Defects in TLR3 expression and RNase L activation lead to decreased MnSOD expression and insulin resistance in muscle cells of obese people.

Obesity is associated with chronic low-grade inflammation and oxidative stress that blunt insulin response in its target tissues, leading to insulin resistance (IR). IR is a characteristic feature of type 2 diabetes. Skeletal muscle is responsible for 75% of total insulin-dependent glucose uptake; consequently, skeletal muscle IR is considered to be the primary defect of systemic IR development. Interestingly, some obese people stay insulin-sensitive and metabolically healthy. With the aim of understanding this difference and identifying the mechanisms responsible for insulin sensitivity maintenance/IR development during obesity, we explored the role of the latent endoribonuclease (RNase L) in skeletal muscle cells. RNase L is a regulator of innate immunity, of double-stranded RNA sensors and of toll-like receptor (TLR) 4 signaling. It is regulated during inflammation by interferons and its activity is dependent on its binding to 2-5A, an oligoadenylate synthesized by oligoadenylate synthetases (OAS). Increased expression of RNase L or downregulation of its inhibitor (RLI) improved insulin response in mouse myogenic C2C12 cells and in primary human myotubes from normal-weight subjects treated with palmitate, a saturated free fatty acid (FFA) known to induce inflammation and oxidative stress via TLR4 activation. While RNase L and RLI levels remained unchanged, OAS level was decreased in primary myotubes from insulin-resistant obese subjects (OB-IR) compared with myotubes from insulin-sensitive obese subjects (OB-IS). TLR3 and mitochondrial manganese superoxide dismutase (MnSOD) were also underexpressed in OB-IR myotubes. Activation of RNase L by 2-5A transfection allowed to restore insulin response, OAS, MnSOD and TLR3 expression in OB-IR myotubes. Due to low expression of OAS, OB-IR myotubes present a defect in RNase L activation and TLR3 regulation. Consequently, MnSOD level is low and insulin sensitivity is reduced. These results support that RNase L activity limits FFA/obesity-induced impairment of insulin response in muscle cells via TLR3 and MnSOD expression.

RNase L controls terminal adipocyte differentiation, lipids storage and insulin sensitivity via CHOP10 mRNA regulation.

Adipose tissue structure is altered during obesity, leading to deregulation of whole-body metabolism. Its function depends on its structure, in particular adipocytes number and differentiation stage. To better understand the mechanisms regulating adipogenesis, we have investigated the role of an endoribonuclease, endoribonuclease L (RNase L), using wild-type and RNase L-knockout mouse embryonic fibroblasts (RNase L(-/-)-MEFs). Here, we identify C/EBP homologous protein 10 (CHOP10), a dominant negative member of the CCAAT/enhancer-binding protein family, as a specific RNase L target. We show that RNase L is associated with CHOP10 mRNA and regulates its stability. CHOP10 expression is conserved in RNase L(-/-)-MEFs, maintaining preadipocyte state while impairing their terminal differentiation. RNase L(-/-)-MEFs have decreased lipids storage capacity, insulin sensitivity and glucose uptake. Expression of ectopic RNase L in RNase L(-/-)-MEFs triggers CHOP10 mRNA instability, allowing increased lipids storage, insulin response and glucose uptake. Similarly, downregulation of CHOP10 mRNA with CHOP10 siRNA in RNase L(-/-)-MEFs improves their differentiation in adipocyte. In vivo, aged RNase L(-)/(-) mice present an expanded adipose tissue, which, however, is unable to correctly store lipids, illustrated by ectopic lipids storage in the liver and in the kidney. These findings highlight RNase L as an essential regulator of adipogenesis via the regulation of CHOP10 mRNA.

Muscle mitochondrial metabolism and calcium signaling impairment in patients treated with statins.

The most common and problematic side effect of statins is myopathy. To date, the patho-physiological mechanisms of statin myotoxicity are still not clearly understood. In previous studies, we showed that acute application in vitro of simvastatin caused impairment of mitochondrial function and dysfunction of calcium homeostasis in human and rat healthy muscle samples. We thus evaluated in the present study, mitochondrial function and calcium signaling in muscles of patients treated with statins, who present or not muscle symptoms, by oxygraphy and recording of calcium sparks, respectively. Patients treated with statins showed impairment of mitochondrial respiration that involved mainly the complex I of the respiratory chain and altered frequency and amplitude of calcium sparks. The muscle problems observed in statin-treated patients appear thus to be related to impairment of mitochondrial function and muscle calcium homeostasis, confirming the results we previously reported in vitro.

[Late thrombosis of a drug-eluting coronary stent after antiplatelet therapy discontinuation]. / Thrombose tardive d'une endoprothèse coronaire pharmacoactive après arrêt des agents antiplaquettaires.

We reported the late thrombosis of a drug-eluting coronary stent related to discontinuation of antiplatelet therapy for venous surgery of the right leg more than half and a year after its implantation. After this acute myocardial infarction, a cardiac assistance device has to be used as a bridge to transplantation because of end stage ischaemic cardiopathy. Antiplatelet therapy management must be revisited for eluting stents, which can clot lately after its implantation.

[Current treatment of acute type A aortic dissection. Surgical treatment and treatment of malperfusion syndrome]. / Prise en charge actuelle des dissections aortiques de type A. Traitement chirurgical et traitement des syndromes de malperfusion.

Acute type A aortic dissection is a surgical emergency. Treatment is based on dissected ascending aortic replacement and correction of an associated aortic insufficiency. Catheterization of the axillary artery, open distal anastomosis and systematic resection of the intimal tear are the main surgical evolutions of the last years. They allowed to significantly reduce intraoperative mortality rate particularly due to bleeding. Thirty days mortality rate of operated aortic dissection is about 20 to 30%. Visceral malperfusion syndromes induced by aortic dissection represent an important cause of postoperative death. An early diagnosis and treatment appears necessary. Thoracoabdominal CT scan allows understanding mechanisms inducing malperfusion. Aortography and an emergency endovascular procedure allow restoring arterial blood flow before renal or mesenteric irreversible ischemia. Collaboration between radiologist, anesthesiologist and surgeon is necessary to optimize survival of acute type A aortic dissection.

Características clínicas de una serie de 134 pacientes con infarto lacunar / Clinical characteristics of a serie of 134 patients with lacunar infarct

Objetivo: estudio comparativo del infarto lacunar IL versus infarto de otra categoría clínica INL. Pacientes/método: análisis prospectivo de 354 pacientes con ictus isquémico ingresados consecutivamente en nuestro hospital durante un año. Se consideraron dos grupos IL (37,9%9 e INL (62,1%). Se comparan edad, sexo, factores de riesgo, grado de déficit neurológico, latencia de ingreso hospitalario, estancia media, evolución, mortalidad y pronóstico a los tres meses. Resultados: los pacientes con IL son más jóvenes (70,81 vs 75,05 años; p<0,0001), la gravedad del déficit neurológico es menor (p<0,0001), el pronóstico funcional semanal es significativamente mejor (p<0,0001) y presentan una menor mortalidad hospitalaria (p<0,001). No encontramos diferencia en la latencia de ingreso, pronóstico trimestral ni tampoco en los factores de riesgo vascular exceptuando la fibralación auricular (p<0,0001). El análisis multivariante confirma como predictores IL la diabetes mellitus (OR: 2.23), el desconocimiento de la hora de inicio del ictus (OR: 2.12), el índice de Barthel semanal (OR: 2,279, la fibrilación auricular (OR: 0.095), el antecedente de ictus previo (OR: 0,43) y una Escala Canadiense ≤ 5 en el momento del ingreso (OR: 0.193). Conclusión: la categoría clínica de IL cursa con factores de riesgo independientemente asociados (diabetes mellitus) y diferencias significativas en el pronóstico a corto plazo (estancia hospitalaria, desarrollo de complicaciones, mortalidad y calidad de vida a los siete días) (AU)

Aim: a comparative study between lacuanr infarct LI and non-lacunar infarct NLI. Patients/methods: a prospective analysis of 134 patients suffering from ischemic infarct that were consecutively hospitalized during a year. Two groups were considered: LI (39,1%) and NLI (62,1%). Age sex, risk factors, degree of neurological deficit, time for being in hospital, evolution, mortality and functional outcome at three months. Results: patients with LI are younger (70,81 vs 75,05 years; p<0,0001), with a mild degree of neurological deficit (p<0,0001), funcional outcome at the seventh day is better (p<0,0001) adn had a lower in hospital mortality (p<0,0001). We do not found any difference about time to be hospitalized, three-month functional outcome and risk factors except for atrial fibrilation (p<0,0001). Multivariate analysis confirms as predictors of Li diabetes mellitus (OR: 2.23), unknown time of stroke onset (OR; 2,12), the seven-day Barthel Index (OR:2,27) atrial fibrilation (OR; 0,095) previous stroke (OR; 0,43) and acute Canadian scale ≤5 (Or: 0,193). Conclusions: LI associates independent risk factors (diabetes mellitus) and significative differences in the immediate clinical features (median time of hospital-stay, mortality, seven-day funcional outcome) (AU)

[Visual neglect secondary to left frontal haemorrhage]. / Negligencia visual secundaria a hemorragia frontal izquierda.

INTRODUCTION: The term visual neglect refers to a lack of attention to visual stimuli coming from the contralateral hemifield. The patient does not seek objects in the abnormal field and often only sees half of a paragraph when reading. Although the right inferior parietal lobe is the most frequently damaged region, the same symptomatology can be due to injury to the frontal lobe, the basal ganglia and the thalamus. CASE REPORT: Female aged 71 with a mitral prosthesis and atrial fibrillation in treatment with dicumarols, who presented a left frontal parenchymatous haemorrhage. The exploration revealed right visual hemineglect without ipsilateral homonymous hemianopsia, associated to a right hemiparesis. DISCUSSION: Even when visual neglect has been described in lesions affecting the parietal lobe, especially on the right hand side, the same symptomatology can be due to injury to the basal ganglia, the thalamus and the frontal lobe. In this last case, it seems that the basis for the pathogenesis lies in the damage done to the underlying white matter, which would disconnect the posterior parietal cortex from the prefrontal cortex.

Negligencia visual secundaria a hemorragia frontal izquierda / Visual neglect secondary to left frontal haemorrhage

Introducción. El término negligencia visual hace referencia a una falta de atención a los estímulos visuales procedentes del hemicampo contralateral. El paciente no busca objetos en el campo anormal, y a menudo sólo lee la mitad del párrafo. Si bien el lóbulo parietal inferior derecho es la región más frecuentemente lesionada, la misma sintomatología puede obedecer a lesiones del lóbulo frontal, ganglios de la base y tálamo. Caso clínico. Mujer de 71 años de edad portadora de prótesis mitral con fibrilación auricular y en tratamiento con dicumarínicos, que presenta una hemorragia parenquimatosa frontal izquierda. En la exploración se objetivó una heminegligencia visual derecha sin hemianopsia homónima ispilateral, asociada a una hemiparesia derecha. Discusión. Aun cuando la negligencia visual se ha descrito en lesiones que afectan al lóbulo parietal, sobre todo el derecho, la misma sintomatología puede obedecer a lesiones de los ganglios de la base, tálamo y lóbulo frontal. En este último supuesto, parece ser que la base patogénica radica en la afectación de la sustancia blanca subyacente, que desconectaría el córtex parietal posterior del córtex prefrontal (AU)

Introduction. The term visual neglect refers to a lack of attention to visual stimuli coming from the contralateral hemifield. The patient does not seek objects in the abnormal field and often only sees half of a paragraph when reading. Although the right inferior parietal lobe is the most frequently damaged region, the same symptomatology can be due to injury to the frontal lobe, the basal ganglia and the thalamus. Case report. Female aged 71 with a mitral prosthesis and atrial fibrillation in treatment with dicumarols, who presented a left frontal parenchymatous haemorrhage. The exploration revealed right visual hemineglect without ipsilateral homonymous hemianopsia, associated to a right hemiparesis. Discussion. Even when visual neglect has been described in lesions affecting the parietal lobe, especially on the right-hand side, the same symptomatology can be due to injury to the basal ganglia, the thalamus and the frontal lobe. In this last case, it seems that the basis for the pathogenesis lies in the damage done to the underlying white matter, which would disconnect the posterior parietal cortex from the prefrontal cortex (AU)

["Household items" : an alternative task to "animals" in the assessment of semantic verbal fluency: a validation study]. / "Cosas en una casa", una tarea alternativa a "animales" en la exploración de la fluidez verbal semántica: estudio de validación.

INTRODUCTION: The semantic verbal fluency (SVF) is usually evaluated with the task animals in 1 minute . This is a test widely applied in the screening of cognitive impairment. In our best knowledge there are not other alternatives categories for this task validated in our environment (Spanish as mother tongue, Spain). OBJECTIVE: To validate the category households items as an alternative parallel task to animals in the assessment of SVF. PATIENTS AND METHODS: Prospective assessment of two categories (animals and household items) in two groups: normal controls and patients with Alzheimer s disease (AD). CONTROL GROUP: n= 22 (13 M, 9 W); age: 73 5 years, education: 12 5 years; MMSE MEC 35: 30 4; Animals : 15 4. Percentile distribution 10th: 11; 50th: 15; 90th: 20; household items : 17 4. Percentile distribution: 10th: 12; 50th: 17; 90th: 22. AD group: n= 24 (9 M, 15 W); age: 74 5 years; education: 11 5 years; MMSE MEC 35: 17 8; Animals : 6 3. Percentile distribution: 10th: 2; 50th: 6; 90th: 9; household items : 6 4. Percentile distribution: 10th: 1; 50th: 6; 90th: 11. It is observed a positive correlation between the two categories (Spearman s Rho: 0.83, p< 0.0001). CONCLUSIONS: Both SVF categories had a similar distribution and a high correlation. This findings demonstrated the validity of the household items as an alternative and parallel form to animals in the assessment of SVF in patients with cognitive impairment or dementia.

'Cosas en una casa', una tarea alternativa a 'animales' en la exploración de la fluidez verbal semántica:estudio de validación / 'Household items': an alternative task to 'animals' in the assessment of semantic verbal fluency. A validation study

Introducción. La fluidez verbal semántica (FVS) se explora habitualmente con la tarea `animales en un minuto', un test que se utiliza generalmente para evaluar el deterioro cognitivo. En nuestro conocimiento no existen tareas de exploración alternativas para esta categoría validadas en nuestro medio (población española y el castellano como lengua materna). Objetivo. Validación de la categoría `cosas que hay en una casa' como forma alternativa para la categoría `animales' en la exploración de la FVS. Pacientes y métodos. Evaluación prospectiva de un grupo control y un grupo de pacientes con la enfermedad de Alzheimer (EA), de la FVS en dos categorías paralelas (animales y cosas en una casa). Resultados. Grupo control: n= 22 (13 H y 9 M); edad: 73ñ5 años; escolaridad:12ñ5 años; MEC-35: 30ñ4; `animales': 15ñ4. Dist. percentil: P-10: 11; P-50: 15; P-90: 20; `cosas en una casa': 17ñ4. Dist. percentil: P-10: 12; P-50: 17; P90: 22. Grupo Alzheimer: n= 24 (9 H y 15 M); edad: 74ñ5 años; escolaridad: 11ñ5 años; MEC-35: 17ñ8; `animales': 6ñ3. Dist. percentil: P-10: 2; P-50: 6; P-90: 9; `cosas en una casa': 6ñ4. Dist. percentil: P-10: 1; P-50: 6; P-90: 11. Se observa una correlación positiva entre ambas categorías, Rho: 0,83, p< 0,0001.Conclusiones. Ambas categorías de FVS presentan una distribución percentil similar y una alta correlación, lo que demuestra su validez y permite su utilización sin restricciones como categorías paralelas de exploración de la FVS en pacientes con deterioro cognitivo (AU)

[Opercular syndrome of vascular aetiology]. / Síndrome opercular de etiología vascular.

INTRODUCTION: Facio linguo masticatory paralysis resulting from bilateral lesion of the anterior opercular region, known today as Foix Chavany Marie syndrome, appears very frequently in adult patients as a consequence of generally ischemic vascular lesions, which directly affect the Rolandic opercula or the subcortical area surrounding them. However, forms that are secondary to infections, neoplasias and even unilateral lesions have been reported. CASE REPORT: Female patient, aged 70, with unknown auricular fibrillation, which started suddenly with right faciobrachial paresis secondary to a left striated ischemic infarction. Approximately 24 hours after beginning intravenous heparinization, the patient presents anarthria, facial hypomimia without asymmetries, dysphagia above all for liquids and bilateral lingual paresis. Extraoccular movements, blinking and corneal reflex were normal. Understanding of spoken and written language was maintained and there were no apraxias or agnosias. Neurological exploration was compatible with an opercular syndrome (OS). Urgent brain CT revealed the existence of a right cortiico subcortical temporal haemorrhage, in addition to the prior contralateral ischemia. The association of both lesions, ischemic and haemorrhagic, mirrored, justified all the symptomatology. DISCUSSION: Anterior OS is characterised by a bilateral voluntary central paresis of the muscles innervated by the 5th, 7th, 9th, 10th and 12th cranial pairs with preservation of emotional or automatic mobility. Underlying mechanisms are also discussed.

[Criteria for percutaneous non-closure of interatrial communications of the ostium secundum type by the Amplatzer septal occluder]. / Critères de non-fermeture percutanée des communications interauriculaires de type ostium secundum par l'Amplatzer septal occluder.

The aim of the study is to recognise the criteria preventing the percutaneous closure of an interatrial communication of the ostium secundum type for the Amplatzer septal occluder device. From January 1999 to December 2000, 121 consecutive patients with an average age of 24.8 +/- 19 years affected with an interatrial communication of the ostium secundum type underwent echocardiographic examination with transthoracic Doppler to evaluate the maximal diameter of the communication, the border dimensions, and the length of the interatrial septum; 92.5% of them underwent haemodynamic investigation to evaluate the shunt and the stretched diameter. Comparison of the umbrella group averages with the surgical group was performed by the Student test, and the frequencies by the Chi 2 test. ROC curves were drawn for the numeric parameters. After these 2 examinations, 68 patients underwent an attempt at percutaneous closure with 61 successful (84.7%) and 53 had a surgical closure straight off. The surgical group was younger, with a more significant shunt and a wider communication. The criteria for non-closure apart from abnormal pulmonary venous reflux were: insufficient border (59% of cases), diameter too wide (16%), multiperforate septum (16%) and insufficient septum length (9%). Percutaneous closure could be performed in 2/3 of interatrial communications without abnormal pulmonary venous reflux. Candidates for surgery were younger, with a more significant shunt and a wider diameter. In retrospect 8 patients of the surgical group could have had percutaneous closure and 7 patients of the umbrella group could have been sent straight for surgery.

Síndrome opercular de etiología vascular / Opercular syndrome of vascular aetiology

Introducción. La parálisis faciolinguomasticatoria por lesión bilateral de la región opercular anterior, conocida hoy como síndrome de Foix-Chavany-Marie, aparece en los pacientes adultos muy frecuentemente como consecuencia de lesiones vasculares generalmente isquémicas, que afectan directamente a los opérculos rolándicos o sus inmediaciones subcorticales. Se han descrito, no obstante, formas secundarias a infecciones, neoplasias e incluso lesiones unilaterales. Caso clínico. Paciente mujer, de 70 años de edad, con fibrilación auricular no conocida, que debuta bruscamente con paresia faciobraquial derecha secundaria a infarto isquémico estriado izquierdo. Aproximadamente 24 horas tras el inicio de la heparinización intravenosa, la paciente presentó anartria, hipomimia facial sin asimetrías, disfagia predominantemente para líquidos y paresia lingual bilateral. Los movimientos extraoculares, el parpadeo y el reflejo corneal eran normales. La comprensión del lenguaje oral y escrito se conservaba. No había apraxias ni agnosias. La exploración neurológica era compatible con un síndrome opercular (SO). La TAC cerebral de urgencia reveló la existencia de una hemorragia temporal corticosubcortical derecha, añadida a la previa isquémica con tralateral. La asociación de ambas lesiones, isquémica y hemorrágica, en espejo, justificaba toda la sintomatología. Discusión. El SO anterior se caracteriza por una paresia central voluntaria bilateral de los músculos inervados por los pares craneales V, VII, IX, X y XII, con preservación de la movilidad emocional o automática. Se discuten los mecanismos subyacentes (AU)

Ross operation for active culture-positive aortic valve endocarditis with extensive paravalvular involvement.

BACKGROUND: We evaluated the midterm results of the Ross operation in active advanced endocarditis. METHODS: Between June 1994 and June 2000 a pulmonary autograft aortic root replacement was performed in 11 consecutive patients who had urgent or emergent procedures for active endocarditis with extensive involvement of the aortic root (10 native, 1 prosthetic). Patients ranged in age from 26 to 45 years (median, 33 years). Indications for operation were uncontrolled infection (n = 5), hemodynamic deterioration (n = 3), or both (n = 3). Four patients were in the New York Heart Association class III, 6 in class IV, and 1 was operated on while in cardiogenic shock. Four patients (36%) suffered an embolic cerebrovascular accident preoperatively. The endocarditis affected the mitral valve in 2 patients and the tricuspid valve in 1 patient. RESULTS: There was no early or late death. Recurrent endocarditis was not detected in any of the patients during the follow-up period ranging up to 72 months (median, 40 months). CONCLUSIONS: The autograft may well be the best substitute for aortic root reconstruction in advanced endocarditis.

Fractures and nonunions of the carpal scaphoid in children.

Fractures of the carpal scaphoid in children show some quite remarkable differences with respect to fractures of the carpal scaphoid in adults. A review of the literature shows that fractures in children are more often located in the distal third, are more often incomplete and are usually not displaced. Our experience with 23 fresh fractures of the carpal scaphoid in children confirms these findings of the literature. Nonunion of the carpal scaphoid is exceedingly rare in children. When reviewing the literature we could find only 29 published cases of nonunion of the carpal scaphoid in children. In most articles describing carpal scaphoid nonunion in children, bone grafting is recommended as the treatment of choice. We report two children with a nonunion of the carpal scaphoid treated successfully by cast immobilization. Therefore, we propose that a child with a nonunion of the carpal scaphoid bone that has never been immobilized previously should be treated by cast immobilization. Surgery should be considered only if there is no indication of healing after 3 months of immobilization.

A recovery model of partial cardiopulmonary bypass in the rat.

This study was undertaken to develop a recovery model of cardiopulmonary bypass (CPB) in rats. Twenty male Wistar rats (475-550 g) were anaesthetized, mechanically ventilated and the femoral vessels cannulated. The extracorporeal circulation circuit comprised a roller pump, a venous reservoir and a modified Capiox 308 paediatric membrane oxygenator. Priming consisted of 20 ml of fresh homologous blood and 15 ml of colloid. Anticoagulation was achieved with heparin (500 IU/kg). Blood gas analysis, blood pressure monitoring and survival studies were performed in CPB (n=10) and Sham (n=10) rats. Partial CPB was always easily established and was conducted at a flow rate of 100 ml/kg/min for 90 min Blood gas analysis and blood pressure data did not differ between the two groups. All CPB rats survived and the 3-week follow-up period remained uneventful. The rat model of CPB was easy to perform and was associated with excellent survival. This recovery model should allow us to study the pathophysiological processes underlying post-CPB multiple organ dysfunction.

Is 10 minutes the optimum immersion time in 0.6% glutaraldehyde for human pericardium?

BACKGROUND AND AIM OF THE STUDY: Pericardial fixation with 0.6% glutaraldehyde is usually assessed by measuring the shrinkage temperature of the tissue: the higher the shrinkage temperature, the greater the degree of cross-linking induced between collagen molecules. Animal pericardium studies have shown maximum response to be obtained after brief immersion (10 min). Our aim was to evaluate the effect of glutaraldehyde immersion time on shrinkage temperature of human pericardium which, to our knowledge, has not yet been studied. METHODS: Pericardial strips were harvested from 40 patients undergoing cardiac surgery. Time of immersion in glutaraldehyde ranged from 3 min to 6 months. Fresh untreated human pericardium samples were used as controls. The relationship between shrinkage temperature and time of treatment with glutaraldehyde was studied using a regression analysis. RESULTS: Glutaraldehyde treatment of pericardial tissues caused an increase in shrinkage temperature that was related biphasically to the time of immersion in glutaraldehyde. Mathematical expression of this curve permitted glutaraldehyde immersion time to be evaluated in relation to the degree of optimal shrinkage temperature. The time required for optimal fixation with glutaraldehyde, as measured by shrinkage temperature, was 100+/-0.77 min. CONCLUSION: Our results suggested that a 10-min exposure to glutaraldehyde was insufficient for 'correct' fixation of human pericardium. Inadequate glutaraldehyde exposure of human pericardium may explain mid and long-term failures reported with this tissue in cardiac surgery.

About a double-body immersion horn system to be used for quantitative sonochemical studies

The majority of quantitative sonochemical studies in the 20-100-kHz frequency range are performed by using an immersion horn system. The new system described in this letter consists of a double immersion horn acted on by a single pair of piezoelectric ceramics. This instrument is well adapted to the quantitative measure of effects, i.e., variations in the rate constant of a specific reaction associated to the change of an experimental parameter. The gas effect, obtained by comparing the rate of a reaction under air and under argon, illustrates the efficiency of the system.

Vascular complications of osteochondromas.

PURPOSE: Osteochondromas are the most common benign tumor of the bone. They are sometimes responsible for vascular complications involving either veins or arteries, principally around the knee. METHODS: We report six cases of such complications. An extensive review of literature through a computerized research was performed. RESULTS: We found 97 cases that were previously reported in the English literature giving sufficient details and providing data on 103 cases for analysis. CONCLUSION: Surgical treatment of vascular complications of osteochondromas is recommended as an urgent procedure to avoid irreversible damages, such as arterial occlusion, embolism, or phlebitis. Prophylactic resection of osteochondromas in the vicinity of a vessel must be performed.

Video-assisted replacement or bypass grafting of the descending thoracic aorta with a new sutureless vascular prosthesis: an experimental study.

PURPOSE: The feasibility of the video-assisted insertion of a new sutureless vascular prosthesis was studied. METHODS: Seven sheep, weighing 25 to 35 kg, were operated on under general anesthesia. The animals were intubated with a single-lumen endotracheal tube and placed in the right lateral decubitus position. A thoracoscope was introduced in the 11th intercostal space, and a minithoracotomy (4 to 5 cm) was performed in the seventh intercostal space. After retraction of the lung, a short segment (10 cm) of the descending thoracic aorta was exposed. Our prosthesis was made of Dacron and was specifically designed to be inserted without a suture. After systemic heparinization, the aorta was cross-clamped with two vascular clamps introduced into the thoracic cavity through two 5-mm thoracic incisions. The aorta was either replaced (five cases) or bypass grafted (two cases). At the completion of the procedure, blood pressure was pharmacologically increased (5 mg intravenous bolus of epinephrine), and each anastomosis was checked for bleeding. All animals were killed, and the prosthesis was retrieved for macroscopic examination. RESULTS: The procedure was completed in each case without extension of the minithoracotomy. Insertion of the prosthesis was easy and fast, and completion of each anastomosis required 10 to 15 minutes. A 3- to 4-mm space between each clip was sufficient for proper attachment. All procedures were performed in less than 120 minutes. No bleeding was observed at the level of each anastomosis, even when a sustained high blood pressure was induced. The proper insertion of the prosthesis and the absence of any anastomotic stenosis was confirmed by means of macroscopic examination. CONCLUSION: Video-thoracoscopic replacement or bypass grafting of the descending thoracic aorta was easy with this new sutureless vascular prosthesis. Minimally invasive vascular surgery might be facilitated with such a prosthesis. However, long-term animal studies are required before human implantation can be undertaken.