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Biomedical subjects

M Valente

Publications and source records attributed to M Valente.

At least 217 records · Page 12Linked to original sources
PubMed1984

Cardiac myxomas: results of 14 years' experience.

From January 1968 to July 1983, 38 patients with an intracardiac myxoma underwent surgical excision of the tumor at our Institution. There were 15 males and 23 females, ranging in age from 17 to 68 years (mean 47.7). In all but 2 patients, the presence of an intracardiac myxoma was documented preoperatively by angiographic and/or echocardiographic study. The first 2 patients of this series were referred with the diagnosis of mitral stenosis, and the myxoma was an unexpected surgical finding. In 32 cases (84.2%) the myxoma was located in the left atrium, in 4 (10.5%) in the right atrium and in 2 (5.3%) in the right ventricle. Surgery was performed on an emergency basis in 36 patients. Two patients (5.2%) both with a left atrial myxoma, died after surgery: one died intraoperatively of hemorrhage and the other after one month of bowel infarction. Follow-up of the 36 survivors ranges from 3 months to 14.5 years (average 5.2 yr); all were controlled by means of clinical and echocardiographic investigations, and no evidence of tumor recurrence was detected. Surgery for intracardiac myxoma, which should be undertaken on an emergency basis, carries a low operative risk; excision of the tumor appears to be curative with no recurrences at long-term follow-up; non-invasive tools are of the utmost importance in both the preoperative assessment and follow-up of these patients.

Adolescent↗
PubMed1983

Surgical treatment for carcinoma of the gastric cardia: a modified proximal esophagogastrectomy.

Proximal esophagogastrectomy saving only the distal half of the greater curvature of the stomach was retrospectively evaluated in 91 consecutive patients with resectable carcinoma of the gastric cardia. Division of the right gastric artery at its beginning provided a free nodal margin if N1 diffusion was observed. Operative mortality was 6.5% and fatal leak rate 3.8%. Survival without dysphagia occurred in all but stage I tumors; for larger tumors recurrence and reflux esophagitis were not able to produce dysphagia because distant metastases were faster to kill the patients. Five-year survival was 0% for stage IV (i.e. incomplete macroscopic resection), 8% for stage III, 12% for stage II and 53% for stage I. Local recurrence occurred only at esophageal anastomosis and for every stage, whereas regional recurrence occurred only for tumors with nodal diffusion. The results of this study are not suitable for a comparison with total esophagogastrectomy by inductive logic, nevertheless deductive arguments are possible if patterns of recurrence are considered. The possibility of regional recurrence for N1 and not for N0 tumors means that the volume of nodal resection has diagnostic specificity for N0 but not for N1 tumors. If N2 nodal diffusion is really a sistemic disease, as indicated by current reports, than greater nodal resection by total esophagogastrectomy can only improve the diagnostic specificity of N1 assessment but not survival.

Aged↗
PubMed1983

NADH and NADPH inhibit lipid peroxidation promoted by hydroperoxides in rat liver microsomes.

Lipid peroxidation induced through cytochrome P-450 activation of cumene hydroperoxide, linolenic acid hydroperoxide and peroxidized phosphatidylcholine in rat liver microsomes is markedly inhibited by either NADH or NADPH. This inhibition is not due to an antioxidant effect. Conversely, cumene hydroperoxide decomposition is stimulated by the reduced pyridine nucleotides but not by some modifiers of cytochrome P-450 (SKF-525A, metyrapon and aniline). The mechanism by which NADH and NADPH prevent lipid peroxidation may involve a reduction of the hydroperoxides mediated by cytochrome P-450 and occurring without formation of free radical forms that are usual sparkers of lipid peroxidation.

Animals↗
PubMed1983

Impact on survival of the extent of resection in unrelapsed lung cancer.

Five-year survival of resected stage Ia non-oat cell lung cancer was evaluated in 69 consecutive patients without recurrence. The impact of the extent of resection on perioperative and long-term mortality was studied after an evaluation of confounding factors, such as age and associated cardiopulmonary diseases, which further stratified our series. Our patients were subdivided into 2 groups: the first included lobectomies and was further subdivided into 2 subsets according to whether the operation had caused the resection of less than 4 (30 cases) or more than 3 segments (18 cases). The second one included pneumonectomies (21 cases). Thirty-two patients were 60 years or older; pulmonary and/or cardiovascular diseases were assessed in 38 patients. There were 6 perioperative deaths, 3 among major lobectomies (more than 3 segments resected) and 3 among pneumonectomies. Survival rate of lobectomies was 75% (86% for minor, 55% for major lobectomies), and 57% for pneumonectomies. Major lobectomies included the highest percentage of elderly patients with cardiopulmonary diseases who had significantly poorer survival probabilities than young subjects without cardiopneumopathies. Lobectomy cases, after standardization by age, had a significantly higher probability of surviving than pneumonectomy cases. Standardization by cardiopulmonary disease showed a better chance for lobectomy cases, although it was not significant. Major lobectomy cases had poorer cumulative survival rate than minor lobectomy cases. Such a difference was revealed in patients 60 years or older and in those with pneumocardiopathies.

Adult↗
PubMed1983

Effects of palmitoyl coenzyme A on rat skeletal muscle sarcoplasmic reticulum.

Palmitoyl coenzyme A (PCoA) inhibits Ca2+ uptake and stimulates Ca2+-activated ATPase in sarcoplasmic reticulum vesicles. The inhibitory effect on Ca2+-uptake is referable to a stimulation of Ca2+ release which is directly correlated to the concentration of PCoA added. The comparison of the Ca2+-releasing effect of PCoA in different experimental conditions indicates that concentrations of PCoA higher than 10 microM may be disruptive for the vesicles while concentrations of PCoA lower than this value can activate a Ca2+-releasing channel or more generally can increase the membrane permeability for Ca2+.

Acyl Coenzyme A↗
PubMed1983

Glutaraldehyde-preserved porcine bioprosthesis. Factors affecting performance as determined by pathologic studies.

The causes of porcine valve failure were evaluated pathologically in 129 bioprostheses (BP) removed at surgery or necropsy. Fifty-one BP had been in place for less than two months (early explants); most of the complications of this group were observed in the mitral position: left ventricular outflow obstruction (43 percent), thrombosis (23.5 percent), myocardial dysruption (20 percent), cardiac rupture (10 percent), and perivalvular leak (3.5 percent). Among the 78 explants in place for more than two months (late explants), 66 had evidence of dysfunction. Calcification was the leading cause of failure (46 percent), followed by thrombosis (17 percent), endocarditis (12 percent), fibrous tissue overgrowth (10 percent), perivalvular leak (9 percent), and primary cusp tears (6 percent). Calcific degeneration is a hallmark of the phenomenon of biodegradation, and experimental animal models are encouraged since they may represent the clue to preventing calcification and therefore enhancing performance and durability of the porcine BP.

Adolescent↗
PubMed1983

Structural profile of cardiac myxoma.

In the 10-year period 1972-1981, 35 cardiac myxomas from 34 patients were studied. 29 tumors were surgical specimens and 6 were necropsy observations. No patient was under 10 years and only 3 were in the second decade. 25 growths were located in the left atrium, 6 in the right atrium and 2 in the right ventricle; 1 patient presented with myxomas involving both atria. The surface examined in 31 tumors appeared villous in 15, smooth in 13 and slightly irregular in 3. The tumor cells were enmeshed in Alcian blue positive mucoid material and presented as isolated, aggregated in clusters or in small cords, or lining vascular-like spaces. Ultrastructural examination performed in 9 cases disclosed a few features of endothelial cells: microvilli, cell interdigitations, desmosomes and pinocytotic vesicles; cytoplasmic organelles were usually more numerous in the cells arranged in clusters and lining spaces than in those isolated or in small cords; well-developed Golgi complex and endoplasmic reticulum were frequently observed and suggest a secretory function for the myxoma cells. The findings herein reported together with those of recent cytochemical studies support a mesenchymal origin for the myxoma cells with differentiation to endothelial line.

Adolescent↗
PubMed1982

Hydrolysis of ITP generates a membrane potential in submitochondrial particles.

ITP hydrolysis catalysed by the ATPase of submitochondrial particles from both bovine heart and rat liver is shown to be linked to the generation of a membrane potential, and therefore also to proton translocation. The magnitude of the membrane potential is similar to that observed during ATP hydrolysis at equivalent concentrations of phosphate and nucleoside tri- and diphosphates. An explanation is suggested for why in other reports ITP was found to be a poor substrate for supporting energy-linked reactions that are driven by the membrane potential.

Adenosine Triphosphatases↗
PubMed1982

Purification from pig liver of a protein which protects liposomes and biomembranes from peroxidative degradation and exhibits glutathione peroxidase activity on phosphatidylcholine hydroperoxides.

The cell sap from pig liver contains a protein which protects phosphatidylcholine liposomes and biomembranes from peroxidative degradation in the presence of glutathione. The activity of this protein has been assayed by measuring the inhibition of aged phosphatidylcholine liposome peroxidation induced by the Fe3+-triethylenetetramine complex. The peroxidation-inhibiting protein from pig liver has been purified 585-fold to homogeneity with overall recovery of activity of 12%. (NH4)2SO4 precipitation, ion-exchange chromatography on DEAE-Sepharose CL-6B and CM23-cellulose, affinity chromatography on glutathione-bromosulfophthalein-Sepharose and gel filtration on Sephadex G-50 were used. Gel filtration and SDS- polyacrylamide gel electrophoresis indicated a molecular weight of approximately 20 000. The protein inhibited peroxidation by Fe3+-triethylenetetramine following a 15 min preincubation of phosphatidylcholine liposomes in the presence of 5mM glutathione or 2-mercapthoethanol. The pure protein exhibited glutathione peroxidase activity on hydroperoxide groups of phosphatidylcholine and on cumene and t-butyl hydroperoxides, with specific activities of 2.2, 3.8 and 0.9 mumol/min per mg protein, respectively. The protein appears to be distinct from the selenoenzyme glutathione peroxidase and from any known glutathione S-transferase. The peroxidation was studied also with fresh phosphatidylcholine liposomes and was induced in this case by Fe-ascorbate. To obtain protection by the peroxidation-inhibiting protein and glutathione, preincubation was not necessary, but alpha-tocopherol, incorporated in the liposomes in the molar ratio 1:250 to phosphatidylcholine, was required. Lipid peroxidation of rat liver mitoplasts and microsomes was blocked when these preparations were incubated in the peroxidizing mixture in the presence of peroxidation-inhibiting protein and glutathione. The protection from Fe3+-triethylenetetramine-induced peroxidation is related apparently to reduction of hydroperoxide groups in polyunsaturated fatty acid residues of phospholipids and to inhibition of free radicals formation by chain branching. Protection from the Fe-ascorbate-induced peroxidation is apparently attributable to the same mechanism. However, the requirement of alpha-tocopherol for protection in the Fe-ascorbate-induced peroxidation suggests that the cooperation of a free-radical scavenger is necessary. It is probable that the glutathione peroxidase activity is involved also in the glutathione-dependent protection exhibited by the protein on lipid peroxidation of biomembranes.

Animals↗
PubMed1982

Common-sense untoward factors in lung cancer resection.

Four common-sense untoward factors (age over 60, pneumonectomy, microresidual disease, and postoperative empyema) were retrospectively evaluated in a consecutive series of 199 surgically apparently complete non-oat cell lung cancer resections. By single-factor analysis all factors showed a lower survival that was contingent for microresidual disease and age over 60. For stage I tumors the negative impact on survival was significant for all except empyema, and for stage II and III tumors only for empyema. Without confounding factors, microresidual disease and age over 60 were negative prognostic factors only for distant mortality, empyema a negative prognostic factor only for early mortality, and pneumonectomy a probable negative prognostic factor for both early and distinct mortality. It is concluded that the scientific method used confirmed the prognostic assessment of common sense for these four factors.

Age Factors↗
PubMed1982

Pregnancy in patients with a porcine valve bioprosthesis.

Seven patients who became pregnant after valve replacement with a Hancock bioprosthesis were followed up during 8 pregnancies. Six had undergone isolated mitral valve replacement, and 1 had mitral and aortic valve replacement. Their age at the time of operation ranged from 14 to 31 years (average 24); delivery occurred 21 to 88 months (average 51.3) after valve replacement. All women were in sinus rhythm at the time of gestation, and administration of oral anticoagulants was avoided in all. No embolic episodes occurred either after operation or during pregnancy, labor, or puerperium. The only major complication during pregnancy was cardiac failure in 1 patient, associated with onset of atrial fibrillation. Four women had vaginal delivery and 3 required cesarean section. All but 1 delivered a normal, healthy baby. One premature infant died soon after birth because of respiratory distress. No maternal or fetal hemorrhagic complications were observed. One patient died 3 months after delivery in severe heart failure caused by diffuse calcification of both mitral and aortic xenografts. Another women underwent successful reoperation soon after the second pregnancy because of calcific stenosis of the mitral porcine valve. It is concluded that (1) bioprosthetic valves can be considered the most suitable devices employed in women of childbearing age because anticoagulants can be avoided, therefore eliminating the risks related to inappropriate administration of oral anticoagulants as well as the hazards associated with the potential teratogenic effect of coumarin drugs; and (2) pregnancy might favor calcification of porcine heterografts, leading to bioprosthetic failure. Until further data are available to support this suspicion, close clinical and echocardiographic follow-up study of these patients is recommended after pregnancy.

Adolescent↗
PubMed1982

Right ventricular myxoma: review of the literature and report of two patients.

The cases of 2 patients with right ventricular myxoma are reported, together with a review of the literature. In both patients the ultimate diagnosis was reached by means of angiocardiography, which revealed large filling defects in the right ventricle. In 1 patient, cardiac catheterization failed to record a transpulmonary gradient. Echocardiography, performed after hemodynamic investigation in both patients, revealed the usual pattern of abnormal echoes moving from the right ventricular cavity to the right outflow tract during the cardiac cycle. In both patients the tumor was successfully excised through a right atrial approach. This approach was preferred to the right ventriculotomy because it provides adequate surgical exposure, avoids undue trauma to the ventricular myocardium, and offers an easy way for inspection of the left heart.

Adolescent↗
PubMed1982

Empyema following lung cancer resection: risk factors and prognostic value on survival.

A retrospective evaluation of 199 consecutive patients undergoing resection for lung cancer revealed a significantly shorter long-term survival for those in whom empyema developed postoperatively. The overall five-year survival for the empyema group was 24% compared with 35% in the control group (patients without empyema), and the median survival was 15 months for the control group. These differences in survival were not found among patients with Stage I lung cancer. Pneumonectomy proved to be the main risk factor for the occurrence of empyema after operation, but a minor risk factor was the anatomical extent of disease. this correlation may be explained by major surgical contamination or manipulation as well as by lower immunological host reaction, all related to the extent of the tumor. A lower immunological defense could also explain the worse outcome for patients with Stage II or III lung cancer in whom empyema developed postoperatively.

Adolescent↗
PubMed1982

Evidence of impending embolization of a calcific cusp fragment from a mitral porcine xenograft.

The use of porcine bioprostheses has been associated with a low rate of embolic complications. The case here presented provides evidence that systemic emboli in porcine valve recipients may not necessarily be due to intracardiac or prosthetic thrombosis, but to detachment and migration of fragments of degenerated cusp tissue. Therefore, urgent assessment of xenograft function is recommended in patients with a porcine bioprosthesis who experience embolic episodes late postoperatively.

Bioprosthesis↗
PubMed1982

Effect of chronic cardiopulmonary disease on survival after resection for stage Ia lung cancer.

The role of chronic cardiopulmonary disease as a risk factor for immediate and late mortality was evaluated retrospectively in a consecutive series of 116 patients who had had resections for stage Ia non-oat-cell lung cancers. The presence of chronic cardiopulmonary disease was diagnosed on the clinical history and preoperative assessment of lung and heart function by traditional means. Patients with chronic cardiopulmonary disease showed a lower five-year survival rate than controls--35% versus 53% (p less than 0.08). The difference increased and became significant if besides having cardiopulmonary disease the patient was over 60 years of age or had had a pneumonectomy--30% versus 52% (p less than 0.025). A higher operative mortality was the main reason for the lower observed survival. Nevertheless, survival of patients at risk exceeded 30% in each subgroup, being 33% for patients over 60 undergoing pneumonectomy. In our series the benefits of resection of lung cancer in patients with impaired cardiopulmonary function were greater than the risks of perioperative and later death even in the groups with a poorer prognosis.

Adult↗
PubMed1982

Intensive iron chelation therapy in beta-thalassemia major: some effects on iron metabolism and blood transfusion dependence.

Subcutaneous infusions of Desferal (DF) rarely induce negative iron balance in thalassemia major patients less than 6 years old. In nonsplenectomized patients the requirements for blood transfusions increase slightly. Urinary iron excretion decreases during the first days following a blood transfusion. An average of 5.8 mg/day equivalent to 30% of the total iron excretion is eliminated with the feces after subcutaneous infusions of DF. Serum ferritin does not decrease significantly after 18-24 months of therapy. The effectiveness of long-term therapy progressively increases in the splenectomized patients, while it decreases appreciably in the course of the treatment in the nonsplenectomized ones.

Adolescent↗