Label-free peptide quantification coupled with in silico mapping of proteases for identification of potential serum biomarkers in gastric adenocarcinoma patients.

OBJECTIVES: We aimed to identify serum level variations in protein-derived peptides between patients diagnosed with gastric adenocarcinoma (GAC) and non-cancer persons (control) to detect the activity changes of proteases and explore the auxiliary diagnostic value in the context of GAC physiopathology. METHODS: The label-free quantitative peptidome approach was applied to identify variants in serum levels of peptides that can differentiate GAC patients from the control group. Peptide sequences were submitted against Proteasix tool predicting proteases potentially involved in their generation. The activity change of proteases was subsequently estimated based on the peptides with significantly altered relative abundance. In turn, activity change prediction of proteases was correlated with relevant protease expression data from the literature. RESULTS: A total of 191 peptide sequences generated by the cleavage of 36 precursor proteins were identified. Using the label-free quantification approach, 33 peptides were differentially quantified (adjusted fold change ≥ 1.5 and p-value < 0.05) in which 19 were up-regulated and 14 were down-regulated in GAC samples. Of these peptides, fibrinopeptide A was significantly decreased and its phosphorylated form ADpSGEGDFLAEGGGVR was upregulated in GAC samples. Activity change prediction yielded 10 proteases including 6 Matrix Metalloproteinases (MMPs), Thrombin, Plasmin, and kallikreins 4 and 14. Among predicted proteases in our analysis, MMP-7 was presented as a more promising biomarker associated with useful assays of clinical practice for GAC diagnosis. CONCLUSION: Our experimental results demonstrate that the serum levels of peptides were significantly differentiated in GAC physiopathology. The hypotheses built on protease regulation could be used for further investigations to measure proteases and their activity levels that have been poorly studied for GAC diagnosis.

Histidine-rich Glycoprotein Could Be an Early Predictor of Vasospasm after Aneurysmal Subarachnoid Hemorrhage.

Cerebral vasospasm (CVS) is a major contributor to the high morbidity and mortality of aneurysmal subarachnoid hemorrhage (aSAH) patients. We measured histidine-rich glycoprotein (HRG), a new biomarker of aSAH, in cerebrospinal fluid (CSF) to investigate whether HRG might be an early predictor of CVS. A total of seven controls and 14 aSAH patients (8 males, 6 females aged 53.4±15.4 years) were enrolled, and serial CSF and serum samples were taken. We allocated these samples to three phases (T1-T3) and measured HRG, interleukin (IL)-6, fibrinopeptide A (FpA), and 8-hydroxy-2'-deoxyguanosine (8OHdG) in the CSF, and the HRG in serum. We also examined the release of HRG in rat blood incubated in artificial CSF. In contrast to the other biomarkers examined, the change in the CSF HRG concentration was significantly different between the nonspasm and spasm groups (p<0.01). The rat blood/CSF model revealed a time course similar to that of the human CSF samples in the non-spasm group. HRG thus appears to have the potential to become an early predictor of CVS. In addition, the interaction of HRG with IL-6, FpA, and 8OHdG may form the pathology of CVS.

Serum complement C3f and fibrinopeptide A are potential novel diagnostic biomarkers for non-alcoholic fatty liver disease: a study in Qingdao Twins.

AIMS: To compare the different serum peptidome patterns between twins with and without non-alcoholic fatty liver disease (NAFLD) in order to help understand the pathogenesis of NAFLD and to identify potential diagnostic and therapeutic targets. METHODS: The peptidomics patterns of 63 cases with NAFLD were compared with their twin healthy controls in Qingdao, China. Peptides between 800 Da and 3,500 Da were captured and concentrated using C18 reversed-phase columns, followed by MALDI-TOF mass spectrometry. The sequences of peptides associated with NAFLD were further identified by MALDI-TOF-TOF. Further validation studies were conducted. One hundred additional serum samples were detected by commercially available ELISA kits to calculate the concentrations of complement C3f and fibrinopeptide A, respectively. The differences of these two peptides in the NAFLD and control groups were compared using SPSS 17.0, respectively. RESULTS: Compared with healthy controls, eleven peaks (861.1, 877.07, 904.5, 1206.57, 1350.64, 1518.7, 1690.9, 1777.94, 2931.29, 3190.4, 3261.4) were up-regulated and 7 peaks (942.44, 1020.47, 1060.06, 1211.7, 1263.63, 1449.76, 2768.3) were down-regulated in the NAFLD group. Two peptides derived from complement C3f and fibrinopeptide A, respectively, had the highest ROC values indistinguishing NAFLD cases from their normal controls. In the validation group, the concentrations of complement C3f and fibrinopeptide A (1466.929 ± 78.306 pg/ml, 4.189 ± 0.326 ng/ml, respevtively) in NAFLD group was higher than in control group (complement C3f 1159.357 ± 99.624 pg/ml, FPA 3.039 ± 0.483 ng/ml; P<0.05). CONCLUSIONS: In this study, we established apeptidomics pattern that could help distinguish NAFLD patients from their twin controls. The differently-regulated peptides identified in our study may be potential diagnostic markers or therapeutic targets for NAFLD.

Development and fit-for-purpose validation of a LC-MS/MS assay for fibrinogen peptide A quantitation in human plasma.

BACKGROUND: Fibrinopeptide A (FPA) is a plasma peptide, formed by the action of thrombin on fibrinogen during clog formation. FPA represents a direct indicator of thrombin activity and could potentially be used as a biomarker for anti-thrombotic therapy development. Results/Methodology: A LC-MS/MS assay with a high throughput solid phase extraction procedure was developed and validated to measure FPA in plasma. The lower limit-of-quantitation (LLOQ) of this assay was determined to be 0.16 nM. The inter- and intra-day%CV was <15%. Freeze-thaw stability of FPA was ±30% up to 3 cycles and linear response of FPA was observed for plasma dilution up to 16-fold. CONCLUSION: The assay was validated and the biological variability of FPA in plasma was established (1-30 nM).

Mass spectrum analysis of serum biomarker proteins from patients with schizophrenia.

Diagnosis of schizophrenia does not have a clear objective test at present, so we aimed to identify the potential biomarkers for the diagnosis of schizophrenia by comparison of serum protein profiling between first-episode schizophrenia patients and healthy controls. The combination of a magnetic bead separation system with matrix-assisted laser desorption/ionization time-of-flight tandem mass spectrometry (MALDI-TOF/TOF-MS) was used to analyze the serum protein spectra of 286 first-episode patients with schizophrenia, 41 chronic disease patients and 304 healthy controls. FlexAnlysis 3.0 and ClinProTools(TM) 2.1 software was used to establish a diagnostic model for schizophrenia. The results demonstrated that 10 fragmented peptides demonstrated an optimal discriminatory performance. Among these fragmented peptides, the peptide with m/z 1206.58 was identified as a fragment of fibrinopeptide A. Receiver operating characteristic analysis for m/z 1206.58 showed that the area under the curve was 0.981 for schizophrenia vs healthy controls, and 0.999 for schizophrenia vs other chronic disease controls. From our result, we consider that the analysis of serum protein spectrum using the magnetic bead separation system and MALDI-TOF/TOF-MS is an objective diagnostic tool. We conclude that fibrinopeptide A has the potential to be a biomarker for diagnosis of schizophrenia. This protein may also help to elucidate schizophrenia disease pathogenesis.

A prognostic biomarker for gastric cancer with lymph node metastases.

Gastric cancer is one of the leading causes of tumor-related deaths in China. The tumor, node, metastasis (TNM) classification system is useful for predicting clinical prognosis of patients with gastric cancer. However, determining the presence of lymph node involvement in the early stages of gastric cancer is difficult without biopsy. Therefore, it is necessary to identify novel serum biomarkers for TNM cancer staging and prognostic follow-up. In this study, we have reported fibrinopeptide-A (FPA) with alanine truncation at the N-terminal as a novel biomarker to differentiate gastric cancer with and without lymph node metastases. We analyzed 369 individual serum samples including gastric cancer patients without lymph node metastases (n = 33), gastric cancer patients with lymph node metastases (n = 157; confirmed by pathology), and age- and sex-matched healthy individuals (n = 179). The data showed that 85.4% of patients with lymph node metastases were positive for FPA with alanine truncation at the N-terminal (degAla-FPA, 1,465.63 Da), as determined by tandem mass spectrometry (MS). Using degAla-FPA as the biomarker, the sensitivity was 85.4% for gastric cancer patients with lymph node metastases, and the specificity was 100% for gastric cancer patients without lymph node metastases. The high sensitivity and specificity achieved with serum degAla-FPA levels indicated that MS technology could facilitate the discovery of a novel and quantitative prognostic biomarker for gastric cancer with lymph node involvement.

[A role of D-dimer and fibrinopeptide A in diagnosis of a hemostasis system disorders].

The investigations, concerning detection of the hemostasis system activation, were done in 26 patients, suffering various critical morbid states (an acute pancreatitis). The contents of products of the enzymes lysis of coagulation system and fibrinolytic system constitute one of the most precise indices. Fibrinopeptid A (FpA) is considered one of the most secure indices, confirming intravascular thrombin formation, and D-dimer--of a fibrin formation. In the patients examined a trustworthy increase of a D-dimer and FpA contents was registered, witnessing the hemostasis system activation in an acute pancreatitis as well as an excessive formation and lysis of fibrin. D-dimer and FpA contents in a plasma constitutes an important diagnostic index, its determination secures the possibility of early diagnosis and control of a hemostasis system disorders.

The application of atmospheric pressure matrix-assisted laser desorption/ionization to the analysis of long-term cryopreserved serum peptidome.

Although most time-of-flight (TOF) mass spectrometers come equipped with vacuum matrix-assisted laser desorption/ionization (MALDI) sources, the atmospheric pressure MALDI (API-MALDI) source is an attractive option because of its ability to be coupled to a wide range of analyzers. This article describes the use of an API-MALDI source coupled to a TOF mass spectrometer for evaluation of the effects of medium- and long-term storage on peptidomic profiles of cryopreserved serum samples from healthy women. Peptides were purified using superparamagnetic beads either from fresh sera or after serum storage at -80°C for 18 months or at -20°C for 8 years. Data were preprocessed using newly developed bioinformatic tools and then were subjected to statistical analysis and class prediction. The analyses showed a dramatic effect of storage on the abundance of several peptides such as fibrinopeptides A and B, complement fractions, bradykinin, and clusterin, indicated by other authors as disease biomarkers. Most of these results were confirmed by shadow clustering analysis, able to classify each sample in the correct group. In addition to demonstrating the suitability of the API-MALDI technique for peptidome profiling studies, our data are of relevance for retrospective studies that involve frozen sera stored for many years in biobanks.

A label-free sensing method for phosphopeptides using two-layer gold nanoparticle-based localized surface plasma resonance spectroscopy.

In this study, a new type of localized surface plasmon resonance (LSPR) sensing substrate for phosphopeptides was explored. It has been known that LSPR response for target species is larger in the near-infrared region (NIR) than in the visible region of the electromagnetic spectrum. Several types of noble metal nanoparticles (NPs) with NIR absorption capacities have been previously demonstrated as effective LSPR-sensing nanoprobes. Herein, we demonstrate a straightforward approach with improved sensitivity by simply using layer-by-layer (LBL) spherical Au NPs self-assembled on glass slides as the LSPR-sensing substrates that are responsive in the NIR region of the electromagnetic spectrum. The modified glass slide acquired an LSPR absorption band in the NIR, which resulted from the dipole-dipole interactions between Au NPs. To enable the chip to sense phosphopeptides, the surface of the glass chip was spin-coated with thin titania film (TiO(2)-Glass@Au NPs). Absorption spectrophotometry was employed as a detection tool. Tryptic digest of α-casein was used as a model sample. The feasibility of using the new LSPR approach for detecting a potential risk factor leading to cancers (i.e., phosphorylated fibrinopeptide A) directly from human serum samples was demonstrated. Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) was used to confirm the results.

Different expression of fibrinopeptide A and related fragments in serum of type 1 diabetic patients with nephropathy.

Type 1 diabetes (insulin-dependent diabetes mellitus, IDDM) is an autoimmune disease affecting about 0.12% of the world's population. Diabetic nephropathy (DN) is a major long-term complication of both types of diabetes and retains a high human, social and economic cost. Thus, the identification of markers for the early detection of DN represents a relevant target of diabetic research. The present work is a pilot study focused on proteomic analysis of serum of controls (n=9), IDDM patients (n=10) and DN patients (n=4) by the ClinProt profiling technology based on mass spectrometry. This approach allowed to identify a pattern of peptides able to differentiate the studied populations with sensitivity and specificity close to 100%. Variance of the results allowed to estimate the sample size needed to keep the expected False Discovery Rate low. Moreover, three peptides differentially expressed in the serum of patients as compared to controls were identified by LC-ESI MS/MS as the whole fibrinopeptide A peptide and two of its fragments, respectively. The two fragments were under-expressed in diabetic patients, while Fibrinopeptide A was over-expressed, suggesting that anomalous turnover of Fibrinopeptide A could be involved in the pathogenesis of DN.

Iron oxide/tantalum oxide core-shell magnetic nanoparticle-based microwave-assisted extraction for phosphopeptide enrichment from complex samples for MALDI MS analysis.

A new type of metal-oxide-coated magnetic nanoparticles (NPs)--tantalum-oxide-coated magnetic iron oxide (Fe3O4@Ta2O5) NPs--which are used as affinity probes for selectively trapping phosphopeptides from complex samples, is demonstrated in this study. In this approach, phosphopeptide enrichment was achieved by incubating the NPs with sample solutions under microwave heating within 1 min. The NP-target species conjugates were readily isolated from samples by magnetic separation followed by matrix-assisted laser desorption/ionization (MALDI) mass spectrometric analysis. When using human serum as the sample, phosphorylated fibrinopeptide-A-derived ions are the only ions observed in the MALDI mass spectra after enrichment by the Fe3O4@Ta2O5 NPs. Furthermore, only phosphopeptides appear in the MALDI mass spectra after using the affinity probes to selectively trap target species from the tryptic digest of a cell lysate and milk sample. The results demonstrated that the Fe3O4@Ta2O5 NPs have the capability of selectively trapping phosphorylated peptides from complex samples. The detection limit of this approach for a phosphopeptide (FQpSEEQQQTEDELQDK) was approximately 10 fmol.

Thrombin induces broad spectrum proteolysis in human serum samples.

BACKGROUND: During clotting, a thrombin cleaves fibrinogen releasing fibrinopeptide A (FPA). FPA is easily identified in serum using matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry (MS). Using MALDI-TOF MS, we observed multiple, progressively shorter fragments of serum FPA. Following ambient incubation of serum, variations in the content of FPA fragments occur over time. Denaturation of a thrombin by heating the serum sample appears to minimize this variation. These observations suggest that intrinsic proteolytic and peptidolytic activity is elevated in serum and perhaps originates from the coagulation cascade enzymes themselves, especially a thrombin. METHODS: Extrinsic addition of a thrombin to a subset (3-30 kDa) of plasma proteins was carried out to induce proteolysis and to examine the resultant peptides to reveal a thrombin susceptible parent proteins. One of these identified proteins, hemopexin, was directly digested by a thrombin and the peptides examined to confirm the observations from the initial plasma protein digestion. RESULTS: Extrinsic addition of a thrombin to a subset (3-30 kDa) of plasma proteins results in wide-spread digestion of proteins unrelated to coagulation, revealing a substrate range encompassing more than fibrinogen. Direct digestion of one of these proteins, hemopexin, by a thrombin confirms these observations. CONCLUSIONS: The resulting peptides indicate broad tolerance beyond the consensus R-G cleavage site of fibrinogen; in fact, there appears to be no bias for the amino acid following the R/K residue. These data support our hypothesis that the enzymatic activities inherent to coagulation, or at least to thrombin, contribute to destabilization of the protein and peptide content of serum.

Biological variation in tests of hemostasis.

The two components of biological variability are interindividual variability, which is the variability due to the heterogeneity of physiologic influences among subjects, and intraindividual variability, which is due to the variability in the same individual over time. Analysis of biological variation is crucial for estimating the critical difference, which corresponds with a threshold suggestive of a statistically significant difference between two consecutive results of a laboratory parameter in the same subject and is therefore unlikely attributable to casual (random) oscillation of values. Studies on biological variation of tests of hemostasis are outdated, and the published results should be confirmed by using modern, fully automated methods. Biological variation for coagulation screening tests (prothrombin time and activated partial thromboplastin time) is low and comparable with the values registered for hematologic parameters. However, the index of individuality (ratio between intraindividual and interindividual variability) suggests that the usual preoperative screening for coagulation disorders is influenced by the between-subjects variability. Thrombin time is very constant within and between subjects. Proteins such as fibrinogen, clotting factors, and antithrombin show a low biological variability. In contrast, fibrinolytic parameters, such as plasminogen activator inhibitor 1 and fibrinopeptide A, show very high variability, and their interpretation in the clinical setting must take this into consideration.

Cardiopulmonary bypass parameters and hemostatic response to cardiopulmonary bypass in infants versus children.

OBJECTIVE: Because infants have relatively more blood loss (mL/kg) than older children during cardiac surgery involving cardiopulmonary bypass (CPB), the authors compared hemostatic activation between infants and older children undergoing cardiac surgery. DESIGN: Observational study. SETTING: University-affiliated children's hospital. PARTICIPANTS: Twenty-eight children (18 infants <1 year and 10 children >1 year) undergoing cardiac surgery with CPB. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Markers of coagulation and fibrinolysis were evaluated at 9 sample points before, during, and after CPB in the 28 children. Infants had greater chest tube output, longer CPB times, and a larger drop in platelet counts during CPB than children. Active tissue plasminogen activator (tPA) increased during CPB in both groups, with infants showing lower levels than children (p < 0.001). In both groups, active plasminogen activator inhibitor type 1 (PAI-1) first decreased during CPB and then increased above baseline postoperatively. Infants had higher PAI-1 than children near the end of CPB (p = 0.01). Thrombin-antithrombin complex levels increased during and after CPB, with infants showing lower levels only during CPB (p = 0.01). D-dimer and prothrombin activation peptide (F1.2) levels increased in a similar pattern for both groups during and after CPB. The length of aortic cross-clamp time and the level of F1.2 after protamine administration correlated significantly and independently with 12-hour chest tube output. CONCLUSIONS: Compared with children, infants had greater blood loss (mL/kg), greater drop in platelets during CPB, lower active tPA, and higher active PAI-1. Cumulative thrombin generation after CPB, indicated by F1.2 levels, correlated with early blood loss.

Incorporation of fibrin molecules containing fibrinopeptide A alters clot ultrastructure and decreases permeability.

Previous studies have shown that a heterozygous mutation in the fibrinogen Aalpha chain gene, which results in an Aalpha R16C substitution, causes fibrinolytic resistance in the fibrin clot. This mutation prevents thrombin cleavage of fibrinopeptide A from mutant Aalpha R16C chains, but not from wild-type Aalpha chains. However, the mechanism underlying the fibrinolytic resistance is unclear. Therefore, this study investigated the biophysical properties of the mutant fibrin that contribute to fibrinolytic resistance. Fibrin clots made from the mutant fibrinogen incorporated molecules containing fibrinopeptide A into the polymerised clot, which resulted in a 'spiky' clot ultrastructure with barbed fibrin strands. The clots were less stiff than normal fibrin and were cross-linked slower by activated FXIII, but had an increased average fiber diameter, were more dense, had smaller pores and were less permeable. Protein sequencing showed that unclottable fibrinogen remaining in the supernatant consisted entirely of homodimeric Aalpha R16C fibrinogen, whereas both cleaved wild-type alpha chains and uncleaved Aalpha R16C chains were in the fibrin clot. Therefore, fibrinolytic resistance of the mutant clots is probably a result of altered clot ultrastructure caused by the incorporation of fibrin molecules containing fibrinopeptide A, resulting in larger diameter fibers and decreased permeability to fibrinolytic enzymes.

Elevated levels of phosphorylated fibrinogen-alpha-isoforms and differential expression of other post-translationally modified proteins in the plasma of ovarian cancer patients.

We evaluated the differentially expressed proteins in the plasma of ovarian cancer (OVC) patients using 2-D SDS-polyacrylamide gel electrophoresis (SDS-PAGE) with post-translational modification (PTM) specific stains after the removal of six high-abundance proteins. The pooled plasma from patients with stage III or IV OVC was compared to a pooled postmenopausal age-matched control. Several proteins were identified as differentially expressed in the plasma of OVC patients. Among them, the phosphorylated fibrinogen-alpha-chain isoform (containing fibrinopeptide-A) was found to be up-regulated. Previously in our laboratory, phosphorylated fibrinopeptide-A was found to be up-regulated in the low molecular weight fraction of serum derived from OVC patients. We examined the levels of phosphorylated fibrinogen-alpha-chain in each patient that constituted the pooled plasma using Western blot, mass spectrometry (MS), and PTM specific stains. Phosphoprotein bands containing fibrinogen-alpha-chain fragments showed up-regulation in all OVC patients.

Identification and confirmation of increased fibrinopeptide a serum protein levels in gastric cancer sera by magnet bead assisted MALDI-TOF mass spectrometry.

Gastric cancer is the second most common malignancy and prognosis remains dismal. The reasons for the poor prognosis are the lack of sensitive serum markers for early detection and screening of high-risk individuals as well as the limited treatment options in advanced cancer stages. Using MALDI-TOF mass spectrometry after prefractionation of sera with magnet hydrophobic C8 coated beads sera from 14 patients with gastric cancer and 14 healthy controls mass spectra were generated. A peptide fragment was found to be highly elevated in cancer sera and was identified as fibrinopeptide A. To confirm proteome analysis of gastric cancer sera, we then screened a larger series of patients with gastric cancer (n = 99), high-risk individuals (n = 13) and normal controls (n = 111) for fibrinopeptide A serum levels. Interestingly, the mean logarithmic concentrations of serum fibrinopeptide A levels were significantly higher in cancer patients (mean 3.636 +/- 0.3738; p < 0.0001) and high-risk individuals (mean 3.569 +/- 0.4722; p < 0.05) compared to normal controls (mean 3.303 +/- 0.4012). In contrast, we observed no association of fibrinopeptide A levels with tumor stage, tumor location, presence of regional or distant metastasis, and Lauren type of gastric cancer. In conclusion, MALDI-TOF mass spectrometry of prefractionated gastric cancer sera allows the identification of potential biomarkers that may lead to the development of serum based tests for screening of high-risk individuals.

Effects of half-dose aprotinin in off-pump coronary artery bypass grafting.

OBJECTIVE: The effects of half-dose aprotinin in off-pump coronary artery bypass (OPCAB) surgery have not yet been described. The present prospective study was designed to investigate its effects in OPCAB. METHODS: Seventy-six patients were randomized into two groups, receiving aprotinin (1 x 10(6) Kallikrein-inactivating units [KIU] loading dose before surgery and 5 x 10(5) KIU/h during surgery, gross dose: 2.5 x 10(6) KIU, n=36) and saline solution (control, n=40) respectively. Perioperative blood samples were collected. Hematologic and hemostatic parameters including platelet adhesion rate, D-dimer, and fibrinopeptide-A (FPA) were analyzed. Perioperative CKMB release was measured. Volume of blood loss, blood transfusion, and other clinical data were recorded throughout the perioperative period. RESULTS: Postoperative blood loss was significantly reduced in patients treated with aprotinin (2 hours; median [25th-75th]: aprotinin: 90.0 [70.0-125.0] ml, control: 145.0 [70.0-180.0] ml, P<0.05; 6 hours: aprotinin: 150.0 [100.0-220.0] ml, control: 225.0 [200.0-347.5.0] ml, P<0.01; 24 hours: aprotinin: 370.0 [220.0-510.0] ml, control: 655.0 [500.0-920.0] ml, P<0.01). The number of patients receiving blood transfusion in each group was similar. Levels of D-dimer rose significantly after surgery, and were significantly lower in the aprotinin group than in the controls (end of surgery, aprotinin, 0.4 [0.2-0.5] mg/l versus controls, 1.4 [0.8-2.3] mg/l; 2 hours, aprotinin, 0.3 [0.2-0.4] mg/l versus controls, 0.9 [0.5-1.4] mg/l; 6 hours, aprotinin, 0.3 [0.2-0.5] mg/l versus controls, 0.6 [0.4-0.9] mg/l; 24 hours, aprotinin, 0.3 [0.2-0.4] mg/l versus controls, 0.5 [0.4-0.9] mg/l; ANOVA for repeated measures, P<0.01). Platelet adhesion rate and FPA levels remained at baseline levels after the operation in the two groups. Early clinical outcomes were similar in the groups. Levels of CKMB were significantly lower in the aprotinin group than in the controls (6 hours after surgery, aprotinin, 10.0 [8.0-16.0] U/l versus controls, 15.5 [11.0-20.3] U/l; 12 hours, aprotinin, 13.5 [10.0-20.0] U/l versus controls, 19.0 [12.8-24.3] U/l; 24 hours, aprotinin, 19.0 [13.5-33.8] U/l versus controls, 25.0 [15.0-43.3] U/l; 72 hours, aprotinin, 13.0 [8.0-18.0] U/l versus controls, 16.0 [10.0-29.0] U/l; ANOVA for repeated measures, P=0.018). CONCLUSION: The results indicated that half-dose aprotinin limits fibrinolysis and myocardial injury, and reduces blood loss after OPCAB surgery.

Tranexamic acid reduces postoperative bleeding in off-pump coronary artery bypass grafting.

OBJECTIVE: Tranexamic acid (TA) reduces blood loss in coronary artery surgery with cardiopulmonary bypass. The present prospective study was designed to investigate its hemostatic effect in off-pump coronary artery bypass (OPCAB). METHOD: Seventy-six patients undergoing elective OPCAB were randomized into two groups, received TA (0.75 g loading dose before surgery and 250 mg/h during surgery, gross dose: 1.5 g, n=36) and saline solution (control, n=40), respectively. Perioperative blood samples were collected. Hematochemical parameters including platelet adhesion rate, D-dimer and fibrinopeptide-A (FPA) were analysis. Volume of blood loss, blood transfusion and other clinical data were recorded throughout the perioperative period. RESULTS: Cumulative blood loss was significantly reduced in the TA group as compared to the controls postoperatively (6 hrs (median [25th-75th]): TA: 200.0 [140.0-230.0] ml, CONTROL: 225.0 [200.0-347.5.0] ml, p=0.009; 24 hrs: TA: 440.0 [270.0-605.0] ml, CONTROL: 655.0 [500.0-920.0] ml, p<0.001). Number of patients received blood transfusion in each group was similar. Levels of D-dimer rose significantly after surgery, and were significantly lower in the TA group than that in controls. Platelet adhesion rate and FPA levels remained at baseline levels after the operation in two groups. Early clinical outcomes were similar between groups. CONCLUSION: The results indicated that tranexamic acid limits fibrinolysis and reduces blood loss after off-pump coronary artery bypass surgery.