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PubMed2001

Entheses and enthesitis: a histopathologic review and relevance to spondyloarthritides.

There are two types of entheses: fibrous, by Sharpey's fibers in membranous bone, and fibrocartilaginous, on endochondral bone, with discontinuous cement lines at the interface between insertion and bone. The connection of hyaline cartilage to subchondral bone is a kind of fibrocartilaginous enthesis. Fibrocartilages are structurally, chemically, and biomechanically intermediate between tendon and cartilage. Enthesitis is not the sole pathologic feature of spondyloarthritides. Synovitis and subchondral bone marrow changes outside the ligamentous insertions, and cartilage proliferation, are important too. In the subentheseal bone marrow and in the synovium, CD8+ T cells play a central role. Imaging of early changes is better achieved by ultrasonography and even better by magnetic resonance imaging than by radiography. No single immunologic target can be identified. The G1 domain of aggrecan is the best candidate, but this does not apply to fibrous entheses. In these complex pathologic conditions, no single abnormality can thus far be designated as a unique hallmark.

Bone and Bones↗

PubMed2004

Proteoglycans in atherosclerosis and restenosis: key roles for versican.

The proteoglycan versican is one of several extracellular matrix (ECM) molecules that accumulate in lesions of atherosclerosis and restenosis. Its unique structural features create a highly interactive molecule that binds growth factors, enzymes, lipoproteins, and a variety of other ECM components to influence fundamental events involved in vascular disease. Versican is one of the principal genes that is upregulated after vascular injury and is a prominent component in stented and nonstented restenotic lesions. The synthesis of versican is highly regulated by specific growth factors and cytokines and the principal source of versican is the smooth muscle cell. Versican interacts with hyaluronan, a long chain glycosaminoglycan, to create expanded viscoelastic pericellular matrices that are required for arterial smooth muscle cell (ASMC) proliferation and migration. Versican is also prominent in advanced lesions of atherosclerosis, at the borders of lipid-filled necrotic cores as well as at the plaque-thrombus interface, suggesting roles in lipid accumulation, inflammation, and thrombosis. Versican influences the assembly of ECM and controls elastic fiber fibrillogenesis, which is of fundamental importance in ECM remodeling during vascular disease. Collectively, these studies highlight the critical importance of this specific ECM component in atherosclerosis and restenosis.

Aneurysm↗

PubMed1992

Collaboration between unlikely disciplines in the creation of a conceptual framework for nurse-computer interactions.

A unique conceptual framework for the study of nurse-computer interaction was created through the collaboration of two researchers in seemingly diverse fields: nursing informatics and developmental psychology. The framework depicts nurses and computers interacting in a system of mutual influences, exchanging information during a particular task, and proceeding on a developmental trajectory. The conceptual framework can help guide research within nursing informatics and help build a cohesive body of knowledge for the future.

Medical Informatics↗

PubMed1998

Fasciola gigantica: studies of the tegument as a basis for the developments of immunodiagnosis and vaccine.

The tegument of bile-dwelling Fasciola gigantica is the interfacing layer that helps the parasite to maintain its homeostasis, and evade the hostile environment, including the host's immune attacks. The tegument is a syncytial layer about 10 mm thick, that is formed by the fusion of cytoplasmic processes of tegument cells, whose soma lie underneath the two muscle layers. The surface of the tegument is highly folded and invaginated into numerous ridges, pits and spines, which help to increase the surface area of the tegument for the absorption and exchanging of molecules, as well as for attachment. The outer membrane covering the tegument is a trilaminate sheet about 12 nm thick, and coated with a carbohydrate-rich glycocalyx layer that also bears high negative charges. Some host molecules may also be adsorbed onto this layer. These unique characteristics enable the parasite to evade the antibody-dependent cell-mediated cytotoxicity (ADCC) reaction exerted by the host. The outer membrane and glycocalyx is continuously replaced by the reserved membrane synthesized and stored in secretory granules of tegument cells, that are transported via cell processes towards the tegument by microtubules. The basal membrane of the tegument is trilaminate and invaginated to form membrane infoldings with closely aligned mitochondria. The tegument cytoskeleton is composed of a highly cross-linked network of 4-6 nm knobby microtrabecular fibers, bundles of intermediate filaments, microtubules that splay out from the tegument cells' processes. Major proteins of the cytoskeleton are actin, paramyosin and tubulin. The flukes' antigens that can elicit strong immunological responses in animal hosts are synthesized and released mainly from the tegument and the cecum. The majority of antigens derived from the surface membrane and the tegument are of MW 97, 66, 58, 54, 47 and 14 kDa, while those released from the cecum are cysteine proteases of MW 27, 26 kDa. Monoclonal antibodies have been raised against some of these antigens, and have been employed in immunodiagnosis of the infection. From the protection conferred to animal models and the in vitro killing assays of young parasites by specific antibodies, candidate vaccines could be selected from these antigens, such as, an antioxidant enzyme, glutathione-S-transferase, the digestive enzyme cysteine proteases, the surface-tegument proteins, such as fatty acid binding protein (14 kDa), membrane proteins (at 66 kDa), as well as muscle protein paramyosin, and hemoprotein. Ongoing research have been directed at deciphering the genetic codes and the syntheses of some of these antigens by recombinant DNA technology.

Animals↗

PubMed2001

Unique effects of different fatty acid species on the physical properties of the torpedo acetylcholine receptor membrane.

To study the effects produced by free fatty acids (FFA) on the biophysical properties of Torpedo marmorata nicotinic acetylcholine receptor-rich native membranes and to investigate the topology of their binding site(s), fluorescence measurements were carried out using the fluorescent probe Laurdan (6-dodecanoyl-2-(dimethylamino) naphthalene) and ADIFAB, an Acrylodan-derivatized intestinal fatty acid-binding protein. The generalized polarization (GP) of the former probe was used to learn about the physical state of the membrane upon FFA binding. Saturated FFA induced a slight increase in GP, whereas cis-unsaturated fatty acids decreased GP. Double bond isomerism could also be distinguished; oleic acid (18:1cis) induced a net disordering effect, whereas elaidic acid (18:1trans) produced no changes in GP. The changes in the efficiency of the Förster energy transfer from the protein to Laurdan brought about by addition of FFA, together with the distances involved in this process, indicate that all FFA studied share a common site at the lipid-protein interface. However, despite being located at the same site, each class of FFA differs in its effect on the physical properties of the membrane. These data lead us to suggest that it is the direct action of FFA at the lipid-protein interface, displacing essential lipids from their sites rather than changes in bulk properties such as membrane fluidity that accounts for the effect of FFA on the acetylcholine receptor membrane.

2-Naphthylamine↗

PubMed1993

Basement membrane formation and re-distribution of the beta 1 integrins in a human intestinal co-culture system.

We have developed a co-culture system suited for the study of epithelial-mesenchymal interactions in the human fetal small intestine. As the epithelial component of this model, we used the human intestinal cell line Caco-2 that is unique in its property to differentiate in vitro into a mature fetal enterocyte-like cell type. A sheet of human intestinal mesenchymal cells, which we derived from an 18-week-old fetus, was used as mesenchymal element. Expression and distribution of cell-specific markers (cytokeratin 18 and dipeptidyl peptidase IV), major basement membrane components, and beta 1 integrins were analyzed. In 14-day co-cultures, Caco-2 cells formed a cytokeratin 18-positive epithelial-like sheet covering the vimentin-positive HIM cell layers. As assessed by brush border dipeptidyl peptidase IV expression, co-cultured Caco-2 cells achieved cytodifferentiation as when cultured on plastic. A complete deposition of all known major human fetal intestinal basement membrane components occurred at the Caco-2/HIM interface. Type IV collagen and tenascin were produced from the mesenchymal compartment, whereas laminin and fibronectin were contributed by both cell types. Interestingly, synthesis and deposition of basement membrane heparan sulfate proteoglycan were exclusively observed in co-cultures, suggesting modulation of epithelial expression of this molecule by HIM cells. Finally, we observed that epithelial integrin-beta 1 chains redistributed at the basal domain of co-cultured Caco-2 cells. Taken together, these observations indicate that the Caco-2/HIM co-culture model is a valuable system to study in vitro human basement membrane formation in the context of intestinal epithelial-mesenchymal interactions.

Basement Membrane↗

PubMed1992

The homodimeric hemoglobin from Scapharca can be locked into new cooperative structures upon reaction of Cys92, located at the subunit interface, with organomercurials.

In the cooperative, homodimeric hemoglobin from Scapharca inaequivalvis, HbI, the subunit interface is formed by the heme-carrying E and F helices and contains the only cysteine residue of the globin chain (Cys92, F2) in an area which changes from hydrophilic to hydrophobic upon oxygenation. Binding of organomercurials to HbI is cooperative and entails major quaternary rearrangements. The reaction of Cys92 with p-chloromercuri-benzoate (PMB) and p-nitro-o-chloromercuriphenol (PN), a sensitive reporter of the cysteine microenvironment at neutral pH values, has been followed in stopped flow experiments. Kinetic evidence for the cooperativity of mercurial binding has been obtained and the rate of the corresponding conformational transition has been estimated. As expected PN, but not PMB, is able to monitor the oxygen-linked change of the cysteine microenvironment. The modification of Cys92 with PN has unique functional effects. In PN-reacted HbI cooperativity is maintained, albeit to a different extent, depending on the ligation state of the protein during mercaptide formation. It may be envisaged that PN locks the protein into new, cooperative, quaternary structures stabilized by hydrogen bonding interactions between the ionized nitrophenol moiety and the contralateral subunit.

Animals↗

PubMed2004

Factors influencing fetal pulse oximetry performance.

Fetal pulse oximetry shares many problems with traditional pulse oximetry, but also poses unique challenges that may compromise accurate SpO2 determination and data availability. The purpose of this review is to characterize the factors that may influence fetal pulse oximetry and their relationship to sensor design. A review of the literature of pulse oximetry identifies the factors that have been shown to influence fetal pulse oximetry performance, as well as other factors from traditional pulse oximetry that may also be expected to have an effect. Sensor design choices, including monitoring site, wavelength, and configuration, are related to the incidence and mitigation of these factors. Sensor designs may be characterized by monitoring site, means of retention, and operating mode (reflectance versus transmission). The factors influencing fetal pulse oximetry may be categorized as follows: fetal physiology, tissue characteristics at the monitoring site, sensor-tissue interface, and external influences. Monitoring site selection is of paramount importance in reducing the impact of interfering factors on fetal pulse oximetry performance. Many factors of importance in traditional pulse oximetry have yet to be characterized as far as their potential for interference in fetal pulse oximetry.

Equipment Design↗

PubMedDate not supplied

Stroke surfaces: temporally coherent artistic animations from video.

The contribution of this paper is a novel framework for synthesizing nonphotorealistic animations from real video sequences. We demonstrate that, through automated mid-level analysis of the video sequence as a spatiotemporal volume--a block of frames with time as the third dimension--we are able to generate animations in a wide variety of artistic styles, exhibiting a uniquely high degree of temporal coherence. In addition to rotoscoping, matting, and novel temporal effects unique to our method, we demonstrate the extension of static nonphotorealistic rendering (NPR) styles to video, including painterly, sketchy, and cartoon shading. We demonstrate how this novel coherent shading framework may be combined with our earlier motion emphasis work to produce a comprehensive "Video Paintbox" capable of rendering complete cartoon-styled animations from video clips.

Algorithms↗

PubMedDate not supplied

Using virtual reality to teach radiographic positioning.

Using virtual reality to teach radiographic positioning overcomes many of the limitations of traditional teaching methods and offers several unique advantages. This article describes a virtual reality prototype that could be used to teach radiographic positioning of the elbow joint. By using virtual reality, students are able to see the movement of bones as the arm is manipulated. The article also describes the development and challenges of using virtual reality in medical education.

Computer Graphics↗

PubMed2006

Crystal structures of VAP1 reveal ADAMs' MDC domain architecture and its unique C-shaped scaffold.

ADAMs (a disintegrin and metalloproteinase) are sheddases possessing extracellular metalloproteinase/disintegrin/cysteine-rich (MDC) domains. ADAMs uniquely display both proteolytic and adhesive activities on the cell surface, however, most of their physiological targets and adhesion mechanisms remain unclear. Here for the first time, we reveal the ADAMs' MDC architecture and a potential target-binding site by solving crystal structures of VAP1, a snake venom homolog of mammalian ADAMs. The D-domain protrudes from the M-domain opposing the catalytic site and constituting a C-shaped arm with cores of Ca2+ ions. The disintegrin-loop, supposed to interact with integrins, is packed by the C-domain and inaccessible for protein binding. Instead, the hyper-variable region (HVR) in the C-domain, which has a novel fold stabilized by the strictly conserved disulfide bridges, constitutes a potential protein-protein adhesive interface. The HVR is located at the distal end of the arm and faces toward the catalytic site. The C-shaped structure implies interplay between the ADAMs' proteolytic and adhesive domains and suggests a molecular mechanism for ADAMs' target recognition for shedding.

ADAM Proteins↗

PubMed1999

Interaction sites of the C-terminal region of the cGMP phosphodiesterase inhibitory subunit with the GDP-bound transducin alpha-subunit.

In the present report, the region of interaction between the GDP-bound alpha-subunit of transducin (alphat.GTP) and the cGMP phosphodiesterase inhibitory gamma-subunit (Pgamma) has been studied. It is widely accepted that the alphat.GTP is the active form of transducin and that the GDP-bound transducin alpha-subunit (alphat. GDP) is the inactive form. We have reported previously that the binding region of the C-terminal of Pgamma on alphat.GTP is in a region between the exposed face of the alpha3 and alpha4 helices of alphat.GTP [Liu, Arshavsky and Ruoho (1996) J. Biol. Chem. 271, 26900-26907]. We now report that N-[(3-[125I]iodo-4-azidophenylpropionamido-S-(2-thiopyridyl) ]cysteine ([125I]ACTP)-derivatized Pgamma (at Cys-68) reversibly undergoes a unique disulphide exchange of the radioiodinated moiety N-(3-[125I]iodo-4-azidophenylpropionamido)cysteine ([125I]APC) from Cys-68 of Pgamma to alphat.GDP but not to the guanosine 5'-(gamma-thio)-triphosphate (GTP[S])-bound transducin alpha-subunit (alphat-GTP[S]). The specificity of the interaction was demonstrated by the fact that exchange was protected by the functionally active Cys-68-->Ala Pgamma mutant, and by pretreatment of the alphat.GDP with the betagamma-subunit of transducin. Chemical cleavage and amino acid sequencing demonstrated that the [125I]ACTP-derived Pgamma specifically transferred the [125I]APC group to Cys-250 and Cys-210 of alphat.GDP. These data indicate that the C-terminal region (especially Cys-68-Trp-70) of Pgamma interacts with alphat. GDP on the exposed interface between alpha2/beta4 and alpha3/beta5 of the alpha-subunit of transducin. Disulphide exchange was also observed with the alpha-subunit of holotransducin but this was only approx. 60% of that of pure alphat.GDP. The variation in the binding pattern between alphat.GDP and alphat.GTP with the C-terminal region of Pgamma may contribute to the functional difference between the GDP- and GTP-bound states.

3',5'-Cyclic-GMP Phosphodiesterases↗

PubMed1995

Regulation of the Src protein tyrosine kinase.

Members of the Src family of protein tyrosine kinases are involved in a variety of cellular processes, including cell growth, cell differentiation and neuronal signalling. N-terminal to the catalytic domain, Src family members contain a Src homology 2 (SH2) domain, a Src homology 3 (SH3) domain, and a unique domain, all capable of protein-protein interactions. Negative regulation by phosphorylation of a conserved tyrosine residue at the C-terminal tail of the molecules is characteristic of this family of enzymes. Phosphorylation of this residue causes the intramolecular interactions of the SH2 domain with the tail, and of the SH3 domain with an as yet undefined region, probably within the catalytic domain. Enzymatically active Src family kinases, on the other hand, are phosphorylated at a tyrosine in the middle of the catalytic domain and phosphorylation of this residue is a prerequisite for high activity. Regulators of these enzymes may thus act by altering the phosphorylation state of the two key tyrosine residues or by interfering with the regulatory intramolecular interactions, either by direct binding or by modification of the interfaces involved.

Gene Expression Regulation, Enzymologic↗

PubMed2004

Clinical applications of optical coherence tomography for the diagnosis and management of macular diseases.

Optical coherence tomography provides high-resolution cross-sectional images of macular pathology in vivo. Owing to its noninvasive noncontact nature and use of near-infrared illumination of the fundus, it is well tolerated by patients. The images can be obtained without dilation and are highly reproducible,quantifying retinal thickness with an axial resolution of 10 microm. These qualities make OCT a powerful diagnostic tool complementary to fluorescein angiography, photography, and biomicroscopy. Optical coherence tomography has proved to be particularly useful for the clinical evaluation of vitreoretinal interface disorders and alterations of the structural anatomy of the macula, such as from edema, choroidal neovascularization, and detachment of the neurosensory retina or RPE. The information obtained from high-resolution evaluation of retinal anatomy allows the diagnosis of conditions that are difficult to establish with biomicroscopy or angiography and improves the clinician's ability to make the optimal treatment decision. The quantitative assessment of OCT allows an objective means to monitor disease progression and therapeutic response.A logical application of this technology is the evaluation of underlying macular pathology in patients considering cataract extraction. Uncovering vitreomacular traction, epiretinal membranes, occult choroidal neovascular membranes with minimal CME, subretinal fluid accumulation, and RPE detachments greatly impacts the clinical management of cataract patients and the weighing of surgical risks and benefits. OCT is a uniquely powerful means of visualizing retinal morphology and pathology that may not be revealed using current techniques of biomicroscopy, fluorescein angiography, or B-scan ultrasonography, and serves as the newest adjunct in diagnostic technology.

Adult↗

PubMed2005

Control of the CFTR channel's gates.

Unique among ABC (ATP-binding cassette) protein family members, CFTR (cystic fibrosis transmembrane conductance regulator), also termed ABCC7, encoded by the gene mutated in cystic fibrosis patients, functions as an ion channel. Opening and closing of its anion-selective pore are linked to ATP binding and hydrolysis at CFTR's two NBDs (nucleotide-binding domains), NBD1 and NBD2. Isolated NBDs of prokaryotic ABC proteins form homodimers upon binding ATP, but separate after hydrolysis of the ATP. By combining mutagenesis with single-channel recording and nucleotide photolabelling on intact CFTR molecules, we relate opening and closing of the channel gates to ATP-mediated events in the NBDs. In particular, we demonstrate that two CFTR residues, predicted to lie on opposite sides of its anticipated NBD1-NBD2 heterodimer interface, are energetically coupled when the channels open but are independent of each other in closed channels. This directly links ATP-driven tight dimerization of CFTR's cytoplasmic NBDs to opening of the ion channel in the transmembrane domains. Evolutionary conservation of the energetically coupled residues in a manner that preserves their ability to form a hydrogen bond argues that this molecular mechanism, involving dynamic restructuring of the NBD dimer interface, is shared by all members of the ABC protein superfamily.

ATP-Binding Cassette Transporters↗

PubMed2005

MARS: microarray analysis, retrieval, and storage system.

BACKGROUND: Microarray analysis has become a widely used technique for the study of gene-expression patterns on a genomic scale. As more and more laboratories are adopting microarray technology, there is a need for powerful and easy to use microarray databases facilitating array fabrication, labeling, hybridization, and data analysis. The wealth of data generated by this high throughput approach renders adequate database and analysis tools crucial for the pursuit of insights into the transcriptomic behavior of cells. RESULTS: MARS (Microarray Analysis and Retrieval System) provides a comprehensive MIAME supportive suite for storing, retrieving, and analyzing multi color microarray data. The system comprises a laboratory information management system (LIMS), a quality control management, as well as a sophisticated user management system. MARS is fully integrated into an analytical pipeline of microarray image analysis, normalization, gene expression clustering, and mapping of gene expression data onto biological pathways. The incorporation of ontologies and the use of MAGE-ML enables an export of studies stored in MARS to public repositories and other databases accepting these documents. CONCLUSION: We have developed an integrated system tailored to serve the specific needs of microarray based research projects using a unique fusion of Web based and standalone applications connected to the latest J2EE application server technology. The presented system is freely available for academic and non-profit institutions. More information can be found at http://genome.tugraz.at.

Algorithms↗

PubMed2006

Investigation of the dimer interface and substrate specificity of prolyl dipeptidase DPP8.

DPP8 belongs to the family of prolyl dipeptidases, which are capable of cleaving the peptide bond after a penultimate proline residue. Unlike DPP-IV, a drug target for type II diabetes, no information is available on the crystal structure of DPP8, the regulation of its enzymatic activity, or its substrate specificity. In this study, using analytical ultracentrifugation and native gel electrophoresis, we show that the DPP8 protein is predominantly dimeric when purified or in the cell extracts. Four conserved residues in the C-terminal loop of DPP8 (Phe(822), Val(833), Tyr(844), and His(859)), corresponding to those located at the dimer interface of DPP-IV, were individually mutated to Ala. Surprisingly, unlike DPP-IV, these single-site mutations abolished the enzymatic activity of DPP8 without disrupting its quaternary structure, indicating that dimerization itself is not sufficient for the optimal enzymatic activity of DPP8. Moreover, these mutations not only decreased k(cat), as did the corresponding DPP-IV mutations, but also dramatically increased K(m). We further show that the K(m) effect is independent of the substrate assayed. Finally, we identified the distinctive and strict substrate selectivity of DPP8 for hydrophobic or basic residues at the P2 site, which is in sharp contrast to the much less discriminative substrate specificity of DPP-IV. Our study has identified the residues absolutely required for the optimal activity of DPP8 and its unique substrate specificity. This study extends the functional importance of the C-terminal loop to the whole family of prolyl dipeptidases.

Amino Acid Sequence↗

PubMed2005

[Usefulness of FDG-PET for the diagnosis of brain tumors].

Although magnetic resonance imaging (MRI) and X-ray computed tomography (CT) are the two imaging modalities used conventionally for the morphological OUN imaging, there are many cases for positron emission tomography (PET) diagnostic. Basal radiopharmaceutic used in PET is a 18F-2-Fluoro-2-deoxy-D-glucose (18FDG). Use of PET imaging provides in vivo biochemical and physiological data and therefore can provide unique functional information about tumors compared to histological or anatomic neuroradiological methods. PET can provide information regarding tumor grading, delineation of tumors margins, differentiation of recurrent brain tumors from necrosis (golden standard), guidance for stereotactic biopsy, response to therapy and prognosis. New value in brain tumor imaging is combining two essential and complementary imaging modalities PET and multisection CT to create one integrated unit that allows both functional and anatomic imaging in a single study. This allows PET-CT for more accurate tumor localization and variability assessment changes impressions and increases diagnostic confidence. The first PET-CT centre in Poland is localised in Cancer Centre in Bydgoszcz. Scanning is performed on a dedicated Biograph (PET-CT) LSO scanner (SIMENS, Germany), and cyclotron RDS-111 (CTI, USA), FDG production laboratory (NUCLEAR INTERFACE, Germany, COMECER, Italy) and FDG quality control (RAYTES, Germany) are radiopharmaceutical production unit.

Brain Neoplasms↗