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Biomedical subjects

G Poli

Publications and source records attributed to G Poli.

At least 253 records · Page 14Linked to original sources
PubMed1986

Novel derivatives of 3 alpha,7 alpha-dihydroxy-5 beta-cholan-24-oic acid (chenodeoxycholic acid) and 3 alpha,7 beta-dihydroxy-5 beta-cholan-24-oic acid (ursodeoxycholic acid).

Several 7-acyl cheno- and ursodeoxycholic acids were obtained in good yields starting from the corresponding cheno- and ursodeoxycholic acids, by a diacylation-selective hydrolysis procedure. A superior method for the synthesis of the 7-oleyl derivatives, by a selective acylation procedure, is also presented.

Chemical Phenomena↗
PubMed1986

Lipid peroxidation and molecular damage to polyunsaturated fatty acids in rat liver. Recognition of two classes of hydroperoxides formed under conditions in vivo.

The diene conjugates formed during the autoxidation of microsomal lipid extracts, and in endoplasmic reticulum in vivo after exposing rats to CCl4 have been examined by second derivative absorption spectrophotometry. Within a few minutes after administering CCl4 to a rat there is a pronounced signal in microsomal lipid extracts that is ascribed to the cis-trans diene conjugates of microsomal polyunsaturated fatty acids. Somewhat later a second signal becomes evident that is ascribed to trans-trans isomers. The appearance of the trans-trans isomer is very strongly suppressed by prior administration of vitamin E to the rat. It is concluded that the relative contents of cis-trans and trans-trans dienes in lipid extracts of tissue reflect the tissue contents of hydrogen donors as already established for model experiments with polyunsaturated fatty acids in vitro.

Animals↗
PubMed1986

New data on kinetics of lipid peroxidation in experimental hepatomas and preneoplastic nodules.

Lipid peroxidation has been found decreased in several hepatomas. The decline has been shown already at the level of preneoplastic nodules obtained after DEN treatment of rats. A substantial exception is represented by the hepatoma cell line MH1C1, deriving from a slightly deviated Morris tumor. Most of the described experiments estimated lipid peroxidation levels in terms of malonaldehyde production by the thiobarbituric acid test. It is now clear that this test does not account for several other aldehydes produced during lipid peroxidation. We now investigated by high performance liquid chromatography (HPLC) the whole range of non-polar aldehydes produced by tumor homogenates and by preneoplastic nodules both in basal conditions and after stimulation with ADP-iron or ascorbate. It was reduced in the preneoplastic nodules as well as in the DEN-induced hepatoma. The susceptibility to the prooxidant effect of ADP-iron or ascorbate was strongly decreased in all hepatomas as well as in preneoplastic nodules. It has been recently published that hepatoma cells are more susceptible than normal liver to the toxic action of aldehydes. This was attributed at least in part to the decreased activity of aldehyde dehydrogenases, as well as to their different distribution in tumor cells. A deeper study on aldehyde metabolism in hepatomas has shown that alcohol dehydrogenase and NADPH-aldehyde reductase also are markedly decreased in Yoshida hepatoma cells and the MH1C1 cell line. However, glutathione transferase, that can use hydroxynonenal as a substrate, is strongly decreased in Yoshida hepatoma cells but not in MH1C1 cells.

Alcohol Dehydrogenase↗
PubMed1986

Increase of OKT4+ cells during treatment with thymostimulin in parenteral drug addicts with persistent generalized lymphadenopathy.

Thymostimulin (TP-1), a parenterally administered calf thymus extract, has induced a significant increase of OKT4+ peripheral cells in 9 drug addicts with persistent generalized lymphadenopathy; OKT4+ lymphocytes decreased gradually after withdrawal of treatment. In a control group, a spontaneous decrease occurred in the same period of observation. A more prolonged treatment should be undertaken to assess the effectiveness of the drug on the evolution of the disease.

Adult↗
PubMed1986

Age related changes of glucagon binding and activity in isolated rat hepatocytes.

Hepatocytes isolated from young and old rats were compared for glucagon binding and its biological effect. Liver cells from young rats showed a receptor binding of the hormone significantly higher than cells from old rats. Such a behaviour was paralleled by the activity of the hormone. In fact, the glucagon-dependent stimulation of adenylate cyclase in the hepatocytes from the former group of animals was twice as high as in the latter.

Adenylyl Cyclases↗
PubMed1986

Stimulation of the antibody response after treatment with thymomodulin in mice immunodepressed with cyclophosphamide and in aging mice.

The capacity of Thymomodulin, a thymic derivative, to restore the antibody response and the number of circulating leucocytes in immunodepressed animals was studied. Administered daily to cyclophosphamide-treated mice, Thymomodulin significantly stimulated the recovery of the antibody response to sheep erythrocytes after a second administration of the antigen. The white blood cell count also showed a rapid and significant increase. Antibody titres were enhanced to normal range values again in immunodepressed rabbits. The possible mechanism of these findings is discussed. Some preliminary results obtained in restoring the immune response in aged mice are also reported.

Aging↗
PubMed1986

Impairment of polymorphonuclear leucocyte function in patients with acquired immunodeficiency syndrome and with lymphadenopathy syndrome.

Granulocyte functions were studied in 20 patients with acquired immunodeficiency syndrome (AIDS), 20 subjects with lymphadenopathy syndrome (LAS) and 15 symptom-free drug addicts (SFDA). Polymorphonuclear leucocyte (PMNL) phagocytosis and killing of C. albicans appeared normal in homosexual men with AIDS, while drug addicts with AIDS or LAS and SFDA showed a significant defect of these functions as compared to healthy controls. Migration of PMNL in response to a chemoattractant was normal in SFDA, but markedly defective both in LAS and in AIDS patients. In the AIDS group no significant differences were evident between homosexual men and drug addicts. We conclude that defective PMNL phagocytosis and killing, unlike defective migration, are somehow related to drug abuse rather than to infection with the causative agent of the immunodeficiency.

AIDS-Related Complex↗
PubMed1985

Mechanisms responsible for carbon tetrachloride-induced perturbation of mitochondrial calcium homeostasis.

Incubation of isolated hepatocytes with CCl4 results in early reduction of the intracellular calcium content, mostly due to loss from the mitochondrial compartment. CCl4 treatment directly affects mitochondrial functions as indicated by the inhibition of Ca2+ uptake in cells permeabilized to the ion by digitonin exposure and by the reduction of intracellular ATP content in hepatocytes incubated in a glucose-free medium. Such mitochondrial damage is not caused by CCl4-induced stimulation of lipid peroxidation since it is not prevented by alpha-tocopherol, used at a concentration able to inhibit completely peroxidative reactions without interfering with CCl4 activation. All data together are in favour of a direct action of CCl4-reactive metabolites on liver cell calcium homeostasis.

Adenosine Diphosphate↗
PubMed1985

Separation and characterization of the aldehydic products of lipid peroxidation stimulated by carbon tetrachloride or ADP-iron in isolated rat hepatocytes and rat liver microsomal suspensions.

Carbonyl products were separated and identified in suspensions of rat liver microsomal fractions and in isolated hepatocytes, after stimulation of lipid peroxidation by incubation with the pro-oxidants CCl4 and ADP-iron. The carbonyl products were allowed to react with 2,4-dinitrophenylhydrazine, and the derivatives were extracted and separated by t.l.c. into three zones of non-polar materials, and one fraction of polar derivatives that remained at the origin. Separation of the individual non-polar hydrazones in each zone by h.p.l.c. demonstrated that zone I prepared from microsomal fraction or hepatocytes incubated with CCl4 or ADP-iron contained mainly 4-hydroxyhex-2-enal, 4-hydroxynon-2-enal and 4-hydroxynona-2,5-dienal. Zone III consisted mainly of the alkanals propanal, pentanal and hexanal, the 2-alkenals propenal, pent-2-enal, hex-2-enal, hept-2-enal, oct-2-enal and non-2-enal, the ketones butanone, pentan-2-one and pentan-3-one, and deca-2,4-dienal. Incubation of a microsomal fraction with ADP-iron was much more effective in producing malonaldehyde and other carbonyl products than an incubation with CCl4. Despite such quantitative differences, there were no obvious qualitative differences in the h.p.l.c. spectra obtained from zones I and III. However, the stoichiometric evaluation of fatty acid loss and the production of malonaldehyde and other carbonyls suggests that the pathways of lipid peroxidation triggered by CCl4 and ADP-iron are different. The accumulation of carbonyl products of lipid peroxidation in isolated hepatocytes is strongly affected by their metabolism; in particular, 4-hydroxyalkenals were found to be metabolized very rapidly. Nonetheless, both CCl4 and ADP-iron produced stimulation in the production of malonaldehyde and non-polar carbonyl production. After incubation of rat hepatocytes with CCl4 or ADP-iron it was found that approx. 50% of the total amount of non-polar carbonyls produced during incubation escaped into the external medium. This was not leakage from dead cells, as 90-95% of the hepatocytes had retained their integrity at the end of the incubation. Release of carbonyl products from cells stimulated to undergo lipid peroxidation may be a mechanism for spreading an initial intracellular disturbance to affect critical targets outside the parent cell.

Adenosine Diphosphate↗
PubMed1985

Carbon tetrachloride-induced inhibition of hepatocyte lipoprotein secretion: functional impairment of Golgi apparatus in the early phases of such injury.

Functional change of liver Golgi apparatus during carbon tetrachloride (CCl4) poisoning was demonstrated both in rat isolated hepatocytes and in the whole animal. The "in vitro" experimental model provided evidence of Golgi derangement early after giving the haloalkane. The "in vivo" analyses also showed that such an alteration involves both formative and secretory sides of the subcellular structure.

Animals↗
PubMed1985

Natural killer cells in intravenous drug abusers with lymphadenopathy syndrome.

We have investigated 25 intravenous drug abusers with the clinical and laboratory features of lymphadenopathy syndrome (LAS) and 10 AIDS patients for the expression of NK activity. LAS and AIDS patients had low NK cytotoxicity compared to normal donors. The defective NK cytotoxicity was analysed in the eight LAS subjects with most marked depression. NK effectors were identified by morphology (large granular lymphocytes, LGL) and monoclonal antibody-defined surface markers (B73.1, N901, HNK1). LAS patients had normal percentages of LGL and B73.1+ and N901+ cells. with the exception of two subjects with very low frequency of B73.1+ and N901+ cells. The percentage of HNK1+ cells was increased in LAS, probably because of the reactivity of this reagent with a subset of conventional OKT8+ cells, relatively augmented in LAS subjects. Depletion of monocytes did not enhance NK activity consistently. LAS patients had a normal frequency of cells capable of binding K562. In-vitro exposure to interferon beta (natural) or gamma (recombinant) augmented the defective NK activity of LAS subjects. Thus, patients with LAS have defective NK activity that cannot be accounted for by a low frequency of the relevant effector cells or by monocytic suppressors. These observations suggest a functional defect of NK cells at one or more of the post-binding steps required for the completion of killing.

Acquired Immunodeficiency Syndrome↗
PubMed1985

Monocyte function in intravenous drug abusers with lymphadenopathy syndrome and in patients with acquired immunodeficiency syndrome: selective impairment of chemotaxis.

We have investigated monocyte function in 17 intravenous drug abusers with the clinical and laboratory features of lymphadenopathy syndrome (LAS). LAS patients had normal numbers of circulating monocytes. Monocytes from LAS patients were comparable to cells from normal donors in terms of phagocytosis of latex beads, interleukin-1 secretion, O2- release and killing of antibody-sensitized lymphoma cells or actinomycin D pretreated WEHI 164 cells. In contrast 13 out of 17 LAS subjects tested in this respect as well as six out of nine AIDS patients showed a marked defect of monocyte chemotaxis. Thus monocytes from patients with LAS or AIDS have a selective defect of monocyte chemotaxis.

Acquired Immunodeficiency Syndrome↗
PubMed1985

[Transitory increase of OKT4+ lymphocytes in the peripheral blood of patients with lymphadenopathy syndrome treated with beta-interferon].

A therapeutic trial with IFN-beta (Hu. Interferon beta lyophilized, Sclavo S.p.A., Siena, Italy), administered thrice weekly but once monthly in six courses was performed for immune-modulating purposes in five parenteral drug addicts affected with lymphadenopathy syndrome. Each dose consisted of 12 X 10(6) international units I.V. Preliminary observations evidenced a significant increase of OKT4+ cells after the first course of therapy. No significant differences from the basal values, though, were found after the following courses, while in a control group of untreated LAS patients, a significant decrease of OKT4+ lymphocytes was observed. Partial remission of symptoms and/or reduction in size of the lymphatic masses were also achieved in all treated patients, although so far none of them can be considered as actually cured.

Antibodies, Monoclonal↗
PubMed1985

Rapid killing of actinomycin D-treated tumor cells by human monocytes. II. Cytotoxicity is independent of secretion of reactive oxygen intermediates and is suppressed by protease inhibitors.

Pretreatment with Actinomycin D (ActD, 1 microgram/ml for 3 hr) rendered WEHI 164 tumor cells susceptible to killing by human monocytes in a 6-hr 51Cr release assay. The present study was designed to elucidate the role of reactive oxygen intermediates (ROI) and of proteolytic enzymes in this reactivity. ActD-treated WEHI 164 cells did not trigger any measurable release of O-2 or H2O2 from monocytes. Monocytes exposed to phorbol-12-myristate-13-acetate, which enhanced release of ROI, did not show augmented killing of ActD-treated tumor cells. Scavengers of oxygen metabolites (catalase, superoxide dismutase, gluthatione, and mannitol), which inhibited ROI-mediated PMA-induced monocyte cytotoxicity against erythrocytes, did not affect monocyte killing of ActD-treated WEHI 164 cells. Enzymatically generated ROI with xanthine/xanthine-oxidase glucose/glucose-oxidase did not show preferential killing of ActD-treated WEHI 164 cells. Two patients with chronic granulomatous disease had normal levels of monocyte cytotoxicity against ActD-treated tumor cells. To determine the possible role of proteolytic enzymes in mediating this reactivity, we studied various antiproteases. Organophosphorous agents (DFP and PMSF), chloromethyl-ketone derivatives of tosylamino acids (TLCK and TPCK), Actinomyces products (pepstatin and chymostatin), and the synthetic protease substrate TAME inhibited monocyte-mediated cytotoxicity against ActD-treated WEHI 164 cells. The macromolecular protease inhibitors alpha-1 antitrypsin, bovine pancreatic trypsin inhibitor (BPTI), soybean trypsin inhibitor, and the synthetic protease substrate ATEE had little effect on monocyte cytotoxicity. When monocytes were preincubated with drugs for 1 hr and washed, TLCK, TPCK, and PMSF inhibited cytolysis, whereas the less effective chymostatin and TAME and the inactive BPTI had no effect under these conditions. Inhibition by preincubation with TLCK, PMSF, and TPCK was completely reversed after 6 hr of culture. Supernatants of monocyte cultures had lytic activity against ActD-treated WEHI 164 but not against untreated cells. Antiproteases inhibited the lytic activity of monocyte supernatants. These results strongly suggest that ROI do not play a critical role in monocyte-mediated rapid killing of drug-treated tumor cells, and that proteolytic enzymes are involved in this reactivity.

Adolescent↗
PubMed1984

Induction of cytochrome(s) P450-dependent drug metabolism in cultured MH1C1 hepatoma cells.

A cell line derived from a Morris hepatoma, MH1C1, was examined for its in vitro expression of monooxygenases. These cells were found to contain different forms of cytochrome P450, as shown by the response to inducers, namely phenobarbital (PB), 3-methylcholanthrene (MC) and metyrapone (MP). MH1C1 cell monolayers exposed to PB or MC showed an increase in the concentration of two spectrally distinct forms of cytochrome P450. The PB and MC treatments elicited enzyme activities towards the substrates aminopyrine and benzo(a)pyrene, respectively. The cell treatment with metyrapone led to a simultaneous stimulation of aminopyrine demethylase and benzo(a)pyrene hydroxylase activities, so underlining the peculiar features of this inducer.

Animals↗