Role of bisphenol A as environmental factor in the promotion of non-alcoholic fatty liver disease: in vitro and clinical study.

BACKGROUND: Bisphenol A is an endocrine disrupting chemical associated with type 2 diabetes mellitus (T2DM), cardiovascular disease and liver enzyme abnormalities. AIM: To evaluate bisphenol A plasma and urine levels in non-alcoholic fatty liver disease (NAFLD) patients compared to healthy subjects. Furthermore, we evaluated, in human HepG2 cells, the effects of exposure to different concentrations of bisphenol A on both oxidative stress induction and cell proliferation. METHODS: We enrolled 60 patients with histological diagnosis of NAFLD with or without T2DM and sixty healthy subjects. In vitro, the proliferation of bisphenol A-exposed HepG2 cells at two different concentrations (0.025 and 0.05 µM) was evaluated, both at high (H-HepG2) and at low (L-HepG2) glucose concentrations for 48 h. Lipoperoxidation was assessed by thiobarbituric acid reactive substances (TBARS) assay. RESULTS: Bisphenol A levels were significantly higher in 60 NAFLD subjects, both in urine and in plasma (P < 0.0001) when compared to controls and, in this group, it appeared to be higher in 30 non-alcoholic steatohepatitis patients compared to 30 simple steatosis subjects (P < 0.05), independently from the presence of T2DM. After a bisphenol A-free diet for 1 month, NAFLD patients showed a significant reduction in bisphenol A circulating levels (P < 0.05), without a significant reduction in urine levels. H-HepG2 cells treated with bisphenol A (0.05 µM) increased proliferation compared to controls at 48 h (P < 0.0001). Bisphenol A increased TBARS levels at 48 h versus controls. CONCLUSIONS: Our study reveals a possible role of bisphenol A as an environmental factor involved in the promotion of NAFLD, particularly in T2DM patients.

Effects of some endocrine disruptors on cell cycle progression and murine dendritic cell differentiation.

Endocrine disruptor chemicals (EDCs), which are predominantly present in the environment, are able to mimic or antagonise the biological activity of hormones primarily through the interaction with specific receptors. The main consequences are adverse effects on the growth and development of reproductive organs, the induction of cancer and effects on neuronal differentiation. In this study, we investigated the ability of certain EDCs, Bisphenol A (BPA), Bisphenol B (BPB), Bisphenol F (BPF), 4-n Nonylphenol (NP) and Octylphenol (OP), belonging to a homogeneous group of phenol origin, to interfere with specific cellular processes, namely, proliferation, by using MCF-7 breast carcinoma cells, and differentiation, by using murine bone marrow dendritic cells. We correlated the data on cell growth with the stimulation of cell cycle progression, which could become a step in the development of cancer, and we established a proliferation ranking between the tested EDCs: NP>BPA>OP>BPB>BPF. In addition, we investigated the ability of NP, BPA and OP to induce the differentiation of dendritic cells, the powerful antigen-presenting cells of the immune system. The differentiation and activation of these cells could affect a well-regulated immune response and determine an allergic sensitisation. We found that BPA and NP were active in determining differentiation.

Differential accumulation of BPA in some tissues of offspring of Balb-C mice exposed to different BPA doses.

Pregnant adult Balb-C mice were exposed daily to two different doses of Bisphenol A (BPA) by subcutaneous injection beginning on gestational day 1 through the seventh day after delivery. The mothers were sacrificed on postpartum day 21, and the offspring were sacrificed at 3 months of age. Control mice were subjected to the same experimental protocol but received saline injections. The liver, muscles, hindbrain and forebrain of the offspring were dissected and processed using HPLC to assess the level of BPA in the tissues and to determine its dependence on the exposure dose and gender. For comparison, the same tissues were dissected from the mothers and analysed. We report the following results: (1) the level of BPA that accumulated in a given tissue was dependent on the exposure dose; (2) the rank order of BPA accumulation in the various tissues was dependent on the gender of the offspring; (3) the average BPA concentrations in the liver and muscle of the female offspring were higher than in the males; and (4) the average BPA concentration in the central nervous system (i.e., the hindbrain and forebrain) of the male offspring was higher than in the females.

Differential accumulation levels in the brain of rats exposed to the endocrine disruptor 4-tert-octylphenol (OP).

Octylphenol (OP) is an endocrine-disrupting chemical that accumulates in various organs. It has also been shown to exert noxious effects on the central nervous system. In the present study, we measured in Sprague-Dawley rats the degree of OP accumulation in different areas of the brain and investigated the effect of OP in pain modulation. Two groups of male Sprague-Dawley rats were treated for 20 days with 50mg/kg BW/day of OP (group 1) or vehicle (group 2). At the end of the treatment, the formalin test was performed to evaluate the effect of OP exposure on pain. Soon after, rats were sacrificed, and the accumulation of OP in the cerebral cortex, hippocampus, hypothalamus, cerebellum, thalamus, striatum, mesencephalus and ventral hindbrain was measured by HPLC analysis. The results showed a greater accumulation of OP in the cerebral cortex compared to all the other areas; there was also more accumulation in the cerebellum compared to the mesencephalus and thalamus. No accumulation was found in the striatum. These results suggest that there is a preferential accumulation of OP in different areas of the brain with consequences to neural behaviour. On the contrary, experiments on facial grooming did not show significant effects of OP on pain.

Bisphenol A content in fish caught in two different sites of the Tyrrhenian Sea (Italy).

Bisphenol A (BPA) is an endocrine disruptor (ED) that is abundant in the environment because of its extensive use in human-manufactured products. In this study, the BPA concentration was measured in the muscle and liver of five edible fish, characterized by different habitat and habits, caught in two different sites of the Tyrrhenian Sea (Italy). Our results show that: (i) fish livers are about 2.5 times more polluted than muscle; (ii) fish caught in the Gulf of Naples are more polluted than those from the Latium coasts, ranging from 1.2-fold more for White Bream to 6.6-fold for Grey Mullet; and (iii) the percentages of fish found to be BPA-polluted in the Gulf of Naples ranged from 73% (for Bass) to 90% (for Mullet), while the Latium fish range from 60% (for Bass) to 90% (for Mullet). These data indicate that consumers of fish caught in the Gulf of Naples are at a greater risk for BPA-induced endocrine pathologies compared to those who consume fish caught along the Latium coasts.

A thionine-modified carbon paste amperometric biosensor for catechol and bisphenol A determination.

A thionine-modified carbon paste electrode for catechol and Bisphenol A (BPA) detection is presented. Graphite powder was modified by adsorbing thionine as electrochemical mediator. The electrochemical response of the modified carbon paste electrode (CPE) was determined before electrode modification with tyrosinase. Then, tyrosinase was added in order to assemble a biosensor. Once established the best operative conditions, an interelectrode reproducibility around 7% was obtained and the resulting biosensor showed improved sensitivities and (S=139.6+/-1.1 nA/microM for catechol and S=85.4+/-1.5 nA/microM for BPA) in comparison with the biosensor constructed without thionine (S=104.4+/-0.5 nA/microM for catechol and S=51.1+/-0.6 nA/microM for BPA) and low detection limits (0.15 microM for both the electrodes and analytes). Also the comparison with the results reported in the literature showed higher sensitivity and lower detection limit for our biosensor. Moreover the functioning of the thionine-tyrosinase CPE was validated following a biodegradation process of water polluted by BPA and comparing the time changes of BPA concentration inferred by the biosensor calibration curve and those determined by means of HPLC measurements.

Effect of bisphenol A with or without enzyme treatment on the proliferation and viability of MCF-7 cells.

Recently, aqueous solutions polluted by BPA have been bioremediated by us using laccase immobilized on hydrophobic membranes in non-isothermal bioreactors. BPA degradation was checked using analytical methods. To assess in vitro the occurred bioremediation, the proliferation and viability indexes of MCF-7 cells incubated in the presence of aqueous solutions of BPA, or of enzyme-treated BPA solutions, have been measured as a function of the initial BPA concentration. The results demonstrated that: i) at each initial BPA concentration used, both the proliferation and viability indexes are a function of the duration of enzyme treatment; ii) proliferation and viability are uncoupled biological processes with respect to BPA enzyme treatment. Non-isothermal bioreactors are a useful tool for the bioremediation of aqueous solutions polluted by BPA, which is an example of an endocrine disruptor that belongs to the alkyl phenol family.

Enzymatic determination of BPA by means of tyrosinase immobilized on different carbon carriers.

Different tyrosinase carbon paste modified electrodes to determine bisphenol A (BPA) concentration in aqueous solutions have been constructed. Variables examined were in the carbon paste composition and in particular: (i) the immobilized enzyme amount; (ii) the carbon type (powder, single or multi-walled nanotubes); (iii) the nature of the pasting oil (mineral oil, hexadecane and dodecane). For each biosensor type the amperometric response was evaluated with reference to the linear range and sensitivity. Constant reference has been made to the amperometric signals obtained, under the same experimental conditions, towards the catechol, a specific phenolic substrate for tyrosinase. The most efficient biosensors were those constructed by using the following composition for the carbon paste: 10% of tyrosinase, 45% of single wall carbon nanotubes (SWCN) and 45% of mineral oil. This biosensor formulation displayed the following electrochemical characteristics: a sensitivity equal to 138 microA/mM, LOD of 0.02 microM (based on three times the S/N ratio), linear range of 0.1-12 microM and response time of 6 min. This experimental work represents a first attempt at construction of a new carbon nanotube-tyrosinase based biosensor able to determine the concentration of BPA, one of the most ubiquitous and hazardous endocrine disruptors which can pollute the drinking and surface water, as well as many products of the food chain.

Nonisothermal reactors for the production of pure water from peritoneal dialysis waste waters.

The diffusion of peritoneal dialysis (PD) at home is somewhat restricted by the difficulty of transport and storage of a large amount of dialytic solutions. This problem is exacerbated in the case of hemodialysis. With the aim of producing pure water to be used in preparing the solution for peritoneal dialysis, or for hemodialysis in general, as one example, we purified the spent dialysate solution from PD. Experiments were carried out with 24 dialysate solutions taken from 8 patients. Pure water was obtained by means of a thermodialysis process in a hollow fiber reactor operating under nonisothermal conditions. Results show that the yield of the nonisothermal process is dependent on the temperature difference applied across the hydrophobic membranes. The production of pure water per square meter of membrane and per hour was equal to 0.55 or 1.2 or 2.0 liters, with a temperature difference of 11 degrees C or 21 degrees C or 28 degrees C, respectively. These results encourage the use of the thermodialysis process in the production of pure water for clinical uses.

Protease removal by means of antiproteases immobilized on supports as a potential tool for hemodialysis or extracorporeal blood circulation.

This work studies protease concentration decrease in aqueous solutions in contact with a modified polyethersulphone graft membrane onto which antiproteases were immobilized. As a model of protease/antiprotease interaction, elastase and alpha1-antitrypsin were used. Experiments were carried out either under fixed amounts of immobilized antiproteases and variable protease concentration or under fixed protease concentration and variable amounts of immobilized antiproteases. In both cases, active protease concentrations decreased with increase in contact time with the membrane. Experimental conditions under which active elastase concentration becomes zero were also found. Occurrence of the same phenomenology has also been ascertained with protease solutions obtained from human blood neutrophils. The membrane activated with alpha1-antitrypsin showed differential inhibitory power on elastase and cathepsin G. This technology could open new perspectives in manufacturing new membranes to be used in hemodialysis and extracorporeal circulation when elastase is released.

Enzyme reaction engineering: effect of methanol on the synthesis of antibiotics catalyzed by immobilized penicillin G acylase under isothermal and non-isothermal conditions.

The effect of methanol on the kinetically controlled synthesis of cephalexin by free and immobilized penicillin G acylase (PGA) was investigated. Catalytic and hydrophobic membranes were obtained by chemical grafting, activation, and PGA immobilization on hydrophobic nylon supports. Butyl methacrylate (BMA) was used as graft monomer. Increasing concentrations of methanol were found to cause a greater deleterious effect on the activity of free than on that of the immobilized enzyme. Methanol, however, improved the kinetic stability of cephalexin synthesized by free PGA, resulting in higher maximum yields. By contrast, immobilized PGA reached 100% yields even in the absence of the cosolvent. Cephalexin synthesis by the catalytic membrane was also performed in a non-isothermal bioreactor. Under these conditions, a 94% increase of the synthetic activity and complete conversion of the limiting substrate to cephalexin were obtained. The addition of methanol reduced the non-isothermal activity increase. The physical cause responsible for the non-isothermal behavior of the hydrophobic catalytic membrane was identified in the process of thermodialysis.

The alpha1-antitrypsin/elastase complex as an experimental model for hemodialysis in acute catabolic renal failure, extracorporeal blood circulation and cardiocirculatory bypass.

A modified polyethersulphone graft membrane was loaded with antiproteases, with the aim of reducing the active protease blood concentration during hemodialysis in acute catabolic renal failure or cardiopulmonary bypass. As protease/antiprotease system, elastase and alpha1-antitrypsin were used. The concentration of active elastase in aqueous solutions decreased as function of contact time with the membrane, approaching saturation. A 40% loss of elastase activity was obtained at pH 7.4, which was not due to autolysis, which accounted for 5% of the loss. The highest reduction was achieved at pH 9.0 (25% higher than at pH 7.4). The saturation level of elastase decrease, calculated by means of the Einstein equation, was reached after more than 47 minutes. We speculate that a time reduction might be achieved either increasing the concentration of immobilized antiproteases, or increasing the rate of elastase movement across the membranes by hydraulic, osmotic, or temperature gradients. This technology can be applied to hemodialysis, and in extracorporeal blood circulation to promote elastase release.