Metabolic engineering combined with site-directed saturated mutations of α-keto acid decarboxylase for efficient production of 6-aminocaproic acid and 1,6-hexamethylenediamine.

6-Aminocaproic acid (6ACA) and 1,6-hexamethylenediamine (HMDA) are key precursors for nylon synthesis, and both are produced using petroleum-based chemical processes. However, the utilization of bio-based raw materials for biological production of monomers is crucial for nylon industry. In this study, we demonstrated that metabolic engineering of Escherichia coli and selected mutations of α-keto acid decarboxylase successfully synthesized 6ACA and HMDA. An artificial iterative cycle from l-lysine to chain-extended α-ketoacids was introduced into Escherichia coli BL21 (DE3). Then, the extended α-ketoacids were decarboxylated and oxidized for 6ACA production. Overexpression of catalase (KatE) combined with the site-directed mutations of α-isopropylmalate synthase (LeuA) contributed synergistic enhancement effect on synthesis of 6ACA, resulting in a 1.3-fold increase in 6ACA titer. Selected mutations in α-keto acid decarboxylase (KivD) improved its specificity and 170.00 ± 5.57 mg/L of 6ACA with a yield of 0.13 mol/mol (6ACA/l-lysine hydrochloride) was achieved by shake flask cultivation of the engineered strain with the KivD# (F381Y/V461I). Meanwhile, the engineered E. coli could accumulate 84.67 ± 4.04 mg/L of HMDA with a yield of 0.08 mol/mol (HMDA/l-lysine hydrochloride) by replacing aldehyde dehydrogenase with bi-aminotransferases. This achievement marks a significant advancement in the biological synthesis of 6-carbon compounds, since the biosynthetic pathways of HMDA are rarely identified.

Pharmacological interventions for the prevention of bleeding in people undergoing elective hip or knee surgery: a systematic review and network meta-analysis.

BACKGROUND: Hip and knee replacement surgery is a well-established means of improving quality of life, but is associated with a significant risk of bleeding. One-third of people are estimated to be anaemic before hip or knee replacement surgery; coupled with the blood lost during surgery, up to 90% of individuals are anaemic postoperatively. As a result, people undergoing orthopaedic surgery receive 3.9% of all packed red blood cell transfusions in the UK. Bleeding and the need for allogeneic blood transfusions has been shown to increase the risk of surgical site infection and mortality, and is associated with an increased duration of hospital stay and costs associated with surgery. Reducing blood loss during surgery may reduce the risk of allogeneic blood transfusion, reduce costs and improve outcomes following surgery. Several pharmacological interventions are available and currently employed as part of routine clinical care. OBJECTIVES: To determine the relative efficacy of pharmacological interventions for preventing blood loss in elective primary or revision hip or knee replacement, and to identify optimal administration of interventions regarding timing, dose and route, using network meta-analysis (NMA) methodology. SEARCH METHODS: We searched the following databases for randomised controlled trials (RCTs) and systematic reviews, from inception to 18 October 2022: CENTRAL (the Cochrane Library), MEDLINE (Ovid), Embase (Ovid), CINAHL (EBSCOhost), Transfusion Evidence Library (Evidentia), ClinicalTrials.gov and WHO International Clinical Trials Registry Platform (ICTRP). SELECTION CRITERIA: We included RCTs of people undergoing elective hip or knee surgery only. We excluded non-elective or emergency procedures, and studies published since 2010 that had not been prospectively registered (Cochrane Injuries policy). There were no restrictions on gender, ethnicity or age (adults only). We excluded studies that used standard of care as the comparator. Eligible interventions included: antifibrinolytics (tranexamic acid (TXA), aprotinin, epsilon-aminocaproic acid (EACA)), desmopressin, factor VIIa and XIII, fibrinogen, fibrin sealants and non-fibrin sealants. DATA COLLECTION AND ANALYSIS: We performed the review according to standard Cochrane methodology. Two authors independently assessed trial eligibility and risk of bias, and extracted data. We assessed the certainty of the evidence using CINeMA. We presented direct (pairwise) results using RevMan Web and performed the NMA using BUGSnet. We were interested in the following primary outcomes: need for allogenic blood transfusion (up to 30 days) and all-cause mortality (deaths occurring up to 30 days after the operation), and the following secondary outcomes: mean number of transfusion episodes per person (up to 30 days), re-operation due to bleeding (within seven days), length of hospital stay and adverse events related to the intervention received. MAIN RESULTS: We included a total of 102 studies. Twelve studies did not report the number of included participants; the other 90 studies included 8418 participants. Trials included more women (64%) than men (36%). In the NMA for allogeneic blood transfusion, we included 47 studies (4398 participants). Most studies examined TXA (58 arms, 56%). We found that TXA, given intra-articularly and orally at a total dose of greater than 3 g pre-incision, intraoperatively and postoperatively, ranked the highest, with an anticipated absolute effect of 147 fewer blood transfusions per 1000 people (150 fewer to 104 fewer) (53% chance of ranking 1st) within the NMA (risk ratio (RR) 0.02, 95% credible interval (CrI) 0 to 0.31; moderate-certainty evidence). This was followed by TXA given orally at a total dose of 3 g pre-incision and postoperatively (RR 0.06, 95% CrI 0.00 to 1.34; low-certainty evidence) and TXA given intravenously and orally at a total dose of greater than 3 g intraoperatively and postoperatively (RR 0.10, 95% CrI 0.02 to 0.55; low-certainty evidence). Aprotinin (RR 0.59, 95% CrI 0.36 to 0.96; low-certainty evidence), topical fibrin (RR 0.86, CrI 0.25 to 2.93; very low-certainty evidence) and EACA (RR 0.60, 95% CrI 0.29 to 1.27; very low-certainty evidence) were not shown to be as effective compared with TXA at reducing the risk of blood transfusion. We were unable to perform an NMA for our primary outcome all-cause mortality within 30 days of surgery due to the large number of studies with zero events, or because the outcome was not reported. In the NMA for deep vein thrombosis (DVT), we included 19 studies (2395 participants). Most studies examined TXA (27 arms, 64%). No studies assessed desmopressin, EACA or topical fibrin. We found that TXA given intravenously and orally at a total dose of greater than 3 g intraoperatively and postoperatively ranked the highest, with an anticipated absolute effect of 67 fewer DVTs per 1000 people (67 fewer to 34 more) (26% chance of ranking first) within the NMA (RR 0.16, 95% CrI 0.02 to 1.43; low-certainty evidence). This was followed by TXA given intravenously and intra-articularly at a total dose of 2 g pre-incision and intraoperatively (RR 0.21, 95% CrI 0.00 to 9.12; low-certainty evidence) and TXA given intravenously and intra-articularly, total dose greater than 3 g pre-incision, intraoperatively and postoperatively (RR 0.13, 95% CrI 0.01 to 3.11; low-certainty evidence). Aprotinin was not shown to be as effective compared with TXA (RR 0.67, 95% CrI 0.28 to 1.62; very low-certainty evidence). We were unable to perform an NMA for our secondary outcomes pulmonary embolism, myocardial infarction and CVA (stroke) within 30 days, mean number of transfusion episodes per person (up to 30 days), re-operation due to bleeding (within seven days), or length of hospital stay, due to the large number of studies with zero events, or because the outcome was not reported by enough studies to build a network. There are 30 ongoing trials planning to recruit 3776 participants, the majority examining TXA (26 trials). AUTHORS' CONCLUSIONS: We found that of all the interventions studied, TXA is probably the most effective intervention for preventing bleeding in people undergoing hip or knee replacement surgery. Aprotinin and EACA may not be as effective as TXA at preventing the need for allogeneic blood transfusion. We were not able to draw strong conclusions on the optimal dose, route and timing of administration of TXA. We found that TXA given at higher doses tended to rank higher in the treatment hierarchy, and we also found that it may be more beneficial to use a mixed route of administration (oral and intra-articular, oral and intravenous, or intravenous and intra-articular). Oral administration may be as effective as intravenous administration of TXA. We found little to no evidence of harm associated with higher doses of tranexamic acid in the risk of DVT. However, we are not able to definitively draw these conclusions based on the trials included within this review.

Antifibrinolytic and Adjunct Hemostatic Agents: The Pediatric Extracorporeal Membrane Oxygenation Anticoagulation CollaborativE Consensus Conference.

OBJECTIVES: To derive systematic-review informed, modified Delphi consensus regarding antifibrinolytic and adjunct hemostatic agents in neonates and children supported with extracorporeal membrane oxygenation (ECMO) for the Pediatric ECMO Anticoagulation CollaborativE consensus conference. DATA SOURCES: A structured literature search was performed using PubMed, EMBASE, and Cochrane Library (CENTRAL) databases from January 1988 to May 2021. STUDY SELECTION: Use of antifibrinolytics (epsilon-aminocaproic acid [EACA] or tranexamic acid), recombinant factor VII activated (rFVIIa), or topical hemostatic agents (THAs). DATA EXTRACTION: Two authors reviewed all citations independently, with a third independent reviewer resolving conflicts. Eleven references were used for data extraction and informed recommendations. Evidence tables were constructed using a standardized data extraction form. MEASUREMENTS AND MAIN RESULTS: Risk of bias was assessed using the Quality in Prognosis Studies tool. The evidence was evaluated using the Grading of Recommendations Assessment, Development, and Evaluation system. Forty-eight experts met over 2 years to develop evidence-based recommendations and, when evidence was lacking, expert-based consensus statements for the management of bleeding and thrombotic complications in pediatric ECMO patients. A web-based modified Delphi process was used to build consensus via the Research And Development/University of California Appropriateness Method. Consensus was defined as greater than 80% agreement. One weak recommendation and three consensus statements are presented. CONCLUSIONS: Evidence supporting recommendations for administration of antifibrinolytics (EACA or tranexamic acid), rFVIIa, and THAs were sparse and inconclusive. Much work remains to determine effective and safe usage strategies.

The tight junction protein claudin 6 is a potential target for patient-individualized treatment in esophageal and gastric adenocarcinoma and is associated with poor prognosis.

BACKGROUND: The prognosis of esophageal adenocarcinoma (EAC) and gastric adenocarcinoma (GAC) remains poor, and new therapeutic approaches are urgently needed. Claudin 6 (CLDN6) is an oncofetal antigen that is largely absent in healthy tissues and upregulated in several cancers, making it a promising therapeutical target. In this study, the expression of CLDN6 was assessed in an large Caucasian EAC and GAC cohort. METHODS: RNA-Seq data from 89 EACs and 371 GACs were obtained from The Cancer Genome Atlas project and EAC/GAC cases were stratified by CLDN6 mRNA expression based on a survival-associated cutoff. For groups with CLDN6 expression above or below this cutoff, differential gene expression analyses were performed using DESeq, and dysregulated biological pathways were identified using the Enrichr tool. Additionally, CLDN6 protein expression was assessed in more than 800 EACs and almost 600 GACs using a CLDN6-specific immunohistochemical antibody (clone 58-4B-2) that is currently used in Phase I/II trials to identify patients with CLDN6-positive tumors (NCT05262530; NCT04503278). The expression of CLDN6 was also correlated with histopathological parameters and overall survival (OS). RESULTS: EACs and GACs with high CLDN6 mRNA levels displayed an overexpression of pathways regulating the cell cycle, DNA replication, and receptor / extracellular matrix interactions. CLDN6 protein expression was associated with shorter OS in EAC and GAC, both in treatment-naïve subgroups and cohorts receiving neoadjuvant therapy. In multivariate analysis, CLDN6 protein expression was an independent adverse prognostic factor in EAC associated with a shorter OS (HR: 1.75; p = 0.01) and GAC (HR: 2.74; p = 0.028). CONCLUSIONS: High expression of CLDN6 mRNA is associated with the dysregulation of distinct biological pathways regulating cell growth, proliferation, and cell-matrix interactions. Clinically, the expression of CLDN6 protein is a valuable adverse prognostic marker in EAC and GAC.

An interlaboratory capillary zone electrophoresis-UV study of various monoclonal antibodies, instruments, and ε-aminocaproic acid lots.

Capillary zone electrophoresis ultraviolet (CZE-UV) has become increasingly popular for the charge heterogeneity determination of mAbs and vaccines. The ε-aminocaproic acid (eACA) CZE-UV method has been used as a rapid platform method. However, in the last years, several issues have been observed, for example, loss in electrophoretic resolution or baseline drifts. Evaluating the role of eACA on the reported issues, various laboratories were requested to provide their routinely used eACA CZE-UV methods, and background electrolyte compositions. Although every laboratory claimed to use the He et al. eACA CZE-UV method, most methods actually deviate from He's. Subsequently, a detailed interlaboratory study was designed wherein two commercially available mAbs (Waters' Mass Check Standard mAb [pI 7] and NISTmAb [pI 9]) were provided to each laboratory, along with two detailed eACA CZE-UV protocols for a short-end, high-speed, and a long-end, high-resolution method. Ten laboratories participated each using their own instruments, and commodities, showing excellence method performance (relative standard deviations [RSDs] of percent time-corrected main peak areas from 0.2% to 1.9%, and RSDs of migration times from 0.7% to 1.8% [n = 50 per laboratory], analysis times in some cases as short as 2.5 min). This study clarified that eACA is not the main reason for the abovementioned variations.

Epsilon aminocaproic acid is associated with acute kidney injury after life-threatening hemorrhage in children.

BACKGROUND: Antifibrinolytic medications have been associated with reduced mortality in pediatric hemorrhage but may contribute to adverse events such as acute kidney injury (AKI). STUDY DESIGN AND METHODS: We conducted a secondary analysis of the MAssive Transfusion in Children (MATIC), a prospectively collected database of children with life-threatening hemorrhage (LTH), and evaluated for risk of adverse events with either antifibrinolytic treatment, epsilon aminocaproic acid (EACA) or tranexamic acid (TXA). The primary outcome was AKI and secondary outcomes were acute respiratory distress syndrome (ARDS) and sepsis. RESULTS: Of 448 children included, median (interquartile range) age was 7 (2-15) years, 55% were male, and LTH etiology was 46% trauma, 34% operative, and 20% medical. Three hundred and ninety-three patients did not receive an antifibrinolytic (88%); 37 (8%) received TXA and 18 (4%) received EACA. Sixty-seven (17.1%) patients in the no antifibrinolytic group developed AKI, 6 (16.2%) patients in the TXA group, and 9 (50%) patients in the EACA group (p = .002). After adjusting for cardiothoracic surgery, cyanotic heart disease, preexisting renal disease, lowest hemoglobin pre-LTH, and total weight-adjusted transfusion volume during the LTH, the EACA group had increased risk of AKI (adjusted odds ratio 3.3 [95% CI: 1.0-10.3]) compared to no antifibrinolytic. TXA was not associated with AKI. Neither antifibrinolytic treatment was associated with ARDS or sepsis. CONCLUSION: Administration of EACA during LTH may increase the risk of AKI. Additional studies are needed to compare the risk of AKI between EACA and TXA in pediatric patients.

Virtual screening of carboxylic acid reductases for biocatalytic synthesis of 6-aminocaproic acid and 1,6-hexamethylenediamine.

The key precursors for nylon synthesis, that is, 6-aminocaproic acid (6-ACA) and 1,6-hexamethylenediamine (HMD), are produced from petroleum-based feedstocks. A sustainable biocatalytic alternative method from bio-based adipic acid has been demonstrated recently. However, the low efficiency and specificity of carboxylic acid reductases (CARs) used in the process hampers its further application. Herein, we describe a highly accurate protein structure prediction-based virtual screening method for the discovery of new CARs, which relies on near attack conformation frequency and the Rosetta Energy Score. Through virtual screening and functional detection, five new CARs were selected, each with a broad substrate scope and the highest activities toward various di- and ω-aminated carboxylic acids. Compared with the reported CARs, KiCAR was highly specific with regard to adipic acid without detectable activity to 6-ACA, indicating a potential for 6-ACA biosynthesis. In addition, MabCAR3 had a lower Km with regard to 6-ACA than the previously validated CAR MAB4714, resulting in twice conversion in the enzymatic cascade synthesis of HMD. The present work highlights the use of structure-based virtual screening for the rapid discovery of pertinent new biocatalysts.

Medical interventions for traumatic hyphema.

BACKGROUND: Traumatic hyphema is the entry of blood into the anterior chamber, the space between the cornea and iris, following significant injury to the eye. Hyphema may be associated with significant complications that uncommonly cause permanent vision loss. Complications include elevated intraocular pressure, corneal blood staining, anterior and posterior synechiae, and optic nerve atrophy. People with sickle cell trait or disease may be particularly susceptible to increases in intraocular pressure and optic atrophy. Rebleeding is associated with an increase in the rate and severity of complications. OBJECTIVES: To assess the effectiveness of various medical interventions in the management of traumatic hyphema. SEARCH METHODS: We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (which contains the Cochrane Eyes and Vision Trials Register) (2022, Issue 3); MEDLINE Ovid; Embase.com; PubMed (1948 to March 2022); the ISRCTN registry; ClinicalTrials.gov; and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP). The last date of the search was 22 March 2022. SELECTION CRITERIA: Two review authors independently assessed the titles and abstracts of all reports identified by the electronic and manual searches. We included randomized and quasi-randomized trials that compared various medical (non-surgical) interventions versus other medical interventions or control groups for the treatment of traumatic hyphema following closed-globe trauma. We applied no restrictions on age, gender, severity of the closed-globe trauma, or level of visual acuity at time of enrollment. DATA COLLECTION AND ANALYSIS: We used standard methodological procedures expected by Cochrane and assessed the certainty of evidence using GRADE. MAIN RESULTS: We included 23 randomized and seven quasi-randomized studies with a total of 2969 participants. Interventions included antifibrinolytic agents (systemic and topical aminocaproic acid, tranexamic acid, and aminomethylbenzoic acid), corticosteroids (systemic and topical), cycloplegics, miotics, aspirin, conjugated estrogens, traditional Chinese medicine, monocular versus bilateral patching, elevation of the head, and bed rest. We found no evidence of an effect on visual acuity for any intervention, whether measured within two weeks (short term) or for longer periods. In a meta-analysis of two trials, we found no evidence of an effect of aminocaproic acid on long-term visual acuity (RR 1.03, 95% confidence interval (CI) 0.82 to 1.29) or final visual acuity measured up to three years after the hyphema (RR 1.05, 95% CI 0.93 to 1.18). Oral tranexamic acid appeared to provide little to no benefit on visual acuity in four trials (RR 1.12, 95% CI 1.00 to 1.25). The remaining trials evaluated the effects of various interventions on short-term visual acuity; none of these interventions was measured in more than one trial. No intervention showed a statistically significant effect (RRs ranged from 0.75 to 1.10). Similarly, visual acuity measured for longer periods in four trials evaluating different interventions was also not statistically significant (RRs ranged from 0.82 to 1.02). The evidence supporting these findings was of low or very low certainty. Systemic aminocaproic acid reduced the rate of recurrent hemorrhage (RR 0.28, 95% CI 0.13 to 0.60), as assessed in six trials with 330 participants. A sensitivity analysis omitting two studies not using an intention-to-treat analysis reduced the strength of the evidence (RR 0.43, 95% CI 0.17 to 1.08). We obtained similar results for topical aminocaproic acid (RR 0.48, 95% CI 0.20 to 1.10) in two trials with 131 participants. We assessed the certainty of the evidence as low. Systemic tranexamic acid had a significant effect in reducing the rate of secondary hemorrhage (RR 0.33, 95% CI 0.21 to 0.53) in seven trials with 754 participants, as did aminomethylbenzoic acid (RR 0.10, 95% CI 0.02 to 0.41), as reported in one study. Evidence to support an associated reduction in risk of complications from secondary hemorrhage (i.e. corneal blood staining, peripheral anterior synechiae, elevated intraocular pressure, and development of optic atrophy) by antifibrinolytics was limited by the small number of these events. Use of aminocaproic acid was associated with increased nausea, vomiting, and other adverse events compared with placebo. We found no evidence of an effect on the number of adverse events with the use of systemic versus topical aminocaproic acid or with standard versus lower drug dose.  The number of days for the primary hyphema to resolve appeared to be longer with the use of systemic aminocaproic acid compared with no use, but this outcome was not altered by any other intervention. The available evidence on usage of systemic or topical corticosteroids, cycloplegics, or aspirin in traumatic hyphema was limited due to the small numbers of participants and events in the trials. We found no evidence of an effect between a single versus binocular patch on the risk of secondary hemorrhage or time to rebleed. We also found no evidence of an effect on the risk of secondary hemorrhage between ambulation and complete bed rest. AUTHORS' CONCLUSIONS: We found no evidence of an effect on visual acuity of any of the interventions evaluated in this review. Although the evidence was limited, people with traumatic hyphema who receive aminocaproic acid or tranexamic acid are less likely to experience secondary hemorrhage. However, hyphema took longer to clear in people treated with systemic aminocaproic acid. There is no good evidence to support the use of antifibrinolytic agents in the management of traumatic hyphema, other than possibly to reduce the rate of secondary hemorrhage. The potentially long-term deleterious effects of secondary hemorrhage are unknown. Similarly, there is no evidence to support the use of corticosteroids, cycloplegics, or non-drug interventions (such as patching, bed rest, or head elevation) in the management of traumatic hyphema. As these multiple interventions are rarely used in isolation, further research to assess the additive effect of these interventions might be of value.

Efficacy and safety of using aminocaproic acid and tranexamic acid during the perioperative period for treating trochanteric fractures in elderly femurs.

BACKGROUND: Tranexamic acid (TXA) has long been the antifibrinolytic hemostatic drug of choice for orthopedic surgery. In recent years, the hemostatic effect of epsilon aminocaproic acid (EACA) has gradually been recognized by orthopedic surgeons and has begun to be used in hip and knee arthroplasty with little mention of the comparison of these two drugs; Therefore, this study compared the efficacy and safety of EACA and TXA in the perioperative period of elderly patients with trochanteric fractures to verify whether EAC could be a "qualified alternative" to TXA and to provide theoretical support for the clinical application of TXA. METHODS: Two hundred and forty-three patients who received proximal femoral nail antirotation (PFNA) for trochanteric fractures from January 2021 to March 2022 at our institution were included and divided into the EACA group (n = 146) and the TXA group. (n = 97) determined by the drugs used in the perioperative period The main observations were blood loss and blood transfusion.The second second outcome was blood routine, coagulation, Hospital complications and complications after discharge. RESULTS: The perioperative EACA patients had significantly lower significant blood loss (DBL) than the TXA group (p < 0.0001) and statistically significant lower C-reactive protein in the EACA group than in the TXA group on postoperative day 1 (p = 0.022). Patients on perioperative TXA had better postoperative day one (p = 0.002) and postoperative day five erythrocyte width than the EACA group (p = 0.004). However, there was no statistically significant difference between the two groups in the remaining indicators in both drugs: blood items, coagulation indicators, blood loss, blood transfusion, length of hospital(LOH), total hospital expense, and postoperative complications (p > 0.05). CONCLUSION: The hemostatic effects and safety of EACA and TXA in the perioperative application of trochanteric fractures in the elderly are essentially similar, and EACA can be considered for use as an alternative to TXA, increasing the flexibility of physicians to use it in the clinical setting. However, the limited sample size included necessitated a high-quality, large sample of clinical studies and long-term follow-up.

Pharmacokinetics of aminocaproic acid in thoroughbred horses.

The antifibrinolytic agent aminocaproic acid (ACA) is occasionally used prior to episodes of intense training in racehorses suffering from exercise-induced pulmonary hemorrhage. Although a previous study indicated that the drug is cleared rapidly in horses, some racetrack practitioners claim that recent adverse analytical findings for ACA in postrace samples were from ACA administrations 5-7 days before the race. The purpose of this study was to re-examine the pharmacokinetics of ACA in horses to address this apparent conundrum. Eight exercise-conditioned thoroughbred horses were administered 5 g of ACA IV, and blood and urine samples were collected at pre-determined time points prior to drug administration and for up to 168 h after dosing. Concentrations of ACA in the serum and urine samples were determined by LC-MS/MS. The pharmacokinetics of ACA in serum were best described by a three-compartment model with a terminal elimination half-life of 24.2 ± 2.9 h. After dosing, ACA was above the lower limit of detection (1 ng/mL for serum and 10 ng/mL for urine) in all serum and urine samples at all time points. In a similar manner, ACA was above the lower limit of quantification (LLOQ; 10 ng/mL for serum and 100 ng/mL for urine) in all serum and urine samples collected from all horses from 0.5 to 120 h post dosing. In six of the eight horses, ACA was above the LLOQ 168 h after dosing in serum and urine samples. LC-MS/MS methodology is the industry standard for testing of samples collected from racehorses with the purpose of controlling the use of medications and performance altering substances. The improved sensitivity of the analytical procedure used in the present study allowed the detection of a prolonged terminal elimination phase of ACA in horses that had not previously been described. Currently, most racing jurisdictions have not adopted a permitted concentration or threshold for ACA in postrace samples, and therefore veterinarians need to allow for an extended withdrawal time of a minimum of 11 days after the administration of ACA to racehorses to substantially reduce the risk of adverse analytical findings of ACA in postrace samples.

Comprehensive Regulation of Liquid-Liquid Phase Separation of Polypeptides.

The elucidation of the molecular driving forces responsible for Liquid-liquid Phase Separation (LLPS) of proteins and nucleic acids within living cells is crucial for understanding its biological functions and its role in related diseases. In the present study, we investigated the regulation of LLPS in a series of polypeptides with repetitive proline and arginine (PR) sequences by modifying their length and the salt concentration in the solution. Our findings indicate that higher salt concentrations are necessary for LLPS of repetitive PR peptides longer than eight PRs, which emerges as a threshold value. To pinpoint the molecular forces driving the LLPS in peptides, we sequentially introduced various concentrations of hydrophobic disruptors, such as 1,6-hexanediol, and electrostatic regulators, such as ethyl alcohol and 6-Aminocaproic acid. We further modulated the electrostatic interaction by introducing ethyl alcohol and 6-Aminocaproic acid to alter the dielectric constant of the solution. The inclusion of ethyl alcohol intensified the electrostatic interaction between arginine molecules, facilitating LLPS of PR15, while 6-Aminocaproic acid yielded the reverse effect. We deduced that the phase separation in peptide systems is conjointly driven by hydrophobicity and electrostatic interactions. These insights can guide the regulation of LLPS in other peptide and protein systems, and could be pivotal in addressing abnormal aggregations of proteins and nucleic acids.

Evaluation of Therapeutic Use of Antifibrinolytics in Cats.

Limited data are available regarding the use of the antifibrinolytic drugs tranexamic acid (TXA) and epsilon aminocaproic acid (EACA) in cats. This study aimed to evaluate the indications for the use of TXA and EACA in cats and to describe dosing regimens used, occurrence of adverse events, and patient outcomes. This was a retrospective multicenter study. Medical databases were searched for feline patients billed for TXA or EACA between 2015 and 2021. Thirty-five cats met the inclusion criteria; 86% received TXA and 14% received EACA. The most common indication was nontraumatic hemorrhage (54%), followed by traumatic hemorrhage (17%) and elective surgery (11%). The median dose was 10 mg/kg for TXA and 50 mg/kg for EACA. Overall, 52% of cats survived to discharge. Potential adverse events were noted in 7/35 (20%) patients. Of these, 29% survived to discharge. No standardized dosing regimen was identified; rather, dose, dosing interval, and duration of administration varied markedly between patients. Administration was potentially associated with severe adverse events, although the retrospective design makes it difficult to establish a causal association with antifibrinolytic use. This study provides a base for future prospective studies by giving an insight into the use of antifibrinolytic drugs in cats.

Use of Antifibrinolytics in Pediatric Life-Threatening Hemorrhage: A Prospective Observational Multicenter Study.

OBJECTIVES: To assess the impact of antifibrinolytics in children with life-threatening hemorrhage. DESIGN: Secondary analysis of the MAssive Transfusion epidemiology and outcomes In Children study dataset, a prospective observational study of children with life-threatening bleeding events. SETTING: Twenty-four children's hospitals in the United States, Canada, and Italy. PATIENTS: Children 0-17 years old who received greater than 40 mL/kg of total blood products over 6 hours or were transfused under activation of massive transfusion protocol. INTERVENTION/EXPOSURE: Children were compared according to receipt of antifibrinolytic medication (tranexamic acid or aminocaproic acid) during the bleeding event. MEASUREMENTS AND MAIN RESULTS: Patient characteristics, medications administered, and clinical outcomes were analyzed using Cox proportional hazard and Kaplan-Meier survival analysis. The primary outcome was 24-hour mortality. Of 449 patients analyzed, median age was 7 years (2-15 yr), and 55% were male. The etiology of bleeding was 46% traumatic, 34% operative, and 20% medical. Twelve percent received antifibrinolytic medication during the bleeding event (n = 54 unique subjects; n = 18 epsilon aminocaproic acid, n = 35 tranexamic acid, and n = 1 both). The antifibrinolytic group was comparable with the nonantifibrinolytic group on baseline demographic and physiologic parameters; the antifibrinolytic group had longer massive transfusion protocol duration, received greater volume blood products, and received factor VII more frequently. In the antifibrinolytic group, there was significantly less 6-hour mortality overall (6% vs 17%; p = 0.04) and less 6-hour mortality due to hemorrhage (4% vs 14%; p = 0.04). After adjusting for age, bleeding etiology, Pediatric Risk of Mortality score, and plasma deficit, the antifibrinolytic group had decreased mortality at 6- and 24-hour postbleed (adjusted odds ratio, 0.29 [95% CI, 0.09-0.93]; p = 0.04 and adjusted odds ratio, 0.45 [95% CI, 0.21-0.98]; p = 0.04, respectively). CONCLUSIONS: Administration of antifibrinolytic medications during the life-threatening event was independently associated with improved 6- and 24-hour survivals in bleeding children. Consideration should be given to use of antifibrinolytics in pediatric patients with life-threatening hemorrhage.

Blood Loss and Transfusion in a Pediatric Scoliosis Surgery Cohort in the Antifibrinolytic Era.

Children and adolescents undergoing posterior spinal fusion for scoliosis experience high rates of bleeding and blood product transfusion. Antifibrinolytic therapy is one key strategy to decrease blood loss and transfusion in pediatric scoliosis surgery. Here we review 172 pediatric scoliosis patients (birth to 21 y) who underwent posterior spinal fusion at our institution from 2017 to 2018. We reported rates of blood loss and transfusion, compared patients receiving tranexamic acid to a ε-aminocaproic acid, and evaluated antifibrinolytic agent and laboratory parameters as predictors of blood loss and transfusion. Intraoperatively, 62% received tranexamic acid and 38% received ε-aminocaproic acid. Overall, blood loss (mean intraoperative estimated blood loss=14.9±9.7 mL/kg, 22% with clinically significant blood loss [>20 mL/kg], and mean calculated hemoglobin mass loss=175.9±70.1 g) and transfusion rates (15% with intraoperative allogeneic red blood cell transfusion and mean intraoperative allogeneic red blood cell transfusion volume=12.5±7.1 mL/kg) were similar to previous cohorts studying intraoperative antifibrinolytics. There was no difference in intraoperative estimated blood loss, clinically significant blood loss, calculated hemoglobin mass loss, or transfusion rates between the antifibrinolytic groups. Antifibrinolytic choice was not predictive of blood loss or transfusion. Routine hematologic laboratory parameters and antifibrinolytic choice were insufficient to predict blood loss or other outcomes. Future prospective laboratory-based studies may provide a more comprehensive model of surgical-induced coagulopathy in scoliosis surgery and provide a better tool for predicting blood loss and improving outcomes.

Antifibrinolytic Drugs for the Prevention of Bleeding in Pediatric Cardiac Surgery on Cardiopulmonary Bypass: A Systematic Review and Meta-analysis.

BACKGROUND: Bleeding is one of the commonest complications affecting children undergoing cardiac surgery on cardiopulmonary bypass. Antifibrinolytic drugs are part of a multifaceted approach aimed at reducing bleeding, though sufficiently sized pediatric studies are sparse, and dosing algorithms are heterogeneous. Our objective was to evaluate the efficacy and safety of antifibrinolytic agents as well as the effectiveness of different dosing regimens in pediatric cardiac surgery using cardiopulmonary bypass. METHODS: We performed a systematic review and meta-analysis evaluating randomized controlled trials published between 1980 and 2019, identified by searching the databases MEDLINE, EMBASE, PubMed, and CENTRAL. All studies investigating patients <18 years of age without underlying hematological disorders were included. The primary outcome was postoperative bleeding; secondary end points included blood product transfusion, mortality, and safety (thromboses, anaphylaxis, renal or neurological dysfunction, and seizures). Different dosing regimens were compared. Studies were dual appraised, outcomes were reported descriptively and, if appropriate, quantitatively using the Review Manager 5 (REVMAN 5) software (The Cochrane Collaboration). RESULTS: Thirty of 209 articles were included, evaluating the following drugs versus control: aprotinin n = 14, tranexamic acid (TXA) n = 12, and epsilon-aminocaproic acid (EACA) n = 4. The number of participants per intervention group ranged from 11 to 100 (median, 25; interquartile range [IQR], 20.5) with a wide age span (mean, 13 days to 5.8 years) and weight range (mean, 3.1-26.3 kg). Methodological quality was low to moderate.All agents reduced mean 24-hour blood loss compared to control: aprotinin by 6.0 mL/kg (95% confidence interval [CI], -9.1 to -3.0; P = .0001), TXA by 9.0 mL/kg (95% CI, -11.3 to -6.8; P < .00001), and EACA by 10.5 mL/kg (95% CI, -21.1 to 0.0; P = .05). Heterogeneity was low for TXA (I2 = 29%; P = .19), moderate for aprotinin (I2 = 41%; P = .11), and high for EACA (I2 = 95%; P < .00001). All agents also reduced 24-hour blood product transfusion. There was no clear dose-response effect for TXA nor aprotinin. Studies were underpowered to detect significant differences in mortality, thromboses, anaphylaxis, and renal or neurological dysfunction. CONCLUSIONS: The available data demonstrate efficacy for all 3 antifibrinolytic drugs. Therefore, the agent with the most favorable safety profile should be used. As sufficient data are lacking, large comparative trials are warranted to assess the relative safety and appropriate dosing regimens in pediatrics.

Prophylactic Use of Antifibrinolytics During Pediatric Cardiac Surgery With Cardiopulmonary Bypass on Postoperative Bleeding and Transfusion: A Systematic Review and Meta-Analysis.

OBJECTIVES: To determine the effect of intraoperative antifibrinolytics, including tranexamic acid (TXA), aminocaproic acid (EACA), or aprotinin, on bleeding in children undergoing cardiac surgery with cardiopulmonary bypass (CPB). DATA SOURCES: Relevant articles were systematically searched from Ovid MEDLINE, Ovid EMBASE, CINAHL, Cochrane Library, and Web of Science to November 15, 2021. STUDY SELECTION: Abstracts were screened, and full texts were reviewed using predetermined inclusion and exclusion criteria using the Preferred Reporting Items for Systematic Reviews and Meta-analyses reporting guideline. DATA EXTRACTION: A standardized data extraction tool was used. DATA SYNTHESIS: Sixty-eight studies including 28,735 patients were analyzed. TXA compared with placebo resulted in a mean decrease in chest tube output of 9.1 mL/kg (95% CI, 6.0-12.3 mL/kg), I2 equals to 65.2%, p value of less than 0.001, platelet requirement of 2.9 mL/kg (95% CI, 0.1-5.8 mL/kg), I2 =72.5%, p value less than 0.001 and plasma requirement of 4.0 mL/kg (95% CI, 0.6-7.2 mL/kg), I2 equals to 94.5%, p value less than0.001. Aprotinin compared with placebo resulted in a mean decrease in chest tube output of 4.3 mL/kg (2.4-6.2 mL/kg), I2 equals to 66.3%, p value of less than 0.001, platelet transfusion of 4.6 mL/kg (95% CI, 0.6-8.6 mL/kg), I2 equals to 93.6%, p value of less than 0.001, and plasma transfusion of 7.7 mL/kg (95% CI, 2.1-13.2 mL/kg), I2 equals to 95.3%, p value of less than 0.001. EACA compared with placebo resulted in a mean decrease in chest tube output of 9.2 mL/kg (2.3-21.0 mL/kg), I2 equals to 96.4%, p value of less than 0.001, RBC transfusion of 7.2 mL/kg (95% CI, 2.4-12.1 mL/kg), I2 equals to 94.5%, p value equals to 0.002, and platelet transfusion of 10.7 mL/kg (95% CI, 2.9-18.5 mL/kg), I2 equals to 0%, p value of less than 0.001. No statistical difference was observed in chest tube output when TXA was compared with aprotinin. Subgroup analysis of cyanotic patients showed a significant decrease in chest tube output, platelet requirement, and plasma requirement for patients receiving aprotinin. Overall, the quality of evidence was moderate. CONCLUSIONS: Antifibrinolytics are effective at decreasing blood loss and blood product requirement in children undergoing cardiac surgery with CPB although the quality of evidence is only moderate.

Effectiveness and Safety of E-aminocaproic Acid in Overall and Less-Invasive Cardiac Surgeries.

OBJECTIVES: To examine E-aminocaproic acid effectiveness in reducing transfusion requirements in overall and less-invasive cardiac surgery, and to assess its safety. DESIGN: Retrospective cohort study. SETTING: Single-center tertiary academic medical center. PARTICIPANTS: A total of 19,111 adult patients who underwent elective surgery requiring cardiopulmonary bypass from January 1, 2008, through December 31, 2016. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Propensity matching was used to create well-balanced groups and separately compare both overall cohort and less-invasive surgery with and without E-aminocaproic acid. Supplementary zero-inflated negative binomial regression analysis was used because outcome data were zero-inflated. Effectiveness was assessed by transfusion requirements, and safety by comparison of in-hospital outcomes. In the overall cohort, patients receiving E-aminocaproic acid received fewer red blood cells postoperatively and fewer intra- and postoperativel blood products. In a less-invasive cohort, there was no significant difference in red blood cell transfusion either intra- or postoperatively, but the E-aminocaproic group received fewer intra- and postoperative platelets, intraoperative cryoprecipitate, and postoperative plasma. There were no significant differences for in-hospital outcomes in both less-invasive and overall cohorts. CONCLUSIONS: The reduction of postoperative red blood cell requirement observed when analyzing the overall cohort did not translate to less-invasive cardiac surgery in the authors' patient population; however, both overall and less-invasive cohorts had lower requirements for other blood components with E-aminocaproic acid. There was no association with major Society of thoracic surgeons (STS)-defined morbidity and mortality in both groups.

Ultrasmall polymer-coated cerium oxide nanoparticles as a traumatic brain injury therapy.

No medication has been approved for secondary injuries after traumatic brain injury (TBI). While free radicals are considered a major mediator of secondary injury, conventional antioxidants only have modest clinical efficacy. Here, we synthesized CX201 consisting of core cerium oxide nanoparticles coated with 6-aminocaproic acid and polyvinylpyrrolidone in aqueous phase. CX201 with 3.49 ± 1.11 nm of core and 6.49 ± 0.56 nm of hydrodynamic diameter showed multi-enzymatic antioxidant function. Owing to its excellent physiological stability and cell viability, CX201 had a neuroprotective effect in vitro. In a TBI animal model, an investigator-blinded randomized experiment showed a single intravenously injected CX201 significantly improved functional recovery compared to the control. CX201 reduced lipid peroxidation and inflammatory cell recruitment at the damaged brain. These suggest ultrasmall CX201 can efficiently reduce secondary brain injuries after TBI. Given the absence of current therapies, CX201 may be proposed as a novel therapeutic strategy for TBI.

Safety of antifibrinolytics in 6583 pediatric patients having craniosynostosis surgery: A decade of data reported from the multicenter Pediatric Craniofacial Collaborative Group.

BACKGROUND: Antifibrinolytics such as tranexamic acid and epsilon-aminocaproic acid are effective at reducing blood loss and transfusion in pediatric patients having craniofacial surgery. The Pediatric Craniofacial Collaborative Group has previously reported low rates of seizures and thromboembolic events (equal to no antifibrinolytic given) in open craniofacial surgery. AIMS: To query the Pediatric Craniofacial Collaborative Group database to provide an updated antifibrinolytic safety profile in children given that antifibrinolytics have become recommended standard of care in this surgical population. Additionally, we include the population of younger infants having minimally invasive procedures. METHODS: Patients in the Pediatric Craniofacial Collaborative Group registry between June 2012 and March 2021 having open craniofacial surgery (fronto-orbital advancement, mid and posterior vault, total cranial vault remodeling, intracranial LeFort III monobloc), endoscopic cranial suture release, and spring mediated cranioplasty were included. The primary outcome is the rate of postoperative complications possibly attributable to antifibrinolytic use (seizures, seizure-like activity, and thromboembolic events) in infants and children undergoing craniosynostosis surgery who did or did not receive antifibrinolytics. RESULTS: Forty-five institutions reporting 6583 patients were included. The overall seizure rate was 0.24% (95% CI: 0.14, 0.39%), with 0.20% in the no Antifibrinolytic group and 0.26% in the combined Antifibrinolytic group, with no statistically reported difference. Comparing seizure rates between tranexamic acid (0.22%) and epsilon-aminocaproic acid (0.44%), there was no statistically significant difference (odds ratio = 2.0; 95% CI: 0.6, 6.7; p = .257). Seizure rate was higher in patients greater than 6 months (0.30% vs. 0.18%; p = .327), patients undergoing open procedures (0.30% vs. 0.06%; p = .141), and syndromic patients (0.70% vs. 0.19%; p = .009). CONCLUSIONS: This multicenter international experience of pediatric craniofacial surgery reports no increase in seizures or thromboembolic events in those that received antifibrinolytics (tranexamic acid and epsilon-aminocaproic acid) versus those that did not. This report provides further evidence of antifibrinolytic safety. We recommend following pharmacokinetic-based dosing guidelines for administration.

Tranexamic versus aminocaproic acids in patients with total hip arthroplasty: a retrospective study.

BACKGROUND: Recently, tranexamic acid (TXA) and epsilon aminocaproic acid (EACA) have been applied in total hip arthroplasty (THA). However, doubts in clinicians' minds about which medicine is more efficient and economical in THA need to be clarified. Therefore, this study compared the efficacy and cost of the intraoperative administration of TXA and EACA per surgery in decreasing perioperative blood transfusion rates in THA. METHODS:  This study enrolled patients who underwent THA between January 2019 to December 2020. A total of 295 patients were retrospectively divided to receive topical combined with intravenous TXA (n = 94), EACA (n = 97) or control (n = 104). The primary endpoints included transfusions, estimated perioperative blood loss, cost per patient and the drop in the haemoglobin and haematocrit levels. RESULTS: Patients who received EACA had greater total blood loss, blood transfusion rates, changes in HGB levels and mean cost of blood transfusion per patient (P < 0.05) compared with patients who received TXA. In addition, both TXA and EACA groups had significantly fewer perioperative blood loss, blood transfusion, operation time and changes in haemoglobin and haematocrit levels than the control group (P < 0.05). Cost savings in the TXA and EACA groups were 736.00 RMB and 408.00 RMB per patient, respectively. CONCLUSIONS: The application of perioperative antifibrinolytics notably reduces the need for perioperative blood transfusions. What's more, this study demonstrated that TXA is superior to EACA for decreasing blood loss and transfusion rates while at a lower cost per surgery. These results indicate that TXA may be the optimum antifibrinolytics for THA in Chinese area rather than EACA.