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Biomedical subjects

G Curatola

Publications and source records attributed to G Curatola.

At least 109 records · Page 6Linked to original sources
PubMed1982

Effect of lead on physical state of erythrocytes and model membranes.

Lead has an high affinity for erythrocyte and influences the membrane bound enzymes activities but its interactions with biological membranes is still unclear. We have investigated the effect of lead as free ion on physical state of erythrocytes and liposomes by Electron Spin Resonance (ESR) using two spin labels 5-doxyl-stearate (5-NS) and 16-doxyl-stearate (16-NS) and by DPH (1,6-diphenyl-1,3,5-hexatriene) fluorescence polarization analysis. Lead induces decrease of fluidity in natural membrane which is more evident in membrane hydrophobic core; the effect is not correlated with lead concentration. Lead ion interacts with negative charged liposomes inducing an increase of their microviscosity.

Cardiolipins↗
PubMed1982

The intrinsic fluorescence characteristics of sarcoplasmic reticulum membranes.

The fluorescence characteristics of tryptophan in sarcoplasmic reticulum, were investigated to gain information concerning its location and environment within the intact membrane system. With an excitation of 295 nm, tryptophan has an emission maximum of 330 nm characteristic of tryptophan in a buried hydrophobic environment. At the wavelength studied only a faint contribution of tyrosine is present. The changes observed in the presence of urea 8 M suggest only a partial exposition of the aromatic residues.

Animals↗
PubMed1982

Interactions between tryptophan and multilamellar liposomes. Effect of n-butanol on tryptophan fluorescence.

The fluorescence of indole ring of tryptophan is sensitive to the characteristics of the solvent in which it is located. So that is can be used as a probe of its microenvironment. In the present report we have studied fluorescence changes of tryptophan molecule located in multilamellar liposome of dipalmitoyl-lecithin (DPL). The temperature dependence of tryptophan fluorescence intensity shows increase related to the phase changes in DPL-liposomes. n-Butanol, a fluidizing agent, induces a linear dependence of tryptophan fluorescence from temperature.

1-Butanol↗
PubMed1982

Changes of membrane fluidity in erythrocytes of lead-exposed workers.

We have studied the effect of lead on the fluidity of erythrocyte membrane to clarify if lead can interact in vivo with biological membranes. Erythrocyte membranes were chosen in our study because a decrease of red cell osmotic fragility is also evident in the absence of laboratory and clinical signs of anaemia. The study was undertaken using the Electron Spin Resonance technique with two spin labels 5-doxyl stearate and 16-doxyl-stearate, which probe the physical state of the polar surface and the inner core of the membrane respectively. Red blood cells and erythrocyte ghosts were prepared from the blood of workers occupationally exposed to lead and from healthy controls. The determinations of Pb blood, Pb urine, urine coproporphyrin and delta-aminolevulinic acid showed an increased internal dose of lead, but the ordinary metabolic and haematological parameters were in the normal range. Our results show that in lead workers there is a change in chemical physical state both in erythrocytes and erythrocyte ghosts consistent with a decrease of membrane fluidity, which is evident in the surface as well as in the inner core of the membrane. The degree of membrane fluidity modification does not appear correlated with blood lead level. Changes in the membrane structural organization could be the molecular basis of some pathological alterations induced by lead.

Adult↗
PubMed1982

Effect of furosemide on renal size: ultrasonic characterization of renovascular hypertension.

In this pilot study, sequential ultrasonic scanning was used to assess (a) whether furosemide injection normally causes an enlargement of kidney size, and (b) whether this effect is blunted in renovascular hypertensives to such a degree as to bear potential diagnostic value. Furosemide caused similar degrees of maximal area enlargement in both kidneys of 10 healthy subjects (16.1 +/- 3.9%) and 10 essential hypertensives (14.8 +/- 4.2%) whereas in 11 renovascular patients maximal distension of the affected kidneys was significantly blunted (9.4 +/- 3.7%) in comparison with that of contralateral kidneys (19.6 +/- 7.7%). In the 6 hypertensives with one small kidney not due to renal artery stenosis, maximal enlargement of the affected kidneys averaged 22.8 +/- 5.1%, and that of contralateral kidneys 15.8 +/- 4.2%. In 8 out of the 11 patients with renovascular hypertension the difference in response between the paired kidneys had values outside the ranges of patients with both the other forms of arterial hypertension. The data suggest that the furosemide test may be of value in the screening for renovascular hypertension.

Adult↗
PubMed1982

[Adsorption of proteins by artificial mineral fibers: in vitro experiments].

Since previous studies reported that in vitro some proteins and phospholipids were absorbed by asbestos fibres, namely chrysotile, in this study, man made filamentous glass fibers are been tested in vitro at the presence of proteins. The objective was to obtain evidence to evaluate whether continuous glass fibers have a behaviour similar to asbestos fibres. A sample of chrysotile fibres was used as control. Uptake of bovine serum albumin and horse spleen ferritin on these continuous glass fibres has been observed. However on glass fibres adsorbed less proteins per weight unit (22 mg/g and 12 mg/g respectively for albumin and ferritin) than asbestos chrysotile fibres (42 mg/g and 49 mg/g respectively for albumin and ferritin).

Adsorption↗
PubMed1981

[Molecular organization of erythrocyte membranes in Duchenne muscular dystrophy].

Lipid-soluble spin labels were used to study lipid protein interactions in erythrocyte membranes obtained from patients with Duchenne muscular dystrophy. The temperature dependence of order parameter (Sn) and correlation time (tau c) have demonstrated alterations in the surface and in the hydrophobic core of membrane; the differences might be correlated with a depletion of extrinsic protein and of intramembrane particles. Our studies suggest a great abnormality of membrane molecular organization in Duchenne muscular dystrophy.

Electron Spin Resonance Spectroscopy↗
PubMed1980

[Study of lipid-protein interactions in mitochondrial membranes using the intrinsic fluorescence of tryptophan].

The environment of membrane-bound proteins has been investigated by measuring the fluorescence of intrinsic tryptophans in intact bovine heart mitochondria, in lipid-depleted mitochondria, and in reconstituted mitochondria. Lipid depletion induces a strong decrease of fluorescence intensity, probably as the result of extraction of peripheral proteins by the solvents used. Comparison of lipid-depleted and lipid-reconstituted mitochondria shows a higher fluorescence in the lipid-depleted membranes; in an Arrhenius plot the fluorescence intensity shows two breaks in the lipid-depleted membranes, but no break in the reconstituted ones. Butanol has little effect on fluorescence intensity of intact mitochondria. The results are compatible with a constant lipid environment of integral proteins which is not modified by either temperature or organic solvents.

Animals↗
PubMed1980

Fluidity of erythrocyte membranes from patients with Duchenne muscular dystrophy: studies in intact erythrocytes and in ghosts.

We have studied the alterations of fluidity in intact erythrocytes and in erythrocyte membranes from patients with Duchenne muscular dystrophy. The interest of this study was to comparison directly two types of results; these demonstrate an increase of fluidity in the erythrocytic membranes, no changes are present when the label is incorporated in intact erythrocytes. It might be inferred that hypotonic haemolysis removes components that are more weakly bound in Duchenne membranes, and that exert an immobilizing effect on the membrane lipids.

Adolescent↗
PubMed1980

Fluidity changes in rat liver plasma membranes during regeneration.

The fluidity of the liver plasma membrane during the first cell cycle of hepatectomized rats has been investigated by means of stearic acid spin labels and of the fluorescence polarization of perylene. The order parameters of 5-doxylstearate, that probes the membrane surface, have been found lowered in the hepatectomized rats after 15 hours from operation, in comparison with anesthetised and sham-operated controls at the same time; on the contrary, the fluidity in the membrane core, as probed by 16-doxylstearate, is increased in all groups. The fluorescence polarization of perylene is also lower in the hepatectomized rats. The results suggest that liver regeneration is accompanied by a fluidity increase of the plasma membrane.

Animals↗
PubMed1980

Effect of anesthesia on membrane fluidity and acetylcholinesterase activity in rat brain synaptosomes.

Anesthesia by means of ketamine induces an increase of fluidity in the hydrophobic area of rat brain synaptic membranes, as proved by the spin label 16-doxyl stearate, in contrast with no change induced in the order parameter of 5-doxylstearate that probes the membrane surface. These effects are qualitatively similar to those observed by ketamine addition in vitro. On the contrary, acetylcholinesterase from synaptic membranes, although inhibited in vitro by ketamine, is activated in ketamine-anesthetised rats suggested that metabolic changes are at the basis of the effects observed in vivo.

Acetylcholinesterase↗
PubMed1980

Plasma membrane changes associated with rat liver regeneration.

The lipid composition and fluidity of plasma membranes have been studied at different stages of liver regeneration (4, 15 and 24 h after surgery). The phospholipid and fatty acid composition is not modified, whereas the cholesterol/phospholipid ratio is lower with respect to control membranes. The modification of the physical properties of the membranes has been studied directly by EPR analysis and indirectly by temperature dependence and cooperativity of some membrane-bound enzymes (Mg2+-ATPase, (Na+ + K+)-ATPase and 5'nucleotidase). Surgical operation or anaesthesia alone causes an early increase in fluidity; such an effect appears to be markedly reduced at a later stage. There seems to be a marked effect of regeneration on plasma membrane fluidity 15 h after partial hepatectomy when several parameters--surface fluidity, cholesterol/phospholipid ratio, and 5'-nucleotidase activity in the presence of concanavalin A -- are modified and indicate an increase in membrane fluidity. It is suggested that this modification of membrane properties could be related to the proliferative process.

Adenosine Triphosphatases↗
PubMed1980

Effect of anesthetics on membrane fluidity tested by two different techniques: EPR spin labels and polarization of perylene fluorescence.

We have investigated the effect of n-butanol on the spectroscopic properties of two types of probes, that are usually employed to detect membrane fluidity, in mitochondrial phospholipid vesicles and mitochondrial membranes. Although both a spin label (16-doxylstearate) and the fluorescent probe perylene detect a higher immobilization of the membrane in comparison with phospholipid vesicles, the effect of butanol in the case of the membrane is strikingly different with the two techniques employed, showing increased fluidity in the case of the spin label and decreased fluidity with the fluorescent probe.

Anesthetics↗
PubMed1979

Progressive muscular dystrophy type Duchenne. I. Spin label studies on the physico-chemical state of erythrocyte membranes.

Electron spin resonance studies of erythrocyte membranes from patients with Duchenne muscular dystrophy exhibit changes in the physical state of lipids and proteins in membranes when compared to membranes from normal subjects. The results suggest that the alterations in membrane lipid-protein organization are present in this disease.

Electron Spin Resonance Spectroscopy↗
PubMed1979

Progressive muscular dystrophy type Duchenne. II. Viscosity and resistence to erythrolytic compounds of erythrocyte membranes.

The transition temperature of erythrocyte ghosts of normal subjects is about 18-20 degrees C. We have studied the viscosity of erythrocyte ghosts of dystrophic children, showing that the transition shifts to lower temperatures (17-18 degrees C). After treatment with erythrocytic compounds like L-Lyso phosphatidyl-Choline dystrophic erythrocytes hemolize at lower Lysophosphatidyl-Choline concentration and at a greater extents than these of normal and carriers subjects.

Erythrocyte Membrane↗
PubMed1979

Molecular mechanism of general anesthesia: II. Spin label studies on synaptic membranes.

In this communication we report the effects of general anesthetics on the mobility and order of spin labeled stearic acid derivatives in synaptic membranes and in bilayers formed from the lipids extracted therefrom. The anesthetics studied abolish the immobilization induced by synaptic membrane proteins on the membrane lipids : this effect, observed particularly in the bilayer core, is interpreted as a labilization of lipid-protein interactions induced by anesthetics.

Anesthesia, General↗
PubMed1979

Molecular mechanism of general anesthesia: I. Fluorescence studies in mitochondrial membranes.

We have tested the working hypothesis that anesthetics, by labilizing lipid-protein interactions, induce conformational changes in membrane proteins involved in the transmission of neural impulses. In the first communication of this series we report that general anesthetics induce changes in the fluorescence of the probes ANS and NPN in model membranes, lipid vesicles and mitochondria. The changes observed concern the quantumyield but not the position of the emission maximum. Such changes may be interpreted as due to fluidization of the membrane core (NPN), accompanied by variable effects in the membrane surface(ANS).

Anesthesia, General↗