Transport properties in a two-temperature plasma: theory and application

An alternate derivation of transport properties in a two-temperature plasma has been performed. Indeed, recent works have shown that the simplified theory of transport properties out of thermal equilibrium introduced by Devoto and then Bonnefoi, very often used in two-temperature modeling, is questionable and particularly does not work when calculating the combined diffusion coefficients of Murphy. Thus, in this paper, transport properties are derived without Bonnefoi's assumptions in a nonreactive two-temperature plasma, assuming chemical equilibrium is achieved. The electron kinetic temperature T(e) is supposed to be different from that of heavy species T(h). Only elastic processes are considered in a collision-dominated plasma. The resolution of Boltzmann's equation, thanks to the Chapman-Enskog method, is used to calculate transport coefficients from sets of linear equations. The solution of these systems allows transport coefficients to be written as linear combinations of collision integrals, which take into account the interaction potential for a collision between two particles. These linear combinations are derived by extending the definition and the calculation of bracket integrals introduced by Chapman et al. to the thermal nonequilibrium case. The obtained results are rigorously the same as those of Hirschfelder et al. at thermal equilibrium. The derivation of diffusion velocity and heat flux shows the contribution of a new gradient, that of the temperature ratio straight theta=T(e)/T(h). An application is presented for a two-temperature argon plasma. First, it is shown that the two-temperature linear combinations of collision integrals are drastically modified with respect to equilibrium. Secondly, the two-temperature simplified theory of transport coefficients of Devoto and Bonnefoi underestimates the electron thermal conductivity with respect to the accurate value at T(e)=20 000 K. Lastly, contrary to the simplified theory of transport coefficients, the diffusion coefficients satisfy the symmetry conditions. An example is given at T(e)=6000 K for different values of straight theta for the diffusion coefficient between electrons and heavy species D(e-Ar) as well as for that between argon atoms and argon ions D(Ar-Ar+).

Maternal-fetal staphylococcal infections: a series report

The objective of this paper is to study the characteristics of maternal-fetal staphyloccocal infection. A retrospective study among 1,582 infants admitted consecutively to our neonatal intensive care unit was carried out from January 1995 through September 1998. The antenatal history, and the clinical and bacteriological findings and outcome of the infants fulfilling maternal-fetal staphyloccocal infection were analysed. Among 122 (7.7%) maternal-fetal infection, 11 cases (8.9%) of congenital staphyloccal infections were diagnosed in 9 premature and 2 full-term babies. Antenatal invasive procedures were noted in 6 occasions (56%). All the 11 infants developed respiratory and hemodynamic failure. Staphylococcus aureus was the most common organism encountered in maternal bacteriologic data (9/11, 82%) as well as on peripheral sites (9/11, 82%) and in blood cultures (7/11, 64%) performed in the infants. There was one case of methicillin-resistant Staphylococcus aureus. The outcome was favorable for 9 infants. Two very preterm neonates died within the first 72 hours of life. Mother-to-infant transmission of Staphylococcus should be suspected whenever invasive procedures are performed during pregnancy and in the presence of severe neonatal distress associated with an inflammatory response. Prompt and adapted antibiotic therapy allows a favourable outcome.

Defect in regulated secretion of P-selectin affects leukocyte recruitment in von Willebrand factor-deficient mice

Stimulation of endothelial cells by various inflammatory mediators leads to release of Weibel--Palade bodies and therefore to exocytosis of both P-selectin (adhesion receptor for leukocytes) and von Willebrand factor (vWf) (platelet ligand). The potential role of vWf in leukocyte recruitment was investigated with the use of vWf-deficient mice. We report a strong reduction of leukocyte rolling in venules of vWf-deficient mice. Similarly, vWf deficiency led to a decrease in neutrophil recruitment in a cytokine-induced meningitis model as well as in early skin wounds. In all instances with an antibody that preferentially recognizes plasma membrane P-selectin, we observed a dramatic reduction in P-selectin expression at the cell surface of vWf-deficient endothelium. With confocal microscopy, we found that the typical rodlike shape of the Weibel--Palade body is missing in vWf -/- endothelial cells and that part of the P-selectin content in the vWf -/- cells colocalized with LAMP-1, a lysosomal marker. However, intracellular P-selectin levels were similar in tumor necrosis factor alpha- and lipopolysaccharide-activated cells of both genotypes. We conclude that the absence of vWf, as found in severe von Willebrand disease, leads to a defect in Weibel--Palade body formation. This defect results in decreased P-selectin translocation to the cell surface and reduced leukocyte recruitment in early phases of inflammation.

Accumulation of triglyceride-rich lipoprotein in subjects with abdominal obesity: the biguanides and the prevention of the risk of obesity (BIGPRO) 1 study

The present study represents a new insight into the Biguanides and the Prevention of the Risk of Obesity (BIGPRO) 1 study population at inclusion. This population, selected basically on the basis of a high waist-to-hip ratio (>/=0.95 for men and >/=0.80 for women), is supposed to represent a group of patients with insulin resistance. The present study was undergone to establish whether apolipoprotein C-III (apoC-III) and apolipoprotein E (apoE) associated with apo B (apoC-III LpB and apoE LpB, respectively), considered to be markers of remnant accumulation, play a role in the hypertriglyceridemia associated with insulin resistance and whether they are related to other biological abnormalities frequently observed in this syndrome. In this population, the concentration of the markers of remnant accumulation increases with triglyceride levels. Therefore, correlation studies were realized to assess the relative effect of insulin and the markers of remnant accumulation on triglyceride plasma level. As a first attempt, a simple correlation analysis revealed that insulin is positively related to the markers of remnant accumulation only in hypertriglyceridemic patients (triglycerides >/=1.7 mmol/L). To assess the independent contribution of these markers, insulin, and other parameters related to the plasma triglyceride concentration, a stepwise multiple regression analysis was run. Results revealed that insulin and the markers of remnant accumulation (specifically, apoE LpB) are independent contributors to the plasma triglyceride concentration. Markers of the endothelial damage, plasminogen activator inhibitor-1, tissue plasminogen activator, and von Willebrand factor, which are often increased in the case of insulin resistance, were tested for their correlation with the markers of remnant accumulation. Plasminogen activator inhibitor-1 is positively correlated with these markers only in hypertriglyceridemic male subjects. It is concluded that increased insulin levels found in insulin resistance syndrome are associated with an increased production of triglyceride-rich lipoproteins enriched in apoC-III and apoE. The accumulation of these remnants and/or their abnormal composition in apoC-III and apoE could be an explanation for the development of hypertriglyceridemia in this syndrome.

The calcium inhibitor SR33805 reduces intimal formation following injury of the porcine carotid artery

We studied the effect of SR33805, a calcium channel blocker, in vitro on the proliferation of vascular smooth muscle cells (SMC) stimulated by foetal calf serum, basic fibroblast growth factor and platelet derived growth factor, and in vivo with regard to SMC migration and proliferation which occurred following injury of the porcine carotid artery. The intimal lesion was induced by a silasten collar surgically positioned around the carotid artery and by a stenosis reducing blood flow by 50% for 30 days. Animals received SR33805 (5 mg/kg/day) 8 days before the induction of the lesion and up to 30 days after. In vitro, SR33805 inhibited in a dose-dependent manner growth factor-induced proliferation of SMC (0.20<IC(50)<0.46 microM). In vivo, SR33805 reduced the intima/media ratio of the cross sectional surface area (decrease of 60%, P<0.05) without affecting neointimal SMC density. The medial SMC density was 40% lower in treated than in control animals (upstream, P<0.05 and downstream to the stenosis, P<0.01). Thus, it appears that SR33805 significantly reduced intimal hyperplasia, which occurred after perivascular manipulation of the artery, an effect consistent with its in vitro proliferation inhibitory activity, suggesting that long-term treatment with SR33805 may reduce or delay SMC proliferation.

Supra-aggregates

Mixtures of oil (isooctane), water, and a double-chained ionic surfactant, Cu(AOT)2 [copper(II) bis(2-ethylhexyl)sulfosuccinate] form equilibrium phases consisting of spontaneous emulsions thermodynamically stable systems. The experimental conditions are such that the head polar group of the surfactant is totally hydrated. The emulsion droplets are comprised of supra aggregates, lamellar spherulites in which interior and exterior are bicontinuous microemulsions. The microstructures and component ratios can be predicted from elementary considerations that require only the notion of local and global packing constraints. The phenomenon of supra aggregation, microphases within any topologically closed container, in equilibrium with an external phase, appears quite general. The results throw some light on the meaning of 'phase' in mesostructured fluids.

Interleukin 11 significantly increases plasma von Willebrand factor and factor VIII in wild type and von Willebrand disease mouse models

Interleukin (IL)-11 is a cytokine with thrombopoietic activity that has been shown to increase plasma von Willebrand factor (vWf) in preliminary clinical studies. This led to further evaluation of the effect of recombinant human (rh)IL-11 on vWf and factor VIII (FVIII) secretion. In vitro, rhIL-11 did not increase vWf production by cultured endothelial cells, which suggests an indirect mechanism. Also, in vivo, plasma vWf was not elevated in mice shortly after a single intravenous (IV) bolus injection of 250 or 1000 microg/kg rhIL-11. The effect of continuous exposure to rhIL-11 was accessed by treating wild type mice for 7 consecutive days with subcutaneous 250 microg/kg/d rhIL-11. Platelet counts increased by 25% and 40% after 4 and 7 days, respectively. Plasma vWf and FVIII levels increased 2-fold after 4 and 7 days. Surprisingly, no effect of rhIL-11 on vWf or FVIII messenger RNA was observed, which suggests that the regulation by rhIL-11 occurs after transcription. No increase in soluble P-selectin was observed after rhIL-11 treatment, indicating that platelet activation is not the source of elevated vWf. Similarly to wild type mice, vWf heterozygous mice responded to rhIL-11 treatment by a significant increase in platelet counts and vWf and FVIII levels. Importantly, in vWf-deficient mice, rhIL-11 also induced a significant increase in FVIII independent of vWf and was able to reduce skin bleeding time. These results suggest that a clinical evaluation of the effects of rhIL-11-induced vWf/FVIII elevation in maintaining hemostasis in mild hemophilia A or von Willebrand disease would be worthwhile.

Pro-coagulant state resulting from high levels of soluble P-selectin in blood

The plasma concentration of soluble adhesion receptors is increased under pathological circumstances, but their function remains enigmatic. Soluble P-selectin (sP-sel) is shed from activated platelets and endothelial cells. Mice genetically engineered to express P-selectin without the cytoplasmic tail (DeltaCT) constitutively show a 3- to 4-fold increase of sP-sel in plasma. We observed that the DeltaCT mice formed fibrin very readily. In an ex vivo perfusion chamber, there was more fibrin deposited at the site of platelet thrombus formation than in wild type (WT), whereas no fibrin deposits were detected using P-selectin-deficient blood during the same interval. Similarly, in vivo, the hemorrhage produced by local Shwartzman reaction was smaller in the DeltaCT mice than in WT. In contrast, we previously showed hemorrhage to be more prominent in P-selectin knock-out mice. Infusion of mouse P-sel-Ig chimera produced the same protective effect in WT mice as seen in the DeltaCT mice, indicating that the effect was due to increased levels of sP-sel. Mice infused with P-sel-Ig showed significantly more fibrin deposited on the luminal face of the injured vessels than control mice. Plasma from DeltaCT mice or mice infused with P-sel-Ig contained higher concentration of pro-coagulant microparticles and clotted one minute faster than WT. This pro-coagulant phenotype of DeltaCT mice could be reversed by a 4-day treatment with PSGL-Ig, a P-selectin inhibitor. We propose that sP-sel should no longer be considered only as a marker of inflammation or platelet activation, but also as a direct inducer of pro-coagulant activity associated with vascular and thrombotic diseases.

Platelets adhere to and translocate on von Willebrand factor presented by endothelium in stimulated veins

With the use of intravital microscopy, a new type of platelet-endothelial interaction in mouse mesenteric venules at low shear (80-100 seconds(-1)) is described. Stimulation of these vessels with calcium ionophore A23187, a known secretagogue of Weibel-Palade bodies, induced immediate platelet adhesion (within 15 seconds) and translocation without the formation of aggregates. This stop-and-go process reached a maximum in approximately 1 minute, when approximately 25 000 platelets adhered/mm(2).s, and then adhesion progressively decreased. This adhesion process was dependent on von Willebrand factor (vWF) and independent of P-selectin. Immunohistologic analysis showed that the venules were not denuded with A23187 treatment, suggesting that platelets adhered to vWF secreted on the luminal face of the endothelial cells. Histamine treatment induced a similar adhesion phenomenon. Platelet adhesion was not abolished in beta3-deficient mice or when the platelets were treated with inhibitory antibodies to PECAM-1 or PSGL-1, indicating that these molecules are not required for platelet-endothelium interaction at low shear. The adhesion was mediated by platelet glycoprotein Ibalpha (GPIbalpha) because the adhesion of murine platelets expressing exclusively the human GPIbalpha could be prevented by a pretreatment with mocarhagin, a snake venom protease that cleaves human GPIbalpha. The results indicate that vWF released from Weibel-Palade bodies can dramatically increase the concentration of platelets along the vessel wall through an interaction with GPIbalpha. It is proposed that this process may rapidly recruit platelets to sites of injury or inflammation in veins.

Modulation of HLA-G antigens expression in myelomonocytic cells

As trophoblast cells and macrophages share cellular characteristics, we investigated the expression of HLA-G antigens during the myelomonocytic differentiation. Analyses with the 87G and 16G1 monoclonal antibodies demonstrated that HLA-G was not expressed in peripheral blood monocytes, in in vitro differentiated dendritic cells and macrophages, and in resident mononuclear phagocytes infiltrating healthy tissues. Conversely, activated macrophages and dendritic cells localized in tumoral biopsies of some lung carcinomas expressed HLA-G antigens. Induction of HLA-G expression at the cell surface of the monohistiocytic cell line U 937 with different cytokines strongly suggests that cytokines secreted during inflammation may be involved in this specific upregulation. Bronchoalveolar macrophages collected from patients suffering from acute HCMV pneumonitis also expressed HLA-G molecules. In vitro, we thus demonstrated that HLA-G antigens are produced during viral reactivation in the macrophages generated after allogeneic stimulation of HCMV latently infected monocytes. Our data suggest that inflammatory processes in lung tissues, like tumoral transformation and HCMV acute infection, are likely to induce HLA-G molecules in infiltrating macrophages and dendritic cells. The expression of molecules capable of downregulating both the innate and adoptive immunity could be a mechanism that helps tumoral and HCMV infected cells to escape immune response.

Methylprednisolone, an alternative to dexamethasone in very premature infants at risk of chronic lung disease

OBJECTIVE

To evaluate the benefits and the medium-term side effects of methylprednisolone in very preterm infants at risk of chronic lung disease.

STUDY DESIGN

Forty-five consecutive preterm infants (< 30 weeks' gestation) at risk of chronic lung disease were treated at a mean postnatal age of 16 days with a tapering course of methylprednisolone. The outcome of treatment was assessed by comparison with 45 consecutive historical cases of infants treated with dexamethasone; the infants did not differ in baseline characteristics.

RESULTS

There were no differences between groups in the rate of survivors without chronic lung disease. Infants treated with methylprednisolone had a higher rate of body weight gain during the treatment period (median 120 g, range 0 to 190, vs. 70 g, range -110 to 210, P = 0.01) and between birth and the age of 40 weeks (median 1660 g, range 1170-2520, vs. 1580 g, range 1,040 to 2,120, P = 0.02). The incidence of both glucose intolerance requiring insulin (0 % vs. 18 %, P = 0.006) and cystic periventricular leukomalacia (2 % vs. 18%, P = 0.03) was lower among methylprednisolone-treated infants.

CONCLUSION

Our observations confirm methylprednisolone to be as effective as dexamethasone and to have fewer side effects. A randomized control trial is needed to further study the efficacy and safety of methylprednisolone in very premature infants at risk of chronic lung disease.

Association of signal-regulatory proteins beta with KARAP/DAP-12

The signal-regulatory proteins (SIRP) are Ig-like cell surface receptors detected in hematopoietic and non-hematopoietic cells. SIRP are classified as SIRPalpha molecules, containing a 110- to 113-amino acid long, or SIRPbeta molecules, with a 5-amino acid long intracytoplasmic domain. SIRPalpha molecules belong to inhibitory immunoreceptor tyrosine-based inhibition motif (ITIM)-bearing molecules. The majority of ITIM-bearing receptors are paired with activating isoforms, which share highly related extracytoplasmic domains but harbor a shorter cytoplasmic domain devoid of ITIM and contain a charged amino acid residue in their transmembrane domain. Activating receptors are associated with immunoreceptor tyrosine-based activation motif (ITAM)-bearing proteins, such as KARAP/DAP-12 and FcRgamma. In this report, we show that human SIRPbeta1 is included in an oligomeric complex with KARAP/DAP-12 in hematopoietic and non-hematopoietic transfectant cells as well as in human monocytes. The physical association between SIRPbeta1 and KARAP/DAP-12 results in the functional coupling of SIRPbeta1 engagement to the recruitment of the protein tyrosine kinase Syk and to serotonin release in RBL cell transfectants. Therefore our results show that SIRPbeta1 acts as an activating isoform of SIRPalpha molecules, confirming the co-existence of inhibitory ITIM-bearing molecules, recruiting SHP-1 and SHP-2 protein tyrosine phosphatases, and activating counterparts, whose engagement couples to protein tyrosine kinases via ITAM-bearing molecules.

Modulation of HLA-G antigens expression by human cytomegalovirus: specific induction in activated macrophages harboring human cytomegalovirus infection

After infection, human CMV (HCMV) establishes a latent and persistent infection in immature myeloid progenitors and peripheral blood monocytes. Completion of the HCMV life cycle is possible upon maturation of monocytes to tissue macrophages and under permissive circumstances, e.g., immunosuppression. We investigated the hypothesis that HLA-G molecules could be induced during HCMV reactivation in activated macrophages to favor virus dissemination. In this study, we provide evidence that HLA-G Ags are produced during viral reactivation in macrophages generated after allogeneic stimulation of HCMV latently infected monocytes. While HLA-G surface expression is up-regulated, classical MHC-I molecules are partially down-regulated by HCMV. In vivo, bronchoalveolar macrophages collected from patients suffering from acute HCMV pneumonitis also express HLA-G molecules. The direct correlation between HLA-G Ag induction and HCMV infection was confirmed in U-373 MG astrocytoma cells. Soluble HLA-G expression is stimulated upon HCMV infection, and this modulation depends on the cooperative action of the two immediate-early-1 pp72 and immediate-early-2 pp86 products. Because HLA-G transcription is active in macrophages and U-373 MG astrocytoma cells, it is likely that the modulation of HLA-G protein expression during HCMV replication occurs at a post-transcriptional level. Our data suggest that induction of HLA-G molecules could be an additional mechanism that helps HCMV to subvert host defenses.

Outcome of premature infants delivered after prolonged premature rupture of membranes before 25 weeks of gestation

OBJECTIVE

To identify factors influencing the outcome of premature infants delivered after prolonged premature rupture of membranes before 25 weeks' gestation.

DESIGN AND POPULATION

All premature infants with gestational age <34 weeks, either inborn or outborn, with history of rupture of membranes before 25 weeks' gestation, admitted to our NICU between January 1992 and July 1997, were eligible for this retrospective study. Collected information included birth weight, gestational age at rupture of membranes and at delivery, duration between rupture of membranes and delivery (latency period), severity of oligohydramnios, pre- and post-natal managements, and follow-up of survivors.

RESULTS

A total of 28 neonates fulfilled the inclusion criteria. Despite new strategies of ventilation and optimal management, the overall mortality rate was 43% (12/28). Nonsurvivors were significantly less mature at rupture of membranes, and had severe oligohydramnios (anamnios). We also noted less antenatal corticosteroids and antibiotic therapy in this group. Nine of eleven infants (82%) following rupture of membranes before 22 weeks' gestation died shortly after birth. The two remaining infants developed severe bronchopulmonary dysplasia. Nine deaths occurred in thirteen cases (69%) of anamnios. The major death causes were refractory respiratory failure and neurologic complications. Half of all survivors (8/16) developed bronchopulmonary dysplasia.

CONCLUSION

The outcome of premature infants following prolonged premature rupture of membranes before 25 weeks' gestation is influenced by gestational age at rupture, severity of oligohydramnios, and antenatal antibiotics and corticosteroids. Neonates with rupture of membranes before 22 weeks have a very low chance of survival at the present time.

Modification of P-selectin glycoprotein ligand-1 with a natural killer cell-restricted sulfated lactosamine creates an alternate ligand for L-selectin

Natural killer (NK) cells are components of the innate immune system that can recognize and kill virally infected cells, tumor cells, and allogeneic cells without prior sensitization. NK cells also elaborate cytokines (e.g., interferon-gamma and tumor necrosis factor-alpha) and chemokines (e.g., macrophage inflammatory protein-1alpha) that promote the acquisition of antigen-specific immunity. NK cell differentiation is accompanied by the cell surface expression of a mucin-like glycoprotein bearing an NK cell-restricted keratan sulfate-related lactosamine carbohydrate, the PEN5 epitope. Here, we report that PEN5 is a post-translational modification of P-selectin glycoprotein ligand-1 (PSGL-1). The PEN5 epitope creates on PSGL-1 a unique binding site for L-selectin, which is independent of PSGL-1 tyrosine sulfation. On the surface of NK cells, the expression of PEN5 is coordinated with the disappearance of L-selectin and the up-regulation of Killer cell Ig-like Receptors (KIR). These results indicate that NK cell differentiation is accompanied by the acquisition of a unique carbohydrate, PEN5, that can serve as part of a combination code to deliver KIR(+) NK cells to specific tissues.

CD4+ T cell surface CCR5 density as a determining factor of virus load in persons infected with human immunodeficiency virus type 1

The intensity of expression of the chemokine receptor CCR5 is involved in in vitro cell infectability by human immunodeficiency virus (HIV)-1 R5 isolates. Because CCR5 expression varies among individuals, the hypothesis that this expression could determine virus load in HIV-1-infected persons was tested. The mean number of CCR5 molecules per cell was measured on peripheral blood CD4+ T lymphocytes (CCR5 density) from HIV-1-infected, asymptomatic, nontreated adults. There was a strong correlation between HIV RNA plasma level and CCR5 density (P=.009) that was independent of cell activation and was not due to an HIV-induced CCR5 up-regulation. These data are compatible with the hypothesis that CCR5 density is a key factor governing cell infectability and in vivo virus production and explain the protective effect of the Delta32CCR5 deletion, which results in low CCR5 expression. CCR5 density might be of critical predictive value in HIV infection.

Treatment with metformin of non-diabetic men with hypertension, hypertriglyceridaemia and central fat distribution: the BIGPRO 1.2 trial

BACKGROUND

In the BIGPRO 1 trial, one year of treatment with metformin in non-diabetic obese subjects with a central fat distribution had no significant effect on fasting plasma triglyceride concentration or on blood pressure despite a decrease in weight, fasting plasma insulin and glucose concentrations. To re-evaluate the effect of metformin on fasting triglyceride concentration and on blood pressure, the BIGPRO 1.2 trial included non-diabetic men (n=168) with a fasting plasma triglyceride concentration > or =1.7 and < or =6.5 mmol/l, high blood pressure (systolic > or =140 and < or =180 and/or diastolic > or =90 and < or =105 mmHg, or treatment for hypertension) and a waist-to-hip ratio > or =0.95.

METHODS

A randomised double-blind trial comparing metformin treatment (850 mg bid) with placebo.

RESULTS

Metformin had no significant effect either on blood pressure or plasma triglyceride concentration. In comparison with the placebo group, fasting plasma insulin (p<0.04), total cholesterol (p<0.05) and Apo B (p<0.008) concentrations decreased more in the metformin group in the BIGPRO 1. 2 trial, confirming most of the previous results of the BIGPRO 1 trial. Tissue plasminogen activator antigen concentration decreased significantly (p<0.01) only in the metformin group, but this was not significantly different from the placebo group (p<0.12); further, there were no significant differences in the change in plasminogen activator inhibitor 1.

CONCLUSIONS

The consistency of the two BIGPRO trials supports the conclusion that metformin affects several cardiovascular risk factors favourably in non-diabetic subjects with a central fat distribution.

Listeria monocytogenes possesses adhesins for fibronectin

Listeria monocytogenes is a gram-positive, nonsporulating, food-borne pathogen of humans and animals that is able to invade many eukaryotic cells. Several listerial surface components have been reported to interact with eukaryotic cell receptors, but the complete mechanism by which the bacteria interact with all of these cell types remains largely unknown. In this work, we found that L. monocytogenes binds to human fibronectin, a 450,000-Da dimeric glycoprotein found in body fluids, on the surface of cells and in an insoluble component of the extracellular matrix. The binding of fibronectin to L. monocytogenes was found to be saturable and dependent on proteinaceous receptors. Five fibronectin-binding proteins of 55.3, 48.6, 46.7, 42.4, and 26.8 kDa were identified. The 55.3-kDa protein was proved to be present at the bacterial cell surface. The binding of L. monocytogenes to fibronectin adds to the number of molecules to which the bacterium is able to adhere and emphasizes the complexity of host-pathogen interactions.