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Biomedical subjects

M Valente

Publications and source records attributed to M Valente.

At least 199 records · Page 11Linked to original sources
PubMed1986

Growth characteristics of human colorectal and non-small cell lung tumors xenografted into nude mice: possible correlation with prognosis.

Specimens from human colorectal tumors and from non-small-cell lung tumors obtained at surgery were subcutaneously implanted as xenografts in athymic Swiss mice of both sexes to investigate to what extent the properties of the original tumors were maintained. A successful take was obtained in 5 of 9 colorectal tumor and 6 of 11 non-small-cell lung tumor xenografts. Moreover, 44% and 45% of the respective tumors could be established as tumor lines. Neither metastases nor local tumor invasion was observed in tumor-bearing mice. Seven of 9 serially transplantable tumors had a short latency period (14-30.5 days) when first xenografted. No significant changes in tumor histopathology were noted after growth into nude mice. Tumor take was partially related to clinical stage and prognosis of patients. In fact, 8 of 12 specimens from N0 patients failed to grow, whereas 7 of 8 tumors from patients with nodal invasion and/or metastasis grew in nude mice. Moreover, for the group of patients whose tumor was "take - ", the one-year survival was 85%, compared to 40% for the "take + " group (p less than 0.05).

Adult↗
PubMed1986

Kallikrein and kininase activities excretion in newborns affected by jaundice.

In a homogeneous group of 30 newborns, aging between 10 hours--10 days, and affected by jaundice, urinary kallikrein and kininase activities were determined. The variable considered were: sex, time of life, weight and gestational age. Urinary samples were taken at the beginning and at the end of phototherapy.

Birth Weight↗
PubMed1986

Perioperative blood transfusion and prognosis of resected stage Ia lung cancer.

Based on the experience of blood-related immunosuppression in kidney transplants, some retrospective studies have reported an adverse relationship between blood transfusion and survival after curative resection for cancer. In order to confirm these findings, we have retrospectively evaluated our population of resected stage Ia non-small cell lung cancers (years 1974-79). Two hundred and eighty-three patients were included in this analysis: 65 underwent pneumonectomy (23%), 205 lobectomy (72%) and 13 sublobar resections (5%). Patients submitted to perioperative blood transfusions were 157 (55%), without major differences according to surgery or tumour extent. The cumulative survival at 8 yr was 40% for transfused patients and 41% for nontransfused, relapse-free survival was respectively 36% and 34%; no differences were detectable stratifying for the amount of blood transfused or the extent of operation. Our experience does not support the hypothesis of an adverse prognosis related to perioperative blood transfusion.

Carcinoma, Non-Small-Cell Lung↗
PubMed1986

Experimental evaluation of porcine-valved conduits processed with a calcium-retarding agent (T6).

The effectiveness of a water-soluble C-12 alkyl sulfate (T6) (U.S. Patent No. 4,323,358) in retarding bioprosthetic calcification was evaluated in 23 porcine-valved conduits (13 T6-treated conduits and 10 controls) implanted in young sheep between the right ventricle and the pulmonary trunk. The grafts were divided into three groups according to the period of function: Group I, less than 2 months; Group II, 2 to 4 months; and Group III, 5 to 7 months. In Group I (four T6 and four controls), endocarditis occurred in five cases. In Group II (three T6 and three controls), four conduits showed severe fibrous peel ingrowth. In Group III (six T6 and three controls), fibrous peel was the main feature in four conduits and calcium deposits occurred in the porcine aortic wall in all cases, with cusp involvement in two; in both T6-treated and control conduits, chemical analysis showed a much lower calcium content of the cusps (8.45 +/- 80 versus 2.95 +/- 1.52 mg/gm dry weight, respectively) than that reported in other animal or human explants. The grade of calcification in control and T6-treated conduits was equal on x-ray analysis, and no differences in calcification patterns were noted on electron microscopy. This experimental model shows a low degree of cusp calcification and no significant differences between T6-treated and control conduits. Peel formation markedly interferes with performance of the porcine-valved conduit. The results of this analysis indicate that valved conduits are not the optimum model for evaluating calcium-retardant agents in biological valves.

Animals↗
PubMed1985

Inhibitory action of quercetin on xanthine oxidase and xanthine dehydrogenase activity.

Quercetin is an equally good inhibitor of xanthine oxidase (type O, oxygen-reducing enzyme) and xanthine dehydrogenase (type D, NAD+-reducing enzyme) activity of a preparation of the xanthine-oxidizing enzyme partially purified from rat liver. The inhibition seems competitive with the oxidase form and non-competitive (mixed-type) with the dehydrogenase form of the enzyme. These inhibitory properties should be referred to the flavonoid structure of quercetin rather than to its antioxidant power. The antioxidant properties of quercetin and its inhibitory effect on the xanthine-oxidizing enzyme are discussed with reference to hyperuricemic and ischemic states.

Animals↗
PubMed1985

[Unstable angina with recurrent episodes of transient elevation of the ST segment: role of transluminal percutaneous angioplasty].

Transluminal angioplasty was performed as an urgent treatment in 9 patients with unstable angina, refractory to medical therapy and ST elevation during pain. All had a coronary stenosis greater than 50% (89 +/- 12%; range 60-99%). The left anterior descending coronary artery was affected in 6 patients, the right coronary artery in 1 patient, the circumflex in 1 patient and 1 patient had two stenosis on both the left anterior descending and the first diagonal branch. A reduction of the luminal stenosis greater than 20% was obtained in all (residual stenosis 30 +/- 11%; range 11-40%). During a follow-up of 6-20 months, two patients only showed recurrence of chest pain. A maximal ergometric test was negative in all patients after 1, 3 and 6 months. A second arteriography, performed in 7 patients after 3-6 months, demonstrated a mean stenosis of 35% (range 30-40%). Transluminal coronary angioplasty is a feasible and effective therapeutic approach in patients with unstable angina and ST elevation, when a significant coronary stenosis is present.

Adult↗
PubMed1985

Vestibular evaluation of infants and preschool children.

This article presents an updated summary of vestibular test modifications employed at the Boys Town National Institute for Communication Disorders in Children. In addition, we report the results of vestibular evaluations of 104 full-term and premature children (47 male and 57 female) ranging in age from 3 months to 6 years, including a group of postmeningitic patients. The evaluations utilized harmonic acceleration (HA). No age-related maturational differences in HA gain, phase, or symmetry for an 0.08 Hz screening frequency were found when full-term and premature infants were compared. Infrared video technology was adapted to provide continuous visual monitoring of head and eye position in the totally darkened test enclosure.

Caloric Tests↗
PubMed1985

Ultrastructural substrates of dystrophic calcification in porcine bioprosthetic valve failure.

Calcific degeneration is the main cause of porcine bioprosthetic valve failure. This dystrophic phenomenon has been studied by transmission electron microscopy in 26 explants; six normally processed unimplanted xenografts and a pig aortic valve from the slaughterhouse served as controls. Loss of endothelial lining and proteoglycans were a regular finding in all the commercially processed valves. In order to detect initial calcifications, we investigated in particular areas apparently devoid of mineralization at x-ray. Three main ultramicroscopic features were found: 1) intracytoplasmic and interstitial calcospherulae in 22 explants, 2) calcified collagen fibrils in 15, and 3) platelike calcium deposits upon amorphous material in 3. X-ray diffraction and energy-dispersive microanalysis identified Ca2+ deposits as crystals of hydroxyapatite. From these findings there is evidence that debris and membrane fragments of the pig cusp cells represent one of the initial nuclei of calcification.

Animals↗
PubMed1985

Inhibition of lipid peroxidation by alpha-tocopherolquinone and alpha-tocopherolhydroquinone.

The antioxidant effect of alpha-tocopherolquinone and alpha-tocopherolhydroquinone was studied in liposomes and rat liver submitochondrial particles. Both alpha-tocopherolquinone and alpha-tocopherolhydroquinone inhibit lipid peroxidation induced by ascorbate/Fe2+ in liposomes and by cumene hydroperoxide in submitochondrial particles. Alpha-tocopherolhydroquinone is much more effective than alpha-tocopherolquinone in inhibiting lipid peroxidation. Submitochondrial particles, depleted of ubiquinones and reincorporated with alpha-tocopherolquinone, are protected from lipid peroxidation only in the presence of succinate. Alpha-tocopherolquinone cannot replace endogenous ubiquinones in the respiratory chain function, nevertheless it can be reduced by the mitochondrial respiratory chain substrates, presumably through the reduced ubiquinones.

Animals↗
PubMed1984

The growth rate in the interpretation of the natural history of lung cancer.

The relationship between growth rate, expressed as doubling time (DT), of 110 lung cancers from randomly collected patients and patient age, sex, histological type, symptoms, smoking habits, size and lymph node involvement was studied. Median DT values of epidermoid carcinomas and adenocarcinomas were superimposable (98 and 99 days, respectively), but 15% of adenocarcinomas had a DT of more than one year. Significant correlations were found with sex (slower growth rate in females) and symptoms (faster growth in symptomatic patients), but only for adenocarcinomas. The number of cigarettes smoked did not seem to affect the growth rate of lung cancers. There was no correlation between growth rate and tumor size or lymph node involvement.

Adult↗
PubMed1984

Comparison of cumene hydroperoxide- and NADPH/Fe3+/ADP-induced lipid peroxidation in heart and liver submitochondrial particles. Mechanisms of protection by succinate.

The NADPH/Fe3+ /ADP system stimulates lipid peroxidation both in rat liver and bovine heart submitochondrial particles, while cumene hydroperoxide is active only in rat liver submitochondrial particles. The lack of a peroxidizing effect of cumene hydroperoxide in heart submitochondrial particles was related to the absence of cytochrome P-450. When ubiquinones are extracted from rat liver and bovine heart submitochondrial particles, succinate can still partially protect the cumene hydroperoxide-induced lipid peroxidation but not the peroxidation induced by NADPH/Fe3+ /ADP. The protective effect of succinate in lipid peroxidation was referred either to the reduction of ubiquinones that can act as antioxidants in the NADPH/Fe3+ /ADP system, or to the reduction of cytochrome P-450 that acts as a peroxidase in the cumene hydroperoxide system.

Adenosine Diphosphate↗
PubMed1984

Calcific degeneration as the main cause of porcine bioprosthetic valve failure.

Sixty-seven glutaraldehyde-processed porcine bioprostheses (PBs), recovered at autopsy or reoperation from 65 patients, were evaluated by roentgenologic and pathologic examination. Seven patients with 8 PBs were younger than 20 years of age. The time interval of function was 2 to 138 months (average 62). Pathologically, 53 explants had signs of intrinsic dysfunction, which was ascribed to calcification in 36 (68%). By x-ray examination, calcific deposits were found in 55 of 67 PBs (82%). The mean duration of function was 70 +/- 32 months in calcified PBs vs 27 +/- 18 months in noncalcified PBs (p less than 0.001). All 26 PBs that had been in place for longer than 6 years were calcified. In 45 PBs the Ca++ deposits were considered severe (mean time of function 76 +/- 32 months) and mild in 10 (mean time of function 44 +/- 22 months) (p less than 0.005). The Ca++ deposits were located at the commissures in 54 PBs (98%), at the body of cusps in 41 (75%), at the free margin in 37 (67%) and at the aortic wall in 37 (67%). When mild, Ca++ deposits involved the commissures in 90% of cases, the body of cusps in 30% and the free margin only in 10%. Forty-seven calcified PBs were mounted on a flexible stent, and 8 had a rigid stent, with an average time of function of 63 +/- 28 and 113 +/- 18 months, respectively (p less than 0.00001). Ca++ dysfunction occurred earlier in the aortic than in the mitral position (59 +/- 19 vs 86 +/- 35 months, p less than 0.05). All the PBs explanted from young patients and 47 of 59 PBs removed from adult patients were calcified, with an average time of function of 50 +/- 21 vs 73 +/- 33 months, respectively (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗