Search PubMed⌕ Search

Biomedical subjects

M Mariani

Publications and source records attributed to M Mariani.

At least 199 records · Page 11Linked to original sources
PubMed1990

Morphological alterations induced by doxorubicin in B16 melanoma cells.

In B16 melanoma, cells morphologically different can be distinguished. In order to establish possible correlations between cell morphology and drug-response, the cytotoxic response to doxorubicin was analyzed. The two subpopulations, represented by two types of colonies, showed a different degree of sensitivity to doxorubicin. Moreover, following treatment, colonies strongly altered in their morphology were found, suggesting a differentiating activity of doxorubicin (dendritic prolongations, increase of intracellular melanin, block of cell proliferation). These results suggest that doxorubicin, besides having a different cytotoxic effect on the two cell subpopulations, induces in this cell line morphological alterations consistent with a differentiation process.

Animals↗
PubMed1990

Comparison of DNA cleavage induced by etoposide and doxorubicin in two human small-cell lung cancer lines with different sensitivities to topoisomerase II inhibitors.

In an attempt to clarify the role of drug-induced protein-associated DNA breaks (i.e., DNA topoisomerase II-mediated DNA cleavage) in the cytotoxic activity of doxorubicin and etoposide, their cellular effects were compared in 2 human small-cell lung cancer (SCLC) lines, characterized by differential sensitivity to DNA topoisomerase II inhibitors. These drugs were selected for comparative studies since they are among the most effective agents in the treatment of SCLC. H146 and N592 cell lines were obtained from pleural effusion and bone-marrow aspirate of pretreated patients, respectively. Both cell lines grew as floating aggregates with similar doubling times (30 and 33 hr for N592 and H146 cells, respectively). Although, immediately after 1 hr exposure to equitoxic drug levels, the extent of DNA cleavage produced by doxorubicin was markedly lower than that produced by etoposide, DNA lesions produced by doxorubicin persisted and even increased following drug removal. In contrast, an almost complete disappearance of etoposide-induced DNA breaks was noted 1 hr after drug removal. Resealing of strand breaks was faster in N592 than in H146 cells. These findings suggest that reversal of these lesions plays a major role in cell survival rather than the occurrence of DNA breaks immediately following drug exposure. This observation is consistent with the view that inhibition of DNA re-ligation rather than stimulation of DNA cleavage is the critical step for drug action. The different response of these cell lines to cytotoxic action of the topoisomerase inhibitors is associated with a differential drug effect on DNA integrity (detected as DNA double-strand breaks and DNA-protein cross-links). However DNA lesions were comparable when cells were exposed to equitoxic drug levels. The observation that etoposide-induced DNA breaks were similar in isolated nuclei from both cell lines suggests that drug-target interaction is modulated in a different manner in the intact cell. As indicated by doxorubicin uptake and retention, cellular drug pharmacokinetics do not account for the different drug response of the studied SCLC lines, presumably, reflecting a different extent of DNA break formation and/or a different cytotoxic consequence of DNA damage.

Carcinoma, Small Cell↗
PubMed1990

Murine monoclonal antibody recognizing a 90-kDa cell-surface determinant selectively lost by multi-drug-resistant variants of CEM cells.

We describe a murine IgG1 monoclonal antibody (MAb56), specific for a cell-surface protein structure (MC56 determinant) expressed by the human CEM cell line. A large band of approximately 90 kDa was identified as the main specific component of the MC56 determinant. Such a 90-kDa protein is significantly associated with the drug-sensitive phenotype, its expression being progressively reduced quantitatively in multi-drug-resistant (MDR) variants of CEM cells, according to the extent of drug resistance. In addition, the MC56 determinant is expressed de novo in drug-sensitive revertant cell lines derived from MDR cells and unreactive with the MAb56. The MAb56 shows a high affinity towards the immunizing drug-sensitive CEM cell line (Ka = 1.86 x 10(9) L/mole) while not binding to MDR cell variants. The expression of the MC56 molecule on a variety of human cells and tissues makes such a cellular determinant a candidate as a marker for studying the MDR phenomenon both in vivo and in vitro.

Animals↗
PubMed1990

Fatty acid acylation of membrane skeletal proteins in human erythrocytes.

Fatty acid acylation of membrane proteins was studied on human erythrocytes by measuring incorporation of [3H]palmitate at different specific radioactivities. A 55 kDa polypeptide within the band 4.5 region was the main acceptor protein for acylation by fatty acids (palmitate, stearate, oleate), while other polypeptides (80, 65, 48, 30 kDa) incorporated [3H]palmitate slowly, in substoichiometric amounts. Integral membrane proteins were preferentially fatty acid acylated. Skeletal membrane proteins were, however, poorly labeled. Neither purified ankyrin nor band 4.1 protein were fatty acid acylated in human erythrocytes. On the other hand, label associated with high molecular weight skeletal proteins resisted low and high ionic strength extractions, and was extracted selectively by urea [corrected] along with a small subpopulation of spectrin which was also tightly associated with the membrane.

Acylation↗
PubMed1990

Left ventricular aneurysm: clinical and hemodynamic data.

Clinical and hemodynamic data of 30 patients with left ventricular aneurysm (27 men, 3 women, mean age 54.9 years) were compared with those of 30 patients with previous myocardial infarction and segmental hypo- or akinesis (28 men, 2 women, mean age 51 years). In each group, 10 patients were affected by one-, two-, or three-vessel disease. A semiquantitative evaluation of collateral coronary circulation showed no significant differences between the two groups. Mean end-diastolic volume was higher in patients with left ventricular aneurysm (p less than .025, less than .05, and less than .001 in 1-, 2-, and 3-vessel disease, respectively) and ejection fraction was lower only in patients with one-, (p less than .001) and two- (p less than .05) vessel disease in comparison with patients without left ventricular aneurysm. No significant difference was evidenced in basal or isometric exercise end-diastolic pressure. The incidence of thrombosis detected by ventriculography was higher in patients with left ventricular aneurysm (33.3 vs. 6.6%). The mean duration of follow-up was 20.7 months in patients with left ventricular aneurysm and 20.6 in the control group. No significant difference was found either in mortality or in reinfarction rate as far as incidence and severity of angina. The incidence of congestive heart failure was more evident, but not significant in patients with left ventricular aneurysm. One embolic episode was present in one patient with aneurysm and intraventricular thrombosis. Left ventricular performance is influenced by an aneurysm when a limited coronary compromise is present (one- and two-vessel disease) while it is not affected in the case of a coexisting three-vessel disease.

Adult↗
PubMed1990

Major antigenic domain recognized by monoclonal antibodies maps within the carboxy-terminal moiety of a recombinant human immunodeficiency virus-1 p24 protein.

Antigenicity in mice of a recombinant polypeptide including the complete amino acid sequence of mature human immunodeficiency virus type 1 p24 protein was studied by induction of monoclonal antibodies (MAbs). A panel of nine recloned hybridomas secreting MAbs with anti-p24 reactivity was isolated and further characterized. Competitive inhibition experiments suggested that the MAbs could be grouped into four epitopic classes corresponding to at least two distinct determinants. Analysis of reactivity to recombinant p24 deletion variants indicated that all the recognized epitopes are localized within a carboxy-terminal domain (amino acids 168-208) which should be largely exposed in recombinant as well as authentic antigen. Lack of response to N-terminal and central portions of p24 suggests that the antigenicity of those regions in the natural polypeptide is strongly conformation-dependent.

Antibodies, Monoclonal↗
PubMed1990

Four year double-blind controlled study of levamisole in multiple sclerosis.

41 patients with definite multiple sclerosis (MS) in the stationary phase entered this four year double-blind levamisole-placebo controlled study. 22 patients were treated with levamisole, 150 or 200 mg once a week for a 4 year period, and other 19 with placebo with the same schedule. Patients were put in one of the two groups at random. The treatment was then stopped for those patients who presented a clear exacerbation before the end of the 4 year trial period, and these cases have been considered as negative. Of the group treated with levamisole 8 patients presented an exacerbation during the observation period, and 14 did not. The group treated with placebo presented 14 subjects who had exacerbations and 5 patients who did not. The difference between the two groups was statistically significant. This study demonstrates that levamisole significantly reduced the number of MS patients with acute relapse during the 4 year period of treatment. Nevertheless, not all patients were free from relapse: that could probably suggest that different immunopathological backgrounds may underlie what we usually call MS.

Adolescent↗
PubMed1990

Purine release from isolated rat heart: a new approach to the study of energy metabolism.

The rate of release of purines (adenosine, inosine, hypoxanthine, xanthine and uric acid) from isolated working rat hearts was measured and compared to tissue concentrations of high energy phosphate compounds. Hearts were subjected to different workloads, and perfusions were performed: with normal oxygen supply (group 1); with the addition of insulin to the standard perfusion buffer, which contained glucose as energy source (group 2); in hypoxic conditions (group 3). In each group purine release increased (P less than 0.01) at higher workload and was closely related to indices of mechanical performance such as cardiac output or minute work (r = 0.902 and 0.858 in group 1, r = 0.902 and 0.851 in group 2, r = 0.851 and 0.881 in group 3, P less than 0.001 in each case). Work had no effect on adenine nucleotides but produced a significant (P less than 0.01) reduction in phosphocreatine/creatine ratio. The comparison of different groups showed that at any level of heart performance purine release was higher (P less than 0.001) in group 3 vs. group 1, and lower (P less than 0.001) in group 2 vs. group 1. High energy phosphates were reduced in group 3 vs. group 1 but were unchanged in group 2 vs. group 1. We conclude that in the isolated heart purine release is directly related to the rate of energy consumption, and inversely related to the rate of energy production. Purine release provides a sensitive method to evaluate myocardial energy metabolism, which is more sensitive than measurement of high energy phosphates.

Animals↗
PubMed1990

Gene transfer by retrovirus-derived shuttle vectors in the generation of murine bispecific monoclonal antibodies.

The present study reports on the use of gene transfer by retrovirus-derived shuttle vectors in the generation of hybrid hybridomas secreting bispecific monoclonal antibodies. neo- and dhfr- genes were infected into distinct murine hybridomas, thus conferring a dominant resistance trait to geneticin (G418) and to methotrexate. The vectors employed were replication-deficient and dependent on complementation by a helper virus provided by the irradiated packaging lines. After cocultivation with the relevant packaging cell lines, stable hybridoma lines expressing the selectable markers were easily obtained and were then suitable for conventional somatic fusion. This high-efficiency method was used to generate two bispecific monoclonal antibodies simultaneously targeting molecules expressed on cytotoxic cells (i.e., T lymphocytes and natural killer cells) against a human melanoma-associated antigen.

Animals↗
PubMed1990

Adenine nucleotide depletion and contractile dysfunction in the "stunned" myocardium.

STUDY OBJECTIVE: The aim of the study was to assess the contribution of adenine nucleotide depletion to postischaemic myocardial dysfunction ("stunned" myocardium). DESIGN: Isolated perfused hearts release purine catabolites even in the absence of ischaemia, and undergo spontaneous reduction of adenine nucleotide pool. A comparison was therefore made between mechanical function, purine release and tissue adenine nucleotides in working rat hearts reperfused after short term ischaemia or subjected to prolonged perfusion (up to 180 min). EXPERIMENTAL MATERIAL: 49 Sprague-Dawley rats of 250-300 g body weight were used. The animals were anaesthetised and the hearts quickly excised and perfused with the working heart technique. MEASUREMENTS AND MAIN RESULTS: Reperfusion after 10 min ischaemia provided a good model of "stunned" myocardium: aortic flow and minute work decreased by 15(SEM 2)% and 20(3)%, no enzyme leakage was observed, and the adenine nucleotide pool decreased by 3.5(0.4) mumols.g-1. During prolonged perfusion no change was observed in any haemodynamic variable until the adenine nucleotide pool was depleted by over 8.5 mumols.g-1. Adenylate energy charge and the phosphocreatine-creatine pool were unchanged in all cases. CONCLUSIONS: Depletion of adenine nucleotides does not account for contractile dysfunction in our model of "stunned" myocardium.

Adenine Nucleotides↗
PubMed1990

Phase II study of high-dose epirubicin in untreated patients with small-cell lung cancer.

Eighteen previously untreated patients with histologically confirmed small-cell lung cancer were treated with high-dose epirubicin (course 1, 100 mg/m2; courses 2-6, 140 mg/m2, day 1), every 3 weeks. Overall response rate was 33% (95% confidence limits, 14-52%), including two complete and four partial responses. The response rates for limited (n = 11) and extensive (n = 7) disease patients were 45% and 14%, respectively. With a median follow-up of 18 months, estimated 2-year survival of all patients was 29% and the median duration of response 18.5 months. The dose-limiting toxicity was myelosuppression, with a median granulocyte nadir of 1,150/mm3; 39% of patients had neutropenic fever. Nausea/vomiting, alopecia, and stomatitis were the most common nonhematological toxicities, usually mild to moderate. Acute cardiac toxicity was unusual and no episodes of congestive heart failure were observed. Cumulative doses of 800 mg/m2 were associated with moderate cardiotoxicity (grade 2), as assessed by endomyocardial biopsy and electron microscopy analysis. These results indicate that epirubicin, at the present doses and schedule, is an active single agent in patients with small-cell lung cancer, with acceptable general and moderate cardiac toxicity.

Aged↗
PubMed1990

Semen anomalies due to voiding defects of the ampullo-vesicular tract. Infertility due to ampullo-vesicular voiding defects.

Anatomical (congenital or postinflammatory) or functional anomalies of the uroseminal intersection can induce a voiding dysfunction of the deferential ampullae and seminal vesicles, leading to infertility. In case of azoospermia or OAT-syndrome with poor semen volume and decreased vesicular markers, some clinical history and examination data can cause suspect of one of such anomalies. The transrectal ultrasonographic findings of anechoic area(s) inside the prostate and/or seminal vesicle (even after recent ejaculation), the peculiar vasovesiculographic pictures (especially after ejaculation following the contrast medium injection into the vasa deferentia), plus the evaluation of the "deferential-ampullary sperm reserve", will permit a detailed diagnosis of the voiding dysfunction of the uroseminal crossing. A successful appropriate treatment of these pathologies can be done. Ultrasonically-guided transrectal puncture, or transurethral incision upstream of (or resection of) the ejaculatory duct orifices, or prolonged sexual abstinence, or artificial spermatocele of the vas deferens, or sperm recovering from urine for GIFT or IVF/ET after washing-out of the seminal tract by vas puncture are all methods, which can be selectively used depending on the individual case, to treat these forms of infertility. The authors present some paradigmatic clinical cases, and report that this pathology presumably occurs in up to 9% of non-selected infertile patient population.

Adult↗
PubMed1990

Alpha-1 adrenoceptor involvement in the control of melatonin secretion in the golden hamster.

The nocturnal peak in pineal and serum melatonin content was reduced following administration of the selective alpha-1 adrenoceptor antagonist prazosin in a dose of 0.25 mg/kg. The effect was pronounced one hour post treatment during the late dark phase of the daily photocycle. These data confirm the reported findings that the hamster pineal sensitivity to adrenergic challenge is confined to the second part of the dark phase and indicate that postsynaptically located alpha-1 adrenoceptors are also involved in the physiological control of melatonin synthesis and/or release in that species.

Animals↗
PubMed1990

Failure of prazosin to mimic the effects of melatonin under in vivo and in vitro conditions.

The gonads of male hamsters exposed to short photoperiod (LD, 10:14) or treated with melatonin in the late afternoon under long photoperiod (LD, 14:10) had undergone complete regression by the end of the treatments (8 weeks). Animals treated for the same period of time with prazosin (a putative melatonin analogue) under the same conditions failed to show a difference in their gonadal status as compared to the long photoperiod controls. Prazosin was unable to prevent melatonin-induced gonadal atrophy when injected either in the morning or 30 min before melatonin. Moreover, prazosin was without any effect on (and unable to prevent the melatonin-stimulated) progesterone production by rat adrenals under in vitro conditions. These data demonstrate that prazosin, which reportedly inhibits 2-[125I]iodomelatonin binding in the hamster brain in an affinity-related manner, does not possess properties of a biological melatonin analogue under conditions of two different model systems in two species.

Adrenal Glands↗
PubMed1990

Comparison of the rat pinealocyte ultrastructure with melatonin concentrations during daytime and at night.

The aim of this study was to investigate the ultrastructure of rat pinealocyte during daytime (1600 h) and at night (0100 h) and to compare these observations with serum melatonin levels in the same animals. In addition, pineal melatonin concentrations were determined in other animals. Both serum and pineal melatonin concentrations were significantly higher at night than during daytime (34 and 21 times, respectively). Sizes of pinealocytes, their nuclei, and nucleoli, as well as cross-sectional areas of mitochondria and granular endoplasmic reticulum were also higher at night than during daytime, whereas areas of lysosomes, Golgi apparatus, and vacuoles containing flocculent material did not differ at the time points studied. In contrast, the number of dense-core vesicles was higher during daytime. The results of the present study show that morphological patterns of higher metabolic activity of the rat pinealocyte at night when compared to those during daytime correlate with melatonin concentrations.

Animals↗
PubMed1990

On the usefulness of levothyroxine suppressive therapy in the medical treatment of benign solitary, solid or predominantly solid, thyroid nodules.

The efficacy of levothyroxine suppressive therapy in the treatment of benign solitary thyroid nodules is controversial. In order to investigate this issue further we studied 122 patients with a solitary, solid or predominantly solid, thyroid nodule. The benign (colloid) nature of all nodules was proved by fine-needle aspiration biopsy. At the pertechnetate-99m thyroid scanning 91% of the nodules were "cold" and 9% "warm". All the patients received suppressive oral doses of levothyroxine (0.1 to 0.2 mg/day). Fifty-three patients were treated with levothyroxine for 6 months, 31 for 9 months and 38 for 12 months. The size of each nodule before and after treatment was evaluated by high-resolution ultrasonography. The actual suppression of TSH secretion was monitored at 3-month intervals using an ultrasensitive immunometric assay. At the end of levothyroxine treatment, patients were classified as responders (decrease in nodule volume greater than or equal to 50%, 68/122 = 55.7%; mean percent change in nodule volume = -77.1 +/- 15.7%), partially responders (decrease in nodule volume less than 50%, 24/122 = 19.7%; mean percent change in nodule volume = -27.5 +/- 10.1%), and nonresponders, when either no change in nodule volume (16/122 = 13.1%) or an increase in nodule volume (14/122 = 11.5%) was observed. In each group serum free T4 rose significantly in response to levothyroxine therapy, whereas serum free T3 remained unchanged. TSH levels were undetectable in all patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1990

Effect of amrinone in the working rat heart: influence of ischaemic damage, adenosine and calcium.

The action of amrinone on the isolated working rat heart was studied. In basal conditions up to 400 mg/l amrinone behaved as a pure chronotropic agent, raising the heart rate by 23%. In ischaemia-damaged hearts 100 mg/l amrinone had a true inotropic action, provoking significant increases in cardiac output (11%), aortic flow (10%) and double product (9%). The addition of 10 microM adenosine, which inhibits the inotropic action of catecholamines, did not modify the response to amrinone. However, when calcium was reduced from 2.5 to 1.25 mM, the inotropy of ischaemia-damaged hearts was not significantly affected by amrinone, and its chronotropic action was reduced. It is concluded that after acute ischaemic damage amrinone increases heart performance even in a poorly responsive species in which no inotropic effect can be produced under basal conditions. In this model its action is resistant to adenosine but depends on the availability of a sufficient amount of extracellular calcium.

Adenosine↗