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Biomedical subjects

G Arcidiacono

Publications and source records attributed to G Arcidiacono.

At least 19 recordsLinked to original sources
PubMed2004

Functional analysis of bioprosthetic heart valves.

Glutaraldehyde-treated bovine pericardium is used successfully as bioprosthetic material in the manufacturing of heart valves leaflets. The mechanical properties of bovine pericardial aortic valve leaflets seem to influence its mechanical behaviour and the failure mechanisms. In this study the effect of orthotropy on tricuspid bioprosthetic aortic valve was analysed, using a three-dimensional finite element model, during the entire cardiac cycle. Multiaxial tensile tests were also performed to determine the anisotropy of pericardium. Seven different models of the same valve were analysed using different values of mechanical characteristics from one leaflet to another, considering pericardium as an orthotropic material. The results showed that even a small difference between values along the two axes of orthotropy can negatively influence leaflets performance as regard both displacement and stress distribution. Leaflets of bovine pericardium bioprostheses could be manufactured to be similar to natural human heart valves reproducing their well-known anisotropy. In this way it could be possible to improve the manufacturing process, durability and function of pericardial bioprosthetic valves.

Animals↗
PubMed2002

[Echocardiographic evaluation of coronary flow reserve in patients with essential hypertension].

BACKGROUND: In patients with essential arterial hypertension (EAH) the left heart ventricular hypertrophy (LVH) causes structural and functional alterations of the coronary vessels that can alter the coronary blood flow reserve. The aim of this study is to evaluate in hypertensive patients with or without LVH versus normotensive subjects, the blood flow and the coronary vasodilatation capability and the coronary blood flow reserve in basal conditions and during dipiridamole i.v. infusion. METHODS: Eighty patients have been selected by ECG, echo color Doppler, transesophageal echocardiography: 50 were hypertensive patients with and without LVH, from mild to moderate to severe and 30 were normotensive subjects. The enrolled patients underwent a first transesophageal echocardiography, before and during infusion of 0.86 mg/kg of dipiridamole in growing doses, 0.56 in four minutes followed after three minutes by 0.30 mg/kg. The observation lasted 18 months, and no patients left the study. RESULTS: The coronary resistances in hypertensive patients were significintally reduced during dipiridamole infusion, maintaining their level higher compared to the normal controls. The reduced coronary vasodilatation capability in hypertensive subjects could be due to an increase of the basal vessel tone and/or a reduced compliance of the coronary resistances. The coronary blood flow reserve is significantly reduced in all hypertensive studied, included those without LVH. It is suggested that this is secondary to increase of the coronary blood flow and tone. CONCLUSIONS: In conclusion essential arterial hypertension is the cause of early anatomical and functional coronary alterations leading hypertensive subjects to risk for coronary events before LVH.

Coronary Circulation↗
PubMed1997

[Solitary primary cerebral echinococcosis. Report of a case].

INTRODUCTION AND AIMS: Echinococcosis is a widespread parasitic disease caused by Echinococcus granulosus. Hydatid cysts are mainly diagnosed in adults except for primary cerebral localisation which is electively observed in childhood owing to the early manifestation of signs and/or symptoms of the space-occupying mass. In July 1995 P.N., a 55-year-old woman, was referred to our attention. She complained of intense asthenia, cephalea not responding to NSAIDs and paroxysms of tremor. RESULTS: The anamnesis revealed close relationships with dogs since infancy and an attack of pleurisy of unknown etiology. The objective examination was negative except for an increased volume of the right-hand thyroid lobe. Hematochemical tests showed relative eosinophilia, a significant positivity of anti-thyroglobulin antibodies and antiperoxidase with normal thyroid function indices. Thyroid scan showed a multinodular goitre. Confirmation of eosinophilia suggested the performance of a parasitological examination of feces with negative results. ECG and EEG were normal. Persistent cephalea led to the performance of an encephalic CAT which revealed a cystic formation in the rolandic region, subsequently confirmed by encephalic MNR. The positivity of the Ghedini-Weinberg test led to the diagnosis of cerebral echinococcosis. Chest X-ray and hepatic scan excluded hydatid localisation in these organs. CONCLUSIONS: The case was diagnosed as solitary primary cerebral echinococcosis. Medical follow-up was commenced with albendazole for six months, after which a control encephalic CAT showed the unchanged size of the cysts. The patient consequently underwent surgical exeresis.

Brain Diseases↗
PubMed1997

Cell body volume of spinal ganglion neurons: estimation by three different methods.

We estimated the mean volumes of two series of nerve cell bodies, one from rabbit and one from rat spinal ganglia by three different methods: a procedure we devised 25 years ago (the circle-fitting method), one of the new stereological methods (the nucleator method) and the method of serial sectioning--the most direct and accurate procedure presently available for estimating cell size. In the case of the rabbit, in which most spinal ganglion neurons have a single nucleolus, the mean volumes estimated by the first two methods are closely similar and deviate by less than 2% from the mean obtained by serial sectioning. In the case of the rat, in which approximately half of the spinal ganglion neurons have more than one nucleolus, the mean volumes estimated by the first two methods are again closely similar, but deviate by about 12% from the mean obtained by serial sectioning. These findings show that: a) both the nucleator method and the circle-fitting procedure are more accurate when applied to neurons with a single nucleolus; b) if certain conditions are respected, not all the methods previously used to estimate cell size give biased results. However, the new stereological procedures are easier and quicker to use than the earlier methods. These findings also show that our previous results obtained by the circle-fitting method are to be considered valid.

Animals↗
PubMed1996

[Angiodysplasia of the right colon and aortic stenosis. A case report].

We report the case of a female patient who came to our observation for a severe enterorrhage. Following colonoscopic examination and color-Doppler M-B Mode echocardiography we made the following diagnosis: "angiodysplasia of the right colon in females with aortic stenosis". It was possible to ascertain whether there were similar lesions in other parts of the gastro-intestinal tract because the patient opposed firmly. In agreement with other authors, we believe that colonoscopic examination is the appropriate method to diagnose gastro-intestinal angiodysplasia. The advanced age and the clinical conditions of the patient did not allow surgical treatment, so we treated her with antihaemorrhagic drugs and elevated doses of ascorbic acid (4 g/die). The disappearance of enterorrhagies, the rapid clinical recovery and the normalization of red blood cell (RBC) count allowed us to discontinue antihaemorrhagic treatment and to continue the administration of elevated doses of ascorbic acid. Eight days later, the patient was discharged in good clinical condition and ascorbic acid was prescribed to be continued at home. A good clinical and haemodynamic balance was observed at the six-month follow-up. In conclusion we think that the clinical case we observed, characterized by the association angiodysplasia of the right colon-aortic stenosis, may be included in the diction Heyde's syndrome. In aging patients with severe concomitant diseases, ineligible for surgical interventions, the enterorrhage caused by a non complicated angiodysplastic lesion of the gastro-intestinal tract may benefit from the acute administration of ascorbic acid as the therapeutic agent of first choice capable to loose and/or stop the haemorragic complication and, in chronic administration, to reduce the number of relapses.

Aged↗
PubMed1995

[Role of MB-mode transthoracic echography in the early diagnosis of acute pulmonary embolism].

The aim of the present study was to evaluate whether transthoracic ecocardiography M-B mode was a sensitive and/or specific test for the early diagnosis of acute pulmonary embolism (PEA). For this purpose, we studied 7 patients with PEA as a complication of: deep leg venous thrombosis (3 cases), complicated bone fractures (2 cases), meniscectomy (1 case) and postpartum (1 case). The patients (3 males and 4 females), mean age of 46 +/- 7 years, did not have any previous earlier heart and/or pulmonary diseases. The diagnosis of PEA was made on the basis of clinical criteria, ecg and laboratory tests. Ecocardiography was performed using an IREX 3 M-B mode equipment; the measurements for the calculation of the indexes were made utilizing a short axis parasternal window. The parameters studied were: RVEDD/LVEDD ratio, LVDI Okubo index and the TR grade. Data were analyzed employing the paired Student's t test. In all patients was observed a statistically significant enlargement on the right heart cavities; while only in 3 of them was it possible to observe a slight reduction of the left ventricular cavities. In conclusion, the ecocardiographic exam was is a sensitive test for the diagnosis of PEA. Particularly, the RVEDD/LVEDD ratio gave an early and quantitative indication of the obstruction severity. Indeed, the morphological alteration of the right cavities became evident when the embolic obstruction was of at least 30%. Hence, we suggest that the standard ecocardiography M-B. mode may be regarded has a rapid diagnostic tool for the diagnosis of PEA.

Acute Disease↗
PubMed1994

Perikaryal projections of spinal ganglion neurons: quantitative differences between membrane domains in contact with different microenvironments.

The perikarya of spinal ganglion neurons display numerous slender projections. In the present investigation we have studied whether the extent of these projections is uniform over the entire perikaryal surface or whether there is a difference between the regions of the perikaryon in contact with different microenvironments. In spinal ganglia of the rat and the lizard we have analysed about 200 neuronal cell bodies arranged in pairs and have compared the extent of the projections quantitatively in the areas of interneuronal contact with that in the areas of neuron-to-satellite cell contact. In both species we have found that the projections are present over the entire perikaryal surface and that the overall development of the perikaryal projections is significantly greater in those portions of the surface in contact with satellite cells than in the portions in contact with another neuron. On the basis of these observations we conclude that the outgrowth of perikaryal projections is an intrinsic property of the nerve cell body which is manifested over the entire perikaryal surface; there is, however, an extrinsic influence from the microenvironment of the neuron, which may account for the quantitative differences in different domains of the perikaryal surface.

Animals↗
PubMed1994

Immunohistochemical study of placental endothelium in physiologic and gestosis-complicated pregnancies.

In this study we examined the placentae of gestosic patients and controls, with immunoistochemical method and HLA-DR monoclonal antibody, in order to show the role of placental endothelium in gestosic pathology onset. Our results show a marked expression of class II histocompatibility antigens in gestosic placentae with respect to controls. We suppose, in gestosic patients, a role for a particular, genetically determined HLA haplotype which increases disease receptivity.

Endothelium↗
PubMed1991

Clusters of nerve cell bodies enclosed within a common connective tissue envelope in the spinal ganglia of the lizard and rat.

A careful search for groups of nerve cell bodies enclosed within a common connective envelope was made in the spinal ganglia of the lizard and rat using a serial-section technique. Nerve cell bodies sharing a common connective envelope were found to be more common in the lizard (9.4%) than in the rat (5.6%). These nerve cell bodies were arranged in pairs, or, less frequently, in groups of three. At times, they appeared to be in immediate contact, with no intervening satellite cells; at others, they remained separated from one another by a satellite cell sheet. The clusters of nerve cell bodies enclosed within a common connective envelope probably result from the arrest of developmental processes in the spinal ganglion. It is possible that, as a result of the cell arrangement here described, certain neurons electrically influence other sensory neurons at the level of the ganglion.

Animals↗
PubMed1989

Internodal microvilli of Schwann cells of myelinated fibres in lizard spinal roots project onto unmyelinated axons.

Tufts of microvilli originating from the internodal cytoplasm of Schwann cells associated with myelinated axons in apparently normal lizard spinal roots have been studied under the electron microscope by means of both single and serial sections. More than one tuft of internodal microvilli may arise from a single Schwann cell. Sometimes mitochondria and more frequently an organelle resembling a multivesicular body with a clear matrix can be found in the Schwann cell cytoplasm underlying a tuft of internodal microvilli. The dimensions (length: 0.4-1.0 microns; diameter: 40-70 nm) and structure of internodal microvilli of the Schwann cell are very similar to those of nodal microvilli of the same cell. Each tuft of internodal microvilli projects towards an adjacent unmyelinated axon which at this site is partly devoid of its own Schwann cell sheath. Thus a single Schwann cell may be related to a myelinated axon and an unmyelinated axon at the same time. Patches of a dense axolemmal undercoating (which could be portions of the cytoskeleton) are present in the unmyelinated axon in close spatial correlation with internodal microvilli. The factors which could induce the formation of internodal microvilli as well as the possible role (or roles) of these microvilli are briefly discussed.

Animals↗
PubMed1988

Qualitative and quantitative observations on the structure of the Schwann cells in myelinated fibres.

Various morphological features of the Schwann cells of myelinated fibres in the lizard thoracic spinal roots were studied, and, when possible, quantified using morphometric methods. About 0.8% of the Schwann cells are binucleate and some display clusters of microvilli along the internodes. The percentages of the cytoplasmic area of the Schwann cell occupied by the following cytoplasmic components were determined: mitochondria, Golgi apparatus, granular endoplasmic reticulum, smooth endoplasmic reticulum, multivesicular bodies, dense bodies, autophagic vacuoles, peroxisome-like bodies, lipofuscin granules and lipid droplets. Linear relationships were found between the sectional areas of the mitochondria and granular endoplasmic reticulum of the Schwann cell and both the length of the profile of the Schwann cell plasma membrane and the size of the related axon. The results obtained are compatible both with the hypothesis that the mitochondria and granular endoplasmic reticulum of the Schwann cell are involved in the production and storage of proteins for the plasma membrane of this cell, and with the hypothesis that these organelles are involved in the production and storage of protein metabolites which are subsequently transferred to the related axons.

Animals↗