PURPOSE: The complex relationship between linear energy transfer (LET) and cellular response to radiation is not yet fully elucidated. To better characterize DNA damage after irradiations with therapeutic protons, we monitored formation and disappearance of DNA double-strand breaks (DNA DSB) as a function of LET and time. Comparisons with conventional γ-rays and high LET carbon ions were also performed. MATERIALS AND METHODS: In the present work, we performed immunofluorescence-based assay to determine the amount of DNA DSB induced by different LET values along the 62 MeV therapeutic proton Spread out Bragg peak (SOBP) in three cancer cell lines, i.e. HTB140 melanoma, MCF-7 breast adenocarcinoma and HTB177 non-small lung cancer cells. Time dependence of foci formation was followed as well. To determine irradiation positions, corresponding to the desired LET values, numerical simulations were carried out using Geant4 toolkit. We compared γ-H2AX foci persistence after irradiations with protons to that of γ-rays and carbon ions. RESULTS: With the rise of LET values along the therapeutic proton SOBP, the increase of γ-H2AX foci number is detected in the three cell lines up to the distal end of the SOBP, while there is a decrease on its distal fall-off part. With the prolonged incubation time, the number of foci gradually drops tending to attain the residual level. For the maximum number of DNA DSB, irradiation with protons attain higher level than that of γ-rays. Carbon ions produce more DNA DSB than protons but not substantially. The number of residual foci produced by γ-rays is significantly lower than that of protons and particularly carbon ions. Carbon ions do not produce considerably higher number of foci than protons, as it could be expected due to their physical properties. CONCLUSIONS: In situ visualization of γ-H2AX foci reveal creation of more lesions in the three cell lines by clinically relevant proton SOBP than γ-rays. The lack of significant differences in the number of γ-H2AX foci between the proton and carbon ion-irradiated samples suggests an increased complexity of DNA lesions and slower repair kinetics after carbon ions compared to protons. For all three irradiation types, there is no major difference between the three cell lines shortly after irradiations, while later on, the formation of residual foci starts to express the inherent nature of tested cells, therefore increasing discrepancy between them.
- MeSH
- DNA Breaks, Double-Stranded radiation effects MeSH
- Humans MeSH
- Linear Energy Transfer * MeSH
- Cell Line, Tumor MeSH
- DNA Repair radiation effects MeSH
- Protons * MeSH
- Relative Biological Effectiveness MeSH
- Cell Survival radiation effects MeSH
- Dose-Response Relationship, Radiation MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
Natural killer (NK) cells are a family of lymphocytes with a natural ability to kill infected, harmed, or malignantly transformed cells. As these cells are part of the innate immunity, the cytotoxic mechanisms are activated upon recognizing specific patterns without prior antigen sensitization. This recognition is crucial for NK cell function in the maintenance of homeostasis and immunosurveillance. NK cells not only act directly toward malignant cells but also participate in the complex immune response by producing cytokines or cross-talk with other immune cells. Cancer may be seen as a break of all immune defenses when malignant cells escape the immunity and invade surrounding tissues creating a microenvironment supporting tumor progression. This process may be reverted by intervening immune response with immunotherapy, which may restore immune recognition. NK cells are important effector cells for immunotherapy. They may be used for adoptive cell transfer, genetically modified with chimeric antigen receptors, or triggered with appropriate antibodies and other antibody-fragment-based recombinant therapeutic proteins tailored specifically for NK cell engagement. NK cell receptors, responsible for target recognition and activation of cytotoxic response, could also be targeted in immunotherapy, for example, by various bi-, tri-, or multi-specific fusion proteins designed to bridge the gap between tumor markers present on target cells and activation receptors expressed on NK cells. However, this kind of immunoactive therapeutics may be developed only with a deep functional and structural knowledge of NK cell receptor: ligand interactions. This review describes the recent developments in the fascinating protein-engineering field of NK cell immunotherapeutics.
- MeSH
- Antineoplastic Agents * MeSH
- Killer Cells, Natural pathology MeSH
- Receptors, Chimeric Antigen * therapeutic use MeSH
- Immunologic Factors MeSH
- Immunotherapy, Adoptive MeSH
- Immunotherapy MeSH
- Humans MeSH
- Tumor Microenvironment MeSH
- Neoplasms * MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Review MeSH
Recently, the problem of viral infection, particularly the infection with herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2), has dramatically increased and caused a significant challenge to public health due to the rising problem of drug resistance. The antiherpetic drug resistance crisis has been attributed to the overuse of these medications, as well as the lack of new drug development by the pharmaceutical industry due to reduced economic inducements and challenging regulatory requirements. Therefore, the development of novel antiviral drugs against HSV infections would be a step forward in improving global combat against these infections. The incorporation of biologically active natural products into anti-HSV drug development at the clinical level has gained limited attention to date. Thus, the search for new drugs from natural products that could enter clinical practice with lessened resistance, less undesirable effects, and various mechanisms of action is greatly needed to break the barriers to novel antiherpetic drug development, which, in turn, will pave the road towards the efficient and safe treatment of HSV infections. In this review, we aim to provide an up-to-date overview of the recent advances in natural antiherpetic agents. Additionally, this paper covers a large scale of phenolic compounds, alkaloids, terpenoids, polysaccharides, peptides, and other miscellaneous compounds derived from various sources of natural origin (plants, marine organisms, microbial sources, lichen species, insects, and mushrooms) with promising activities against HSV infections; these are in vitro and in vivo studies. This work also highlights bioactive natural products that could be used as templates for the further development of anti-HSV drugs at both animal and clinical levels, along with the potential mechanisms by which these compounds induce anti-HSV properties. Future insights into the development of these molecules as safe and effective natural anti-HSV drugs are also debated.
- MeSH
- Antiviral Agents chemistry pharmacology MeSH
- Biological Products chemistry pharmacology MeSH
- Drug Industry MeSH
- Humans MeSH
- Herpesvirus 1, Human drug effects MeSH
- Herpesvirus 2, Human drug effects MeSH
- Drug Discovery * MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
- Review MeSH
Lidská výživa se skládá ze tří základních složek: sacharidů, lipidů a proteinů. Sacharidy přitom tvoří až 60 % a většina z tohoto množství je přijímána ve formě škrobů. Trávicí systém štěpí tento polysacharid pomocí enzymů – amyláz a glukozidáz – až na glukózu, která je základním zdrojem energie pro živočišné buňky. Inhibicí amyláz a glukosidáz se snižuje biologická dostupnost glukózy a dochází k redukci postprandiální hyperglykemie (zvýšené množství glukózy v krvi po jídle). Tyto inhibitory mohou hrát významnou úlohu při diagnostice a léčbě cukrovky a obezity. Látky s tímto účinkem se vyskytují i v některých rostlinách a v poslední době jsou předmětem intenzivního výzkumu.
Human nutrition consists of three main components: saccharides, lipids, and proteins. Saccharides account for as much as 60 percent and most of this amount comes in the form of starches. By using enzymes (amylases and glucosidases), the digestive system breaks down this polysaccharide into glucose which is the basic source of energy for animal cells. The inhibition of amylases and glucosidases decreases the biological availability of glucose, thus reducing postprandial hyperglycaemia (elevated blood glucose after a meal). These inhibitors may play a significant role in diagnosing and treatment of diabetes and obesity. Substances having this effect are also found in certain plants and have been intensively studied recently.
- MeSH
- alpha-Amylases antagonists & inhibitors MeSH
- alpha-Glucosidases MeSH
- Alkaloids pharmacology MeSH
- Pinus MeSH
- Diabetes Mellitus drug therapy MeSH
- Financing, Organized MeSH
- Hibiscus MeSH
- Hyperglycemia MeSH
- Glycoside Hydrolase Inhibitors MeSH
- Humans MeSH
- Morus MeSH
- Obesity drug therapy MeSH
- Postprandial Period physiology drug effects MeSH
- Plant Extracts pharmacology MeSH
- Check Tag
- Humans MeSH
- Publication type
- Review MeSH
Hereditary mutations in polynucleotide kinase-phosphatase (PNKP) result in a spectrum of neurological pathologies ranging from neurodevelopmental dysfunction in microcephaly with early onset seizures (MCSZ) to neurodegeneration in ataxia oculomotor apraxia-4 (AOA4) and Charcot-Marie-Tooth disease (CMT2B2). Consistent with this, PNKP is implicated in the repair of both DNA single-strand breaks (SSBs) and DNA double-strand breaks (DSBs); lesions that can trigger neurodegeneration and neurodevelopmental dysfunction, respectively. Surprisingly, however, we did not detect a significant defect in DSB repair (DSBR) in primary fibroblasts from PNKP patients spanning the spectrum of PNKP-mutated pathologies. In contrast, the rate of SSB repair (SSBR) is markedly reduced. Moreover, we show that the restoration of SSBR in patient fibroblasts collectively requires both the DNA kinase and DNA phosphatase activities of PNKP, and the fork-head associated (FHA) domain that interacts with the SSBR protein, XRCC1. Notably, however, the two enzymatic activities of PNKP appear to affect different aspects of disease pathology, with reduced DNA phosphatase activity correlating with neurodevelopmental dysfunction and reduced DNA kinase activity correlating with neurodegeneration. In summary, these data implicate reduced rates of SSBR, not DSBR, as the source of both neurodevelopmental and neurodegenerative pathology in PNKP-mutated disease, and the extent and nature of this reduction as the primary determinant of disease severity.
- MeSH
- Apraxias genetics pathology MeSH
- Charcot-Marie-Tooth Disease genetics pathology MeSH
- DNA Breaks, Double-Stranded * MeSH
- DNA Repair Enzymes genetics MeSH
- Fibroblasts metabolism pathology MeSH
- Phosphotransferases (Alcohol Group Acceptor) genetics MeSH
- DNA Breaks, Single-Stranded * MeSH
- Humans MeSH
- Microcephaly genetics pathology MeSH
- Mutation genetics MeSH
- DNA Repair genetics MeSH
- X-ray Repair Cross Complementing Protein 1 genetics MeSH
- Seizures genetics pathology MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
This study presents a simple, label-free electrochemical technique for the monitoring of DNA ligase activity. DNA ligases are enzymes that catalyze joining of breaks in the backbone of DNA and are of significant scientific interest due to their essential nature in DNA metabolism and their importance to a range of molecular biological methodologies. The electrochemical behavior of DNA at mercury and some amalgam electrodes is strongly influenced by its backbone structure, allowing a perfect discrimination between DNA molecules containing or lacking free ends. This variation in electrochemical behavior has been utilized previously for a sensitive detection of DNA damage involving the sugar-phosphate backbone breakage. Here we show that the same principle can be utilized for monitoring of a reverse process, i.e., the repair of strand breaks by action of the DNA ligases. We demonstrate applications of the electrochemical technique for a distinction between ligatable and unligatable breaks in plasmid DNA using T4 DNA ligase, as well as for studies of the DNA backbone-joining activity in recombinant fragments of E. coli DNA ligase.
- Publication type
- Meeting Abstract MeSH
Počet kroků, které urazí denně zdraví dospělí lidé, se pohybuje mezi 4000 a 18 000. Adaptačním podnětem však není jen celkový objem kroků, ale také intenzita, tedy frekvence kroků. Ta se pohybuje v rozmezí 64 až 170 kroků za minutu. Řada autorů se shoduje, že za optimální zátěž střední intenzity lze považovat chůzi o frekvenci kroků 100 za minutu. Ta odpovídá intenzitě 3 METs a pro netrénované osoby s nízkou zdatností představuje zátěž střední intenzity. Pro zdatnější však intenzita zátěže musí být větší, a tedy jsou vhodné i jiné formy pohybové aktivity než pouhá chůze (džogink, plavání, kolo, běžky aj.). Půlhodina touto frekvencí kroků znamená v denní bilanci přídavek 3000 kroků denně, a to by obvykle mělo naplnit doporučení na 7000 až 11 000 kroků denně. V prevenci rizik souvisejících s každodenní přemírou nepřetržitého sezení, se doporučuje alespoň každých 30 minut sezení přerušit a po dobu 2-5 minut se věnovat pohybové aktivitě - sem patří chůze či jednoduché průpravné cviky dolními končetinami, případně zašlapání na ergometru, je-li k dispozici. Dostatek chůze by tak měl být základním pohybovou aktivitou každého člověka, další formy PA by měly zdravotní účinek PA jako součásti životního stylu jen dále podpořit.
It appears that healthy adults can take anywhere between approximately 4,000 and 18,000 steps/day. However, not only total number of steps/day is important to evoke adaptive response, but results of controlled studies of treadmill and over-ground walking demonstrate that there is between 64-170 steps/minute. 10,000 steps/day is a reasonable target for healthy adults. It seems that 100 steps/minute represents a reasonable value (i.e. 3 METs and more) that can be useful as a recommendable level of moderate intensity walking. For subjects who obtain higher fitness level the intensity of daily physical activity must be also higher - using suitable other forms of physical activity (jogging, swimming, biking, cross-country skiing etc.). 30 minutes walking on that cadence requires a minimum of 3,000 steps. Added to usual daily number of steps recommended equivalent of 7,000 to 11,000 steps/day could be easily accomplished. To avoid the adverse health consequences, related to everyday excess of continuous sitting it is recommended that seated-based work should be regularly broken up for 2 to 5 minutes with standing-based work, the use of sit-stand desks, or the taking of short active exercise breaks every 30 minutes.
Magnetorheological elastomer (MRE) materials have the potential to be used in a wide range of applications that require long-term service in hostile environments. These widespread applications will result in the emergence of MRE-specific durability issues, where durability refers to performance under in-service environmental conditions. In response, the outdoor tropical climatic environment, combined with the effects of weathering, will be the primary focus of this paper, specifically the photodegradation of the MRE. In this study, MRE made of silicone rubber (SR) and 70 wt% micron-sized carbonyl iron particles (CIP) were prepared and subjected to mechanical and rheological testing to evaluate the effects under natural weathering. Magnetorheological elastomer samples were exposed to the natural weathering conditions of a tropical climate in Kuala Lumpur, Malaysia, for 30 days. To obtain a comprehensive view of MRE degradation during natural weathering, mechanical testing, rheology, and morphological evaluation were all performed. The mechanical and rheological properties test results revealed that after 30 days of exposure and known meteorological parameters, Young's modulus and storage modulus increased, while elongation at break decreased. The degradation processes of MRE during weathering, which are responsible for their undesirable change, were given special attention. With the help of morphological evidence, the relationship between these phenomena and the viscoelastic properties of MRE was comprehensively defined and discussed.
- MeSH
- Elastomers * MeSH
- Weather MeSH
- Rheology MeSH
- Silicone Elastomers MeSH
- Tropical Climate * MeSH
- Publication type
- Journal Article MeSH
