Sabrina Lussignoli

Defective platelet response to arachidonic acid and thromboxane A2 in subjects with PlA2 polymorphism of β3 subunit (glycoprotein IIIa)

The membrane complex αIIbβ3 is the major receptor for fibrinogen and is involved in platelet adhesion and aggregation. Evidence has been presented that the PlA2 allele of the β3 PlA1/A2 gene polymorphism might be an independent risk factor for coronary thrombosis, but the matter is still controversial. We investigated the relationship between this polymorphism and possible alterations of platelet functions in vitro. The platelet adhesion to fibrinogen‐coated microplate wells and the aggregation induced by several different agonists were tested in 63 healthy volunteers, among them, 49 subjects with PlA1/A1 polymorphism, 12 subjects with PlA1/A2 polymorphism and two subjects with PlA2/A2 polymorphism. Subjects with PlA1/A2 polymorphism or with PlA2/A2 polymorphism showed significantly lower platelet responses as compared with PlA1/A1 subjects when either arachidonic acid or the thromboxane A2 analogue, U46619, were used as agonists. In resting condition and after thrombin or ADP stimulation, platelet function was normal in all the subjects. An increased sensitivity to the anti‐aggregatory effect of acetylsalicylic acid was observed in platelets from subjects with the PlA2 allele. Finally, using a flow‐cytometric evaluation and determining the β‐thromboglobulin plasma levels, we did not find any evidence of a PlA2 platelet hyper‐reactivity ex vivo. Our findings are not consistent with the hypothesis that the purported increase of cardiovascular risk in these subjects may be as a result of platelet hyperactivation. On the contrary, the PlA2 allele is associated with a platelet functional deficiency, specifically linked to the activation of the fibrinogen receptor by thromboxane A2.

The similia principle From cellular models to regulation of homeostasis

We have developed two models of the similarity principle, essentially based on the regulatory mechanisms of biological homeostasis. A first model (gating theory) is designed to explain a series of experimental findings obtained in our laboratory, pointing to the occurrence of inverse effects of various agents on human neutrophils in vitro. A second, more general, model (regulation of stressed homeostatic networks) is designed to integrate modern concepts of priming, desensitization and signal transduction into the classical homoeopathic theory of inversion of effect at the clinical level, i.e. the symptom-based similia principle. KEYWOROS: Similia principle; Homeostasis; Leukocytes; Receptors; Transduction systems; Gating theory; Stress; Inverse effects; Hormesis.

Study on Paradoxical Effects of NSAIDs on Platelet Activation

We recently described a stimulatory effect of high doses (>100 μmol/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 aggreation. 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 μmol/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 μmol/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 μmol/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 × 108 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 ACTIVITY OF POLYPHOSPHAZENE-BASED NAPROXEN SLOW RELEASE SYSTEMS

A biocompatible and biodegradable polyphosphazene bearing phenylalanine ethyl ester, imidazole and chlorine (10.7:1:2.5 molar ratio) as substituents of the phosphorus atoms of the polymer backbone was studied for the preparation of polymeric naproxen slow‐release systems.

Effects of Podophyllum peltatum compounds in various preparations and dilutions on human neutrophil functions in vitro

Abstract Human blood neutrophil granulocytes (neutrophils) treated with Podophyllum peltatum L.-derived compounds exhibited an enhanced oxidative response to subsequent challenge with bacterial formyl peptides. This priming effect was concerned with superoxide anion (O2−) release (respiratory burst). The phenomenon was observed with a potentized preparation containing, among other things, podophyllum extract (Podophyllum compositum), with Podophyllum 4x (final concentration of active principle about 0.025 μg/ml), whereas enhancement of O2− release was not caused by homoeopathic Podophyllum 12x or other components of the complex homoeopathic preparation. Purified podophyllotoxin had the same effect at doses of 0.1–10 μg/ml, whereas doses higher than 100 μg/ml of podophyllotoxin inhibited the respiratory burst, so that pure toxin showed a typical bi-phasic dose-response curve. Similar effects were obtained with purified colchicine (1–1000 μg/ml), a microtubule-disrupting agent. No priming by a Podophyllum-derived compound was observed on neutrophils stimulated with 50 ng/ml phorbol ester. Further, both potentized podophyllum-derived compounds and pure podophyllotoxin-inhibited cellular adhesion to the serum-coated surface of culture microplates. These results show that low potencies of a drug extract have specific stimulating effects on the activation of neutrophil metabolism. The same stimulating effects are also caused by low doses of the active principle of the drug, which is an inhibitor when used at high doses.

Dose-Dependence of the Various Functional Responses of Neutrophils to Formylpeptides

The up- and down-regulation of the response to a specific stimulatory compound, according to its doses and to the sensitivity of the cells, is a widespread process in biology, immunology and endocrinology. Leukocytes are particularly suitable models for studying these changes of biological response as these cells may be easily isolated from blood and from inflammatory exudates and appear to be regulated by a large variety of mediators both in vitro and in vivo (disease states).

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.

A computer model of the ‘five elements’ theory of traditional Chinese medicine

Summary In this article, a model is presented of a network whose structure was inspired by the ‘five elements law’ of Chinese medicine. Computer simulations illustrate the dynamic behavior of this system, that can be set in different attractors of Boolean type and can be differentially modified by delays and perturbations. We suggest that this model may contribute to the understanding of the ‘logic’ of the regulation of biological systems by means of small and carefully selected perturbations, a major line of thought of complementary therapies.