bluuebunny/crossref_metadata_2025 huggingface dataset:
Physiological functions of imprinted genes
Authors: Tycko Benjamin , Morison Ian M.
Published: October 2002

Genomic imprinting in gametogenesis marks a subset of mammalian genes for parent‐of‐origin‐dependent monoallelic expression in the offspring. Embryological and classical genetic experiments in mice that uncovered the existence of genomic imprinting nearly two decades ago produced abnormalities of growth or behavior, without severe developmental malformations. Since then, the identification and manipulation of individual imprinted genes has continued to suggest that the diverse products of these genes are largely devoted to controlling pre‐ and post‐natal growth, as well as brain function and behavior. Here, we review this evidence, and link our discussion to a website (http://www.otago.ac.nz/IGC) containing a comprehensive database of imprinted genes. Ultimately, these data will answer the long‐debated question of whether there is a coherent biological rationale for imprinting. © 2002 Wiley‐Liss, Inc.
Role of leukemia inhibitory factor in the regulation of the proliferation and differentiation of neonatal mouse epidermal melanocytes in culture
Authors: Hirobe Tomohisa
Published: October 2002

Mouse epidermal melanoblasts/melanocytes preferentially proliferated from disaggregated epidermal cell suspensions derived from newborn mouse skin in a serum‐free melanoblast/melanocyte‐proliferation medium supplemented with dibutyryl adenosine 3′:5′‐cyclic monophosphate (DBcAMP) and/or basic fibroblast growth factor (bFGF). Leukemia inhibitory factor (LIF) supplemented to the medium from initiation of primary culture increased the proliferation of melanoblasts or melanocytes as well as the differentiation of melanocytes. Pure cultured primary melanoblasts or melanocytes were further cultured with the medium supplemented with LIF from 14 days (keratinocyte depletion). LIF stimulated the proliferation of melanoblasts or melanocytes as well as the differentiation of melanocytes in the absence of keratinocytes. Moreover, anti‐LIF antibody supplemented to the medium from initiation of primary culture inhibited the proliferation of melanoblasts or melanocytes as well as the differentiation of melanocytes. These results suggest that LIF is one of the keratinocyte‐derived factors involved in regulating the proliferation and differentiation of neonatal mouse epidermal melanocytes in culture in cooperation with cAMP elevator and bFGF. © 2002 Wiley‐Liss, Inc.
New insights into the role of extracellular matrix during tumor onset and progression
Authors: Pupa Serenella M. , Ménard Sylvie , Forti Stefania , Tagliabue Elda
Published: October 2002

Recently, a view of the tumor as a functional tissue interconnected with the microenvironment has recently been described. For many years, the stroma has been studied in the context of the malignant lesion, and only rarely has its role been considered before carcinogenic lesions appear. Recent studies have provided evidence that stromal cells and their products can cause the transformation of adjacent cells through transient signaling that leads to the disruption of homeostatic regulation, including control of tissue architecture, adhesion, cell death, and proliferation. It is now well established that tumor progression requires a continually evolving network of interactions between neoplastic cells and extracellular matrix. A relevant step of this process is the remodeling of microenvironment which surrounds tumors leading to the release of ECM‐associated growth factors which can then stimulate tumor and/or endothelial cells. Finally, tumor cells reorganizing the extracellular matrix to facilitate communications and escape the homeostatic control exerted by the microenvironment modify response to cytotoxic treatments. © 2002 Wiley‐Liss, Inc.
Sonography of soft tissue masses of the neck
Authors: Gritzmann Norbert , Hollerweger Alois , Macheiner Peter , Rettenbacher Thomas
Published: October 2002

In many clinical conditions, high‐resolution sonography and color (power) Doppler sonography can be used as the first‐line modality for evaluating cervical soft tissue masses. Cervical cysts, lipomas, paragangliomas, neurogenic tumors, hemangiomas, and lymphangiomas often exhibit characteristic sonographic appearances. Sonography can be used for lymph node assessment, and most salivary gland diseases can be diagnosed sonographically. Sonography can be used to guide needle biopsy of soft tissue neoplasms and lymph nodes. In addition, the relationship between a cervical mass and the great vessels can be evaluated. © 2002 Wiley Periodicals, Inc. J Clin Ultrasound 30:356–373, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/jcu.10073
Phagocytosis—The mighty weapon of the silent warriors
Authors: Djaldetti Meir , Salman Hertzel , Bergman Michael , Djaldetti Ruth , Bessler Hanna
Published: October 2002

Professional phagocytes, comprising polymorphonuclear neutrophils and monocyte/macrophage cells, play an important role in the host defense. Any defect in their function exposes the organism to microbial intruders terminating in fatal diseases. The functional responses of the phagocytes to bacterial and fungal infections include chemotaxis, actin assembly, migration, adhesion, aggregation, phagocytosis, degranulation, and reactive oxygen species production. Superoxide generation by phagocytic NADPH oxidase is an imperative step toward bacterial killing. Phagocytes participate in inflammatory reactions and exert tumoricidal activity. They are supported by serum factors such as immunoglobulins, cytokines, complement, the acute phase reactant C‐reactive protein, production of antibacterial proteins, and others. In addition to their principal task to eliminate bacteria, they are engaged in removing damaged, senescent, and apoptotic cells. Engulfed cell debris, large particles such as latex beads, fat, and oil droplets, are examples of phagocytic activity illustrated in the present review with transmission and scanning electron microscope micrographs. Numerous factors, such as diseases and stressful conditions, affect the engulfing activity of the professional phagocytes. Our experience regarding the impaired phagocytic capacity of cells in patients with diabetes and chronic renal failure is discussed. The results obtained in our laboratory from experiments detecting the effect of strenuous physical exercise, hypothermia, fasting, and abdominal photon irradiation on the phagocytic capacity of human polymorphonuclear neutrophils and rat peritoneal macrophages are hereby summarized and the reports on those subjects in the recent literature are reviewed. A variety of assays are applied for quantifying phagocytosis. Flow cytometry based on incubation of phagocytic cells with fluorescent conjugated particles and measuring the amount of fluorescence as an indicator of the engulfing capacity of the cells is a useful method. A direct visualization of the ingested particles using light or electron microscopy is a valuable tool for estimation of phagocytic function. In our hands, the use of semithin sections of embedded phagocytes following their incubation with latex particles provided satisfactory results for measuring the total number of phagocytic cells, as well as the internalizing capacity of each individual cell. Microbiological assays, the nitroblue tetrazolium test, quantitation of antibody‐ and antigen‐mediated phagocytosis, as well as methods reviewed in detail in other reports are additional applications for determination of this intricate process. Microsc. Res. Tech. 57:421–431, 2002. © 2002 Wiley‐Liss, Inc.
Phagocytosis by invertebrate hemocytes: Causes of individual variation in Panorpa vulgaris scorpionflies
Authors: Kurtz Joachim
Published: October 2002

An in vitro phagocytosis assay, adjusted to as little as 1 μL of insect hemolymph, enables the microscopic determination of phagocytosis for single individuals of small insects. Even repeated determination over the lifetime of individuals is possible. This method makes it feasible to study individual variation in invertebrate phagocytic capacity. Possible sources of such variation are reviewed in this article: genetic differences, development, aging, reproduction, presence of parasites, and diverse environmental influences are natural sources of individual variation in phagocytosis. However, the methods used for phagocytosis and microscopic evaluation are also (unwelcome) sources of variation. To optimize incubation time for in vitro phagocytosis, time courses were determined. Furthermore, the reliability of visual counting and image analysis for the microscopic quantification of phagocytosis are compared. The influences of larval development and adult aging on phagocytosis by Panorpa vulgaris hemocytes are subsequently demonstrated. During development, a decrease in hemocyte numbers but a simultaneous increase in the proportion of phagocytosing hemocytes was observed when larvae reached pupation. On the other hand, adults showed a dramatic decrease in phagocytic capacity with age, while cell numbers remained fairly constant. The results show that individual variation in phagocytosis can be determined accurately in small invertebrates and related to its causes. This might be especially interesting in the context of studies relating individual immunocompetence to ecology, life history variation, and behavior. Microsc. Res. Tech. 57:456–468, 2002. © 2002 Wiley‐Liss, Inc.
Bacteria–hemocyte interactions and phagocytosis in marine bivalves
Authors: Canesi Laura , Gallo Gabriella , Gavioli Miriam , Pruzzo Carla
Published: October 2002

Marine bivalves (such as mussels, oysters, and clams) are widespread mollusks in coastal waters at different latitudes; due to their filter‐feeding habits, they accumulate large numbers of bacteria from the harvesting waters and may act as passive carriers of human pathogens. To cope with this challenge, bivalves possess both humoral and cellular defense mechanisms with remarkably effective capabilities. The circulating cells, or hemocytes, are primarily responsible for defense against parasites and pathogens; microbial killing results from the combined action of the phagocytic process with humoral defense factors such as agglutinins (e.g., lectins), lysosomal enzymes (e.g., acid phosphatase, lysozyme), toxic oxygen intermediates, and various antimicrobial peptides. In this work, current knowledge of the mechanisms underlying the interactions between bacteria and the hemolymph components of marine bivalves is summarized. Bacterial susceptibility to hemolymph killing in different bivalve species may be a consequence of the different ability of bacterial products to attract phagocytes, the presence or absence of specific opsonizing molecules, the hemocyte capability to bind and engulf different bacteria, and the different bacterial sensitivity to intracellular killing. The role of soluble (e.g., agglutinins and opsonins) and surface‐bound factors in bacterial phagocytosis by hemocytes of the most common marine bivalve species is described and the possibility that environmental temperatures and other seasonal factors may influence this process is considered. Moreover, the potential strategies used by bacteria to evade phagocytic killing by hemocytes are discussed. From the available data it is clear that several questions need further investigation; the elucidation of the factors influencing phagocytosis in bivalves and the fundamental strategies used by bacteria to escape hemolymph killing are important not only to understand bivalve immune defenses but also to explain the persistence of pathogenic bacteria in bivalve tissues and to predict the consequent impact on human health. Microsc. Res. Tech. 57:469–476, 2002. © 2002 Wiley‐Liss, Inc.
Amphibia Kupffer cells
Authors: Sichel Giovanni , Scalia Marina , Corsaro Concetta
Published: October 2002

Amphibia Kupffer cells (i.e., liver resident macrophages) show many common characteristics when compared with Mammalia Kupffer cells: filopodia, microvillous‐like structures, lamellipodia, fuzzy coat, coated vesicles, bristled vacuoles, nonspecific esterase activity, and pinocytotic and phagocytic activity are present both in Amphibia and Mammalia Kupffer cells. On the other hand, some differences are present between Kupffer cells of both zoological classes: phagocytosed red cells and their derivatives, iron–protein complexes, and lipofuscin bodies are normally present in Amphibia Kupffer cells, but absent in the same cells of healthy mammals. Worm‐like structures are not seen in Amphibia and endogenous peroxidase activity is very weak in these animals compared with Mammalia. The most important difference lies in the ability of Amphibia Kupffer cells to produce melanins: in fact the tyrosinase gene is expressed, “melanosome centers” are present, and dopa oxidase activity is demonstrable. Microsc. Res. Tech. 57:477–490, 2002. © 2002 Wiley‐Liss, Inc.
Fate of donor bone marrow cells in medial collateral ligament after simulated autologous transplantation
Authors: Watanabe Nobuyoshi , Woo Savio L‐Y. , Papageorgiou Christos , Celechovsky Chris , Takai Shinro
Published: October 2002

A potential strategy to enhance ligament healing by transplantation of mesenchymal stem cells (MSCs), which are demonstrated to differentiate into fibroblast‐like cells in vitro, is presented. The objective of this study was to follow transplanted nucleated cells from bone marrow, which contain MSCs, in the healing medial collateral ligament (MCL) over time, and to examine their phenotype and survivability. It was hypothesized that MSCs in nucleated cells from bone marrow would differentiate into fibroblast‐like cells in the healing ligament following adaptation to the environment. The transplantation model employed in this study eliminates the immune response to a donor by the recipient using a transgenic rat (donor), which does not produce foreign protein from transgenes, and its wild‐type rat (recipient) in order to simulate autologous transplantation. The MCL of the wild‐type rat was ruptured, where 1 × 106 nucleated cells of bone marrow from the transgenic rat were injected. The transgenes in transplanted nucleated cells were detected throughout the healing MCL for 28 days by in situ hybridization. At 3 days, many donor cells were evident in the injury site and fascial pocket, and some were found in the midsubstance. Morphologically, transplanted cells with elongated nuclei were found at the ruptured edge of the midsubstance and surface of the unruptured site after 3 days. At 28 days, these cells continued to survive in the healing MCL. Their shapes were similar to those of surrounding recipient MCL fibroblasts. Thus, transplanted cells might differentiate into fibroblasts. Therefore, it was demonstrated that there is a potential for nucleated cells from bone marrow to serve as a vehicle for therapeutic molecules as well as to be a source in enhancing healing of ligaments. Microsc. Res. Tech. 58:39–44, 2002. © 2002 Wiley‐Liss, Inc.
Morphology and evolution of the respiratory apparatus in the family Eubelidae (Crustacea, Isopoda, Oniscidea)
Authors: Paoli Pasquino , Ferrara Franco , Taiti Stefano
Published: October 2002

The morphology of the respiratory apparatus in the pleopodal lungs of the family Eubelidae was investigated. The family is a monophyletic group including more than 240 species in 53 genera (three of which are nomina dubia), mostly distributed in the Afrotropical Region (tropical Africa and Arabian Peninsula). In all the Eubelidae, except for the monospecific genus Parelumoides and two species of the genus Elumoides, the exopods of pleopods have lungs. All the pulmonary morphologies present in the entire suborder Oniscidea are found: 1) uncovered lungs, composed of a pleated respiratory surface, directly exposed to the air (Atracheodillo‐type) or partially enclosed within the appendage (Synarmadilloides‐type); 2) covered lungs with several spiracles and respiratory trees, housed within the appendages, with spiracles surrounded by a specialized, nonrespiratory, structure (perispiracular area) (Eubelum‐ and Somaloniscus‐types); 3) covered lungs with only one spiracle, with or without perispiracular area, and one respiratory tree (Aethiopopactes‐ and Periscyphis‐types), which in taxa with Periscyphis‐type lung crosses the insertion of the appendage and penetrates into the pleon with bundles of respiratory tubules. The evolution of the various types of lungs is discussed. It is concluded that the two main evolutionary lines, i.e., uncovered lungs and covered lungs, originated independently from an ancestral respiratory structure—the semilunar area. A first mechanism of development of the semilunar area by folding of its surface produced the Atracheodillo‐type (all folds coplanar with the surface of the exopod) and Synarmadilloides‐type (folds partly coplanar and partly intraflexed inside the exopod) uncovered lungs. A second mechanism of development by tubular invagination of the cuticle of the semilunar area produced the polyspiracular Eubelum‐type lungs (numerous arborescent invaginations) and the monospiracular Aethiopopactes‐type lungs (only one arborescent invagination), probably passing through a common intermediate pattern. From the common pattern, both the poly‐ and monospiracular types would have inherited the characteristic concave cell arrangement of the perispiracular area. The Somaloniscus‐type and Periscyphis‐type lungs are forms specialized for arid environments, directly derived from the Eubelum‐type and Aethiopopactes‐type, respectively. J. Morphol. 253:272–289, 2002. © 2002 Wiley‐Liss, Inc.
A complete substitutional analysis of VIP for better tumor imaging properties
Authors: Bhargava Sarah , Licha Kai , Knaute Tobias , Ebert Bernd , Becker Andreas , Grötzinger Carsten , Hessenius Carsten , Wiedenmann Bertram , Schneider‐Mergener Jens , Volkmer‐Engert Rudolf
Published: October 2002

Since numerous tumor cells overexpress the vasoactive intestinal peptide (VIP) receptor subtype 1 (VPAC1), VIP–dye conjugates would be useful as contrast agents for in vivo imaging. However, proteolytic degradation of VIP in vivo limits their diagnostic use and highlights the need for structurally optimized VIP derivatives with improved pharmacokinetics. Here, we applied parallel nano‐synthesis of cleavable peptides on cellulose membranes to perform a complete VIP substitutional analysis. The resulting 504 different VIP–dye analogs were tested for cell binding by flow cytometry. They provided a detailed analysis of amino acid positions essential for binding to VPAC1 overexpressing cells. A generalized VIP–dye binding motif derived from the substitutional analysis results served as a reference point for further optimization. An [Arg8]‐VIP‐dye analog showed increased stability towards proteolytic degradation, good tumor‐to‐tissue contrast in mice and a longer half‐life in vivo. Copyright © 2002 John Wiley & Sons, Ltd.
Influence of oxygen flow rate on signal and T1 changes in oxygen‐enhanced ventilation imaging
Authors: Mai Vu M. , Liu Benjamin , Li Wei , Polzin Jason , Kurucay Saban , Chen Qun , Edelman Robert R.
Published: October 2002

Purpose

To investigate the optimal oxygen flow rate for oxygen‐enhanced MR ventilation imaging.

Materials and Methods

Using a cardiac‐triggered nonselective inversion recovery (IR) half Fourier single‐shot fast spin echo sequence, series of images were acquired with the subject alternately inhaling room air and 100% oxygen. Oxygen flow rates of 5 L/min, 10 L/min, 15 L/min, 20 L/min, and 25 L/min were studied, and signal intensity from the oxygen‐enhanced ventilation images and T1 of the lung were measured.

Results

The average signal intensity was 63.0 ± 21.0 for 5 L/min, 98.7 ± 26.8 for 10 L/min, 133.8 ± 20.0 for 15 L/min, 138.7 ± 19.7 for 20 L/min, and 139.2 ± 37.9 for 25 L/min. The average T1's of the lung were 1399 msec ± 130 msec for room air, 1314 msec ± 101 msec for 5 L/min, 1276 msec ± 105 msec for 10 L/min, 1207 msec ± 71 msec for 15 L/min, 1206 msec ± 90 msec for 20 L/min, and 1207 msec ± 42 msec for 25 L/min.

Conclusion

The optimal flow rate is 15 L/min for oxygen‐enhanced ventilation imaging. J. Magn. Reson. Imaging 2002;16:37–41. © 2002 Wiley‐Liss, Inc.
What do matrix‐assisted laser desorption/ionization mass spectra reveal about ionization mechanisms?
Authors: Papantonakis Michael R. , Kim Jun , Hess Wayne P. , Haglund Richard F.
Published: October 2002

We present ion mass spectra obtained by matrix‐assisted laser desorption/ionization for analytes of ∼1000 Da across the largest range of wavelengths and pulse durations to date. The matrix used in all cases was 2,5‐dihydroxybenzoic acid. Based on the data and fundamentals of laser–material interactions, we evaluated the plausibility of discriminating among such ion formation mechanisms as multiphoton ionization and excited‐state ionization from mass spectra alone. Some previously proposed mechanisms appear unlikely for the matrix–analyte systems that we studied, casting doubt on their general applicability. Moreover, although analysis of mass spectra can apparently exclude certain mechanisms, it cannot establish which of several competing mechanisms is actually operative. This is particularly true with respect to variations in pulse duration and wavelength. Copyright © 2002 John Wiley & Sons, Ltd.
Characterization of silicate monomer with sodium, calcium and strontium but not with lithium and magnesium ions by fast atom bombardment mass spectrometry
Authors: Tanaka Miho , Takahashi Kazuya
Published: October 2002

Fast atom bombardment mass spectrometry (FABMS) was applied to the direct detection of silica species dissolved in LiCl, NaCl, MgCl2, CaCl2 and SrCl2 solutions in order to investigate its dissolution process in solution. Several species of dissolved silicate complexes in the solution were directly detected by FABMS. The peak intensities of [SiO2(OH)2Na]−, [SiO3(OH)Ca]− and [SiO3(OH)Sr]− increased with increasing concentrations of NaCl, CaCl2 and SrCl2, whereas the peak intensities of [SiO2(OH)2Li]− and [SiO3(OH)Mg]− did not increase with increasing concentrations of LiCl and MgCl2. These results indicte that silicate and cation bind in the solution not after but before ionization. The isotope pattern of Sr2+ confirmed the existence of the silicate–Sr complex not only with increase of the concentration of silica but also the mass numbers of Sr. The silicate complexes formed with Na+, Ca2+ and Sr2+ showed high stability in chloride solution. This is in good accordance with the fact that Na+, Ca2+ and Sr2+ accelerate the dissolution of silica to form complexes during solution equilibrium. Considering that the stability constant was examined and reported in other papers, this new findings that Mg2+ does not form a complex with silicic acid (Si(OH)4) is very important. Copyright © 2002 John Wiley & Sons, Ltd.
Field evaluation of the efficacy and immunogenicity of recombinant hepatitis B vaccine without HBIG in newborn Vietnamese infants
Authors: Milne Alexander , West David J. , Chinh Dang Van , Moyes Chris D. , Poerschke Gabriele
Published: October 2002

A study involving more than 2,000 infants was conducted in Vietnam to assess the field effectiveness and immunogenicity of recombinant hepatitis B vaccine given at birth, 1 month, 2 months, without concomitant hepatitis B immune globulin (HBIG). All received a 5 μg dose of H‐B‐VAX™II at birth. Infants born to non‐carrier mothers (Group 1; N = 1798) then received 2.5 μg doses at 1 and 2 months of age, while infants of HBeAg‐negative (Group 2; N = 125) or HBeAg‐positive (Group 3; N = 88) carrier mothers received 5 μg doses. No Group 1 or 2 vaccinees were infected. In Group 3, 12 (14.6%) of 82 infants did become infected (estimated efficacy 84%). 98.0–98.6% of uninfected infants who were tested for anti‐HBs developed a seroprotective concentration ≥ 10 IU/L. In hyperendemic Vietnam, where routine maternal screening and passive‐active prophylaxis of high‐risk infants with vaccine plus HBIG is not feasible, administration of vaccine alone to all newborns may control effectively HBV infection. J. Med Virol. 67:327–333, 2002. © 2002 Wiley‐Liss, Inc.
Prolonged hepatitis A infection in an HIV‐1 seropositive patient
Authors: Costa‐Mattioli Mauro , Allavena Clotilde , Poirier Anne‐Sophie , Billaudel Sylviane , Raffi François , Ferré Virginie
Published: October 2002

Hepatitis A virus (HAV) is a worldwide disease; in most cases, it causes an acute self‐limited illness that does not lead to a chronic state. The course of HAV viremia in a homosexual male with human immunodeficiency virus type 1 (HIV‐1) and the correlation between HIV and HAV viral load, alanine aminotranferase (ALT) level, and CD4+ lymphocyte count were investigated during the course of the infection. HAV RNA was detected quantitatively up to 256 days after clinical onset. To our knowledge, this specific case is the first report of a prolonged infection with hepatitis A in a male with HIV‐1. The ALT levels decreased gradually; however, 286 days after clinical onset of hepatitis, ALT levels were three times higher than normal values. HIV viral load was not affected by the infection with HAV and CD4+ cell count was stable during the course of the co‐infection. The duration and the high‐titer viremia of hepatitis A virus in an immunodeficient patient constitute a serious risk of the spread of hepatitis A within this population. As inactivated HAV vaccine is safe in HIV‐positive subjects, it would be wise to establish a strategy of preventive vaccination in this high‐risk group. J. Med. Virol. 68:7–11, 2002. © 2002 Wiley‐Liss, Inc.
Intrahepatic MxA and PKR protein expression in chronic hepatitis C virus infection
Authors: MacQuillan Gerry C. , de Boer W. Bastiaan , Platten Michael A. , McCaul Kieran A. , Reed William D. , Jeffrey Gary P. , Allan Jane E.
Published: October 2002

The therapeutic effect of interferon‐alpha and ribavirin in the treatment of chronic hepatitis C viral infection is limited. To identify patient characteristics that may predict responsiveness to treatment, the intrahepatic protein expression of two directly induced IFN‐alpha effector proteins, MxA and PKR, were studied. Forty liver biopsy samples from patients with a variety of chronic liver diseases were stained for MxA and PKR protein using immunohistochemical techniques. In a HCV patient cohort, 30 liver biopsies were stained for MxA and PKR protein prior to treatment with IFN‐alpha and ribavirin. PKR protein expression was not upregulated in viral liver disease. In contrast, MxA protein expression was significantly upregulated in viral liver disease (P = 0.005). In chronic HCV liver disease, moderate to strong cytoplasmic expression of MxA protein was observed in hepatocytes and monocytes, indicating endogenous hepatocellular IFN‐alpha pathway activation. In the HCV patient cohort treated with combination therapy, strong pre‐treatment MxA hepatocyte expression was predictive of a non‐response to treatment (odds ratio 9.33; P = 0.01; 95% confidence interval 1.63–53.2). This effect was independent of HCV genotype and viral load. It is concluded that pretreatment hepatocellular MxA expression may become a useful predictor of response to combination treatment with IFN‐alpha and ribavirin. J. Med. Virol. 68:197–205, 2002. © 2002 Wiley‐Liss, Inc.
Frequency/time‐domain modelling of 3D waveguide structures by a BI‐RME approach
Authors: Arcioni P. , Bozzi M. , Bressan M. , Conciauro G. , Perregrini L.
Published: October 2002

This paper presents a full wave method for the determination of the mathematical model of a 3D waveguide structure in the form of the pole expansion in thes‐plane of its generalized admittance matrix. The method is based on a boundary integral‐resonant mode expansion approach. By the introduction of appropriate state‐variables, the method leads to the pole expansion by solving a linear generalized eigenvalue problem, like in the well‐known techniques used up to now in frequency/time domain modelling based on finite difference or finite element methods. With respect to these methods we have the advantage of a significant reduction in both memory allocation and computing time. Two examples show the accuracy of the results and the efficiency of the method. Copyright © 2002 John Wiley & Sons, Ltd.
A systematic approach for extracting lumped circuit parameters of microstrip discontinuities from their S‐parameter characteristics
Authors: Mittra R. , Suntives A. , Hossain M. S. , Ma J.
Published: October 2002

This paper describes a systematic approach for extracting the lumped circuit parameters of microstrip discontinuities from their S‐parameter characteristics—which are assumed to be known—by using a three‐ step procedure. We begin by computing the lumped equivalent circuit parameters, e.g., L, C, R and/or G, with a direct extraction procedure, which relates the S‐parameters to the Z‐ (or Y‐) parameters of the discontinuity. Next, we use these values as initial guesses for an optimization code based on the genetic algorithm, to obtain circuit parameters that are invariant over a specified frequency range. Finally, we develop an artificial neural network model for predicting the values of these circuit elements rapidly as we change the physical and electrical parameters of the discontinuity, for instance the width or height of the etch, and the complex dielectric constant of the substrate. The application of the direct extraction technique is first illustrated by considering a number of representative two‐port microstrip discontinuities, viz., the chamfered bend and gap discontinuities. It is then extended to three‐port structures, for instance, a T‐junction. The validation is given for the case examples investigated by comparing the S‐parameter calculated from the equivalent circuit with those obtained from a full‐wave EM solver. We also use the chamfered bend as a case example to illustrate the application of this three‐step procedure. Copyright © 2002 John Wiley & Sons, Ltd.
Developmental changes in the expression of iron regulatory proteins and iron transport proteins in the perinatal rat brain
Authors: Siddappa Asha Jyothi M. , Rao Raghavendra B. , Wobken Jane D. , Leibold Elizabeth A. , Connor James R. , Georgieff Michael K.
Published: October 2002

The perinatal brain requires a tightly regulated iron transport system. Iron regulatory proteins (IRPs) 1 and 2 are cytosolic proteins that regulate the stability of mRNA for the two major cellular iron transporters, transferrin receptor (TfR) and divalent metal transporter‐1 (DMT‐1). We studied the localization of IRPs, their change in expression during perinatal development, and their relationship to TfR and DMT‐1 in rat brain between postnatal days (PND) 5 and 15. Twelve‐micron frozen coronal sections of fixed brain tissue were obtained from iron‐sufficient Sprague‐Dawley rat pups on PND 5, 10, and 15, and were visualized at 20 to 1,000× light microscopy for diaminobenzidine activity after incubation with specific primary IRP‐1, IRP‐2, DMT‐1, and TfR antibodies and a universal biotinylated secondary and tertiary antibody system. IRP and transport protein expression increased in parallel over time. IRP1, IRP2, and DMT‐1 were partially expressed in the choroid plexus epithelial cells at PND 5 and 10, and fully expressed at PND 15. The cerebral blood vessels and ependymal cells strongly expressed IRP1, IRP2, and DMT‐1 as early as PND 5. Substantive TfR staining was not seen in the choroid plexus or ependyma until PND 15. Glial and neuronal expression of IRP1, IRP2, DMT‐1, and TfR in cortex, hippocampal subareas and striatum increased over time, but showed variability in cell number and intensity of expression based on brain region, cell type, and age. These developmental changes in IRP and transporter expression suggest potentially different time periods of brain structure vulnerability to iron deficiency or iron overload. © 2002 Wiley‐Liss, Inc.
Extracellular proteolysis in brain injury and inflammation: Role for plasminogen activators and matrix metalloproteinases
Authors: Lo Eng H. , Wang Xiaoying , Cuzner M. Louise
Published: October 2002

The role of intracellular proteases (e.g., calpains and caspases) in the pathophysiology of neuronal cell death has been extensively investigated. More recently, accumulating data have suggested that extracellular proteolysis also plays a critical role. The two major systems that modify the extracellular matrix in brain are the plasminogen activator (PA) and matrix metalloproteinase (MMP) axes. This Mini‐Review delineates major pathways of PA and MMP action after stroke, brain trauma, and chronic inflammation. Deleterious effects include the disruption of blood–brain barrier integrity, amplification of inflammatory infiltrates, demyelination, and possibly interruption of cell–cell and cell–matrix interactions that may trigger cell death. In contrast, PA‐MMP actions may contribute to extracellular proteolysis that mediates parenchymal and angiogenic recovery after brain injury. As the mechanisms of deleterious vs. potentially beneficial PA and MMP actions become better defined, it is hoped that new therapeutic targets will emerge for ameliorating the sequelae of brain injury and inflammation. © 2002 Wiley‐Liss, Inc.
The integrin family of cell adhesion molecules has multiple functions within the CNS
Authors: Milner Richard , Campbell Iain L.
Published: October 2002

Integrins comprise a large family of cell adhesion molecules that mediate interactions between the extracellular environment and the cytoplasm. During the last decade, analysis of the expression and function of these molecules has revealed that integrins regulate many aspects of cell behavior including cell death, proliferation, migration, and differentiation. Within the central nervous system (CNS), most of the early studies focused on the role of integrins in mediating adhesive and migratory events in two distinct processes: neural development and CNS inflammation. Interestingly, recent analysis of transgenic mice has provided some surprising results regarding the role of integrins in neural development. Furthermore, a large body of evidence now supports the idea that in addition to these well‐described functions, integrins play multiple roles in the CNS, both during development and in the adult in areas as diverse as synaptogenesis, activation of microglia, and stabilization of the endothelium and blood‐brain barrier. Many excellent reviews have addressed the contribution of integrins in mediating leukocyte extravasation during CNS inflammation. This review will focus on recently emerging evidence of novel and diverse roles of integrins and their ligands in the CNS during development and in the adult, in health and disease. © 2002 Wiley‐Liss, Inc.
Trust as a mediator of the relationship between organizational justice and work outcomes: test of a social exchange model
Authors: Aryee Samuel , Budhwar Pawan S. , Chen Zhen Xiong
Published: October 2002

Data obtained from full‐time employees of a public sector organization in India were used to test a social exchange model of employee work attitudes and behaviors. LISREL results revealed that whereas the three organizational justice dimensions (distributive, procedural and interactional) were related to trust in organization only interactional justice was related to trust in supervisor. The results further revealed that relative to the hypothesized fully mediated model a partially mediated model better fitted the data. Trust in organization partially mediated the relationship between distributive and procedural justice and the work attitudes of job satisfaction, turnover intentions, and organizational commitment but fully mediated the relationship between interactional justice and these work attitudes. In contrast, trust in supervisor fully mediated the relationship between interactional justice and the work behaviors of task performance and the individually‐ and organizationally‐oriented dimensions of citizenship behavior. Copyright © 2002 John Wiley & Sons, Ltd.
Synoptic climatology of major floods in the Negev Desert, Israel
Authors: Kahana Ron , Ziv Baruch , Enzel Yehouda , Dayan Uri
Published: October 2002

This study examines the extent to which the floods in the Negev Desert, an area that constitutes the southern half of Israel, are not the outcome of purely local weather conditions but are, rather, the result of distinct synoptic‐scale events. This was done through compiling and analysing a hydro‐climatological database of all the major floods in the Negev, and then categorizing them manually into synoptic types that cause the major floods.

The type analysis is based on the US National Meteorological Center data sets with 2.5° × 2.5° resolution analysed by GrADS. Data were compiled and studied for 52 floods for the period 1965–94, with peak discharge above the magnitude of 5 year recurrence intervals (RI > 5 years) in at least one drainage basin.

Distinct extreme synoptic patterns are indeed associated with 42 of the 52 floods. They were grouped into four synoptic types, two of which were associated with 37 events: (a) an active Red Sea trough, defined as a surface trough extending from East Africa through the Red Sea toward the eastern Mediterranean, accompanied by a pronounced trough at the 500 hPa level over eastern Egypt: (b) a Syrian low, defined as a well‐developed Mediterranean cyclone accompanied by a pronounced upper‐level trough, both located over Syria. Each of the four synoptic types has its own evolution course, and a unique seasonal and spatial distribution of its associated flooded basins.

These findings imply that the major floods in the Negev can be considered as signatures of exceptional synoptic‐scale evolutions, and that major floods reflect extreme climatic events. Our results indicate that it is possible to use a set of dynamic and thermodynamic variables for predicting the occurrence and location of major flash floods. Copyright © 2002 Royal Meteorological Society.
Evaluating Antarctic sea ice variability and its teleconnections in global climate models
Authors: Liu Jiping , Martinson Douglas G. , Yuan Xiaojun , Rind David
Published: October 2002

This study evaluates simulated Antarctic sea ice edge (SIE) variability and its teleconnections in three global coupled climate models (GISS, NCAR and GFDL) against the observations. All models do a reasonable job in simulating the seasonal advance and retreat of the Antarctic sea ice fields. The simulated GISS and NCAR SIE distributions are in agreement with observations in summer and autumn, whereas the GFDL model does best in spring and winter. A common problem is the poor simulation of the observed SIE in the Weddell Sea. All models are not particularly good at simulating the observed regionally varying SIE trends. A comparison of dominant empirical orthogonal function modes of surface air temperature (SAT) variability in each model associated with observed modes show that the models generally capture features of the more prominent covarying spatial patterns such as an El Niño–southern oscillation (ENSO)‐like pattern in the tropical Pacific.

The simulated teleconnection patterns between detrended Antarctic SIE anomalies and detrended global SAT anomalies in each model are evaluated for comparison with observed teleconnection patterns. All models capture the ENSO‐like phenomenon to some degree. Also, the GISS and NCAR models capture the Antarctic dipole pattern and meridional banding structure through the Pacific. The Antarctic SIE regions showing the strongest extrapolar teleconnections differ among the models and between the models and observations. Almost all models miss the observed polar–extrapolar teleconnections in the central Indian, western extreme of the tropical and southern Pacific, and over the tropical continents. Copyright © 2002 Royal Meteorological Society.
Formation and reorientation of structure in the surge‐type glacier Kongsvegen, Svalbard
Authors: Woodward John , Murray Tavi , McCaig Andrew
Published: October 2002

Kongsvegen, a surge‐type glacier in Spitsbergen, Svalbard, shares a tide‐water margin with the glacier Kronebreen. The complex has been in retreat since a surge advance of Kongsvegen around 1948. The surface of Kongsvegen displays suites of deformational structures highlighted by debris‐rich folia. These structures are melting out to form a network of sediment ridges in the grounded terminal area. The structures are also visible in a marginal, 1 km long, 5–20 m high cliff‐face at the terminus. Current models for the evolution of deformational structures at Kongsvegen divide the structures into suites based on their orientation and dip, before assigning a mechanism for genesis based on structure geometry. Interpretation of aerial photographs and field mapping of surface structures suggest that many structures were reorientated or advected during the surge. We suggest that many of the deformational structures highlighted by debris‐rich folia represent reorientated, sediment‐filled crevasses. Some evidence of thrusting is apparent but the process is not as ubiquitous as previously suggested. Many deformational structures also appear to have been offset by more recent structures. Mechanisms of structural development must, therefore, be considered within the context of distinct stages of glacier flow dynamics and multiple surge episodes. Furthermore, evidence for thrusting and folding within the glacier systems of Svalbard has been used as the basis for interpreting Quaternary glacial landforms in the UK. The findings of this paper, therefore, have implications for interpretations of the Quaternary record. Copyright © 2002 John Wiley & Sons, Ltd.
Surface‐enhanced Raman scattering of 3‐phenylpropionic acid (hydrocinnamic acid)
Authors: Castro J. L. , López Ramírez M. R. , López Tocón I. , Otero J. C.
Published: October 2002

Raman and surface‐enhanced Raman scattering (SERS) spectra of 3‐phenylpropionic acid on silver colloids at several concentrations and pH values were recorded. The analysis of the spectra indicated that 3‐phenylpropionic acid links to the metal through its carboxylate group, keeping the aromatic ring almost perpendicular to the surface. Moreover, the acid undergoes an α, β‐dehydrogenation in some extension in such a way that the recorded SERS is the result of the competitive adsorption of 3‐phenylpropionic and trans‐cinnamic acids. Likewise, the contribution of the charge‐transfer mechanism to the enhancement of the SERS of 3‐phenylpropionic acid was estimated, making evident its important participation in the enhancement of modes 6a, 9a and 8a. Copyright © 2002 John Wiley & Sons, Ltd.
Studies on ferroelectric perovskites and Bi‐layered compounds using micro‐Raman spectroscopy
Authors: Dobal P. S. , Katiyar R. S.
Published: October 2002

This paper provides a review of a systematic micro‐Raman scattering study on various lead‐ and barium‐based ABO3 perovskites (A = Pb, La, Ba, Sr, Ce, Gd, Nd and B = Ti, Zr), Aurivillius‐type Bi‐layered compounds (SrBi2Ta2O9, Bi4Ti3O12) and their solid solutions useful in a broad range of device applications. Various factors that influence the material properties such as particle size, stresses, stoichiometry, compositional homogeneity and their effects on phase transition were investigated. The processing conditions, A‐ and B‐site substitution, size‐dependent Raman spectra and the structure–property correlations are discussed in the bulk, thin film and nano‐crystalline forms of these materials. A film thickness dependence stress study on lead titanate (PT) and lead zirconate titanate (PZT) films indicated that the nature of stress depends strongly on the lattice parameters of the film and substrate. The size effect was found to decrease the ferroelectric transition temperature in lead‐based perovskite materials. Both ionic charge and radii induced changes in the Raman spectra of A‐ and B‐site substituted perovskites and layered compounds were studied. A‐site substitution in strontium bismuth tantalite (SBT) was found to induce a relatively linear variation of transition temperature compared with the B‐site substituted SBT. Raman spectra of layered compounds and their solid solutions exhibited a strong dependence on dopants resulting in structural modifications. Copyright © 2002 John Wiley & Sons, Ltd.
Outsourcing: a core or non‐core strategic management decision?
Authors: Heikkilä Jussi , Cordon Carlos
Published: October 2002

Practicing managers often use the idea of core competence as one of the principal guidelines for making decisions about outsourcing. Managers of large corporations commonly support their outsourcing decisions with the familiar argument that ‘We keep core competences in‐house, and we outsource non‐core activities’.

This paper questions the usefulness of the ‘non‐core competence’ concept for practical decision making. It reviews and discusses a comprehensive list of drivers for outsourcing decisions as well as the potential risks related to outsourcing initiatives.

Instead of taking the simplistic ‘core or non‐core’ approach, the paper suggests a more creative way to evaluate a larger variety of competencies. The business contexts of four successful companies are described and several examples of their outsourcing/insourcing decisions are presented.

Examples show that poor implementation undermines decisions that are based on even the most imaginative definition of competence structures. Successful outsourcing depends on managing the outsourcing relationship well after the decision is made.

Copyright © 2002 John Wiley & Sons, Ltd.
The rumen digestion of dry matter, nitrogen and cell wall constituents of the pods of Leucaena leucocephala and some Acacia species
Authors: Ngwa A T , Nsahlai I V , Bonsi M L K
Published: October 2002

The disappearance of dry matter (DM), nitrogen and cell wall constituents of the pods of Leucaena leucocephaia and some Acacia species incubated in the rumen of Jersey cattle was studied. The chemical compositions of the pods (seeds + husks), seeds and husks were examined separately. Amino acid and lipid analyses were limited to the pods and seeds, while mineral and tannin analyses were done on the pods alone. The seeds had higher crude protein (CP) contents than the pods, with values ranging from 200 to 300 g CP kg−1 DM. The Leucaena pods and seeds had higher (p > 0.001) CP contents than the Acacia pods and seeds. The neutral detergent fibre concentrations in the husks were higher than in the pods and seeds with the pods of A erioloba having the highest and those of A nilotica the lowest values. These values were highly influenced by the seed/husk ratio. A sieberiana and Leucaena had the highest and lowest concentrations of condensed tannins respectively. The pods of A tortilis and A karoo were particularly rich in macro‐ and micro‐minerals, while the others contained sufficient quantities that could contribute substantially to the dietary requirements of small ruminants. The amino acid concentrations differed significantly (p < 0.001) among the pods, with the Leucaena pods having the highest concentrations. The Leucaena pods and seeds also had higher (p < 0.001) lipid contents than the Acacia pods and seeds. Dry matter and nitrogen degradabilities were higher (p < 0.001) for the pods of A nilotica and A sieberiana, while A karoo had the lowest values. The cell wall constituents of the pods of A tortilis and A erioloba were the most and the least susceptible to microbial degradation respectively. The rates of degradation of the fibre fractions as well as the lag times were similar (p > 0.05) among the pods. The results show that these pods can serve as a valuable source of nitrogen and minerals for ruminants fed roughage‐based diets.

© 2001 Society of Chemical Industry