Scaling of far-field wake angle of nonaxisymmetric pressure disturbance

It has been recently emphasized that the angle of maximum wave amplitude α in the wake of a disturbance of finite size can be significantly narrower than the maximum value α_{K}=sin^{-1}(1/3)≃19.47^{∘} predicted by the classical analysis of Kelvin. For axisymmetric disturbance, a simple argument based on the Cauchy-Poisson initial-value problem suggests that the wake angle decreases following a Mach-like law at large velocity, α≃Fr_{L}^{-1}, where Fr_{L}=U/sqrt[gL] is the Froude number based on the disturbance velocity U, its size L, and gravity g. In this paper we extend this analysis to the case of nonaxisymmetric disturbances, relevant to real ships. We find that, for intermediate Froude numbers, the wake angle follows an intermediate scaling law α≃Fr_{L}^{-2}, in agreement with the recent prediction of Noblesse et al. [Eur. J. Mech. B/Fluids 46, 164 (2014)]. We show that beyond a critical Froude number, which scales as A^{1/2} (where A is the length-to-width aspect ratio of the disturbance), the asymptotic scaling α≃Fr_{B}^{-1} holds, where now Fr_{B}=A^{1/2}Fr_{L} is the Froude number based on the disturbance width. We propose a simple model for this transition, and provide a regime diagram of the scaling of the wake angle as a function of parameters (A,Fr_{L}).

Dynamics of grain ejection by sphere impact on a granular bed

The dynamics of grain ejection consecutive to a sphere impacting a granular material is investigated experimentally and the variations of the characteristics of grain ejection with the control parameters are quantitatively studied. The time evolution of the corona formed by the ejected grains is reported, mainly in terms of its diameter and height, and favorably compared with a simple ballistic model. A key characteristic of the granular corona is that the angle formed by its edge with the horizontal granular surface remains constant during the ejection process, which again can be reproduced by the ballistic model. The number and the kinetic energy of the ejected grains are evaluated and allow for the calculation of an effective restitution coefficient characterizing the complex collision process between the impacting sphere and the fine granular target. The effective restitution coefficient is found to be constant when varying the control parameters.

Subcritical Kelvin-Helmholtz instability in a Hele-Shaw cell

We investigate experimentally the subcritical behavior of the Kelvin-Helmholtz instability for a gas-liquid shearing flow in a Hele-Shaw cell. The subcritical curve separating the solutions of a stable plane interface and a fully saturated nonlinear wave train is determined. Experimental results are fitted by a fifth order complex Ginzburg-Landau equation whose linear coefficients are compared to theoretical ones.

Biodegradable biocomposite non-woven matrices based on PDLLA- and elastin-solubilized proteins/elastin

Poly(D,L-lactide) (PDLLA) was synthesized by ring-opening polymerization of D,L-lactide. Non-woven PDLLA matrices were prepared by an extrusion/winding process. The process conditions were optimized and the surfaces of these matrices were modified by glow-discharge treatment and/or glutaraldehyde incorporation for immobilization of elastin-derived proteins (ESP) to the matrix to increase the biocompatibility and also to improve the bioactivity of the matrix. Glow-discharge conditions were optimized. Ethylene diamine (EDA) and Ar were used as the active monomers in the plasma phase. When EDA was used, the glow-discharge treated PDLLA matrices were first allowed to be reacted with glutaraldehyde, although, when Ar used, the treated matrices were used directly for ESP immobilization. The higher degree of immobilization was obtained for EDA and glutaraldehyde. The ESP-incorporated PDLLA matrices were further treated with elastin by cross-reaction of the ESP molecules on the matrix surfaces with elastin. Scanning electron microscopy (SEM) studies showed that ESP were homogeneously deposited the surface of the matrix.

Gap size effects for the Kelvin-Helmholtz instability in a Hele-Shaw cell

We report experimental results for the Kelvin-Helmholtz instability between two immiscible fluids in parallel flow in a Hele-Shaw cell. We focus our interest on the influence of the gap size between the walls on the instability characteristics. Experimental results show that the instability threshold, the critical wavelength, the phase velocity, and the spatial growth rate depend on this gap size. These results are compared to both the previous two-dimensional analysis of Gondret and Rabaud [Phys. Fluids 9, 3267 (1997)] and the three-dimensional analysis recently derived by Plouraboué and Hinch [Phys. Fluids (to be published)], showing that the agreement is still not complete especially when gap size increases.

Elastin-derived protein coating onto poly(ethylene terephthalate). Technical, microstructural and biological studies

Recently, it has been shown in our laboratory that certain proteins solubilized from elastin (ESP) formed a tight association with certain polymers such as elastin or polyethylene glycol terephthalate (PET) ... . The present paper deals with the description of the optimal chemical conditions of this unexpected association, its microstructure and its biological properties. A microstructural study of the composite ESP-PET material was performed using scanning and transmission electron microscopy. The thickness of the yield composite was evaluated (0.4-2 microm) but its imperviousness was unsatisfactory using ESP alone. So, we tentatively coated PET with the elastin-ESP complex. The microscopic views confirmed that the polymer was better filled by the organic matrix, the thickness of the layer being markedly improved (3 microm). Simultaneously, we attempted to verify whether the yielded composite retains the biological properties previously demonstrated with the 'Biopatches' and probably due to ESP. Thus, the culture of endothelial cells on an ESP-coating (with elastin or not) showed that a 100 microg/cm2 ESP concentration was able to promote endothelial cell growth in perfect conditions, maintaining their phenotypic character. While several physico-chemical determinations are in progress in our laboratory to identify and characterize the protein involved, a prototype of small-calibre vascular prosthesis was elaborated with elastin-ESP-PET composite and will be placed in a dog at the abdominal femoral junction to evaluate the in vivo performance of such an attractive material in artery restoration.

Unexpected original property of elastin derived proteins: spontaneous tight coupling with natural and synthetic polymers

Elastin fibres can be decomposed into their constituting proteins using several processes; in particular by saponification of some bonds with KOH in aqueous tertiobutyl alcohol, elastin solubilized proteins - ESP- of 10 to 200 KDa were produced with a good yield (70-80%). It is demonstrated that some of these proteins were capable of tightly re-associating with the native elastin fibres and remained bound on the fibres, in spite of several drastic washes using 1 M Guanidinium, HCl at 37 degrees C for 1 h. At pH 4-5, approximately 30-40 microg ESP were retained per mg elastin. The same association is also shown to occur, under similar conditions, with Poly-ethylene-terephthalate, Poly-hexamethylene diamine-adipic acid but not with polyurethanes. The optimal conditions of the coupling were described as depending on ESP concentration, time, pH, ionic strength and Ca++. It was also shown that opposite pH conditions, i.e. pH 14, 0.5 M NaOH, could allow the retained proteins to desorb from polyesters. Hence, it will be possible to determine the sort of proteins which could be involved. This property of ESP allows us (1) to better understand the exceptional capacity of tissue repair certainly due to adhesive properties of the artificial connective matrices containing elastin or ESP, developed in our laboratory, (2) to provide a new approach for elucidating elastin microstructure and function, (3) especially to provide a new mode for coating certain fibres, yielding materials with bioactive and biofunctional qualities.

Rejection of islets differing by a single antigen is dependent on donor MHC

To study the effect of expression of a single foreign antigen on the outcome of otherwise compatible mouse islet grafts, we have used transgenic mice expressing the human complement receptor 2 (CR2, CD21, C3d/EBV receptor) on their pancreatic beta-cells (RIP-CR2 mice). Donors were RIP-CR2 mice, typed at the major histocompatibility complex (MHC) as H-2(k), H-2(b), or H-2(bxk), and recipients were streptozotocin-treated nontransgenic B6 x CBA F1 mice (H-2(bxk)). H-2(b) or H-2(bxk) CR2-expressing islets were not rejected (mean survival time [MST] >100 days) but induced a peri-insulitis and an antibody response to CR2. In contrast, H-2(k) CR2-expressing islets were rejected in 80% of the cases with a MST of 65 +/- 23 days and were massively infiltrated by a destructive insulitis. In both cases, the infiltrate was mainly made of CD4+ cells, with few CD8+ cells. The isotype of IgG antibody response to CR2 was studied: recipients of H-2(k) grafts had a predominantly IgG1 response, while recipients of H-2(b) grafts had a balanced IgG2a and IgG1 response. To further evaluate the mechanism of differential rejection of the two types of grafts, recipients were immunized with CR2-expressing rat insulinoma cells before transplantation. Preimmunization with CR2 did not affect the outcome of H-2(b) grafts but greatly accelerated the rejection of H-2(k) grafts. These experiments indicate that expression of a single foreign antigen on beta-cells triggers an immune response leading to rejection or to peri-insulitis, depending on the MHC of donor islets.

New preparation and microstructure of the EndoPatch elastin-collagen containing glycosaminoglycans

Several improvements of the basic reaction between elastin-solubilized peptides and type I + III collagens are presented. They concern the prior incubation of the proteins in an adequate medium as well as the addition of heparan sulphate or hyaluronic acid (HA) and the consequent effects on the physical properties of yielded matrices. The addition of HA in small amounts enabled us to make membranes with good performances.

Evaluation of bioabsorbable elastin-fibrin matrix as a barrier in surgical periodontal treatment

The purpose of this investigation was to test clinically the efficiency of a recently described bioabsorbable matrix as a guided tissue regeneration membrane. This matrix was prepared from an original reaction between elastin and fibrin monomers and is now extensively used in several domains of surgery. The study group was composed of 26 patients, with a total of 35 lesions (22 intrabony defects, 8 Class II furcations and 5 Class III furcations) presenting moderate to advanced adult periodontitis. After initial therapy, measurements were made with a calibrated periodontal probe. Probing depth (PD) and gingival margin location (GM) measurements were taken twice: immediately before surgery and after 6 months before re-entry. Clinical attachment level (CAL), vertical osseous level (VOL) and alveolar crest location (AC) measurements were taken during surgery and after 6 months with re-entry procedures for all the patients. Color change of the gingival margin was only observed in 4 defects and device exposure occurred in the proportion of 2 out of the 35 defects. No foreign body reaction was observed in any case. At the intrabony defects mean PD reduction was 5 mm (P < 0.001), and mean gain of CAL was 4 mm (P < 0.001). Mean VOL was 4.3 mm (P < 0.001), mean gingival recession was 0.9 mm (P < 0.05) and mean AC was 0.2 mm (NS). At the Class II furcation defects the mean PD reduction was 4.5 mm (P < 0.001), mean gain CAL vertical was 3.2 mm and CAL horizontal was 4.5 mm (P < 0.001). Gingival recession averaged 1 mm (NS). A complete closure was observed in 2 out of the 8 defects. At the Class III furcation defects the mean PD reduction was 3.6 mm (P < 0.05) and mean CAL-V gain was 1.5 mm (P < 0.02). However the 5 sites showed no horizontal attachment gain and none were unchanged. A very low gingival recession, gingival reaction, crestal bone loss, and device exposure occurred during this study. This preliminary study suggests that the use of a biosynthetic barrier may have beneficial effects in the treatment of intrabony defects and Class II furcation defects. Randomized controlled trials are necessary to evaluate the efficacy and safety of this bioabsorbable membrane in periodontal therapy.

Colonization of a calcium phosphate/elastin-solubilized peptide-collagen composite material by human osteoblasts

The evaluation of the suitability of a new biomaterial as a possible substitute for bone tissue is described here. This biomaterial is based on calcium phosphate particles linked to an artificial connective matrix, the elastin-solubilized peptides (ESP) associated with type I and III collagens. This work demonstrates the feasibility of shaping this composite material into discs, describes its microstructural characteristics, and evaluates its capacity as a substrate for the proliferation of human osteoblasts without loss of their phenotypic expression.

Use of a biodegradable elastin-fibrin material, Neuroplast, as a dural substitute

Since the new Neuroplast biomaterial is now commonly used in several domains of restorative and curative surgery, its preliminary evaluation as a dura mater substitute in the rabbit was performed and is described herein. Whereas the importance of prosthesis thickness was implicated and solved (0.2 rather than 1.0 mm), both macroscopic examination and histological studies revealed for the neotissue an effective patency, a good continuity and especially no or almost no adherence at all. As Neuroplast is now available for use everywhere in humans, this material is being developed in several fields of neurosurgery.

New bioactivation mode for vascular prostheses made of Dacron polyester

The performance of vascular prostheses, especially those of small calibre, still presents several problems. The use of polyesters such as the well-known poly(ethylene terephthalate) (Dacron) and, more recently, poly(tetrafluoroethylene) and polyurethanes provides a marked improvement. We have developed a process to increase the efficiency of such prostheses, using the ability of the Dacron polyester to be covalently modified by proteins under mild chemical conditions. The biomaterial is obtained from the particular interaction of elastin-solubilized peptides with type I + III collagens under very precise conditions. We have obtained an irreversible covalent bonding on Dacron. These biological conditions and the addition of connective proteins and glycosaminoglycans conferred on the resulting material a composition and a three-dimensional structure equivalent to the subendothelium, providing bioactive properties suitable for the development of a vascular prosthesis.

New artificial connective matrix made of fibrin monomers, elastin peptides and type I + III collagens: structural study, biocompatibility and use as tympanic membranes in rabbit

Experiments leading to the conception and development of a new artificial connective matrix based on collagen-elastin-fibrin associations are presented. Preliminary evaluation of this biomaterial as an artificial tympanic membrane is described. Morphological evaluation was performed by histopathological and scanning electron microscopic studies. Biocompatibility was documented by subcutaneous implantation and experimental grafting in rabbits was performed with histopathological studies of the tympanic grafted membranes. The positive results obtained in this experimental study enable future studies in humans to be prepared.

[Preliminary results of the evaluation of the Endopatch E-F in digestive surgery]

Endopatch E-F is a new product elaborated with natural human and animal proteins. Its synthesis originates in a covalent link between elastin and fibrin monomers. Numerous experimental studies carried out in animal have previously shown its ability to reinforce healing process of digestive wall. The results reported herein have been obtained in very selected patients in whom a digestive anastomosis had to be done in spite of unfavorable circumstances, such as intra-abdominal infection, radiated bowel or ascitis. From October 1990 to October 1992, 21 digestive anastomosis have been performed in 18 patients. All were reinforced by Endopatch E-F. Two deaths have been observed (mortality: 11.1%), which do not look like a consequence of the use of the product (One myocardial infarction and one cirrhotic failure). There were 2 post-operative fistulas (9.5% of the whole anastomosis). No patients had any reaction of intolerance. These preliminary results confirm experimental data, and suggest that Endopatch EF can be used in order to reinforce digestive sutures when performed under unfavorable circumstances.

A new biodegradable elastin-fibrin material; its use in urological, digestive and cardiovascular surgery

A new original artificial connective matrix mainly made of elastin and fibrin-like product is used to reinforce damaged tissues and to close and restore a loss of substance in several domains of surgery: all sites in the digestive system and urinary tract; besides, it can substitute for the pericardium in iterative heart operations. In all cases, the original tissue is restored ad integrum while the biodegradable material disappears completely, without any complications.

[Substitution for an experimental duodenal substance loss in the dog with an original bioreactive material]

The aim of this study was to evaluate the suitability of the Elastin Fibrin material as a patch to close a full thickness 1.5 cm diamater duodenal wall defect in the dog. This material originates from a reaction between elastin and fibrin monomers and is available in sheet form of differing thickness. Three Beagles underwent surgical creation of a duodenal defect ant the patch closure with elastin fibrin. Coelioscopic check of the patch was performed at day 8, 15, 39, 60, 90, 120. There was no morbidity or mortality. Macroscopic and histologic examination showed complete disappearance of the patch material and restitution of the duodenal wall at 6 months. These results suggest that in selected cases, evaluation in human may be justified.

Oxidized alpha 1-proteinase inhibitor: a fast-acting inhibitor of human pancreatic elastase

Unlike human neutrophil elastase or porcine and rat pancreatic elastases, human pancreatic elastase is rapidly inhibited by oxidized alpha 1-proteinase inhibitor. The second-order association-rate constant for the reaction of the oxidized inhibitor with this enzyme (kass = 10(5) M-1 s-1) is only 8-fold lower than that measured with native alpha 1-proteinase inhibitor. Elastase releases faster from its complex with the oxidized inhibitor (t1/2 approximately 0.7 days) than from its complex with the native inhibitor (t1/2 approximately 5 days). Oxidized alpha 1-proteinase inhibitor is as efficient as the native inhibitor in inhibiting the elastolytic activity of elastase. Oxidized alpha 1-proteinase inhibitor may thus be considered as a physiological inhibitor of human pancreatic elastase which may prevent degradation of blood vessel elastin during acute hemorrhagic pancreatis.

New artificial connective matrix-like structure: thrombogenicity and use as endothelial cell culture support

The recently described artificial connective matrix made of elastin solubilized peptides, type I+III collagens and connective proteins is shown to have structural and biological properties very close to the natural arterial subendothelium: the capacity to promote endothelial cell cultures maintaining their phenotype expression and its non-thrombogenicity. This new bioactive composite material could be used to replace arteries.

New artificial connective matrix-like structure made of elastin solubilized peptides and collagens: elaboration, biochemical and structural properties

Several improvements of the basic reaction between elastin peptides and type III collagen, specially the addition of heparan sulphate proteoglycans, are presented. The consequent elaboration of either cell culture support or membranes are described and illustrated by scanning electron microscopy. The material produced possesses composition, very well organized lamellar structure and some properties quite close to natural membranes such as subendothelial tissue.

In vitro studies of elastin-fibrin biomaterial degradation: preservative effects of protease inhibitors and antibiotics

The degradability of a new elastin-fibrin material was tested in vitro versus human pancreatic elastase (HPE) and plasmin (PL) activities. It is shown that aprotinine Iniprol, a well-known protease inhibitor and Eglin C, a new potent inhibitor of HPE, especially when used in synergy, efficiently protected the material. A small amount of specific antibiotics was incorporated into the material. The two products will allow the material to be used in digestive surgery with improved safety.

In vitro association of type III collagen with elastin and with its solubilized peptides

Elastin fibres or elastin solubilized peptides associated with type III collagen, under physiological conditions, to form a gel-like substance. The gel cohesion could be markedly improved either by desiccation process (gently air-dried rather than lyophilized) or by addition of adhesive connective proteins such as fibronectin, laminin and type IV collagen. They conferred to the material the composition and the structural appearance of typical basement membrane-like structure. Their properties enable us to investigate the biomaterial in several domains.

Kinetics of the inhibition of human pancreatic elastase by recombinant eglin c. Influence of elastin

Recombinant eglin c is a potent reversible inhibitor of human pancreatic elastase. At pH 7.4 and 25 degrees C, kass. = 7.3 x 10(5) M-1.s-1, kdiss. = 2.7 x 10(-4) s-1 and Ki = 3.7 x 10(-10) M. Stopped-flow kinetic indicate that the formation of the stable enzyme-inhibitor complex is not preceded by a fast pre-equilibrium complex or that the latter has a dissociation constant greater than 0.3 microM. The elastase-eglin c complex is much less stable at pH 5.0 and 25 degrees C, where kdiss. = 1.1 x 10(-2) s-1 and Ki = 7.3 x 10(-8) M. At pH 7.4 the activation energy for kass. is 43.9 kJ.mol-1 (10.5 kcal.mol-1). The kass. increases between pH 5.0 and 8.0 and remains essentially constant up to pH 9.0. This pH-dependence could not be described by a simple ionization curve. Both alpha 2-macroglobulin and alpha 1-proteinase inhibitor are able to dissociate the elastase-eglin c complex, as evidenced by measurement of the enzymic activity of alpha 2-macroglobulin-bound elastase or by polyacrylamide-gel electrophoresis of mixtures of alpha 1-proteinase inhibitor and elastase-eglin c complex. The rough estimate of kdiss. obtained with the alpha 2-macroglobulin dissociation experiment (1.6 x 10(-4) s-1) was of the same order of magnitude as the constant measured with the progress curve method. Eglin c strongly inhibits the solubilization of human aorta elastin by human pancreatic elastase. The extent of inhibition is the same whether elastase is added to a suspension of elastin and eglin c or whether elastase is preincubated with elastin for 3 min before addition of eglin c. However, the efficiency of the inhibitor sharply decreases if elastase is reacted with elastin for more prolonged periods.

Biocompatibility of elastin-fibrin material in the rat

Biocompatibility and biodegradability of a new elastin-fibrin material were investigated in several organs and tissues of the rat. It has been demonstrated that the material was quite well tolerated in all cases, except in bone marrow. Its use is considered in several aspects of reparative or constructive surgery.

Repair of experimental arteriotomy in rabbit aorta using a new resorbable elastin-fibrin biomaterial

A new artificial connective matrix which results from two reactions of fibrinogen and fibronectin on elastin was used to obturate a slit made in the abdominal aorta of rabbit. The so-called Elastin-Fibrin biomaterial behaved as a scaffold through which all the different structures were restored to their former condition. At 3 months, the material had disappeared and no thrombus, no inflammation or reject had been detected.

Some factors affecting properties of elastin-fibrin biomaterial

The elasticity, mechanical strength and permeability of a new biomaterial made of elastin and fibrin were investigated. It was shown that gamma-irradiation to sterilize the product, and sulphur derivatives (Merceptyl, thiourea, cystein) working as reticulating agents modified these properties. Depending on whether or not the biomaterial needs to be stiff, strong or elastic both physical processes could intervene separately or together. The good permeability of this material allows it to be used in several surgical fields as a true artificial connective matrix.

Biochemical study of adduct synthesis between fibrin monomers and elastin

Monomers of fibrin generated by thrombin from fibrinogen reacted with elastin to give a new addition product or adduct. Adduct formation resulted from a covalent bond between fibrin monomers and elastin. The kinetic studies of this reaction confirmed that the adduct was formed before fibrin precipitated to produce the clot. The reaction depended on elastin, fibrinogen and thrombin concentrations. When thrombin-induced and reptilase-induced fibrin were compared, it became obvious that fibrin monomers did intervene more commonly as Des AA-fibrin than as Des AA.BB-fibrin. The adduct synthesis was completely inhibited by 150 microM of the peptide Gly-Pro-Arg-Pro which was previously known to stabilize the fibrin monomers and consequently to inhibit the polymerization completely. It is shown that FXIII could intervene directly in the reaction where homological quality of elastin (human versus bovine) and purity of thrombin were other important factors.

A new reconstituted connective tissue matrix: preparation, biochemical, structural and mechanical studies

A fibrinogen derivative generated by thrombin was reacted with elastin to yield a new addition product or adduct between the two proteins. Addition of fibronectin, and then of collagen, did not interfere with the basic elastin-fibrinogen reaction and conferred the qualities of an artificial connective tissue to the product. Biochemical, structural and biomechanical aspects of the new matrix were studied. Aprotinin, heparin, thiomersal, and thiourea did not inhibit the main reaction; indeed, some of these ingredients improved the matrix cohesion. Scanning electron microscopy showed the genesis of a true network whose meshes were more reticulated by the addition of thiourea. Biomechanical studies, i.e., strength and elasticity showed the thiourea matrix to be the strongest. These intrinsic properties suggest the product could have biological and clinical applications.

Collagen studies in congenital cutis laxa

A case of congenital cutis laxa (CCL) of unclear mode of inheritance associated with multiple pulmonary artery branch stenosis was extensively investigated to assess possible correlations between clinical, ultrastructural, and biochemical features. Light microscopy revealed that elastic fibers were absent in the papillary dermis, while hypoplastic elsewhere. Transmission electron microscopy showed a poor elastin matrix content in some elastic fibers, variable diameters of collagen fibrils, and abundant glycogen granules in most dermal cells. Measurement of collagen fibril diameters, using an image analyzer, was carried out in the patient and two age- and site-matched controls. A bimodal distribution was found in the upper reticular dermis of the patient. In vitro analysis of collagen in skin fibroblast cultures of the patient showed increased collagen synthesis with a balanced production of type I and type III procollagens. Our study confirms that CCL represents a disorder both of collagen and elastic connective tissue.

Adduct formation between soluble fibrin monomers and elastin

Monomers of fibrin generated from fibrinogen by thrombin reacted with elastin to give a new addition product or adduct. The adduct formation results from a covalent bond between both proteins, formation of which is dependent on elastin, fibrinogen and Ca2+ concentrations; but, Factor XIIIa did not intervene. Addition of fibronectin, together with fibrinogen, as cold insoluble proteins from human plasma, and of soluble collagen from rat tail tendon did not inhibit the first reaction. This enabled us to elaborate a new artificial connective matrix.

Inhibition of human pancreatic elastase II activity on human aortic elastin by human alpha 2-macroglobulin

Human alpha 2-macroglobulin-human pancreatic elastase II binding were investigated using a homologous substrate, human aortic elastin, in order to test the enzymatic activity. We demonstrated that two moles of alpha 2-M are required to inhibit one mole of HPEII when the enzyme is added to a mixture of elastin and alpha 2-M. In addition, when the elastase-alpha 2-M complex is prepared under some circumstances, it exhibits an elastinolytic activity.

Soluble fibrinogen derivatives generated by thrombin: affinity for elastin

When human citrated plasma is dialysed against a phosphate buffer containing Ca++, citrate anions are removed, thrombin is generated and soluble fibrinogen derivatives (fibrin monomers and/or soluble fibrin polymers) are formed. These derivatives are able to combine with human or bovine elastin to form a very stable addition product or adduct. The formation of the adduct is dependent on time, Ca++ and thrombin concentrations.