor. The addition of β‐endorphin (β‐end) to oocytes cultured in hormonally‐supplemented in vitro maturation (IVM) medium had no effect on the rates of oocytes reaching the metaphase II (MII) stage, but significantly decreased the maturation rate (P < 0.05) and arrested oocytes at metaphase I (MI) after culture in hormone‐free medium (P < 0.001). Naloxone (Nx) reverted this inhibitory effect of β‐end. Moreover, Nx “per se” showed a dose‐dependent dual effect. When added at high concentration (10−3 M), it significantly reduced the rate of oocytes in MII (P < 0.001), thus increasing the rate of oocytes arrested in MI. However, Nx added at low concentration (10−8 M) significantly increased oocyte maturation (P < 0.001). High concentration of Nx induced an increase in both intracellular calcium concentration ([Ca2+]i) and in the activity of the mitogen‐activated protein kinase (MAPK) also called extracellular‐regulated kinase (ERK) in cumulus cells of bovine COCs. Blocking the rise in [Ca2+]i with the calcium chelator acetoxymethylester‐derived form of bis (o‐aminophenoxy) ethane‐N,N,N′,N′‐tetraacetic acid (BAPTA‐AM) reversed the Nx‐dependent inhibition of meiotic maturation observed at high Nx concentrations. Whereas blocking ERK with the MAPK/ERK kinase (MEK) inhibitor, PD98059, had no effect on this process. Therefore, we concluded that the μ‐opioid receptor, by inducing [Ca2+]i increase, participates in the cumulus‐oocyte coupled signaling associated with oocyte maturation. Mol. Reprod. Dev. 63: 210–222, © 2002 Wiley‐Liss, Inc.
Comparison between PMSG‐ and FSH‐induced superovulation for the generation of transgenic rats
Authors: Popova Elena , Krivokharchenko Alexander , Ganten Detlev , Bader Michael
Published: September 2002

Superovulation protocols using single injections of pregnant mare's serum gonadotropin (PMSG) or minipumps with follicle‐stimulating hormone (FSH) were compared in immature Sprague–Dawley (SD) rats. We used the following criteria: total number of ova, rate of fertilization, in vitro embryo development, sensitivity of zygotes to the microinjection of foreign DNA into the pronucleus, and their in‐vivo development after transplantation into the oviduct of a recipient. Female SD rats were stimulated with 15 IU PMSG or 10 mg FSH followed by the injection of human chorionic gonadotropin (hCG) at doses of 20 and 30 IU per female. After hCG administration, they were mated with males of the same strain and sacrificed on day 1 of pregnancy. The percentage of mated animals and the fertilization rate was similar in all groups. In rats given PMSG, the number of ovulated zygotes was hCG dose‐dependent. In contrast, the dose of hCG did not influence the efficiency of superovulation in rats given FSH, which was equal to PMSG‐treated rats at the optimal dose of hCG. The rates of in vitro blastocyst development (31.4 and 23.3%) and the resistance to microinjection into the pronucleus did also not differ significantly between zygotes of both studied groups. The proportion of offspring developing from microinjected zygotes after oviduct transfer (26.2 and 26.8%, respectively) and the rate of transgene integration per newborns (7.3 and 4.9%, respectively) was similar in both experimental groups. The results of this study demonstrate that superovulation of immature SD rats by PMSG is equally effective as FSH treatment and, thus, preferable for transgenic rat technology due to the lower costs and easier handling Mol. Reprod. Dev. 63: 177–182, 2002. © 2002 Wiley‐Liss, Inc.
Cross‐linking of ZP2 and ZP3 by transglutaminase is required for the formation of the outer layer of fertilization envelope of carp egg
Authors: Chang Yea‐Sha , Wang Yu‐Wen , Huang Fore‐Lien
Published: September 2002

A transglutaminase (TGase) cDNA was cloned from carp ovary. It was highly homologous to zebrafish TGase. Immunoblot and enzymatical assay showed that TGase was present on the chorion and in the cytoplasm of carp eggs. Addition of TGase inhibitor, cadaverine or ethylene diaminetetracetic acid (EDTA) to the cortical reaction medium impaired the formation of the outer layer of fertilization envelope (FEo), the adhesive structure of carp egg. Fibroin‐like substance (FLS), cystatin, cathepsin‐like substance (CLS), and FEO‐1 were the components of FEo, wherein the majority of the former three were conjugated to form macromolecules of 90–205 kDa while the latter one was present in monomer of 22 kDa. Cadaverine interfered slightly the discharge of FLS conjugates out of the perivitelline space (PVS) but affected profoundly the recruitment of FLS conjugates to FE, whereas EDTA completely inhibited both the release and the recruitment of FLS conjugates to FE. Both EDTA and cadaverine did not inhibit the discharge of FEO‐1 out of PVS but could inhibit the recruitment of FEO‐1 to FE. The mechanism was studied. ZP2 and ZP3, the major constituents of inner layer of FE, were cross‐linked during cortical reaction, which rendered FE hardened. In the presence of EDTA, the cross‐linking of ZP2 and ZP3 were inhibited, thus FE remained soft. The PVS of an egg with a hardened FE was less expanded than an egg with a soft FE. It was assumed that a less expanded PVS would generate a higher fluid pressure than a more expanded PVS did. Therefore, the transportation of the macromolecules such as the FLS‐cystatin‐CLS conjugates out of PVS was facilitated in control and cadaverine‐treated eggs whose FE were hardened but was blocked in EDTA‐treated eggs whose FE were unhardened. On the other hand, the transportation of small molecules such as FEO‐1 out of FE was not restrained, so they were discharged out of the PVS of the control and TGase inhibitor‐treated eggs. In addition, TGase activity was also required for the recruitment of FLS conjugates to FE. Mol. Reprod. Dev. 63: 237–244, © 2002 Wiley‐Liss, Inc.
Link protein as an enhancer of cumulus cell–oocyte complex expansion
Authors: Sun Guang Wei , Kobayashi Hiroshi , Suzuki Mika , Kanayama Naohiro , Terao Toshihiko
Published: September 2002

To investigate the specific components involved in regulating cumulus cell–oocyte complex (COC) expansion in an in vitro mouse experiment, freshly‐isolated COC were cultured in the presence of various combinations of FSH (1.0 μg/ml), proteins of the inter‐α‐inhibitor (IαI) family (a light chain, also known as bikunin, heavy chains [HC1 +  HC2] and IαI [0.01–2.0 μg/ml]) and link protein (LP) (0.016–10 μg/ml) for 24 h and were observed for expansion of their cumulus cells (percent of COC with + 3 and + 4 expansion and average projected area). The COC were videotaped in real time at the initiation of culture and after 24 h of culture. FSH alone did not stimulate cumulus expansion under serum‐free conditions; however, treatment with IαI (0.1–2.0 μg/ml) or heavy chains (10 μg/ml), but not bikunin (10 μg/ml), in the presence of FSH significantly increased COC expansion, with maximal promotion occurring at 1.0 μg/ ml of IαI. Addition of LP (2.0 μg/ml) to the medium containing IαI (1.0 μg/ml) and FSH resulted in significantly higher expansion levels than were observed in response to IαI alone, although LP alone (10 μg/ml) had no or very little effect by itself. Anti‐IαI or anti‐LP polyclonal antibody, which inhibits binding of IαI and LP, respectively, to hyaluronic acid (HA), markedly reduced expansion of the surrounding cumulus cell extracellular matrices. Therefore, in vitro, LP might serve, in part, to enhance the COC expansion possibly by stabilizing HA‐IαI (or heavy chains) complex on the surrounding cumulus cell matrices. Mol. Reprod. Dev. 63: 223–231, © 2002 Wiley‐Liss, Inc.
Capacitation state‐dependent changes in adenosine receptors and their regulation of adenylyl cyclase/cAMP
Authors: Adeoya‐Osiguwa Susan A. , Fraser Lynn R.
Published: September 2002

This study was designed to localize adenosine receptors and to provide evidence that specific receptors are active only in either uncapacitated or capacitated mouse spermatozoa, where they play a role in regulating cAMP production. Using specific antibodies, stimulatory A2A receptors were localized primarily on the acrosomal cap region and the flagellar principal piece. Interestingly, the staining was much more pronounced in uncapacitated than in capacitated spermatozoa, suggesting capacitation‐dependent changes in epitope accessibility. A1 receptors showed a very similar distribution, but the staining was markedly greater in capacitated than in uncapacitated cells. After addition of purified decapacitation factor (DF) to capacitated cells, strong staining for A2A was regained, suggesting reversibility in epitope accessibility. Chlortetracycline analysis revealed that an agonist specific for A2A receptors had no detectable effect on capacitated cells, but after DF‐induced decapacitation, the agonist then stimulated capacitation. That agonist also significantly stimulated cAMP production in uncapacitated cells, had no effect on capacitated cells, but regained the ability to stimulate cAMP in the latter following DF treatment. In contrast, an A1 agonist inhibited cAMP in capacitated cells. These results indicate that specific adenosine receptors function in a reversible manner in one or other capacitation state, resulting in regulation of cAMP. Mol. Reprod. Dev. 63: 245–255, © 2002 Wiley‐Liss, Inc.
Molecular cloning and sequencing of cDNA encoding for human FA‐1 antigen
Authors: Naz Rajesh K. , Zhu Xiaolong
Published: September 2002

The cDNA encoding for the human FA‐1 sperm antigen was cloned and sequenced from the in‐house constructed subtractive human testis cDNA expression library in λZiplox using the FA‐1 monoclonal antibody (mAb). The full‐length sequence was obtained by using the 5′ rapid amplification of 5′‐cDNA end (5′‐RACE) procedure. It is 1,576‐bp long, and has an open reading frame (ORF) of 283 amino acids (aa) with the first ATG Met start codon at nucleotide (nt) 57 and the stop codon TAG at nt 906. It has two termination codons at the 5′ end before the ATG start codon. The translated protein has a calculated molecular weight of 32.1 kDa and estimated isoelectric point (pI) of 11.59. It has one potential N‐linked glycosylation site and one tyrosine phosphorylation site, besides several O‐linked glycosylation and serine and threonine phosphorylation sites. Hydrophilicity analysis of the deduced aa sequence showed it to be a membrane‐anchored protein. Extensive computer search in the database did not identify any known nt/aa sequence having homology with FA‐1 cDNA or deduced aa, indicating it to be a novel gene. The Northern blot and reverse transcription‐polymerase chain reaction (RT‐PCR)–Southern blot analyses indicated the testis‐specific expression of FA‐1 antigen at the mRNA level. The ORF of the FA‐1 was subcloned into pGEX‐1λT for expression. The expressed FA‐1 recombinant protein had a molecular size of ∼40 kDa, and was recognized by the FA‐1 mAb, and not by the myeloma control Ig. The rabbit antibodies (Ab) raised against the recombinant (r) FA‐1 antigen recognized the rFA‐1 antigen as well as the native (n) FA‐1 antigen. The rFA‐1 Ab specifically recognized a protein band of ∼50 kDa in human testis extract in the Western blot involving 11 types of human tissue extracts, indicating the testis‐specific expression of FA‐1 at the protein level. The Ab showed binding with live and methanol‐fixed human sperm at the post‐acrosomal, mid‐piece, and tail regions. The Ab caused a significant (P < 0.001) and concentration‐dependent inhibition of human sperm capacitation/acrosome reaction by blocking tyrosine phosphorylation of the FA‐1 antigen. The sperm‐specific human FA‐1 recombinant antigen may find applications in immunocontraception, and diagnosis and treatment of immunoinfertility in humans. Mol. Reprod. Dev. 63: 256–268, © 2002 Wiley‐Liss, Inc.
Proton electron double resonance imaging of the in vivo distribution and clearance of a triaryl methyl radical in mice
Authors: Li Haihong , Deng Yuanmu , He Guanglong , Kuppusamy Periannan , Lurie David J. , Zweier Jay L.
Published: September 2002

Proton electron double resonance imaging (PEDRI) measures the spatial distribution of paramagnetic species in biological samples using the Overhauser effect. Triaryl methyl (TAM) free radicals have been developed as a spin probe for PEDRI since they have very long T1e. Therefore, low RF power levels are sufficient to saturate the electron spin system with resultant high NMR enhancement facilitating application of PEDRI in living animals. In this report, PEDRI studies were performed at 0.02 T. The power‐dependent image enhancement was studied using phantoms of TAM in saline, then the distribution and pharmacokinetics of TAM in living mice were measured. Following intravenous administration of 0.7 mmol/kg of TAM, enhancements of up to −34 were observed enabling visualization of its distribution within the body. Maximum uptake of TAM in the vascular compartment was seen 1 min postadministration with half‐clearance within 5 min. Maximum uptake in the kidneys occurred at 10 min with half‐clearance at 26 min and maximum accumulation in the bladder after 50 min. Thus, TAM is initially compartmentalized in the vasculature and this is followed by rapid uptake and excretion by the kidneys. PEDRI enabled rapid imaging of the distribution and clearance of this paramagnetic probe and this information should facilitate the use of TAM as a label for oximetry and other applications. Magn Reson Med 48:530–534, 2002. © 2002 Wiley‐Liss, Inc.
Frequency‐modulated steady‐state free precession imaging
Authors: Foxall D.L.
Published: September 2002

Exploration of the possibilities of steady‐state free precession (SSFP) excitation has led to the discovery that it is tolerant of slow variations in spectral offset frequency. The effect has been used to eliminate banding artifacts from images obtained with the fully balanced SSFP imaging sequence. Magn Reson Med 48:502–508, 2002. © 2002 Wiley‐Liss, Inc.
Continuous arterial spin labeling using a local magnetic field gradient coil
Authors: Trampel Robert , Mildner Toralf , Goerke Ute , Schaefer Andreas , Driesel Wolfgang , Norris David G.
Published: September 2002

Continuous arterial spin labeling (ASL) using a locally induced magnetic field gradient for adiabatic inversion of spins in the common carotid artery of human volunteers is demonstrated. The experimental setup consisted of a helmet resonator for imaging, a circular RF surface coil for labeling, and gradient loops to produce a magnetic field gradient. A spin‐echo (SE) echo‐planar imaging (EPI) sequence was used for imaging. The approach is independent of the gradients of the MR scanner. This technology may be used if the imaging gradient system does not produce an appropriate magnetic field gradient at the location of the carotid artery—for example, in a head‐only scanner—and is a prerequisite for the development of a system that allows continuous labeling during the imaging experiment. Magn Reson Med 48:543–546, 2002. © 2002 Wiley‐Liss, Inc.
MRI of lungs using partial liquid ventilation with water‐in‐perfluorocarbon emulsions
Authors: Huang Ming Qiang , Ye Qing , Williams Donald S. , Ho Chien
Published: September 2002

A novel 1H‐MRI contrast modality for rat lungs has been developed using water‐in‐perfluorocarbon (PFC) emulsions for partial liquid ventilation™ (PLV). The feasibility of the new ventilation protocol for 1H‐MRI studies of lungs has been demonstrated. 1H‐MR images of lungs have been obtained with sensitivity and spatial resolution higher than those of the 19F‐MRI of lungs previously reported. Diffusion‐weighted MRI measurements of lungs showed that the results obtained are related to the pulmonary architecture and functional properties of lungs. Although the methodology needs further improvement and evaluation, it appears to have great potential in a wide range of new applications in the field of lung MRI, such as in vivo detection of lung cancer, emphysema, and allograft rejection following lung transplantation. The ability of this technique to achieve high‐quality MR images of lungs, together with its technical simplicity, stability, and low cost, makes this method a promising imaging technique for the lungs. Magn Reson Med 48:487–492, 2002. © 2002 Wiley‐Liss, Inc.
Quantitation of absolute 2H enrichment of plasma glucose by 2H NMR analysis of its monoacetone derivative
Authors: Jones John G. , Perdigoto Rui , Rodrigues Tiago B. , Geraldes Carlos F.G.C.
Published: September 2002

A simple 2H NMR method for quantifying absolute 2H‐enrichments in all seven aliphatic positions of glucose following its derivatization to monoacetone glucose is presented. The method is based on the addition of a small quantity of 2H‐enriched formate to the NMR sample. When the method was applied to [2‐2H]monoacetone glucose samples prepared from [2‐2H]glucose standards of known enrichments in the range of 0.2–2.5%, enrichment estimates derived by the NMR method were in good agreement with the real enrichment values of the [2‐2H]glucose precursors. The measurement was also applied to monoacetone glucose derived from human plasma glucose samples following administration of 2H2O and attainment of isotopic steady state, where glucose H2 and body water enrichment are equivalent. In these studies, the absolute H2 enrichment of plasma glucose estimated by the formate method was in good agreement with the 2H‐enrichment of body water measured by an independent method. Magn Reson Med 48:535–539, 2002. © 2002 Wiley‐Liss, Inc.
Recessed elliptical‐centric view‐ordering for contrast‐enhanced 3D MR angiography of the carotid arteries
Authors: Watts R. , Wang Y. , Redd B. , Winchester P.A. , Kent K.C. , Bush H.L. , Prince M.R.
Published: September 2002

Fast arterial‐venous transit in the carotid arteries requires accurate, reliable timing of the acquisition to the bolus transit to maximize arterial signal and minimize venous artifacts. The rising edge of the bolus is not utilized in conventional elliptical‐centric view‐ordering because the critical k‐space center must be acquired with full arterial enhancement. In this study, a recessed elliptical‐centric view‐ordering scheme is introduced in which the k‐space center is acquired a few seconds following scan initiation. The recessed view‐ordering is shown to be more robust to timing errors than the conventional scheme in a study of 37 patients. Magn Reson Med 48:419–424, 2002. © 2002 Wiley‐Liss, Inc.