Journal articles on the topic 'Tissue surface density'
To see the other types of publications on this topic, follow the link: Tissue surface density.
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 journal articles for your research on the topic 'Tissue surface density.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse journal articles on a wide variety of disciplines and organise your bibliography correctly.
1
FLORES, ROLANDO A., MARK L. TAMPLIN, BENNE S. MARMER, JOHN G. PHILLIPS, and PETER H. COOKE. "Transfer Coefficient Models for Escherichia coli O157:H7 on Contacts between Beef Tissue and High-Density Polyethylene Surfaces†." Journal of Food Protection 69, no. 6 (June 1, 2006): 1248–55. http://dx.doi.org/10.4315/0362-028x-69.6.1248.
Full textAbstract:
Risk studies have identified cross-contamination during beef fabrication as a knowledge gap, particularly as to how and at what levels Escherichia coli O157:H7 transfers among meat and cutting board (or equipment) surfaces. The objectives of this study were to determine and model transfer coefficients (TCs) between E. coli O157:H7 on beef tissue and high-density polyethylene (HDPE) cutting board surfaces. Four different transfer scenarios were evaluated: (i) HDPE board to agar, (ii) beef tissue to agar, (iii) HDPE board to beef tissue to agar, and (iv) beef tissue to HDPE board to agar. Also, the following factors were studied for each transfer scenario: two HDPE surface roughness levels (rough and smooth), two beef tissues (fat and fascia), and two conditions of the initial beef tissue inoculation with E. coli O157:H7 (wet and dry surfaces), for a total of 24 treatments. The TCs were calculated as a function of the plated inoculum and of the cells recovered from the first contact. When the treatments were compared, all of the variables evaluated interacted significantly in determining the TC. An overall TC-per-treatment model did not adequately represent the reduction of the cells on the original surface after each contact and the interaction of the factors studied. However, an exponential model was developed that explained the experimental data for all treatments and represented the recontamination of the surfaces with E. coli O157:H7. The parameters for the exponential model for cross-contamination with E. coli O157:H7 between beef tissue and HDPE surfaces were determined, allowing for the use of the resulting model in quantitative microbial risk assessment.
2
Turiv, Taras, Jess Krieger, Greta Babakhanova, Hao Yu, Sergij V. Shiyanovskii, Qi-Huo Wei, Min-Ho Kim, and Oleg D. Lavrentovich. "Topology control of human fibroblast cells monolayer by liquid crystal elastomer." Science Advances 6, no. 20 (May 2020): eaaz6485. http://dx.doi.org/10.1126/sciadv.aaz6485.
Full textAbstract:
Eukaryotic cells in living tissues form dynamic patterns with spatially varying orientational order that affects important physiological processes such as apoptosis and cell migration. The challenge is how to impart a predesigned map of orientational order onto a growing tissue. Here, we demonstrate an approach to produce cell monolayers of human dermal fibroblasts with predesigned orientational patterns and topological defects using a photoaligned liquid crystal elastomer (LCE) that swells anisotropically in an aqueous medium. The patterns inscribed into the LCE are replicated by the tissue monolayer and cause a strong spatial variation of cells phenotype, their surface density, and number density fluctuations. Unbinding dynamics of defect pairs intrinsic to active matter is suppressed by anisotropic surface anchoring allowing the estimation of the elastic characteristics of the tissues. The demonstrated patterned LCE approach has potential to control the collective behavior of cells in living tissues, cell differentiation, and tissue morphogenesis.
3
Lulli, Filippo, Claudia de Bertoldi, Roberto Armeni, Lorenzo Guglielminetti, and Marco Volterrani. "Warm-season Turfgrass Species Generate Sports Surfaces with Different Playability." HortTechnology 24, no. 6 (December 2014): 749–56. http://dx.doi.org/10.21273/horttech.24.6.749.
Full textAbstract:
Synthetic sports surfaces are increasingly subject to standardization of athlete-surface and ball-surface interactions (playability parameters). Such standardizations have led to an increase in the level of the engineering and predictability of these surfaces, and as such may be beneficial also for natural turf. In warm and temperate climates, many natural turf sports surfaces are established with warm-season (C4) turfgrass species due to their suitability to the environment in such areas. This study was aimed at evaluating the Féderation Internationale de Football Association (FIFA)-standard playing characteristics of different sports turf surfaces obtained from three commonly used C4 turfgrass species: 1) ‘Tifway 419’ hybrid bermudagrass (Cynodon dactylon var. dactylon × C. transvaalensis), 2) ‘Zeon’ manilagrass (Zoysia matrella), and 3) ‘Salam’ seashore paspalum (Paspalum vaginatum) for factors concerning leaf tissue (silica, lignin, water content) and canopy structure (shoot density, leaf architecture, stolon density, etc.). Results showed that surfaces of different C4 turfgrass species generate different playability parameters, with seashore paspalum being a harder faster surface, manilagrass being a softer slower surface, and hybrid bermudagrass showing intermediate characteristics. These playing quality results were associated with certain specific canopy biometrical/morphological parameters such as shoot density, horizontal stem density (HSD), leaf section, and, to a lesser extent, to certain plant tissue compounds (lignin, silica).
4
Kochová, Petra, Tomáš Gregor, Eva Prosecká, Lada Eberlová, and Zbyněk Tonar. "Multiscale Heterogeneity of Bone Microporosities and Tissue Scaffolds." Key Engineering Materials 592-593 (November 2013): 350–53. http://dx.doi.org/10.4028/www.scientific.net/kem.592-593.350.
Full textAbstract:
Our aim was to use stereology to quantify the volume fraction of osteocyte lacunes, volume fraction of large blood vessels, numerical density of osteocyte lacunes, volume of osteocyte lacunae and bone surface in series of micro-CT images representing samples of spongy and compact bone of human tibia. The spongy bone had a smaller volume fraction of osteocyte lacunes, a greater numerical density of bone lacunes, a smaller volume of the lacunes within the same bone volume and a greater bone surface density when compared to the compact bone. Stereology provided us with data on hierarchical organization of bone structural heterogeneity with reasonable time costs.
5
Brunette, D. M., and B. Chehroudi. "The Effects of the Surface Topography of Micromachined Titanium Substrata on Cell Behavior in Vitro and in Vivo." Journal of Biomechanical Engineering 121, no. 1 (February 1, 1999): 49–57. http://dx.doi.org/10.1115/1.2798042.
Full textAbstract:
Surface properties, including topography and chemistry, are of prime importance in establishing the response of tissues to biomaterials. Microfabrication techniques have enabled the production of precisely controlled surface topographies that have been used as substrata for cells in culture and on devices implanted in vivo. This article reviews aspects of cell behavior involved in tissue response to implants with an emphasis on the effects of topography. Microfabricated grooved surfaces produce orientation and directed locomotion of epithelial cells in vitro and can inhibit epithelial downgrowth on implants. The effects depend on the groove dimensions and they are modified by epithelial cell–cell interactions. Fibroblasts similarly exhibit contact guidance on grooved surfaces, but fibroblast shape in vitro differs markedly from that found in vivo. Surface topography is important in establishing tissue organization adjacent to implants, with smooth surfaces generally being associated with fibrous tissue encapsulation. Grooved topographies appear to have promise in reducing encapsulation in the short term, but additional studies employing three-dimensional reconstruction and diverse topographies are needed to understand better the process of connective-tissue organization adjacent to implants. Microfabricated surfaces can increase the frequency of mineralized bone-like tissue nodules adjacent to subcutaneously implanted surfaces in rats. Orientation of these nodules with grooves occurs both in culture and on implants. Detailed comparisons of cell behavior on micromachined substrata in vitro and in vivo are difficult because of the number and complexity of factors, such as population density and micromotion, that can differ between these conditions.
6
Moriwaki, Takeshi, Tomonori Oie, Keiichi Takamizawa, Yoshinobu Murayama, Toru Fukuda, Sadao Omata, and Yasuhide Nakayama. "Surface density mapping of natural tissue by a scanning haptic microscope (SHM)." Journal of Medical Engineering & Technology 37, no. 2 (January 30, 2013): 96–101. http://dx.doi.org/10.3109/03091902.2012.747008.
Full text
7
Mujkić, Robert, Darija Šnajder Mujkić, Ivana Ilić, Edi Rođak, Antun Šumanovac, Anđela Grgić, Dalibor Divković, and Kristina Selthofer-Relatić. "Early Childhood Fat Tissue Changes—Adipocyte Morphometry, Collagen Deposition, and Expression of CD163+ Cells in Subcutaneous and Visceral Adipose Tissue of Male Children." International Journal of Environmental Research and Public Health 18, no. 7 (March 31, 2021): 3627. http://dx.doi.org/10.3390/ijerph18073627.
Full textAbstract:
Childhood obesity is a complex health problem, and not many studies have been done on adipose tissue remodeling in early childhood. The aim of this study was to examine extracellular matrix remodeling in the adipose tissue of healthy male children depending on their weight status. Subcutaneous and visceral adipose tissue was obtained from 45 otherwise healthy male children who underwent elective surgery for hernia repairs or orchidopexy. The children were divided into overweight/obese (n = 17) or normal weight groups (n = 28) depending on their body mass index (BMI) z-score. Serum was obtained for glucose, testosterone, triglyceride, total cholesterol, high-density lipoprotein (HDL), and low-density lipoprotein (LDL) measurements. Sections of adipose tissue were stained with hematoxylin and eosin to determine the adipocytes’ surface area, and Masson’s trichrome stain was used to detect the adipocytes’ collagen content. Immunohistochemistry for CD163+ cells was also performed. The results showed that male children in the overweight group had higher serum triglyceride levels, greater adipocyte surface area and collagen content in their subcutaneous adipose tissue, more crown-like structures in fat tissues, and more CD163+ cells in their visceral adipose tissue than males in the normal weight group. In conclusion, in male children, obesity can lead to the hypertrophy of adipocytes, increased collagen deposition in subcutaneous adipose tissues, and changes in the polarization and accumulation of macrophages.
8
Else, P. L., and A. J. Hulbert. "Mammals: an allometric study of metabolism at tissue and mitochondrial level." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 248, no. 4 (April 1, 1985): R415—R421. http://dx.doi.org/10.1152/ajpregu.1985.248.4.r415.
Full textAbstract:
Body composition, mitochondrial volume density, and mitochondrial membrane surface area were measured in six species of mammals representing a 100-fold weight range (18-2,067 g). The mammals examined included three eutherian species, two marsupial, and one monotreme species. The tissues examined were liver, kidney, brain, lung, heart, and skeletal muscle (gastrocnemius). Allometric equations were derived for tissue weight, and the allometric exponents ranged from 0.69 (brain) to 1.01 (skeletal muscle). Allometric relationships for mitochondrial membrane surface area were also determined both per milliliter tissue and per total tissue. Small mammals had a higher mitochondrial membrane surface area per milliliter tissue than large mammals in all tissues examined. These differences were significant in liver, kidney, brain, and heart. Total mitochondrial membrane surface area per tissue had allometric exponents ranging from 0.55 (kidney) to 0.78 (skeletal muscle). When total mitochondrial membrane surface area was summated for the major internal organs examined (liver, kidney, heart, and brain), the allometric equation was mitochondrial membrane surface area (m2) = 3.04 body wt0.59 (g). This was similar to the exponent of standard metabolic rate against body weight in the species examined (i.e., 0.62). The inclusion of skeletal muscle and lung into the summated mitochondrial membrane surface area increased the exponent to 0.76. This is compared with the relationship between maximal O2 consumption and body size in mammals.
9
Penn, Marc S., Mei-Zhen Cui, Allison L. Winokur, John Bethea, Thomas A. Hamilton, Paul E. DiCorleto, and Guy M. Chisolm. "Smooth muscle cell surface tissue factor pathway activation by oxidized low-density lipoprotein requires cellular lipid peroxidation." Blood 96, no. 9 (November 1, 2000): 3056–63. http://dx.doi.org/10.1182/blood.v96.9.3056.
Full textAbstract:
Abstract Tissue factor, which is expressed in vascular lesions, increases thrombin production, blood coagulation, and smooth muscle cell proliferation. We demonstrate that oxidized low-density lipoprotein (LDL) induces surface tissue factor pathway activity (ie, activity of the tissue factor:factor VIIa complex) on human and rat smooth muscle cells. Tissue factor messenger RNA (mRNA) was induced by oxidized LDL or native LDL; however, native LDL did not markedly increase tissue factor activity. We hypothesized that oxidized LDL mediated the activation of the tissue factor pathway via an oxidant-dependent mechanism, because antioxidants blocked the enhanced tissue factor pathway activity by oxidized LDL, but not the increased mRNA or protein induction. We separated total lipid extracts of oxidized LDL using high-performance liquid chromatography (HPLC). This yielded 2 major peaks that induced tissue factor activity. Of the known oxysterols contained in the first peak, 7α- or 7β-hydroxy or 7-ketocholesterol had no effect on tissue factor pathway activity; however, 7β-hydroperoxycholesterol increased tissue factor pathway activity without induction of tissue factor mRNA. Tertiary butyl hydroperoxide also increased tissue factor pathway activity, suggesting that lipid hydroperoxides, some of which exist in atherosclerotic lesions, activate the tissue factor pathway. We speculate that thrombin production could be elevated via a mechanism involving peroxidation of cellular lipids, contributing to arterial thrombosis after plaque rupture. Our data suggest a mechanism by which antioxidants may offer a clinical benefit in acute coronary syndrome and restenosis.
10
Penn, Marc S., Mei-Zhen Cui, Allison L. Winokur, John Bethea, Thomas A. Hamilton, Paul E. DiCorleto, and Guy M. Chisolm. "Smooth muscle cell surface tissue factor pathway activation by oxidized low-density lipoprotein requires cellular lipid peroxidation." Blood 96, no. 9 (November 1, 2000): 3056–63. http://dx.doi.org/10.1182/blood.v96.9.3056.h8003056_3056_3063.
Full textAbstract:
Tissue factor, which is expressed in vascular lesions, increases thrombin production, blood coagulation, and smooth muscle cell proliferation. We demonstrate that oxidized low-density lipoprotein (LDL) induces surface tissue factor pathway activity (ie, activity of the tissue factor:factor VIIa complex) on human and rat smooth muscle cells. Tissue factor messenger RNA (mRNA) was induced by oxidized LDL or native LDL; however, native LDL did not markedly increase tissue factor activity. We hypothesized that oxidized LDL mediated the activation of the tissue factor pathway via an oxidant-dependent mechanism, because antioxidants blocked the enhanced tissue factor pathway activity by oxidized LDL, but not the increased mRNA or protein induction. We separated total lipid extracts of oxidized LDL using high-performance liquid chromatography (HPLC). This yielded 2 major peaks that induced tissue factor activity. Of the known oxysterols contained in the first peak, 7α- or 7β-hydroxy or 7-ketocholesterol had no effect on tissue factor pathway activity; however, 7β-hydroperoxycholesterol increased tissue factor pathway activity without induction of tissue factor mRNA. Tertiary butyl hydroperoxide also increased tissue factor pathway activity, suggesting that lipid hydroperoxides, some of which exist in atherosclerotic lesions, activate the tissue factor pathway. We speculate that thrombin production could be elevated via a mechanism involving peroxidation of cellular lipids, contributing to arterial thrombosis after plaque rupture. Our data suggest a mechanism by which antioxidants may offer a clinical benefit in acute coronary syndrome and restenosis.
11
HOVENBERG, Hans W., Ingemar CARLSTEDT, and Julia R. DAVIES. "Mucus glycoproteins in bovine trachea: identification of the major mucin populations in respiratory secretions and investigation of their tissue origins." Biochemical Journal 321, no. 1 (January 1, 1997): 117–24. http://dx.doi.org/10.1042/bj3210117.
Full textAbstract:
Bovine respiratory secretions were separated into gel and sol phases to allow the identification of the gel-forming mucins. Mucins were subsequently isolated from the surface epithelium and submucosal tissue to investigate the tissue origins of the species in the secretions. Density-gradient centrifugation revealed ‘high-density’ and ‘low-density’ mucins in the gel phase of the secretions. The ‘high-density’ mucins were large, composed of subunits joined by disulphide bonds and contained two highly glycosylated domains of apparently different lengths, whereas the ‘low-density’ mucins were smaller and monomeric. The sol also contained both ‘high-density’ and ‘low-density’ species. A ‘high-density’ mucin similar to that in the gel was isolated from the surface epithelium, suggesting that the goblet cells produce large, gel-forming mucins. A second ‘high-density’ species was released from the submucosal tissue after reduction/alkylation, indicating that large mucins from the submucosal glands may also be a component of the mucus gel. In addition, two small, ‘low-density’ mucins were obtained from the submucosal tissue. One species was associated with the gel phase but was also present in the sol, whereas the other was present only in the sol. Bovine respiratory-tract secretions thus comprise a complex mixture of large gel-forming mucins originating from the goblet cells and submucosal glands, and smaller ‘soluble’ species from the submucosal glands which may interact with the gel.
12
Furuhashi, Akihiro, Yasunori Ayukawa, Ikiru Atsuta, Yunia Dwi Rakhmatia, Noriyuki Yasunami, and Kiyoshi Koyano. "Influence of Titanium Surface Topography on Peri-Implant Soft Tissue Integration." Key Engineering Materials 529-530 (November 2012): 559–64. http://dx.doi.org/10.4028/www.scientific.net/kem.529-530.559.
Full textAbstract:
At the neck area of dental implant surface, machined surface (Ms) has been employed to avoid surface contamination. Recently, implants which have roughened surface texture (Rs) at their neck are also available. However, from the viewpoint of soft tissue integration, it remains to be elucidated whether or not surface topography affects the soft tissue attachment around implants. The aim of the present study was to clarify the influence of surface topography on peri-implant soft tissue integration. First, surface roughness of both surfaces was measured. Second, protein adsorption capability on both surfaces was examined. Then, as the rat implant model, titanium implants with each surface were inserted into the maxillae. Horseradish peroxidase (HRP) tracer was applied 4 weeks post implantation to the gingival sulci of implants or natural teeth (NT) to investigate the sealing capability of periodontal/peri-implant soft tissue. Collagen density was also observed by fluorescent staining. As a result, surface roughness (Sa) of Ms and Rs was 0.16 µm and 0.25 µm, respectively. Protein adsorption capability on both surface showed no significant differences. In the NT group of the rat implant model, presence of HRP was restricted only in the coronal portion of epithelium. In both implant groups, in contrast, more invasion of HRP was observed in the soft tissue around implants. Especially in the Ms group, more HRP was observed in the deeper area compared with Rs group. Stronger expression of collagen was observed around Rs compared to Ms at the connective tissue-implant interface. It could be speculated that, with dense collagen, Rs implants showed stronger soft tissue integration compared with Ms implants, but the integration is not as strong as NT’s.
13
Huang, Xinglu, Jane Chisholm, Jie Zhuang, Yanyu Xiao, Gregg Duncan, Xiaoyuan Chen, Jung Soo Suk, and Justin Hanes. "Protein nanocages that penetrate airway mucus and tumor tissue." Proceedings of the National Academy of Sciences 114, no. 32 (July 24, 2017): E6595—E6602. http://dx.doi.org/10.1073/pnas.1705407114.
Full textAbstract:
Reports on drug delivery systems capable of overcoming multiple biological barriers are rare. We introduce a nanoparticle-based drug delivery technology capable of rapidly penetrating both lung tumor tissue and the mucus layer that protects airway tissues from nanoscale objects. Specifically, human ferritin heavy-chain nanocages (FTn) were functionalized with polyethylene glycol (PEG) in a unique manner that allows robust control over PEG location (nanoparticle surface only) and surface density. We varied PEG surface density and molecular weight to discover PEGylated FTn that rapidly penetrated both mucus barriers and tumor tissues in vitro and in vivo. Upon inhalation in mice, PEGylated FTn with optimized PEGylation rapidly penetrated the mucus gel layer and thus provided a uniform distribution throughout the airways. Subsequently, PEGylated FTn preferentially penetrated and distributed within orthotopic lung tumor tissue, and selectively entered cancer cells, in a transferrin receptor 1-dependent manner, which is up-regulated in most cancers. To test the potential therapeutic benefits, doxorubicin (DOX) was conjugated to PEGylated FTn via an acid-labile linker to facilitate intracellular release of DOX after cell entry. Inhalation of DOX-loaded PEGylated FTn led to 60% survival, compared with 10% survival in the group that inhaled DOX in solution at the maximally tolerated dose, in a murine model of malignant airway lung cancer. This approach may provide benefits as an adjuvant therapy combined with systemic chemo- or immunotherapy or as a stand-alone therapy for patients with tumors confined to the airways.
14
Moretti, Celso L., Steven A. Sargent, Donald J. Huber, and Rolf Puschmann. "Internal Bruising Affects Chemical and Physical Composition of Tomato Fruit." HortScience 32, no. 3 (June 1997): 522C—522. http://dx.doi.org/10.21273/hortsci.32.3.522c.
Full textAbstract:
Tomato (Lycopersicon esculentum L.) fruits, cv. Solarset, were harvested at the mature-green stage and treated with 50 μL/L ethylene at 20C. Breaker fruits (<10% red coloration) were dropped from 40 cm onto a smooth, solid surface and held along with undropped fruits at 20°C and 85% relative humidity. At table-ripe stage, pericarp, placental, and locular tissue were individually excised and analyzed for total carotenoids, total soluble sugars, soluble solids content, titratable acidity, density (locule tissue), polygalacturonase activity, and electrolyte efflux (pericarp tissue). Internal bruising caused by impact forces significantly affected pericarp and locule tissues, but not placental tissue. For bruised locule tissue, total carotenoids content decreased by 37.1%, vitamin C content by 15.6%, and titratable acidity by 15.3% as compared to control. However, density was increased by 3.0%. For bruised pericarp tissue, vitamin C content decreased by 16.5%, while polygalacturonase activity and electrolyte efflux increased by 33.3% and 24.8%, respectively. The development of abnormal ripening following an impact was confined to locule and pericarp tissues and appears to be related to the disruption of cellular structure and stimulation of enzymic activity.
15
Váradi, Katalin, Jürgen Siekmann, Peter Turecek, H. Peter Schwarz, and Victor Marder. "Phospholipid-bound Tissue Factor Modulates both Thrombin Generation and APC-mediated Factor Va Inactivation." Thrombosis and Haemostasis 82, no. 12 (1999): 1673–79. http://dx.doi.org/10.1055/s-0037-1614898.
Full textAbstract:
SummaryHemostasis is initiated by tissue factor (TF) exposed on cellular phospholipid (PL) membranes, leading to thrombin generation. The binding of thrombin to thrombomodulin (TM), activates the protein C pathway, resulting in the inactivation of factors Va and VIIIa by activated protein C (APC) and a negative feedback effect on thrombin generation. A new assay system was developed for simultaneous measurement of thrombin and APC generation in defibrinated plasma induced by large unilamellar PL vesicles complexed with full-length recombinant TF (TF:PL). TF:PL preparations with a low TF concentration induced an initial rate of thrombin generation below 100 nM/min, and resulted in less thrombin formation in the presence of TM than in its absence. In contrast, TF:PL preparations with a high concentration of TF induced a higher rate of thrombin generation, and APC-mediated feedback inhibition did not occur, despite maximal APC generation. We used the same TF:PL surfaces to study factor Va inactivation by APC in a non-plasma reaction system, and found an inverse correlation between TF surface density and the rate of factor Va inactivation. This observation suggests a previously unrecognized hemostatic effect of TF, namely a non-enzymatic surface density-based inhibition of the anticoagulant effect of APC. In this model, high concentrations and surface density of TF exert complementary effects by promoting the regular procoagulant cascade and by inhibiting the protein C pathway, thereby maximizing hemostasis after vascular injury.
16
Mitrophanov, Alexander Y., Vijay Govindarajan, Shu Zhu, Scott L. Diamond, and Jaques Reifman. "Computational Modeling and Microfluidics Reveal Characteristic Patterns of Regulation of Clot Structure and Mechanics By Tissue Factor Localization." Blood 132, Supplement 1 (November 29, 2018): 1164. http://dx.doi.org/10.1182/blood-2018-99-111542.
Full textAbstract:
Abstract The growth of a blood clot is initiated by tissue factor (TF) exposure and is expected to depend on TF localization (i.e., its level and spatial distribution). We sought to understand how the structural and mechanical properties of clots under flow are shaped by simultaneously varying the surface density of TF and its area of exposure. We used a microfluidic device harboring thrombogenic surfaces that differed in length and TF surface density. We perfused human whole blood through this device and continually measured platelet deposition, thrombin formation, and fibrin accumulation by means of fluorescence microscopy. Using our recently developed, detailed mathematical model of spatial clot growth under flow, we performed computational simulations to gain insights into the connection between the structure of a clot and its mechanical properties, such as resistance to blood flow and flow axial velocity. We detected a non-additive, synergistic influence of the thrombogenic surface length and TF surface density on bulk thrombin and fibrin generation. We found that thrombogenic surface length and TF density controlled not only bulk accumulation, but also the occlusivity of the deposited platelet mass, as well as clot resistance to flow. The extent of this control depended on the blood flow velocity. An increase in the TF surface density resulted in condition-dependent differential acceleration of platelet deposition, thrombin formation, and fibrin accumulation. The viscous resistance of the clot was characterized by spatial variations and was higher in the inner clot region. Notably, despite variations in the intraclot structure, variations in the intraclot flow velocity were minor compared to the abrupt decrease in flow velocity at the boundary of the platelet deposition domain. Our analysis revealed characteristic patterns that describe how the shape, size, internal structure, and viscous resistance of a clot depend on the surface density of TF and its area of exposure. Taken together, our results suggest that the structure and mechanics of a growing clot are correlated, but can differ in their regulation by the distinct aspects of TF localization. These findings provide new insights into how initiating signals can temporally and spatially affect thrombus growth under flow. DISCLAIMER: The opinions and assertions contained herein are the private views of the authors and are not to be construed as official or as reflecting the views of the U.S. Army or of the U.S. Department of Defense. This abstract has been approved for public release with unlimited distribution. Disclosures No relevant conflicts of interest to declare.
17
Antonini, L. M., Karine Parise, A. R. S. Witt, Israel Durli Savaris, L. Gustavo, and Célia de Fraga Malfatti. "Nanostructured Titanium Surface Obtained by Electrochemical Treatment." Materials Science Forum 775-776 (January 2014): 19–23. http://dx.doi.org/10.4028/www.scientific.net/msf.775-776.19.
Full textAbstract:
Research on titanium and its alloys as biomaterials have been attracted the interest because of its clinical success, but they have been facing problems due to failures caused by tissue cohesion loss, fracture. Studies involving the influence of surface roughness of titanium implants on the osseointegration rate and biomechanical fixation have been develop. However, it is neessary to understand the effect of surface morphology on the osseointegration process. This paper aims to examine the effect of current density on the electropolishing process of Ti in order to obtain nanostructured surfaces. Ti samples were mechanically abraded and then subjected to electropolishing in acidic solution. After the electropolishing process, the samples were characterized by atomic force microscopy, profilometry and wettability tests. Preliminary results show that the increase on current density contributed to the decrease in nanoroughness of substrate yet it did not affect the surface wettability, which presented an hydrophilic behaviour.
18
Jarnik, M., M. N. Simon, and A. C. Steven. "Cornified cell envelope assembly: a model based on electron microscopic determinations of thickness and projected density." Journal of Cell Science 111, no. 8 (April 15, 1998): 1051–60. http://dx.doi.org/10.1242/jcs.111.8.1051.
Full textAbstract:
In stratifying squamous epithelia, the cornified cell envelope (CE), a peripheral layer of crosslinked protein, is assembled sequentially from precursor proteins initially dispersed in the cytoplasm. Its major component is loricrin (37 kDa in mouse), which contributes from approx. 60% to >80% of the protein mass in different tissues. Despite its importance to the mechanical resilience and impenetrability of these tissues, detailed information has not been obtained on CE structure, even on such basic properties as its thickness or uniformity across a given CE or from tissue to tissue. To address this issue, we have studied CEs isolated from three murine epithelia, namely epidermis, forestomach and footpad, by electron microscopy of metal-shadowed specimens and scanning transmission electron microscopy (STEM) of unstained specimens. The former data reveal that the cytoplasmic surface is smoothly textured whereas the extracellular surface is corrugated, and that the average thickness is 15.3+/−1.2 nm, and strikingly uniform. Measurements of mass-per-unit-area from the STEM images yielded values of approx. 7.0+/−0.8 kDa/nm2, which were remarkably consistent over all three tissues. These data imply that the mature CE has a uniquely defined thickness. To explain its uniformity, we postulate that loricrin forms a molecular monolayer, not a variable number of multiple layers. In this scenario, the packing density is one loricrin monomer per 7 nm2, and loricrin should have an elongated shape, 2.5-3.0 nm wide by approx. 11 nm long. Moreover, we anticipate that any inter-tissue variations in the mechanical properties of CEs should depend more on protein composition and cross-linking pattern than on the thickness of the protein layer deposited.
19
NORDMAN, Henrik, Julia R. DAVIES, and Ingemar CARLSTEDT. "Mucus glycoproteins from pig gastric mucosa: different mucins are produced by the surface epithelium and the glands." Biochemical Journal 331, no. 3 (May 1, 1998): 687–94. http://dx.doi.org/10.1042/bj3310687.
Full textAbstract:
An antibody (PGM2B) recognizing a pig gastric-mucin apoprotein reacts with the surface epithelium of pig gastric mucosa. Virtually no reactivity was observed over the mucin-producing cells in the glands, which were recognized by the GlcNAc-selective Griffonia simplicifoliaII (GSA-II) lectin. Mucins from the glandular tissue of the cardiac region, corpus and antrum were purified using isopycnic density-gradient centrifugation in CsCl/guanidinium chloride. In the cardiac region, two major mucin populations at 1.5 and 1.4 g/ml were identified. The high-density population reacted preferentially with the PGM2B antibody and resembled mucins from the surface epithelium of this region, whereas the low-density population reacted strongly with the GSA-II lectin and appeared to originate from the glands. In the glandular tissue of corpus, a component with strong GSA-II lectin reactivity, which was distinctly different from the surface mucins from this region, was found at 1.4 g/ml, thus resembling the gland component from the cardiac region. Mucins from antrum glandular tissue contained at least two GSA-II lectin-reactive populations banding at 1.5 and 1.4 g/ml, respectively. Gland mucins from all regions were large oligomeric glycoproteins and heterogeneous with respect to charge properties, as shown by using rate-zonal centrifugation and ion-exchange HPLC, respectively. Gel chromatography of mucin glycopeptides showed that gland mucins from antrum and corpus contained significantly longer glycosylated domains than those from the surface mucosa. Thus, mucins from pig gastric glandular tissue comprise a number of large and oligomeric glycoproteins that differ from those from the surface epithelium in buoyant density, apoprotein structure and carbohydrate substitution.
20
Tsatas, Dina, Mark S. Baker, and Gregory E. Rice. "Tissue-specific Expression of the Relaxed Conformation of Plasminogen Activator Inhibitor-2 and Low-density Lipoprotein Receptor-related Protein in Human Term Gestational Tissues." Journal of Histochemistry & Cytochemistry 45, no. 12 (December 1997): 1593–602. http://dx.doi.org/10.1177/002215549704501202.
Full textAbstract:
The relaxed conformation of plasminogen activator inhibitor-2 (PAIr) is formed during inactivation of the matrix-degrading enzyme urokinase plasminogen activator (uPA). The presence of PAIr in tissues, therefore, indicates the in situ inhibition of uPA-mediated proteolysis. In addition, PAIr functions as a ligand for the clearance receptor low-density lipoprotein receptor-related protein (LRP), thereby promoting internalization of receptor-bound uPA-PAIr complexes from the cell surface. The rapid internalization of receptor-bound, inactivated uPA has been suggested to be characteristic of invasive cell phenotypes. The aims of this study were to characterize the immunohistochemical localization of PAIr in human term gestational tissues (amnion, choriodecidua, and placenta) and to establish its co-expression with other components of the uPA cascade. The results obtained indicate that PAIr immunoreactivity was exclusively localized to amnion epithelial cells, with only minimal staining in the underlying chorion. PAIr immunoreactivity was not detectable in any of the trophoblastic tissues examined (villous and extravillous). The tissue-specific expression of PAIr immunoreactivity was not significantly altered in association with labor onset. uPA and PAI-2 staining was localized predominantly to amnion epithelial cells, underlying chorion, and trophoblast cells of villous and extravillous tissue. Amnion and trophoblasts of extravillous and chorionic tissue showed uPAR immunoreactivity, whereas staining in placenta was absent. Immunoreactive LRP was confined to trophoblasts of the chorion, and the villous and extravillous tissue. For the first time, localization of PAIr at the tissue level has been identified. The data obtained are consistent with the hypothesis that cells of invasive phenotype, although expressing all components of the uPA cascade, do not accumulate immunoreactive PAIr, because it is rapidly internalized from the cell surface. Conversely, cells of noninvasive phenotype will accumulate PAIr immunoreactivity only in the absence of LRP expression. We propose that the presence of PAIr and the absence of LRP at the cell surface are putative markers of noninvasive phenotypes.
21
Sapudom, Jiranuwat, Walaa Kamal E. Mohamed, Anna Garcia-Sabaté, Aseel Alatoom, Shaza Karaman, Nikhil Mahtani, and Jeremy C. M. Teo. "Collagen Fibril Density Modulates Macrophage Activation and Cellular Functions during Tissue Repair." Bioengineering 7, no. 2 (March 31, 2020): 33. http://dx.doi.org/10.3390/bioengineering7020033.
Full textAbstract:
Monocytes circulate in the bloodstream, extravasate into the tissue and differentiate into specific macrophage phenotypes to fulfill the immunological needs of tissues. During the tissue repair process, tissue density transits from loose to dense tissue. However, little is known on how changes in tissue density affects macrophage activation and their cellular functions. In this work, monocytic cell line THP-1 cells were embedded in three-dimensional (3D) collagen matrices with different fibril density and were then differentiated into uncommitted macrophages (MPMA) using phorbol-12-myristate-13-acetate (PMA). MPMA macrophages were subsequently activated into pro-inflammatory macrophages (MLPS/IFNγ) and anti-inflammatory macrophages (MIL-4/IL-13) using lipopolysaccharide and interferon-gamma (IFNγ), and interleukin 4 (IL-4) and IL-13, respectively. Although analysis of cell surface markers, on both gene and protein levels, was inconclusive, cytokine secretion profiles, however, demonstrated differences in macrophage phenotype. In the presence of differentiation activators, MLPS/IFNγ secreted high amounts of IL-1β and tumor necrosis factor alpha (TNFα), while M0PMA secreted similar cytokines to MIL-4/IL-13, but low IL-8. After removing the activators and further culture for 3 days in fresh cell culture media, the secretion of IL-6 was found in high concentrations by MIL-4/IL-13, followed by MLPS/IFNγ and MPMA. Interestingly, the secretion of cytokines is enhanced with an increase of fibril density. Through the investigation of macrophage-associated functions during tissue repair, we demonstrated that M1LPS/IFNγ has the potential to enhance monocyte infiltration into tissue, while MIL-4/IL-13 supported fibroblast differentiation into myofibroblasts via transforming growth factor beta 1 (TGF-β1) in dependence of fibril density, suggesting a M2a-like phenotype. Overall, our results suggest that collagen fibril density can modulate macrophage response to favor tissue functions. Understanding of immune response in such complex 3D microenvironments will contribute to the novel therapeutic strategies for improving tissue repair, as well as guidance of the design of immune-modulated materials.
22
Moyes, Christopher D., Odile A. Mathieu-Costello, Richard W. Brill, and Peter W. Hochachka. "Mitochondrial metabolism of cardiac and skeletal muscles from a fast (Katsuwonus pelamis) and a slow (Cyprinus carpio) fish." Canadian Journal of Zoology 70, no. 6 (June 1, 1992): 1246–53. http://dx.doi.org/10.1139/z92-172.
Full textAbstract:
Tuna cardiac (atrium, compact and spongy ventricle) and skeletal muscle (red and white) were compared with carp tissues to determine the importance of mitochondrial differences in supporting the high aerobic capacities in tuna. Mitochondria isolated from red muscle of both species oxidized each of the physiological fuels at similar rates per milligram of mitochondrial protein, when differences in assay temperature are considered. The highest rate of oxygen consumption by ventricle mitochondria was 2 times greater in tuna than carp. The maximal oxidation rates were 3–4 times higher in ventricle than red muscle in both species. Tuna tissues had as much as 30–80% more mitochondrial protein per gram of tissue than carp. Morphometrically this was manifested as extremely densely packed mitochondrial cristae, rather than increased mitochondrial volume densities. In general, higher aerobic capacities of tuna ventricle and red muscle are primarily attributable to greater tissue mass and, to a lesser extent, differences in the nature or quantity of mitochondria per gram of tissue. Unlike ventricle and red muscle, tissues with relatively low mitochondrial contents in carp (white muscle, atrium) demonstrated several-fold higher mitochondrial contents in tuna. Enzyme analyses of tissue and isolated mitochondria suggest a greater dependence of tuna tissues on fatty acids as fuels. Activities of carnitine palmitoyl transferase (CPT) per milligram of protein were 2–2.5 times higher in tuna red muscle and ventricle mitochondria than in carp mitochondria from the same tissues. Whole tissue activity ratios of hexokinase/CPT, which indicate the relative importance of glucose and fatty acid metabolism, were 5 times higher in carp spongy ventricle and 12 times higher in carp compact ventricle. These data suggest that muscle aerobic capacity can be increased at several levels: tissue mass, mitochondrial volume density, cristae surface density, and mitochondrial specific activity. Large differences observed between carp and tuna muscles are due to cumulative effects of several of these factors.
23
Hsu, Y. L., C. H. Lee, S. M. Chiu, Y. C. Sung, K. Y. Yang, and C. W. Chu. "Anti-Sticking Properties of PVD CrWNx, CrOx and ZrOx Coatings on Medical Electrode Application." Defect and Diffusion Forum 297-301 (April 2010): 656–63. http://dx.doi.org/10.4028/www.scientific.net/ddf.297-301.656.
Full textAbstract:
The side effect of electrosurgery includes tissue charring, smoke generation and the adhesion of tissue to electrodes. These effects prolong surgery and interfere with effective coagulation. In this paper, CrWNx, CrOx and ZrOx coating were prepared by an unbalanced magnetron sputtering. The microstructure of films was characterized using XRD, XPS, TEM and AFM. The hydrophobicity and surface energy of coatings were calculated by contact angle measurement and Wu harmonic mean approach. Anti-sticking in vitro test was performed by monopolar electrosurgery using pork liver tissue. The hardness of CrWNx , ZrOx and CrOx coatings were 44 GPa, 26.3 GPa and 20.7 GPa, respectively. The CrOx coating had the lowest surface energy 33.5 mN/m and the highest contact angle of water as high as 103°. The high surface O-H bonds density of CrOx coating and N-H bonds density of CrWNx coating could explain about their lower polar component of surface energy. All the three PVD coatings remarkably reduced the quantity of tissue adhesion on the electrode from about 2 times (ZrOx and CrWNx coatings) to 4.88 times (CrOx coating) than uncoated SUS304 electrode.
24
Hirai, Jiro, and Takehisa Matsuda. "Self-Organized, Tubular Hybrid Vascular Tissue Composed of Vascular Cells and Collagen for Low-Pressure-Loaded Venous System." Cell Transplantation 4, no. 6 (November 1995): 597–608. http://dx.doi.org/10.1177/096368979500400609.
Full textAbstract:
A tubular, hierarchically structured hybrid vascular tissue composed of vascular cells and collagen was prepared. First, a cold mixed solution of bovine aortic smooth muscle cells (SMCs) and Type I collagen was poured into a tubular glass mold composed of a mandrel and a sheath (example of dimensions: inner diameter, 1.5 mm; outer diameter, 7 mm; length, 7 cm). Upon incubation at 37°C, an SMC-incorporated collagenous gel was formed. After the sheath was removed, the resulting fragile tissue, when cultured in medium, thinned in a time-dependent manner to form an opaque, dense tissue. Higher SMC seeding density and lower initial collagen concentration induced more rapid and prominent shrinkage of the tissue. Morphologic investigation showed that over time, bipolarly elongated SMCs and collagen fiber bundles became positioned around the mandrel. Both components became circumferentially oriented. When the mandrel was removed, a tubular hybrid medial tissue was formed. A hybrid vascular tissue with a hierarchical structure was constructed by seeding endothelial cells onto the inner surface of the hybrid medial tissue. Prepared tissues tolerated luminal pressures as great as 100 mmHg and mechanical stress applied during an anastomotic procedure. This method allowed us to prepare a tubular hybrid medial tissue of predetermined size (inner diameter, wail thickness, and length) by selecting appropriate mold design, initial collagen concentration, and SMC seeding density. Such hybrid vascular tissues may provide physiological functions when implanted into the venous system.
25
Shih, Ting-Yu, Jean-Dean Yang, Yu-Hua Chen, Chia-Wei Hong, Mei-Ju Yang, and Jui-Hsiang Chen. "DEVELOPMENT OF PEG-CONTAINING BRUSH COPOLYMER: THEIR EFFECT ON RESISTANCE TO PROTEIN ADSORPTION BEHAVIORS." Biomedical Engineering: Applications, Basis and Communications 25, no. 05 (October 2013): 1340008. http://dx.doi.org/10.4015/s1016237213400085.
Full textAbstract:
Polyethylene glycol (PEG) has been grafted onto surface of many medical devices to reduce or eliminate protein adsorption that often leads to infection or inflammatory responses. Besides commonly used surface activation strategies, here in this work, the novel functional brush copolymer poly (vinyl alcohol)-g-PEG-co-polyurethane (PVA-g-(PEG-co-PU)) was first synthesized, characterized, and evaluated. PVA is used here as a versatile backbone platform for grafting functional molecules. On the one hand, the PU molecules can attach to the surface of desired PU-based implants, on the other hand, the presence of densely grafted PEG at the materials–tissue interface effectively impedes nonspecific protein adsorption. These copolymers with various grafting ratio of PEG and PU were analyzed by Fourier transform infrared spectroscopy and gel permeation chromatography. The brush copolymers that were obtained were further coated on the PU surface and contact angle measurements were performed. It was found that the brush copolymers turn the surface more hydrophilic with increasing PEG grafting density. Furthermore, the effects of PEG ratio on protein adsorption-resistant behavior were investigated. Protein adsorption was found to be the lowest on the surfaces with the highest PEG grafting density on PVA backbone. The study demonstrated unique brush copolymer to work as a potentially useful coating material.
26
Xu, J., X. Zhou, H. Ge, and Y. Zhao. "Adhesion of endothelial cells using self-assembly peptides under precise deformation control of tissue-engineered vessels." Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine 221, no. 8 (August 1, 2007): 833–36. http://dx.doi.org/10.1243/09544119jeim163.
Full textAbstract:
The objective of this study was to anchor endothelial cells using self-assembly peptides under precise deformation control of tissue-engineered vessels. An acelluarized vascular matrix was used as the control group to examine the function of self-assembly peptides. In the experiment group, the self-assembly peptides were added to the inner surface of tissue-engineered vessels to form a monolayer. Then the endothelial cells were injected into the vascular lumen. A deformation control system was developed which was based on real-time image analysis and feedback control system. After dynamic culture by different deformation (set points 1, 5, and 10 per cent), the endothelial cell densities of experimental and control groups were compared. Both the self-assembly peptides and the extent of deformation affected the endothelial cell density on the inner surface of tissue-engineered vessels. The construct with self-assembly peptides under 5 per cent deformation gained the highest endothelial cell density. It was concluded that the deformation of assembled peptides contributes to the development and adhesion of endothelial cells in the inner surface of tissue-engineered vessels.
27
Otero-Marquez, Oscar, Mona Fayad, Alexander Pinhas, Toco Y. P. Chui, Richard B. Rosen, and Harsha S. Reddy. "Retinal Surface Macrophage Changes in Thyroid Eye Disease before and after Treatment with Teprotumumab." Case Reports in Ophthalmological Medicine 2022 (February 7, 2022): 1–5. http://dx.doi.org/10.1155/2022/5275309.
Full textAbstract:
Retinal surface macrophages play key roles in the regulation of immune response, maintenance of vitreous clarity, and tissue repair. We examined the variation of parafoveal surface macrophages in a thyroid eye disease (TED) patient before and after treatment with teprotumumab (Tepezza, Horizon therapeutics). Pre- and posttreatment parafoveal surface macrophages were imaged using clinical en face OCT, and their density was assessed using a novel cell density mapping technique. Pretreatment, surface macrophage cell density was high. Macrophages had a nonuniform spatial distribution, and their appearance was round with few protrusions, consistent with an “activated” state. Posttreatment, cell density decreased. The macrophages were regularly spaced and had a ramified appearance and filopodia-like processes, consistent with a “quiescent” state. Surface macrophage density decreased as the Clinical Activity Score (CAS) decreased with teprotumumab treatment, suggesting a potential association of these cells with an underlying intraocular and retinal inflammatory process previously not described in TED.
28
Zhou, Caiying, Juncheng Lu, and Xingsheng Wang. "Adhesion Behavior of Textured Electrosurgical Electrode in an Electric Cutting Process." Coatings 10, no. 6 (June 25, 2020): 596. http://dx.doi.org/10.3390/coatings10060596.
Full textAbstract:
Soft tissue adhesion on the electrosurgical electrode has been a major concern in clinical surgery. In order to improve the adhesion property of the electrode, micro-textures with different morphologies including micro-dimples, longitudinal micro-channels, and lateral micro-channels were created on the electrode surface by laser surface texturing (LST). Electric cutting experiments were then performed to investigate the adhesion behavior of different electrodes. Experimental results showed that the textured electrode surfaces could reduce the soft tissue adhesion significantly due to the effect of air in micro-textures and the reduction of contact area between the electrode and the soft tissue. Moreover, the temperature distribution of the electric cutting process was simulated through COMSOL to verify the effect of different micro-textures on adhesion behavior. It was demonstrated that the better anti-adhesion property could be obtained at a large area density combined with lateral micro-channels.
29
Hoyt, R. H., M. L. Cohen, P. B. Corr, and J. E. Saffitz. "Alterations of intercellular junctions induced by hypoxia in canine myocardium." American Journal of Physiology-Heart and Circulatory Physiology 258, no. 5 (May 1, 1990): H1439—H1448. http://dx.doi.org/10.1152/ajpheart.1990.258.5.h1439.
Full textAbstract:
To delineate potential structural mechanisms of impaired cell coupling induced by hypoxia in canine myocardium, we characterized derangements in intercellular junctions and alterations in the space constant in strips of ventricular epimyocardium before and after selected intervals of hypoxia in vitro. Tissue samples were analyzed morphometrically with transmission and freeze-fracture electron microscopy. Space constants in control tissues averaged 1.61 +/- 0.47 mm (mean +/- SD). After 30 and 60 min of hypoxia, space constants declined by 0.24 +/- 0.22 and 0.32 +/- 0.17 mm, respectively (P less than 0.05 vs. control in each case). Impaired coupling was not reversible with reoxygenation. Focal pathological separation of intercalated disk membranes was observed after 30 min of hypoxia, but morphometric analysis demonstrated no reduction in gap junction surface density to account for uncoupling after 30 min of hypoxia. However, after 60 min of hypoxia, gap junction surface density was reduced by 45%. Quantitative analysis of freeze-fractured gap junction replicas after 30 min of hypoxia revealed a significant decrease in P-face particle diameter from 8.51 +/- 1.64 nm in control tissues to 7.25 +/- 1.33 nm (P less than 0.01) with no further change at 60 min. Thus impaired coupling at 30 min is likely related to a change in the gap junction particle. Further uncoupling after 60 min of hypoxia is likely related, in addition, to reduced gap junction surface density. These results suggest that alterations in P-face particles and gap junction surface density are important determinants of progressive cellular uncoupling induced by hypoxia.
30
Reitbauer, Jürgen, Franz Harrer, Rene Eckhart, and Wolfgang Bauer. "Focus variation technology as a tool for tissue surface characterization." Cellulose 28, no. 11 (May 28, 2021): 6813–27. http://dx.doi.org/10.1007/s10570-021-03953-0.
Full textAbstract:
Abstract The surface of tissue paper is relatively complex compared to other paper grades and consists of several overlapping structures like protruding fibres, crepe and fabric-based patterns at different spatial frequencies. The knowledge of tissue surface characteristics is crucial when it comes to improvement with respect to surface softness and the perceptual handfeel of tissue products. In this work we used the optical based, non-contact measurement principle of focus variation for surface characterization of dry-creped, textured and through air dried (TAD) tissue. Based on the three tissue grades, a procedure which includes the characterization of the whole tissue surface throughout different scales within one setup, was developed. Surprisingly, focus variation was rarely used in tissue-related research, as it provides robust and reliable 3D surface information which can be used for further areal surface analysis. Special attention was given to the preparation and discussion of the raw data up to the final analysis including several spatial filtering steps. Enhanced surface parameters like the developed interfacial area ratio (Sdr) and the power spectral density (PSD) were used to describe the surface adequately. The surface roughness of the three tissue grades was compared, with the textured tissue showing the highest roughness in Sdr and PSD analysis. Although both methods are based on different principles, a high correlation in terms of evaluated roughness is evident. Regular structures like crepe and patterns are obtainable as peaks at the respective frequency with a certain intensity in the PSD evaluation. Apart from topography in terms of structures and roughness, the wide field of view of the focus variation measurement also allows assessment of effects related to flocculation and sheet formation. The developed procedure could also be appropriate for other fibre based materials and/or fabrics, which are similar to tissue with respect to optical properties such as for example nonwovens. Graphic abstract
31
Beers, Kimberly, Debashish Sur, and G. Bahar Basim. "Chemical Mechanical Surface Nano-Structuring (CMNS) Implementation on Titanium Based Implants to Enhance Corrosion Resistance and Control Biocompatibility." MRS Advances 5, no. 43 (2020): 2209–19. http://dx.doi.org/10.1557/adv.2020.325.
Full textAbstract:
AbstractTitanium is the metal of choice for many implantable devices including dental prostheses, orthopaedic devices and cardiac pacemakers. Titanium and its alloys are favoured for hard tissue replacement because of their high strength to density ratio providing excellent mechanical properties and biocompatible surface characteristics promoting in-vivo passivation due to spontaneous formation of a native protective oxide layer in the presence of an oxidizer. This study focuses on the development of a three-dimensional chemical, mechanical, surface nano-structuring (CMNS) process to induce smoothness or controlled nano-roughness on the bio-implant surfaces, particularly for applications in dental implants. CMNS is an extension of the chemical mechanical polishing (CMP) process. CMP is utilized in microelectronics manufacturing for planarizing the wafer surfaces to enable photolithography and multilayer metallization. In biomaterials applications, the same approach can be utilized to induce controlled surface nanostructure on three-dimensional implantable objects to promote or demote cell attachment. As a synergistic method of nano-structuring on the implant surfaces, CMNS also makes the titanium surface more adaptable for the bio-compatible coatings as well as the cell and tissue growth as demonstrated by the electrochemical and surface wettability evaluations on implants prepared by DI-water machining versus oil based machining.
32
Yuan, Tingting, Naifei Chen, Hang Jin, and Hongmei Yin. "Increased microvascular permeability and low level of low-density lipoprotein cholesterol predict symptomatic intracerebral hemorrhage in acute ischemic stroke." Science Progress 103, no. 2 (April 2020): 003685042092415. http://dx.doi.org/10.1177/0036850420924153.
Full textAbstract:
Symptomatic intracerebral hemorrhage is a serious potential complication of recombinant tissue-type plasminogen activator thrombolysis in acute ischemic stroke. We investigated the optimal imaging and clinical parameters to predict symptomatic intracerebral hemorrhage in acute ischemic stroke patients after recombinant tissue-type plasminogen activator therapy. We retrospectively reviewed 151 acute ischemic stroke patients with thrombolytic therapy, who were dichotomized into symptomatic intracerebral hemorrhage group and non–symptomatic intracerebral hemorrhage group. They underwent multimodal computed tomography, including the measurement of permeability surface. We compared the clinical and radiological characteristics between symptomatic intracerebral hemorrhage group and non–symptomatic intracerebral hemorrhage group, using univariate analysis. Receiver operating characteristic analysis and multivariate logistic regression analyses were then used to determine symptomatic intracerebral hemorrhage predictors. Of 151 patients, 14 patients (9.27%) developed symptomatic intracerebral hemorrhage on follow-up imaging. Relative permeability surface (infarct permeability surface/contralateral normal permeability surface) ( p < 0.05) and baseline low-density lipoprotein cholesterol level ( p < 0.05) were both predictors of symptomatic intracerebral hemorrhage. Receiver operating characteristic analysis of relative permeability surface revealed an optimal relative permeability surface threshold of 2.239, with an area under the curve of 0.87 (95% confidence interval, 0.732–1.0). The relative permeability surface was 2.239, the sensitivity for symptomatic intracerebral hemorrhage was 85.7%, the specificity was 94.9%, the positive predictive value was 70.6%, and the negative predictive value was 95.5%. For low-density lipoprotein cholesterol, the optimal threshold was 2.45, with an area under the curve of 0.726 (95% confidence interval, 0.586–0.867), the sensitivity for symptomatic intracerebral hemorrhage was 73.0%, the specificity was 64.3%, the positive predictive value was 67.16%, and the negative predictive value was 79.09%. Our study demonstrated that increased infarct permeability surface and low level of low-density lipoprotein cholesterol can be two predictors of symptomatic intracerebral hemorrhage. Detection of relative permeability surface and low-density lipoprotein cholesterol may help clinicians to identify acute ischemic stroke patients with the higher risk of symptomatic intracerebral hemorrhage; intravenous thrombolytic therapy should be carefully performed for patients with high relative permeability surface and low low-density lipoprotein cholesterol. We may take relative permeability surface and low-density lipoprotein cholesterol into account to refine therapeutic decision-making in acute ischemic stroke.
33
Kappelmann, Rick B., Jiri Prazma, and Harold C. Pillsbury. "Comparative Morphometric Analysis of Cochlear Vessels in Wistar-Kyoto Rats, Spontaneously Hypertensive Rats, and Aged Spontaneously Hypertensive Rats." Otolaryngology–Head and Neck Surgery 97, no. 6 (December 1987): 522–28. http://dx.doi.org/10.1177/019459988709700602.
Full textAbstract:
Vessel density and the ratio of the tissue area to the vessel surface area were studied by morphometric analysis techniques in normal rats, spontaneously hypertensive rats (SHR), and aged spontaneously hypertensive rats (aged SHR). Horseradish peroxidase was injected intravenously and the animals were killed 10 minutes later. The temporal bones were harvested, fixed in glutaraldehyde, and decalcified in 10% ethylenediamine tetraacetic acid (EDTA). After 7 days of decalcification, the cochleas were dissected and incubated with a diaminobenzidine tetrahydrochloride solution. Sections with stained vessels were projected onto the digitizing plate with the help of the camera lucida. The computer was used to calculate tissue area, vessel length, and vessel surface area. A statistically significant increase ( p < 0.05) in both the tissue area to vessel length ratio and the tissue area to vessel surface area ratio was demonstrated in the SHR and the aged SHR groups when compared to the WKY in the stria vascularis. No statistically significant difference was found between the two SHR groups. These data show a decrease of the vessel density in the capillary beds of the stria vascularis in spontaneously hypertensive rats. No statistically significant difference was found in the diameters of the capillary among the three groups.
34
Shindo, Hironori, Jisu Park, and Makoto Taniguchi. "Effect of amino group density for prevention of mammary gland tissue detachment from coated glass surface." Journal of Bioscience and Bioengineering 112, no. 2 (August 2011): 180–83. http://dx.doi.org/10.1016/j.jbiosc.2011.04.005.
Full text
35
Dobbie, James W., and James D. Anderson. "Ultrastructure, Distribution, and Density of Lamellar Bodies in Human Peritoneum." Peritoneal Dialysis International: Journal of the International Society for Peritoneal Dialysis 16, no. 5 (September 1996): 482–87. http://dx.doi.org/10.1177/089686089601600510.
Full textAbstract:
Objective To determine the ultrastructure, relative density, and location of lamellar bodies in the various regions, structures, cells, and intercellular matrix in normal human peritoneum; to carry out engineering analysis of the role of lamellar structures in serosal lubricancy and deduce what effect this system may have on the process of peritoneal dialysis. Design Five samples of normal human parietal peritoneum obtained at elective operation were fixed in a tannic acid-glutaraldehyde mixture and submitted to examination by transmission electron microscopy. Detailed analysis using reconstruction of serial electron micrographs and tracings of montages were employed in determining location, disposition, density, and geometric patterns of lamellar bodies in all levels of the peritoneal membrane. Results Lamellar profiles were found in greatest density enmeshed in surface microvilli and in mesothelial cytoplasm. Lamellar bodies were frequently observed capping the external portion of mesothelial junctional complexes, and within intercellular junctions. Lamellar bodies were also encountered in macrophages, both in the peritoneal cavity and submesothelial tissue, and also in fibroblasts. Lamellar bodies were present in low density in the matrix ground substance of submesothelial connective tissue, in blood vessel walls between smooth muscle, in endothelial cell cytoplasm, and in vascular lumina. Conclusion Three-dimensional analysis of lamellae on mesothelial surfaces indicates that an arrangement of constantly changing microscopic spheres and cylinders would act as “ball and roller bearings” among the microvilli for the lubrication of opposing surfaces. The entrapment offluid in lamellar bubbles, which in normal peritoneum fill the microvillous layer, would, if maintained in peritoneal dialysis, constitute a stagnant layer of considerable stability and inertia.
36
Zhang, Ning, Vincent Milleret, Greta Thompson-Steckel, Ning-Ping Huang, János Vörös, Benjamin R. Simona, and Martin Ehrbar. "Soft Hydrogels Featuring In-Depth Surface Density Gradients for the Simple Establishment of 3D Tissue Models for Screening Applications." SLAS DISCOVERY: Advancing the Science of Drug Discovery 22, no. 5 (March 9, 2017): 635–44. http://dx.doi.org/10.1177/2472555217693191.
Full textAbstract:
Three-dimensional (3D) cell culture models are gaining increasing interest for use in drug development pipelines due to their closer resemblance to human tissues. Hydrogels are the first-choice class of materials to recreate in vitro the 3D extra-cellular matrix (ECM) environment, important in studying cell-ECM interactions and 3D cellular organization and leading to physiologically relevant in vitro tissue models. Here we propose a novel hydrogel platform consisting of a 96-well plate containing pre-cast synthetic PEG-based hydrogels for the simple establishment of 3D (co-)culture systems without the need for the standard encapsulation method. The in-depth density gradient at the surface of the hydrogel promotes the infiltration of cells deposited on top of it. The ability to decouple hydrogel production and cell seeding is intended to simplify the use of hydrogel-based platforms and thus increase their accessibility. Using this platform, we established 3D cultures relevant for studying stem cell differentiation, angiogenesis, and neural and cancer models.
37
Nezafat, Negin Beryani, Mahmood Ghoranneviss, Seyed Mohammad Elahi, Azizollah Shafiekhani, Zohreh Ghorannevis, and Shahram Solaymani. "Topographic characterization of canine teeth using atomic force microscopy images in nano-scale." International Nano Letters 9, no. 4 (November 1, 2019): 311–15. http://dx.doi.org/10.1007/s40089-019-00284-8.
Full textAbstract:
Abstract The purpose of the present study was to investigate a new method to evaluate micro topography and micro morphology of hard tissue of canine teeth using an atomic force microscope (AFM). For this aim, three extracted human canine teeth were applied. The unpolished surfaces were analyzed with AFM images with 15 µm × 5 µm area and their information obtained by power spectral density (PSD) method and fast Fourier transform algorithm. It was observed that PSD analyses extract suitable information about surface morphological variations so that by moving from enamel to cementum, the fractal dimension and surface complexity were increased.
38
McCaffery, Ian, John Rossi, Katherine Paweletz, Yanyan Tudor, Steve Elliott, Leigh Busse, V. Dan Fitzpatrick, and Scott D. Patterson. "Analysis of Cell Surface Erythropoietin Receptor (EpoR) Expression and Function in Epithelial Human Tumor Tissues Reveals No Detectable Cell Surface Expression or Function." Blood 112, no. 11 (November 16, 2008): 5396. http://dx.doi.org/10.1182/blood.v112.11.5396.5396.
Full textAbstract:
Abstract Analysis of Cell Surface Erythropoietin Receptor (EpoR) Expression and Function in Epithelial Human Tumor Tissues Reveals No Detectable Cell Surface Expression or Function A number of studies have reported that EpoR mRNA is detectable at low levels in human epithelial tumor tissues and have raised the possibility that this surface EpoR protein expression could render human tumor cells responsive to Epo with inferred implications for the use of erythropoietic stimulating agents in the Oncology setting. To date the only data supporting this hypothesis has been generated using mRNA analysis or protein analysis using antibodies that have subsequently been shown to not be specific for EpoR. To address these possible issues more directly we have analyzed EpoR expression and function in a large panel of human primary tumor tissues isolated by surgical resection from a variety of epithelial tumor cells (including colon, non small cell lung, breast and ovarian tumors). Solid human tumor tissue was disaggregated using a treatment shown to preserve cell surface EpoR density and function in positive controls (below). Flow cytometric analysis of primary tumor cells in the disaggregated tumor population was performed using multiple markers specific for epithelial tumor cells, as well as viability dyes and apoptotic markers to exclude non-viable and or apoptotic cells from the analysis. Using anti-EpoR monoclonal antibodies with high sensitivity and specificity for EpoR, no expression of cell surface EpoR was detected in primary tumor cells in any of the more than 60 human epithelial tumor specimens analyzed. In contrast, high levels of expression were observed in a positive control cell line (UT7/Epo) analysed in parallel, as well as a physiologically relevant primary tissue (differentiated erythroid progenitor cells). Notably, in a fraction of the ovarian and breast tumor tissues cell surface EpoR expression was identified in CD45+ tumor infiltrating leukocytes. No EpoR expression was detected in non tumor cells that were not CD45+ suggesting no contribution from other stromal elements in the tumor. These observations may explain the reported detection of EpoR mRNA in a subset of breast and other solid tumor patients, as those previous analyses involved bulk tumor tissue and did not allow analysis of tumor cell specific expression. To test the possibility that low cell-surface EpoR protein density on tumor cells may be sufficient for function but undetectable by flow cytometry, we evaluated the ability of primary human tumor tissue to support an EpoR-driven signal pathway. EpoR function was analyzed in primary human tumor cells treated with a range of concentrations of recombinant human Epo (rHuEpO; 0.1–300U/mL) under conditions shown to result in productive EpoR dependent signaling in positive control cells/tissues. Analysis of possible EpoR-driven signaling was determined by intracellular flow cytometry using antibodies specific for the phosphorylated forms of STAT5, Akt, Erk1/2, p70S6, STAT3, STAT1, STAT6, JNK, and c-jun. Attribution of any detected signaling to viable tumor cells was performed via the use of a combination of tumor cell specific and viability/apoptosis markers. No evidence of downstream signaling was observed in primary tumor cells in epithelial tumors from over 60 patients at any concentration of rHuEpo, whereas UT7/Epo cells, treated in parallel, showed robust Epo concentration-dependent activation of signaling. Furthermore, activation of these signaling proteins was detected when the same primary human tumor cells were treated in parallel with a cocktail of known human tumor growth factors, confirming that these cells are capable of responding to exogenous stimuli using the same pathways as EpoR and that these signaling events can be readily detected using the platform. Taken together these data support the hypothesis that tumor cells in solid human tumors do not express functional cell surface EpoR and are not responsive to physiological or therapeutically relevant concentrations of Epo or indeed very high levels of Epo (300U/mL).
39
Vahabikashi, Amir, Ariel Gelman, Biqin Dong, Lihua Gong, Elliott D. K. Cha, Margit Schimmel, Ernst R. Tamm, et al. "Increased stiffness and flow resistance of the inner wall of Schlemm’s canal in glaucomatous human eyes." Proceedings of the National Academy of Sciences 116, no. 52 (December 5, 2019): 26555–63. http://dx.doi.org/10.1073/pnas.1911837116.
Full textAbstract:
The cause of the elevated outflow resistance and consequent ocular hypertension characteristic of glaucoma is unknown. To investigate possible causes for this flow resistance, we used atomic force microscopy (AFM) with 10-µm spherical tips to probe the stiffness of the inner wall of Schlemm’s canal as a function of distance from the tissue surface in normal and glaucomatous postmortem human eyes, and 1-µm spherical AFM tips to probe the region immediately below the tissue surface. To localize flow resistance, perfusion and imaging methods were used to characterize the pressure drop in the immediate vicinity of the inner wall using giant vacuoles that form in Schlemm’s canal cells as micropressure sensors. Tissue stiffness increased with increasing AFM indentation depth. Tissues from glaucomatous eyes were stiffer compared with normal eyes, with greatly increased stiffness residing within ∼1 µm of the inner-wall surface. Giant vacuole size and density were similar in normal and glaucomatous eyes despite lower flow rate through the latter due to their higher flow resistance. This implied that the elevated flow resistance found in the glaucomatous eyes was localized to the same region as the increased tissue stiffness. Our findings implicate pathological changes to biophysical characteristics of Schlemm’s canal endothelia and/or their immediate underlying extracellular matrix as cause for ocular hypertension in glaucoma.
40
Noviana, Deni, Sri Estuningsih, Devi Paramitha, Mokhammad Fakhrul Ulum, and Hendra Hermawan. "In Vitro Cytotoxicity and In Vivo Tissue Response Study of Foreign Bodies Iron Based Materials." Advanced Materials Research 1112 (July 2015): 449–52. http://dx.doi.org/10.4028/www.scientific.net/amr.1112.449.
Full textAbstract:
A foreign body is any object originating outside the body. It may migrate from its entry site and cause pain, inflammation and infection. This study aims to examine in vitro cytotoxicity and in vivo tissue response at different implantation sites of two iron-based foreign body (FeFB) specimens: pure Fe wire, Cr-coated Fe wire, and SS316L wire as control. In vitro cytotoxicity was assessed towards rat smooth muscle cells with direct method of methyl thiazolyl tetrazolium (MTT) assay. In vivo tissue response was examined using mice animal model until day 14 after surgical implantation in subcutaneous nape area and intramuscular right femoral muscle. Cell viability, surface morphology and Fe ion release were examined. Implant density and tissue response were examined by using radiographic imaging and histology, respectively. Results showed that both FeFB specimens exhibited similar cell viability with SS316L. Iron ion concentration was higher in both FeFB medium compared to that of SS316L and with oxide layer formation on their surface. Radiographic analysis showed that the density of both FeFB implants end-side was increased. Meanwhile, histological tissue response at intramuscular sites for FeFB specimens showed a prominent inflammatory response compared to SS316L. Detailed analysis on cell and tissue-material interactions of the iron-based foreign body specimens is discussed further in this article.
41
MacKenzie, K., and H. Dobson. "DuMond Spectroscopy: A Technique for the Determination of Bone Density." Veterinary and Comparative Orthopaedics and Traumatology 06, no. 04 (1993): 194–97. http://dx.doi.org/10.1055/s-0038-1633057.
Full textAbstract:
DuMond spectroscopy is a new technique for the determination of bone mineral density. The instrument consists of an Americium-241 source mounted in an absorber post located on the surface of a sodium iodide detector. The analysis is based on the energy distribution of photons scattered by the tissue. Measurements made using a series of powdered bovine cortical bone and wax mixtures gave an R value of 0.991. Repeated measurements made on a series of calcaneus specimens gave a precision of 0.96%.
42
Christ, Andreas, Theodoros Samaras, Esra Neufeld, and Niels Kuster. "TRANSMISSION COEFFICIENT OF POWER DENSITY INTO SKIN TISSUE BETWEEN 6 AND 300 GHZ." Radiation Protection Dosimetry 192, no. 1 (October 2020): 113–18. http://dx.doi.org/10.1093/rpd/ncaa179.
Full textAbstract:
Abstract The latest electromagnetic safety guidelines define transmitted or epithelial power density as the basic restriction above 6 GHz. In this note, we derive an approximation for a conservative transmission coefficient for quasi plane wave incidence as a function of the frequency for the normal component of the Poynting vector with respect to the evaluation plane or tissue surface |Sz inc| and for its modulus ||Sinc||. The maximum transmission coefficient for the normal component of the Poynting vector ${\boldsymbol{T}}_{\mathbf{z}}^{\mathbf{max}}$ is 1 independent of tissue composition and frequency. Approximations of ${\boldsymbol{T}}_{\mathbf{total}}^{\mathbf{max}}$ normalized to ||Sinc|| for thin and thick stratum corneum are provided allowing higher exposures. These approximations allow to conservatively demonstrate compliance with basic restrictions when quasi plane-wave conditions are locally satisfied and enhancement effects of standing waves between source and body can be neglected. The reported results are important to regulators and standardization bodies regarding revisions of compliance requirements and safety guidelines.
43
Liu, Guang, Pengfei Zhang, Yang Liu, Deyuan Zhang, and Huawei Chen. "Self-Lubricanting Slippery Surface with Wettability Gradients for Anti-Sticking of Electrosurgical Scalpel." Micromachines 9, no. 11 (November 13, 2018): 591. http://dx.doi.org/10.3390/mi9110591.
Full textAbstract:
Soft tissue sticking on electrosurgical scalpels in minimally invasive surgery can increase the difficulty of operation and easily lead to medical malpractice. It is significant to develop new methods for anti-sticking of soft tissue on electrosurgical scalpels. Based on the characteristics of biomimetic ultra-slippery surface, a self-lubricating slippery surface with wettability gradients on electrosurgical scalpel was designed and fabricated. Non-uniformly distributed cylindrical micro pillars, which constitute the wettability gradients, were prepared by an electrolytic etching process and the theoretic of the spontaneous liquid spreading process was analyzed. The silicophilic property of wettability gradients surface was modified by octadecyltrichlorosilane (OTS) self-assembling coat with biocompatible liquid lubricant dimethyl silicone oil. The contact angle of gradient’s surface at different temperatures was measured. The transportation behaviors of both water and dimethyl silicone oil on the wettability gradient’s surface were investigated; the results illustrate that the wettability gradient’s slippery surface can successfully self-lubricate from regions with low pillar density to regions with high pillar density, ascribed to the unbalanced Young’s force. The anti-sticking capability of the electrosurgical scalpel with self-lubricating slippery surface was tested. Both the adhesion force and adhesion mass under different cycles were calculated. The results suggest that the as-prepared slippery surface has excellent anti-sticking ability associated with better durability.
44
Curtiss, G. A., D. M. Leppinen, Q. X. Wang, and J. R. Blake. "Ultrasonic cavitation near a tissue layer." Journal of Fluid Mechanics 730 (July 30, 2013): 245–72. http://dx.doi.org/10.1017/jfm.2013.341.
Full textAbstract:
AbstractIn this paper we examine the dynamics of an initially stable bubble due to ultrasonic forcing by an acoustic wave. A tissue layer is modelled as a density interface acted upon by surface tension to mimic membrane effects. The effect of a rigid backing to the thin tissue layer is investigated. We are interested in ultrasound contrast agent type bubbles which have immediate biomedical applications such as the delivery of drugs and the instigation of sonoporation. We use the axisymmetric boundary integral technique detailed in Curtiss et al. (J. Comput. Phys., 2013, submitted) to model the interaction between a single bubble and the tissue layer. We have identified a new peeling mechanism whereby the re-expansion of a toroidal bubble can peel away tissue from a rigid backing. We explore the problem over a large range of parameters including tissue layer depth, interfacial tension and ultrasonic forcing.
45
Crowley, Hildegard H. "Pretreating Epoxy Thin Sections With Sodium Periodate Prior To Immunostaining." Microscopy Today 5, no. 6 (August 1997): 24–25. http://dx.doi.org/10.1017/s1551929500056091.
Full textAbstract:
Pretreatment of epoxy thin sections with strong oxidizing agents such as hydrogen peroxide, sodium methoxide, and sodium m-metaperiodate facilities the location of antigens with immunostaining procedures. Etching, or pretreatment, of sections unmasks antigenic sites on glutaraldehyde fixed and postosmicated tissue, partially removes osmium bonds, temporarily decreases the hydrophobicity of the epoxy surface layer of the section, reduces the electron density of the tissue and increases resistance to heavy rnetai poststaining.
46
Ferraris, Sara, Fernando Warchomicka, Fatemeh Iranshahi, Lia Rimondini, Andrea Cochis, and Silvia Spriano. "Electron Beam Structuring of Ti6Al4V: New Insights on the Metal Surface Properties Influencing the Bacterial Adhesion." Materials 13, no. 2 (January 15, 2020): 409. http://dx.doi.org/10.3390/ma13020409.
Full textAbstract:
Soft tissue adhesion and infection prevention are currently challenging for dental transmucosal or percutaneous orthopedic implants. It has previously been shown that aligned micro-grooves obtained by Electron Beam (EB) can drive fibroblast alignment for improved soft tissue adhesion. In this work, evidence is presented that the same technique can also be effective for a reduction of the infection risk. Grooves 10–30 µm wide and around 0.2 µm deep were obtained on Ti6Al4V by EB. EB treatment changes the crystalline structure and microstructure in a surface layer that is thicker than the groove depth. Unexpectedly, a significant bacterial reduction was observed. The surfaces were characterized by field emission scanning electron microscopy, X-ray diffraction, confocal microscopy, contact profilometry, wettability and bacterial adhesion tests. The influence of surface topography, microstructure and crystallography on bacterial adhesion was systematically investigated: it was evidenced that the bacterial reduction after EB surface treatment is not correlated with the grooves, but with the microstructure induced by the EB treatment, with a significant bacterial reduction when the surface microstructure has a high density of grain boundaries. This correlation between microstructure and bacterial adhesion was reported for the first time for Ti alloys.
47
Hansen, Carsten B., Charles Pyke, Lars C. Petersen, and L. Vijaya Mohan Rao. "Tissue factor–mediated endocytosis, recycling, and degradation of factor VIIa by a clathrin-independent mechanism not requiring the cytoplasmic domain of tissue factor." Blood 97, no. 6 (March 15, 2001): 1712–20. http://dx.doi.org/10.1182/blood.v97.6.1712.
Full textAbstract:
Endocytosis and recycling of coagulation factor VIIa (VIIa) bound to tissue factor (TF) was investigated in baby hamster kidney (BHK) cells stably transfected with TF or TF derivatives. Cell surface expression of TF on BHK cells was required for VIIa internalization and degradation. Approximately 50% of cell surface–bound VIIa was internalized in one hour, and a majority of the internalized VIIa was degraded soon thereafter. Similar rates of VIIa internalization and degradation were obtained with BHK cells transfected with a cytoplasmic domain-deleted TF variant or with a substitution of serine for cysteine at amino acid residue 245 (C245S). Endocytosis of VIIa bound to TF was an active process. Acidification of the cytosol, known to inhibit the internalization via clathrin-coated pits, did not affect the internalization of VIIa. Furthermore, receptor-associated protein, known to block binding of all established ligands to members of the low-density lipoprotein receptor family, was without an effect on the internalization of VIIa. Addition of tissue factor pathway inhibitor/factor Xa complex did not affect the internalization rate significantly. A substantial portion (20% to 25%) of internalized VIIa was recycled back to the cell surface as an intact and functional protein. Although the recycled VIIa constitutes to only approximately 10% of available cell surface TF/VIIa sites, it accounts for 65% of the maximal activation of factor X by the cell surface TF/VIIa. In summary, the present data provide evidence that TF-dependent internalization of VIIa in kidney cells occurs through a clathrin-independent mechanism and does not require the cytoplasmic domain of TF.
48
Vu, Ngoc Bich, and Minh Thi-Nguyet Nguyen. "A simple and scalable method to generate spheroids from human mesenchymal stem cells for use in tissue engineering." Biomedical Research and Therapy 7, no. 12 (December 29, 2020): 4139–51. http://dx.doi.org/10.15419/bmrat.v7i12.652.
Full textAbstract:
Introduction: Tissue engineering is a field suited for applying stem cells, besides stem cell transplantation. In the current tissue engineering approaches, stem cells are typically seeded onto a suitable scaffold and induced into specific tissues under particular conditions. However, this strategy has faced some limitations, namely that stem cell proliferation on the scaffolds' surface has been inefficient to fill the porous scaffolds to produce solid tissues. Some limitations have been improved by using stem cell spheroids on the scaffold in place of single stem cells. This study aimed to evaluate a simple and feasible method to produce spheroids of mesenchymal stem cells (MSCs) from adipose and umbilical cord tissues for use in tissue engineering.
Methods: MSCs from human adipose tissue (adipose-derived stem cells, i.e., ADSCs) and human umbilical cord tissues (umbilical cord-derived mesenchymal stem cells, i.e., UCMSCs) were isolated according to previously published protocols. To produce spheroids, ADSCs and UCMSCs were cultured in non-adherent V-bottom 96-well plate. Three cell densities were evaluated: 250 cells/well, 500 cells/well, and 1,000 cells/well. The generated spheroids were evaluated based on spheroid diameter, necrotic core formation (using propidium iodide (PI) and Hoechst 33342 staining), and spheroid structure (by Hematoxylin & Eosin staining).
Results: The results showed that at a density of 250 cells/well, spheroids were formed without necrotic cores from both ADSCs and UCMSCs. However, at a higher density, all spheroids had a necrotic core as part of the three zones (proliferating, quiescent, and necrotic zones).
Conclusion: Spheroids from ADSCs and UCMSCs can be easily produced by culturing 250 cells/well in a non-adherent V-bottom 96-well plate. This process can be scaled up by using the liquid handling robot system to load cells into the plates.
49
Fujie, Hiromichi, Kei Oya, Yuki Tani, Kenji Suzuki, and Norimasa Nakamura. "Stem Cell-Based Self-Assembled Tissues Cultured on a Nano-Periodic-Structured Surface Patterned Using Femtosecond Laser Processing." International Journal of Automation Technology 10, no. 1 (January 4, 2016): 55–61. http://dx.doi.org/10.20965/ijat.2016.p0055.
Full textAbstract:
The present study was conducted to determine the effects of a nano-periodic-structured surface on the morphological and mechanical properties of a stem-cell-based self-assembled tissue (scSAT) developed for biological tissue repair. Nano-periodic groove structures were patterned on a pure titanium surface using femtosecond laser processing, and the structure was replicated on polydimethylsiloxane (PDMS). The depth, periodic pitch, and surface roughness (Ra) of the PDMS grooves were 48 ± 21 nm, 522 ± 9 nm, and 17 ± 5 nm, respectively. Human synovial cells, including mesenchymal stem cells, were subjected to 4-time cell passage, and then cultured on the PDMS surface at a density of 4.0 × 105cells/cm2in a growth medium with 0.2 mM ascorbic acid 2-phosphate to produce scSATs (nano-scSAT). For comparison, some of the cells subjected to 4-time cell passage were cultured on either a flat PDMS substrate with 6 ± 1 nm of surface roughness (Ra) (flat-scSAT) or a commercially available cell culture plate of polystyrene (normal-scSAT), at a cell density identical to that in the nano-scSAT group. At 28 days of cell culture, the scSATs were gently detached from the culture plates and subjected to morphological observation and mechanical testing. Microscopic observation revealed that the nano-scSATs exhibited a dense tissue of cells and an extracellular matrix with an anisotropic structure, while the flat- and normal-scSATs exhibited a sparse and isotropic structure. The tangent modulus and tensile strength were significantly higher in the nano-scSATs than in the flat- and normal-scSATs. These results suggest that a nano-periodic-structured surface improves the morphological and mechanical properties of scSATs.
50
NORDMAN, Henrik, Julia R. DAVIES, Gert LINDELL, Carme de BOLÓS, Francisco REAL, and Ingemar CARLSTEDT. "Gastric MUC5AC and MUC6 are large oligomeric mucins that differ in size, glycosylation and tissue distribution." Biochemical Journal 364, no. 1 (May 8, 2002): 191–200. http://dx.doi.org/10.1042/bj3640191.
Full textAbstract:
Gastric MUC5AC and MUC6 mucins were studied using polyclonal antibodies. Immunohistochemistry showed MUC5AC to originate from the surface epithelium, whereas MUC6 was produced by the glands. Mucins from the surface epithelium or glands of corpus and antrum were purified using CsCl/4M guanidinium chloride density-gradient centrifugation. MUC5AC appeared as two distinct populations at 1.4 and 1.3g/ml, whereas MUC6, which was enriched in the gland tissue, appeared at 1.45g/ml. Reactivity with antibodies against the Leb structure (where Le represents the Lewis antigen) followed the MUC5AC distribution, whereas antibodies against the Ley structure and reactivity with the GlcNAc-selective Solanum tuberosum lectin coincided with MUC6, suggesting that the two mucins are glycosylated differently. Rate-zonal centrifugation of whole mucins and reduced subunits showed that both gastric MUC5AC and MUC6 are oligomeric glycoproteins composed of disulphide-bond linked subunits and that oligomeric MUC5AC was apparently smaller than MUC6. A heterogeneous population of ‘low-density’ MUC5AC mucins, which were smaller than the ‘high-density’ ones both before and after reduction, reacted with an antibody against a variable number tandem repeat sequence within MUC5AC, suggesting that they represent precursor forms of this mucin. Following ion-exchange HPLC, both MUC5AC and MUC6 appeared as several distinct populations, probably corresponding to ‘glycoforms’ of the mucins, the most highly charged of which were found in the gland tissue.