Minimum energy pathways via quantum Monte Carlo.

We perform quantum Monte Carlo (QMC) calculations to determine minimum energy pathways of simple chemical reactions, and compare the computed geometries and reaction barriers with those obtained with density functional theory (DFT) and quantum chemistry methods. We find that QMC performs in general significantly better than DFT, being also able to treat cases in which DFT is inaccurate or even unable to locate the transition state. Since the wave function form employed here is particularly simple and can be transferred to larger systems, we suggest that a QMC approach is both viable and useful for reactions difficult to address by DFT and system sizes too large for high level quantum chemistry methods.

Excitation spectrum of a supersolid.

Conclusive experimental evidence of a supersolid phase in any known condensed matter system is presently lacking. On the other hand, a supersolid phase has been recently predicted for a system of spinless bosons in continuous space, interacting via a broad class of soft-core, repulsive potentials. Such an interaction can be engineered in assemblies of ultracold atoms, providing a well-defined pathway to the unambiguous observation of this fascinating phase of matter. In this Letter, we study by first principles computer simulations the elementary excitation spectrum of the supersolid, and show that it features two distinct modes, namely, a solidlike phonon and a softer collective excitation, related to broken translation and gauge symmetry, respectively.

Two waves of nuclear factor kappaB recruitment to target promoters.

Proinflammatory stimuli induce the rapid and transient translocation of nuclear factor (NF)-kappaB to the nucleus, where it activates transcription from several genes, including those encoding inflammatory cytokines and chemokines, adhesion molecules, and cytoprotective proteins. Using chromatin immunoprecipitation, we show that after an acute stimulation two distinct waves of NF-kappaB recruitment to target promoters occur: a fast recruitment to constitutively and immediately accessible (CIA) promoters and a late recruitment to promoters requiring stimulus-dependent modifications in chromatin structure to make NF-kappaB sites accessible (promoters with regulated and late accessibility [RLA]). Our results suggest that a mechanism of specificity in NF-kappaB-dependent transcriptional responses relies on the ability of individual stimuli to make RLA promoters accessible to NF-kappaB before its rapid extrusion from the nucleus.

The human toll signaling pathway: divergence of nuclear factor kappaB and JNK/SAPK activation upstream of tumor necrosis factor receptor-associated factor 6 (TRAF6).

The human homologue of Drosophila Toll (hToll) is a recently cloned receptor of the interleukin 1 receptor (IL-1R) superfamily, and has been implicated in the activation of adaptive immunity. Signaling by hToll is shown to occur through sequential recruitment of the adapter molecule MyD88 and the IL-1R-associated kinase. Tumor necrosis factor receptor-activated factor 6 (TRAF6) and the nuclear factor kappaB (NF-kappaB)-inducing kinase (NIK) are both involved in subsequent steps of NF-kappaB activation. Conversely, a dominant negative version of TRAF6 failed to block hToll-induced activation of stress-activated protein kinase/c-Jun NH2-terminal kinases, thus suggesting an early divergence of the two pathways.

Deparaffination time: a crucial point in histochemical detection of tissue copper.

The search for a sensitive histochemical method for revealing tissue copper has been the object of many workers in the past. In spite of multiple methods available, the occurrence in clinical practice of negative histochemical stains, even in cases with high copper levels demonstrated by quantitative methods is very high.This study was aimed at verifying the role of technical variations in the sensitivity of the Timm method and, in particular, the role of the dewaxing time of paraffin sections. To this end, 15 liver specimens, 10 from patients affected by Wilson's disease and 5 newborn livers were fixed in 10% formalin, paraffin embedded and routinaly processed. Four 4-micron sections from each case were rinsed in xylene for 10, 20, 60 min, and for 24 hrs. All sections were stained with Timm's method. In 13 out of the 15 liver biopsies utilized in this study, the sensitivity of Timm's method in revealing copper deposits in liver cells appeared to be dependent on the dewaxing time. In two other cases, reactivity of copper granules to Timm solution did not change significantly with the different deparaffination times. The best results were obtained by rinsing sections in xylene for 24 hrs, the worst in sections treated with xylen for 10 minutes. In particular, in five cases of Wilson's disease, Timm stain applied to sections following ten minutes of xylene were completely negative, while copper granules were clearly evidenced in the same section following an overnight bath in xylene. Our data show that an overnight bath of paraffin sections in xylene may completely change the sensitivity of Timm stain in revealing copper deposits in the liver, relaunching copper histochemistry in the diagnosis of copper-related liver diseases.

[Combined surgery of acute type A aortic dissections by ascending aorta replacement and bare stent]. / Chirurgie combinée des dissections aiguës de type A, par remplacement de l'aorte ascendante et endoprothèse non couverte.

UNLABELLED: Aim. After surgical treatment of type A aortic dissections a long segment of these aortas often remain dissected. Our goal was to analyse feasibility and first clinical and pathophysiological results of a combined treatment by ascending aorta replacement and stenting of the arch or descending aorta with Djumbodis(R) bare stents. PATIENTS AND METHODS: Twenty two cases from two centres were analyzed (Universitary Hospital of Parma and Rangueil Universitary Hospital of Toulouse). RESULTS: All the stents have been implanted with short times of circulatory arrest. Average follow-up was 278 days (0-2005). There were two peroperative deaths (9.1%). One year cumulate survival rate was 72.7%. Postoperative complications were mainly respiratory and renal. We have shown a reduction in number of perfused false lumen for aortic arches, more often stented, than for descending aortas (p=0.0104), and for dissected and stented segments versus dissected unstented segments (p=0.0083). CONCLUSION: Our study demonstrates feasibility of this combined procedure and its positive effect on pathophysiologic evolution. Long term results have to be evaluated, but we think promising to extend this treatment to the whole dissected aorta.

Gene transfer-mediated expression of physiological numbers of the type II decoy receptor in a myelomonocytic cellular context dampens the response to interleukin-1.

Available information suggests that the type II IL-1 receptor (RII) is a nonsignaling molecule which acts as a decoy for IL-1. The decoy function model for RII was supported by gene transfer experiments in fibroblasts and keratinocytes. Therefore, inhibition of IL-1 responsiveness after decoy RII gene transfer could reflect a non-physiological cellular context and receptor number. In the present study, constructs encoding RII or a cytoplasmic deletion mutant (delta 372-398) were transfected into U937 cells which express only low levels of RI detectable by RT-PCR. Gene transfer resulted in receptor numbers (approximately equal to 10(3)/cell) of the same order of magnitude as that found in normal myelomonocytic cells. Transfer of RII or a cytoplasmic deletion mutant into U937 did not increase responsiveness to IL-1, as assessed by IL-8 expression and production; it actually considerably dampened it. These results are consistent with the view that in a myelomonocytic cellular context, RII does not contribute to signaling and represents a unique pathway of negative regulation of the IL-1 system.

Asymptomatic patient reoperated on for severe proximal stenosis of circular sequential vein graft.

The case is described of a fifty year old man who underwent coronary bypass surgery using the circular sequential vein graft technique. At follow-up study (6 months after operation), despite his asymptomatic status, the effort test revealed antero-lateral myocardial ischemia. A coronary angiography showed a 90% proximal stenosis of the graft at 1.5 cm from the aortic anastomosis. The patient was reoperated on and the circular graft was reconstructed. Despite the severe stenosis this technique of myocardial revascularization has developed intercoronary anastomoses, improving the cardiac contractility and avoiding further clinical complications.

Carotid endarterectomy under hypothermic extracorporeal circulation: a method of brain protection for special patients.

This study was undertaken to evaluate the efficacy of hypothermic extracorporeal circulation for cerebral protection in 17 patients having simultaneous carotid endarterectomy and cardiac operations. The cardiopulmonary by-pass (CPB) was conducted using total hemodilution. The body temperature was cooled to 25 degrees C and the heart was arrested with cardioplegic solution. The carotid endarterectomy was performed first followed by the cardiac operation. No neurological or cardiac complications occurred. These results support the reliability of hypothermic cardiopulmonary bypass as a method of providing cerebral protection during simultaneous cardiac and carotid surgical procedures.

New perspectives for the treatment of thoracic aortic aneurysm with self-expanding endoprostheses. Preliminary experience.

We present our preliminary experience with the application of covered aortic stents to treat aneurysms and dissections of the thoracic artery, a technique that was developed in 1996. Seven selected patients were treated with World Medical Talent bare spring tip endoprostheses and followed up for a total of 67 months. All prostheses were implanted at the Parma General Hospital Cardiovascular Department. Seven patients, average age 57.8 years, range 44-73 years, were treated; a total of 11 prosthetic segments were implanted. Aortic pathologies included: 2 isthmic atherosclerotic aneurysms, 2 chronic dissections, 1 acute dissection, 1 thoracic aneurysm associated with an aneurysm of the abdominal aorta below the renal arteries. Dilation diameters ranged from 6-9 cm, lengths from 4-12 cm. All patients underwent computerized tomography and angiography before stent implantation. The procedure was carried out in an operating room with the patient under general anesthesia and in controlled hypotension. In 2 cases the common iliac artery, prepared for the extraperitoneal route by application of a No. 10 Dacron introducer sheath, was used as the insertion site; in 4 cases the common femoral artery was used, in the case of the double aneurysm the traditional surgical route was used to correct the abdominal aneurysm, and the thoracic aneurysm was repaired through the abdominal prosthesis. All patients were released in good condition; thrombosis of the aneurysm surrounding the graft was immediate in all cases except one which required the application of a second segment shortly after the initial procedure. There were no major complications; one case of iatrogenic dissection of the femoral artery used as the access site required a prosthetic bypass. No implant-related complications were observed during follow-up. Our initial experience has been favorable and demonstrates that stents can be utilized for aortic pathologies of varying etiologies; we had no mortality or major complications, and hospital stays were short. Long term results must be confirmed before the therapeutic potential of this technique can be fully evaluated.

Prevention of deep venous thrombosis by a new low molecular weight heparin (Fluxum) in cardiac surgery.

The prophylactic deep venous antithrombotic efficacy of a low molecular weight heparin (LMWH) was compared with traditional unfractionated calcium heparin in 39 patients submitted to cardiac surgery. The patients were allocated at random to receive either LMWH-Fluxum 3200 IUaXa daily (Group A: 20 patients) or calcium heparin 5000 IU three times daily (Group B: 19 patients). Both treatments were started on the first day after surgery and continued over the fourth postoperative days. One or more risk factors for deep venous thrombosis in addition to the cardiac pathology were present in all the patients of group A and in 13 (72.2%) of group B. Mean times of surgery, blood loss during the perioperative period and number of blood units transfused in both groups were not statistically significant. The deep venous system was investigated by continuous wave Doppler and real time colour Echotomography. No evidence of thrombosis was detected in the two groups. Side effects and subcutaneous hematomas were present in only four patients of group B. Both drugs showed good tolerance, provoking no variations of the main laboratory parameters. We conclude that Fluxum (LMWH) for the efficacy and convenience given by a single daily dose, could represent an alternative choice in the prevention of deep venous thrombosis in cardiac surgery.

[Thallium-201 myocardial perfusion imaging after aortocoronary bypass in patients treated with sulodexide or ASA-dipyridamole]. / Analisi con tallio-201 del quadro perfusionale miocardico dopo bypass aortocoronarico in pazienti trattati con sulodexide ed in pazienti trattati con ASA-dipiridamolo.

The aim of this investigation was to compare the preventive effect of sulodexide, a glycosaminoglycan drug, tested versus ASA-dipyridamole association, on the occlusion of venous aortocoronary bypass. A group A of 23 patients, for a total of 22 anastomosis with internal mammary artery and 46 venous bypass, was treated with sulodexide 500 USL/day. A group B of 18 patients for a total of 19 anastomosis with internal mammary artery and 33 venous bypass, was treated with ASA-dipyridamole 300 mg + 400 mg/day. Three and 9 months after surgery, all patients underwent thallium-201 myocardial perfusion imaging, associated with ergometric test. At the first control after 3 months, reversible perfusion defect in one or more myocardial segments was observed in 8 patients of group A and 3 patients of group B (2 A patients and 1 B patient in non revascularized myocardial segments); after 9 months, reversible perfusion defects were observed in 4 A patients and in 4 B patients. After 3 months, non reversible perfusion defect imaging in non infarcted myocardial segments was observed in 2 A patients and in 1 B patient; after 9 months, in 1 patient of both groups. This research shows higher incidence, at first control after 3 months, of ischemic reversible perfusion defects in patients treated with sulodexide, with an evident improvement in some patients recontrolled after 9 months. At the last control after 9 months, the scintigraphic findings showed similar evidence of perfusion defects in both groups treated with sulodexide or ASA-dipyridamole, with concordant angiographic findings (78.6%). Our preliminary results are encouraging and suggest further widespread studies on sulodexide therapy.

[Surgical therapy of post-infarct aneurysm of the left ventricle. Immediate and long-term results]. / Terapia chirurgica dell'aneurisma post-infartuale del ventricolo sinistro. Risultati immediati ed a distanza.

Between January 1982 and December 1986, 62 patients (59 male and 3 female) ranging in age from 37 to 69 years (mean 53) underwent resection of postinfarction left ventricular aneurysm. The indication for operation was angina in 23 cases (37%), congestive heart failure (CHF) in 7 (11.2%), angina and CHF in 29 (46.8%), rupture in 1; 2 patients were low symptomatic. Ventricular arrhythmias were present in 6 (9.7%) cases and previous systemic embolism in 4 (6.4%). Forty-seven (75.8%) patients had lesions of three coronary arteries with involvement of left main coronary artery in 4 cases; 10 (16.1%) had lesions of two vessels [left anterior descending (LAD) and/or right coronary artery]; 4 (6.4%) had only LAD artery involvement, and 1 had no significant coronary artery stenoses. Left ventricular ejection fraction (EF) was less than 0.30 in 22% of cases, between 0.30 and 0.40 in 25.4% and greater than 0.40 in 50%. The location of the aneurysm was anterolateral or apical (83.8%), posterior (14.5%) and lateral (1.6%). Left ventricular aneurysmectomy with myocardial revascularization was performed in 61 patients (bypass/patient = 2.7), with ventricular septoplasty in 20 and concomitant mitral valve replacement in 3 patients. LAD was grafted in 59.6% of anterior aneurysm. Operative mortality (30 days) was 4.8%, the late mortality, with a follow-up between 12 and 72 months (mean 38), was 6.7% and the actuarial 5 year survival rate was 85% (91% without operative mortality). In our experience, despite no evidence of any operative risk factors, no improvement was noted in radionuclide left ventricular ejection fraction in patients undergoing aneurysmectomy with ventricular septoplasty.(ABSTRACT TRUNCATED AT 250 WORDS)

Practical Schemes for Accurate Forces in Quantum Monte Carlo.

While the computation of interatomic forces has become a well-established practice within variational Monte Carlo (VMC), the use of the more accurate Fixed-Node Diffusion Monte Carlo (DMC) method is still largely limited to the computation of total energies on structures obtained at a lower level of theory. Algorithms to compute exact DMC forces have been proposed in the past, and one such scheme is also put forward in this work, but remain rather impractical due to their high computational cost. As a practical route to DMC forces, we therefore revisit here an approximate method, originally developed in the context of correlated sampling and named here the Variational Drift-Diffusion (VD) approach. We thoroughly investigate its accuracy by checking the consistency between the approximate VD force and the derivative of the DMC potential energy surface for the SiH and C2 molecules and employ a wide range of wave functions optimized in VMC to assess its robustness against the choice of trial function. We find that, for all but the poorest wave function, the discrepancy between force and energy is very small over all interatomic distances, affecting the equilibrium bond length obtained with the VD forces by less than 0.004 au. Furthermore, when the VMC forces are approximate due to the use of a partially optimized wave function, the DMC forces have smaller errors and always lead to an equilibrium distance in better agreement with the experimental value. We also show that the cost of computing the VD forces is only slightly larger than the cost of calculating the DMC energy. Therefore, the VD approximation represents a robust and efficient approach to compute accurate DMC forces, superior to the VMC counterparts.

[Congenital arteriovenous fistula between the subclavian artery and vein. (Discussion of a surgically treated case) (author's transl)]. / Fistola artero-venosa congenita tra l'arteria e la vena succlavia (discussione di un caso trattato chirurgicamente).

The Authors report a case of a congenital arteriovenous fistula between the subclavian artery and vein in a 42 years-old woman. The clinical examinations are discussed for the exact classification and the topographic localisation. The surgical treatment (extirpation of the fistula) is necessary especially because arteriovenous fistulas have a tendency to progress, which may lead to severe cardiac insufficiency, aneurismatic dilatations and risks of endocarditis.

[Digital angiography and surgery of the carotid: our experience]. / Angiografia digitale e chirurgia delle carotidi: la nostra esperienza.

Digital subtraction angiography (DSA) has became a common diagnostic procedure in the investigation of patients with cerebrovascular disorders. In these report is described a series of 80 cases previously examined in 8 different department of radiology, 59 with IV.DSA and 21 with IA.DSA. Thirty per cent of IV.DSA images were judged to be technically inadequate, so that further evaluations with conventional angiography have been needed, and in 3 patients (5.0%) the IV.DSA diagnosis was overturned. The authors recommend intraarterial digital subtraction angiography for evaluation of extracranial carotid occlusive disease always resulted the definitive diagnostic procedure in their experience.

[Our experience in the surgery of thoracic aorta]. / La nostra esperienza nella chirurgia dell'aorta toracica.

Particular interest was given to 61 cases of aneurysm and all possible risks and failures of the surgical procedures were discussed. The importance of how diagnostic, technical and instrumental investigations greatly improved therapy was emphasized. The largest group of patients investigated statistically was composed of patients suffering from acute aortic dissection. Emphasis was put on how modern diagnostic technology resulted in a faster and safe procedure, keeping in mind, however, that many severe cases were still unsuccessful. With regard to traumatic lesions of the aorta, typical of young patients, the importance of a complete clinical and surgical approach was stressed in order to treat the visceral and scheletral lesions that are often present.