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Biomedical subjects

A Giuliani

Publications and source records attributed to A Giuliani.

At least 199 records · Page 11Linked to original sources
PubMed1986

New chemical trends in ganglioside research.

A report is given of recent progress in the methodology for isolation of gangliosides from natural sources, for the preparation of molecular species of gangliosides homogeneous in both the oligosaccharide and ceramide portions of the molecule, for chemical manipulation and derivatization of gangliosides, and for the preparation of gangliosides radiolabelled in different parts of the molecule. Particular emphasis has been given to: high performance liquid chromatographic procedures capable to separate gangliosides on the basis of their oligosaccharide or ceramide moieties and yielding completely homogeneous compounds, that is gangliosides with a single oligosaccharide, a single long chain base and a single fatty acid; two-dimensional thin-layer chromatographic procedures, provided with a fully computerized quantification system, particularly suitable to identifying gangliosides containing alkali-labile linkages, including ganglioside lactones; chemical procedures of high yield for reducing gangliosides at the double bond of long chain base, for selective removal of the fatty acyl moiety and replacement with a novel fatty acid, and for the synthesis of ganglioside lactones; chemical procedures for inserting fluorescent, paramagnetic or photoreactive probes at the fatty acyl part of the ganglioside molecule; procedures for chemical isotopic radiolabelling of gangliosides at the level of sialic acid acetyl group and at the fatty acid moiety. Examples are provided evidencing the significance and potential use of a variety of ganglioside derivatives in the study of ganglioside metabolism and functional implications.

Affinity Labels↗
PubMed1986

Influence of interferon on the functional expression of natural killer target structures of murine lymphoma cells.

Murine lymphoma cells (YAC-1), induced by Moloney leukemia virus, nontreated (YAC) or pretreated in vitro with interferon (YAC-IF), were tested for their susceptibility to natural killer (NK)-mediated cytolysis. In line with previous reports YAC-IF were less susceptible to NK lysis than YAC cells. In cold competition assay, YAC-IF inhibited cytotoxicity to a lesser extent than YAC lymphoma when labeled target YAC cells were used. However, when radioactive YAC-IF cells were used as targets, cold competition attained with both YAC and YAC-IF was essentially the same. Furthermore, effector splenocytes, depleted of NK effector cells through immunoabsorption on YAC monolayer, were inactive against both YAC and YAC-IF targets. On the other hand, effector lymphocytes, absorbed on YAC-IF monolayer, retained NK activity against YAC cells but not against YAC-IF targets. These results are compatible with the hypothesis that interferon (IF) modulates negatively a subset of "interferon-susceptible" (IFS) NK target structure(s) (TS) of YAC cells, which would then express membrane determinants not functionally present on YAC-IF cells. On the other hand YAC and YAC-IF cells share "interferon-resistant" (IFR) TS not affected by pretreatment with IF. In order to test whether IFS X TS and IFR X TS are present on the same cell or clonally distributed, YAC cells were cloned and tested for NK susceptibility following IF pretreatment. The results did not support the hypothesis of a clonal distribution of both IFS X TS and IFR X TS since IF pretreatment of all clones, obtained by limiting dilution, resulted in a net impairment of target susceptibility to NK effector cells.

Animals↗
PubMed1986

A new insight into chemical mutagenesis by multivariate data analysis.

Computerized data analysis was applied to a genotoxicity data base, consisting of 42 chemicals assayed in 20 short-term mutagenicity tests. Factor and cluster analysis were used to elicit underlying patterns and to classify the chemicals in groups homogeneous for the kind of genetic damage induced. This analysis put in light a clear differentiation between effects in in vivo and in vitro systems, while the heuristic value of the traditional categories (such as point-mutation and chromosomal damage, or prokariotic and eukariotic systems) was not confirmed.

Humans↗
PubMed1985

Alpha-fucosidase-ganglioside interactions. Action of alpha-L-fucosidase from the hepatopancreas of Octopus vulgaris on a fucose-containing ganglioside (Fuc-GM1).

alpha-L-Fucosidase, prepared in highly purified form (Mr 70 000-74 000) from Octopus hepatopancreas, was able to hydrolyse a fucose-containing ganglioside, namely Fuc-GM1 (II3NeuAc,IV2Fuc-GgOse4-Cer). The enzyme showed an irregular kinetic behaviour (v/[S] and v/[E] relationships following sigmoidal curves) when working on micellar Fuc-GM1 (Mr of the micelle 500 000), but obeyed regular hyperbolic kinetics when acting on low-Mr substances. It was observed that, on incubation with micellar Fuc-GM1 under the conditions used for the enzyme assay, Octopus alpha-L-fucosidase produced a ganglioside-enzyme complex that was catalytically inactive. This complex had an Mr exceeding 500 000 and a ganglioside/protein ratio of 4:1 (w/w), which is consistent with a stoichiometric combination of one ganglioside micelle with two enzyme molecules. Inactivation of alpha-L-fucosidase by formation of the corresponding complexes was also obtained with micellar gangliosides GM1 (II3NeuAc-GgOse4-Cer), GD1a (II3NeuAc,IV3NeuAc-GgOse4-Cer) and GT1b [II3(NeuAc)2,IV3-NeuAc-GgOse4-Cer], which are not substrates for the enzyme, indicating that the ganglioside micelles per se act as enzyme inhibitors. However, alpha-L-fucosidase easily forms a Fuc-GM1-alpha-L-fucosidase complex, displaying regular Michaelis-Menten kinetics. Therefore the anomalous behaviour exhibited by alpha-L-fucosidase on micellar Fuc-GM1 is likely due to formation of the complex, which separates the fucosyl linkage from the active site of the complexed enzyme, but makes it available to the enzyme in the free form.

Animals↗
PubMed1985

Interactions of pig brain cytosolic sialidase with gangliosides. Formation of catalytically inactive enzyme-ganglioside complexes.

Cytosolic sialidase A was extracted from pig brain and purified about 2000-fold with respect to the starting homogenate (about 550-fold relative to the cytosolic fraction). The enzyme preparation provided a single peak on Ultrogel AcA-34 column chromatography and had an apparent molecular weight of 4 x 10(4). On incubation with micellar ganglioside GT1b, (molecular weight of the micelle, 3.5 x 10(5)) under the conditions used for the enzyme assay, brain cytosolic sialidase A formed two ganglioside-enzyme complexes, I and II, which were isolated and characterized. Complex II had a molecular weight of 4.2 X 10(5), and a ganglioside/protein ratio (w/w) of 4:1. This is consistent with a stoichiometric combination of one ganglioside micelle and two enzyme molecules. Complex I was probably a dimer of complex II. In both complexes I and II cytosolic sialidase was completely inactive. Inactivation of cytosolic sialidase by formation of the corresponding complexes was also obtained with gangliosides GD1a and GD1b, which, like GT1b, are potential substrates for the enzyme and GM1, which is resistant to the enzyme action. Therefore, the enzyme becomes inactive after interacting with ganglioside micelles. GT1b-sialidase complexes acted as excellent substrates for free cytosolic sialidase, as did the complexes with GD1a and GD1b.

Animals↗
PubMed1985

Cluster analysis of short-term tests: a new methodological approach.

A totally data-based approach to the evaluation of short-term tests is proposed. The performances of 22 tests over a range of 42 chemicals (data from literature) were studied by cluster analysis. The comparison between them was performed only on the basis of their responses to the chemicals. Two different clustering methods produced a coincident classification, pointing to a clear resolution of all tests into 3 groups with common characteristics. With respect to carcinogen discrimination, cluster 1 showed the highest sensitivity and the lowest specificity. Cluster 3 had opposite characteristics. The tests of cluster 2 showed intermediate features. As far as the membership to clusters is concerned, the literature data about the responses to chemicals indicated a strong test system specificity. This apparently overcame both phylogeny and end-point community. A major characteristic of the present approach is the ability to elicit underlying patterns, the knowledge of which can contribute both to hypothesis formulation and be useful for practical purposes.

Animals↗
PubMed1985

Enzymatic characterization of E.U.E. (embryonal human explants) cells adapted to hypertonic media.

E.U.E. cells (general population) were submitted to biochemical and cytoenzymatic tests to compare the enzymatic profile of E.U.E. cells (controls) with that of E.U.E. adapted to hypertonic medium. The adapted cells are characterized by very high oxoreductase activity (LDH, HBDH, G-6-P DH) and very high alkaline-phosphatase activity. Clones derived from general population were also submitted to biochemical tests to characterize those more strictly related to the enzymatic profile of adapted cells. The profile of clone N. 13 resembles on this respect that of the adapted cells. The high redox activity is a prerequisite supporting energy supply for osmotic work. The increased activity of plasma membrane enzymes of the adapted cells is also demonstrable in cells exposed for short time to salinity.

Adaptation, Physiological↗
PubMed1985

Rational approach to the evaluation of short-term tests: analysis of a homogeneous data base.

The major thrust in this study is the analysis by mathematical classification techniques of a homogeneous set of data on short-term tests. The data base generated by the International Program for the Evaluation of Short-Term Tests for Carcinogens was chosen as the model system and was studied first by cluster analysis. For this purpose, an adequate subset of data was selected and the associations between tests were explored on the basis of their performances over a range of chemicals. Then the complementary analysis of the functional relationships between the chemicals, in respect to their genotoxic effects, was performed. In both cases, a clearly structured underlying typology was brought out. Specific indications were suggested by this analysis. First, the data base studied indicated a relative independence of the performances of the assays from phylogeny and genetic endpoints. Second, the chemicals assayed were grouped together (on the basis of functional similarities) according to relationships that may represent a ground for structure-activity relationship investigations. A further important topic of this study was the quantitative evaluation of the test performances in respect to carcinogenicity prediction. To assess the effectiveness with which short-term assays can detect carcinogens and noncarcinogens, discriminant-analysis techniques were applied. On the data set considered here, the short-term tests showed 83.9% global ability to correctly classify chemicals as carcinogens or noncarcinogens. Even if these results are directly dependent on the representativity of the data set chosen, they clearly point out to the high heuristic potency of applying data-analysis techniques to genetic toxicology research.

Animals↗
PubMed1985

Primary ureteral carcinoma. Experience in a general surgical service.

Five cases (3M, 2F) of ureteral transitional cell carcinoma are reported. they have been observed in the last two years in a general surgical service. All the patients have been treated surgically. Gross hematuria was present in all the patients. Three cases had multicentric tumor sites. Three tumors were located in the distal ureter. Four cases showed a non functioning kidney at IVP. In two, because of obstruction, retrograde pyelography was unsuccessful. Ultrasound was able to demonstrate hydronephrosis. In the two cases submitted to angio-CT the spread of the tumor was correctly diagnosed. Frequency, etiology, clinical, diagnostic findings and surgical therapy as well have all been taken into account, based on the literature. Histopathologic aspects, grade and stage, are considered too. The authors emphasize the necessity to find and understand the cause of an unexplained hematuria, since ureteral carcinoma is not as rare as previously thought. Being grade and stage closely related to prognosis, the diagnostic delay must be reduced.

Aged↗
PubMed1985

Solitary pulmonary nodule: correlation between radiographic findings and nature of the lesions.

A retrospective study of 92 solitary pulmonary nodules of patients submitted to surgery is reported. The review was carried out only on chest X-rays performed prior to surgery. The radiographic signs concerning density, contour and margin were correlated with the benign or malignant nature of the lesions. 91.06% of the malignant nodules had a lobulated-umbilicated contour and ill-defined margins; 82.60% of the benign nodules had smooth contour and well-defined margins. Radiographically visible calcifications were found in 85% (6 cases) of the benign nodules, and in 15% (1 case) of the malignant ones. It is concluded that it is impossible to make a definite diagnosis of nature of SPN, due to the different types of tumor growth.

Adolescent↗
PubMed1984

Behaviour of several enzymes of lysosomal origin in human plasma during pregnancy.

The following enzymes of lysosomal origin were fluorimetrically determined in maternal plasma from the second to the ninth month of pregnancy at 1-mth intervals: beta-D-N-acetylglucosaminidase (EC 3.2.1.30), beta-D-glucuronidase (EC 3.2.1.31), beta-D-glucosidase (EC 3.2.1.21), beta-D-galactosidase (EC 3.2.1.22), alpha-D-galactosidase (EC 3.2.1.23), alpha-L-fucosidase (EC 3.2.1.51) and alpha-D-mannosidase (EC 3.2.1.24) (pH 4.0). As reference microsomal alpha-D-mannosidase (pH 5.7) was also studied. Thirty-eight healthy women, aged 18-37 yr, who had a normal pregnancy followed by normal parturition, were studied. All enzymes, with the only exception of beta-D-galactosidase, showed a progressive and statistically significant increase of activity throughout pregnancy. At the end of pregnancy, the increase ranged from a maximum of 5.6-fold for beta-D-N-acetylglucosaminidase to a minimum of 0.55-fold for alpha-D-mannosidase, pH 5.7. In the case of beta-D-N-acetylglucosaminidase, the level at the fifth month of pregnancy was significantly higher than that at the third month, and from the sixth to the ninth month each level significantly differed from that of the month immediately preceding.

Abortion, Induced↗
PubMed1984

Approaches in the study of ganglioside metabolism.

Ganglioside GM1, 3H-labeled in the sphingosine or terminal galactose moiety was injected into mice and its metabolic fate in the liver was followed. After administration of sphingosine-labeled GM1 all major liver gangliosides (GM3, GM2, GM1, GD1a-NeuAc, NeuG1) became radioactive, the radioactivity residing in all cases on the sphingosine moiety. The specific radioactivity was highest on GM1, followed by GM2, GM3 and GD1a-NeuAc, NeuG1. Several neutral glycosphingolipids and sphingomyelin were also formed. After administration of galactose-labelled GM1 the only radioactive gangliosides present in the liver were GM1 and GD1a-NeuAc, NeuG1, both carrying the radioactivity on the terminal galactose residue, with no formation of labelled neutral glycosphingolipids. Subcellular studies gave clear evidence that GM1, after being taken up by the liver, was mainly degraded to GM2, GM3 and neutral glycosphingolipids at the level of lysosomes. A part of it was sialylated to more complex gangliosides and some of its metabolic by-products were used for the biosynthesis of other sphingolipid species, likely at the level of the Golgi apparatus. All this suggests that exogenous GM1 is introduced in the metabolic routes of endogenous gangliosides and of other sphingolipids, which are operating in the liver.

Animals↗
PubMed1984

Biological monitoring of workers in the rubber industry. II. UV-induced unscheduled DNA synthesis in the lymphocytes of vulcanizers.

DNA-repair ability was estimated in a group of vulcanizers by measuring in vitro UV-induced unscheduled. DNA synthesis (UDS) in peripheral lymphocytes, and compared with that of an adequate control group. A considerable interindividual variability was shown by the UDS responses of the subjects studied both in the control and exposed population. Significantly (P = 0.0158) decreased UDS values were observed among the vulcanizers as compared to the referents. Neither age nor cigarette-smoking was observed to affect the UDS response, thus suggesting an association between the industrial exposure and decrease in the DNA-repair rate.

Cells, Cultured↗
PubMed1984

Increased immunogenicity of murine lymphoma cells following exposure to gamma rays in vivo.

Studies performed in our laboratory showed that a marked increase in immunogenicity occurred in murine lymphoma cells exposed to a mutagenic compound such as 5 (3,3'-dimethyl-1-triazeno)-imidazole-4-carboxamide (DTIC in vivo or in vitro. Subsequently, further experiments were conducted to test whether ionizing radiations would be able to affect the immunogenic properties of cancer cells in a mouse leukemia model. Male CD2F1 mice were inoculated with histocompatible L1210 Ha leukemia and treated with 400 R of total-body irradiation. A number of transplant generations were carried out with leukemic cells collected from irradiated donors, thus generating a "radiation treated line" (RTL). The immunogenicity of RTL cells increased significantly with respect to that of L1210 Ha line as early as 3 passages in vivo. However, no strong transplantation antigens comparable to those elicited by treatment with DTIC were found in RTL cells, even after a number of transplant generations. Combined effects of bis-chloroethyl-nitrosourea and weak anti-RTL responses of the host were markedly synergistic. Moreover, RTL lymphoma acquired strong immunogenic properties after a single cycle of DTIC treatment in vivo. These results may provide a model for exploiting radiation-induced increase of tumor cell immunogenicity for combined radio-immunochemotherapy.

Animals↗