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D Ricci

Publications and source records attributed to D Ricci.

At least 55 records · Page 3Linked to original sources
PubMed1997

Mechanical and morphological properties of living 3T6 cells probed via scanning force microscopy.

Scanning Force Microscopy (SFM) is utilized to study living confluent 3T6 cells. Images based on mechanical contrast are obtained and related morphological details, mostly regarding the cell cytoskeleton, are analyzed. Moreover, numerical estimates of the local mechanical properties of the living cells are given, by extensive use of the "force-vs.-distance" operation mode. On the basis of the results obtained, the potentialities of SFM as an optimal new technique available for probing the cell cytoskeleton of unstained living cells, and assessing related models, are shortly discussed.

Actins↗
PubMed1997

Changes of nuclear PI-PLC gamma1 during rat liver regeneration.

We have previously demonstrated that rat liver nuclei contain PI-PLC beta1 and gamma1 in the inner nuclear matrix and lamina associated with specific phosphodiesterase activity (Bertagnolo et al., 1995, Cell Signall. 7, 669-678). Since compensatory hepatic growth is an informative and well characterized model for natural cell proliferation, the presence of specific PI-PLC isoforms and their activity as well as PIP2 recovery were studied at various regenerating times, ranging from 3 to 22 h after partial hepatectomy. Three PI-PLC isoforms (beta1, gamma1, delta1) were examined in control and regenerating liver cells by using specific antibodies. By means of in situ immunocytochemistry and confocal microscopy, PI-PLC beta1 was found mainly in the nucleoplasm and this pattern was not modified after hepatectomy. On the contrary, the nuclear gamma1 isoform showed a marked decrease at 3 and 16 h after hepatectomy, but a clear increase at 22 h covering with bright intensity the whole nucleus. The PI-PLC delta1 isoform, which is exclusively cytoplasmic, was not altered during rat liver regeneration. By western blotting analysis on whole cell homogenates, none of the PI-PLC isozymes under study showed proliferation-linked modification. However, analyses of isolated nuclei identified changes in the nucleus associated PI-PLC gamma1 that paralleled the in situ observation whereas the beta1 isoform was unmodified at all the times examined. Nuclear phosphodiesterase activity on PIP2 was lower at 3 and 16 h, in comparison with sham operated rats, increased at 6 h and reached the highest value after 22 h. Consistently, the recovery of PIP2, obtained in conditions that optimise PIP-kinase activity, showed a marked decrease at 3 h and an increase up to 16 h of liver regeneration, followed by a further decrease at 22 h. These data are consistent with a close relationship between cell proliferation and the nuclear inositide cycle, depending, in rat liver, predominantly on the modulation of the gamma1 isoform of PI-PLC.

Animals↗
PubMed1997

Inositol 1,4,5-trisphosphate distribution in Lycopersicon esculentum Mill seedlings cultivated "in vitro" under different conditions.

Measurements of inositol 1,4,5-trisphosphate (Ins1,4,5-P3) in cotyledons, epicotyls and roots of tomato seedlings grown "in vitro" either in the light or in the dark indicated that higher concentrations of this signal-transducing molecule are contained in hypogeous vs. epigeous tissues. The same was observed in induced cotyledon explants grown in the light in the presence of growth regulators. Data concerning phosphatidylinositol metabolism in seedling roots are also reported. Taken together, our results may be helpful in understanding the role of the polyphosphoinositide signal system in plants.

Calcium Chloride↗
PubMed1997

Bile salt-induced cytotoxicity and ursodeoxycholate cytoprotection: in-vitro study in perifused rat hepatocytes.

OBJECTIVES: Membrane toxicity induced by hydrophobic bile salts may be important in liver diseases. Administration of ursodeoxycholate reduces serum liver enzymes in chronic liver diseases, but the nature of this effect is still unclear. We aimed at establishing a convenient in-vitro system for investigating the hepatotoxic properties of hydrophobic bile salts and the putative hepatoprotective effect of ursodeoxycholate. METHODS: About 100 mg of freshly isolated rat hepatocytes were suspended on a resin column (Bio-Gel P4 fine) and perifused with different concentrations of bile salts. The effluent was collected at 5-min intervals and assayed for lactate dehydrogenase (LDH), aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activity. Enzyme leakage induced by bile salts was compared with that induced by Triton X-100 (Union Carbide, Danbury, CT, USA) at different concentrations. After perifusion, hepatocytes were collected for electron microscopic observation. RESULTS: Cytotoxicity of individual bile salts, assessed by enzyme release, was time and concentration dependent and corresponded to their hydrophilic-hydrophobic balance. Perifusion with hydrophilic bile salts, cholate and ursodeoxycholate, did not result in a significant enzyme release in concentrations up to 5 mmol/l, whereas hydrophobic bile salts, chenodeoxycholate and deoxycholate, induced significant enzyme leakage even in low concentrations, 0.5 and 0.1 mmol/l, respectively. Addition of ursodeoxycholate significantly reduced the hepatotoxic effect of deoxycholate. This protective effect was evident within minutes. The ultrastructural appearance of hepatocytes exposed to hydrophobic bile salts was very similar to the non-specific cellular lysis observed after exposition to Triton X-100, suggesting that they act mainly in a detergent-like fashion. CONCLUSION: Perifused rat hepatocytes seem a convenient in-vitro system for investigating the hepatotoxic properties of bile salts and hepatoprotective effect of ursodeoxycholate, offering the opportunity to investigate the effects of bile salts under dynamic conditions, mimicking the in-vivo situation, and allowing continuous enzyme release monitoring. Hydrophobic bile salts seem to act mainly in a detergent-like fashion; ursodeoxycholate-related hepatoprotection could be due not only to a dilution effect of toxic bile salts, but also to a direct cytoprotective effect.

Animals↗
PubMed1996

Brain alpha 1-adrenoceptor in the cardiovascular responses to BHT-920 and phenylephrine.

1. It is well known that alpha 1A-adrenoceptors have binding sites for imidazolic and for phenylethylaminic drugs. A study was made relating alpha 1A-adrenoceptor involvement in cardiovascular responses to intracerebroventricular (ICV) injection of BHT-920, an imidazoliclike drug, and phenylephrine, a phenylethylaminic drug, in conscious sham-operated and sinoaortically-denervated rats. 2. In sham-operated rats, cardiovascular responses to BHT-920 (30 micrograms, ICV) were increase of blood pressure and bradycardia but in sinoaortically denervated rats, after the pressor response, a decrease of blood pressure was also seen. The pressor and bradycardic responses to agonist were greater in sinoaortically denervated rats than in sham-operated rats. Phenylephrine (90 micrograms, ICV) showed a biphasic effect on blood pressure: an increase followed by a decrease, and bradycardia. The cardiovascular responses to phenylephrine in sinoaortic-denervated rats were greater than in sham-operated rats. 3. In sinoaortically denervated and sham-operated rats subchronically treated with the alpha 1-adrenoceptor antagonist prazosin (0.5 mg kg-1, intraperitoneally twice daily, for 6 days), an increase of cardiovascular responses to ICV administration of BHT-920 and phenylephrine was seen. 4. Baroreceptor deafferentation by sinoaortic denervation enhances the cardiovascular responses to BHT-920 and phenylephrine. The effects of BHT-920 could be mediated by brain alpha 1A adrenoceptors because this agonist has an imidazoliclike structure; phenylephrine could also be activating central alpha 1A-adrenoceptors. The enhanced cardiovascular responses after prazosin treatment could also be due to a supersensitivity of brain alpha 1A-adrenoceptors.

Adrenergic alpha-Agonists↗
PubMed1996

Nuclear phosphoinositide-specific phospholipase C, phosphatidylinositol 4,5-bisphosphate and protein kinase C during rat spermatogenesis.

Presence and intracellular distribution of phosphoinositide-specific phospholipase C, phosphatidylinositol 4,5-bisphosphate and protein kinase C have been investigated in rat maturing germ cells and spermatozoa. The isoforms beta 1 and gamma 1 of phosphoinositide-specific phospholipase C were immunologically identified and found to be predominantly nuclear or cytoplasmic and nuclear, respectively. The two enzymes were present in the maturing cell lineage of the seminiferous tubule, except for the nucleus of late spermatids, and absent in spermatozoa, in which, however, a phosphoinositide-specific phospholipase C activity persisted, due to yet uncharacterized enzyme(s). Protein kinase C paralleled these developmental changes, and was completely down-regulated in both total cell homogenates and isolated nuclei obtained from spermatozoa. On the contrary, phosphatidylinositol 4,5-bisphosphate, present at the nuclear level in all cell types, accumulated in the nuclei of late spermatids and spermatozoa. These data support the contention that the spermatozoon nucleus stores a lipid-dependent signaling apparatus which could be reactivated either during sperm maturation or at fertilization.

Animals↗
PubMed1995

Identification of PI-PLC beta 1, gamma 1, and delta 1 in rat liver: subcellular distribution and relationship to inositol lipid nuclear signalling.

The subcellular distribution of PI-PLC beta 1, gamma 1, and delta 1 has been investigated in rat liver by western blot and immunohistochemical analysis with a panel of isoform-specific antibodies. The data obtained in situ on cryo-sectioned tissue indicate that PI-PLC beta 1 is predominantly nuclear, while gamma 1 is largely cytoplasmic and delta 1 is sharply restricted to the cytoplasm. In fractionation experiments, the Western blot analysis indicated that the recovery of the nuclear isoforms beta 1 and gamma 1 was not affected by the removal of the nuclear membrane, and that the two enzymes persisted in nuclear matrix and lamina, obtained after nuclease digestion and extraction with high salt and detergent. The assay of the phosphodiesterase activity in different cell fractions correlates with the observed relative abundance of the enzymes, and specific inhibition with neutralizing anti-beta 1 and -gamma 1 isoforms confirms that these are the enzymes active at the nuclear level. These results demonstrate that in rat liver cells, as in other cell types, different members of the PI-PLC family show a discrete intracellular distribution, and suggest that PI-PLC beta 1 and gamma 1 play a central role in modulating the nuclear phosphoinositide cycle.

Animals↗
PubMed1995

Hairy cell leukemia without splenomegaly nor myelofibrosis in a patient with gastric adenocarcinoma: early phase of the disease or a variant?

The first case of patient affected both by gastric carcinoma and hairy cell leukemia (HCL) is reported. From a clinical standpoint, this 54-year old man presented with striking leukopenia without splenomegaly. From a morphological point of view, the infiltration by leukemic cells occurred in the hypoplasic areas of the bone marrow biopsy (BMB) without increase in reticulin fibers. From these observations the authors deduce that: 1) BMB in many cases is the only morphologic tool for diagnosis and prognosis of HCL; 2) probably the "hypoplasic" variant of HCL will become more frequent, because of the increasing indication to BMB in course of pancytopenia, even in absence of splenomegaly; 3) our case is probably related more to an early phase of the disease than to a distinct variant. In addition, we propose that the co-existence of an aggressive solid tumor and HCL could be related to the immunosuppressive action by hairy cells.

Adenocarcinoma↗
PubMed1995

Increased sinusoidal wall permeability and liver fatty change after two-thirds hepatectomy: an ultrastructural study in the rat.

Accumulation of lipids in the hepatocyte cytoplasm after partial hepatectomy (PH) has long been recognized, but the mechanism behind this phenomenon is still poorly understood. In this study, rats subjected to a standard two-thirds PH showed early and marked increase in portal venous pressure (P < .01). On scanning electron microscopy, the regenerating liver fixed by portal perfusion under hemodynamic conditions identical to that found in vivo during the first 24 hours showed a significant (P < .01) 10-fold increase in the sinusoidal wall porosity (percentage open area by fenestrations). This was paralleled by the disappearance of the sieve-plate arrangement of small fenestrations and by a significant decrease in the number of fenestrations per micrometers squared of sinusoidal surface at 6 (P < .01) and 12 hours (P < .05). In addition, there were major changes in the frequency and distribution of all three classes of fenestrations. At 6 and 12 hours, there was a marked decrease of small class 1 fenestrations and a marked increase of intermediate class 2 fenestrations and large class 3 fenestrations (P < .0001). A concurrent accumulation of lipid droplets in the hepatocyte cytoplasm produced a 20-fold increase in the hepatocyte total lipid volume. A statistically significant linear correlation (r = 0.907; P < .01) was found between the amount of intracellular lipids and the data quantitating the changes in porosity of liver sinusoids at 24 hours. It is concluded that an increased sinusoidal wall permeability to lipids may be the primum moves in the pathogenesis of transient liver fatty change after PH in the rat.

Animals↗
PubMed1995

Bone marrow biopsy in 50 AIDS patients: a diagnostic approach.

Fifty bone marrow biopsies (BMB) and aspirates (BMA) of AIDS patients were examined to identify possible morphologic signs of HIV infection. The following parameters were evaluated: 1) cellularity; 2) myelo-erythroid ratio (M:E); 3) morphology of haemopoietic lineages; 4)plasmacell amount; 5) lymphocytes amount; 6)reticulin content. Hypercellularity, increase in number and morphological alterations of megakaryocytes, raised reticulin content, mild plasmacytosis and frequent presence of reactive lymphoid aggregates are features suggestive, thought not diagnostic, for HIV infection on BMB. It results that bone marrow morphologic examination in HIV-positive patients plays a distinctive role in ruling out the presence of opportunistic infections or associated neoplasias (haematologic or not) and in contributing to clarify the significance of a peripheral pancytopenia.

Acquired Immunodeficiency Syndrome↗
PubMed1994

A randomized comparison of coronary-stent placement and balloon angioplasty in the treatment of coronary artery disease. Stent Restenosis Study Investigators.

BACKGROUND: Coronary-stent placement is a new technique in which a balloon-expandable, stainless-steel, slotted tube is implanted at the site of a coronary stenosis. The purpose of this study was to compare the effects of stent placement and standard balloon angioplasty on angiographically detected restenosis and clinical outcomes. METHODS: We randomly assigned 410 patients with symptomatic coronary disease to elective placement of a Palmaz-Schatz stent or to standard balloon angioplasty. Coronary angiography was performed at base line, immediately after the procedure, and six months later. RESULTS: The patients who underwent stenting had a higher rate of procedural success than those who underwent standard balloon angioplasty (96.1 percent vs. 89.6 percent, P = 0.011), a larger immediate increase in the diameter of the lumen (1.72 +/- 0.46 vs. 1.23 +/- 0.48 mm, P < 0.001), and a larger luminal diameter immediately after the procedure (2.49 +/- 0.43 vs. 1.99 +/- 0.47 mm, P < 0.001). At six months, the patients with stented lesions continued to have a larger luminal diameter (1.74 +/- 0.60 vs. 1.56 +/- 0.65 mm, P = 0.007) and a lower rate of restenosis (31.6 percent vs. 42.1 percent, P = 0.046) than those treated with balloon angioplasty. There were no coronary events (death; myocardial infarction; coronary-artery bypass surgery; vessel closure, including stent thrombosis; or repeated angioplasty) in 80.5 percent of the patients in the stent group and 76.2 percent of those in the angioplasty group (P = 0.16). Revascularization of the original target lesion because of recurrent myocardial ischemia was performed less frequently in the stent group than in the angioplasty group (10.2 percent vs. 15.4 percent, P = 0.06). CONCLUSIONS: In selected patients, placement of an intracoronary stent, as compared with balloon angioplasty, results in an improved rate of procedural success, a lower rate of angiographically detected restenosis, a similar rate of clinical events after six months, and a less frequent need for revascularization of the original coronary lesion.

Angioplasty, Balloon, Coronary↗
PubMed1994

Scanning force microscopy on live cultured cells: imaging and force-versus-distance investigations.

Extensive measurements with the scanning force microscope on living cells in their native liquid environment are described with the purpose of critically assessing the extent of the interaction between the SFM tip and the (soft) cell materials and the effect of such interaction on topographic information. Images are obtained under various force conditions and systematically correlated with force-versus-distance curves. As a result, detailed indications about tip indentation are given, thickness estimates deduced and identification of submembranous cytoplasmic structures suggested.

Animals↗
PubMed1994

[Monoclonal gammopathies: differential diagnosis with bone marrow biopsy].

Aim of the present study is to examine the morphological aspects of monoclonal gammopathies (GM) detectable by bone marrow biopsy. With reference to Multiple Myeloma (MM), the more important disease of this group from a clinical standpoint, other conditions will be later evaluated. Particular attention will be given to Monoclonal Gammopathy of Undetermined Significance (MGUS) that still today is characterized by wide shadows concerning both ethiology and evolution significance.

Biopsy↗