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M P de Miranda

Publications and source records attributed to M P de Miranda.

16 recordsLinked to original sources
PubMed2006

Mechanism and control of the F+H2 reaction at low and ultralow collision energies.

This article uses theoretical methods to study the dependence on stereodynamical factors of the mechanism and reactivity of the F+H2 reaction at low and ultralow collision energies. The impact of polarization of the H2 reactant on total and state-to-state integral and differential cross sections is analyzed. This leads to detailed pictures of the reaction mechanism in the cold and ultracold regimes, accounting, in particular, for distinctions associated with the various product states and scattering angles. The extent to which selection of reactant polarization allows for external control of the reactivity and reaction mechanism is assessed. This reveals that even the simplest of reactant polarization schemes allows for fine, product state-selective control of differential and (for reactions involving more than a single, zero orbital angular momentum partial wave) integral cross sections.

Journal Article↗
PubMed2006

Analysis of the H + D2 reaction mechanism through consideration of the intrinsic reactant polarisation.

The effect of reactant polarisation on the dynamics of the title reaction at collision energies up to 1.6 eV is analysed in depth. The analysis takes advantage of two novel theoretical concepts: intrinsic reaction properties and stereodynamical portraits. Exact quantum methods are used to determine the polarisation moments that quantify the intrinsic reactant polarisation at various levels of detail, including or not product state and/or scattering angle resolution. The data is then examined with the aid of stereodynamical portraits, which facilitate the rationalisation of the stereochemical effects that are relevant for the reaction dynamics. This allows for detailed characterisations of the so-called direct and delayed reaction mechanisms.

Deuterium↗
PubMed1998

Use of a donor aortic cross for arterial reconstruction of the pancreaticoduodenal allograft.

Combined liver-pancreas procurement generally requires back bench reconstruction of the arterial blood supply with a donor Y-iliac graft to the pancreas graft. A modified vascular reconstruction that uses donor aortic cross including the brachiocephalic trunk and the left carotid artery as a single arterial patch is presented. This is useful when iliac grafts are unavailable or are being used as an alternative technique.

Anastomosis, Surgical↗
PubMed1995

Laparoscopic cholecystectomy in cirrhotic patients.

Cholecystectomy in cirrhotic patients is commonly followed by high morbidity and mortality. In our study, laparoscopic cholecystectomy was performed in 12 cirrhotic patients (eight Child A and four Child B) in an effort to obtain lower complication and mortality rates. The mean age of the group was 51.8 years; seven of the 12 patients were men. Four patients had liver disease from virus B, five from virus C, one because of alcohol, and two had cryptogenic liver cirrhosis. The average operative time was 157 min. Intraoperative cholangiography could be performed in eight cases. No mortality or need to perform laparotomy occurred. Only one patient required blood transfusion (8.3%). Postoperative complications occurred in four patients, but these were easily controlled and included renal failure, diabetic impairment, hematoma with ascitic leakage through the wound, and wound abscess, one case each. No postoperative liver failure was observed. All patients walked and were refed in the first 24 h after surgery. They were dismissed in an average period of 2.5 days. Our primary view demonstrated that laparoscopic cholecystectomy was safe and well tolerated by selected cirrhotic patients (Child A and B) with clear indication for surgery.

Cholecystectomy, Laparoscopic↗
PubMed1989

Use of endoscopic Congo red test in the evaluation of ulcer recurrence risks after proximal gastric vagotomy. A new interpretive method.

The endoscopic Congo red test (ECRT) was performed in 43 patients who underwent proximal gastric vagotomy (PGV) for duodenal ulcer (DU). The aim of the study was to develop a standard and reliable way to interpret the results obtained in this test. Thus, the results of ECRT were related to post-operative clinical evaluation and to pre- and post-operative basal and pentagastrin-stimulated gastric acidity. Whenever ECRT was considered positive, we called it in "large extension" if a red-to-black colour change occurred in three or more of the areas studied. Positive ECRT was observed in 39 patients (90.7%). There was a statistically significant (P less than 0.01) correlation between poor clinical results and positive ECRT in "large extension". We concluded that: (1) a positive ECRT result has no clinical or prognostic significance in DU patients after PGV; (2) ECRT, analysed according to the extension of the areas turning black, is a practical and reliable method to establish clinical results and prognosis in these patients.

Adult↗
PubMedDate not supplied

[Immunological parameters in the differential diagnosis of ascites secondary to peritoneal carcinomatosis, hepatic cirrhosis, and congestive heart failure].

As a contribution to the study of ascites in patients with liver cirrhosis, congestive heart failure and peritoneal carcinomatosis evaluate in serum and ascites the concentrations of alphafetoprotein, carcinoembryonic antigen and fibronectin, they might suggest a diagnosis for the basic pathology. Forty-seven patients were studied, from whom 23 with cirrhosis, 17 peritoneal carcinomatosis and 7 with congestive heart failure. We conclude that: a) none of the tools usually employed in the analysis of ascitic fluid alone can make the base pathological process responsible for producing ascites; b) fibronectins were more useful for differential diagnosis between cirrhosis and carcinomatosis; c) alpha-fetoprotein and carcinoembryonic antigen were not useful for the definition for differential diagnosis.

Ascites↗
PubMedDate not supplied

[Hepatic hemangiomas. The importance of the image].

In the authors' experience, 0.24% of the patients submitted to liver imaging (ultrasound or computerized tomography) have hemangiomas. These are shown as solid nodular lesions, mostly found by chance. Sometimes they do not appear as typical solid vascular lesions. The authors' experience and the literature are discussed. A clear and concise approach to this benign neoplasm is suggested.

Adult↗
PubMedDate not supplied

Intestinal anastomoses.

Anastomotic dehiscence remains the main cause of morbidity and mortality of intestinal resections, mainly the colorectal (77, 95, 110). Very often in the literature the words dehiscence and fistula are misused for the same meaning. Nevertheless, attention must be paid to the fact that these two situations may be distinct. Dehiscence is defined as the failure of healing of the anastomoses, while fistula is the leakage of the intestinal content into the peritoneal cavity. So, the evidence of fistula is always accompanied by dehiscence, although a dehiscence may not develop into a fistula, should it be blocked by omentum or surrounding organs (110, 117). The incidence of overt dehiscence varies from 0.1% to 30% in the literature (13, 15, 17, 27, 31, 40, 44, 46, 76, 77, 81, 96, 113, 120, 123, 126, 133, 135). The Colon Cancer Project of the Saint Mary's Hospital in London, a multicentric study of patients submitted to bowel resections revealed a post operative mortality of 22% in patients with dehiscence and 7% for uncomplicated anastomoses. This led to the struggle various authors to achieve better results, regarding techniques and suture materials, such as the number of planes involved, inverted or everted sutures, wound healing and the influence of local and systemic factors, like infections, antibiotics, NSAIDs on sutures. Recently, surgical stapling gained importance among surgeons, due to its technical advantages. However, this is still very controversial and must undergo further investigations (93, 107, 109, 112, 115, 116). So, in order to understand the pathophysiology of the complications and to reduce morbidity and mortality, related to intestinal anastomoses, it is necessary to study the events involved in intestinal healing after resection, as well as the technique, materials used and the factors related to anastomotic failure.

Anastomosis, Surgical↗
PubMedDate not supplied

Prognostic value of preoperative tests in the surgical treatment of ascites with the implant of Le Veen shunts in cirrhotics.

In the period of January 1978 to October 1988, 32 Le Veen shunts (LVS) were implanted in 20 patients, out of which 16 were alcoholic cirrhotics and 4 postnecrotic cirrhotics. In the present study, we correlated preoperative laboratory data of these patients with their postoperative evolution, comparing the clinical results of patients who survived more than 30 days (13 patients = 65%) with the results of those who died within the same period (7 patients = 35%). For that matter, 14 laboratory tests were performed in order to measure the serum levels of hematocrit, hemoglobin, urea, creatinine, sodium, potassium, bilirubin, albumin, AST, ALT, alkaline phosphatase, fibrinogen, gamma GT and prothrombin activity. After statistical analysis, we observed that 6 of the 14 tests performed could be considered of prognostic value in the following decreasing order of importance: fibrinogen, alkaline phosphatase, prothrombin activity, urea, gamma GT and bilirubin. We observed that all the 7 patients who died prematurely presented 3 or more of these levels altered, when compared with standard values. Based on these data, we concluded that serum levels of fibrinogen, alkaline phosphatase, urea, gamma GT, bilirubin and activity of prothrombin proved to be important factors in determining the prognosis of immediate survival in cirrhotic patients who underwent LVS implantation. We also concluded that when 3 or more of these factors are altered, the implant of LVS is contraindicated, whatever clinical criteria for indication and contraindication were taken into account.

Adult↗
PubMedDate not supplied

[Surgical treatment of ascites with Le Veen shunt in patients with alcoholic liver disease].

Studies were carried out on 16 alcoholic cirrhotics with clinically intractable ascites who underwent the implant of peritoneovenous (LeVeen) shunts. Our purpose was to find out how this group of patients responded to this kind of surgical treatment for ascites. Fifteen of these patients were male and one female, with a median age of 51.3 years. According to Child classification, 7 were Child B and 9 Child C. Thirty-three surgeries were conducted, in that 5 were performed for revision of the shunt positioning and 12 for the replacement of the valves. A total of 28 shunts were used. Postoperative immediate mortality occurred in 5 patients (4 Child C and one Child B). The median late postoperative follow-up of the 11 patients who survived was 25.8 months. We concluded that LeVeen shunt implantation is a valid palliative therapeutic resource for the treatment of ascites in alcoholic cirrhotics. The results obtained with this patient population are similar to those observed in cirrhotics who presented other etiologies. We also concluded that late mortality was not related to the implant of a LeVeen shunt but was due to the normal course of the disease.

Ascites↗
PubMedDate not supplied

[Surgical treatment of portal hypertension in patients with liver cirrhosis].

Surgical options in the treatment of portal hypertension in cirrhotics are reviewed, regarding elective and emergency cases as well as the results in alcoholics and non-alcoholics. After literature review and personal experience analysis, it is concluded that endoscopic sclerotherapy should be the treatment of choice in cirrhotic patients with bleeding esophageal varices. When this fails, distal splenorenal shunt is indicated for compensated Child A and B. Regarding Child C and decompensated Child B, the choice should be a portocaval or meso caval shunts or esophageal transection with a stapler associated to splenectomy.

Esophageal and Gastric Varices↗
PubMedDate not supplied

[Use of the Leveen shunt in the treatment of clinically intractable ascites].

From January 1978 to August 1987, 21 patients received a peritoneovenous shunt using the Le Veen valve (LVV). The indications criteria were the long-term diuretic therapy failure (mean time = 24.4 months) or resistence to medical therapy during hospital internment. The 21 patients underwent 36 surgeries, being 4 valve position review and 11 changes of LVV. The mean age was 51.6 years. Fifteen patients had alcoholic cirrhosis, 3 postnecrotic cirrhosis, one Budd-Chiari syndrome, one mansoni Schistosomiasis, and one malignant ascites. Ten were Child B and 9 Child C patients. Eight patients with history of previous esophageal varices bleeding (EVB) underwent endoscopic sclerotherapy (EE) before LVV implantation. Seven patients died in the early postoperative period (3 Child B and 4 Child C patients). Three patients died due to EVB and the others as consequence of hepatic failure (one), cardiac insufficiency (one), sepsis (one), and bronchopneumonia (one). The mean follow-up was 19.9 months (1-61). Early LVV occlusion occurred in 4 patients and late valve occlusion in others 4 patients. The LVV changes were done at ambulatorial preceeding. Ten patients (47.6%) died in late follow-up and in these cases death was related to the main disease course. It is concluded that: 1) LVV is a useful therapy in patients with intractable ascites, since it is not the terminal manifestations of disease; 2) early mortality is related to liver function and late mortality to main disease course; 3) ascitic patients with EVB should undergo endoscopic sclerotherapy before LVV implantation.

Actuarial Analysis↗
PubMedDate not supplied

[Pyogenic liver abscesses: analysis of 36 cases treated by percutaneous drainage].

Thirty-six patients with pyogenic liver abscess treated by percutaneous drainage plus antibiotic therapy were reviewed. The most frequent symptoms were fever (75%) and pain (72.2%), and the most common physical signs were liver enlargement (58.3%) and jaundice (33.3%). The mean time interval from admission to diagnosis was 16 days. CT scans and ultrasonography were diagnostic in 100% of the patients. The percutaneous drainage was effective in one attempt in 19 patients, two attempts in 8, three attempts in 8 patients and more than four attempts in only one patient. There were three patients with hemoperitoneum (8.7%) as a post-drainage complication, one of them needed to be treated surgically. Mean hospital stay was of 24.8 days and the mortality rate was 5.5%. Percutaneous drainage plus antibiotic therapy is then an efficient therapeutic approach to the treatment of pyogenic liver abscess.

Adolescent↗
PubMedDate not supplied

[Hepatic hemangioma. Analysis of 103 cases. Clinical considerations and imaging methods].

Hemangiomas are the most common benign vascular tumor found in the liver. In this study, 103 cases of hepatic hemangiomas were analysed in a retrospective manner. Image aspects such as those seen in ultrassonography, computed tomography, nuclear magnetic resonance and arteriography are discussed. The incidence was higher amongst the female sex, between individuals from 40 to 60 years old, which presented predominantly without symptoms (66%) and localized mainly in the right hepatic lobe (74%). The meaning of those aspects, when adopted, permits the clinicians to differentiate benign from malignant nodular lesions in the liver.

Adult↗
PubMedDate not supplied

Cholelithiasis in cirrhotic patients. (Analysis of cholelithiasis among patients with liver cirrhosis in São Paulo, Brazil).

During the past 20 years, several authors have reported increased prevalence of cholelithiasis in liver cirrhosis. This biliary disease has been implicated with the deterioration of liver function, liver disease of alcoholic origin or even the presence of hypersplenism in this patient population. This study analyzes the incidence and possible factors which are responsible for promoting cholelithiasis in cirrhosis. The study included 110 cirrhotic patients of a private center specialized in treating liver diseases. The incidence of cholelithiasis was 27.3% (25.3% in males and 33.3% in females). There was no correlation between liver function defined by Child's classification or through the laboratory examinations (AST, ALT, AP, GGT, PT, Alb, TB, DB, PA) and the presence of gallstones. No evidence was found that the etiology of cirrhosis or the presence/absence of hypersplenism affected the prevalence of cholelithiasis in this population. In conclusion, an increased prevalence of cholelithiasis was verified in this population of cirrhotics but the pathogenesis is still obscure.

Adolescent↗