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PubMed1996

Aspirin does not increase allogeneic blood transfusion in reoperative coronary artery surgery.

While preoperative aspirin (ASA) therapy does not increase allogeneic transfusion in elective primary coronary artery bypass grafting (CABG) operations, the impact of ASA consumption on transfusion in cardiac operations with greater risk of bleeding has not been investigated. We examined the influence of ASA consumption on mediastinal drainage and allogenic transfusion in 317 patients undergoing reoperative CABG surgery. Patients receiving ASA or ASA containing medications within 7 days preoperatively (n = 215) had similar perioperative characteristics but were older and had smaller red cell volumes than control patients not receiving ASA (n = 102). All patients received aminocaproic acid, but autotransfusion of mediastinal blood or platelet rich plasma, aprotinin, or desmopressin were not used. No significant differences were observed between ASA and control groups with respect to postoperative hematocrit, mediastinal drainage, frequency of reexploration for excessive bleeding, amount of allogeneic packed red blood cell, fresh frozen plasma, platelet concentrate or cryoprecipitate transfusion, or the fraction of patients receiving any allogeneic blood product. There was no difference in mediastinal drainage when stratified by timing of most recent ASA ingestion. Multiple linear regression identified duration of cardiopulmonary bypass (CPB), internal mammary artery harvesting, chronic preoperative steroid therapy and use of an intraaortic balloon pump (IABP) as significant predictors of mediastinal drainage. Logistic regression demonstrated that female gender, prolonged duration of CPB, advanced age, use of IABP, and a negative history of smoking were significant independent predictors of blood product transfusion. There was no significant interaction of preoperative heparin therapy with ASA on transfusion demonstrated by univariate or multivariate analyses. These results indicate that preoperative ASA ingestion is not an important determinant of mediastinal drainage or allogeneic transfusion, even after repeat CABG operations, and that surgical and patient characteristics are more important predictors of these outcomes.

Age Factors↗
PubMed2004

Avoidance of bleeding during surgery in patients receiving anticoagulant and/or antiplatelet therapy: pharmacokinetic and pharmacodynamic considerations.

Perioperative management of chronically anticoagulated patients and/or patients treated with antiplatelet therapy is a complex medical problem. This review considers the pharmacokinetic and pharmacodynamic properties of commonly used antiplatelet and anticoagulant drugs with special emphasis on loss of effects after discontinuation and possible counteracting (or antidote) strategies. These drugs are aspirin (acetylsalicylic acid), ticlopidine/clopidogrel, abciximab, tirofiban and eptifibatide, heparin (unfractionated and low-molecular-weight), warfarin and direct thrombin inhibitors. Since the pharmacological mechanisms of some of these drugs are based on irreversible or slowly reversible effects, their pharmacokinetic profiles are not necessarily predictive for their pharmacodynamic profiles. A close and direct relationship between plasma concentrations and effects is seen only for the glycoprotein (GP) IIb/IIIa inhibitors tirofiban and eptifibatide with a fast off-rate for dissociation from the GPIIb/IIIa receptor, and for direct thrombin inhibitors (hirudin and argatroban). For other compounds, drug concentrations in plasma and pharmacodynamic effects are not closely correlated because of, for example, irreversible binding to their target (aspirin, clopidogrel and abciximab), inhibition of the generation of a subset of clotting factors with differing regeneration and degradation rates (coumarins) or sustained binding to the vascular wall (heparins). Surgery in patients on anticoagulant and/or antiplatelet therapy may be categorised as: (i) elective versus urgent; and (ii) cardiopulmonary bypass (CPB) versus non-CPB. Monotherapy with clopidogrel or aspirin need not be discontinued in elective non-CPB surgery, and temporary discontinuation of warfarin should be accompanied by preoperative intravenous heparin only in selected high-risk patients. Vitamin K as an antidote for warfarin should only be used subcutaneously and solely in urgent/emergency surgery. In elective surgery requiring CPB (coronary artery bypass grafting), it is recommended to discontinue aspirin 7 days preoperatively in patients with a low risk profile. Patients requiring urgent CPB surgery (e.g. after failure of a percutaneous coronary angioplasty with or without coronary stent deployment) are usually pretreated with several antiplatelet agents (e.g. aspirin and clopidogrel, together with a GPIIb/IIIa inhibitor) together with unfractionated or low-molecular-weight heparin. With judicious planning, urgent/emergency cardiac surgery can be safely performed on these patients. Delaying surgery (e.g. for 12 hours in patients treated with abciximab) should be considered if possible. Standard heparin doses should be given to achieve optimal anticoagulation for CPB. Prophylactic use of aprotinin (intra- and/or postoperatively), aminocaproic acid or tranexamic acid should be considered. Early (in the operating theatre prior to chest closure) and judicious use of replacement blood products (platelets) should be commenced when clinically indicated.

Anticoagulants↗
PubMed1995

Roles of individual kringle domains in the functioning of positive and negative effectors of human plasminogen activation.

In order to identify the individual contributions of the kringle (K) domains of human plasminogen (Pg) to the epsilon-aminocaproic acid (EACA) induced stimulation of Pg activation by low-molecular-weight urokinase-type plasminogen activator (LMW-uPA) and inhibition of this same activation by Cl-, we constructed the most conservative recombinant- (r-) Pg mutants possible that would greatly reduce the strength of the EACA binding site in the omega-amino acid binding kringles, [K1Pg] ([D139-->N]r-Pg), [K4Pg] ([D413-->N]r-Pg), and [K5Pg] ([D515--N]r-Pg). In each case, this involved mutation of a critical Asp (to Asn) within these three kringle domains in intact Pg. The three r-mutants were expressed in r-baculovirus-infected lepidopteran insect (Trichoplusia ni) cells. In the presence of Cl-, the positive activation effector, EACA, first stimulated and then inhibited the LMW-uPA-catalyzed initial activation of wild-type (wt) r-[Glu1]Pg and, to a lesser extent, the [K5Pg] mutant, [D518-->N/Glu1]r-Pg. The concentration of EACA that produced 50% stimulation of activation (C50) occurred at 3.3 mM for wtr-[Glu1]Pg and at 0.7 mM for [D518-->N/Glu1]r-Pg. Subsequent inhibition by EACA occurred with a C50 of approximately 15 mM and is likely due to inhibition of the amidolytic activity of plasmin generated during the activation. Similar initial activation rates of both [D139-->N]r-Pg and [D413N]r-Pg did not display this initial EACA-mediated stimulatory phase but did undergo ultimate inhibition with a C50 for this process that was similar to wtr-[Glu1]Pg and [D518-->N/Glu1]r-Pg.(ABSTRACT TRUNCATED AT 250 WORDS)

Aminocaproates↗
PubMed2006

The kaolin-activated Thrombelastograph predicts bleeding after cardiac surgery.

OBJECTIVE: The objective of this study was to determine the relationship of the kaolin-activated Thrombelastograph (TEG) with postoperative bleeding and laboratory tests of coagulation in the setting of cardiac surgery with the routine use of -aminocaproic acid. DESIGN: Prospective observational study. SETTING: An adult heart center at a tertiary referral, university hospital. PARTICIPANTS: Thirty adult cardiac surgical patients. INTERVENTIONS: The kaolin-activated TEG, platelet counts, prothrombin times, activated partial thromboplastin times, and fibrinogen levels were measured before induction of anesthesia, during cardiopulmonary bypass, and on arrival in the intensive care unit. Mediastinal and thoracostomy drainage were measured every hour for 4 hours after arrival in the intensive care unit. MEASUREMENTS AND MAIN RESULTS: Correlation and multivariate linear regression modeling were used to describe relationships among coagulation tests, TEG parameters, and early postoperative bleeding. The TEG maximum amplitude (MA) parameter correlated well with postoperative bleeding (r = -0.6, p = 0.0018), more so than platelet count (r = -0.45, p = 0.02), fibrinogen level (r = -0.40, p = 0.06), or prothrombin time (r = 0.43, p = 0.02). The receiver operating characteristic curve c-index describing MA as a predictor for postoperative bleeding is 0.78. Abnormalities in all the laboratory test results were associated with an abnormal MA. CONCLUSIONS: In conclusion, the kaolin-activated TEG is associated with early coagulopathic bleeding. It may reflect the severity of a global coagulopathy affecting both platelets and coagulation factors and be a guide to incremental prohemostatic therapy in this setting.

Aged↗
PubMed1989

Metabolic behavior of cell surface biotinylated proteins.

The turnover of proteins on the surface of cultured mammalian cells was measured by a new approach. Reactive free amino or sulfhydryl groups on surface-accessible proteins were derivatized with biotinyl reagents and the proteins solubilized from culture dishes with detergent. Solubilized, biotinylated proteins were then adsorbed onto streptavidin-agarose, released with sodium dodecyl sulfate and mercaptoethanol, and separated on polyacrylamide gels. Biotin-epsilon-aminocaproic acid N-hydroxysuccinimide ester (BNHS) or N-biotinoyl-N'-(maleimidohexanoyl)hydrazine (BM) were the derivatizing agents. Only 10-12 bands were adsorbed onto streptavidin-agarose from undervatized cells or from derivatized cells treated with free avidin at 4 degrees C. Two-dimensional isoelectric focusing-sodium dodecyl sulfate gel electrophoresis resolved greater than 100 BNHS-derivatized proteins and greater than 40 BM-derivatized proteins. There appeared to be little overlap between the two groups of derivatized proteins. Short-term pulse-chase studies showed an accumulation of label into both groups of biotinylated proteins up until 1-2 h of chase and a rapid decrease over the next 1-5 h. Delayed appearance of labeled protein at the cell surface was attributed to transit time from site of synthesis. The unexpected and unexplained rapid disappearance of pulse-labeled proteins from the cell surface was invariant for all two-dimensionally resolved proteins and was sensitive to temperature reduction to 18 degrees C. Long-term pulse-chase experiments beginning 4-8 h after the initiation of chase showed the disappearance of derivatized proteins to be a simple first-order process having a half-life of 115 h in the case of BNHS-derivatized proteins and 30 h in the case of BM-derivatized proteins.(ABSTRACT TRUNCATED AT 250 WORDS)

Aminocaproates↗
PubMed1995

Determinants of lipoprotein(a) assembly: a study of wild-type and mutant apolipoprotein(a) phenotypes isolated from human and rhesus monkey lipoprotein(a) under mild reductive conditions.

We previously observed that rhesus monkey lipoprotein(a) [Lp(a)], is lysine-binding defective (Lys-) and attributed this deficiency to the presence of Arg72 in the lysine-binding site (LBS) of kringle IV-10 of apolipoprotein(a) [apo(a)] [Scanu, A.M., Miles, L.A., Fless, G.M., Pfaffinger, D., Eisenbart, J., Jackson, E., Hoover-Plow, J.L., Brunck, T., & Plow, E.F. (1993) J. Clin. Invest. 91, 283-291]. We also identified human mutants having Arg72 instead of Trp72 (wild type) in the LBS of kringle IV-10 [Scanu, A M., Pfaffinger, D., lEE, J.C., & Hinman, J. (1994) Biochim. Biophys. Acta 1227, 41-45]. Unique to the human mutant phenotype were the very low levels of plasma Lp(a), suggesting structural differences between human and rhesus apo(a) and a possible divergent mode of Lp(a) assembly. In order to explore the possibility of a relationship between apo(a) LBS and Lp(a) assembly, we developed a novel method for isolating wild-type and mutant apo(a) phenotypes in a free form by subjecting each parent Lp(a) to mild reductive conditions using 2 mM dithioerythritol (DTE) and 100 mM of the lysine analogue, epsilon-aminocaproic acid (EACA). The application of this method to the study of wild-type and mutant apo(a) species showed that regardless of the source of Lp(a), i.e., positive lysine binding (Lys+) or negative lysine binding (Lys-), all of the isolated free apo(a)s were Lys+. Moreover, incubation of free apo(a)s with their autologous human or rhesus low-density lipoproteins (LDL) generated Lp(a) complexes which were structurally and functionally indistinguishable from their parent native Lp(a). In each instance, the reassembly process was inhibited by the presence of either EACA or proline. These two reagents had a minimal effect on either Lp(a) or reassembled Lp(a) [RLp(a)]. Free apo(a) bound to apoB100 of very low density lipoproteins (VLDL) to form a triglyceride-rich Lp(a). These results show that (1) both human and rhesus Lp(a) are amenable to dissassembly and reassembly, (2) the presence of Arg72 in the LBS of kringle IV-10 is not involved, at least directly, in this process, (3) its cleavage from apoB100 opens up in apo(a) a domain that is both EACA and proline sensitive and involved in Lp(a) assembly, and (4) the apoB100 of VLDL is also competent to bind apo(a). Our observations also suggest that the difference in plasma Lp(a) levels between the rhesus and the human mutant, both having Arg72 in the LBS of apo(a) kringle IV-10, is not related to the assembly process, but more likely to a divergence in production/secretion rates between the two apo(a) phenotypes.

Aminocaproates↗
PubMed1986

Rebleeding after traumatic hyphema.

We reviewed the medical records of 175 patients who were admitted between 1977 and 1984 with a diagnosis of traumatic hyphema to define the incidence of operative intervention for the treatment of complications related to rebleeding. Of the 156 patients admitted with primary hyphemas, 25 (16%) rebled during hospitalization. Seven of these 25 in-hospital rebleeds required surgical intervention. Nineteen other patients were admitted with ocular histories and examinations strongly suggestive of rebleeding prior to admission (secondary hyphema--presumed preadmission rebleed). Seven of these 19 eyes underwent surgery. Of the 175 eyes studied, only one eye that did not rebleed underwent surgery during the initial hospitalization. Fourteen (32%) of 44 eyes that rebled underwent operative intervention. Nine of these 14 patients were operated on under general anesthesia. Potential benefits of newer hyphema treatments, such as epsilon-aminocaproic acid, designed to prevent rebleeding should be weighed against not only the ocular risks of rebleeding but also the risks of general anesthesia.

Adolescent↗
PubMed1998

Reexploration for hemorrhage following coronary artery bypass grafting: incidence and risk factors. Northern New England Cardiovascular Disease Study Group.

OBJECTIVE: To assess mortality and risk factors associated with reexploration for hemorrhage in patients undergoing coronary artery bypass grafting (CABG). DESIGN: Regional cohort study. Patient characteristics, treatment variables, and outcome measures were collected prospectively. SETTING: All 5 centers performing cardiac surgery in Maine, New Hampshire, and Vermont. PATIENTS: A consecutive cohort of 8586 patients undergoing isolated CABG between 1992 and 1995. MAIN OUTCOME MEASURES: Postoperative hemorrhage leading to reexploration, in-hospital mortality, and length of stay. RESULTS: A total of 305 patients (3.6%) underwent reexploration for bleeding. In these patients, in-hospital mortality was nearly 3 times higher (9.5% vs 3.3% for patients not requiring reoperation, P<.001) and average length of stay from surgery to discharge was significantly longer (14.5 days vs 8.6 days, P<.001). High rates of reexploration for hemorrhage were observed in patients with prolonged (> 150 minutes) cardiopulmonary bypass (39 [11.1%] of 351) and in those requiring an intra-aortic balloon pump intraoperatively (12 [8%] of 139). In multivariate analysis, older age, smaller body surface area, prolonged cardiopulmonary bypass, and number of distal anastomoses were associated with increased bleeding risks. The use of thrombolytic therapy within 48 hours of surgery was weakly but not significantly associated with the need for reexploration. Factors not significantly associated with reexploration included patient sex, preoperative ejection fraction, surgical priority, history of liver disease, myocardial infarction, prior CABG, renal failure, and diabetes mellitus. CONCLUSIONS: Hemorrhage requiring reexploration after CABG is associated with markedly increased mortality and length of stay. Patients predicted to have increased risks of bleeding may benefit from prophylactic use of aprotinin, aminocaproic acid, or other agents shown to reduce hemorrhage.

Aged↗
PubMed1996

Effects of fibinolysis on neurite growth from dorsal root ganglia cultured in two- and three-dimensional fibrin gels.

The mechanism of neurite penetration of three-dimensional fibrin matrices was investigated by culturing embryonic chick dorsal root ganglia (DRGs) within fibrin gels, upon fibrin gels, and upon laminin. The length of neurites within three-dimensional matrices of fibrin was decreased in a concentration-dependent manner by agents that inhibited plasmin, e.g. aprotinin, or that inhibited plasminogen activation, e.g., epsilon-aminocaproic acid (EACA), or plasminogen antiserum. In contrast, such agents increased the length of neurites growing out from DRGs cultured upon two-dimensional substrates of fibrin and had no effect on the length of neurites growing out from DRGs cultured upon laminin. Visualization of neurites within three-dimensional fibrin matrices demonstrated that the distance between fibrin strands was much smaller than the diameter of neurites. All these data were consistent with the hypothesis that fibrinolysis localized to the region of the neurite tip is an important mechanism for neurite penetration of a physical barrier of fibrin strands arranged in a three-dimensional matrix.

Animals↗
PubMed2004

Near-fatal uterine hemorrhage during induction chemotherapy for acute myeloid leukemia: a case report of bilateral uterine artery embolization.

Severe transfusion-dependent uterine hemorrhage is a relatively uncommon complication of induction chemotherapy for acute myeloid leukemia (AML). Even less common is the failure of systemic conjugated estrogens in this setting. We report a case of life-threatening uterine hemorrhage in a 38-year-old woman in the setting of transfusion-refractory thrombocytopenia after completing induction chemotherapy for AML. She experienced dramatic breakthrough uterine hemorrhage despite multiple platelet transfusions, conjugated estrogens, recombinant factor VIIa, epsilon-aminocaproic acid, and intracavitary thrombin-soaked gauze tamponade. At the point of near-exsanguination in the setting of hypotension, hematocrit of 14%, and a platelet count of 3,000/microL, she underwent bilateral uterine artery embolization which proved immediately successful. We review the literature and indications for this procedure in the oncologic patient care setting.

Adult↗
PubMed1990

Hemostasis in malignancy.

Hemostatic abnormalities are present in a majority of patients with metastatic cancer. These abnormalities can be categorized as 1) increased platelet aggregation and activation, 2) abnormal activation of coagulation cascade, 3) release of plasminogen activator, and 4) decreased hepatic synthesis of anticoagulant proteins like Protein C and antithrombin III. The abnormal activation of coagulation cascade is mediated through release of Tissue Factor, Factor X activators, and other miscellaneous procoagulants from the plasma membrane vesicles of tumor cells. Macrophages of a tumor-bearing host also produce increased amounts of Tissue Factor. Production of Factor X activators and macrophage Tissue Factor is decreased by warfarin. The ability of the tumor cells to produce platelet-aggregating activity and plasminogen activator parallels their metastatic potential in animal and experimental systems. These studies also show that antiplatelet agents and antibodies against plasminogen activator can suppress the metastatic process. One or more laboratory abnormalities of hemostasis can be shown in up to 95% of patients with metastatic cancer. These abnormalities, however, are unable to predict subsequent development of thromboembolic or hemorrhagic complications. Clinical complications occur in 9-15% of the patients in the form of thrombotic or hemorrhagic disorders. The therapy of tumor-related coagulopathy should be guided by its clinical expression. Subclinical DIC should not be treated. Coumadin is generally ineffective for therapy of thrombosis in cancer patients. There is no consensus regarding the use of heparin in acute promyelocytic leukemia (APL). The defibrination in APL may be from disseminated intravascular coagulation as well as systemic fibrinolysis, as shown by decreased alpha 2 antiplasmin levels. In such cases, epsilon aminocaproic acid plus heparin therapy may be of benefit.

Antithrombin III↗
PubMed1976

The effect of premarin on blood loss attending open heart surgery.

Premarin was administered prophylactically to every other patient in a series of 148 consecutive cases of open intracardiac surgery. Of these, 132 patients were matched to analyse the results of Premarin administration and postoperative blood loss. There were 67 patients who were given Premarin and 65 who did not receive this drug; both groups were identical in respect of age and sex. Matching was undertaken according to history of previous cardiac operations and anticoagulation, type of valve surgery or repair of congenital anomaly, duration of perfusion, platelet count and the use of fresh blood and epsilon-aminocaproic acid in the postoperative period. The prophylactic use of Premarin was not associated with a reduction in postoperative bleeding.

Adolescent↗
PubMed1990

Estimation of biotinylated lectin by isoelectric focusing.

Concanavalin A (Con A) was biotinylated to various degrees using N-biotinyl-omega-aminocaproic-acid-N-hydroxy succinimide ester as the biotinylation reagent, and then analyzed by isoelectric focusing using PhastGel IEF 3-9. The isoelectric points of biotinylated ConAs were found to decrease with increasing concentration of the biotinylation reagent. Analysis by isoelectric focusing followed by dot blotting clearly indicated that the biotinylated ConA with an isoelectric point lower than that of the original ConA by 2.2 +/- 0.6 had the strongest binding activity for ovalbumin.

Biotin↗
PubMed1996

Quantitation of glycated hemoglobins in human adult blood by capillary isoelectric focusing.

A precise and reproducible method for assessment of glycated hemoglobin in human adult red blood cells is reported, based on capillary isoelectric focusing (IEF). In order to obtain baseline resolution between adult hemoglobin (Hb A) and its glycated form (Hb A1c), two species which differ by minute delta pI values, < 0.03 pH units, the following procedure was adopted: the focusing mixture consisted of 5% Ampholine, pH 6-8, 0.5% Pharmalyte, pH 3-10, 3% short-chain liquid polyacrylamide and an equimolar mixture of two "separators", 0.33 M beta-alanine and 0.33 M 6-aminocaproic acid. The last two compounds flatten the pH gradient in the pI region of the two Hbs, thus allowing full separation. Additionally, the Hb samples, instead of being pulse-loaded, are uniformly distributed in the background electrolyte. A longer capillary life-time is obtained if all nonbuffering ions are eliminated; thus, as catholyte, 50 mM Lys (pH 9.7) is utilized and as anolyte 50 mM acetic acid (pH 3.5) is adopted. The percentages of Hb A1c, as obtained by capillary IEF, are in good agreement (+/- 6%) with data obtained by one of the standard zone electrophoretic methods in clinical chemistry, i.e., the Helena REP Glyco gel system.

Acrylic Resins↗
PubMed1994

Healing of large segmental defects in rat femurs is aided by RhBMP-2 in PLGA matrix.

Recombinant human bone morphogenetic protein-2 (rhBMP-2) can be used to enhance the repair of congenital or acquired bone pathologies when formulated in the appropriate carrier. Poly [D,L-(lactide-co-glycolide)] (PLGA) has been shown to be an effective carrier of rhBMP-2. We investigated several particle sizes PLGA and several doses of rhBMP-2 in a rat orthotopic model. We also investigated the effects of a fibrinolytic inhibitory agent, epsilon aminocaproic acid (EACA), on the healing response. Our data indicate that higher doses of rhBMP-2 resulted in increased failure torque (408 +/- 70 N-mm or 60% of the intact value) and higher incidence of union (100%). The induced bone in femurs treated with the smaller particle size PLGA achieved the greatest torsional stiffness and strength. The presence of rhBMP-2 was necessary for new bone to form, but the presence of EACA did not change these results; the use of the PLGA carrier appeared to increase bone strength and stiffness. In fact, with higher doses of rhBMP-2 in PLGA, the stiffness of the new bone was equal to that of intact controls (64 +/- 20 N-mm/deg [intact femurs] versus 45 +/- 10 N-mm/degree [medium dose in small PLGA], 61 +/- 17 N-mm/degree [high dose in small PLGA], and 36 +/- 11 N-mm/degree [medium dose in large PLGA]; P > .05). In conclusion, PLGA implanted with rhBMP-2 effectively aided in healing large segmental defects in rat femurs.

Animals↗
PubMed2003

A fibrin-based arterial media equivalent.

We report here, with respect to collagen production and the mechanical properties of a fibrin-based media equivalent (ME), on our efforts to optimize the culture conditions of neonatal SMCs entrapped in tubular fibrin gels. We examined several factors, including the concentration of fibrinolysis inhibitor, the cell source and initial number, the addition of TGF-beta and insulin to the culture medium, and the time in culture. We found that varying the concentration of epsilon-aminocaproic acid (ACA), an inhibitor of fibrinolysis, did not affect the collagen production, but that lower concentrations resulted in a compromised physical integrity of the ME. While use of neonatal SMCs yielded superior results over adult SMCs, a higher initial cell number did not improve results. The addition of 1 ng/mL of TGF-beta to the medium increased the collagen content fourfold and the ultimate tensile strength (UTS) and modulus approximately tenfold after 3 weeks, while the addition of both TGF-beta and insulin improved collagen content sixfold and UTS and modulus almost 20-fold. Additional TGF-beta (5 ng/mL) did not improve any of the properties measured, but additional time in culture did. Samples incubated for 6 weeks with TGF-beta and insulin contained about seven times the amount of collagen and had a three-times higher UTS and modulus than did samples incubated for only 3 weeks. When compared to collagen MEs, the fibrin MEs compacted to a greater extent and were both stronger and stiffer when cultured under the same conditions, having after 6 weeks a tensile modulus and ultimate tensile strength similar to those of rat abdominal aorta.

Animals↗
PubMed2005

Hydrolytic degradation behavior of biodegradable polyetheresteramide-based polyurethane copolymers.

In this article, a new kind of biodegradable polyetheresteramide-based polyurethane (PEEA-U) copolymers were prepared by the melt polycondensation method from epsilon-caprolactone, 6-aminocaproic acid, poly(ethylene glycol), and toluene diisocyanate. The water absorption of PEEA-U was affected strongly by the reaction time and the content of chain extender; and the hydrolytic degradation behavior of the copolymers was mainly determined by the reaction time, chain extender content, and the pH value of the degradation medium. Also, DSC, (1)H-NMR, and inherent viscosity were used to characterize the degradation behavior of the copolymers.

Absorbable Implants↗