Do foodborne polyethylene microparticles affect the health of rainbow trout (Oncorhynchus mykiss)?

Due to the fact that plastic pollution is a global environmental problem of modern age, studies on the impact of these synthetic materials on aquatic, and especially fish organisms, are an important part of the ecosystem and human nutrition. In our study, the toxicity of pristine polyethylene (PE) microparticles (approx. 50 µm) on rainbow trout (Oncorhynchus mykiss) was tested in three different dietary concentrations - 0.5%, 2% and 5%. After six weeks of exposure, various health indices were evaluated. Electron microscopy of the intestine revealed the disintegration of PE particles to <5 µm in size, and thus we concluded that microplastics are able to reach tissues. The haematological profile revealed changes in total red blood cells count and haematocrit (5% PE) which could be associated with spleen congestion observed histologically. The marker of lipid peroxidation was increased in gills suggesting the disruption of balance in antioxidant enzymes capacity and histopathological imaging revealed inflammation in higher PE concentrations. In addition, ammonia was decreased and calcium elevated in biochemical profile, confirming the gill damage. Electron microscopy of the gills showed lesions of lamellae and visible rings around the mucinous cell opening indicating their higher activity. Another injured was the liver tissue, as confirmed by hepatodystrophies and increased expression of pro-inflammatory genes in 2% PE. Impaired innate immunity was confirmed by an increased presence of mucinous cells and a decrease in leukocytes. Kidney damage manifested itself by higher expression of pro-inflammatory cytokines and histopathology. The damage in gills, liver and kidney together correlated with the increased antioxidant capacity of plasma. In conclusion, PE microparticles are able to affect health indices of O. mykiss. The potential problem for aquatic ecosystems and even human consumption should be considered.

Rosiglitazone shows partial oncostatic effect in rat mammary carcinogenesis.

Peroral antidiabetics from thiazolidinedione (glitazone) group showed oncostatic effects in preclinical models. This study evaluated chemopreventive effects of rosiglitazone in N-methyl-N-nitrosourea-induced mammary carcinogenesis in rats. N-methyl-N-nitrosourea was administered in two intraperitoneal doses each per 50 mg/kg b.w. between 40th and 51st postnatal days. Rosiglitazone was administered in a diet at a concentration of 10 ppm and 100 ppm, respectively, 9 days before the first carcinogen dose until the termination of the experiment. During the experiment the animals were weekly weighed and palpated for the presence of mammary tumors and estimation of latency period, tumor frequency per group and animal, and tumor volume were recorded. The experiment was terminated 16 weeks after the first carcinogen dose, basic tumor growth parameters and selected metabolic and hormonal variables were evaluated. Chemoprevention with higher rosiglitazone dose decreased tumor frequency per group by 44%, other tumor parameters (incidence, tumor frequency per animal) were decreased insignificantly (at both doses), latency period was not changed. Rosiglitazone administration decreased cumulative tumor volume, more efficiently at lower dose. Glycaemia and insulinaemia decreased after lower rosigitazone dose administration but glycaemia did not exceed normal values. Higher rosiglitazone dose alleviated some metabolic alterations resulting from cancer progression more effectively but induced a prominent cardiac hypertrophy.

[Amoebae of the genus Acanthamoeba--causative agents of human infections]. / Menavky rodu Acanthamoeba--pôvodcovia infekcií cloveka.

Amoebae of the genus Acanthamoeba Volkonsky, 1931 are ubiquitous, amphizoic organisms with a cosmopolitan distribution. Pathogenic strains are the causative agents of a difficult to treat disease, granulomatous amoebic encephalitis (GAE), and skin infections in immunocompromised individuals, and of a painful corneal disease--amoebic keratitis (AK) in immunocompetent individuals. The major portals of entry are the nasopharyngeal mucosa, pulmonary parenchyma, skin lesions (GAE, skin infections), eyes in contact lenses wearers with a history of improper contact lens wear and care, or corneal trauma (AK). Symptoms of the diseases are non-specific and variable which alongside with the lack of awareness among health care professionals often hamper early diagnosis. While treatment options for GAE and skin infections are limited and poorly effective, various antifungals and antimicrobials have proved beneficial in AK, although the therapy is often complicated and long.

Weak cytotoxic activity of miltefosine against clinical isolates of Acanthamoeba spp.

Hexadecylphosphocholine (miltefosine) is an anticancer drug active in vitro against various protozoan parasites, and recently used for the treatment of disseminated Acanthamoeba infection. In the present study, we present results of weak cytotoxic activity of this potential amoebicidal agent for 2 of 3 clinical isolates of Acanthamoeba spp. Although the inhibition effect for all tested concentrations was apparent, and showed 100% eradication of trophozoites of Acanthamoeba castellanii strain at a concentration of 62.5 µM after 24 hr, the strains Acanthamoeba sp. and Acanthamoeba lugdunensis exhibited low sensitivity to hexadecylphosphocholine, even in high concentrations. The determined minimal trophocidal concentrations were 250 µM for Acanthamoeba sp. and 500 µM for A. lugdunensis after 24 hr of exposure. Although hexadecylphosphocholine is a potential agent for treatment of Acanthamoeba keratitis and systemic infections, in clinical practice the possible insusceptibility of the amoebic strain should be considered for optimizing therapy.

Metformin in chemically-induced mammary carcinogenesis in rats.

In this paper the chemopreventive effect of peroral antidiabetic metformin in mammary carcinogenesis in female Sprague-Dawley rats was evaluated. Mammary carcinogenesis was induced by N-methyl-N-nitrosourea (NMU) administered in two intraperitoneal doses each per 50 mg/kg b.w. between 43.-55. postnatal days. Metformin was administered in drinking water (at a concentration of 50 microg/ml and 500 microg/ml) 13 days before the first NMU dose until the termination of the experiment. During the experiment the animals were weekly weighed and palpated for the presence of mammary tumors, the incidence, latency, tumor frequency, and tumor volume were recorded. The experiment was terminated 18 weeks after the first NMU dose, basic tumor growth parameters and metabolic and hormonal variables were evaluated. Metformin did not significantly alter the tumor growth although a delay in tumor onset was recorded after higher metformin dose. Metformin altered metabolic and hormonal variables. Insulinemia decreased after both metformin doses in comparison with intact rats without changes in glycemia, triacylglycerols concentration was decreased in liver and increased in serum when compared to intacts. Higher metformin dose attenuated lipoperoxidation in liver.