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A Andreoni

Publications and source records attributed to A Andreoni.

At least 19 recordsLinked to original sources
PubMed1992

Excited singlet state properties of anthracenedione photosensitizers.

The absorption, fluorescence and S1 state kinetics of anthracycline antitumour drugs (e.g. daunomycin, adriamycin) and several imino- and/or amino-substituted derivatives are investigated. The study, which includes all anthracyclines which possess photocytocidal activity, is extended to the disubstituted aminoanthracenedione, mitoxantrone, a red-light-absorbing antitumour drug whose activity, both in vitro and in vivo, is enhanced by photoactivation. The S1 state of the anthracycline imino and amino derivatives, in aqueous buffer at pH 7.4, is characterized by bi-exponential decay kinetics which indicates the presence of two ground state populations differing in the extent of hydrogen bonding. The ammonium group of the sugar moiety of anthracyclines contributes to the quenching of the S1 state population through a prototropic mechanism.

Antibiotics, Antineoplastic↗
PubMed1991

B16 melanoma response in vivo to photochemotherapy with mitoxantrone and red light.

The cytocidal activity of light-activated mitoxantrone in mice bearing B16 melanoma was investigated. Mice inoculated with 10(6) tumor cells on day 0 were i.p. injected with 1 mg/kg body weight of mitoxantrone on days 1, 5 and 9 and exposed to 108 J/cm2 of suitably filtered red light from a halogen lamp on days 2, 6 and 10. The treatment significantly prolonged the median survival time compared to both therapy with mitoxantrone and with red light alone.

Animals↗
PubMed1991

Blockade of cholinergic muscarinic receptors by pirenzepine and GHRH-induced GH secretion in the acute and recovery phase of anorexia nervosa and atypical eating disorders.

In view of the important role played by the cholinergic system in the neural regulation of growth hormone (GH) secretion, the ability of pirenzepine, a selective antagonist of muscarinic cholinergic receptors, to blunt the GH response to GH-releasing hormone (GHRH) was studied in adolescent females with anorexia nervosa in the acute (AN-AP) five AN-AP patients, administration of GHRH 1-40 (1 microgram/kg IV) evoked a significantly higher GH response than in controls at established intervals, whereas in eight AN-RP and seven AED patients it was higher than in controls at only one (150-min) and two (150-min, 180-min) time intervals, respectively. In the AN-AP patients, pretreatment with pirenzepine (0.6 mg/kg IV) only partially blocked the GH response to GHRH, whereas in the same AN-AP patients tested during recovery, and in AN-RP and AED patients, the drug completely suppressed the GH response to GHRH, as it did in controls. In view of pirenzepine's mechanism of action, these findings are best explained by the existence in the hypothalamus of AN-AP patients of a cholinergic hypertone and/or a diminished somatostatinergic function. Evaluation of the clinical and hormonal characteristics of the anorectic patients studied would indicate that factors other than undernutrition and its biological consequences, which subside in the recovery stage of the disease and are not present in AED patients, contribute to the anomalous GH response pattern of AN-AP patients.

Adolescent↗
PubMed1991

Enhancement of antitumor drug cytotoxicity via laser photoactivation.

We investigate the efficacy of daunomycin, some imino- and amino-substituted daunomycin analogues and the disubstituted aminoanthracenedione, mitoxantrone, in photosensitizing short-term cell kill upon irradiation in the long wavelength visible range, during incubation of Fisher rat thyroid cells with the drugs. While all compounds exhibit similar cytocidal effects on our cell line, in the absence of irradiation, administering 86 J/cm2 at wavelengths either coincident or close to drug absorption peaks causes greater enhancement in cell mortality for the 4-demethoxydaunomycin analogues than either the parent drug or its 5-imino-derivative. A lower enhancement is observed with mitoxantrone. In particular, C50 doses (i.e. concentrations that would kill 50% cells) as low as approximately 10(-9) M are found for both 6- and 11-amino 4-demethoxydaunomycin, compared with the values obtained in the absence of light, which are 2.59 x 10(-4) and 0.43 x 10(-4) M, respectively. Our previous studies of the photophysical and photochemical properties of the excited states of these drugs, and ESR and spin trapping studies of photosensitized generation of singlet oxygen, which were extended in this work to include mitoxantrone, indicate that the cytocidal effects proceed via type I rather than type II mechanisms.

Animals↗
PubMed1991

Photocytotoxicity of anthracyclines upon laser excitation in their long-wavelength absorption bands.

Newly synthesized daunomycin derivatives with red-shifted absorption compared to the parent molecule are shown to be able to photosensitize cells in vitro upon excitation with either argon or argon-pumped dye laser. Administering 86 J/cm2 total fluence (1 h irradiation) to Fisher rat thyroid cells during 2 h incubation with either daunomycin (excitation wavelength: 488 nm) or 5-iminodaunomycin (595 nm) produced cell killing at doses (about 2.7 X 10(-7) M for 50% cell survival) which were not toxic if administered in the dark. Greater photocytotoxicity (about 7 X 10(-8) M for 50% cell survival) was obtained with 4-demethoxydaunomycin as well as with its 6- and 11-amino derivatives (514 nm) while no cell killing as a result of photosensitization was observed for either Adriamycin or its 4'-iodo derivative. Our results suggest that the photosensitizing efficacy correlates with the absence of the methoxy group in the anthraquinone chromophore but is rather independent of the occurrence of triplet-mediated photoreactions. Finally, the fact that the imino- or amino-substituted 4-demethoxy compounds exhibit red-shifted absorption spectra compared to the parent molecule might be exploited for in vivo applications of the photoactivated cytotoxicity reported in this work.

Animals↗
PubMed1990

Failure of glucose infusion to suppress the exaggerated GH response to GHRH in patients with anorexia nervosa.

The growth hormone (GH) response to GH-releasing hormone (GHRH) is characteristically exaggerated in anorexia nervosa (AN). Hyperglycemia suppresses the GH response to GHRH in normal subjects. To test whether this inhibitory action of hyperglycemia is preserved in AN, we performed a GHRH (GHRH 1-40, 1 micrograms/kg) test under basal conditions (saline infusion) and during steady-state hyperglycemia (200 mg/dl, induced by the intravenous administration of 8 mg/min.kg of glucose) in 6 adolescent girls with acute-stage AN (as diagnosed by psychopathological, hormonal, and nutritional criteria) and in 5 age-matched female controls. In control subjects, GHRH stimulated GH release during saline, but not glucose, infusion. In the anorectic patients, the GH response to GHRH was exaggerated during both saline infusion (2.97 +/- 0.79 versus 0.52 +/- 0.22 micrograms.120 min.ml-1, p less than 0.02) and under hyperglycemic conditions (4.61 +/- 0.56 versus 0.33 +/- 0.10, p less than 0.001). We conclude that the inhibitory action of hyperglycemia on GHRH-induced GH release is lost in the acute phase of AN.

Acute Disease↗
PubMed1990

Quantitative measurements of porphyrin pigments in tissues via photoacoustic spectroscopy.

We investigated the possibility of using photoacoustic spectroscopy as an analytical technique for the quantitative measurement of injected porphyrins in tissues. Samples of liver excised from treated (i.e., injected 24 h in advance with 100 mg/kg Photofrin II) mice and control mice were lyophilized and reduced to powder; then, about 16-mg powder samples were compacted to equal volumes inside the photoacoustic cell. Amplitude and phase spectra were measured in the range 280-760 nm. From these data we computed the photoacoustic absorbance spectra; they were suitably normalized in order to account for differences in hemoglobin concentration among the livers of different mice. The absorbance difference spectra (treated minus control) were computed in the region of wavelengths above 450 nm, where porphyrins and hemoglobin exhibit major differences. Finally, by estimating the value of the thermal diffusion length of the powdered sample and those of the extinction coefficients of the most relevant Photofrin II components in the spectral region considered, we were able to evaluate the local drug concentration and determined a value (260 micrograms/g of wet tissue) that is in the range expected for the dose of Photofrin II injected.

Acoustics↗
PubMed1990

Time-resolved luminescence spectroscopy of photosensitizers of biomedical interest.

Studying the fluorescence decay of chromophores, either used as fluorescent labels to stain specific biomolecules or as photosensitizers to produce irreversible chemical or physico-chemical modifications on biological substrates, is being demonstrated to be a valuable method of investigating the interactions underlying a variety of phenomena. In fact, all possible primary steps in a photosensitized biological system are phenomena that may occur during the chromophore S1 lifetime and act as quenching mechanisms of the S1 state. Thus they can be identified, and the relative importance of the corresponding transient species quantitatively determined, with suitable techniques of time-resolved fluorescence spectroscopy. The examples discussed in this paper concern both tumor photosensitizing drugs, such as anthracyclines and porphyrins, and skin sensitizers (e.g. furocoumarins).

Luminescence↗
PubMed1990

Effects of cholinergic muscarinic antagonist pirenzepine on GH response to GHRH 1-40 in patients with anorexia nervosa.

The effects of cholinergic muscarinic receptor antagonist pirenzepine on the GHRH-induced GH release were studied in 10 adolescent females with anorexia nervosa at different stages of the disease, in 5 adolescent females with eating disorders and in 5 normal adolescents. The patients were characterized according to psychological (DSM III-R), endocrinological (GnRH test), nutritional (Somatomedin-C, T3), and clinical (% IBW, duration of the amenorrhoea) criteria. On two separate occasions, each subject received an i.v. bolus injection of GHRH 1-40 (1 microgram/kg) alone or preceded by pirenzepine (0.6 mg/kg i.v. 5 min before GHRH 1-40). GHRH 1-40 injection induced a significantly (P less than 0.05) higher GH increase in the patients with anorexia nervosa at the acute stage as compared with the controls. Pirenzepine did not abolish opportunely the exaggerated GH response to GHRH 1-40 in anorectic patients at the acute stage unlike the control, who showed the blockade of GHRH-induced GH release by the cholinergic muscarinic antagonist (P less than 0.05). The anorectic adolescents at the non acute stage and the adolescents with eating disorders showed varying reductions of GH response; however, pirenzepine produced a blunted suppression of GHRH-induced GH increase as compared to the controls, which was not statistically significant. Somatomedin-C values were significantly (P less than 0.05) lower in anorectic patients at the acute stage as compared with controls. The abnormal activity of cholinergic system in anorectic patients, as our data show, could induce the GH hypersecretion through an inhibitory influence on the somatostatinergic function. The reduced somatomedin-C levels, a specific malnutrition index in anorectic patients, produce a modified feed-back on the hypothalamic site (somatostatin) and/or directly on the pituitary, following the GH hypersecretion.

Adolescent↗
PubMed1990

Recent developments in imaging diagnosis in fractures of the acetabulum: the role of CAT and tridimensional reconstruction.

The authors report their experience in a radiographic study of the treatment of 22 cases of fractures of the acetabulum. All the patients were studied using both traditional radiography and CAT, and the results were then compared. In 17 cases (77%) the CAT images were integrated with a tridimensional reconstruction (3D). The diagnostic aid provided by CAT was of crucial importance in planning treatment and selecting the most suitable surgical approach. Furthermore, 3D reconstruction may provide a valuable link between traditional radiography and CAT in evaluating complex fractures. The authors conclude that a comprehensive radio-diagnostic study should be a routine preoperative procedure in complex fractures of the acetabulum, and in all cases where traditional radiography yields doubtful results.

Acetabulum↗
PubMed1989

Cell photosensitization by 5-iminodaunomycin activated with red light.

5-Iminodaunomycin, an anthracycline antitumor drug exhibiting an absorption peak at 595 nm, is shown to photosensitize in vitro cell kill. The photoactivation is performed irradiating the culture dishes during the incubation with the drug for 2 h with 34 mW/cm2 intensity, that is with light doses of up to 245 J/cm2. Long-term effects of administering 50 ng/ml and light for 2 h are studied in terms of growth curves. We show that photoactivation enhances the dark toxicity by a factor of about 10. Immediate cell death is produced by irradiating the cells in the presence of higher drug concentrations (e.g., 1000 ng/ml) which, however, are not toxic in the short term if administered in the dark. The viable cell percentage decreases at increasing light doses, being about 0.6% at the maximum dosage. Administering lower light doses, such as 30 J/cm2, which corresponds to an exposure duration of 15 min, has a short-term effect on the cell survival that strongly depends on the timing of the exposures within the incubation period.

Animals↗
PubMed1989

Triplet state characteristics and singlet oxygen generation properties of anthracyclines.

The triplet states of adriamycin (Ad), daunomycin (D) and two daunomycin analogues, daunomycinone (Dc) and daunomycin N-trifluoroacetamide (DAc), have been studied using laser flash photolysis and pulse radiolysis techniques. Triplet lifetimes, molar absorption coefficients, energy levels and quantum yields have been obtained for Dc and DAc, and estimated for D and Ad. Time-resolved near-infrared singlet oxygen luminescence measurements have been carried out on D, Ad and 5-iminodaunomycin (5-ID) in 2H2O solution and Dc in benzene solution at room temperature. Singlet oxygen quenching by the water-soluble anthracyclines was observed and a second-order rate constant of approx. 10(8) M-1.s-1 obtained. Electron spin resonance experiments have demonstrated that D photoexcited at lambda less than or 365 nm gives rise to singlet oxygen as shown by its reaction with 2,2,6,6-tetramethyl-4-piperidone to give the corresponding nitroxyl radical. Although all the anthracyclines studied have the ability to photosensitize the formation of singlet oxygen, the quantum yields are very low (phi delta approximately 0.02-0.03), suggesting that these anthracyclines would be poor photodynamic sensitisers.

Acetamides↗
PubMed1989

Laser time-resolved fluorescence study of the interaction between anthracyclines and cardiolipin.

The molecular interaction between cardiolipin vesicles and two representative anthracyclines, daunomycin and 5-iminodaunomycin, has been studied at pH 7.1 by laser time-resolved fluorescence, for a cardiolipin-to-anthracycline ratio r ranging from 0.02 to 5. The fluorescence lifetime of daunomycin is 1.03 ns. For r = 0.3 - 5 a longer-lived transient (1.91 - 1.49 ns) is present and originates from the excitation of daunomycin bound on a single phosphate group of cardiolipin. At r = 0.3 two lifetimes are observed, the second one being due, partially, to free daunomycin and bound drug molecules embedded in the lipid bilayer. The fastest-decaying species is present for r = 0.5 - 2.0 and identified as two adjacent, stacked-up daunomycin molecules bound onto the two phosphate groups of the cardiolipin. In the case of 5-iminodaunomycin, a less cardiotoxic analogue, three-exponential decay is never observed and a fast-decaying component, pi approximately 0.2 ns, is already present at low r and vanishes for r greater than 0.5. The constancy of the lifetimes of the longer-lived species may originate from the reorientation of the bound drug from the hydrophilic to the lipid domain.

Antibiotics, Antineoplastic↗
PubMed1989

A double-blind comparative study of ketanserin with atenolol in essential hypertension.

Sixty patients, with mild to moderate essential hypertension, were considered for a double-blind trial comparing the effects of ketanserin and atenolol. After 2 weeks of placebo, a group of 30 patients was given ketanserin 20 mg twice daily for 15 days and 40 mg twice daily for the subsequent 45 days, while the second group (30 patients) was given atenolol for 60 days at the dose of 100 mg once daily. Blood pressure and pulse rate in the supine and standing positions were evaluated every 15 days. After the beginning of treatment with ketanserin, there was a gradual but highly significant decrease of the diastolic and systolic blood pressure values. No important side-effects or significant alterations in the biochemical parameters considered were observed during treatment with ketanserin.

Adult↗