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Biomedical subjects

P Scarpelli

Publications and source records attributed to P Scarpelli.

6 recordsLinked to original sources
PubMed2004

Possible involvement of oxidative stress in exercise-mediated platelet activation.

In this study, we have attempted to verify whether a single bout of strenuous exercise performed by sedentary healthy individuals may interfere with the mechanisms controlling platelet sensitivity through exercise-related modifications of plasma oxidant/antioxidant equilibrium. Strenuous exercise resulted in an increased ADP- and collagen-evoked platelet aggregation associated with modified membrane fluidity and ion homeostasis. We also observed an enhanced plasma accumulation of secondary products of lipid peroxidation together with an increased susceptibility of low density lipoprotein (LDL) to in vitro oxidation and a decreased total plasma antioxidant potential. Notably, an acute elevation of nitrite/nitrate (NOx) amount was detected in plasma, whilst a decreased NOx content was measured in platelets. Findings of the current study suggest that oxidative stress induced by acute strenuous exertion may interfere with platelet responsiveness by promoting ox-LDL-mediated platelet activation and by decreasing platelet-derived nitric oxide bioactivity.

Adenosine Diphosphate↗
PubMed2003

Possible involvement of plasma antioxidant defences in training-associated decrease of platelet responsiveness in humans.

The aim of this study was to evaluate in sedentary individuals the effects of a 20-week exercise training program on ex vivo platelet responsiveness and the possible involvement of plasma antioxidant defences in relation to the mechanisms controlling platelet sensitivity. A statistically significant decrease in ADP- and collagen-evoked platelet aggregation was observed after physical training together with an increase in plasma total antioxidant capacity (TEAC), superoxide dismutase activity, and high-density lipoprotein cholesterol (HDL-C) concentration. Additionally, a rise in lag time for in vitro low-density lipoprotein (LDL) oxidation as well as a decreased plasma level of secondary products of lipid peroxidation were observed after training, and the values for lag time were significantly correlated with TEAC and HDL-C. Nitrate/nitrite (NOx) content both in plasma and in platelet cytosol was significantly enhanced at the end of the training period and a significant positive correlation was found between plasma and intraplatelet NOx values. Furthermore, intraplatelet NOx content was positively correlated with HDL-C levels. The findings of the current study suggest that the improvement of antioxidant defences induced by moderate regular exercise may be involved in desensitising blood platelets most likely through the inhibition of LDL oxidation and the simultaneous enhancement of plasma and intraplatelet NOx bioavailability and HDL-C level.

Adaptation, Physiological↗
PubMed1993

Rapid determination of erythrocyte pyruvate kinase activity.

We report a new potentiometric method for determining pyruvate kinase (PK). Enzymatic activity is measured by monitoring the change in pH produced in the reaction buffer under International Committee for Standardization in Haematology (ICSH) standardized assay conditions, and the lactate dehydrogenase reaction is automatically subtracted in each measuring cycle. The analysis, performed at 37 degrees C, requires a 10-microL sample (isolated erythrocytes or whole blood) and is completed in 2.5 min. The intra-assay CV is < 4% (PK between 3 and 35 U/g Hb); the interassay CV is 4.0% (PK 15 U/g Hb); results are linear from 3 to 30 U/g Hb. A good correlation with the ICSH reference method (x) was found: y = 1.011x - 0.05; n = 32; r = 0.9939; Sylx = 0.75 (units: U/g Hb). The reference intervals of the PK activity in isolated erythrocytes (RBC-PK) were estimated in 89 normal subjects. We found that women possess a higher RBC-PK than do men (P < 0.0001) and that the biological variability (CVb) of RBC-PK is 13.5%. Applications of the proposed method to the hematological routine are reported.

Adolescent↗
PubMed1987

Circadian variability of blood pressure and heart rate in newborns and cardiovascular chronorisk.

At present, neonates are being given screening tests for relatively rare diseases, such as phenylketonuria. The time has come to give emphasis to assessing the risk for major handicapping diseases, such as coronary heart disease, stroke, and certain diseases of the kidney. Modern technology for blood pressure and heart rate monitoring and data analysis provides noninvasive means to determine when preventive measures are indicated.

Blood Pressure↗
PubMed1980

Functional renal alterations in chronic liver diseases.

83 patients with chronic active hepatitis (CAH), 38 of them with cirrhosis, were studied and compared with 10 control subjects suffering from chronic persistent hepatitis (CPH). Tubular acidosis frequently was found in our cases. Renal plasma flow and glomerular filtration rate were significantly decreased in CAH when compared with CPH. Selective renal arteriography showed evident decrease of arterial flow in the outer cortex. Selective renal scan with 99mTc microspheres of human albumin showed a frequent escape of the tracer from the kidney to the lung. PGE1 and PGE2 levels appeared higher in the renal artery than in the vein and were significantly more elevated in 9 cases with cirrhosis vs. 13 controls. These results suggest the frequent functional impairment of the kidney also in the early stages of CAH, with an increase of PGE levels and an opening of intrarenal shunts.

Acidosis, Renal Tubular↗