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Biomedical subjects

C Marchetti

Publications and source records attributed to C Marchetti.

At least 73 records · Page 4Linked to original sources
PubMed1986

Cytoplasmic bodies in lymphatic endothelial cell.

Although micropinocytotic vesicles and other large vesicular structures have been observed in lymphatic endothelial cells on electron microscopy, in this study ultrastructure attention was focused on a variety of other membrane-bounded structures in the cytoplasm of these cells in the rabbit heart. The first type was oval or round in transverse section and elongated in longitudinal section, was 100-200 nm in diameter and contained regularly spaced tubules. These features resembled rod-shaped bodies detected thus far only in blood vascular endothelial cells. A second type of cytoplasmic body was also frequently seen in lymphatic endothelium. It contained irregularly spaced small vesicles, 5-7 in number and 45 nm in diameter. A third type of vesiculated body was only occasionally found. This latter structure was greater than the previously described bodies and ranged from 3-5 micron in diameter, and filled with granular, inhomogeneous material and filamentous-like components. The functional significance of these intraendothelial bodies is as yet unexplained.

Animals↗
PubMed1986

Lymph vessels of the heart. A comparative study of various techniques for light and electron microscopy.

This investigation was carried out in order to find out which was the best technique, among those reported in the literature, to recognize the small lymph vessels by light microscopy, while at the same time allowing a good ultrastructural preservation of tissues. The study was performed with rabbit hearts according to the following methods: (1) injection of India ink into the wall of the heart followed by perfusion with aldehyde fixative; (2) injection of India ink into the wall of the heart followed by immersion in aldehyde fixative; (3) treatment of the animals with histamine dihydrochloride by e.v. route and aldehyde (4) fixation by immersion; (5) fixation by immersion in osmium tetroxide fixative; fixation by immersion in aldehyde fixative; (6) fixation by perfusion with the same mixture as in (5). In cases (1), (2), (3), (5), and (6), the tissue specimens were postfixed in osmium tetroxide according to conventional methods. The validity of the different methods was checked by examining semithin sections of varying thickness at the light microscope and ultrathin sections at the transmission electron microscope. A comparative examination of the preparation showed that the method allowing the promptest recognition of the small lymph vessels, together with the best ultrastructural preservation and a good reproducibility of results was perfusion of the coronary circle.

Animals↗
PubMed1985

Stereotactic radiosurgery utilizing a linear accelerator.

The authors have developed a radiosurgical technique based on multiple arc irradiations. The target is fixed to the rotational isocenter of a Varian 4 MV linear accelerator. The first irradiation is carried out while the radiating source is rotating on a 100-140 degrees arc. The patient is then rotated around a vertical axis passing through the target, and arc irradiations are repeated in different angular positions. By this technique it is possible to obtain very steep dose gradients at the borders of the target volume. High doses are usually delivered in two shots. 47 patients have been treated so far in a clinical trial that started in November 1982. The paper deals with the preliminary results (more than 6 months' follow-up) obtained in patients affected by nonresectable brain tumors and AVMs.

Adolescent↗
PubMed1985

External stereotactic irradiation by linear accelerator.

Stereotactic radiotherapy has two advantages: (a) the possibility of giving high radiation doses to small but spatially well-defined target volumes and (b) the presence of a stepped dose gradient between the target volume and the surrounding healthy tissues. To utilize these advantages, the authors built a new stereotactic head frame by which the intracranial target is fixed to the rotational isocenter of a 4-MV linear accelerator. The collimator openings are selected according to the volume and the three-dimensional configuration of the target, and the radiation dose is based on the radiosensitivity of the lesion. After the patient is fixed to the frame, the radiation source and the patient are rotated so that the target is irradiated through infinite portals distributed over the convexity of the skull. It is thereby possible to obtain very high radiation doses centered into the target with a stepped dose gradient. The preliminary radiodosimetric tests and the operative technique are described. The advantages of this technique compared to interstitial radiotherapy and Leksell's radiosurgery are emphasized. This noninvasive procedure has been used to treat a series of intracranial tumors.

Adolescent↗
PubMed1985

Lymph vessels of the rabbit heart: distribution and fine structure in ventricles.

We examined the distribution and fine morphology of small lymph channels in the rabbit heart, and particularly in the ventricular myocardium. Light microscopy showed many small subendocardial lymphatics in both ventricles and especially in the subendocardium of papillary muscles and right side of the septum. Electron microscopy revealed that the endothelial ultrastructure of these lymphatics was similar at different sites. The cytoplasm exhibited frequent adluminal expansions and contained numerous micropinocytotic vesicles opening both into the lumen and surrounding interstitium. Bundles of microfilaments, commonly arranged in a parallel fashion, were also visible. Between laminations of the endothelial wall were relatively dense, finely granular material. Intercellular contacts were characterized by cell superimpositions and interlockings, specialized junctions and occasionally maculae adherentes. The basal membrane was discontinuous and often of variable thickness. In the surrounding connective tissue, thin filaments appeared adjacent to the abluminal surface of the endothelial wall. Although the fine structure of the walls of small lymphatics in the rabbit ventricular myocardium was similar to that of small lymphatics at other sites, their distribution varied from other mammalian species.

Animals↗
PubMed1984

GM1 micelles modify the transport properties of the ionophore gramicidin D in artificial planar bilayers.

We have analyzed the effects induced in different phospholipid planar bilayers by monosialoganglioside micelles containing the ionophore gramicidin D. The membrane conductance increases after the addition of GM1 micelles at various ionophore/ganglioside ratios. We believe this fact may be ascribed to gramicidin molecules that incorporate into the bilayer together with gangliosides. In the presence of micelles the mean lifetime and the amplitude of the gramicidin single channel did not present relevant modifications when dioleoylphosphatidylcholine or phosphatidylserine were used to form the bilayer. Calcium proved to trigger the interaction between phosphatidylethanolamine membranes and GM1 micelles containing gramicidin. In this case the ionic pore presents a longer lifetime and a lower amplitude with respect to pure gramicidin. We suggest that different properties developed by gramicidin may depend on structural organization of gangliosides when incorporated into the phospholipid bilayer.

Biophysical Phenomena↗
PubMed1977

A case of progressive external ophthalmoplegia (Kiloh-Nevin type) with abnormal mitochondria. Clinical, histochemical and ultrastructural findings.

A case of progressive external ophthalmoplegia is described, in which the onset of the illness was at 28--30 years, with fatigability and muscular pains in the lower limbs as presenting symptoms. At 36--37 years weakness of the mimic muscles also appeared and fatigability and muscular pains spread to the upper limbs: EMG examination showed signs of light myopathic involvement of the shoulder-girdle muscles, so that a muscular biopsy was performed (right deltoid). Histoenzymologic studies showed the presence of generally atrophic dark fibres, which can be brought about to red-ragged fibres. Ultrastructural study showed bizarrely shaped mitochondria, with dense matrix and circular and confluent cristae, which were found in fibres with plenty of indifferent sarcoplasm and with anomalies in myofibrils. No mitochondrial inclusions were seen.

Adult↗
PubMed1977

Mitochondrial abnormalities in some human muscular diseases and in experimental ischemic myopathy.

Morphologic abnormalities have been observed in two cases of human polymyositis and in three cases of ocular myopathies. Similar findings can be observed in experimental ischemic myopathy. "Ragged red" fibres, with anomalous distribution of oxidative enzymes, mitochondrial alterations, with presence of intracristal paracrystalline inclusions and degenerative myofibrillar changes are the similar features. The similarity between some of these alterations, expecially mitochondrial changes, is remarkable, but it is difficult to correlate them to the primary etiology of described human myopathies.

Adult↗
PubMedDate not supplied

Morphometric computerized analysis on the dentinal tubules and the collagen fibers in the dentine of human permanent teeth.

A morphometric analysis has been performed on important components of human dentine using an image computerized analyzer. The dentinal tubule diameter and their area percentage were calculated. Moreover the area percentage of the collagen fibers in the dentinal matrix was measured. These parameters have been evaluated in different areas of the coronal and the radicular dentine in permanent teeth. Measurements have been performed on undecalcified and decalcified teeth and on teeth treated with enzymatic digestion to remove the organic non collagen matrix and to evidentiate the collagen fiber network. The values obtained in different areas of the tooth and in samples submitted to different treatments were evaluated by statistical analysis. Dentinal tubule diameter and area percentage significatively decrease from the inner to the peripheral dentine both in the undecalcified teeth as in the decalcified ones and in the samples undergone to enzymatic digestion. The collagen fiber percentage in the organic matrix is significatively lower in the mantle dentine.

Adult↗
PubMedDate not supplied

[Light and electron microscopy observations on different tissues of a complex odontoma].

Several aggregates of dental tissues constitute the complex odontoma. They are almost completely covered by a layer of prismatic enamel. By the observations at transmission and scanning electron microscope enamel present the characteristics of a not fully developed tissue. The organic component is still abundant and the enamel surface is covered by a cellular layer having the morphological features of the mature ameloblasts. Therefore this enamel results to be yet actively engaged in the maturation phase although the tissues of the odontoma have generally a limited developing time.

Adolescent↗
PubMedDate not supplied

[Prevalence and clinical meaning of insulin-specific IgE antibodies].

Systemic and local reactions to insulins in patients affected by insulin-dependent diabetes are uncommon but may be life threatening. Both systemic and local adverse reactions to therapy may be managed by different therapeutic schemes. The availability of human (DNA recombinant) insulin raised hopes that this be the choice treatment for allergic complications. However, controlled studies showed that reaginic (IgE) antibodies are directed to common insulin determinants and not to heterologus protein contaminants. Therefore we investigated in 62 patients undergoing insulin therapy, prevalence and clinical significance of the detection of specific IgE to insulin. Furthermore, we searched for a relationship between atopic status and the presence of antiinsulin IgE. In our study prevalence of specific IgE to insulin was 16.1%. We showed a correlation between clinical symptoms and the presence of specific IgE to insulin, when these antibodies are of an elevated class (R.A.S.T. class 2 or more). When specific IgE were present we detected antibodies to all insulines (bovine, porcine and human) thus confirming that specific IgE are directed to a common antigenic determinant. Finally, we couldn't find a relationship between atopic status and the presence of reaginic antibodies to insulin.

Aged↗
PubMedDate not supplied

Lymphatic vessels in inflamed human dental pulp.

Investigation has been performed on both the light and electron microscopic characteristics of the lymphatic vessels present in the dental pulp of human teeth which have been affected by serious carious lesions. These conditions provoke a severe inflammatory response resulting in structural and functional modifications of the tissue; increase of the tissue pressure is followed by the need for a more intensive lymphatic drainage. In the inflamed pulps, dilated lymphatic vessels with distended walls and "open junctions" between endothelial cells are detectable. On the other hand they lack certain endothelial structures which characterize the morphology of these vessels under normal conditions. In the pulpal regions affected by fibrotic proliferation shrunken vessels with irregular profiles are present. From these observations it is possible to obtain other information on the mechanisms regulating the lymphatic drainage in different structural and functional conditions of the interstitium.

Dental Pulp↗
PubMedDate not supplied

A retrospective analysis concerning physical aspects and clinical dosimetry in radiosurgery.

The authors have reviewed their experience with treatments of small intracranial lesions by unconventionally fractionated stereotactic radiotherapy using a 4 MV photon beam. Treatment is carried out by multiple non coplanar arc irradiation obtained rotating the target, while kept at the isocentre of a Linac, around a vertical axis. The outmost concentration of the dose within the target volume enables consistent reduction of the amount of the absorbed dose by critical structures of the intact brain. They analyse the dose distribution and the method to optimise the choice of the therapeutic dose. Finally, some radiobiological considerations are presented.

Humans↗
PubMedDate not supplied

[Pre- and postoperative radiotherapy of oral carcinoma of a locally advanced stage. An analysis of the results and complications].

The combination of radiotherapy and surgery in the treatment of advanced oral carcinoma (T3 and T4 lesions) yields good possibilities of recovery; whether radiotherapy should be given before or after surgery is still debated. Fifty patients with advanced oral carcinomas were analyzed: 24 of them were irradiated before and 26 after surgery; doses ranged from 40 to 56 Gy for the first group of patients, and from 50 to 68 Gy for the second one. The disease-free survival 48 months after the diagnosis was 36% in patients who received preoperative irradiation, and 53.6% in patients who received postoperative radiotherapy; the latter allowed local control of the disease to be significantly improved (chi 2 3.99, 0.01 less than p less than 0.05). The quality of survival was worse in the group receiving preoperative irradiation, because of radiation-induced surgical complications, which were especially observed in patients with diffuse disease. Our findings suggest that postoperative radiotherapy may be advisable if the tumor is resectable, since tolerance and local control rate were acceptable. On the contrary, nearly inoperable masses and massive neck diseases often require preoperative irradiation.

Adult↗