Antonella Mattana

Plasma and platelet taurine are reduced in subjects with insulin-dependent diabetes mellitus: effects of taurine supplementation.

Plasma and platelet taurine concentrations were assayed in 39 patients with insulin-dependent diabetes mellitus (IDDM) and in 34 control subjects matched for age, sex, and both total and protein-derived daily energy intake. Platelet aggregation induced by arachidonic acid in vitro at baseline and after oral taurine supplementation (1.5 g/d) for 90 d was also studied. Plasma and platelet taurine concentrations (mean +/- SEM) were lower in diabetic patients (65.6 +/- 3.1 mumol/L, or 0.66 +/- 0.07 mol/g protein) than in control subjects (93.3 +/- 6.3 mumol/L, or 0.99 +/- 0.16 mol/g protein, P < 0.01). After oral supplementation, both plasma and platelet taurine concentrations increased significantly in the diabetic patients, reaching the mean values of healthy control subjects. The effective dose (mean +/- SEM) of arachidonic acid required for platelets to aggregate was significantly lower in diabetic patients than in control subjects (0.44 +/- 0.07 mmol compared with 0.77 +/- 0.02 mmol, P < 0.001, whereas after taurine supplementation it equaled the mean value for healthy control subjects (0.72 +/- 0.04 mmol). In in vitro experiments, taurine reduced platelet aggregation in diabetic patients in a dose-dependent manner, whereas 10 mmol taurine/L did not modify aggregation in healthy subjects.

Composition and in vitro antimicrobial activity of the essential oil of Thymus herba-barona Loisel growing wild in Sardinia

Abstract Two samples of the essential oils from Thymus herba-barona Loisel (Labiatae) of Sardinian origin were chemically characterized and their antimicrobial activity evaluated, in comparison with T. vulgaris and T. serpyllum oils, on the basis of their minimum inhibitory concentrations (M.I.C.s) and of the contact times required to totally inhibit development of microorganisms. GC and GC/MS analysis showed that the main components of essential oils of T. herba-barona were carvacrol (75.4% and 73–0%), borneol (3.6% and 6.4%) and p-cymene (3.9% and 3.3%), while the percentage of thymol was very low (1.0% and 0.7%). Results of the antimicrobial investigation demonstrated that both oils possessed similar and relevant microbicidal activities, especially against Gram+ bacteria (M.I.C.s range 0.125–0.500 mg/mL) and mycetes (M.I.C.s 0.125–0.500 mg/mL). At inhibitory concentrations, times required to kill microbial inocula (5–10 min) are comparable with those of chlorhexidine gluconate, an antiseptic with a broad range of antimicrobial activities. The strong activity of T. herba-barona oils is very probably due to the presence of carvacrol, which was found from our screenings to exhibit a similar antimicrobial activity. Our findings provide for a rationale basis of a possible utilization of this oil in fields requiring safe and cheap compounds with antiseptic and preservative properties, such as cosmetic, pharmaceutical and food industries.

In Vitro Evaluation of the Effectiveness of the Macrolide Rokitamycin and Chlorpromazine against Acanthamoeba castellanii

ABSTRACT The present study demonstrates the in vitro effectiveness of the macrolide rokitamycin and the phenothiazine compound chlorpromazine against Acanthamoeba castellanii. Growth curve evaluations revealed that both drugs inhibit trophozoite growth in dose- and time-dependent ways. The effects of both drugs when they were used at the MICs at which 100% of isolates are inhibited were amoebistatic, but at higher doses they were amoebicidal as well as cysticidal. Experiments showed that when rokitamycin was associated with chlorpromazine or amphotericin B, rokitamycin enhanced their activities. Furthermore, low doses of rokitamycin and chlorpromazine, alone or in combination, blocked the cytopathic effect of A. castellanii against WKD cells derived from the human cornea. These results may have important significance in the development of new anti-Acanthamoeba compounds.

ADP and Other Metabolites Released from Acanthamoeba castellanii Lead to Human Monocytic Cell Death through Apoptosis and Stimulate the Secretion of Proinflammatory Cytokines.

ABSTRACT Monocytes/macrophages are thought to be involved in Acanthamoeba infections. The aim of this work was to study whether soluble metabolites (ADP and other compounds) released by Acanthamoeba castellanii trophozoites could induce morphological and biochemical changes in human monocytic cells in vitro. We demonstrate here that ADP constitutively released in the medium by A. castellanii, interacting with specific P2y2 purinoceptors expressed on the monocytic cell membrane, caused a biphasic rise in [Ca2+]i, morphological changes characteristics of cells undergoing apoptosis, caspase-3 activation, and secretion of tumor necrosis factor alpha (TNF-α). The same results were found in monocytes exposed to purified ADP. Cell damage and TNF-α release induced by amoebic ADP were blocked by the P2y2 inhibitor suramin. Other metabolites contained in amoebic cell-free supernatants, with molecular masses of, respectively, >30 kDa and between 30 and 10 kDa, also caused morphological modifications and activation of intracellular caspase-3, characteristics of programmed cell death. Nevertheless, mechanisms by which these molecules trigger cell damage appeared to differ from that of ADP. In addition, other amoebic thermolable metabolites with molecular masses of <10 kDa caused the secretion of interleukin-1β. These findings suggest that pathogenic free-living A. castellanii by release of ADP and other metabolites lead to human monocytic cell death through apoptosis and stimulate the secretion of proinflammatory cytokines.

By Releasing ADP, Acanthamoeba castellanii Causes an Increase in the Cytosolic Free Calcium Concentration and Apoptosis in Wish Cells

ABSTRACT The role played by soluble molecules that may participate in acanthamoebal cytopathogenicity has yet to be fully characterized. We demonstrate here that Acanthamoeba castellanii trophozoites constitutively release ADP in the medium. Cell-free supernatants prepared from A. castellanii, by interaction with specific P2y2 purinoceptors expressed on the Wish cell membrane, caused a biphasic rise in [Ca2+]i, extensive cell membrane blebbing, cytoskeletal disorganization, and the breakdown of nuclei. Cell damage induced by amoebic supernatants was blocked by the P2y2 inhibitor Suramin. The same results were found in Wish cells exposed to purified ADP. These findings suggest that pathogenic free-living A. castellanii may have a cytopathic effect on human epithelial cells through ADP release, by a process that begins with a rise of cytosolic free-calcium concentration, and culminates in apoptosis.

Taurine Potentiates the Antiaggregatory Action of Aspirin and Indomethacin

In plasma, the physiological levels of taurine have been reported to be 0.05–0.22 mM depending on the species1 while platelet levels are a hundred times higher than the plasma2. These cellular fragments possess active transport sites2. However, the physiological significance of taurine in the platelets is still obscure although it has been shown that taurine stabilizes platelets against platelet activating factor (PAF) in guinea-pigs and ADP in man3,4

Deoxyadenosine metabolism in a human colon-carcinoma cell line (LoVo) in relation to its cytotoxic effect in combination with deoxycoformycin

We have assessed the intracellular metabolism of 2′‐deoxyadenosine in a human colon‐carcinoma cell line (LoVo), both in the absence and in the presence of deoxycoformycin, the powerful inhibitor of adenosine deaminase. The combination of 2′‐deoxyadenosine and deoxycoformycin has been reported to inhibit the growth of LoVo cells in culture. In this paper we demonstrate that the observed toxic effect is strictly dependent on cell density. In the absence of deoxycoformycin, 2′‐deoxyadenosine is primarily deaminated to 2′‐deoxyinosine and then converted into hypoxanthine. In the presence of the inhibitor, the deoxynucleoside, in addition to a phosphorylation process, undergoes phosphorolytic cleavage giving rise to adenine. The conversion of 2′‐deoxyadenosine to adenine might represent a protective device, emerging when the activity of adenosine deaminase is reduced or inhibited. There is much evidence to indicate that the enzyme catalyzing this process may be distinct from methylthioadenosine phosphorylase and S‐adenosyl homocysteine hydrolase, which are the enzymes reported to be responsible for the formation of adenine from 2′‐deoxyadenosine in mammals. Int. J. Cancer 75:713–720, 1998.© 1998 Wiley‐Liss, Inc.

TAURINE LEVELS IN PLASMA AND PLATELETS IN INSULIN-DEPENDENT AND NON-INSULIN-DEPENDENT DIABETES MELLITUS: CORRELATION WITH PLATELET AGGREGATION

In human volunteers it has been shown that taurine supplementation decreases collagen-induced thromboxane release and platelet aggregation (6). In addition, we found that, while in vitro taurine did not modify platelet aggregation per se, it potentiated the effect of anti-aggregating agents such as aspirin, papaverine, or sodium nitroprusside (13). These observations seem to indicate a possible role for taurine in the modulation of platelet function.

In vitro phagocytic interaction between Trichomonas vaginalis isolates and bacteria.

The phagocytic activity of 12Trichomonas vaginalis isolates against both gram-positive bacteria (Staphylococcus aureus ATCC 25923,Lactobacillus spp.) and gram-negative bacteria(Enterobacter cloacae ATCC 13047, 5 strains ofEscherichia coli, Pseudomonas aeruginosa ATCC 27853) was studied. Results showed that all the isolates were able to ingestStaphylococcus aureus to a variable degree, and almost all of them showed phagocytic activity againstPseudomonas aeruginosa. Furthermore, experiments with a restricted number of isolates ofTrichomonas vaginalis showed that they phagocytized, often very effectively, human vaginal lactobacilli. Only in some cases was the addition of serum essential for bacteria ingestion. Phagocytic uptake ofEscherichia coli andEnterobacter cloacae was not detectable under the experimental conditions used. It is concluded that phagocytosis may be involved in changes in vaginal biocenosis during the early stages of trichomoniasis.

Acanthamoeba castellanii (Genotype T4) Stimulates the Production of Interleukin-10 as well as Pro-inflammatory Cytokines in THP-1 Cells, Human Peripheral Blood Mononuclear Cells and Human Monocyte-Derived Macrophages

ABSTRACT Free-living amoebae of the genus Acanthamoeba can cause severe and chronic infections in humans, mainly localized in immune privileged sites, such as the brain and the eye. Monocytes/macrophages are thought to be involved in Acanthamoeba infections, but little is known about how these facultative parasites influence their functions. The aim of this work was to investigate the effects of Acanthamoeba on human monocytes/macrophages during the early phase of infection. Here, THP-1 cells, primary human monocytes isolated from peripheral blood, and human monocyte-derived macrophages were either coincubated with trophozoites of a clinical isolate of Acanthamoeba (genotype T4) or stimulated with amoeba-derived cell-free conditioned medium. Production of proinflammatory cytokines (tumor necrosis factor alpha [TNF-α], interleukin-6 [IL-6], and IL-12), anti-inflammatory cytokine (IL-10), and chemokine (IL-8) was evaluated at specific hours poststimulation (ranging from 1.5 h to 23 h). We showed that both Acanthamoeba trophozoites and soluble amoebic products induce an early anti-inflammatory monocyte-macrophage phenotype, characterized by significant production of IL-10; furthermore, challenge with either trophozoites or their soluble metabolites stimulate both proinflammatory cytokines and chemokine production, suggesting that this protozoan infection results from the early induction of coexisting, opposed immune responses. Results reported in this paper confirm that the production of proinflammatory cytokines and chemokines by monocytes and macrophages can play a role in the development of the inflammatory response during Acanthamoeba infections. Furthermore, we demonstrate for the first time that Acanthamoeba stimulates IL-10 production in human innate immune cells, which might both promote the immune evasion of Acanthamoeba and limit the induced inflammatory response.