PubMed Health⌕ Search

Biomedical subjects

M Valentino

Publications and source records attributed to M Valentino.

At least 19 recordsLinked to original sources
PubMed1991

Effects of lead on polymorphonuclear leukocyte (PMN) functions in occupationally exposed workers.

Previous in vitro experiments have shown that lead can inhibit PMN chemotaxis, phagocytosis and superoxide formation. Moreover, we have observed an inhibition of PMN chemotaxis in workers occupationally exposed to lead with a mean blood lead concentration of 3.06 mumol/l. The present study was carried out to evaluate locomotion and luminol assisted chemiluminescence (CL) of polymorphonuclear leukocytes (PMN) harvested from ten lead occupationally exposed workers with blood lead concentrations of 1.59 mumol/l (SD 0.27 mumol/l). Since lipids affect PMN activity and lipid composition is modified in erythrocytes of lead workers, PMN lipids were also studied. Ten healthy male subjects of the same age were taken as controls. Chemotaxis, i.e. locomotion stimulated through a specific membrane receptor, was impaired in the PMN of lead workers, but random migration, i.e. unstimulated cell locomotion, and respiratory burst were both unmodified. Cholesterol and phospholipids were not changed, but the percentage of arachidonic acid was significantly increased. The release of LTB4, generated by the oxidative metabolism of arachidonic acid, was increased. CL, which detects reactive oxygen species (ROS), was unmodified, but this lack of change could be the result of an increase in ROS, due to the augmentated percentage of arachidonic acid, and of a decrease in ROS, due to a direct inhibitory effect of lead on ROS generation. On the basis of the results from these ex vivo experiments, the conclusion that chemotaxis is the PMN function primarily affected by lead was confirmed. PMN are considered to be one of the first cellular targets for the action of lead; low exposure to lead modifies their activity and mainly modifies chemotaxis and LTB4 production.

Adult↗
PubMed1991

Comparison of questionnaire and biochemical markers to detect alcohol abuse in a West Indian population.

This study bears upon the respective validity of biochemical markers and questionnaires to detect alcohol abuse in a population with a high rate of alcohol-linked neurological complications. GammaGT and apoprotein AII were the most powerful of eight studied biochemical markers in detecting two-thirds of excessive drinkers. The CAGE questionnaire identified 74% of moderate drinkers and 94% of excessive drinkers with a life style and patterns of alcohol consumption different from previously tested target populations. The joint association of the CAGE questionnaire and apoprotein AII detected more than 9 out of 10 moderate or excessive drinkers defined on the basis of a quantity-frequency grid.

Adult↗
PubMed1990

[Decrease of blood lead in the Marche population, 1979-1989].

Blood lead concentration was measured from 1979 to 1989 in 1148 subjects (834 males and 314 females) living in Regione Marche of Italy. Blood concentration lowered in the time from 34.6 mcg/100ml in 1979 to 12.3 mcg/100ml in 1989. The greatest decrease was measured after 1982 and this appears to be related to the reduction, on the basis of CEE dispositions, of lead concentration in gasoline. Blood lead concentration was higher in males than in females (18.2 mcg/100ml vs 16.5 mcg/100ml) and in people living in the cities with more than 50.000 inhabitants (18.3 mcg/100ml). The smoking habit, the wine assumption and the use of canned foods do not influence blood lead concentration, which is instead increased in subjects which usually drink water drawn from artesian wells.

Adolescent↗
PubMed1989

Changes in membrane properties of erythrocytes and polymorphonuclear cells in psoriasis.

Using fluorescence polarization of 1,6-diphenyl-1,3,5-hexatriene and its cationic derivative, 1-(4-trimethylaminophenyl)-6-phenyl-1,3,5-hexatriene, we evaluated membrane fluidity in living polymorphonuclear leukocytes and in erythrocytes of psoriatic patients. Our results have shown that erythrocyte membranes of psoriatic patients exhibit a decrease of fluidity. These changes were not associated with any relevant modifications of the cholesterol to phospholipid molar ratio. Moreover, we observed a decrease in polymorphonuclear leukocytes membrane fluidity associated with changes in chemotactic migration. Our results indicate changes of membrane fluidity involving membranes different from the epidermal cells and suggest the hypothesis of a defective membrane-cytoskeleton interaction in psoriasis.

Adolescent↗
PubMed1989

[Increase in chemiluminescence induced by receptor-independent stimulation of polymorphonuclear cells from psoriatic patients].

Using a lucigenin-dependent chemiluminescence the authors have measured the "respiratory burst" in polymorphonuclear cells from psoriatic patients and controls. Measurements were performed under stimulation with zymosan, phorbol 12-myristate 13-acetate and latex beads. It has been revealed that the response after stimulation with zymosan increased although there was no significant difference between patients and controls, while the response after stimulation with phorbol 12-myristate 13-acetate and latex beads was significantly increased. Our results suggest an enhanced metabolic activity of polymorphonuclear cells induced by stimuli acting independently from cell-membrane receptors. Therefore an enhanced excitability of polymorphonuclear leukocytes of psoriatic patients is supposed.

Adult↗
PubMed1988

Increased membrane heterogeneity in stimulated human granulocytes.

TMA-DPH fluorescence decay in human PMN before and after stimulation with FMLP was studied using frequency domain fluorometry. Membrane heterogeneity was assessed by the width of the continuous distributions of lifetime values of Lorentzian shape used to describe the fluorescence decay. In non-stimulated granulocytes TMA-DPH fluorescence decay is characterized by two distributions of lifetime values centered at 6.5 and 1.0 ns and full width at half maximum of 0.3 and 1.2 ns, respectively. Within 15 min after stimulation, the center values of the two distribution components were 5.1 and 0.8 ns and the distribution width was 0.8 and 0.6 ns, respectively. These results indicate changes of membrane domain organization which can be ascribed to compositional changes and redistribution of membrane components.

Cell Membrane↗
PubMed1988

Impairment of chemotaxis of polymorphonuclear leukocytes from lead acid battery workers.

Since lead impairs in vitro the functions of macrophagic cells, we have studied the chemotactic activity of polymorphonuclear leukocytes (PMNs) obtained from lead acid battery workers who were removed from exposure one month before, because they had an abnormal lead absorption. Controls were 18 age matched subjects without any history of occupational lead exposure. Both lead acid battery workers and controls had no alterations of the blood haematological and metabolic parameters. Chemotaxis was carried on in Boyden chambers using zymosan activated serum as chemotactic stimulus. The chemotactic indexes are 56.4 +/- 8.7 in acid battery workers and 75.6 +/- in controls. The difference, which is statistically significant, shows that lead workers have an impairment of PMNs chemotactic activity.

Adult↗
PubMed1988

Fluorescence lifetime distributions of 1,6-diphenyl-1,3,5-hexatriene reveal the effect of cholesterol on the microheterogeneity of erythrocyte membrane.

The fluorescence decay of 1,6 diphenyl-1,3,5-hexatriene (DPH) has been used to characterize aspects of the erythrocyte membrane structure related to the microheterogeneity of the lipid bilayer. The DPH decay has been studied using frequency domain fluorometry and the data analyzed either by a model of discrete exponential components or a model that assumes a continuous distribution of lifetime values. The main intensity fraction was associated with a lifetime value centered at about 11 ns in the erythrocyte membrane, but a short component of very low fractional intensity had to be considered to obtain a good fit to the data. The lifetime value of the long component was insensitive to temperature, while the width of the distribution decreased with increasing temperature. In multilamellar liposomes prepared from phospholipids extracted from the erythrocytes, the long lifetime component showed a temperature dependence. The depletion of 27% of the cholesterol in the erythrocyte membrane induced a broadening of the distribution, suggesting a homogenizing effect of cholesterol. This effect has also been detected in egg phosphatidylcholine at a very low cholesterol/phospholipid molar ratio. The role of cholesterol on membrane heterogeneity is discussed in relation to the effect of cholesterol on water penetration.

Cell Fractionation↗
PubMed1988

Activation of the alternative complement pathway and generation of stimulating factors for granulocytes by glass fibers.

Continuous-filament glass fibers coated with organic agents, candidate asbestos substitutes, were assessed for their ability to elicit from normal human serum complement-derived cleavage products which are able to stimulate the chemotaxis and the respiratory burst of polymorphonuclear leukocytes. Glass fibers generated chemoattracting and respiratory stimulating factors for polymorphonuclears from human serum. The effect was dose related for chemotaxis from the serum fiber concentration of 75 micrograms/ml to 1,250 micrograms/ml. The serum chemoattracting activity, as well the respiratory stimulation, were dramatically impaired when serum had been preliminarily absorbed with antiC5 antiserum. Since the impairment of chemotactic activity occurred also in the presence of EDTA, but not in the presence of EGTA, we assumed an activation of the alternative complement pathway. Glass fibers were studied in comparison to a UICC sample of Canadian chrysotile asbestos, which is able to activate in vitro the alternative complement pathway. Glass fibers exhibited less ability than asbestos fibers to generate complement cleavage products with chemotactic activity for polymorphonuclears; however, they produced an activity about equal to 80% of a chemotactic standard stimulus such as zymosan-activated plasma.

Asbestos↗
PubMed1988

Increased neutrophil leukocyte chemotaxis induced by release of a serum factor in toluene-diisocyanate (TDI) asthma.

The activation of blood neutrophil leukocytes has been proven in subjects with IgE-mediated and non-IgE-mediated asthma. This event appears to be modulated by the release of humoral factors. We submitted 12 toluene-diisocyanate (TDI) asthmatic workers to TDI provocation. During the late asthmatic reaction there was release of a serum chemoattracting factor for normal neutrophil leukocytes and activation of asthmatic neutrophil leukocytes. This appears to be the first demonstration of neutrophil chemotactic activity liberated during the late TDI reaction in humans. The results are explained by an acute inflammatory process occurring during the late asthmatic reaction induced by TDI.

Adult↗
PubMed1987

Erythrocyte membrane heterogeneity studied using 1,6-diphenyl-1,3,5-hexatriene fluorescence lifetime distribution.

The fluorescence decay of 1,6-diphenyl-1,3,5-hexatriene has been used to characterize the structural organization of erythrocyte membranes. At 37 degrees C a large fraction of the decay (0.96) is associated with a lifetime value of 11.31 ns, while a minor fraction has a short lifetime of 2.63 ns. The distribution analysis approach has shown that the 11 ns component can be described using a Lorentzian distribution function having a full width at half maximum of 0.27 ns. The width of this component is associated with the membrane structural organization since liposomes from erythrocyte total lipid extract exhibit a narrower width. Moreover the distribution width is sensitive to different treatments of erythrocyte membrane.

Diphenylhexatriene↗
PubMed1987

Fluorescence lifetime distributions of 1,6-diphenyl-1,3,5-hexatriene in phospholipid vesicles.

The fluorescence emission properties of 1,6-diphenyl-1,3,5-hexatriene (DPH) in 1,2-dipalmitoyl-3-sn-phosphatidylcholine and 1,2-dimyristoyl-3-sn-phosphatidylcholine multilamellar vesicles have been measured by using multifrequency phase fluorometry. The fluorescence decay of DPH in the phospholipid vesicles has been analyzed by assuming either that the decay is made up of a discrete sum of exponential components or that the decay is made up of one or more continuous distributions of lifetime components. The fit of the decay curve using exponentials required at least two terms, and the reduced X2 was relatively large. The fit using a continuous distribution of lifetime values used two continuous components. Several symmetric distribution functions were used: uniform, Gaussian, and Lorentzian. The distribution function that best described the decay was the Lorentzian. The full width at half-maximum of the Lorentzian distribution was about 0.6 ns at temperatures below the phase transition temperature. At the phospholipid phase transition and at higher temperatures, the distribution became quite narrow, with a width of about 0.1 ns. It is proposed that the lifetime distribution is generated by a continuum of different environments of the DPH molecule characterized by different dielectric constants. Below the transition temperature in the gel phase, the dielectric constant gradient along the membrane normal determines the distribution of decay rates. Above the transition, in the liquid-crystalline phase, the translational and rotational mobility of the DPH molecule increases, and the DPH experiences an average environment during the excited-state lifetime. Consequently, the distribution becomes narrower.(ABSTRACT TRUNCATED AT 250 WORDS)

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1987

In vitro impairment of human granulocyte functions by lead.

Chemotaxis and receptor independent phagocytosis of human polymorphonuclear leukocytes (PMNs) exposed to lead in vitro (concentrations between 1.2 microM and 115 microM) were studied. Chemotaxis was measured in Boyden chambers and phagocytosis was investigated using latex beads. Additional methods were also applied. Superoxide anion formation from PMNs activated with preopsonized zymosan was quantified as superoxide dismutase-inhibitable reduction of ferricytochrome c. Steady state fluorescence polarization was performed using trimethylammonium diphenylexatriene (TMA-DPH). Lead concentrations were highly correlated both with decreased chemotactic activity (r = 0.70 p less than 0.01) and with decreased phagocytosis (r = 0.68 p less than 0.01). Ferricytochrome c reduction was not significantly affected. An increase in fluorescence polarization was recorded at the highest concentration of lead used, i.e. 57.6 microM and 115 microM, both in unstimulated PMNs and in PMNs activated with N-formyl-methionyl-leucyl-phenylalanine chemotactic peptide (n-FMLP). Moreover, an increase in the fluorescence polarization was observed in PMNs pretreated with a microtubule disrupting drug, exposed to lead concentrations of 14.4 microM and 57.6 microM and then activated with n-FMLP; no increase was recorded at the lowest lead concentrations used, i.e. 1.2 microM and 3.6 microM. The possible interaction of lead with the membrane-cytoskeleton apparatus is discussed.

Adult↗