Biomedical subjects

C Marchetti

Publications and source records attributed to C Marchetti.

At least 109 records · Page 6Linked to original sources

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↗

PubMed1990

Voltage-dependent calcium currents in rat gonadotropes separated by centrifugal elutriation.

Centrifugal elutriation of rat pituitary cells yielded two functionally active fractions (6 and 7) that contained 30-40 and 50-60% gonadotropes, respectively. We studied the membrane ionic currents of these cells with the whole cell patch-clamp method. In physiological solution, cells from the enriched fractions displayed a tetrodotoxin-sensitive sodium current. In 20 mM external calcium and zero sodium, the inward current contained two components that were different in threshold, steady-state inactivation, and deactivation. One component was half activated at approximately -25 mV, half inactivated from a holding potential of -61 mV, and deactivated with a time constant of 3 ms. The second component was half activated at 6 mV and deactivated with a time constant of 0.35 ms. These two currents resembled the high-voltage-activated and low-voltage-activated calcium current described in many preparations, including clonal and primary pituitary cells. Bath application of 20 nM gonadotropin-releasing hormone caused a transient and reversible decrease of the calcium current at depolarized voltages and a negative shift of 10 mV in the activation curve. Both effects were observed in a percentage of cells that closely matches the percentage of gonadotropes in the fraction. The shift appeared to affect both components of the current and can partially account for the increased activity of Ca2+ channels at potentials close to the resting value.

Animals↗

PubMed1990

Linear accelerator radiosurgery of three-dimensional irregular targets.

Current radiosurgical techniques allow concentration of radiation from external sources into spherical targets. Nonspherical target volumes require a modification of the irradiation technique. Moreover, isodose shaping is sometimes necessary to spare nearby important radiosensitive structures. To meet these prerequisites we have introduced some technical refinements: (1) computer-controlled rectilinear translations of the target in combination with different angular positions of the source and (2) computer-controlled rotations of the target around a vertical axis in combination with different angular positions of the source. The first solution has proven efficient for treating irregular targets, while the second one was employed for focusing the radiation dose inside volumes obtained by rotation of ellipses.

Brain Neoplasms↗

PubMed1990

An enzyme-histochemical, ultrastructural and morphometric study on fetal and neonatal rat diaphragms.

The organogenesis of the rat diaphragm was studied with enzyme-histochemical, ultrastructural and morphometrical methods. 18 to 20 and 22 day in utero diaphragms were examined as well as 2-8-14 and 25 day old ones, in order to determine the age related changes in the diameter and the percentage of muscle fibers and mitochondria. In all examined ages, morphometric data showed type II fiber predominance. Type I and II fibers were equivalent in diameter. During fetal life, mitochondrial size increases appreciably with age while the mitochondrial percentage does not. Instead in postnatal life, the mitochondrial diameter is almost constant both for the small type I fibers and for the large ones (type II fibers). The mitochondrial percentage gradually increases particularly in the small fibers.

Adenosine Triphosphatases↗

PubMed1990

Immunocytochemical labelling of Merkel cells of human oral mucosa by means of antibodies to protein gene product 9.5.

Merkel cell (MC) are one of the non-keratinocyte cell populations that reside in oral epithelium. Protein gene product 9.5 (PGP 9.5) is a protein specifically present in the cytoplasm of neurons and neuroendocrine cells. It is demonstrated by immunofluorescence and immunoperoxidase that MC of oral human mucosa express PGP 9.5-like immunoreactivity. This finding is in agreement with the hypothesis that oral MC are paraneurons or neuroendocrine cells. The use of anti-PGP 9.5 serum may be of value for future studies of MC in normal and pathological oral tissues.

Antibodies↗

PubMed1990

[Photon or electron irradiation of the internal breast lymph node chain. Experimental dosimetry and clinical implications].

The radiation therapy of internal mammary chain, according to many other authors, is indicated in patients with N + breast cancer or with inner quadrant disease. Since the direct field with gamma radiation seems to induce important adverse effects on myocardium, the authors were induced to check experimentally dose distributions of 12-15 MeV electron beams and compare the results to gamma photon dose distribution. Materials and dosimetric methods as well as experimental results are described. Moreover theoretic and practical point of view are discussed coming to the conclusion that electron beams are more suitable for myocardial saving. Nevertheless some technical variations are required, to maintain the typical homogeneity of photon beams.

Breast Neoplasms↗

PubMed1990

[Light microscopy and electron microscopy study of the lymphatic capillaries of human dental pulp].

The existence and the morphological characteristics of the lymphatic capillaries of the dental pulp have been and are yet discussed. In this study the morphological properties of the lymphatic capillaries of the healthy human dental pulp have been described at light and electron microscopy. For the investigation human enclosed incisive and canine teeth surgically extracted and permanent premolars extracted for orthodontic reasons were used. On semithin sections the lymph capillaries are detectable as vessels of 15-50 microns in diameter with a very irregular shape and a subtle wall. No pericytes or muscular cells surround the endothelial lining. At ultrastructural level the lymph capillaries show a very thin and indented wall with protrusions towards the vessels lumen or the interstitium. The connections between adjacent endothelial cells are different and variously shaped: end to end contacts, overlapping between cellular protrusions and complex interdigitations among multiple protrusions of the endothelial cells. Sometimes the overlappings between endothelial cells determine intraparietal channels in communications with the interstitium and the vessel lumen. A discontinuous basal lamina and a network of filaments and fibrils surround the endothelial wall. Between the cytoplasmic organelles micropinocytotic vesicles, multivesicular bodies and the Weibel-Palade bodies are present.

Basement Membrane↗

PubMed1990

[Gardner syndrome. A report of 3 cases in members of the same family].

The aim of the present report is to describe the overall mandibular and extramandibular lesions correlated to Gardner's syndrome which were found in the same family (mother and two daughters). In two cases (mother and one daughter) mandibular lesions consisted of osteoma. In the latter, these were associated with composite odontoma. In the other daughter the lesions consisted of desmoid fibroma. The two daughters revealed single colonic polyposis whereas the mother was affected by multiple colonic polyposis and subcutaneous lipoma. Such a constellation of lesions may be attributed to Gardner's syndrome, a Mendelian hereditary syndrome which is often incomplete. In fact, intestinal polyposis can only be associated with one of the various extraintestinal manifestations of the syndrome. The recognition of the syndrome is important given the high percentage of intestinal polyp-adenocarcinoma associations.

Adolescent↗

PubMed1989

[Use of nimesulide in orthognathic surgery of the jaws].

The aim of this clinical study was to value the antiphlogistic and analgesic efficiency of Nimesulide on 40 patients suffering from facial anomalies and subjected to corrective surgery with many facial osteotomies (Le Fort 1, sagittal osteotomy of mandibular ramus sec. Obwegeser-Dal Pont). Nimesulide was effective in reducing post-surgery oedema and spontaneous and caused pain. Besides it was of easy assumption and well suffered from the major part of the patients subjected to this kind of surgery.

Adolescent↗