Brief exposure to triphenyltin produces irreversible inhibition of the cytotoxic function of human natural killer cells

In Vitro Assay Using Proboscidea parviflora W. and Phaseolus lunatus L. Plant Extracts to Control Pythium amazonianum

Avocado tree wilt is a disease caused by Phytophthora cinnamomi Rands. Recently, this disease has been associated to Pythium amazonianum, another causal agent. Avocado tree wilt is being currently controlled with synthetic fungicides that kill beneficial microorganisms, polluting the environment and leading to resistance problems in plant pathogens. The current research work aims to provide alternative management using extracts from Proboscidea parviflora W. and Phaseolus lunatus L. to control the development of mycelia in P. amazonianum in vitro. Raw extracts were prepared at UAAAN Toxicology Laboratory, determining the inhibition percentages, inhibition concentrations and inhibition lethal times. Several concentrations of the plant extracts were evaluated using the poisoned medium methodology, showing that both extracts control and inhibit mycelial development, in particular P. lutatus, which inhibits mycelial growth at concentrations lower than 80 mg/L, being lower than P. parviflora extracts. These extracts are promising candidates for excellent control of Pythium amazonianum.

Triphenyltin hydroxide induces changes in the oxidative stress parameters of fish

Among all organotin compounds , triphenyltin hydroxide (TPhTH) is widely used as fungicide and moluscicide in Brazil. However, the effects of TPhTH on the biochemical parameters of non-target organisms, such as fish, are little known. The aim of the present study is to assess the possible toxic effects of different concentrations of waterborne TPhTH on silver catfish belonging to species Rhamdia quelen. The fish were exposed to two different concentrations of TPhTH (1.08 and 1.70 µg/L as Sn) for 15 days and then compared to the control group (triplicate, n = 3). The antioxidant profile (catalase (CAT) and the glutathione S-transferase (GST)) and the oxidative stress parameters (TBARS-thiobarbituric acid-reactive substances and protein carbonyl (PC)) were set after the exposure to TPhTH. The TBARS level and the PC content increased in several organs of the Rhamdia quelen (brain, liver, muscle and gills) under the two concentrations of TPhTH in comparison to the control group. The CAT activity in the liver and gills has enhanced in all tested TPhTH concentrations. The GST activity increased in the brain, liver and muscle tissues under all the TPhTH concentrations. The significant changes in the biomarkers indicated that the investigated pesticide could have harmful effect on fish, in the field. However, these biomarkers were measured after the fish received doses lower than the recommended for use in agriculture.

Immunosuppressive effects of triclosan, nonylphenol, and DDT on human natural killer cells in vitro

Human natural killer (NK) cells are a first-line immune defense against tumor cells and virally-infected cells. If their function is impaired, it leaves an individual more susceptible to cancer development or viral infection. The ability of compounds that contaminate the environment to suppress the function of NK cells could contribute to the increased risk of cancer development. There are a wide spectrum of compounds that significantly contaminate water and food that are consumed by humans, leading to accumulation of some of these compounds in human tissues. In the current study, we examined the ability of three such compounds to diminish the function of human NK cells. Triclosan (TC) is an antimicrobial agent used in a large number of antibacterial soaps. Nonylphenol (NP) is a degradation product of compounds used as surfactants and as stabilizers in plastics. 4,4'-Dichlorodiphenyltrichloroethane (DDT) is a pesticide that is mainly used to control mosquitoes. The compounds were examined for their ability to suppress NK function following exposures of 1 h, 24 h, 48 h, and 6 days. Each agent was able to substantially decrease NK lytic function within 24 h. At a concentration of 5 microM, both TC and NP inhibited NK lytic function by 87 and 30%, respectively; DDT decreased function by 55% at 2.5 microM. The negative effects of each of these compounds persisted and/or intensified following a brief (1 h) exposure to the compounds, indicating that the impairment of function cannot be eliminated by removal of the compound under in vitro conditions.

Inhibition of gap junctional Intercellular communication in WB-F344 rat liver epithelial cells by triphenyltin chloride through MAPK and PI3-kinase pathways

Background

Organotin compounds (OTCs) have been widely used as stabilizers in the production of plastic, agricultural pesticides, antifoulant plaints and wood preservation. The toxicity of triphenyltin (TPT) compounds was known for their embryotoxic, neurotoxic, genotoxic and immunotoxic effects in mammals. The carcinogenicity of TPT was not well understood and few studies had discussed the effects of OTCs on gap junctional intercellular communication (GJIC) of cells.

Method

In the present study, the effects of triphenyltin chloride (TPTC) on GJIC in WB-F344 rat liver epithelial cells were evaluated, using the scrape-loading dye transfer technique.

Results

TPTC inhibited GJIC after a 30-min exposure in a concentration- and time-dependent manner. Pre-incubation of cells with the protein kinase C (PKC) inhibitor did not modify the response, but the specific MEK 1 inhibitor PD98059 and PI3K inhibitor LY294002 decreased substantially the inhibition of GJIC by TPTC. After WB-F344 cells were exposed to TPTC, phosphorylation of Cx43 increased as seen in Western blot analysis.

Conclusions

These results show that TPTC inhibits GJIC in WB-F344 rat liver epithelial cells by altering the Cx43 protein expression through both MAPK and PI3-kinase pathways.

Tetrabromobisphenol A has immunosuppressive effects on human natural killer cells

Human natural killer (NK) cells are lymphocytes that destroy tumor cells, virally-infected cells, and antibody-coated cells. Tetrabromobisphenol A (TBBPA) is used both as a reactive and as an additive flame retardant in a variety of materials and appears to contaminate the environment. TBBPA has been found in human blood samples and if it interferes with NK cell function, this could increase the risk of tumor development and/or viral infection. The present study examines the effects of exposure to various concentrations of TBBPA for 24 hr, 48 hr, and 6 days on the lytic function, tumor-target-binding function, and ATP levels of NK cells. These same parameters were also monitored in NK cells that were exposed to TBBPA for 1 h followed by 24 hr, 48 hr, and 6 days in TBBPA-free media. A 24-h exposure of NK cells to 5 microM TBBPA caused a >95% decrease in NK lytic function, a 70% decrease in binding function, and a 34% decrease in ATP levels in NK cells. Exposure to 2.5 microM TBBPA for 24 h decreased lytic function by 76%, binding function by 20%, and had no effect on ATP levels. Exposure of NK cells to 5 microM TBBPA for 1 h followed by 24 h in TBBPA-free media caused a progressive and persistent loss of lytic function (41%) while not affecting either binding ability or ATP levels. The results indicate that TBBPA exposures decrease the lytic function of human NK cells and that an initial brief (1 hr) exposure can cause a progressive loss of function. In addition, the data also indicate that TBBPA-induced loss of NK lytic function can occur at a concentration of TBBPA that does not affect target-binding ability and ATP levels of NK cells.

Transplacental transfer of phenyltins from a pregnant Dall's porpoise (Phocoenoides dalli) to her fetus

The maternal to fetal transfer of monophenyltin (MPT), diphenyltin (DPT), and triphenyltin (TPT) was investigated for the first time in a cetacean species, a mother-fetus pair of Dall's porpoises (Phocoenoides dalli) collected off the Sanriku coast, Japan. The mother individual was contaminated by phenyltin compounds, and the muscle, blubber, and liver accounted for 90% of the total phenyltin burden. A two-generation phenyltin contamination via transplacental transfer was demonstrated. This study revealed that the transfer rate was 0.29% for total phenyltins to a fetus of about 6-month-old. Unlike in the mother, the fetal liver could not be considered the target organ for all the phenyltins studied. In a ca. 100kg-weight mother Dall's porpoise and its fetus of 2.21kg-weight, approximately 153microg (TPT, 139microg; DPT, 9.4microg; MPT, 4.2microg) and 0.44microg of total phenyltins (TPT, 0.38microg; DPT, 0.03microg; MPT, 0.03microg) were found, respectively. The body burden of TPT consisted of 91% and 86% of the total phenyltin burdens in the maternal and fetal bodies, respectively.