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Biomedical subjects

R Massa

Publications and source records attributed to R Massa.

At least 55 records · Page 3Linked to original sources
PubMed1998

[Computerized tomography, magnetic resonance, and nuclear medicine in the non-invasive diagnosis of focal nodular hyperplasia of the liver].

INTRODUCTION: Focal nodular hyperplasia (FNH) is a benign liver lesion requiring a prompt diagnosis and a conservative management. Aim of our study was to prospectively integrate enhanced CT, MRI, nuclear medicine in the noninvasive diagnosis of FNH. MATERIAL AND METHODS: 20 FNH lesions (diameter ranging 1.5-13 cm) in 18 asymptomatic patients were investigated with MRI and nuclear medicine. MRI examinations were performed with a 1.5 T superconducting system (Philiphs NT) by acquiring T1-weighted, T2-weighted, T2-weighted fat-suppressed Turbo Spin-Echo and dynamic MRI sequences, with breath-hold T1-weighted Turbo Field Echo and Gd-DTPA. Nuclear medicine included in all cases 99mTc sulfur colloid or 99mTc iminodiacetic acid studies. Diagnostic sensitivity of MRI was compared with that of nuclear medicine, and the sensitivity of the two modalities combined. The definitive diagnosis was made by percutaneous core-needle biopsy (12 lesions), surgery (2 lesions) and longterm follow-up (6 lesions). RESULTS: In 13 lesions larger than 3.5 cm typical findings, such as the central scar and homogeneous pattern, were observed in 9 cases (75%) with enhanced CT, in 10 cases (83%) with unenhanced MRI and in 11 cases (91%) after gadolinium injection. Hepatobiliary scintigraphy showed increased tracer uptake in delayed scans in 10/12 cases (83%) while sulfur colloid studies were diagnostic in 2/12 cases only (16%), showing the same tracer uptake than the surrounding liver parenchyma. In 7 lesions smaller than 3.5 cm, only 1 case showed typical findings; dynamic MRI showed typical early hypervascularity in 5 of the 6 remaining lesions (71%) which persisted on late images. In lesions smaller than 3.5 cm, sulfur colloid studies were diagnostic in 1/7 lesions (14%) and hepatobiliary scintigraphy in 3/7 lesions (42%). Considering all 20 lesions, MRI-nuclear medicine integration performed better than MRI alone. CONCLUSIONS: Enhanced MRI and biliary scintigraphy are important tools to make the final diagnosis of FNH. In small lesions both examinations should performed, but in large lesions MRI may be sufficient to make an unquestionable diagnosis, limiting hepatobiliary scintigraphy to questionable cases.

Contrast Media↗
PubMed1997

Non-thermal effects of microwaves on proteins: thermophilic enzymes as model system.

Two thermophilic and thermostable enzymes, isolated from Sulfolobus solfataricus, S-adenosylhomocysteine hydrolase and 5'-methylthioadenosine phosphorylase, were exposed to 10.4 GHz microwave radiation in order to discriminate between thermal and non-thermal microwave effects. The exposure causes a non-thermal, irreversible and time-dependent inactivation of both enzymes; the inactivation rate is related to the energy absorbed and is independent of the enzyme concentration. The influence of salts on enzyme inactivation has also been investigated. Conformational changes of S-adenosylhomocysteine hydrolase, detected by fluorescence and circular dichroism techniques, suggest that microwaves induce protein structural rearrangements not related to temperature.

Adenosylhomocysteinase↗
PubMed1997

The NADPH-diaphorase-containing system in the brain of the budgerigar (Melopsittacus undulatus).

In the present investigation we studied the presence and distribution of histochemically detected neuronal NADPH-diaphorase (ND) in the brain of the budgerigar, Melopsittacus undulatus. Positive neurons are widely distributed throughout the central nervous system. ND-containing neurons are present in the telencephalon and the paleostriatal-parolfactory lobe complex. Positive cells were observed also in the neostriatum, including the main auditory area (field L), in several nuclei of the archistriatum and in the hyperstriatum (accessory, dorsal, and ventral). In the diencephalon, positive neurons were present both in the lateral hypothalamic and periventricular areas, and in a segregate area at the confluence of the anterior commissure and the lateral prosencephalic bundle. A group of positive perikarya was located lateral to the dorsal part of the IIIrd ventricle, and continued laterally into the thalamus. Weakly stained neurons were observed in the thalamic dorsomedial posterior nucleus. In the mesencephalon, ND-containing neurons were scattered in the reticular formation (pars lateralis and pars medialis) and in the optic tecta. A large population of positive neurons was observed in the substantia nigra, the ventral area of Tsai and the nucleus interpeduncularis. Positive neurons extended through the tegmental nuclei to the locus coeruleus. In the cerebellum, the granular neurons were weakly stained and the internal cerebellar nuclei were surrounded by a wide network of positive fibers. In the medulla the number of positive cells was highly reduced, but stained neurons were observed in the cochlear as well in the vestibular nuclei. The data here presented suggest that the distribution of ND-containing neurons in the brain of the budgerigar is different from those of the chicken and quail. The locations of positive neurons suggest also a possible involvement in sound perception and production pathways, and visual perception.

Animals↗
PubMed1997

[Incidentaloma of the adrenal gland. A clinical case].

The case of a 58 years-old woman with incidental adrenal tumor without endocrinological features of Cushing's syndrome, dexamethasone nonsuppressible uptake of 131I-19 iodocholesterol on right adrenal gland, and no uptake of the left, is described. Right adrenalectomy was performed with the diagnosis of adrenal tumor. The histopathological study revealed that the mass was an adrenal adenoma composed of mixtures of clear and compact cells. Postoperative course was uneventful without replacement therapy with cortisol. This case report suggest that in patients with incidental adrenal tumor, the adrenocortical scintigraphy is very useful for the identification for autonomously functioning adrenal mass.

Adenocarcinoma, Clear Cell↗
PubMed1996

Partial block of glycolysis in late-onset phosphofructokinase deficiency myopathy.

A late-onset, myopathic variant of phosphofructokinase (PFK) deficiency has been previously described in two patients of Ashkenazic descent. We report here on a non-Ashkenazic woman with the onset, at the age of 48 years, of a progressive limb girdle myopathy that was not preceded by a history of exercise intolerance. Muscle biopsy findings at the age of 58 years showed deposition of amylopectin-like material in muscle fibers and the absence of histochemical PFK activity. Enzymatic PFK activity in vitro was only 4% of normal. Since the forearm ischemic exercise test induced a sub-normal production of serum lactate, the patient underwent phosphorus magnetic resonance spectroscopy (31P-MRS), a non-invasive method that allows in vivo assessment of the functional status of the glycolytic pathway and mitochondrial oxidative metabolism by measuring the high-energy phosphates and cytosolic pH. In vivo, 31P-MRS disclosed a residual glycolytic flux and a normal rate of ATP production both at rest and during exercise. These results suggest that, in some patients, muscle PFK deficiency may be partial in vivo, and more severe in vitro, possibly due to protein or mRNA instability rather than absence. The presence of these findings in a patient with the late-onset myopathic form is compatible with a distinct pathogenetic mechanism, relying on progressive polysaccharide accumulation, rather than on acute energetic shortage in muscle fibers.

Female↗
PubMed1996

Muscular uptake of Tc-99m MIBI and TI-201 in Duchenne muscular dystrophy.

Lack of dystrophin, a protein localized to the inner surface of the sarcolemma of the muscle fiber, is the cause of Duchenne type muscular dystrophy. Plasma membrane damage of the muscular fiber occurs, followed by Ca++ influx into the fibers. There is severe mitochondrial damage in dystrophic but still viable fibers. Five children aged 5-7 years were studied with MRI, TI-201, and Tc-99m sestamibi scintigraphy of the thighs. These three methods showed that the sartorius is the least damaged muscle in Duchenne type muscular dystrophy. MRI showed mild damage of adductors and quadriceps; TI-201 scintigraphy showed a marked reduction of radioactivity in the same muscles; Tc-99m sestamibi uptake occurred only in the sartorius muscle; the quadriceps was not imaged and adductors showed a faint image. A decrease of water in muscular fibers as well as fatty fibrous substitution, occurs after death of the fibers, whereas plasma membrane and mitochondrial damage reduced the uptake of tracers when the fiber is still viable. The interesting mismatch between sestamibi and TI-201 can be explained by considering that the cellular mechanism of uptake and retention of Tc-99m sestamibi involves both plasma membrane and mitochondria, whereas the uptake of TI-201 is only affected by plasma membrane damage.

Child↗
PubMed1996

NADPH-diaphorase neurons contacting the cerebrospinal fluid in the ventricles of rat brain.

Two populations of scattered neurons containing nitric oxide synthase activity were detected in the wall of the third and lateral cerebral ventricles of rat brain, using histochemistry for NADPH-diaphorase activity. One type was multipolar and lay supraependymally, with dendrites oriented in the plane of the ependymal layer. The second type was bipolar and was situated subependymally, with dendrites extending in opposite directions, either into the surrounding brain tissue or to the ventricular surface. Moreover, multipolar neurons, situated in the corpus callosum and in the subcortical white matter, had long varicose dendrites extending toward the roof of the lateral ventricles. As a result, numerous NADPH-diaphorase neurites spread out on the free surface of the ependymal layer in contact with the CSF. These observations raise the possibility that periventricular nitrergic neurons play an essential role in registering the composition of the CSF and in modulating subcortical cerebral blood flow. A further possibility is that supraependymal nitrergic neuronal processes are effectors regulating activity of ependymal cells.

Animals↗
PubMed1996

Meckel's diverticulum: imaging diagnosis.

Despite the availability and wide use of modern imaging techniques, the diagnosis of Meckel's diverticulum is difficult. The signs and symptoms vary from none to those of an acute abdomen or gastrointestinal bleeding. Findings on physical examination may be inconsistent because of the variable location of the diverticulum, and bleeding may occur with no appreciable physical findings. Finally, small diverticula are often concealed by overlying small-bowel loops on routine small-bowel barium studies. The purposes of this article are to review the use of available techniques for the imaging diagnosis of Meckel's diverticulum, to discuss the relative advantages and indications for the various procedures, and to emphasize the role each plays in specific clinical circumstances. The embryology, anatomy, and clinical presentation of Meckel's diverticulum are also briefly discussed.

Humans↗
PubMed1996

Plasma endothelin-1 levels in patients with aldosterone-producing adenoma and pheochromocytoma.

The aim of the study was to evaluate possible changes of plasma endothelin-1 levels (ET-1) in patients with hypertension secondary to primary aldosteronism and pheochromocytoma. We enrolled in the study: 12 patients affected by aldosterone-producing adenoma (5 M and 7 W; mean age 42.1 +/- 17.2 years); 8 patients with pheochromocytoma (5 M, 3 W; mean age 36.2 +/- 17.1 years); 15 patients with essential hypertension (9 M, 6 W; mean age 48.5 +/- 10 years). We also enrolled a normal control group (8 M, 12 W; mean age 34.2 +/- 11 years). The mean plasma ET-1 concentrations in patients with pheochromocytoma were significantly higher (23.9 +/- 5.2 pg/ml) than those in normal subjects (7.3 +/- 1.9 pg/ml), in patients with primary aldosteronism (12.1 +/- 3.8 pg/ml) and in patients with essential hypertension (9.2 +/- 3 pg/ml); p < 0.001, respectively. The present investigation demonstrates that in human adrenal hypertension patients with pheochromocytoma have increased circulating ET-1 levels respect to patients with aldosterone-producing adenoma.

Adenoma↗
PubMed1996

Ventilation-perfusion mismatching as prognostic factor of respiratory failure after pulmonary resection.

This paper reports the results of a retrospective study undertaken to assess the reliability of regional ventilation-perfusion pulmonary scanning in predicting the remaining respiratory function (pFEV1), and the early and long-term outcome of 33 patients with chronic airways disease, submitted to pulmonary resection at the 1st Department of Surgery. All patients had been diagnosed as resectable with the traditional tools and had a traditional pFEV1 (tpFEV1) greater than 800 ml. All pFEV1 were re-calculated (npFEV1) with our new formula which also includes as lost for function all lung areas not to be resected with V/Q mismatching. Normal perfusion and ventilation distribution was found in 24.2% of patients in the lesion area and in 33.3% in the remaining pulmonary areas. An impairment of perfusion was observed in the lesion area in 72.7% of patients, in the remaining areas in 48.4%. An impairment of ventilation was observed in the same regions in 66.6% and 48.5% of patients, respectively. Abnormality in ventilation/perfusion matching occurred in the lesion area in 15.2% of cases, in the ipsilateral lung areas in 18.2%, in the contralateral lung in 48.4% of cases. In predicting postoperative FEV1, and early and long-term mortality among our resectable patients, the tpFEV1 showed an accuracy of 91%, an index of resectability of 93.7%, of unresectability of 0%. Our npFEV1 reached an accuracy of 94.4%, an index of resectability of 100% and an index of unresectability of 66.7%.

Adolescent↗
PubMed1995

Immunocytochemical localization of vinculin in muscle and nerve.

A complete survey of the immunofluorescence distribution of the cytoskeletal protein vinculin in the normal skeletal muscle and peripheral nerve of humans and of different rodent species was performed. Our results enable us to localize vinculin in different types of adhesion plaques such as sarcolemmal costameres and neuromuscular and myotendinous junctions, but also in a fine intermyofibrillar lattice, possibly associated with intermediate filaments and/or with the triads. Moreover, we describe the presence of vinculin in junctional domains of several, previously unrecognized, specialized cells such as: the outer sheath of the muscle spindle capsule, the multilayered flat cells of the perineurium, the smooth muscle cells of epineurial blood vessels, and the endothelial cells in the endoneurium. These data call for a major role of vinculin in mechanisms of adhesion between cells, between cell and substrate and between intermyofibrillar components in the neuromuscular system. Such knowledge provides an anatomical background for studies on the possible pathological effects induced by an impairment in vinculin function.

Adult↗
PubMed1995

[Idiopathic ventricular tachycardia with onset in the verapamil-sensitive left ventricle: the clinical characteristics and long-term follow-up of 37 patients].

BACKGROUND: Idiopathic verapamil-responsive left ventricular tachycardia (IVRLVT) is a rare, well known form of ventricular tachycardia. Issues concerning long-term prognosis, drug prophylaxis and non-pharmacological therapy are rarely reported in the literature. We report the long-term follow-up, the efficacy of various drugs in the prophylaxis and the role of catheter ablation in a large group of patients with IVRLVT. METHODS AND RESULTS: This retrospective study involves 37 patients with a mean age of 28.3 +/- 14.8 years at first IVRLVT episode. The tachycardia morphology was typically with a right bundle-branch block configuration in all cases, with left axis deviation in 33 and right axis deviation in 5 (one patient had the 2 morphologies). Four patients had a mitral valve prolapse; the remaining 33 patients had neither clinical nor echocardiographic signs of heart disease. Only sporadic ventricular extrasystoles were detected at Holter monitoring in 73% of cases; 30% of patients had positive criteria for the presence of late potentials at signal averaged ECG. During electrophysiologic study, the tachycardia could be easily induced in 91% of patients. Mean follow-up is 7.3 +/- 4.7 years; all patients are alive at the end of follow-up. A mean of 2.3 +/- 1.2 drugs was prescribed in 35 patients (94.6%); betablockers were effective in 66% of the cases, verapamil in 20%, class I drugs in 22%, class III drugs in 15%. Both the 2 patients, who never received prophylaxis, and the 4 who stopped medication, utilize verapamil in case of recurrences. Eight patients were submitted to catheter ablation, with DC shock the first 2 patients, with RF energy from the third on; all but one (with DC shock) were successfully cured. CONCLUSIONS: Long-term follow-up confirmed the good prognosis of this form of ventricular tachycardia; a new insight that has been addressed about prophylaxis is the high efficacy of betablockers in preventing relapse and the poor efficacy of verapamil per os in chronic prophylaxis. Radiofrequency catheter ablation is effective and safe, using the earliest ventricular potential and the pace-mapping reproducing the same morphology of the tachycardia in all the 12 leads as a marker to identify the site of RF application, and may be proposed to all patients suffering from frequent episodes of IVRLVT.

Adolescent↗
PubMed1994

Dystrophin is not essential for the integrity of the cytoskeleton.

Dystrophin is localized, in normal muscle fibers, on the cytoplasmic surface of the sarcolemma. The function of this protein is not known but, according to its structure and intracellular distribution, it seems likely that dystrophin interacts with other cytoskeletal proteins to form a complex linkage between myofibrils, sarcolemma and extracellular matrix. To evaluate the possibility that dystrophin deficiency induces, per se, a disarray in the cytoskeleton, we studied three components of this structure in muscle fibers of the dystrophic mdx mouse in a phase preceding the onset of necrosis. Vinculin, abundant in sarcolemmal structures called costameres, desmin, the principal component of intermediate filaments and nebulin, constituent of the so-called "third filament" within the sarcomere, were stained with the indirect immunofluorescence technique in cryostat sections. The same monoclonal antibodies were used in Western blots of proteins extracted from the same muscles. No difference was observed in the distribution or in the relative abundance of the three proteins, comparing muscles from 18 day-old mdx and control mice. Our results indicate that the lack of dystrophin does not induce, per se, alterations in the structures linking the sarcolemma to the contractile apparatus. It is likely that the structural damage in dystrophin-less muscle fibers is initially confined to limited portions of the plasma membrane. These focal lesions, impairing intracellular calcium homeostasis, can lead to muscle fiber necrosis.

Animals↗
PubMed1993

NADPH diaphorase activity is inhibited by EDTA in neurons but not in choroid plexus epithelium.

NADPH diaphorase histochemical staining was investigated in rat brain and choroid plexuses. All epithelial cells of the latter as well as some sparse neurons in striatum and cerebral cortex showed strong NADPH reaction product. While staining was homogeneous in neuronal cytoplasm, it was particulate in epithelial cells. Preincubation with EDTA (0.1 mM, 2h) prevented appearance of NADPH diaphorase reaction in neurons but not in choroid plexuses. These data show that in rat brain two forms of NADPH diaphorase are present; they are specifically localized in neurons and choroidal cells, respectively.

Animals↗
PubMed1993

Photoperiodic adaptation to breeding at different latitudes in great tits.

The photoperiodic responses in testicular growth and plasma levels of LH in nonmigratory great tits from Tromsö, Norway (69 degrees 40'N), Göteborg, Sweden (57 degrees 42'N), and Milano, Italy (45 degrees 26'N) were compared under the same lighting conditions. Male great tits, collected during midwinter, were transferred to Göteborg, and shifted from an 8-hr day in early January to a lighting regime in which day length was increased by 1/2 hr per week for 16 weeks. Control birds (only from Sweden) were kept on a 8L:16D light regime during the entire study. Blood samples were collected weekly, and laparotomies were performed every other week. Initially testicular size (approximately 1.6 mm) and plasma levels of LH (approximately 0.45 ng/ml) were similar among the four groups. Between 4 and 8 weeks after the onset of the experiment testes gradually, but significantly, increased to about 2 mm in length in the control group. This slow growth was also observed in the experimental groups. The control bird testes did not increase in size any further. The onset of the rapid testicular growth phase differed among the three experimental groups. In great tits from Milano it began when day length exceeded 11 hr; in birds from Tromsö, when day length was greater than 12 hr; and in great tits from Göteborg, when day length was between 11 and 12 hr. Once the rapid gonadal growth phase had begun it took about 6 weeks for the testes to reach maximal size (approximately 6.8 mm) in all three populations.(ABSTRACT TRUNCATED AT 250 WORDS)

Acclimatization↗
PubMed1993

Mate choice and reproductive success in the red-legged partridge (Alectoris rufa).

Behavioral patterns, reproductive success, and concentrations of plasma-luteinizing hormone, testosterone, and estrogen were compared in pairs of red-legged partridges which had either selected their own mates or had been randomly paired. Males in self-selected pairs called more frequently than males in non-self-selected pairs. Females in self-selected pairs but not those in non-self-selected pairs guarded their nests. Females in self-selected pairs had a greater egg production and laid more of their eggs in nests than females in non-self-selected pairs. There was a significant difference between the two groups in the concentration of plasma testosterone in males, which was higher in males from self-selected pairs prior to the onset of egg laying. These results are consistent with the hypothesis that mate choice affects both reproductive parameters and nest defense in monogamous birds.

Animals↗
PubMed1993

Sudomotor skin responses to brain stimulation do not depend on nerve sensory fiber functionality.

Evaluation of sudomotor innervation to the limbs was performed via electrical stimulation of the median nerve at the wrist and transcranial magnetic stimulation of the brain. Sympathetic skin responses (SSRs) from the palms and the soles were recorded in a patient suffering from a form of predominantly sensory neuropathy. Motor responses to nerve stimulation were present, even if with slower than normal conduction velocity. However, median, ulnar and sural nerve sensory potentials were absent. SSRs to median nerve stimulation at the wrist were missing on palms and soles. By contrast, during brain stimulation of the hand motor area with magnetic impulses, SSRs were reliably identifiable at all recording sites. It is hypothesized that SSRs to mixed nerve stimulation need normal functionality of afferent fibers, while those to brain stimulation can be elicited without any sensory information from the limbs.

Brain↗