898 resultados para Experience Sampling Methods
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An approach was developed for the preparation of cryogenic ground spiked filter papers with Cu and Zn for use as synthetic calibrating standards for direct solid microanalysis. Solid sampling graphite furnace atomic absorption spectrometry was used to evaluate the microhomogeneity and to check the applicability of the synthetic calibrating standards for the direct determination of Cu and Zn in vegetable certified reference materials. The found concentrations presented no statistical differences at the 95% confidence level. The homogeneity factors ranged from 2.7 to 4.2 for Cu and from 6.4 to 11.5 for Zn.
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The generalized Gibbs sampler (GGS) is a recently developed Markov chain Monte Carlo (MCMC) technique that enables Gibbs-like sampling of state spaces that lack a convenient representation in terms of a fixed coordinate system. This paper describes a new sampler, called the tree sampler, which uses the GGS to sample from a state space consisting of phylogenetic trees. The tree sampler is useful for a wide range of phylogenetic applications, including Bayesian, maximum likelihood, and maximum parsimony methods. A fast new algorithm to search for a maximum parsimony phylogeny is presented, using the tree sampler in the context of simulated annealing. The mathematics underlying the algorithm is explained and its time complexity is analyzed. The method is tested on two large data sets consisting of 123 sequences and 500 sequences, respectively. The new algorithm is shown to compare very favorably in terms of speed and accuracy to the program DNAPARS from the PHYLIP package.
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Background, Rural experience for dental students can provide valuable clinical education, change attitudes to rural practice, and make a valuable contribution to clinical service provision. The aim of this paper is to assess the costs and benefits of service delivery by students through rural training programmes Methods: Groups of two students worked in the public dental clinics in adjacent rural centres where there had been long-term difficulties in recruiting staff. The costs and benefits of the programme were assessed by the impact on waiting lists, the total cost per patient of, a course of care and by the marginal cost of adding service provision by students to existing arrangements. Results: The total costs of emergency and complete treatment provided by students were greater than the costs of treatment provided by public-sector dentists but less than the costs of private providers treating public patients. However, the value of services were greater when care was provided by students or private providers and the marginal cost of students providing services was 50-70 per cent of the cost of care provided by public dentists. Conclusion: This assessment suggests that the service benefits achieved compliment the primary objective of influencing the attitude of students to rural practice.
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The volatile components of the chin gland secretion of the wild European rabbit, Oryctolagus cuniculus (L.), were investigated with the use of gas chromatography. Studies of the chemical nature of this secretion by previous workers demonstrated that it was important in the maintenance of social structure in this species. This study identified 34 different volatile components that consist primarily of aromatic and aliphatic hydrocarbons. Especially common are a series of alkyl-substituted benzene derivatives that provide most of the compound diversity in the secretion. Samples of chin gland secretion collected from animals at three different geographical locations, separated by more than 100 km, showed significant differences in composition. This work suggests that variation among populations needs to be considered when undertaking semiochemical research. Alternate nonparametric methods are also used for the analysis of chromatographic data.
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Foraging adults of phytophagous insects are attracted by host-plant volatiles and supposedly repelled by volatiles from non-host plants. In behavioural control of pest insects, chemicals derived from non-host plants applied to crops are expected to repel searching adults and thereby reduce egg laying. How experience by searching adults of non-host volatiles affects their subsequent searching and oviposition behaviour has been rarely tested. In laboratory experiments, we examined the effect of experience of a non-host-plant extract on the oviposition behaviour of the diamondback moth (DBM), Plutella xylostella, a specialist herbivore of cruciferous plants. Naive ovipositing DBM females were repelled by an extract of dried leaves of Chrysanthemum morifolium, a non-host plant of DBM, but experienced females were not repelled. Instead they were attracted by host plants treated with the non-host-plant extract and laid a higher proportion of eggs on treated than on untreated host plants. Such behavioural changes induced by experience could lead to host-plant range expansion in phytophagous insects and play an important role in determining outcome for pest management of some behavioural manipulation methods.
Coronary CT angiography using 64 detector rows: methods and design of the multi-centre trial CORE-64
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Multislice computed tomography (MSCT) for the noninvasive detection of coronary artery stenoses is a promising candidate for widespread clinical application because of its non-invasive nature and high sensitivity and negative predictive value as found in several previous studies using 16 to 64 simultaneous detector rows. A multi-centre study of CT coronary angiography using 16 simultaneous detector rows has shown that 16-slice CT is limited by a high number of nondiagnostic cases and a high false-positive rate. A recent meta-analysis indicated a significant interaction between the size of the study sample and the diagnostic odds ratios suggestive of small study bias, highlighting the importance of evaluating MSCT using 64 simultaneous detector rows in a multi-centre approach with a larger sample size. In this manuscript we detail the objectives and methods of the prospective ""CORE-64"" trial (""Coronary Evaluation Using Multidetector Spiral Computed Tomography Angiography using 64 Detectors""). This multi-centre trial was unique in that it assessed the diagnostic performance of 64-slice CT coronary angiography in nine centres worldwide in comparison to conventional coronary angiography. In conclusion, the multi-centre, multi-institutional and multi-continental trial CORE-64 has great potential to ultimately assess the per-patient diagnostic performance of coronary CT angiography using 64 simultaneous detector rows.
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Purpose. Total thyroidectomy (TT) with level VI and VII central neck dissection is the initial treatment for medullary thyroid carcinoma (MTC) without identifiable neck metastasis. Level II to V lateral neck dissection is performed if neck metastasis is present or suspected. We conducted this study to identify the frequency and clinical determinants of skip neck metastasis in MTC. Methods. We reviewed the medical records of 32 patients who underwent TT and bilateral neck dissection for MTC. The clinical features were correlated with pN status in the central versus lateral compartments of the neck. Results. Neck lymph node metastasis (pN+) was found in 20 patients (62.5%) and skip metastases were found in 7 (35%) patients. The sensitivity of the pN status of the central compartment of the neck to predict the pN status of the lateral compartment of the neck was 53.8% and specificity was 63.2%. We found pN+ in 90% of the patients with lymph nodes > 15mm in diameter versus 50% in those with lymph nodes < 1.5mm in diameter. Conclusions. There is skip metastasis in MTC. It is unsafe to use the lymph node status of the central compartment of the neck to define the pN status of the lateral neck. A lymph node greater than 15 mm in diameter is related to pN status.
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Objective: Fast-track rehabilitation is a group of simple measures that reduces morbidity, postoperative complication and accelerates postoperative rehabilitation reducing hospital stay. It can be applied to lung cancer lobectomy. Fast-track rehabilitation cornerstones are: minimally invasive surgical techniques using video-assisted and muscle sparring incisions, normovolemia, normothermia, good oxygenation, euglicemia, no unnecessary antibiotics, epidural patient-controlled analgesia, systemic opiods-free analgesia, early ambulation and oral feeding. Our objective is to describe a five-year experience with fast-track rehabilitation for lung cancer lobectomy. Patients and methods: A retrospective non-controlled study including 109 consecutive patients submitted to fast-track rehabilitation in the postoperative care of lung cancer lobectomy was performed. Only collaborative patients who could receive double-lumen intubation, epidural. catheters with patient-controlled analgesia, who had Karnofsky index of 100, previous normal feeding and ambulation, absence of morbid obesity, diabetes or asthma, were eligible. Postoperative oral feeding and aggressive ambulation started as soon as possible. Results: Immediate postoperative extubation even in the operation room was possible in 107 patients and oral feeding and ambulation were possible before the first hour in 101 patients. Six patients could not receive early oral feeding or ambulate due to hypnosis secondary to preoperative long effect benzodiazepines. Two patients could not ambulate immediately due to epidural catheter misplacement with important postoperative pain. Ninety-nine discharges occurred at the second postoperative day, four of them with a chest tube connected to a Heimlich valve due to air teak. No complication of early feeding and ambulation was observed. Postoperative hypnosis due to long duration benzodiazepines or pain does not allow early oral feeding or ambulation. Avoiding long duration preoperative benzodiazepines, immediate postoperative extubation, regional thoracic PCA and early oral feeding and ambulation were related to a lesser frequency of complication and a shorter hospital stay. Conclusion: Fast-track rehabilitation for lung cancer lobectomies can be safety performed in a selected group of patients if a motivated multidisciplinary group of professionals is available and seems to reduce postoperative complication and hospital stay. (C) 2009 European Association for Cardio-Thoracic Surgery. Published by Elsevier B.V. All rights reserved.
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BACKGROUND: Early gastric cancer (EGC) is defined as adenocarcinoma limited to the mucosa or submucosa regardless of lymph node involvement. Local EGC recurrence rates have been described ill Lip to 6% of cases. OBJECTIVES: To evaluate predictive factors for incomplete resection and local recurrence of EGC treated by endoscopic mucosal resection (EMR) that was followed up for at least one year. METHODS: From June 1994 to December 2005, 46 patients with EGC underwent EMR. Possible predictive factors for incomplete endoscopic resection and local recurrence were identified by medical chart analysis. Demographic, endoscopic and histopathological data were retrospectively evaluated. EMR was considered complete or incomplete. Patients from the complete resection group were divided into subgroups (with and without local EGC recurrence). RESULTS: Complete resection was possible in 36 cases (76.6%). Predictive factors for incomplete resection were turnout location (P=0.035), histological type (P=0.021), lesion size (P=0.022) and number of resected fragments (P=0.013). On multivariate analysis, undifferentiated histological type (OR 0.8; 95% Cl 0.036 to 0.897) and number of resected fragments (OR 7.34; 95% Cl 1.266 to 42.629) were independent predictive factors for incomplete resection. In the complete resection group, a larger lesion size was associated with a higher the number of resected fragments (P=0.018). Local recurrence occurred in nine cases (25%). Use of the cap technique was the only predictive factor for local recurrence in five of seven cases (71.4%) (P=0.006). CONCLUSIONS: A larger lesion size was associated with a higher number of resected fragments. Undifferentiated adenocarcinoma and piecemeal resection were predictive factors for incomplete resection. Technique type was a predictive factor for local EGC recurrence.
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Objective To report the experience with fetal cystoscopy and laser fulguration of posterior urethral values (PUV) for severe lower urinary tract obstruction (LUTO). Methods Between July 2006 and December 2008, fetal cystoscopy was offered to 23 patients whose fetuses presented with severe LUTO. favorable urinary analysis and gestational age <26 weeks. Fetal urinary biochemistry was evaluated before and after cystoscopy. All infants were followed 6-12 months after birth. Abnormal renal function was defined when serum creatinine higher than 50 mu mol/L (2 Standard Deviation) or the necessity of dialysis or renal transplantation. Autopsy was always performed whenever fetal or neonatal deaths occurred. Results Eleven patients decided to undergo fetal therapy and 12 elected to continue with expectant observation. There was no difference between both groups in gestation age at diagnosis and referral examinations. Urethral atresia was diagnosed in 4/11 (36.4%) fetuses by fetal cystoscopy. At 26 weeks, fetuses that were managed expectantly presented with worse urinary biochemistry results (p < 0.05). Survival rates and percentage of infants with normal renal function were significantly higher in the cystoscopic group than in the expectant group (P < 0.05). Conclusions Percutaneous fetal cystoscopy is feasible using a thinner special cannula for prenatal diagnosis and therapy of LUTO. Prenatal laser ablation of the PUV under cystoscopy may prevent renal function deterioration improving postnatal outcome. Copyright (C) 2009 John Wiley & Sons, Ltd.
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Introduction. The use of arterial grafts (AG) in pediatric orthotopic liver transplantation (OLT) is an alternative in cases of poor hepatic arterial inflow, small or anomalous recipient hepatic arteries, and retransplantations (re-OLT) due to hepatic artery thrombosis (HAT). AG have been crucial to the success of the procedure among younger children. Herein we have reported our experience with AG. Methods. We retrospectively reviewed data from June 1989 to June 2010 among OLT in which we used AG, analyzing indications, short-term complications, and long-term outcomes. Results. Among 437 pediatric OLT, 58 children required an AG. A common iliac artery interposition graft was used in 57 cases and a donor carotid artery in 1 case. In 38 children the graft was used primarily, including 94% (36/38) in which it was due to poor hepatic arterial inflow. Ductopenia syndromes (n = 14), biliary atresia (BA; n = 11), and fulminant hepatitis (n = 8) were the main preoperative diagnoses among these children. Their mean weight was 18.4 kg and mean age was 68 months. At the mean follow-up of 27 months, multiple-organ failure and primary graft nonfunction (PNF) were the short-term causes of death in 9 children (26.5%). Among the remaining 29 patients, 2 (6,8%) developed early graft thrombosis requiring re-OLT; 5 (17%) developed biliary complications, and 1 (3.4%) had asymptomatic arterial stenosis. In 20 children, a graft was used during retransplantation. The main indication was HAT (75%). BA (n = 15), ductopenia syndromes (n = 2), and primary sclerosing cholangitis (n = 2) were the main diagnoses. Their mean weight was 16.7 kg and age was 65 months. At a mean follow-up of 53 months, 7 children died due to multiple-organ failure or PNF. Among the remaining 13 patients, 3 developed biliary complications and 1 had arterial stenosis. No thrombosis was observed. Conclusion. The data suggested that use of an AG is useful alternative in pediatric OLT. The technique is safe with a low risk of thrombosis.
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Introduction. Biliary atresia (BA) is the leading indication for orthotopic liver transplantation (OLT) among children. However, there are technical difficulties, including the limited dimensions of anatomical structures, hypoplasia and/or thrombosis of the portal vein and previous portoenterostomy procedures. Objective. The objective of this study was to present our experience of 239 children with BA who underwent OLT between September 1989 and June 2010 compared with OLT performed for other causes. Methods. We performed a retrospective analysis of patient charts and analysis of complications and survival. Results. BA was the most common indication for OLT (207/409; 50.6%). The median age of subjects was 26 months (range, 7-192). Their median weight was 11 kg (range, 5-63) with 110 children (53.1%) weighing <= 10 kg. We performed 126 transplantations from cadaveric donors (60.8%) and 81 from living-related donors (LRD) (39.2%). Retransplantation was required for 31 recipients (14.9%), primarily due to hepatic artery thrombosis (HAT; 64.5%). Other complications included the following: portal vein thrombosis (PVT; 13.0%), biliary stenosis and/or fistula (22.2%), bowel perforation (7.0%), and posttransplantation lymphoproliferative disorder (PTLD; 5.3%). Among the cases of OLT for other causes, the median age of recipients was 81 months (range, 11-17 years), which was higher than that for children with BA. Retransplantation was required in 3.5% of these patients (P < .05), mostly due to HAT. The incidences of PVT, bowel perforation, and PTLD were significantly lower (P < .05). There was no significant difference between biliary complications in the 2 groups. The overall survival rates at 1 versus 5 years were 79.7% versus 68.1% for BA, and 81.2% versus 75.7% for other causes, respectively. Conclusions. Children who undergo OLT for BA are younger than those engrafted for other causes, displaying a higher risk of complications and retransplantations.
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Introduction. Only about 15% of the potential candidates for lung donation are considered suitable for transplantation. A new method for ex vivo lung perfusion (EVLP) can be used to evaluate and recondition ""marginal,"" nonacceptable lungs. We have herein described an initial experience with ex vivo perfusion of 8 donor lungs deemed nonacceptable. Materials and Methods. After harvesting, the lungs were perfused ex vivo with Steen Solution, an extracellular matrix with high colloid osmotic pressure. A membrane oxygenator connected to the circuit received gas from a mixture of nitrogen and carbon dioxide, maintaining a normal mixed venous blood gas level in the perfusate. The lungs were gradually rewarmed, reperfused, and ventilated for evaluation through analyses of oxygenation capacity, pulmonary vascular resistance (PVR), lung compliance (LC), and biopsy. Results. The arterial oxygen pressure (with inspired oxygen fraction of 100%) increased from a mean of 206 mm Hg in the organ donor at the referring hospital to a mean of 498 mm Hg during the ex vivo evaluation. After 1 hour of EVLP, PVR varied from 440-1454 dynes/sec/cm(5); LC was in the range of 26-90 mL/cmH(2)O. There was no histological deterioration after 10 hours of cold ischemia and 1 hour of EVLP. Conclusions. The ex vivo evaluation model can improve oxygenation capacity of ""marginal"" lungs rejected for transplantation. It has great potential to increase lung donor availability and, possibly, reduce time on the waiting list.
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Introduction. Cytomegalovirus (CMV) infection, a common complication in lung transplant (LT) patients, is associated with worse outcomes. Therefore, prophylaxis and surveillance with preemptive treatment is recommended. Objectives. Describe the epidemiology and impact on mortality of CMV infection in LT patients receiving CMV prophylaxis. Methods. Single-center retrospective cohort of LT recipients from August 2003 to March 2008. We excluded patients with survival or follow-up shorter than 30 days. We reviewed medical charts and all CMV pp65 antigen results. Results. Forty-seven patients met the inclusion criteria and 19 (40%) developed a CMV event: eight CMV infections, seven CMV syndromes, and 15 CMV diseases. The mean number of CMV events for each patient was 1.68 +/- 0.88. Twelve patients developed CMV events during prophylaxis (5/12 had CMV serology D+/R-). Forty-six of the 47 patients had at least one episode of acute rejection (mean 2.23 +/- 1.1). Median follow-up was 22 months (range = 3-50). There were seven deaths. Upon univariate analysis, CMV events were related to greater mortality (P = .04), especially if the patient experienced more than two events (P = .013) and if the first event occurred during the first 3 months after LT (P = .003). Nevertheless, a marginally significant relationship between CMV event during the first 3 months after LT and mortality was observed in the multivariate analysis (hazards ratio: 7.46; 95% confidence interval: 0.98-56.63; P = .052). Patients with CMV events more than 3 months post-LT showed the same survival as those who remained CMV-free. Conclusion. Prophylaxis and preemptive treatment are safe and effective; however, the patients who develop CMV events during prophylaxis experience a worse prognosis.
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Background/purpose: The introduction of the piggyback technique for reconstruction of the liver outflow in reduced-size liver transplants for pediatric patients has increased the incidence of hepatic venous outflow block (HVOB). Here, we proposed a new technique for hepatic venous reconstruction in pediatric living-donor liver transplantation. Methods: Three techniques were used: direct anastomosis of the orifice of the donor hepatic veins and the orifice of the recipient hepatic veins (group 1); triangular anastomosis after creating a wide triangular orifice in the recipient inferior vena cava at the confluence of all the hepatic veins (group 2); and a new technique, which is a wide longitudinal anastomosis performed at the anterior wall of the inferior vena cava (group 3). Results: In groups 1 and 2, the incidences of HVOB were 27.7% and 5.7%, respectively. In group 3, no patient presented HVOB (P = .001). No difference was noted between groups 2 and 3. Conclusions: Hepatic venous reconstruction in pediatric living-donor liver transplantation must be preferentially performed by using a wide longitudinal incision at the anterior wall of the recipient inferior vena cava. As an alternative technique, triangulation of the recipient inferior vena cava, including the orifices of the 3 hepatic veins, may be used. Published by Elsevier Inc.