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Objective: Inappropriate handling of cells can generate modifications in the genomic DNA. The additional risk is cross-contamination. Isoenzyme analysis with gel agarose electrophoresis is a known, fast, and cheap technique for detection of species-specific isoforms of intracellular enzymes. The aim of the experimental work was to check if variations in the cell growth conditions can affect morphology and/or nuclear anomalies including micronuclei (MN) in the L929 cells; and to define how sensitive and selective is the classic gel agarose electrophoresis for analysis of isoforms of the selected enzymes to detect cross-contamination of L929 cultures with HeLa cells or with the related species, such as CHO-K1 cells, in the case of unavailability of the commercial kits. Methods: The experiments were done with use of the National Collection of Type Cultures clone 929 (L929)-mouse fibroblasts from subcutaneous connective tissue; HeLa-human cervix adenocarcinoma; and CHO-K1-epithelial-like hamster ovary cells. Cell morphology was evaluated with a light/fluorescence microscope. MN were determined with the cytokinesis-block micronucleus assay, and the isoenzyme analysis was performed using gel agarose electrophoresis. Results: As shown, the overgrown cultures result in a significant increase of the MN in the L929 cells. The band patterns for lactate dehydrogenate, glucose-6-phosphate dehydrogenase, or malate dehydrogenase allow identification of the single L929, HeLa, or CHO-K1 cell line and to detect the cross-contamination, even up to 0.4%. Conclusions: There can be no exceptions from the recommended cell culture conditions in the passage scheme. The sensitivity of the gel agarose separation depends on the cells and on the type of enzyme tested and seems to be sufficient in a quick screening of the CHO-K1, L929, or HeLa cell cultures through the possible mutual contamination.

Vitamin C has a number of acitvities that could contribute to its immune-modulating effects. The only question is whether we should provide ourselves with only the right level of it, or do we need much more during a pandemic? The possibility of reducing the incidence of viral diseases in a well-nourished population through the use of dietary supplements based on vitamin C is not supported in the literature. Despite this, the belief that an extra intake of vitamin C can increase the efficacy of the immune system is still popular and vitamin C is advertised as a remedy to prevent infectious disease. This article refers to the justification of the use of vitamin C in high doses as an anti-SARS-CoV-2 prophylaxis in healthy subjects. Does it make sense or not? As it turns out, any effects of vitamin C supplementation may be more prominent when the baseline vitamin C level is low, for example in physically active persons. People with hypovitaminosis C are more likely to respond to vitamin C administration. No studies regarding prevention of COVID-19 with high-dose vitamin C supplementation in healthy subjects were found.

The MN a (in vitro the micronucleus assay) is recommended for studying genotoxicity of chemicals. However, no protocol is currently available for experiments with mouse fibroblast L929 cells. The aim of this study was to improve the scope of CBMN b (cytokinesis-block micronucleus) test. Optimization consisted of: selection of a non-cytotoxic concentration of cytokinesis blocker - cytoB c (cytochalasin B) and type and definition of the positive controls, verification of the efficacy of phenobarbital/5,6-benzoflavone as an S9 enzyme inducer as well as the identification of an optimal staining method. The compounds were tested in three exposure regimens: 6 h exposure with S9 activation followed by a 24 h recovery period, 6 h exposure followed by a 24 h recovery without metabolic activation of S9 and 30 h continuous exposure without S9. Different parameters, such as internal and interlaboratory reproducibility were investigated and criteria for test correctness were proposed. Higher MN rates were achieved using 1 μg/mL cytoB c as a cytokinesis blocker, and MMS d (methyl methanesulfonate), (250 μM), Col e (colchicine), (0.5 μM) and CP f (cyclophosphamide), (30 μM) as positive controls. In regard to the recommended S9 inducer, phenobarbital/5,6-benzoflavone was more effective as Aroclor 1254. Giemsa and acridine orange stains were optimal for the evaluation of MN formation. The protocol described in this study with L929 cells produced the reliable results and is suitable for performing the CBMN b experiments according to the current OECD Guideline #487., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Vitamin D generates many extraskeletal effects due to the vitamin D receptor (VDR) which is present in most tissues throughout the body. The possible role of vitamin D in infections is implied from its impact on the innate and adaptive immune responses. A significant effect is also the suppression of inflammatory processes. Because vitamin D could be acknowledged as a "seasonal stimulus", as defined by R. Edgar Hope-Simpson, it would be crucial to prove it from a potential easy and cheap prophylaxis or therapy support perspective as far as influenza infections are concerned. The survey of the literature data generates some controversies and doubts about the possible role of vitamin D in the prevention of influenza virus. The most important point is to realise that the broad spectrum of this vitamin's activity does not exclude such a possibility. According to most of the authors, more randomized controlled trials with effective, large populations are needed to explore the preventive effect of vitamin D supplementation on viral influenza infections., Competing Interests: The author declares no conflict of interest.

Background: Oxidative stress accompanies neurodegeneration and also causes abnormalities in thiaminedependent processes. These processes have been reported to be diminished in the brains of patients with several neurodegenerative diseases., Objectives: The aim of this work was to conduct a comparative analysis of the impact of supplemented thiamine on the viability of human B lymphocytes with CAG abnormal expanded huntingtin gene (mHTT) (GM13509) and control, B lymphocytes without mHTT (GM14467) through the following studies: determination of the supplemented thiamine concentrations, which are effective for cell growth stimulation after incubation in thiamine deficit conditions; determination of cell capability to intake the exogenous thiamine; evaluation of exogenous thiamine influence on the profile of the genes related to thiamine and energy metabolism; determination of ATP synthesis and activities of thiamine-dependent enzymes, KGDHC and BCKDHC in the intact cells and upon the exogenous thiamine., Material and Methods: The following methods were used: EZ4U test for cell growth analysis; HPLC for determination of thiamine intake and ATP synthesis, qRT-PCR for evaluation of the gene profiles and spectrophotometric method for KGDHC and BCKDHC activities determination., Results: Maximal cell growth stimulation was observed at 2.5 mM in GM14467 up to 135% of the control culture and at 5.0 mM in GM13509 cells up to 165% of the control culture. Native levels of total ATP and KGDHC and BCKDHC activities in both cell types were comparable and did not changed upon thiamine deficit or supplementation. GM13509 cells showed more of an increase in growth stimulation upon thiamine supplementation than GM14467 cells and this effect was reflected in the increase of intracellular thiamine concentration., Conclusions: The above results and reported changes in expression of GAPDH, IDH1 and SLC19A3 genes observed upon thiamine deficit conditions suggest that intracellular thiamine status and energy metabolism can have a role in HD pathogenesis.

According to the Polish Ministry of Health decree, the medical devices and all raw materials used for their manufacturing are in force to be compatible with biological tissues, cells and body fluids regarding its clinical use. It is defined as biocompatibility. The scope of the methods proposed in the norm PN-EN ISO 10993-1 makes possible to get full preclinical characteristics of the medical device and allows to form the opinion about safety of it to the patients after its marketing. The test directed as the principal to make, independently on characteristics, kind, contact duration and clinical use of the device is cytotoxicity in vitro. This test defines the impact of the device on the cells through microscopic evaluation or through activities of the enzymes specific for living cells. Toxicity of the material to the cells may be reflected in: change of single cells or whole cell culture morphology, change of cellular metabolic activity, DNA damage or disadvantage of cell proliferation. Biocompatibility of the medical devices is one of the main elements considered in a risk management process at the stage of designing and manufacturing as well of the raw materials as the final product and the critical point in this matter is sterilization.

The pleiotropism of vitamin D is due to the presence of vitamin D receptor in the cells of nearly all tissues and organs within the human body, including the CNS. Multiple evidence is available to support neuroprotective properties of vitamin D. These include, for example, the presence of 25(OH)D-lot-hydroxylase, an enzyme responsible for production of calcitriol, within the human brain. Among its other activities, calcitriol modifies production and release of neurotrophic factors, affects expression of genes associated with GABAergic signaling and stimulates biosynthesis of catecholamines. Antioxidative and anti-inflammatory properties were also demonstrated in research studies. By confronting the known pathomechanisms of Alzheimer's disease (AD) and the mechanism of action of vitamin D, one may propose that systemic insufficiency of vitamin D is a potential risk factor of AD. Studies conducted to date confirm the inverse relationship between serum calcidiol levels and the risk of dementia diseases, including AD. Elevated cerebrospinal fluid level of VDBP, a vitamin D binding protein that is also responsible for elimination of P-amyloid peptide (AP), a pathogenic factor characteristic for AD, is considered to be a potential marker of AD. Reduction in AP levels within the CNS is the most important therapeutic target in the treatment of AD. Animal studies confirmed the impact of vitamin D-enriched diet on the reduction in amyloid deposits, AP peptide levels and inflammatory reactions as well as on the increase in the level of neurotrophic factor within the brains of AP protein precursor (APPP) - transgenic mice. In case of AD, the purposefulness of initiating treatment before the onset of clinical symptoms is being highlighted. Vitamin D is worth consideration since by inducing the expression of VDR gene it leads, among others, to the silencing of the transcription of the gene encoding the AOAPP and thus inhibits its cleavage into peptides that form amyloid deposits. Despite the fact that at current state vitamin D can hardly be considered a therapeutic agent with an established efficient dose in AD, authors of studies suggest that it is important in AD prophylaxis in elderly patients with age-related reduction of serum calcidiol lev- els.