Hamster Cells Research Articles

Antimicrobial activity, toxicity and accumulated hard-tissue debris (AHTD) removal efficacy of several chelating agents.

To evaluate the antimicrobial, toxicity and cleaning effectiveness of ethylenediaminetetraacetic acid (EDTA) and maleic acid (MA) alone and combined with cetrimide (CTR). Cytotoxic and genotoxic effects were assessed on Chinese hamster cells V79 using the MTT, clonogenic and micronucleus assays, respectively. The bacterial inhibitory and bactericidal concentrations (MIC and MBC, respectively) were determined on a strain of Enterococcus faecalis. Antimicrobial tests were performed on a biofilm model after treatment with the chelating agents by using a biofilm eradication concentration (MBEC) and confocal laser scanning microscope (CLSM) assays. Quantification of cell biomass and percentage of live and dead cells in the biomass were assessed for each group. The percentage reduction of accumulated hard-tissue debris (AHTD) after root canal preparation and final irrigation protocols was evaluated by micro-CT. Statistical tests of one-way analysis of variance (anova), Bonferroni test, Kruskal-Wallis test, Dunn's multiple comparison test and Wilcoxon matched-pairs signed-rank tests were used. Cetrimide alone as well as in combination with EDTA and MA at dilutions of 1/10 and 1/100 was significantly more toxic as compared to untreated controls (P<0.001). All tested mixtures were nontoxic at a dilution of 1/1000. EDTA retained a weak inhibitory and bactericidal effect against planktonic cells, whilst MA inhibited cells growth and killed 99.9% of the cells when diluted. CTR revealed the most prominent effect, being inhibitory and bactericidal, also when diluted. Cetrimide alone or combined with EDTA was able to remove, respectively, 40% (P<0.01) and 60% (P<0.001) of the entire biomass after 1min. Conversely, MA alone and in combination with CTR did not have a significant effect on biomass reduction. After final irrigation, the AHTD volume was significantly decreased in all groups (P<0.05). EDTA+CTR and MA+CTR were associated with a significant reduction in the percentage of AHTD on the entire root canal compared to the same solutions without surfactant. 7% MA was less cytotoxic in comparison with 17% EDTA. The addition of cetrimide to EDTA and MA removed accumulated hard-tissue debris effectively from the canal walls and increased their antimicrobial activity when compared to the same solutions without detergents.

Effects of Titanium Dioxide Nanoparticles on the Hprt Gene Mutations in V79 Hamster Cells.

The genotoxicity of anatase/rutile TiO2 nanoparticles (TiO2 NPs, NM105 at 3, 15 and 75 µg/cm2) was assessed with the mammalian in-vitro Hypoxanthine guanine phosphoribosyl transferase (Hprt) gene mutation test in Chinese hamster lung (V79) fibroblasts after 24 h exposure. Two dispersion procedures giving different size distribution and dispersion stability were used to investigate whether the effects of TiO2 NPs depend on the state of agglomeration. TiO2 NPs were fully characterised in the previous European FP7 projects NanoTEST and NanoREG2. Uptake of TiO2 NPs was measured by transmission electron microscopy (TEM). TiO2 NPs were found in cytoplasmic vesicles, as well as close to the nucleus. The internalisation of TiO2 NPs did not depend on the state of agglomeration and dispersion used. The cytotoxicity of TiO2 NPs was measured by determining both the relative growth activity (RGA) and the plating efficiency (PE). There were no substantial effects of exposure time (24, 48 and 72 h), although a tendency to lower RGA at longer exposure was observed. No significant difference in PE values and no increases in the Hprt gene mutant frequency were found in exposed relative to unexposed cultures in spite of evidence of uptake of NPs by cells.

Repair of DNA damage induced by the novel nucleoside analogue CNDAG through homologous recombination.

We postulate that the deoxyguanosine analogue CNDAG [9-(2-C-cyano-2-deoxy-1-β-D-arabino-pentofuranosyl)guanine] likely causes a single-strand break after incorporation into DNA, similar to the action of its cytosine congener CNDAC, and that subsequent DNA replication across the unrepaired nick would generate a double-strand break. This study aimed at identifying cellular responses and repair mechanisms for CNDAG prodrugs, 2-amino-9-(2-C-cyano-2-deoxy-1-β-D-arabino-pentofuranosyl)-6-methoxy purine (6-OMe) and 9-(2-C-cyano-2-deoxy-1-β-D-arabino-pentofuranosyl)-2,6-diaminopurine (6-NH2). Each compound is a substrate for adenosine deaminase, the action of which generates CNDAG. Growth inhibition assay, clonogenic survival assay, immunoblotting, and cytogenetic analyses (chromosomal aberrations and sister chromatid exchanges) were used to investigate the impact of CNDAG on cell lines. The 6-NH2 derivative was selectively potent in T cell malignant cell lines. Both prodrugs caused increased phosphorylation of ATM and its downstream substrates Chk1, Chk2, SMC1, NBS1, and H2AX, indicating activation of ATM-dependent DNA damage response pathways. In contrast, there was no increase in phosphorylation of DNA-PKcs, which participates in repair of double-strand breaks by non-homologous end-joining. Deficiency in ATM, RAD51D, XRCC3, BRCA2, and XPF, but not DNA-PK or p53, conferred significant clonogenic sensitivity to CNDAG or the prodrugs. Moreover, hamster cells lacking XPF acquired remarkably more chromosomal aberrations after incubation for two cell cycle times with CNDAG 6-NH2, compared to the wild type. Furthermore, CNDAG 6-NH2 induced greater levels of sister chromatid exchanges in wild-type cells exposed for two cycles than those for one cycle, consistent with increased double-strand breaks after a second S phase. CNDAG-induced double-strand breaks are repaired mainly through homologous recombination.

Molecular Diversity from Arid‐Land Plants: Valorization of Terpenes and Biotransformation Products

Asteraceae plants from arid lands are a source of biomass, resin and latex rich in terpenoids with diverse biological effects. Thirty-six previously isolated terpenes, comprising sesquiterpenes, diterpenes, triterpenes and quassinoids, isolated from arid-land plants and a series of metabolites from the biotransformation of some lead compounds were evaluated against insect pests (Spodoptera littoralis, Leptinotarsa decemlineata, Myzus persicae and Rhopalosiphum padi), cells (insect, hamster, murine and human tumoral cells) and parasites (Trypanosoma cruzi and Leishmania infantum). Among the insecticidal sesquiterpenes, maalian-1α,8α-diol (12) and γ-eudesmol (17) were antifeedant against L. decemlineata, M. persicae and cytotoxic to Sf9 insect cells, and (-)-maali-3-en-8α-ol (10), (+)-maaliane-5α,8α,9α-triol (11), chrysothame (31) and holacanthone (35) were antifeedant against S. littoralis. The parasite L. infantum was slightly more sensitive than T. cruzi to the test compounds (39 % vs. 33 % of active compounds) with compound 17 and the biotransformed diterpene 27 being antiparasitic to L. infantum, with no cytotoxic effects on mammalian cells. Moreover, sesquiterpenes 3 and 17, and grindelane diterpenes 22, 23 and 26 showed selective activity against chemoresistant human colon, cervical and melanoma cancer cells. Thus, considering our results, the best candidates for future studies are compounds 17 and 3, due to their activity on insect pests, parasites (17) and tumoral cells (3, 17, 22, 23 and 26).

In vivo and in vitro analysis of cytogenotoxicity in populations living in abnormal conditions from Santos-Sao Vicente estuary.

The aim of the study was to evaluate cyto- and genotoxic effects in populations living in subnormal clusters in Santos São Vicente estuary. For in vivo study, samples of buccal mucosa and peripheral blood cells were collected. Micronucleus assay and single-cell gel (comet) assay were performed. For in vitro study, Chinese ovary hamster (CHO) cells were exposed to contaminated water. The results showed that people living in the contaminated estuary have increased DNA damage in oral mucosa and peripheral blood cells, as detected in the micronucleus and comet assays respectively. In addition, estuarine water was able to promote cytotoxicity at the highest concentrations, as well as decrease the number of cells in the G1 phase. In summary, our results indicate that water from the Santos-São Vicente estuary is capable of inducing cytogenotoxicity in mammalian cells in vivo and in vitro.

Gene (HPRT) and chromosomal (MN) mutations of nickel metal powder in V79 Chinese hamster cells

Nickel metal is a naturally occurring element used in many industrial and consumer applications. Human epidemiological data and animal cancer bioassays indicate that nickel metal is not likely to be a human carcinogen. Yet, nickel metal is classified as a suspected human carcinogen (CLP) and possibly carcinogenic to humans (IARC). There are no reliable studies on the potential for nickel metal to induce gene and micronucleus (MN) mutations. To fill these datagaps and increase our understanding of the mechanisms underlying the lack of nickel metal carcinogenicity, gene and micronucleus mutation studies were conducted with nickel metal powder (N36F) in V79 Chinese Hamster cells following OECD 476 and 487 guidelines, respectively, under GLP. Gene mutation at the hprt locus was tested, with and without metabolic activation, after 4-h treatment with 0.05–2.5 mM nickel metal powder. Cytokinesis-block MN frequency following exposure to 0.25–1.5 mM nickel metal was tested after 4-h treatment, with and without metabolic activation, followed by a 24-h treatment without metabolic activation. In the gene mutation assay, there were modest increases in hprt mutants observed at some test concentrations, not exceeding 2.2-fold, which were either within the historical control values and/or showed no concentration-response trend. The positive controls showed increases of at least 7-fold. Likewise, no increases in the MN frequency exceeding 1.5-fold were observed with nickel metal, with no concentration-response trends. Taking these results together, it can be concluded that nickel metal is non-mutagenic and does not cause gene nor chromosomal mutations.

Toxicity and Anti-promastigote Activity of Benzoxazinoid Analogs Against Leishmania (Viannia) braziliensis and Leishmania (Leishmania) infantum.

Purpose: Here, we aim to evaluate the antileishmanial activity of compounds with a benzoxazinoid (BX) skeleton, previously synthesized by our group, against Leishmania (Viannia) braziliensis and Leishmania (Leishmania) infantum promastigotes. Methods: Anti-promastigote activity, as well as cytotoxicity, were determined using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) colorimetric assays. The selectivity index (SI) for each compound was calculated using a ratio of the cytotoxicity of compounds and the geometric mean (GM) of antileishmanial concentrations to each species tested. The comparisons between groups were carried out using a t test or analysis of variance (one-way ANOVA). A P value of less than 0.05 was considered significant. Results: All the compounds tested were active, with IC50 falling between 92±6.19 µg/mL and 238±6.57 µg/mL for L. braziliensis, and 89±6.43 µg/mL and 188±3.58 µg/mL against L. infantum. Bex2, Bex3, Pyr1, Pyr2, and Pyr4 were compounds that showed activity similar to the drug Glucantime®, exhibited low cytotoxicity against splenic hamster cells (CC50 raging between >400 and 105.7±2.26 µg/mL) and had favorable selectivity indices (SI 1.12 to 3.96). Conclusion: The analogs in question are promising prototypes for the pharmaceutical development of novel, safer and more effective leishmanicidal agents.

ERCC1 C8092A polymorphism predicts fair survival outcome in Japanese patients with pharyngo-laryngeal squamous cell carcinoma.

To evaluate the prognostic significance of DNA excision repair gene polymorphisms, excision repair cross-complementation group 1 (ERCC1) and X-ray repair complementing defective repair in Chinese hamster cells 1 (XRCC1) polymorphisms were investigated in Japanese patients with head and neck squamous cell carcinoma (HNSCC). A total of 225 consecutive patients with HNSCC who underwent surgery or chemoradiotherapy/radiotherapy (CRT/RT) with curative intent as primary treatment from 2006 to 2017 were recruited. ERCC1 C8092A and XRCC1 Arg399Gln polymorphisms in DNA extracted from individual blood samples were determined by the polymerase chain reaction-restriction fragment length polymorphism method. Cumulative survival was estimated by Kaplan-Meier analysis with a log-rank test and Cox proportional hazards model stratified by treatment arm, adjusting for clinical prognostic factors. Multivariate analysis showed that carriers with the ERCC1 8092 (C/A+A/A) genotype (hazard ratio, 3.56; 95% confidence interval, 1.22-7.39; p = 0.02) had significantly worse survival than those with ERCC1 8092 C/C who received CRT/RT. Conversely, the XRCC1 Arg399Gln polymorphism did not influence survival in patients who received CRT/RT as well as surgery. The ERCC1 C8092A polymorphism might be an independent predictor of response to CRT and survival outcome in patients with HNSCC. This is the first report to investigate the role of DNA excision repair gene polymorphisms in patients with head and neck cancer in a Japanese population.

The Golgi Apparatus of Neocortical Glial Cells During Hibernation in the Syrian Hamster.

Hibernating mammals undergo torpor periods characterized by a general decrease in body temperature, metabolic rate, and brain activity accompanied by complex adaptive brain changes that appear to protect the brain from extreme conditions of hypoxia and low temperatures. These processes are accompanied by morphological and neurochemical changes in the brain including those in cortical neurons such as the fragmentation and reduction of the Golgi apparatus (GA), which both reverse a few hours after arousal from the torpor state. In the present study, we characterized – by immunofluorescence and confocal microscopy – the GA of cortical astrocytes, oligodendrocytes, and microglial cells in the Syrian hamster, which is a facultative hibernator. We also show that after artificial induction of hibernation, in addition to neurons, the GA of glia in the Syrian hamster undergoes important structural changes, as well as modifications in the intensity of immunostaining and distribution patterns of Golgi structural proteins at different stages of the hibernation cycle.

Inhibitor Development with Simoctocog Alfa in Previously Untreated Patients with Severe Haemophilia a: Final Results of the Nuprotect Study

Introduction FVIII inhibitor development is the greatest challenge when treating previously untreated patients (PUPs) with hemophilia A (HA). The SIPPET study reported a cumulative inhibitor incidence of 44.5% (28.4% high-titre) in PUPs treated with recombinant FVIII (rFVIII) products produced in hamster cell lines and 26.8% (18.6% high-titre) with plasma-derived FVIII products containing von Willebrand factor (pdFVIII/VWF). Simoctocog alfa (Nuwiq®) is a 4th generation rFVIII produced in a human cell line without chemical modification or protein fusion. The NuProtect study assessed the immunogenicity, efficacy and safety of simoctocog alfa in PUPs with severe HA. A prespecified interim analysis was published with data up to 20 and 50 EDs (Haemophilia 2018; 24:211) and here we report the final results. Methods NuProtect was a prospective, multinational, open-label, non-controlled, phase III study. True PUPs (no prior FVIII treatment) with severe HA of any age and ethnicity were to be enrolled and treated for 100 exposure days (EDs) or a maximum of 5 years with simoctocog alfa for prophylaxis, on-demand treatment, treatment of breakthrough bleeding episodes (BEs) and surgical prophylaxis. Type of treatment and dose were determined by the investigator. Inhibitor screening (modified Bethesda assay) was performed at screening, every 3-4 EDs until ED20, then every 10-12 EDs or at least every 3 months, at completion, and if inhibitor development was suspected. Inhibitor levels of ≥0.6 to &amp;lt;5 Bethesda units [BU]/mL were defined as low-titer and ≥5 BU/mL as high-titer. Cumulative inhibitor incidence (primary endpoint) and 95% confidence intervals (CIs) were calculated (Kaplan-Meier). Efficacy endpoints (inhibitor-free periods) included the annualized bleeding rate (ABR) during prophylaxis and efficacy in treating BEs/surgical prophylaxis (4-point objective scales: excellent, good [successful]; moderate or none). Adverse events (AEs) were monitored throughout the study. Results Of 108 subjects consented, 105 PUPs, median age of 12 months (range 0-146) at ED1 were evaluable for inhibitor development. They were treated for a median of 101 EDs (range 1-1164), with 96 patients treated for ≥100 EDs (or until inhibitor development, including 5 patients with 97-99 EDs). The majority of patients with available genetic data had null F8 gene mutations (90/102 [88.2%]) and 13 (12.0%) had a family history of inhibitors. Cumulative inhibitor incidence was 17.6% (95% CI: 10.0%, 25.3%) for high-titre inhibitors and 27.9% (95% CI: 19.1%, 36.7%) for all inhibitors (Figure 1). No PUPs with non-null F8 mutations developed inhibitors. In 50 PUPs on continuous prophylaxis for ≥6 months, the mean (SD) ABR was 0.54 (1.07) [median 0] for spontaneous BEs and 3.61 (3.82) [median 2.53] for all BEs. The treatment of BEs was successful in 92.9% (747/804) of rated BEs in 85 patients with treated BEs and 91.9% of BEs were controlled with 1 or 2 infusions. Surgical prophylaxis was successful for 94.7% (18/19) of rated procedures and moderate for 5.3% (1/19). Excluding inhibitors, only one (0.9%) patient had an AE classified as serious by the investigator (hospitalization due to a mild rash that resolved with anti-histamine treatment). Conclusions Simoctocog alfa had a similar inhibitor incidence in PUPs with severe HA as pdFVIII/VWF products in SIPPET. No inhibitors occurred in PUPs with non-null F8 mutations. Simoctocog alfa had a median spontaneous ABR of 0 during prophylaxis and was successful in the treatment of 92.9% of BEs and in 94.7% of surgical procedures. These results complement results in previously treated patients (PTPs) and support the use of simoctocog alfa in the prevention and treatment of BEs in PUPs and PTPs. References Liesner R, et al. Haemophilia 2018; 24: 211-20. Disclosures Liesner: Octapharma, Bayer, Takeda, Novo Nordisk, CSL Behring, Roche: Research Funding; Octapharma, SOBI, Novo Nordisk: Speakers Bureau; Octapharma, Bayer, Takeda: Consultancy. Neufeld:Octapharma, Shire Pharmaceuticals (Baxalta), Novo Nordisk, Celgene, NHLBI/NIH: Research Funding; Octapharma, Agios, Acceleron, Grifols, Pfizer, CSL Behring, Shire Pharmaceuticals (Baxalta), Novo Nordisk, ApoPharma, Genentech, Novartis, Bayer Healthcare: Consultancy; Octapharma: Other: study investigator, NuProtect study (Octapharma-sponsored).

Proliferation, apoptosis, and number of Sertoli cells in the Syrian hamster during recrudescence after exposure to short photoperiod†‡.

The Sertoli cell (Sc) has been described as a quiescent cell once the animal has reached sexual maturity. Syrian hamster is an animal that displays testicular regression due to short photoperiod, during which process germ cells and Sc are removed through apoptosis. The aim of this work was to investigate histochemically whether the spontaneous testicular recrudescence processes after exposure to a short photoperiod lead to an increase in Sc proliferative activity in order to restore the normal population. Three spontaneous recrudescence groups were established: initial (IR), advanced (AR), and total (TR) recrudescence, which were compared with animal undergoing the regression process (mild: MRg, strong: SRg, and total: TRg) and animals in long photoperiod (Controls). Histological sections were submitted to histochemical techniques for detecting apoptotic and proliferative Sc with bright-field and fluorescence microscopy. For each group, the proliferative Sc index (PScI) and apoptotic Sc index (AScI), and the total number of Sc were obtained. The results revealed the existence of Vimentin+/TUNEL+ as well as Vimentin+/PCNA+ cells. The PScI was significantly higher in TRg and IR than in the other groups. The AScI was only significantly higher in MRg and SRg with respect to the other groups. The total number of Sc increased among TRg, IR, and AR, reaching values similar to those of the Controls. In conclusion, the increase in Sc proliferation from final regression and recrudescence, accompanied by a similar rate of apoptosis to the Control group, is the cause of the restoration of the Sc population during spontaneous recrudescence.

Demographic Approaches to the Study of Aging on Cell Cultures

Aging organisms die out in accordance with the “Gompertz law,” i.e., the probability of their death increases with age. Survival curve construction is the main tool for gerontologists to study aging and test antiaging drugs. The analysis of survival curves includes obtaining some indices characterizing aging of the population, for example, the average and maximum lifespan, the mortality rate, and the aging rate. Testing geroprotectors can be correctly performed only by obtaining such curves. The dying out of stationary cell populations—bacteria, yeast, and mammalian cell cultures—also occurs in accordance with the Gompertz equation. In this regard, it is reasonable to use the construction of survival curves and their analysis to study the “aging” of non-subcultured cell cultures and testing anti-aging drugs on them. We used this approach in our experiments, due to which we were able to detect the positive anti-aging effect of the Quinton Marine Plasma on stationary phase aging culture of Chinese hamster cells.

Rotavirus Species B Encodes a Functional Fusion-Associated Small Transmembrane Protein.

Rotavirus is an important cause of diarrheal disease in young mammals. Rotavirus species A (RVA) causes most human rotavirus diarrheal disease and primarily affects infants and young children. Rotavirus species B (RVB) has been associated with sporadic outbreaks of human adult diarrheal disease. RVA and RVB are predicted to encode mostly homologous proteins but differ significantly in the proteins encoded by the NSP1 gene. In the case of RVB, the NSP1 gene encodes two putative protein products of unknown function, NSP1-1 and NSP1-2. We demonstrate that human RVB NSP1-1 mediates syncytium formation in cultured human cells. Based on sequence alignment, NSP1-1 proteins from species B, G, and I contain features consistent with fusion-associated small transmembrane (FAST) proteins, which have previously been identified in other genera of the Reoviridae family. Like some other FAST proteins, RVB NSP1-1 is predicted to have an N-terminal myristoyl modification. Addition of an N-terminal FLAG peptide disrupts NSP1-1-mediated fusion. NSP1-1 from a human RVB mediates fusion of human cells but not hamster cells and, thus, may serve as a species tropism determinant. NSP1-1 also can enhance RVA replication in human cells, both in single-cycle infection studies and during a multicycle time course in the presence of fetal bovine serum, which inhibits rotavirus spread. These findings suggest potential yet untested roles for NSP1-1 in RVB species tropism, immune evasion, and pathogenesis.IMPORTANCE While species A rotavirus is commonly associated with diarrheal disease in young children, species B rotavirus has caused sporadic outbreaks of adult diarrheal disease. A major genetic difference between species A and B rotaviruses is the NSP1 gene, which encodes two proteins for species B rotavirus. We demonstrate that the smaller of these proteins, NSP1-1, can mediate fusion of cultured human cells. Comparison with viral proteins of similar function provides insight into NSP1-1 domain organization and fusion mechanism. These comparisons suggest that there is a fatty acid modification at the amino terminus of the protein, and our results show that an intact amino terminus is required for NSP1-1-mediated fusion. NSP1-1 from a human virus mediates fusion of human cells, but not hamster cells, and enhances species A rotavirus replication in culture. These findings suggest potential, but currently untested, roles for NSP1-1 in RVB host species tropism, immune evasion, and pathogenesis.

The H2S-Nrf2-Antioxidant Proteins Axis Protects Renal Tubular Epithelial Cells of the Native Hibernator Syrian Hamster from Reoxygenation-Induced Cell Death.

During hibernation, repeated cycles of ischemia-reperfusion (I-R) leave vital organs without injury. Studying this phenomenon may reveal pathways applicable to improving outcomes in I-R injury-induced human diseases. We evaluated whether the H2S–nuclear factor erythroid 2-like 2 (Nrf2)–antioxidant proteins axis protects renal proximal tubular epithelial cells (RPTECs) of the native hibernator, the Syrian hamster, from reperfusion-induced cell death. To imitate I-R, the hamsters’, and control mice’s RPTECs were subjected to warm anoxia, washed, and then subjected to reoxygenation in fresh culture medium. Whenever required, the H2S-producing enzymes inhibitor aminooxyacetate or the lipid peroxidation inhibitor α-tocopherol were used. A handmade H2S detection methylene blue assay, a reactive oxygen species (ROS) detection kit, a LDH release cytotoxicity assay kit, and western blotting were used. Reoxygenation upregulated the H2S-producing enzymes cystathionine beta-synthase, cystathionine γ-lyase, and 3-mercaptopyruvate sulfurtransferase in the hamster, but not in mouse RPTECs. As a result, H2S production increased only in the hamster RPTECs under reoxygenation conditions. Nrf2 expression followed the alterations of H2S production leading to an enhanced level of the antioxidant enzymes superoxide dismutase 3 and glutathione reductase, and anti-ferroptotic proteins ferritin H and cystine-glutamate antiporter. The upregulated antioxidant enzymes and anti-ferroptotic proteins controlled ROS production and rescued hamster RPTECs from reoxygenation-induced, lipid peroxidation-mediated cell death. In conclusion, in RPTECs of the native hibernator Syrian hamster, reoxygenation activates the H2S–Nrf2–antioxidant proteins axis, which rescues cells from reoxygenation-induced cell death. Further studies may reveal that the therapeutic activation of this axis in non-hibernating species, including humans, may be beneficial in I-R injury-induced diseases.

Characterization of a replication-competent vector encoding DsRed based on a human adenovirus type 4 a-like strain

Human adenovirus type 4 (HAdV4) is an etiological agent of acute respiratory disease (ARD) in pediatric and adult patients. HAdV4 strains can be divided into two major genomic clusters, namely prototype (p)-like viruses and a-like viruses. Here, the complete genome sequence of HAdV4 strain GZ01, isolated from a child with ARD in southern China, is first reported and analyzed. This strain was determined to be of the 4a1 genome-type based on in silico restriction profiles. Then, a replication-competent rAd4DsRed virus, containing the HAdV4 GZ01 infectious genome and expressing the reporter molecule DsRed, was generated and characterized. Recombinant rAd4DsRed can infect AD293, hamster, and mouse cells in which DsRed protein was expressed. No changes in antigenicity and genome replication were detected for rAd4DsRed and wild-type HAdV4. Mice immunized with rAd4DsRed was elicited a marked antibody response to DsRed. A rapid method of testing neutralizing antibodies against HAdV3 and HAdV4 was also established using a mixture of rAd4DsRed and rAd3EGFP. Our results provide the foundation to develop HAdV4 vaccines, potential vector platforms for vaccine and gene therapy, and rapid methods for serological and antiviral screening.

Studies into the Effect of “Mild” Uncoupling with 2,4-Dinitrophenol on the Growth of Chinese Hamster Cell Culture and Its Subsequent Dying out in the Stationary Phase

Partial uncoupling of the processes of oxidative phosphorylation and energy storage in the form of ATP (“mild” uncoupling) helps reduce the production of reactive oxygen species and can also mimic the effect of calorie restriction. A number of studies have shown that uncouplers, such as 2,4-dinitrophenol (DNP), affect the lifespan of Drosophila, yeast, mice, and rats as well as the manifestation of “age-related” changes in cultures of mammalian and human cells undergoing replicative senescence. This paper is devoted to studying the effect of DNP on the growth and subsequent dying out of “stationary phase aging” Chinese hamster cells. Using the method for evaluating the colony-forming efficiency of cells, the maximum permissible concentration was selected, 5 ×10–5 M, in which the substance presumably induces “mild” uncoupling and does not inhibit cell proliferation. At higher concentrations, DNP has a cytotoxic effect on the studied cell culture. Under the influence of DNP in the potentially “mild” uncoupling concentration (5.6 × 10–7 M), the kinetics of cell growth and dying out does not change, and the lifespan of the cell culture does not increase. This effect may be due to the type of cells studied. In addition, there is a probability that the optimal concentration lies in the range from 5 ×10–7 to 5 × 10–5 M or even lower than 5 × 10–7 M.

Error-prone replication of a 5-formylcytosine-mediated DNA-peptide cross-link in human cells

DNA-protein cross-links can interfere with chromatin architecture, block DNA replication and transcription, and interfere with DNA repair. Here we synthesized a DNA 23-mer containing a site-specific DNA-peptide cross-link (DpC) by cross-linking an 11-mer peptide to the DNA epigenetic mark 5-formylcytosine in synthetic DNA and used it to generate a DpC-containing plasmid construct. Upon replication of the DpC-containing plasmid in HEK 293T cells, approximately 9% of progeny plasmids contained targeted mutations and 5% semitargeted mutations. Targeted mutations included C→T transitions and C deletions, whereas semitargeted mutations included several base substitutions and deletions near the DpC lesion. To identify DNA polymerases involved in DpC bypass, we comparatively studied translesion synthesis (TLS) efficiency and mutagenesis of the DpC in a series of cell lines with TLS polymerase knockouts or knockdowns. Knockdown of either hPol ι or hPol ζ reduced the mutation frequency by nearly 50%. However, the most significant reduction in mutation frequency (50%-70%) was observed upon simultaneous knockout of hPol η and hPol κ with knockdown of hPol ζ, suggesting that these TLS polymerases play a critical role in error-prone DpC bypass. Because TLS efficiency of the DpC construct was not significantly affected in TLS polymerase-deficient cells, we examined a possible role of replicative DNA polymerases in their bypass and determined that hPol δ and hPol ϵ can accurately bypass the DpC. We conclude that both replicative and TLS polymerases can bypass this DpC lesion in human cells but that mutations are induced mainly by TLS polymerases.

Expression of the genes encoding bovine LH in a line of Chinese hamster ovary cells

Summary. Synthesis of biologically active LH is complex, due in part to its hetero-dimeric subunit structure and to the numerous post-translation modifications of each subunit. Through the use of mammalian expression vectors we have been able to introduce the bovine α subunit and LH-β genes into a Chinese hamster ovary cell line deficient in dihydrofolate reductase. The bovine genes are actively expressed and the Chinese hamster ovary cells secrete biologically active LH. The expression vector containing the bovine α subunit gene also contains a modified mouse gene encoding dihydrofolate reductase, permitting the use of methotrexate to amplify selectively the bovine α subunit gene after its integration into the genome of the Chinese hamster cells. This provides a novel means for assessing the importance of α subunit concentration with respect to assembly of the heterodimer. In addition, methotrexate selection leads to the over-production of LH (10 µg/106 cells/24 h). Finally, because the bovine LH produced in the Chinese hamster ovary cells is glycosylated, this transfection system can be used in conjunction with in-vitro mutagenesis to determine whether site-specific changes in glycosylation have an effect on subunit assembly and biological activity. This transfection approach therefore offers multiple avenues to explore further the molecular mechanisms underlying the complex biosynthetic pathway of bovine LH.

Genotoxicity evaluation of tobacco and nicotine delivery products: Part Two. In vitro micronucleus assay

In this study, a variety of test matrices from tobacco and nicotine delivery products were assessed against a 3R4F Kentucky reference cigarette using the in vitro micronucleus assay. Testing was conducted using two Chinese hamster cell lines (CHO and V79), and a human lymphoblastoid cell line (TK6), in accordance with established guidelines.Total particulate matter (TPM) from a 3R4F Reference cigarette was compared to an electronic cigarette e-liquid, electronic cigarette TPM and TPM from a commercial tobacco heating product using a standard and an extended treatment condition with recovery period.Cells were assessed with 3R4F TPM prior to assessment of the other tobacco and nicotine product test matrices. These cell lines gave varied responses to 3R4F TPM with the most robust response using V79 cells. The use of an extended exposure/recovery period was seen to increase assay sensitivity for CHO and V79 cell lines but was less clear for TK6 cells.Negative responses were observed for all products except 3R4F across all treatment conditions in V79 cells. The most potent response to cigarette smoke was following extended treatment with recovery, suggesting this may be a more appropriate treatment for the future assessment of tobacco and nicotine product test matrices.

Identification of CP77 as the Third Orthopoxvirus SAMD9 and SAMD9L Inhibitor with Unique Specificity for a Rodent SAMD9L.

Orthopoxviruses (OPXVs) have a broad host range in mammalian cells, but Chinese hamster ovary (CHO) cells are nonpermissive for vaccinia virus (VACV). Here, we revealed a species-specific difference in host restriction factor SAMD9L as the cause for the restriction and identified orthopoxvirus CP77 as a unique inhibitor capable of antagonizing Chinese hamster SAMD9L (chSAMD9L). Two known VACV inhibitors of SAMD9 and SAMD9L (SAMD9&L), K1 and C7, can bind human and mouse SAMD9&L, but neither can bind chSAMD9L. Clustered regularly interspaced short palindromic repeat (CRISPR)-Cas9 knockout of chSAMD9L from CHO cells removed the restriction for VACV, while ectopic expression of chSAMD9L imposed the restriction for VACV in a human cell line, demonstrating that chSAMD9L is a potent restriction factor for VACV. In contrast to K1 and C7, cowpox virus CP77 can bind chSAMD9L and rescue VACV replication in cells expressing chSAMD9L, indicating that CP77 is yet another SAMD9L inhibitor but has a unique specificity for chSAMD9L. Binding studies showed that the N-terminal 382 amino acids of CP77 were sufficient for binding chSAMD9L and that both K1 and CP77 target a common internal region of SAMD9L. Growth studies with nearly all OPXV species showed that the ability of OPXVs to antagonize chSAMD9L correlates with CP77 gene status and that a functional CP77 ortholog was maintained in many OPXVs, including monkeypox virus. Our data suggest that a species-specific difference in rodent SAMD9L poses a barrier for cross-species OPXV infection and that OPXVs have evolved three SAMD9&L inhibitors with different specificities to overcome this barrier.IMPORTANCE Several OPXV species, including monkeypox virus and cowpox virus, cause zoonotic infection in humans. They are believed to use wild rodents as the reservoir or intermediate hosts, but the host or viral factors that are important for OPXV host range in rodents are unknown. Here, we showed that the abortive replication of several OPXV species in a Chinese hamster cell line was caused by a species-specific difference in the host antiviral factor SAMD9L, suggesting that SAMD9L divergence in different rodent species poses a barrier for cross-species OPXV infection. While the Chinese hamster SAMD9L could not be inhibited by two previously identified OPXV inhibitors of human and mouse SAMD9&L, it can be inhibited by cowpox virus CP77, indicating that OPXVs encode three SAMD9&L inhibitors with different specificities. Our data suggest that OPXV host range in broad rodent species depends on three SAMD9&L inhibitors with different specificities.