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Biomedical subjects

M Barbieri

Publications and source records attributed to M Barbieri.

At least 109 records · Page 6Linked to original sources
PubMed1994

Electrophysiological basis for the enhanced cardiac arrhythmogenic effect of isoprenaline in aged spontaneously hypertensive rats.

We used normotensive (WKY) and spontaneously hypertensive rats (SHR) of 2, 6 and 18 months of age to get insight into the mechanisms responsible for the increased incidence of ventricular arrhythmias in hypertensive heart disease. We studied: (1) isoprenaline-induced spontaneous activity in isolated papillary muscle; (2) action potential characteristics; (3) beta-adrenoceptor and A1-adenosine receptor number and affinity; and (4) intracellular cyclic AMP (cAMP) levels. The saturation binding assay was performed in enzymatically isolated ventricular myocytes using the hydrophilic antagonist 3H-CGP 12177 for beta-adrenoceptors and 3H-DPCPX for A1-adenosine receptors. cAMP was measured by a competitive binding assay in myocytes before and after exposure to isoprenaline. Intracellular action potential was recorded from papillary muscles by means of 3 M KCl-filled glass microelectrodes. The presence of isoprenaline-induced automaticity was assessed by interrupting the electrical stimulation periodically. In isolated papillary muscles, isoprenaline (10 nM) induced spontaneous activity more frequently in 18-month-old SHR (90.0%) than in 6-(25.0%, P < 0.05) and 2-month-old SHR (0%, P < 0.001). No age-related statistically significant differences in isoprenaline-induced automaticity were observed in WKY. The incidence of isoprenaline-induced automaticity was higher in 18-month-old SHR than in age-matched WKY (22.2%, P < 0.05). KD and Bmax for beta-adrenoceptors and A1-receptors were not significantly modified in different groups. cAMP levels before and after isoprenaline stimulation were significantly lower in 18-month-old SHR than in age-matched WKY. Action potential duration (APD) was markedly prolonged in both normotensive and hypertensive rats during aging. APD was significantly prolonged in 18-month-old SHR compared to the WKY. A "diastolic depolarization", caused by the presence of delayed after-depolarizations, became apparent in the oldest animals. The slope of the delayed after-depolarization was increased by isoprenaline (1-10 nM) in 18-month-old SHR and this effect was significantly greater than that observed in 18-month-old WKY (P < 0.05). In conclusion, beta-adrenergic responsiveness is enhanced in hypertensive rats during aging, resulting in a greater incidence of abnormal automaticity. This effect does not appear to be related to changes in beta-adrenoceptor or A1-receptor density or affinity; it is likely that the electrophysiological alterations may play a role in this phenomenon.

Action Potentials↗
PubMed1994

Use of specific antibody and circulating antigen serum levels in the hydatid immunodiagnosis of asymptomatic population.

Levels of specific antibodies (Ab) and circulating antigens (CAg) were tested by ELISA in sera from 115 surgically confirmed hydatid patients, 41 individuals exhibiting other parasitic and unrelated diseases and 69 healthy subjects. Addition of CAg data to Ab detection in this sera collection increased sensitivity from 85% (only Ab) to 89% (Ab + CAg). Combination of ultrasonography with Ab and CAg serology for diagnosis of asymptomatic population in endemic areas was analyzed. One field survey (163 persons) involved both blood extraction and ultrasonography to all the population. Three people exhibited cyst images and all of them were Ab positive, while 6 Ab and 1 CAg positive individuals exhibited no cyst image. Another survey (1620 persons) involved a selection of 85 subjects for serology according to ultrasound data and record of family hydatid history. Twelve per cent exhibited no hydatid image being serologically positive and 14% were serologically negative but exhibited cyst image. Ultrasonography and serology (Ab and CAg) should be used in combination to maximize the diagnostic yield in asymptomatic population.

Antibodies, Helminth↗
PubMed1994

Ionic basis of action potential prolongation of hypertrophied cardiac myocytes isolated from hypertensive rats of different ages.

OBJECTIVE: The aim was to determine the ionic basis of action potential lengthening associated with cardiac hypertrophy. METHODS: Action potentials and ionic currents of left ventricular myocytes isolated from normal and hypertrophied hearts were recorded with patch pipettes. Since cardiac hypertrophy is a time dependent process, myocytes isolated from hearts of spontaneously hypertensive rats (SHR) of different ages (3 and 18 months old) were compared with those of age matched normotensive controls (Wistar Kyoto rats, WKY). RESULTS: Membrane capacitance, an index of cell size, was significantly higher in SHR than WKY. The degree of action potential prolongation was independently correlated with hypertension and its duration, resulting in a statistically significant lengthening of action potential in 18 month old SHR compared to age matched WKY and to 3 month old SHR. ICa,L density was not significantly modified in hypertrophied myocytes compared to normal controls. Depolarising steps positive to -40 mV activated an outward current, which was composed of both transient (ItO) and maintained components (Ilate) and played a major role in controlling repolarisation in rat ventricular myocytes. Ito density was significantly reduced in SHR myocytes compared to age matched WKY and was also smaller in 18 month old compared to 3 month old SHR. Ilate was not statistically different in 3 and 18 month old SHR and WKY. Current-voltage relationships for IK1 were completely superimposable in all groups. CONCLUSIONS: Prolongation of action potential in the hypertrophied heart of SHR is due to specific alterations in the repolarising potassium current Ito. The phenomenon is directly related to the duration of hypertension.

Action Potentials↗
PubMed1994

Minoxidil (Mx) as a prophylaxis of doxorubicin--induced alopecia.

BACKGROUND: Minoxidil (Mx) is known to induce hair growth in men with male-pattern baldness. Based on this potential, the effectiveness of Mx 2% topical solution was evaluated in cancer patients (pts) to prevent doxorubicin-induced alopecia. PATIENTS AND METHODS: 48 female pts with different types of solid tumors treated with doxorubicin-based chemotherapy in a dose range of 50-60 mg/m2/cycle were randomly assigned to receive Mx 2% topical solution or placebo. RESULTS: 88% and 92% of pts in both arms showed severe alopecia (p = ns). No adverse effects were observed. CONCLUSION: In this study Mx 2% topical solution was non-toxic but was not effective in the prevention of chemotherapy-induced alopecia.

Adult↗
PubMed1993

High performance latex reagent for hydatid serology using an Echinococcus granulosus lipoprotein antigen fraction purified from cyst fluid in one step.

A lipoprotein fraction from fertile bovine hydatid cyst fluid (FBHCF) was isolated by affinity chromatography on acrylic-heparin. The heparin-binding lipoprotein fraction (HBLF) was proved to be free from host immunoglobulins and albumin. Immunoblotting with confirmed human hydatid sera showed that the major relevant diagnostic bands in FBHCF were also present in HBLF. HBLF or FBHCF were used to sensitize polystyrene latex particles. HBLF-latex showed both higher reactivity with positive hydatid human sera and higher batch-to-batch reproducibility than FBHCF-latex. Titration of sera from 119 surgically confirmed hydatid patients, 48 with other parasitic diseases, 6 with unrelated diseases and 37 healthy subjects was performed using HBLF-latex and conventional ELISA (using FBHCF). Sensitivity and specificity were 83 and 87% for ELISA and 87 and 88% for HBLF-latex. These results indicate that, while being simpler and faster to perform, the HBLF-latex has a similar diagnostic value to that of the conventional ELISA test.

Agglutination Tests↗
PubMed1993

The riboskeleton: the "brain" of the cell?

The complexity of the RNA world has surprised biologists many times in recent years and has led, among other things, to a new definition of a gene. Its implications, however, may go even further than that. It is possible that the ribonucleoproteins form an information processing system which functions as the "brain" of the cell.

Animals↗
PubMed1992

[Abdominal visceral lesions in patients with multiple trauma].

The paper describes a series of 385 cases of multiple injuries which were treated between 1987 and 1991 at the Emergency Unit of the Fatebenefratelli Hospital in Milan. Special attention was paid to abdominal trauma and visceral injuries in terms of both diagnosis and treatment.

Abdominal Injuries↗
PubMed1992

Prolonged propionyl-L-carnitine pre-treatment of rabbit: biochemical, hemodynamic and electrophysiological effects on myocardium.

Recently it has been reported that prolonged treatment with propionyl-L-carnitine, a carnitine derivative, results in a positive inotropic effect. To gain further insight into its mode of action, we pre-treated 253 rabbits for up to 10 days with daily doses of 1 mmol/kg propionyl-L-carnitine or L-carnitine intraperitoneally, using saline-treated animals as control. Twenty-four hours after the last injection, we isolated papillary muscles for electrophysiological investigations. Whole hearts were used in perfusion experiments for biochemical and hemodynamic measurements. In addition, mitochondria were harvested from these hearts for the analysis of their function. Plasma and cardiac levels of free carnitine, along with plasma short-chain acylcarnitines, increased at least two-fold after treatment with carnitine or its propionyl-ester, with concomitant rises in tissue long-chain acylcarnitine and long-chain acyl-CoA. At the time of animal sacrifice, treatment did not increase plasma or tissue propionyl-L-carnitine content. The studies carried out with perfused hearts and isolated mitochondria failed to show an effect of propionyl-L-carnitine pre-treatment on high-energy phosphate metabolism or respiration. Papillary muscles from animals, treated for 10 days, showed a lengthening of the action potential duration from 63 +/- 4 to 102 +/- 6 ms (P less than 0.001) at -10 mV. Perfused hearts from these rabbits displayed positive inotropy, as indicated by an improved pressure development at higher ventricular filling volumes, e.g., from 39 +/- 4 to 60 +/- 3 mmHg (P less than 0.05) at 3.6 ml. Pre-treatment with L-carnitine or saline failed to affect the electrophysiological and hemodynamic variables. Thus, prolonged treatment of rabbits with propionyl-L-carnitine, but not with L-carnitine, improved contractility and lengthened action potential duration in isolated muscle preparations.

Action Potentials↗
PubMed1991

Cardiac electrophysiological effects of a new dihydropyridine calcium antagonist (BBR 2160).

BBR 2160 is a new dihydropyridine derivative belonging to the group of the so-called tiampidines. We used intracellular microelectrodes to characterize the electrophysiological properties of BBR 2160 on sheep Purkinje fibres and guinea-pig papillary muscle. BBR 2160 (10(-7) and 10(-6) M) dose dependently decreased the contractility of driven Purkinje fibre and papillary muscle. This effect was associated with a lowering of the plateau phase and a shortening of action potential duration in papillary muscle. The effect of the drug developed quite slowly over time. The amplitude and Vmax of normal action potential were not affected by BBR 2160. Instead BBR 2160 reduced the amplitude and Vmax of the slow action potentials (which are a relatively good index of the slow inward current) induced by histamine (10(-5) M) in K(+)-depolarized (22 mM) papillary muscle. The results suggest that BBR 2160 has calcium-antagonistic properties in cardiac tissue.

Action Potentials↗
PubMed1991

Lack of correlation between the antiarrhythmic effect of L-propionylcarnitine on reoxygenation-induced arrhythmias and its electrophysiological properties.

1. The antiarrhythmic effect of L-propionylcarnitine (L-PC) was evaluated in the guinea-pig isolated heart; arrhythmias were induced with hypoxia followed by reoxygenation and by digitalis intoxication. 2. L-PC 1 microM, was found to be the minimal but effective antiarrhythmic concentration against reoxygenation-induced ventricular fibrillation. No antiarrhythmic effect was observed against digitalis-induced arrhythmias. D-Propionylcarnitine, L-carnitine and propionic acid did not exert antiarrhythmic effects. 3. During hypoxia and reoxygenation L-PC consistently prevented the rise of the diastolic left ventricular pressure, and significantly reduced the release of the cardiac enzymes creatine kinase (CK) and lactic dehydrogenase (LDH). 4. The electrophysiological effects of L-PC were then studied on either normal sheep cardiac Purkinje fibres or those manifesting oscillatory after potentials induced by barium or strophanthidin. 5. L-PC (1 and 10 microM) did not significantly modify action potential characteristics and contractility of normal Purkinje fibres, or the amplitude of OAP induced by strophanthidin or barium. 6. It is concluded that the antiarrhythmic action of L-PC on reoxygenation-induced arrhythmias is not correlated with its direct electrophysiological effects studied on normoxic preparations.

Animals↗
PubMed1989

The reconstruction principle.

The theory of epigenesis is the undisputed paradigm of embryology, and it is still based on the classical concept proposed by Aristotle: the idea that embryonic development is a generation of structures which takes place according to a design--today we say a set of instructions--already present in the fertilized egg. This is a doctrine which can be referred to as 'pre-information', since it claims the preexistence of information exactly as the old theory of preformation claimed the preexistence of form. Here, however, it is shown that a more general version of epigenesis can be held, because of a new principle which states that it is mathematically possible to obtain not only a convergent generation of form, or structure, but also a convergent generation of information.

Animals↗
PubMed1989

Airborne mineral fibre concentrations in an urban area near an asbestos-cement plant.

Ambient air concentrations of asbestos and total mineral fibres were measured during the period June-July 1985 at several locations near a large asbestos-cement factory located in the proximity of a northern Italian town. Measurements of the number and type of fibres were made by means of analytical scanning electron microscopy and energy-dispersive X-ray analysis (SEM-EDXA), essentially according to the RTM2 reference method of the Asbestos International Association. Total mineral fibre concentrations (longer than 5 microns) ranged from below detection limit (D.L., i.e. 0.4 fibres per litre (f/1] to 227 f/1 (single value); mean values ranged from 1.3 to 74.0 f/1. However, elemental microanalysis (EDXA) showed that about 65% of fibres were sulfate fibres, 20% were aluminium silicates or other silicates, and only 15% were asbestos fibres (mainly chrysotile and tremolite-group amphiboles). Asbestos concentrations (fibres more than 5 microns in length) were in the range of less than D.L. to 19.1 f/1, mean values ranging from less than D.L. to 11.1 f/1. The results obtained showed large differences in day-to-day concentrations, suggesting that they were affected by the rate of production in the plant and by weather conditions. In particular, wind direction and distance from the source appeared to be of major importance since the highest asbestos fibre concentrations were mostly found at points closer to the source and downwind. When the distance from the source was increased, other local factors appeared to be determining. In addition, the large proportion of non-asbestos mineral fibres and elongated sulfate (or sulfur-containing) particles clearly indicates major contributions from other sources, such as local pollution and natural soil erosion.

Air Pollutants↗