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Tissue Cells (tissue + cell)
Kinds of Tissue Cells Selected AbstractsSensitivity of alveolar macrophages to substrate mechanical and adhesive propertiesCYTOSKELETON, Issue 6 2006Sophie Féréol Abstract In order to understand the sensitivity of alveolar macrophages (AMs) to substrate properties, we have developed a new model of macrophages cultured on substrates of increasing Young's modulus: (i) a monolayer of alveolar epithelial cells representing the supple (,0.1 kPa) physiological substrate, (ii) polyacrylamide gels with two concentrations of bis-acrylamide representing low and high intermediate stiffness (respectively 40 kPa and 160 kPa) and, (iii) a highly rigid surface of plastic or glass (respectively 3 MPa and 70 MPa), the two latter being or not functionalized with type I-collagen. The macrophage response was studied through their shape (characterized by 3D-reconstructions of F-actin structure) and their cytoskeletal stiffness (estimated by transient twisting of magnetic RGD-coated beads and corrected for actual bead immersion). Macrophage shape dramatically changed from rounded to flattened as substrate stiffness increased from soft ((i) and (ii)) to rigid (iii) substrates, indicating a net sensitivity of alveolar macrophages to substrate stiffness but without generating F-actin stress fibers. Macrophage stiffness was also increased by large substrate stiffness increase but this increase was not due to an increase in internal tension assessed by the negligible effect of a F-actin depolymerizing drug (cytochalasine D) on bead twisting. The mechanical sensitivity of AMs could be partly explained by an idealized numerical model describing how low cell height enhances the substrate-stiffness-dependence of the apparent (measured) AM stiffness. Altogether, these results suggest that macrophages are able to probe their physical environment but the mechanosensitive mechanism behind appears quite different from tissue cells, since it occurs at no significant cell-scale prestress, shape changes through minimal actin remodeling and finally an AMs stiffness not affected by the loss in F-actin integrity. Cell Motil. Cytoskeleton 2006. © 2006 Wiley-Liss, Inc. [source] Alterations of plasma antioxidants and mitochondrial DNA mutation in hair follicles of smokersENVIRONMENTAL AND MOLECULAR MUTAGENESIS, Issue 3 2002Chin-San Liu Abstract The effects of long-term smoking on mitochondrial DNA (mtDNA) deletions in hair follicles were investigated in subjects with different antioxidant capacity. Twenty-two male smokers with a smoking index of greater than 5 pack-years and without any known systemic diseases were recruited for this study. Forty healthy nonsmoking males were included as controls. We found that the concentrations of ascorbate and ,-tocopherol and the activities of glutathione S -transferase (GST) and glutathione peroxidase in blood plasma were significantly decreased in smokers. The levels of glutathione and protein thiols in whole blood and the incidence of a 4,977 bp deletion of mtDNA (dmtDNA) in hair follicles were significantly increased in smokers. A significantly higher incidence of the 4,977 bp dmtDNA was found in smokers with plasma GST activity less than 5.66 U/l (OR = 7.2, P = 0.020). Using multiple covariate ANOVA and logistic regression, we found that age and low plasma GST activity were the only two risk factors for the 4,977 bp dmtDNA. These results suggest that smoking depletes antioxidants and causes mtDNA deletions and that plasma GST may play an important role in the preservation of the mitochondrial genome in tissue cells of smokers. Environ. Mol. Mutagen. 40:168,174, 2002. © 2002 Wiley-Liss, Inc. [source] Bioactive and Degradable Composite Microparticulates for the Tissue Cell Population and Osteogenic DevelopmentADVANCED ENGINEERING MATERIALS, Issue 10 2009Hye-Sun Yu Bioactive and degradable composite microspheres (bioactive glass,synthetic biopolymer) were produced to deliver tissue cells and to aid their osteogenic development targeted for hard tissues. Cellular population (left, SEM cell image at day 3) and osteoblastic differentiation (right, immunofluorescence staining with bone marker at day 14) on the microspheres was evident, suggesting the composite microspheres provided effective 3D substrate conditions for hard tissue regeneration. [source] Ecoimmunity: immune tolerance by symmetric co-evolutionEVOLUTION AND DEVELOPMENT, Issue 6 2007Uri Nevo SUMMARY It is widely accepted that immune tolerance toward "self" is established by central and peripheral adaptations of the immune system. Mechanisms that have been demonstrated to play a role in the induction and maintenance of tolerance include thymic deletion of self-reactive T cells, peripheral T cell anergy and apoptosis, as well as thymic and peripheral induction of regulatory T cells. However, a large body of experimental findings cannot be rationalized solely based on adaptations of the immune system to its environment. Here we propose a new model termed Ecoimmunity, where the immune system and the tissue are viewed as two sides of a continuously active and co-evolving predator,prey system. Ecoimmunity views self-tolerance, not as an equilibrium in which autoimmunity is chronically suppressed, but as a symmetrical balanced conflict between the ability of immune cells to destroy tissue cells by numerous mechanisms, and the capacity of adapted tissue cells to avoid predation. This balance evolves during ontogeny, in parallel to immune adaptations, embryonic tissue cells adapt their phenotype to the corresponding immune activity by developing the ability to escape or modulate damaging local immune responses. This phenotypic plasticity of tissue cells is directed by epigenetic selection of gene expression pattern and cellular phenotype amidst an ongoing immune pressure. Thus, whereas some immune cells prey predominantly on pathogens and infected cells, self-reactive cells continuously prey on incompetent tissue cells that fail to express the adapted phenotype and resist predation. This model uses ecological generalization to reconcile current contradictory observations as well as classical enigmas related to both autoimmunity and to tolerance toward foreign tissues. Finally, it provides empirical predictions and alternative strategies toward clinical challenges. [source] Contribution of endothelial cells to organogenesis: a modern reappraisal of an old Aristotelian conceptJOURNAL OF ANATOMY, Issue 4 2007E. Crivellato Abstract It is well established that many tissue-derived factors are involved in blood vessel formation, but evidence is now emerging that endothelial cells themselves represent a crucial source of instructive signals to non-vascular tissue cells during organ development. Thus, endothelial cell signalling is currently believed to promote fundamental cues for cell fate specification, embryo patterning, organ differentiation and postnatal tissue remodelling. This review article summarizes some of the recent advances in our understanding of the role of endothelial cells as effector cells in organ formation. [source] Upregulation of Osteopontin by Osteocytes Deprived of Mechanical Loading or Oxygen,JOURNAL OF BONE AND MINERAL RESEARCH, Issue 2 2005Ted S Gross PhD Abstract The pathway(s) by which disuse is transduced into locally mediated osteoclastic resorption remain unknown. We found that both acute disuse (in vivo) and direct hypoxia (in vitro) induced rapid upregulation of OPN expression by osteocytes. Within the context of OPN's role in osteoclast migration and attachment, hypoxia-induced osteocyte OPN expression may serve to mediate disuse-induced bone resorption. Introduction: We have recently reported that disuse induces osteocyte hypoxia. Because hypoxia upregulates osteopontin (OPN) in nonconnective tissue cells, we hypothesized that both disuse and hypoxia would rapidly elevate expression of OPN by osteocytes. Materials and Methods: The response of osteocytes to 24 h of disuse was explored by isolating the left ulna diaphysis of adult male turkeys from loading (n = 5). Cortical osteocytes staining positive for OPN were determined using immunohistochemistry and confocal microscopy. In vitro experiments were performed to determine if OPN expression was altered in MLO-Y4 osteocytes by direct hypoxia (3, 6, 24, and 48 h) or hypoxia (3 and 24 h) followed by 24 h of reoxygenation. A final in vitro experiment explored the potential of protein kinase C (PKC) to regulate hypoxia-induced osteocyte OPN mRNA alterations. Results: We found that 24 h of disuse significantly elevated osteocyte OPN expression in vivo (145% versus intact bones; p = 0.02). We confirmed this finding in vitro, by observing rapid and significant upregulation of OPN protein expression after 24 and 48 h of hypoxia. Whereas 24 h of reoxygenation after 3 h of hypoxia restored normal osteocyte OPN expression levels, 24 h of reoxygenation after 24 h of hypoxia did not mitigate elevated osteocyte OPN expression. Finally, preliminary inhibitor studies suggested that PKC serves as a potent upstream regulator of hypoxia-induced osteocyte OPN expression. Conclusions: Given the documented roles of OPN as a mediator of environmental stress (e.g., hypoxia), an osteoclast chemotaxant, and a modulator of osteoclastic attachment to bone, we speculate that hypoxia-induced osteocyte OPN expression may serve to mediate disuse-induced osteoclastic resorption. Furthermore, it seems that a brief window of time exists in which reoxygenation (as might be achieved by reloading bone) can serve to inhibit this pathway. [source] Interplay among enteric neurons, interstitial cells of Cajal, resident and not resident connective tissue cellsJOURNAL OF CELLULAR AND MOLECULAR MEDICINE, Issue 7 2009Maria-Simonetta Faussone-PellegriniArticle first published online: 16 JUN 200 [source] Involvement of vascular endothelial growth factor, CD44 and CD133 in periodontal disease and diabetes: an immunohistochemical studyJOURNAL OF CLINICAL PERIODONTOLOGY, Issue 1 2009Guendalina Lucarini Abstract Aim: The aim of this study was to investigate the relationship between expression of angiogenic and regeneration markers and periodontal disease in subjects with/without diabetes mellitus. Material and Methods: Immunohistochemical detection of vascular endothelial growth factor (VEGF), CD44 and CD133 was performed in 16 samples each of (1) healthy gingiva from non-diabetic subjects (controls), (2) gingiva from non-diabetic subjects with periodontitis, (3) gingiva from subjects with type 1 diabetes and periodontitis, (4) gingiva from subjects with type 2 diabetes and periodontitis. Results: Diseased gingivae from patients with diabetes and periodontitis had greater clinical measures of periodontal disease than those with periodontitis only. VEGF expression was significantly enhanced in epithelial and endothelial cells from patients with periodontitis compared with controls (p<0.05). Epithelial CD44 expression was strong in all groups, while CD44 was significantly enhanced (p<0.05) in connective tissue cells from both diabetic groups. Epithelial and endothelial CD133 expression was comparable in all patients except those with type 2 diabetes and periodontitis, where it was not detected. Stromal CD133 expression was significantly lower in patients with type 2 diabetes and periodontitis and was increased in periodontitis patients (p<0.05). Conclusions: The involvement and high expression of VEGF, CD44 and CD133 in periodontal disease may predict a greater regeneration capacity of gingival tissue. [source] Nucleolar organizer region staining patterns in paraffin-embedded tissue cells from human skin cancersJOURNAL OF CUTANEOUS PATHOLOGY, Issue 5 2005Rosana F. Romão-Corrêa Background:, Increased number of nucleoli (nucleolar organizer regions, NORs) with abnormal shapes and sizes, including small dots, has been used as prognostic tools to evaluate tumor proliferation levels and troublesome borderline lesions. In this study, NOR patterns of skin cancers were performed in the search of a valuable prognostic method to complement other histological procedures. Methods:, Paraffin-embedded tumor tissue was obtained from basal and squamous cell carcinomas, cutaneous malignant melanoma, premalignant lesions, and Skmel-28 human melanoma cells. Slices were dewaxed and AgNOR stained. The patterns were scored and submitted for statistical analyses. Results:, All types of cancer cells showed variable numbers of abnormally shaped nucleoli and dot-like structures. Only tumor cells presented four or more nucleoli, with or without dots, while 85% of the normal cells had one single NOR without dots. Most data were statistically significant when compared to normal cells. As a whole, squamous cell carcinoma and malignant melanoma tumor cells had less NOR alterations than basal cell carcinoma (BCC) tumor types. Conclusions:, Changes in the number and shape of nucleoli present in malignant cells could be attributed to increased levels on rDNA transcription on cancer cells, besides abnormal remodeling of chromatin, which could disrupt proper nucleoli association. Increased genetic alterations on malignant basal cells could contribute to impair invasive and migration abilities of BCC tumors. [source] A reovirus disease in cultured mud crab, Scylla serrata, in southern ChinaJOURNAL OF FISH DISEASES, Issue 3 2007S-P Weng Abstract A reovirus, designated mud crab reovirus (MCRV), associated with large economic losses was recently isolated from marine cultured mud crab, Scylla serrata, in southern China. The complete viral particle is 70 nm in diameter, icosahedral and non-enveloped. The virus infects connective tissue cells of the hepatopancreas, gills and intestine in mud crab and develops in the cytoplasm. Hundred per cent mortality was observed in mud crab experimentally infected by intramuscular injection, bath inoculation and oral inoculation, while cohabitation infection caused 80% mortality. The viral genome consists of 13 linear dsRNA segments, with an electrophoretic pattern 1/5/7. The results of this study suggest that the virus is highly pathogenic and can be transmitted enterically as well as via the body surface of mud crab. Although the genomic organization of this virus is different from that of the other crab reoviruses, CcRV-W2 and DpPV, all three of these reoviruses have similar electrophoresis patterns. Therefore, MCRV may be a new member of the DpPV and CcRV-W2 group. [source] Phenotypic comparison of periodontal ligament cells in vivo and in vitroJOURNAL OF PERIODONTAL RESEARCH, Issue 2 2001P. Lekic The mammalian periodontal ligament contains heterogeneous populations of connective tissue cells, the precise function of which is poorly understood. Despite close proximity to bone and the application of high amplitude physical forces, cells in the periodontal ligament (PL) are capable of expressing regulatory factors that maintain PL width during adult life. The study of PL homeostasis and PL cell differentiation requires culture and phenotypic methods for precise characterization of PL cell populations, in particular those cells with an inherently osteogenic program. Currently it is unknown if cells cultured from the PL are phenotypically similar to the parental cells that are present in the tissues. We have compared the phenotype of cells in vivo with cells derived from the PL and expanded in vitro to assess the general validity of in vitro models for the study of phenotypic regulation in vivo. Rat PL cells were isolated by either scraping the root of the extracted first mandibular molars (Group A), or by scraping the alveolar socket following extraction of first mandibular molars (Group B), or by obtaining a mixture of cells after disaggregating a block of tissue consisting of first mandibular molar, PL and the surrounding alveolar bone (Group C). Cultured cells at confluence were fixed and immunostained for ,-smooth muscle actin (,-SMA), osteopontin (OPN), alkaline phosphatase (AP), or bone sialoprotein (BSP). For in vivo assessments, frontal sections of rat first mandibular molar were immunostained for ,-SMA, OPN, AP and BSP. We examined osteogenic differentiation of cultured PL cell cultures by bone nodule-forming assays. In vivo and at all examined sites, >68% of PL cells were immunostained for AP; ,50% and ,51% for OPN and ,-SMA (p=0.3), respectively, while only ,8% were positively stained for BSP (p<0.01). Analysis of cultured PL cells in Groups A, B and C showed 54%, 53% and 56% positive staining for ,-SMA respectively; 51%, 56%, 54% for OPN; 66%, 70%, 69% for AP and 2.2%, 1.4% and 2.8% for BSP. The mean percentage of PL cells in situ stained for the different markers was similar to that of cultured PL cells (Group A,Group B,Group C in situ for p>0.2) except for BSP which was 3 to 4 fold higher in vivo(p<0.01). PL cell cultures treated with dexamethasone showed mineralized tissue formation for all groups (A, B, C), but no mineralized tissue formation was detected in the absence of dexamethasone. As PL cells express quantitatively similar phenotypes in vitro and in vivo, we conclude that the in vitro models used here for assessment of PL cell differentiation appear to be appropriate and are independent of the cell sampling method. Further, dexamethasone-dependent progenitors are present both on the root and bone-related sides of the PL. [source] Starch,poly(,-caprolactone) and starch,poly(lactic acid) fibre-mesh scaffolds for bone tissue engineering applications: structure, mechanical properties and degradation behaviourJOURNAL OF TISSUE ENGINEERING AND REGENERATIVE MEDICINE, Issue 5 2008M. E. Gomes Abstract In scaffold-based tissue engineering strategies, the successful regeneration of tissues from matrix-producing connective tissue cells or anchorage-dependent cells (e.g. osteoblasts) relies on the use of a suitable scaffold. This study describes the development and characterization of SPCL (starch with ,-polycaprolactone, 30:70%) and SPLA [starch with poly(lactic acid), 30:70%] fibre-meshes, aimed at application in bone tissue-engineering strategies. Scaffolds based on SPCL and SPLA were prepared from fibres obtained by melt-spinning by a fibre-bonding process. The porosity of the scaffolds was characterized by microcomputerized tomography (µCT) and scanning electron microscopy (SEM). Scaffold degradation behaviour was assessed in solutions containing hydrolytic enzymes (,-amylase and lipase) in physiological concentrations, in order to simulate in vivo conditions. Mechanical properties were also evaluated in compression tests. The results show that these scaffolds exhibit adequate porosity and mechanical properties to support cell adhesion and proliferation and also tissue ingrowth upon implantation of the construct. The results of the degradation studies showed that these starch-based scaffolds are susceptible to enzymatic degradation, as detected by increased weight loss (within 2 weeks, weight loss in the SPCL samples reached 20%). With increasing degradation time, the diameter of the SPCL and SPLA fibres decreases significantly, increasing the porosity and consequently the available space for cells and tissue ingrowth during implantation time. These results, in combination with previous cell culture studies showing the ability of these scaffolds to induce cell adhesion and proliferation, clearly demonstrate the potential of these scaffolds to be used in tissue engineering strategies to regenerate bone tissue defects. Copyright © 2008 John Wiley & Sons, Ltd. [source] Nasal endothelial interleukin-10 expression is negatively correlated with nasal symptoms after allergen provocationALLERGY, Issue 5 2009B. Muller Background:, Despite major efforts, factors that predict or correspond to the level of allergic symptoms remain elusive. Given our previous observations of mucosal interleukin-10 (IL-10) expression by local tissue cells and its described role as immune modulator, we hypothesized that, in allergic rhinitis, nasal mucosal IL-10 expression could influence the severity of symptoms. Methods:, In this study, we investigated endothelial IL-10 expression in nasal mucosa of healthy- and house dust mite allergic patients, both before and after provocation, and under nasal steroid therapy. Nasal turbinate biopsies were taken from healthy individuals as well as from house dust mite allergic patients, both before and after provocation. Allergic patients received fluticasone proprionate aqueous nasal spray or control treatment. In the allergic patients, endothelial IL-10 scores based on immunohistochemical stainings were correlated with allergic symptoms, measured by visual analog scores. Results:, At baseline, variable levels of endothelial IL-10 were detected in nasal biopsies. After nasal provocation, but not at baseline, endothelial IL-10 expression corresponded very closely to the allergic symptoms after allergen provocation. Low symptom scores were correlated with high endothelial IL-10 scores. This correlation disappeared after fluticason propionate treatment. Conclusions:, There is a large variation in the level of endothelial IL-10 expression both in healthy individuals and in house dust mite allergic patients. Endothelial IL-10 expression may affect local immune reactions resulting in reduced levels of allergic symptoms. [source] Xylem Flow and its Driving Forces in a Tropical Liana: Concomitant Flow-Sensitive NMR Imaging and Pressure Probe MeasurementsPLANT BIOLOGY, Issue 6 2000N. Wistuba Abstract: Flow-sensitive NMR imaging and pressure probe techniques were used for measuring xylem water flow and its driving forces (i.e., xylem pressure as well as cell turgor and osmotic pressure gradients) in a tropical liana, Epipremnum aureum. Selection of tall specimens allowed continuous and simultaneous measurements of all parameters at various distances from the root under diurnally changing environmental conditions. Well hydrated plants exhibited exactly linearly correlated dynamic changes in xylem tension and flow velocity. Concomitant multiple-probe insertions along the plant shoot revealed xylem and turgor pressure gradients with changing magnitudes due to environmental changes and plant orientation (upright, apex-down, or horizontal). The data suggest that in upright and - to a lesser extent - in horizontal plants the transpirational water loss by the cells towards the apex during the day is not fully compensated by water uptake through the night. Thus, longitudinal cellular osmotic pressure gradients exist. Due to the tight hydraulic coupling of the xylem and the tissue cells these gradients represent (besides the transpiration-induced tension in the xylem) an additional tension component for anti-gravitational water movement from the roots through the vessels to the apex. [source] Changes in mesophyll anatomy and sink,source relationships during leaf development in Quercus glauca, an evergreen tree showing delayed leaf greeningPLANT CELL & ENVIRONMENT, Issue 5 2003S.-I. MIYAZAWA ABSTRACT Changes in mesophyll anatomy, gas exchange, and the amounts of nitrogen and cell wall constituents including cellulose, hemicellulose and lignin during leaf development were studied in an evergreen broad-leaved tree, Quercus glauca, and in an annual herb, Phaseolus vulgaris. The number of chloroplasts per whole leaf in P. vulgaris increased and attained the maximal level around 10 d before full leaf area expansion (FLE), whereas it continued to increase even after FLE in Q. glauca. The increase in the number of palisade tissue cells per whole leaf continued until a few days before FLE in Q. glauca, but it had almost ceased by 10 d before FLE in P. vulgaris. The radius and height of palisade tissue cells in Q. glauca, attained their maximal levels at around FLE whereas the thickness of the mesophyll cell wall and concentrations of the cell wall constituents increased markedly after FLE. These results clearly indicated that, in Q. glauca, chloroplast development proceeded in parallel with the cell wall thickening well after completion of the mesophyll cell division and cell enlargement. The sink,source transition, defined to be the time when the increase in daily carbon exchange rate exceeds the daily increase in leaf carbon content, occurred before FLE in P. vulgaris but after FLE in Q. glauca. During leaf area expansion, the maximum daily increase in nitrogen content on a whole leaf basis (the maximum leaf areas were corrected to be identical for these species) in Q. glauca was similar to that in P. vulgaris. In Q. glauca, however, more than 70% of nitrogen in the mature leaf was invested during its sink phase, whereas in P. vulgaris it was 50%. These results suggest that Q. glauca invests nitrogen for cell division for a considerable period and for chloroplast development during the later stages. We conclude that the competition for nitrogen between cell division and chloroplast development in the area of expanding leaves can explain different greening patterns among plant species. [source] Crystal structure of human coactosin-like protein at 1.9 Å resolutionPROTEIN SCIENCE, Issue 11 2004Xuemei Li Abstract Human coactosin-like protein (CLP) shares high homology with coactosin, a filamentous (F)-actin binding protein, and interacts with 5LO and F-actin. As a tumor antigen, CLP is overexpressed in tumor tissue cells or cell lines, and the encoded epitopes can be recognized by cellular and humoral immune systems. To gain a better understanding of its various functions and interactions with related proteins, the crystal structure of CLP expressed in Escherichia coli has been determined to 1.9 Å resolution. The structure features a central ,-sheet surrounded by helices, with two very tight hydrophobic cores on each side of the sheet. CLP belongs to the actin depolymerizing protein superfamily, and is similar to yeast cofilin and actophilin. Based on our structural analysis, we observed that CLP forms a polymer along the crystallographic b axis with the exact same repeat distance as F-actin. A model for the CLP polymer and F-actin binding has therefore been proposed. [source] Developmental Changes of Cell Adhesion Molecule Expression in the Fetal Mouse LiverTHE ANATOMICAL RECORD : ADVANCES IN INTEGRATIVE ANATOMY AND EVOLUTIONARY BIOLOGY, Issue 10 2010Yoshinori Sugiyama Abstract Developmental changes of cell adhesion molecule expression, especially in nonparenchymal cells, have hardly ever been analyzed in the murine liver. The present study was undertaken to immunohistochemically examine the expression of NCAM, ICAM, VCAM, and N-cadherin during mouse liver development and in fetal liver cell cultures. NCAM was transiently expressed in mesenchymal cells of the septum transversum and sinusoidal cells in liver development. In vitro studies demonstrated that desmin-positive stellate cells expressed this cell adhesion molecule. NCAM expression in periportal biliary epithelial cells and connective tissue cells also coincided well with bile duct remodeling processes in the perinatal periods. Expression of ICAM and VCAM was transiently restricted to hepatoblasts, hepatocytes and hemopoietic cells in fetal stages. N-cadherin was expressed not only in hepatoblasts and hepatocytes, but also in nonparenchymal cells such as endothelial cells, stellate cells and connective tissue cells, however the expression was weak. These results suggest that each cell adhesion molecule may play an important role during development in hepatic histogenesis, including hepatoblast/hepatocyte-stellate cell interactions, hemopoiesis, and bile duct morphogenesis. Anat Rec 293:1698,1710, 2010. © 2010 Wiley-Liss, Inc. [source] Actin-Based Motility in the Net Slime Mould Labyrinthula: Evidence for the Role of Myosin in Gliding MovementTHE JOURNAL OF EUKARYOTIC MICROBIOLOGY, Issue 6 2005TERENCE M. PRESTON Abstract. In contrast to crawling movement (e.g. in amoebae and tissue cells) the other major class of substratum-associated motility in eukaryotes, gliding, has received relatively little attention. The net slime mold Labyrinthula provides a useful laboratory model for studying this process since it exhibits a particular kind of gliding in its plasmodial stage. Here nucleated spindle cells glide along self-established cytoplasmic trackways in a predominantly unidirectional manner, at 1,2 ,m/s. These trackways, upon which gliding is dependent, are held by filopodial tethers some distance off the well-developed reticulopodial mesh anchoring the plasmodium onto the substratum. Reflection interference microscopy resolves this matrix in live plasmodia. The axially disposed cytoskeletal elements of the trackways are revealed by rhodamine-labelled phalloidin to be rich in F-actin. A weft of peripheral, rapidly extending filopodia (50 ,m/min) typifies the expanding regions of the plasmodium. Here spindle cells are recruited before emigrating into newly differentiated trackways. Immunoblotting whole plasmodia or a sucrose-soluble cytoplasmic extract reveals a single actin-positive band of Mr 48 kDa. Polyclonal antibodies to two distinct myosin peptide sequences identify a single myosin HC (Mr 96 kDa) in immunoblots. Gliding was reversibly blocked by 10 mM 2,3-butanedione-2-monoxime, a myosin ATPase inhibitor, but it was insensitive to the actin-binding drugs cytochalasin D and phalloidin. We suggest that the force (>50 pN) for gliding motility results from interaction of myosin molecules, associated with the spindle cells, with trackway F-actin via the bothrosomes. [source] PD-1/B7-H1 Interaction Contribute to the Spontaneous Acceptance of Mouse Liver AllograftAMERICAN JOURNAL OF TRANSPLANTATION, Issue 1 2010M. Morita The programmed death-1 (PD-1)/B7-H1 pathway acts as an important negative regulator of immune responses. We herein investigated the role of the PD-1/B7-H1 pathway in establishing an immunological spontaneous tolerance status in mouse liver allografting. B7-H1 is highly expressed on the donor-derived tissue cells and it is also associated with the apoptosis of infiltrating T cells in the allografts. Strikingly, a blockade of the PD-1/B7-H1 pathway via anti-B7-H1mAb or using B7-H1 knockout mice as a donor led to severe cell infiltration as well as hemorrhaging and necrosis, thus resulting in mortality within 12 days. Furthermore, the expression of the FasL, perforin, granzyme B, iNOS and OPN mRNA in the liver allografts increased in the antibody-treated group in comparison to the controls. Taken together, these data revealed that the B7-H1 upregulation on the tissue cells of liver allografts thus plays an important role in the apoptosis of infiltrating cells, which might play a critical role of the induction of the spontaneous tolerance after hepatic transplantation in mice. [source] Evaluation of Process-Induced Dimensional Changes in the Membrane Structure of Biological Cells Using Impedance MeasurementBIOTECHNOLOGY PROGRESS, Issue 3 2002Alexander Angersbach The impact of high intensity electric field pulses, high hydrostatic pressure, and freezing-thawing on local structural changes of the membrane was determined for potato, sugar beet tissue, and yeast suspensions. On the basis of the electrophysical model of cell systems in biological tissues and suspensions, a method was derived for determining the extent of local damage of cell membranes. The method was characterized by an accurate and rapid on-line determination of frequency-dependent electrical conductivity properties from which information on microscopic events on cellular level may be deduced. Evaluation was based on the measurement of the relative change in the sampleapos;s impedance at characteristically low ( fl) and high ( fh) frequencies within the ,-dispersion range. For plant and animal cells the characteristic frequencies were fl , 5 kHz and fh > 5 MHz and for yeast cells in the range fl , 50 kHz and fh > 25 MHz. The observed phenomena were complex. The identification of the underlying mechanisms required consideration of the time-dependent nature of the processing effects and stress reactions of the biological systems, which ranged from seconds to several hours. A very low but significantly detectable membrane damage (0.004% of the total area) was found after high hydrostatic pressure treatment of potato tissue at 200 MPa. The membrane rupture in plant tissue cells was higher after freezing and subsequent thawing (0.9% of total area for potato cells and 0.05,0.07% for sugar beet cells determined immediately after thawing), which increased substantially during the next 2 h. [source] Expression of insulin-like growth factor-I in lesional and non-lesional skin of patients with morphoeaBRITISH JOURNAL OF DERMATOLOGY, Issue 1 2008M.M.T. Fawzi Summary Background, Morphoea (scleroderma) is a chronic disorder characterized by circumscribed sclerotic plaques with the hallmark of increased fibroblast activation and fibrosis. Through its effect on connective tissue cells and immune cells, insulin-like growth factor (IGF)-I has been found to play a role in some autoimmune connective tissue diseases and has been implicated in the pathogenesis of several fibrotic disorders. Objectives, To evaluate the role of IGF-I in the pathogenesis of morphoea. Methods, The study was carried out on 15 patients with morphoea and nine healthy controls. Two 5-mm punch skin biopsies were taken from every patient (one from lesional and one from non-lesional skin) and a single biopsy was taken from the normal skin of each control. A 10-mL blood sample was also taken from each patient and control. Quantitative detection of tissue and serum levels of IGF-I was done using an enzyme-linked immunosorbent assay technique. Results, IGF-I in lesional skin was significantly higher than in non-lesional and control skin (P = 0·001 and P = 0·021, respectively). Moreover, a significantly higher level of IGF-I was detected in patient serum when compared with control serum (P < 0·001). A direct significant correlation existed between lesional and non-lesional skin level (r = 0·618, P = 0·014), and between lesional skin level and Rodnan score (r = 0·538, P = 0·039). Conclusions, Despite the small sample size, this study suggests that IGF-I plays an important role in the pathogenesis of fibrosis, characteristic of morphoea. Studies on a larger number of patients with morphoea as well as on patients with systemic sclerosis are recommended. Furthermore, therapeutic trials using IGF-I antagonist (octreotide) are highly recommended in patients with morphoea. [source] Ultrastructural study of tissues surrounding replanted teeth and dental implantsCLINICAL ORAL IMPLANTS RESEARCH, Issue 3 2009Kazuhiro Shioya Abstract Objectives: The aim of this study was to describe the ultrastructure of the dentogingival border at replanted teeth and implants. Material and methods: Wistar rats (8 weeks old) were divided into groups for replantation and implantation experiments. In the former, the upper right first molars were extracted and then immediately replanted. In the latter, pure titanium implants were used. All tissues were fixed, demineralized and embedded in epoxy resin for ultrastructural observations. Results: One week after replantation, the junctional epithelium was lost, and the oral sulcular epithelium covered the enamel surface. The amount of the epithelium increased in 2 weeks, and resembled the junctional epithelium, and the internal basal lamina and hemidesmosomes were formed in 4 weeks. One week after implantation, peri-implant epithelium was formed, and in 2 and 4 weeks, this epithelium with aggregated connective tissue cells were observed. In 8 weeks, the peri-implant epithelium receded, and aligned special cells with surrounding elongated fibroblasts and bundles of collagen fibers appeared to seal the implant interface. Conclusion: In replantation of the tooth, the internal basal lamina remained at the surface of the enamel of the replanted tooth, which is likely to be related to regeneration of the junctional epithelium and the attachment apparatus at the epithelium,tooth interface. Following implantation, a layer of cells with characteristics of connective tissue cells, but no junctional epithelium and attachment apparatus, was formed to seal the site of the implant. [source] | |||||||||||||||||||||||||