Leukocytes as a reservoir of circulating oncogenic DNA and regulatory targets of tumor-derived extracellular vesicles

Essentials Tumor-bearing mice were employed to follow oncogenic HRAS sequences in plasma, and blood cells. Cancer DNA accumulated in leukocytes above levels detected in exosomes, platelets and plasma. Extracellular vesicles and nucleosomes are required for uptake of tumor DNA by leukocytes. Uptake of tumor-derived extracellular vesicles by leukocytes triggers coagulant phenotype.

SUMMARY

Background Tumor-derived extracellular vesicles (EVs) and free nucleosomes (NSs) carry into the circulation a wealth of cancer-specific, bioactive and poorly understood molecular cargoes, including genomic DNA (gDNA). Objective Here we investigated the distribution of extracellular oncogenic gDNA sequences (HRAS and HER2) in the circulation of tumor-bearing mice. Methods and Results Surprisingly, circulating leukocytes (WBCs), especially neutrophils, contained the highest levels of mutant gDNA, which exceeded the amount of this material recovered from soluble fractions of plasma, circulating EVs, platelets, red blood cells (RBCs) and peripheral organs, as quantified by digital droplet PCR (ddPCR). Tumor excision resulted in disappearance of the WBC-associated gDNA signal within 2-9 days, which is in line with the expected half-life of these cells. EVs and nucleosomes were essential for the uptake of tumor-derived extracellular DNA by neutrophil-like cells and impacted their phenotype. Indeed, the exposure of granulocytic HL-60 cells to EVs from HRAS-driven cancer cells resulted in a selective increase in tissue factor (TF) procoagulant activity and interleukin 8 (IL-8) production. The levels of circulating thrombin-antithrombin complexes (TAT) were markedly elevated in mice harboring HRAS-driven xenografts. Conclusions Myeloid cells may represent a hitherto unrecognized reservoir of cancer-derived, EV/NS-associated oncogenic gDNA in the circulation, and a possible novel platform for liquid biopsy in cancer. In addition, uptake of this material alters the phenotype of myeloid cells, induces procoagulant and proinflammatory activity and may contribute to systemic effects associated with cancer.

Bacteriophages: biosensing tools for multi-drug resistant pathogens

Pathogen detection is of utmost importance in many sectors, such as in the food industry, environmental quality control, clinical diagnostics, bio-defence and counter-terrorism. Failure to appropriately, and specifically, detect pathogenic bacteria can lead to serious consequences, and may ultimately be lethal. Public safety, new legislation, recent outbreaks in food contamination, and the ever-increasing prevalence of multidrug-resistant infections have fostered a worldwide research effort targeting novel biosensing strategies. This review concerns phage-based analytical and biosensing methods targeted towards theranostic applications. We discuss and review phage-based assays, notably phage amplification, reporter phage, phage lysis, and bioluminescence assays for the detection of bacterial species, as well as phage-based biosensors, including optical (comprising SPR sensors and fiber optic assays), electrochemical (comprising amperometric, potentiometric, and impedimetric sensors), acoustic wave and magnetoelastic sensors.

CMOS Conductometric System for Growth Monitoring and Sensing of Bacteria

We present the design and implementation of a prototype complementary metal-oxide semiconductor (CMOS) conductometric integrated circuit (IC) for colony growth monitoring and specific sensing of Escherichia coli (E. coli) bacteria. The detection of E. coli is done by employing T4 bacteriophages as receptor organisms. The conductometric system operates by measuring the resistance of the test sample between the electrodes of a two-electrode electrochemical system (reference electrode and working electrode). The CMOS IC is fabricated in a TSMC 0.35-μm process and uses a current-to-frequency (I to F) conversion circuit to convert the test sample resistance into a digital output modulated in frequency. Pulsewidth control (one-shot circuit) is implemented on-chip to control the pulsewidth of the output digital signal. The novelty in the current work lies in the ability of the CMOS sensor system to monitor very low initial concentrations of bacteria (4×10(2) to 4×10(4) colony forming unit (CFU)/mL). The CMOS system is also used to record the interaction between E. coli and its specific receptor T4 bacteriophage. The prototype CMOS IC consumes an average power of 1.85 mW with a 3.3-V dc power supply.

Effect of tranexamic acid incorporated in fibrin sealant clots on the cell behavior of neuronal and nonneuronal cells

Fibrin sealants are commonly used for hemostasis following surgery on various types of tissues. Aprotinin, an effective fibrinolysis inhibitor, is one of the components in some fibrin sealant products currently available. Tranexamic acid (tAMCHA) is another fibrinolysis inhibitor and is used as an alternative to aprotinin. Recent studies on fibrin sealant products containing tAMCHA indicate that it may be responsible for various adverse reactions when used in neurological applications. To determine a possible mechanism for such adverse reactions, we examined the effect of tAMCHA on the behavior of neuronal and nonneuronal cells using in vitro assays. The data indicate that different concentrations of tAMCHA incorporated in fibrin clots had no effect on the initial cell adhesion of either proliferative cells (glial cells and fibroblasts) or nonproliferative cells (neuronal cells) to the fibrin clots. Moreover, a high concentration of tAMCHA (300-450 mM) incorporated in the fibrin clots increased glial and fibroblast proliferation on fibrin clots. However, because tAMCHA is known to leach out of the fibrin clots, we have also examined the effect of solubilized tAMCHA in a growth medium on cells seeded on matrix-coated surfaces. A high concentration (300-450 mM) of tAMCHA detached all cell types from matrix-coated dishes. Our model suggests that tAMCHA in fibrin clots has no adverse effect on cells bound to the fibrin clots; however, tAMCHA leaching out from the fibrin clots reduces adhesion of adjacent cells bound to their natural extracellular matrix. Thus, a high concentration of tAMCHA should not be used as a fibrinolysis inhibitor in fibrin sealant products, especially in neurosurgery.

Low-molecular-weight heparins in the treatment of deep-vein thrombosis

OBJECTIVE

To compare the characteristics and clinical efficacy of low-molecular-weight heparins (LMWHs) and unfractionated heparin (UFH) in the treatment of deep-vein thrombosis (DVT). Adverse effects, dosing, and cost issues are also discussed.

DATA SOURCES

A MEDLINE search (January 1984-October 1997) was used to identify pertinent French and English literature, including clinical trials and reviews on LMWHs and their use in DVT.

STUDY SELECTION

Trials comparing dalteparin, enoxaparin, tinzaparin, and nadroparin with UFH were selected. As studies were numerous, only randomized trials including more than 50 patients were reviewed. Moreover, all patients studied had a first episode of symptomatic DVT confirmed by objective tests (i.e., venography, duplex ultrasonography, impedance plethysmography). Clinical efficacy and safety of LMWHs were assessed in these trials.

DATA EXTRACTION

Results pertaining to venographic assessment, recurrent thromboembolism, total mortality, and bleeding complications were extracted from the selected studies.

DATA SYNTHESIS

Compared with UFH, LMWHs have a longer plasma half-life, better subcutaneous bioavailability, more predictable anticoagulant response, and require less intense laboratory monitoring. Most trials demonstrate comparable effects on thrombus extension and incidence of recurrent thromboembolism. Compared with UFH, LMWHs do not alter total mortality. Although animal trials predict a lower hemorrhagic potential for LMWHs, the incidence of bleeding complications is generally similar to that observed with UFH. Outpatient management of DVT with LMWHs has shown comparable safety and efficacy with inpatient UFH use but a shorter hospital stay.

CONCLUSIONS

Because LMWHs are as safe and as effective as UFH, and because of their more convenient method of administration, they can be considered valuable alternatives for the treatment of DVT. Savings generated by less intensive laboratory monitoring and the possibility of early hospital discharge and outpatient therapy may outweight the higher acquisition cost of LMWHs.

Integrins in point contacts mediate cell spreading: factors that regulate integrin accumulation in point contacts vs. focal contacts

We have studied the function and distribution of the alpha 1 beta 1, alpha 5 beta 1 and alpha 6 beta 1 heterodimers on type-1 astrocytes with antibodies specific for integrin subunits (alpha 1, alpha 5, alpha 6, and beta 1). The alpha 1 beta 1 heterodimer mediates adhesion to laminin and collagen, the alpha 5 beta 1 to fibronectin in an RGD-dependent manner. The alpha 5 beta 1 integrin is found in focal contacts in long-term cultures of well-spread astrocytes colocalizing with vinculin and the termini of actin stress fibers. alpha 1 beta 1 heterodimers can occasionally be found as small aggregates within focal contacts but they do not accumulate there. Instead, alpha 1 beta 1 integrins are found in punctate deposits called point contacts which are distributed over the upper and the lower cell surfaces whether laminin, collagen, fibronectin or polylysine is used as a substratum. Unlike focal contacts, point contacts contain clathrin but rarely codistribute with actin or vinculin. Two observations indicate that these point contacts are functional. First, mAb 3A3, directed against the rat alpha 1 subunit, inhibits the attachment of astrocytes to laminin and collagen. Second, during the spreading of astrocytes, a band of point contacts forms around the cell perimeter at a time when no focal contacts are visible. While alpha 1 beta 1 integrins are found only in point contacts in astrocytes, the alpha 6 beta 1 integrin, another laminin receptor, is localized within focal contacts. Moreover, alpha 1 beta 1 heterodimers accumulate in focal contacts in fibroblasts. Thus, the alpha subunit contributes, independent of its ligand, to functional integrin heterodimer accumulation in focal contacts or in point contacts. This accumulation varies among different cell types with apparently identical heterodimers as well as with the motile state (spreading vs. flattened) of the same cells.

[A new technic of cerebral protection. Surgery of the aortic arch]

A new technique of cerebral protection during surgery of the aortic arch is described. It is based on electric perfusion of the carotid arteries with low temperature (6 degrees-10 degrees) blood. This requires the adjunction on the cardiopulmonary bypass of an independent heat-exchanger. The first results obtained in 6 patients showed perfect protection of the brain throughout the surgical procedure, with early recovery from anaesthesia and complete absence of neurological sequelae. There were no deaths.

[Repeated valvular replacements]

After more than two decades of cardiac valve replacement surgery, the number of reoperations has increased and third or even fourth replacements are no longer rare occurrences. Of the 2072 valves prostheses implanted at the Hôpital Foch between 1970 and December 1984, 134 (6.4%) have been changed at least once and 27 prostheses (1.3%) have been replaced three or more times in 23 patients. Eighteen patients were operated on three times and 5 patients 4 times, a total of 73 operations. Ten patients had aortic valve prostheses, 7 had mitral valve prostheses and 6 had double aortic and mitral valve prostheses. The technical difficulties due to previous cardiac surgery were not great or easily surmounted as every procedure was performed by a median sternotomy and only 2 out of 50 required cannulation of the femoral vessels for cardiopulmonary bypass. The repair itself consisted of simple valve replacement in 3 out of 4 cases (30 single and 3 double valve replacements, 3 valve reinsertions). The other operations required more complex techniques such as remodelling of the ring of insertion or the use of a valved tube. None of the patients died in the operating theatre. However, 3 patients died during the hospital period (13%) and there were 2 late deaths (10%) and 1 patient (5%) was lost to follow-up. The 17 survivors were followed up for 3 to 148 months (average 42 months). Half the patients are now in functional Classes I or II of the NYHA classification. These results show that repeated valve replacement has an acceptable operative risk.(ABSTRACT TRUNCATED AT 250 WORDS)

[Computerized management of the medical record in cardiac surgery. Experience at Foch Hospital]

Between 1979 and 1983, about 2 000 case reports of patients undergoing cardiac surgery were computerised. The availability of the centralised computer facilities of Hôpital Foch made this experiment possible. The computerised case notes were divided into several chapters in which a certain amount of data was compulsive and provision was made for the addition of further information. The data was introduced in the form of a numerical code out of a possible choice of 700 contained in a dictionary. A terminal located in the department was used to introduce the information or to consult a given case file directly. Statistical analysis of the cases was performed using APL language, the basis of which must be known in order to continue interrogation, the reply being almost immediate. Several examples of the use of the system are given: number of patients, average duration of surgery, characteristics of the ten oldest patients. Other studies include the use of double entry tables to determine the relationship between two variables such as the variation of cardiothoracic index and the degree of postoperative bleeding. Each case takes about 20 minutes to be coded; the number of cases not entered has decreased greatly year by year. The differences in language used in comparison with already existing systems are: the use of syntax, the possibility of dating events, an "open" dictionary. The main drawbacks of the system are: forgetting to code certain data and restrictions of interrogation (easier for fixed than for facultative data). The overall results have been clearly positive.(ABSTRACT TRUNCATED AT 250 WORDS)

[Dissection of the ascending aorta after aortic valve replacement]

From October, 1969 to December, 1982, 1117 aortic valve replacements were performed at the Foch Medico-Surgical Centre. Five of these operations (0.4%) were followed, within 6 months to 6 years (mean 37 months), by acute dissection of the whole ascending aorta with a varying degree of extension further down. Such accidents raise problems of aetiology, diagnosis, treatment and possibly prevention. All 5 patients had an emergency operation with prosthetic replacement of the ascending aorta; in some cases the 2 cylinders were glued to the distal and proximal aortic stumps. The other forms of treatment were related to the lesions encountered. All patients survived and underwent follow-up angiography after 6 months to 5 1/2 years. Lesions of cystic necrosis of the media were regularly found at histology. In every case during the first operation the surgeon reported that the aorta was dilated or particularly fragile. The question therefore arises as to whether ascending aortas that are fragile and of more than 5 cm in diameter should be systematically replaced.

[A new surgical technic for the treatment of left ventricular aneurysm: the overcoat aneurysmoplasty. Preliminary results. 11 cases]

The classical surgical techniques used in post-myocardial infarction left ventricular aneurysms consist in resecting as much as possible of visible fibrous tissues and closure of the two borders by "U"--shaped sutures supported by a Teflon bond. There are two drawbacks to this approach: resection often involves the surface arterial network which often has a significant role to play in vascularising the remaining myocardium; fibrous, akinetic or dyskinetic zones of the anterior 2/3 of the interventricular septum cannot be resected. The proposed technique consists in limiting the surface of resection and in lowering the left border of the aneurysm as far as the posterior 1/3 of the septum. The septum is then sutured over the aneurysm to the antero-lateral wall of the left ventricle. Ten patients were operated using this technique: there were no operative deaths; preoperative cardiac failure regressed in 4 out of 5 patients; one patient was operated for unstable ventricular tachycardia, the arrhythmias disappeared after surgery; one patient operated during the 3rd week for left ventricular pseudo-aneurysm required intra-aortic balloon pumping and developed episodes of VT which finally resolved.

[Aortocoronary bypass with 10 years' follow-up. Apropos of 183 cases]

Between 1970 and 1972, 183 patients were admitted to the CMC Foch (Pr D. Guilmet) for saphenous vein aorto-coronary bypass surgery. Ten years later a questionnaire was sent to the patient and his cardiologist and the two replies were analysed. Before surgery, all patients had invalidating angina: 12 p. 100 had unstable angina, 61 p. 100 had previous myocardial infarction. Preoperative coronary angiography showed triple vessel disease in 64,5 p. 100, double vessel disease in 18,6 p. 100 and single vessel disease in 14,2 p. 100. There hundred and thirty two grafts were performed (average 1,8 per patient); 42 endarteriectomies were also carried out, 35 on the right coronary artery. Complete revascularisation was achieved in 95 cases (52 p. 100). The incidence of perioperative infarction was 17,5 p. 100 and operative mortality was 7,6 p. 100. Thirty two patients (19 p. 100) died during the 10 year study period; 11 deaths were of cardiovascular origin. The 10 year actuarial survival rate was 66 p. 100. Half the patients are asymptomatic and nearly two thirds take no anti-anginal therapy. The patency of the grafts was chacked in about half the cases and was found to be 72,8 p. 100 at one year. From the professional point of view, two thirds of patients returned to full time working one year after surgery. The degree of activity at 10 years is only known in 87 cases; half these patients are working and a quarter have retired normally. This study shows that: --coronary bypass surgery has excellent long-term effects on symptoms; --the incidence of infarction and survival are comparable to other reported studies; --patients with triple or double vessel disease may have lived longer after surgery than had they been treated medically.

[Surgery of recurrent aortic dissection. Apropos of 6 cases]

The authors report a series of 6 cases of recurrent dissection, 4 of which were treated surgically, out of a total of 64 acute dissections of the aorta referred to the CMC Foch, between January 1969 and October 1981. Three types of recurrent dissection were identified: --"de novo" recurrent dissection: a new dissection occurring in part of the aorta previously unaffected with a new intimal tear; --recurrent dissection due to extension of the previous dissection; --"in situ" recurrent dissection. Surgery is the treatment of choice because of the poor prognosis. Extensive resection (sometimes carried out in several stages) and deep hypothermia are valuable techniques when part of the aorta giving off arteries to vital organs has to be replaced. The use of GRF biological glue in the treatment of the original acute dissection has been a significant advance in the prophylaxis of recurrent dissection as it ensures better repair of the distal false lumen (27% persistent false lumens). With respect to an extensive replacement of the dissected vessel, the authors advise operation in several stages, especially in young subjects with Marfan's syndrome who are at high risk of recurrent dissection. All cases of acute dissection of the aorta, operated or not, should be followed up indefinitely with clinical and radiological examination, completed, when necessary, by an angioscan and an aortography.

[Coarctation and dystrophic aneurysm of the thoracic aorta (author's transl)]

Coarctation and dystrophic aneurysm of the thoracic aorta are seldom associated. In this series of 6 patients the aneurysm, often voluminous, was located on the ascending aorta in 1 case, on the distal part of the aortic arch in 3 cases and on the descending aorta in 2 cases. Surgical treatment consisted of resection and prosthetic replacement of the coarcted and aneurysmal segment under extracorporeal circulation. In a 13-years old patient, however, the coarctation was repaired but the aneurysm of the descending aorta below it was deliberately left in situ. All six patients are now asymptomatic. Post-operative angiography was performed in 4 cases with satisfactory results. In all cases the dystrophic aneurysm resulted from lesions of the elastic fibers of the tunica media and was therefore different from other aneurysms associated with coarctations.

[Calcifying obstructive disease of the descending thoracic aorta]

The authors present the first surgically treated case of calcifying obstructive disease of the descending thoracic aorta. The diagnosis was based upon the coexistence of an aortic isthmus coarctation syndrome together with massive calcifications seen by chest X-ray. The aetiology remains uncertain but the authors tend in favour of an atheromatous aetiology. Cure was obtained by simple surgical treatment.