bluuebunny/crossref_metadata_2025_split huggingface dataset:
Explant pathology study of decellularized carotid artery vascular grafts
Authors: Hilbert Stephen L. , Boerboom Lawrence E. , Livesey Stephen A. , Ferrans Victor J. 
Published: March 2004

AbstractThe purpose of this study was to evaluate the morphologic findings in small‐diameter freeze‐dried decellularized carotid artery grafts implanted in goats as carotid artery interposition grafts for 6–7 months. Unimplanted decellularized carotid artery grafts did not contain intact cells; however, remnants of smooth muscle cells were present in the media. The extracellular matrix was well preserved. All decellularized grafts were patent at explant, without significant dimensional changes or aneurysm formation. Their luminal surfaces were lined by a thin neointima, consisting of myofibroblasts, collagen, and a discontinuous layer of endothelial cells. Histologic evidence of calcification within the explants was not observed; however, electron microscopy showed calcification of minute remnants of cell membranes. Inflammatory cells were not present in the graft wall. Host cell migration was greatest in the adventitia along the length of the graft. Migration of host cells into the media was more apparent close to the anastomoses, forming cellular nests rich in extracellular proteoglycans, whereas cell migration into areas subjacent to the lumen was minimal. Ingrowth of host blood vessels was not observed. These results demonstrate satisfactory structural and morphologic features of a decellularized carotid artery small‐diameter graft implanted for up to 7 months. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res 69A: 197–204, 2004
Preformed grafts of porcine small intestine submucosa (SIS) for bridging segmental bone defects
Authors: Moore Douglas C. , Pedrozo Hugo A. , Crisco Joseph J. , Ehrlich Michael G. 
Published: March 2004

AbstractPrevious studies suggest that fresh, morselized porcine small intestine submucosa (SIS) may have promise in the treatment of large bone defects. This study evaluated the bone regenerative potential of preformed tubular SIS grafts, designed to provide a scaffold for regeneration of diaphyseal bone. Critical length segmental defects in the femurs of male rats were either left unfilled (n = 11) or filled with morselized cancellous bone (n = 12), or spanned with intramedullary tubes (n = 12) or periosteal sleeves (n = 12) fabricated from SIS. All of the animals were euthanized 12 weeks postoperatively. Healing was assessed with biweekly radiographs, routine histology, and mechanical testing. Copious new bone formed in the defects of all of the animals treated with cancellous bone; 10 of the 12 animals in that group had healed their defects. In contrast, no new bone was formed in the defects left unfilled or treated with SIS; only fibrous tissue was found. In both of the SIS‐treated groups, the SIS persisted at twelve weeks. The cellular response to the SIS involved a mild mononuclear infiltrate in the loose or delaminated superficial layers of the tubes and sleeves, with few cells in the deeper layers. The results of this study cast doubt on the ability of SIS to support or stimulate growth of bone across a critical length segmental bone defect. Additional work will be required to determine whether our results reflect the protocols used to prepare and fabricate the SIS grafts used in the study or the inherent inability of SIS to support new bone growth. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res 69A: 259–266, 2004
Laminin‐5‐enriched extracellular matrix accelerates angiogenesis and neovascularization in association with ePTFE
Authors: Kidd Kameha R. , Williams Stuart K. 
Published: March 2004

AbstractThe performance of biomedical implant devices is often limited by inappropriate tissue responses associated with synthetic materials used in device construction. Adverse healing responses, in particular the lack of an extensive vascular supply in the peri‐implant tissue, are believed to lead to the ultimate failure of many of these medical devices. Accelerated formation of new blood vessels in the peri‐implant tissue and within porous polymeric implants is hypothesized to improve the performance of such biomedical implant devices. The current study evaluated the use of cell‐mediated, extracellular matrix modification of expanded polytetrafluoroethylene (ePTFE) to increase vessel growth in peri‐implant tissue and within the pores of the implants. Discs of ePTFE were modified through cell‐mediated matrix deposition using epithelial and endothelial cell lines with variable deposition of collagen types, fibronectin, and laminin types. Cell matrix‐modified discs, Matrigel‐coated discs, and nonmodified discs were implanted in both the adipose and subcutaneous tissues of the rat. Following a 5‐week implant period, samples were removed and evaluated histologically and morphometrically for the presence of blood vessels in the peri‐implant tissue and within the pores of the polymer as well as for the presence of activated macrophages and monocytes. A significantly increased presence of activated macrophages and monocytes was associated only with the samples modified with the matrix from a human microvessel endothelial cell line. Increased vessel density was identified in association with those ePTFE samples modified with either the 804‐G, HaCaT, or II‐4 cell matrices, all of which have extracellular matrices enriched in the protein laminin‐5. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res 69A: 294–304, 2004
Fibroblast response to a controlled nanoenvironment produced by colloidal lithography
Authors: Dalby Matthew J. , Riehle Mathis O. , Sutherland Duncan S. , Agheli Hossein , Curtis Adam S.G. 
Published: March 2004

AbstractIt is thought that by understanding how cells respond to topography, that better tissue engineering may be achievable. An important consideration in the cellular environment is topography. The effects of microtopography have been well documented, but the effects of nanotopography are less well known. Previously, methods of nanofabrication have been costly and time‐consuming, but research by engineers, physicists, and chemists is starting to allow the production of nanostructures using low‐cost techniques. In this report, nanotopography is specifically considered. Controlled patterns of 160 nm high nanocolumns were produced for in vitro cell culture using colloidal lithography. By studying cell adhesion with time and cytoskeletal (actin, tubulin, and vimentin) maturity, insight has been gained as to how fibroblasts adhere to these nanofeatures. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res 69A: 314–322, 2004
Long‐term regeneration of the rat sciatic nerve through a biodegradable poly(DL‐lactide‐ϵ‐caprolactone) nerve guide: Tissue reactions with focus on collagen III/IV reformation
Authors: Jansen Koen , Meek Marcel F. , van der Werff John F. A. , van Wachem Pauline B. , van Luyn Marja J. A. 
Published: March 2004

AbstractLong‐term studies on nerve‐guide regeneration are scarce. Therefore, in rats, long‐term (16 months) sciatic nerve regeneration through poly(DL‐lactide‐ϵ‐caprolactone) [poly(DLLA‐ϵ‐CL)] nerve guides was studied and compared with the nonoperated control side. Poly(DLLA‐ϵ‐CL) degradation and possible long‐term foreign body reaction against poly(DLLA‐ϵ‐CL) nerve guides, as well as the distribution of both collagen type III and IV were studied. In vivo poly(DLLA‐ϵ‐CL) studies have been performed before but not for such long time points; also, a detailed analysis of collagen III/IV has not been presented before. The results demonstrate that biodegradable poly(DLLA‐ϵ‐CL) nerve guides yield good nerve regeneration and collagen III/IV deposition relative to the anatomy of the control side. Regenerated nerve showed almost similar collagen type III/IV distribution patterns as compared with the nonoperated control side, although the delineation of matrix was clearer in the control side. The relative amount of collagen III and IV immunostaining in nerve cross‐sections did not, however, differ between the control nerve tissue and the operated side after 16 months. After 16 months of implantation, however, some very small fragments of biomaterial could still be found on the edge of the epineurium of the regenerated nerve, indicating remnants of a secondary foreign body reaction. The biomaterial fragments and foreign body reaction did not influence the nerve regeneration process after 16 months. Biodegradable poly(DLLA‐ϵ‐CL) nerve guides are useful for long‐term bridging of short peripheral nerve gaps. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res 69A: 334–341, 2004
Comparison of environmental scanning electron microscopy with high vacuum scanning electron microscopy as applied to the assessment of cell morphology
Authors: McKinlay Karen J. , Allison Francis J. , Scotchford Colin A. , Grant David M. , Oliver James M. , King John R. , Wood John V. , Brown Paul D. 
Published: March 2004

AbstractThe efficacy of conventional high vacuum scanning electron microscopy (SEM), environmental SEM (ESEM), and confocal laser scanning microscopy techniques in the assessment of cell–material interactions is compared. Specific attention is given to the application of these techniques in the assessment of the early morphological response of human osteoblast‐like cells cultured on titanium dioxide. The processing of cells cultured for conventional high vacuum SEM leads to the loss of morphological features that are retained when using ESEM. The use of cytoskeletal labeling, viewed with confocal laser scanning microscopy, in conjunction with ESEM gives an indication of the changes to cell morphology as a consequence of incubation time in response to interactions at the biological/material interface. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res 69A: 359–366, 2004
Bone formation using novel interconnected porous calcium hydroxyapatite ceramic hybridized with cultured marrow stromal stem cells derived from Green rat
Authors: Ito Yoshiyuki , Tanaka Nobuhiro , Fujimoto Yoshinori , Yasunaga Yuji , Ishida Osamu , Agung Muhammad , Ochi Mitsuo 
Published: March 2004

AbstractThe clinical use of cultured marrow stromal stem cells (MSCs) has recently attracted attention in the field of tissue engineering. For the clinical use of the MSCs, a prominent scaffold is needed. A scaffold hybridized with MSCs is transformed into a “bioactive bone substitute,” and this provides good osteoconduction. In this study, a novel calcium hydroxyapatite ceramic with an interconnected porous structure (IP‐CHA) was used as a scaffold. MSCs were harvested from Green rats containing Green Fluorescent Protein (GFP), and then these hybrids were implanted into the tibias of Sprague–Dawley rats. The purposes of this study were to examine the osteogenic ability of these hybrids without coculture, and to evaluate whether the resulting bone formation originated from the grafted MSCs or the recipient's cells. The hybridized group showed excellent bone formation compared with the IP‐CHA‐only implant group. Observation of the implanted MSCs revealed that they survived 8 weeks after surgery, and differentiated into osteoblast‐like cells, thus providing bone formation. This implantation of the MSCs/IP‐CHA composite provides excellent osteoconduction, and is expected to have extensive clinical applications. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res 69A: 454–461, 2004
Is telomere erosion a mechanism of species extinction?
Authors: Stindl Reinhard 
Published: March 2004

AbstractAccording to the fossil record, 99.9% of all species that have ever lived on Earth have disappeared. However, only about 4% died out during the five mass extinction events, whereas it seems that the majority of species vanished without any signs of significant earthbound or extraterrestrial physical threats. Clearly, biological extinction mechanisms are by far the most important, but they are subject to serious limitations concerning the worldwide disappearance of species. In view of that, species‐inherent mechanisms, which could lead to the worldwide destabilization of a population, might be worth reconsideration. Telomeres, the protective caps of chromosome ends, and the enzyme telomerase have been well preserved in plants and animals during evolution. In the absence of telomerase activity, telomeric DNA has been shown to shorten every time a cell divides. The concept of a mitotic clock based on the gradual erosion of telomeres is now generally accepted and has been confirmed in numerous plants and animals. Chromosomal rearrangements are the hallmarks of two completely different biological phenomena, cancer and speciation. In premalignant cells, gradual telomere erosion beyond a critical threshold is a well‐known inducer of chromosomal instability. The species clock hypothesis, as presented here, is based on the idea of a tiny loss of mean telomere length per generation. This mechanism would not rapidly endanger the survival of a particular species. Yet, after many thousands of generations, critically short telomeres could lead to the weakening and even the extinction of old species and would simultaneously create the unstable chromosomal environment that might result in the origination of new species. J. Exp. Zool. (Mol. Dev. Evol.) 302B: 111–120, 2004. © 2004 Wiley‐Liss, Inc.
Geographic variability in expression of the sex‐linked AAT–1 gene of the bell‐ring frog, Buergeria buergeri
Authors: Sumida Masayuki , Ohta Shigeru , Atsumi Shigeru , Fujii Tamotsu 
Published: March 2004

AbstractCytological observation and artificial crossing experiments were used to examine the geographic differences in the sex‐determining mechanism and mode of inheritance of the sex‐linked AAT–1 gene in the bell‐ring frog, Buergeria buergeri. The AAT–1 phenotypes were also examined by allozyme analysis using field‐caught females and males collected from 19 populations from the Honshu, Shikoku, and Kyushu islands of Japan, in order to comprehensively elucidate the geographic variability in the expression of the sex‐linked AAT–1 gene of B. buergeri. The results showed that the Aomori population of B. buergeri from the northern end of Honshu was female heterogametic in sex determination, that chromosome No. VII was a sex chromosome of the ZZ/ZW type, and that the sex‐linked AAT–1 gene was expressed on both the Z and W chromosomes. This mode of AAT–1 expression in the Aomori population was different from that in the Hiroshima population from western Honshu, in which the AAT–1 gene was expressed on the Z chromosome but not on the W chromosome. The results also showed that there was no differentiation among populations in the expression of the AAT–1 genes on the Z chromosome, whereas two populations, the Hiroshima and Aomori frogs, exhibited distinct modes of expression of the AAT–1 gene on the W chromosome. These two modes of expression may be widely distributed in western and eastern Japan, and coexist in the central part of Honshu. J. Exp. Zool. (Mol. Dev. Evol.) 302B: 182–194, 2004. © 2004 Wiley‐Liss, Inc.
Comparative genomic analysis of vertebrate Hox3 and Hox4 genes
Authors: Hadrys Thorsten , Prince Victoria , Hunter Michael , Baker Robert , Rinkwitz Silke 
Published: March 2004

AbstractWe used a comparative genomic approach to identify putative cis‐acting regulatory sequences of the zebrafish hoxb3a and hoxb4a genes. We aligned genomic sequences spanning the clustered Hoxb1 to Hoxb5 genes from pufferfish, mice, and humans with the zebrafish hoxba and hoxbb cluster sequences. We identified multiple blocks of conserved sequences in non‐coding regions within and surrounding the Hoxb3/b4 gene locus; a subset of these blocks are conserved in the zebrafish hoxbb cluster, despite loss of hoxb3/b4 genes. Overall, we find that the architecture of the Hoxb3/b4 loci and of the conserved sequence elements is very similar in teleosts and mammals. Our analyses also revealed two alternative transcripts of the zebrafish hoxb3a gene and an exon sequence unusually located 10 kb upstream of adjacent hoxb4a; an equivalent murine Hoxb3 exon has not yet been confirmed. We show that many of the Hoxb3/b4 conserved non‐coding sequences correlate with functional neural enhancers previously described in the mouse. Further, within the conserved non‐coding sequences we have identified binding sites for transcription factors, including Kreisler/Valentino, Krox20, Hox, and Pbx, some of which had not been previously described for the mouse. Finally, we demonstrate that the regulatory sequences of zebrafish hoxa3a are divergent with respect to the mouse ortholog Hoxa3, or the paralog hoxb3a. Despite limited conservation of regulatory sequences, zebrafish hoxa3a and hoxb3a genes share very similar expression profiles. J. Exp. Zool. (Mol. Dev. Evol.) 302B: 147–164, 2004. © 2004 Wiley‐Liss, Inc.
It's “juxta” potassium channel!
Authors: Rasband Matthew N. 
Published: March 2004

AbstractNeuronal excitability depends on the appropriate expression and localization of ion channels. Juxtaparanodal Kv1 channels have been used as a model to study the role of neuroglial interactions in regulating the expression and localization of channels in myelinated axons. Recent advances in our understanding of the composition of juxtaparanodal Kv1 channel protein complexes as well as the cellular and molecular mechanisms underlying their localization at juxtaparanodes are discussed. © 2004 Wiley‐Liss, Inc.
Systemic administration of N‐acetylcysteine protects dopaminergic neurons against 6‐hydroxydopamine‐induced degeneration
Authors: Muñoz Ana M. , Rey Pablo , Soto‐Otero Ramon , Guerra Maria J. , Labandeira‐Garcia Jose L. 
Published: March 2004

AbstractThe results of several in vitro studies have shown that cysteine prodrugs, particularly N‐acetylcysteine, are effective antioxidants that increase the survival of dopaminergic neurons. N‐acetylcysteine can be systemically administered to deliver cysteine to the brain and is of potential use for providing neuroprotection in the treatment of Parkinson's disease. However, it has also been reported that an excess of cysteine may induce neurotoxicity. In the present study, we injected adult rats intrastriatally with 2.5 μl of 6‐hydroxydopamine (7.5 μg) and N‐acetylcysteine (240 mM) or cysteine (240 mM) or intraventricularly with 6‐hydroxydopamine (200 μg) and subcutaneously with N‐acetylcysteine (10 and 100 mg/kg). We studied the effects of these compounds on both the nigrostriatal dopaminergic terminals and the surrounding striatal tissue. The tissue was stained with fluoro‐jade (a marker of neuronal degeneration) and processed by immunohistochemistry to detect tyrosine hydroxylase, neuronal and glial markers, and the stress protein heme‐oxygenase‐1. After intrastriatal injection, both cysteine and N‐acetylcysteine had clear neuroprotective effects on the striatal dopaminergic terminals, but also led to neuronal degeneration (as revealed by fluoro‐jade staining) and astroglial and microglial activation, as well as intense induction of heme‐oxygenase‐1 in astrocytes and microglial cells. Subcutaneous administration of N‐acetylcysteine also induced significant reduction of the dopaminergic lesion (about 30% reduction). However, we did not observe appreciable N‐acetylcysteine‐induced fluoro‐jade labeling in striatal neurons or any of the above‐mentioned changes in striatal glial cells. The results suggest that low doses of cysteine prodrugs may be useful neuroprotectors in the treatment of Parkinson's disease. © 2004 Wiley‐Liss, Inc.
Corrosion behavior of steel in Chengdao offshore oil exploitation area
Authors: Li Y. , Hou B. , Li H. , Zhang J. 
Published: March 2004

AbstractFrom September 1992 to September 1995, the corrosion behavior of three marine steels was studied in Chengdao offshore area by means of individually and electro‐connectedly hanging plates in order to provide data for anticorrosion design of oil‐exploitation structures there.The variation trend of corrosion rate with exposure time showed that the variation curves and degrees of three steels were generally identical and had nothing to do with the exposure time. The whole change trend of corrosion rates in three years showed that the corrosion rates of 20# steel were nearly identical in different positions, each of which was a little lower than that of 16 Mn steel specimens in corresponding positions, also was lower than that of A3 steel specimens in tidal zone and immersion zone. Although 20# steel corroded rapidly at first, its corrosion rate has a decreasing trend in the long‐term service. Therefore, 20# steel is feasible to be applied for a long time in various marine zones, especially nearby the low tidal line and immersion zone. The results of A3 steel, 16 Mn steel and 20# steel by means of electrically connected hanging plate in three years indicated that the corrosion of the steel specimens in the splash zone was the most severe as the result of dry‐wet cycle and macrocell effect. Specimens in the other positions corroded mildly, and that in tidal zone corroded most slowly. The corrosion rate of 20# steel was the highest among the three steels in the test, and the corrosion rates of A3 steel and 16 Mn steel were identical on the whole. When the specimens were hanged electro‐connectedly, the macrocell effect generally tended to increase with exposure time. The highest corrosion rate of A3 steel in the splash zone in the three years was about 0.278 mm/a, while that of 16 Mn steel was about 0.321 mm/a, and that of 20# steel was 0.330 mm/a or so. In contrast, the corrosion rate of the steels in the tidal zone was the lowest in three years, which were 0.052 mm/a (A3 steel), 0.048 mm/a (16 Mn steel) and 0.040 mm/a (20# steel).
The influence of Metal Dusting on gas reactions
Authors: Kempen A. T. W. , van Wortel J. C. 
Published: March 2004

AbstractGas composition analysis measurements have been performed in the outlet gas stream of a laboratory metal dusting test furnace in order to study the influence of metal dusting on gas reactions. This analysis has shown that carbon deposition is associated with metal dusting, i.e. the material most severely attacked by metal dusting, catalyses the formation of carbon to the largest extent. Also, metal dusting has not been seen to influence the methanation reactions. A kinetic model has been used to interpret the obtained data with respect to the catalytic activity of several high temperature materials showing that the catalytic activity of the material can vary by orders of magnitude for different reactions.