S62798, a TAFIa inhibitor, accelerates endogenous thrombolysis in a murine model of pulmonary thromboembolism

 

Pulmonary embolism (PE) is the third leading cause of cardiovascular death in western countries. The enhancement of fibrinolysis constitutes a promising approach to treat thrombotic diseases. In patients, venous thrombosis and thromboembolism risks are associated with increased plasma levels of TAFI (Thrombin Activatable Fibrinolysis Inhibitor) antigen as well as the active form TAFIa. S62798 is a competitive, selective and potent human TAFIa inhibitor (IC50±SD=11.2±0.4nM). It is however less potent on mouse TAFIa (IC50±SD=270±39nM). Here, we tested the ability of S62798 to enhance endogenous fibrinolysis in a mouse model of pulmonary thromboembolism.

Human Tissue Factor (TF) was injected in C57Bl6 male mice. Ten minutes later, mice (n=4 to 14 per group) were treated (IV) with S62798 (from 0.01 to 100mg/kg) or vehicle (0.9% NaCl). Ten or twenty minutes (min) later, mice were anesthetized and lungs were collected, homogenized and pulmonary fibrin was quantified by ELISA. Results are expressed as ratio of geometric mean of pulmonary fibrin (μg/mL): tested treatment/ vehicle [95% confidence interval (CI)].

Ten minutes after S62798 treatment, pulmonary fibrin deposition was dose-dependently decreased with a Minimal Effective Dose of 0.04mg/kg [90% prediction interval 0.037 - 0.051] and an ED50 of 0.03mg/kg [95% CI: 0.01; 0.06]. Mice were then treated with 0.1mg/kg S62798 or vehicle (10 min after TF induction) and fibrin deposition in lungs was quantified 10 and 20 minutes post S62798 treatment. The level of pulmonary fibrin deposition was significantly decreased (p<0.0001) compared to vehicle group (ratio 0.31 [0.21; 0.45] at 10 min; 0.35 [0.24; 0.51] at 20 min). Finally, the effect of S62798 (1mg/kg) in combination with heparin was evaluated (n=10/group). When administered 10 min before TF injection, heparin (2000IU/kg) significantly (p<0.0001) decreased pulmonary fibrin level (20 min post TF: ratio 0.03 [0.01; 0.05]). When treatment was done in a curative setting (10 min post TF), heparin alone had no effect (p=0.85) on fibrin deposition (ratio 0.96 [0.65; 1.43]) whereas a similar significant (p<0.0001) decreased pulmonary fibrin deposition was observed in response to S62798 alone or associated with heparin (ratio 0.27 [0.18; 0.40] (S62798 alone) and 0.29 [0.20; 0.43] (S62798+heparin)).

In this model, curative S62798 treatment, alone or associated to heparin, accelerated clot degradation by potentiating endogenous fibrinolysis and thus decreased pulmonary fibrin deposition. Due to its capacity to enhance endogenous fibrinolysis, S62798, which has completed phase I studies, is expected to be a therapeutic option for intermediate high risk PE patients on top of anticoagulants. With early recanalization, S62798 should rapidly reduce pulmonary artery pressure and resistance, with concomitant improvement in right ventricular function, preserving cardiac function, and reducing acute PE-related morbidity and mortality in these patients.

Funding Acknowledgement

Type of funding source: None

Antibiotic-loaded ceramic sternum for sternal replacement in a patient with deep sternal wound infection

A 68-year-old man presented with destruction of his sternum after cardiac surgery. Classical management with multiple debridements, vacuum dressings and antibiotics failed. A replacement of his sternum was performed using an antibiotic-loaded porous alumina ceramic sternum. Despite the infected wound, the ceramic sternum did not get infected due to the high antibiotic concentration obtained locally. Two years after the surgery, no relapse occurred and the pulmonary function tests improved.

An antibiotic loaded ceramic sternum to treat destroyed infected sternum: 4 cases

Background

After its destruction during refractory deep sternal wound infection (DSWI), current sternum reconstructions mainly rely on muscle flaps technique, but such technique have pitfalls and limits. To tackle the limited possibilities to use device implantation because of the risk of infection, we developed a self-protected device allowing its implantation in an infected area.

Methods

We used gentamicin alone or in combination with vancomycin loaded in a porous ceramic sternum to replace sternums destroyed during DSWI. The aim was to mechanically replace the sternum and to secure the implantation by killing the remaining bacteria in the wound thanks to the loaded antibiotic.

Results

This device was implanted in four infected patients during DWSI with sternal dehiscence. No complication occurred during surgeries, and wound healing was obtained quickly. Local antibiotic concentrations largely exceeded the ones needed for their efficacy while no antibiotic was found in the blood. All patients are well-being. However previously unknown gentamicin resistant bacteria, present in the surgical wound at the time of positioning, required sternal implant removal for one patient after 19 months. For all patients, pulmonary function tests (PFT) improved after implantation.

Conclusions

The ceramic sternum played its role consolidating the thoracic cage without stiffening. The antibiotic loaded in the sternum allowed a secure implantation, killing bacteria before the colonization of the implant even in this infected area. These four implantations are promising for patients with sternal destruction after DSWI.

First Sternal Cleft Repair Using a Porous Alumina Ceramic Prosthesis in a 9-Year-Old Child

Sternal cleft is a rare congenital abnormality, often associated with other congenital defects. We present the case of a 9-year-old child with complete sternal cleft, treated with an innovative sternal prosthesis. Surgery was performed to protect the heart and also, as pulsations was visible, leading to serious esthetical concerns, to enhance school integration, which was difficult. The porous alumina device used was initially designed for sternal reconstruction after refractory deep sternal wound infection or carcinoma. Surgery and early follow-up were simple. There was no complication and the follow-up of more than 1 year reveals a good healing without breath discomfort and a correct development of the chest wall. In this rare indication, the alumina ceramic sternal prosthesis offers a reliable alternative to classical methods, such as muscle flap, autogenous tissue transfer, costal homograft, and other prosthetic materials like mesh or synthetic patch.

First case of sternum replacement with a bioceramic prosthesis after radio-induced sarcoma

Objectives

To date, no "gold standard" technique has been developed for sternum replacement in cases of radioinduced sarcoma, which is a rare and aggressive disease. Current techniques rely on metallic prostheses, meshes, or bone grafts-procedures that that are associated with several complications. We therefore tried a new solution that might simplify and optimize this surgery.

Methods

We used a porous alumina ceramic prosthesis (Ceramil: i.ceram, Limoges, France) that has several interesting characteristics, such as osseointegration, biocompatibility, radiolucency, and high mechanical strength.

Results

We report the first case of sternal replacement surgery involving the implantation of a ceramic prosthesis after radio-induced sternal sarcoma. In 2005, a 54-year-old woman was diagnosed with local breast cancer for which she underwent all appropriate treatment. Ten years later, she developed radio-induced sarcoma of the sternum. A complete sternal replacement was performed on 24 April 2015, with no postoperative complications. Imaging by ¹⁸F-flurodeoxyglucose positron-emission tomography-computed tomography performed 26 months after the surgery showed no local recurrence. The patient seems to have fully recovered and has resumed normal activity.

Conclusions

This new technique is promising. For the first time, we highlight the feasibility, safety, and efficacy of sternal replacement using a porous alumina ceramic prosthesis.

Porous alumina ceramic sternum: A reliable option for sternal replacement

CONTEXT:

To date, there is no gold standard technique for sternum replacement. Current techniques rely on metallic prosthesis, meshes and bars, or bone grafts. However, they have several pitfalls.

AIMS:

The aim of this article is to report the results of sternal replacement with a porous alumina ceramic sternum.

SETTINGS AND DESIGN:

Surgeries were performed in two teaching hospitals in France.

METHODS:

We designed a porous alumina ceramic prosthesis which possesses interesting characteristics for this surgery such as great biocompatibility, a certain level of bacterial resistance, radiolucency, and compatibility with radiotherapy. The implant is stitched to the ribs with suture thread and does not require osteosynthesis material.

RESULTS:

Six patients with a mean age of 60.6 years received this prosthesis. Indication was tumor in five cases and mediastinitis in one case. The mean follow-up is 20 months (3–37 months). No major complication occurred and healing was fine for all patients. Patients did not complain of breathing discomfort or pain related to the prosthesis.

CONCLUSIONS:

This new technique is promising even if there are only six patients in this study.

Sortilin limits EGFR signaling by promoting its internalization in lung cancer

Tyrosine kinase receptors such as the epidermal growth factor receptor (EGFR) transduce information from the microenvironment into the cell and activate homeostatic signaling pathways. Internalization and degradation of EGFR after ligand binding limits the intensity of proliferative signaling, thereby helping to maintain cell integrity. In cancer cells, deregulation of EGFR trafficking has a variety of effects on tumor progression. Here we report that sortilin is a key regulator of EGFR internalization. Loss of sortilin in tumor cells promoted cell proliferation by sustaining EGFR signaling at the cell surface, ultimately accelerating tumor growth. In lung cancer patients, sortilin expression decreased with increased pathologic grade, and expression of sortilin was strongly correlated with survival, especially in patients with high EGFR expression. Sortilin is therefore a regulator of EGFR intracellular trafficking that promotes receptor internalization and limits signaling, which in turn impacts tumor growth.

Type-2 diabetes and carotid stenosis: a proposal for a screening strategy in asymptomatic patients

The objective of this prospective observational study was to establish the prevalence of carotid atherosclerosis in an asymptomatic diabetic population and to determine predictive factors for a screening optimization. A total of 300 consecutive type-2 diabetic subjects (166 males, 134 females) underwent a physical examination and duplex carotid scanning. Patients with a recent cerebrovascular event (±6 weeks) or previous carotid surgery were excluded. The prevalence of carotid stenosis ≥60% or occlusion was 4.7%; the prevalence of carotid atherosclerosis was 68.3%. Risk factors for stenosis ≤60% or occlusion were the presence of diabetic retinopathy (OR: 3.62; 95% CI: 1.12-11.73), ankle-brachial index (ABI) <0.85 (OR: 3.94; 95% CI: 1.21-12.84) and a personal history of neurological disorders (OR: 4.54; 95% CI: 1.16-17.81). Being female was a protective factor (OR: 0.09; 95% CI: 0.01-0.78). The two factors in the analysis limited to the male population were an ABI < 0.85 (OR: 3.66; 95% CI: 1.04-12.84) and a personal history of coronary heart disease (OR: 3.34; 95% CI: 1.01-11.01). If male diabetics without either of these two factors are excluded, the negative predictive value for carotid stenosis is 96.6%. In conclusion, the prevalence of atherosclerotic carotid disease in diabetic patients is high. In these patients, the probability of finding >60% stenosis is highest among men with a history of coronary heart disease or an ABI <0.85.

[Hypoglycaemic coma revealing a malignant recurrence during Doege-Potter syndrome]

INTRODUCTION

The Doege-Potter syndrome is a rare paraneoplastic syndrome, first described by Doege and Potter in 1930, that usually involves solid fibrous pleural tumours. Hypoglycaemia is a rare complication of these tumours, due to secretion of insulin-like growth factors, and it can be the presenting symptom. The incidence of malignancy is low, about 12-15 %.

CASE REPORT

An 81-year-old Caucasian man, operated on 20 years previously for a benign pleural fibroma, presented with several episodes of loss of consciousness due to profound hypoglycaemia and a history of increasing dyspnea. The chest X-ray revealed an intrathoracic mass. Following excision histological examination confirmed recurrence with malignant transformation to a high-grade sarcoma.

CONCLUSION

The Doege-Potter syndrome is a rare condition but it should be suspected in episodes of hypoglycaemia associated with a history of dyspnea. These patients should be followed up postoperatively because of the risk of tumour recurrence.

3D analysis of advanced nano-devices using electron and atom probe tomography

The structural and chemical properties of advanced nano-devices with a three-dimensional (3D) architecture have been studied at the nanometre scale. An original method has been used to characterize gate-all-around and tri-gate silicon nanowire transistor by combining electron tomography and atom probe tomography (APT). Results show that electron tomography is a well suited method to determine the morphological structure and the dimension variations of devices provided that the atomic number contrast is sufficient but without an absolute chemical identification. APT can map the 3D chemical distribution of the atoms in devices but suffers from strong distortions in the dimensions of the reconstructed volume. These may be corrected using a simple method based on atomic density correction and electron tomography data. Moreover, this combination is particularly useful in helping to understand the evaporation mechanisms and improve APT reconstructions. This paper demonstrated that a full 3D characterization of nano-devices requires the combination of both tomography techniques.

[MacLeod syndrome and pneumothorax: don't be fooled]

INTRODUCTION

MacLeod syndrome, also known as Swyer-James syndrome, is a rare syndrome characterized by unilateral lung hyperlucency. It is a form of constrictive bronchiolitis which is caused by repeated acute bronchiolitis and/or pulmonary infections during infancy.

CASE REPORT

The patient was a 26-year-old man who had had a first left pneumothorax at the age of 21. He smokes tobacco. When he was 1-year-old he had experienced repeated episodes of acute bronchiolitis. At age 26, he suffered from a second left pneumothorax which was wrongly diagnosed as a recurrent drain-resistant pneumothorax. Misdiagnosed, he underwent a chemical pleurodesis during thoracoscopy. As a hyperlucency remained in the left upper part of the lung on chest X-ray, further investigations were undertaken and a diagnosis of MacLeod syndrome was made.

CONCLUSIONS

MacLeod syndrome is rare. It can be associated with pneumothorax which can be a source of misdiagnosis and error in the management of these patients. Therefore, the diagnostic criteria and therapeutic indications are reiterated. The probable mechanism of association between pneumothorax and Macleod syndrome is also discussed.

[Subcutaneous fistula from a pneumatocele: surgical treatment]

INTRODUCTION

A pneumatocele is an air containing cavity, without a wall. It is a rare complication of thoracic trauma.

CASE REPORT

The patient was a 46-year-old drug addict, positive for the human immunodeficiency virus. Following a fall in which he fractured the posterior parts of the right 7th and 8th ribs, he developed a subcutaneous fistula and a pneumatocele of the right lower lobe. It did not resolve spontaneously and surgery was undertaken. The pneumatocele and the subcutaneous cavity were drained and the rib fractures were stabilized with Judet struts.

CONCLUSIONS

Pneumatocele is a classical but rare complication of thoracic trauma, resulting from a tear of the lung. The differential diagnosis includes localised pneumothorax, an intrathoracic gastric hernia and pneumomediastinum. The usual treatment is surveillance but in this case, surgery was necessary for drainage of the cavities and stabilization of the rib fractures.