Biomedical subjects
Publications and source records attributed to A Sbarbati.
A notchlike bone defect in the basiocciput due to a prominent fossa navicularis was incidentally discovered in a patient referred for radiologic evaluation of sinusitis. MR images showed that the osseous defect was filled with lymphoid tissue of the pharyngeal tonsil. The occurrence of this anatomic variant is discussed, with reference to ancient anatomic works.
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.
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.
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.
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.
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.
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.
Samples of the respiratory mucosa of children with recurrent respiratory infections suspected of having primary ciliary dyskinesia are routinely fixed with glutaraldehyde before ultrastructural examination. This standard technique, however, may not be optimal for visualizing ciliary components or for preserving several cellular and extracellular structures during dehydration and embedding procedures. In this study, brushes of nasal (28 samples) and/or tracheal (9 samples) mucosa from 32 children with recurrent respiratory tract infections were examined. Twenty-nine samples were fixed with glutaraldehyde supplemented with tannic acid to determine if the ultrastructural analysis of respiratory epithelium and bronchial secretions could be improved. Eight samples were conventionally fixed with glutaraldehyde alone. Lesions of the cellular membrane and damaged cells were easily visualized using tannic acid supplemented fixation. Internal ciliary structures including individual microtubules and dynein arms were also more clearly observed. In addition, the internal structure of microvilli of the respiratory epithelium could be studied and the presence of phospholipid-rich surfactant-like material within nasal and tracheal secretions were visualized after tannic acid supplemented fixation. We suggest that addition of tannic acid during fixation is useful for accurate ultrastructural evaluation of respiratory mucosa in both clinical and experimental situations.
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.
Parathyroid glands (n = 271) removed from 130 patients were examined by light and electron microscopy. A standardized method of tissue processing was employed and morphometry was performed. The aim of the paper is to provide a description of the human parathyroid chief cell ultrastructure in health and disease, with quantitative evaluation of structures involved in secretion of parathyroid hormone in a large case series, and to discuss their role in current diagnostic histopathology. The patients were euparathyroid (n = 10), or affected by primary (n = 97), secondary (n = 8), or tertiary (n = 15) hyperparathyroidism. In normal glands, solid parenchyma was composed of chief cells, large clear cells, transitional-oxyphil cells, and oxyphil cells. Chief cell hyperplasia, pseudo-adenomatous hyperplasia, adenoma, water-clear cell hyperplasia, and carcinoma were the most usual forms of parathyroid disease responsible for primary hyperparathyroidism. In chief cell hyperplasia, all the parathyroid glands were enlarged and the chief cells were in an active state of hormone secretion, with a large Golgi complex, abundant rough endoplasmic reticulum (RER), small lipid droplets, and tortuous plasma membrane. In pseudo-adenomatous hyperplasia, one gland was enlarged and the others displayed a normal size; however, electron microscopic examination and morphometric analysis showed that all the glands had active cells. Adenomas displayed a pattern similar to those of pseudo-adenomatous hyperplasia, with one gland enlarged and the others of normal size. However, ultrastructural examination and morphometry showed that the normal-size glands were hypo-active. Water-clear cell hyperplasia showed cells filled with cytoplasmic vacuoles. In these cells, structures with intermediate features between secretory granules and vacuoles were visible. Nucleo-cytoplasmic atypias were frequently visible in parathyroid carcinoma cells. In secondary and tertiary hyperplasia, active chief cells were regularly mixed with oxyphil or transitional-oxyphil cells. The tertiary hyperplasia was characterized by RER-associated structures that were not found in the normal or other pathological conditions. These results demonstrate that electron microscopy and morphometry represent useful tools in parathyroid histopathology.
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.
The rat pericoronary adipose tissue was perfused in the presence of either the liposynthetic hormone insulin or the lipolytic hormone noradrenaline. Insulin perfusion associated with a) larger adipocyte mean sectional diameter in comparison with noradrenaline perfusion; b) glycogen deposition; c) appearance of small fat globules at discrete sites at the periphery of the main lipid drop. The two latter phenomena were apparently dose-dependent. Massive lipid deposition was induced by addition of triglycerides to the perfusion medium and this associated with appearance of prominent endoplasmic reticulum in the cytoplasm. In noradrenaline-perfused adipose tissue many small lipid droplets surrounded the central lipid deposit and the endoplasmic reticulum was in the form of both thin long, dashed cisternae sometime surrounding lipid droplets and grouped, anastomosing tubular cisternae. The present work shows that the perfused white adipose tissue of the heart is a suitable model to study, in situ, the morphological effects of hormones in adipocytes.
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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.
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.
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.
Electron spectroscopic imaging (ESI) is a recent tool for electron microscopic analysis which permits the recognition of the distribution of elements in a specimen, with a spatial resolution up to 5 nm. The authors performed the ESI together with X-ray microanalysis (EDX) and transmission electron microscopy to study granulomatous subcutaneous nodules in a patient who had undergone a desensitising therapy with an aluminium-containing vaccine. Aluminium was detected both by EDX and ESI, mainly in lysosomes of histiocytes containing needle-shaped material in a lucent matrix. However, ESI provided a better localization of aluminium with respect to EDX. This result suggests that the identification of aluminium-containing structures cannot be obtained only by ultrastructural morphology and underlines the utility of a microanalitycal study for a correct diagnosis in the presence of a needle-shaped deposition of dense material in lysosomes.
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.