Avian trematodes of central European corvids are heterogeneous regarding preferences for host species and age.

Corvids are highly adaptive birds that respond well to anthropogenic changes in their environment. Trematode communities of corvids were studied mainly in the 1950s through 1970s in regularly flooded parts of the Volga River delta in Russia; more recent studies and data from other regions where the corvids are in less contact with postflooding habitats are limited. Data for Corvus corax were lacking. Using our samples obtained from 1963 to 2023, we performed a large-scale analysis of trematode species composition and community structure in Corvus frugilegus, Corvus cornix, C. corax, Coloeus monedula, Pica pica, and Garrulus glandarius; all originated from the Czech Republic. We identified corvids as hosts of mutually overlapping component communities of only a few species of trematodes (Brachylecithum lobatum, Lyperosomum petiolatum, Lyperosomum longicauda, Tamerlania zarudnyi, Urogonimus macrostomus), with the presence of many rare and incidental findings of other trematode species. Only a few species used corvids as their core hosts (L. longicauda and B. lobatum). Trematode component communities in first-year birds included Prosthogonimus cuneatus, Prosthogonimus ovatus, Plagiorchis asperus, and Morishitium dollfusi due to an increased share of insects (intermediate hosts of Prosthogonimus and Plagiorchis) and snails (intermediate hosts of Morishitium) in the diet of juveniles. The trematode component communities of corvid species overlapped but were heterogeneous at the level of host individuals, likely reflecting differences in food sources related to the respective host ages and nesting sites.

Severe decline in abundance of Cyathostoma lari, a parasite of the nasal and orbital sinuses of gulls, at their central European nesting grounds.

Cyathostoma lari is a parasite of the nasal and orbital sinuses of gulls and other hosts in Europe and Canada. Here, we provide an overview of previously published data on the prevalence and infection intensity of C. lari in gulls. Furthermore, based on our data, we analyze the spatiotemporal trends in the prevalence and intensity of infection by C. lari in Chroicocephalus ridibundus in Czechia (central Europe; data from 1964 to 2014) and compare them with those obtained from five species of gulls in Karelia (Northwest Russia; data from 2012-2020). Based on our preliminary observations, we hypothesized that C. lari is subject to a decline in certain regions, but this decline is not necessarily applicable throughout its distribution range. We found that the C. lari population crashed in specific parts of its distribution range. The reasons are unknown, but the observed population changes correspond with the diet switch of their core host in Czechia, C. ridibundus. We previously observed a diet switch in Czech C. ridibundus from earthworms (intermediate hosts of C. lari) to other types of food. This diet switch affected both young and adult birds. Nevertheless, it may not necessarily affect populations in other regions, where they depend less on earthworms collected from agrocenoses affected by agrochemicals and trampling. Correspondingly, we found that these changes were limited only to regions where the gulls feed (or fed) on arable fields. In Karelia, where arable fields are scarce, gulls likely continue to feed on earthworms and still display high infection rates by C. lari. Therefore, C. lari, a parasite of the nasal and orbital sinuses of gulls, nearly disappeared from their central European nesting grounds but is still present in better-preserved parts of its distribution range.

Molecular characterization of European Pygorchis Looss, 1899.

Adult trematodes of the genus Pygorchis Looss, 1899 (Trematoda: Philophthalmidae) parasitize the cloaca of birds. The genus contains three species, all of which are rarely reported and molecular phylogenetics of which have not been applied. The absence of reference DNA sequences limit studies of their indistinct larval forms. Based on the materials that were obtained from birds of the Czech origin, we performed a molecular characterization of both currently known Pygorchis spp., which are known from the Palearctic, the type species Pygorchis affixus Looss, 1899 and Pygorchis alakolensis Zhatkanbaeva, 1967, and provided morphological description of the examined P. alakolensis specimen. We found that the two species were of similar dimensions; the only difference was in the position of testes and in the extent of vitelline follicles. However, the position of testes in P. affixus was variable, and approximately 10% of examined P. affixus individuals had testes positioned obliquely. The second feature that allows differential diagnostic, the extent of vitelline follicles, was more reproducible as the vitelline follicles of P. affixus did not extend beyond the intestinal caeca, or, in exceptional cases, they extended them at only one side. In the examined P. alakolensis individual, the testes were positioned obliquely, and the vitelline follicles extended beyond the intestinal caeca. We reported P. alakolensis for the first time from Europe; previously, it was known only from Central Asian lakes and rivers. We confirmed the classification of Pygorchis into Philophtalmidae.

Helminth endoparasites of the smooth newt Lissotriton vulgaris: linking morphological identification and molecular data.

The helminth endoparasites of many European amphibian species are often known exclusively from morphological descriptions. A molecular library of DNA sequence data linked to morphological identifications is still in its infancy. In this paper, we aim to contribute to such a library on the smooth newt Lissotriton vulgaris, the intermediate and definitive host of 31 helminth parasites, according to evidence published so far. Newts (n = 69) were collected at two study sites in western Germany and examined for the presence of helminths. A total of five helminth species were detected in 56 (81%) of the newts, but only one or two species infected a single host. Four out of five helminth species were identified morphologically and based on DNA sequences as Parastrigea robusta (metacercariae), Oswaldocruzia filiformis, Megalobatrachonema terdentatum (adults and larvae) and Cosmocerca longicauda, and the corresponding sequences were provided subsequently. Oswaldocruzia molgeta was confirmed to be a junior synonym of O. filiformis. Molecular data on a fifth species (a cosmocercid nematode) that could not be identified at species level were added to GenBank. These findings increased the molecular library on morphologically identified smooth newt parasites significantly, from 12 to 15 entries.

Positivity for islet cell autoantibodies in patients with monogenic diabetes is associated with later diabetes onset and higher HbA1c level.

AIMS: Islet cell autoantibodies are associated with autoimmune insulitis and belong to the diagnostic criteria of type 1 diabetes mellitus. However, growing evidence suggests that autoantibodies are present in other types of diabetes. Here, we focus on the autoantibody incidence in Czech patients with maturity-onset diabetes of the young and analyse their functional relevance in terms of diabetes onset and control. METHODS: Autoantibodies against glutamic acid decarboxylase (GAD) 65 and protein tyrosine phosphatase islet antigen 2 (IA-2) were measured in a cohort of 28 Czech patients with maturity-onset diabetes of the young, all confirmed by genetic testing. Selected clinical data were correlated to the status and kinetics of autoantibodies. RESULTS: One quarter of patients with maturity-onset diabetes of the young examined (7/28; 25%) was positive for GAD or IA-2 autoantibodies. GAD autoantibodies were more prevalent (7/7) than IA-2 autoantibodies (1/7). The incidence of autoantibodies did not correlate with human leukocyte antigen status. The patients who were positive for the autoantibodies developed diabetes later than those who were autoantibody-negative, but had worse glycaemic control (increased HbA1c ). Expression of autoantibodies decreased with any improvement of diabetes compensation. Only one patient did not correspond to the above and displayed signs of combined signs of maturity-onset diabetes of the young and Type 1 diabetes. CONCLUSIONS: The data suggest transient but highly prevalent islet cell autoantibody expression in Czech patients with maturity-onset diabetes of the young. The autoantibodies were found in patients with delayed diabetes onset, and in times of insufficient diabetes control. As improvement of glycaemic control was associated with a decrease in levels of autoantibodies, their presence may reflect the kinetics of ß-cell destruction induced by causes other than autoimmune ones.

[Dabrafenib: the new inhibitor of hyperactive B-RAF kinase]. / Dabrafenib: nový inhibitor hyperaktivní kinázy B-RAF.

The B-RAF kinase is among major targets of biological therapy of cancer. B-RAF acts in the MAP kinase pathway, being activated by any of the RAS G-proteins. Hyperactive B-RAF is typically detected in chemoresistant and radioresistant malignant metastatic melanoma. In this study, we focus on the reversible ATP-competitive inhibitor dabrafenib (GSK-2118436), which is now in phase III clinical trial for use in subjects with various cancers expressing hyperactive B-RAF. Dabrafenib is selective for B-RAFV600E and B-RAFV600K (less for B-RAFV600D) over wild-type B-RAF. Thus, similarly to vemurafenib (Zelboraf), suggested is mandatory pre-screening for activating B-RAF mutations in the cancer tissue of each subject. Dabrafenib inhibits neoplastic growth at concentrations 53.8 nM in plasma, which corresponds to 30 mg/kg qd p.o., or to --- 3 mg/kg qd i.v. Most of the cancers expressing hyperactive B-RAF respond to dabrafenib treatment, but the complete response is only rarely achieved. Toxic side effects include skin lesions, pyrexia, frequent fatigue, nausea and pain. Resistance to dabrafenib is frequently developed via de novo RAS mutations, leading to the disease relapse. The RAS G-protein is capable of signaling downstream not only through B-RAF, but also through closely related C-RAF, which circumvents the effects of the B-RAF inhibitor. Thus, dabrafenib should not be prescribed to subjects with neoplasias that are positive for activating RAS mutations. Since B-RAF mutations alone cause only the formation of benign naevi, since the tumors frequently and quickly acquire resistance to B-RAF inhibitors, and because the B-RAF-inhibitor-mediated treatment outcomes are severely affected by changes in the activity and expression of a number of signaling molecules (among them PI3K/mTOR, PTEN, AKT, MEK, PDGFRß), it can be anticipated that dabrafenib treatment should be suggested only as a part of combined therapy targeting simultaneously the other pathways responsible for cancer onset and progression.

[Advances in clinical treatment of malignant melanoma: B-RAF kinase inhibition]. / Pokroky v klinické lécbe zhoubného melanomu: inhibice kinázy B-RAF.

Malignant melanoma is an aggressive cancer of pigment-producing cells, derivates of the neural crest. Surgical resection is the most effective form of treatment during initial phases of the disease. Advanced stages are usually treated by adjuvant immunotherapy (interferon alpha) or dacarbazine + multiferon. Response and survival rates are extremely poor. The emerging approach of personalized medicine brings about significant advances in the treatment of melanoma. Apart from administration of imatinib for a small subgroup of melanomas harbouring KIT mutations, the most promising approach is the use of B-RAF kinase inhibitors. The previously tested RAF inhibitors (e.g. sorafenib) did not perform better compared to conventional chemotherapy or immunotherapy. However, the results are much more promising with the recently developed inhibitor PLX4032 (Plexxikon; RG7204, Roche Pharmaceuticals; vemurafenib). This inhibitor targets tumours harbouring B-RAF(V600E) of B-RAF(V600K) activating mutations, which are present in 40-70% of malignant melanomas. An absence of the above mentioned activating mutations or parallel presence of activating RAS mutations (e.g. RAS(G12D)) should be used as contraindications. The use of PLX4032 provides better outcome than any of the currently used therapies, including partial or complete response recorded in 81% of patients, and prolonged median survival. Currently, this drug is being tested in phase II and III trials. The incidence of PLX4032-related adverse effects is relatively high; acquired resistance repeatedly occurring within several months of treatment may also represent a significant problem. Combined therapy is probably needed to further increase the complete response rate and to prolong survival. This should either include some of the currently used chemotherapeutics, or alternatively it may employ inhibitors of some of the kinases capable of stimulating the MEK and ERK kinases independently of B-RAF (e.g. COT). Nevertheless, even PLX4032 monotherapy should be viewed as a significant improvement of the current state-of-the-art treatment of malignant melanoma.

[Indication of EGFR kinase inhibitors should be refined]. / Zpresneme indikaci podávání inhibitoru kinázové aktivity EGFR.

Even though lung cancer incidence began to decline in the majority of industrialized countries, is still belong to cancers with one of the highest incidence and mortality rates. In the Czech Republic, epidermal growth factor receptor (EGFR) kinase activity inhibitors erlotinib and gefitinib are approved for the use as the second- and third-line treatment of non-small-cell lung cancer. In a cohort of non-small-cell lung cancer patients, erlotinib administration led to tumour regression in less than 20% of patients. However, when used in patients with EGFR-activating mutations, e.g. L858R or delE746-A750, the response rate increased to 75-82% in several parallel clinical studies. Similarly, improved response rate was reported in patients bearing amplified wild-type EGFR gene. In contrary, patients with T790M, D761Y, L747S, and T854A mutations (and some other rare abberations) were found to be resistant to treatment with small-molecule inhibitors targeting the active site of the kinase domain. These mutations do not change the EGFR affinity to gefitinib or erlotinib but the mutated receptor is able to bind ATP into its active site even in the presence of erlotinib or gefitinib, similar to a wild-type receptor without an inhibitor. Besides that, when the EGFR molecule bears both the activating (e.g. L858R) and resistance-inducing mutation (e.g. T790M), the tumour acquires resistance to both erlotinib and gefitinib treatment. Currently, research focuses on a development of new strategies that would allow treatment of patients bearing mutations inducing resistance to the small-molecule inhibitors targeted on the active site of EGFR kinase domain. Contrary to the current guidelines for Czech oncologists, identification of EGFR with any of the above mentioned resistance-inducing somatic mutations should be considered as an explicit contraindication for non-small-cell cancer treatment using small-molecule EGFR kinase activity inhibitors erlotinib or gefitinib. This should also include patients in whom a resistance-inducing mutation is detected together with any of the activating mutations or deletions.

Use of protein tyrosine phosphatase inhibitors as promising targeted therapeutic drugs.

Protein tyrosine phosphatases (PTPs) are considered to be involved in the etiology of diabetes mellitus, neural diseases such as Alzheimer;s and Parkinson;s disease, regulation of allergy and inflammation, or they are even considered to be responsible for the pathogens; virulence in vivo. Since discovery of first PTP inhibitors such as dephostatin in early 90th years, the research moved on toward search for inhibitors specific for the individual PTP molecules. Currently, dozens of new PTP inhibitors are reported each year, ranging from natural products, natural product analogs, peptides, phosphonates, nonpeptidic inhibitors, mimotopes, metal-containing inhibitors, redox inhibitors, to simply silencing RNAs as widely used inhibitors of PTP expression. Several currently used drugs also show PTP inhibitory activity. Among them are sodium stibogluconate, phenylarsine oxide, alendronate, etidronate, vanadate, gallium nitrate, suramin, or aplidin. However, the market is still waiting for the first clinically approved selective PTP inhibitor. Here in this review are described inhibitors of activity or expression of the particular classical PTPs, with emphasis on specific inhibition of the respective PTP over the others. The inhibitors are not classified according to their chemical composition, but according to their biological activity, which should help to simplify search for inhibitors of particular classical PTPs. Even though PTP inhibitors are difficult to develop, lifting the fog of phosphatase inhibition is of the great market potential and further clinical impact.

Regulation of cys-based protein tyrosine phosphatases via reactive oxygen and nitrogen species in mast cells and basophils.

Activation of mast cells and basophils is accompanied by the production of reactive oxygen and nitrogen species that regulate diverse signaling pathways leading to the release of inflammatory mediators and production of a variety of cytokines. Although the functional pathways of reactive oxygen and nitrogen species in vivo are not completely understood, some novel metabolic pathways can be envisioned based on recent findings that protein tyrosine phosphatases can be regulated by reversible oxidation. In this review, we describe major sources and targets of reactive oxide and nitrogen species in mast cells and basophils. Direct and indirect regulations of class I and II Cys-based protein tyrosine phosphatases (LMW-PTP, PTEN, PTP-PEST, SHP-2, PTP1B, PTPalpha, PTPepsilon, DEP-1, TC45, SHP-1, HePTP and LAR) are discussed. The combined data highlight the role of redox-regulated protein tyrosine phosphatases as targets in the development of new ways of therapeutic intervention in allergies and inflammatory diseases.

Finding the smoking gun: protein tyrosine phosphatases as tools and targets of unicellular microorganisms and viruses.

Protein tyrosine phosphatases (PTPs) are increasingly recognized as important effectors of host-pathogen interactions. Since Guan and Dixon reported in 1990 that phosphatase YopH serves as an essential virulence determinant of Yersinia, the field shifted significantly forward, and dozens of PTPs were identified in various microorganisms and even in viruses. The discovery of extensive tyrosine signaling networks in non-metazoan organisms refuted the moth-eaten paradigm claiming that these organisms rely exclusively on phosphoserine/phosphothreonine signaling. Similarly to humans, phosphotyrosine signaling is thought to comprise a small fraction of total protein phosphorylation, but plays a disproportionately important role in cell-cycle control, differentiation, and invasiveness. Here we summarize the state-of-art knowledge on PTPs of important non-metazoan pathogens (Listeria monocytogenes, Staphylococcus aureus, Porphyromonas gingivalis, Caulobacter crescentus, Yersinia, Synechocystis, Leishmania, Plasmodium falciparum, Entamoeba histolytica, etc.), and focus also at the microbial proteins affecting directly or indirectly the PTPs of the host (Mycobacterium tuberculosis MTSA-10, Bacillus anthracis anthrax toxin, streptococcal ß protein, Helicobacter pylori CagA and VacA, Leishmania GP63 and EF-1α, Plasmodium hemozoin, etc.). This is the first review summarizing the knowledge on biological activity and pharmacological inhibition of non-metazoan PTPs, with the emphasis of those important in host-pathogen interactions. Targeting of numerous non-metazoan PTPs is simplified by the fact that they act either as ectophosphatases or are secreted outside of the pathogen. Interfering with tyrosine phosphorylation represents a powerful pharmacologic approach, and even though the PTP inhibitors are difficult to develop, lifting the fog of phosphatase inhibition is of the great market potential and further clinical impact.