Epinephrine induced platelet aggregation in rat platelet-rich plasma

Topical combined tranexamic acid and epinephrine versus topical epinephrine in control of intraoperative bleeding of external dacryocystorhinostomy

PURPOSE

To compare the efficacy of gauze soaked with combined tranexamic acid (TXA) (100 mg/ml) epinephrine 1:200,000 versus gauze soaked with only epinephrine 1:200,000 used to guard against intraoperative bleeding in external Dacryocystorhinostomy (DCR).

PATIENTS AND METHODS

The study included 33 patients; only 30 patients fulfilled the inclusion criteria and were divided randomly into 2 groups using the random numbers table, with 15 patients in each group. The first group (Group A) was operated upon using gauze soaked with combined TXA (100 mg/ml) and epinephrine 1:200,000, while the second group (Group B) was operated upon using gauze soaked only with epinephrine 1:200,000.

RESULTS

The amount of bleeding was significantly lower in group A (29.4 ± 17.1 ml) compared to group B (49.1 ± 18.1 ml), with a P value = 0.005. In addition, the number of used gauzes and total surgical time was significantly lower in group A compared to group B, with P value = 0.008 and 0.01 respectively.

CONCLUSION

External DCR using gauze soaked with combined TXA (100 mg/ml) and epinephrine 1:200,000 showed a significant reduction in the amount of intraoperative bleeding compared to gauze soaked with epinephrine 1:200,000 only. The reduction in the amount of bleeding with the addition of TXA resulted in clearer surgical field, shorter surgical time and more surgeon satisfaction.Query.

Perilla oil and α-linolenic acid ameliorated thrombosis in rats induced by collagen and epinephrine

Perilla frutescens is an annual herbaceous plant widely cultivated for oil production in China, Japan, and Korea. In this study, we investigated the effect of perilla oil (PO) on thrombosis induced by collagen and epinephrine (CE) in rats. The oral administration of PO significantly increased prothrombin time (PT) and activated partial thromboplastin time (aPTT) in the blood plasma and inhibited the expression of cells adhesion markers (CAMs) such as intercellular CAM-1 (ICAM-1), vascular CAM (VCAM-1), E-selectin and P-selectin in the aorta tissue. Furthermore, pulmonary occlusion induced by CE in rats was suppressed by PO. α-Linolenic acid (ALA) was quantified at 60.14 ± 2.50 g/100 g of PO, and its oral administration at the same concentration with that in PO exerted the similar effect on PT, aPTT, ICAM-1, VCAM-1, E-selectin and P-selectin in CE-induced thrombosis rats. Taken together, PO and ALA significantly ameliorated thrombosis by regulating CAMs.

Antiplatelet therapy at discharge and long-term prognosis in Takotsubo syndrome: Insights from the Spanish National Registry (RETAKO)

INTRODUCTION

Endothelial dysfunction and platelet activation have been highlighted as possible mediators in Takotsubo syndrome (TTS). Nevertheless, to date, evidence on the usefulness of antiplatelet therapy in TTS remains controversial. The aim of our study is to evaluate long-term prognosis in TTS patients treated with antiplatelet therapy (APT) at hospitalization discharge.

MATERIAL AND METHODS

An ambispective cohort study from the Spanish National Takotsubo Registry database was performed (June 2002 to March 2017). Patients were divided into two groups: those who received APT at hospital discharge (APT cohort) and those who did not (non-APT cohort). Primary endpoint was all-cause death. Secondary endpoints included the composite of recurrence or readmission and a composite of death, recurrence or readmission.

RESULTS

From a total of 741 patients, 728 patients were alive at discharge. Follow-up was performed in 544 patients, who were included in the final analysis: 321 patients (59.0%) in the APT cohort and 223 patients (41.0%) in the non-APT cohort. The APT cohort had a better clinical presentation and received more heart failure and acute coronary syndrome-like therapies (angiotensin converting enzyme inhibitors/angiotensin receptor blockers: 75.1% vs. 51.1%; p<0.001, betablockers: 71.3% vs. 50.7%; p<0.001, statins: 67.9% vs. 33.2%; p<0.001). After adjusting for confounder factors, APT at discharge was a protective factor for all-cause death (adjusted hazard ratio (HR) 0.315, 95% confidence interval (CI): 0.106-0.943; p=0.039) and the composite endpoint of all-cause death, recurrence or readmission (adjusted HR 0.318, 95% CI: 0.164-0.619; p=0.001) at month 25 of follow-up.

CONCLUSION

Patients with TTS receiving APT at discharge presented better prognosis up to two-years of follow-up compared with their counterparts not receiving APT.

Reduction in SOCE and Associated Aggregation in Platelets from Mice with Platelet-Specific Deletion of Orai1

Calcium signalling in platelets through store operated Ca²⁺ entry (SOCE) or receptor-operated Ca²⁺ entry (ROCE) mechanisms is crucial for platelet activation and function. Orai1 proteins have been implicated in platelet’s SOCE. In this study we evaluated the contribution of Orai1 proteins to these processes using washed platelets from adult mice from both genders with platelet-specific deletion of the Orai1 gene (Orai1^flox/flox; Pf4-Cre termed as Orai1^Plt-KO) since mice with ubiquitous Orai1 deficiency show early lethality. Platelet aggregation as well as Ca²⁺ entry and release were measured in vitro following stimulation with collagen, collagen related peptide (CRP), thromboxane A2 analogue U46619, thrombin, ADP and the sarco/endoplasmic reticulum Ca²⁺-ATPase (SERCA) inhibitor thapsigargin, respectively. SOCE and aggregation induced by Thapsigargin up to a concentration of 0.3 µM was abrogated in Orai1-deficient platelets. Receptor-operated Ca²⁺-entry and/or platelet aggregation induced by CRP, U46619 or thrombin were partially affected by Orai1 deletion depending on the gender. In contrast, ADP-, collagen- and CRP-induced aggregation was comparable in Orai1^Plt-KO platelets and control cells over the entire concentration range. Our results reinforce the indispensability of Orai1 proteins for SOCE in murine platelets, contribute to understand its role in agonist-dependent signalling and emphasize the importance to analyse platelets from both genders.

How effective is periarticular multimodal drug injection in open elbow arthrolysis? A prospective double-blind randomized controlled trial

BACKGROUND

Evidence on the efficacy and safety of periarticular multimodal drug injection (PMDI) in open elbow arthrolysis (OEA) is limited. This study aimed to investigate differences in postoperative pain, blood loss, and range of motion (ROM) between PMDI vs. no injection among patients undergoing OEA, and the presence of PMDI-related complications.

METHODS

This prospective, double-blind randomized controlled trial included 59 patients who underwent OEA. Patients randomly received PMDI (ropivacaine, epinephrine, ketoprofen) before wound closure or no injection. The primary outcomes were elbow pain over the first postoperative week at rest and during motion, measured using the visual analog scale (VAS). VAS scores were compared to attain the 20-mm threshold values for a minimum clinically important difference. Parecoxib consumption on OEA night and postoperative days (PODs) 1-3 and total consumption during the first postoperative week were recorded. Blood loss was recorded every 24 hours until POD 3. ROM during rehabilitation was measured daily from day 1 to day 7 after surgery, as well as at 3-month follow-up. Medication-related side effects were recorded prospectively.

RESULTS

The mean VAS score showed clinically important differences between PMDI and control groups at rest on OEA night (mean difference [MD], 25 mm; P < .001) and first 3 PODs with motion (POD 1: MD, 28 mm, P < .001; POD 2: MD, 21 mm, P < .001; POD 3: MD, 21 mm, P < .001) but not in other postoperative assessments. Parecoxib consumption was lower in the PMDI group on OEA night and PODs 1-3. Total parecoxib consumption during the first postoperative week was lower in the PMDI group vs. the control group (MD, 148 mg; P < .001). Blood drainage was less in the PMDI group vs. the control group on POD 1 (MD, 38 mL; P = .016) but not on POD 2 (P = .950), POD 3 (P = .259), or total (P = .184). The PMDI group exhibited significantly better ROM during the first 4 PODs than the control group, whereas there was no difference at 3-month follow-up. No medication-related side effects were noted in the PMDI group.

CONCLUSION

PMDI effectively relieves pain and reduces analgesic consumption for OEA patients, without an apparent increase in risks.

Comparative efficacy and safety of topical hemostatic agents in primary total knee arthroplasty: A network meta-analysis of randomized controlled trials

BACKGROUND

Topical hemostatic agents are commonly used for reducing perioperative blood loss and transfusion requirement in primary total knee arthroplasty (TKA), although the optimal option has yet to be defined. This study aimed to evaluate the efficacy and safety of topical hemostatic agents and rank the best intervention using the network meta-analysis (NMA) method.

METHODS

We searched Web of science, PubMed, and Cochrane Library database up to April 2020, for randomized controlled trials (RCTs) on topical hemostatic agents in primary TKA. The quality of included studies was assessed using the Cochrane "risk of bias" tool. Direct and indirect comparisons were performed for the result of network meta-analysis followed by consistency test.

RESULTS

Thirty seven RCTs with 3792 patients were included in this NMA and the pooled results indicated that tranexamic acid plus diluted epinephrine (TXA+DEP) displayed the highest efficacy in reducing total blood loss, hemoglobin drop and transfusion requirement. None of the included treatments was found to increase risk of thromboembolic events compared to placebo. According to the results of ranking probabilities, TXA+DEP had the highest possibility to be the best topical hemostatic agent with regard to the greatest comparative efficacy and a relatively high safety level.

CONCLUSION

Current evidence supports that administration of TXA+DEP may be the optimal topical hemostatic agent to decrease blood loss and transfusion requirement in primary TKA. More direct studies that focused on the topical application of TXA+DEP versus other treatments are needed in the future.

Utilization of epinephrine-soaked gauzes to address bleeding from osteotomy sites in non-tourniquet total knee arthroplasty: a retrospective cohort study

Background

Reducing tourniquet inflation time is important because of the complications of tourniquet extensively used for the control of hemorrhage in total knee arthroplasty (TKA). Bleeding management is critical to acquire a relative bloodless arthrotomy interface for maximize cement fixation in non-tourniquet TKA. The purpose of this study was to investigate hemostatic and hemodynamic effects of epinephrine-soaked gauzes in cemented TKAs.

Methods

A retrospective cohort study of 101 patients in two groups was performed. The first group (n = 51) underwent unilateral TKA with our procedures of epinephrine use, the second group (n = 50) had the same protocol with tourniquet and no epinephrine utilization. Surgical field visualization was assessed by grading scale for difficulty of intraoperative visualization due to blood and number of surgical field clearances. Perioperative blood loss was recorded. Hemodynamic parameters were observed in the epinephrine group.

Results

There was statistically significant difference (p < 0.01) on surgeon-rated difficulty in visualization in the epinephrine group between before and after use of epinephrine, and no statistically significant difference (p = 0.96) between two groups before cementing. No statistically significant result on numbers of surgical field clearances between two groups (p = 0.25) was found. Epinephrine group showed significant difference in hidden blood loss compared with no epinephrine group (576.6 ± 229.3 vs 693.2 ± 302.9, respectively, p = 0.04). The hemodynamic effects of epinephrine may be under control.

Conclusion

The procedure of epinephrine soaked gauzes, as a prudent adjunct, may be effective to reduce blood loss and obtain bloodless bone sections in non-tourniquet TKAs, regardless of hemodynamics.

Gellable silk fibroin-polyethylene sponge for hemostasis

Traditional haemostatic materials generally have slow hemostasis rate and poor biocompatibility. This paper reports on the haemostatic properties and mechanism of silk fibroin (SF). SF-PEG sponge that could be solubilised and changed to gel form by blood was fabricated through mixing SF and polyethylene glycol (PEG, 1500 Da) followed by lyophilisation of the mixed solution. SF-PEG sponge, together with control samples of SF sponge (no PEG) and a commercially available haemostatic material, gelatine sponge, were subjected to the hemostasis tests using a liver trauma model of rabbit. The results showed that SF was superior to gelatine sponge in hemostasis time (136.17 ± 62.27 s and 249.83 ± 29.18 s) and blood loss (2.16 ± 1.27 g vs. 4.97 ± 1.44 g). Furthermore, in vitro experiments indicated SF-PEG sol-gel transition promoted platelet adhesion and aggregation, as well as platelet-fibrinogen interaction. Therefore, except for the physical blocking of bleeding port due to PEG-induced SF fast gelation, SF might also have an impact on blood coagulation process, a phenomenon that has not been reported before. In conclusion, SF is a new type of haemostatic material that might be able to meet the requirements of speed, efficiency and biosafety in a variety of clinical applications.

Pharmacological Studies Pertaining to Smooth Muscle Relaxant, Platelet Aggregation Inhibitory and Hypotensive Effects of Ailanthus altissima

OBJECTIVE

This in vitro and in vivo study was conducted to rationalize some of traditional medicinal uses of Ailanthus altissima in gastrointestinal, respiratory, and cardiovascular systems.

MATERIALS

Crude extract of Ailanthus altissima (Aa.Cr) and its fractions were prepared and utilized in in vitro and in vivo studies. For in vitro studies, Aa.Cr was investigated on isolated rabbit jejunum, isolated tracheal strip, and isolated aorta of rat suspended in tissue organ bath. Platelet rich and platelet poor plasma were used to study platelet aggregation inhibitory activity. In vivo antidiarrheal effect of Aa.Cr was investigated on balb/c mice pretreated with castor oil to induce diarrhea and SD rats were used to study hypotensive activity.

RESULTS

Concentration dependent spasmolytic effects of Aa.Cr and its DCM fraction (Aa.DCM) were observed on spontaneous and spasmogen induced contractions in jejunum isolated from rabbit, but effect against high potassium (high-K+) induced contractions was more potent. Moreover Aa.Cr showed parallel shifting of calcium response curve to the right side. While its aqueous fraction (Aa.aq) caused spasmogenesis of isolated rabbit jejunum, this effect was blocked partially with prior administration of atropine (1μM). Concentration dependent protection against castor oil induced diarrhea was also observed. Relaxant effect was observed by the application of Aa.Cr and Aa.DCM against high-K+ and carbachol (CCh) induced contractions in tracheal strips isolated from SD rats, while Aa.Aq caused partial relaxation of high-K+ induced contractions, but no effect was observed against CCh induced contractions. Relaxation of rat aorta by the application of Aa.Cr and its fractions was also observed. Inhibition of force of contraction in rabbit atrium was also observed. Inhibition of platelet aggregation was observed against epinephrine and ADP induced aggregation.

CONCLUSION

Keeping in view the observed results, it is concluded that smooth muscle relaxant, platelet aggregation inhibitory and hypotensive effect may be due to the blockage of calcium channels.

Tranexamic Acid Plus Low-dose Epinephrine Reduces Blood Loss in Total Knee Arthroplasty: A Systematic Review and Meta-analysis

The present study assessed the effectiveness of the combined administration of tranexamic acid (TXA) plus low-dose epinephrine in primary total knee arthroplasty (TKA). We searched the following Chinese electronic databases: China National Knowledge Infrastructure and WanFang Data. We also searched the following English electronic databases: PubMed, Embase, Web of Science, and Central Register of Controlled Trials. To search for additional eligible studies, we also used Google's search engine. All randomized controlled trials (RCT) comparing TXA plus low-dose epinephrine (Combined group) and TXA alone in TKA were systematically searched. The primary outcomes were total blood loss, hidden blood loss, the requirement for transfusion, maximum hemoglobin (Hb) drop, and deep venous thrombosis (DVT). Drainage volume, operation time, length of stay, hospital for special surgery (HSS) score, and range of motion (ROM) were considered as secondary outcomes. Subgroup analyses were performed to assess the benefits of using a tourniquet and the application routes of topical or intravenous TXA between the two groups. Statistical analysis was assessed using RevMan 5.3 software. Four independent RCT were included involving 426 patients, with 213 patients in the Combined group and 213 patients in the TXA alone group. In the Combined group there was significant reduction in total blood loss (MD, 204.70; 95% CI, -302.76 to -106.63; P < 0.0001), hidden blood loss (MD, 185.63; 95% CI, -227.56 to -143.71; P < 0.00001), drainage volume (MD, 93.49; 95% CI, -117.24 to -69.74; P < 0.00001), and maximum Hb drop (MD, 5.33, 95% CI, -6.75 to -3.91; P < 0.00001). No statistical differences were found postoperatively in terms of the requirement for transfusion (risk ratio, 0.52; 95% CI, 0.26-1.04; P = 0.06), operation time (MD, 0.85; 95% CI, -2.62 to 4.31; P = 0.63), length of stay (MD, -0.02; 95% CI, -0.52 to 0.47; P = 0.93), HSS score (MD, 0.78; 95% CI, -0.36 to 1.92; P = 0.18), and ROM (MD, 1.40; 95% CI, -1.01 to 3.81; P = 0.26), and not increasing the risk of DVT (risk ratio, 1.00; 95% CI, 0.33 to 3.02; P = 1.00) in the two groups. This meta-analysis demonstrated that the administration of tranexamic acid plus low-dose epinephrine is a safe and efficacious treatment to reduce total blood loss, hidden blood loss, drainage volume, and maximum Hb drop in primary TKA, without increasing the risk of DVT in primary THA.

Application of tranexamic acid and diluted epinephrine in primary total hip arthroplasty

: Tranexamic acid (TXA) and diluted epinephrine (DEP) has been reported to be an efficient and well tolerated way for reducing blood loss in total hip arthroplasty (THA). This meta-analysis was designed to compare the effectiveness of combination application of TXA with DEP in primary THA. The following electronic databases were searched, including PubMed, EMBASE, Web of Science, the Cochrane Library, China National Knowledge Infrastructure and Google Search Engine, for published studies involving the TXA with DEP in primary THA. All randomized controlled trials (RCTs) were included. Statistical analysis was assessed using RevMan 5.3 software. Five independent RCTs were included, with a total sample size of 496 patients. The application of TXA with DEP can significantly reduce total blood loss (mean difference, 246.13; 95% CI, -369.95 to -122.32; P < 0.0001), hidden blood loss (mean difference, 299.98; 95% CI -433.61 to -166.35; P < 0.0001) and transfusion requirements (risk ratio, 0.50; 95% CI 0.28-0.90; P = 0.02) compared with the TXA alone. There were no significant differences in intraoperative blood loss (P = 0.46), drainage volume (P = 0.61), length of stay (P = 0.53) and the rate of DVT (P = 0.56) between the two groups. On the basis of current evidence, this meta-analysis showed that the application TXA with DEP is a well tolerated and efficacious treatment to reduce total blood loss, hidden blood loss and transfusion requirements in primary THA, without increasing the risk of DVT in primary THA.

Low-Dose Epinephrine Plus Tranexamic Acid Reduces Early Postoperative Blood Loss and Inflammatory Response: A Randomized Controlled Trial

BACKGROUND

The reductions of perioperative blood loss and inflammatory response are important in total knee arthroplasty. Tranexamic acid reduced blood loss and the inflammatory response in several studies. However, the effect of epinephrine administration plus tranexamic acid has not been intensively investigated, to our knowledge. In this study, we evaluated whether the combined administration of low-dose epinephrine plus tranexamic acid reduced perioperative blood loss or inflammatory response further compared with tranexamic acid alone.

METHODS

This randomized placebo-controlled trial consisted of 179 consecutive patients who underwent primary total knee arthroplasty. Patients were randomized into 3 interventions: Group IV received intravenous low-dose epinephrine plus tranexamic acid, Group TP received topical diluted epinephrine plus tranexamic acid, and Group CT received tranexamic acid alone. The primary outcome was perioperative blood loss on postoperative day 1. Secondary outcomes included perioperative blood loss on postoperative day 3, coagulation and fibrinolysis parameters (measured by thromboelastography), inflammatory cytokine levels, transfusion values (rate and volume), thromboembolic complications, length of hospital stay, wound score, range of motion, and Hospital for Special Surgery (HSS) score.

RESULTS

The mean calculated total blood loss (and standard deviation) in Group IV was 348.1 ± 158.2 mL on postoperative day 1 and 458.0 ± 183.4 mL on postoperative day 3, which were significantly reduced (p < 0.05) compared with Group TP at 420.5 ± 188.4 mL on postoperative day 1 and 531.1 ± 231.4 mL on postoperative day 3 and Group CT at 520.4 ± 228.4 mL on postoperative day 1 and 633.7 ± 237.3 mL on postoperative day 3. Intravenous low-dose epinephrine exhibited a net anti-inflammatory activity in total knee arthroplasty and did not induce an obvious hypercoagulable status. Transfusion values were significantly reduced (p < 0.05) in Group IV, but no significant differences were observed in the incidence of thromboembolic complications, wound score, range of motion, and HSS score among the 3 groups (p > 0.05).

CONCLUSIONS

The combined administration of low-dose epinephrine and tranexamic acid demonstrated an increased effect in reducing perioperative blood loss and the inflammatory response compared with tranexamic acid alone, with no apparent increased incidence of thromboembolic and other complications.

LEVEL OF EVIDENCE

Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

Effects of low-dose epinephrine on perioperative hemostasis and inflammatory reaction in major surgical operations: a randomized clinical trial

Essentials Blood loss and immune reaction are closely related to morbidity and recovery after surgery. We studied the effect of epinephrine plus tranexamic acid on blood loss and immune reaction. Epinephrine plus tranexamic acid reduced postoperative total blood loss and immune reaction. Epinephrine plus tranexamic acid did not increase the incidence of complications.

SUMMARY

Background Hemostasis, thrombosis and surgical stress-induced immune reactions are important for perioperative morbidity and recovery after major surgical operations. Objectives To evaluate the effects of combined administration of low-dose epinephrine (LDEPI) and tranexamic acid (TXA) on perioperative blood loss, thromboembolic complications and inflammatory responses in patients undergoing total hip arthroplasty (THA). Patients/Methods Patients scheduled for THA (n = 195) were randomized into three interventions: intravenous LDEPI plus TXA (group IV); topical diluted epinephrine plus TXA (group TP); and TXA alone as control (group CT). The primary outcome was perioperative blood loss on postoperative day (POD) 1. Secondary outcomes included perioperative blood loss on POD 3, intraoperative blood loss, volume of drainage, transfusion values, coagulation and fibrinolysis parameters, inflammatory cytokine levels, cases of thrombosis, intravenous fluid on the operation day, and length of hospital stay. Results The mean calculated amounts of total blood loss in groups IV, TP and CT were 631.2 mL, 760.5 mL, and 825.6 mL, respectively, on POD 1; treatment effects (differences) were 194.4 mL (95% confidence interval [CI] 146.7-242.0) and 65.0 mL (95% CI 17.4-112.7). Groups IV and TP had lower levels of proinflammatory cytokines (tumor necrosis factor-α and interleukin [IL]-1β) and higher levels of the anti-inflammatory cytokine IL-10, and showed faster development of coagulation and fibrinolysis (without change in peak levels), than group CT early postoperation. No differences were observed in transfusion, thromboembolic and other outcomes among the groups. Conclusion The combined administration of LDEPI and TXA was more effective in reducing perioperative blood loss and alleviating the inflammatory response than TXA alone, without increasing the incidence of thromboembolic and other complications.

Tranexamic acid plus diluted-epinephrine versus tranexamic acid alone for blood loss in total joint arthroplasty: A meta-analysis

BACKGROUND

We conducted the present meta-analysis to assess the efficacy and safety of tranexamic acid (TXA) plus diluted-epinephrine (DEP) for patients with total joint arthroplasty (TJA, including total knee arthroplasty (TKA) and total hip arthroplasty (THA)).

METHODS

Electronic databases (PubMed, EMBASE, the Cochrane Central Register of Controlled Trials (CENTRAL), Chinese Wanfang databases, and Google databases) were systematically searched up to December 2016. Only randomized controlled trials (RCTs) were included. The primary outcomes were total blood loss and need for transfusion. The secondary outcomes were hemoglobin drop and the incidence of deep venous thrombosis (DVT) and hematoma. Continuous outcomes and discontinuous outcomes were compiled as the weighted mean difference (WMD) and relative risk (RR) with 95% confidence intervals (CI), respectively.

RESULTS

A total of 5 RCTs with a total of 493 patients were eligible and ultimately included in the meta-analysis. Compared with the TXA group, TXA plus DEP yielded a significant reduction in total blood loss (WMD = -244.78; 95% CI -290.12 to -199.44; P < .001), need for transfusion (RR = 0.27; 95% CI 0.15-0.48; P < .001) and hemoglobin drop (WMD = -0.81; 95% CI -1.22 to -0.40; P < .001). There was no significant difference in incidence of DVT (RR=0.67; 95% CI 0.27-1.64; P = .382) or hematoma (RR=0.89; 95% CI 0.30-2.61; P = .831) between the TXA plus DEP group and the TXA group.

CONCLUSION

TXA plus DEP can decrease perioperative blood loss without increasing the incidence of DVT compared with TXA alone. However, considering the limited number of included RCTs, this conclusion should be interpreted cautiously, and more high-quality RCTs are needed to verify the efficacy and safety of TXA plus DEP for TJA patients.

The efficacy and safety of epinephrine for postoperative bleeding in total joint arthroplasty: A PRISMA-compliant meta-analysis

BACKGROUND

Total joint arthroplasty (TJA) usually results in postoperative bleeding. Some randomized controlled trials (RCTs) and nonrandomized controlled trials (non-RCTs) have been performed to evaluate the effects of epinephrine on postoperative bleeding after TJA. However, this remained controversial about the efficacy and safety of epinephrine for postoperative bleeding in TJA. The objective of our meta-analysis was to compare the overall effect and safety of epinephrine and placebo for postoperative bleeding in TJA.

METHODS

PubMed, Embase, and the Cochrane Library were searched to identify potentially relevant articles. RCTs or non-RCTs involving epinephrine and placebo for blood loss in total knee arthroplasty or total hip arthroplasty were included. Our study was performed based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement. RevMan v5.3 was used to analyze the relevant data.

RESULTS

Four RCTs and 1 non-RCT involving 646 participants met the inclusion criteria. The overall pooled results from meta-analysis demonstrated that compared with control groups, epinephrine groups could significantly reduce the postoperative bleeding volume (mean difference [MD] = -168.42, 95% confidence interval [CI]: -272.37 to -64.47, P = 0.001). There was no significant difference in intraoperative bleeding volume between epinephrine and control groups (MD = -12.89, 95% CI: -53.45 to 27.69, P = 0.53). No significant difference was found between 2 groups in terms of postoperative hemoglobin loss (MD = -0.28, 95% CI: -0.66 to 0.10, P = 0.15). Compared with the control groups, no statistically significant difference was found in terms of postoperative transfusion rate in epinephrine groups (relative risk [RR] 0.86, 95% CI: 0.64-1.15, P = 0.31). In addition, the results of the meta-analysis also indicated no significant difference in terms of the incidence rate of deep venous thrombosis (DVT) between 2 groups (RR 0.28, 95% CI: 0.05-1.64, P = 0.16).

CONCLUSION

The meta-analysis showed that epinephrine could significantly reduce postoperative bleeding volume in TJA without increasing the incidence of DVT. However, there was no significant reduction in intraoperative bleeding volume, postoperative hemoglobin loss, and transfusion rate after the administration of epinephrine.

LIMITATIONS

In this study, a higher heterogeneity and a risk of selection bias may be present in postoperative hemoglobin loss. In addition, the sample size of the included studies was too small, so our findings need to be further validated with more high-quality and larger scale RCTs in the future.

SYSTEMATIC REVIEW REGISTRATION NUMBER

None.

Incidence and predictors of stroke during the index event in an ethnically diverse Takotsubo cardiomyopathy population

Takotsubo cardiomyopathy (TTS) is a peculiar clinical condition often affecting postmenopausal women after a stressful trigger. The underlying mechanisms have not been completely elucidated but several hypotheses have been advanced, with catecholamine cardiotoxicity, microvascular dysfunction and coronary artery spasm each suggested to play a role. The incidence of stroke after TTS appears to range from 0% to 7.7%, and interestingly TTS has been described as both a cause and a complication of stroke. We sought to assess the incidence and predictors of stroke during the index event (peri-index event stroke) in a heterogeneous TTS population. We conducted a retrospective descriptive study reviewing patients who were discharged with a diagnosis of TTS from the Einstein Medical Center, Philadelphia, PA and Danbury Hospital, Danbury, CT in the period between 2003 and 2014. A total of Incidence and predictors of stroke during the index event in an ethnically diverse Takotsubo cardiomyopathy population 206 patients met the modified Mayo Clinic criteria and were included in the study. The patients' overall mean age was 67.8 years; 87% (n=179) were females and 25% (n=53) were African Americans. The following incidence rates were found: stroke 7%, in-hospital heart failure 26.7%, and in-hospital death 7%. On multivariate analysis independent predictors (expressed as odds ratios with 95% confidence intervals) of periindex event stroke were: i) African American race (OR 3.2, 95% CI 1.2-10.2, p=0.048); ii) hypertension (OR 10.5, 95% CI 1.3-88, p=0.03). ACE inhibitor use was a protective factor for developing peri-index event stroke (OR 0.15, 95% CI 0.04-0.5, p=0.001). There was a trend towards dual antiplatelet therapy (DAPT) being protective for stroke (OR 0.3, 95% CI 0.05-1.1, p=0.08). The incidence of peri-index event stroke was 7%. African American race and hypertension were found to be independent predictors of peri-index event stroke. Prospective clinical trials are needed to confirm these findings and to better determine the impact of hypertension as a risk factor for stroke and to assess the role of DAPT in preventing it.

Topical Application of Tranexamic Acid Plus Diluted Epinephrine Reduces Postoperative Hidden Blood Loss in Total Hip Arthroplasty

We evaluated the efficacy and safety of topical application of tranexamic acid (TXA) plus diluted epinephrine (DEP) and its effect on perioperative hidden blood loss and transfusion requirement in primary unilateral total hip arthroplasty (THA). We randomized 107 patients undergoing THA into two groups: 53 received intra-articular TXA 3 g plus 1:200,000 DEP 0.25 mg; 54 received topical TXA 3 g alone. Results showed that combined administration significantly reduced total blood loss (P=0.009), hidden blood loss (P=0.001) and transfusion rate (1.9 vs. 9.3%) compared with TXA alone, without increasing the risks of thromboembolic and hemodynamic complications. Topical TXA plus DEP in THA can decrease postoperative hidden blood loss and avoid homologous transfusion without substantial complications.

Antiplatelet therapy in Takotsubo cardiomyopathy: does it improve cardiovascular outcomes during index event?

Plasma catecholamines may play an important role in Takotsubo cardiomyopathy (TCM) pathophysiology. Patients with disproportionately high catecholamine responses to stressful events are prone to worse clinical outcomes. Catecholamines stimulate platelet activation and, therefore, may determine the clinical presentation and outcomes of TCM. We conducted a retrospective, descriptive study TCM patients admitted between 2003 and 2013 to Einstein Medical Center, Philadelphia, PA, USA and Danbury Hospital, Danbury, CT, USA. A total of 206 patients met Modified Mayo TCM criteria. Using a multiple logistic model, we tested whether aspirin, dual antiplatelet therapy (DAPT) aspirin + clopidogrel, beta blocker, statin, or ACE inhibitor use were independent predictors of major adverse cardiovascular events (MACE) during the index hospitalization. MACE was defined as in-hospital heart failure, in-hospital death, stroke or respiratory failure requiring mechanical ventilation. Incidence of in-hospital heart failure was 26.7 %, in-hospital death was 7.3 %, stroke was 7.3 % and MACE was 42.3 %. In a multiple logistic regression model (adjusted for gender, race, age, physical stressor, hypertension, diabetes, hyperlipidemia, smoking history, body mass index, initial left ventricular ejection fraction, single antiplatelet therapy, DAPT, beta blocker, statin, and ACE inhibitor) aspirin and DAPT at the time of hospitalization were independent predictors of a lower incidence of MACE during the index hospitalization (aspirin: OR 0.4, 95 % CI (0.16-0.9), P = 0.04; DAPT: OR 0.23; 95 % CI (0.1-0.55); P < 0.01. Physical stressor itself was also found to be an independent predictor of worse MACE: OR 5.1; 95 % CI (2.4-11.5); P < 0.01. In our study, aspirin and DAPT were independent predictors of a lower incidence of MACE during hospitalization for TCM. Prospective clinical trials are needed to confirm the findings of this study.

Topical Administration of Tranexamic Acid Plus Diluted-Epinephrine in Primary Total Knee Arthroplasty: A Randomized Double-Blinded Controlled Trial

The aim of this trial was to evaluate the efficacy and safety of intra-articular administration of tranexamic acid (TXA) plus diluted-epinephrine (DEP) on perioperative blood loss and transfusion in primary unilateral total knee arthroplasty (TKA) without drainage. One hundred patients scheduled to undergo TKA were randomized into two groups: 50 patients received intra-articular 3g TXA plus 0.25mg DEP (1:200,000), and 50 patients received 3g topical TXA alone. The results showed that topical combined administration significantly reduced total blood loss (P=0.006), hidden blood loss (P=0.000) and transfusion rate (0% vs. 4%), without increasing the risk of thromboembolic and hemodynamic complications (P>0.05). Therefore, topical TXA plus DEP was effective and safe in reducing blood loss and transfusion following TKA, without substantial complications.

Alterations in the extracellular catabolism of nucleotides and platelet aggregation induced by high-fat diet in rats: effects of α-tocopherol

The aim of this study was to assess whether α-tocopherol administration prevented alterations in the ectonucleotidase activities and platelet aggregation induced by high-fat diet in rats. Thus, we examined four groups of male rats which received standard diet, high-fat diet (HFD), α-tocopherol (α-Toc), and high-fat diet plus α-tocopherol. HFD was administered ad libitum and α-Toc by gavage using a dose of 50 mg/kg. After 3 months of treatment, animals were submitted to euthanasia, and blood samples were collected for biochemical assays. Results demonstrate that NTPDase, ectonucleotide pyrophosphatase/phosphodiesterase, and 5'-nucleotidase activities were significantly decreased in platelets of HFD group, while that adenosine deaminase (ADA) activity was significantly increased in this group in comparison to the other groups (P < 0.05). When rats that received HFD were treated with α-Toc, the activities of these enzymes were similar to the control, but ADA activity was significantly increased in relation to the control and α-Toc group (P < 0.05). HFD group showed an increased in platelet aggregation in comparison to the other groups, and treatment with α-Toc significantly reduced platelet aggregation in this group. These findings demonstrated that HFD alters platelet aggregation and purinergic signaling in the platelets and that treatment with α-Toc was capable of modulating the adenine nucleotide hydrolysis in this experimental condition.

The Operculina macrocarpa (l.) urb. (jalapa) tincture modulates human blood platelet aggregation

ETHNOPHARMACOLOGICAL RELEVANCE

Operculina macrocarpa is an ornamental climbing plant of the Northeastern Brazil extensively used in traditional medicine as depurative of the blood and for the treatment of thrombosis. To investigate the antiplatelet and anticoagulant potential of Operculina macrocarpa and to determine the possible mechanisms of action.

MATERIAL AND METHODS

The Operculina macrocarpa tincture (OMT) was characterized by the polyphenol content and chromatographic profile established by HPLC with detection and quantification of three phenol acids (caffeic, clorogenic and gallic acids). The human platelet aggregation was induced in vitro by the agonists ADP, collagen, thrombin, epinephrine or arachidonic acid, and the antiplatelet effect of OMT was evaluated in the presence or absence of aspirin (a nonselective inhibitor of cyclooxygenase), pentoxifylline (a phosphodiesterase inhibitor), ticlopidine (a P2Y12 purinoceptor antagonist) or ODQ (a selective inhibitor of guanilate cyclase). The effect of OMT on the partial thromboplastin time, prothrombin time and bleeding time were investigated on human or rat plasma.

RESULTS

The strongest antiplatelet effect of OMT (50-400 µg/mL) was observed on the ADP- induced aggregation with inhibitions up to 55%, while among others agonists (epinephrine, collagen, thrombin and arachidonic acid) maximal inhibitions reached by OMT (200 µg/mL) were on platelet aggregation induced by collagen (18%) or epinephrine (20%). The antiplatelet effect of OMT (400 µg/mL) was comparable to aspirin, a nonspecific inhibitor of cyclooxygenase. The ticlopidine and pentoxifylline increased 5.1 and 3.8 fold the inhibitory effect of OMT on ADP-induced platelet aggregation, respectively. On the other hand, l-arginine, ODQ and aspirin showed a slightly or no effect on antiplatelet effect of OMT. The bleeding time in rats was significantly increased by OMT, but the tincture did not interfere on the activated partial thromboplastin or prothrombin time in human plasma.

CONCLUSIONS

This study showed that the tincture of Operculina macrocarpa has antiplatelet effect that cannot be attributed to a single biochemical mechanism and at least part of it cannot be related to the OMT inhibition of P2Y12 purinergic receptors.

Identification and characterization of platelet α2-adrenoceptors and imidazoline receptors in rats, rabbits, cats, dogs, cattle, and horses

This study aimed to pharmacologically identify and characterize α2-adrenoceptors and imidazoline (I) receptors (I1- and I2-subtype) on canine, feline, bovine, equine, murine, and leporine platelet membranes. Saturation binding studies with both (3)H-yohimbine and (3)H-clonidine showed that α2-adrenoceptors were expressed on canine, leporine, feline, and murine platelets but not on bovine and equine platelets. In competition studies, the rank order of affinity of 6 compounds for canine platelet α2-adrenoceptors was similar to that of potency at α2A-subtype reported in human platelets. Saturation binding studies in the presence of norepinephrine showed that canine, feline, bovine, and equine platelets had I1-receptors defined by (3)H-clonidine binding, but neither murine nor leporine platelets had I1-receptors; whereas, platelets of all species had I2-receptors defined by (3)H-idazoxan binding. In competition studies, more potent compounds displayed biphasic competition curves with (3)H-clonidine. The rank orders of affinity of I1 compounds for high-affinity components of I1-receptors of canine, feline, bovine, and equine platelets and I2-receptors of all species platelets were similar to those of compounds for high-affinity components reported in human I1- and I2-receptors, respectively. Guanine nucleotides inhibited the high-affinity component of naphazoline binding to canine I1-receptors, but not to I2-receptors. Furthermore, guanine nucleotides dose-dependently inhibited (3)H-clonidine binding to I1-receptors; whereas, they did not interfere with (3)H-idazoxan binding to I2-receptors, supporting the notion that Il-receptors may belong to a G protein-coupled receptor superfamily in canine platelets. Interspecific variations of platelet α2-adrenoceptor and imidazoline receptor expressions may explain different platelet responses to catecholamines and imidazoline α-adrenergic agents.

Exercise training prevents ecto-nucleotidases alterations in platelets of hypertensive rats

In this study, we investigated the effect of 6 weeks of swimming training on the ecto-nucleotidase activities and platelet aggregation from rats that developed hypertension in response to oral administration of L-NAME. The rats were divided into four groups: control (n = 10), exercise (n = 10), L-NAME (n = 10), and exercise L-NAME (n = 10). The animals were trained five times per week in an adapted swimming system for 60 min with a gradual increase of the workload up to 5 % of animal's body weight. The results showed an increase in ATP, ADP, AMP, and adenosine hydrolysis, indicating an augment in NTPDase (from 35.3 ± 8.1 to 53.0 ± 15.1 nmol Pi/min/mg protein for ATP; and from 21.7 ± 7.0 to 46.4 ± 15.6 nmol Pi/min/mg protein for ADP as substrate), ecto-5'-nucleotidase (from 8.0 ± 5.7 to 28.1 ± 6.9 nmol Pi/min/mg protein), and ADA (from 0.8 ± 0.5 to 3.9 ± 0.8 U/L) activities in platelets from L-NAME-treated rats when compared to other groups (p < 0.05). A significant augment on platelet aggregation in L-NAME group was also observed. Exercise training was efficient in preventing these alterations in the exercise L-NAME group, besides showing a significant hypotensive effect. In conclusion, our results clearly indicated a protector action of moderate intensity exercise on nucleotides and nucleoside hydrolysis and on platelet aggregation, which highlights the exercise training effect to avoid hypertension complications related to ecto-nucleotidase activities.

Pomolic acid, triterpenoid isolated from Licania pittieri, as competitive antagonist of ADP-induced aggregation of human platelets

Pomolic acid (PA), triterpenoid isolated from Licania pittieri, has previously shown a potent ability to inhibit adenosine diphosphate (ADP)- and epinephrine-induced human platelet aggregation. To investigate whether PA could be an antagonist of ADP-activated receptors of human platelets (P2Y(1) and P2Y(12)), pharmacological studies were conducted to examining its ability to modulate the platelet shape change induced by a selective P2Y(1) receptor agonist MRS2365 and also the nature of its possible interaction with ADP receptors by analyzing the characteristics of log concentration-response curves of ADP constructed in the absence and in the presence of fixed concentrations of PA, using in vitro platelet aggregation assays. PA did not interfere with the activation of P2Y(1) receptor by MRS2365 to induce platelet shape change and displayed a competitive antagonism of ADP-induced platelet aggregation, which most probably involves competition for a single binding site in platelets. The estimated equilibrium dissociate constant (K(b)) of PA as ADP receptor antagonist was 15.4±0.06nM. Together, these findings give indirect evidence for the idea that PA could be a potent competitive antagonist of P2Y(12) receptor, and open the possibility to consider it as new member of the non-nucleotide generation of antiplatelet drugs.

Reactionary haemorrhage reduction with adrenaline infiltration in proximal tibial osteotomy: a randomized clinical study of safety and efficacy

INTRODUCTION

In corrective osteotomy, wound closure is undertaken with or without deflation of the tourniquet. Hypoxia from the tourniquet causes vasodilatation associated with reactionary haemorrhage and reduced haemoglobin concentration and possibly increased blood transfusion rate. Reactionary haemorrhage and related transfusion need can be reduced through vasoconstriction from adrenaline infiltration.

METHOD

A randomized, placebo-controlled trial was done to compare adrenaline-saline solution to normal saline in the control of reactionary haemorrhage after proximal tibial osteotomy in children. Sixty-one eligible patients were divided into two groups and had corrective osteotomy under the same surgeon over a period of 7 years.

RESULTS

Wound infiltration with adrenaline-saline solution 1:200,000 and normal saline was done in groups one and two, respectively. No intra-operative adverse effect was recorded. There was a 20% incidence of superficial wound dehiscence in group 1 and none in controls. The mean volume of blood in drains in the first 24 h post operation was 85 ml in group 1 and 225 ml in group 2 (p < 0.001). The mean haemoglobin level on the fifth day post operation was 11.8 g/dl in group 1 and 8.2 g/dl in group 2 (p < 0.001). There was no blood transfusion in group one while two patients were transfused in group two.

CONCLUSION

In conclusion, wound infiltration with adrenaline was effective in reducing the extent of reactionary haemorrhage and post-operative drop in haemoglobin concentration. There was no significant difference in the transfusion rates in both groups.

Platelet function and Isoprostane biology. Should isoprostanes be the newest member of the orphan-ligand family?

While there have been many reports investigating the biological activity and signaling mechanisms of isoprostanes, their role in biology, particularly in platelets, appears to still be underestimated. Moreover, whether these lipids have their own receptors is still debated, despite multiple reports that discrete receptors for isporpstanes do exist on platelets, vascular tissues, amongst others. This paper provides a review of the important literature of isoprostanes and provides reasoning that isoprostanes should be classified as orphan ligands until their receptor(s) is/are identified.

Fructose-1,6-bisphosphate inhibits in vitro and ex vivo platelet aggregation induced by ADP and ameliorates coagulation alterations in experimental sepsis in rats

Sepsis is a systemic response to an infection that leads to a generalized inflammatory reaction. There is an intimate relationship between procoagulant and proinflammatory activities, and coagulation abnormalities are common in septic patients. Pharmaceutical studies have focused to the development of substances that act on coagulation abnormalities and on the link between coagulation and inflammation. Fructose-1,6-bisphosphate (FBP) is a high-energy glycolitic metabolite that in the past two decades has been shown therapeutic effects in great number of pathological situations, including sepsis. The aims of this study were to assess the effects of FBP on platelet aggregation in vitro and ex vivo in healthy and septic rats and evaluate the use of FBP as a treatment for thrombocytopenia and coagulation abnormalities in abdominal sepsis in rat. FBP inhibited platelet aggregation (P < 0.001) in vitro in healthy rats from the smallest dose tested, 2.5 mM, in a dose-dependent manner. The mean effective dose calculated was 10.6 mM. The highest dose tested, 40 mM, completely inhibited platelet aggregation (P < 0.001) induced by ADP. Platelet aggregation in plasma from septic rats was inhibited only with higher doses of FBP, starting from 20 mM (P < 0.001). The calculated mean effective dose was 19.3 mM. Ex vivo platelet aggregation in septic rats was significantly lower (P < 0.05) than healthy rats and the treatment with FBP, at the dose of 2 g/kg, diminished the platelet aggregation at the extension of 27% (P < 0.001), suggesting that FBP is a potent platelet aggregation inhibitor in vivo. Moreover, treatment with FBP 2 g/kg prevented thrombocytopenia (P < 0.001), prolongation of prothrombin and partial thromboplastin time (P < 0.001), but not fibrinogen, in septic rats. The most important findings in this study are that FBP is a potent platelet aggregation inhibitor, in vitro and ex vivo. It presents protective effects on coagulation abnormalities, which can represent a treatment against DIC. The mechanisms for these effects remain under investigation.

Inhibition of adrenaline and adenosine diphosphate induced platelet aggregation by Lansberg's hognose pit viper (Porthidium lansbergii hutmanni) venom

The haemostatic components of venom from the genus Porthidium has been poorly studied, although it is known that severe manifestations occur when humans are envenomed, which include invasive oedema and disseminated ecchymosis. The effects of venom on blood platelets are commonly studied and are normally carried out with platelet-rich plasma (PRP). A series of crude venom dilutions was used to determine the effects of adenosine diphosphate (2 microM) and adrenaline (11 microM) induced platelet aggregation. Venom of Porthidium lansbergii hutmanni was fractioned by anionic exchange chromatography, and the fractions were also used to determine the 50% inhibition of adenosine diphosphate (ADP) and adrenaline-induced platelet aggregating dose (AD50). Crude venom has more effect in inhibiting adrenaline-induced aggregation (AD50 = 0.0043 microg) followed by the adenosine diphosphate (AD50 = 17 microg). Peaks I and II obtained by chromatography also inhibited adrenaline-induced platelet aggregation with an AD50 of 3.2 and 0.013 microg, respectively, and both peaks inhibited ADP-induced platelet aggregation with an AD50 of 10 microg. The main purpose of this work was to characterise the in vitro effects caused by P. lansbergii hutmanni crude venom and its fractions on the platelet aggregation mediated by adrenaline and ADP agonists.

Effects of higenamine and its 1-naphthyl analogs, YS-49 and YS-51, on platelet TXA2 synthesis and aggregation

The effects of higenamine and its 1-naphthyl analogs, YS-49 and YS-51, on thromboxane A(2) (TXA(2)) formation from arachidonic acid (AA) and aggregation in platelets, were investigated. YS-49 and YS-51 (IC(50); 32.8 and 39.4 microM respectively) exhibited much stronger inhibitory effects on TXA(2) formation than higenamine (IC(50); 2.99 mM). The higher inhibitory potencies of YS-49 and YS-51 (IC(50): 3.3 and 5.7 microM respectively) than higenamine (IC(50): 140 microM) on AA induced rat platelet aggregation was presumed to be the result of low inhibitory effect of higenamine than YS-49 and YS-51 on TXA(2) production from AA. Among the present three compounds, the more hydrophobic naphthylmethyl groups were supposed to be more favorable than p-hydroxybenzyl moiety, at 1-position of the tetrahydroisoquinoline ring, to display the inhibitory effects on TXA(2) production and AA induced aggregation of platelets. In addition, higenamine, YS-49 and YS-51 were observed directly antagonistic on TXA(2) receptor (TP receptors) by displaying inhibitory effects to U46619 (TXA(2) mimetic) induced platelet aggregation, however all of the three compounds showed similar order of inhibitory potencies. The present results are suggestive that YS-49 and YS-51 exert their inhibitory effects on AA-induced platelet aggregation partly by inhibiting the production of TXA(2) from AA and partly by directly blocking the TP receptor, in addition to the previously reported effects on alpha(2)-adrenergic receptor. On the other hand, higenamine is supposed to antagonize AA-induced platelet aggregation by mostly directly blocking the TP receptor.

Local infusion of norepinephrine reduces blood losses and need of transfusion in total knee arthroplasty

Blood loss after total knee arthroplasty (TKA) is often associated with cardiovascular complications and a high transfusion rate of allogenic blood. In our study we focused our attention on developing a new intra-surgical procedure that appears safe, easy to perform and effective in the reduction of bleeding in TKA. We evaluated 84 patients who underwent TKA and met our inclusion criteria; they were assigned to two groups: 55 controls in which a saline solution was used to wash the surgical field before tourniquet release, and a second group of 29 patients, in which a saline solution containing a low dose of norepinephrine was locally applied before tourniquet release. The local administration of a low dose of norepinephrine has induced a significant reduction of perioperative blood loss and blood transfusion requirements; in addition, this method was characterised by the absence of complications or adverse effects. In conclusion, our data suggest that intraoperative local administration of a low dose of norepinephrine could represent an effective and safe method of reducing blood loss and preventing blood transfusions in patients with TKA.

Increased aggregation response of platelets in patients with inflammatory bowel disease

BACKGROUND

Platelets play an important role in hemostatic and inflammatory responses. To evaluate any potential enhancement of platelet activity in patients with inflammatory bowel disease (IBD), we measured the platelet aggregation responses to various stimuli.

METHODS

Twenty-two healthy controls, 24 patients with ulcerative colitis (UC) and 25 patients with Crohn's Disease (CD) were studied. The aggregation responses induced by three agonists (epinephrine, collagen, and ADP) were measured by an 8-channel aggregometer. The platelet-derived microparticles (PDMP) levels were measured by an enzyme-linked immunosorbent assay.

RESULTS

Twenty-one out of the 22 healthy controls did not respond to epinephrine (0.1 microg/ml), collagen (0.2 microg/ml), or ADP (1.0 microM). Eight out of the 12 active UC patients were sensitive to all agonists, and 4 patients showed increased sensitivity to epinephrine/collagen or epinephrine/ADP. Three out of the 12 inactive UC patients were normal, but 9 of these patients showed increased sensitivity, mainly to epinephrine. Ten out of the 12 active CD patients were sensitive to all agonists, and 2 active CD patients were sensitive to epinephrine/collagen or epinephrine/ADP. Eight out of the 13 inactive CD patients were sensitive to two or all agonists. Even after remission, almost all of the UC and CD patients showed some increased sensitivity to the agonists. The platelet number and the plasma PDMP levels were significantly higher in the active IBD patients than in the control group.

CONCLUSIONS

Platelet aggregation responses are enhanced in IBD, even in inactive-phase patients. This increased sensitivity of the platelets may play an important role in the pathophysiology of IBD.

Anti-platelet pentacyclic triterpenoids from leaves ofcampsis grandiflora

Five pentacyclic triterpenoids, oleanolic acid (1), hederagenin (2), ursolic acid (3), tormentic acid (4) and myrianthic acid (5), were isolated from the methanol extract of the leaves of Campsis grandiflora, and structures of the compounds were established by the spectroscopic methods. Compounds 2, 3, 4, and 5 were isolated for the first time from the genus Campsis. All of the compounds (IC50: 45.3, 32.8, 82.6, 42.9 and 46.2 microM respectively) were as equivalently inhibitive as acetylsalicylic acid (IC50: 57.0 microM) on epinephrine induced platelet aggregation.

Apparent heterogeneous responsiveness of human platelet rich plasma to catecholamines

The platelet-rich plasma (PRP) from 35 healthy Korean volunteers were challenged by four catecholamines and clonidine, which were known as alpha-adrenergic agonists. Wide individual variations were observed with the respect to the pattern and the degree of aggregation in response to each agent. They fall into five distinct groups; Group A (2.9%) was responsive to all five agonists; Group B (28.6%) aggregated in response to (-)-epinephrine, (-)- norepinephrine and epinine; Group C (37.1%) aggregated in response to (-)-epinephrine and (-)-norepinephrine;Group D (11.4%) aggregated only by (-)-epinephrine; Group E (20%) showed impaired responsiveness to all the alpha-agonists tested. All of the non-responding PRP were capable of induction of aggregation in response to (-)-epinephrine, (-)-norepinephrine and epinine in the presence of near-threshold concentration of collagen. Variations were also observed between groups with dopamine and clonidine. Dopamine and clonidine failed to induce secondary aggregation, even in the presence of low concentration of collagen, in most of the PRP preparations belonging to Groups D and E and only slight improvements were observed in the preparations belonging to groups Band C. The observation on heterogeneous responsiveness to catecholamines with PRP of Korean volunteers is quite different from the previous report with PRP of presumably mostly Caucasians.

Anti-platelet effect of the constituents isolated from the barks and fruits of Magnolia obovata

In the course of our work on anti-platelet constituents from plants, five phenolic compounds, magnolol, honokiol, obovatol, methyl caffeate, and syringin, were isolated from the methanol extracts of the barks and fruits of Magnolia obovata. The compounds were identified based on the spectroscopic data. Methyl caffeate was isolated for the first time from the genus Magnolia and it showed 3 approximately 4-folds higher potency than ASA. The activities of obovatol and honokiol were comparable to ASA. Magnolol and syringin showed only very mild inhibitory effects to all the stimulators.

Antithrombotic effects of YS-49 and YS-51--1-naphthylmethyl analogs of higenamine

The antiplatelet and antithrombotic effects of YS-49 and YS-51--l-naphthylmethyl analogs of higenamine, which is a benzyl-tetrahydroisoquinoline alkaloid isolated from Aconitum japonicum (Ranunculaceae)--were investigated. YS-49 and YS-51 showed inhibitory activities to both human and rat platelet aggregation induced by ADP, collagen and epinephrine. They were more inhibitory to epinephrine-induced aggregation (IC(50); 3.4 and 1.7 microM of YS-49, and 6.0 and 6.3 microM of YS-51 to human and rat platelets, respectively) than ADP- or collagen-induced aggregation. The antithrombotic effects of YS-49 and YS-51 were also observed in both mouse acute thrombosis model and rat arterio-venous shunt (AV shunt) model. The oral administration of YS-49 and YS-51 (50 or 100 mg/kg) increased the recovery rates from the acute thrombotic challenge in mice and lowered the weight of thrombus formed inside the AV shunt tube in rats.