Efficacy of aprotinin with various anticoagulant agents in cardiopulmonary bypass

Aprotinin Inhibits SARS-CoV-2 Replication

Severe acute respiratory syndrome virus 2 (SARS-CoV-2) is the cause of the current coronavirus disease 19 (COVID-19) pandemic. Protease inhibitors are under consideration as virus entry inhibitors that prevent the cleavage of the coronavirus spike (S) protein by cellular proteases. Herein, we showed that the protease inhibitor aprotinin (but not the protease inhibitor SERPINA1/alpha-1 antitrypsin) inhibited SARS-CoV-2 replication in therapeutically achievable concentrations. An analysis of proteomics and translatome data indicated that SARS-CoV-2 replication is associated with a downregulation of host cell protease inhibitors. Hence, aprotinin may compensate for downregulated host cell proteases during later virus replication cycles. Aprotinin displayed anti-SARS-CoV-2 activity in different cell types (Caco2, Calu-3, and primary bronchial epithelial cell air-liquid interface cultures) and against four virus isolates. In conclusion, therapeutic aprotinin concentrations exert anti-SARS-CoV-2 activity. An approved aprotinin aerosol may have potential for the early local control of SARS-CoV-2 replication and the prevention of COVID-19 progression to a severe, systemic disease.

Leukocyte count affects expression of reference genes in canine whole blood samples

Background

The dog is frequently used as a model for hematologic human diseases. In this study the suitability of nine potential reference genes for quantitative RT-PCR studies in canine whole blood was investigated.

Findings

The expression of these genes was measured in whole blood samples of 263 individual dogs, representing 73 different breeds and a group of 40 mixed breed dogs, categorized into healthy dogs and dogs with internal and hematological diseases, and dogs that underwent a surgical procedure. GeNorm analysis revealed that a combination of 5 to 6 of the most stably expressed genes constituted a stable normalizing factor. Evaluation of the expression revealed different ranking of reference genes in Normfinder and GeNorm. The disease category and the white blood cell count significantly affected reference gene expression.

Conclusions

The discrepancy between the ranking of reference genes in this study by Normfinder and Genorm can be explained by differences between the experimental groups such as "disease category" and "WBC count". This stresses the importance of assessing the expression stability of potential reference genes for gene experiments in canine whole blood anew for each specific experimental condition.

Natural and engineered kallikrein inhibitors: an emerging pharmacopoeia

The kallikreins and kallikrein-related peptidases are serine proteases that control a plethora of developmental and homeostatic phenomena, ranging from semen liquefaction to skin desquamation and blood pressure. The diversity of roles played by kallikreins has stimulated considerable interest in these enzymes from the perspective of diagnostics and drug design. Kallikreins already have well-established credentials as targets for therapeutic intervention and there is increasing appreciation of their potential both as biomarkers and as targets for inhibitor design. Here, we explore the current status of naturally occurring kallikrein protease-inhibitor complexes and illustrate how this knowledge can interface with strategies for rational re-engineering of bioscaffolds and design of small-molecule inhibitors.

A Mechanical Study of Rigid Plate Configurations for Sternal Fixation

Rigid metal plates are a promising alternative to wires for reapproximating the sternum after open-heart surgery due to their potential ability to reduce motion at the wound site and thereby reduce the likelihood of post-operative healing complications. Despite initial clinical success, the use of plates has been limited, in part, by insufficient knowledge about their most effective placement. This study compares the ability of five plate configurations to provide stable closure by limiting sternal separation. Commercially available x-shaped and box-shaped plates were used and combinations of parameters (plate type, location, and number of plates) were investigated in vitro. Lateral distraction tests using controlled, uniform loading were conducted on 15 synthetic sterna and the distractions between separated sternum halves were measured at seven locations. Distractions at the xiphoid, a critical region clinically, varied widely from 0.03 +/- 0.53 mm to 4.24 +/- 1.26 mm depending on all three plate parameters. Of the configurations tested, three x-shaped plates and one box-shaped plate resisted sternal separation most effectively. These results provide the first comparison of plate configurations for stabilizing a sternotomy. However, basic mechanical analyses indicate that sternal loading in vivo is non-uniform; future studies will need to accurately quantify in vivo loading to improve in vitro test methods.

Intravenous rFVIIa administered for hemorrhage control in hypothermic coagulopathic swine with grade V liver injuries

BACKGROUND

Intravenous administration of recombinant activated human clotting factor VII (rFVIIa) has been used successfully to prevent bleeding in hemophilia patients undergoing elective surgery, but not in previously normal trauma patients. This study was conducted to determine whether rFVIIa was a useful adjunct to gauze packing for decreasing blood loss from grade V liver injuries in hypothermic and coagulopathic swine.

METHODS

All animals (n = 10, 35 +/- 2 kg) underwent a 60% isovolemic exchange transfusion with 6% hydroxyethyl starch and were cooled to 33 degrees C core temperature. The swine then received a grade V liver injury and 30 seconds later, either 180 microg/kg rFVIIa, or saline control. All animals were gauze packed 30 seconds after injury and resuscitated 5.5 minutes after injury with lactated Ringer's solution to their preinjury mean arterial pressure. Posttreatment blood loss, mean arterial pressure, resuscitation volume, and clotting studies were monitored for 1 hour. Histology of lung, kidney, and small bowel were obtained to evaluate for the presence of microvascular thrombi.

RESULTS

At the time of injury, core temperature was 33.3 degrees +/- 0.4 degrees C, hemoglobin was 6 +/- 0.7 g/dL, prothrombin time was 19.1 +/- 1.0 seconds, activated partial thromboplastin time was 29.0 +/- 4.8 seconds, fibrinogen was 91 +/- 20 mg/dL, and platelets were 221 +/- 57 x 105/mL, with no differences between groups (p > 0.05). Clotting factor levels confirmed a coagulopathy at the preinjury point. The posttreatment blood loss was less (p < 0.05) in group 1 (527 +/- 323 mL), than in group 2 (976 +/- 573 mL). The resuscitation volume was not different (p > 0.05). One-hour survival in both groups was 100%. Compared with the control group, rFVIIa increased the circulating levels of VIIa and, despite hypothermia, shortened the prothrombin time 5 minutes after injection (p < 0.05). Laboratory evaluation revealed no systemic activation of the clotting cascade. Postmortem evaluation revealed no evidence of large clots in the hepatic veins or inferior vena cava, or microscopic thrombi in lung, kidney, or small intestine.

CONCLUSION

rFVIIa reduced blood loss and restored abnormal coagulation function when used in conjunction with liver packing in hypothermic and coagulopathic swine. No adverse effects were identified.

Evaluation of a new point of care heparin test for cardiopulmonary bypass: the TAS heparin management test

Patients undergoing cardiopulmonary bypass (CPB) require anticoagulation with heparin to avoid thrombosis within the bypass circuit. The common method used to monitor the degree of anticoagulation is the activated clotting time (ACT). We evaluated a novel point of care device, the TAS (Pharmanetics, Raleigh, NC, USA) heparin management test (HMT), for its suitability in monitoring anticoagulation during CPB. In vitro analysis showed a dose-response (r2=0.988) of the HMT from 0.078-10.0 U/ml heparin, covering the range of heparin used during cardiac surgery (2-5 U/ml). Fifty randomly selected patients undergoing CPB were studied. Preheparin clotting times for these patients were 143+/-32 s for the HMT and 146+/-18 s for the ACT; 435+/-60 s HMT and 438+/-39 s ACT during CPB; 145+/-50 s HMT and 128+/-14 s ACT post-protamine (r2=0.797). epsilon-Aminocaproic acid treatment for inhibition of fibrinolysis did not affect the HMT. We conclude that the HMT correlates well with the ACT and may be useful for monitoring heparin during CPB. Advantages of the HMT are small sample volume and good sensitivity to heparin.

Aprotinin in pediatric cardiac operations: a benefit in complex malformations and with high-dose regimen only

BACKGROUND

The benefits and the current indications of aprotinin in congenital operations are not well defined. At present there are only a few studies available that have investigated a small number of patients in several heterogeneous groups of malformations.

METHODS

We investigated efficacy and safety of aprotinin in three groups of children < 15 kg, presenting with isolated ventricular septum defect (n = 60), tetralogy of Fallot (n = 52), and transposition of the great arteries (n = 56). Low-dose aprotinin regimen A1 (500,000 KIU in pump prime only) and high-dose aprotinin A2 (50,000 KIU/kg during induction of anesthesia, 50,000 KIU/kg in pump prime, and 20,000 KIU/h continuous infusion) were compared to a control group A0 (without aprotinin) regarding perioperative blood loss, transfusion requirements, and effects on the coagulation system.

RESULTS

The most common coagulation tests of aprotinin-treated patients and the platelet numbers were comparable with those of control patients preoperatively and 15 minutes after protamine administration. A significant dose-dependent reduction in fibrin-fibrinogen split products was observed at the end of cardiopulmonary bypass in the majority of aprotinin-treated patients with transposition. In patients with ventricular septum defect and Fallot, no significant difference in blood loss and transfusion requirements could be observed between patients with or without aprotinin and no difference was observed between low- and high-dose regimen. In transposition of the great arteries, high-dose aprotinin led to significant reduction of blood loss (p = 0.02) and postoperative blood transfusion (p = 0.003). Severe side effects as a result of administration of aprotinin were not observed.

CONCLUSIONS

High-dose aprotinin reduces blood loss and transfusion requirement only in complex congenital cardiac operations; therefore aprotinin cannot be recommended as a blood conservation agent in routine pediatric operations.