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Biomedical subjects

G Doria

Publications and source records attributed to G Doria.

At least 73 records · Page 4Linked to original sources
PubMed1990

[Multiparameter analysis of the ergometric test. Significance of the failure of systolic blood pressure to decrease during recovery phase as an index of coronary disease].

Ergometric tests were performed in 27 patients who had previously undergone coronarography following instrumental findings and/or symptoms which seemed highly indicative of ischemic cardiopathy. The aim of the study was to assess the diagnostic importance of the failure of systolic blood pressure to decrease during the third minute of the recovery phase of the test as an index of coronary disease. In particular, as reported by other studies, the ratio between systolic blood pressure at the third minute of recovery and maximum systolic blood pressure during the test was also assessed values above 0.7 were considered pathological. Sixteen out the 27 patients examined showed lesions which were hemodynamically significant, whereas 11 patients were free of lesions and 9 had previous myocardial necrosis. The level of the above ratio in subjects without significant coronary lesions was 0.66 +/- 0.05, whereas it was 0.85 +/- 0.04 (p less than 0.01) in patients with coronary disease. Sensitivity, specificity, and positive and negative prognostic values were respectively 91.6%, 62%, 64.7% and 90.9%. In patients with lesions to the three main arteries both the sensitivity and the specificity were 100%. In the same patients, the ST criteria were 85.7%, 50%, 81.8% and 74.3%.

Blood Pressure↗
PubMed1990

[Evaluation of acute cardiotoxicity from the combination cyclophosphamide-mitoxantrone-5-fluorouracil (CMF) with Holter ECG].

By making use of a twenty-four hour Holter monitoring, it as been possible to compute the acute cardiotoxicity of the cyclophosphamide + mitoxantrone + 5-fluorouracil (CNF) association in twenty oncologic patients (pts) each of whom being immune from organic cardiopathy emerging clinically and at their first cycle of chemotherapy. The following parameters have been computed: meaningful changes in the heart frequency; premature atrial and ventricular depolarizations, both as a first appearance and as a clear growth in the number; the ST dislocation entity; malignant ventricular arrhythmias. The administration of CNF at the doses of: 600 mg/m2 of cyclophosphamide, 12 mg/m2 of mitoxantrone and 600 mg/m2 of 5-fluorouracil , has caused a meaningful increase in the heart frequency on 6 pts (30%), an increase of premature atrial depolarization on 4 pts (20%) with an appearance ex novo on 2 pts (10%), an increase of premature ventricular depolarization, without any passing to superior Lown classes, on 2 pts (10%) with an appearance ex novo on 3 pts (15%). Although the results in the study point out a frequency percentage of simple hyperkinetic arrhythmias equal to the 55%, the lack of more serious hyperkinetic arrhythmias and of intense disorders of ventricular repolarization testified to a synergic effect as a determining factor on the acute cardiotoxicity of the previously discussed association, in our opinion.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1990

[3 cases of gingival hyperplasia during nifedipine therapy].

The authors report the cases of three male patients, aged 36, 54 and 52 years, who developed gingival hypertrophy during treatment with nifedipine at a dose of 40 mg/daily. Hypertrophy was the same as that observed in patients treated with anti-convulsive or cytostatic drugs, and may probably be due to interference with calcium ions and local factors. Full recovery was achieved by suspending nifedipine treatment in all patients.

Adult↗
PubMed1989

Competition for antigen presentation in living cells involves exchange of peptides bound by class II MHC molecules.

T cells recognize foreign proteins as peptides bound to self molecules encoded by the major histocompatibility complex (MHC). The kinetics of interaction between purified class II MHC molecules and peptides is unusual, in that the rate of association is very slow, but once formed, the complexes are extremely stable. This raises the question of how the antigen-presenting cell provides a sufficient number of free MHC binding sites to ensure T cell immunity. We present results suggesting that an exchange of peptide in MHC binding sites may take place under physiological conditions.

Ammonium Chloride↗
PubMed1989

Structural requirements for the interaction between peptide antigens and I-Ed molecules.

We have analyzed the structural characteristics of the interaction between I-Ed molecules and their peptide ligands. It was found that unrelated good I-Ed binders share structurally similar "core" regions that were experimentally demonstrated to be crucial for binding to I-Ed molecules. Single amino acid substitution analogues of one good I-Ed binder, hen egg lysozyme 107-116, were analyzed for their capacity to bind to I-Ed molecules and to activate two different I-Ed-restricted T cell hybridomas. The results illustrate the great permissiveness of I-Ed-peptide interaction and the great specificity of T cell recognition. It was concluded from these analyses that basic residues on the peptide molecule play a crucial role in binding to I-Ed. This contrasts with the structural requirements for binding to the other Iad isotype, I-Ad, the crucial hydrophobic residues. Thus, different class II molecules of the same MHC haplotype may have rather distinct peptide binding specificities, thereby expanding the repertoire of possible immunogenic peptides presented for T cell recognition.

Amino Acid Sequence↗
PubMed1989

Inheritance of immune responsiveness, life span, and disease incidence in interline crosses of mice selected for high or low multispecific antibody production.

High (H) and low (L) antibody responder lines of mice separated by selective breeding present a maximal interline difference in antibody (Ab) response to Ag of different specificities (general genetic regulation). The analysis of SRBC agglutinin response in H line, L line, F1 hybrids, F2, and backcross segregants demonstrates that Ab responsiveness is a polygenic trait regulated by the additive interaction of 5 to 7 independent loci, with an incomplete dominance (44% +/- 7%) of the high response character, and a 30% +/- 10% impact of the environmental factors. The life span of H, L, F1, F2, and backcross populations is correlated positively with 2-ME-resistant agglutinin response (r = 0.97, p less than 0.001) and negatively with 2-ME-sensitive agglutinin response (r = 0.95, p = 0.01) (interpopulation correlation). Similar correlations are also observed in individuals of the various populations, especially in F1 x L backcross, in which the largest phenotypic variance is found. The positive correlation between Ab responsiveness and life span was confirmed by ELISA titration for distinct IgG isotypes (intrapopulation correlation). Malignant lymphomas and chronic nephritis were the two most common diseases observed. The age-adjusted incidence of such diseases, which is largely affected by environmental factors, accounts for the longer life span of H, as compared with L, mouse populations. The longevity of the 30% or less survivors, chiefly determined by the rate of physiologic aging, is a polygenic character regulated by the cumulative interaction of 3 to 7 independent loci, with a complete dominance of the long life trait and an impact of the environmental factors of about 60%. Thus we have grounds for regarding general Ab responsiveness and life span as polygenic traits regulated by a small number of identical or closely linked gene loci, and immune responsiveness as a defense mechanism against neoplastic and inflammatory diseases.

Aging↗
PubMed1989

Cholinergic agonists selectively induce proliferative responses in the mature subpopulation of murine thymocytes.

The incubation of murine thymocytes for 24 hr in the presence of cholinergic agonists induces selective proliferation of PNA- cells as measured by thymidine incorporation. The response of PNA- cells is mediated by the activation of nicotinic receptors. This conclusion is suggested by the inability of the muscarinic agonist, oxotremorine, to induce cell proliferation and by the inhibition exerted by the nicotinic antagonist, d-tubocurarine. The presence of cholinergic axons in the murine thymus adds biological interest to the selective expression of functional cholinergic receptors on mature thymocytes.

Animals↗
PubMed1989

Age-related changes within a suppressor T cell circuit.

The effects of aging on cellular and molecular components of the 4-hydroxy-3-nitrophenyl acetyl-specific suppressor T (Ts) cell circuit were analyzed in vitro using inducer (Ts1), transducer (Ts2), and effector (Ts3) cells and activating factors (TsF1 and TsF2) derived from young or old mice. The activation of Ts2 cells by TsF1 and of Ts3 cells by TsF2 was found age-restricted, suggesting a loss of Ts2 and Ts3 cell subsets in old mice. However, the activation of Ts3 cells by small amounts of TsF2 is more efficient when both are derived from old rather than from young mice while the same level of maximum suppression is attained. Higher affinity of the interactions involved in Ts cell activation may compensate for loss of Ts cell subsets in old mice. No age restriction was found for antigen presentation to Ts1 cells and for the interaction between Ts3 cells and target B cells. Thus, the effects of aging on immunosuppression result from changes within the Ts cell circuit.

Aging↗
PubMed1989

An Apple IIE microcomputer program for multiple non-independent comparisons by the Scheffe's test.

When more than two groups of observations from the same set of experimental data are compared and pairwise tested for equality of their means, appropriate statistical treatment of the data is required. The overall variation in the set of data must be considered, and also the statistical non-independence of each pairwise comparison must be taken into account. We describe a simple Apple IIE microcomputer program that applies the Scheffe's test for multiple comparisons. A numerical example and a sample output of this program are also included. The listing of the program is reported in the Appendix.

Analysis of Variance↗
PubMed1989

[The diagnostic value of delta-R and delta-Q as positive criteria of the ergometry test in a group of patients with angina pectoris of effort].

ECG-exercise tests were performed in 29 patients affected by effort chest pain. All patients underwent coronary angiography and/or revealed positive results in the cycloergometer effort test. The aim of the study was to evaluate ultrasonic variations in the R and Q waves due to maximal effort, so as to increase the information provided by the effort ECG. In the coronary angiographic test, 21 out of 29 patients revealed significant hemodynamic coronary stenosis; 10 patients were affected by previous myocardial necrosis; 8 patients showed no hemodynamic coronary lesions (OV). In the OV patients a statistically significant increase was observed in the Q wave at maximal effort in comparison with average basal values; on the other hand, there was a decrease, although not significant, in voltage at peak effort in patients with coronary stenosis. R wave amplitude was smaller in comparison to basal values in OV patients, while a significant increase was observed in the 21 patients with coronary lesions.

Aged↗
PubMed1988

Mechanisms influencing the immunodominance of T cell determinants.

The preferential recognition of certain amino acid sequences from foreign protein antigens by T cells is referred to as T cell epitope immunodominance. To determine the mechanisms underlying this phenomenon, we have studied the correlation between the interaction of a series of synthetic peptides encompassing the entire hen egg-white lysozyme (HEL) sequence with class II molecules of the H-2k haplotype, and T cell responsiveness to these peptides. After HEL priming, three immunodominant T cell epitopes were found: two, included in the HEL sequences 51-61 and 112-129, were recognized in association with I-Ak molecules, and one, included in sequence 1-18, in association with I-Ek molecules. Accordingly, these peptides bound to the appropriate class II molecule, as demonstrated by competition for antigen presentation. Several other HEL peptides, although capable of associating with class II molecules, were not immunodominant. The absence of immunodominance has been shown to arise by three different mechanisms: (a) competition by an immunodominant peptide for presentation in vivo, (b) failure to generate the peptide during antigen processing, and (c) an inherently poor capacity of the T cell repertoire to respond to a particular peptide-MHC complex.

Animals↗
PubMed1988

In vivo restoration of T cell functions by human IL-1 beta or its 163-171 nonapeptide in immunodepressed mice.

The immunorestorative capacities of human (hu) IL-1 beta or its synthetic fragment 163-171 (VQGEESNDK) were assessed in vivo in mice immunodepressed by aging, sublethal irradiation, or both. Subcutaneous administration of hu rIL-1 beta into immunodepressed animals immediately after carrier (horse red blood cells, HRBC) priming could restore to normal levels Th cell activity. This was measured as the ability of spleen cells from HRBC-primed mice to induce a hapten-specific antibody response in spleen cells from nonimmune mice in vitro stimulated with the hapten-carrier conjugate TNP-HRBC. In parallel, the ability of spleen cells from hu rIL-1 beta-treated immunodepressed animals to produce T cell growth factor activity upon in vitro mitogen stimulation was also increased significantly as compared to that of untreated mice and approached that of immunocompetent controls. The immunorestorative activity of hu rIL-1 beta on Th cell activity and T cell growth factor production could be mimicked by the synthetic nonapeptide 163-171 which, at the doses used, produced in most instances even greater effects than the whole protein. Although the optimal immunorestorative doses of the 163-171 peptide were several orders of magnitude higher than those of hu rIL-1 beta, the complete lack of IL-1-like inflammatory and toxic effects suggests that the synthetic hu IL-1 beta fragment may be successfully used as immunomodulating agent in the therapy of T cell immunodeficiencies.

Adjuvants, Immunologic↗
PubMed1988

In vivo stimulation and restoration of the immune response by the noninflammatory fragment 163-171 of human interleukin 1 beta.

The synthetic nonapeptide VQGEESNDK, corresponding to the fragment 163-171 of human IL-1 beta, showed in vivo immunomodulatory capacities qualitatively and quantitatively comparable to those of the mature human IL-1 beta protein. In fact, both IL-1 beta and the 163-171 fragment stimulated the immune response of normal mice and restored immune reactivities of immunocompromised animals. In addition, the synthetic IL-1 peptide was as efficient as the entire protein in inducing tumor rejection and radioprotection. On the other hand, the 163-171 fragment did not cause any of several inflammation-associated metabolic changes inducible by the whole IL-1 beta molecule in vivo: hypoferremia, hypoglycemia, hyperinsulinemia, increase in circulating corticosterone, SAA and fibrinogen, decrease in hepatic drug-metabolizing enzymes. Furthermore, at variance with IL-1 beta, the 163-171 peptide did not show the toxic effects causing shock and death in adrenalectomized mice. Thus, these results confirm our previous in vitro observations that functional domains are identifiable within the multipotent cytokine IL-1 beta, and demonstrate the biological relevance of this finding in a variety of in vivo systems. The identification of a selectively active fragment of a cytokine may thus represent a significant step towards a better directed and more rational immunotherapeutic approach.

7-Alkoxycoumarin O-Dealkylase↗
PubMed1988

Enhancement of suppressor T cell activity by injection of anti-IFN-gamma monoclonal antibody.

In the present study, the contribution of IFN-gamma to the generation of helper activity in mice was investigated by use of anti-mouse IFN-gamma rat mAB (AN 18.17.24). This mAb was alum precipitated and injected i.p. before or after carrier priming. Results show that spleen cell helper activity is markedly inhibited by anti-IFN-gamma mAb injection. This inhibition is time and dose dependent, and counteracted by IFN-gamma administration. Thus, the anti-IFN-gamma mAb appears to inhibit helper cell activity by neutralization of the IFN-gamma required for the antibody response. Moreover, AN 18.17.24 mAb injection results in increased activation of Lyt-2+ T cells which markedly suppress Th activity. These findings altogether indicate that besides the activation of macrophages and Th, IFN-gamma seems to exert a negative interference in suppressor T lymphocyte circuits and, as a consequence, to inhibit immunosuppression.

Animals↗
PubMed1988

Heterogeneity of immune responsiveness in healthy elderly subjects.

We studied a group of healthy elderly subjects (satisfying the SENIEUR Protocol admission criteria), chosen as a model of age-associated immune deficiency on the basis of their reduced skin reactivity to recall antigens. Results show that aged subjects, taken as a whole, display impaired T-cell functions: reduced blastogenetic responses to mitogens, IL-2 production, responsiveness to exogenous IL-2, and percentage of Tac positive blasts. However, the age-associated immune defect shows a wide range of impairment, even in a relatively homogeneous group of anergic/hypoergic subjects. In fact, a considerable proportion of our elderly subjects displays responses comparable with those of adult controls. These observations suggest that (a) immune deficiency is not a characteristic of aging per se; (b) cutaneous delayed hypersensitivity is not a criterion sensitive enough to identify people with age-associated immune deficit; and (c) more than one test is required to evaluate T-cell impairment in aging.

Aging↗
PubMed1988

In vivo immunopotentiating activity of thymopentin in aging humans: modulation of IL-2 receptor expression.

The effect of thymopentin treatment was investigated in immunocompromised elderly subjects. Thymopentin was able to increase IL-2 production and IL-2 receptor expression, as assessed on PHA-activated blasts by percentage of Tac-positive cells and response to exogenous IL-2. After treatment, an increased precursor frequency, estimated by limiting dilution analysis, of PHA-responding lymphocytes was observed in two out of six subjects tested. In vitro experiments with thymopentin show that the drug was able to enhance blastogenesis by PHA of elderly lymphocytes but not of adult cells. These results indicate that (a) the increased IL-2 synthesis/IL-2 receptor expression may be the crucial mechanism of the immunopotentiating activity of the drug in elderly subjects and (b) an increased intrinsic T-cell responsiveness seems to be responsible for this immunopotentiating activity, although an increase in the size of the responsive T-cell pool could not be excluded.

Adjuvants, Immunologic↗