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Due to toxicity and compliance issues and the emergence of resistance to current medications new drugs for the treatment of Human African Trypanosomiasis are needed. A potential approach to developing novel anti-trypanosomal drugs is by inhibition of the 6-oxopurine salvage pathways which synthesise the nucleoside monophosphates required for DNA/RNA production. This is in view of the fact that trypanosomes lack the machinery for de novo synthesis of the purine ring. To provide validation for this approach as a drug target, we have RNAi silenced the three 6-oxopurine phosphoribosyltransferase (PRTase) isoforms in the infectious stage of Trypanosoma brucei demonstrating that the combined activity of these enzymes is critical for the parasites’ viability. Furthermore, we have determined crystal structures of two of these isoforms in complex with several acyclic nucleoside phosphonates (ANPs), a class of compound previously shown to inhibit 6-oxopurine PRTases from several species including Plasmodium falciparum. The most potent of these compounds have Ki values as low as 60 nM, and IC50 values in cell based assays as low as 4 μM. This data provides a solid platform for further investigations into the use of this pathway as a target for anti-trypanosomal drug discovery., Author summary Human African Trypanosomiasis (HAT) is a life-threatening infectious disease caused by the protozoan parasite, Trypanosoma brucei. Current treatments suffer from low efficacy, toxicity issues and complex medication regimens. Moreover, an alarming number of these parasites are demonstrating resistance to current drugs. For these reasons, there is a renewed effort to develop new classes of modern therapeutics based upon the unique T. brucei cellular processes. One potential new drug target is 6-oxopurine phosphoribosyltransferase (PRTase), an enzyme central to the purine salvage pathway and whose activity is critical for the production of the nucleotides (GMP and IMP) required for DNA/RNA synthesis within this protozoan parasite. We demonstrated that T. brucei encodes two isoforms of hypoxanthine-guanine PRTases (HGPRT) and one hypoxanthine-guanine-xanthine PRTase (HGXPRT). The concurrent activity of these enzymes is required for the normal cell growth in vitro. Moreover, acyclic nucleoside phosphonates represent a promising class of potent and selective compounds as they inhibit the enzymes with Ki values in nanomolar range and exert cytotoxic effects on T. brucei cells grown in vitro with EC50 values in the single digit micromolar range. Our results provide a new foundation for further investigations of these compounds in vivo and suggest that 6-oxopurine salvage pathway represents a possible target for future drug discovery efforts directed at eliminating HAT.

The authors researched the incidence of suicidal thoughts and related factors in 123 patients of the psychiatric ward of the Hospital of České Budějovice with diagnosed attempted suicide in their medical history for the period from January 2013 – June 2015.The research was carried out in two stages. At the beginning of the hospitalization, quantitative data collection was implemented using a semi-structured questionnaire, followed by qualitative research conducted with semi-structured phone conversation, based on previous patient's written consent. The research data were statistically processed to obtain information about the character of relations among individual characteristics. To quantify them, the Bayesian Network (BN) was constructed, and to identify relations among individual characteristics, the Hill-Climbing algorithm was used. Before deriving the network, variables were discretized. The network parameters were set based on a data matrix using the maximal plausibility method.The results of analysed set show that the probability of suicidal thoughts is high, achieving a value of 0.750 (0.781 for women and 0.724 for men). If the patient visits a contact centre for drug-addicted persons, the probability of suicidal thoughts decreases to 0.683. If the patient visits a psychotherapist, the values of 0.736 are achieved. If a daily care centre is visited, the estimated risk rises to 0.832 and the probability of the patient repetitively attempting suicide is 0.606. If the interviewed person regularly consumes alcohol, the probable relapse amounts to 0.616. But if the person consumes alcohol from time to time, the probability rises to 0.701. In case of abstinence, the probable relapse decreases to 0.565.The incidence of suicidal thoughts in observed patients was high, and the amount of risk was influenced by gender, by visiting follow-up care facilities, psychotherapy, and particularly by the frequency of alcohol consumption. Intermittent alcohol consumption is the highest-risk factor in connection with relapsing suicide. In case of psychiatric patients with attempted suicide in their medical history, all verified preventive and therapeutic procedures that can contribute to prevention of relapses should be used within follow-up professional care. Specific approach of the closest social environment, medical literacy of the population and state safety measures are important.

Campylobacteriosis is among the most frequently reported foodborne diseases in both the Czech Republic (CR) and South Bohemian Region (SBR). Campylobacteriosis has been a notifiable disease in the CR since 1984. The objective of this study is the analysis of the data reported to the surveillance system between 2005 and 2014 to describe the seasonal variation, age specific incidence, and route of transmission of campylobacteriosis in the South Bohemian Region.The data reported to the surveillance system EPIDAT from 2005 to 2014 were analysed in order to determine the incidence trends and seasonality, age distribution, and route of transmission of campylobacteriosis in the South Bohemian Region.Campylobacteriosis incidence in the South Bohemian Region follows the same annual pattern as in the Czech Republic. There is a very slight declining trend in the incidence over the study period. A strong seasonal variation was observed, with a late summer peak and a winter low. An exception to the regularity of the incidence pattern was an outbreak notified in 2010. The most affected age groups are children 1 to 5 years and newborns (0 age group). In the other age groups, the incidence has a declining tendency. The most common vehicles for the transmission of campylobacteriosis are chicken and meat products while other vehicles and routes of transmission have been reported exceptionally.Only one third of cases have been notified along with the suspected route of transmission. The most common route of transmission is through the consumption of contaminated chicken and meat, including smoked meat products. Therefore, the measures targeting consumers and also producers of poultry, meat, and unpasteurized milk products may contribute to the reduction of campylobacteriosis incidence.

Aristolochic acid (AA) causes aristolochic acid nephropathy, Balkan endemic nephropathy, and their urothelial malignancies. To identify enzymes involved in the metabolism of aristolochic acid I (AAI), the major toxic component of AA we used HRN (hepatic cytochrome P450 [Cyp] reductase null) mice, in which NADPH:Cyp oxidoreductase (Por) is deleted in hepatocytes. AAI was demethylated by hepatic Cyps in vitro to 8-hydroxy-aristolochic acid I (AAIa), indicating that less AAI is distributed to extrahepatic organs in wild-type (WT) mice. Indeed, AAI-DNA-adduct levels were significantly higher in organs of HRN mice, having low hepatic AAI demethylation capacity, than in WT mice. Absence of AAI demethylation in HRN mouse liver was confirmed in vitro; hepatic microsomes from WT, but not from HRN mice, oxidized AAI to AAIa. To define the role of hepatic Cyps in AAI demethylation, modulation of AAIa formation by CYP inducers was investigated. We conclude that AAI demethylation is attributable mainly to Cyp1a1/2. The higher AAI-DNA adduct levels in HRN than WT mice were the result of the lack of hepatic AAI demethylation concomitant with a higher activity of cytosolic NAD(P)H:quinone oxidoreductase (Nqo1), which activates AAI. Mouse hepatic Cyp1a1/2 also activated AAI to DNA adducts under hypoxic conditions in vitro, but in renal microsomes, Por and Cyp3a are more important than Cyp1a for AAI-DNA adduct formation. We propose that AAI activation and detoxication in mice are dictated mainly by AAI binding affinity to Cyp1a1/2 or Nqo1, by their turnover, and by the balance between oxidation and reduction of AAI by Cyp1a.

Ellipticine is an antineoplastic agent, whose mode of action is based mainly on DNA intercalation, inhibition of topoisomerase II and formation of DNA adducts mediated by cytochrome P450 (CYP). We investigated the ability of CYP enzymes in rat, rabbit and human hepatic microsomes to oxidize ellipticine and evaluated suitable animal models mimicking its oxidation in humans. Ellipticine is oxidized by microsomes of all species to 7-hydroxy-, 9-hydroxy-, 12-hydroxy-, 13-hydroxyellipticine and ellipticine N(2)-oxide. However, only rat microsomes generated the pattern of ellipticine metabolites reproducing that formed by human microsomes. While rabbit microsomes favored the production of ellipticine N(2)-oxide, human and rat microsomes predominantly formed 13-hydroxyellipticine. The species difference in expression and catalytic activities of individual CYPs in livers are the cause of these metabolic differences. Formation of 7-hydroxy- and 9-hydroxyellipticine was attributable to CYP1A in microsomes of all species. However, production of 13-hydroxy-, 12-hydroxyellipticine and ellipticine N(2)-oxide, the metabolites generating DNA adducts, was attributable to the orthologous CYPs only in rats and humans. CYP3A predominantly generates these metabolites in rat and human microsomes, while CYP2C3 activity prevails in microsomes of rabbits. The results underline the suitability of rat species as a model to evaluate human susceptibility to ellipticine.

The submitted paper deals with possibilities of assessment of human age based on findings of stereospecific breakdown of proteins containing D-forms of aspartic acid. The stereospecificity of enzymatic breakdown assumes that after enzymatic hydrolysis peptide breakdown products with different molecular weights--the so-called peptide map--will be formed, depending how many D-aspartyl residues the protein contains. The authors proved in the submitted preliminary study in subjects of different age the formation of breakdown products of different size in non-collagenous proteins of human dentin which was hydrolyzed by protease V8 from Staphylococcus aureus.

The human parvovirus B 19 was discovered in 1975 by Cossart but its etiological association with erythema infectiosum and hydrops of the foetus was proved only in 1984-1985. The objective of the submitted prospective study was to assemble basic findings on the herd immunity of the female population and the risk of infection with this agent during pregnancy. Seropositivity of women of fertile age before the epidemic of parvovirus B 19 in 1993 and 1994 was cca 50%, after the epidemic 70%. Erythema infectiosum is a childhood disease (96% of the cases are children under 14 years of age), but seroprevalence of parvovirus IgG in these age groups is only 11%. Thus the infection in adults is frequent but not diagnosed. A parvovirus etiology of possible loss of the foetus on the basis of serological examination is encountered only exceptionally. The Czech commercial preparation gammaglobulin can be used for prevention and treatment of a non-immune foetal hydrops.

The human parvovirus B 19 was discovered in 1975 by Cossart in England. Later (1984) evidence was provided that this virus is the etiological agent of erythema infectiosum and hydrops foetalis, and in 1985 it was provided that it is also the etiological agent of some types of arthritis or arthropaties and vasculitis. The diagnosis of the disease caused by this agent is most frequently based on evidence of specific immunoglobulins. The epidemiological and clinical impact of parvoviral infections in the Czech Republic was not known so far. Examination of sera from 562 subjects aged 0-60 years assembled in 1992 in three Czech regions revealed in children, age 0 - 4 years 9.8%, during preschool and school age 27 - 35.7% and in age groups above 15 years a 53.3 - 57.7% seroprevalence of IgG parvovirus B 19, roughly equally distributed among both sexes. The more frequent prevalence of specific immunoglobulins was proved in small groups of female workers in nurseries (66.7%), nursery schools (91.7%) and in blood transfusion stations (77.8%). The seropositivity of the general female population of matched age groups, with the exception of women aged 20 - 24 years, was 53.86%.