Biomedical subjects

C Marchetti

Publications and source records attributed to C Marchetti.

At least 19 recordsLinked to original sources

PubMed1992

Lymphatic vessels of the human dental pulp in different conditions.

The characteristics of the lymphatic vessel endothelial wall have been investigated in human normal and inflamed dental pulps. In normal pulps the endothelial wall is characterized by the presence of micropinocytotic vesicles and intraparietal channels. In the inflamed pulpal tissue, where an increase in interstitial fluid pressure occurs, the distended endothelial wall presents open junctions between endothelial cells and the openings of the intraparietal channels. Moreover the micropinocytotic vesicles disappear. The cytoplasm of the endothelial cells is characterized by the presence of numerous Weibel-Palade bodies, which increase in number in the dilated vessels. In the fibrillar apparatus surrounding the lymphatic vessel wall collagen fibrils are the prevalent component, while elastic fibers are not present. The different morphological properties of the lymphatic vessels are compared and discussed with regard to the variation of the functional conditions of the tissue.

Adult↗

PubMed1992

Dermal lymphatics in myotonic dystrophy.

Myotonic dystrophy is an hereditary disorder of several organ systems. Skeletal muscle is a principal target organ, but abnormalities also occur in the peripheral microcirculation. Because morphological and functional changes in the dermal blood microcirculation may affect interstitial fluid drainage of the skin, we examined dermal lymphatic morphology in adult patients with myotonic dystrophy. Skin biopsies were taken from the big toe from patients with myotonic dystrophy (age 18-50 years) and subjected to light and electron microscopy; five healthy subjects served as controls. The salient findings in myotonic dystrophy were ultrastructural changes of the lymphatic endothelial cells and the fibrillar elements that surround the lymphatic wall. These abnormal lymphatic findings are interpreted in light of changes in the blood microvasculature and loose connective tissue in this disorder.

Adolescent↗

PubMed1991

The Istituto Rizzoli-Beretta experience with osteosarcoma of the jaw.

Twenty-eight osteosarcomas (OS) of the jaw were reported. There were 15 male and 13 female patients (age range, 9 to 68 years; mean, 36.9 years); 57.1% of the patients were older than 30 years of age. Swelling was the most frequent symptom; it was reported on an average of 6 months before diagnosis. Most of the tumors of the maxilla (eight patients) occurred in the alveolar ridge (six of eight). In the mandible (20 patients), the body was the preferred site (11 of 20). Radiographically most of the lesions were either lytic and sclerotic or only lytic. Histologically, 12 cases (42.9%) were osteoblastic osteosarcoma, ten (35.8%) were chondroblastic, four (14.3%) were fibroblastic, and two (7%) were round cell OS. Of the 28 cases, three (10.7%) were low grade, and 25 (89.3%) were high grade. Thirteen patients had intralesional surgery, and 13 had marginal surgery as their initial treatment. Recurrence was the rule in the first group, and it was 69% in the second group. Twenty patients (71%) died, and eight are alive. Of these, two are alive with disease. In the six patients who are alive and disease-free, all but one had marginal to wide surgical margins at the time of the first procedure or wide margins at the time of the recurrences along with chemotherapy or radiation therapy. In the patient in which the surgical margins were marginal, the lesion was small 2.5 X 2 cm. This patient was alive without evidence of disease after 9 years of follow-up.

Adolescent↗

PubMed1991

[Dental tissue-composite bonding. SEM study].

The Authors investigated the different operative methods effects in the transition zone between human fresh teeth calcified tissues and a composite material. Morphological observations, done by means of standard and back scattered scanning electron microscopy, demonstrated the Gluma adhesion system efficiency towards enamel and dentin if manufacturing's applying systems are carefully followed, by showing a structure with no solutions of continuity between tooth and restoration.

Composite Resins↗

PubMed1991

Development of a second generation stereotactic apparatus for linear accelerator radiosurgery.

Linear accelerator radiosurgery technique is based on a multiple intersecting arc irradiations procedure. The coincidence of the axis of two rotation movements (of gantry and treatment couch) into the isocenter is critical for focusing irradiation. In October 1989, our linear accelerator was changed and the stereotactic apparatus had to be adapted to the new machine. After multiple mechanical tests of the new machine, the stereotactic head frame was fixed to the roller bearing allowing rotation of the couch. The new apparatus is described.

Humans↗

PubMed1991

Immunohistochemical localization of endothelin-like immunoreactivity in human tooth germ and mature dental pulp.

The distribution in oral tissues of endothelin, a multifunctional peptide originally identified within endothelial cells, and subsequently in some epithelial cells, neurons and neuroendocrine cells, has not been investigated yet. We have studied the localization of endothelin-like immunoreactivity in human tooth germ and mature dental pulp by immunohistochemical techniques. Such immunoreactivity was detected only within endothelial cells in both mature dental pulp and developing tooth. Arteries and veins of various sizes as well as small thin vessels displayed endothelin-like immunoreactivity. In the tooth germ, the cells of the enamel organ or the precursors of the odontoblasts were found unreactive. In the mature pulp, no cells of the stroma or nerves displayed endothelin-like immunoreactivity. These findings suggest that vascular endothelium may be the only source of endothelin in human dental tissues. It is tentatively proposed that endothelin released in mature tooth pulp may participate in the regulation of the pulpal blood flow. Although the possible role of endothelin in developing tissues is far from being clear, the mitogenic effects and the proto-oncogenes expression induced by endothelin in some cells raise the possibility that this peptide might also play a role during tooth development.

Adult↗

PubMed1991

A transient outward current dependent on external calcium in rat cerebellar granule cells.

The outward potassium current of rat cerebellar granule cells in culture was studied with the whole-cell patch-clamp method. Two voltage-dependent components were identified: a slow current, resembling the classical delayed rectifier current, and a fast component, similar to an IA-type current. The slow current was insensitive to 4-aminopyridine and independent of external Ca2+, but significantly inhibited by 3 mM tetraethylammonium. The fast current was depressed by external 4-aminopyridine, with an ED50 = 0.7 mM, and it was abolished by removal of divalent cations from the external medium. The sensitivity of the transient outward current to different divalent cations was investigated by equimolar substitution of Ca2+, Mn2+ and Mg2+. In 2.8 mM Mn2+, the transient potassium conductance was comparable to that in 2.8 mM Ca2+, while in 2.8 mM Mg2+ the transient component was drastically reduced, as in the absence of any divalent cations. However, when Ca2+ was present, Mg2+ up to 5 mM had no effect. The transient current increased with increasing concentrations of external Ca2+, [Ca2+]o, and the maximum conductance vs. [Ca2+]o curve could be approximated by a one-site model. In addition, the current recorded with 5.5 mM BAPTA in the intracellular solution was not different from that recorded in the absence of any Ca2+ buffer. These results suggest that divalent cations modulate the potassium channel interacting with a site on the external side of the cell membrane.

Animals↗

PubMed1991

Right-sided anarchic (alien) hand: a longitudinal study.

A patient with a bilateral frontal vascular lesion, encroaching upon the mesial cortex on the left and damage of the corpus callosum showed the 'alien hand' phenomenon on the right. The various hypotheses as to the nature of the lesion for the alien hand phenomenon to appear are discussed. It is proposed that an acute clinical condition, following a lesion of the corpus callosum only, should be differentiated from a chronic condition resulting from the additional fronto-mesial lesion.

Arm↗

PubMed1991

Voltage-dependent calcium currents in dissociated granule cells from rat cerebellum.

Voltage-dependent calcium currents were investigated by the patch-clamp technique in whole-cell recording configuration in cultures from 8-day-old rat cerebella, which contained greater than or equal to 90% granule cells. In solutions designed to minimize the sodium and potassium conductances and in 20 mM barium, an inward current activated around -25 mV, reached a peak amplitude at +20 mV and reversed around +80 mV. In 20 mM calcium, this current was approximately 50% of that in barium. From one to three days in vitro only 16% of the cells tested (n = 20) had a current exceeding 50 pA in maximum amplitude, while after four days in vitro the current reached 100 pA in all neurons tested (n greater than 70). Verapamil (50-100 microM) reversibly depressed this current. The dihydropyridine agonist Bay K 8644 (1 microM) enhanced the maximum conductance by 25 +/- 8% (n = 4), caused a negative shift in the activation of 21 +/- 5 mV and a prolongation of the deactivation time course as the voltage was stepped back from +20 to -80 mV. The GABAB agonist baclofen (50 microM) reversibly depressed the current by 27 +/- 8% in 80% of the cells. The effect was similar to that of GABA (10 microM), when the GABAA response (chloride current) was partially blocked by bicucculine. This current can be classified as a dihydropyridine-sensitive high-voltage-activated calcium current. The modulation by GABAB agonists is likely to be significant for presynaptic inhibition.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗

PubMed1991

Case studies in working memory: a case for single cases?

Patterns of cognitive deficit in single neuropsychological cases are common sources of evidence for theories of normal cognition. In particular, the working memory model has benefited from data obtained from a number of contrasting patients, in some cases resulting in modifications of the working memory model. In this paper, patterns of data from short-term memory patients and anarthric patients are compared with patterns of data from normal subjects. The patterns of patient data that were unlike those patterns typically found for groups of normal subjects, could be incorporated within a modified version of the articulatory loop component of the working memory model. However a small number of individual normal subjects also did not show the pattern that is reported on the basis of average performance of groups of normal subjects. This causes some difficulty in interpreting those data from such 'aberrant normal' patterns, and those data from single patients with functional cognitive deficits. The implications of these findings for the interpretation of neuropsychological data are discussed in the context of the working memory model, but with the intention of making a general point pertaining to the development of functional models of cognition. It is argued that single case studies should continue to provide a useful source of evidence, providing that care is exercised in considering the implications of such data for models of normal cognition.

Adult↗

PubMed1991

Lymphatic vessels in the healthy human dental pulp.

The lymphatic vessels of the dental pulp have been studied in non-carious teeth of young people. A network of lymphatic vessels drains the pulpal tissue. The lymphatic capillaries are characterized by a thin wall with an irregular profile. Cellular projections rise from the endothelial cells. Micropinocytotic vesicles and intercellular adjoining structures are the main mechanisms for the lymph formation. Multivesicular structures, Weibel-Palade bodies and paracrystalline inclusions have been observed.

Child↗

PubMed1991

Lymphatic vessels in the developing diaphragm of the rat.

Diaphragms of fetal, neonatal and young albino rats have been observed both under light and electron microscopes to examine the presence and distribution of lymphatic vessels and their morphological features. In fetal diaphragms of between 18 and 22 days of gestation, no normal lymphatic vessels can be seen; only after birth, specifically in neonatal and 2-day-old rats, small lymphatic vessels appear; they are in close proximity to the blood vessels in the inner areas of the muscle. As the rats get older, lymphatic vessels are also observed in the subserosa where an abundant connective tissue is present. The fine structure of diaphragmatic lymphatic vessels is different at different ages. In neonatal rats of up to 2 days, the endothelial wall is very thin and often holed. The relationships between contiguous endothelial cells are characterized by simple end-to-end or overlapping structures. The basement membrane is virtually absent. Within the first week of life, the endothelial wall becomes more complex; along the wall, complex interdigitations between two contiguous endothelial cells often touch. A discontinuous basement membrane and collagen and elastic fibers surround the vessels. In the older rats (from 14 to 25 to 140 days), next to the complex interdigitations which characterize the junction between two contiguous endothelial cells, cellular flaps interdigitate forming a channel which opens out either to the exterior or the interior of the vessel. Dense bundles of elastic and collagen fibers are closely apposed to the endothelial wall.

Animals↗

PubMed1991

Immunocytochemical evidence for the presence of somatostatin-like immunoreactive nerves in human dental pulp.

Specific antiserum to somatostatin was used for the immunocytochemical detection of this neuropeptide in human dental pulp. Immunoreactive axon varicosities were observed in the radicular as well as coronal pulp. Fibers displaying somatostatin-like immunoreactivity were detectable within radicular nerve trunks and were found to be associated mainly with blood vessels. Nevertheless, positive fibers with no apparent relation to blood vessels were also observed. No pulp cell was found to be immunoreactive. Previous physiological studies demonstrated that somatostatin may function as a regulatory peptide in feline dental pulp via a pre-synaptic inhibition of substance P release from sensory nerve terminals. It is tempting to speculate that such a mechanism may also be effective in human teeth and may be of value in the regulation of pulpal blood flow and in situations when sensory nerve fibers are activated, e.g., during pulpal inflammation.

Axons↗

PubMed1991

[An ultrastructural study of the fibrillary component of dental tissues].

The recent interest for highly sophisticated techniques of dental tissue preparation aiming to display very particular structures, moved the AA. to improve the literature suggestions. In particular they made TEM and SEM observations of transitional zones between healthy and normal pulp and dentin after decalcification and trypsin at different concentrations treatment. The images obtained draw in the attention the study facilities of a technique that really removes all the non collagenic material. The data obtained in the pericellular zones also allowed some interventions in the recent literature discussion about inter-odontoblastic fibres.

Decalcification Technique↗

PubMed1991

Scanning and transmission electron microscopy of rabbit heart lymphatic capillaries.

The ultrastructural characteristics of the lymphatic capillaries of the rabbit heart were examined by scanning and transmission electron microscopy (SEM and TEM) using similar technical preparation. SEM defined the interrelationships between endothelial cells including the pocket-like structures formed by overlapping between cells and the corresponding intercellular bridges. Except for rare spindle cells apposed on the luminal surface of the endothelium seen only on SEM, these features were confirmed by TEM. On the abluminal side of the lymphatic capillary wall, a rich network of filaments and fibrils was detectable using both ultrastructural techniques. These two modalities (SEM and TEM) complement one another in defining the microanatomy of the lymphatic capillary.

Animals↗

PubMed1990

Radiotherapeutic treatment for breast cancer choroidal metastases.

A series of 14 eyes (11 patients) with choroidal metastases from breast cancer were reported. The lesions were classified into three grades according to the severity and extent of involvement. Eleven eyes (9 patients) were treated by radiotherapy with two opposed lateral fields using a 4 MeV linear accelerator. The contralateral eye received a prophylactic irradiation. An average dose of 42 Gy was delivered (range, 30-50). Results of radiotherapy were the following: 5 CR and 2 PR in grade II (9 eyes) and 2 PR in grade III (2 eyes). We conclude that radiotherapy is useful to control choroidal metastases of breast cancer. No contralateral metachronous involvement was found. Quality of life of responders showed a marked improvement. Radiation-induced injury was not seen.

Breast Neoplasms↗

PubMed1990

Peptidergic nerves in human dental pulp. An immunocytochemical study.

The peptidergic innervation of human dental pulp was studied with indirect immunofluorescence and immunoperoxidase techniques. Pulpal nerve fibres displaying immunoreactivity for cholecystokinin, calcitonin gene-related peptide, C-terminal flanking peptide of neuropeptide tyrosine, leucine-enkephalin, methionine-enkephalin, neuropeptide K, neuropeptide tyrosine, peptide with N-terminal histidine and C-terminal isoleucine, somatostatin-28, substance P and vasoactive intestinal polypeptide were observed. Immunoreactive axon varicosities were detectable within radicular and coronal nerve trunks and within the nerve plexus of Raschkow in the para-odontoblastic region. Many peptidergic nerve fibres were observed in association with blood vessels of various sizes. Substance P- and calcitonin-gene-related peptide-immunoreactive axons were visible in the odontoblastic layer. The occurrence of VIP- and PHI-immunoreactive fibres lends support to the hypothesis that human tooth may be supplied by parasympathetic nerves. The immunocytochemical results here shown provide a morphological basis to previous experimental studies concerning the possible roles of neuropeptides in nociception mechanisms, control of the blood flow and modulation of the inflammatory response in dental tissues.

Dental Pulp↗

PubMed1990

Immunocytochemical detection of protein p38 in human dental pulp.

The occurrence and distribution of protein p38 (synaptophysin) were investigated by immunofluorescence. Immunoreactivity for protein p38-like antigen was detected within axons of radicular nerve trunks entering the tooth and within nerve terminals close to blood vessels. Immunoreactive structures were also observed in the para-odontoblastic region. It is proposed that protein p38, translocated within small synaptic vesicles from neuronal perikarya along the axons, may be a reliable marker for detection of nerve endings in human tooth.

Axons↗