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The diagnosis and management of preterm labor with intact membranes
Published in Hung N. Winn, Frank A. Chervenak, Roberto Romero, Clinical Maternal-Fetal Medicine Online, 2021
Roberto Romero, Tinnakorn Chaiworapongsa, Francesca Gotsch, Lami Yeo, Ichchha Madan, Sonia S. Hassan
Fetal fibronectin has been used in the evaluation of asymptomatic women to predict their risk of preterm delivery. Numerous meta-analyses (176,184,377–380) have concluded that cervicovaginal fetal fibronectin testing might be clinically useful in the prediction of preterm birth, with an emphasis given to the high negative predictive value of the test, particularly in women who are symptomatic of threatened preterm labor and for delivery within 7 to 10 days of sampling. Kurtzman et al. (381) have proposed the use of quantitative fetal fibronectin screening in asymptomatic women with a prior preterm delivery. This group demonstrated that quantitative fetal fibronectin assessment at 24 weeks of gestation could be used to predict the risk of spontaneous preterm delivery before 34 weeks of gestation, and that this risk increased as the quantity of fetal fibronectin (FFN) increased [compared with an FFN = 0 ng/mL; RR 2.42 (FFN 1–49ng/mL;95% CI0.76–5.66), 4.68(FFN 50–199ng/mL; 95% CI 1.28–10.95), and 9.94 (FFN>200ng/mL; 95% CI 2.90–19.67)] (381).
Introduction to Oral and Craniofacial Tissue Engineering
Published in Vincenzo Guarino, Marco Antonio Alvarez-Pérez, Current Advances in Oral and Craniofacial Tissue Engineering, 2020
María Verónica Cuevas González, Eduardo Villarreal-Ramírez, Adriana Pérez-Soria, Pedro Alberto López Reynoso, Vincenzo Guarino, Marco Antonio Alvarez-Pérez
Another essential fibrous protein in the matrix for playing a crucial role in the organization of the interstitial of the extracellular matrix and for interactions with cells is fibronectin. Fibronectin is directly related to central cellular events related to the matrix, such as cell adhesion, migration, growth and differentiation. Fibronectin is a protein made up of a dimer that is held together by a pair of disulfide linkages in the carboxyl terminus, and each monomer has a molecular weight around of ~250 kDa. Similar to elastin, fibronectin is a protein encoded by a single gene. However, fibronectin may occur in different versions due to alternative splicing, generating up to 20 known isoforms. Fibronectin can be stretched several times over its resting length by a neighboring cellular traction force. Owing to the tensile strength over fibronectin, it undergoes to conformational changes to expose integrin-binding sites recognized by integrins on the cellular surface. Consequently, the adhesion of integrins to fibronectin is allowed and promotes fibronectin-fibril assembly, which implies that fibronectin is also a mechano-regulator of the extracellular matrix (Frantz et al. 2010; Pankov and Yamada 2002; Xu and Mosher 2011).
Eosinophil Interactions with Extracellular Matrix Proteins
Published in Bruce S. Bochner, Adhesion Molecules in Allergic Disease, 2020
Garry M. Walsh, Andrew J. Wardlaw
Fibronectins (reviewed in 15) are abundant in the ECM and represent a complex and heterogeneous group of molecules that play an important role in processes as diverse as embryogenesis, thymocyte maturation, and T-cell function. Fibronectin has been shown to be involved in the morphogenesis of lung epithelium (16); its expression is increased in adults during lung injury and repair (17,18); human bronchial epithelial cells are capable of fibronectin production (19); and it may also play an important role in the pathogenesis of lung fibrosis (20,21). Fibronectin is encoded by a single gene, but alternative splicing of the primary RNA transcript results in polypeptide diversity that appears to be regulated in a cell type-specific fashion (22,23). Three separate exons, namely EIIIA, EIIIB, or IIICS, are subject to alternative splicing. The IIICS region of fibronectin contains a number of sites recognized by the integrin α4β1 (very late activation antigen-4 [VLA-4]), namely CS-1 and CS-5 (24). The 25-amino-acid sequence CS-1 is the most active binding site in the IIICS region (25), and it appears to be the minimum sequence on the fibronectin molecule required for recognition by α4β1 (26,27). Plasma fibronectin lacks the IIICS cell-binding region in at least half its subunits, whereas tissue fibronectin has it in both subunits (28).
Mimicking chronic glaucoma over 6 months with a single intracameral injection of dexamethasone/fibronectin-loaded PLGA microspheres
Published in Drug Delivery, 2022
Alba Aragón-Navas, María J. Rodrigo, David Garcia-Herranz, Teresa Martinez, Manuel Subias, Silvia Mendez, Jesús Ruberte, Judit Pampalona, Irene Bravo-Osuna, Julian Garcia-Feijoo, Luis E. Pablo, Elena Garcia-Martin, Rocío Herrero-Vanrell
Fibronectin plays a major role in the adhesion of many cell types, in fact, fibronectin is considered as the extracellular glue (Zollinger & Smith, 2017). Fibronectin has a RGD loop that is a promiscuous site for many cellular integrins, such as α5β1, α3β1, α8β1, and αvβ3 (Pankov & Yamada, 2002). This could explain how, unlike our other models where microspheres without fibronectin were injected (Garcia-Herranz et al., 2021; Rodrigo et al., 2021), focal adhesions were observed between the iris and the cornea (Figure 11). These synechiae are established through the fibronectin-containing microspheres and that would glue the iris and cornea (Figure 11). Obviously, these synechiae will modify the flow of the aqueous humor and therefore its reabsorption at the level of the trabecular meshwork.
Molecular and endocrine mechanisms involved in preterm birth
Published in Gynecological Endocrinology, 2022
Elena Pisacreta, Paolo Mannella
With the final goal of reducing the incidence and consequences of PTB, screening and diagnostic tests have been studied in the last years. Fetal fibronectin (FFN) is the most used among the biochemical biomarkers. FFN is an extracellular matrix glycoprotein, discovered in the 80’s [8] which is in a chorion-decidual interface and is produced by amniocytes and cytotrophoblasts. It is a kind of “glue” that holds together maternal and fetal tissues.” FFN is normally found in cervico-vaginal secretion during the first months of pregnancy, much more at the beginning and then it slowly decreases until 22 weeks’ gestation. Between 22 and 34 weeks’ gestation, FFN should be undetectable and a negative FFN can be considered a marker that PTB will not take place in the following 14 days [9]. In this way, FFN has a strong negative predictive value on PTB but, at the same time, a positive FFN test does not mean a warranted delivery [10]. This is important in order to lead clinical management of women such as in the use of antenatal glucocorticoids and tocolytics [11]. Furthermore, in experimental models of anion cell mice, FFN has a crucial role not only as a biochemical marker of PTB but also in its pathogenesis. In fact, Mogami et al. [12] demonstrated that the injection of FFN in pregnant mice can activate PTB and that this inoculation of FFN on amnion cells causes a crucial increase of metalloproteinases activity and prostaglandins synthesis which triggers labor.
Fibronectin modified alginate coating enhances cell targeting and homing to bone marrow in BALB/c mice
Published in Journal of Microencapsulation, 2022
Yogesh Kumar Verma, Gangenahalli Ugraiah Gurudutta
Bone marrow transplantation (BMT) is used for the treatment of many disorders that include radiation injury, immunodeficiencies and leukaemia (Hardy and Ikpeazu 1989). However, shortage of sufficient number of stem cells and premature differentiation in the peripheral vasculature due to growth factors decreases the efficiency of BMT. The engraftment of transplanted stem cells is regulated by the process of migration and homing. Molecules such as, CXCR4, integrins and selectins, mediate rolling, and adhesion of stem cells to endothelium of blood vessels before transendothelium migration to BM (Lapidot et al.2005). Integrins viz. CD49d (VLA4/integrin α4)/CD29 (integrin β1) and CD49e (VLA5/integrin α5)/CD29, play an important role in migration and homing of haematopoietic and progenitor stem cells (Pelayo 2012). Fibronectin, which is a high-molecular weight (∼440kDa) glycoprotein, is found in extracellular matrix and binds to cell membrane-spanning integrin receptors. It also has binding affinity towards extracellular matrix molecules including collagen, fibrin, and heparan sulphate proteoglycans. Fibronectin exists as a dimer, it promotes the process of adhesion and transendothelial migration (TEM) by binding with integrin receptors present on stem cells at BM endothelium (Quesenberry and Becker 1998, Pankov and Yamada 2002).