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Biomedical subjects

P Bellavite

Publications and source records attributed to P Bellavite.

At least 19 recordsLinked to original sources
PubMed2000

Influence of an acute exercise on neutrophil and platelet adhesion, nitric oxide plasma metabolites in inactive and active subjects.

In this work we studied the influence of an acute exercise either on nitrite/nitrate plasma levels or on neutrophil and platelet adhesion in inactive and active subjects. Twelve healthy subjects (6 inactives and 6 actives) exercised on a racing cycle ergometer performing stepwise increases in intensity until reaching, within 5 min, a heart rate of 150 beats x min(-1) which represents an oxygen consumption of about 75 % of the individual maximum rate of oxygen uptake. From peripheral venous blood samples (drawn from all subjects before, immediately after the end of exercise, and 1 hour later) neutrophils and platelets were isolated to test plate adhesion, and nitrite/nitrate concentrations were measured in the plasma. Immediately after the acute exercise, in active subjects we observed a significant decrease in the percentage of neutrophil adhesion (7.96+/-2.38 vs. 14.10+/-3.14), associated with an increase in nitrite/nitrate plasma levels (81.38+/-10.76 vs. 41.08+/-8.13 micromol x l(-1)), restored by a 40 min pre-incubation with NG-nitro-L-arginine methyl ester (L-NAME). In unstimulated platelets we observed a significant lower percentage of platelet adhesion in active subjects compared to inactives after exercise. With thrombin or adenosine 5'-diphosphate as agonists platelet adhesion did not result significantly different in active subjects compared to inactives. In conclusion, our data show that physical exercise can induce changes in some cell activities, even if transient, and favour the generation of nitric oxide. The lower adhesion of neutrophils and platelets induced by regular exercise could be an important goal in the prevention of vascular and inflammatory diseases.

Adult↗
PubMed1999

A microplate-based colorimetric assay of the total peroxyl radical trapping capability of human plasma.

We developed a colorimetric assay estimating the radical-scavenging activity of human plasma. The test is based on a measure, in 96-well microplates at 450 nm, of the bleaching of carotenoid crocin by peroxyl radicals generated during thermal decomposition of 2, 2'-azobis-(2-amidinopopane) dihydrochloride (ABAP). The inhibition of this bleaching is a function of the antioxidant power of substances added to incubation mixture. We determined the optimal conditions for a sensitive, rapid, and reproducible assay of 50% inhibitory capacity (IC50) of a range of antioxidant substances and of plasma. Only a total of 200 microl of plasma is required in a complete dose-inhibition curve. The IC50 of normal human plasma resulted of 2.70 microl of plasma/250 microl assay volume. The total antioxidant capability (TAC) of plasma was defined as the reciprocal of IC50 and its value in a group of 19 healthy adults resulted in 0. 369 +/- 0.06. Intraassay and interassay coefficients of variation of plasma TAC were 6.13 and 4.80%, respectively. Measurement of samples with different uric acid concentration showed that antioxidant activity of uric acid accounts for approximately two-thirds of TAC.

Adult↗
PubMed1999

Effect of Traumeel S, a homeopathic formulation, on blood-induced inflammation in rats.

OBJECTIVE: To evaluate the activity of Traumeel S (TRS), a homeopathic formulation containing Arnica montana and other plant extracts and minerals on an animal model of traumatic inflammation. DESIGN: TRS and individual components thereof were administered locally to rats 1 h before hind-paw injection with 0.1 ml of homologous blood and the development of oedema was measured over five hours. In each experiment, a control group was treated with saline. MAIN OUTCOME MEASURES: Paw volume of each rat was measured before oedema and 1, 3, and 5 h after oedema induction. Serum levels of IL-6 were determined at hour 5. RESULTS: The decrease of paw oedema, associated with the process of healing, was more rapid in rats treated with TRS (P < 0.05 after 3 h and P < 0.01 after 5 h). Similar effects were also induced by separate injection of most, but not all, TRS ingredients. The efficacy of complete mixture of TRS was higher than the combination of a selection of active components. TRS also reduced oedema development when administered after the oedema induction. The therapeutic effect of TRS was associated with a significant decrease of systemic interleukin-6 production. CONCLUSION: TRS seems to act by speeding up the healing process instead of blocking the development of oedema from the beginning. Moreover, its effect cannot be considered as the 'sum' of its active components and probably a synergistic interaction occurs to determine the final effect.

Animals↗
PubMed1999

Expression of FCepsilonII/CD23 on human neutrophils isolated from rheumatoid arthritis patients.

CD23, the low affinity receptor for IgE, is a 45 kilodalton molecule belonging to the C-type lectin family, some members of which have been identified as adhesion molecules. Since it has been described upregulated in different cells in chronic inflammatory diseases and in rheumatoid arthritis in particular, where neutrophils are directly involved in tissue damage, our interest, in this work, has been focused on the expression and regulation of this antigen on neutrophil membrane. We studied 22 patients suffering from rheumatoid arthritis and 22 healthy control subjects. CD23 expression on neutrophil membrane was analyzed by immunofluorescence. Neutrophils of 9 out of 22 patients expressed CD23 molecules, neutrophils of 11 out of 22 patients expressed CD23 only after 24 h of incubation in RPMI; only 2 out of 22 patients did not express the CD23 antigen on neutrophil membrane either after isolation or after a 24 h incubation. On the contrary neutrophils isolated from healthy subjects did not express CD23 molecules upon isolation. Only in 7/22 control subjects neutrophils resulted positive after 24 h of incubation in RPMI. Moreover, we found that in our experimental conditions the presence of IFN-g or GM-CSF alone or in combination with IL-4 inhibited CD23 expression during the 24 h incubation. Our results show that there is a strong association between neutrophil ability to express CD23 and rheumatoid arthritis, and that such expression may be regulated by GM-CSF, IFN-gamma and IL-4.

Adult↗
PubMed1999

Neutrophil migration, oxidative metabolism and adhesion in early onset periodontitis.

The aim of this study was to evaluate neutrophil function in patients suffering from the generalized form of early onset periodontitis (EOP). We investigated neutrophil migration in vivo and neutrophil superoxide production and adhesion in response to a variety of compounds; neutrophils were isolated both from blood and a skin experimental exudate of 15 patients with EOP and of 15 sex- and age-matched normal control subjects. No difference was found in neutrophil migration in vivo (71.2+/-16.4x10(6) and 68.8+/-10.7x10(6) PMN/cm2/24 h in patients affected by early onset periodontitis and normal subjects respectively) and in adhesion. The superoxide production in response to STZ and PMA was similar between the 2 groups, while superoxide production in response to fMLP was markedly lower in patients than in control subjects both in circulating neutrophils (5.6+/-2.2 versus 10.4+/-2.3 nmoles O2-/10(6) cells, p<0.0001) and in exudate neutrophils (16.3+/-4.3 versus 22.3+/-4.7 nmoles O2-/10(6) cells, p<0.005). In general, neutrophil function in patients suffering from early onset periodontitis does not differ from control subjects, suggesting that the overall defence function of these cells is normal. The only parameter that we have found to be different between the 2 groups is the low superoxide production after fMLP stimulation. The stimulus- and function-specificity of this defect in neutrophils from patients indicates the existence of a dysregulation of the signal transduction pathway distal to fMLP receptor and proximal to NADPH oxidase activation.

Adult↗
PubMed1999

Invasive aspergillosis in neutropenic patients: rapid neutrophil recovery is a risk factor for severe pulmonary complications.

BACKGROUND: In invasive aspergillosis, the duration of neutropenia is an accepted risk factor, and recovery from neutropenia is generally associated with a favourable outcome. However, the rapidity of granulocyte recovery may rarely be associated with adverse sequelae. The purpose of this study was to define the relationship between neutrophil (polymorphonuclear, PMN) recovery after chemotherapy-induced bone marrow aplasia and the occurrence of severe pulmonary complications (haemoptysis, pneumothorax and death) in patients with haematological malignancies who developed invasive fungal pneumonias. METHODS: Twenty consecutive patients were retrospectively studied; eight of them had developed pulmonary events between 5 and 11 days after neutrophil recovery that followed deep neutropenia (PMN < 100 microL-1). RESULTS: Five patients had haemoptysis (one of these also had pneumothorax) and three had pneumothorax. According to the multiplicative logistic model, the odds of occurrence of a pulmonary event increased significantly with increasing PMN count on the fifth day (P < 0.001). Five of the eight patients who had pulmonary complications died. Also, the risk of death was larger in the presence of rapid neutrophil recovery, although the difference was not statistically significant (P = 0.111). Analysis of clinical and laboratory data showed that the risk of pulmonary complications significantly increased when the neutrophil concentration was > 4500 microL-1 on day 5 after deep granulocyte neutropenia (PMN < 100 microL-1). There was no correlation between pulmonary complications, dosage of amphotericin B and deaths. CONCLUSION: The occurrence of life-threatening complications in patients with invasive fungal pneumonia is closely related to rapid PMN recovery.

Adolescent↗
PubMed1999

Homeopathic terminology: a consensus quest.

The aim of this project is to develop a common homeopathic terminology to improve communication. A questionnaire was sent by email to an international group of experts. As a result of an iterative process we propose that a number of terms which are inaccurate, unclear or have become outdated should be replaced by new terms. The main areas in which terminology should be updated are: concepts relating to: homeopathic pharmacology, research, homeopathic medicine, the principle of similarity, homeostasis and disease imitation, miasms, experimental homeopathy, provings and pathogenic trials.

Homeopathy↗
PubMed1999

Dual effects of a homeopathic mineral complex on carrageenan-induced oedema in rats.

Carrageenan oedema, a classical experimental model commonly used to test activity of anti-inflammatory drugs, was used to evaluate the therapeutic activity of a low-potency mineral complex (MC). The MC was administered in the right plantar surface of albino rats 60 min before, simultaneously and 30 min after injection of carrageenan, an irritant which causes a local, transitory increase of fluid volume. The administration of the MC 60 min before the injection of carrageenan primed the animal to enhanced inflammatory response to the irritant. The administration of MC contemporarily to carrageenan did not modify the kinetic and the extent of the oedema, while the administration of the MC 30 min after the induction of the oedema significantly reduced the early phase of the inflammatory reaction. This indicated that the therapeutic action of this MC is not due to conventional anti-inflammatory effect but to activation of endogenous regulatory mechanisms, a phenomenon which may be regarded as a simple application of the 'similia rule'.

Animals↗
PubMed1999

Differential effects of dietary supplementation with fish oil or soy lecithin on human platelet adhesion.

To investigate the possible regulating role of omega-6 and of omega-3 fatty acids on platelet adhesiveness, we randomised 60 volunteers into three groups to take 20 ml (equivalent to 0.3 g omega-6, 3.6 g omega-3; omega-6/omega-3 ratio 0.1) per day of a fish oil supplement, or to take 25 g (equivalent to 1.5 g omega-6, 0.5 g omega-3; omega-6/omega-3 ratio 3) per day of a soy lecithin supplement, or to continue on their usual diet without any supplement (control group) for a period of 15 days. Platelet adhesion on fibrinogen-coated 96-well microtitre plates was evaluated in the resting condition and after stimulation with 2 microM ADP or 0.02 U/ml thrombin. Compared to the values before the experimental period, the fish oil group showed a significant reduction in stimulated adhesion (with ADP: from 18.8% to 15.6%, p<0.01; with thrombin: from 24.4% to 20.8%, p<0.005), whereas no difference was noted in the resting condition (from 3.6% to 3.5%, NS). In the soy lecithin group, platelet adhesion was increased in all test conditions (with ADP: from 18.7% to 23.2%, p<0.001; with thrombin: from 24.0% to 29.9% p<0.001; resting: from 3.5% to 6.6%, p<0.001). No significant changes were observed in the control group. A good correlation was found between platelet adhesion data and the changes in the platelet fatty acid omega-6/omega-3 ratio caused by the different supplementations. Our results indicate an inhibitory effect of fish oil rich in omega-3 fatty acids on stimulated human platelet adhesiveness and a stimulatory effect of soy lecithin rich in omega-6 fatty acids on resting and stimulated adhesion. They suggest moreover that the omega-6/omega-3 ratio is a determinant of platelet adhesion.

Adenosine Diphosphate↗
PubMed1999

[Homeopathy in the perspective of scientific research].

A significant portion of the traditional concepts of homeopathy (similia principle, experimentation on healthy humans, the cure of whole person, the use of minimum doses or high dilution/potency of medicines) are amenable to investigations conducted according to criteria accepted by biomedical science. Even though many randomized and controlled clinical studies seem to demonstrate the efficacy of some homeopathic medicines and their superiority to placebo, other trials have given negative results. A definite clear answer is not yet possible due to the scarce quality of some published reports, to lack of reproduction by independent investigators and to the uncertainty regarding the methodologies to be used for testing the claims of homeopathy. As regards the possible physiopathological, biophysical and pharmacological explanations for the action of homeopathic remedies, there are models which tend to set the similia principle as a general expression of the action-reaction principle, within the context of dynamic systems theory. The clarification of the more controversial aspects regarding dilution/potency of medicines remains tied to several promising developments in physics of condensed matter, in chaos theory and in biophysics.

Biophysical Phenomena↗
PubMed1998

Neutrophil functions and IL-8 in psoriatic arthritis and in cutaneous psoriasis.

The aim of this study is to determine some functions of neutrophil in patients affected by psoriatic arthritis and to compare them to those of patients affected by cutaneous psoriasis and to normal controls. We used a model of experimental cutaneous inflammation allowing to separate a cluster of purified and viable PMN cells. Then we analyzed, within the three groups, the IL-8 concentration in serum and in the supernatant obtained from the inflammatory site to gather data on the possible pathogenic role played by this cytokine in psoriatic arthritis. We studied neutrophil functions in patients with cutaneous psoriasis and psoriatic arthritis, in acute phase, in comparison with healthy control subjects. We investigated in vivo neutrophil migration by Senn's skin window technique and measured adhesion assay and superoxide production in circulating and migrating neutrophils after different stimuli. We also measured IL-8 concentration in serum and in the supernatant obtained from the inflammatory site, artificially created through the skin window scrape. Neutrophil migration in vivo was significantly higher in both groups of patients than in controls. In the presence of fMLP, blood cells showed a burst of superoxide release, which was significantly more pronounced in patients when compared to healthy controls. Neutrophils from skin window scrape showed a much higher response to fMLP as compared to blood cells of all subject groups, but no differences were observed between patients and controls. No correlation was found between the three groups in adhesion ability under basal condition or in response to different stimuli by circulating and migrating neutrophils. Our results also show a great increase of IL-8 in the exudate from patients compared to controls. Our study shows that there is no difference in neutrophil functions between patients with psoriatic arthritis and cutaneous psoriasis; moreover we suggest that the source of high IL-8 levels are neutrophils rather than the keratinocytes.

Adult↗
PubMed1998

Effects of dietary fish oil and soy phosphatidylcholine on neutrophil fatty acid composition, superoxide release, and adhesion.

Fifty-seven healthy volunteers matched for sex and age were subdivided in 3 groups and their usual Western diets were supplemented according to three different protocols: group 1, fish oil supplement (20 ml/day); group 2, soybean phosphatidylcholine (PC) (25 g/day) and group 3, no supplementation (control group). After 2 weeks several important modifications of neutrophil fatty acid composition were observed: fish oil induced a significant decrease of linoleic (LA) and arachidonic acid (AA) and a significant increase of eicosapentaenoic (EPA) and docosahexaenoic acid (DHA), while soy PC induced significant increases of LA, total polyunsaturated fatty acid (PUFA) and PUFA/SFA ratio. Neutrophil superoxide generation and adhesion were not modified by fish oil diet, on the contrary a slight but significant increase of O2.- production in response to fMLP was measured after soy PC diet. Our study confirms the possibility of changing neutrophil fatty acid composition in vivo by dietary means, but also suggests that the manipulation of cell functions, like superoxide anion generation and adhesion, is not easily and directly achieved by controlling membrane lipid environment.

Adolescent↗
PubMed1998

Decrease of platelet intracellular pH and adhesion by ticlopidine in patients with vascular disease.

BACKGROUND: Ticlopidine inhibits platelet aggregation by preventing the binding of fibrinogen to its platelet receptor. We examined whether this inhibition involved platelet transduction system such as Na+/H+ pump and platelet intracellular calcium. METHODS: Platelet adhesion in 13 patients with peripheral vascular disease treated with ticlopidine, 250 mg b.i.d for 30 days, was measured in culture microplates before and after therapy. The microplate wells were coated with human plasma, fibrinogen or collagen, and platelet adhesion was studied in the resting condition and after stimulation with 1 and 10 microM ADP. At the same time, platelet intracellular calcium and ADP-induced calcium increases were measured with the fluorescent indicator Fura 2. In addition, intracellular pH and thrombin-induced pH variations were measured with the fluorescent probe BCECF. RESULTS: Platelet adhesion to plasma and fibrinogen was significantly reduced (about 50%) after treatment with ticlopidine, while adhesion to collagen was not modified. Basal calcium and ADP-induced calcium increase were not significantly different before and after ticlopidine. Platelet basal intracellular pH was reduced (from 7.44+/-0.009 to 7.41+/-0.017, p<0.05), but agonist-induced alkalinisation was not significantly different. Early acidification, not dependent on Na+/H+ exchange, was also reduced (p<0.05). CONCLUSIONS: These data do not seem to support the hypothesis that ticlopidine-induced reduction of platelet adhesion depends on alteration of the mechanisms determining signal transduction, at least as far as basal and post-stimulation intracellular calcium is concerned. On the contrary, the possibility that ticlopidine inhibits the Na+/H+ antiport remains open to consideration.

Aged↗
PubMed1997

Specific and long-lasting suppression of rat adjuvant arthritis by low-dose Mycobacterium butyricum.

We have tested the therapeutic effect of intraperitoneal injections of Mycobacterium butyricum on the development of adjuvant arthritis in rats and we have explored the specificity and the duration of effectivity of this treatment. Rats with induced arthritis were injected intraperitoneally with the causative antigen, Mycobacterium butyricum, at concentrations 10 times lower than the inducing one, on the 3rd and 10th day after arthritis induction. The severity of the disease was assessed on the basis of physical (arthritis index, paw swelling) and biochemical (serum interleukin-6) parameters. The treatment with Mycobacterium butyricum led to a significant suppression of adjuvant-induced arthritis. This therapeutic effect was both antigen-specific, because intraperitoneal aspecific inflammation did not prevent the disease, and long-lasting. The results obtained in this model confirm the possibility of modulating the autoimmune process even when the immunological response is already triggered, suggesting new therapeutic strategies, more suitable than preventive vaccination, in human autoimmune diseases.

Animals↗
PubMed1997

A scientific reappraisal of the 'principle of similarity'.

In the history of therapeutics, the 'principle of similarity'--the treatment of 'same by same' or of 'like by like'--may be traced back to a number of medical traditions, including the systems of Hippocrates, Paracelsus and Hahnemann. Although in recent years we have witnessed a renaissance of interest in traditional medicines and 'holistic' medical practices, the reliability of the principle of similarity has still to be demonstrated on experimental grounds, and very few studies have been conducted to understand the underlying mechanism(s). Acceptance of this phenomenon requires supporting evidence of possible mechanisms and high-quality studies exploring its effectiveness in clinical medicine. The aim of this work is to provide a rational approach to the analysis of the various aspects of this historical yet also modern medical principle, in order to construct a plausible framework of ideas capable of facilitating further basic and clinical research into this field.

Animals↗
PubMed1997

Study on paradoxical effects of NSAIDs on platelet activation.

We recently described a stimulatory effect of high doses (> 100 mumol/L) diclofenac on platelet adhesion. In this study we extend our research to the possible biochemical mechanisms of the observed effects, to other non steroidal anti-inflammatory drugs (NSAIDs) (flurbiprofen, indomethacin, acetylsalicylic acid, ibuprofen, nitrofenac and nitroflurbiprofen) and to the effect of high doses diclofenac and flurbiprofen on platelet aggregation. We observed that high doses of diclofenac and of flurbiprofen, but not of the other tested NSAIDs, increased platelet adhesion at doses ranging from 100 to 500 mumol/L, an effect completely removed by the 12-lipoxygenase-inhibitor nordihydroguaiaretic acid. Moreover, they had no pro-aggregating effect, inhibiting platelet aggregation induced by 10 mumol/L arachidonic acid and dose-dependently increasing the [Ca2+]i. Finally, whereas no basal nitric oxide release by washed platelets was detected, when platelets were incubated by 500 mumol/L diclofenac or flurbiprofen, the production of nitric oxide, as measured by amounts of nitrite released, was 4.4 +/- 0.5 and 3.8 +/- 0.4 pmol/5 x 10(8) platelets/min, respectively. Our data indicate that high doses diclofenac and flurbiprofen are promoters of the early phases of platelet activation, probably through the 12-lipoxygenase pathway.

Anti-Inflammatory Agents, Non-Steroidal↗