Whole Blood Clotting Research Articles

Correlation analysis of coagulation disorders and the severity and outcome of pediatric sepsis: Thromboelastography method

Objective To assess the association between coagulation disorders and the severity as well as the outcome of pediatric sepsis by thromboelastography(TEG) method. Methods Total of 62 patients suffering from sepsis or severe sepsis in PICU in our hospital from February 2014 to January 2015 were included in this study.All patients had routine blood tests, inflammatory biomarkers(CRP, PCT) tests, organ function parameters(ALT, TBiL, ALB, Cr, BUN, PaO2/FiO2) tests, lactic acid, classical coagulation laboratory test(platelets count, APTT, PT, INR, Fib, D-dimers) and TEG(R, K, α, MA, LY30, CI) everyday for the first 3 days of diagnosis of sepsis or severe sepsis(D1, D2, D3). (1)D1~3 TEG results between Sepsis and Severe sepsis groups were investigated; D1 inflammatory biomarkers and D1~3 critical scores between hypocoagulation and hypercoagulation groups were investigated.(2)D1 organ function parameters(ALT, TBiL, ALB, Cr, BUN, PaO2/FiO2)and D1~3Pediatric multiple organ dysfunction score(P-MODS) between hypocoagulation and hypercoagulation groups were investigated.(3)D1~3 TEG results between sepsis and severe sepsis groups were compared; Dependence of 28 day survival on normal or pathological D1CI, APTT, PT were evaluated using Kaplan-Meier plots and Log Rank test. Results (1)Coagulation disorders and the severity of sepsis: Compared with sepsis group(n=41), severe sepsis group(n=21) presented persistent hypocoagulability: D1~2R and D1, D3K were significantly prolonged, D1~3α, MA, CI were significantly reduced(P<0.05); Compared with hypercoagulation group(n=26), hypocoagulation group(n=16) had significantly higher D1PRISM Ⅲ scores(P<0.05), lower D1 neutrophils counts(P<0.05). (2)Coagulation disorders and multiple organ dysfunction syndrome: Compared with hypercoagulation group, hypocoagulation group had more severe organ dysfunctions: Cr, BUN, ALT were increased(P<0.05); higher D1 P-MODS scores(P<0.05)and D1~3 organ failure index(P<0.05)were found in hypocoagulation group.(3)Coagulation disorders and outcome of sepsis: hypocoagulation group had a higher mortality than hypercoagulation group(62.5% vs.15.4%, P<0.05); Non-survival group(n=18) presented persistent hypocoagulability compared with survival group(n=44) according to D1~3TEG results[D1~2R, D1 and D3K were prolonged, D1~3α, MA, CI were reduced(P<0.05)]; Kaplan-Meier plots demonstrated that normal or pathological D1CI were associated with 28-day survival(P<0.05). Conclusion TEG assays present that persistent hypocoagulability can reveal the severity and 28 day prognosis of sepsis.TEG may be a valuable tool in assessing whole blood coagulation disorders in pediatric sepsis with a comprehensive evaluation of the severity as well as the outcome of sepsis. Key words: Thromboelastography; Sepsis; Severe sepsis; Coagulation disorders; Organ dysfunctions; Pediatrics

Lytic efficacy of tissue plasminogen activator and ultrasound in porcine clots doped with barium sulfate in vitro

Swine and porcine tissue are employed routinely for preclinical models of ischemic stroke. In this study, we examined the lytic susceptibility of porcine whole-blood clots, prepared with and without barium sulfate, a radiopaque x-ray contrast agent. The degree of lytic efficacy in the two types of clots was compared for recombinant tissue plasminogen activator (rt-PA) concentrations ranging from 0 to 100 μg/mL. Subsequently, a in vitro flow model and time-lapse thrombolysis microscopy system was used to evaluate lysis in clots with and without barium sulfate in response to rt-PA and 120-kHz intermittent ultrasound exposure. The degree of lysis observed with both types of clots was similar for rt-PA concentrations up to 15.75 μg/mL. However, clots doped with barium sulfate demonstrated significantly lower lysis at higher rt-PA concentrations. Similarly, results obtained using the in vitro flow model showed that both types of clots underwent comparable lysis when treated with 15.75 μg/mL rt-PA. Further, using Definity® and 120-kHz ultrasound as an adjuvant to rt-PA did not enhance lysis in either porcine clot model compared to rt-PA alone. These results highlight the considerable differences in the degree of clot lysis between porcine clots and previously reported studies that used human clots.

Effect of distance and delay in access to care on outcome of snakebite in rural north-eastern Nigeria

Snakebite envenoming is a major cause of morbidity and mortality in rural areas of the tropics. Timely administration of effective antivenom remains the mainstay of management. The study was a quantitative descriptive study aimed at exploring the causes and effects of delay, distance and time taken to access care on snakebite outcomes in Nigeria. All prospective snakebite victims reporting to Kaltungo General Hospital were enrolled. Data on demography, date and time bitten, date and time admitted, site of bite, circumstances of snakebite, responsible snake, clinical features, 20-minute whole-blood clotting test, antivenom administered and outcome were recorded. Delay arising from use of traditional first aid (TFA), time elapsed from snakebite to presentation and the shortest distance from bite location to the hospital was calculated or obtained using a global positioning system. The association between delay before hospital presentation and poor outcome was not statistically significant, even though there was a 2% higher likelihood of poor outcome among those with a 1-hour delay compared to those without delay (odds ratio 1.02, 95% confidence interval 1.00-1.03). There was no difference in distance from bite location to hospital between those with a poor outcome (74) compared to those with a good outcome (325). Those with a poor outcome had more severe envenomation requiring more antivenoms and longer hospital stays. Given poor access to antivenom therapy at distant locations &#8805;100 km, victims were more likely to use TFA such as black 'snake' stone, with consequent prolonged delays. Antivenoms should be more readily available at distant places. Community education on avoiding potentially harmful TFA and prompt access to care is recommended. There is a need to provide snakebite care to multiple peripheral, relatively more rural inaccessible areas.

The key roles of complement and tissue factor in Escherichia coli-induced coagulation in human whole blood.

The complement system and the Toll-like (TLR) co-receptor CD14 play important roles in innate immunity and sepsis. Tissue factor (TF) is a key initiating component in intravascular coagulation in sepsis, and long pentraxin 3 (PTX3) enhances the lipopolysaccharide (LPS)-induced transcription of TF. The aim of this study was to study the mechanism by which complement and CD14 affects LPS- and Escherichia coli (E. coli)-induced coagulation in human blood. Fresh whole blood was anti-coagulated with lepirudin, and incubated with ultra-purified LPS (100 ng/ml) or with E. coli (1 × 10(7) /ml). Inhibitors and controls included the C3 blocking peptide compstatin, an anti-CD14 F(ab')2 antibody and a control F(ab')2 . TF mRNA was measured using quantitative polymerase chain reaction (qPCR) and monocyte TF surface expression by flow cytometry. TF functional activity in plasma microparticles was measured using an amidolytic assay. Prothrombin fragment F 1+2 (PTF1.2) and PTX3 were measured by enzyme-linked immunosorbent assay (ELISA). The effect of TF was examined using an anti-TF blocking antibody. E. coli increased plasma PTF1.2 and PTX3 levels markedly. This increase was reduced by 84->99% with compstatin, 55-97% with anti-CD14 and > 99% with combined inhibition (P < 0·05 for all). The combined inhibition was significantly (P < 0·05) more efficient than compstatin and anti-CD14 alone. The LPS- and E. coli-induced TF mRNA levels, monocyte TF surface expression and TF functional activity were reduced by > 99% (P < 0·05) with combined C3 and CD14 inhibition. LPS- and E. coli-induced PTF1.2 was reduced by 76-81% (P < 0·05) with anti-TF antibody. LPS and E. coli activated the coagulation system by a complement- and CD14-dependent up-regulation of TF, leading subsequently to prothrombin activation.

191 Interleukin-1 Alpha is Directly Activated During Haemostasis by Thrombin Cleavage

<h3></h3> The clinical consequences of atherosclerosis are closely associated with thrombus formation following plaque rupture. Thrombin primarily cleaves fibrinogen into fibrin which forms a thrombus at sites of injury, but can also induce inflammation indirectly via PAR receptors. Chronic inflammation is a key feature of atherosclerosis that promotes both plaque growth and instability, and links between inflammation and haemostasis are widely proposed. We now present data showing that the powerful proatherogenic cytokine IL-1α is directly activated by thrombin. We find that thrombin treatment of pro-IL-1α produces a truncated form, indicating cleavage of the protein in a similar manner to its canonical calpain cleavage. Mutation of the thrombin consensus in IL-1α prevented cleavage, confirming the site. Thrombin cleavage of pro-IL-1α induced similar cytokine activity as calpain, while recombinant proteins equivalent to the thrombin- and calpain-cleaved forms had identical activity. Importantly, cleavage and activation of pro-IL-1α also occurred during coagulation of platelet-rich plasma and whole blood, suggesting physiological relevance. Again, thrombin-site mutant pro-IL-1α was uncleaved and lacked activity, proving the specific action of thrombin. Murine pro-IL-1α also requires processing for cytokine activity and again thrombin cleavage induced full activity, supporting an evolutionary conserved mechanism. Importantly, specific mutation of the site in mouse pro-IL-1α prevents thrombin cleavage, which has enabled us to generate a novel knock-in mouse to study the <i>in vivo</i> relevance of these findings. We show that thrombin cleaves and activates pro-IL-1α at a novel site that is conserved across species. This suggests that thrombin-mediated activation of IL-1α during thrombosis may directly promote inflammation. We propose that this represents an unappreciated fundamental link between the key enzyme of thrombosis and the principal cytokine within immunity. These findings have broad implications for normal physiology and the pathogenesis of diseases such as atherothrombosis.

Study of multi-functional electrospun composite nanofibrous mats for smart wound healing

Composite nanofibers derived from synthetic and natural polymers normally show desirable characteristics in biomedical applications. In this study, composite nanofibrous mats (denoted as CNMs) with diameters of around 300nm were fabricated facilely using blends of chitosan, gelatin and shape memory polyurethane (SMPU) by electrospinning and subsequent post-treatment with a silver nitrate solution. The obtained CNMs have shape memory effect and show desirable water vapor transmission ratio, surface wettability, satisfactory biological properties including antibacterial activity against the common Gram-negative and Gram-positive bacteria, cytocompatibility demonstrated to fibroblast, and the hemostatic property through a whole-blood clotting test. In addition, such CNMs can possibly benefit the wound healing through shape fixation-assisted easy processing and shape recovery-assisted closure of cracked wounds, which can be fine-tuned by pre-programming. Therefore, the CNMs presented in this study can be used as potential smart wound dressings.

Black hemostatic sponge based on facile prepared cross-linked graphene

In this study, we demonstrate for the first time the remarkable hemostatic performance of a cross-linked graphene sponge (CGS) as a superb hemostat. The CGS can absorb plasma immediately (<40ms) to form a blood cell layer and promotes subsequent clotting. The interaction between the interface of the CGS and blood cells reveals that the fast blood coagulation is primarily attributed to the enrichment of hemocytes and platelets on the wound surface. An in vitro dynamic whole-blood clotting test further highlights the effectiveness of the CGS. Considering the facile preparation, low cost, nontoxicity, and long shelf life of the portable black sponge, the CGS has great potential for trauma treatment.

Correlation of Coagulation Markers and 4F-PCC-Mediated Reversal of Rivaroxaban in a Rabbit Model of Acute Bleeding

IntroductionRivaroxaban is an oral, selective direct factor Xa inhibitor approved for several indications in patients at risk of thrombotic events. One limitation of its clinical use is the lack of data pertaining to its reversal in situations where urgent response is critical (e.g. acute bleeding events or emergency surgery). Materials and methodsThis study assessed the effectiveness of a four-factor prothrombin complex concentrate (4F-PCC; Beriplex®/Kcentra®) for the reversal of rivaroxaban-associated bleeding in an in vivo rabbit model, and evaluated the correlations between in vitro coagulation parameters and haemostasis in vivo. ResultsAdministration of single intravenous doses of rivaroxaban (150–450μg/kg) resulted in increased and prolonged bleeding following standardised kidney incision. Pre-incision treatment with 4F-PCC (25–100IU/kg) resulted in a dose-dependent reversal of rivaroxaban (150 and 300μg/kg)-associated increases in time to haemostasis and blood loss; no reversal was seen at the highest rivaroxaban dose (450μg/kg). Of the in vitro biomarkers tested, thrombin generation and whole-blood clotting time correlated well with in vivo measures of 4F-PCC-mediated effects. Thrombin generation was highly reagent-dependent, with the assay initiated using the phospholipid-only reagent being the most predictive of effective haemostasis in vivo. ConclusionsIn summary, in a rabbit model of acute bleeding, treatment with 4F-PCC reduced bleeding to control levels following rivaroxaban 150μg/kg and 300μg/kg administration.

Maggot excretion products from the blowfly Lucilia sericata contain contact phase/intrinsic pathway-like proteases with procoagulant functions.

For centuries, maggots have been used for the treatment of wounds by a variety of ancient cultures, as part of their traditional medicine. With increasing appearance of antimicrobial resistance and in association with diabetic ulcers, maggot therapy was revisited in the 1980s. Three mechanisms by which sterile maggots of the green bottle fly Lucilia sericata may improve healing of chronic wounds have been proposed: Biosurgical debridement, disinfecting properties, and stimulation of the wound healing process. However, the influence of maggot excretion products (MEP) on blood coagulation as part of the wound healing process has not been studied in detail. Here, we demonstrate that specific MEP-derived serine proteases from Lucilia sericata induce clotting of human plasma and whole blood, particularly by activating contact phase proteins factor XII and kininogen as well as factor IX, thereby providing kallikrein-bypassing and factor XIa-like activities, both in plasma and in isolated systems. In plasma samples deficient in contact phase proteins, MEP restored full clotting activity, whereas in plasma deficient in either factor VII, IX, X or II no effect was seen. The observed procoagulant/intrinsic pathway-like activity was mediated by (chymo-) trypsin-like proteases in total MEP, which were significantly blocked by C1-esterase inhibitor or other contact phase-specific protease inhibitors. No significant influence of MEP on platelet activation or fibrinolysis was noted. Together, MEP provides contact phase bypassing procoagulant activity and thereby induces blood clotting in the context of wound healing. Further characterisation of the active serine protease(s) may offer new perspectives for biosurgical treatment of chronic wounds.

Fibrinolytic activity and dose-dependent effect of incubating human blood clots in caffeic acid phenethyl ester: in vitro assays.

Background. Caffeic acid phenethyl ester (CAPE) has been reported to possess time-dependent fibrinolytic activity by in vitro assay. This study is aimed at investigating fibrinolytic dose-dependent activity of CAPE using in vitro assays. Methods. Standardized human whole blood (WB) clots were incubated in either blank controls or different concentrations of CAPE (3.75, 7.50, 15.00, 22.50, and 30.00 mM). After 3 hours, D-dimer (DD) levels and WB clot weights were measured for each concentration. Thromboelastography (TEG) parameters were recorded following CAPE incubation, and fibrin morphology was examined under a confocal microscope. Results. Overall, mean DD (μg/mL) levels were significantly different across samples incubated with different CAPE concentrations, and the median pre- and postincubation WB clot weights (grams) were significantly decreased for each CAPE concentration. Fibrin removal was observed microscopically and indicated dose-dependent effects. Based on the TEG test, the Ly30 fibrinolytic parameter was significantly different between samples incubated with two different CAPE concentrations (15.0 and 22.50 mM). The 50% effective dose (ED50) of CAPE (based on DD) was 1.99 mg/mL. Conclusions. This study suggests that CAPE possesses fibrinolytic activity following in vitro incubation and that it has dose-dependent activities. Therefore, further investigation into CAPE as a potential alternative thrombolytic agent should be conducted.

Antidotes for patients taking novel oral anti-coagulants.

Antidotes for patients taking novel oral anti-coagulants.

Managing coagulopathy and thromboprophylaxis in the neurosurgical patient

Our understanding of the mechanisms underlying coagulation have advanced rapidly in recent years. In addition, there are new methods to assess coagulation and new agents in the treatments of thromboembolic diseases such as atrial fibrillation, myocardial infarction and venous thromboembolism. It is particularly important for the neurosurgeon to be familiar with this topic in order to balance risks between bleeding and thrombosis in association with surgery. This review provides an overview of the ‘cell-based’ theory of coagulation and the technique of rotational thromboelastograpy to measure wholeblood coagulation. We discuss current management strategies related to haemorrhage control, haemostasis in polytrauma, and the elective and emergency peri-operative management of aspirin, thienopyridines, warfarin and the novel oral anticoagulants (rivaroxaban, dabigatran, apixaban). Finally, the current evidence regarding neurosurgical thromboprophylaxis is reviewed.

Targeted dissolution of deep vein thrombosis by low-frequency ultrasound-mediated microbubbles carrying streptokinase

Objective To study thrombolytic efficiency and influencing factors of low-frequency ultrasound-mediated microbubbles carrying streptokinase.Methods Whole blood clots,contrast agent of ultrasound microbubble and streptokinase solution were prepared.Three groups were set up in this study,including control group (C,2 ml normal saline given),streptokinase group (S,streptokinase alone given) and ultrasound microbubble carrying streptokinase group [UMS,ultrasound (1.2 W/cm2 for 20 min) microbubbles carrying streptokinase].After treatment,the whole blood clots were weighed.Results The ultrasound microbubbles carrying streptokinase were stable.There was significant difference in the clot weight among the three groups (P ＜ 0.01).The thrombolysis rate in UMS group was 50.7％.Conclusion Lowfrequency ultrasound-mediated microbubbles carrying streptokinase may promote the dissolution of deep vein thrombosis effectively. Key words: Deep vein thrombosis; Ultrasound microbubble; Targeted therapy

The Effects of Thrombocytopenia on Clotting Profile in Whole Blood As Determined By Thromboelastography When Anticoagulant Is Present at Therapeutic or Prophylactic Concentration

Background: Anticoagulant therapy for the treatment of venous thromboembolism in patients with concomitant thrombocytopenia has been based on anecdotal evidence. The platelet (PLT) threshold at which anticoagulant therapy should be withheld is still controversial. A PLT count of 50 × 109/L was recommended to be the threshold in the past, but newer reviews have lowered the threshold to 30 × 109/L. We previously used thromboelastography (TEG) to study clotting in plasma reconstituted with autologous PLT. Since red cells also play a significant role in hemostasis and coagulation, we hereby developed a TEG model with whole blood (WB) in order to better mimic in vivo conditions to evaluate the clot formation in thrombocytopenic blood.Objective: Using TEG to monitor clotting in whole blood samples containing unfractionated heparin (UFH) or dalteparin, we evaluated the differences in clotting profile when PLT in the samples were reduced to thrombocytopenic range.Methods: Whole blood was collected from healthy volunteers in syringes containing citrate phosphate dextrose adenine (CDPA-1, pH=5.5) and 30 μg/L corn trypsin inhibitor. Magnetic CD 61 antibody chromatography was used to deplete PLT in the blood to a count of ≤ 15 × 109/L. Platelet-depleted whole blood (PDWB) was then mixed with untouched blood from the same donor to obtain the predefined PLT counts. Clotting was initiated in the TEG cups with 10 mM CaCl2 and tissue factor (TF) in the presence of either UFH (0.3 U/mL or 0.1 U/mL) or dalteparin (1 IU/mL or 0.3 IU/mL). Due to the mechanistic differences between UFH and dalteparin, we optimized the amount of TF to maximize the sensitivity of TEG assay for individual anticoagulants; thus, 2.25 pM and 2.05 pM were used for UFH and dalteparin experiments, respectively. However, the same amount of TF was used to evaluate the clotting with the same anticoagulant at both therapeutic and prophylactic concentrations. Clotting was monitored using a Haemoscope TEG at 37 ºC for a maximum of 3 hr or until maximum amplitude (MA) had been achieved. Three parameters of clotting profile including R, MA and area under the curve within the first 15 min of clotting (AUC15) were used for further analysis. A p-value < 0.05 was considered statistically significant.Results: All3 parameters showed significant compromise of clotting when PLT decreased from 150 × 109/L to < 15 × 109/L in the presence of UFH or dalteparin at therapeutic range. When these anticoagulants were reduced to prophylactic concentration, the clotting was also significantly moderated, but to a lesser extent, comparing samples with PLT at 150 × 109/L and those with PLT < 15 × 109/L. These are in accordance with the bleeding tendency in vivo.At 30 × 109/L, the newer recommended PLT threshold at which anticoagulant should be withheld in thrombocytopenic patients, the clotting parameters did not show any significant difference as compared to those at the traditional threshold of 50 × 109/L when UFH and dalteparin were at therapeutic concentrations. Similarly, when UFH was reduced to a prophylactic concentration, we detected no significant difference in the clotting profile between 50 × 109 PLT/L and 30 × 109 PLT/L. In contrast, in samples with dalteparin at a prophylactic concentration, MA was significantly lower at 30 × 109 PLT/L when compared with that at 50 × 109 PLT/L although R and AUC15 had no statistical difference. Additionally, samples of PDWB containing either anticoagulant at prophylactic concentration had better clot formation than those samples of 50 × 109 PLT/L containing UFH or dalteparin at therapeutic concentration.Conclusion: The TEG profile of WB clotting in this in vitro model simulates bleeding tendency observed clinically. In the presence of UFH or dalteparin at therapeutic concentration, there was no statistical difference in the TEG parameters comparing thrombocytopenic blood with 50 × 109 PLT/L and 30 × 109 PLT/L, supporting the latter as the new threshold to hold anticoagulant in thrombocytopenic patients. In addition, instead of holding all anticoagulants in severe thrombocytopenic patients with PLT < 30 × 109/L, administering UFH or dalteparin at prophylactic doses may offer a safe alternative, as both imped clotting in TEG even less than those at therapeutic concentration with thrombocytopenic blood at 50 × 109 PLT/L. [Display omitted] [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

The paradox of the lupus anticoagulant: history and perspectives.

A unique coagulation inhibitor prolonging whole-blood clotting time was described more than 50 years ago in two patients with systemic lupus erythematosus (SLE). The immunoglobulin nature of the inhibitor and its interaction with antiphospholipid antibodies was later demonstrated and the term "lupus anticoagulant (LA)" was coined to describe this laboratory finding. It soon became apparent that LA was a misnomer as it is often found in plasma from patients with clinical conditions other than SLE and is associated with thromboembolic events that may occur in otherwise healthy individuals. Individuals with LA have circulating autoantibodies that inhibits blood coagulation. These are mostly of IgG or IgM class and mainly directed against a phospholipid (PL)-binding plasma protein, β2-glycoprotein I (β2GPI). The presence of β2GPI-dependent LA represents a well-recognized risk factor for venous and arterial thromboembolism, as well as pregnancy loss and morbidity. β2GPI-dependent LA in the presence of documented previous thromboembolism, or history of pregnancy loss/morbidity, identifies definite anti-PL syndrome. Laboratory diagnosis of LA is thus of particular importance, as it may assign patients with a common event (thrombosis) to a group with a high risk for recurrence, which is a prerequisite for long-term oral antithrombotic treatment.

The effect of corn trypsin inhibitor and inhibiting antibodies for FXIa and FXIIa on coagulation of plasma and whole blood

Corn trypsin inhibitor (CTI), an inhibitor of FXIIa, is used to prevent plasma coagulation by contact activation, to specifically investigate tissue factor (TF)-initiated coagulation. In the present work the specificity of CTI for factor (F) XIIa is questioned. In the commercial available plasma coagulation assays CTI was found to double activated partial thromboplastin time (APTT) at a plasma concentration of 7.3±1.5μm CTI (assay concentration 2.4μm). No effect was found on the prothrombin time (PT) when high TF concentrations were used. Also, with specific antibodies for FXIIa and for FXIa only APTT was found to be extended but not PT. With specific enzyme assays using chromogenic substrates CTI was shown to be a strong inhibitor of FXIIa and a competitive inhibitor of FXIa with Ki =8.1±0.3μm, without effect on the coagulation factors FVIIa, FIXa, FXa and thrombin. In thrombin generation and coagulation (free oscillation rheometry, FOR) assays, initiated with low TF concentrations, no effect of CTI (plasma concentrations of 4.4 and 13.6μm CTI, 25 resp. 100mgL(-1) in blood) was found with ≥1pm TF. At ≤0.1pm TF in the FOR whole blood assay the coagulation time (CT) concentration dependently increased while the plasma CT became longer than the observation time. To avoid inhibition of FXIa and the thrombin feedback loop we recommend that for coagulation assays the concentration of CTI in blood should be below 20mgL(-1) (1.6μm) and in plasma below 3μm.

Sedative, hematologic and hemostatic effects of dexmedetomidine-butorphanol alone or in combination with ketamine in cats.

Acute stress induced by physical restraint can interfere with the validity of laboratory findings. Sedation could minimize such stress. However, it is not known whether sedation can affect hematologic and hemostatic parameters in cats. The purpose of this study was to evaluate hematologic and hemostatic parameters in domestic cats subjected to physical restraint in addition to one of two sedation protocols. In total, 50 cats were subjected to physical restraint and were then randomly divided into two groups of 25 animals, receiving dexmedetomidine (5 µg/kg) and butorphanol (0.3 mg/kg; DB group) or dexmedetomidine (5 µg/kg), butorphanol (0.3 mg/kg) and ketamine (3 mg/kg; DBK group). The cats were assessed for acute stress, sedation level, onset of sedation and duration of sedation. Blood samples were collected after handling and after sedation. The complete blood count (CBC), platelet count, buccal mucosal bleeding time (BMBT), whole-blood clotting time, prothrombin time (PT), activated partial thromboplastin time (aPTT) and thrombin time (TT) were determined for each sample, before and after chemical restraint. No statistically significant differences were found in the hematologic parameters. Certain hemostatic parameters (PT, aPTT and TT) were higher in the DB group (P <0.05). The onset of sedation was similar in the two groups, and the duration of sedation was longer in the DBK group. Both sedation protocols were effective for short-duration chemical restraint for blood collection from the studied cats, and no clinically relevant effects on hematologic or hemostatic parameters were detected.

Red blood cells and thrombin generation in sickle cell disease

The prothrombotic nature of sickle cell disease (SCD) is evidenced by the chronically elevated levels of almost all coagulation activation biomarkers, and an increased incidence of certain thrombotic events, including venous thromboembolism. Numerous studies have attempted to define the extent and elucidate the mechanism of the observed increase in thrombin generation in SCD patients in vivo. In general, these studies were performed using thrombin generation assays in platelet poor or platelet rich plasma and showed little difference in endogenous thrombin potential between the SCD cohort and healthy matched controls. In SCD, erythrocytes and monocytes have been demonstrated to exhibit procoagulant characteristics. Thus, the absence of these cellular components in standard thrombin generation assays may fail to reflect global hypercoagulability in the whole blood of patients with SCD. We were therefore surprised to see no difference in net thrombin generation in tissue factor-initiated initiated clotting of whole blood from patients with SCD. However, we are continuing to reconcile these seemingly disparate observations by slight modifications of the whole blood model that include alternative coagulation triggers and a re-examination of the net thrombin generation when the protein/protein S system is simultaneously interrogated.

Effects of poly(amidoamine) dendrimers on the structure and function of key blood components

Poly(amidoamine) dendrimers have a variety of promising biomedical applications; however, the biological safety of the dendrimers has not been well clarified. This study focuses on the effects of poly(amidoamine) dendrimers (G3, G4, G5, G5–OH) on the structure and function of key blood components, in order to elucidate the impacts of the dendrimers on the aggregation, morphology, lysis of human red blood cells, structural and conformational change as well as polymerization of fibrinogen, and the coagulation of blood tissue. The poly(amidoamine) dendrimers caused aggregation, morphological changes, and lysis of red blood cells, depending on the dendrimer concentration, generation, and surface functional groups. All the dendrimers induced fibrinogen structural and conformational changes, but only cationic dendrimers impaired fibrinogen polymerization ability at high concentrations. In addition, the cationic dendrimers inhibited the activity of clotting factors and fibrinogen in the coagulation of whole blood. Therefore, the surface functional groups, generation, and concentration of the dendrimers play important roles in affecting the structure and function of key blood components. These results provide a critical theoretical basis for the molecular design and clinical application of the poly(amidoamine) dendrimers.

Stationary Versus Agitated Storage of Whole Blood During Acute Normovolemic Hemodilution

Acute normovolemic hemodilution is an intraoperative technique to reduce the number of red blood cells lost in shed blood during surgery. Standard guidelines for storage of platelets recommend constant gentle agitation to maintain gas exchange for the metabolically active platelets. The collected whole blood (WB) for acute normovolemic hemodilution remains stationary for as long as 8 hours before reinfusion. We hypothesized that gentle agitation of WB throughout storage would improve the coagulation properties of the WB at the time of reinfusion. WB was collected from 10 volunteer donors and control samples taken. The units were split in 2 storage groups: agitated (rocked) and stationary (unrocked). Cell counts and fibrinogen levels, as well as thromboelastography (TEG®) measurements, including TEG® PlateletMapping® assays, were performed on the control sample and the test samples after 8 hours of rocked or unrocked storage at room temperature. Nine units WB from 9 different healthy volunteers were tested. There were no significant differences in hematocrit, hemoglobin, red blood cells counts, platelet counts, or fibrinogen levels between the control samples and the rocked and unrocked WB samples. WB coagulation as measured by TEG® was preserved during the 8-hour storage period in both the rocked and unrocked samples. There were no significant differences between the control, rocked, and unrocked samples in time to initiate clotting, time of clot formation, rate of clot formation, or maximum strength of clot values. There were also no significant differences in the fibrin contribution to clot strength between the control, rocked, and unrocked samples, and no significant difference between the platelet activation from adenosine diphosphate or arachidonic acid among any of the 3 groups. Given the small sample size, there is no statistical evidence on which to reject the null hypothesis of there being no difference in the changes from the baseline between coagulation function as measured by TEG® between WB that is either agitated or kept stationary for 8 hours. These findings need to be confirmed in a larger study.