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Biomedical subjects

E Mariani

Publications and source records attributed to E Mariani.

At least 55 records · Page 3Linked to original sources
PubMed1998

Age-dependent decreases of NK cell phosphoinositide turnover during spontaneous but not Fc-mediated cytolytic activity.

The progressive increase in the number of peripheral NK cells found in the elderly does not correlate with a corresponding increase in lytic activity. On the contrary, a decreased function of circulating NK cells purified from old subjects was observed on a per cell basis. Most of the studies on NK cells have focused on late events such as lytic activity. In view of this, little is currently known about the modification of the early signalling pathways of NK cells in elderly people. This study investigated whether the modification of NK lytic activity could be related to differences in the metabolic pattern of activation of these cells in the elderly. NK cells were negatively purified by immunomagnetic depletion from the peripheral blood of selected old and young healthy subjects. Hydrolysis of inositol phospholipids was measured following incubation with K562 target cells and/or CD16 mAb for different times. Our data show that there is a pronounced age-related decrease in the ability to generate total inositol monophosphates and, particularly, inositol trisphosphates by NK cells following K562 stimulation (spontaneous cytolytic activity) together with an attenuated and delayed hydrolysis of phosphatidylinositol bisphosphate, while phosphoinositide turnover is preserved following Fc triggering (antibody-dependent cell-mediated cytotoxicity). These results confirm that, also in old subjects, different biochemical pathways of activation are involved in NK cells when target or antibody-mediated triggering occurs and may aid the development of experimental and therapeutic strategies to counteract declines in cell mediated immune functions associated to advancing age.

Adult↗
PubMed1998

TNF-alpha but not IL-1 and IL-6 modifies the susceptibility of human osteosarcoma cells to NK lysis.

TNF-alpha-treated osteosarcoma cells have an enhanced susceptibility to NK lysis which mostly depends on the increased expression of CD54 molecules. Since IL-1 and IL-6 share overlapping biological properties with TNF-alpha, we investigated whether the treatment of osteosarcoma cells with these cytokines could modify their susceptibility to NK lysis and whether these modifications were related to a different distribution of CD54, CD56 and CD58 molecules. We demonstrated that the expression of CD54 and CD58 on osteosarcomas correlated positively with the susceptibility to NK lysis and that this susceptibility was enhanced by TNF-alpha treatment but not by IL-1 and IL-6 stimulation.

CD56 Antigen↗
PubMed1997

Human osteosarcoma cell susceptibility to natural killer cell lysis depends on CD54 and increases after TNF alpha incubation.

Osteosarcoma cell lines vary widely in their susceptibility to natural killer (NK) cell lysis in vitro although it is still unclear why this occurs. In this study we investigated the expression of some cell adhesion molecules on osteosarcomas to determine which of these can modify the susceptibility to NK lysis and we also attempted to modulate the cytolytic susceptibility of these targets with TNF alpha. We found that osteosarcoma lysis induced by NK cells correlates with different expression of the CD54 adhesion molecule on osteosarcomas and the increased susceptibility after TNF alpha treatment mostly depends on the expression of CD54 molecules on target cells.

Adult↗
PubMed1997

Epitope specificity of Th0/Th2 CD4+ T-lymphocyte clones induced by vaccination with rHBsAg vaccine.

BACKGROUND & AIMS: Different amino acid sequences of hepatitis B virus surface antigen (HBsAg) are involved in the activation of CD4+ lymphocytes needed to induce an optimal antiviral function. The aim of this study was to characterize the CD4-mediated response to immunodominant HBsAg epitopes in hepatitis B virus (HBV) vaccine recipients by defining minimal sequences recognized by T cells, cytokine profiles, and HLA restriction of peptide recognition. METHODS: T-lymphocyte lines and clones specific for HBsAg were isolated from the peripheral blood of subjects immunized with recombinant HBsAg and stimulated in vitro with synthetic peptides spanning the whole HBsAg sequence. RESULTS: Four immunodominant epitopes (sequences 21-40, 136-155, 156-175, and 211-226) were identified. Using panels of truncated peptides of different length, sequences 21-28, 165-172, and 215-223 were shown to correspond to the minimal epitopes recognized by T cells. The antigen-specific T-lymphocyte proliferation was HLA class II restricted, and each peptide could be presented in association with different HLA class II determinants. Th0/Th2 cytokine patterns were induced on peptide stimulation. CONCLUSIONS: These results indicate the presence of at least four immunodominant epitopes within HBsAg that represent potential candidates for the design of anti-HBV synthetic vaccines.

Adult↗
PubMed1997

Expression of beta-galactoside alpha 2,6-sialyltransferase does not alter the susceptibility of human colon cancer cells to NK-mediated cell lysis.

The extent of processing of N-linked oligosaccharides and the sialylation of the target cell membranes has been positively correlated with resistance to lysis mediated by NK cells, but a conclusive evidence has never been reached. Colon cancer tissues express an increased activity of beta-galactoside alpha 2,6-sialyltransferase (EC 2.4.99.1, alpha 2,6ST), which catalyzed the addition of sialic acid in alpha 2,6-linkage to Gal beta 1,4GlcNAc (N-acetyllactosamine) sequences of glycoprotein N-linked chains. The resulting increased level of membrane alpha 2,6-sialylation appears to be related with a more invasive behavior of cancer cells. This phenomenon may depend on a decreased sensitivity of colon cancer cells to NK cells. To obtain conclusive evidence on the role played by sialylation of N-linked chains in determining the target cell susceptibility to NK-mediated lysis, human colon cancer cell lines not expressing sialyltransferases acting on N-linked chains were transfected with a rat alpha 2,6ST cDNA. Stable transfectants expressed different levels of alpha 2,6ST activity, were reactive with the Sambucus nigra lectin, specific for alpha 2,6-linked sialic acid, and compared with control transfectants, showed a remarkable decrease in the number of unsubstituted Gal beta 1,4GlcNAc terminal sequences. The NK susceptibility of these clones was found to be identical to that of control transfectants, either when unstimulated- or IL-2-stimulated lymphocytes were used as effectors. Neuraminidase treatment of target cells does not result in significant changes to NK susceptibility. Our data demonstrate that sialic acid alpha 2,6-linked to N-linked chains of target cell glycoproteins does not play a major role in recognition of the target by human NK cells.

Amino Sugars↗
PubMed1996

Perforins in human cytolytic cells: the effect of age.

The ageing process is associated with a progressive increase in the number of circulating NK cells, together with a decreased lytic activity per cell. A similar decrease in activity was also found for CD8 lymphocytes. Cytotoxic T- and NK cells express cytoplasm granules containing cytolytic effector molecules (as perforins, studied here) which can recognize and destroy damaged, infected and/or mutated target cells. To investigate whether an altered distribution of perforins in cytolytic cells or a reduced number of cytolytic cells producing perforins underlies decreased cytolytic activity with advancing age, perforin expression was assessed at the single cell level in T- (CD4 and CD8) and NK (CD16) peripheral blood lymphocytes from elderly subjects by flow cytometry. Perforin distribution at the cellular level in CD8+ and CD16+ cell cytoplasm suggested a similar distribution during ageing and a similar number of cells producing perforins. In addition, perforin utilization was maintained in the generation of cytolytic activity against K562 target cells and perforin synthesis in culture following activation was unabated. These data stress the importance of other factors, such as defective signal transduction for granule exocytosis, that may account for the different pattern of lytic activity found in aged people.

Adult↗
PubMed1996

Synthesis of ethylammonium iodides of omega-dialkylaminoethyl ethers of 5-(arylmethylene)-1,3,3-trimethyl-2-oxabicyclo [2.2.2.] octan-6-hydroxyimines as potential cosmetic ingredients.

The synthesis of nine quaternary ammonium iodides derived from omega-dialkylaminoethyl ethers of 5-(arylmethylene)-1,3, 3-trimethyl-2-oxabicyclo[2.2.2]octan-6-hydroxyimines, as potential cosmetic ingredients, is described. They are routinely prepared starting from cineole aminoethers by reaction with iodoethane and their physics-chemical data are reported. These substances were studied for their UV absorption and three of these compounds were also submitted to microbiological assays on five test organisms. The substances have their UV absorption maxima at 284-321 nm, and one compound is active on Staphylococcus aureus, Streptococcus faecalis and Candida albicans. These preliminary findings seem to indicate that some of these compounds could be considered as potential UV sunscreens; one compound, having a moderate antimicrobial activity, could be considered a potential active compound in cosmetics as deodorants, toothpastes, mouthwashes and other oral care products.

Anti-Infective Agents↗
PubMed1996

Synthesis and pharmacological activity of some N,N-disubstituted 1-amino-2-phenyl-3H,12H-naphtho[1,2-b]pyrano[2,3-d]pyran-3-ones.

The synthesis of some N,N-disubstituted 1-amino-2-phenyl-3H,12H-naphtho[1,2-b]pyrano[2,3-d]pyran-3-ones 4, by reaction of phenylchloroketene with a series of N,N-disubstituted 3-aminomethylene-2,3-dihydro-4H-naphtho[1,2-b]pyran-4-ones, followed by dehydrochlorination in situ of the primary adducts with DBN, is described. Some compounds 4 showed antiarrhythmic and analgesic activities.

Anti-Arrhythmia Agents↗
PubMed1996

Biological parameters influencing the immunological response to plasma derived and recombinant hepatitis B vaccines.

Personnel (1856 subjects) belonging to local health units (medical and paramedical staff) that have been vaccinated since 1984 against hepatitis B virus (HBV) with HBsAg plasma purified preparations (Hevac-B and H-B-Vax) or recombinant DNA preparation (Engerix-B) were followed in plasma anti-HBs antibody levels. At the end of the protocols, different seroconversion percentages and different anti-HBs levels were reached: the best results were obtained with Engerix-B. Sex and principally age influenced the antibody production: women generally reached highest protective antibody levels and the 21-30 year group was more responsive than other groups. The injection of a supplementary 4th or 5th dose in low or non-responders could restore the specific immunity in the majority of the subjects and increase the anti-HBs level. The time course after the immunization of antibody levels depended on the level reached at the end of vaccination schedule. These data suggest that different antibody level monitorings of vaccinated subjects, planned on the basis of the antibody level reached at the end of vaccination, could prevent a loss of protection against the HBV infection.

Adult↗
PubMed1995

Visual evoked potentials in NIDDM: a longitudinal study.

In order to assess the possible progression of neurological abnormalities over time and the value of visual evoked potential alterations in predicting stability and severity of diabetes-related optic pathway disease, a longitudinal study in non-insulin-dependent diabetic patients was performed. Neurological examination, visual evoked potentials with pattern reversal, motor and sensory nerve conduction velocities and metabolic control were studied in 18 non-insulin-dependent diabetic patients and in 35 normal control subjects at baseline and again after 4.6 +/- 0.8 years (range 4-6). At the first recording the peak P100 wave latencies were significantly delayed in the diabetic patients compared with the control subjects; signs of peripheral neuropathy were detected in five patients, clinical in three and in two there was only neurophysiological alteration without clinical signs. The second recording revealed no significant alterations of P100 latencies in patients compared with baseline, but the number with clinical signs and/or neurophysiological alterations with no clinical signs of peripheral neurological disease was increased to seven. In conclusion, we observed that visual evoked potential alterations were stable over time whereas peripheral neurological disease progressed and correlated positively with metabolic control.

Case-Control Studies↗
PubMed1995

Cycloocta[b]pyran derivatives with local anesthetic, platelet antiaggregating and other activities.

The synthesis of some N,N-disubstituted 4-amino-5,6,7,8,9,10-hexahydro-3- phenyl-2H-cycloocta[b]pyran-2-ones by reaction of phenylchloroketene with a series of N,N-disubstituted 2-aminomethylenecyclooctanones, followed by dehydrochlorination in situ of the primary adducts with DBN, is described. The dimethylamino derivative showed a local anesthetic activity in mice superior to that of lidocaine, and some compounds exhibited a platelet antiaggregating activity in vitro superior or comparable to that of acetylsalicylic acid, as well as weak antiarrhythmic and antiinflammatory activities in rats.

Anesthetics, Local↗
PubMed1994

Distribution and lytic activity of NK cell subsets in the elderly.

Old subjects present an increased number of NK cells associated with a decreased lytic activity of isolated and cloned CD16 cells. Recently, two new surface molecules of 58 kDa, identified by the monoclonal antibodies GL183 and EB6, have been described. The presence of these molecules, which can be coexpressed on CD16+ cells allows the recognition of the NK cell subsets whose cytolytic activity is restricted to different allospecificities. This study investigated a group of old subjects to determine whether a particular distribution or a different lytic activity of NK subsets, defined by MoAbs GL183 and EB6, is involved in the altered cytolytic activity found during ageing. Further, we investigated whether the ageing process might be responsible for a restriction of the NK cell repertoire involved in the recognition of allogenic cells. We found that old and young subjects have a similar proportion of double positive and double negative GL183/EB6 cells, while in the old group single positive subsets were increased. The lytic activity of sorted NK subsets isolated from old and young subjects was similar, although double positive and double negative cells from the old presented a lower cytotoxic activity. The addition of IFN-beta or rIL-2 to the culture medium restored the lytic activity to the level found in young subjects. These data show that the decreased NK lytic activity found in the old subjects is shared out among the different NK subsets and normal aged subjects do not lose the NK repertoire found in the young.

Aged↗
PubMed1994

Standardization of a micro-cytotoxicity assay for human natural killer cell lytic activity.

Cytotoxicity assays are widely used to evaluate the functional activity of NK and T cells against tumour target cells and the release of radioactive sodium chromate from labelled target cells is still the most commonly used marker of target lysis in culture supernatants. We describe here the standardization of a micro-cytotoxicity test in which the number of cytolytic effector and tumour target cells have been decreased by a factor of 10. The release obtained by 500 tumour target cells was compared with the release obtained by 5000 target cells in the standard cytotoxicity assay for target:effector cell ratios from 1:1 to 1:100. Both gamma and beta emissions of the 51Cr isotope were evaluated to determine the assay release. The results obtained by the micro-cytotoxicity assay (500 target cells) were comparable to those of the standard assay (5000 target cells) and 51Cr release evaluation using the gamma counter was the most sensitive method of determining lytic activity using 500 tumour target cells. beta counter evaluation using solid phase scintillation was found to be a reproducible alternative method, even if the lytic curves cannot be compared with those obtained using the traditional method.

Chromium↗
PubMed1994

Discrete localization of different DNA topoisomerases in HeLa and K562 cell nuclei and subnuclear fractions.

Monoclonal antibodies raised against DNA topoisomerase I and against topoisomerase II alpha and beta isoforms, which have been previously demonstrated to be highly specific and capable of detecting cell cycle-related variations of the topoisomerase II isoforms (Negri et al., 1992, Exp. Cell Res. 200, 452-459), have been utilized for a fine subcellular localization. Immunocytochemistry by confocal and electron microscopy have been used for a topological and quantitative evaluation of the fine distribution of the different topoisomerases in HeLa and K562 cells. Topoisomerase I and topoisomerase II alpha are present both in the nucleoplasm and in the nucleolus, though at different relative ratios, while topoisomerase II beta is exclusively present at the nucleolar level. This is further confirmed by immunoblotting and immunocytochemical quantitative evaluations performed on purified nuclear matrix fractions obtained from K562 cells. In fact, the amount of topoisomerase I and topoisomerase II alpha present in the whole cell nuclei is partly lost in isolated nuclei but, while topoisomerase I is further significantly reduced in nuclear matrix preparations, the topoisomerase II alpha content is only slightly decreased. On the other hand, the great majority of topoisomerase II beta is retained in the nuclear matrix and can be detected exclusively in association with the nucleolar remnant. These results are consistent with specific functional roles hypothesized for the different topoisomerase types.

Antibodies, Monoclonal↗
PubMed1994

Intracellular Cu/Zn superoxide dismutase levels in T and non-T cells from normal aged subjects.

The decreased immune response associated with aging may, in part, reflect intrinsic age-related biochemical alteration in lymphocytes from older subjects. The 'reactive oxygen species hypothesis' of aging postulates that these molecules are involved in the modifications leading to cellular senescence. Superoxide dismutase (SOD), and in particular the Cu/Zn-dependent intracellular form, plays a critical role in the defense against these species, but it is controversial whether this function declines in lymphocytes in old age. We utilized two different methods to evaluate Cu/Zn SOD levels in T and non-T cells (CD3+, CD3-, CD4+, CD8+, CD16+) from young and old individuals: a specific and sensitive enzyme immunoassay performed on extracts of sorted cells, and a flow cytometry double fluorescence technique with monoclonal antibodies against Cu/Zn SOD and the different lymphocyte subsets. The Cu/Zn SOD cell content was assayed both in basal conditions and after peripheral blood lymphocyte stimulation with Concanavalin A, anti-CD3 monoclonal antibody and phorbol myristate acetate. In basal conditions, and considering the various subsets, no differences were found between young and old individuals, although data analysis revealed high and low responders in both groups. Taking all the subjects together, higher levels of this enzyme were found in CD3+ T lymphocytes, in particular in the CD4+ cells. After peripheral blood lymphocyte stimulation, Cu/Zn SOD concentration was higher than levels in unstimulated cells, both in young and old individuals, and particularly using Concanavalin A with respect to anti-CD3 and phorbol myristate acetate. In conclusion, the synthesis of Cu/Zn SOD does not seem to be affected by aging in proliferating cells. The highest levels of Cu/Zn SOD present in CD4+ cells, both from young and old individuals, may prevent the oxidant stress of these elements which play a major role in the inflammation sites.

Adult↗
PubMed1994

O-(2-dialkylaminoethyl)oximes of 5-(arylmethylene)-1,3,3-trimethyl-2-oxabicyclo [2.2.2]octan-6-ones with hypotensive, antiarrhythmic and other activities.

The synthesis of some O-(2-dialkylaminoethyl)oximes of 5-[(4-methoxy- or 4-methylthiophenyl)methylene]-1,3,3-trimethyl-2-oxabicyclo[2.2.2] octan-6-ones 5 by reaction of the corresponding oximes as sodium salts with the appropriate 2-chloroethyldialkylamine in dry ethanol solution is described. Some aminoethers 5 showed appreciable hypotensive and antiarrhythmic activities in rats, as well as a weak platelet antiaggregating activity in vitro and a moderate infiltration anesthesia in mice.

Anesthetics, Local↗