The association between histopathologic effects and liver weight changes induced in mice and rats by chemical exposures: An analysis of the data from Toxicity Reference Database (ToxRefDB).

Absolute (ALW) and relative (RLW) liver weight changes are sensitive endpoints in repeat-dose rodent toxicity studies, and their changes are often used for quantitative assessment of health effects induced by hepatotoxic chemicals using the benchmark dose-response modeling (BMD) approach. To find biologically relevant liver weight changes to chemical exposures, we evaluated all data available for liver weight changes and associated liver histopathologic findings from the Toxicity Reference Database (ToxRefDB). Our analysis of 389 subchronic mouse and rat studies for 273 chemicals found significant differences in treatment-related ALW and RLW changes between dose groups with and without liver histopathologic changes. In addition, we demonstrate that chemical treatment-induced ALW and RLW changes can predict the presence of histopathologic findings and inform the selection of biologically relevant liver weight changes for BMD modeling and derivation of toxicity values.

Interactions between chromium species and DNA in vitro and their potential role in the toxicity of hexavalent chromium.

Epidemiological and animal studies have supported the carcinogenicity of hexavalent chromium [Cr(VI)]; however, molecular changes responsible for the induction of cancer by Cr(VI) are not entirely understood. Numerous mechanistic studies suggested the role of oxidative stress and genotoxicity in Cr(VI)-mediated carcinogenesis; however, specific types of DNA damage have not yet been conclusively attributed to specific chromium species or other reactive byproducts generated in biological systems exposed to Cr(VI). Due to the remarkably complex chemistry and biological effects of chromium species generated through the intracellular reduction of Cr(VI), their relevance for Cr(VI)-mediated carcinogenesis has not yet been fully elucidated and continues to be a subject of ongoing discussions in the field. In this report, we describe a complex world of chromium species and their reactivity with DNA and other biologically relevant molecules in vitro to inform a more complete understanding of Cr(VI)-mediated toxicity. In addition, we discuss previous results in the context of in vitro models and analytical methods to reconcile some conflicting findings on the biological role of chromium species.

Potential problem of the co-occurrence of pandemic COVID-19 and seasonal influenza.

In times of COVID-19 pandemics, the upcoming period of the year when influenza activity usually increases in the Northern Hemisphere brings new medical and public health challenges. These challenges include the risk of mixed infections and/or a possible collision of the two epidemics (“twindemia”) with a potentially serious impact on individual health and public health. In this report, we discuss the results of the published stu-dies and conclude that the catastrophic collision of the seasonal influenza and COVID-19 epidemics is unlikely when efficient non-pharmaceutical public health measures are applied to control or mitigate the spread of the COVID-19 epidemic. This conclusion is supported by several lines of evidence, including the extremely low seasonal influenza activity registered in the Southern Hemisphere in 2020. On the other hand, the existence of mixed SARS-CoV-2 and influenza virus infections has been demonstrated in humans. The continuing uncertainty about the occurrence and potential severity of these mixed infections emphasizes the importance of seasonal influenza vaccination in the current epidemiological situation and raises the need to: (i) ensure vaccine availability, (ii) facilitate access to safe seasonal influenza vaccination under the conditions of the ongoing COVID-19 epidemic, and (iii) promote the vaccine to the public.

Significance of transcriptionally-active high-risk human papillomavirus in sinonasal squamous cell carcinoma: Case series and a meta-analysis.

Sinonasal cancers represent a highly heterogeneous group of head and neck cancers, for which etiological and prognostic significance of high-risk human papillomavirus (HPV) infections has not yet been conclusively established. We investigated the presence of transcriptionally-active high-risk HPV in a series of 34 sinonasal squamous cell cancer (SNSCC) cases and evaluated the effect of transcriptionally-active HPV on the overall survival. In addition, we performed a meta-analysis of previously published studies, including this study, to summarize the prevalence of HPV positivity across histological subtypes of SNSCC. The presence of transcriptionally-active HPV was detected by HPV mRNA using the polymerase chain reaction (PCR) or in situ hybridization (ISH). p16 expression was evaluated as a surrogate marker for transcriptionally-active HPV infection by immunohistochemistry (IHC), the presence of high-risk HPV DNA was tested by PCR and the HPV genotypes were determined by sequencing of PCR amplicons. Transcriptionally-active HPV infections were found in ~25% of the SNSCC cases. The role of HPV infection in keratinizing SNSCC may be higher than previously reported (~32% in our study vs. ~0-6.3% in all other studies). Patients with transcriptionally-active HPV-positive SNSCCs were more likely to be diagnosed at earlier stages (p<0.05) and displayed better mean overall survival, although the difference between HPV-positive and HPV-negative groups was not statistically significant. In contrast to other non-oropharyngeal squamous cell carcinomas (non-OPSCCs) of the head and neck, in SNSCCs, p16/IHC and p16/IHC+HPV DNA displayed high specificity as surrogate markers of transcriptionally-active HPV infections. However, p16/IHC may have significantly lower sensitivity as a surrogate marker of transcriptionally-active HPV in SNSCCs compared to OPSCCs. Furthermore, in our group of SNSCCs, all cases positive for high-risk HPV DNA by PCR were also transcriptionally-active (causative) infections with positive HPV mRNA by ISH. Our results imply a possible different role of HPV-mediated carcinogenesis of squamous cell epithelium in oropharyngeal and sinonasal sites with the latter displaying a lower proportion of causative HPV infections; nevertheless, most cases positive for high-risk HPV DNA, p16/IHC or combination thereof were also found positive for transcriptionally-active HPV. The prognostic significance of HPV status in SNSCCs remains inconclusive and future studies should investigate the presence of transcriptionally-active HPV by direct HPV testing.

Epidemiology of gliomas in women diagnosed with breast cancer supports the protective role of estrogenic exposure.

Gliomas represent the most common type of brain cancers, but their etiology is still poorly understood and understanding of their risk factors is limited. The role of sex hormones in the development of brain cancers has been suggested by epidemiological and experimental studies and clinical observations, which highlighted the need for more evidence before hormone-modulating interventions are developed for prevention or treatment of gliomas. The results of this retrospective cohort study using data from SEER 9 cancer registries demonstrate a decreased risk of brain cancers in women diagnosed with breast cancers at 40+ years, which is consistent with hypothesis that estrogenic exposure reduces the risk of development of gliomas. In contrast, women diagnosed with breast cancer at < 40 years display an increased risk of subsequent brain cancers than women in general population, which likely reflects the role of shared genetic risk factors. These findings support the protective role of estrogens against development of gliomas and suggest the importance of early diagnosis and development of preventive approaches for women diagnosed at younger age (Tab. 2, Fig. 1, Ref. 37).

Cisplatin binds to pre-miR-200b and impairs its processing to mature microRNA.

Cisplatin is an important anticancer drug with a complex mode of action, a variety of possible targets, and numerous resistance mechanisms. While genomic DNA has traditionally been considered to be its most critical anticancer target, several lines of evidence suggest that various RNAs and other biomolecules may play a role in its anticancer mode of action. In this report we demonstrate that cisplatin modifies pre-miR-200b, impairs its processing to mature miRNA, and decreases miR-200b expression in ovarian cancer cells. Considering the role of miR-200b in epithelial-to-mesenchymal transition and cancer chemosensitivity, cisplatin-induced modification of pre-miR-200b and subsequent deregulation of mature miR-200b may, depending on cell context, limit anticancer activity of this important anticancer drug. More gener- ally, precursor miRNAs may be important targets of cisplatin and play a role in this drug's anticancer activity or modulate cell responses to this drug.

[Foodborne botulism - a re-emerging public health challenge]. / Alimentárny botulizmus - staronová výzva pre verejné zdravotníctvo.

Human foodborne botulism is an intoxication caused by ingestion of botulinum neurotoxins (BoNT) of serotypes A, B, E, and rarely also serotype F, produced in contaminated food by anaerobic bacteria Clostridium botulinum group I, group II, or by toxigenic strains of C. butyricum and C. baratii. BoNT-producing Clostridia are ubiquitously distributed in the environment and, under suitable conditions, they can enter the food chain, proliferate and produce BoNT in a variety of foods. In the past, the risk of foodborne botulism was primarily associated with homemade canned foods; however, the epidemiological importance of commercial and restaurant food is increasing nowadays. In this article, we review the public health aspects of foodborne botulism, including its clinical, epidemiological and laboratory diagnosis and discuss potential risks associated with minimally heated, vacuum or modified atmosphere-packed, ready-to-eat foods of extended durability.

Acquired resistance of pancreatic cancer cells to cisplatin is multifactorial with cell context-dependent involvement of resistance genes.

Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal of malignancies, in large measure, due to the propensity of PDAC cells to acquire resistance to chemotherapeutic agents. A better understanding of the molecular basis of acquired resistance is a major focus of contemporary PDAC research. We report here the results of a study to independently develop cisplatin resistance in two distinct parental PDAC cell lines, AsPC1 and BxPC3, and to subsequently examine the molecular mechanisms associated with the acquired resistance. Cisplatin resistance in both resistant cell lines was found to be multifactorial and to be associated with mechanisms related to drug transport, drug inactivation, DNA damage response, DNA repair and the modulation of apoptosis. Our results demonstrate that the two resistant cell lines employed alternative molecular strategies in acquiring resistance dictated, in part, by pre-existing molecular differences between the parental cell lines. Collectively, our findings indicate that strategies to inhibit or reverse acquired resistance of PDAC cells to cisplatin, and perhaps other chemotherapeutic agents, may not be generalized but will require individual molecular profiling and analysis to be effective.

Evidence for the role of microRNA 374b in acquired cisplatin resistance in pancreatic cancer cells.

Recent evidence has implicated microRNAs (miRNAs) as potentially significant players in the acquisition of cancer-drug resistance in pancreatic and other cancers. To evaluate the potential contribution of miRNAs in acquired resistance to cisplatin in pancreatic cancer, we compared levels of more than 2000 human miRNAs in a cisplatin-resistant cell line (BxPC3-R) derived from parental (BxPC3) cells by step-wise exposure to increasing concentrations of the drug over more than 20 passages. The acquired drug resistance was accompanied by significant changes in the expression of 57 miRNAs, of which 23 were downregulated and 34 were upregulated. Employing a hidden Markov model (HMM) algorithm, we identified downregulation of miR-374b as likely being directly involved in acquisition of the drug-resistant phenotype. Consistent with this prediction, ectopic overexpression of miR-374b in the resistant BxPC3-R cells restored cisplatin sensitivity to levels approaching those displayed by the BxPC3 parental cells. The results are consistent with a growing body of evidence implicating miRNAs in acquired cancer-drug resistance and with the potential therapeutic value of these small regulatory RNAs in blocking and/or reversing the process.

Human papillomavirus and Epstein-Barr virus in nasopharyngeal carcinoma in a non-endemic eastern european population.

Nasopharyngeal carcinoma (NPC) is a rare malignancy in the Czech Republic and Slovakia, with the standardized incidence rate of < 1:100000 person-years. Viral status of NPC in these non-endemic Eastern European regions is currently unknown. In a retrospective study, we evaluated the presence of EBV and HPV in 62 NPC cases. EBV status was determined by the use of in situ hybridization (ISH) for EBV encoded small RNA 1 (EBER1). HPV status was examined with p16 immunohistochemistry, DNA ISH and DNA polymerase chain reaction. Sixty-one studied cases showed non-keratinizing morphology and one was keratinizing squamous cell carcinoma. Only one NPC with non-keratinizing morphology was scored as p16-positive (nuclear and cytoplasmic staining ≥ 70% of tumor cells). This case was positive for high-risk HPV by ISH and the DNA PCR confirmed the presence of HPV18 type. At the same time, this case was found negative for EBV. Remaining sixty-one cases that were scored as p16-negative were all found HPV-negative by ISH and the DNA PCR. EBV was detected in 85.5% (53/62) of cases and 9 cases were EBV-negative, including the case of keratinizing NPC. In contrast with previous reports on the prevalence of EBV-positivity in Caucasian patients with NPC, the majority of patients coming from this non-endemic region show EBV-positivity; therefore, they may be candidates for novel EBV-targeting therapies. Conversely, HPV-positive NPC is very rare and HPV does not seem to play a significant role in the etiopathogenesis of NPC in these Eastern European populations.

The design, synthesis and anticancer activity of new nitrogen mustard derivatives of natural indole phytoalexin 1-methoxyspirobrassinol.

Nitrogen mustards cis-1-methoxy-2-deoxy-2-[N,N-bis(2 -chloroethyl)amino]spirobrassinol (4) and trans-1-methoxy-2-deoxy-2-[N,N-bis(2 -chloroethyl)amino]spirobrassinol (5) derived from 1-methoxyspirobrassinol, an indole phytoalexin produced by the Japanese radish Raphanus sativus var. hortensis were designed as prospective dual-action compounds with DNA-alkylating effect and glutathione-depleting effects that may sensitize cancer cells to alkylating agents. Both new compounds demonstrated cytostatic/cytotoxic effects on various leukemia and ovarian cancer cell lines and dsDNA-destabilizing effects in vitro. Compound 4, the more promising of the two compounds, exerts earlier onset of anticancer effects on Jurkat cells via induction of apoptosis compared to the traditional alkylating anticancer agent melphalan. In addition, it demonstrated higher potency on ovarian cancer OVCAR-3 cell line and lower fold resistance between Jurkat and Jurkat-M cells selected for the resistance to melphalan. Therefore, compound 4 may be less affected by certain cancer drug resistance mechanisms than melphalan and it may become a prototype of a new class of anticancer active nitrogen mustards that combine DNA-damaging and DNA-damage-sensitizing properties.

Cruciferous phytoalexins: antiproliferative effects in T-Jurkat leukemic cells.

We tested antiproliferative activity of selected cruciferous phytoalexins including brassinin, 1-methoxybrassinin, (+/-)-spirobrassin, (+/-)-1-methoxyspirobrassinin and (+/-)-1-methoxyspirobrassinol, in leukemic Jurkat cell. The most effective of the tested phytoalexins was 1-methoxybrassinin with IC(50) 10 micromol l(-1). However, significant effect of all phytoalexines was also determined at concentration 1 micromol l(-1). In 1-methoxybrassinin-treated Jurkat cells, we found significant increase in the fraction of cells with a sub-G(0)/G(1) DNA content, which is considered to be a marker of cell death by apoptosis. Apoptosis was also confirmed by the annexin V staining. In summary, 1-methoxybrassinin exerted potent antiproliferative activity probably due to cell cycle arrest and apoptosis induction.

[Apoptosis, tumor phenotype and pathogenesis of malignant tumors]. / Apoptóza, nádorový fenotyp a patogenéza zhubných nádorov.

Integrity of multicellular organisms is maintained by balance between cell proliferation and programmed cell death (apoptosis). Apoptosis is programmed cell death by regulated active process characterized by specific morphological and biochemical changes, whereas necrosis is a passive and genetically uncontrolled process followed by an inflammatory reaction of surrounding tissue. Suppression of apoptosis may contribute to the development of malignant tumours by means of accumulation of continuously proliferating cells and disruption of elimination of genetically altered cells with increasing malignant potential. Cell proliferation, differentiation and apoptosis are regulated by p16-cyclin D1-CDK4-Rb and p19ARF-p53-p21WAF1 pathways, which interact through multifunctional genes Rb and p53. Malignant tumours result from an accumulation of mutations of oncogenes, tumour-suppressor genes, pro-apoptotic and anti-apoptotic genes or from functional alterations of protein products of these genes as well. That results in dysregulation of the cell cycle and apoptosis and in the development of other signs of tumour phenotype (chromosomal instability, disruption of DNA repair, disruption of cell-cell communications and interactions between cells and extracellular matrix, suppression of the cell differentiation and replicative senescence, angiogenesis and changes in cell motile activity). Alteration of apoptosis, and/or genes involved in its regulation, is expressed in most manifestations of tumour phenotype. Thus, alteration of apoptosis strongly affects biological properties of malignant tumours and efficacy of their multimodal therapy. Present-day multimodal therapy of malignant tumours is specifically aimed at promoting the rate of apoptosis within tumours.

Antiproliferative and cancer chemopreventive activity of phytoalexins: focus on indole phytoalexins from crucifers.

Phytoalexins are produced by plants after exposure to physical, biological or chemical stress and a specific group of these metabolites represent indole phytoalexins produced by important plants of the family Cruciferae. With respect to the epidemiologically proven cancer chemopreventive properties of brassica vegetables, antiproliferative and anticarcinogenic activities of indole phytoalexins have been studied. Several indole phytoalexins (i.e. brassinin, spirobrassinin, brassilexin, camalexin, 1-methoxyspirobrassinin, 1-methoxyspirobrassinol and methoxyspirobrassinol methyl ether) have been found to possess significant antiproliferative activity against various cancer cells and this activity is supposed to be associated with the modulation of activity of transcription factors regulating cell cycle, differentiation and apoptosis. Indole phytoalexins (i.e. cyclobrassinin, spirobrassinin, brassinin) also exhibited cancer chemopreventive activity in models of mammary and skin carcinogenesis. Understanding the molecular and cellular mechanism of action of such drugs and their structure-activity relationships is necessary for development new derivatives with more favourable profile of antiproliferative and chemopreventive activities.

[Pharmacokinetics of ethyl alcohol and its importance for forensic calculations of blood alcohol levels]. / Farmakokinetika etylalkoholu a jej poznatky pre súdnolekárske výpocty hladín alkoholu v krvi.

Calculations of blood alcohol concentration for forensic purposes are based on several simplified assumptions (linear pharmacokinetics of ethanol, constant rate of ethanol elimination within full range of time, constant rate of alcohol absorption and constant time of peak blood alcohol levels achievement which is by convention depending only on type of a beverage and quantity of food consumed). Simplified and idealized assumptions mentioned above significantly restrict possibility of back-extrapolations of blood alcohol concentrations from the observed values and calculations based on them exclude the absorption phase of blood alcohol curve from being estimated. In this work there are designs of more advanced models of alcohol pharmacokinetics describing blood alcohol concentrations within full ranges of blood alcohol curves. Their possible benefits for forensic medicine and practical aspects are discussed.