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PubMed1993

Interaction of human plasma fibronectin with alpha-elastin.

Because there are contradictory reports about the interaction of plasma fibronectin with elastin, we investigated the interaction in vitro. When human plasma was applied to an alpha-elastin-Sepharose column at 4 degrees C, the column-binding fraction contained fibronectin. When isolated plasma fibronectin was applied to the same column at 4 degrees C, most of the fibronectin bound to the column and was eluted with 1 M KBr. However, the binding affinity of plasma fibronectin to the alpha-elastin-Sepharose column was much weaker at 25 degrees C than at 4 degrees C. The elastin-plasma fibronectin interaction was further confirmed by demonstrating the binding of alpha-elastin to fibronectin on polyvinylidene difluoride membranes using an alpha-elastin specific antibody. The elevation of the surface hydrophobicity of plasma fibronectin at 4 degrees C was observed by hydrophobic chromatography, using alkyl-Sepharose columns. It seems that the binding of plasma fibronectin to alpha-elastin involves hydrophobic interaction, which is affected by temperature and possibly by other factors.

Chromatography, Affinity↗
PubMed1994

Cell-free formation of disulfide-bonded multimer from isolated plasma fibronectin in the presence of a low concentration of SH reagent under a physiological condition.

Purified plasma fibronectin in Tris-buffered saline aggregated on incubation at 37 degrees C in the presence of dithiothreitol without the presence of cells. On SDS polyacrylamide gel electrophoresis without reduction, dimeric fibronectin showed a 460 kDa band, while the protein band of aggregated fibronectin remained at the top of the running gel. The aggregate was a disulfide-bonded multimer, since both the dimeric and the multimeric fibronectins migrated as 230 kDa polypeptides after reduction. The multimer formation required SH reagent and proceeded faster with higher SH concentration, suggesting the occurrence of a disulfide exchange reaction during the aggregation. Since dimeric fibronectin with carboxymethylated sulfhydryl groups also formed multimers under the same condition, the free sulfhydryl groups of dimeric fibronectin may not be involved in the multimer formation, suggesting involvement of disulfide exchange from intramolecular bonds to intermolecular bonds. The multimerization was not influenced by Na+, Ca2+, or EDTA, while urea-treated fibronectin required a higher concentration of dithiothreitol for multimer formation. Fibronectin partially degraded by m-calpain did not form multimers. The multimeric fibronectin retained heparin-binding and cell attachment activities, but had lost gelatin-binding activity. Involvement of the terminal regions containing type I and type II repeats was suggested in the interaction of pFN leading to the multimerization.

Animals↗
PubMed1981

Characterization of porcine plasma fibronectin and its fragmentation by porcine liver cathepsin B.

Fibronectin was isolated from porcine plasma by affinity chromatography with gelatin-linked Sepharose 4B. Porcine fibronectin had a chemical composition similar to those of human and other fibronectins and reacted with antiserum raised against human fibronectin. It showed hemagglutination activity with trypsin-treated rabbit erythrocytes, though the activity was far less than that of human fibronectin. Porcine plasma fibronectin consisted of two subunit chains of about 230,000-daltons linked by disulfide bonds(s). Limited proteolysis of this protein with porcine liver cathepsin B yielded five major fragments which were investigated by affinity chromatography with gelatin- and heparin-linked Sepharose 4B. One fragment (Mr = 50,000) was bound to gelatin but not to heparin, while the remaining four were bound to heparin but not to gelatin, suggesting that plasma fibronectin takes a discrete domain structure with respect to interaction with these two macromolecules. The three larger heparin-binding fragments, Mr = 175,000, 150,000, and 130,000 were eluted with different concentrations of a mixture of NaCl and urea from the heparin-column, suggesting that they have different interactions with heparin, the 130,000-dalton fragment being the one with the strongest interaction. After reduction with 2-mercaptoethanol, the 175,000-dalton fragment was converted to the 150,000-dalton region fragment, which, together with the unchanged 150,000-dalton fragment, appeared to be equivalent in amount to the 130,000-dalton fragment. This finding suggests that the 150,000- and 130,000-dalton fragments may have originated from different subunit chains. Since the 175,000-dalton fragment was not produced by cathepsin B digestion of fibronectin which had been treated with plasmin, it was concluded that the 175,000-dalton fragment contained interchain disulfide bond(s) which had linked the native subunit chains. These results suggest that porcine plasma fibronectin has non-identical subunit chains composed of domains which differ in interaction with heparin and in susceptibility to cathepsin B.

Amino Acids↗
PubMed1984

Isolation and characterization of human placenta fibronectin.

Fibronectin was isolated from human placenta tissues and compared with human plasma fibronectin. Placenta and plasma fibronectins had similar amino acid compositions, immunological properties, and cell attachment-promoting activities, but differed in apparent molecular weight on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, which could be accounted for at least partly by the difference in carbohydrate composition. Unlike plasma fibronectin, placenta fibronectin failed to form a precipitin line with concanavalin A in a double diffusion system. The non- or low-reactivity of placenta fibronectin with this lectin was also demonstrated by affinity chromatography with concanavalin A-agarose, in which more than 90% of the radiolabeled glycopeptides derived from placenta fibronectin was not retained on the gel. The two fibronectins also differed in the reactivity with Lens culinaris agglutinin of their glycopeptide fractions. These data indicate that placenta and plasma fibronectins are different in their carbohydrate structures and, therefore, suggest the presence of a tissue- or cell-specific mechanism for processing the carbohydrates of this glycoprotein.

Amino Acids↗
PubMed1995

Intracrine role of progesterone in fibronectin production and deposition by chicken ovarian granulosa cells in vitro: effect of extracellular calcium.

The role of extracellular Ca2+ in progesterone-induced fibronectin production and deposition by hen granulosa cells was studied. Granulosa cells isolated from preovulatory follicles of the chicken ovary were incubated in Ca(2+)-deficient or Ca(2+)-containing medium 199, and the amount of total fibronectin produced (fibronectin deposited in the matrix, secreted into the medium, or associated with cells) was measured by ELISA. The quantity of fibronectin deposited as well as the total amount of fibronectin produced in the presence or absence of exogenous progesterone was suppressed in Ca(2+)-deficient medium. It required greater concentrations of exogenous progesterone to significantly increase fibronectin production in Ca(2+)-deficient medium than in Ca(2+)-replete medium. Cyanoketone, an inhibitor of progesterone synthesis, suppressed total fibronectin produced by unstimulated cells both in the absence and presence of Ca2+. However, the inhibitory effect of cyanoketone was significantly less in Ca(2+)-replete medium than in Ca(2+)-deficient medium. Exogenous progesterone reversed completely the inhibitory effects of cyanoketone. In the presence of cyanoketone, progesterone caused a greater (3-fold) increase in fibronectin production in Ca(2+)-replete medium than in the absence of Ca2+. Thapsigargin, an agent that mobilizes Ca2+ from internal stores, suppressed basal and progesterone-induced fibronectin production in the absence and presence of cyanoketone. However, the inhibitory effect of thapsigargin was significantly reduced in Ca(2+)-replete medium.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1999

Nitric oxide mediates LC-3-dependent regulation of fibronectin in ductus arteriosus intimal cushion formation.

Ductus arteriosus intimal cushion formation is characterized by fibronectin-dependent smooth muscle cell (SMC) migration. Enhanced fibronectin synthesis in ductus SMC is regulated by the interaction of LC-3, a microtubule-associated protein, with an AU-rich element (ARE) in the 3'-untranslated region of fibronectin mRNA, facilitating its recruitment to polyribosomes for translation. Since nitric oxide (NO) is implicated in posttranscriptional gene regulation and is produced in the ductus, we investigated its mechanistic role in LC-3-mediated fibronectin synthesis. NO production was sevenfold higher in ductus vs. aortic SMC (P<0.005) associated with increased neuronal NO synthase (nNOS) expression. The NOS inhibitor L-NMMA decreased fibronectin synthesis by approximately 45-50% (P<0.05), whereas the NO donor, SNAP, increased ductus fibronectin synthesis approximately onefold (P<0.05); neither agent altered fibronectin mRNA levels. Immunoblotting revealed that SNAP increased and L-NMMA reduced a membrane-associated phosphorylated form of LC-3. RNA gel mobility shift assays confirmed that NO enhanced LC-3 binding to the fibronectin mRNA ARE. Our studies indicate a tissue-specific program in the ductus arteriosus whereby elevated nNOS expression and NO production regulate the posttranscriptional increase in fibronectin synthesis required for SMC motility.

3' Untranslated Regions↗
PubMed1983

Lung vascular permeability after reversal of fibronectin deficiency in septic sheep. Correlation with patient studies.

Plasma fibronectin deficiency and opsonic dysfunction exist in critically ill septic surgical, trauma, and burn patients with multiple organ failure. Fibronectin deficiency can be reversed by infusion of fresh plasma cryoprecipitate. The influence of therapy with human cryoprecipitate on lung vascular permeability in septic sheep with plasma fibronectin deficiency following surgery was evaluated. Additionally, selected studies on pulmonary function in septic surgical and trauma patients after infusion of plasma cryoprecipitate were completed. In patients, ventilation-perfusion balance appeared to improve as measured by the multiple inert gas elimination technique. With the lung lymph fistula preparation in fibronectin deficient sheep, infusion of human plasma cryoprecipitate (10 units; 250 ml) delayed the onset and minimized the increase in lung vascular permeability during postoperative Pseudomonas sepsis (5 X 10(9) bacteria, I.V.; 5 X 10(10) bacteria, I.P.). For example, in a first group of sheep, the transvascular protein clearance (TPC) at 2 hrs in septic sheep (n = 4) treated with only saline (volume control) was 20.1 +/- 3.1 ml/hr, compared to 11.23 +/- 0.83 ml/hr in the sheep (n =a 4) treated with fibronectin-rich cryoprecipitate (p less than 0.05). In a second group of sheep, cryoprecipitate depleted of fibronectin by affinity chromatography was used as the control solution. It also did not manifest this protective effect with respect to lung vascular permeability. Thus, at 2 hrs the lymph flow (Qlym) was 30.2 ml/hr and the transvascular protein clearance (TPC) was 18.0 ml/hr in septic sheep given fibronectin-deficient cryoprecipitate. In contrast, in the fibronectin-rich cryoprecipitate treated sheep, the Qlym was 14.8 ml/hr and the TPC was 8.12 ml/hr. It is suggested that fibronectin may influence lung vascular integrity during sepsis following surgery and trauma.

Adolescent↗
PubMed1994

Promotion of Escherichia coli adherence to rubber slices by adsorbed fibronectin.

Biomaterial-associated infections are a problem in the use of endoprosthetic materials in the palliative treatment of malignant obstructive jaundice. Fibronectin has been reported to mediate adherence of bacteria to host tissue and biomaterials. Adsorption of fibronectin to rubber--representing material used for biliary drainage--and subsequent adherence of Escherichia coli strain PSS1 and E. coli strain NG7C (which binds to immobilised fibronectin) were investigated. Quantitative adsorption of fibronectin to rubber slices was studied with 125I-labelled, purified human plasma fibronectin. In buffer solutions, fibronectin showed a high affinity for rubber slices. Adherence of the E. coli strains to uncoated rubber slices was similar and was significantly inhibited by the presence of plasma components and bile. Adherence of E. coli PSS1 to fibronectin-coated slices was poor. In contrast, E. coli NG7C adhered efficiently to coated slices in proportion to the amount of adsorbed fibronectin; adherence was not reduced by the presence of albumin or bile, or the fibronectin-binding ligands gelatin, heparin and fibrinogen. However, pre-digestion of coated slices with trypsin significantly reduced adherence.

Adsorption↗
PubMed1984

Fibronectin in basal cell epithelioma: sources and significance.

Nodular basal cell epitheliomas (BCE) contain fibronectin both within tumor nodules and at the nodule-stroma interface (basement membrane zone). Fibronectin within or at the periphery of tumor nodules could be derived from the tumor cells, from entrapped stroma, or from plasma. The present study was designed to elucidate the source(s) of fibronectin within BCE nodules. If stromal entrapment occurred to any great extent, von Willebrand factor VIII:Ag-stained blood vessels within tumor nodules should be evident by immunofluorescence techniques. Likewise, if plasma proteins were deposited in BCE, the tumor nodules should stain with fluorescein-conjugated antifibrinogen antibodies. Therefore, 6 basal cell epitheliomas were double labeled with rhodamine-conjugated antihuman fibronectin and fluorescein-conjugated antihuman factor VIII:Ag or fluorescein-labeled antihuman fibrinogen. Fibronectin was present in a linear disposition along the margin of tumor lobules and as a fine filamentous deposit in the central portions of tumor tissue. There was no evidence of fibrinogen or factor VIII:Ag in any of the tumor lobules. Factor VIII:Ag was present in a granular pattern within blood vessel walls that coursed between tumor nests. An indirect immunoperoxidase technique using rabbit antihuman fibronectin and peroxidase-labeled goat antirabbit IgG demonstrated that fibronectin within the central portion of the tumor lobules was closely associated with the tumor cells. The absence of fibrinogen and factor VIII:Ag within the tumor tissue indicates that the fibronectin is probably not plasma- or stroma-derived while immunoperoxidase data suggest that fibronectin may be a product of BCE cells.

Antigens↗
PubMed1995

Ganglioside GT1b inhibits keratinocyte adhesion and migration on a fibronectin matrix.

Highly sialylated gangliosides have been shown to alter cellular adhesion to a fibronectin matrix. The effect of these gangliosides on the adhesion, spreading, and migration of cultured keratinocytes on a fibronectin matrix has not been explored. Ganglioside GT1b significantly prevented attachment of keratinocytes to fibronectin and also detached previously adherent keratinocytes in a concentration-dependent manner without cell toxicity. GT1b did not affect adhesion of keratinocytes to wells coated with laminin, type I or type IV collagen, 804G extracellular matrix, or albumin. GT1b also inhibited keratinocyte migration on fibronectin in a concentration-dependent manner at concentrations as low as 5 nM GT1b, but had no effect on migration of keratinocytes plated on other matrices. GT1b binds to intact fibronectin and to the 120-kD RGDS-containing cell-binding fibronectin fragment, but not to the heparin- or gelatin-binding fragments of fibronectin. Although RGDS competes with GT1b in inhibiting adhesion, GT1b does not diminish binding of keratinocytes to a derivatized RGDS substratum, suggesting that the GT1b effect involves a non-RGDS site in the cell-binding region that modulates RGDS/alpha 5 beta 1 integrin receptor interaction. Through a specific effect on keratinocyte interaction with fibronectin, GT1b may participate in the regulation of cell adhesion and migration on a fibronectin substratum, which are important events during wound healing and the spreading of cutaneous neoplasia.

Cell Adhesion↗
PubMed1992

Degradation of fibronectin and vitronectin in chronic wound fluid: analysis by cell blotting, immunoblotting, and cell adhesion assays.

We used a combination of cell blotting, immunoblotting, and cell adhesion assays to analyze fibronectin and vitronectin in wound fluid from acute and chronic wounds. Acute wound fluid (e.g., suction blister fluid, mastectomy fluid) contained intact fibronectin and vitronectin as major cell adhesion proteins. In marked contrast, chronic wound fluid samples from three of 11 patients with venous stasis ulcers showed complete degradation of vitronectin and degradation of fibronectin into small molecular mass polypeptides less than 125 kDa. Three of these polypeptides--54, 93, and 125 kDa--were biologically active in promoting cell attachment and were recognized by monoclonal antibodies that bind fibronectin near the arg-gly-asp (RGD) domain. In wound fluid samples from the other eight of 11 patients, only slight degradation of vitronectin and fibronectin occurred, which resulted in a mixture of mostly intact molecules along with large fragments. Intact fibronectin in chronic wound fluid samples contained the ED-A domain, which showed that fibronectin synthesis occurred locally in the wound bed. Wound fluid containing extensively degraded vitronectin and fibronectin reversibly inhibited cell adhesion, and excess fetal bovine serum, but not purified fibronectin, neutralized the inhibitory effect. We suggest that protease activity in some chronic wounds may cause degradation of adhesion proteins and prevent cell adhesion necessary for normal wound closure.

Animals↗
PubMed1987

Increased plasma fibronectin concentrations in obesity: normalization during weight loss.

In 23 morbidly obese patients we investigated the influence of a large weight loss (30.6 kg, range 17.5-90.8) on the plasma fibronectin concentrations. Further, changes in plasma fibronectin were related to serum insulin levels and to liver biochemistry. Between the measurements patients had been treated with an intermittent very-low-calorie formula diet sufficient in respect to protein, minerals and vitamins. They were investigated in weight-stable states. Before weight reduction, 14 patients (61%, 95% confidence limits 39-80%) had elevated plasma fibronectin levels. Plasma fibronectin decreased (medians 1.22 and 0.59 mumol/l before and after weight loss, p less than 0.01) and was after weight loss within the normal range in 14 patients. The change in plasma fibronectin was unassociated with the magnitude of the weight loss as well as with the reduction of overweight. The resulting plasma fibronectin levels were also uncorrelated with the body weight and with the final degree of overweight. Serum insulin decreased (p less than 0.01) during the weight reduction and the change correlated (p less than 0.05) with the change in plasma fibronectin. Serum lactate dehydrogenase, which is associated with the degree of hepatic fatty change, declined (p less than 0.01), but the individual change was unrelated with the change in plasma fibronectin. In conclusion, the elevated plasma fibronectin levels in morbidly obese subjects seem to normalize during weight loss. We suggest the normalization to be mediated--at least in part--by a reduction of the insulin levels.

Adult↗
PubMed1991

Stimulation of fibronectin secretion in cultured human keratinocytes by transforming growth factor-beta not by other growth inhibitory substances.

We investigated the effects of various growth inhibitory substances on fibronectin secretion in cultured normal human keratinocytes. Fibronectin secretion in keratinocytes was expressed by two methods: immunofluorescent staining of cells with anti-human fibronectin antibody, and sodium dodecyl-sulphate-polyacrylamide gel electrophoresis of [35S]-labeled proteins secreted by the cells followed by autoradiography. With immunofluorescent staining, the extracellular fibronectin was observed as coarse fibrils only in some cells of the control culture, while cells treated with 20 ng/ml transforming growth factor-beta 1 (TGF-beta 1) showed intense fluorescences in a radiating pattern around most of the cells, indicating that TGF-beta 1 markedly increased fibronectin secretion in keratinocytes. Analysis of [35S]-methionine labeled proteins also revealed that TGF-beta 1 increased fibronectin secretion eight fold in culture medium. TGF-beta 2 has also induced weak increase of fibronectin secretion 1.8 fold in keratinocytes. In contrast, other growth inhibitory substances, such as tumor necrosis factor-alpha, 1,25-dihydroxyvitamin D3 and cyclosporin A, did not show any significant effects on fibronectin secretion. These results indicated that increase of fibronectin secretion is not associated with growth inhibitory effect, but rather with a specific effect of TGF-beta.

Cells, Cultured↗
PubMed1991

Inhibitory effect of fibronectin and its recombinant polypeptides on the adhesion of metastatic melanoma cells to laminin.

We have utilized recombinant fibronectin fragments with cell-binding domain (C-274), heparin-binding domain (H-271) or CS1 peptide in type III connecting segment (IIICS) and their fusion polypeptides such as CH-296 (containing C-274, H-271 and CS1), CH-271 (containing C-274 and H-271) and C-CS1 (containing C-274 and CS1) to investigate the mechanism of the fibronectin-mediated inhibitory effect on tumor cell adhesion to laminin as well as fibronectin. These fragments retained cell adhesion-promoting and/or heparin-binding properties when they were immobilized on a surface. Pretreatment of tumor cells with CH-296 or CH-271 suppressed cell adhesion to both laminin and fibronectin. H-271 at the high concentration of 500 micrograms/ml slightly inhibited cell adhesion to laminin (but not to fibronectin), whereas C-274, C-CS1 or a mixture of C-274, H-271 and CS1 (similar molar ratio to CH-296) inhibited cell adhesion to fibronectin but not to laminin. On the other hand, tumor cell adhesion to laminin-substrate was also inhibited by heparin or heparan sulfate, which were able to bind to laminin, suggesting that heparin-like molecules on the cell surface may be included among the laminin receptors. These results indicated that the co-presence of cell- and heparin-binding domains of fibronectin may be required for the fibronectin-mediated inhibitory effect on tumor cell adhesion to laminin, and that the interaction of the heparin-binding domain of fibronectin with the cell surface leads to the inhibition of the cell adhesion to laminin.

Amino Acid Sequence↗
PubMed1991

Multifunctional nature of P fimbriae of uropathogenic Escherichia coli: mutations in fsoE and fsoF influence fimbrial binding to renal tubuli and immobilized fibronectin.

P fimbriae of the F7(1) serotype of Escherichia coli are composed of a major subunit, FsoA, and of three minor proteins named FsoG, FsoE, and FsoF. FsoG is the Gal alpha(1-4)Gal-specific lectin. We assessed mutated recombinant strains each deficient in one fimbrial component for adhesion to frozen sections of rat cortical kidney and to fibronectin immobilized on glass. Rat kidney lacks the Gal alpha(1-4)Gal-containing glycolipids. The fsoG mutant strain was as adhesive to sections of rat kidney and to fibronectin-coated glass as was the recombinant strain expressing the complete fso gene cluster. The fsoA mutant strain was highly adhesive to fibronectin and to kidney sections. In the rat kidney, the adhesion of these strains was predominantly localized to sites of basolateral membranes of tubuli. The fsoE and the fsoF mutant strains were slightly less adhesive to kidney structures and failed to adhere to fibronectin. The fsoE, fsoF double mutant strain adhered neither to fibronectin nor to kidney sections. None of the fso recombinant strains reacted with soluble fibronectin, suggesting that the interaction is dependent on the conformation of the fibronectin molecules. Recombinant strains expressing the F7(2), F8, F11, F13, and F14 serovariants of the P fimbria also showed adherence to immobilized fibronectin. The results show that in addition to binding to globoseries of glycolipids via the G protein, the P fimbriae of uropathogenic E. coli exhibit a tissue-binding property influenced by fsoE and fsoF gene products and with affinity for basolateral membranes and fibronectin.

Amino Acid Sequence↗
PubMed1993

Two different genes coding for fibronectin-binding proteins from Streptococcus dysgalactiae. The complete nucleotide sequences and characterization of the binding domains.

The binding of Streptococcus dysgalactiae to fibronectin involves fibronectin-binding protein(s) present on the bacterial surface. Previously, we reported the cloning of two different genes coding for cell-wall-associated fibronectin-binding proteins from S. dysgalactiae strain S2 [Lindgren, P.-E., Speziale, P., McGavin, M. J., Monstein, H.-J., Höök, M., Visai, L., Kostiainen, T., Bozzini, S. & Lindberg, M. (1992) J. Biol. Chem. 267, 1924-1931]. The two genes, fnbA and fnbB, have now been sequenced and the primary amino acid sequences of the two fibronectin-binding proteins, FnBA and FnBB, have been deduced. The two proteins have predicted molecular masses of 117 kDa and 122 kDa, respectively, and are organized in a similar way. The fibronectin-binding activities are localized in repeated motifs, 32-37 amino acids long, in the COOH-terminal regions of the proteins. The two fibronectin-binding proteins have heterologous amino acid sequences, except for the COOH-terminal ends which include the fibronectin-binding repeats. The fibronectin-binding regions of the genes have been fused to IgG-binding domains of protein A, utilizing the IgG-binding capacity of the resulting fusion proteins, to facilitate isolation of the fibronectin-binding domains.

Adhesins, Bacterial↗
PubMed2000

Cervicovaginal fibronectin and cervical length at 23 weeks of gestation: relative risk of early preterm delivery.

OBJECTIVES: To establish the prevalence of cervicovaginal fetal fibronectin positivity at 23 weeks of gestation in a routine population of singleton pregnancies and determine the relative risk of spontaneous delivery before 33 weeks in women with a fibronectin positive result. DESIGN: Prospective clinical study. SETTING: Inner city antenatal clinic. POPULATION: Singleton pregnancies attending for routine antenatal care. METHODS: Cervicovaginal fetal fibronectin and cervical length were measured at 23 weeks of gestation. The distribution of fibronectin positivity within subgroups according to maternal characteristics was calculated and the relative risk of spontaneous delivery before 33 weeks was estimated. MAIN OUTCOME MEASURES: Prevalence of a fibronectin positive result and its relation to cervical length measurement and spontaneous preterm delivery before 33 weeks. RESULTS: Of 5,146 women participating in the study, 182 (3.5%) had a fibronectin positive result and 76 (1.5%) had a cervical length of < 15 mm. Fibronectin positive women were more likely to be Afro-Caribbean in origin, to have had a previous second trimester miscarriage and to have a short cervix. In the 5,068 women who were managed expectantly, the significantly independent relative risk of spontaneous delivery at < 33 weeks was 46.2 (95% CI 18.8-113.6), for cervical length of < or = 15 mm, 8.1 (95% CI 3.8-17.5) for a fibronectin positive result, and 4.4 (95% CI 2.2-9.1) for cigarette smoking. CONCLUSION: Fibronectin positivity at 23 weeks of gestation provides useful prediction of pregnancies at risk of spontaneous preterm delivery before 33 weeks, with a relative risk that is twice as high as cigarette smoking, but is a sixth of that of cervical length.

Adult↗
PubMed2000

Prostaglandin endoperoxide H synthase mRNA expression in the fetal membranes correlates with fetal fibronectin concentration in the cervico-vaginal fluids at term: evidence of enzyme induction before the onset of labour.

OBJECTIVE: To determine the relationship of prostaglandin endoperoxide H synthase (PGHS) expression in the gestational tissues and fetal fibronectin in cervico-vaginal fluids before the onset of labour at term. DESIGN: Cross-sectional, observational study. SAMPLES: Amnion, chorion laeve and decidua were collected from 24 term pregnant women following elective caesarean section. Samples of cervico-vaginal secretions were obtained from the same women immediately before caesarean section. METHODS: PGHS-1 and PGHS-2 mRNA levels in tissues were determined by specific ribonuclease protection assays. Fetal fibronectin concentrations in the cervico-vaginal fluids were measured by enzyme-linked immunosorbent assay. The abundance of PGHS mRNA was compared between groups of patients with the same mean gestational age but different cervico-vaginal fetal fibronectin levels. Linear regression analysis was used to determine the association between PGHS levels and fetal fibronectin. RESULTS: Two groups of women were identified who had significantly different fetal fibronectin values but the same gestational ages. The group with the higher fetal fibronectin concentrations had significantly higher PGHS- 1 and PGHS-2 mRNA levels in the chorion laeve and higher PGHS-2 mRNA levels in the amnion, than the group with lower fetal fibronectin concentrations. PGHS- 1 and PGHS-2 mRNA levels in the chorion laeve and PGHS-2 mRNA in the amnion showed an overall significant association with fetal fibronectin levels. CONCLUSIONS: High concentrations of fetal fibronectin in cervico-vaginal secretions before the onset of spontaneous labour at term are associated with high levels of PGHS-2 mRNA in the chorion laeve and the amnion and of PGHS- 1 mRNA in the chorion laeve. Increased expression of PGHS in these tissues may therefore be involved in the events leading to term birth.

Amnion↗