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C Zancanaro

Publications and source records attributed to C Zancanaro.

At least 73 records · Page 4Linked to original sources
PubMed1989

Immunoelectron microscopical identification of the uncoupling protein in brown adipose tissue mitochondria.

The distribution of the uncoupling protein (UCP) in brown adipocyte mitochondria of the hibernant Muscardinus avellanarius was obtained by ultrastructural immunocytochemistry. In both cryosections and sections of Lowicryl-embedded material UCP was localized in the mitochondrial cristae of brown adipocytes, but not in liver mitochondria. It should now be possible to easily identify the morphology of cells committed to BAT differentiation in the tissue as well as in cell culture.

Adipose Tissue, Brown↗
PubMed1989

Basal cells of the frog's taste organ: fluorescence histochemistry with the serotonin analogue 5,7-dihydroxytryptamine in supravital conditions.

We utilized the fluorescent serotonin analogue 5,7-dihydroxytryptamine (5,7DHT) to visualize basal cells in the frog's taste organ in supravital conditions. In whole mounts of lingual mucosa, specifical and detailed morphological visualization of fluorescent basal cells was obtained in the peripheral and central region of the intact taste organ; similar results were obtained after mechanical dissociation. Preincubation with serotonin prevented any fluorescence in basal cells. Electron microscopy showed good preservation of the ultrastructural morphology of the taste disk after exposure to 5,7DHT. The advantages of the current method as compared with conventional ones are discussed. This simple, reliable procedure will be useful to further define the biology of neuroendocrine cells in taste as well as in other organs.

5,7-Dihydroxytryptamine↗
PubMed1989

Morphological identification of brown adipose tissue by magnetic resonance imaging in the rat.

Morphological distinction between brown and white adipose tissue was obtained in the rat by MRI at 7 Tesla. Both superficial (subcutaneous) and deep (mediastinal) brown fat was visualized; the level of resolution was less than 1 mm. These results show that MRI is a potentially useful tool for studying the biology of brown adipose tissue in the experimental animal and, prospectively, in man.

Adipose Tissue↗
PubMed1988

Differences in glucose metabolic enzyme activities in human adipose tissue from abdominal and gluteal regions.

In order to verify whether intersite differences exist in glucose metabolism of subcutaneous human adipose tissue, basal and insulin-stimulated 14C-1-glucose incorporation into triglycerides and the activities of some enzymes of glucose disposal were tested in abdominal and gluteal adipose tissue of 31 nondiabetic obese otherwise healthy women during isocaloric diet and after 2 weeks of very-low-calorie-protein-sparing modified diet. Basal 14C-1-glucose incorporation into triglycerides was quite similar in the adipose tissue of the two sites, and it was not influenced by dietary restriction. Insulin stimulated this metabolic activity to the same extent in both sites during isocaloric diet; after hypocaloric diet this effect of insulin was slightly decreased in adipose tissue of the abdominal site and completely abolished in the gluteal site. No enzymatic activity was different between the examined subcutaneous regions during the isocaloric diet; after very-low-calorie intake, hexokinase activity decreased in both sites, once again more markedly in the gluteal one; glucose-6-P-dehydrogenase activity decreased in the adipose tissue of the gluteal region only. These data suggest that glucose metabolism of the adipose tissue of the gluteal region is particularly decreased by severe calorie restriction. Therefore, since lipolysis does not occur at a higher rate in gluteal adipose tissue during calorie restriction, this tissue seems to undergo a resting metabolic phase during hypocaloric diet.

Abdomen↗
PubMed1988

Marginal and folliculo-stellate cells of the pituitary gland of the rat. A comparative morphometric study in lactating animals.

We examined non-granulated pituitary cells (folliculo-stellate cells and anterior and posterior marginal cells of the pituitary cleft) in lactating and virgin female rats by means of electron microscopy and morphometry. Ultrastructure and morphometric parameters of the cells lining the pituitary cleft were similar in the two groups of animals. On the contrary, folliculo-stellate cells showed a marked nucleocytoplasmic activation in lactating rats in the electron microscope, which was confirmed by morphometric measurements. These results are not consistent with the hypothesis that the three cell types share the same reactivity during pituitary hyperfunction and that they have a common function, as suggested by purely morphological studies in various endocrine conditions. We believe that quantitation of cell response during such stimuli could be useful to further elucidate this matter.

Animals↗
PubMed1988

The fine morphology of the basal cell in the frog's taste organ.

We investigated the fine morphology of basal cell in the frog's taste organ by means of transmission electron microscopy. Results show that basal cells are placed at the base of the disc and are highly polarized; the cell body is peripherally located and a long cell process reaches the central region of the taste disc without branching. The cell body contains the nucleus, the Golgi apparatus and large lysosomes; junctions between more peripherally located 'marginal' cells prevent passage of macromolecules from oral ambient to basal cells as shown by horse-radish peroxidase experiments. The cell process, running just over the basement membrane in the taste disc epithelium, is rich in microtubules, filaments and clustered secretory granules arranged near the plasmalemma. Nerves interrupting the basement membrane make synaptic-like junctions with basal cells. The cell process ends in the central region of the taste disc; here, the basal cell is expanded to contain filaments, secretory granules and mitochondria in characteristic arrangement and contacts intraepithelial nerve endings as well as basal processes of sensory and supporting cells. Marginated granules are found where basal cell contacts nerve ending and also where nerve and sensory cells contact basal cell. Our findings are consistent with the hypothesis that basal cells are under nerve control and that they may have a diffuse (paracrine) influence on neighbouring cells in the frog's taste organ.

Animals↗
PubMed1987

Effects of noradrenaline exposure on rat brown adipocytes in cultures. An ultrastructural study.

Adipocytes in intact brown adipose tissue show multivacuolar lipid deposit and mitochondria of 'typical' morphology. Cultured brown adipocytes retain the multivacuolar lipid deposit, while 'typical' mitochondria degenerate and 'atypical' organelles appear instead of the former. Since evidence exists that catecholamines deeply influence brown adipose tissue morphology and function in vivo, we undertook the present ultrastructural investigation to assess whether exposure of cultured brown fat cell to noradrenaline could prevent (or induce regression of) the in vitro morphological modifications of brown adipocytes. Brown adipocytes cultured for 8 h in the presence of noradrenaline (5 X 10(-5) M) had a larger mitochondrial area (i.e. a larger percentage of cytoplasm occupied by non-degenerating mitochondria) in comparison with control cells, as assessed by morphometry; this was due to larger number of mitochondria in noradrenaline-treated cells. Moreover, a number of cells with mitochondria strictly resembling those of the intact tissue were visible in noradrenaline-treated cultured after 8 hr, while 'typical' mitochondria were no longer observed in parallel control cultures. After 5 days of culture without hormone addition, exposure to noradrenaline (5 X 10(-5) M) did not induce quantitative modifications of 'atypical' mitochondria or changes of their ultrastructure up to 12 hr. However, reduction in size of the lipid deposit and activation of both rough endoplasmic reticulum and Golgi apparatus were evident in noradrenaline-treated adipocytes in comparison with non-treated cells.

Adipose Tissue, Brown↗
PubMed1987

Brown adipose tissue: a scanning electron microscopic study of tissue and cultured adipocytes.

The ultrastructure of rat brown adipose tissue (BAT) and of adipocytes cultured from BAT were studied by scanning electron microscopy (SEM). Brown adipocytes in the intact tissue were arranged in lobules with bundles of collagen among them; within each lobule 20- to 40-microns-large adipocytes were packed together. Fibers of reticular collagen enveloped each adipocyte and also connected each cell to vessels and nerves. At the adipocyte surface rounded protrusions were present, which corresponded to the BAT-typical multivacuolar lipid depot. Gradual digestion of the stroma with collagenase disclosed a more delicate, felt-like cover surrounding each adipocyte, probably representing the external lamina of the cell. Complete digestion of the stroma showed a smooth plasmalemma with occasional roundish blebs which varied in size. Cultured (24 h) brown adipocytes from the stromal-vascular fraction of BAT were elongated or polygonal in shape, with a flattened, central nucleus and a number of spherical cytoplasmatic inclusions which have the same dimension and location as lipid droplets. These inclusions were arranged either at cellular poles or around the nucleus; this suggests that brown adipocytes with mature features were present in the culture. Pictures suggesting the detachment of lipid droplets from the cell body were also visible. Lipid droplet extrusion could be a complementary mechanism which might explain the rapid delipidation of brown adipocytes in culture.

Adipose Tissue↗
PubMed1987

Metformin enhances insulin binding to "in vitro" down regulated human fat cells.

Insulin binding to human adipose tissue from surgical patients was determined after three different preincubation conditions: a) 24 hrs in the presence or absence of 80 ng/ml insulin; b) 24 hrs in the presence of 80 ng/ml insulin or insulin plus 4 micrograms/ml metformin; c) 48 hrs pre-incubation as in b). We found that insulin down regulated its own receptor after 24 hours pre-incubation; when metformin was present in the pre-incubation medium together with insulin, insulin binding to adipose tissue was significantly higher than in tissue exposed to insulin alone after 48 hrs pre-incubation; a similar effect of metformin was already seen after 24 hrs, but was not statistically significant. We suggest that metformin can correct down regulation of the insulin receptor. This finding could explain discrepant results among studies dealing with the influence of metformin on insulin binding. Moreover, these results could be useful in understanding the mechanism of action of metformin in insulin-resistant states, e.g. type II diabetes.

Adipose Tissue↗
PubMed1986

Effect of insulin on lipolysis in adipose tissue of rats of different ages.

Several authors have not been able to find any antilipolytic effect of insulin in adipose tissue "in vitro". We investigated the possible role of cell size and/or age of donors on this phenomenon. The lipolytic rates (glycerol release per cell) were lower in the small cells of the 4-6 weeks old rats than in the larger cells of the 25-30 weeks old animals; however, the difference disappeared when the data were expressed per unit of cell surface area. Insulin (0.5-50 ng/ml) failed to inhibit both maximally and submaximally noradrenaline stimulated lipolysis in the adipocytes of the young rats, but its antilipolytic action was fully restored by using glucose-free medium. Therefore, at our experimental conditions, a glucose dependent factor, possibly involving the preferential hydrolysis of newly synthetized triglycerides, seems to blunt or to mask the insulin induced inhibition of glycerol release. Relatively higher rates of glucose metabolism and a lower lipolysis in small fat cells might explain the difference in the action of insulin on glycerol release in the adipose tissue of young rats as compared to the older ones.

Adipose Tissue↗
PubMed1986

Ultrastructure of brown adipocytes mitochondria in cell culture from explants.

Brown adipocytes lose in culture their typical mitochondria, which are replaced by others of non typical morphology. During studies aimed at clarifying this phenomenon we found that better preservation of the 'typical' mitochondrial morphology is obtained in vitro after a long period of time, when cells from small fragments (explants) of brown adipose tissue (BAT) are cultured instead of collagenase-isolated brown adipocytes. These results suggest that the explant technique could be better suited to study brown adipocytes in culture than other methods employing collagenase-isolated cells.

Adipose Tissue, Brown↗
PubMed1984

Lack of effect of intravenous metformin on plasma concentrations of glucose, insulin, C-peptide, glucagon and growth hormone in non-diabetic subjects.

A study was carried out to evaluate the acute effect of an intravenous injection of metformin on the fasting plasma concentrations of glucose, insulin, C-peptide, glucagon and growth hormone in 15 non-diabetic subjects. Metformin (1 g) was administered as a bolus in a peripheral vein and blood was sampled 2, 5, 10, 15 and 30 minutes after the drug injection. No significant change in fasting concentration of glucose nor in C-peptide, insulin, glucagon and growth hormone fasting levels was noticed. It is concluded that metformin does not possess an acute direct hypoglycaemic effect in non-diabetic subjects and does not acutely affect the basal activity of endocrine pancreas and pituitary gland in releasing insulin, glucagon and growth hormone.

Adult↗
PubMed1984

Influence of metformin on metabolic effect of insulin in human adipose tissue in vitro.

To study the mechanism(s) of action of metformin, fragments of human subcutaneous adipose tissue were incubated with therapeutic blood concentrations of metformin. In the absence of insulin no effect of metformin was seen on either lipolysis or glucose metabolism. When insulin was present, however, metformin stimulated glucose conversion into both triglycerides and CO2. In marked contrast, no effect of metformin was observed on the antilipolytic effect of insulin. In agreement with this selective effect no change in insulin binding was found. In conclusion, metformin seems to exert its effect on glucose metabolism by potentiating the action of insulin at a post-receptor level, possibly on the rate of glucose transport.

Adipose Tissue↗
PubMedDate not supplied

Evaluation of frog gastric mucous secretion by 7T magnetic resonance imaging.

This work describes a new method to evaluate the action of drugs on gastric mucus secretion by 7 T MRI. A polyethylene probe was inserted into the stomach of frogs, a water washing cycle was performed, air was inflated into the stomach, and the probe was removed. Drugs were administered topically by mixing them with the water used for stomach washing, and a series of images was collected. In untreated animals, a mucous layer emitting a high intensity signal covered the gastric mucosa. Atropine administration strongly reduced the mucous layer thickness. After pilocarpine administration, MRI images showed that the mucous layer was thicker than in controls. After metacholine administration, the thickness of the mucous layer was increased in comparison with both controls and pilocarpine-treated animals, in accord with the expected drug-induced increase of mucous secretion. Quantitative analysis of the mucous layer thickness on MRI images confirmed the above findings. In conclusion, these results indicate that MRI at 7 T is a sensitive in vivo screening test to evaluate the effect of drugs on gastric mucus secretion in absence of surgical manipulation, thereby enabling morphofunctional studies that cannot be performed by conventional methods.

Animals↗
PubMedDate not supplied

Starvation-induced insulin resistance: influence on 3-O-methylglucose transport.

Starvation causes insulin resistance which is partly due to decrease of insulin action on glucose transport in target cells. Preliminary data from other authors suggest that starvation is associated with an increase of the time necessary for insulin to exert its maximum effect on glucose transport. In order to verify this finding, 3-O-methylglucose (3OMG) transport was studied in isolated rat adipocytes from starved and fed rats. The total intracellular space for 3OMG was not modified by 48h starvation. After 48h starvation, 3OMG transport into fat cells was less responsive to maximum insulin concentration than in controls: 33 +/- 2% (controls) vs 23 +/- 4% (starved) of total glucose space, p less than 0.05; the sensitivity to insulin was normal or even increased in comparison to controls: 50% of maximum effect was reached at 42 microU/ml insulin in controls and at 26 microU/ml insulin in starved animals. We could not find any effect of starvation on the time-response curves of insulin action.

3-O-Methylglucose↗
PubMedDate not supplied

Ultrastructural morphology of folliculo-stellate cells in human pituitary adenomas.

Fifty-six pituitary adenomas were studied by electron microscopy in a search for the presence of folliculo-stellate cells (FSCs) with the aim of evaluating their prevalence and ultrastructural morphology. FSCs were scattered in two adenomas (one oncocytoma and one densely granulated GH cell adenoma) and were numerous in a sparsely granulated GH cell adenoma; their overall prevalence was 5.4%. Ultrastructural examination of the three neoplasms revealed that FSCs were hypertrophic element with abundant cytoplasm and organelles (in contrast to FSCs of the normal pituitary) and no obvious signs of neoplastic transformation. Junctional complexes between FSCs were similar to those described in the normal gland. Numerous follicular structures were lined by FSCs. FSCs in pituitary adenomas are probably nonneoplastic, reactive cells showing signs of hyperactivity, similar to FSCs found during pituitary hypersecretion and in estrogen-induced tumor.

Adenoma↗
PubMedDate not supplied

Neuronal intermediate filaments in the developing tongue of the frog Rana esculenta.

The expression of several neuronal intermediate filament (NIF) proteins was investigated in the tongue of metamorphosing tadpoles (stage 38-45 of Gosner) and in adult individuals of the frog, Rana esculenta by means of immunohistochemistry. Results showed that nerve fibres at early stages of tongue development expressed peripherin (a NIF protein usually found in differentiating neurones) as well as the light- and medium molecular weight NIF polypeptide subunits (NF-L and NF-M, respectively); in the adult frog, peripherin was still found in nerve fibres reaching the fungiform papilla together with NF-M, but NF-L immunoreactivity was absent therein. Clusters of epithelial cells expressing peripherin were found in the early developing tongue before differentiation of taste organs, and NF-L and NF-H immunoreactivities were present in basal (Merkel) cells of the adult frog taste disc. Results indicate that neurones innervating the adult frog's taste disc maintain a certain plasticity in their cytoskeleton and that neuronal-like cells are present in the undifferentiated and differentiated tongue epithelium possibly playing a role in the developing and mature taste organ.

Animals↗