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Biomedical subjects

F Pasquali

Publications and source records attributed to F Pasquali.

At least 55 records · Page 3Linked to original sources
PubMed1986

Point-mutated p21ras couples a muscarinic receptor to calcium channels and polyphosphoinositide hydrolysis.

A high-affinity muscarinic receptor is detectable both in normal 3T3 mouse fibroblasts and in their transformed counterpart obtained by transfection with the oncogene EJ/T24-H-ras. However, only the transformed cell line is responsive to muscarinic agonist carbamylcholine in terms of Ca2+ influx and polyphosphoinositide hydrolysis, whereas the normal cell line is unresponsive. Using a point-mutated p21ras protein and monoclonal antibodies anti-p21ras, we provide evidences that p21ras couples to receptor-operating calcium channels and to polyphosphoinositide hydrolysis a muscarinic receptor which is uncoupled in normal mouse fibroblasts.

Animals↗
PubMed1986

Internalization and metabolism of endogenous heparin by cultured endothelial cells.

We have studied the ability of bovine adrenal capillary cells cultured in vitro to uptake and metabolize heparin. We have previously demonstrated that endogenous heparin can be extracted from human plasma (Vannucchi, S. et al., (1985) Biochem. J. 227, 57-65), and here we show that also endothelial cells contain heparin. However, experiments with (35S)sodium sulfate labeling indicate that these cells do not synthesize de novo heparin, but they uptake it from culture serum. Bovine adrenal capillary endothelial cells are able to bind and uptake (3H)heparin added to culture medium and they also release its low molecular weight degradation products, thus indicating a metabolism of heparin. We discuss about the role of endothelial cell-mediated uptake and metabolism of endogenous heparin in relationship with circulating heparin. We also discuss about these events as related to some of the antithrombogenic properties of the endothelium.

Animals↗
PubMed1986

The Mr 17500 region of the A chain of urokinase is required for interaction with a specific receptor in A431 cells.

We have found the existence of specific receptors for the plasminogen activator, urokinase, in A431 human epidermoid carcinoma cells, cultures in plasminogen-free conditions. Two subsets of receptors have been recognized on the basis of 125I-labelled urokinase binding analysis: about 1 X 10(3) high-affinity (Kd = 5.0 X 10(-11) M) and 1 X 10(5) low-affinity (Kd = 9 X 10(-9) M) receptors per cell. The electron microscopic observation of a urokinase: ferritin conjugate has shown single and clustered receptors at the cell surface. Down-regulation of the receptors (T1/2 = 3.77 h) follows the binding of urokinase. The binding does not involve an intact catalytic site and is inhibited by a monoclonal antibody against the Mr 17500 proteolytic fragment of the A chain of urokinase.

Amyloid beta-Protein Precursor↗
PubMed1986

A 45,X male with a Yp/18 translocation.

A patient described as a 45,X male (Forabosco et al. 1977) was examined for the presence of Y-specific DNA by using various probes detecting restriction fragments from different regions of the Y chromosome. Positive hybridization signals were obtained for Yp fragments only. In situ hybridization with two different probes, pDP31 and the pseudoautosomal probe 113F, led to a clear assignment of the Yp sequences to the short arm of one chromosome 18. Cytogenetically, the presence of all of Yp including the Y centromere on 18p could be demonstrated replacing a segment of similar size of 18p. Thus, the Y/18 translocation chromosome is dicentric structurally, but it was shown to be monocentric functionally with the no. 18 centromere active. Gene dosage studies with the probe B74 defining a sequence at 18p11.3 demonstrated a single dose of this sequence in the patient. In agreement with these observations, the patient shows clinical signs of the 18p-syndrome. It is concluded that in XO males in general, the X is of maternal origin while the maleness is due to a de novo Y/autosome translocation derived from the father. Depending on the nature of the autosomal deficiency caused by the Y/autosome translocation, the patient may have congenital malformations.

Child↗
PubMed1986

Chromosomal aberrations in lymphocyte and fibroblast cultures of patients with the sporadic type of Kaposi sarcoma.

Numerical and structural chromosomal aberrations were found in metaphases from lymphocyte cultures from Sardinian patients with the sporadic type of Kaposi sarcoma, and also in fibroblasts derived from cultured biopsies of the tumoral lesions. In several cases there was evidence of clonal evolution of some of the chromosomal aberrations. The chromosomes most frequently involved in numerical aberrations were 10, 13, 15, 22 and the X and Y chromosomes, and those most frequently involved in translocations and deletions were 7, 13, 15, 22 and the X chromosomes. The hypothesis is made that in Kaposi sarcoma the chromosomal instability and clonal evolution in vivo could be modulated by the immunologic situation peculiar to the condition.

Aged↗
PubMed1986

Different break-points in Philadelphia chromosome variant translocations and in constitutional and sporadic translocations.

Three different samples of translocations were considered in an attempt to identify those chromosomal bands preferentially involved in variant Philadelphia chromosome (Ph1) translocations, and to compare them with bands preferentially broken in constitutional and sporadic translocations. The first sample included 204 cases of variant Ph1 translocations with 221 identified break-points (bp), the second consisted of 106 cases of non-Robertsonian constitutional translocations with 213 bp identified, and the third one of 185 bp identified in sporadic translocations found occasionally in single cells of subjects with normal karyotypes and without haematological disorders. A statistical analysis demonstrated that there are some bands preferentially broken in each of the samples, and this with a high level of significance (P less than 0.001). The analysis of the distributions of the chi 2 components permitted us to identify the 12 bands preferentially involved in variant Ph1 translocations and the 13 and 9 bands preferentially involved in constitutional and sporadic translocations, respectively. The comparison among the groups of preferential bp showed that the bands most involved in the three samples are different. Some theoretical problems related to the origin of the Ph1 chromosome are discussed.

Chromosome Banding↗
PubMed1986

Flow cytometric evaluation of proliferative activity and ploidy in myelodysplastic syndromes and acute leukemias.

Propidium iodide (PI) DNA distribution of bone marrow (BM) cells was studied by flow cytometry (FCM) in 36 patients without hematologic or malignant disease (normal BM) and in 172 patients with anemias (36 pts), myelodysplastic syndromes (MDS) (33 pts) and acute leukemia (AL) at diagnosis (60 pts), remission (24 pts) and relapse (19 pts). White blood cells from normal male subjects were used as an external diploid reference standard (median CV = 3.8). Patients with normal BM, anemias, MDS and acute leukemia at diagnosis had tritiated thymidine labeling index (LI) and most with MDS and AL had also evaluable cytogenetics performed on the same BM sample used for FCM. In normal BM, median aliquot of cells with PI-DNA content intermediate between the diploid and the tetraploid value (2n-4n cells %) was 15.7. The ratio between the fluorescence intensity of the G0/1 peak of normal BM cells and the fluorescence intensity of the G0/1 peak of the reference standard (FI ratio) ranged from 93 to 1.05 (mean +/- 2SD). The 2n-4n cell % was higher than normal in anemias (p less than .001), lower in leukemias (p less than .001) and widely scattered in MDS. A linear correlation was found between 2n-4n cell % and LI, with 2n-4n cell % value higher than LI. The FI ratio was lower than normal in anemias (p less than .05), higher in AL with normal cytogenetics (p less than .02) and broadly scattered in MDS with normal cytogenetics. From our experience, PI-DNA-FCM is a simple and adequate method to evaluate proliferative activity in hematologic diseases. Nevertheless, caution must be taken in attributing small changes in FI ratio to aneuploidy, since they are found in anemias and in MDS and AL with normal cytogenetics, possibly due to differences in PI uptake by different cell types.

Acute Disease↗
PubMed1985

Transformation of BALB/3T3 cells with EJ/T24/H-ras oncogene inhibits adenylate cyclase response to beta-adrenergic agonist while increases muscarinic receptor dependent hydrolysis of inositol lipids.

Balb/3T3 murine fibroblasts transformed by transfection with the EJ/T24 human bladder carcinoma oncogene were assayed in terms of adenylate cyclase response and hydrolysis of polyphosphoinositides dependent on specific agents. Transformed cells were much less responsive to beta-adrenergic agonists in rising cAMP than normal cells. They are instead much more sensitive to muscarinic receptor agonists, inducing a rapid intracellular accumulation of inositol phosphates. These results suggest that the functional alteration of the cell membrane caused by the product of the point mutated H-ras oncogene concerns in 3T3 fibroblasts both inhibitory and stimulatory effects, respectively on adenylate cyclase and phosphoinositide-phosphodiesterase.

Adenylyl Cyclases↗
PubMed1985

[Glycosaminoglycans in pleural effusions. Preliminary results].

Distinction between benign and malignant pleural effusions is often a very difficult problem. Glycosaminoglycans play an important role in cellular proliferation and differentiation. The authors examined glycosaminoglycans in 17 samples, 11 malignant and 7 benign. Separation of glycosaminoglycans has been achieved by centrifugation-addition of trichloracetic acid-centrifugation-addition of cold ethanol. Glycosaminoglycans have been analyzed by electrophoresis on cellulose acetate sheets. 6 malignant samples had higher levels of HA and CS than standard. The authors distinguished benign effusions in two subgroups: inflammatory and cardiac. Among inflammatory, 3 had higher levels of HS and 1 of HA and CS. Further investigations are necessary to elucidate possible different patterns.

Aged↗
PubMed1985

Effects of cortisone with and without heparin on angiogenesis induced by prostaglandin E1 and by S180 cells, and on growth of murine transplantable tumours.

Cortisone acetate, locally applied in sustained-release pellets, is effective in inhibiting angiogenesis induced by prostaglandin E1 in the rabbit cornea. The inhibitory effect of cortisone is not increased by addition of heparin. Similar results were obtained with angiogenesis induced by S180 cells. The effects of cortisone with and without heparin were also studied on 5 transplantable murine tumours: 3 variants of B16 melanoma, Lewis lung carcinoma and fibrosarcoma M4. The effect of cortisone in slowing the growth rate of tumours was modestly potentiated by heparin, but no regression of the tumour mass occurred.

Alprostadil↗
PubMed1985

Cytogenetic pattern in leukemic cells of patients with constitutional chromosome anomalies.

Acquired karyotypic changes analyzed by banding techniques in 21 patients with a malignant hematologic disorder and a major constitutional chromosome anomaly, including ten patients with trisomy 21, five patients with a balanced translocation, and six patients with a sex chromosome anomaly. Detailed karyotypic findings were ascertained in 28 additional patients reported in the literature. Some striking differences were observed in the combined material of the present series and cases previously published as regards (a) distribution of morphological leukemia types among patients with different types of constitutional anomalies, and (b) incidence and type of acquired chromosomal abnormality among patients with different types of constitutional anomalies.

Adolescent↗
PubMed1985

Plasminogen activator: morphological evidence of binding, internalization and delivery to lysosomes in 3T3 mouse fibroblasts.

Using a direct conjugate of urokinase and ferritin, the binding has been followed at the plasma membrane and the internalization of urokinase into BALB/C-3T3 fibroblasts, cultured in plasminogen-free conditions. At 0 degree C, the conjugate was observed bound on both coated and uncoated cell surface regions as singlets, and small and large clusters. No binding was observed in the presence of excess native urokinase. The binding was impaired by preincubation of the conjugate with a competitive inhibitor of the catalytic site, suggesting an interaction between the receptor and the catalytic site of the enzyme. Within 1 min at 37 degrees C, urokinase clustered on coated regions of the plasma membrane. At 5 min after warming, ferritin was found on deeply indented coated pits and in both coated and uncoated vesicles close to the cell surface. By 10 min at 37 degrees C, ferritin particles were present in uncoated endosomes and in multivesicular bodies in the Golgi area. Within 10 min, the receptors on the surface strongly decreased. New receptors were observed on the membrane after 20 min at 37 degrees C. At this time, ferritin was observed both in endosomes or multivesicular bodies and in vesicles close to the plasma membrane.

Animals↗
PubMed1985

Reconstitution of the complement channel into lipid vesicles and planar bilayers starting from the fluid phase complex.

Proteolysis of the fluid phase complement complex SC5b-9 transforms it into an amphiphilic molecule which resembles the membrane attack complex of complement and reconstitutes into lipid vesicles. Complement-containing vesicles prepared in this way can be made to fuse with planar lipid bilayers transferring their protein content to the host membrane. Massive conductance increases can thus be observed, which are due to the insertion of a large number of ionic channels into the membrane. Using low concentrations of vesicles, single channels can be studied.

Animals↗
PubMed1984

Cooperative effect of exogenous heparin-like compounds and secreted glucocorticoid-induced inhibitor on plasminogen activator in 3T3 cell cultures.

Balb/c 3T3 cultures grown in the absence of serum release both plasminogen activator and plasminogen activator inhibitor in the culture medium. Cellular transformation with SV-40 virus increased the level of the activator, whereas dexamethasone increased the level of the inhibitor. Heparin added to the medium potentiated the glucocorticoid-induced inhibitory activity, strongly decreasing or completely abolishing the activity of plasminogen activator. Heparin sulfate showed similar effects to heparin, although at higher concentrations. It is suggested that heparin-like compounds are involved in the regulation of plasminogen activator, acting as inhibitory cofactors.

Animals↗
PubMed1984

Electrical properties of ionic channels formed by Helix pomatia hemocyanin in planar lipid bilayers.

Helix pomatia hemocyanin forms ion-conducting channels in planar lipid bilayer membranes when added at mg/ml concentration. These channels have several original features. They fluctuate between one conducting and some poorly conducting states and fluctuations can be grouped in bursts. Different channels can have widely different conductance amplitudes. Both channel conductance and burst lifetime are dependent on the applied voltage. Fluctuations within a burst show a complex kinetic behaviour which has been explained developing a multistate model. The model calls for one single open state and six different closed states. Transitions are allowed only between one of the closed states and the open one and obey first order kinetics. This model is able to fit all our experimental curves obtained in single channel experiments.

Animals↗
PubMed1983

Involvement of chondroitin sulphate in preventing adhesive cellular interactions.

Glycosaminoglycans isolated from native non-adhesive surfaces of both endothelial and mesothelial origin and from endothelial cells cultured in vitro were analyzed by electrophoresis and characterized by chemical and enzymatic breakdown. All the surfaces examined expose in vivo chondroitin 6-sulphate as the main glycosaminoglycan. Under in vitro culture, the exposure of chondroitin sulphate is reduced. Paper chromatography of hydrolysis products upon degradation by chondroitinase AC shows equal amounts of both 6- and 4-sulphated disaccharides. At the same time, the surfaces lose their non-adhesiveness to leukocytes. The addition of fibroblast growth factor to endothelial monolayers restores both non-adhesiveness to leukocytes and exposure of chondroitin sulphate. These results seem to indicate that the exposure of chondroitin sulphate is important in preventing cellular adhesion.

Cell Adhesion↗