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Biomedical subjects

G Gazzanelli

Publications and source records attributed to G Gazzanelli.

At least 37 records · Page 2Linked to original sources
PubMed2000

Matrix metalloproteinases expression in HL-60 promyelocytic leukemia cells during apoptosis.

Human promyelocytic leukemia HL-60 cells have been used as a model to study both the expression of matrix-metalloproteinases and the mechanisms of programmed cell death. In the present study we examined the expression of these proteases in HL-60 cells stimulated by different apoptotic triggers. As shown by zymography, HL-60 cells released three major isofroms of the matrix-degrading proteases; when the leukemic cells were grown in serum-free conditions, as well as after hyperthermia and methotrexate treatment, we found a significant loss of the constitutive production of the 92 kDa matrixmetalloprotease, with an unequivocable molecular and ultrastructural evidence of programmed cell death. These results suggest that in HL-60 cells the expression/release of matrix metalloproteases can be down-regulated in the presence of the apoptotic-induced alterations, and that the decreased matrix-degrading capacity of this leukemic cell line during apoptosis may reduce its invasive potential.

Apoptosis↗
PubMed2000

Prostate-specific antigen synthesis and secretion by human placenta: a physiological kallikrein source during pregnancy.

Prostate-specific antigen (PSA), a kallikrein-like serine protease until recently thought to be prostate specific, has been demonstrated in various nonprostatic tissues and body fluids. PSA has been also found in human endometrium and amniotic fluids, even if the significance of this novel expression is unclear. In this study, we have demonstrated by multiple techniques that human placental tissue, obtained at delivery from normal full-term pregnancies, synthesizes and secretes PSA. RT-PCR showed the presence of PSA messenger ribonucleic acid; biochemical, chromatographic, and immunological studies revealed the expression of both free and complexed PSA forms; immunoelectron microscopy indicated the syncytiotrophoblast as the site of PSA synthesis and secretion. Moreover, in vitro experiments demonstrated that PSA production and secretion are up-regulated by 17beta-estradiol, a pregnancy-related steroid hormone. These results suggest that human placenta is a source of the PSA present in amniotic fluid and maternal serum during pregnancy.

Adult↗
PubMed1999

Nuclear bodies are usual constituents in tissues of hibernating dormice.

In previous studies we demonstrated in several tissues of the hazel dormouse Muscardinus avellanarius that during hibernation cell nuclei contain particular structural constituents absent in euthermia. In the present study we examine the same tissues in euthermic and hibernating individuals of the edible dormouse Glis glis in order to investigate possible modifications of nuclear structural constituents occurring during hibernation in this species. Edible dormice were captured in the wild and maintained in an external animal house. Samples of liver, pancreas, brown adipose tissue and adrenal cortex were taken from three hibernating and three euthermic animals and processed for resin embedding. Ultrastructural and immunocytochemical studies were carried out on cell nuclei of these tissues. The most evident feature of cell nuclei of hibernating dormice was the presence of several nuclear bodies, namely fibro-granular material, amorphous bodies, coiled bodies, perichromatin granule-like granules and nucleoplasmic fibrils, the distribution of which was peculiar to each tissue. No one of these constituents was detectable during euthermia. Immunocytochemical analyses revealed that they contain some splicing factors. Apart from some differences, maybe due to the different characteristics of lethargy, the nuclear bodies found in edible dormice were morphologically and immunocytochemically similar to those previously described in the same tissues of hazel dormice. They therefore seem to be strictly correlated to the hibernating state. If they represent storage and/or assembly sites of splicing factors to be rapidly used upon arousal, they could represent a usual structural feature in cells of hibernating species.

Adipose Tissue, Brown↗
PubMed1999

Growth factors stimulate the activity of key glycolytic enzymes in isolated digestive gland cells from mussels (Mytilus galloprovincialis Lam.) through tyrosine kinase mediated signal transduction.

Digestive gland cells isolated from mussels (Mytilus) have previously been demonstrated to respond to mammalian EGF with a cytosolic Ca(2+) transient and stimulated DNA synthesis; both responses were mediated by activation of tyrosine kinase receptors. The present study examines the mechanisms involved in further signal progression and possible targets of phosphorylation/dephosphorylation processes. The effects of EGF, IGF-I, and insulin on the activity of two key glycolytic enzymes PFK (phosphofructokinase) and PK (pyruvate kinase) were evaluated. All the peptides tested induced a transient and dose-dependent stimulation of the activity of both PFK and PK, which involved activation of MAPKs. Quantitative immunoelectron microscopy, utilizing monoclonal anti-phosphotyrosine antibodies, revealed that EGF induced a transient increase in tyrosine phosphorylation. The results demonstrate that, in marine invertebrate cells, activation of tyrosine kinase membrane receptors by growth factors triggers signal transduction pathways involving a phosphorylative cascade similar to that of mammalian cells. Moreover, these data suggest that, in mussel cells, growth factors may play a physiological role in the in vivo regulation of glucose metabolism by modulating, through reversible phosphorylation, the activity of key glycolytic enzymes.

Animals↗
PubMed1999

Prostate-specific antigen found in type I breast cyst fluids is a secretory product of the apocrine cells lining breast gross cysts.

Prostate-specific antigen (PSA), a serine protease thought to be exclusively produced by the prostate epithelial cells, has been recently found in human breast tissues and fluids. PSA in breast cancer is associated with the presence of steroid-hormones and receptors, and its presence seems to be a favourable prognostic indicator. In order to clarify whether the cells lining breast cysts may represent the source of PSA found in human breast cyst fluid, we performed an ultrastructural immunolocalization of PSA in the cells surrounding Type I breast cysts, obtained from breast cyst fluids of women affected by breast gross cystic disease, the most commonly occurring benign breast lesions associated with increased cancer risk. These apocrine cells show morphological features typical of actively synthesizing and secreting cells, and a PSA labelling distributed on free ribosomes, RER cisternae, and secretory granules, indicating that the metabolically active apocrine cells lining the Type I cysts are responsible for the production and secretion of PSA in Type I breast cyst fluids. The synthesis and intracystic accumulation of this serine protease in biosynthetically active apocrine Type I cysts can play an important role in the natural history of breast gross cystic disease as well as in the mechanism of cyst evolution.

Adult↗
PubMed1999

Immunoreactivity, ultrastructural localization, and transcript expression of prostate-specific antigen in human neuroblastoma cell lines.

Prostate-specific antigen (PSA) is considered a highly specific biochemical marker of the human prostate gland, and it currently is used for prostate cancer diagnosis and monitoring. Recently, PSA production and secretion were found in nondiseased and diseased cells, tissues, and fluids from women. In this study, we characterized the presence of PSA in two human neuroblastoma cell lines with biochemical, ultrastructural, and molecular approaches. Using reverse transcription-PCR, we identified PSA mRNA, and Western blotting revealed a substantial amount of complexed form of PSA protein, which is localized mainly in free ribosomes. Although the role of PSA in human neuroblastoma cell lines is still unknown, our study supports the hypothesis that this serine protease may be involved in controlling the growth of human brain tumor cells, adding more support to the notion that PSA is a widespread kallikrein-like protease with biological functions much more complex than recently thought.

Blotting, Western↗
PubMed1998

GABA transporter-1 (GAT-1) immunoreactivity in the cat periaqueductal gray matter.

Using light- and electron-microscopic immunocytochemistry, we investigated the regional distribution and the ultrastructural localization of GAT-1, a prominent GABA transporter, in the cat PAG. Light microscopic observations indicate that GAT-1-immunoreactive elements are particularly dense in PAG-DL and form a pair of longitudinal columns extending in the intermediate region of this structure. At electron-microscopic level, GAT-1 immunoreactivity was present in axon terminals forming symmetric synapses and in the distal processes of astroglial cells. These data further confirm the existence of longitudinal columns within PAG. They also indicate that GAT-1 could influence the action of GABA on its receptors, probably regulating the magnitude and duration of GABA's synaptic action on PAG neurons, and suggest that astrocytes may play an important role in this process.

Animals↗
PubMed1998

Ultrastructural, morphometrical and immunocytochemical analyses of the exocrine pancreas in a hibernating dormouse.

Pancreatic acinar cells of euthermic, hibernating and arousing individuals of the hazel dormouse Muscardinus avellanarius (Gliridae) have been observed at the electron-microscopic level and analysed by means of ultrastructural morphometry and immunocytochemistry in order to investigate possible fine structural changes of cellular components during periods of strikingly different degrees of metabolic activity. During hibernation, the cisternae of the rough endoplasmic reticulum (RER) flatten assuming a parallel pattern, the Golgi apparatus is extremely reduced and the mitochondria contain many electron-dense particles. The cell nuclei appear irregularly shaped, with deep indentations containing small zymogen granules. They also contain abundant coiled bodies and unusual constituents, such as amorphous bodies and dense granular bodies. Large numbers of zymogen granules occur in all animals. However, the acinar lumina are open and filled with zymogen only in euthermic animals, whereas, in hibernating and arousing individuals, they appear to be closed. Morphometrical analyses indicate that, in pancreatic acinar cells, nuclei and zymogen granules significantly decrease in size from euthermia to hibernation, probably reflecting a drastic decrease of metabolic activities, mainly protein synthesis and processing. In all the studied animals, immunocytochemistry with specific antibodies has revealed an increasing gradient in alpha-amylase content along the RER-Golgi-zymogen granule pathway, reflecting the protein concentration along the secretory pathway. Moreover, during deep hibernation, significantly larger amounts of alpha-amylase accumulate in RER and zymogen granules in comparison to the other seasonal phases analysed. Upon arousal, all cytoplasmic and nuclear constituents restore their euthermic aspect and all morphometrical and immunocytochemical parameters exhibit the euthermic values, thereby indicating a rapid resumption of metabolic activities.

Amylases↗
PubMed1998

Ultrastructural characterization and biochemical profile of human gross cystic breast disease.

Human gross cystic breast disease is a benign condition affecting about 7-10% of adult women occurring with the highest incidence in the premenopausal decade. Although breast cysts do not represent a preneoplastic condition per se, several studies indicate an increased breast cancer risk in women affected by this pathology. In this report we study 115 breast cystic fluid samples obtained by needle-aspiration from women with gross cystic breast disease. The samples were analysed biochemically and the cells contained therein were observed at the electron microscope. According to their biochemical profiles, the cysts were subdivided into three types: Type I, showing a Na/K ratio < 0.5 and a typical protein content; Type II, showing a Na/K ratio >10 and a protein content quite similar to plasma; Type III, showing a Na/K ratio between 1 and 7 and an intermediate protein content. The electron microscopic examination demonstrated that Type I cystic fluid cells exhibit morphological features typical of actively synthesising and secreting cells, while the characteristics of Type II cells indicate a low metabolic activity. Type III cells have characteristics typical of both Type I and Type II cells, thereby confirming the intermediate nature of this cyst type. We hypothesise that these cyst types could represent different developmental stages of a structural evolution pathway, during which the biosynthetically active 'apocrine stage' would be the key step to cell neoplastic transformation.

Adult↗
PubMed1997

Glutamate-positive neurons and terminals in the cat periaqueductal gray matter (PAG): a light and electron microscopic immunocytochemical study.

The morphology, distribution, proportion, size, and synaptic organization of periaqueductal gray matter neurons labeled with immunocytochemical techniques by an anti-glutamate (Glu) polyclonal serum were investigated in six adult cats (PAG-GLU 1-6). At the light microscopic level, numerous Glu-positive neurons were found throughout each subdivision of the periaqueductal gray matter. Their proportion and size, calculated in semi-thin sections (1-microm-thick), varied slightly among the subdivisions of the periaqueductal gray matter. The morphology of Glu-positive neurons was similar to that of the multipolar, triangular, and fusiform cells described in previous Golgi studies. Numerous puncta, interpreted as dendrites, axons, and axon terminals were also present in all subdivisions without preferential distribution. At the electron microscopic level, all synaptic contacts made by Glu-positive axon terminals were of the asymmetric type, but not all presynaptic elements making asymmetric synapses were labeled. The vast majority of postsynaptic elements contacted by Glu-positive axon terminals were labeled and unlabeled dendrites. The present results describe for the first time the presence of both Glu-positive neurons and terminals in the feline periaqueductal gray matter and provide further evidence that Glu is the probable neurotransmitter of numerous excitatory neurons of this structure.

Animals↗