Effects of ethylene oxide and ethylene inhalation on DNA adducts, apurinic/apyrimidinic sites and expression of base excision DNA repair genes in rat brain, spleen, and liver

Ethylene oxide (EO) is an important industrial chemical that is classified as a known human carcinogen (IARC, Group 1). It is also a metabolite of ethylene (ET), a compound that is ubiquitous in the environment and is the most used petrochemical. ET has not produced evidence of cancer in laboratory animals and is "not classifiable as to its carcinogenicity to humans" (IARC, Group 3). The mechanism of carcinogenicity of EO is not well characterized, but is thought to involve the formation of DNA adducts. EO is mutagenic in a variety of in vitro and in vivo systems, whereas ET is not. Apurinic/apyrimidinic sites (AP) that result from chemical or glycosylase-mediated depurination of EO-induced DNA adducts could be an additional mechanism leading to mutations and chromosomal aberrations. This study tested the hypothesis that EO exposure results in the accumulation of AP sites and induces changes in expression of genes for base excision DNA repair (BER). Male Fisher 344 rats were exposed to EO (100 ppm) or ET (40 or 3000 ppm) by inhalation for 1, 3 or 20 days (6h/day, 5 days a week). Animals were sacrificed 2h after exposure for 1, 3 or 20 days as well as 6, 24 and 72 h after a single-day exposure. Experiments were performed with tissues from brain and spleen, target sites for EO-induced carcinogenesis, and liver, a non-target organ. Exposure to EO resulted in time-dependent increases in N7-(2-hydroxyethyl)guanine (7-HEG) in brain, spleen, and liver and N7-(2-hydroxyethyl)valine (7-HEVal) in globin. Ethylene exposure also induced 7-HEG and 7-HEVal, but the numbers of adducts were much lower. No increase in the number of aldehydic DNA lesions, an indicator of AP sites, was detected in any of the tissues between controls and EO-, or ET-exposed animals, regardless of the duration or strength of exposure. EO exposure led to a 3-7-fold decrease in expression of 3-methyladenine-DNA glycosylase (Mpg) in brain and spleen in rats exposed to EO for 1 day. Expression of 8-oxoguanine DNA glycosylase, Mpg, AP endonuclease (Ape), polymerase beta (Pol beta) and alkylguanine methyltransferase were increased by 20-100% in livers of rats exposed to EO for 20 days. The only effects of ET on BER gene expression were observed in brain, where Ape and Pol beta expression were increased by less than 20% after 20 days of exposure to 3000 ppm. These data suggest that DNA damage induced by exposure to EO is repaired without accumulation of AP sites and is associated with biologically insignificant changes in BER gene expression in target organs. We conclude that accumulation of AP sites is not a likely primary mechanism for mutagenicity and carcinogenicity of EO.     

Systemic and Mucosal Immune Reactivity upon Mycobacterium avium ssp. paratuberculosis Infection in Mice

Mycobacterium avium ssp. paratuberculosis (MAP) is the cause of Johne''s disease, an inflammatory bowel disorder of ruminants. Due to the similar pathology, MAP was also suggested to cause Crohn''s disease (CD). Despite of intensive research, this question is still not settled, possibly due to the lack of versatile mouse models. The aim of this study was to identify basic immunologic mechanisms in response to MAP infection. Immune compromised C57BL/6 Rag2 ^−/− mice were infected with MAP intraperitoneally. Such chronically infected mice were then reconstituted with CD4⁺ and CD8⁺ T cells 28 days after infection. A systemic inflammatory response, detected as enlargement of the spleen and granuloma formation in the liver, was observed in mice infected and reconstituted with CD4⁺ T cells. Whereby inflammation in infected and CD4⁺CD45RB^hi T cell reconstituted animals was always higher than in the other groups. Reconstitution of infected animals with CD8⁺ T cells did not result in any inflammatory signs. Interestingly, various markers of inflammation were strongly up-regulated in the colon of infected mice reconstituted with CD4⁺CD45RB^lo/int T cells. We propose, the usual non-colitogenic CD4⁺CD45RB^lo/int T cells were converted into inflammatory T cells by the interaction with MAP. However, the power of such cells might be not sufficient for a fully established inflammatory response in the colon. Nevertheless, our model system appears to mirror aspects of an inflammatory bowel disease (IBD) like CD and Johne''s diseases. Thus, it will provide an experimental platform on which further knowledge on IBD and the involvement of MAP in the induction of CD could be acquired.     

Long COVID and its Management

The pandemic of COVID-19 is the biggest public health crisis in 21^st Century. Besides the acute symptoms after infection, patients and society are also being challenged by the long-term health complications associated with COVID-19, commonly known as long COVID. While health professionals work hard to find proper treatments, large amount of knowledge has been accumulated in recent years. In order to deal with long COVID efficiently, it is important for people to keep up with current progresses and take proactive actions on long COVID. For this purpose, this review will first introduce the general background of long COVID, and then discuss its risk factors, diagnostic indicators and management strategies. This review will serve as a useful resource for people to understand and prepare for long COVID that will be with us in the foreseeable future.     

Comparsion ofin vitro activities of antifungal drugs and propolis against yeasts isolated from patients with superficial mycoses

Thein vitro susceptibilities of propolis and antifungal drugs were determined against some yeasts isolated from patients with superficial mycoses. The agents tested included fluconazole, itraconazole, ketoconazole, terbinafine and propolis. MICs were determined by the broth microdilution technique following National Committee for Clinical Laboratory Standards document M27-P. For allCandida albicans isolates from the patients with superficial mycoses, ketoconazole presented higher (P<0.05) efficiency than that of the other antifungal agents tested. The geometric mean MIC values of antifungal drugs and propolis against the yeasts tested ranged from 0.087 to 12.69 μg/mL and 0.4–0.6 μg/mL, respectively. Propolis also showed an important antifungal activity against the yeasts tested, MIC ranges of the propolis were between 0.01–1.65 μg/mL. Based on these results, propolis requires further investigation as a potential agent for the treatment of superficial mycoses.     

Dietary selenium- and vitamin E-induced alterations in some rabbit tissues

The present study was designed to investigate and compare the effects of dietary selenium (Se) and vitamin E on some physiological parameters and histological changes in liver, heart, and skin tissues, as well as the blood parameters and the related enzymes. Both sex young rabbits were fed with deficient (9.8 μg/kg diet), adequate (225 μg/kg diet), and rich (4.2 mg/kg diet) Se and vitamin E diets for 12–15 wk for this purpose. As the plasma Se levels and the erythrocyte glutathione (GSH) peroxidase activity decreased (79.8±9.4 ng/ml and 2.0±0.3 U/g Hb, respectively) in the deficient group, these values increased (100.4±2.7 ng/mL and 14.5±4.3 U/g Hb) in the rich group significantly with respect to the control group. The other antioxidant enzyme activities and the related element levels did not change significantly in either one of the experimental groups. Although the platelet counts of the two experimental groups were not different from the control values, the collagen and the adenosine diphosphate (ADP) stimulated platelet aggregation rate and intensity increased in the deficient group (p<0.05) and decreased very significantly (p<0.001) in the rich group. In both of the experimental groups, as the percentage values of the neutrophils decreased, the lymphocytes and the eosinophils increased significantly. According to the light microscopic investigations, the observed lesions of considerable intensity within the tissues that elicit cell degenerations were more pronounced in the animals fed with the rich diet than in those fed with the deficient diet. The deficiency as well as toxicity of Se and the deficiency of vitamin E caused several alterations in the physiological functions of the tissues, and these alterations were supported by the histological lesions within these tissues.     

Specific binding of a Pop6/Pop7 heterodimer to the P3 stem of the yeast RNase MRP and RNase P RNAs

Pop6 and Pop7 are protein subunits of Saccharomyces cerevisiae RNase MRP and RNase P. Here we show that bacterially expressed Pop6 and Pop7 form a soluble heterodimer that binds the RNA components of both RNase MRP and RNase P. Footprint analysis of the interaction between the Pop6/7 heterodimer and the RNase MRP RNA, combined with gel mobility assays, demonstrates that the Pop6/7 complex binds to a conserved region of the P3 domain. Binding of these proteins to the MRP RNA leads to local rearrangement in the structure of the P3 loop and suggests that direct interaction of the Pop6/7 complex with the P3 domain of the RNA components of RNases MRP and P may mediate binding of other protein components. These results suggest a role for a key element in the RNase MRP and RNase P RNAs in protein binding, and demonstrate the feasibility of directly studying RNA-protein interactions in the eukaryotic RNases MRP and P complexes.     

Comparative study of in vitro methods to analyse the antifungal activity of propolis against yeasts isolated from patients with superficial mycoses

AIM: To test a total of 15 strains belonging to four species of yeasts by different in vitro methods against propolis and itraconazole (ITC). METHODS AND RESULTS: Three methods were compared for susceptibility testing of yeast isolates to propolis: disc diffusion method, agar dilution method and National Committee for Clinical Laboratory Standards (NCCLS, M27A) broth microdilution method. ITC was selected as the antifungal agent for comparison study. Using the broth microdilution method, the geometric mean for MIC (microg ml(-1)) with regard to all isolates was < or =0.06 for propolis and < or =0.35 for ITC. The broth microdilution and the agar dilution methods were in good agreement (75%) for propolis against yeasts isolated from patients with superficial mycoses. Using the diffusion method, all strains showed a broad zone of inhibition at the first available reading time (24 or 48 h). An increase of MIC values was accompanied by a decrease of growth inhibition zone diameter. A favourable correlation was found between MIC and inhibition zone around the disc for propolis sample and the correlation coefficient was: r = -0.626 (P < 0.01). CONCLUSIONS: This study suggests the potential value of the agar dilution and disc diffusion method as a convenient alternative method for testing of yeasts to propolis. SIGNIFICANCE AND IMPACT OF THE STUDY: This study demonstrated that propolis and ITC were very active against yeasts from patients with superficial mycoses. The other prominent finding in this study is that RPMI 1640 with L-glutamine was the available broth for the in vitro susceptibility testing of yeasts.     

Ultrasonic monitoring of glycerol settling during transesterification of soybean oil

A low-intensity ultrasonic measurement system was used to monitor the products of transesterification of soybean oil in methanol to FAME (biodiesel). The byproducts of the transesterification reaction are methyl esters, glycerol and other products. During the transesterification reaction, the glycerol, having a higher density than the methyl ester, settles at the bottom of the reaction vessel. The aim of this study was to measure the glycerol deposition rate during transesterification and to assess the reaction rate and end time. Soybean oil was converted into biodiesel at four temperature levels. The amount of catalyst (KOH) used in the transesterification reactions was determined by titration. The ultrasonic waveforms captured during the reaction were recorded and analyzed automatically. The ultrasonic system monitored the effects of reaction temperatures on the glycerol settling rate and the reaction end times. The ultrasonic measurement of glycerol settling would be a useful non-destructive method for evaluating the effects of parameters such as catalyst amount, mixing time and temperature on transesterification reactions.