bluuebunny/crossref_metadata_2025 huggingface dataset:
Reduced adhesion of blood cells to biodegradable polymers by introducing phosphorylcholine moieties
Authors: Iwasaki Yasuhiko , Tojo Yoko , Kurosaki Tomoyuki , Nakabayashi Nobuo
Published: May 2003

Aliphatic polyesters are believed to be good biocompatible polymers for tissue engineering because of their biodegradability and nontoxicity of the degradated products. However, it is necessary to reduce the nonspecific protein adsorption for the application of biodegradable polymers to drug delivery systems or antiadhesive membranes. We hypothesized that novel biodegradable polymers could be synthesized by introducing phosphorylcholine moieties into aliphatic polyesters. The L‐lactide was polymerized in the presence of L‐α‐glycelophosphorylcholine (LGPC) using stannous octate as the catalyst. The molecular weight and crystallinity of poly(L‐lactide) (PLLA)‐based phospholipid polymers (PLLA‐PC) decreased with an increase in the composition of the LGPC unit in the PLLA‐PC. The hydrolysis of the PLLA‐PC was evaluated by soaking the polymer membranes in a phosphate buffer solution. The rate of weight loss was increased with increasing the LGPC units in PLLA‐PC. The surface analysis of the membranes using an X‐ray photoelectron microscope showed the composition of phosphorylcoline groups on the surface. The amount of adsorbed protein and adherent blood cell on the polymer surface was decreased with introducing LGPC unit. PLLA‐PC is a promising biodegradable polymer having blood compatibility and antiadhesive property. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 65A: 164–169, 2003
Coaxial double‐tubular compliant arterial graft prosthesis: Time‐dependent morphogenesis and compliance changes after implantation
Authors: Sonoda Hiromichi , Takamizawa Keiichi , Nakayama Yasuhide , Yasui Hisataka , Matsuda Takehisa
Published: May 2003

In order to reduce the compliance mismatch between the native artery and the artificial graft, we have developed a coaxial double‐tubular compliant graft, using multiply micropored segmented polyurethane (SPU) thin films, which mimics the relationship between the intraluminal pressure and vessel internal diameter (P‐D) of the native artery (termed “J” curve). The graft was coaxially assembled by inserting a high‐compliance inner tube with a heparin‐immobilized photocured gelatin coating layer into a low‐compliance outer tube with a photocured hydrophilic polymer coating layer. Twenty‐eight coaxial double‐tubular compliant grafts were implanted into the canine common carotid arteries in an end‐to‐end fashion for up to 12 months. The overall patency rate was 86% (24/28), and neither rupture nor aneurysmal formation was observed. A neoarterial wall was formed via transanastomotic and transmural tissue ingrowth, resulting in neoarterial tissue formation on the luminal surface and into the intertubular space of the double‐tubular graft, accompanied by mainly myofibroblasts and inflammatory cells in the early stage and endothelialization and collagen‐rich extracellular matrices in the late stage of implantation. Surrounding‐tissue adhesion with the outer tube was prevented by the hydrophilic polymer coating. Although the J curve of the implanted prototype model was preserved 1 month after implantation, the impaired J curves were observed because of tissue ingrowth and tissue adhesion between the outer surface of the inner tube and the surrounding tissues 3 and 6 months after implantation. At 12 months after implantation, however, the implanted coaxial double‐tubular graft exhibited high compliance due to biodegradation of the SPU films. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 65A: 170–181, 2003
Investigation of elasto‐mechanical properties of alginate microcapsules by scanning acoustic microscopy
Authors: Klemenz Albrecht , Schwinger Christian , Brandt Jörg , Kressler Jörg
Published: May 2003

High‐frequency scanning acoustic microscopy (SAM) was used for investigation of acoustic impedance and 3D‐surface topography of full alginate microspheres that act as model of artificial biological cells. Elasto‐mechanical properties of the investigated specimens have been characterized by acoustic impedance. Mean surface impedance of microspheres (diameter: 300 μm) was measured with SAM at 900 MHz with a spatial resolution of 1.5 μm. The sensitivity and reproducibility of SAM had to be increased considerable to receive and quantify signals in the very low impedance region. The multilayer analysis method was used to get quantitative data of acoustic impedance with SAM at a microscopic level. 3D images show details of structure and surface topography. As a reference, bulk measurements were performed on full alginate cylinders. The acoustical impedance and the mechanical stiffness c11 were obtained from mass density and longitudinal ultrasound velocity at 6 MHz. The impedances received with both methods are in close agreement. The results demonstrate the SAM as a powerful tool for characterizing mechano‐elastical parameters as well as surface structure and topography of microspheres with high spatial resolution. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 65A: 237–243, 2003
Loss of chondroitin 6‐sulfate and hyaluronan from failed porcine bioprosthetic valves
Authors: Grande‐Allen K. Jane , Mako W. John , Calabro Anthony , Shi Yaling , Ratliff Norman B. , Vesely Ivan
Published: May 2003

Explanted porcine bioprosthetic valves have a thinned spongiosa, partially because of an overall loss of glycosaminoglycans (GAGs). We measured the concentrations of specific GAG classes in explanted bioprosthetic valves (n = 14, implanted 12.0 ± 4.7 years) compared with glutaraldehyde‐fixed porcine controls. After extraction with NaOH, GAGs were analyzed using either a hexuronic acid assay or fluorophore‐assisted carbohydrate electrophoresis to quantify the individual GAG classes. The total GAG concentration in explants was 198 ± 95 pmol/mg wet weight—93% less than freshly fixed controls. Explants also contained altered proportions of the different GAG classes relative to controls. The proportions of hyaluronan and chondroitin/dermatan‐6‐sulfate were reduced from 39 to 7% and 34 to 18% of total GAGs, respectively. The predominant explant GAG class was chondroitin/dermatan‐4‐sulfate (proportion elevated from 14 to 70%). This GAG is commonly found in the collagen‐associated proteoglycan decorin, which is likely well crosslinked by glutaraldehyde. Chondroitin‐6‐sulfate is commonly found in the water‐ and hyaluronan‐binding proteoglycan versican, which is likely poorly crosslinked. The loss of versican and its associated water‐binding capacity is consistent with the thinned spongiosa. The resultant compromise of hydration, compressive resistance, and viscoelasticity may be responsible for the deterioration of the bioprosthesis in vivo. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 65A: 251–259, 2003
Human serum opsonization of orthopedic biomaterial particles: Protein‐binding and monocyte/macrophage activation in vitro
Authors: Sun Doo‐Hoon , Trindade Michael C. D. , Nakashima Yasuharu , Maloney William J. , Goodman Stuart B. , Schurman David J. , Smith R. Lane
Published: May 2003

Wear particles generated after total joint arthroplasty activate monocyte/macrophages and incite formation of a granulomatous periprosthetic tissue associated with bone loss and implant loosening. This study tested the hypothesis that selective opsonization of orthopedic implant biomaterial wear particles by human serum proteins influences monocyte/macrophage activation. Serum protein binding to metallic, polymeric, and ceramic particles was determined by one‐dimensional sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS‐PAGE). Individual proteins bound to particles were subsequently identified using two‐dimensional SDS‐PAGE, microsequencing techniques, and SWISS‐PROT analysis. Effects of selective protein opsonization on particle‐induced monocyte/macrophage activation were assessed by quantification of interleukin‐1beta, interleukin‐6, and tumor necrosis factor‐alpha release. Results from one‐dimensional gel analyses revealed distinct serum protein‐binding patterns specific for each material tested. Two‐dimensional gel analysis together with amino acid sequencing of the prominent protein species confirmed the presence of albumin and alpha‐1‐antitrypsin bound to all particles tested. In contrast to the metallic particles, apolipoprotein was a major species associated with polymeric particles. Opsonization of PMMA particles with purified preparations of each of the identified proteins showed that albumin significantly enhanced particle‐induced monocyte/macrophage activation. These data confirm orthopedic biomaterial specific binding of human serum proteins and demonstrate that albumin exacerbates particle‐induced monocyte/macrophage activation. Alterations in the chemical and surface properties of orthopedic biomaterials to modulate protein interactions may improve implant longevity. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 65A: 290–298, 2003
Dissolution properties of calcium phosphate granules with different compositions in simulated body fluid
Authors: Monteiro Magna Maria , da Rocha Nilce Carbonel Campos , Rossi Alexandre Malta , de Almeida Soares Gloria
Published: May 2003

Calcium phosphate granules were produced through the calcination of three hydroxyapatites (HAs) at 1150°C: nearly‐stoichiometric (NS‐HA), calcium‐deficient (CD‐HA), and carbonated (Carb‐HA). The characterization using scanning electron microscope (SEM), X‐ray diffraction (XRD), and Fourier‐transformed infrared spectroscopy (FT‐IR) showed that those granules exhibit strong differences in chemical composition, surface texture, and dissolution behavior. Sample dissolution in a simulated body fluid (SBF) and precipitation of a calcium phosphate layer on the granule surface were followed up for 7 days by chemical analysis of calcium content in SBF. After 80‐min reaction, precipitation of new calcium phosphate phases predominates over the dissolution of original granules. Comparison between SEM images and XRD/FT‐IR analysis revealed that the composition of the calcium phosphate layer and its precipitation rate depend on the HA composition and its heat treatment. Calcined carbonated apatite induces the precipitation of an octacalcium phosphate (OPC) layer, whereas a carbonated apatite layer is formed from calcined‐deficient HA. The calcined nearly‐stoichiometric HA exhibits low efficiency in producing carbonated apatite layer. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 65A: 299–305, 2003
Antibacterial characteristics of newly developed amphiphilic lipids and DNA–lipid complexes against bacteria
Authors: Inoue Y. , Fukushima T. , Hayakawa T. , Takeuchi H. , Kaminishi H. , Miyazaki K. , Okahata Y.
Published: May 2003

The purpose of this study was to investigate the antibacterial activity of newly developed amphiphilic lipids and DNA/lipid complexes against two types of oral bacteria and two types of hospital infection bacteria. Nine amphiphilic lipids were quantitatively prepared from the reaction of n‐alkyl alcohol, α‐amino acids, and p‐toluenesulfonic acid. Nine DNA–lipid complexes were prepared by the simple mixing of DNA and amphiphilic lipids. The DNA–lipid complexes were insoluble in water. The antibacterial activity of lipids and DNA–lipid complexes against Porphyromonas gingivalis, Streptococcus mutans, Staphylococcus aureus, and Pseudomonas aeruginosa were evaluated by the disk‐diffusion method. Seven artificial lipids showed antibacterial behavior; in particular, the lipids prepared from n‐decyl alcohol and glycine and from n‐decyl alcohol and L‐alanine showed antibacterial activity against the four bacterial strains used in this study. On the other hand, the lipids of glutamic acid derivatives did not show any antibacterial activity against the four bacteria strains except for the lipid with an n‐octyl group. Five DNA–lipid complexes also had an antibacterial effect. The complex prepared from DNA and glycine decyl ester p‐toluenesulfonic acid salt exhibited antibacterial activity against the four types of bacteria strains. In this study it was found that lipids and DNA–lipid complexes with a mono‐decyl group or a mono‐dodecyl group have more favorable antibacterial activity. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 65A: 203–208, 2003
Preparation, characterization, and in vitro release of gentamicin from coralline hydroxyapatite‐alginate composite microspheres
Authors: Sivakumar M. , Rao K. Panduranga
Published: May 2003

In this work, composite microspheres were prepared from bioactive ceramics such as coralline hydroxyapatite [Ca10(PO4)6(OH)2] granules, a biodegradable polymer, sodium alginate, and an antibiotic, gentamicin. Previously, we have shown a gentamicin release from coralline hydroxyapatite granules–chitosan composite microspheres. In the present investigation, we attempted to prepare composite microspheres containing coralline hydroxyapatite granules and sodium alginate by the dispersion polymerization technique with gentamicin incorporated by absorption method. The crystal structure of the composite microspheres was analyzed using X‐ray powder diffractometer. Fourier transform infrared spectra clearly indicated the presence of per‐acid of sodium alginate, phosphate, and hydroxyl groups in the composite microspheres. Scanning electron micrographs and optical micrographs showed that the composite microspheres were spherical in shape and porous in nature. The particle size of composite microspheres was analyzed, and the average size was found to be 15 microns. The thermal behavior of composite microspheres was studied using thermogravimetric analysis and differential scanning calorimetric analysis. The cumulative in vitro release profile of gentamicin from composite microspheres showed near zero order patterns. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 65A: 222–228, 2003
High‐frequency interferon‐γ‐secreting splenocytes specific for murine cytomegalovirus immediate‐early‐1 (IE‐1) peptide 168YPHFMPTNL176 are insufficient to provide complete protection from viral challenge
Authors: Morley Peter J. , Ertl Peter F. , Sweet Clive
Published: May 2003

Infection of Balb/c mice with murine cytomegalovirus (MCMV) has been used extensively as a model system with which to study host mechanisms of immunity to cytomegaloviruses. In this model, the cytotoxic T‐lymphocyte (CTL) response crucial for clearing infected cells is dominated by CTLs specific for the MCMV nonapeptide 168YPHFMPTNL176 encoded by the immediate‐early 1 (IE‐1) gene. The intradermal injection of plasmid pcDNA89 encoding IE‐1 has been shown to offer some protection from viral challenge. In the present studies, the protective efficacy of immunisation with pcDNA89 given by intradermal injection was compared with particle‐mediated DNA delivery (PMDD) and contrasted with that induced by injection with the K181 MCMV strain and with temperature‐sensitive mutants (tsm) derived from the K181 strain. Modest protection was afforded by pcDNA89 immunisation given by PMDD, but none was observed after intradermal injection. PMDD immunisation induced a frequency of 168YPHFMPTNL176‐specific interferon‐γ (IFN‐γ)‐secreting splenocytes, which was equivalent to that after K181 infection and significantly higher than tsm immunisation. Whereas tsm‐immunised mice were completely protected from MCMV challenge, PMDD‐immunised mice were only weakly protected. Tsm immunisation protected mice completely against challenge with natural isolates having sequence variation in the IE‐1 nonapeptide, while PMDD‐immunised mice were weakly protected from isolates encoding 168YPHFMPTNL176 and were not protected against isolates encoding 168YPHFMPPSL176 or 168YLDFMPPNL176. Thus, while IE‐1‐specific IFN‐γ‐secreting splenocytes do contribute to immunity from MCMV challenge, their presence in isolation is insufficient to provide complete protection and they may not be involved in the protection observed against MCMV isolates having IE‐1 sequence variation. J. Med. Virol. 69:240–250, 2003. © 2003 Wiley‐Liss, Inc.
Quantitative Epstein‐Barr virus (EBV) serology in lung transplant recipients with primary EBV infection and/or post‐transplant lymphoproliferative disease
Authors: Verschuuren Erik , van der Bij Wim , de Boer Wim , Timens Wim , Middeldorp Jaap , The T. Hauw
Published: May 2003

The Epstein‐Barr virus (EBV)‐specific antibody response was studied in lung transplant patients to assess their value in the diagnosis and prognosis of post‐transplant lymphoproliferative disease. Recently developed synthetic peptides representing Epstein‐Barr nuclear antigen‐1 (EBNA‐1), diffuse early antigen (EA(D)), and virus capsid antigen (VCA) were studied in a semiquantitative enzyme‐linked immunosorbent assay (ELISA) to study antibody patterns in 12 seronegative lung transplant patients, of whom four developed a post‐transplant lymphoproliferative disease, and seven seropositive lung transplant patients, all of whom developed a post‐transplant lymphoproliferative disease. Immunoblot technique was used as a control. All 12 EBV‐seronegative patients had a very limited antibody response that was restricted mainly to VCA antibodies. EA(D) antibodies became detectable in only two patients. Antibody response never preceded clinical diagnosis of post‐transplant lymphoproliferative disease in the four EBV‐seronegative patients who developed post‐transplant lymphoproliferative disease. In the seven seropositive lung transplant patients with post‐transplant lymphoproliferative disease, we found a rise in antibody titer in only two patients. Immunoblot analysis confirmed the serological results. In conclusion, EBV‐specific antibody patterns after lung transplantation are highly restricted and variable and of limited value for the diagnosis or prognosis of post‐transplant lymphoproliferative disease. J. Med. Virol. 69:258–266, 2003. © 2003 Wiley‐Liss, Inc.
Transcriptional inactivation of amphotropic murine leukemia virus replication in human cells
Authors: Ploss Martin , Berdel Bianca , Heber Ricarda , Reuss Frank U.
Published: May 2003

Amphotropic murine leukemia virus (MLV) replicates in cells from various mammalian species including humans and is a potential contaminant in MLV vector preparations for human gene transfer studies. Because MLV replication proceeds through an RNA genome that is generated under the control of viral enhancer and promoter elements, vectors were developed that delete such elements during transduction to reduce the generation of replication‐competent virus. It was shown recently that replication of amphotropic MLV in certain human cells is possible without the 75 bp transcription enhancers. It is now demonstrated that enhancer‐independent replication requires functional elements within U3 and is repressed by an extended deletion in the U3 region comprising enhancers, promoter and flanking sequences. It is concluded that the transcriptional inactivation of amphotropic MLV in human cells requires the combined deletion of enhancers and of additional elements in U3. J. Med. Virol. 69:267–272, 2003. © 2003 Wiley‐Liss, Inc.
Molecular investigation of hepatitis E virus infection in patients with acute hepatitis in Kathmandu, Nepal
Authors: Shrestha Santosh Man , Shrestha Shobhana , Tsuda Fumio , Nishizawa Tsutomu , Gotanda Yuhko , Takeda Naokazu , Okamoto Hiroaki
Published: May 2003

One hundred fifty‐four consecutive patients with sporadic acute hepatitis, who were seen at a city hospital in the Kathmandu valley of Nepal in 1997, were studied. IgM antibodies to hepatitis A virus were detected in four patients (3%), IgM antibodies to hepatitis B core in four patients (3%), hepatitis B surface antigen in 20 (13%), and hepatitis C virus RNA in four patients (3%). IgM antibodies to hepatitis E virus (HEV) (anti‐HEV IgM) and HEV RNA were detected in 77 (50%) and 48 (31%), respectively. Consequently, 86 patients (56%) including nine HEV‐viremic patients without anti‐HEV IgM, were diagnosed with hepatitis E. The cause of hepatitis was not known in 53 patients (34%). All 48 HEV RNA‐positive samples were genotyped as 1, and subtyped further as 1a in 17 (35%), 1c in 29 (60%), and mixed infection of 1a and 1c in 2 (4%). A seasonal difference in the prevalence of HEV subtypes was recognized. Before the rainy season (January to July), both 1a and 1c isolates were found: the intrasubtypic difference was up to 9.0% and 1.7%, respectively, in the 412‐nucleotide sequence of open reading frame 2. During the rainy season (August), only 1c isolates (n = 17) with 99.5–100% identity were found; 13 of 17 isolates had the same sequence, being identical to the 3 isolates that emerged at the end of July. These results suggest that a particular HEV 1c strain spread widely during the rainy season and was implicated in a small epidemic in the Kathmandu valley in August 1997. J. Med. Virol. 69:207–214, 2003. © 2003 Wiley‐Liss, Inc.
Co‐circulation of two genotypes of measles virus and mutual change of the prevailing genotypes every few years in Osaka, Japan
Authors: Kubo Hideyuki , Iritani Nobuhiro , Seto Yoshiyuki
Published: May 2003

Genotypes of 44 wild‐type measles virus (MV) strains isolated in Osaka, Japan, during 1997–2001, were determined based on phylogenetic analyses of a 456‐nt 3′ terminal nucleoprotein gene sequence with the reference MV strains designated by the World Health Organization. The wild‐type MV strains were classified into two genotypes, D3 and D5, recognized as indigenous in Japan. Six of 12 strains isolated in 1997 were classified into genotype D3 and the other 6 into D5. Eleven of 13 strains were D3, and 2 were D5 in 1998. There were no measles epidemics, and no strains were isolated in 1999. Nine of 10 strains were genotype D5, and only one was D3 in 2000, and 9 of 9 were D5 in 2001. These results indicate that the wild‐type MV strains classified into genotypes D3 and D5 co‐circulated without the complete change of the MV genotype in Osaka, except in 2001. Furthermore, the prevailing genotype was different between 1998 and 2000–2001. Together with a previous report about MV genotype in this area during 1993–1995, these results suggest that the mutual change of the prevailing wild‐type MV genotypes between D3 and D5 occurs every few years in Osaka, Japan. J. Med. Virol. 69:273–278, 2003. © 2003 Wiley‐Liss, Inc.
Mucosal immunization with inactivated HIV‐1‐capturing nanospheres induces a significant HIV‐1‐specific vaginal antibody response in mice
Authors: Akagi Takami , Kawamura Masaki , Ueno Masamichi , Hiraishi Katsuya , Adachi Masakazu , Serizawa Takeshi , Akashi Mitsuru , Baba Masanori
Published: May 2003

Mucosal secretory IgA is considered to have an important role in the prevention of human immunodeficiency virus type 1 (HIV‐1) transmission through sexual intercourse. Therefore, substances that induce HIV‐1‐specific IgA antibody in the genital tract may become promising candidates for prophylactic vaccine against HIV‐1 infection. We have previously reported that concanavalin A‐immobilized polystyrene nanospheres (Con A‐NS) could efficiently capture HIV‐1 particles and gp120 antigens on their surface and that intravaginal immunization with inactivated HIV‐1‐capturing nanospheres (HIV‐NS) induced vaginal anti‐HIV‐1 IgA antibody in mice. In this study, various strategies for immunization with HIV‐NS were undertaken to induce HIV‐1‐specific IgA response in the mouse genital tract. HIV‐NS were administered intravaginally, orally, intranasally or intraperitoneally to mice. Progesterone treatment enhanced the anti‐HIV‐1 IgA response to intravaginal immunization significantly, but intranasal immunization with HIV‐NS was more effective compared with other immunization routes in terms of vaginal IgA response. In addition, vaginal washes from intranasally immunized mice were capable of neutralizing HIV‐1IIIB. Thus, application of HIV‐NS is a practical approach to promote HIV‐1‐specific IgA response by the vaginal mucosa in the mouse and intranasal appears to be an effective immunization route in this animal model. Intranasal immunization with HIV‐NS should be further pursued for its potential as an HIV‐1 prophylactic vaccine. J. Med. Virol. 69:163–172, 2003. © 2003 Wiley‐Liss, Inc.
Determination of HCV genotype by direct sequence analysis of quantitative PCR products
Authors: Gargiulo Franco , De Francesco Maria Antonia , Pinsi Gabriele , Pollara Caterina , Terlenghi Luigina , Perandin Francesca , Manca Nino
Published: May 2003

Hepatitis C virus (HCV) genotyping, combined with quantitative evaluation of HCV RNA, may be beneficial for the management of chronic hepatitis C and in the selection of candidates for interferon treatment. In this study, the COBAS AMPLICOR HCV MONITOR™ test, a commercially available quantitative assay for HCV RNA, was used. Amplification products obtained from HCV‐positive cases were subjected to direct sequencing and genotyping based on seven phylogenetically informative regions within the 5′UTR. Results were compared with those obtained by INNO‐LiPA assay. Typing results yielded by both methods were in complete accordance for type and subtype assignment. Twenty‐nine of 500 specimens (5.8%) were unclassifiable and belonged to samples with a titer of <70.000 IU, as determined by quantitative assay. Despite this limitation, the overall gain in efficiency, the low rate of test failure and a better resolution of mixed genotypes all constitute a considerable advantage of this system over the commercial hybridization technique for routine clinical laboratory use. J. Med. Virol. 69:202–206, 2003. © 2003 Wiley‐Liss, Inc.
Inter‐subtype cross‐neutralizing antibodies recognize epitopes on cell‐associated HIV‐1 virions
Authors: Donners Helen , Davis David , Willems Betty , van der Groen Guido
Published: May 2003

HIV‐1 infected individuals with cross‐neutralizing antibodies against primary HIV‐1 isolates belonging to Group M (env A‐H) and O, are identified. To investigate the neutralization‐kinetics of primary isolates with these antibodies, different neutralization assay conditions are compared. Each set is summarized as a/b/c where a is the time in hours for which antibody is incubated with virus, b is the time in hours allowed for virus to absorb to cells, c is the total culture period in days, from the cells' first exposure to virus, before antigen production (peripheral blood mononuclear cells) or number of fluorescent cells (GHOST) are measured. In HIV‐infected individuals, neutralizing antibodies can be detected against a wide range of primary isolates (Group M; A–H and Group O) in PBMC‐assays with short incubation phases (1/2/7 or 1/24/7). If cultures are extended (1/2/14 or 1/24/14), however, neutralization can be lost. In kinetic experiments, neutralization can even be seen without pre‐incubation (a = 0 hr). This study shows that neutralization of primary HIV isolates by cross‐reactive antibodies can continue after the virus has bound to its target cell. This neutralization, however, is not an all or nothing loss in virus infectivity. Most often it leads only to a reduction in viral replication rates. J. Med. Virol. 69:173–181, 2003. © 2003 Wiley‐Liss, Inc.
Crystallization and Morphology of Poly(ethylene 2,6‐naphthalene dicarboxylate) Containing Additives
Authors: Gao Xia , Liu Ruigang , Yu Ying , Jin Manna , Bu Haishan
Published: May 2003

The influence of nucleating agents (AClyn®, Surlyn® and sodium benzoate (SB)) alone and together with nucleating promoter (Ceraflour® 993 and Ceraflour® 991 and poly(1,4‐butylene sebacate)) on the crystallization and morphology of poly(ethylene 2,6‐naphthalene dicarboxylate) (PEN) was investigated by means of differential scanning calorimeter, polarized optical microscopy and small angle light scattering. It was revealed that AClyn, Surlyn and SB effectively accelerate nucleation and crystallization of PEN with increasing the ratio of nucleating agent up to 1 wt.‐%. A combination of nucleating agent and nucleating promoter leads to further increase in crystallization rate at low temperature, but only a slight change at high temperature. Hedrites were obtained in pure PEN and the addition of SB and Ceraflour 993 produces small crystals with poor perfection upon crystallization in high temperature region. When crystallization temperature was below 210 °C, spherulites were observed in pure PEN and also in the samples of PEN/Ceraflour 993 and PEN/SB but with smaller size.

Crystal morphology of PEN crystallized at 240 °C for 40 min.

magnified image

Crystal morphology of PEN crystallized at 240 °C for 40 min.
New electromagnetic bandgap nonlinear coplanar waveguides
Authors: Martín Ferran , Falcone Francisco , Bonache Jordi , Lopetegi Txema , Laso Miguel A. G. , Carreras J. L. , Sorolla Mario
Published: May 2003

In this paper, nonlinear transmission lines (NLTLs) consisting of coplanar waveguides periodically loaded with shunt connected varactor diodes, periodically perturbed by varying the slot width, are studied. To our knowledge, this is the first time that these structures, combining a distributed nonlinearity with an electromagnetic bandgap (EBG), are investigated. A prototype device with a cutoff frequency near 1 GHz and designed to inhibit power transmission within a narrow frequency gap near cutoff has been fabricated. Harmonic balance simulations as well as nonlinear measurements indicate that power transfer to the second harmonic is enhanced if the third harmonic lies within the forbidden gap. The work opens the door to a major design flexibility of NLTL frequency multipliers and phase shifters by adding the EBG concept to the structure. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 37: 397–401, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10929
A wideband meander‐line probe‐fed patch antenna
Authors: Ooi B. L. , Lee C. L.
Published: May 2003

In this paper, the characteristics of a bent meander‐line probe fed patch antenna are investigated. The air‐filled patches are designed at a height of about 9% of the wavelength and the bent meander‐line probe fed antenna is able to achieve an impedance bandwidth of about 31% for a VSWR of less than 2. The four basswoods, which support the microstrip patch, are noticed experimentally to have little effect on the overall performance. The in‐band return loss of the proposed antenna is found experimentally to be better than the recently proposed L‐shaped probe patch antenna. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 37: 401–403, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10930
Characteristics of a compact CPW resonant cell
Authors: Xue Q. , Mo T.‐T. , Shum K. M. , Chan C. H.
Published: May 2003

This paper proposes a novel structure called a compact coplanar waveguide resonant cell (CCRC), which can exhibit slow‐wave and bandstop characteristics by only one single unit. The same pattern has been adopted in the compact microstrip resonant cell (CMRC) as reported previously and here is applied to CPW with both infinite and finite ground planes. Experimental results show quite good agreement with simulations. By alternating the slot width of the CCRC section from that of normal CPW, good transmitting characteristics can be achieved at a passband of low frequency. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 37: 408–410, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10933
T‐coupled circular microstrip antenna with H‐shaped aperture for bandwidth and radiation‐gain improvements
Authors: Liu Ji‐Chyun , Wu Hui Chi , Chiang Meng Shan , Tsou Hsin‐Yi
Published: May 2003

A novel design of a T‐coupled circular microstrip antenna with H‐shaped aperture for bandwidth and radiation gain improvements is presented in this paper. The circular patch determines the certain resonated frequency, the H‐shaped aperture structure is used to obtain a response for the desired (3.7–4.2 GHz) band, and then the T‐coupled feed line enhances the response of the band using the impedance‐matching technique. In addition, the available radiation gain (4.5–5.0 dBi) is also obtained. This design procedure is described and the simulated and experimental results, including frequency response and radiation patterns, are presented and discussed. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 37: 414–417, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10935
Study of a dual‐band packaged patch antenna on a PC card for 5–6 GHz wireless LAN applications
Authors: Kunda V. K. , Ali M. , Sheng‐Hwang Huan , Sittironnarit T.
Published: May 2003

A study of a dual‐band PC card mounted folded microstrip patch antenna is presented for use with a laptop computer. The antenna operates in the wireless local area network (WLAN) bands from 5.15–5.35 GHz and from 5.725–5.825 GHz within 2.5:1 VSWR. Three cases are considered. First, the PC‐card‐mounted antenna is studied without a laptop. Next, it is attached externally to a laptop and its characteristics are analyzed. Finally the antenna is studied as packaged within a laptop. Detailed antenna characteristics, including current distribution, VSWR, radiation pattern, and gain, are given. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 37: 423–428, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10938
Attenuation characteristics of InP/InGaAsP deep‐ridge waveguide turning mirror
Authors: Park Jeong‐Woo , Beak Yongsoon , Song Jung‐Ho , Sim Eun‐Deok , Kim Seong‐Bock , Park Kyung‐Hyun
Published: May 2003

Attenuation of a deep‐ridge waveguide turning mirror is analyzed using a simple overlap integral calculation. According to this analysis, loss of the fabricated mirror was improved by 1.1 dB and uniformity was also improved. Our analysis shows that more reduction of attenuation can be made by using the steep mirror facet through an optimization of the dry etch condition. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 37: 428–431, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10939
An open‐cell layer approach for scattering and radiation
Authors: Chumachenko Vitaliy P.
Published: May 2003

A novel close approximation of a layer surrounding the scatterer which does not reflect outgoing waves is proposed. The layer consists of cells. Inside each cell, the scattered field is expended in terms of waves propagating from the sides of the cell, except the outer one. The realizability and appropriateness of the construction are checked by solving the scattering from circular and square conducting cylinders. The approach has the advantage of simplicity and provides sufficiently accurate results in a wide range of frequencies. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 37: 444–447, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10944
Printed uni‐planar dual‐band monopole antenna
Authors: Fang Chi‐Yin , Chen Hong‐Twu , Wong Kin‐Lu
Published: May 2003

A printed dual‐band monopole antenna suitable for wireless local‐area network (WLAN) applications in the 2.4‐ and 5.2‐GHz bands is presented. The monopole antenna including the ground plane is printed on the same (front) surface of a narrow FR4 substrate (with no metallic portion in the back side of the substrate), which makes it easy to fabricate. In addition, the antenna also showed good radiation characteristics. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 37: 452–454, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10947
An elliptic dielectric resonator antenna designed for circular polarization with single feed
Authors: Kishk Ahmed A.
Published: May 2003

A single‐fed elliptic dielectric resonator antenna is designed for circular polarization. The feed is a coaxial probe chosen with the proper parameters to achieve wideband matching and good circular polarization properties. The analysis is performed numerically using WIPL‐D. The single‐fed DRA achieves 3.5% circular polarization bandwidth and 14% matching bandwidth. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 37: 454–456, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10948
Width and thickness effects of dielectric overlay on even and odd mode resonance frequency of microstrip ring resonator
Authors: Jacob Julie , Nuangnum Chote , Aiyer R. C.
Published: May 2003

The effect of perturbation on even‐ and odd‐mode resonance frequencies of a microstrip ring resonator (MRR) is studied. Overlay of alumina strips with variable width (1 mm to 4 mm) and thickness (0.635 mm to 3.175 mm) are used to perturb the MRR. The change in even‐ and odd‐mode resonance frequencies, due to width of the overlay, is found to be nonlinear. Odd‐mode frequency is observed to be independent of perturbation due to the thickness of the overlay. Even‐mode frequency variations tend to saturate for thickness greater than about four times the substrate height. Based on the experimental results, empirical equations for even‐ and odd‐mode resonance frequencies are reported. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 37: 465–470, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10952
Linking data to electronic records
Authors: Longden Heather
Published: May 2003

Today it is possible to maintain electronic records in a single application in compliance with 21 CFR Part 11. However, most electronic data for a sample in an analytical laboratory is spread across a number of software applications as well as traditional paper systems. This article will examine how it is possible to link both paper and electronic records together in hybrid systems. A case study is used to demonstrate the practical aspects of a totally electronic process. Copyright © 2003 John Wiley & Sons, Ltd.
New day: CQA
Authors: Winchell Terry
Published: May 2003

Many CQA (clinical quality assurance) units were just being formed in the United States in the early 1980s, but are now commonly recognized components of Quality Assurance. CQA units operate in a unique environment when compared to GMP (good manufacturing practice) and GLP (good laboratory practice) units, and have vast responsibilities with regard to the magnitude and constantly changing nature of the clinical research activities they serve. The uniqueness and enormity of this task demands strategically planned activities that are designed to maximize the benefit of each CQA professional on staff. A number of methods are discussed in this article. Increased focus will deliver CQA into a new era of high impact. If properly focused and directed, CQA can serve as a small fulcrum to leverage big change in clinical research. This change is not limited to improved GCP compliance and quality, but can significantly improve company efficiency and profitability as well. Copyright © 2003 John Wiley & Sons, Ltd.
Importance of biotic interactions in large rivers: an experiment with planktivorous fish, dreissenid mussels and zooplankton in the St. Lawrence River
Authors: Thorp James H. , Casper Andrew F.
Published: May 2003

Physical conditions are usually considered pre‐eminent in controlling river plankton, but biotic interactions may be important in slackwater areas. To begin testing this general hypothesis, we conducted a 12‐day, predator–prey experiment in 3500 litre mesh enclosures in a slackwater area of the St. Lawrence River using planktivorous, juvenile yellow perch (Perca flavescens) and Dreissena mussels. Results generally supported our hypotheses that: (1) perch would directly suppress large zooplankton via predation but benefit microzooplankton through indirect interactions; and (2) dreissenids would directly depress rotifer densities via predation and have indirect negative effects on macrozooplankton. Based on gut contents of experimental fish, cladocera were the principal prey of smaller yellow perch (c. 46–50 mm), followed by copepods, ostracods, and rotifers. Larger juvenile perch (c. 67–73 mm) fed almost exclusively on copepods and ostracods. Densities of calanoid copepodids, nauplii, and some cyclopoid copepods (Diacyclops thomasi) were significantly depressed by perch, and adult Eurytemora affinis (99% of adult calanoids) essentially disappeared from fish enclosures. Despite being a favourite prey item of small perch, densities of the small cladoceran Bosmina (Sinobosmina) spp. were significantly higher when fish were present (150% greater than control densities on Day 12). Densities of the very abundant rotifer Polyarthra were >300% greater in fish enclosures than controls by Day 12, and the rotifers Synchaeta and predaceous Ploesoma were significantly more abundant in the presence of perch. Increases in rotifers and cladocera suggest indirect, positive effects of fish related to significantly higher phytoplankton biomass or decreased densities of predaceous copepods. Densities of eight of ten zooplankton groups examined declined significantly when mussels were present, and calanoid copepodids also declined but not significantly. Chlorophyll‐a concentrations were slightly lower in mussel enclosures. This evidence suggests biotic interactions play important roles among potamoplankton in slackwater habitats, but river‐wide implications of these findings require further study. Copyright © 2003 John Wiley & Sons, Ltd.
Macroinvertebrate community structure and function associated with large wood in low gradient streams
Authors: Johnson Lucinda B. , Breneman Dan H. , Richards Carl
Published: May 2003

Large woody debris (wood) plays a number of important roles in forested stream ecosystems. Wood in streams provides habitat and flow refugia for fish and invertebrates, and is a site of biofilm production that serves as food for grazing organisms. Logs added to streams are rapidly colonized by invertebrates, and this habitat alteration is accompanied by changes in community composition and functional processes. A multiple habitat, qualitative sampling approach was employed to evaluate macroinvertebrate communities associated with wood habitats in 71 stream reaches in central Michigan and southeastern Minnesota, two agricultural regions in the midwestern United States. Macroinvertebrate taxa were classified with respect to behaviour (e.g. sprawler, clinger, swimmer), as well as trophic/feeding characteristics. These traits were used to examine community structure as a function of wood abundance and distribution. Although wood is not abundant in these streams and logs are generally small in size, wood is a very important habitat in both Michigan and Minnesota: 86% and 95% of the total taxa encountered at Michigan and Minnesota study sites, respectively, were found in wood habitats. Differences in regional patterns in the distribution of taxa across habitats were observed between Michigan and Minnesota. These are believed to result from differences in the number of habitat types available, and the dominant substrate composition. Local invertebrate diversity increased in Michigan, but not Minnesota, with the presence of wood habitats in streams. The presence of wood at a site increased the average taxa richness by 15 and 10 taxa in Michigan and Minnesota, respectively. Macroinvertebrate behavioural attributes and functional traits associated with wood habitats suggest that community traits may vary due to both local difference in flow and the location of wood in the channel. Copyright © 2003 John Wiley & Sons, Ltd.
Phylogeny, diet, and habitat of an extinct ground sloth from Cuchillo Curá, Neuquén Province, southwest Argentina
Authors: Hofreiter Michael , Betancourt Julio L. , Sbriller Alicia Pelliza , Markgraf Vera , McDonald H. Gregory
Published: May 2003

Advancements in ancient DNA analyses now permit comparative molecular and morphological studies of extinct animal dung commonly preserved in caves of semiarid regions. These new techniques are showcased using a unique dung deposit preserved in a late glacial vizcacha (Lagidiumsp.) midden from a limestone cave in southwestern Argentina (38.5° S). Phylogenetic analyses of the mitochondrial DNA show that the dung originated from a small ground sloth species not yet represented by skeletal material in the region, and not closely related to any of the four previously sequenced extinct and extant sloth species. Analyses of pollen and plant cuticles, as well as analyses of the chloroplast DNA, show that the Cuchillo Curá ground sloth browsed on many of the same herb, grass, and shrub genera common at the site today, and that its habitat was treeless Patagonian scrub-steppe. We envision a day when molecular analyses are used routinely to supplement morphological identifications and possibly to provide a time-lapse view of molecular diversification.
Extending the limits of the Borrobol Tephra to Scandinavia and detection of new early Holocene tephras
Authors: Davies Siwan M. , Wastegård Stefan , Wohlfarth Barbara
Published: May 2003

Analyses of two infilled lakes in Blekinge, southeast Sweden, indicate the presence of at least three tephra horizons of Termination 1 and early Holocene age. Geochemical analyses confirm the presence of the Borrobol Tephra, the Askja Tephra (10,000 14C yr B.P.), and one previously unreported tephra of Icelandic origin. Extending the limits of the Borrobol Tephra to Scandinavia illustrates that this ash is far more widespread than previously realized and is therefore, an important marker horizon for determining the rate and timing of the initial warming at the start of Greenland Interstade 1 (GI-1) within Europe. The relatively unknown Askja Tephra and the newly discovered Hässeldalen Tephra are stratigraphically placed at the Younger Dryas/Preboreal transition. This paper demonstrates the suitability and success associated with the extraction techniques for tracing microtephra horizons in areas distal to volcanic sources.
Millennial-scale climate changes on South Georgia, Southern Ocean
Authors: Rosqvist Gunhild C. , Schuber Pernilla
Published: May 2003

The location of South Georgia (54°S, 36°W) makes it a suitable site for the study of the climatic connections between temperate and polar environments in the Southern Hemisphere. Because the mass balance of the small cirque glaciers on South Georgia primarily responds to changes in summer temperature they can provide records of changes in the South Atlantic Ocean and atmospheric circulation. We use grey scale density, weight-loss-on-ignition, and grain size analyses to show that the proportion of glacially eroded sediments to organic sediments in Block Lake was highly variable during the last 7400 cal yr B.P. We expect that the glacial signal is clearly detectable above noise originating from nonglacial processes and assume that an increase in glacigenic sediment deposition in Block Lake has followed Holocene glacier advances. We interpret proglacial lake sediment sequences in terms of summer climate warming and cooling events. Prominent millennial-scale features include cooling events between 7200 and 7000, 5200 and 4400, and 2400 and 1600 cal yr B.P. and after 1000 cal yr B.P. Comparison with other terrestrial and marine records reveals that the South Georgian record captures all the important changes in Southern Hemisphere Holocene climate. Our results reveal a tentative coupling between climate changes in the South Atlantic and North Atlantic because the documented temperature changes on South Georgia are anti-phased to those in the North Atlantic.