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F Osculati

Publications and source records attributed to F Osculati.

At least 19 recordsLinked to original sources
PubMed1995

In vivo morpho-functional study of rat gastric mucus secretion.

BACKGROUND: Morpho-functional studies of gastric mucosa are hampered by the lack of a technique allowing direct in situ visualization of the mucus in small living laboratory animals. METHODS: The material covering the gastric surface was studied in vivo in rats by magnetic resonance imaging (MRI) at 4.7 Tesla, and modification of its secretion was evaluated after pharmacological treatment. RESULTS: In unstimulated animals, the glandular portion of the stomach was lined by a layer of material emitting a signal of high intensity. Administration of 16,16-dimethyl prostaglandin E2 caused an accumulation of this material within a maximum 30 min after the administration of the drug. At 45 min, gastric emptying occurred and at 60 min, the lumen was almost free of material emitting a signal of high intensity. An increase in the intensity of the signal emitted from the material filling the gastric lumen was found after pentagastrin injection. After 45 min, the intensity of the signal emitted from the material in the gastric lumen decreased. 1H localized spectroscopy showed that after injection of pentagastrin there was an increase in the water proton peak within the gastric lumen. About one hour after stimulation, the water proton peak returned to the basal value. CONCLUSIONS: This study demonstrates that MRI displays gastric mucus in living small rodents and represents a sensitive screening test for pharmacological action on this structure, enabling morpho-functional studies.

Animals↗
PubMed1995

Interferon alpha/beta-induced abnormalities in adipocytes of suckling mice.

The modification induced by interferon (IFN) in brown adipose tissue (BAT) was studied by high spatial resolution magnetic resonance imaging (MRI), histology, and transmission electron microscopy (TEM). In IFN-treated mice, at MRI, the interscapular BAT was slightly enlarged and showed non-homogeneous areas of lipid accumulation. The thickness of the subcutaneous white adipose tissue was reduced with respect to control mice. In the liver, MRI showed a lipid accumulation. In IFN-treated mice, by light microscopy, brown adipocytes showed a larger lipid deposit with respect to control mice. At TEM, in BAT, the mitochondria were reduced in number, smaller and the number of cristae was also significantly reduced with respect to the controls (9.1 +/- 1.5 vs 20.1 +/- 1.9, P < 0.01). The inclusions in the mitochondrial matrix were significantly less numerous in IFN-treated than in control animals (1.9 +/- 0.7 vs 0.9 +/- 0.7 for mitochondrial section, P < 0.01). Abnormalities of endoplasmic reticulum described in hepatocytes were not found in brown adipocytes of IFN-treated mice. The present work demonstrates that, in the BAT of suckling mice, IFN-treatment induces morphologic alterations and that brown adipocytes have MRI and TEM features resembling those found in the lipid laden BAT of aged animals.

Adipocytes↗
PubMed1995

The frog taste disc: a prototype of the vertebrate gustatory organ.

The frog taste disc (TD) is apparently the largest gustatory organ found in vertebrates and seems to differentiate into a specialized variety of the prototypic scheme of the taste bud. An explanation for this unusual organization is lacking although it is possible to speculate the existence of environmental and nutritional requirements. Up to the present time, the most common model of the TD was based on two main cell types (sensory and sustentacular). This model may oversimplify the morphology of this structure since more numerous cell types have been described. We now propose a new model of the TD, based on comprehensive data on the ultrastructure of the organ obtained in the last 20 years. The main conclusions are the following: (1) the TD is a pluristratified epithelium with a general organization similar to that of the olfactory and vomeronasal epithelium; (2) it has skeleton composed of three different types of epithelial cells; (3) the chemoreceptorial surface is covered by different microenvironments; (4) three different types of neuro-epithelial systems are present; the type II is an 'open' sensory cell with axonal contacts devoid of vesicles; the type III is an 'open' sensory cell with synaptic-like junctions; the type i.v. is a 'closed' sensory cell with a 'Merkel-neurite complex'; (5) the nerve fibers in the basal plexus are mostly cholinergic while the peridiscal nerve fibers are mostly peptidergic. The presence of several cell types in the TD must be considered using these large receptors in electrophysiological studies or as a source of isolated cells, and their complexity must induce caution in the interpretation of the data. Text books of histology usually describe the peripheral structures associated with taste as very simple: an idea that probably must be revised. A taste organ is a highly complex structure composed of several sensory systems and a comparative approach can aid comprehension of its general organization. The study of the 'large taste organs' present in some species of amphibians can provide useful data for knowledge of the gustatory system of vertebrates.

Animals↗
PubMed1995

Biogenic amines in the taste organ.

The presence and content of biogenic amines in taste disk-bearing fungiform papillae of the frog, Rana esculenta, the only available model of an isolated taste organ, were verified by means of HPLC. Fungiform papillae were found to contain measurable amounts of serotonin, epinephrine and norepinephrine. The amounts of serotonin and epinephrine were significantly higher in fungiform papillae than in the general mucosa of the tongue. Moreover, the epinephrine content of fungiform papillae was found to differ across the tongue, in accordance with previous physiological studies showing an inhomogeneous response of different tongue regions to taste stimuli. Ultrastructural and histochemical investigations confirmed the presence of catecholamine and serotonin. The latter was found to be contained mainly in the basal cells of the frog taste disk. These results extend previous qualitative data on the presence of biogenic amines in taste chemoreceptors.

Animals↗
PubMed1994

Microvascular lesions in reflux oesophagitis and Barrett's oesophagus.

In 30 patients with reflux oesophagitis, the mucosal microvessels have been studied by transmission electron microscopy. The aim of the study was to test the hypothesis that a microvascular injury is involved in reflux oesophagitis, and to clarify if the epithelial metaplasia is correlated with a contemporaneous modification of the microvasculature in Barrett's oesophagus. In squamous epithelium-lined mucosa, signs of microangiopathy were found in all patients and capillaries regularly showed an interrupted, duplicated, or thickened basal lamina. In areas of columnar metaplasia, capillaries showed an ectatic lumen and a thin basal lamina without duplications or interruptions; endothelial cells had a thin rim of cytoplasm with many fenestrations. These findings demonstrate that microangiopathy is associated with epithelial damage in reflux oesophagitis.

Adult↗
PubMed1994

Magnetic resonance spectroscopy investigations of brown adipose tissue and isolated brown adipocytes.

Brown adipose tissue and collagenase-isolated brown adipocytes were investigated in rats by means of 1H and 13C nuclear magnetic resonance spectroscopy. After chloroform-methanol extraction of brown adipose tissue, proton and natural abundance 13C spectra of the chloroform fraction showed resonances attributable to triglycerides, and were qualitatively similar to those of the corresponding fraction of white adipose tissue. By means of quantitative analysis of 1H spectra, fatty acid unsaturation and polyunsaturation in triglycerides were found to be lower in brown than white adipose tissue; moreover, unsaturation parameters decreased in triglyceride fatty acids of brown adipose tissue upon norepinephrine administration or cold acclimatization of rats, and were affected by the age of donors. The molar percentage of mono- and polyunsaturated C18 fatty acids in triglycerides was determined from 13C spectra and found to change in the early post-natal period. Isolated, agarose-embedded brown adipocytes from 4-day-old rats showed a number of peaks in the carbohydrate region of 1H spectra that were not present in spectra of white adipocytes and almost disappeared in brown fat cells of older animals. These peaks could be restored by insulin exposure. Natural abundance 13C spectra of isolated brown adipocytes were resolved enough to allow unambiguous assignment of resonances to carbons of fatty acids, glycerol, glucose, ethanolamine, and choline. Calculation of the mono- to polyunsaturated fatty acids ratio in the cells was also performed. Nuclear magnetic resonance spectroscopy is a useful tool for the investigation of brown adipose tissue and adipocytes therefrom.

Acclimatization↗
PubMed1993

Freeze-fracture characterization of cell types at the surface of the taste organ of the frog, Rana esculenta.

The ultrastructure and distribution of intramembrane particles in the chemoreceptor surface of the frog taste organ have been studied by means of freeze-fracture. Sustentacular, wing, mucous cells and two different types of putative taste cells were found to reach the free surface of this chemoreceptor. Each of these cell types was characterized by a different pattern and density of intramembrane particles in the free surface. Wing cells displayed a relatively low number of large intramembrane particles (11.1 +/- 1.4 nm in diameter). Particles of similar size were also present in a much higher concentration in the membrane of cylinder-ending putative taste cells. In microvilli-ending putative taste cells, mucous cells, and sustentacular cells, small intramembrane particles were observed (6.8 +/- 0.78, 6.9 +/- 1.3, 7.2 +/- 0.7 nm in diameter, respectively). The density of these particles was higher in the sustentacular cells than in the other two cell types. These data provide evidence that there are two morphologically distinct types of putative taste cells in the frog taste organ, demonstrating that they are characterized by different pattern of intramembrane particles in their free surface. Furthermore, the present results support previous findings indicating that wing and sustentacular elements represent two different cell types.

Animals↗
PubMed1993

Ultrastructural and morphometrical analyses of the brown adipocyte nucleus in a hibernating dormouse.

The fine morphology, size, and perichromatin granule frequency were analysed in brown adipocyte nuclei from hibernating, arousing, and euthermic dormice, Muscardinus avellanarius. Unusual nuclear structural constituents such as nuclear amorphous bodies, coiled body-like constituents and bundles of nucleoplasmic filaments were described as typical of hibernating nuclei. Morphometrical findings showed significant difference in total nuclear and nucleolar size in the three physiological conditions investigated as well as decreasing frequency of perichromatin granules in nuclei of hibernating to arousing to euthermic animals. A possible involvement of these granules in the intranuclear transport or storage of pre-mRNA is discussed in the context of other experimental evidence.

Adipocytes↗
PubMed1993

Reflux esophagitis in children: a scanning and transmission electron microscopy study.

In children, excess of gastroesophageal reflux causes lesions of the esophageal mucosa that we have studied by scanning and transmission electron microscopy (SEM and TEM respectively) in 27 grasp biopsies prelevated during endoscopic procedures. Ultrastructural lesions can be graded on the basis of their severity. In grade I, epithelial cells are well preserved in the deepest layers whereas the superficial cells display ultrastructural alterations such as irregular microridges or reduced intercellular junctions. In grade II, the surface is composed of extruding cells and in the intermediate layer, large intercellular spaces containing lympho-monocytic cells are visible. In grade III, the mucosal surface is characterized by crater-like erosions, degenerating cells are visible in all the layers; in two patients columnar epithelium-lined areas (Barrett's esophagus) have been identified. Our results suggest that in patients with reflux esophagitis, ultrastructural examination of grasp biopsies prelevated by pediatric endoscopes allows a grading of the anatomical lesions providing data that can not be obtained by conventional histology.

Adolescent↗
PubMed1992

Surfactant-like material in the antral gastric mucosa of children.

It has been proposed that the hydrophobicity of the gastric mucosa is due to surfactant-like material (SLM), mainly composed of phospholipid, adsorbed to the mucosal surface. Biochemical and physiological studies have been performed in different mammals but morphological data on children are lacking. In the present work, the presence of SLM on the antral gastric mucosa of children has been studied by electron microscopy. The results demonstrate that SLM is present and shows two different forms, lamellar bodies and lamellar layers. In the mucosae without endoscopic, histologic, and ultrastructural alterations we have found SLM when the tannic acid method has been used but not when the tissue has been fixed only in glutaraldehyde. Our results suggest that in children with ultrastructural alterations of the epithelium, the amount of gastric SLM is increased in respect to children with a normal mucosa and that the amount of SLM on the surface of the gastric antral mucosa is modified in pathologic conditions.

Adolescent↗
PubMed1992

Magnetic resonance imaging of the saccular otolithic mass.

The frog's inner ear was studied in vivo by high spatial resolution magnetic resonance imaging at 7 Tesla. The vestibule, the internal acoustic meatus, and the auditory tube have been identified. The large otolithic mass contained in the vestibule showed a virtual absence of magnetic resonance signal probably due to its composition of closely packed otoconia.

Animals↗
PubMed1991

In vivo morphometry and functional morphology of brown adipose tissue by magnetic resonance imaging.

Brown adipose tissue (BAT) is the main effector of nonshivering thermogenesis and diet-induced thermogenesis in mammals. Assessment of the magnitude and perturbations of BAT deposits in the intact, living body would be of much relevance for quantitative studies of BAT functions, but such studies have been impossible to date. In this paper it is shown that magnetic resonance imaging (MRI) morphometry can provide the means for accurate, repeated determinations of the volume of BAT deposits in a living animal; moreover, tissue modifications due to acclimation at different ambient temperatures are revealed in vivo by MRI, which correlates with histology and ultrastructure. Furthermore, MRI differentiates areas of BAT responsive to acute adrenergic stimulation, thereby giving information on the thermogenetically active tissue in the intact animal. Therefore, MRI represents a reliable tool for correlative morphological and functional studies of BAT in the living animal.

Adipose Tissue, Brown↗
PubMed1991

The correlation between magnetic resonance imaging and ultrastructural patterns of brown adipose tissue.

The present paper reports on magnetic resonance imaging (MRI) at high spatial resolution of the brown adipose tissue (BAT) in laboratory rodents, in comparison with light and electron microscopy findings. Our aim was to assess whether MRI correlates with the expected ultrastructural differences between newborn and adult BAT. The study was performed on the cervical and the interscapular BAT deposits by means of a nuclear magnetic resonance (NMR)-spectrometer equipped with a high resolution imaging system. Ultrastructural examination of BAT at different ages showed three different patterns of adipocyte ultrastructure in BAT which were associated with different MRI patterns. In BAT, MRI identifies the prevalent type of adipocyte in the tissue providing information consistent with ultrastructural results. Results presented here show that MRI represents a precise and reliable tool to investigate the morphology of tissues in living animals. The safe, non-invasive MRI technique represents a very useful tool in morphological research.

Adipose Tissue, Brown↗
PubMed1991

Age-related modification in the thymus of rats and mice: an in vivo study by magnetic resonance. MR imaging of the thymus.

Techniques of magnetic resonance were used to investigate in vivo the normal thymus and its age-related modifications in small rodents. The data were compared with anatomical preparations and histological sections of the animals. The possibility to visualize modifications of the thymus in living organisms open new perspectives for the follow up of experimental manipulations on laboratory animals.

Age Factors↗
PubMed1990

Characterization of different microenvironments at the surface of the frog's taste organ.

We used a panel of histochemical techniques to identify and characterize the cell-associated extracellular material at the surface of the frog's taste organ. We employed morphological and histochemical techniques using both the light microscope and the electron microscope. Results show that the apical, external aspect of cells reaching the surface of the taste organ is in close contact with a layer of amorphous material. The histochemical characteristics of this material vary according to the cell type with which it is in contact. Three different microenvironments can be identified at the surface of the frog's taste organ: type 1 microenvironment is associated with the superficial layer of mucus (secretory) cells; type 2 microenvironment characterizes the surface of the so-called wing cells, which reach the surface of the taste organ as thin laminae running among mucus cells; and type 3 microenvironment shrouds the free endings of putative taste cells and is rich in calcium and lipids. Type 2 and type 3 microenvironments fix peroxidase (a sapid macromolecule) with increasing affinity. We conclude that highly differentiated microenvironments exist at the surface of the frog's taste organ, and these could play a role in the chain of biological events leading to the taste sensation. Furthermore, characterization of the cell-associated, specific microenvironments can help clarify the role of the different cell types in the frog's taste organ.

Animals↗
PubMed1990

The chemoreceptor surface of the taste disc in the frog, Rana esculenta. An ultrastructural study with lanthanum nitrate.

The distribution of lanthanum on the taste disc of the frog, Rana esculenta, after en bloc staining of the tongue with lanthanum nitrate was studied at the ultrastructural level by means of scanning electron microscopy (in the secondary electron mode or in the back scattered electron mode), energy-dispersive X-ray microanalysis, transmission electron microscopy and electron spectroscopic imaging. It was consistently found that lanthanum distribution on the surface of the taste disc is not homogeneous and that the surface of putative receptor cells is in contact with strongly lanthanum-positive material. Calcium co-localizes with lanthanum at that level. These results suggest that different microenvironments exist at the surface of the taste disc and that this could be relevant to the receptor function.

Animals↗
PubMed1990

An ultrastructural study of normal human thymic epithelium in primary cultures.

The ultrastructural study of a large series of samples of normal human thymic epithelial cells (TECs) in primary cultures is here presented. Cultured TECs are heterogeneous due to marked differences in their cytoplasmic organization. In particular, a spectrum of ultrastructural features have been observed, ranging from poorly-differentiated cells to secretory and epidermoid-like ones, as well as intermediate transitional forms and cells co-expressing both epidermoid-like and secretory features. Cells with peculiar secretory (neuroendocrine-like) characteristics have also been identified in the culture obtained from one of the donors. These data suggest the existence of a thymic epithelial cell type which may act as a dynamic unit, changing its cytoplasmic organization in response to microenvironmental signals. The types and interrelationships of cytoplasmic organelles observed in the secretory cells suggest that the production of thymic peptides involves the classical pathway of protein synthesis and secretion.

Cell Differentiation↗