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Biomedical subjects

G Antonini

Publications and source records attributed to G Antonini.

At least 127 records · Page 7Linked to original sources
PubMed1988

Reversed phase high performance liquid chromatography of adrenocorticotropin 1-39 and its fragments in the native and oxidized forms.

This paper reports HPLC separations of human ACTH 1-39 and its fragments (ACTH 1-10, 4-10, 11-24) making use of original gradient systems. Both H2O2 or chloramine T were demonstrated to oxidize the Met 4 present in ACTH 1-39, 1-10, and 4-10; the oxidized forms were HPLC separated from the corresponding native polypeptides, indicating that this method is suitable for the identification in biological fluid of ACTH, its fragment and their methionine-sulphoxide derivatives with possible relevance to the problem of ageing and inactivation of active polypeptide.

Adrenocorticotropic Hormone↗
PubMed1987

Cytochrome-c oxidase. Subunit structure and proton pumping.

This article reviews the significance of the subunit structure of cytochrome-c oxidase in proton pumping and in particular summarizes available evidences for or against a role of subunit III in the control of this important function of the enzyme.

Chemical Phenomena↗
PubMed1987

Modulation of cytochrome oxidase activity by inorganic and organic phosphate.

The activity of cytochrome oxidase reconstituted into phospholipid vesicles has been studied as a function of orthophosphate, ATP and inositol hexakisphosphate concentrations. The respiratory-control ratio was found to be quite sensitive to these compounds and was inversely related to the anion concentration. This effect is related to a phosphate-dependent decrease in the rate constant for ferrocytochrome c oxidation observed in the presence of ionophores. The data cannot be interpreted simply on the basis of ionic strength, which is known to limit cytochrome c binding to cytochrome oxidase, since cytochrome oxidase-containing vesicles responded differently to phosphate depending on the energization state of the phospholipid membrane.

Adenosine Triphosphate↗
PubMed1987

Reconstitution of monomeric cytochrome c oxidase into phospholipid vesicles yields functionally interacting cytochrome aa3 units.

When the carbon monoxide complex of fully reduced cytochrome c oxidase, reconstituted into liposomes, is mixed with oxygen-containing buffer, complex kinetic progress curves are observed. This pattern is seen irrespective of whether the oxidase used in reconstitution is the dimeric or monomeric (subunit III-depleted) enzyme. These findings are interpreted in the light of similar experiments on the detergent-solubilized enzyme reported by Gibson and Greenwood (Gibson, Q.H., and Greenwood, C. (1963) Biochem. J. 86, 541-554) and confirmed by ourselves. We conclude that reconstitution of monomeric (subunit III-less) enzyme yields, preferentially, vesicles containing more than one functional unit, possibly associated as dimers. This result is of significance to our understanding of the relationships between aggregation state and proton pumping capacity of cytochrome oxidase.

Animals↗
PubMed1987

The effect of saturation with Zn2+ and other metal ions on the antibacterial activity of ovotransferrin.

The antibacterial activity of metal complexes of ovotransferrin was tested "in vitro" against different bacterial species and the Zn2+ saturated ovotransferrin appeared to be the most active by comparison with the apo-protein and other metal complexes. Appropriate controls showed that such an effect was neither due to Zn2+ ions, nor to iron deprivation, but to a specific activity of the Zn-ovotransferrin complex. This antibacterial activity required a direct contact of Zn-ovotransferrin with the bacterial surface. In vivo experiments confirmed the higher antibacterial activity of Zn-ovotransferrin as compared with the apo-form.

Animals↗
PubMed1987

Ambulatory electrocardiographic monitoring in myotonic dystrophy (Steinert's Disease). A study of 22 patients.

Ambulatory electrocardiographic monitoring (AEM) was performed in 22 patients (range 13-62 years; mean age 38.2 +/- 12.7) with grades I, II and III of myotonic dystrophy in order to evaluate the occurrence of potentially dangerous cardiac arrhythmias and conduction disturbances. All patients had previously undergone echocardiographic examination to determine whether structure and function abnormalities were present. In 6 patients with normal resting electrocardiogram, AEM revealed: first degree A-V block (4 cases), class IVa Lown ventricular arrhythmias (3 cases) and episodes of atrial fibrillation (4 cases). In 2 of 3 cases with abnormal scalar electrocardiogram new abnormalities (first degree A-V block and further prolongation of P-R interval) were demonstrated by AEM. Only 1 patient had mild signs of left ventricular dysfunction at echo. Disorders of cardiac conduction and rhythm are characteristic of myotonic dystrophy and can predispose to severe cardiac events. In this respect AEM is shown to be an early and sensitive tool in identifying patients at risk.

Adolescent↗
PubMed1987

A study of several red cell enzyme markers in two samples of the Italian population. Report of new CA1 and PGD variant phenotypes.

Gene frequencies for 17 red cell enzymatic markers have been determined in two samples of the Italian population (Lombardy and Tuscany regions). A significant difference was found between the two samples for the AK1 and PGM1 systems (AK1*2 .028 and .044, PGM1*2 .254 and .301 in Lombardy and Tuscany respectively). Variant phenotypes, for PEPA, PEPB, CA2, PGM2, PGD and GPT markers, have been observed; some of these are due to new alleles occurring at the CA2 and PGD loci.

Alleles↗
PubMed1986

Transient kinetics of subunit-III-depleted cytochrome c oxidase.

Cytochrome c oxidase from ox heart was depleted of subunit III and its transient kinetic properties studied by stopped-flow and flash photolysis. It was found that the overall mechanism of electron transfer is very similar for subunit-III-depleted and native oxidase, although significant differences in some kinetic parameters have been detected. These include the second-order rate constant for cytochrome c oxidation and the rate-limiting step of the overall process. Moreover, at low cytochrome c/oxidase ratios (where the number of reducing equivalents is insufficient), the rate of reoxidation of cytochrome a was found to be very slow, even in air, and in fact for the subunit-III-depleted enzyme is even slower than for the native oxidase. The stability of reduced cytochrome a excludes the likelihood that removal of subunit III leads to a new O2-binding site, and the result may be relevant to the lowered vectorial H+/e- stoichiometry. The subunit-III-depleted oxidase can be pulsed under appropriate conditions and its combination with CO is unchanged, as shown by kinetic experiments and difference spectroscopy.

Animals↗
PubMed1986

Effect of sodium selenite on guinea-pig cardiac isolated mitochondria.

The pre-incubation with sodium selenite reduces the respiratory index in guinea-pig cardiac mitochondria when alpha-ketoglutarate and glutamate are used as substrates. This decrease is dose-dependent. On the other hand, no modification in respiratory index is measured with malate or malate plus pyruvate. The effect on sodium selenite is prevented by CoA administration. Moreover, 25 microM sodium selenite reduces the Km and Vmax of alpha-ketoglutarate dehydrogenase measured at steady-state with variable amount of CoA.

Animals↗
PubMed1986

Peripheral neuropathy and ototoxicity of dichlorodiamineplatinum: instrumental evaluation. Preliminary results.

Clinical use of cis-platinum in the treatment of many human tumors is increasing. Since side effects could represent a limitation of its use, we evaluated neurotoxic effects of this compound in a group of 23 patients on antiblastic treatment for gynecological neoplasms. Evaluation was performed by clinical-neurological examination, neurophysiological data (electromyography, maximal motor conduction velocity, and sensory conduction velocity) and potentials. Seven patients reported subjective symptoms of neurological involvement. In 2 cases there was a change in the electromyographic pattern. The otolaryngological examination showed a change in the hearing threshold in 3 patients and in 1 case the fatigue test was positive. Neurotoxic effects and hearing damage was not related to the treatment schedule.

Adolescent↗
PubMed1986

The response of ventral horn neurons to ricin. An experimental abiotrophy model.

The morphological alterations of anterior horn neurons of the spinal cord of rabbits produced by the administration of ricin conveyed via retrograde axonal flow are described. The differences with the primary response after axonal transection and the similarity with degenerative abiotrophic systemic lesions are discussed.

Animals↗
PubMed1985

Mechanism of control of cytochrome oxidase activity by the electrochemical-potential gradient.

Cytochrome c oxidation by bovine cytochrome oxidase embedded into liposomal vesicles with high respiratory control ratio (RCR = 6-10) has been studied by rapid-mixing experiments in the presence and absence of different ionophores. Kinetic analysis of the reaction indicates a linkage between the intrinsic activity of the enzyme, the efficiency of coupling and the electrochemical potential across the membrane. A simple model, based on two allosteric states with different catalytic properties in rapid equilibrium, is presented and successfully applied in the simulation of the observed time-course.

Animals↗
PubMed1985

Antifungal activity of ovotransferrin towards genus Candida.

The inhibiting activity of ovotransferrin was tested towards different species belonging to genus Candida. Of one hundred strains tested, only C. krusei showed a noticeable resistance, while the other species appeared to be more sensitive than bacteria to the action of ovotransferrin. The influence of anions, such as bicarbonate and citrate, on the inhibiting activity of ovotransferrin was also investigated. Moreover it was observed that iron saturated ovotransferrin retained its activity, thus suggesting an interaction between the protein and Candida cells.

Antifungal Agents↗