The role of medical counseling in secondary prevention of cancer in the elderly.

In western countries the elderly are those who experience the major impact of cancer, as epidemiologic data clearly show. Thus, secondary prevention of cancer (SPC) in older persons deserves more attention than it has received until now. Target subjects, however, are often reluctant to enter SPC plans. The reasons range from the lack of knowledge about the importance of SPC to the underevaluation of the risk of cancer, or, even more often, to the anxiety and fear that may stem from such a clinical investigation. In this context, the intervention known as counseling finds its natural and essential role. In the paper some general considerations on the significance of medical counseling is given, with particular emphasis on its role in SPC in the elderly. The analysis herein reported points out the specific skills and methods that physicians can adopt to cope with the eventually adverse influences that may affect the participation of the elderly in SPC initiatives. However, such action should avoid any paternalistic approach and respect the patient's will and autonomy.

An in vitro bacterial model of cytotoxicity to living cells caused by dopamine and 6-hydroxydopamine oxidation at physiological pH.

The cytotoxicity of dopamine (DA) and 6-hydroxydopamine (6-OHDA) on living cells, in vitro, has been previously deeply investigated in neuroblastoma cells. This study was designed to explore the possibility to use bacteria as targets for studying DA and 6-HODA cytotoxicity. Both DA and 6-HODA oxidize when added to bacteriological media. The rate of autoxidation of 6-HODA was greater than DA within the first hours. The oxidation-dependent cytotoxicity caused bacterial growth-inhibition and killing at concentration of 10(-4)M. All the bacterial strains tested were slightly more susceptible to DA than to 6-HODA. Antioxidants (sodium metabisulfite, cysteine) prevented the oxidation and abolished the growth-inhibitory activity. The addition of exogenous catalase protected the cells against the effect of the oxidation of both the catecholamines up to the concentration of 5 mM, while the addition of exogenous superoxide dismutase protected the cells only at the minimal inhibitory concentrations. Taking into account that some of the results obtained are similar to those previously reported using neuroblastoma cells as targets, the use of bacteria for studying oxygen toxicity from these catecholamines seems to be a potentially useful model system.

Mueller-Hinton broth undergoes visible oxidative color changes in the presence of peroxidase and hydrogen peroxide.

In the presence of peroxidase and hydrogen peroxide, Mueller-Hinton broth undergoes a slow but clearly detectable color change from pale yellow to dark yellow or brown. An investigation of this phenomenon led to the conclusion that it is the result of the oxidation of tyrosine, a major component of the broth. Indeed, tyrosine has long been known to oxidize upon treatment with peroxidase and hydrogen peroxide. The observations reported here, besides being curious for the clinical microbiologist, might deserve attention for the possible implications in the medium color darkening which sometimes happens during microbial growth.

'Oxygen toxicity' induced by isoproterenol oxidation on living cells. An in vitro prokaryotic model.

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.

Streptococcus faecalis susceptibility to amiloride depends on medium pH.

Amiloride is one of the major molecular probes in basic and applied investigations on the physiology of cation transport in animal cells. In these cells the drug also exerts growth inhibitory activity. Recently, we discovered that amiloride causes growth inhibition also on bacterial cells. In this paper we report that medium pH influences amiloride activity on Streptococcus faecalis. The lowering of external pH causes a drop in the susceptibility of this bacterium to amiloride up to an almost complete resistance. This finding, constitutes a novel aspect of the in vitro experimental pharmacology of this diuretic potentially useful also in clinical pharmacology and in animal cell investigations.

Whole-cell bacterial peroxidase test with isoproterenol as the hydrogen donor.

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.

Chlorpromazine as permeabilizer and reagent for detection of microbial peroxidase and peroxidaselike activities.

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.

Effect of amiloride on the intracellular sodium and potassium content of intact Streptococcus faecalis cells in vitro.

Amiloride at millimolar concentrations caused marked changes in the growth-dependent intracellular balance of Na+ and K+ in Streptococcus faecalis. These results, whether specific to transport processes or resulting from indirect yet unknown mechanisms, constitute the first evidence of an effect of amiloride on bacterial electrolytes.

In vitro antistreptococcal activity of the potassium-sparing diuretics amiloride and triamterene.

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.

Amiloride, a diuretic with in vitro antimicrobial activity.

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.

New method for detecting Epstein-Barr virus association in nonproducer lymphoblastoid cell lines.

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.

Competitive enzyme immunoassay for detection of complement-fixing antibodies in diagnostic virology.

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.

Inhibition of nonspecific streptococcal coagglutination reactions.

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.