Projeto de Conversor CC-CC Isolado Ressonante Alimentado em Corrente

TCC (graduação) - Universidade Federal de Santa Catarina. Centro Tecnológico. Engenharia Elétrica.Este trabalho é referente a realização de um protótipo de um Conversor CC-CC Isolado Ressonante alimentado em corrente. O qual inclui uma explicação teórica sobre o conversor e suas etapas de operação, realização de métodos de cálculo e projeto, escolha de componentes, realização de simulações e posterior fabricação do conversor. Diversos testes foram realizados para validação da teoria versus prática. Conclui-se que o conversor possui baixas perdas por comutação devido ao ZCS (Comutação por corrente nula) e que por consequência apresenta bom rendimento levando-se em conta que se trata de um conversor isolado

Surgical ampullectomy: an underestimated operation in the era of endoscopy

AbstractIntroductionBenign neoplastic, inflammatory or functional pathologies of the ampulla of Vater are mainly treated by primary endoscopic interventions. Consequently, transduodenal surgical ampullectomy (TSA) has been abandoned in many centres, although it represents an important tool not only after unsuccessful endoscopic treatment. The aim of the study was to analyse TSA for benign lesions of the ampulla of Vater.Patients and methodsAll patients who underwent TSA between 2001 and 2014 were included. Patients were analysed in terms of indications, postoperative morbidity and mortality as well as long-term success.ResultsEighty-three patients underwent TSA. Indications included adenomas in 44 and inflammatory stenosis in 39 patients. 96% of the patients had undergone endoscopic therapeutic approaches prior to TSA (median no. of interventions n = 3). Postoperative morbidity occurred in 20 patients (24%). There was one procedure-associated death (mortality 1.2%). The mean follow-up was 54 months. Long-term overall success rate for TSA was 83.6%. After TSA for ampullary adenoma, the recurrence rate was 4.5%.ConclusionTSA is an underestimated surgical procedure, which can be performed safely with high long-term efficacy. It can be implemented in clinical algorithms for patients with benign pathologies of the ampulla of Vater, particularly after unsuccessful endoscopic treatment

Surgical ampullectomy: an underestimated operation in the era of endoscopy

AbstractIntroductionBenign neoplastic, inflammatory or functional pathologies of the ampulla of Vater are mainly treated by primary endoscopic interventions. Consequently, transduodenal surgical ampullectomy (TSA) has been abandoned in many centres, although it represents an important tool not only after unsuccessful endoscopic treatment. The aim of the study was to analyse TSA for benign lesions of the ampulla of Vater.Patients and methodsAll patients who underwent TSA between 2001 and 2014 were included. Patients were analysed in terms of indications, postoperative morbidity and mortality as well as long-term success.ResultsEighty-three patients underwent TSA. Indications included adenomas in 44 and inflammatory stenosis in 39 patients. 96% of the patients had undergone endoscopic therapeutic approaches prior to TSA (median no. of interventions n = 3). Postoperative morbidity occurred in 20 patients (24%). There was one procedure-associated death (mortality 1.2%). The mean follow-up was 54 months. Long-term overall success rate for TSA was 83.6%. After TSA for ampullary adenoma, the recurrence rate was 4.5%.ConclusionTSA is an underestimated surgical procedure, which can be performed safely with high long-term efficacy. It can be implemented in clinical algorithms for patients with benign pathologies of the ampulla of Vater, particularly after unsuccessful endoscopic treatment

A mathematical model of levodopa medication effect on basal ganglia in parkinson’s disease: An application to the alternate finger tapping task

Malfunctions in the neural circuitry of the basal ganglia (BG), induced by alterations in the dopaminergic system, are responsible for an array of motor disorders and milder cognitive issues in Parkinson's disease (PD). Recently Baston and Ursino (2015a) presented a new neuroscience mathematical model aimed at exploring the role of basal ganglia in action selection. The model is biologically inspired and reproduces the main BG structures and pathways, modeling explicitly both the dopaminergic and the cholinergic system. The present work aims at interfacing this neurocomputational model with a compartmental model of levodopa, to propose a general model of medicated Parkinson's disease. Levodopa effect on the striatum was simulated with a two-compartment model of pharmacokinetics in plasma joined with a motor effect compartment. The latter is characterized by the levodopa removal rate and by a sigmoidal relationship (Hill law) between concentration and effect. The main parameters of this relationship are saturation, steepness, and the half-maximum concentration. The effect of levodopa is then summed to a term representing the endogenous dopamine effect, and is used as an external input for the neurocomputation model; this allows both the temporal aspects of medication and the individual patient characteristics to be simulated. The frequency of alternate tapping is then used as the outcome of the whole model, to simulate effective clinical scores. Pharmacokinetic-pharmacodynamic modeling was preliminary performed on data of six patients with Parkinson's disease (both “stable” and “wearing-off” responders) after levodopa standardized oral dosing over 4 h. Results show that the model is able to reproduce the temporal profiles of levodopa in plasma and the finger tapping frequency in all patients, discriminating between different patterns of levodopa motor response. The more influential parameters are the Hill coefficient, related with the slope of the effect sigmoidal relationship, the drug concentration at half-maximum effect, and the drug removal rate from the effect compartment. The model can be of value to gain a deeper understanding on the pharmacokinetics and pharmacodynamics of the medication, and on the way dopamine is exploited in the neural circuitry of the basal ganglia in patients at different stages of the disease progression

Sex Is the Main Determinant of Levodopa Clinical Pharmacokinetics: Evidence from a Large Series of Levodopa Therapeutic Monitoring

Background: Different studies, mostly with limited cohorts, have suggested the effects of patients' characteristics on levodopa (LD) pharmacokinetics. Objective: We primarily aimed at investigating in a large population the relationship between patients' features and LD kinetic variables, to assess the main demographic and clinical predictors of LD clinical pharmacokinetics. Methods: The study was retrospective, based on data collected from subjects with parkinsonism on chronic LD undergoing LD therapeutic monitoring (TM). LD TM includes serial quantitative motor tests and blood samples to measure plasma drug concentrations after each subject's chronically taken first-morning LD dose intake. Results: Five hundred patients, 308 males (61.6%), mean (SD) age of 65 (10.1) years were included. Parkinsonian symptoms and LD therapy lasted 5.5 (4.5) and 3.4 (3.9) years, respectively. MDS-UPDRS part III "off" score was 28.8 (15.2). LD dose was 348.2 (187.1) mg/day. From multiple linear regression analysis, test dose, sex, type of LD decarboxylase inhibitor, weight and MDS-UPDRS part III score were linear predictors of both LD peak plasma concentration (Cmax) (R2 = 0.52) and area under the 3-h plasma concentration-time curve (AUC) (R2 = 0.71), while age was a further predictor only for AUC. Besides test dose, sex was the strongest independent contributing variable to LD AUC, which resulted 27% higher in females compared to males. Conclusion: This is the largest collection of data on the relationship between demographic and clinical-therapeutic variables and LD kinetics in patients with parkinsonian symptoms. As a main clinically practical finding, women might require a 25% reduced weight-normalized LD dose compared with men to achieve the same LD bioavailability

Closed cannulation of subclavian vein vs open cut-down of cephalic vein for totally implantable venous access port (TIVAP) implantation: protocol for a systematic review and proportional meta-analysis of perioperative and postoperative complications

Background: Totally implantable venous access port (TIVAP) implantation is one of the most often performed operations in general surgery (over 100,000/year in Germany). The two main approaches for TIVAP placement are insertion into the cephalic vein through an open cut-down technique (OCD) or closed cannulation technique of the subclavian vein (CC) with Seldinger technique. Both procedures are performed with high success rates and very low complication frequencies. Because of the low incidence of complications, no single interventional trial is able to report a valid comparison of peri- and postoperative complication frequencies between both techniques. Therefore, the aim of this systematic review is to summarize evidence for peri- and postoperative complication rates in patients undergoing OCD or CC. Methods/Design: A systematic literature search will be conducted in The Cochrane Library, MEDLINE, and Embase to identify randomized controlled trials (RCTs), observational clinical studies (OCS), or case series (CS) reporting peri- and/or postoperative complications of at least one implantation technique. A priori defined data will be extracted from included studies, and methodological quality will be assessed. Event rates with their 95% confidence intervals will be derived taking into account the follow-up time per study by patient-months where appropriate. Pooled estimates of event rates with corresponding 95% confidence intervals will be calculated on the base of the Freeman-Tukey double arcsine transformation within a random effect model framework. Discussion: The findings of this systematic review with proportional meta-analysis will help to identify the procedure with the best benefit/risk ratio for TIVAP implantation. This may have influence on daily practice, and data may be implemented in treatment guidelines. Considering the impact of TIVAP implantation on patients’ well being together with its socioeconomic relevance, patients will benefit from evidence-based treatment and health-care costs may also be reduced. Systematic review registration PROSPERO CRD42013005180

The Bologna motor and non-motor prospective study on parkinsonism at onset (BoProPark): study design and population

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How resistant are levodopa-resistant axial symptoms? Response of freezing, posture and voice to increasing levodopa intestinal infusion rates in Parkinson's disease

Treatment of freezing of gait (FoG) and other Parkinson's disease (PD) axial symptoms is challenging. Systematic assessments of axial symptoms at progressively increasing levodopa doses are lacking. We sought to analyze the resistance to high levodopa doses of FoG, posture, speech, and altered gait features presenting in daily-ON therapeutic condition

The in situ near-total pancreatectomy (LIVOCADO procedure) for end-staged chronic pancreatitis

PURPOSE: Total pancreatectomy for severe pain in end-stage chronic pancreatitis may be the only option, but with vascular involvement, this is usually too high risk and/or technically not feasible. The purpose of the study was to present the clinical outcomes of a novel procedure in severe chronic pancreatitis complicated by uncontrollable pain and vascular involvement. METHODS: We describe an in situ near-total pancreatectomy that avoids peripancreatic vascular dissection (Livocado procedure) and report on surgical and clinical outcomes. RESULTS: The Livocado procedure was carried out on 18 (3.9%) of 465 patients undergoing surgery for chronic pancreatitis. There were 13 men and 5 women with a median (IQR) age of 48.5 (42.4–57) years and weight of 60.7 (58.0–75.0) kg. All had severe pain and vascular involvement; 17 had pancreatic parenchymal calcification; the median (IQR) oral morphine equivalent dose requirement was 86 (33–195) mg/day. The median (IQR) maximal pain scores were 9 (9–10); the average pain score was 6 (IQR 4–7). There was no peri-operative or 90-day mortality. At a median (IQR) follow-up of 32.5 (21–45.75) months, both maximal and average pain scores were significantly improved post-operatively, and at 12 months, two-thirds of patients were completely pain free. Six (33%) patients had employment pre-operatively versus 13 (72%) post-operatively (p = 0.01). CONCLUSIONS: The Livocado procedure was safe and carried out successfully in patients with chronic pancreatitis with vascular involvement where other procedures would be contraindicated. Perioperative outcomes, post-operative pain scores, and employment rehabilitation were comparable with other procedures carried out in patients without vascular involvement

A randomised controlled trial to evaluate and optimize the use of antiplatelet agents in the perioperative management in patients undergoing general and abdominal surgery- the APAP trial (ISRCTN45810007)

<p>Abstract</p> <p>Background</p> <p>Due to the increase of cardiovascular diseases acetylsalicylic acid (ASA) has become one of the most frequently prescribed drugs these days. Despite the rising number of patients with ASA medication presenting for elective general and abdominal surgery and the potentially increased risk of hemorrhage in these patients, there are no clear, evidence-based guidelines for the perioperative use of antiplatelet agents. The present randomised controlled trial was designed to evaluate the safety and optimize the use of ASA in the perioperative management of patients undergoing general and abdominal surgery.</p> <p>Methods/Design</p> <p>This is a two-arm, monocenter randomised controlled trial. Patients scheduled for elective surgical treatment (i.e. inguinal hernia repair, cholecystectomy and colorectal resections) with ASA as a permanent medication are randomised equally to perioperative continuation or discontinuation of ASA. Patients who are randomised in the discontinuation group stop the administration of ASA five days prior to surgical treatment and start intake of ASA on postoperative day 5. Fifty-two patients will be enrolled in this trial. The primary outcome is the incidence of postoperative bleeding and cardiovascular events at 30 days after surgery. In addition a set of general as well as surgical variables are analysed.</p> <p>Discussion</p> <p>This is a randomised controlled two-group parallel trial designed to assess the safety and optimize the use of ASA in the perioperative management of patients undergoing general and abdominal surgery. The results of this pilot study build the basis for a confirmative randomised controlled trial that may help to clarify the use and potential risk/benefits of perioperative ASA medication in patients undergoing elective surgery.</p> <p>Trial registration</p> <p>The trial is registered with Current Controlled Trials <a href="http://www.controlled-trials.com/ISRCTN45810007">ISRCTN45810007</a>.</p