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PubMed1997

Rapid fetal fibronectin swab-test in preterm labor patients treated by betamimetics.

OBJECTIVE: A preliminary study to examine the value of a rapid fetal fibronectin swab-test used as a bedside test in the prognosis of preterm labor. STUDY DESIGN: Women presenting with preterm labor and intact membranes and less than 3 cm dilated were enrolled in a single referral center. Cervicovaginal swabs were assessed for the presence or absence of fetal fibronectin by means of a rapid monoclonal antibody assay the positivity of which was revealed by a colorimetric reaction. Results were compared with uterine contractions frequency, Bishop cervical score, duration of tocolysis and interval to delivery. The predictive value of fetal fibronectin test for delivery within 7, 14 or 21 days from sampling and before 32 and 37 weeks' of gestation was assessed in the two groups. RESULTS: Among 124 eligible patients, 19 presented with a positive fibronectin test and 105 with a negative one. Gestational age at sampling, Bishop cervical score and duration of tocolysis were identical in the two groups. The number of contractions was significantly lower and gestational age at delivery was significantly higher in the fibronectin negative group. Fetal fibronectin in cervicovaginal secretions has a high sensitivity (89%) for delivery within 7 days. Absence of fetal fibronectin in cervicovaginal secretions of patients presenting with uterine contractions could rule out preterm labor within 7 and 14 days with a predictive value of 99 and 95.2%, respectively. In negative fetal fibronectin patients, preterm delivery before 32 and 37 weeks' is unlikely to occur with a predictive value of 97 and 85%, respectively. CONCLUSION: Cervicovaginal fetal fibronectin detected by a rapid bedside swab-test in women with symptoms of preterm labor compares favourably with quantitative assays and could prove useful in the management of preterm labor. This should be confirmed in a longer prospective study.

Adrenergic beta-Agonists↗
PubMed1998

Immunohistochemical detection of fibronectin in postmortem incised wounds of porcine skin.

Fibronectin plays an important role in tissue repair and wound healing. Previous literature reports indicated that fibronectin could be a marker of vitality for wounds with a survival time of more than a few minutes. In order to verify these findings were performed immunohistochemical investigations on the expression of fibronectin in incised wounds of porcine skin inflicted into various anatomical regions in the early postmortem interval (0-5 min after circulatory arrest). Tissue specimens were collected 12-14 h postmortem and investigated for fibronectin on paraffin sections (alkaline phosphatase and monoclonal anti-alkaline phosphatase procedure). A markedly positive expression of fibronectin (not only next to the wound margin and clearly stronger than in normal undamaged skin) could be demonstrated in eleven out of 36 samples. A moderately positive fibronectin reaction was detectable in seven further specimens. Muscular contraction bands were observed in nine out of 36 specimens. The various reaction patterns of fibronectin cannot be finally explained, but are probably due to a passive transudation of skin tissue by blood components from injured vessels. As a result of these investigations the specificity and validity of fibronectin as a parameter of vitality has to be questioned. Fibronectin immunohistochemistry again reveals that the validity of parameters as vital criteria decreases when their manifestation time is short; postmortem/supravital induction seems to be possible resembling vital reactions in these cases.

Animals↗
PubMed1985

[Changes in levels of plasma fibronectin after surgery for digestive cancer].

Fibronectin is a large, adhesive glycoprotein, also called opsonic alpha 2 surface-binding glycoprotein. This glycoprotein which participates in all adhesions may modulate wound healing; plasma fibronectin, because it is opsonically active, may mediate reticulo-endothelial activity. Citrated plasma samples were analysed from twenty surgical patients with digestive cancer. The samples were obtained preoperatively and on 1st, 3rd, 7th, 14th and 28th postoperative days. Fibronectin assay was made by laser immunonephelometry. Other samples were obtained from a population of 340 healthy male and female subjects whose age ranged from 10 to 70 years, so that reference could be made to the standard mean of fibronectin related to the age of each patient. In the surgical patients, there was a significant decrease in fibronectin from the first to the third postoperative day. On the 7th day, there was a secondary increase of fibronectin levels which exceeded the preoperative values at the 14th and 28th days. There was no plasma dilution when the samples were collected, this being shown by protidaemia, osmolarity and haematocrit which were measured at the same time. "Septic" and "non septic" patients were compared. For septic patients, fibronectin levels were lower and the secondary increase occurred later than in the non septic patients. Patients with no secondary increase did not recover and died. Fibronectin levels were compared with other classical parameters of nutritional assessment, i.e. albumin, prealbumin, transferrin and urinary creatinine indexes. These parameters were not well correlated. However, this study may indicate the usefulness of fibronectin as an indicator of nutritional status and of non specific host defence.

Aged↗
PubMed2004

Tyrosine phosphorylation-dependent PI 3 kinase/Akt signal transduction regulates TGFbeta-induced fibronectin expression in mesangial cells.

TGFbeta stimulates expression of fibronectin in various cells, including mesangial cells. The mechanism by which TGFbeta exerts this effect is not fully understood. We investigated the involvement of tyrosine phosphorylation and the phosphatidylinositol (PI) 3 kinase/Akt signalling pathway in this process. TGFbeta increased tyrosine phosphorylation, resulting in activation of PI 3 kinase in mesangial cells. Inhibition of tyrosine phosphorylation blocked TGFbeta-induced fibronectin expression. Inhibition of PI 3 kinase activity also prevented fibronectin expression induced by TGFbeta. Furthermore, expression of constitutively active PI 3 kinase by adenovirus-mediated gene transfer increased fibronectin expression similar to TGFbeta. TGFbeta stimulated Akt serine threonine kinase in a tyrosine kinase- and PI 3 kinase-dependent manner. Inhibition of TGFbeta-induced Akt activity by adenovirus-mediated expression of a dominant-negative mutant of Akt abolished expression of fibronectin. Dominant-negative PI 3 kinase or dominant-negative Akt inhibited TGFbeta-induced fibronectin transcription. In contrast, and similarly to TGFbeta, expression of constitutively active PI 3 kinase or constitutively active Akt increased transcription of fibronectin, confirming a prominent role of these kinases in expression of fibronectin. These data provide the evidence that activation of TGFbeta receptor serine threonine kinase stimulates the PI 3 kinase/Akt pathway in a tyrosine phosphorylation-dependent manner and define a role for the same signal transduction pathway in TGFbeta-induced fibronectin expression.

Animals↗
PubMed2001

Collagen VI deficiency affects the organization of fibronectin in the extracellular matrix of cultured fibroblasts.

Fibronectin is one of the main components of the extracellular matrix and associates with a variety of other matrix molecules including collagens. We demonstrate that the absence of secreted type VI collagen in cultured primary fibroblasts affects the arrangement of fibronectin in the extracellular matrix. We observed a fine network of collagen VI filaments and fibronectin fibrils in the extracellular matrix of normal murine and human fibroblasts. The two microfibrillar systems did not colocalize, but were interconnected at some discrete sites which could be revealed by immunoelectron microscopy. Direct interaction between collagen VI and fibronectin was also demonstrated by far western assay. When primary fibroblasts from Col6a1 null mutant mice were cultured, collagen VI was not detected in the extracellular matrix and a different pattern of fibronectin organization was observed, with fibrils running parallel to the long axis of the cells. Similarly, an abnormal fibronectin deposition was observed in fibroblasts from a patient affected by Bethlem myopathy, where collagen VI secretion was drastically reduced. The same pattern was also observed in normal fibroblasts after in vivo perturbation of collagen VI-fibronectin interaction with the 3C4 anti-collagen VI monoclonal antibody. Competition experiments with soluble peptides indicated that the organization of fibronectin in the extracellular matrix was impaired by added soluble collagen VI, but not by its triple helical (pepsin-resistant) fragments. These results indicate that collagen VI mediates the three-dimensional organization of fibronectin in the extracellular matrix of cultured fibroblasts.

Animals↗
PubMed1995

Splicing patterns of fibronectin mRNA from normal and osteoarthritic human articular cartilage.

Fibronectin, a large extracellular glycoprotein, mediates the interaction of cells with the extracellular matrix. Heterogeneity in the structure of fibronectin is largely due to the alternative splicing of three exons (IIIB, IIIA and V) during processing of the fibronectin primary transcript. Osteoarthritis, a degenerative disease of synovial joints, is characterized by a progressive loss of the articular cartilage eventually resulting in pain and loss of joint function. In contrast to the loss of most cartilage matrix proteins accompanying this process, osteoarthritic cartilage contains more fibronectin than disease-free cartilage. We examined the splicing patterns of fibronectin mRNA from adult human articular cartilage of normal and osteoarthritic joints by RNase protection (exon IIIA and exon IIIB) and reversed transcription-polymerase chain reaction (exon V) assays to determine whether or not the increased fibronectin content in osteoarthritic cartilage is also associated with differences in the splicing patterns of these three alternatively spliced exons. The results revealed no gross differences in splicing of these exons between the fibronectin mRNA isolated from adult human articular normal and osteoarthritic cartilage. Thus alterations in the structure of cartilage fibronectin do not appear to correlate with the increased level of fibronectin protein associated with osteoarthritis.

Adult↗
PubMed1997

Intermittent cyclic loading of cartilage explants modulates fibronectin metabolism.

OBJECTIVE: The aim of this study was to evaluate systematically the effect of tissue load, its amplitude, time of intermittence and duration of loading on the biosynthesis and release of fibronectin by intermittently loaded mature bovine articular cartilage explants. METHODS: Cyclic compressive pressure was introduced using a sinusoidal waveform of 0.5 Hz-frequency with a peak stress of 0.1, 0.5 or 1.0 MPa for a period of 10 s followed by an unloaded period lasting 10, 100 or 1000 s. Fibronectin and total proteins were radiolabeled with 10 microCi/ml [3H]-phenylalanine during the final 18 h of the 1, 3 or 6 day experiments. The content of endogenous fibronectin was determined using enzyme-linked immunosorbant assay (ELISA), whereas the viability of explants was measured using sections of cartilage explants stained with fluorescein diacetate and propidium iodide. The deformation of loaded explants was determined using a load-displacement transducer system. RESULTS: The mechanical factor time of intermittence significantly altered the synthesis and release of fibronectin by cartilage explants, whereas the tested range of load magnitudes, as well as the duration of loading, seemed to be of subordinate importance. Loading affected the viability of the superficial zone in the cartilage, whereas the chondrocytes of the intermediate and deep zone remained viable. The compression of loaded explants was dependent on the magnitude of stress, as well as on the duration of unloading between each loading cycle. Synthesis of fibronectin, the retention of newly synthesized fibronectin within the extracellular matrix, and the portion of newly synthesized proteins that were fibronectin was significantly increased in cartilage explants which were cyclically compressed with 0.5 MPa for 10 s followed by a period of unloading lasting 100 s. CONCLUSIONS: Previous studies reporting that cartilage explants of human and animal osteoarthritic joints synthesize and retain elevated amounts of fibronectin imply that in our experiments mechanical stimuli can induce a fibronectin metabolism in vitro which mimics some of the osteoarthritic characteristics.

Animals↗
PubMed1985

Domain structure of human plasma and cellular fibronectin. Use of a monoclonal antibody and heparin affinity to identify three different subunit chains.

The domain structure of human plasma fibronectin was investigated by using heparin-binding and antibody reactivity of fibronectin and its proteolytically derived fragments. Digestion of human plasma fibronectin with a combination of trypsin and cathepsin D produced six major fragments. Affinity chromatography showed that one fragment (Mr 45 000) binds to gelatin and three fragments (Mr 31 000, 36 000, and 61 000) bind to heparin. The 31K fragment corresponds to NH2-terminal fragments isolated from other species. The 36K and 61K fragments are derived from a region near the C-terminus of the molecule and appear to be structurally related as demonstrated by two-dimensional peptide maps. A protease-sensitive fragment (Mr 137 000), which binds neither gelatin nor heparin but which has been shown previously to be chemotactic for cells [Postlethwaite, A. E., Keski-Oja, J., Balian, G., & Kang, A. H. (1981) J. Exp. Med. 153, 494-499], separates the NH2-terminal heparin- and gelatin-binding fragments from the C-terminal 36K and 61K heparin-binding fragments. A monoclonal antibody to fibronectin that recognized the 61K heparin-binding fragment was used to isolate a sixth fragment (Mr 34 000) that did not bind to heparin or gelatin and that represents a difference between the 61K and 36K heparin-binding fragments. Cathepsin D digestion produced an 83K heparin-binding, monoclonal antibody reactive fragment that contains the interchain disulfide bond(s) linking the two fibronectin chains at their C-termini. The data indicate that plasma fibronectin is a heterodimeric molecule consisting of two very similar but not identical chains (A and B). In contrast, enzymatic digestion of cellular fibronectin produced a 50K heparin-binding fragment lacking monoclonal antibody reactivity which suggests that the cellular fibronectin subunit is similar to the plasma A chain in enzyme susceptibility but contains a larger heparin-binding domain. A model relating the differences in the three fibronectin polypeptides to differences in published cDNA sequences is presented.

Amniotic Fluid↗
PubMed1981

Interaction of fibronectin with collagen fibrils.

The interaction of fibronectin with native collagen during collagen fibril formation was investigated. Fibronectin prepared from serum, or from the cell surface, bound to the forming collagen fibrils while less fibronectin bound to preformed fibers. Denatured collagen competed with native collagen in binding fibronectin. Fibronectin delayed the precipitation of collagen fibrils but did not alter the total amount of fibrils formed. Fibronectin which was heated to 30 degrees C for 30 min did not promote cell adhesion but still bound to native collagen and delayed fiber formation. The collagen-binding fragment of fibronectin produced by digestion either with chymotrypsin or with neutrophil elastase had a similar effect in delaying fibril formation, but the cell-binding fragment was not active. These studies indicate that fibronectin can bind to aggregating collagen fibers probably at the same site shown previously to bind to denatured collagen. Since fibronectin inhibits the rate of collagen fibrillogenesis, it may regulate the size of collagen fibers.

Animals↗
PubMed2004

Dynamic alterations of fibronectin layers on copolymer substrates with graded physicochemical characteristics.

Desorption and exchange of preadsorbed fibronectin layers in pure buffer solution and solutions of human serum albumin or fibronectin, respectively, were studied in dependence on the physicochemical characteristics of maleic acid copolymer films used as substrates. Although the preadsorbed amount of fibronectin differed only slightly, the protein was found to exhibit a significantly enhanced anchorage at the more hydrophobic polymer surface as compared to the more hydrophilic and more negatively charged polymer surface. The preadsorbed fibronectin layer was most efficiently exchanged by fibronectin (i.e., in the homodisplacement process) while pure buffer solution and human serum albumin solutions induced desorption or exchange of fibronectin to lower and similar degrees. An increase of the total adsorbed amount of protein due to additional adsorption of fibronectin or human serum albumin accompanied the partial exchange of the preadsorbed fibronectin in the displacement experiments. Evaluation of the kinetics of desorption and exchange of fibronectin at any of the substrates revealed two kinds of surface-attached protein populations--a fast desorbing species and a species with a slow desorption and exchange rate. By a multivariate regression analysis the surface characteristics of the polymer substrate were confirmed to determine the degree of protein desorption and exchange while the dynamics of the layer alteration was found to solely depend on the diffusion behavior of the proteins.

Chemical Phenomena↗
PubMed1982

Association of fibronectin with carboxy-group-modified proteins in vitro.

Treatment of human immunoglobulin G, albumin and fibronectin with water-soluble carbodi-imide at pH4.75 in the presence of glycine ethyl ester resulted in an avid binding of (125)I-labelled native fibrinectin to the modified proteins. Succinoylation, reduction and alkylation or heat-denaturation had no such effect. In affinity chromatography under physiological conditions, serum was depleted of fibronectin when run through columns of the carbodi-imide-treated proteins coupled to agarose. Fractions eluted from such columns with urea were enriched in fibronectin. The binding of radiolabelled fibronectin to the carbodi-imide-treated proteins was inhibited by unlabelled fibronectin in relatively low concentrations, but also by albumin in higher concentrations. Heat-denatured albumin inhibited at concentrations approx. 10-30 times lower than native albumin. The binding reaction had a pH optimum of 6-8. It was inhibited at high ionic strength and in the presence of urea. Anionic detergents inhibited at millimolar concentrations, but non-ionic detergents did not inhibit the binding reaction. The results were interpreted as showing that: (1) fibronectin is capable of binding to itself, to immunoglobulin G and to albumin after a reduction of the negative surface charge of these proteins, and may have a general ability to bind such modified proteins; (2) this binding can take place under physiological conditions; (3) carboxy-group-modified proteins selectively bind fibronectin from serum. This novel binding phenomenon could be important in terms of the opsonin function of circulatory fibronectin. We propose that fibronectin may recognize modified (denatured) proteins and mediate their uptake by the reticuloendothelial system.

Cations, Divalent↗
PubMed1998

Entry of OpaA+ gonococci into HEp-2 cells requires concerted action of glycosaminoglycans, fibronectin and integrin receptors.

Heparan sulphate proteoglycans are increasingly implicated as eukaryotic cell surface receptors for bacterial pathogens. Here, we report that Neisseria gonorrhoeae adheres to proteoglycan receptors on HEp-2 epithelial cells but that internalization of the bacterium by this cell type requires the serum glycoprotein fibronectin. Fibronectin was shown to bind specifically to gonococci producing the OpaA adhesin. Binding assays with fibronectin fragments located the bacterial binding site near the N-terminal end of the molecule. However, none of the tested fibronectin fragments supported gonococcal entry into the eukaryotic cells; a 120 kDa fragment carrying the cell adhesion domain with the amino acid sequence RGD even inhibited the fibronectin-mediated uptake of MS11-OpaA. This inhibition could be mimicked by an RGD-containing hexapeptide and by alpha 5 beta 1 integrin-specific antibodies, suggesting that interaction of the central region of fibronectin with integrin receptors facilitated bacterial uptake. Fibronectin was unable to promote gonococcal entry into HEp-2 cells that had been treated with the enzyme heparinase III, which degrades the glycosaminoglycan side-chains of proteoglycan receptors. On the basis of these results, we propose a novel cellular uptake pathway for bacteria, which involves the binding of the pathogen to glycosaminoglycans that, in turn, act as co-receptors facilitating fibronectin-mediated bacterial uptake through integrin receptors. In this scenario, fibronectin would act as a molecular bridge linking to Opa-proteoglycan complex with host cell integrin receptors.

3T3 Cells↗
PubMed2001

The pavA gene of Streptococcus pneumoniae encodes a fibronectin-binding protein that is essential for virulence.

Streptococcus pneumoniae colonizes the nasopharynx in up to 40% of healthy subjects, and is a leading cause of middle ear infections (otitis media), meningitis and pneumonia. Pneumococci adhere to glycosidic receptors on epithelial cells and to immobilized fibronectin, but the bacterial adhesins mediating these reactions are largely uncharacterized. In this report we describe a novel pneumococcal protein PavA, which binds fibronectin and is associated with pneumococcal adhesion and virulence. The pavA gene, present in 64 independent isolates of S. pneumoniae tested, encodes a 551 amino acid residue polypeptide with 67% identical amino acid sequence to Fbp54 protein in Streptococcus pyogenes. PavA localized to the pneumococcal cell outer surface, as demonstrated by immunoelectron microscopy, despite lack of conventional secretory or cell-surface anchorage signals within the primary sequence. Full-length recombinant PavA polypeptide bound to immobilized human fibronectin in preference to fluid-phase fibronectin, in a heparin-sensitive interaction, and blocked binding of wild-type pneumococcal cells to fibronectin. However, a C-terminally truncated PavA' polypeptide (362 aa residues) failed to bind fibronectin or block pneumococcal cell adhesion. Expression of pavA in Enterococcus faecalis JH2-2 conferred > sixfold increased cell adhesion levels to fibronectin over control JH2-2 cells. Isogenic mutants of S. pneumoniae, either abrogated in PavA expression or producing a 42 kDa C-terminally truncated protein, showed up to 50% reduced binding to immobilized fibronectin. Inactivation of pavA had no effects on growth rate, cell morphology, cell-surface physico-chemical properties, production of pneumolysin, autolysin, or surface proteins PspA and PsaA. Isogenic pavA mutants of encapsulated S. pneumoniae D39 were approximately 104-fold attenuated in virulence in the mouse sepsis model. These results provide evidence that PavA fibronectin-binding protein plays a direct role in the pathogenesis of pneumococcal infections.

Adhesins, Bacterial↗
PubMed1999

Elevated urinary fibronectin levels after transurethral resection of bladder tumour: a possible role in patients failing therapy with bacillus Calmette-Guérin.

OBJECTIVE: To investigate fibronectin levels in urine samples from patients with noninvasive transitional cell carcinoma (TCC) of the bladder immediately and for 4 weeks after transurethral resection of bladder tumour (TURBT), to determine whether soluble fibronectin within the bladder, which blocks the attachment of bacillus Calmette-Guérin (BCG), might lower the efficacy of BCG therapy over this period. PATIENTS AND METHODS: Urinary fibronectin was measured using an enzyme-linked immunosorbent assay in 25 patients with superficial bladder TCC who underwent TURBT for complete resection. Eight samples were collected for each patient, one before and seven during the 4 weeks after TURBT. RESULTS: High levels of urinary fibronectin were detected in 18 patients (72%) after TURBT. In 16 patients the fibronectin level returned to normal within 2 weeks of surgery. The other two patients showed elevated levels of fibronectin for > 4 weeks. CONCLUSIONS: These results show that urinary fibronectin concentration is significantly increased in most patients after TURBT and this should be considered in patients who receive BCG therapy. Treatment within the first 2 weeks after TURBT may be associated with a high failure rate, as urinary fibronectin levels were increased significantly in about three-quarters of these patients during that period. Indeed, the persistent elevation of fibronectin, occurring in two of the present patients, may be responsible for some of the failures of BCG therapy when it is administered 2-5 weeks after surgery.

BCG Vaccine↗
PubMed1999

Role of fibronectin deposition in cystogenesis of Madin-Darby canine kidney cells.

BACKGROUND: Madin-Darby canine kidney (MDCK) cells cultured within collagen I gel exhibit clonal growth and form spherical multicellular cysts. The cyst-lining epithelial cells are polarized with the basolateral surface in contact with the collagen gel and the apical surface facing the lumen. To understand whether MDCK cysts construct the basal lamina, we characterized the composition of the extracellular matrix deposited by MDCK cysts. The cyst-lining cells produced an apparently incomplete basal lamina containing a discontinuous laminin substratum. In addition, the basal cell surface of the cyst was surrounded by a thick layer of fibronectin. This study was conducted to delineate the role of fibronectin deposition in cystogenesis. METHODS: MDCK cells cultured in collagen gel were employed. We first used Arg-Gly-Asp (RGD) peptides containing disintegrin rhodostomin to disturb the interaction between fibronectin and the cell surface integrin. We then established several stable transfectants expressing the fibronectin antisense RNA and with which to directly examine the role of fibronectin in cystogenesis. RESULTS: Rhodostomin markedly decreased the growth rates of the MDCK cyst, suggesting the importance of a normal interaction between fibronectin and integrins. The stable transfectants overexpressing the fibronectin antisense RNA exhibited relatively lower levels of fibronectin and markedly lower cyst growth rates than the control clone. The lower growth rate was correlated with an increase in collagen gel-induced apoptosis. CONCLUSIONS: The results indicate that the deposition of fibronectin underlying the cyst-lining epithelium serves to prevent apoptosis induced by three-dimensional collagen gel cultures, and hence facilitates cyst growth of MDCK cells.

Animals↗
PubMed2000

Role of fibronectin deposition in branching morphogenesis of Madin-Darby canine kidney cells.

BACKGROUND: Madin-Darby canine kidney (MDCK) epithelial cells grown in collagen gels in the presence of hepatocyte growth factor (HGF) form branching tubules. The tubule-lining epithelial cells are polarized with the basolateral surface in contact with the collagen gel and the apical surface facing the lumen. To delineate whether MDCK branching tubules construct the basal lamina, we characterized the composition of the extracellular matrix deposited by MDCK tubules. The tubule-lining cells produced an apparently incomplete basal lamina containing a discontinuous laminin substratum. In addition, a thick layer of fibronectin surrounded the basal cell surface of the branching tubule. In an attempt to delineate the role of fibronectin deposition in branching morphogenesis, we conducted this study. METHODS: MDCK cells cultured in collagen gel were employed. We first used arginine-glycine-aspartate peptides containing disintegrin rhodostomin to disturb the interactions between fibronectin and cell surface integrins. Furthermore, we established several stable transfectants expressing fibronectin antisense RNA to examine the role of fibronectin in branching morphogenesis directly. RESULTS: Rhodostomin inhibited the formation of branching tubules. The transfectants expressing fibronectin antisense RNA exhibited relatively lower levels of synthesized fibronectin and markedly diminished growth rates of branching tubules than the control clone. An inhibition of branching morphogenesis induced by the overexpression of fibronectin antisense RNA was manifested by the decrease in cell growth rates and cell migration. CONCLUSION: These results indicate that the deposition of fibronectin underlying the tubule-lining epithelium serves to enhance cell proliferation and migration, and hence facilitates the branching tubulogenesis of MDCK cells.

Animals↗
PubMedDate not supplied

Effect of cardiopulmonary bypass on plasma fibronectin, IgG, and C3.

The effect of cardiopulmonary bypass operations on the concentration of plasma fibronectin, IgG, and C3 was studied in 28 patients. During cardiopulmonary bypass operations, plasma IgG, and C3 decreased to about 45 percent of their preoperative concentrations, probably as a result of hemodilution and blood loss. On the average, plasma fibronectin decreased significantly more (p less than 0.002), to 32 percent of its preoperative concentration, probably as a result of hemodilution, blood loss, and consumption. We assumed that consumption of fibronectin occurred when its concentration decreased more than the concentrations of IgG and C3. Interestingly, consumption of fibronectin during bypass operations was not demonstrated in seven of the 28 patients who did not require blood products within the 24-hour period after operation. We suggest that consumption, rather than dilution, of plasma fibronectin might be clinically important. A significant (p less than 0.002) negative correlation was observed between the length of the bypass and the concentration of plasma fibronectin during this 24-hour period. We also studied the rate of regeneration of fibronectin, IgG, and C3 in 12 of these patients. The concentrations of fibronectin and C3 were normal by the fifth postoperative day. The rate of regeneration of IgG, however, was slower than that of fibronectin and C3.

Aged↗
PubMed1998

Fetal fibronectin as a predictor of preterm birth: an overview.

The objective of this study was to determine if cervicovaginal fibronectin is predictive of preterm birth. Articles involving human subjects published in English between January 1976 and December 1997 were retrieved from MEDLINE using the keywords: fibronectin, fetal fibronectin, oncofetal fibronectin, preterm, PROM, preterm birth, and preterm labor. We included studies that were prospective, enrolled women at less than 37 weeks' gestation and blinded caregivers to the fetal fibronectin test results. Of the 24 studies meeting the inclusion criteria, 15 included symptomatic women; 8 included asymptomatic women; and 1 study included both. Data were abstracted independently by two authors and a meta-analysis of results of test characteristics, using summary values, was undertaken where possible. For symptomatic women, the sensitivity for delivery within 7 to 10 days of sampling was excellent (summary value [95% confidence interval ¿CI¿]: 98% [95%, 100%]). For delivery within 14 days, the sensitivity was somewhat lower (summary value [95% CI]: 82% [74%, 90%]) and lower still for delivery within 21 days (summary value [95% CI]: 73% [67%, 80%]). For delivery less than 34 weeks the sensitivity was good, but poor for delivery less than 37 weeks (summary value [95% CI]: 87% [81%, 94%], 54% [51%, 58%] respectively). For asymptomatic women, the sensitivity of fetal fibronectin for delivery less than 34 and less than 37 weeks was poor (summary value [95% CI]: 43% [36%, 50%] and 64%[57%, 71%] respectively). The specificity of fetal fibronectin for symptomatic and asymptomatic women was over 80% for all outcomes. For symptomatic women, a negative test for fetal fibronectin should be useful at ruling out the likelihood of delivery within 7 to 10 days of sampling. For asymptomatic women, testing for fetal fibronectin is unlikely to be useful as many women at risk will be misclassified as normal.

Body Fluids↗