Experimental Observations of Laser-Driven Tin Ejecta Microjet Interactions.

The study of high-velocity particle-laden flow interactions is of importance for the understanding of a wide range of natural phenomena, ranging from planetary formation to cloud interactions. Experimental observations of particle dynamics are sparse given the difficulty of generating high-velocity flows of many particles. Ejecta microjets are micron-scale jets formed by strong shocks interacting with imprinted surfaces to generate particle plumes traveling at several kilometers per second. As such, the interaction of two ejecta microjets provides a novel experimental methodology to study interacting particle streams. In this Letter, we report the first time sequences of x-ray radiography images of two interacting tin ejecta microjets taken on a platform designed for the OMEGA Extended Performance (OMEGA EP) laser. We observe that the microjets pass through each other unattenuated for the case of 11.7±3.2 GPa shock pressures and jet velocities of 2.2±0.5 km/s but show strong interaction dynamics for 116.0±6.1 GPa shock pressures and jet velocities of 6.5±0.5 km/s. We find that radiation-hydrodynamic simulations of the experiments are able to capture many aspects of the collisional behavior, such as the attenuation of jet velocity in the direction of propagation, but are unable to match the full spread of the strongly interacting cloud.

[Metabolic syndrome among people with HIV in central Tunisia: Prevalence and associated factors]. / Le syndrome métabolique chez les personnes vivant avec le VIH dans le centre tunisien : prévalence et facteurs associés.

INTRODUCTION: Metabolic abnormalities are frequently reported in HIV infection. They were mainly related to the chronic infection and the use of antiretroviral therapy. OBJECTIVE: Describe the epidemiological, clinical, laboratory and treatment features of people living with HIV (PLHIV) on antiretroviral therapy and determine the prevalence of metabolic syndrome and its associated factors. MATERIALS AND METHODS: We conducted a cross-sectional, descriptive and analytical study in the service of Infectious Diseases of the University Hospital of Monastir. We included all PLHIV on antiretroviral therapy for at least 3 months. Biological explorations based on metabolic parameters were performed systematically for all patients after informed consent. Metabolic syndrome was assessed according to the definitions of the International Diabetes Federation (IDF) in 2005. We divided the patients into two groups: Group A: PLHIV with metabolic syndrome (n=19) and Group B: PLHIV without metabolic syndrome (n=51). RESULTS: We included in this study 70 PLVIH. The metabolic syndrome was noted in 19 cases (27.1%). The average age was 43.7 years in group A and 36.7 years in group B. Gender distribution were uniform in the two groups (P=0.4). HIV infection has been evolving for 9.7 and 5.8 years respectively in group A and B, P=0.017. Body mass index (BMI) was significantly higher in group A (26.4 vs 23.5kg/m2, P=0.008). Two patients in group A (10.5%) and 14 patients in group B (27.4%) had a low CD4 count (<200/mm3). Protease inhibitor regimens were prescribed in five cases (26.3%) in group A and 26 cases (50.9%) in group B. In multivariate models, Age over 40 (OR=9.9, 95% CI 2.4-40.6, P=0.001) and BMI ≥25 Kg/m2 (OR=8.47, 95% CI 1.94-36.8, p=0.004) were both independently associated with the presence of the metabolic syndrome. CONCLUSION: Metabolic syndrome is common among PLHIV on antiretroviral therapy. The identification of factors associated is a main parameter for early detection of metabolic risk and personalized management.

A VERSATILE SHARP INTERFACE IMMERSED BOUNDARY METHOD FOR INCOMPRESSIBLE FLOWS WITH COMPLEX BOUNDARIES.

A sharp interface immersed boundary method for simulating incompressible viscous flow past three-dimensional immersed bodies is described. The method employs a multi-dimensional ghost-cell methodology to satisfy the boundary conditions on the immersed boundary and the method is designed to handle highly complex three-dimensional, stationary, moving and/or deforming bodies. The complex immersed surfaces are represented by grids consisting of unstructured triangular elements; while the flow is computed on non-uniform Cartesian grids. The paper describes the salient features of the methodology with special emphasis on the immersed boundary treatment for stationary and moving boundaries. Simulations of a number of canonical two- and three-dimensional flows are used to verify the accuracy and fidelity of the solver over a range of Reynolds numbers. Flow past suddenly accelerated bodies are used to validate the solver for moving boundary problems. Finally two cases inspired from biology with highly complex three-dimensional bodies are simulated in order to demonstrate the versatility of the method.

Fluorodeoxyglucose positron emission tomography and somatostatin receptor scintigraphy for diagnosing and staging carcinoid tumours: correlations with the pathological indexes p53 and Ki-67.

We performed this study in order to evaluate the diagnostic accuracy of whole-body fluorodeoxyglucose positron emission tomography (FDG PET) imaging and somatostatin receptor scintigraphy (SRS) for localizing primary carcinoid tumours and evaluating the extent of the disease. A secondary aim was to correlate those findings with the histological characteristics of the lesions. FDG PET was performed in 17 patients and SRS in 16. All patients had pathologically proven carcinoids. All lesions were verified by histopathological analysis or by follow-up. Ki-67 and p53 expression were assessed as an indicator of the tumours' aggressiveness. FDG PET correctly identified 4/7 primary tumours and 8/11 metastatic spreads, as compared to six and 10 respectively, for SRS. Most tumours were typical carcinoids with low Ki-67 expression. No correlation was found between the histological features and the tracer's uptake. We conclude that SRS remains the modality of choice for evaluating patients with carcinoid tumours, regardless of their proliferative activity. FDG PET should be reserved to patients with negative results on SRS.

Positron emission tomography (PET) for staging low-grade non-Hodgkin's lymphomas (NHL).

Although positron emission tomography (PET) imaging is now recognized as a useful tool for staging intermediate and high-grade non-Hodgkin's lymphoma (NHL), few data are available regarding its accuracy in low grade NHL. We therefore studied 36 patients with histologically proven low-grade NHL. Whole-body 2-(fluorine-18) fluoro-2-deoxy-D-glucose (FDG) PET was performed at the time of initial diagnosis (n = 21) or for disease recurrence (n = 15) prior to any treatment. PET results were compared to those of physical examination and computed tomography (CT). PET studies were read without knowledge of any clinical data. Any focus of increased activity was described and given a probability of malignancy using a 5 point-scale (0: normal to 4: definitively malignant). An individual biopsy was available for a total of 31 lesions. The sensitivity and specificity were 87% and 100% for FDG-PET, 100% and 100% for physical examination and 90% and 100% for CT respectively. In addition, 42 of 97 peripheral lymph node lesions observed by FDG-PET were clinically undetected, whereas the physical examination detected 23 additional nodal lesions. PET and CT both indicated 12 extranodal lymphomatous localizations. FDG-PET showed 7 additional extranodal lesions while 5 additional unconfirmed lesions were observed on CT. Regarding bone marrow infiltration, PET and biopsy were concordant in 24 patients with 11 true positive (TP) and 13 true negative (TN). However PET was FN in 11 patients and no biopsy was performed in one patient. The combination PET/CT/physical examination seems to be more sensitive than the conventional approach for staging low grade NHL. Its sensitivity however is unacceptably low for diagnosing bone marrow infiltration.

Positron emission tomography (PET) with 18F-fluorodeoxyglucose (18F-FDG) for the staging of low-grade non-Hodgkin's lymphoma (NHL).

BACKGROUND: Although PET has been shown to be highly sensitive in the primary staging of lymphoma, previous studies with small numbers of patients indicated that low-grade NHL may not always be adequately detected by PET. We undertook this study to determine factors influencing the detection of lesions by PET in low-grade NHL and to evaluate the utility of PET in this indication. PATIENTS AND METHODS: Forty-two patients underwent conventional staging procedures (clinical examination, oto-rhino-laryngologic examination, computed tomography of the chest, abdomen and pelvis, gastroscopy and bone marrow biopsy as well as whole-body non-attenuation corrected 18F-FDG-PET RESULTS: PET detected 40% more abnormal lymph node areas than conventional staging in follicular lymphoma but was inappropriate for the staging of small lymphocytic lymphoma where it detected less than 58% of abnormal lymph node areas. PET showed more lesions than conventional staging for peripheral (34% more lymph node areas detected) and thoracic lymph node (39% more) areas but not for abdominal or pelvic lymph nodes (26% fewer areas detected). The sensitivity to detect bone marrow infiltration was unacceptably low for PET. In contrast, PET was as effective as standard procedures for the detection of other extranodal localizations, although a few localizations were detected only by PET and a few others only by conventional procedures. CONCLUSIONS: PET may contribute to the management of patients with low-grade follicular NHL. For the other low-grade lymphoma subtypes, the role of PET is less evident. Further studies using PET to evaluate the results of treatment or to diagnose disease recurrence are warranted in low-grade follicular NHL.

Whole-body positron emission tomography using 18F-fluorodeoxyglucose compared to standard procedures for staging patients with Hodgkin's disease.

BACKGROUND AND OBJECTIVES: Accurate staging is essential in order to determine appropriate treatment in Hodgkin's disease (HD). (18)F-fluorodeoxyglucose positron emission tomography ((18)F-FDG PET) offers the advantage of metabolic imaging that is largely independent of morphologic criteria. In the present study we evaluated the role of (18)F-FDG PET compared to routine procedures for the staging of patients with HD. DESIGN AND METHODS: Thirty-three patients with HD underwent standard staging procedures (clinical examination, laboratory screening, chest X-ray, computed tomography (CT) of the chest and abdomen and bilateral bone marrow biopsies) and a whole-body (18)F-FDG PET study. In clinical examination, an isolated lymph node > 1 cm or multiple lymph nodes > or = 1 cm in size were considered abnormal. Positive findings at both clinical examination or CT and (18)F-FDG PET were regarded as actual locations of disease. Negative findings with both methods were regarded as true negative (no involvement by HD). In cases of discrepancy, response to treatment and follow-up data were used to assess the overall accuracy of the patient's original evaluation. RESULTS: Completely concordant results in lymph node staging were observed in 20 patients. The two staging procedures indicated complementary information in 1 patient. Conventional staging indicated more pathologic lymph node areas in 6 patients (at least 1 false positive). (18)F-FDG PET showed more sites in 6 patients. The sensitivity of (18)F-FDG PET in detecting all known pathologic lymph nodes was 83% for peripheral lymph nodes, 91% for thoracic lymph nodes and 75% for abdominal and pelvic lymph nodes. Conventional staging procedures and (18)F-FDG PET indicated the same tumor stage in 26 patients. Based on (18)F-FDG PET, downstaging was suggested in 4 patients, including a biopsy-proven case. However in 1 of these cases this was incorrect. (18)F-FDG PET suggested upstaging in 3 patients. Based on conventional staging or (18)F-FDG PET the same treatment strategy was defined in 32 patients. In one patient (18)F-FDG PET downstaged disease extension (stage IIIA-->IIA) that would have suggested radiotherapy as a possible treatment option. INTERPRETATION AND CONCLUSIONS: (18)F-FDG PET provides an easy and efficient whole-body method for the evaluation of patients with HD. (18)F-FDG PET never missed tumor masses >1 cm. (18)F-FDG PET detected additional sites of disease not seen by conventional procedures and identified absence of disease in some sites suspected to be involved. However, in our patients this did not translate into changes in treatment strategy.

Persistent tumor 18F-FDG uptake after a few cycles of polychemotherapy is predictive of treatment failure in non-Hodgkin's lymphoma.

BACKGROUND AND OBJECTIVE: Early recognition of the ineffectiveness of chemotherapy could result in lower cumulative drug toxicity and tumor burden at the start of salvage therapy, which might improve clinical outcome. Therefore, we studied the value of (18)F-FDG PET for early evaluation of response in patients with non-Hodgkin's lymphoma (NHL). DESIGN AND METHODS: We studied 28 patients by (18)F-FDG PET after a median of 3 cycles of polychemotherapy. The presence or absence of abnormal (18)F-FDG uptake was correlated to clinical outcome (median follow-up: 17.5 months, range 4-47 months). RESULTS: Five of 28 patients still had increased (18)F-FDG uptake in one or more sites previously shown to be involved by lymphoma at baseline evaluation. Only one of these five patients entered complete remission (CR), whereas among the 23 patients with negative (18)F-FDG PET studies, two died of toxicity during chemotherapy and all the others entered clinical CR (p<0.00001). All five patients with and 7/21 patients without residual abnormal (18)F-FDG uptake relapsed or reprogressed (positive predictive value for relapse: 100%, negative predictive value: 67%). By Kaplan-Meier analysis, progression-free survival (PFS) at 1 and 2 years was respectively 20+/-18% and 0% for (18)F-FDG PET positive patients and 81+/-9% and 62+/-12% for (18)F-FDG PET negative patients (p=0.0001). Overall survival (OS) at 1 and 2 years was respectively 20+/-18% and 0% for (18)F-FDG PET positive and 87+/-7% and 68+/-11% for (18)F-FDG PET negative patients (p<0.0001). INTERPRETATION AND CONCLUSIONS: Persistent tumoral (18)F-FDG uptake after a few cycles of polychemotherapy is predictive of CR, PFS and OS in NHL. Further studies are warranted to determine whether (18)F-FDG PET has a predictive value independent from conventional prognostic factors. However, the sensitivity of qualitative (18)F-FDG PET imaging in identifying patients with a poor outcome was insufficient. Earlier evaluation after only one cycle of chemotherapy and quantitative analysis might increase the sensitivity of 18F-FDG PET is predicting treatment failure.

An appraisal of 18-fluorodeoxyglucose positron emission tomography for melanoma staging.

BACKGROUND: Positron emission tomography (PET scan) using fluorodeoxyglucose (FDG) is increasingly recognized as a reliable diagnostic method to detect metastases of malignant melanoma (MM). OBJECTIVE: To compare the diagnostic performance of 18-FDG PET scan to that of conventional imaging. METHODS: A total of 28 assessments were conducted in 24 patients at risk of metastatic MM. RESULTS: The diagnostic accuracy was over 80% and similar for PET scan and conventional imaging. CONCLUSION: Both the specificity and sensitivity of PET scan are high although not perfect. Confrontation of data with anatomical location and clinicopathological findings remains mandatory.

Whole-body positron emission tomography using 18F-fluorodeoxyglucose for posttreatment evaluation in Hodgkin's disease and non-Hodgkin's lymphoma has higher diagnostic and prognostic value than classical computed tomography scan imaging.

A residual mass after treatment of lymphoma is a clinical challenge, because it may represent vital tumor as well as tissue fibrosis. Metabolic imaging by 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET) offers the advantage of functional tissue characterization that is largely independent of morphologic criteria. We compared 18F-FDG PET to computed tomography (CT) in the posttreatment evaluation of 54 patients with Hodgkin's disease (HD) or intermediate/high-grade non-Hodgkin's lymphoma (NHL). Residual masses on CT were observed in 13 of 19 patients with HD and 11 of 35 patients with NHL. Five of 24 patients with residual masses on CT versus 1 of 30 patients without residual masses presented a positive 18F-FDG PET study. Relapse occurred in all 6 patients (100%) with a positive 18F-FDG PET, 5 of 19 patients (26%) with residual masses on CT but negative 18F-FDG PET, and 3 of 29 patients (10%) with negative CT scan and 18F-FDG PET studies (P

Whole-body 18F-FDG PET for the evaluation of patients with Hodgkin's disease and non-Hodgkin's lymphoma.

Whole-body metabolic information provided by 18F-FDG PET could help in the evaluation of lymphoma patients at diagnosis and follow-up. We studied 60 patients, 42 at initial presentation and 18 for disease recurrence (23 aggressive non-Hodgkin's lymphoma, 21 low-grade non-Hodgkin's lymphoma and 16 Hodgkin's disease). All patients underwent a clinical examination, computed tomography (CT) and a non-attenuated PET scan within 1 week. The patients received 222-296 MBq (6-8 mCi) 18F-FDG intravenously and emission scans were recorded 45-90 min later. 18F-FDG PET detected more lymph nodes than the clinical examination or CT, but this rarely resulted in upstaging (two patients). The concordance between PET and CT for the evaluation of the spleen, liver and digestive tract was quite good. Discordance was noted in 12 patients for the evaluation of bone marrow infiltration, but confirmation by MRI or focal biopsy was not always obtained. We conclude that non-attenuated 18F-FDG PET is an easy and efficient whole-body method for the evaluation of patients with lymphomas. Compared with conventional techniques, however, it does not appear to offer much improvement for staging but provides a satisfactory base for follow-up.

ECT in the presence of intracranial aneurysm.

Two patients with known intracranial aneurysms (ICA) received electroconvulsive therapy (ECT). The first patient received ECT 4 years after the clipping of a right middle cerebral artery aneurysm. Treatment with esmolol failed to completely prevent an increase in blood pressure, but she did well nonetheless. The second patient underwent clipping of a basilar artery aneurysm 11 years before ECT. At the time of ECT, angiography showed a right paraophthalmic artery aneurysm. He received esmolol before each ECT, and, like the first patient, still had significant peri-ictal increases in his blood pressure, but otherwise tolerated the procedure well. Our experience and previously published literature indicate that even with pretreatment, patients often sustain significant increases in their blood pressure. However, this has not been accompanied by any morbidity. Possible guidelines for the management of ICA in association with ECT are discussed.

Can pulse oximetry and end-tidal capnography reflect arterial oxygenation and carbon dioxide elimination during laparoscopic cholecystectomy?

An investigation was carried out on 13 ASA class 1 or 2 adult patients undergoing laparoscopic cholecystectomy. Throughout laparoscopy, the end-tidal PCO2 was continuously monitored by capnography and the arterial hemoglobin oxygen saturation by pulse oximetry. Also, repeated measurements of arterial blood gases were done. Ventilation was controlled using an inspired oxygen concentration of 33% and tidal volume of 10 to 15 ml/kg at a rate of 10-14/min. The report showed that both the mean end-tidal PCO2 and arterial PCO2 progressively increased following carbon dioxide insufflation, to reach a maximal value after 30 min, with no significant change in the arterial-alveolar PCO2 gradient. Also, the arterial PO2 significantly decreased, and the hemoglobin oxygen saturation was always above 98% whether monitored by arterial blood gas analysis or by pulse oximetry. The results suggest that end-tidal capnography and pulse oximetry can be used as noninvasive techniques for monitoring arterial oxygenation and carbon dioxide elimination during laparoscopic cholecystectomy.

End-tidal carbon dioxide tension during laparoscopic cholecystectomy. Correlation with the baseline value prior to carbon dioxide insufflation.

An investigation of end-tidal carbon dioxide tension changes was carried out in 19 healthy adult patients undergoing laparoscopic cholecystectomy. Following induction of anaesthesia, and throughout surgery, the end-tidal carbon dioxide tension was continuously monitored by capnography. The value following carbon dioxide insufflation increased with time to reach a maximum value after 40 min. Correlation of the individual maximum end-tidal carbon dioxide tension during laparoscopy with the corresponding baseline value prior to carbon dioxide insufflation showed a positive linear relationship (correlation coefficient 0.86). The correlation showed that an end-tidal carbon dioxide tension of 5.32 kPa (40 mmHg) can be achieved during laparoscopy when the baseline value is adjusted to around 4.0 kPa (30 mmHg).

Trauma management in a war zone: the Lebanese war experience.

Lessons learned from the Vietnam and Korean conflicts have emphasized the necessity of an organized preparedness for optimal management of casualties. The present report summarizes the experience of a tertiary care center in the present Lebanese war. Between 1975 and 1986, approximately 30,000 war casualties were treated at the American University of Beirut Medical Center (AUBMC). A disaster plan was implemented whenever more than 25 major trauma victims were received within 1 hour. In-field stabilization and emergency room (ER) thoracotomy were not employed. The results are illustrated by an analysis of 1,500 cases of abdominal trauma, (1,314 high-velocity gunshot wounds, 29 stab wounds, 157 blunt injuries). A total of 1,420 patients were operated on within 6 hours of admission and 711 within the first hour. Overall mortality was 130, 8.7%; 9.5% for gunshot wounds, 3.4% for stab wounds, and 2.5% for blunt trauma. One hundred forty-five patients or 9.7% had negative findings at laparotomy. The factors affecting mortality were hypotension on admission (26.5% for a BP less than 90 mm Hg and 2.8% for a BP higher than 90 mm Hg) and the presence of extra-abdominal injuries (14.4% with and 4.4% without). The chief causes of death were hemorrhage (3.7%), sepsis (2.1%), and ARDS (1.2%).

Thrombosed Björk-Shiley standard disc mitral valve prosthesis.

Between April 1980 and June 1986, 274 patients underwent mitral valve replacement (MVR) with the Björk-Shiley (BS) standard disc mitral valve prosthesis at the American University of Beirut Medical Center (AUBMC). Eleven patients (3.9%) presented 6-41 months after surgery with prosthetic valve dysfunction due to thrombosis. Inadequate control of anticoagulation was the major factor predisposing to thrombosis in all except one. All patients had documented rheumatic valvular disease. Nine patients were operated on an emergency basis and two died before any surgical intervention was possible. Thrombectomy was performed on six patients with four survivors and MVR in three with two survivors. Two patients died intraoperatively (22%). Three pregnant patients underwent mechanical declotting; pregnancy was terminated by abortion in 2 and by caesarean section and live birth in one. We conclude that implantation of the BS mitral valve prosthesis mandates emphasis on anticoagulation and the difficulty encountered with continuous anticoagulant therapy in pregnancy.

Wandering intravascular missiles: report of five cases from the Lebanon war.

From 1980 to 1986, during the Lebanon war, five patients with missile embolization were seen at the American University of Beirut Medical Center. Three had entry in the heart or thoracic aorta with peripheral embolization, and two had entry in the internal carotid artery and inferior vena cava with embolization to the middle cerebral artery and heart, respectively. Embolization was suspected when, in the absence of an exit, routine x-ray films showed the missile in a distant location. Angiography and echocardiography confirmed the diagnosis. Peripheral arterial emboli were extracted while cerebral and venous emboli were kept, as they caused transient symptoms and remained silent.