Bioelectronic organ-based sensor for microfluidic real-time analysis of the demand in insulin.

On-line and real-time analysis of micro-organ activity permits to use the endogenous analytical power of cellular signal transduction algorithms as biosensors. We have developed here such a sensor using only a few pancreatic endocrine islets and the avoidance of transgenes or chemical probes reduces bias and procures general usage. Nutrient and hormone-induced changes in islet ion fluxes through channels provide the first integrative read-out of micro-organ activity. Using extracellular electrodes we captured this read-out non-invasively as slow potentials which reflect glucose concentration-dependent (3-15 mM) micro-organ activation and coupling. Custom-made PDMS-based microfluidics with platinum black micro-electrode arrays required only some tens of islets and functioned at flow rates of 1-10 µl/min which are compatible with microdialysis. We developed hardware solutions for on-line real-time analysis on a reconfigurable Field-Programmable Gate Array (FPGA) that offered resource-efficient architecture and storage of intermediary processing stages. Moreover, real-time adaptive and reconfigurable algorithms accounted for signal disparities and noise distribution. Based on islet slow potentials, this integrated set-up allowed within less than 40 µs the discrimination and precise automatic ranking of small increases (2 mM steps) of glucose concentrations in real time and within the physiological glucose range. This approach shall permit further development in continuous monitoring of the demand for insulin in type 1 diabetes as well as monitoring of organs-on-chip or maturation of stem-cell derived islets.

A tensegrity driven DNA nanopore.

Control of transport across membranes, whether natural or synthetic, is fundamental in many biotechnology applications, including sensing and drug release. Mutations of naturally existing protein channels, such as hemolysin, have been explored in the past. More recently, DNA channels with conductivities in the nanosiemens range have been designed. Regulating transport across DNA channels in response to external stimuli remains an important challenge. Previous designs relied on steric hindrance to control the inner diameter of the channel, which resulted in unstable electric signatures. In this paper we introduce a new design to control electric channel conductance of a DNA nanopore. The tensegrity driven mechanism inhibits the flux of small analytes while keeping a tightly controlled ionic transport modulated by the addition of specific DNA sequences. Current signals are clearly defined, with no sign of gating, opening new perspectives in single molecule DNA sensing.

Adenylyl cyclase 8 is central to glucagon-like peptide 1 signalling and effects of chronically elevated glucose in rat and human pancreatic beta cells.

AIMS/HYPOTHESIS: Glucose and incretins regulate beta cell function, gene expression and insulin exocytosis via calcium and cAMP. Prolonged exposure to elevated glucose (also termed glucotoxicity) disturbs calcium homeostasis, but little is known about cAMP signalling. We therefore investigated long-term effects of glucose on this pathway with special regard to the incretin glucagon-like peptide 1 (GLP-1). METHODS: We exposed INS-1E cells and rat or human islets to different levels of glucose for 3 days and determined functional responses in terms of second messengers (cAMP, Ca(2+)), transcription profiles, activation of cAMP-responsive element (CRE) and secretion by measuring membrane capacitance. Moreover, we modulated directly the abundance of a calcium-sensitive adenylyl cyclase (ADCY8) and GLP-1 receptor (GLP1R). RESULTS: GLP-1- or forskolin-mediated increases in cytosolic calcium, cAMP-levels or insulin secretion were largely reduced in INS-1E cells cultured at elevated glucose (>5.5 mmol/l). Statistical analysis of transcription profiles identified cAMP pathways as major targets regulated by glucose. Quantitative PCR confirmed these findings and unravelled marked downregulation of the calcium-sensitive adenylyl cyclase ADCY8 also in rat and in human islets. Re-expression of ADCY8, but not of the GLP1R, recovered GLP-1 signalling in glucotoxicity in INS-1E cells and in rat islets. Moreover, knockdown of this adenylyl cyclase showed that GLP-1-induced cAMP generation, calcium signalling, activation of the downstream target CRE and direct amplification of exocytosis by cAMP-raising agents (evaluated by capacitance measurement) proceeds via ADCY8. CONCLUSIONS/INTERPRETATION: cAMP-mediated pathways are modelled by glucose, and downregulation of the calcium-sensitive ADCY8 plays a central role herein, including signalling via the GLP1R.

[Advances in surgery for carotid stenosis. 900 operations (1983-1994)]. / Les progrès de la chirurgie des sténoses carotidiennes. 900 interventions (1983-1994).

OBJECTIVES: To evaluate morbidity and mortality in carotid endarterectomy in a personal series. METHODS: Nine hundred endartectomies were performed from 1983 to 1994. All patients had > 70% carotid narrowing. Five hundred five patients underwent without preoperative angiography. RESULTS: Outcome was analyzed for 3 periods showing decreasing mortality from 4.56% in 1983-86 to 0.67% in 1990-1994. CONCLUSION: The reduction in morbidity and mortality resulted from the combined effects of pre-, per-, and post-operative care including noninvasive preoperative diagnosis of internal carotid artery stenosis using ultrasound duplex and surgery without previous angiography, delayed surgery in case of recent prolonged hemispheric deficit or of ischemic defect detected on computed tomography (CT) or magnetic resonance imaging (MRI), cerebral evaluation with CT-scan or MRI the day before operation, surgery under locoregional anesthesia, monitoring of arm arterial blood pressure during the first 24 hours following surgery.

[Carotid surgery without systematic preliminary angiography. 402 patients treated by surgery between 1986 and 1992]. / Chirurgie carotidienne sans angiographie préalable systématique. 402 patients opérés entre 1986 et 1992.

Ultrasonography of the carotid bifurcation is a high performance technique for the detection of carotids stenosis. Associated with Doppler and echography, ultrasonography offers a means of precisely evaluating atheromatous stenoses of the bifurcation. The degree of narrowing can be calculated from the pulsed Doppler recordings and colour echo-Doppler measurements, reducing the subjective interpretation factor (the operator-dependent nature of the exploration is no longer related to data collection). Most severe stenoses can be diagnosed with these techniques. The question now is whether carotid angiography is still necessary to establish the indication for surgical endarterectomy. We attempted to give an answer based on our prospective series of 402 endarterectomies of the carotid bifurcation performed between 1986 and 1992 without prior routine angiography. Arteriography was performed occasionally in the pre-operative work-up but was limited to cases in which the ultrasonography was judged insufficient. We observed a mortality of 0.25% and a morbidity of 0.5%. This diagnostic approach is justified by its lower cost and reduced risk due to arteriography. In addition, unidentified arterial lesions downstream have little or no effect on indications and outcome.

[Post-traumatic aortic valve insufficiencies]. / Les insuffisances aortiques post-traumatiques.

Aortic regurgitation due to closed chest trauma is rare. It is related either to a valve lesion itself (ruptured cusp) or to trauma of the ascending aorta (subadventitial rupture with prolapse of the underlying aortic valve cusp). Four cases are described, 2 men and 2 women aged 30 to 66 years, after severe injuries in road traffic accidents: three patients had rupture of the aorta and the other had isolated rupture of the non-coronary aortic valve cusp. This pathology is unique due to the pathogenic mechanism associated with multiple thoracic injuries (right costal flap, sternal fracture, pulmonary contusion ...). The polytraumatic context explains the diagnostic difficulties and the secondary importance of the valve problem. Late surgery of these lesions was conservative in 3 cases: valve replacement was necessary in 1 case. If the haemodynamic tolerance of the aortic regurgitation is good, surgery should be deferred until the polytraumatic emergency has been dealt with. Good surgical results, often with conservative procedures, encourage earl operation after the acute polytraumatic period.

[Colonic angiodysplasia with chronic digestive hemorrhage cured after valvular replacement for aortic valve stenosis]. / Angiodysplasie colique avec hémorragie digestive chronique guérie après remplacement valvulaire pour sténose aortique.

Aortic stenosis is found in 15 to 25% of patients with gastrointestinal angiodysplasia. The usual treatment for haemorrhagic angiodysplasia associated with aortic stenosis is the same as for other types of gastrointestinal angiodysplasias: segmental intestinal resection, electrocoagulation and laser photocoagulation. The authors report the case of a 73 year old woman with a long history of gastro-intestinal bleeding and chronic anaemia requiring a number of hospital admissions for blood transfusions. The cause of this bleeding remained obscure for many years, as it was initially thought to be due to portal hypertension complicating cyrrhosis and a surgical porto-caval shunt was performed. Later, angiodysplasia of the colon was recognised and a segmental colonic resection was performed. These two surgical procedures had no effect on the chronic bleeding and finally the patient was referred for a gram negative endocarditis complicating aortic stenosis, previously considered to be non-surgical. After controlling the infection, the patient was sent for surgery of the aortic valve disease with mitral regurgitation in view of progressive degradation of left ventricular function. A double valve replacement with bioprostheses was undertaken with no complication. Finally, three years now after valve replacement, no further bleeding has occurred and control colonoscopy is normal. In the light of this case and a review of the literature of about 30 similar cases, the physiopathology and management of these patients is discussed with respect to the choice of valve prosthesis and the attitude to anticoagulant therapy. These observations suggest that in the presence of valvular heart disease at a surgical stage associated to an angiodysplasia, it is preferable to propose valve surgery to start with. Gastro-intestinal surgery is only indicated if haemorrhage persists after a period of observation.

[Ischemic vascular complications following thrombopenia induced by heparin. Diagnostic and therapeutic problems]. / Complications vasculaires ischémiques secondaires aux thrombopénies induites par l'héparine. Problèmes diagnostiques et thérapeutiques.

The authors report 21 cases of heparin-induced thrombocytopenia with ischemic vascular complications. The clinical presentations were peripheral arterial ischemia (16 cases), hemiplegia (1 case) and deep vein thrombosis (4 cases). The vascular surgeon confronted by these complications in an emergency situation should recognise the difficulties of clinical diagnosis (atypical forms) and biological investigations (problems of tests of platelet aggregation). Arterial occlusions are usually accessible to disobliteration with a Fogarty catheter without peroperative heparinisation. Delayed diagnosis explains the seriousness of these complications; in our series of 21 patients, there were 2 deaths, 1 paraplegia, 4 amputations due to arterial problems, 4 severe post-deep vein thrombosis conditions, two of which followed trans-metatarsal amputation. The diagnosis of heparin-induced thrombocytopenia implies immediate withdrawal of heparin therapy. A relay with a low molecular weight heparin is not without risk and should only be undertaken after a negative platelet aggregation test (with the low molecular weight heparin). These tests are rarely practicable in emergency situations and a relay using oral anti-vitamin K antagonists with a rapid onset of action is probably the safest option.

[A "non-narrowing" patch using the superior thyroid artery in surgery of carotid arteries]. / Patch de "non-rétrécissement" utilisant l'artère thyroïdienne supérieure en chirurgie carotidienne.

It seems to be generally agreed that a closing patch is necessary after carotid endarterectomy. The materials utilized (prostheses or veins) having their own morbidity, we prefer to use a piece taken from the superior thyroid artery; Satisfactory results were obtained in the first 26 cases. This autologous biological material has the advantage of being an arterial structure (therefore compatible with the sutured artery) which is obtained in situ and spares the venous system.

[Anuria associated with an aorto-iliac aneurysm. Apropos of a case]. / Anurie associée à un anévrysme aorto-iliaque. A propos d'une observation.

The authors report a case of a perianeurysmal retroperitoneal fibrosis (RPF) with oligoanuric renal failure. A complete assessment was performed with computed tomography. Bilateral ureteral catheterization restored normal renal function and allowed surgical treatment to be performed including an aorto-iliac replacement and a bilateral ureterolysis with intra-peritoneal diversion of the ureter. A review of the literature revealed 15 similar cases. Pathophysiology and treatment of the retroperitoneal peri-aneurysmal fibrosis are discussed.

[Pelvic arteriovenous fistula after ligation of the spermatic cord]. / Fistule artério-veineuse pelvienne après ligature du cordon spermatique.

The authors report the case of a 40 year old man undergoing left orchiectomy for Leydig cell tumour. Eight months later, the patient presented with a thrill in the left femoral triangle which angiography revealed to be due to a voluminous pelvic arteriovenous fistula arising at the expense of the left hypogastric artery, especially the arteries supplying the external genitalia. Surgical repair of the arteriovenous fistula was performed without prior embolisation. This haemorrhagic surgery was facilitated by the use of a blood recovery apparatus. The immediate postoperative course was uneventful and follow-up angiography one year later showed perfect stability of the result. This case offers an occasion to recall the risks of fistula during massive ligation of arteriovenous pedicles even in the case of small pedicles which should be treated with the same preventive approach as for the renal or splenic pedicle, i.e. separate ligation of the arterial and the venous element.

[Value of measuring transcutaneous oxygen pressure in arterial disease of the legs]. / Intérêt de la mesure de la pression transcutanée d'oxygène dans l'artériopathie des membres inférieurs.

The authors specify the methods used for measuring teh transcutaneous oxygen pressure (TcPO2), then present the four main advantages of the TcPO2. 1. Although the decision to amputate remains controlled by the clinical evaluation, TcPO2 is useful when one has to choose to preserve or not the heel support or the knee joint, when hesitating on the indication of amputation or the nature of the pain of a stump. Two measurements are crucial: a value of TcPO2 in a decubitus position greater than 30 mmHg at the amputation level seems to guarantee a primary healing, while under 10 mmHg, failure is the rule. 2. Correlations between the Fontaine classification and TcPO2 measured on the fore-foot in decubitus position, show that, at stages I and II, the TcPO2 is not significantly decreased in comparison with the control group (54 +/- 12 mmHg at stage I, 49 +/- 11 mmHg at stage II) and that at stages III and IV, TcPO2 is significantly much lower than at stages I and II and the value of 10 mmHg seems a remarkable threshold defining severe ischemias (12 +/- 15 mmHg at stage III, 3 +/- 5 mmHg at stage IV). 3. A prospective study of 66 arterial disease of the lower extremities cases, at stages II and IV, validated by a TcPO2 measured at the fore-foot in decubitus position less than 10 mmHg, and which could all benefit from reconstructive arterial surgery, is presented.(ABSTRACT TRUNCATED AT 250 WORDS)