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Biomedical subjects

A Cittadini

Publications and source records attributed to A Cittadini.

At least 109 records · Page 6Linked to original sources
PubMed1992

Evaluation, by noninvasive methods, of the effects of acute loss of thyroid hormones on the heart.

To evaluate the effects of the acute loss of thyroid hormones on the heart the authors studied 11 women with acute hypothyroidism. The cardiac study was performed by means of electrocardiography (ECG), radionuclide ventriculography (RNV) at rest and under effort, and monodimensional echocardiography (MD-echo) and was repeated with ECG and MD-echo after six months of thyroxine suppressive therapy. The ECG showed a significant prolongation of QT interval and flattening and inversion of T wave with normal heart rate. The MD-echo revealed left ventricular function in the normal range and normal left ventricular dimensions. RNV showed the ejection fraction in the lower normal range at rest, which increased to a smaller extent under effort in comparison with a control group. The ECG performed during suppressive therapy with L-thyroxine yielded normal findings with an increase of heart rate and of R wave amplitude, and the MD-echo showed no significant variations of cardiac function due to the increase of heart rate.

Adult↗
PubMed1992

Copper deficiency and pigmentation in the rat: morphofunctional aspects.

The effects of a low copper diet on pigmentation, pigment cell and melanosome morphology have been investigated in ACI/T male rats. After a three months treatment the fur and skin pigmentation is reduced as compared to the controls. The melanocytes of the treated rats show the phenotype of active pigment cells while some melanosomes are abnormally differentiated: both lamellar and granular organelles are present in the same pigment cell and mosaic age melanosomes appear. The abnormal melanosome structure expressed by the treated-rat melanocytes is also evident in vitro. After incubation with deoxycholate the melanosomes from the low-copper diet treated rats are much more altered than those from the control rats. The phenotype of the rats starved for copper seems to mimic as regards pigmentation the phenotype of the mouse Mo (mottled) mutation that is an experimental model of the Menkes' kinky hair syndrome. In conclusion copper deficiency seems to affect both the morphology and function of the pigment cells.

Animals↗
PubMed1991

The effect of magnesium on glycolysis of permeabilized Ehrlich ascites tumor cells.

We have previously observed that extracellular Mg2+ influences the phosphofructokinase (PFK) activity of intact Ehrlich Ascites tumour cells (EATC). In this study we have investigated the mechanism by which Mg2+ modulates this key glycolytic enzyme in EATC made permeable to the cation by either digitonin or dextran sulphate. Results showed that when Mg2+ is freely permeable to the cytosol, the in vivo PFK activity, calculated as FDP/G6P ratio, is not increased as it is in intact cells. We also observed that in permeabilized cells Mg2+ determines the increase of glucose 6 phosphate (G6P), fructose 1,6 bisphosphate (FDP) and lactate production. We hypothesize that extracellular Mg2+ regulates PFK and glycolysis in these neoplastic cells not by entering the cytosol but by a specific interaction with the plasma membrane.

Adenosine Triphosphate↗
PubMed1991

Efficacy of ticlopidine in the prevention of thromboembolic events in patients with VVI pacemakers.

This study was designed to evaluate whether long-term treatment with ticlopidine reduces the incidence of thromboembolic episodes in patients with a VVI pacemaker. One hundred eleven patients with a VVI pacemaker were randomly assigned to two groups: group A (52 patients) was treated with ticlopidine at the dose of 250 mg a day; and group B (59 patients) was not treated and served as a control group. The primary analysis of efficacy of ticlopidine was based on the occurrence of thromboembolic episodes and of cardiovascular and cerebrovascular deaths. The mean follow-up period was 66 months. In group A, there was a significant reduction in the incidence of thromboembolic episodes (P less than 0.05) with a smaller incidence of total cardiovascular and cerebrovascular deaths (8 in group A and 18 in group B; P = 0.05) as compared with group B. Twelve percent of patients had moderate side effects with 1 dropout (epistaxis). Our data confirm the high incidence of thromboembolic events in patients with a VVI pacemaker and demonstrate the efficacy of ticlopidine in preventing them.

Aged↗
PubMed1991

Measurement of the concentration of amphotericin B in brain tissue of scrapie-infected hamsters with a simple and sensitive method.

A simple, sensitive, and reproducible assay for the measurement of the amphotericin B concentration in tissue extracts was developed by using the fourth derivative of the absorption spectrum of amphotericin B between wavelengths of 330 and 430 nm. The amphotericin B concentration in spleen and brain was proportional to the total amount administered. The amphotericin B concentration in the brain was highly correlated with the increase in the mean incubation period of intracerebrally scrapie-infected hamsters.

Amphotericin B↗
PubMed1991

Magnesium in normal and neoplastic cell proliferation: state of the art on in vitro data.

Information about the involvement of Mg2+ in all biochemical processes that participate in cell proliferation is reviewed in order to define the role of this divalent cation in normal and pathological growth. The lack of conclusive data about cell Mg2+ homeostasis does not suggest any definitive model for its role in the control of cell proliferation. On the other hand, new important information about its absolute requirement in crucial steps of cell activation that can, beside other functions, trigger cell division, strongly support the involvement of Mg2+ in the control of cell proliferation. Studies on the growth of cells in vitro, however, while confirming the indispensible requirement for Mg2+ in extracellular media, do not completely clarify the mechanism(s) or the exact phase/point of the cell cycle where Mg2+ exerts its regulation. Furthermore, the observation that tumour cells grown in culture are influenced by external divalent cations confirms the involvement of Mg2+ in cancer as well as in normal cell proliferation. The proposed explanations (theories, hypotheses) are described and discussed.

Animals↗
PubMed1991

Subclinical cardiotoxicity by doxorubicin: a pulsed Doppler echocardiographic study.

In order to detect subclinical levels of Doxorubicin (D) cardiotoxicity, 21 patients aged 42 +/- 8 years with malignancies and treated with D as a part of a multiple regimen, were evaluated. The mean cumulative dose of D was 242 +/- 112 mg.m-2 (150 to 520 mg.m-2). Patients with systemic hypertension, valvular diseases, suspected coronary artery disease, ejection fraction less than 55% as assessed by radionuclide angiography, and aged more than 50 years were excluded from the study. A Doppler echocardiographic examination was performed before and after the course of D therapy with a mean interval of 142 days. The following variables were assessed: fractional shortening (FS), ejection fraction (EF), stroke volume (SV), isovolumic relaxation time (IVRT), maximal early diastolic flow velocity (Emax), maximal late diastolic flow velocity (Amax), and mitral deceleration time (Mdt). Indices derived from 19 aged-matched normal subjects were compared to those of the patients before the course of therapy. Doppler echocardiographic measurements did not differ significantly between the control group and patients before the course of therapy. While there were no significant changes in FS, EF, and SV in the study group before and after therapy, indices of diastolic filling showed striking differences: IVRT changed from 72 +/- 11 to 87 +/- 19 ms (P less than 0.001), Emax from 81 +/- 12 to 65 +/- 17 cm.s-1 (P less than 0.001), Mdt from 174 +/- 25 to 183 +/- 34 ms (P less than 0.05), Amax from 44 +/- 17 to 52 +/- 16 cm.s-1 (P less than 0.01). These data demonstrate impaired diastolic filling after doxorubicin therapy at conventional dosages.

Adult↗
PubMed1989

The effect of Mg2+ upon 6-phosphofructokinase activity in Ehrlich ascites tumor cells in vivo.

The effect of Mg2+ addition to intact Ehrlich ascites tumor cells (EATC) has been investigated. A decrease of glucose 6-phosphate (G6P) content and an increase of fructose 1,6-diphosphate (FDP) content are detected in glucose utilizing EATC incubated with increasing Mg2+ concentrations (from 0 to 5.0 mM). The strong enhancement of FDP/G6P ratio is taken as evidence for in vivo stimulation of phosphofructokinase 1 (PFK) (ATP:D-fructose-6-phosphate 1-phosphotransferase; EC 2.7.1.11). A similar effect can be observed when glucose is replaced by fructose as the glycolytic substrate. Stimulation of PFK is paralleled by substantial depletion of ATP. Cytochalasin B prevents the observed phenomena. Cell total Mg increases by about 15% when EATC are incubated with 5 mM Mg2+. The overall data show that extracellular Mg2+ may modulate glycolytic flux in EATC in vivo. Implications and significance of these phenomena in the regulation of cancer cell metabolic features are discussed.

3-O-Methylglucose↗
PubMed1988

Superoxide dismutase depletion and lipid peroxidation in rat liver microsomal membranes: correlation with liver carcinogenesis.

The depletion of superoxide dismutase in the liver of rats held on a copper-deficient diet for 8 weeks induces two profound modifications in microsomal membrane characteristics. These membranes show: (1) a low degree of peroxidation induced in vitro by both endogenous (NADPH and tert-butylhydroperoxide) and exogenous sources (xanthine/xanthine oxidase) of oxygen radicals as revealed by malondialdehyde and diene-conjugate production; (2) a strong decrease of polyunsaturated and an increase of monounsaturated fatty acid content. These alterations are similar to those found in microsomal membranes from fast-growing hepatomas which exhibit a pronounced saturation of fatty acid pattern and lack superoxide dismutase. These observations support the hypothesis that during hepatocarcinogenesis the loss of superoxide dismutase causes an oxidative stress that increases cellular membrane lipid peroxidation, as a consequence of which the cell responds by synthesizing more saturated fatty acids that permanently modify cell membrane structure and properties.

Animals↗
PubMed1988

Impairment of microsomal calcium sequestration activity upon superoxide dismutase depletion in rat liver.

We have studied the Ca2+-accumulation activity of microsomal vesicles isolated from the liver of rats held for from 2 to 8 weeks on a copper-deficient diet. With this treatment that deeply modifies fatty acid composition, microsomal membranes show progressively lower Ca2+ sequestration. The activity can be fully restored upon physiological copper supply to the depleted animals. The determination of kinetic parameters of microsomal Ca2+ uptake shows that copper deficiency affects mainly the apparent velocity, leaving unaffected the apparent affinity of the pump for Ca2+. Many similarities were found between this model and the Morris hepatomas with different growth rate. The data support the hypothesis that the oxidative stress imposed on the cell by the loss of superoxide dismutase can influence many cell features, with different implications in the regulation of several biological and biochemical functions.

Animals↗
PubMed1987

Further observations on the effect of calcium ionophores on ascites tumor cells.

The effect of the Ca2+ ionophore ionomycin on neoplastic thymocytes in comparison to its effect on normal thymus cells was studied. Ionomycin increases intracellular Ca2+ in normal lymphocytes but fails to increase Ca2+ in neoplastic thymocytes. In these cells the ionophore causes a transient increase in cytosolic free Ca2+. The lack of effect of ionomycin reproduces that of A23187, but it does not depend on reduced availability of intracellular Mg2+ to exchange with Ca2+; it appears to depend on the strong activity of the plasma membrane Ca2+-extruding pump that counteracts ionomycin permeabilization and that can be partly inhibited by the calmodulin inhibitor R24571 (calmidazolium). Neoplastic thymocytes show a high content of magnesium, the intracellular binding of which is efficiently regulated by endogenous ATP. The data show also an interesting correlation between the regulation of energy metabolism (aerobic glycolysis) and cation homeostasis in the neoplastic cells studied.

Animals↗