Toxicological evaluation of multi-class pesticide residues in vegetables and associated human health risk study for adults and children

This article describes, for the first time in 10 years, the toxicological evaluation of pesticide residues in highly consumed vegetables (35 commodities) and health risk studies. Among 1075 vegetable samples consisting mainly of tuber, root, fruiting, and Brassica, 20% of samples contained 38 pesticides in the range of 0.005–18.7 mg/kg and 1% > maximum residue limits (MRLs). Organophosphates and chloronitrile were most frequently found (20%) in the pesticide class. The highest concentration of 18.7 mg/kg was noted for dichlofluanid. Fruiting vegetables (8%), especially tomatoes (5%), were the most contaminated, while multi-residues were determined in 5% of the samples. Risk assessment was performed by analytical results and consumption on the 97.5 percentile expressed as hazard index (HI) and hazard quotient (HQ). The highest chronic HI was calculated for diazinon in lettuce (32% Acceptable Daily Intake (ADI) adults and 36% children) and for forbidden dieldrin in carrots (26%, 62% ADI). The highest acute HI was estimated for dichlofluanid in lettuce (69% Acute Reference Dose (ARfD)) for adults, whereas for children it was above the acceptance values of ARfD (168%). Organophosphate insecticides with common mode of action showed the greatest HQ (108% ADI). Vegetables may not be a serious problem for consumers, but investigations on pesticide residues are necessary to ensure food safety and the protection of human health, especially toward children who are more highly exposed to pesticides than adults.     

Mycobacterium tuberculosis AtsG (Rv0296c), GlmU (Rv1018c) and SahH (Rv3248c) Proteins Function as the Human IL-8-Binding Effectors and Contribute to Pathogen Entry into Human Neutrophils

Mycobacterium tuberculosis is an extremely successful intracellular pathogen that has evolved a broad spectrum of pathogenic mechanisms that enable its manipulation of host defense elements and its survival in the hostile environment inside phagocytes. Cellular influx into the site of mycobacterial entry is mediated by a variety of chemokines, including interleukin-8 (IL-8), and the innate cytokine network is critical for the development of an adaptive immune response and infection control. Using affinity chromatography, liquid chromatography electrospray ionization tandem mass spectrometry and surface plasmon resonance techniques, we identified M. tuberculosis AtsG arylsulphatase, bifunctional glucosamine-1-phosphate acetyltransferase and N-acetylglucosamine-1-phosphate uridyl transferase (GlmU) and S-adenosyl-L-homocysteine hydrolase (SahH) as the pathogen proteins that bind to human IL-8. The interactions of all of the identified proteins (AtsG, GlmU and SahH) with IL-8 were characterized by high binding affinity with K_D values of 6.83x10^-6 M, 5.24x10^-6 M and 7.14x10^-10 M, respectively. Furthermore, the construction of Mtb mutant strains overproducing AtsG, GlmU or SahH allowed determination of the contribution of these proteins to mycobacterial entry into human neutrophils. The significantly increased number of intracellularly located bacilli of the overproducing M. tuberculosis mutant strains compared with those of “wild-type” M. tuberculosis and the binding interaction of AtsG, GlmU and SahH proteins with human IL-8 may indicate that these proteins participate in the modulation of the early events of infection with tubercle bacilli and could affect pathogen attachment to target cells.     

Investigation of Paradiplozoon homoion (Monogenea, Diplozoidae) life cycle under experimental conditions

Diplozoids (Diplozoidae, Monogenea) are fish ectoparasites with a direct life cycle without intermediate hosts. Their free swimming larva, the oncomiracidium, hatches from eggs, invades a fish host and metamorphoses into a post-oncomiracidial larval stage, the diporpa. Later, two diporpae fuse and live as a pair in cross-copulation during their adult life. An experimental study was designed to investigate the life cycle of Paradiplozoon homoion (Monogenea, Diplozoidae) parasitizing their common fish hosts, gudgeon (Gobio gobio). A total of 35 gudgeon parasitized by diplozoids were collected from their natural environment of the Vlára River, Czech Republic, and kept together in tanks with 41 non-parasitized gudgeons reared in a laboratory environment. In total, 100 adult specimens of P. homoion were collected from the Vlára River gudgeon and a new parasite generation was expected to be observed on fish reared in the laboratory environment. Eight days after the first diplozoid eggs appeared on fish gills, the presence of diporpae with one or two pairs of clamps was noted. The appearance of the first juveniles was recorded at the same time as diporpae. Development of P. homoion from egg to sexually mature adult stage took 33 days at a constant temperature of 20 degrees C. The development of eggs in adults of the second generation was observed 2 days after the first observation of these adults. The behavior of oncomiracidia was also studied and this free swimming stage of diplozoids survived for 22 h in the absence of a host. When host fish were experimentally infected by oncomiracidia, diporpae were found attached to the fish gill apparatus within 2 h of infection.     

Three new species of picobiine mites (Acari: Syringophilidae) parasitising African flycatchers (Aves: Muscicapidae)

Three new species of quill mites of the subfamily Picobiinae Johnston & Kethley, 1973 (Acari: Syringophilidae) are described from African flycatchers (Passeriformes: Muscicapidae): Picobia cichladusa n. sp. on Cichladusa arquata Peters and P. myrmecocichla n. sp. on Myrmecocichla arnotti (Tristram), both from Tanzania, and P. echo n. sp. on Cossypha heuglini Hartlaub from the Democratic Republic of the Congo.     

Molecular and functional interactions between Escherichia coli nucleoside-diphosphate kinase and the uracil-DNA glycosylase Ung

Escherichia coli nucleoside-diphosphate kinase (Ndk) catalyzes nucleoside triphosphate synthesis and maintains intracellular triphosphate pools. Mutants of E. coli lacking Ndk exhibit normal growth rates but show a mutator phenotype that cannot be entirely attributed to the absence of Ndk catalytic activity or to an imbalance in cellular triphosphates. It has been suggested previously that Ndk, similar to its human counterparts, possesses nuclease and DNA repair activities, including the excision of uracil from DNA, an activity normally associated with the Ung and Mug uracil-DNA glycosylases (UDGs) in E. coli. Here we have demonstrated that recombinant Ndk purified from wild-type E. coli contains significant UDG activity that is not intrinsic, but rather, is a consequence of a direct physical and functional interaction between Ung and Ndk, although a residual amount of intrinsic UDG activity exists as well. Co-purification of Ung and Ndk through multicolumn low pressure and nickel-nitrilotriacetic acid affinity chromatography suggests that the interaction occurs in a cellular context, as was also suggested by co-immunoprecipitation of endogenous Ung and Ndk from cellular extracts. Glutathione S-transferase pulldown and far Western analyses demonstrate that the interaction also occurs at the level of purified protein, suggesting that it is specific and direct. Moreover, significant augmentation of Ung catalytic activity by Ndk was observed, suggesting that the interaction between the two enzymes is functionally relevant. These findings represent the first example of Ung interacting with another E. coli protein and also lend support to the recently discovered role of nucleoside-diphosphate kinases as regulatory components of multiprotein complexes.     

Extension of the Nef reaction to C-glycosylnitromethanes

Acid-catalysed methanolysis of 3,4,5,6-tetra-O-acetyl-1,2-dideoxy-l-arabino-hex-1-enitol proceeds via a cascade set of consecutive reactions resulting in its regiospecific conversion to a mixture of alpha- and beta-C-L-arabinofuranosylmethanal dimethyl acetals and a mixed internal methyl acetal. Structures of the final products of the overall process provide unique evidence that a kinetically controlled, five-membered-ring closure precedes a six-membered-ring closure in reversible systems capable of giving both five-membered and six-membered all-sp3-atom rings. Determination of the reaction intermediate enabled extension of the Nef reaction to C-glycosylnitromethanes. Protonated aci-nitro forms of C-glycosylnitromethanes that are resistant to the Nef reaction in aqueous acidic media undergo a modified Nef reaction in acidified methanol, and the corresponding C-glycosylmethanal dimethyl acetals with alpha-L-arabinopyranosyl, beta-D-glucopyranosyl, beta-D-galactopyranosyl, beta-D-mannopyranosyl and beta-L-rhamnopyranosyl configurations were obtained in moderate yields.     

Chronic thyroiditis--current issue in the cytological diagnostics of the thyroid gland

INTRODUCTION: Lowered and non-homogenous echogenicity in patients with chronic thyroiditis (CT) may cause problems in revealing focal lesions in ultrasound scans. Moreover, frequent anisocytosis of thyroid follicular cells and of oncocytes may falsely suggest neoplastic growth. The aim of the study was to evaluate the frequency of CT diagnosed in patients subjected to fine-needle aspiration biopsy (FNAB) of the thyroid in years 1994-2005, as well as to assess the cancer frequency in the operated patients with CT. MATERIAL AND METHODS: As much as 23 173 cytological reports and corresponding outcomes were analyzed and in patients treated surgically verified against postoperative histopathological examinations. Moreover, the analysis of cytological smears in CT with distinguishing its types (lymphocytic, epithelial-hyperplastic, colloidal, oxyphillic) was performed in 50 patients; the changes between subsequent FNABs in the picture of the smears were also assessed. RESULTS: The frequency of diagnosed CT had been increasing in the evaluated time span from 2.6% to 9.7% (p < 0.0001). There were 11 cases of papillary carcinoma found coexisting with CT. The analysis of cytological types of CT showed that the lymphocytic type prevailed over the others (lymphocytic - 43%, colloidal--21%, epithelial-hyperplastic--20%, oxyphilic--16%, p < 0.001). The evolution in time of the cytological picture was observed. CONCLUSION: The increase in the frequency of CT observed in smears obtained from the thyroid gland and the reports on the coexistence of CT with papillary carcinoma suggest the necessity of prudent diagnostics and follow-up of patients with CT.     

Role of pro-oxidant properties of flavonoids in the induction of detoxifying enzymes gene expression

Flavonoids are one of the most important components of human daily diet. In recent years flavonoids have became the subject of extensive investigations mostly due to their heath-promoting properties. Beneficial health effects of flavonoids are mainly ascribed to their antioxidant activity. However, there is increasing evidence of the positive role of pro-oxidant properties of flavonoids, considered previously as highly unfavorable, through the induction of detoxifying enzymes gene expression. The article discusses recent reports on the EpRE-mediated induction of NQO1 (NAD(P)H: quinone oxidoreductase) gene expression by the flavonoids (flavonols, flavones and flavan-3-oles) and the role of pro-oxidant properties of the flavonoids in the mechanism of this induction.     

Porcine pregnancy-associated glycoprotein family (pPAGs) - as in vitro-produced chorionic ligands for luteal and uterine gonadotropin receptors

This paper compares proteomic interaction-types and binding-effectiveness of secretory chorionic ligands (including pPAGs) with other proteins, i.e. gonadotropin membrane receptors (Rc) isolated from luteal-phase corpora lutea, uterine myometrium and endometrium of cyclic (cCLRc, cMYORc and cENDRc) or pregnant (pCLRc, pMYORc and pENDRc) pigs. Binding-effectiveness of miscellaneous in vitro-produced chorionic ligands (+pPAGs) was compared by radioreceptor assay (RRA) with endometrial (END) proteins of cyclic, pseudopregnant and pregnant gilts - as negative control ligands and porcine LH and hCG - as positive control ligands. The binding-comparison suggests that the pPAGs may play an important role as potential antiluteolytic or luteoprotective chorionic-origin signals during pregnancy, according to the binding-effectiveness of secretory chorionic ligands (+pPAGs) that was relatively comparable to LH/hCG - as classical ligands competing for luteal and uterine gonadotropin receptors of cyclic and pregnant pigs.