Fibrinogen ß chain and FXIII polymorphisms affect fibrin clot properties in acute pulmonary embolism.

BACKGROUND: Prothrombotic fibrin clot properties, including increased clot density, are in part genetically determined. We investigated whether fibrinogen alpha-chain gene (FGA) c.991A>G (rs6050), fibrinogen beta chain gene (FGB) -455G>A (rs1800790) and factor XIII gene (F13) c.103G>T (rs5985) polymorphisms affect plasma fibrin clot properties in patients with acute pulmonary embolism (PE). METHODS: As many as 126 normotensive patients with PE, free of cancer, were genotyped by TaqMan assay. Fibrin clot permeability (Ks ), clot lysis time (CLT) and endogenous thrombin potential (ETP) were assessed on admission. RESULTS: The minor allele frequencies were as follows: FGA rs6050 (n = 62, 0.31), FGB rs1800790 (n = 40, 0.17) and F13 rs5985 (n = 49, 0.23). There were no differences related to any of the polymorphisms with regard to demographic, clinical and laboratory data, except for fibrinogen concentration, which was higher in carriers of F13 rs5985 polymorphism (p = .024), and PE combined with deep-vein thrombosis, which was less prevalent in FGB rs1800790 polymorphism carriers (p = .004). Carriers of FGB rs1800790 A allele and F13 rs5985 T allele had lower Ks , prolonged CLT and higher ETP compared with major homozygotes (all p < .05). After adjustment for fibrinogen, all differences remained significant (all p < .01). There were no associations between the FGA rs6050 polymorphism and Ks , CLT or ETP. CONCLUSION: Our study showed that FGB rs1800790 and F13 rs5985 polymorphisms contribute to the prothrombotic fibrin clot phenotype and these effects are strong enough to be observed in the acute phase of PE.

Formation of fibrin at sights of conceptus adhesion in the ewe.

In ruminants, various molecules are involved in regulating conceptus attachment and adhesion; however, molecules that maintain the conceptus adhesion have not been well characterized. We hypothesized that conceptus must produce a molecule(s), yet uncharacterized or overlooked, which maintain conceptus adhesion to the uterine epithelium. In this study, we aimed to identify new candidate(s) in conceptus secretory proteins responsible for maintaining conceptus adhesion in sheep. We performed RNA-sequence analysis with ovine conceptuses, followed by endometria obtained from pregnant animals on day 15 (P15: pre-attachment), 17 (P17: right after attachment), and 21 (P21: post-attachment; adhesion) and iTRAQ analysis of uterine flushing on P15 and P17. To identify the proteins secreted from conceptuses, we cross-referenced the transcriptome and proteome data. These analyses identified 16 and 26 proteins as conceptus secretory proteins on P15 and P17, respectively. Gene ontology analysis revealed that the conceptus secretory proteins were enriched in those categorized to fibrinolysis and coagulation. RT-qPCR analysis verified that the expression levels of transcripts in conceptuses encoding coagulation factors, fibrinogen subunits, and fibrinolysis factors were significantly higher on P21 than on P15 or P17, which were supported by those through in situ hybridization, Western blotting and immunohistochemistry. Histology analysis confirmed that fibrin protein was present at the conceptus adhesion region on P21. These results suggest that in addition to the numerous adhesion molecules so far characterized, fibrin is a new candidate molecule for maintaining conceptus adhesion for pregnancy continuation in ruminants.

Soluble GPVI is elevated in injured patients: shedding is mediated by fibrin activation of GPVI.

Soluble glycoprotein VI (sGPVI) is shed from the platelet surface and is a marker of platelet activation in thrombotic conditions. We assessed sGPVI levels together with patient and clinical parameters in acute and chronic inflammatory conditions, including patients with thermal injury and inflammatory bowel disease and patients admitted to the intensive care unit (ICU) for elective cardiac surgery, trauma, acute brain injury, or prolonged ventilation. Plasma sGPVI was measured by enzyme-linked immunosorbent assay and was elevated on day 14 after thermal injury, and was higher in patients who developed sepsis. sGPVI levels were associated with sepsis, and the value for predicting sepsis was increased in combination with platelet count and Abbreviated Burn Severity Index. sGPVI levels positively correlated with levels of D-dimer (a fibrin degradation product) in ICU patients and patients with thermal injury. sGPVI levels in ICU patients at admission were significantly associated with 28- and 90-day mortality independent of platelet count. sGPVI levels in patients with thermal injury were associated with 28-day mortality at days 1, 14, and 21 when adjusting for platelet count. In both cohorts, sGPVI associations with mortality were stronger than D-dimer levels. Mechanistically, release of GPVI was triggered by exposure of platelets to polymerized fibrin, but not by engagement of G protein-coupled receptors by thrombin, adenosine 5'-diphosphate, or thromboxane mimetics. Enhanced fibrin production in these patients may therefore contribute to the observed elevated sGPVI levels. sGPVI is an important platelet-specific marker for platelet activation that predicts sepsis progression and mortality in injured patients.

Pathophysiological significance of protein hydrophobic interactions: An emerging hypothesis.

Fibrinogen is a unique protein that is converted into an insoluble fibrin in a single enzymatic event, which is a characteristic feature of fibrinogen due to its susceptibility to fibrinolytic degradation and dissolution. Although thrombosis is a result of activated blood coagulation, no explanation is being offered for the persistent presence of fibrin deposits in the affected organs. A classic example is stroke, in which the thrombolytic therapy is effective only during the first 3-4 h after the onset of thrombosis. This phenomenon can now be explained in terms of the modification of fibrinogen structure induced by hydroxyl radicals generated during the period of ischemia caused, in turn, by the blocking of the blood flow within the obstructed vessels. Fibrinogen modification involves intra-to intermolecular disulfide rearrangement induced by the reductive power of hydroxyl radicals that result in the exposition of buried hydrophobic epitopes. Such epitopes react readily with each other forming linkages stronger than the peptide covalent bonds, thus rendering them resistant to the proteolytic degradation. Also, limited reduction of human serum albumin (HSA) generates hydrophobic polymers that form huge insoluble complexes with fibrinogen. Consequently, such insoluble copolymers can be deposited within the circulation of various organs leading to their dysfunction. In conclusion, the study of protein hydrophobic interactions induced by a variety of nutritional and/or environmental factors can provide a rational explanation for a number of pathologic conditions including cardiovascular, neurologic, and other degenerative diseases including cancer.

Clot friction variation with fibrin content; implications for resistance to thrombectomy.

BACKGROUND: Despite significant advancements in the procedural efficacy of mechanical thrombectomy in patients with ischemic stroke in recent years, there still remains a portion of the population that does not achieve good recanalization. The reasons for this may be varied. We hypothesized that static friction between the clot and the vessel, or catheter wall might contribute to the difficulty in removing the clot. OBJECTIVE: To determine if there is a relationship between clot composition and the resistance to sliding (friction) which might contribute to resistance to clot removal. METHODS: As clot composition can vary significantly, we investigated five different types of clot in order to measure their respective frictional properties. To do this, a custom-made testing apparatus was created, consisting of various replaceable low-friction surfaces on which the clots could be placed. The surface was then gradually tilted until the clots began to slide; the angle at which this occurred is related to the coefficient of friction of the clots. The experiment was repeated on a bovine aortic surface in order to confirm the results. RESULTS: We found that fibrin-rich clots (<20% red blood cell content) have a significantly higher coefficient of friction than clots with a red blood cell content >20%. This result was confirmed by repeating the experiment on a bovine aortic surface as a representation of the interaction between clots and the arterial wall. CONCLUSIONS: The friction properties of clots were found to be related to the content ratio of fibrin to red blood cells. Future imaging techniques that could show fibrin and red blood cell content might help us to predict the 'stickiness' of a clot.

Viscoelastic Monitoring to Guide Hemostatic Resuscitation in Liver Transplantation Surgery.

Coagulopathic bleeding must be anticipated during liver transplantation (LT) surgery. Patients with end-stage liver disease (ESLD) often present with disease-related hematologic disturbances, including the loss of hepatic procoagulant and anticoagulant clotting factors and thrombocytopenia. Transplantation surgery itself presents additional hemostatic changes, including hyperfibrinolysis. Viscoelastic monitoring (VEM) is often used to provide targeted, personalized hemostatic therapies for complex bleeding states including cardiac surgery and major trauma. The use in these coagulopathic conditions led to its application to LT, although the mechanisms of coagulopathy in these patients are quite different. While VEM is often used during transplant surgeries in Europe and North America, evidence supporting its use is limited to a few small clinical studies. The theoretical and clinical applications of the standard and specialized VEM assays are discussed in the setting of LT and ESLD.

Ultrastructural, Confocal and Viscoelastic Characteristics of Whole Blood and Plasma After Exposure to Cadmium and Chromium Alone and in Combination: An Ex Vivo Study.

BACKGROUND/AIMS: Heavy metal pollution is increasing in the environment, contaminating water, food and air supplies. This can be linked to many anthropogenic activities. Heavy metals are absorbed through the skin, inhalation and/or orally. Irrespective of the manner of heavy metal entry in the body, the blood circulatory system is potentially the first to be affected following exposure and adverse effects on blood coagulation can lead to associated thrombotic disease. Although the plasma levels and the effects of cadmium (Cd) and chromium (Cr) on erythrocytes and lymphocytes have been described, the environmental exposure to heavy metals are not limited to a single metal and often involves metal mixtures, with each metal having different rates of absorption, different cellular, tissue, and organ targets. Therefore the aim of this study is to investigate the effects of the heavy metals Cd and Cr alone and whether Cr synergistically increases the effect of Cd on physiological important processes such as blood coagulation. METHODS: Human blood was exposed to the heavy metals ex vivo, and thereafter morphological analysis was performed with scanning electron- and confocal laser scanning microscopy (CLSM) in conjunction with thromboelastography®. RESULTS: The erythrocytes, platelets and fibrin networks presented with ultrastructural changes, including varied erythrocytes morphologies, activated platelets and significantly thicker fibrin fibres in the metal-exposed groups. CLSM analysis revealed the presence of phosphatidylserine on the outer surface of the membranes of the spherocytic erythrocytes exposed to Cd and Cr alone and in combination. The viscoelastic analysis revealed only a trend that indicates that clots that will form after heavy metal exposure, will likely be fragile and unstable especially for Cd and Cr in combination. CONCLUSION: This study identified the blood as an important target system of Cd and Cr toxicity.

Hematopoietic-to-mesenchymal transition of adipose tissue macrophages is regulated by integrin ß1 and fabricated fibrin matrices.

Some bona fide adult adipocytes arise de novo from a bone marrow-derived myeloid lineage. These studies further demonstrate that adipose tissue stroma contains a resident population of myeloid cells capable of adipocyte and multilineage mesenchymal differentiation. These resident myeloid cells lack hematopoietic markers and express mesenchymal and progenitor cell markers. Because bone marrow mesenchymal progenitor cells have not been shown to enter the circulation, we hypothesized that myeloid cells acquire mesenchymal differentiation capacity in adipose tissue. We fabricated a 3-dimensional fibrin matrix culture system to define the adipose differentiation potential of adipose tissue-resident myeloid subpopulations, including macrophages, granulocytes and dendritic cells. Our data show that multilineage mesenchymal potential was limited to adipose tissue macrophages, characterized by the acquisition of adipocyte, osteoblast, chondrocyte and skeletal muscle myocyte phenotypes. Fibrin hydrogel matrices stimulated macrophage loss of hematopoietic cell lineage determinants and the expression of mesenchymal and progenitor cell markers, including integrin ß1. Ablation of integrin ß1 in macrophages inhibited adipocyte specification. Therefore, some bona fide adipocytes are specifically derived from adipose tissue-resident macrophages via an integrin ß1-dependent hematopoietic-to-mesenchymal transition, whereby they become capable of multipotent mesenchymal differentiation. The requirement for integrin ß1 highlights this molecule as a potential target for controlling the production of marrow-derived adipocytes and their contribution to adipose tissue development and function.

Interface between breast cancer cells and the tumor microenvironment using platelet-rich plasma to promote tumor angiogenesis - influence of platelets and fibrin bundles on the behavior of breast tumor cells.

Cancer progression is associated with an evolving tissue interface of direct epithelial-tumor microenvironment interactions. In biopsies of human breast tumors, extensive alterations in molecular pathways are correlated with cancer staging on both sides of the tumor-stroma interface. These interactions provide a pivotal paracrine signaling to induce malignant phenotype transition, the epithelial-mesenchymal transition (EMT). We explored how the direct contact between platelets-fibrin bundles primes metastasis using platelet-rich plasma (PRP) as a source of growth factors and mimics the provisional fibrin matrix between actively growing breast cancer cells and the tumor stroma. We have demonstrated PRP functions, modulating cell proliferation that is tumor-subtype and cancer cell-type-specific. Epithelial and stromal primary cells were prepared from breast cancer biopsies from 21 women with different cancer subtypes. Cells supplemented with PRP were immunoblotted with anti-phospho and total Src-Tyr-416, FAK-Try-925, E-cadherin, N-cadherin, TGF-ß, Smad2, and Snail monoclonal antibodies. Breast tumor cells from luminal B and HER2 subtypes showed the most malignant profiles and the expression of thrombin and other classes of proteases at levels that were detectable through FRET peptide libraries. The angiogenesis process was investigated in the interface obtained between platelet-fibrin-breast tumor cells co-cultured with HUVEC cells. Luminal B and HER2 cells showed robust endothelial cell capillary-like tubes ex vivo. The studied interface contributes to the attachment of endothelial cells, provides a source of growth factors, and is a solid substrate. Thus, replacement of FBS supplementation with PRP supplementation represents an efficient and simple approach for mimicking the real multifactorial tumor microenvironment.

Vascularization after treatment of gingival recession defects with platelet-rich fibrin or connective tissue graft.

OBJECTIVE: The aim of this study was to evaluate histologically the following treatment of bilateral localized gingival recessions with coronally advanced flap (CAF) combined with platelet-rich fibrin (PRF) or subepithelial connective tissue graft (SCTG). MATERIALS AND METHODS: Tissue samples were harvested from 14 subjects either 1 or 6 months after the surgeries. The 2-mm punch biopsies were obtained from the mid-portion of the grafted sites. Neutral buffered formalin fixed, paraffin-embedded 5-µm thick tissue sections were stained with hematoxylin eosin and Masson's trichrome in order to analyze the collagen framework, epithelium thickness and rete-peg length. Multiple sequential sections were cut from paraffin-embedded blocks of tissue and immunohistochemically prepared for detection of vascular endothelial growth factor, CD31 and CD34, for the assessment of vascularization. RESULTS: Rete peg formation was significantly increased in the sites treated with PRF compared to the SCTG group after 6 months (p < 0.05). On the contrary, the number of vessels was increased in the SCTG group compared to the PRF group after 6 months (p < 0.05). No statistically significant differences were observed in the collagen density. Staining intensity of CD31 increased in submucosal area of PRF group than SCTG group after 1 month. Higher staining intensity of CD34 was observed in the submucosal area of PRF group compared with SCTG group after 6 months. CONCLUSIONS: The results of the present study suggest that in histological evaluation because of its biological compounds, PRF results earlier vessel formation and tissue maturation compared to connective tissue graft. CLINICAL RELEVANCE: PRF regulated the vascular response associated with an earlier wound healing.

Generalidades del sistema de la coagulación y pruebas para su estudio / Overwiew of the Coagulation System and laboratory tests for its study

En la década de los años sesenta, se describió la cascada de la coagulación como una secuencia de eventos enzimáticos iniciada por dos vías, la intrínseca y la extrínseca, las cuales convergían en una vía común para generar una enzima multifuncional, denominada trombina. La principal función de esta enzima consistía en transformar el fibrinógeno, en fibrina, una proteína que se polimeriza espontáneamente para formar la base estructural del coágulo. Posteriormente, se propuso el Modelo Celular según el cual la coagulación no es la consecuencia de vías de activación enzimáticas secuenciales, sino de una red de interacciones entre proteínas plasmáticas y transmembranas, así como, varios tipos celulares, que permiten la formación de complejos enzimáticos altamente eficientes con la finalidad de generar trombina. Esta revisión explica en detalle ambos enfoques, además, aborda las diferentes funciones que cumple la trombina dentro de la hemostasia y los mecanismos de inhibición que regulan la coagulación. Finalmente, se describen diferentes pruebas empleadas en la actualidad para evaluar la funcionalidad del sistema de coagulación, como: el tiempo de tromboplastina parcial activado, el tiempo de protrombina, el tiempo de trombina, el tiempo de reptilasa, el tiempo de coagulación por ecarina y el uso de sustratos cromogénicos para evaluar cada factor de la coagulación. Finalmente, dado a que la generación de trombina es clave dentro de la coagulación y a que el potencial de generar trombina puede indicar propensión a desarrollar eventos trombóticos o hemorrágicos, en este trabajo se presentan los métodos existentes para determinar la generación de trombina.

In the sixties, the clotting cascade was proposed, which describes the coagulation process as a sequence of enzymatic events initiated by two different pathways, the intrinsic and the extrinsic pathways, converging on a common pathway, to generate a multifunctional enzyme, thrombin, whose main function is to convert fibrinogen into fibrin, a protein that polymerizes spontaneously to form the building block of a hemostatic clot. Later, it was proposed a cell-based model of the hemostasis according to that coagulation does not occur as a consequence of linear sequential enzyme activation pathways, but rather via a network of simultaneous interactions between plasmatic and transmembrane proteins, as well as several cellular types, that allow the formation of highly efficient enzymatic complexes that lead to thrombin generation. In this review, we summarize these two approaches highlighting the functions of thrombin within the hemostasis and the inhibition mechanisms that regulate the blood coagulation. Moreover, we described different tests that are used to assess the function of the coagulation system, such as: activated partial thromboplastin time, prothrombin time, thrombin time, reptilase time, ecarin clotting time, and the use of chromogenic substrates to evaluate individual coagulation factors. Finally, because of thrombin generation is a fundamental part of the blood coagulation and, an estimation of how well a particular individual can generate thrombin may correlate with either a risk of bleeding or thrombosis, we also include the existing methods to evaluate the potential of thrombin generation in an individual.

Altered Fibrin Clot Properties in Patients With Cerebral Venous Sinus Thrombosis: Association With the Risk of Recurrence.

BACKGROUND AND PURPOSE: Venous thromboembolism and ischemic stroke are associated with unfavorable fibrin clot structure and function. We hypothesized that denser fibrin networks displaying impaired lysability characterize patients with cerebral venous sinus thrombosis (CVST). METHODS: We assessed plasma fibrin clot properties in 50 patients (aged 38.9±9.8 years, 36 women) after the first CVST unrelated to trauma or malignancy after anticoagulation withdrawal and 50 well-matched controls. Recurrences were recorded during follow-up (18-46; median, 36 months). RESULTS: Clot permeability was lower in patients with CVST than in controls (Ks, 6.43±0.97 versus 7.3±1.2 10(-9) cm(2); P<0.001) and was associated with prolonged clot lysis time (103.0±16.8 versus 92.4±16.2 minutes; P<0.001), lower maximum rate of D-dimer release from clots (0.068 [0.064-0.071] versus 0.072 [0.067-0.078] mg/L per minute; P<0.001) and higher maximum D-dimer levels in the lysis assay (4.39±0.56 versus 4.19±0.46 mg/L, respectively; P=0.03). Patients with CVST had a slightly shorter lag phase (P=0.02) and higher maximum absorbance of fibrin gels on turbidimetry (P<0.001) compared with controls. Deficiencies in natural anticoagulants or antiphospholipid syndrome, and factor V Leiden occurred more often in the patients (P<0.05). CVST recurred in 6 patients (12%) and was associated with 21% higher baseline fibrinogen (P=0.007), 20% lower Ks (P=0.04) and 17% greater D-Dmax (P=0.01). Multiple logistic regression showed that only elevated D-Dmax (>4.83 mg/L) predicted CVST recurrence (odds ratio, 5.1; 95% confidence interval, 1.63-16.19) after adjustment for fibrinogen. CONCLUSIONS: CVST is associated with the formation of more compact plasma fibrin clots and resistance to fibrinolysis, which may predispose to the recurrence.

Quantifying cell-induced matrix deformation in three dimensions based on imaging matrix fibers.

During processes such as development and cancer metastasis, cells migrate into three-dimensional fibrous matrices. Previous studies have speculated on the mechanical forces required for migration by observing matrix fiber alignment, densification, and degradation, but these forces remain difficult to quantify. Here we present a new experimental technique to simultaneously measure full-field 3D displacements and structural remodeling of a fibrous matrix, both of which result from cellular forces. We apply this "2-in-1" experimental technique to follow single cells as they invade a physiologically relevant fibrin matrix. We find that cells generate tube-like structures in the matrix by plastically deforming their surroundings, and they re-use these tubes to extend protrusions. Cells generate these tubular structures by applying both pulling and pushing forces.

A fibrin matrix promotes the differentiation of EMSCs isolated from nasal respiratory mucosa to myelinating phenotypical Schwann-like cells.

Because Schwann cells perform the triple tasks of myelination, axon guidance and neurotrophin synthesis, they are candidates for cell transplantation that might cure some types of nervous-system degenerative diseases or injuries. However, Schwann cells are difficult to obtain. As another option, ectomesenchymal stem cells (EMSCs) can be easily harvested from the nasal respiratory mucosa. Whether fibrin, an important transplantation vehicle, can improve the differentiation of EMSCs into Schwann-like cells (SLCs) deserves further research. EMSCs were isolated from rat nasal respiratory mucosa and were purified using anti-CD133 magnetic cell sorting. The purified cells strongly expressed HNK-1, nestin, p75(NTR), S-100, and vimentin. Using nuclear staining, the MTT assay and Western blotting analysis of the expression of cell-cycle markers, the proliferation rate of EMSCs on a fibrin matrix was found to be significantly higher than that of cells grown on a plastic surface but insignificantly lower than that of cells grown on fibronectin. Additionally, the EMSCs grown on the fibrin matrix expressed myelination-related molecules, including myelin basic protein (MBP), 2',3'-cyclic nucleotide 3'-phosphodiesterase (CNPase) and galactocerebrosides (GalCer), more strongly than did those grown on fibronectin or a plastic surface. Furthermore, the EMSCs grown on the fibrin matrix synthesized more neurotrophins compared with those grown on fibronectin or a plastic surface. The expression level of integrin in EMSCs grown on fibrin was similar to that of cells grown on fibronectin but was higher than that of cells grown on a plastic surface. These results demonstrated that fibrin not only promoted EMSC proliferation but also the differentiation of EMSCs into the SLCs. Our findings suggested that fibrin has great promise as a cell transplantation vehicle for the treatment of some types of nervous system diseases or injuries.

Effect of osteogenic periosteal distraction by a modified Hyrax device with and without platelet-rich fibrin on bone formation in a rabbit model: a pilot study.

This study evaluated the effect of a modified Hyrax device and platelet-rich fibrin (PRF) on osteogenic periosteal distraction (OPD). Twelve adult male New Zealand white rabbits were separated into two main groups (six in each) according to the duration of the consolidation period (4 or 8 weeks). In each main group, the animals underwent OPD of the left and right sides of the mandible and were divided into four subgroups (three animals per group): device vs. device+PRF, and PRF vs. sham. Radiographic, histological, histomorphometric, and micro-computed tomography (micro-CT) analyses were performed. New bone formation was observed on the lateral and vertical sides of the mandible of all groups. Micro-CT and histomorphometry showed that the device+PRF group presented the highest percentages of bone volume and bone area at 4 weeks (56.67 ± 12.67%, 41.37 ± 7.57%) and at 8 weeks (49.67 ± 8.33%, 55.46 ± 10.67%; significantly higher than the other groups, P<0.001), followed by the device group at 4 weeks (33.00 ± 1.73%, 33.21 ± 11.00%) and at 8 weeks (30.00 ± 3.00%, 23.25 ± 5.46%). In conclusion, the modified Hyrax device was used successfully for OPD in a rabbit model to gain vertical ridge augmentation, and greater bone maturation was achieved with the addition of PRF.

Influence of the association between platelet-rich fibrin and bovine bone on bone regeneration. A histomorphometric study in the calvaria of rats.

This study aimed to investigate the effects of platelet-rich fibrin (PRF) associated or not with Bio-Oss on bone defects in the calvaria of rats. A critical-size defect of 5-mm diameter was performed in the calvaria of 48 rats. These animals were divided into six groups of eight animals each, according to the treatment received: homogeneous clot, autogenous clot, autogenous PRF, homogeneous PRF, Bio-Oss, or Bio-Oss associated with PRF. The animals were euthanized after 30 or 60 days. Bone regeneration was evaluated by histomorphometric analysis. The highest mean percentages of new bone formation at 30 days (54.05% ± 5.78) and 60 days (63.58% ± 5.78) were observed in the Bio-Oss associated with PRF group; in particular, the percentage of new bone at 30 days was significantly higher than that of all of the other groups (P<0.01). At 60 days, the Bio-Oss associated with PRF (63.58% ± 5.78) and Bio-Oss (57.34% ± 5.78) groups had similar results, and both showed a statistical difference compared to the other groups. PRF had a positive effect on bone regeneration only when associated with Bio-Oss.

Textile heart valve: first in-vivo experiment in the aortic position.

Non-invasive aortic valve implantation has become an alternative technique to surgical valve replacement in patients at high risk for open-chest surgery. With over 100,000 procedures already performed clinically, the technology is expected to involve less-critical patients in future. Whereas, biological valve tissue is a fragile material when folded for low-diameter catheter insertion purposes, textile polyester is a less-fragile material and may offer an alternative material to replace valve leaflets. One issue related to textile is the porosity of the material, which may induce exaggerated tissue ingrowth. Today, data relating to interactions between living tissues and fabrics used as valve materials are available only in the mitral position. Hence, the study aim was to observe the interaction pattern when the valve is implanted in the aortic position, and to assess the influence of sinus whirls on this pattern.

Evaluation of fibrin-based gene-activated matrices for BMP2/7 plasmid codelivery in a rat nonunion model.

PURPOSE: Treatment of large-segmental bone defects still is a challenge in clinical routine. Application of gene-activated matrices (GAMs) based on fibrin, bone morphogenic protein (BMP) 2/7 plasmids and nonviral transfection reagents (cationic polymers) could be an innovative treatment strategy to overcome this problem. The aim of this study was to determine the therapeutic efficacy of fibrin GAMs with or without additional transfection reagents for BMP2 and 7 plasmid codelivery in a femur nonunion rat model. METHODS: In this experimental study, a critical-sized femoral defect was created in 27 rats. At four weeks after the surgery, animals were separated into four groups and underwent a second operation. Fibrin clots containing BMP2/7 plasmids with and without cationic polymer were implanted into the femoral defect. Fibrin clots containing recombinant human (rh) BMP2 served as positive and clots without supplement as negative controls. RESULTS: At eight weeks, animals that received GAMs containing the cationic polymer and BMP2/7 plasmids showed decreased bone volume compared with animals treated with GAMs and BMP2/7 only. Application of BMP2/7 plasmids in fibrin GAMs without cationic polymer led to variable results. Animals that received rhBMP2 protein showed increased bone volume, and osseous unions were achieved in two of six animals. CONCLUSIONS: Cationic polymers decrease therapeutic efficiency of fibrin GAM-based BMP2/7 plasmid codelivery in bone regeneration. Nonviral gene transfer of BMP2/7 plasmids needs alternative promoters (e.g. by sonoporation, electroporation) to produce beneficial clinical effects.

Endocrine regulation of airway contractility is overlooked.

Asthma is a prevalent respiratory disorder triggered by a variety of inhaled environmental factors, such as allergens, viruses, and pollutants. Asthma is characterized by an elevated activation of the smooth muscle surrounding the airways, as well as a propensity of the airways to narrow excessively in response to a spasmogen (i.e. contractile agonist), a feature called airway hyperresponsiveness. The level of airway smooth muscle (ASM) activation is putatively controlled by mediators released in its vicinity. In asthma, many mediators that affect ASM contractility originate from inflammatory cells that are mobilized into the airways, such as eosinophils. However, mounting evidence indicates that mediators released by remote organs can also influence the level of activation of ASM, as well as its level of responsiveness to spasmogens and relaxant agonists. These remote mediators are transported through circulating blood to act either directly on ASM or indirectly via the nervous system by tuning the level of cholinergic activation of ASM. Indeed, mediators generated from diverse organs, including the adrenals, pancreas, adipose tissue, gonads, heart, intestines, and stomach, affect the contractility of ASM. Together, these results suggest that, apart from a paracrine mode of regulation, ASM is subjected to an endocrine mode of regulation. The results also imply that defects in organs other than the lungs can contribute to asthma symptoms and severity. In this review, I suggest that the endocrine mode of regulation of ASM contractility is overlooked.

Altered plasma fibrin clot properties and fibrinolysis in patients with multiple myeloma.

BACKGROUND: Multiple myeloma (MM) is associated with increased risk of venous and arterial thromboembolism. Formation of denser and poorly lysable fibrin clots is observed in patients with arterial and venous thromboembolism. We investigated fibrin clot properties and their determinants in MM patients. MATERIALS AND METHODS: Ex vivo plasma fibrin clot permeability, turbidity and susceptibility to lysis were evaluated in 106 MM patients at the time of diagnosis vs. 100 age- and sex-matched controls. MM patients had lower clot permeability (Ks ), compaction, indicating denser fibrin clots, impaired fibrin polymerization with longer lag phase and lower final turbidity (D-Dmax ), combined with hypofibrinolysis reflected by longer lysis time and slower rate of D-dimer release from fibrin clots (D-Drate ) compared with controls (all P < 0·001). RESULTS: Patients with IgG MM had lower Ks compared with IgA MM [5·9 (5·1-6·4) vs. 6·3 (5·9-7·2) 10(-9)  cm(2) ; P = 0·007] and longer lysis time compared with light-chain-disease patients [11·4 (10·9-12·3) vs. 10·7 (9·8-11·9) min; P = 0·022]. Of the fibrin variables, only Ks was significantly lower in patients with International Staging System (ISS) grade III than in those with ISS grade I and II [5·9 (4·9-6·6) vs. 6·2 (5·7-6·8) 10(-9)  cm(2) ; P = 0·015]. Multivariate analysis adjusted for age and fibrinogen showed that in MM patients elevated peak thrombin levels determine Ks and D-Dmax , while thrombin-activatable fibrinolysis inhibitor (TAFI) activity predicts Ks , t50% , D-Drate and lag phase. CONCLUSIONS: Our study demonstrates prothrombotic fibrin clot phenotype in patients with MM, with a significant impact of increased thrombin formation and TAFI activity.