Biomedical subjects
Publications and source records attributed to S Giunta.
Chlorpromazine was used to perform a test for the detection of microbial peroxidase activities. The compound acts as both a cell permeabilizer and a reagent in the procedure developed which allows the detection of peroxidase and peroxidase like reactions both semiquantitatively in whole cell determinations and quantitatively in cell-free supernatants.
The ionophore antimicrobial agents provide evidence that perturbations of the electrolyte balance of bacterial cells exert a growth-inhibitory activity. Several drugs acting on animal cell membranes have also been shown to be active on bacterial cells. In this paper, we report preliminary susceptibility studies showing that the class of potassium-sparing diuretics acting directly on monovalent cation fluxes on animal cells possesses a selective growth-inhibitory activity on hemolytic streptococci.
The regulatory action exerted on receptors by acebutolol, a cardioselective beta-blocker containing intrinsic sympathomimetic activity, has been investigated. beta-Adrenoceptor affinity and density of human mononuclear leukocytes were assayed in hypertensive patients before and after treatment with 400 mg/day acebutolol. While receptor affinity showed no changes between pre- and post-treatment values, a statistically significant decrease has been demonstrated in receptor density following treatment. Blood pressure and heart rate were also measured in order to test the efficacy of the administered drug. All these parameters showed a fall in the post-treatment values. It is concluded that the partial agonist acebutolol, in spite of the fact that it acts clinically as a beta-blocker, has the regulatory mechanism characteristic of agonists.
The effect of amiloride, an inhibitor of passive sodium influx in animal cells, was investigated on the in vitro bacterial growth. Amiloride blocked the growth of different bacterial strains at concentrations ranging from 25 to 1,300 micrograms/ml. While generally the block was bacteriostatic and bacteria, on amiloride removal, recovered their ability to growth, the drug showed a killing activity on hemolytic streptococci. Gram-positive bacteria revealed a greater susceptibility to amiloride than gram-negative ones. Although an hitherto unknown effect of amiloride cannot be excluded, from the known mechanism of action of amiloride on animal cells it might be suggested that sodium permeability plays a critical role on bacterial multiplication.
beta 2-Adrenoceptor characteristics of human mononuclear leukocytes were assayed in hypertensive patients before and after treatment with 100 mg/day atenolol. While no changes have been observed in receptor affinity, a statistically significant increase (36%) has been demonstrated in receptor density following treatment. Blood pressure and heart rate were also measured in order to test the efficacy of the administered drug. All these parameters showed a fall in the post-treatment values. It is concluded that at therapeutic concentration, beta 2-adrenoceptors undergo up-regulation by atenolol in spite of its cardioselectivity. Such a regulation, which may represent a fundamental step in the mechanism leading to withdrawal syndrome, may, therefore, be suggested being quite widespread.
The present study was aimed to decide whether Na+ influx can be involved in regulation of murine L 1210 leukemia cell growth. Cells were cultivated in the presence of different concentrations of amiloride and cellular growth was monitored by 3H-thymidine incorporation/10(5) cells. This drug inhibited cell growth in concentrations ranging from 1 X 10(-5) to 1 X 10(-3) mmol/ml. Even short time treatments with amiloride caused irreversible alterations: the cells, although survived, lost their ability to divide. The results support the hypothesis that Na+ influx is necessary for the duplication of tumor cells.
Human peripheral blood thymus lymphocytes are capable of forming, when stimulated by phytohemagglutinin, single-cell-derived colonies in an in vitro soft-agar system. Blood samples were obtained from 33 healthy men ranging in age from 20 to 96 years of age and from 11 diabetic men ranging in age from 42 to 60 years and 11 age-matched controls. With increasing age a reduction in the number of single-cell-derived colonies and a decrease in their residual in vitro proliferation potential was observed. Such a defect appeared at an earlier age in diabetic men. The defect in proliferative potential of cells of either old or diabetic men did not depend on factors present in their blood plasma.
The reliability of latex coagglutination testing for the serological grouping of hemolytic streptococci is limited by the relatively high incidence of false-positive reactions. Pretreatment of streptococcal suspensions with antisera for the various groups that show clumping gives a specific inhibition of the latex agglutination with the true group, whereas the other groups continue to agglutinate aspecifically. The method is rapid and easy to perform, allows the exact grouping of those streptococci giving aspecific reactions, and is also a useful confirmatory test with monoreactive strains.
A competitive enzyme immunoassay was developed to detect serum complement-fixing antibodies in virus diseases. This assay utilized conglutinin-covered plastic beads as the solid phase to detect specific antibody-antigen complexes that competed for complement with a probe complex comprised of Escherichia coli beta-galactosidase and its specific antibody. Binding to the solid phase is C3bi mediated, and when specific antibody-antigen complexes are not present the probe is bound and an enzymatic reaction ensues. This type of competitive assay was introduced in the field of immunopathology for investigating circulating immune complexes by Manca et al. (Clin. Immunol. Immunopathol. 16:131-141, 1980). The assay gave satisfactory results in terms of specificity, reproducibility, and handling, enabling laboratories to obtain results in 5 h. The sensitivity of the method coincided with that of the complement fixation test. However, this technique offers several advantages over conventional complement fixation because it requires less time, is easier to perform, and gives more reliable quantitative results. The data obtained indicated that this competition assay offers a feasible alternative to conventional complement fixation tests and should be useful in routine diagnostic applications and in seroepidemiological surveys.
Epstein-Barr virus association in nonproducer human lymphoblastoid cell lines can be demonstrated by the presence of the virus genome (nucleic acid hybridization studies) or by the detection of the virus-coded complement-fixing antigen (complement fixation and/or anti-complement immunofluorescent test). This paper describes an enzyme immunoassay for the detection of Epstein-Barr virus complement-fixing antigen and its application to the demonstration of Epstein-Barr virus association in nonproducer lymphoblastoid cell lines. The assay is based on competition for complement between Epstein-Barr complement-fixing antigen and its specific antibody and a probe complex composed of Escherichia coli beta-galactosidase and specific anti-beta-galactosidase antibody. This competitive enzyme immunoassay is a specific and sensitive procedure for detecting Epstein-Barr virus association in nonproducer cell lines, allowing also quantitative estimation of the amount of antigen produced.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
It has been demonstrated that peripheral blood lymphocytes, particularly the "atypical" ones, are predominantly of the T type in infectious mononucleosis (IM). This is based on membrane marker studies (E rosettes, receptor for complement, receptor for Fc fragment of immunoglobulins (Ig), and membrane Ig) and by anti-T lymphocyte serum. On the other hand, lymphoblastoid cell lines derived from IM patients show the characteristics of B lymphocytes. This permits the suppostion that EBV infects B lymphocytes and stimulates them to proliferate. The cell proliferation is unlimited in vitro and is probably controlled in vivo by T cells. The reduction of cellular immunity in vivo, which contrasts with the high number of T cells in peripheral blood, could be explained by the fact that T cells are engaged in the regulation of B cell proliferation.
We present a case of a urothelial neoplasm arising within a direct bladder hernia in the inguinal canal. Bladder hernias are rarely found preoperatively and are exceptional sites of neoplasm. Spiral computed tomography with gaseous insufflation of the bladder demonstrated the bladder hernia and the extension of the neoplasm in the inguinal canal more accurately than other computed tomographic techniques with nonopacified and iodinated urine.
The evaluation of mural invasion (T) in primary urinary bladder carcinoma is important in the planning of an appropriate surgical or radiochemotherapeutic strategy. Previous investigators using computed tomography (CT) have evaluated the bladder filled with urine, urine opacified with iodinated contrast material, or air insufflation. The purpose of this trial was to establish which of these three techniques was the most accurate by comparing data obtained in postoperative staging (pT). Sixty-five patients with primary bladder cancer were enrolled, all of whom were studied by spiral CT with these three techniques. Patients were assigned to four stage groups: Ta-T1, T2-T3a, T3b, and T4. The results demonstrated total accuracies of 95% for the air-insufflated bladder, 90.5% for opacified urine, and 87% for noncontrast studies. In conclusion, the air-insufflated bladder is the more accurate technique in the evaluation of the T parameter in primary bladder cancer, especially in the first and third stage groups.
Oxygen radical damage is a relevant problem in gerontological research. It has been implicated both in the aging process itself and in aging-related pathologies. Oxygen radicals from catecholamines seem to play an important role in central nervous system and cardiovascular system disorders during aging. Prokaryotic experimental systems have been shown to provide a simple and short term in vitro model for 'oxygen toxicity' from catecholamine oxidation which might be useful also in age-related research. In this paper we show that the synthetic sympathomimetic catecholamine, isoproterenol, oxidizes when added to bacteriological media and that this oxidation process causes bacterial growth inhibition. Both isoproterenol oxidation and the growth-inhibitory activity can be prevented by the addition of antioxidants. The addition of exogenous catalase (CAT), while unable to prevent isoproterenol oxidation, totally suppressed the bacterial growth inhibition; the addition of exogenous superoxide dismutase partially antagonized isoproterenol oxidation and suppressed bacterial growth inhibition although less efficiently than CAT. The model described suggests that besides 'oxygen toxicity' by endogenous natural catecholamines, iatrogenic tissue injury caused by the oxidation intermediates from this class of pharmacological compounds must also be considered.
The beta-adrenergic compound isoproterenol was used as oxidizable reagent in a whole-cell assay for the detection of bacterial peroxidase activities. Isoproterenol has been shown to constitute a useful reagent for detecting peroxidase activities in enzymatic tests, utilizing standard purified enzymes, and in the microbiological application proposed. The procedure developed is simple and rapid to perform. In contrast to currently used whole-cell tests for bacterial peroxidases, the assay described here does not need preliminary permeabilization; moreover, the compound utilized does not have related toxicological problems. Therefore, the isoproterenol assay may represent a low-cost safe additional peroxidase test in clinical bacteriology.
Explore the source record for details and available documents.