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Biomedical subjects

M Valente

Publications and source records attributed to M Valente.

At least 91 records · Page 5Linked to original sources
PubMed1997

Comparison of the water diuretic activity of kappa receptor agonists and a vasopressin receptor antagonist in dogs.

Strategies for developing selective water diuretic agents have involved development of kappa opioid receptor agonists and vasopressin V2 receptor antagonists; however, these two classes of compounds have not been compared directly. We have investigated the activity of three kappa receptor agonists and one nonpeptide vasopressin receptor antagonist in conscious dogs. SB 215520, SB 215519 and niravoline are selective kappa agonists with variable abilities to cause a water diuresis and ataxia in rats. When administered to conscious hydropenic dogs, the kappa agonists resulted in an increase in free water clearance; however, these effects were associated with an antinatriuresis, an increase in heart rate and, at the higher doses, central nervous system side effects. Conversely, the vasopressin receptor antagonist, OPC 31260, resulted in a significant water diuresis without any accompanying changes in sodium excretion and heart rate, and with no apparent central nervous system effects. These studies suggest that, at least in dogs, a vasopressin receptor antagonist is a more selective water diuretic than a kappa receptor agonist.

Animals↗
PubMed1997

[Profound venous thrombosis and popliteal cyst: problems of differential diagnosis relative to the use of phleboscintigraphy. Description of a clinical case].

The following is the case report of M. G. a 68-year-old male carrier of polcythemia vera, a pathology in which the risk of thrombosis is increased. The patient presented clinically suspected deep venous thrombosis and a phleboscintigraphy confirmed the diagnosis. A real-time B-mode ultrasonography performed later instead demonstrated a popliteal cyst. The case report focuses on diagnostic methods in deep venous thrombosis and particular attention is paid to the role of phleboscintigraphy, of impedance plethysmography and of real time B-mode ultrasonography.

Aged↗
PubMed1997

Differences in performance between Oticon MultiFocus Compact and ReSound BT2-E hearing aids.

Differences in performance were evaluated between binaural fittings of the Oticon MultiFocus (MF) and ReSound BT2-E on 25 hearing-impaired subjects across two sites. Subjects were initially fit using each manufacturer's algorithm and adjustments were made at 1 week based on subjects' responses to diary questions. Performance was assessed after a 4- to 6-week trial period with each hearing aid set using the Speech Perception in Noise (SPIN) test administered at 50, 65, and 80 dB SPL, the Abbreviated Profile of Hearing Aid Benefit (APHAB) questionnaire, loudness judgments of female connected discourse at 65 and 80 dB SPL, and an overall preference selection. The MF yielded significantly better SPIN scores at 50 and 65 dB SPL, while the BT2-E yielded a significantly better score at 80 dB SPL. No statistically significant differences were found in the APHAB benefit scores between the hearing aid sets, but both sets were significantly better than the subjects' own hearing aids on three of the four subscales. The MF produced slightly higher mean loudness judgments at both input levels than the BT2-E. Finally, 12 subjects preferred the BT2-E, 10 subjects preferred the MF, and three subjects stated no preference. The results are discussed in terms of audiogram effects on preference and effects of differences in signal processing approaches between the devices.

Audiometry↗
PubMed1996

Arrhythmogenic right ventricular cardiomyopathy. Dysplasia, dystrophy, or myocarditis?

BACKGROUND: Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a frequent cause of sudden death in young individuals and athletes. Although familial occurrence has been documented and a gene defect was recently localized on chromosome 14q23-q24 the etiopathogenesis of the disease is still obscure. METHODS AND RESULTS: A pathological study was conducted in 30 hearts with ARVC (age range, 15 to 65 years; mean, 28 years). In the 27 autopsy cases, the mode of death was sudden in 24 and congestive heart failure in 3. ECG, available in 19 cases, showed inverted T waves in the right precordial leads in 15 cases (79%) and ventricular arrhythmias in 15 (79%). Right ventricular aneurysms were present in 15 hearts (50%) and located in the inferior wall in 12. Left ventricle and ventricular septum were involved in 14 (47%) and 6 (20%) cases, respectively. Scattered foci of lymphocytes with myocardial death were observed in 20 cases (67%). Electron microscopy studies, although confirming the myocardial death and lymphocyte infiltrates, did not show any specific ultrastructural substrate. Two pathological patterns, fatty (40%) and fibrofatty (60%), were identified. The fibrofatty pattern was associated with a thinner right ventricular wall (P < .0001) and a higher occurrence of focal myocarditis (P < .001). In sections of right ventricular free wall with maximal fatty infiltration, the mean percentage area of fatty tissue was 35.9 +/- 11.1% in control versus 80.4 +/- 9.6% in the ARVC, fatty variety (P < .00001). Involvement of the left ventricle and/or ventricular septum, right ventricular aneurysms, and inflammation were found almost exclusively in the fibrofatty variety. CONCLUSIONS: In the fibrofatty variety of ARVC, the myocardial atrophy appears to be the consequence of acquired injury (myocyte death) and repair (fibrofatty replacement), mediated by patchy myocarditis. Whether the inflammation is a primary event or a reaction to spontaneous cell death remains unclear.

Adolescent↗
PubMed1996

Conservative management of esophageal leaks by transluminal endoscopic drainage of the mediastinum or pleural space.

BACKGROUND: The management of postoperative leaks into the mediastinum or pleural cavities after esophageal surgery yields unsatisfactory results. A recently described method, drainage of the mediastinum or pleural cavity through suture line defects, has been used in our department with eight patients. METHODS: A suction tube was advanced over an endoscopically placed guide wire into the abscess from inside the esophagus, and gentle aspiration was used to remove saliva and secretions. Intravenous antibiotics and total parenteral nutrition were also given. RESULTS: The sepsis was rapidly controlled, and the abscess cavity progressively collapsed in all cases. Seven patients recovered and were discharged 34 to 61 days after operation; one died of concomitant complications. CONCLUSIONS: This method seems promising for the management of intrathoracic esophageal leaks.

Aged↗
PubMed1996

Mixed gonadal dysgenesis: histological and ultrastructural findings in two cases.

Mixed gonadal dysgenesis (MGD) is an intersex genetic abnormality characterized by a streak gonad and a contralateral testis (that is typically cryptorchid) or bilateral streak testes. A uterus and one or both fallopian tubes also may be present. The external genitalia are frequently ambiguous. We studied two phenotypic "females" with MGD. One had a mosaic 45X (40%) and 46XYq (60%) karyotype, a left streak gonad, and a small testis in a right inguinal hernia, whereas the other had a 46XY karyotype, a left streak gonad, and, on the right, a testis with gonadoblastoma. On histological and ultrastructural examination the testis in the first case showed prepubertal tubules lined by a few spermatogonia and immature Sertoli cells with asynchronism in nuclear-cytoplasmic maturation. Ultrastructural examination of the gonadoblastoma in the second case showed neoplastic Sertoli cells. Irregular maturation of Sertoli cells appears to be a feature of MGD. Gonadal extirpation and pathological examination in these cases are important in order to make the correct diagnosis and prevent neoplastic changes.

Adolescent↗
PubMed1996

[The evaluation of rehabilitative therapy in peripheral arteriopathy. Our experience].

Motor rehabilitation alone is considered and effective treatment for patients affected by claudicatio intermittens although underlying diseases may often influence but not exclude its efficacy. According to the literature no agreement exists about rehabilitative methods. The authors, in order to contribute to a standardization of rehabilitative methods, report their experience characterized by good results. Moreover, the authors stress the importance of the treatment in desisting from habits like cigarette smoking.

Aged↗
PubMed1996

Low-profile porcine bioprosthesis (Liotta): pathologic findings and mode of failure in the long-term.

BACKGROUND AND AIMS OF THE STUDY: The Liotta low profile porcine bioprosthesis (LBP) was designed in order to minimize complications due to excessive protrusion of the stent prongs in the left ventricle. MATERIALS AND METHODS: From April 1984 to November 1993, 25 LBP surgical explants were available for pathology study, which included gross and X-ray evaluations. Reoperation was performed after a mean period of 95 +/- 25 months (range 46 to 143 months), in five males and 20 females (mean age at implantation 51.1 +/- 11.4 years). RESULTS: The cause of failure was stenosis due to cusp stiffness caused by dystrophic calcification in one and incompetence in 24 LBPs. In only one case was incompetence ascribable to endocarditis; in the remaining 23 the mechanism of regurgitation was due to commissural tearing (21 LBPs), commissural dehiscence (one LBP) and both tears and dehiscence (one LBP). Overall, 28 commissural tears were observed: 20 involved the right coronary cusp, eight the left coronary cusp, and none the non-coronary cusp. The anterior commissure was most frequently involved by tears (n = 17) followed by the right posterior (n = 9) and the left posterior (n = 2). Tears were calcium-related in all but two cases. Calcific deposits were observed in each explant, involving a total of 62 commissural attachments, 17 cusp bodies and five right muscular shelves. CONCLUSION: In conclusion, valve regurgitation is the usual mode of LBP failure in the mitral position; commissural tearing of the right coronary cusp was the most common cause of valve regurgitation, and occurred even in the presence of pin-point calcification. These pathologic findings seem to confirm that low profile design, which implies bulging of the right coronary cusp, entails the risk of increased stress at the commissures, accelerated calcification and tearing.

Adult↗
PubMed1996

[The evaluation of the use of DEAE-dextran in glycemic control in diabetic patients in pregnancy].

Thirty pregnant women with a pre-gestational history of type II diabetes or sugar intolerance and recruited during the second trimester of pregnancy, were administered DEAE-dextran (1 g x 3 times a day) in association with compensatory insulin therapy. Results of the end of trial tests showed amelioration of all of the parameters studied. The sugar curve after 120' from glucose load (100 g at fasting), showed a highly significant decrease at T90. Triglycerides T0 vs T90 gave p = 0.0001, probably due to improved body utilization of the insulin. DEAE-dextran was well tolerated and all of the patients enrolled at the beginning, completed the trial.

Blood Glucose↗
PubMed1995

The aortic valve after heart transplantation.

We studied the aortic root (wall, semilunar cusp, septal myocardium) in 37 patients (29 male and 8 female; mean age; 41 years) who died 2 to 4,380 days (mean, 398 days) after heart (n = 34) and heart-lung (n = 3) transplantation. The aim of the study was to assess tissue viability, graft-host biological interaction, and cusp mineralization with time. Study methods included gross inspection and photos of each specimen, microradiography, histology and immunohistochemistry, scanning and transmission electron microscopy, and atomic absorption spectroscopy. There were no cases of valve dysfunction; in particular, cusp tears or perforations never occurred. Only 1 valve, in place for 12 years, had a pin-point calcification visible to the naked eye. Optimal preservation of the tissue components (endothelium, fibroblasts, collagen and elastic fibers, proteoglycans, intrinsic nervous ganglia) was observed at both short and long term. Concomitant acute rejection of valve leaflets and myocardium was seen in 7, mild valve thickening in 14, myxoid degeneration in 4, and graft aortic atherosclerosis in 26. Mineralization was negligible and was not progressive with time. No linear correlation was found between mineralization and number of acute rejections. In conclusion, we observed optimal cusp viability and integrity even at long term, concomitant valve and myocardium rejection with no valvular sequelae, and negligible, non-progressive cusp calcification. Donor-recipient blood group matching, heart-beating donor, and chronic immunosuppression are the reasonable explanations of the optimal durability of the aortic valve after heart transplantation.

Adult↗
PubMed1995

Melanotic neuroectodermal tumor of the epididymis in infancy: case report and review of the literature.

Melanotic neuroectodermal tumor of infancy (MNTI) is a rare, benign tumor that usually involves the upper or lower jaw, but it may also arise in other sites. We describe a case of MNTI located in the left epididymis of a 6-month-old boy. Left orchiectomy was performed. Immunohistochemical and ultrastructural studies revealed two types of cells: small, poorly differentiated cells that were positive for neuron-specific enolase protein and vimentin, and larger epithelial cells that were positive for melanoma antigen (HMB45) and frequently contained large and elongated melanosomes, similar to those described in retinal pigmented epithelium. At 12 months of follow-up, no recurrences or metastases were seen. Primary involvement of the epididymis has been previously reported in only 16 cases. Immunohistochemical and ultrastructural studies suggest that the neoplasm is of neural crest origin.

Creatine Kinase↗
PubMed1995

Hydrogen peroxide induces a long-lasting inhibition of the Ca(2+)-dependent glutamate release in cerebrocortical synaptosomes without interfering with cytosolic Ca2+.

We studied the action of H2O2 on the exocytosis of glutamate by cerebrocortical synaptosomes. The treatment of synaptosomes with H2O2 (50-150 microM) for a few minutes results in a long-lasting depression of the Ca(2+)-dependent exocytosis of glutamate, induced by KCl or by the K(+)-channel inhibitor 4-aminopyridine. The energy state of synaptosomes, as judged by the level of phosphocreatine and the ATP/ADP ratio, was not affected by H2O2, although a transient decrease was observed after the treatment. H2O2 did not promote peroxidation, as judged by the formation of malondialdehyde. In indo-1-loaded synaptosomes, the treatment with H2O2 did not modify significantly the KCl-induced increase of [Ca2+]i. H2O2 inhibited exocytosis also when the latter was induced by increasing [Ca2+]i with the Ca2+ ionophore ionomycin. The effects of H2O2 were unchanged in the presence of superoxide dismutase and the presence of the Fe3+ chelator deferoxamine. These results appear to indicate that H2O2, apparently without damaging the synaptosomes, induces a long-lasting inhibition of the exocytosis of glutamate by acting directly on the exocytotic process.

Animals↗
PubMed1995

Four cases of acoustic neuromas with normal hearing.

In 95 percent of the cases, patients with acoustic neuromas will have some magnitude of hearing loss in the affected ear. This paper reports on four patients who had acoustic neuromas and normal hearing. Results from the case history, audiometric evaluation, auditory brainstem response (ABR), electroneurography (ENOG), and vestibular evaluation are reported for each patient. For all patients, the presence of unilateral tinnitus was the most common complaint. Audiologically, elevated or absent acoustic reflex thresholds and abnormal ABR findings were the most powerful diagnostic tools.

Adult↗
PubMed1995

Recognition of speech in noise with hearing aids using dual microphones.

Fifty subjects with mild to moderately severe sensorineural hearing loss and prior experience with amplification were evaluated at two sites (25 subjects at each site). Speech recognition in noise scores were measured using the Hearing in Noise Test (HINT) for each subject while wearing binaural behind-the-ear hearing aids allowing switching between two fitting algorithms ("basic" and "party") and two microphone conditions (single microphone omnidirectional and dual-microphone directional). Results revealed an average improvement in signal-to-noise ration (SNR) of 7.4 to 8.5 dB at the two sites for the directional conditions in comparison to the omnidirectional conditions. No significant improvement in SNR was measured between the two fitting algorithms. In addition, the Profile of Hearing Aid Benefit (PHAB) (Site I) and the Abbreviated Profile of Hearing Aid Benefit (APHAB) (Site II) were administered. Results revealed that the benefit scores for background noise and reduced cues (Site I) and background noise and aversiveness of sounds (Site II) were significantly higher than those reported in the established norms. Finally, 76 percent of the subjects of Site I reported that the experimental hearing aids provided "significantly better" or "better" performance than their current hearing aids.

Adult↗
PubMed1994

Effects of 1-year treatment with ipriflavone on bone in postmenopausal women with low bone mass.

Ipriflavone (IP) (7-isopropoxyisoflavone), a synthetic isoflavone derivative, is active in both inhibiting bone resorption and enhancing osteoblast function. This property suggested its clinical use in the treatment of involutional osteoporosis, and in the prevention of postmenopausal bone mass loss. Forty postmenopausal women with low bone mineral content were enrolled and randomly treated for 12 months with IP 600 mg/day or placebo (PL), according to a double-blind, parallel group design. All patients wee also given an oral calcium supplementation (1 g/day). Bone mineral density (BMD) was measured at the spine (L2-L4) by dual-energy X-ray absorptiometry and at the distal radius by single-photon absorptiometry. Bone metabolism markers (serum calcium, phosphate, osteocalcin, and alkaline phosphatase, and urinary calcium, phosphate, and hydroxyproline) were assessed at the same times. After 12 months, a reduction of BMD was evidenced in the PL-treated group, at both the spine (-2.2%, P < 0.01 vs baseline) and the forearm (-1.2%). In the IP-treated group, an increase of BMD was obtained (+1.2%, P < 0.01 vs placebo, at the spine; +3%, not significant, at the forearm). Bone markers were in the normal range for postmenopausal women; no statistically significant modifications were observed during the treatment period. Three patients were withdrawn from the treatment in the IP-treated group, and two in the PL-treated group for gastrointestinal disturbances. In the other women, the tolerance of the drug was good and the compliance with the oral treatment was excellent.

Absorptiometry, Photon↗