Analysis of fibrinogen concentrate pharmacokinetics and dosing for bleeds and surgery in adults, adolescents, and children with congenital afibrinogenaemia and hypofibrinogenaemia.

INTRODUCTION: Congenital afibrinogenaemia and hypofibrinogenaemia are rare coagulation disorders where clotting is impaired due to a lack of fibrinogen. Consequent bleeding episodes (BEs) are treated using human fibrinogen concentrate (HFC). AIM: This post-hoc analysis compared HFC pharmacokinetics (PK) and dosing between patient age groups and defined the in vivo recovery (IVR) for children with a- and hypofibrinogenaemia. METHODS: The analysis used data from the FORMA-01 (Phase 2), FORMA-02 and FORMA-04 (Phase 3) multinational, prospective, open-label studies in patients with a- and hypofibrinogenaemia. HFC PK in adults/adolescents (≥12 years; FORMA-01) and children (<12 years; FORMA-04) was examined. Haemostatic efficacy in BE treatment and perioperative prophylaxis was examined in FORMA-02 and FORMA-04 using an objective 4-point scale, with success defined as excellent/good. RESULTS: Median (range) age was 23 years for FORMA-01 (12-53; n = 22), 26.5 years for FORMA-02 (12-54; n = 25), and 6 years for FORMA-04 (1-10; n = 13). Mean PK parameters were lower for children (AUC, Cmax , IVR; p = .02), while clearance was higher. Median (range) total dose of HFC for all BEs was 59.41 mg/kg (32.12-273.80) in adults/adolescents and was 24% higher (ns) in children at 73.91 mg/kg (47.45-262.50). Treatment was successful in 98.9% of the 89 BEs in adults/adolescents and in 100% of the 10 BEs in children, with comparable results for perioperative prophylaxis. CONCLUSION: As expected, HFC PK differed between adults/adolescents and children. However, with the higher doses given to children, HFC showed similar efficacy across age groups. Dose adaptation based on age groups appears recommendable.

Recombinant Human HPS Protects Mice and Nonhuman Primates from Acute Liver Injury.

Acute liver injury shares a common feature of hepatocytes death, immune system disorders, and cellular stress. Hepassocin (HPS) is a hepatokine that has ability to promote hepatocytes proliferation and to protect rats from D-galactose (D-Gal)- or carbon tetrachloride (CCl4)-induced liver injury by stimulating hepatocytes proliferation and preventing the high mortality rate, hepatocyte death, and hepatic inflammation. In this paper, we generated a pharmaceutical-grade recombinant human HPS using mammalian cells expression system and evaluated the effects of HPS administration on the pathogenesis of acute liver injury in monkey and mice. In the model mice of D-galactosamine (D-GalN) plus lipopolysaccharide (LPS)-induced liver injury, HPS treatment significantly reduced hepatocyte death and inflammation response, and consequently attenuated the development of acute liver failure. In the model monkey of D-GalN-induced liver injury, HPS administration promoted hepatocytes proliferation, prevented hepatocyte apoptosis and oxidation stress, and resulted in amelioration of liver injury. Furthermore, the primary pharmacokinetic study showed natural HPS possesses favorable pharmacokinetics; the acute toxicity study indicated no significant changes in behavioral, clinical, or histopathological parameters of HPS-treated mice, implying the clinical potential of HPS. Our results suggest that exogenous HPS has protective effects on acute liver injury in both mice and monkeys. HPS or HPS analogues and mimetics may provide novel drugs for the treatment of acute liver injury.

Fibrinogen concentrates in hereditary fibrinogen disorders: Past, present and future.

Hereditary fibrinogen disorders (HFD) are rare coagulation disorders. Even if the spectrum of symptoms is broad depending on the sub-type, bleeding is the most common complication. Of the available sources of fibrinogen replacement, fibrinogen concentrate provides a safer and more effective option to treat and prevent bleeding. Recent clinical trials on established and new fibrinogen concentrates have increased our knowledge on the clinical pharmacology of these products, pointing out possible age and weight differences for dose adjustment. The efficacy of fibrinogen infusions has been demonstrated, especially for the management of acute bleeding with an excellent response based on investigator rating. The target fibrinogen levels in the setting of both minor and major surgeries have been better specified. The safety has been confirmed with a low number of adverse events but there still remains concern over possible thrombotic risks. Pharmacological, clinical aspects and future perspectives on the utilization of fibrinogen concentrates in the treatment and prevention of bleeding in patients with HFD are reviewed.

Pharmacokinetic study of the structural components of adenosine diphosphate-encapsulated liposomes coated with fibrinogen γ-chain dodecapeptide as a synthetic platelet substitute.

Fibrinogen γ-chain (dodecapeptide HHLGGAKQAGDV, H12)-coated, ADP-encapsulated liposomes [H12-(ADP)-liposomes] were developed as a synthetic platelet alternative that specifically accumulates at bleeding sites as the result of interactions with activated platelets via glycoprotein IIb/IIIa and augments platelet aggregation by releasing ADP. The aim of this study is to characterize the pharmacokinetic properties of H12-(ADP)-liposomes and structural components in rats, and to predict the blood retention of H12-(ADP)-liposomes in humans. With use of H12-(ADP)-liposomes in which the encapsulated ADP and liposomal membrane cholesterol were radiolabeled with (14)C and (3)H, respectively, it was found that the time courses for the plasma concentration curves of (14)C and (3)H radioactivity showed that the H12-(ADP)-liposomes remained intact in the blood circulation for up to 24 hours after injection, and were mainly distributed to the liver and spleen. However, the (14)C and (3)H radioactivity of H12-(ADP)-liposomes disappeared from organs within 7 days after injection. The encapsulated ADP was metabolized to allantoin, which is the final metabolite of ADP in rodents, and was mainly eliminated in the urine, whereas the cholesterol was mainly eliminated in feces. In addition, the half-life of the H12-(ADP)-liposomes in humans was predicted to be approximately 96 hours from pharmacokinetic data obtained for mice, rats, and rabbits using an allometric equation. These results suggest that the H12-(ADP)-liposome has potential with proper pharmacokinetic and acceptable biodegradable properties as a synthetic platelet substitute.

Pharmacokinetic study of minipooled solvent/detergent-filtered cryoprecipitate factor VIII.

Eighteen cryoprecipitate minipools, each made of 30 units of low volume, concentrated cryoprecipitate, have been treated by solvent-detergent and filtration (S/D-F) in a single-use CE-marked bag system. The S/D-F cryoprecipitate contained a mean of 10.5 IU mL⁻¹ factor VIII (FVIII), 17 mg mL⁻¹ clottable fibrinogen, and >10 IU mL⁻¹ von Willebrand factor ristocetin co-factor, and anti-A and anti-B isoagglutinins were undetectable. The products have been infused in 11 severe (FVIII <1%) haemophilia A patients (mean age: 17.4 years; mean weight: 57.6 kg) at a dose close to 40 IU kg⁻¹. Patients were hospitalized for at least 36 h to determine FVIII recovery, half-life and clearance. They were also closely monitored for possible adverse events. None of the infused patients demonstrated reactions or adverse events even though they did not receive anti-allergic drugs or corticosteroids prior to infusion. The mean recovery of FVIII 10 min postinfusion was 69.7%. Mean FVIII half-life was 14.2 h and clearance was 2.6 mL h⁻¹ kg⁻¹. All patients had a bleeding-free interval of 8-10 days postS/D-F cryoprecipitate infusion. The data show that S/D-F cryoprecipitate FVIII presents a normal pharmacokinetics profile, and support that it could be safely used for the control of acute and chronic bleeding episodes in haemophilia A patients.

Pharmacology, Efficacy and Safety of a Triple-Secured Fibrinogen Concentrate in Children Less than or Equal to 12 Years with Afibrinogenaemia.

OBJECTIVE: To date, the use of a fibrinogen concentrate (FC) administered in children with inherited fibrinogen deficiency is poorly documented. Treatment modalities may differ from those of adults. The aim of this study was to investigate the pharmacokinetics (PK), efficacy (bleeding/surgery) and safety of a triple-secured FC (FibCLOT, LFB, France) in young patients aged of 12 years or less. METHODS: This was a prospective, non-comparative, multicentre, phase 2-3 study. Estimated PK parameters were based on population PK modelling. Target fibrinogen levels were 1.2 and 1.0 g/L for major and minor events, respectively. In vivo recovery (IVR) was calculated at study entry to tailor the dose. RESULTS: Sixteen afibrinogenaemia patients were treated with FC: 12 included in the PK study (6 aged ≤ 6 years and 6 aged 7-12 years). IVR at 1 hour post-infusion (geometric mean [coefficient of variation]) was 1.91 [20%] mg/dL per mg/kg and results were similar between the two age groups (1.87 [14%]) and (1.96 [27%]) with no statistical differences. Estimated half-life (t 1/2) was 49.0 hours [12%] with no observed differences between groups (46.6 hours [10%] and 51.6 hours [12%]). Overall efficacy was rated as excellent/good in 96.9% of 32 bleeds and in 100% of 11 surgeries. Most of the events (39/43, 90.7%) were managed with one infusion. There was no serious adverse drug reaction. CONCLUSION: Individually tailored dosing was efficacious in children who exhibited a lower IVR and shorter t 1/2 than those previously reported in adolescent and adult patients emphasising the importance of individualised dose optimisation.

TecoflexTM functionalization by curdlan and its effect on protein adsorption and bacterial and tissue cell adhesion.

Curdlan modified polyurethane was created by physically entrapping the former on TecoflexTM surface. ATR-FT-IR, SEM-EDAX and AFM analysis revealed the formation of stable thin curdlan layer on the film. Contact-angle measurements showed that the modified film was highly hydrophilic. Confocal laser scanning microscopy showed the existence of entrapped layer of approximately 20-25 microm in depth. Surface entrapment of curdlan minimized both protein adsorption and mouse L929 fibroblast cell adhesion relative to the control. Surface induced cellular inflammatory response was determined from the expression levels of proinflammatory cytokine TNF-alpha, by measuring their mRNA profiles in the cells using real time polymerase chain reaction (RT-PCR) normalized to the housekeeping gene GAPDH. The inflammatory response was suppressed on the modified substrate as expression of TNF-alpha mRNA was found to be up regulated on TecoflexTM, while it was significantly lower on curdlan substrate. The adhesion of S. aureus decreased by 62% on curdlan modified surface. Using such simple surface entrapment process, it will be possible to develop well-defined surface modifications that promote specific cell interactions and perhaps better performance in the long-term as implant.

Iodine-125-fibrinogen kinetics in the rabbit arterial wall.

Elevated fibrinogen has been claimed as an independent risk factor for the development of atherosclerosis. Incorporation of fibrinogen into human atherosclerotic lesions has been demonstrated. We assessed in a rabbit model of experimental atherosclerosis, biodistribution as well as kinetics and vascular uptake of (125)I-fibrinogen. Rabbits aged 6 months were fed a 1% cholesterol supplemented diet. After experimental de-endothelialization of rabbit aorta using a Fogarthy catheter, (125)I-fibrinogen uptake was enhanced by more than one order of magnitude as compared to intact segments covered by endothelium. Six rabbits per group were examined. Even re-endothelialized segments showed a significantly higher uptake of the radiolabeled protein. Maximum arterial uptake varied between 12 (de- and re-endothelialized segments) and 24h (intact areas) after injection of (125)I-fibrinogen. In conclusion, these experiments for the first time suggest the increased uptake of radiolabeled fibrinogen in the aortic de-endothelized wall in rabbits.

Clinical pharmacology, efficacy and safety study of a triple-secured fibrinogen concentrate in adults and adolescent patients with congenital fibrinogen deficiency.

Essentials A novel fibrinogen concentrate was evaluated in patients with congenital fibrinogen deficiency. An open-label, phase 2-3 trial studied pharmacology, efficacy, and safety in patients >6 years. The product offers safe and effective therapy in the treatment and prophylaxis of bleeding. Data in recovery show the need of adjusted treatment and further investigation in children. SUMMARY: Background Single-factor replacement therapy is considered the most suitable treatment option for hereditary fibrinogen deficiency. A triple-secured plasma-derived human fibrinogen product was developed to increase the safety of the former fibrinogen concentrate. Objectives This non-randomized, open-label, prospective study investigated pharmacokinetics, efficacy, and safety of a novel fibrinogen concentrate (FibCLOT® /CLOTTAFACT® LFB, France) in inherited deficiency. Patients/Methods Fourteen patients ≥40 kg received fibrinogen concentrate for pharmacology and 16 ≥ 23 kg received treatment for bleeding or surgery. Each treatment was followed by a 3-week safety observation period. Key outcomes included number of infusions, dose, bleeding control, daily assessment, hemoglobin, blood loss, transfusions, and physicians' global assessment of response. Results Incremental recovery was 2.35 mg mL-1  per mg kg-1 and maximal concentration 1.41 g L-1 (geometric mean) after 0.060 g kg-1 infusion in 14 afibrinogenemic patients. Terminal half-life was 69.3 h (non-compartmental analysis). The maximum clot firmness was increased by a mean of 10.3 mm from baseline to maximal effect. Sixteen patients participated to the efficacy phase: 32 bleeding episodes were treated in 9 patients, and 15 patients underwent 38 surgical/invasive procedures. All patients achieved appropriate hemostasis: response to treatment was successful in all bleeds (95% CI, 0.89-1.00) and procedures (95% CI, 0.91-1.00). Most (94%) bleeds were controlled with a single infusion (median 0.050 g kg-1 ). Two patients experienced asymptomatic distal venous thromboses identified by systematic ultrasound. Conclusion FibCLOT® /CLOTTAFACT® showed a pharmacokinetic profile comparable to that of other fibrinogen concentrates and provides safe and clinically effective substitution therapy for fibrinogen-deficient patients.

Novel cryoprecipitate for wound healing and skin grafts in rats.

The authors sought to evaluate the ability of locally administered enhanced cryoprecipitate (eCryo) to improve the wound healing of split thickness skin grafts (STSG) and their donor sites. An STSG (5 x 5 cm) was harvested on the back of 30 rats and divided into four areas that were then treated in one of the following groups: A: 'standard' dressing without STSG; B: eCryo without STSG; C: eCryo with STSG coverage and D: STSG alone. Macroscopic and histological assessments (histomorphometric grading scale and cellular composition) were evaluated at days 7, 14, 21 and 28 for wound healing. All wound beds as well as STSGs healed well without any complications. Eighty per cent of the STSG showed a histological graft take of >75% after 28 days. There were no statistically significant differences of macroscopic or histological results between the groups at any time point. Preparation of eCryo is easy and effective. Its use as an adhesive for STSGs is safe and shows similar results as controls. The theoretical benefits of eCryo did not show significant differences. Possible reasons as well as important findings for future research on wound healing are discussed.

Pharmacokinetics, clot strength and safety of a new fibrinogen concentrate: randomized comparison with active control in congenital fibrinogen deficiency.

Essentials Congenital afibrinogenemia causes a potentially life-threatening bleeding and clotting tendency. Two human fibrinogen concentrates (HFCs) were compared in a randomized pharmacokinetic study. Bioequivalence was not shown for AUCnorm , which was significantly larger for the new HFC. Increases in clot strength were comparable, and no thromboses or deaths occurred in the study. SUMMARY: Background Human fibrinogen concentrate (HFC) corrects fibrinogen deficiency in congenital a-/hypofibrinogenemia. Objectives To assess pharmacokinetics (PK), effects on thromboelastometry maximum clot firmness (MCF), and safety of a new double virus-inactivated/eliminated, highly purified HFC vs. active control. Patients/Methods In this multinational, randomized, phase II, open-label, crossover study in 22 congenital afibrinogenemia patients aged ≥ 12 years, 70 mg kg-1 of new HFC (FIBRYGA, Octapharma AG) or control (Haemocomplettan® P/RiaSTAP™, CSL Behring GmbH) were administered, followed by crossover to the other concentrate. Fibrinogen activity, PK and MCF in plasma were assessed. Results The concentrates were not bioequivalent for the primary endpoint, AUCnorm (mean ratio, 1.196; 90% confidence interval [CI], 1.117, 1.281). Remaining PK parameters (Cmaxnorm , IVR, t1/2 , MRT) reflected bioequivalence between concentrates, except for clearance (mean ratio, 0.836; 90% CI, 0.781, 0.895) and Vss (mean ratio, 0.886; 90% CI, 0.791, 0.994). Mean AUCnorm was significantly larger for the new HFC (1.62 ± 0.45 vs. 1.38 ± 0.47 h kg g L-1  mg-1 , P = 0.0001) and mean clearance was significantly slower (0.665 ± 0.197 vs. 0.804 ± 0.255 mL h-1  kg-1 , P = 0.0002). Mean MCF increased from 0 mm to 9.68 mm (new HFC) and 10.00 mm (control) 1-hour post-infusion (mean difference, -0.32 mm; 95% CI, -1.70, 1.07, n.s.). No deaths, thromboses, viral seroconversions or serious related adverse events occurred. Conclusions Bioequivalence was not demonstrated for AUCnorm , clearance and Vss . Larger AUCnorm and slower clearance were observed for the new HFC. Remaining pharmacokinetic parameters reflected bioequivalence to control. Safety profiles and increases in clot strength were comparable between concentrates.

Effect of biopassive and bioactive surface-coatings on the hemocompatibility of membrane oxygenators.

Postoperative complications associated with cardiopulmonary bypass (CPB) surgery and extracorporeal circulation (ECC) procedures are still a major clinical issue. Improving the hemocompatibility of blood contacting devices used for ECC procedures may ameliorate various postpump syndromes. In a simulated CPB model using human blood, we investigated the hemocompatibility, fibrinogen adsorption, and platelet receptor (GPIIb-IIIa) binding capacity of surface-modified membrane oxygenators (Jostra Quadrox). Three groups were compared: (i) biopassive protein coatings (SafeLine), (ii) bioactive heparin coatings (BioLine), and (iii) noncoated controls. During the 2 h recirculation period, plasma concentrations of activation markers for platelets (beta-thromboglobulin), inflammation (elastase), complement (C5a), and coagulation (prothrombin fragment 1+2, thrombin-antithrombin III) were lower in the groups with biopassive and bioactive coatings compared to the noncoated group (p < 0.01). These parameters did not significantly differ between the two surface-coated groups, except for complement activation: C5a levels were higher in the biopassive group compared to the bioactive group (p < 0.01). Moreover, surface-coated oxygenators showed less fibrinogen adsorption, GPIIb-IIIa binding, and platelet/leukocyte adhesion (p < 0.01). We assume that fewer fibrinogen and platelet receptor molecules bound to the surface-coated oxygenator surfaces results in fewer platelet adhesion and activation, which will significantly contribute to the improved hemocompatibility of the biopassive and bioactive oxygenators. Our results suggest that the application of bioactive oxygenators (BioLine) during CPB surgery may reduce postoperative complications for the patient more effectively than biopassive oxygenators (SafeLine).

Direct quantification of dual protein adsorption dynamics in three dimensional systems in presence of cells.

Understanding the composition of the adsorbed protein layer on a biomaterial surface is of an extreme importance as it directs the primary biological response. Direct detection using labeled proteins and indirect detection based on enzymatic assays or changes to mass, refractive index or density of a surface have been so far established. Nevertheless, using current methodologies, detection of multiple proteins simultaneously and particularly in a three-dimensional (3D) substrates is challenging, with the exception of radiolabeling. Here using fluorescence molecular tomography (FMT), we present a non-destructive and versatile approach to quantify adsorption of multiple proteins within 3D environments and reveal the dynamics of adsorption of human serum albumin (HSA) and fibrinogen (Fib) on 3D polymeric scaffold. Furthermore, we show that serum starved human articular chondrocytes in 3D environment preferentially uptake HSA over Fib and to our knowledge this represents the first example of direct visualization and quantification of protein adsorption in a 3D cell culture system. STATEMENT OF SIGNIFICANCE: The biomaterial surface upon exposure to biological fluids is covered by a layer of proteins, which is modified over a period of time and dictates the fate of the biomaterial. In this study, we present and validate a new methodology for quantification of protein adsorption on to a three-dimensional polymer scaffold from unitary and binary systems, using fluorescence molecular tomography, an optical trans-illumination technique with picomolar sensitivity. In additional to being able to follow behavior of two proteins simultaneously, this methodology is also suitable for studying protein uptake in cells situated in a polymer environment. The ability to follow protein adsorption/uptake in a continuous manner opens up new possibilities to study the role of serum proteins in biomaterial compatibility.

AFM force spectroscopy of the fibrinogen adsorption process onto dental implants.

Protein binding to implants is governed by the physicochemical properties of the biomaterial surface. The adhesion of a protein onto a solid surface is nonspecific. The aim of this study was to assess the adsorption process of fibrinogen at two different dental implants. The first biomaterial has a sand-blasted titanium surface, whereas the second one is covered by a calcium phosphate coating. After scanning electron microscopy and atomic force microscopy characterization of the implant surfaces, force spectroscopy has been used to determine the unbinding force of fibrinogen adsorbed at the two different substrates. Force-measurement findings indicate that the detachment force of fibrinogen adsorbed onto both surfaces varies as a function of the interaction time. The mean strength of the unbinding forces increases with the interaction time (100 and 1,000 ms, respectively). However, experimental data suggest that fibrinogen fixes to the two studied biomaterials by different mechanisms. Moreover, it appears that, after an interaction time of 1,000 ms, the detachment force of the adsorbed protein is quite larger for the titanium surface than for the calcium phosphate coating.

Competitive adsorption of fibrinogen and dipalmitoylphosphatidylcholine at the air/aqueous interface.

The competitive adsorption of fibrinogen (FB) and DPPC at the air/aqueous interface, in phosphate buffer saline at 25 degrees C, was studied with tensiometry, infrared reflection absorption spectroscopy (IRRAS), and ellipsometry. For FB/DPPC mixtures with 750 ppm (0.075 wt%) FB and 1000 ppm (0.10 wt%) DPPC, the tension behavior was found to be similar to that of FB when alone, even with DPPC and FB being at the interface. Thus, FB interferes with adsorption of DPPC and inhibits its surface tension lowering ability. When FB protein is introduced in the solution after a DPPC monolayer has formed, the adsorption of FB is inhibited by the DPPC monolayer. When a DPPC monolayer is spread onto a solution with a preadsorbed FB layer, the DPPC monolayer excludes FB from the surface and controls the tension behavior with little inhibition by FB. When a DPPC dispersion is introduced with the Trurnit method, or sprayed dropwise, onto an aqueous FB/DPPC surfaces, the DPPC layer formed on the surface prevents the adsorption of FB and dominates the surface tension behavior. These results have implications in controlling the inhibition of lung surfactant tension behavior by serum proteins, when they leak at the alveolar lining layer, and in developing surfactant replacement therapies for alveolar respiratory diseases.

In vivo magnetic resonance imaging of coronary thrombosis using a fibrin-binding molecular magnetic resonance contrast agent.

BACKGROUND: The advent of fibrin-binding molecular magnetic resonance (MR) contrast agents and advances in coronary MRI techniques offers the potential for direct imaging of coronary thrombosis. We tested the feasibility of this approach using a gadolinium (Gd)-based fibrin-binding contrast agent, EP-2104R (EPIX Medical Inc), in a swine model of coronary thrombus and in-stent thrombosis. METHODS AND RESULTS: Ex vivo and in vivo sensitivity of coronary MR thrombus imaging was tested by use of intracoronarily delivered Gd-DTPA-labeled fibrinogen thrombi (n=6). After successful demonstration, in-stent coronary thrombosis was induced by x-ray-guided placement of thrombogenic-coated, MR-lucent stents (n=5). After stent placement, 60 micromol of EP-2104R was injected via the left main coronary artery. Free-breathing, navigator-gated 3D coronary MR angiography and thrombus imaging were performed (1) before and after stent placement and (2) before and after EP-2104R. Thrombi were confirmed by x-ray angiography and autopsy. Fibrinogen thrombi: 5 of 6 intracoronarily delivered Gd-labeled fibrinogen clots (approximately 250 micromol/L Gd) were visible on MRI and subsequently confirmed by x-ray angiography. In-stent thrombi: in-stent thrombosis was observed in all stents after EP-2104R. Four of 5 thrombi were confirmed by x-ray angiography. Chemical analysis of 2 thrombi demonstrated 99 to 147 micromol/L Gd. CONCLUSIONS: We demonstrate the feasibility of MRI of coronary thrombus and in-stent thrombosis using a novel fibrin-binding molecular MR contrast agent. Potential applications include detection of coronary in-stent thrombosis or thrombus burden in patients with acute coronary syndromes.

Surface structures and properties of polystyrene/poly(methyl methacrylate) blends and copolymers.

Sum frequency generation (SFG) vibrational spectroscopy has been applied to study the molecular surface structures of polystyrene (PS)/poly(methyl methacrylate) (PMMA) blends and the copolymer between PS and PMMA (PS-co-PMMA) in air, supplemented by atomic force microscopy (AFM) and contact angle goniometer. Both the blend and the copolymer have equal weight amounts of the two components. SFG results show that both components, PS and PMMA, can segregate to the surface of the blend and the copolymer before annealing, although PMMA has a slightly higher surface tension. Upon annealing both SFG results and contact angle measurements indicate that the PS segregates to the surface of the PS/PMMA blend more but no change occurs on the PS-co-PMMA surface. AFM images show that the copolymer surface is flat but the 1:1 PS/PMMA blend has a rougher surface with island like domains present. The annealing effect on the blend surface morphology has also been investigated. We collected amide SFG signals from interfacial fibrinogen molecules at the copolymer or blend/protein solution interfaces as a function of time. Different time-dependent SFG signal changes have been observed, showing that different surfaces of the blend and the copolymer mediate fibrinogen adsorption behavior differently.

Interactions of carboplatin with fibrin(ogen), implications for local slow release chemotherapy.

The effect of carboplatin (CPt) on fibrin(ogen) clot formation and the possible use of this combination for local slow release chemotherapy were examined. CPt significantly reduced thrombin-induced fibrin clotting time (CT) and increased clot turbidity in a concentration-dependent manner. When CPt was mixed with physiological levels of fibrinogen (>1 mg/ml), electron-dense nanoparticles (3 nm) were formed, as demonstrated by both optical particle counter and transmission electron microscopy (TEM). Upon thrombin-induced coagulation, the CPt nanoparticles were trapped within the fibrin mesh. At higher fibrinogen levels (>5 mg/ml), the 3-nm CPt nanoparticles aggregated, so that approximately 2% and approximately 0.5% of the CPt on the fibrinogen appeared as larger particles of 10 and 50 nm, respectively. Dialysis experiments showed that 60-70% of the CPt was released from the fibrin clot within one hour as a non-particulate soluble form, while approximately 30% of particulate CPt were retained. Up to 5 mg/ml this portion of firmly attached CPt was dependent of the initial drug level. CPt released from the fibrin by either diffusion or by fibrinolysis exhibited cytotoxic activity towards retinoblastoma (RB) cell lines (Y-79 and Weri RB1) equivalent to free drug. Our study indicates that CPt enhances fibrin clot formation and suggests the use of fibrin with high dose CPt for slow release chemotherapy against localized tumors such as retinoblastoma.

Pharmacokinetic properties of a pasteurised fibrinogen concentrate.

The main pharmacokinetic characteristics of a plasma-derived, pasteurised fibrinogen concentrate were assessed in an open, multicentre, non-controlled study in five patients with congenital afibrinogenaemia or severe congenital hypofibrinogenaemia. Plasma samples were assayed for fibrinogen content in laboratories of the participating clinical centres (CCs) and additionally in a central laboratory at Aventis Behring (ABL). The values of the pharmacokinetic variables, using the fibrinogen determination at ABL, yielded a somewhat shorter terminal half-life compared with that determined at the CCs, with median (range) values of 2.7 days (2.5-3.7 days) versus 3.6 days (3.0-5.3 days), respectively. Fibrinogen clearance rate was clearly lower at the ABL with values of 0.91 ml/h/kg (0.84-1.22 ml/h/kg) compared with 1.65 ml/h/kg (0.82-2.55 ml/h/kg) at the CCs. The distribution volume at steady state (V-ss) of 89 ml/kg (81-116 ml/kg) was also smaller at the ABL than at the CCs (101 ml/kg [84-139 ml/kg]). Response, in vivo recovery and area under the curve did not differ noticeably between the laboratories. The normalisation or near normalisation of pre-infusion pathological coagulation tests indicated a good haemostatic efficacy of the tested fibrinogen concentrate, which was also generally well tolerated and not associated with any serious adverse reactions.