Biomedical subjects

F Osculati

Publications and source records attributed to F Osculati.

At least 37 records · Page 2Linked to original sources

PubMed1999

alpha-Gustducin expression in the vomeronasal organ of the mouse.

The expression of alpha-gustducin, a G protein alpha subunit involved in bitter and sweet taste transduction, was investigated in chemosensory tissues of adult mice. By immunohistochemistry, alpha gustducin was absent in the olfactory neuroepithelium. Instead, alpha gustducin was expressed in a subset of bipolar cells in the proliferative zone of the vomeronasal neuroepithelium as well as in taste buds. Northern blot analysis confirmed the presence of alpha gustducin in isolated vomeronasal organs. Moreover, immunohisto- chemistry revealed the expression of alpha gustducin in scattered cells of the nasal respiratory epithelium. These results show for the first time that alpha gustducin is expressed in chemosensory tissue outside the alimentary tract, suggesting that common transduction mechanisms could be shared by apparently unrelated chemosensory tissues.

Animals↗

PubMed1999

The anatomy and functional role of the circumvallate papilla/von Ebner gland complex.

We suggest that the description of the reciprocal relationships between the circumvallate papilla (CP) and von Ebner glands (VEGs) reported in most textbooks of anatomy must be rewritten. In the past, the VEG was described as a gland ancillary to the taste buds, mainly involved in the washing of the vallum around the CP or in perireceptorial events. Recent data obtained in our laboratory or reported in the literature indicate that both these structures form a single functional unity which could be called circumvallata papilla/von Ebner gland (CP/VEG) complex. The CP/VEG complex seems to represent an important enzyme- and pheromone-producing system composed of a sensitive (taste buds) and an effectory (VEG) branch linked by feedback mechanisms of control. In our hypothesis, the taste buds located in the distal portion of the VEG ductal system can be considered similar to the chemoreceptory cells located in other portions of the digestive apparatus such as pancreatic and bile ducts. Therefore, the CP/VEG complex represents a rare example of chemoreceptor-secretory organ.

Humans↗

PubMed1999

Alpha-gustducin-immunoreactive solitary chemosensory cells in the developing chemoreceptorial epithelium of the rat vallate papilla.

The presence of solitary chemosensory cells was studied in rat vallate papillae during the first week of post-natal life by alpha-gustducin immunocytochemistry. In 1- to 3-day-old rats, isolated alpha-gustducin-immunoreactive cells were found within the epithelium of the vallate papilla. These cells, mainly located in the basal layer, were scattered among keratocytes and wrapped in alpha-gustducin-negative epithelial cells in a glia-like fashion. The alpha-gustducin-immunoreactive cells were usually round and some of them gave rise to short, large processes directed towards the lumen of the oral cavity or the basal lamina. Rarely, some cells showed an evident bipolar shape. Small taste buds containing either alpha-gustducin-immunoreactive or alpha-gustducin-negative cells appeared in the vallate papillae of 4-day-old rats in which isolated, bipolar-shaped alpha-gustducin-immunoreactive cells were also found. After the first week of post-natal life, the taste buds appeared basically similar to those of adult animals. In conclusion, the present study demonstrates that the presence of epithelial cells with characteristics of solitary chemosensory cells precedes the development of the taste buds.

Age Factors↗

PubMed1998

Electrophysiological characterization of a putative supporting cell isolated from the frog taste disk.

Chemosensory cells in vertebrate taste organs have two obvious specializations: an apical membrane with access to the tastants occurring in food, and synapses with sensory axons. In many species, however, certain differentiated taste cells have access to the tastants but lack any synaptic contacts with axons, and a supportive rather than chemosensory function has been attributed to them. Until now, no functional data are available for these taste cells. To begin to understand their role in taste organ physiology, we have characterized with patch-clamp recording techniques the electrophysiological properties of a putative supporting cell-the so-called wing cell-isolated from frog taste disks. Wing cells were distinguished from chemosensory elements by the presence of a typical, sheet-like apical process. Their resting potential was approximately -52 mV, and the average input resistance was 4.8 GOmega. Wing cells possessed voltage-gated Na+ currents sensitive to TTX, and an inactivating, voltage-gated K+ current sensitive to TEA. Current injections elicited single action potentials but not repetitive firing. We found no evidence for voltage-gated Ca2+ currents under various experimental conditions. Amiloride-sensitive Na+ channels, thought to be involved in Na+ chemotransduction, were present in wing cells. Many of the membrane properties of wing cells have been also reported for chemosensory taste cells. The presence of ion channels in wing cells might be suggestive of a role in controlling the microenvironment inside the taste organs or the functioning of chemosensory cells or both. In addition, they might participate directly in the sensory transduction events by allowing loop currents to flow inside the taste organs during chemostimulation.

Action Potentials↗

PubMed1998

Evolution strategy optimization for selective pulses in NMR

We present a first set of improved selective pulses, obtained with a numerical technique similar to the one proposed by Geen and Freeman. The novelty is essentially a robust and efficient "evolution strategy" which consistently leads, in a matter of minutes, to "solutions" better than those published so far. The other two ingredients are a "cost function," which includes contributions from peak and average radiofrequency power, and some understanding of the peculiar requirements of each type of pulse. For example, good solutions for self-refocusing pulses and "negative phase excitation pulses" (which yield a maximum signal well after the end of the pulse) are found, as may have been predicted, among amplitude modulated pulses with 270 degrees tip angles. Emphasis is given to the search for solutions with low RF power for selective excitation, saturation, and inversion pulses. Experimental verification of accuracy and power requirements of the pulses has been performed with a 4.7 T Sisco imager. Copyright 1998 Academic Press.

Journal Article↗

PubMed1998

A PC-based workstation for processing and analysis of MRI data.

The present work demonstrates that a low cost, flexible and user-friendly workstation for the MRI laboratory can be implemented by using a personal computer and public-domain software. The workstation is based on a Pentium personal computer, operating under the Linux operative system, and uses the software Khoros (Khoral Research, Albuquerque, NM). This software is a general purpose package for handling signals and we here report its suitability for MR images analysis. Khoros allows to create workspaces where different procedures (also written by the users) can be combined for implementing more complex procedures. We created workspaces for obtaining 2D and 3D images from time domain data which also allow for apodization and zero-filling. The time required for a 3D-FFT (matrix size 128x128x128) is about 12 min with the presently used microprocessor. We have also created workspaces for calculating apparent diffusion coefficient maps and for segmentation of MR images. Our results demonstrate that a personal computer equipped with public-domain software can represent a powerful tool to fulfil the MRI laboratory common needs.

Animals↗

PubMed1998

Effect of dietary supplementation with zinc sulphate on the aging process: a study using high field intensity MRI and chemical shift imaging.

High field intensity magnetic resonance imaging (HF-MRI) has been applied to the in vivo study of age-related processes of organs located in the cervical-thoracic region in mice and to describe the effects of oral zinc supplementation on these processes. Spin-echo (SE) pulse sequence and chemical shift imaging (CSI) techniques have been used. Aging produced a progressive reduction of muscular masses and of thymic area, whereas the HF-MRI appearances of spinal cord and of salivary glands were unchanged. In some aged animals, subcutaneous fat was reduced while visceral fat was well developed. In the group of old animals supplemented with zinc sulphate, muscular masses were more developed than that of the group of untreated old animals. Oral zinc supplementation also produced an enlargement of the adipose tissue and the thymic area showed an increase of about 65% compared with thymic area measured in the group of old animals used as controls. The present study confirms previous data about the effects of Zn supplementation on aging processes and demonstrates that HF-MRI is a powerful technique to study processes of aging, providing information about the effects of drug treatments on these processes.

Adipose Tissue↗

PubMed1998

Solitary chemosensory cells in the developing chemoreceptorial epithelium of the vallate papilla.

The solitary chemosensory cells are considered typical of aquatic vertebrates and have never been described in the oral cavity of terrestrial vertebrates. We describe elements with ultrastructural characteristics of the solitary chemosensory cell in the gustatory epithelium of rats in the first week of extrauterine life. These elements appeared isolated, located among keratinocytes, and wrapped by glial-like elements. They showed a bipolar shape with a round cell body, a thin apical process, and a thicker basal one. Nerve fibers contacted the cell body and the processes. The cells showed small dense granules mainly located near nerve contacts. Small bundles of tonofilaments were visible in the perinuclear cytoplasm. Similar elements were not found in rats after the first week of extrauterine life. The present study demonstrates in a mammal that the development of taste buds is preceded by the presence of epithelial elements with ultrastructural characteristics of the solitary chemosensory cells described in lower vertebrates. This finding suggests that the oral chemoreception in the suckling rats may be mediated by three different pathways (i.e., gustatory system, common chemical sense, and solitary chemosensory cell system).

Animals↗

PubMed1998

Membrane-bounded intratubular bodies in rat taste buds.

The ultrastructural features of membrane-bounded bodies contained in the tubulo-vesicular system in the outer segment of taste bud cells are described. Each body showed a round, fusiform or oval shape, was surrounded by a trilaminar membrane and enclosed an electron dense matrix sometimes containing inclusions. These bodies were found at all ages studied. Similar structures were also found embedded in the material plugging the taste pore. Our findings suggest that these bodies could be secreted at the free surface of the cells and be involved in the concentration of divalent cations.

Animals↗

PubMed1998

High-field magnetic resonance imaging of the developing human brain from the 10th to the 16th week of gestational Age.

In the present work, high-field magnetic resonance imaging (HF-MRI) was applied to study the developing human brain paying particular attention to the structures of interest in pathology of malformation. The aim of the work was to evaluate the possible application of HF-MRI to the analysis of brain development in the absence of some limits of conventional histological technique. Seven formalin-fixed human fetuses of 50, 65, 70, 85, 110, 116 and 125 mm crown/ rump length (corresponding to a gestational age ranging from 10 to 16 weeks) were examined in an imager-spectrometer equipped with a 4. 7-tesla horizontal magnet with a 33-cm bore. In the brain of all the fetuses the telencephalic, mesencephalic and rhombencephalic vesicles were recognizable and an easy quantitative evaluation of the brain curvatures in the absence of distortion due to dissection was possible. Comparing fetuses at different gestational ages, the spatial modification of the different vesicles was evident. In fetuses at 16 weeks of gestational age, stratified compartments of the telencephalic wall were evident. The germinal zone and the cortical plate were visible: the germinal layer was identifiable as a hypointensity in the periventricular area. The subplate zone and the intermediate zone emitted a strong intensity signal. Our study demonstrates that HF-MRI can contribute to the study of the complex developmental events in the human brain from the 10th to 16th week of gestational age in a submillimetric scale of resolution. This technique can provide information about the morphology of the encephalic vesicles and their relations with the bone cavity that cannot be obtained with conventional methods and may be a useful adjunct to histological techniques.

Anatomy, Cross-Sectional↗

PubMed1998

Ultrastructural lesions in the small bowel of patients with cystic fibrosis.

In the small bowel of patients with cystic fibrosis, primary defects involving both chloride transport and mucus secretion have been demonstrated, but there is no general consensus about the morphologic counterpart of functional and biochemical abnormalities. We have studied the intestinal mucosa in a group of patients with cystic fibrosis and gastrointestinal symptoms with the aim of evaluating whether the intestinal mucosa is normal as previously described. The results showed that the small bowel involvement is characterized by a typical pattern of lesions with preservation of the mucosal architecture and abundant mucus at the surface. In the villi, the absorbing cells were generally well preserved, but unusual features were found in the apical portion of the goblet cells, which formed sacks containing mucus droplets. Similar sacks were also found detached from the goblet cells. Aspects of degeneration were present in the upper portion of the crypts where elements with an extensive vacuolization of the cytoplasm and swelling were detectable. This study demonstrates that in patients with cystic fibrosis the ultrastructure of the small bowel mucosa is not normal as previously described, but that an ultrastructurally detectable enteropathy exists. This enteropathy seems to be localized mainly in sites where molecular biology studies described the highest expression of cystic fibrosis transmembrane conductance regulator.

Child↗

PubMed1997

Biogenic amines in the vomeronasal organ.

The vomeronasal organ of frog and mouse was investigated for the presence and content of serotonin and catecholamines by means of high-performance liquid chromatography. Measurable amounts of serotonin, adrenaline and noradrenaline were found in the vomeronasal organ of adult individuals of both species. The amine content varied with sex of adult frogs and mice and sexual maturity of mice. In preliminary experiments, acute exposure to male urine containing pheromone affected the amine content in the vomeronasal organ of adult female mice. These data suggest that functional sex dimorphism is present in the vomeronasal organ, and biochemical changes therein take place according to stage of sexual maturity. The role of biogenic amines in the vomeronasal organ deserves further study.

Animals↗

PubMed1997

NADPH-diaphorase in antral gastritis of childhood.

BACKGROUND: Nitric oxide has an important role in the pathophysiology of the gastric mucosa. However, to date, it is not clear if nitric oxide plays a cytoprotective or cytotoxic role in the pathogenesis of mucosal lesion. METHODS: We have used the NADPH-diaphorase histochemistry that selectively stains cells containing nitric oxide synthase, the enzyme that catalyzes the production of nitric oxide on the antral gastric mucosa of children with antral gastritis. RESULTS: In the lamina propria of the mucosa, the presence of the enzymatic activity was found in perivascular round cells and nerve fibers. In the epithelium, focal positivity to NADPH-diaphorase was found in superficial cells, mainly located in the extrusive zones. The epithelial cells in the pits and glands were negative, in the mucous layer, Helicobacter pylori were also stained by NADPH-diaphorase. A single H. pylori-infected child who was also examined after eradication of the H. pylori showed during the control examination absence of microorganisms and reduction of the NADPH-diaphorase-positive cells in the mucosa. CONCLUSIONS: Our results demonstrate that, in gastric mucosa, endogenous and exogenous structures express a NADPH-diaphorase activity.

Animals↗

PubMed1997

Chemical shift imaging at 4.7 tesla of brown adipose tissue.

In vivo distinction between small deposits of brown adipose tissue (BAT) and surrounding tissues may be difficult. In this article, we propose an experiment paradigm, based on techniques of chemical shift magnetic resonance imaging (CSI), which can improve the methods presently available for the study of BAT. Male rats were examined in an imager-spectrometer equipped with a 4.7 T magnet. Proton spectra of isolated BAT deposits showed that both fat and water protons contributed significantly to the genesis of the magnetic resonance signal. An equivocal definition of BAT deposits was obtained by three (respectively, spin-echo, water-selective, and fat-selective) images. The spin-echo (SE), T1-weighted image provided the best anatomical description of the structures. The images selective for fat-protons displayed the degree of lipid accumulation in each area. The images selective for water-protons provided an internal control of adipose tissue localization. The proposed paradigm allows an unequivocal definition of BAT deposits and appears particularly useful in studies where experimental manipulation (i.e., cold acclimation or drug treatment) produces changes in this issue.

Adipose Tissue↗

PubMed1996

Induction of NADPH-diaphorase activity in the rat forebrain after middle cerebral artery occlusion.

Induction of NADPH-diaphorase (NDP) following ischemic infarction was studied by means of histochemistry in the rat cerebral cortex 1,2,7, and 14 days after distal occlusion of the right middle cerebral artery (MCA). The fine structure of cells in the penumbra region of the necrotic center was also investigated. MCA distal occlusion resulted in ischemic lesion of the frontoparietal cortex of variable extent; NDP induction was detected in neurons, astrocytes, macrophages, and endothelial cells, with regional specificity and a temporal gradient. One, two, and seven days after MCA occlusion, weak NDP positivity was consistently induced in some pyramidal neurons in cortical areas neighboring the necrotic area; NDP induction was also seen in pyramidal neurons of the ipsilateral anterior cingulate and infralimbic cortices and in the tenia tecta. In addition, numerous NDP-positive pyramidal neurons were detected in the contralateral frontoparietal cortex after relatively large ischemic lesions. Two weeks after MCA occlusion, NDP induction in neurons was only evident in the deep cortical layers near the lesion. NDP histochemistry combined with glial fibrillary acidic protein immunofluorescence, performed 7 days after MCA occlusion, indicated that the astrocytes at the periphery of the necrotic area were hypertrophic and some of them were also NDP-positive. One and two days after MCA occlusion, numerous macrophages displaying NDP positivity of variable intensity were seen at the periphery of the necrotic area and in the external capsule of the ischemic cerebral hemisphere. Many endothelial cells in the cortex and subcortical white matter were consistently NDP-positive in all rats. Electron microscopic studies indicated that the area adjacent to the necrotic center was composed of fibrous astrocytes, with the morphological characteristics of proliferation, and numerous lysosome-filled macrophages. Altogether the present results suggest that focal cerebral ischemia may induce in different cell types nitric oxide synthase, which is equivalent to NDP in fixed tissue. The induction of nitric oxide synthase may be related to (1) blood-flow regulation at relatively early postischemic stages, which may decline when collateral circulation is established, and/or (2) cytotoxic or neuroprotective mechanisms.

Animals↗

PubMed1996

The microvascular system in ischemic cortical lesions.

In the rat, normal blood flow can be restored in the territory of the occluded artery after an arterial occlusion. This event has been attributed to changes in the collateral vessels supplying the territory of the occluded artery. Since only a limited amount of data is available about the plasticity of the microvascular system after a cortical ischemic lesion, in the present study we have evaluated whether the restoration of blood flow to normal levels in the territory of the middle cerebral artery after permanent ischemia is due only to flow through preexisting collateral vessels or also to the development of new microvessels. Middle cerebral artery occlusion was performed in 45 rats. After 24 h of ischemia, magnetic resonance imaging was used to select 16 rats with cortical lesions of similar size and location. After 2 weeks, vascular corrosion casts were obtained from 8 rats by injection of low-viscosity resin and observed by scanning electron microscopy. A correlative light and electron microscopy study was performed using the remaining 8 rats. Two different patterns of vascular modifications were found, one dorsal and one ventral to the lesion. The dorsal portion of the lesion was vascularized by collateral arteries originating from the anterior or posterior cerebral arteries. Collateral trunks showed a meandering course, mainly in the occipital pole. In the ventral portion of the lesion a complex microvascular system was found characterized by an intense vascular proliferation. The arterioles showed a parallel, candelabrum-like pattern with dichotomic branching. Contraction rings were frequently seen. The capillaries showed a sinusoid-like structure, with a large lumen and a continuous endothelium with many micropinocytotic vesicles. A peripheral ring-shaped venous sinus was composed of a network of flat vessels. These results give the first comprehensive description of the microvascular modifications in a focal model of infarct and suggest that the restoration of blood flow to normal levels described in the territory of the middle cerebral artery after permanent ischemia may be due not only to flow through collateral vessels but also to the development of a new vascular system originating mainly from branches of the middle cerebral artery before the occlusion point.

Animals↗

PubMed1996

Extrusion of corpora amylacea from the marginal gila at the vestibular root entry zone.

We have studied the vestibular nerve in patents suffering from Meniere' s disease and vascular cross-compression syndrome of the root entry zone due to close contact with the nerve of the antero-inferior cerebellar artery or one of its branches. All patients underwent vestibular neurectomy using the restrosigmoid approach which allows the resection of a relatively long nerve segment. In all the studied vestibular nerves a central and a peripheral zone could be distinguished. In the central zone, a massive accumulation of corpora amylacea (CA) was detected in the cytoplasm of astrocytes. Many CA were seen to protrude from the central nervous system into the pial connective tissue. These structures resembled sessile or predunculated polyps, with a complex system of scissurae at their bases. CA were also found in extracellular location in the pial connective tissue near capillaries, and not wrapped by membranes. Our findings suggest that after their production in astrocytes, CA are transferred into a pial connective tissue across the glial-limiting lamina. Thus, the present results indicate that CA do not merely represent an accumulation of abnormal material, but they could instead be part of a glio-pial system devoted to the clearance of substances from the nervous system.

Adult↗

PubMed1996

Tissutal imaging by nuclear magnetic resonance.

The present work reviews the main applications of nuclear magnetic resonance (NMR)-technology and, in particular, of magnetic resonance imaging (MRI) to tissutal analysis. To date, MRI represents a precise and reliable tool to investigate morphology and functional modification of tissues in vivo, providing information consistent with histology. MRI has numerous advantages over conventional techniques: it is harmless to tissues; volume measurements in vivo could be useful for morphometric studies; the same tissue can be examined several times (e.g. at different ages); several organs can be examined at the same time; serial sections of relevant structures can be obtained in all planes, thereby allowing detailed reconstruction of the three-dimensional configuration of organs; motion within a tissue can be detected; and subsequent histological and ultrastructural studies of the tissue are possible. The main drawback (besides the cost of the basic instrumentation) is that resolution is relatively low in comparison with light microscopy. Finally, the analysis of the results is difficult, needing interdisciplinary competence, and MRI methods of tissutal analysis are not yet well standardized. Therefore, in our opinion, MRI is an interesting tool, complementary to other histological techniques, and it cannot be ignored by microscopists. However, in vivo MRI data must be evaluated with caution and histological controls are always required.

Animals↗