Remimazolam: A Retrospective Study of Initial Safety and Recovery Data in Diverse Procedural Sedation.

PURPOSE: The new ultra-short-acting benzodiazepine, remimazolam, offers a pharmacokinetic and pharmacodynamic advantage over commonly used procedural sedation medication. This retrospective study explored the real-world utilization of remimazolam during procedural sedation to support the development of a nurse sedation protocol. The primary outcome was to identify associations between recovery time, adverse reactions, and dose-response in expanded patient populations. METHODS: This study reviewed charts of 292 adult patients from 3 hospitals within one institution who received remimazolam during procedural sedation between June 1, 2021 and December 31, 2021. Data were analyzed using logistic and linear regression. FINDINGS: The median time to alert in patients receiving remimazolam alone was 12 minutes (interquartile range 10, 17) and increased when additional sedation medications were utilized. Receiving additional sedative medication significantly increased the odds of hypoxia (OR 2.77, 95% CI 1.30-5.91, P = 0.008) after adjusting for body mass index (BMI), American Society of Anesthesiologists physical status (ASA-PS), and total remimazolam dose. There was a 25% increase in odds of experiencing hypoxia for every 5 kg/m2 increase in BMI (95% CI 1.01-1.54, P = 0.037). IMPLICATIONS: Remimazolam presents as a promising option for nurse procedural sedation, offering minimal impact on hemodynamics and respirations, quick recovery, and no residual sedative effects.

Lymphatic Mapping with Contrast-enhanced Ultrasound for Lymphaticovenous Anastomosis Surgery: How We Do It.

Lymphaticovenous anastomosis (LVA) surgery is an effective surgery for the treatment of lymphedema in the extremities. Indocyanine green lymphography is the reference standard for visualizing lymphatics for LVA surgery, but it has several limitations; most notably, superficial dermal congestion can mask deeper lymphatic vessels. To overcome the limitations, we add contrast-enhanced ultrasound (CEUS) lymphography. We have previously reported that CEUS lymphography can identify lymphatic vessels for LVA surgery that indocyanine green lymphography does not. Here, we describe how we perform CEUS lymphography, including workflow, technique, and documentation. Before informed consent, the patient must be screened for possible adverse reactions to microbubbles. The procedure involves multiple intradermal injections of the microbubble agent at various sites along the extremity. After each injection, imaging for microbubble uptake by lymphatic vessels is performed using an ultrasound scanner with contrast-specific software. We use sulfur hexafluoride lipid-type A microspheres (Lumason/SonoVue; Bracco Suisse SA), but we are investigating the performance of other Food & Drug Administration-approved microbubble agents for CEUS lymphography. Having a systematic approach to marking the skin can mitigate the hindrance of marking over ultrasound coupling gel. Another benefit of CEUS lymphography is the rapid identification of neighboring veins compatible in size and location for anastomosis. We hold regular scheduled multidisciplinary meetings for coordination of care, discussion of outcomes, quality assurance, and ongoing innovation.

Activated Prothrombin Complex Concentrate in Pediatric Cardiac Patients, Our Early Experience.

BACKGROUND: Pediatric cardiac surgery is associated with abnormal coagulation, bleeding, and nearly ubiquitous transfusions. With the popularization of patient blood management, attempts are being made to decrease liberal transfusions by administering prothrombin complex concentrates (PCCs). The safety and efficacy of PCCs in adult cardiac surgery has been studied extensively, but only few reports address this in children. We performed an observational study focused on transfusion requirements after off-label use of activated PCC Factor Eight Inhibitor Bypassing Activity (FEIBA) as an adjunct to post-cardiopulmonary bypass (CPB) hemostatic protocol. METHODS: We reviewed the medical records of children ≤15 kg undergoing cardiac operations with CPB between May 2018 and March 2022. A propensity score (PS) analysis was performed to identify matched pairs of patients who did and did not receive FEIBA. RESULTS: Out of 210 patients who met the inclusion criteria, 44 patients received FEIBA. Propensity score-based analysis identified 40 matched pairs of patients with similar baseline characteristics. There was no statistically significant difference in the primary outcome-the volume of transfusion after CPB, which included all allogeneic blood products and salvaged washed red cells administered after protamine. Specifically, FEIBA patients were transfused 28 (22-34) mL/kg and controls were transfused 22 (11-49) mL/kg, P = .989. Upon arrival to ICU, the FEIBA group averaged an 8% lower international normalized ratio, compared with the controls (P = .009) and a 1.08 g/dL higher hemoglobin (P = .050). Neither difference remained significant on POD 1. CONCLUSIONS: In this exploratory study, we found no change in transfusion requirements after CPB despite FEIBA administration.

Serial virus filtration: A case study evaluating the product-dependent impact of control strategies on process efficiency.

The production of biopharmaceutical products carries an inherent risk of contamination by adventitious viruses. Historically, these manufacturing processes have incorporated a dedicated virus filtration step to ensure product safety. However, challenging process conditions can lead to passage of small viruses to the permeate pool and an overall decrease in the desired virus logarithmic reduction value (LRV) for the process. The implementation of serial virus filtration has improved the robustness of such processes, albeit concerns about increased operating times and process complexity have limited its implementation. This work focused on optimizing a serial filtration process and identifying process control strategies to provide maximum efficiency while ensuring proper controls for process complexity. Constant TMP was identified as the optimal control strategy, which combined with the optimal filter ratio, resulted in a robust and faster virus filtration process. To demonstrate this hypothesis, data with two filters connected in series (1:1 filter ratio) are presented for a representative non-fouling molecule. Similarly, for a fouling product, the optimal setup was a combination of a filter connected in series to two filters operated in parallel (2:1 filter ratio). The optimized filter ratios bring cost- and time-savings benefits to the virus filtration step, thereby offering improved productivity. The results of risk and cost analyses performed as part of this study combined with the control strategy, offer companies a toolbox of strategies to accommodate products with different filterability profiles in their downstream processes. This work demonstrates that the safety advantages of performing filters in series can be achieved with minimal increases in time, cost, and risk.

Evaluation of Direct Oral Anticoagulant Reversal Agents in Intracranial Hemorrhage: A Systematic Review and Meta-analysis.

Importance: Direct oral anticoagulant (DOAC)-associated intracranial hemorrhage (ICH) has high morbidity and mortality. The safety and outcome data of DOAC reversal agents in ICH are limited. Objective: To evaluate the safety and outcomes of DOAC reversal agents among patients with ICH. Data Sources: PubMed, MEDLINE, The Cochrane Library, Embase, EBSCO, Web of Science, and CINAHL databases were searched from inception through April 29, 2022. Study Selection: The eligibility criteria were (1) adult patients (age ≥18 years) with ICH receiving treatment with a DOAC, (2) reversal of DOAC, and (3) reported safety and anticoagulation reversal outcomes. All nonhuman studies and case reports, studies evaluating patients with ischemic stroke requiring anticoagulation reversal or different dosing regimens of DOAC reversal agents, and mixed study groups with DOAC and warfarin were excluded. Data Extraction and Synthesis: Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines were used for abstracting data and assessing data quality and validity. Two reviewers independently selected the studies and abstracted data. Data were pooled using the random-effects model. Main Outcomes and Measures: The primary outcome was proportion with anticoagulation reversed. The primary safety end points were all-cause mortality and thromboembolic events after the reversal agent. Results: A total of 36 studies met criteria for inclusion, with a total of 1832 patients (967 receiving 4-factor prothrombin complex concentrate [4F-PCC]; 525, andexanet alfa [AA]; 340, idarucizumab). The mean age was 76 (range, 68-83) years, and 57% were men. For 4F-PCC, anticoagulation reversal was 77% (95% CI, 72%-82%; I2 = 55%); all-cause mortality, 26% (95% CI, 20%-32%; I2 = 68%), and thromboembolic events, 8% (95% CI, 5%-12%; I2 = 41%). For AA, anticoagulation reversal was 75% (95% CI, 67%-81%; I2 = 48%); all-cause mortality, 24% (95% CI, 16%-34%; I2 = 73%), and thromboembolic events, 14% (95% CI, 10%-19%; I2 = 16%). Idarucizumab for reversal of dabigatran had an anticoagulation reversal rate of 82% (95% CI, 55%-95%; I2 = 41%), all-cause mortality, 11% (95% CI, 8%-15%, I2 = 0%), and thromboembolic events, 5% (95% CI, 3%-8%; I2 = 0%). A direct retrospective comparison of 4F-PCC and AA showed no differences in anticoagulation reversal, proportional mortality, or thromboembolic events. Conclusions and Relevance: In the absence of randomized clinical comparison trials, the overall anticoagulation reversal, mortality, and thromboembolic event rates in this systematic review and meta-analysis appeared similar among available DOAC reversal agents for managing ICH. Cost, institutional formulary status, and availability may restrict reversal agent choice, particularly in small community hospitals.

Haptoglobin treatment contributes to regulating nitric oxide signal and reduces oxidative stress in the penis: A preventive treatment for priapism in sickle cell disease.

Background: In sickle cell disease (SCD), reduced bioavailability of endothelial NO and cGMP results in reduced expression of phosphodiesterase type 5 (PDE5), thus impairing the penile erection control mechanism and resulting in prolonged penile erection (priapism). In SCD, reduced NO bioavailability is associated with excess plasma hemoglobin due to intravascular hemolysis and increased oxidative stress. Haptoglobin is the plasma protein responsible for reducing plasma hemoglobin levels, but in SCD, haptoglobin levels are reduced, which favors the accumulation of hemoglobin in plasma. Therefore, we aimed to evaluate the effects of haptoglobin treatment on functional and molecular alterations of erectile function, focusing on the contractile and relaxant mechanisms of corpus cavernosum (CC), as well as oxidative stress. Methods: SCD mice were treated with haptoglobin (400 mg/kg, subcutaneous) or vehicle of Monday, Wednesday and Friday for a period of 1 month. Corpus cavernosum strips were dissected free and placed in organ baths. Cumulative concentration-response curves to the acetylcholine, sodium nitroprusside, phenylephrine and KCL, as well as to electrical field stimulation (EFS), were obtained in CC. Protein expressions of eNOS, phosphorylation of eNOS at Ser-1177, nNOS, PDE5, ROCK1, ROCK2, gp91phox, 3-nitrotyrosine, and 4-HNE were measured by western blot in CC. Results: Increased CC relaxant responses to acetylcholine, sodium nitroprusside and electrical-field stimulation were reduced by haptoglobin in SCD mice. Reduced CC contractile responses to phenylephrine and KCl were increased by haptoglobin in SCD mice. Haptoglobin prevented downregulated eNOS, p-eNOS (Ser-1177), PDE5, and ROCK2 protein expressions and reduced protein expressions of reactive oxygen species markers, NADPH oxidase subunit gp91phox, 3-nitrotyrosine and 4-HNE in penises from SCD mice. Haptoglobin treatment did not affect ROCK1 and nNOS protein expressions in penises from SCD mice. Basal cGMP production was lower in the SCD group, which was normalized by haptoglobin treatment. Conclusion: Treatment with haptoglobin improved erectile function due to up-regulation of eNOS-PDE5 expression and down-regulation of the gp91phox subunit of NADPH oxidase and oxidative/nitrosative stress in the penises of SCD mice. Treatment with haptoglobin also increased contractile activity due to up-regulation of ROCK2. Therefore, haptoglobin treatment may be an additional strategy to prevent priapism in SCD.

Twinkling-guided ultrasound detection of polymethyl methacrylate as a potential breast biopsy marker: a comparative investigation.

Since its first description 25 years ago, color Doppler twinkling has been a compelling ultrasound feature in diagnosing urinary stones. While the fundamental cause of twinkling remains elusive, the distinctive twinkling signature is diagnostically valuable in clinical practice. It can be inferred that if an entity twinkles, it empirically has certain physical features. This work investigates a manipulable polymeric material, polymethyl methacrylate (PMMA), which twinkles and has measurable surface roughness and porosity that likely contribute to twinkling. Comparative investigation of these structural properties and of the twinkling signatures of breast biopsy markers made from PMMA and selected commercially available markers showed how twinkling can improve ultrasound detection of devices intentionally designed to twinkle. While this specific application of detecting breast biopsy markers by twinkling may provide a way to approach an unmet need in the care of patients with breast cancer, this work ultimately provides a platform from which the keys to unlocking the fundamental physics of twinkling can be rigorously explored.

Lymphatic Mapping Using US Microbubbles before Lymphaticovenous Anastomosis Surgery for Lymphedema.

Background Lymphaticovenous anastomosis (LVA) surgery is an effective surgical treatment of secondary lymphedema in the extremities, but indocyanine green (ICG) fluorescent lymphography, the reference standard for imaging target lymphatic vessels, has several limitations. More effective methods are needed for preoperative planning. Purpose To evaluate whether contrast-enhanced US (CEUS) can be used to identify target lymphatic vessels for LVA surgery in patients with secondary upper extremity lymphedema and compare the results with those from ICG fluorescent lymphography. Materials and Methods In this single-center retrospective review, CEUS with intradermal injection of microbubbles was performed in patients before LVA surgery in the upper extremities between October 2019 and September 2021. All patients had secondary upper extremity lymphedema from breast cancer treatment. Technical success rate was defined as lymphatic vessels identified with use of CEUS that led to successful LVAs. Descriptive statistics were used. Results All 11 patients were women (mean age, 56 years ± 8 [SD]). The median number of microbubble injection sites was 11 (range, 8-14). CEUS helped identify lymphatic vessels in all 11 women, including in six women in whom ICG fluorescent lymphography could not be performed or failed to help identify any targets. Thirty-five explorations (median, three per patient; range, two to four) were performed, and 24 LVAs (median, three per patient; range, zero to four) were created. Of the anastomoses, 33% (eight of 24) were mapped with use of both CEUS and ICG fluorescent lymphography, 58% (14 of 24) with CEUS only, and 8% (two of 24) with ICG fluorescent lymphography only. Among the 33 explorations on targets mapped with CEUS, an anastomosis could be made at 22 sites, for a technical success rate of 67%. Seven women had at least one additional LVA created from the use of CEUS. Conclusion Contrast-enhanced US is a promising tool for identifying lymphatic vessels in the upper extremities, especially when indocyanine green fluorescent lymphography fails to depict targets or cannot be used. Published under a CC BY 4.0 license.

Plasma-Derived Hemopexin as a Candidate Therapeutic Agent for Acute Vaso-Occlusion in Sickle Cell Disease: Preclinical Evidence.

People living with sickle cell disease (SCD) face intermittent acute pain episodes due to vaso-occlusion primarily treated palliatively with opioids. Hemolysis of sickle erythrocytes promotes release of heme, which activates inflammatory cell adhesion proteins on endothelial cells and circulating cells, promoting vaso-occlusion. In this study, plasma-derived hemopexin inhibited heme-mediated cellular externalization of P-selectin and von Willebrand factor, and expression of IL-8, VCAM-1, and heme oxygenase-1 in cultured endothelial cells in a dose-responsive manner. In the Townes SCD mouse model, intravenous injection of free hemoglobin induced vascular stasis (vaso-occlusion) in nearly 40% of subcutaneous blood vessels visualized in a dorsal skin-fold chamber. Hemopexin administered intravenously prevented or relieved stasis in a dose-dependent manner. Hemopexin showed parallel activity in relieving vascular stasis induced by hypoxia-reoxygenation. Repeated IV administration of hemopexin was well tolerated in rats and non-human primates with no adverse findings that could be attributed to human hemopexin. Hemopexin had a half-life in wild-type mice, rats, and non-human primates of 80-102 h, whereas a reduced half-life of hemopexin in Townes SCD mice was observed due to ongoing hemolysis. These data have led to a Phase 1 clinical trial of hemopexin in adults with SCD, which is currently ongoing.

Safety and tolerability of liquid amikacin in antibiotic-loaded bone cement - a case series.

High-dose liquid antibiotics are uncommon in bone cement. We present a case series of patients in which up to 16 mL of liquid amikacin (250 mg mL - 1 ) was successfully incorporated into bone cement to treat periprosthetic joint infections. We did not observe adverse drug reactions definitively attributed to its use.

Pleckstrin-2 is essential for erythropoiesis in ß-thalassemic mice, reducing apoptosis and enhancing enucleation.

Erythropoiesis involves complex interrelated molecular signals influencing cell survival, differentiation, and enucleation. Diseases associated with ineffective erythropoiesis, such as ß-thalassemias, exhibit erythroid expansion and defective enucleation. Clear mechanistic determinants of what make erythropoiesis effective are lacking. We previously demonstrated that exogenous transferrin ameliorates ineffective erythropoiesis in ß-thalassemic mice. In the current work, we utilize transferrin treatment to elucidate a molecular signature of ineffective erythropoiesis in ß-thalassemia. We hypothesize that compensatory mechanisms are required in ß-thalassemic erythropoiesis to prevent apoptosis and enhance enucleation. We identify pleckstrin-2-a STAT5-dependent lipid binding protein downstream of erythropoietin-as an important regulatory node. We demonstrate that partial loss of pleckstrin-2 leads to worsening ineffective erythropoiesis and pleckstrin-2 knockout leads to embryonic lethality in ß-thalassemic mice. In addition, the membrane-associated active form of pleckstrin-2 occurs at an earlier stage during ß-thalassemic erythropoiesis. Furthermore, membrane-associated activated pleckstrin-2 decreases cofilin mitochondrial localization in ß-thalassemic erythroblasts and pleckstrin-2 knockdown in vitro induces cofilin-mediated apoptosis in ß-thalassemic erythroblasts. Lastly, pleckstrin-2 enhances enucleation by interacting with and activating RacGTPases in ß-thalassemic erythroblasts. This data elucidates the important compensatory role of pleckstrin-2 in ß-thalassemia and provides support for the development of targeted therapeutics in diseases of ineffective erythropoiesis.

Cell-free oxidized hemoglobin drives reactive oxygen species production and pro-inflammation in an immature primary rat mixed glial cell culture.

BACKGROUND: Germinal matrix intraventricular hemorrhage (GM-IVH) is associated with deposition of redox active cell-free hemoglobin (Hb), derived from hemorrhagic cerebrospinal fluid (CSF), in the cerebrum and cerebellum. In a recent study, using a preterm rabbit pup model of IVH, intraventricularly administered haptoglobin (Hp), a cell-free Hb scavenger, partially reversed the damaging effects observed following IVH. Together, this suggests that cell-free Hb is central in the pathophysiology of the injury to the immature brain following GM-IVH. An increased understanding of the causal pathways and metabolites involved in eliciting the damaging response following hemorrhage is essential for the continued development and implementation of neuroprotective treatments of GM-IVH in preterm infant. METHODS: We exposed immature primary rat mixed glial cells to hemorrhagic CSF obtained from preterm human infants with IVH (containing a mixture of Hb-metabolites) or to a range of pure Hb-metabolites, incl. oxidized Hb (mainly metHb with iron in Fe3+), oxyHb (mainly Fe2+), or low equivalents of heme, with or without co-administration with human Hp (a mixture of isotype 2-2/2-1). Following exposure, cellular response, reactive oxygen species (ROS) generation, secretion and expression of pro-inflammatory cytokines and oxidative markers were evaluated. RESULTS: Exposure of the glial cells to hemorrhagic CSF as well as oxidized Hb, but not oxyHb, resulted in a significantly increased rate of ROS production that positively correlated with the rate of production of pro-inflammatory and oxidative markers. Congruently, exposure to oxidized Hb caused a disintegration of the polygonal cytoskeletal structure of the glial cells in addition to upregulation of F-actin proteins in microglial cells. Co-administration of Hp partially reversed the damaging response of hemorrhagic CSF and oxidized Hb. CONCLUSION: Exposure of mixed glial cells to oxidized Hb initiates a pro-inflammatory and oxidative response with cytoskeletal disintegration. Early administration of Hp, aiming to minimize the spontaneous autoxidation of cell-free oxyHb and liberation of heme, may provide a therapeutic benefit in preterm infant with GM-IVH.

Bargain Hunting for Buffered Lidocaine: A Collaborative Discovery of Cost-saving Strategies That Can Improve Patient Care.

Buffered lidocaine is a local anesthetic option during percutaneous needle-directed procedures in the breast. At our institution, sodium bicarbonate (the buffer) is dispensed in volumes that frequently lead to medical waste and shortages. In this study, we describe how moving the buffering of lidocaine from the procedure room to our clinical hospital pharmacy results in a reduction in costs and improves satisfaction across the breast radiology department. While cost savings are difficult to tease out in practices that opt for bundled payments, we were able to access pricing and supply data and coordinate with our pharmacy to change our practice. Making these changes saves our practice $26 000 a year and allows us to continue to offer buffered lidocaine even during sodium bicarbonate shortages. This manuscript describes how these changes came about and their economic impact.

Two Non-gadolinium-based, Innovative Approaches to Preoperative Lymphangiography.

Most magnetic resonance lymphangiography techniques employ intravenous gadolinium-based contrast agents, which carry a US Food and Drug Administration warning about gadolinium retention in the body when used intravenously. Because of this, there may be reluctance to perform intradermal injections of gadolinium-based contrast agents in patients with obstructed lymphatic drainage due to concerns about gadolinium retention in the skin and soft tissues and potential-related toxicity. The aim of this study was to show proof of concept of 2 preoperative lymphangiographic techniques that do not use gadolinium-based contrast agents. One technique used contrast-enhanced ultrasound with intradermal injections of microbubbles (Lumason) in a patient with stage 3, nonpitting left upper extremity edema. Another technique used magnetic resonance imaging with intradermal injections of 0.03 mg/mL or 0.003% ferumoxytol (Feraheme) in a patient with stage 3, nonpitting right lower extremity edema. Both contrast-enhanced ultrasound with microbubbles and magnetic resonance lymphangiogram with ferumoxytol were able to identify candidates for lymphovenous bypass surgery. These candidates were not identified by conventional indocyanine green injections. The authors conclude that (1) low-dose ferumoxytol is a potentially effective non-gadolinium-based contrast alternative to gadolinium-based contrast agent in magnetic resonance lymphangiography and (2) contrast-enhanced ultrasound can identify candidate lymphatic vessels for anastomosis.

Intravascular hemolysis activates complement via cell-free heme and heme-loaded microvesicles.

In hemolytic diseases, such as sickle cell disease (SCD), intravascular hemolysis results in the release of hemoglobin, heme, and heme-loaded membrane microvesicles in the bloodstream. Intravascular hemolysis is thus associated with inflammation and organ injury. Complement system can be activated by heme in vitro. We investigated the mechanisms by which hemolysis and red blood cell (RBC) degradation products trigger complement activation in vivo. In kidney biopsies of SCD nephropathy patients and a mouse model with SCD, we detected tissue deposits of complement C3 and C5b-9. Moreover, drug-induced intravascular hemolysis or injection of heme or hemoglobin in mice triggered C3 deposition, primarily in kidneys. Renal injury markers (Kim-1, NGAL) were attenuated in C3-/- hemolytic mice. RBC degradation products, such as heme-loaded microvesicles and heme, induced alternative and terminal complement pathway activation in sera and on endothelial surfaces, in contrast to hemoglobin. Heme triggered rapid P selectin, C3aR, and C5aR expression and downregulated CD46 on endothelial cells. Importantly, complement deposition was attenuated in vivo and in vitro by heme scavenger hemopexin. In conclusion, we demonstrate that intravascular hemolysis triggers complement activation in vivo, encouraging further studies on its role in SCD nephropathy. Conversely, heme inhibition using hemopexin may provide a novel therapeutic opportunity to limit complement activation in hemolytic diseases.

Haptoglobin and hemopexin inhibit vaso-occlusion and inflammation in murine sickle cell disease: Role of heme oxygenase-1 induction.

During hemolysis, hemoglobin and heme released from red blood cells promote oxidative stress, inflammation and thrombosis. Plasma haptoglobin and hemopexin scavenge free hemoglobin and heme, respectively, but can be depleted in hemolytic states. Haptoglobin and hemopexin supplementation protect tissues, including the vasculature, liver and kidneys. It is widely assumed that these protective effects are due primarily to hemoglobin and heme clearance from the vasculature. However, this simple assumption does not account for the consequent cytoprotective adaptation seen in cells and organs. To further address the mechanism, we used a hyperhemolytic murine model (Townes-SS) of sickle cell disease to examine cellular responses to haptoglobin and hemopexin supplementation. A single infusion of haptoglobin or hemopexin (± equimolar hemoglobin) in SS-mice increased heme oxygenase-1 (HO-1) in the liver, kidney and skin several fold within 1 hour and decreased nuclear NF-ĸB phospho-p65, and vaso-occlusion for 48 hours after infusion. Plasma hemoglobin and heme levels were not significantly changed 1 hour after infusion of haptoglobin or hemopexin. Haptoglobin and hemopexin also inhibited hypoxia/reoxygenation and lipopolysaccharide-induced vaso-occlusion in SS-mice. Inhibition of HO-1 activity with tin protoporphyrin blocked the protections afforded by haptoglobin and hemopexin in SS-mice. The HO-1 reaction product carbon monoxide, fully restored the protection, in part by inhibiting Weibel-Palade body mobilization of P-selectin and von Willebrand factor to endothelial cell surfaces. Thus, the mechanism by which haptoglobin and hemopexin supplementation in hyperhemolytic SS-mice induces cytoprotective cellular responses is linked to increased HO-1 activity.

Characterization of Renal Injury and Inflammation in an Experimental Model of Intravascular Hemolysis.

Intravascular erythrocyte destruction, accompanied by the release of pro-oxidative and pro-inflammatory components hemoglobin and heme, is a common event in the pathogenesis of numerous diseases with heterogeneous etiology and clinical features. A frequent adverse effect related to massive hemolysis is the renal injury and inflammation. Nevertheless, it is still unclear whether heme--a danger-associated molecular pattern--and ligand for TLR4 or upstream hemolysis-derived products are responsible for these effects. Well-characterized animal models of hemolysis with kidney impairment are needed to investigate how hemolysis drives kidney injury and to test novel therapeutic strategies. Here, we characterized the pathological processes leading to acute kidney injury and inflammation during massive intravascular hemolysis, using a mouse model of phenylhydrazine (PHZ)-triggered erythrocyte destruction. We observed profound changes in mRNA levels for markers of tubular damage (Kim-1, NGAL) and regeneration (indirect marker of tubular injury, Ki-67), and tissue and vascular inflammation (IL-6, E-selectin, P-selectin, ICAM-1) in kidneys of PHZ-treated mice, associated with ultrastructural signs of tubular injury. Moreover, mass spectrometry revealed presence of markers of tubular damage in urine, including meprin-α, cytoskeletal keratins, α-1-antitrypsin, and α-1-microglobulin. Signs of renal injury and inflammation rapidly resolved and the renal function was preserved, despite major changes in metabolic parameters of PHZ-injected animals. Mechanistically, renal alterations were largely heme-independent, since injection of free heme could not reproduce them, and scavenging heme with hemopexin in PHZ-administered mice could not prevent them. Reduced overall health status of the mice suggested multiorgan involvement. We detected amylasemia and amylasuria, two markers of acute pancreatitis. We also provide detailed characterization of renal manifestations associated with acute intravascular hemolysis, which may be mediated by hemolysis-derived products upstream of heme release. This analysis provides a platform for further investigations of hemolytic diseases and associated renal injury and the evaluation of novel therapeutic strategies that target intravascular hemolysis.

Outcomes Following Three-Factor Inactive Prothrombin Complex Concentrate Versus Recombinant Activated Factor VII Administration During Cardiac Surgery.

OBJECTIVE: To compare outcomes following inactive prothrombin complex concentrate (PCC) or recombinant activated factor VII (rFVIIa) administration during cardiac surgery. DESIGN: Retrospective propensity-matched analysis. SETTING: Academic tertiary-care center. PARTICIPANTS: Patients undergoing cardiac surgery requiring cardiopulmonary bypass who received either rFVIIa or the inactive 3-factor PCC. INTERVENTIONS: Outcomes following intraoperative administration of rFVIIa (263) or factor IX complex (72) as rescue therapy to treat bleeding. MEASUREMENTS AND MAIN RESULTS: In the 24 hours after surgery, propensity-matched patients receiving PCC versus rFVIIa had significantly less chest tube outputs (median difference -464 mL, 95% confidence interval [CI] -819 mL to -110 mL), fresh frozen plasma transfusion rates (17% v 38%, p = 0.028), and platelet transfusion rates (26% v 49%, p = 0.027). There were no significant differences between propensity-matched groups in postoperative stroke, deep venous thrombosis, pulmonary embolism, myocardial infarction, or intracardiac thrombus. Postoperative dialysis was significantly less likely in patients administered PCC versus rFVIIa following propensity matching (odds ratio = 0.3, 95% CI 0.1-0.7). No significant difference in 30-day mortality in patients receiving PCC versus rFVIIa was present following propensity matching. CONCLUSIONS: Use of rFVIIa versus inactive PCCs was significantly associated with renal failure requiring dialysis and increased postoperative bleeding and transfusions.

Perioperative Use of Coagulation Factor Concentrates in Patients Undergoing Cardiac Surgery.

Coagulopathy and bleeding are common in patients undergoing cardiac surgery, with a perioperative transfusion rate in excess of 50%. The mechanism of coagulopathy associated with cardiac surgery using cardiopulmonary bypass is multifactorial. Historically, coagulation factor-mediated bleeding in such instances has been treated with allogeneic plasma transfusion. Coagulation factor concentrate use for treatment of hemophilia, congenital factor deficiencies and, more recently, emergency warfarin reversal is common. Formulations of factor concentrates include single and multifactor concentrates and both human and recombinant-derived products. Off-label use of factor concentrates for coagulopathy and bleeding associated with cardiac surgery has been described for decades; however, sound clinical research with regard to this practice is limited. This review highlights the literature discussing the use of factor concentrates in patients undergoing cardiac surgery and provides an overview of reasonable uses or lack thereof for factor concentrates in clinical practice.

Purified and Recombinant Hemopexin: Protease Activity and Effect on Neutrophil Chemotaxis.

Infusion of the heme-binding protein hemopexin has been proposed as a novel approach to decrease heme-induced inflammation in settings of red blood cell breakdown, but questions have been raised as to possible side effects related to protease activity and inhibition of chemotaxis. We evaluated protease activity and effects on chemotaxis of purified plasma hemopexin obtained from multiple sources as well as a novel recombinant fusion protein Fc-hemopexin. Amidolytic assay was performed to measure the protease activity of several plasma-derived hemopexin and recombinant Fc-hemopexin. Hemopexin was added to the human monocyte culture in the presence of lipopolysaccharides (LPS), and also injected into mice intravenously (i.v.) 30 min before inducing neutrophil migration via intraperitoneal (i.p.) injection of thioglycolate. Control groups received the same amount of albumin. Protease activity varied widely between hemopexins. Recombinant Fc-hemopexin bound heme, inhibited the synergy of heme with LPS on tumor necrosis factor (TNF) production from monocytes, and had minor but detectable protease activity. There was no effect of any hemopexin preparation on chemotaxis, and purified hemopexin did not alter the migration of neutrophils into the peritoneal cavity of mice. Heme and LPS synergistically induced the release of LTB4 from human monocytes, and hemopexin blocked this release, as well as chemotaxis of neutrophils in response to activated monocyte supernatants. These results suggest that hemopexin does not directly affect chemotaxis through protease activity, but may decrease heme-driven chemotaxis and secondary inflammation by attenuating the induction of chemoattractants from monocytes. This property could be beneficial in some settings to control potentially damaging inflammation induced by heme.