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Biomedical subjects

R Cavallo

Publications and source records attributed to R Cavallo.

At least 55 records · Page 3Linked to original sources
PubMed1993

Effect of interferon-alpha on immediate early gene expression of murine cytomegalovirus.

Interferon-alpha (IFN-alpha) significantly reduced the replication of murine cytomegalovirus (MCMV) in mouse embryo fibroblasts derived from the susceptible mouse strain C3H/HeJ. When infectious virus production was measured, a strong decrease in virus titer was observed in IFN-treated cells at a multiplicity of infection (moi) of 1 and 0.5 pfu/cell. Analysis of virus-specified mRNAs by Northern blot assay revealed that IFN-alpha had a significant effect on the expression of viral mRNAs at 48h. In particular, the mRNAs of the major immediate early (IE) transcription units, IE1, IE2, and IE3, were impaired by IFN-alpha. In addition, decrease of IE1 mRNA synthesis was accompanied by a reduction of the major IE product (pp89), as revealed by Western blot assay. These results suggest that IFN-alpha may inhibit MCMV replication by directly impairing IE gene transcription.

Animals↗
PubMed1991

Intrathymic lymphoid cell differentiation in myasthenia gravis: an immunophenotypic study.

Thymocytes express multiple different surface antigens according to their stage of maturation. We studied lymphocyte surface differentiation antigens using direct immunofluorescence technique in the thymus of 20 patients with myasthenia gravis (MG) and 10 controls undergoing cardiac surgery. Fluorescein isothiocyanate-conjugated monoclonal antibodies were used to stain thymic cell surface antigens. We found a decrease in the percent expression of CD1, CD5, and CD7 surface antigens and a significant increase of CD20+ cells in myasthenic thymus compared with the controls. The changes in the percent expression of CD3, CD4, and CD8 antigens were not significant. These data suggest both the decrease in the immunophenotypes corresponding to cortical thymocytes (probably reflecting the cortical atrophy of the MG thymus) and the increase of mature B Cells (CD20+), which may participate in an active immune response.

Adult↗
PubMed1991

CD8+ high CD11b+ low T cells (T suppressor-effectors) in multiple sclerosis cerebrospinal fluid are increased during high dose corticosteroid treatment.

Using simultaneous dual direct immunofluorescence the effect of high dose intravenous methylprednisolone on the expression of T lymphocyte differentiation antigens in paired cerebrospinal fluid and peripheral blood samples of nine clinically active patients with multiple sclerosis was studied. Corticosteroid treatment was associated with a clinical improvement in eight out of the nine patients. In cerebrospinal fluid of all patients the treatment was associated with a decrease of CD3+, CD4+ and CD8+ T cells, and of intra-central nervous system IgG synthesis. CD8+ high CD11b+ low suppressor-effector T cells behaved differently in the eight patients who improved with treatment, where they significantly increased, and in the patient without clinical response, where they were almost unchanged. Similar phenotypic changes were found in peripheral blood, and all changes returned towards baseline after treatment. The lower sensitivity to corticosteroids of CD8+ high CD11b+ low T cells could change the balance between immunoregulatory T subsets. In this study the increased availability of a subpopulation mainly composed of T cells with a suppressor-effector function was associated with a clinical response to treatment.

Adrenal Cortex Hormones↗
PubMed1991

In-vitro activity of quinolones against different species of staphylococci of recent clinical isolation.

We considered 256 strains of S. aureus (SA) and S. non-aureus (SnA) of recent clinical isolation. Their susceptibility (S) or resistance (R) to pefloxacin, ciprofloxacin, enoxacin, ofloxacin (which have been used in therapy for several years) and to timentin as well, has been tested, in relation with methicillin susceptibility (MS) and methicillin resistance (MR). To date, the activity of quinolones against all staphylococci remains relatively high, notwithstanding the appearance of resistant strains, in particular among MR SnA. Of the four quinolones examined, ofloxacin showed to be the most active, i.e. effective against 100% of the staphylococci, either SA or SnA.

4-Quinolones↗
PubMed1990

Increased thymocyte differentiation in myasthenia gravis: a dual-color immunofluorescence phenotypic analysis.

Thymocytes express multiple, different surface antigens according to their stage of maturation. Surface differentiation antigens have been studied with the technique of simultaneous dual-color, direct immunofluorescence in the thymuses of 20 patients with myasthenia gravis (MG) and 10 control subjects with cardiac diseases. Fluorescein isothiocyanate-conjugated and phycoerythrin-conjugated monoclonal antibodies were used to stain thymic cell suspensions. A significant decrease in the percentage of immature and common thymocyte phenotypes (CD1+,3+ and CD4+,8+) and a significant increase in the percentage of mature thymocyte phenotypes (CD1-,3+; CD4+,8-; and CD4-,8+) and of B cells (CD20+) were found in MG thymuses compared with controls. These data, indicating an increased availability of mature, fully immunocompetent T and B cells, indirectly suggest the occurrence of an active immune response in MG thymus.

Adult↗
PubMed1988

Circadian variations of interferon-induced enhancement of human natural killer (NK) cell activity.

We searched for circadian changes in the enhancement of the NK activity after exposure to IFN-gamma of peripheral blood mononuclear (PBM) cells obtained serially throughout the 24-h cycle. In August-October 1986, blood was drawn from 7 healthy, diurnally active and nocturnally resting male volunteers (22-34 yr) at 4-h intervals for 24 h starting at 08:00. PBM cells were immediately separated and assayed for NK cell activity, using K 562 cultured cells as a target in a 4-h 51Cr release assay after prior incubation for 20 h with buffer or 300 IU rIFN-gamma. Circadian variations of the spontaneous NK cell cytotoxicity were apparent; the activity was at its maximum at the end of the night or in the early morning and then declined in the afternoon. The 24-h rhythmic pattern was validated with statistical significance by the Cosinor method (p less than 0.02; acrophase 04:22). Maximum enhancement by IFN-gamma was attained in the second part of the night or in the early morning, i.e. in phase with the peak of the spontaneous NK cell activity. A significant circadian rhythm of the percent increase above control levels was validated by the Cosinor method (p less than 0.01; acrophase 04:03). Our findings may be of relevance to a better understanding of the mechanisms of control of human NK activity and warrant consideration as an approach to improve the effectiveness of time-qualified immunotherapy.

Adult↗
PubMed1987

Inhibition by cortisol of human natural killer (NK) cell activity.

The effects of cortisol on the natural killer (NK) activity of human peripheral blood mononuclear (PBM) cells were studied in vitro using a direct 4-h 51Cr-release assay and K 562 cell line as a target. Preincubation for 20 h of PBM cells drawn from healthy donors with 1 X 10(-8) to 1 X 10(-5) M cortisol resulted in a significant decrease of NK cell activity. The magnitude of the suppression was directly related to the steroid concentration and inversely related to the number of effector cells. Cortisol was able to minimize the enhancement of NK cytotoxicity obtainable in the presence of immune interferon (IFN-gamma). A significantly higher suppression was achieved after sequential exposure of PBM cells to cortisol and equimolar levels of prostaglandin E2 (PgE2). The concomitant incubation with theophylline and isobutyl-methylxanthine failed to enhance the cortisol-induced suppression, whereas PgE2-dependent inhibition significantly increased after exposure of PBM cells to methyl-xanthines. The inhibitory effect of cortisol was partially or totally prevented by the concomitant incubation with equimolar amounts of 11-deoxycortisol and RU 486 but not of progesterone. Treatment of NK effectors with a monoclonal anti-human corticosteroid-binding globulin (CBG) antibody produced an enhancement of the spontaneous NK activity and a partial suppression of cortisol-mediated effects. Our results suggest that endogenous glucocorticoids play a role in the regulation of NK cell-mediated cytotoxicity. Since the effect of cortisol was additive to that of PgE2 and was not changed by phosphodiesterase inhibitors, it is conceivable that the hormone acts at a level different from the adenylate cyclase-phosphodiesterase system. Data obtained with the use of antiglucocorticoids and the anti-CBG antibody are compatible with a role both of high-affinity glucocorticoid receptors and of CBG in mediating cortisol action on the human NK cell activity.

1-Methyl-3-isobutylxanthine↗
PubMed1987

Studies on the mechanism of cortisol inhibition of human natural killer cell activity: effects of calcium entry blockers and calmodulin antagonists.

The role of Ca2+ in mediating the inhibition by glucocorticoids of human natural killer (NK) activity was investigated using Ca2+ entry blockers (verapamil and its desmethoxy-derivatives LU46973 and LU47093) and calmodulin antagonists (pimozide and two naphthalenesulfopamide derivatives, W-7 and W-13). Peripheral blood mononuclear (PBM) cell preparations were incubated for 20 h with 1 x 10(-6) M cortisol and these agents in various combinations (concentration range: 1 x 10(-7) - 1 x 10(-5) M) and then assayed in a direct 4-h cytolytic assay using 51Cr-labeled K 562 target cells. Exposure to cortisol led to a significant reduction of NK cell activity (about 50% with respect to the spontaneous activity). Ca2+ entry blockers displayed per se a dose-dependent depressive effect on cytotoxicity and gave significant enhancement of cortisol-dependent inhibition. Calmodulin antagonists were per se minimally effective but clearly amplified the cortisol-mediated inhibition. Raising extracellular Ca2+ by CaCl2 or intracellular Ca2+ by the ionophore A23187 yelded an appreciable reduction of these effects. Our data are compatible with the view that extracellular and intracellular Ca2+ play a role in the control of human NK cell activity. Moreover, it is conceivable that the mechanisms involved in glucocorticoid inhibition of NK cell activity involve Ca2+-dependent pathways.

Adult↗
PubMed1987

Imipenem: morphological changes and lethal effects on Pseudomonas aeruginosa.

Imipenem, a new carbapenem antibiotic shows an extremely broad spectrum of antibacterial activity for almost all Gram-negative and Gram-positive aerobic and anaerobic bacteria. It is stable to beta-lactamases and shows a high affinity for PBP 2. The changes in morphology and ultrastructure caused by the antibiotic on Ps. aeruginosa confirm that imipenem acts by binding primarily to PBP 2, resulting in irregular and round shaped cells, and later during treatment to PBP 1 with cellular lysis. The involvement of PBP 1 is also demonstrated by the fast bactericidal kinetics on Ps. aeruginosa, E. coli and Staph. aureus.

Anti-Bacterial Agents↗
PubMed1987

Circadian changes in human natural killer-cell activity.

The circadian changes in natural killer (NK) activity of peripheral blood mononuclear cells (PDM) were studied in five clinically healthy, diurnally active, nocturnally resting women. Data on spontaneous NK-cell activity were complemented by data on the chronosusceptibility to in vitro inhibition by 1 X 10(-6) M cortisol and by the rhythmometric evaluation of rectal temperature and plasma cortisol as potential circadian markers. In April-July, 1985, blood was drawn at 4-hr intervals for 24 hr starting at 0800 hr. Cells were immediately separated and assayed for NK activity using K 562 cultured cells as a target and a 4-hr 51Cr-release assay. Circadian variations of the spontaneous NK activity were apparent; the maximum of the activity occurred in the morning or in the early afternoon. In individual subjects, peak-to-through differences were 50% or more of the 24-hr mean. Chronosusceptibility to cortisol (20 hr incubation prior to the cytotoxic assay) was ecphasic with respect to the spontaneous NK-cell activity, with a maximum in the evening or night. Data obtained by immunofluorescence using specific anti-NK cell monoclonal antibodies confirm the occurrence of a higher number of phenotypically identifiable NK effectors in the morning vs. other circadian stages. Our data confirm previous findings and extend their scope to immunopharmacology emphasizing the need for time-qualified investigations on immune coordination in vivo.

Adult↗
PubMed1986

Cortisol at physiological concentrations and prostaglandin E2 are additive inhibitors of human natural killer cell activity.

The effects of cortisol and prostaglandin E2 on preparations of human peripheral blood mononuclear cells that mediate natural killer cytotoxicity were evaluated. Natural killer cell activity was measured using 51Cr-labelled K562 target cells and effector to target cell (E:T) ratios of 50:1, 25:1, 12.5:1 and 6:1. In vitro preincubation of mononuclear cell preparations for 20 h with 1 X 10(-8) to 1 X 10(-5) M cortisol resulted in a significant decrease of natural killer cell activity. The magnitude of the suppression was directly related to the steroid concentration and inversely related to the E:T ratio. Exposure of cortisol-treated mononuclear cells to 1 X 10(-6) M prostaglandin E2 resulted in a significantly higher level of inhibition than after treatment with the two agents singularly. In contrast, the concomitant incubation with 1 X 10(-5) to 1 X 10(-4) M theophylline, or with 1 X 10(-6) to 1 X 10(-5) M isobutyl-methylxanthine, two widely used phosphodiesterase inhibitors, failed to demonstrate a significant enhancement of cortisol-induced suppression. Prostaglandin E2-dependent inhibition, on the other hand, was more intense after the inhibition of phosphodiesterase activity. Taken together, these results show that cortisol at physiological concentrations has the property of depressing human natural killer cell activity in vitro and suggest that endogenous glucocorticoids play a role in the in vivo regulation of this natural cytotoxicity. Additionally, cortisol and prostaglandin E2 are additive inhibitors of natural killer cell activity. Since the effect of cortisol in our experiments was not changed by theophylline or isobutyl-methylxanthine it is conceivable that the hormone acts at a level different from the adenylate cyclase/phosphodiesterase system.

1-Methyl-3-isobutylxanthine↗
PubMed1986

[Effect of mercaptans on serum IgA].

Using reducing agents like dithiothreitol (DTT) 2.5 mM IgM lose their ability to bind antigens but they can be still detected by an anti-IgM antiserum. IgA are more resistant to reduction than IgM but using higher concentrations of DTT they lose both the ability to bind antigens and the possibility to be detected by an anti-IgA antiserum. Because of this fact IgA after mild reduction can result more or less inactivated according to the method employed to detect them. Using ELISA or similar methods that need an immunological detection of preformed immune complexes IgA-Ag, the loss of activity is more marked than using techniques such as HAI that detect them directly.

Antigen-Antibody Reactions↗
PubMed1986

Visual orientation to the human face in the premature and fullterm newborn.

Visual orientation to the human face was studied by the method of Brazelton in 15 fullterm newborns on the 4th-5th day of life and in 21 premature newborns (gestational age 27-37 weeks) tested weekly up to 40 weeks conceptional age. No evidence of visual orientation was found before 33 weeks. Performances on a par with those of fullterm newborns were not attained until 37-38 weeks on average, though in a few cases this was achieved at 35 weeks. The quality of orientation improved gradually from 32-33 weeks to 38 weeks, but with wide inter- and intra-individual variations. Noteworthy were the discontinuity and transient worsening of visual orientation of the extremely premature subjects (gestational age less than or equal to 31 weeks) in the weeks following birth. Neurological status at the time of the test, rather than pre-and perinatal risk factors, correlated positively with the quality of the visual responses. No statistically significant differences in orientation were found between premature newborns at term age and fullterm newborns.

Age Factors↗
PubMed1984

Thyroid hormone levels in human breast cyst fluid.

Radioimmunoassayable levels of total and free 3,5,3'-triodothyronine (T3) and thyroxine (T4), thyroid stimulating hormone (TSH), thyroxine binding globulin (TBG) and prolactin (Prl) were measured in a series of samples of breast cyst fluid (BCF) aspirated from 73 pre-menopausal women with gross cystic disease of the breast and in coincidental blood samples. In BCF free T3 and free T4 were consistently higher than in plasma (P less than 0.001) as was also total T3 in the majority of cases (P less than 0.05). Total T4, TBG and Prl were much lower than in plasma (P less than 0.001). TSH was roughly as in plasma. No correlation was found between plasma and BCF values. The results indicate that thyroid hormones may be accumulated in their effective form in the cyst fluid. A highly significant inverse correlation was found between intracystic free T3 and log (Prl). Our data, considered in relation to previous experimental evidence, suggest the possibility that thyroid hormones act at the breast level in concert with Prl. Accumulation of thyroid hormones in BCF could play a role in the development or maintenance of gross cystic disease of the breast or be a mere consequence of the cystic changes.

Adult↗